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2017

[69]  Singh, A., Auzanneau F.-I., Coradini, M.G., Grover, G., Weiss, R.G., Rogers, M.A.face 2017. Molecular Nuances Governing the Self-Assembly of 1,3:2,4-Dibenzylidene-D-Sorbitol. Langmuir. 33, 10907-10916.


1,3:2,4 Dibenzylidene-D-sorbitol (DBS) is the gold-standard for low-molecular-weight organogelators (LMOGs). DBS gels a wide array of solvents, as illustrated by the large Hansen sphere representing gels (2dd = 33.5, dp = 7.5, and dh = 8.7 MPa1/2; radius = 11.2 MPa1/2). Derivatives of DBS have been synthesised to isolate and determine molecular features essential for organogelation. Herein, π-π stacking and hydrogen-bonding are the major non-covalent interactions examined. The importance of π-π stacking was studied using 1,3:2,4 dicyclohexanecarboxylidene-D-sorbitol (DCHS), which eliminates possible π-π stacking, while still conserving the other structural aspects of DBS. The replacement of the benzyl groups with cyclohexyl groups led to a very a poor gelator; only one of the several solvents examined, carbon tetrachloride, formed a gel. 1,3:2,4 diethylidene-D-sorbitol (DES), another DBS analogue incapable of π-π stacking however now with very different polarity, gelated a large Hansen space (2dd = 34.0, dp = 10.9, and dh = 10.8 MPa1/2; Radius = 9.2 MPa1/2). DES gels solvents with higher dp and dh than DBS. To assess the role of hydrogen bonding, DBS was acetalated (A-DBS) and it was found that the Hansen space gelated by A-DBS shiftes to less polar solvents with higher hydrogen-bonding Hansen solubility parameters (HSPs) (2dd = 33.8, dp = 6.3, and dh = 9.6 MPa1/2; Radius = 11.1 MPa1/2) than DBS. These systematic structural modifications are the first step in exploring how specific intermolecular features alter aspects of Hansen space corresponding to positive gelation outcomes.


[68] Jensen, D.A., Rogers, M.A. & Schaffner, D.W.  2017.  . Surfactant Concentration and Type Affects the Removal of Escherichia coli from Pig Skin During a Simulated Handwash. Letters in Applied Microbiology.  65, 292-297.


The effect of surfactant type and concentration on a bland soap formulations ability to remove bacteria from hands remains largely unstudied. Several combinations of surfactants and water were combined to test bacterial removal efficacy using a  handwashing device (two pieces of pig skin and a mechanical motor) to simulate a handwash. A nalidixic acid resistant, non-pathogenic strain of Escherichia coli (ATCC11229) was used. Two anionic surfactants, sodium lauryl sulfate and sodium stearoyl lactylate, and two nonionic surfactants, poloxamer 407 and sorbitan monostearate, each in concentrations of 2%, 5%, and 10% were studied. A slight  positive (r2=0.17) but significant (p=0.03) correlation was observed between hydrophile-lipophile balance value and mean log reduction. No correlation was observed between pH of the treatment solution and the mean log reduction (r2=0.05, p=0.25). A 10% sodium lauryl sulfate mixture showed the highest log reduction (x̄= 1.1 log cfu reduction, SD=0.54), and was the only treatment significantly different from washing with water (p=0.0005). There was a correlation between increasing surfactant concentrations above the critical micelle concentration, and mean microbial reduction (r2=0.62, p=0.001).


[67] Singh, A., Auzanneau, F.-I., Rogers, M.A. 2017. Advances in Edible Oleogel Technologies - A Decade in Review.  Food Research International.  97, 307-317.


Trans and saturated fat replacers/substitutes have been a tremendously active area of research for the food industry. Unlike polymers used for hydrogels, oleogels utilize small, amphiphilic molecules that self-assemble via highly specific, non-covalent interactions entrapping liquid oil via capillary forces. Edible applications of oleogels have replaced the need for trans unsaturated and saturated fatty acids to structure processed foods. These innovations mitigate the use of hardstock fats that are associated with deleterious health risks and negative consumer perception. Over the past decade, oleogels have made significant strides towards emulating desired sensory traits while maintaining healthy nutritional profile of the oil. Due to the rapid advancements in the past decade, the most promising technologies will be reviewed.


[65]  Alhassawi, F.M., Corradini, M.G., Rogers, M.A., Ludescher, R.D.* 2017. Potential Application of Luminescent Molecular Rotors in Food Research. Critical Reviews in Food Science & Nutrition. DOI: 10.1080/10408398.2017.127858.


Fluorescent molecular rotors are compounds whose emission is modulated by segmental mobility; photoexcitation generates a locally excited (LE), planar state that can relax either by radiative decay (emission of a photon) or by formation of a twisted intramolecular charge transfer (TICT) state that can relax non-radiatively due to internal rotation. If the local environment around the probe allows for rapid internal rotation in the excited state, fast non- radiative decay can either effectively quench the fluorescence or generate a second, red-shifted emission band. Conversely, any environmental restriction to twisting in the excited state due to free volume, crowding or viscosity, slows rotational relaxation and promotes fluorescence emission from the LE state. The environmental sensitivity of molecular rotors has been exploited extensively in biological applications to sense microviscosity in biofluids, the stability and physical state of biomembranes, and conformational changes in macromolecules. The application of molecular rotors in food research, however, has been only marginally explored. In this review, we summarize the main characteristics of fluorescent molecular rotors, their current applications in biological research and their current and potential applications as sensors of physical properties in food science and engineering.


[66] Alhassawi, F.M., Fondaco, D., Ben-Elazar, K., Ben-Elazar, S., Yim Yan Fan, Corradini, M.G., Ludescher, R.D., Bolster, D., Chu, Y., Johnson, J., Rogers, M.A.* 2017. In vitro Measurements of Luminal Viscosity and Glucose/Maltose Bioaccessibility for Oat Bran, Instant Oats, and Steel Cut Oats. Food Hydrocolloids. 70, 293-303.


Three commercially available oat products—instant oats, steel cut oats, and oat bran—were studied using the TNO Intestinal Model-1 (TIM-1) coupled with fluorescence spectroscopy and molecular rotors to evaluate carbohydrate digestion and in vitro gastric viscosity as a function of time. A proportional relationship between total bioaccessible sugars and the concentration of available carbohydrates was observed for the different oat-based foods. The rate of starch digestion was greatest for instant oats and lowest for steel cut oats. β-glucan, starch, and total carbohydrate concentrations were proportional to the initial gastric viscosity. Overall, gastric viscosity differed considerably between samples. Instant oat and oat bran viscosities were highest at the onset of digestion and decreased with time, whereas the viscosity of steel cut oats at the onset of digestion was the lowest viscosity observed, increasing with time. These findings suggest that modification of food form and formulation during processing alters sugar bioaccessibility and luminal viscosity.


[64] Rogers, M.A.,* Corradini, M.G., Emge T.A.  2017. Solvent Induced Supramolecular Anisotropy in Molecular Gels. Materials Chemistry and Physics. 194, 224-230.


Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels.

2016

[63] Rogers, M.A.,* Marangoni. A.G., 2016. Kinetics of 12-Hydroxyoctadecanoic Acid SAFiN Crystallization Rationalized using Hansen Solubility Parameters. Langmuir. 32, 12833-12841.


Changes in solvent chemistry influenced kinetics of both nucleation and crystallization of 12-hydroxyoctadecenoic, as determined using differential scanning calorimetry and applying a modified Avrami model to the calorimetric data. Altering solvent properties influenced solvent-gelator compatibility, which in turn altered the chemical potential of the system at the onset of crystallization, the kinetics of gelation, and the resulting 12HOA crystal fiber length. The chemical potential at the onset of crystallization was linearly correlated to both the hydrogen-bonding Hansen solubility parameter and the solvent-gelator vectorial distance in Hansen space, Ra. Our work suggests that solvent properties can be modulated to affect the solubility of 12HOA, which in turn influences the kinetics of crystallization and the self-assembly of this organogelator into supramolecular crystalline structures. Therefore, modulation of solvent properties during organogelation can be used to control fiber length, and thus engineer the physical properties of the gel.


[62] Corradini, M.G.,* Rogers, M.A. 2016. Molecular Gels: Improving Selection and Design Through Computational Methods. Current Opinion in Food Science. 9, 84-92.


The supramolecular self-assembly of low molecular weight gelators (LMWGs) enables the formation and development of novel soft materials, sensors and smart delivery systems potentially useful in the food industry. Identification of effective LMWGs for food applications usually involves extensive, laborious, and time-consuming screening of gelator/ solvent combinations. The advancement of computational tools can reduce screening time, speed up the discovery of appropriate edible, nontoxic gelators for food applications and shed light on solvent-gelator interactions. The state of the art on computational techniques developed to advance the understanding selection and rational design of LMWGs are discussed herein.


[61]  Rogers, M.A., Spagnuolo, P.A. 2016. A Potential Anti-Cancer Hard-Stock Fat Replacer. Food Science & Nutrition, DOI: 10.1002/fsn3.433.


Short chain ceramides, such as N-Acetoyl-D-erythro-sphingosine (C2) have a remarkable ability to structure edible oils, such as canola oil, into self-standing organogels without any added saturated or trans fats. These short chain ceramides are ubiquitously found in foods ranging from eggs to soybeans. As the ceramide fatty acid chain length increases, there is an increase in the melting temperature of the organogel and a decrease in the elastic modulus. Gelation ability is lost at 2 wt% when the fatty acid chain length increases to 6 carbons; however, organogels form at 5 wt% up to 18 carbons. Short chain ceramides, C2, decrease cell viability of colon, prostate, ovarian and leukemia cell lines; while ceramides with long chain fatty acids, C18, do not effect the viability of these cancer cell lines. This suggests that a bioactive spreadable fat, with no trans or added saturated fat, with the potential to alter the viability of cancer cell growth, is possible.


[60] De La Peña-Gil, A., Toro-Vazquez, J.F., Rogers, M.A.,  2016. Simplifying Hansen Solubility Parameters for Complex Edible Fats and Oils.  Food Biophysics.  11, 283-291.


Hansen solubility parameters (HSPs), often used to predict the miscibility between two compounds, are an alternative tool in evaluating the ability of the solvent to interact via dispersion, dipole-dipole, and hydrogen bonding interactions. The aim of this paper is to find a simple way to calculate HSPs for complex mixtures of triglycerides (TAGs). HSPs were calculated using two approaches: the first assumes that the contributions to the dispersion, dipole-dipole, and hydrogen bonding interactions may be subdivided into larger functional moieties (i.e., fatty acids and fatty acid methyl esters) that are additive, while the second approach assumes that vegetable oils are comprised of mixtures of simple TAGs in the same mass fractions as the fatty acids. The HSPs obtained using the two approaches are compared to reference values determined using the "Hansen Solubility Parameters in Practice" software (HSPiP) considering the complex TAG profile for each vegetable oil.

HSPs for vegetable oils, obtained with the HSPiP software, did not correspond well to the HSPs obtained from the group contribution approach, when using fatty acids, fatty acids + glycerol or fatty acid methyl esters. In contrast, the HSPs calculated for vegetable oils, assuming that all TAGs are simple and in the same mass fractions as the fatty acids, provide similar values to the HSPs obtained from the HSPiP software. Therefore, it is possible to calculate the HSPs for complex oils by simply knowing the fatty acid composition. Knowledge of HSPs may be used to rationalize the ability of certain low molecular weight molecules to develop organogels in vegetable oils as well as the crystallization of triglycerides.


[59] Rogers, M.A., Feng, Q., Ladizhansky, V., Good, D., Grahame, D.A.S., Bryksa, B.C., Smith, S.A., Corridini, M, Lim, L.-T., Guild, B., Burnet, P.-G., Shim, Y.Y., Reaney, M.J.T. 2016. Self-Assembled Supramolecular Fibrillar Networks Comprised of a Cyclic Peptide--LOB3. RCS Advances.  6, 40765-40776.


To the best of our knowledge, this is the first report of a self-assembling orbitide that is capable of forming 1D nano-fibers and ultimately 3D molecular gel networks. LOB3 (a.k.a. cyclolinopeptide A), extracted from Linum usitatissimum L. (flaxseed), forms molecular gels in acetonitrile. LOB3 molecular gels, illustrate that cyclic peptides may be comprised of more complex amino acid sequences than have been currently reported. It appears that cyclization, to form orbitides, imparts conformational aspects to the molecule facilitating self-organization into crystalline nano-fibers. These nanoscale fibers, ~ 300 nm in diameter and >100 mm in length, aggregate into bundles of fibers which may exceed micron dimensions. Within the nano-fibers, the orbitides adapt an antiparallel b-sheet-like conformation with high molecular periodicity, as illustrated by CD and XRD.


[58] Thilakarathna, S., Rogers, M.A., Huynh, S., Lan, Y., Marangoni, A., Robinson, L., Wright, A.J. 2016. Investigations of in vitro bioaccessibility from interesterified stearic acid-rich blends.  Food & Function.  7, 1932-1940.


Interesterification impacts stearic acid (SA) absorption when human volunteers consumed a 70:30 wt% high-oleic sunflower and canola stearin blend (NIE) compared to the same blend which had undergone either chemical (CIE) and enzymatic (EIE) interesterified (IE). In this study, in vitro lipid digestion, bioaccessibility, and changes in undigested lipid composition and melting behavior were compared using the TIM-1. Overall, bioaccessibility was higher with interesterification (p<0.05). Oleic acid bioaccessibility was also higher than SA bioaccessibility for NIE, and vice versa for the IE blends (p<0.05). SA was more concentrated in the undigested triacylglycerols (TAG) from NIE, corresponding to a relatively higher melting temperature of the undigested lipids. The results suggest the impact of TAG composition, fatty acid position and/or physical properties on lipid digestion. Bioaccessibility, assessed from the TIM-1, was linearly correlated (R2=0.8640) with postprandial serum TAG concentration in the human study. Lipolysis of NIE, CIE, and EIE was also investigated using a static batch gastro-duodenal digestion model. Similar non-linear relationships were observed with both the TIM-1 in vitro and in vivo human studies results (R2=0.7996 and 0.7275, respectively; p<0.05). Therefore, the in vitro digestion models offered predictive insights related to the impacts of lipid interesterificaton on absorption, with the TIM-1 out performing the static batch model.

[57] Rogers, M.A., 2016.  Naturally Occurring Nanoparticles in Food.  Current Opinion in Food Science. 7, 14-19.



Food nanotechnology is extremely complex and with hesitant consumers this may be sufficient to impede this technology from being implemented and benefits realized. Nano-sized particles are not new to our food supply and there are numerous naturally occurring nano-sized elements present in the foods we consume, including foods as wholesome as milk. Furthermore, nanoparticles arise as a result of processing, such as homogenization and milling and in complex foods, there also exists the possibility that certain combinations of ingredient spontaneously self-assemble into nano-fibers and micelles. During digestion, nanofabrication is used to aid in transport of lipids due to the micellization of fatty acids and monoglycerides with bile salts, phospholipids and cholesterol. It is imperative to advance the science of nanomaterials with the technology, and to be intimately aware that our biology is not experiencing for the first time nanomaterials.


2015

[56] Spagnuolo, P.A., & Rogers, M.A., Food as a Drug. 2015 Oncoscience.  2, 801-802.


In his Pulitzer Prize winning novel “The Emperor of all Maladies”, Dr. Siddhartha Mukherjee eloquently summarizes the history of rational drug design and its origins in understanding the impact of a food- derived bioactive compound (i.e., folic acid) in disease pathophysiology. Dr. Mukherjee reminds us that Sidney Farber’s 1948 seminal paper[1] in the New England Journal of Medicine set the framework for rational drug design. After observing that administration of folic acid in children with acute lymphoblastic leukemia (ALL) accelerated their disease, Farber and colleagues (notably Subbarao) developed anti-folate compounds to treat ALL. These drugs, aminopterin and later methotrexate, which is still used to this day as a cornerstone of several chemotherapy regimens, revolutionized cancer chemotherapy. In the 1980s, studies revealed that supplementation with all-trans retinoic acid (ATRA), a vitamin A derivative, forced differentiation of HL60 cells in culture. Later it was provided to a female patient with acute promyelocytic leukemia (APML) and she miraculously responded. She is alive and well today[2] and ATRA remains a cornerstone of APML therapy.


[55] Wang, T.M. and Rogers, M.A. 2015. Biomimicry – An Approach to Engineering Oils into Solid Fats.  Lipid Technology. 27, 1-4.


The ability to eliminate trans fats, without incorporating additional saturated fats, is limited by the physico-chemical properties of the processed food and what role the lipids play in the food structure. To maintain the levels of cardio-protective unsaturated fats alternative methods to structure them are desperately needed. One such strategy is to utilize oleogels or molecular gels comprised of small molecules. Herein, we illustrate the potential of biomimicking the assemblies formed by the intercellular lipids in stratum corneum using stearic acid, ceramide III and replacing cholesterol with b-sitosterol.


[54] Rogers, M.A. 2015. Innovations in Food Science: From Bioactives to Whole Foods. Current Opinion in Food Science. 4, 139-140.


Innovations in food science are occurring at such a rapid pace that they have and continue to transform our food supply. However, with these technological advances we must approach with extreme caution to ensure that the science keeps breadth with the technology. Food scientists and their industries have had negative impacts on their consumers with such advents of trans fats and carcinogenic by-products of maillard reaction and as such there is often distrust by consumers and media that impede new technologies, with potentially extremely beneficial health consequence, from reaching the market place. It is imperative to note that along with our blunders, food scientists are responsible for our affordable, diverse and safe food supply, which is often taken for granted.

[53] Rogers, M.A., Liu, X., Mallia, V.A., Weiss, R.G. 2015. Dissecting Kinetic Pathways to Formation of the Fibrillar Objects in Molecular Gels Using Synchrotron FT-IR. CrystEngComm. Supramolecular gels themed issue. 17, 8085-8092


Sols to gels transition is often difficult to study due to short time frame of pseudo-crystallization making it difficult to view in real time. The use of fast infrared spectroscopic methods, allow changes in the environments of individual functional groups as gelator molecules aggregate and form SAFiNs, is an ideal method to elucidate the behavior during the transition. By examining the kinetics of aggregation of a homologous series of amides structurally related to (R)-12-hydroxy-N-propyloctadecanamide (1) and (R)-12-hydroxyoctadecanamide insights are garnered into why very small structural modifications result in complete loss of gelation ability. The observations demonstrate the utility of fast infrared spectroscopy as a valuable new tool to delve into the detailed mechanisms of self-assembly. Perhaps more importantly, this technique is amenable to use with a wide range of other gelator systems. Finally, by understanding the activation energies as a function of molecular structure, we may be able to tailor the gelation ability of new classes of poorly understood gelators.

[52]  Ting,Y., Jiang,Y., Lan, Y., Xia, C., Lin, Z., Rogers, M.A., and Huang, Q.* 2015. Viscoelastic emulsion improved the bioaccessibility and oral bioavailability of crystalline compound: A mechanistic study using in vitro and in vivo models.  Molecular Pharmaceutics.  12, 2229-2236.


Tangeretin (5,6,7,8,4′-pentamethoxyflavone), a polymethoxylated flavonone found

predominantly in citrus fruit peels, has numerous bioactivities including anti-inflammation, anticancer and anti-obesity etc. Due to its hydrophobicity, tangeretin exhibits poor oral bioavailability. In the present study, an optimized viscoelastic emulsion system was formulated for tangeretin oral delivery, and different in vitro and in vivo models have been developed to investigate the effect of emulsification on the digestion and absorption of tangeretin.

[51]  Lan, Y., and Rogers, M.A. 12-Hydroxystearic Acid SAFiNs in Aliphatic Diols– A Molecular Oddity.  CrystEngComm. Supramolecular gels themed issue.  DOI: 10.1039/C5CE00652J.


12-Hydroxystearic acid (12-HSA), a structurally simple and cost-effective low molecular weight organogelator, has been studied extensively. It is established that the primary intermolecular interaction for self-assembly of 12-HSA molecular gels is hydrogen bonding and to a lesser extent van der Waals interactions. Due to the solvent-gelator interplay, it is expected that more polar solvents, especially hydrogen-bonding rich solvents are more likely to dissolve 12-HSA preventing gelation or crystallization. Surprisingly, it is found that 12-HSA is able to gelate a series of diols, but not their mono functional alcohols. A potential gelation mechanism is proposed that the diol co-crystallizes between 12-HSA molecules promoting 1-dimensional growth. The gelation behavior, fiber morphology, thermal properties as well as viscolastic properties of the resultant gels are drastically affected by the structure of diol solvents. Solvents shorter in chain length, with –OH groups at each terminal end, tend to form fibrous aggregates with higher gelation capacity, higher melting points and mechanically are stronger. Both increasing the diol chain length and the position of the hydroxyl groups from the primary positions lead to reduced gelation ability. The resultant gels comprised of highly branched, ‘spherulitic-like’ crystals are mechanically weaker with lower melting point.


Link to article: http://pubs.rsc.org/en/Content/ArticleLanding/2015/CE/C5CE00652J#!divAbstract

[50]  Lan, Y., Corradini, M.G., Weiss, R.G., Raghavan, S.R., and Rogers, M.A., To Gel or Not to Gel: Correlating Molecular Gelation with Solvent Parameters. Chemical Soceity Reviews. 44, 6035-6058.


Rational design of small molecular gelators is an elusive and herculean task, despite the rapidly growing body of literature devoted to such gels over the past decade. The process of self-assembly, in molecular gels, is intricate and must balance parameters influencing solubility and those contrasting forces that govern epitaxial growth into axially symmetric elongated aggregates. Although the gelator-gelator interactions are of paramount importance in understanding gelation, the solvent-gelator specific (i.e., H-bonding) and nonspecific (dipole-dipole, dipole-induced and instantaneous dipole induced forces) intermolecular interactions are equally important. Solvent properties mediate the self-assembly of molecular gelators into their self-assembled fibrillar networks. Herein, solubility parameters of solvents, ranging from partition coefficients (logP), to Henry’s law constants (HLC), to solvatochromic ET(30) parameters, and Kamlet-Taft parameters (b, a and p), and to Hansen solubility parameters (dp, dd, dh), are correlated with the gelation ability of numerous classes of molecular gelators. Advanced solvent clustering techniques have lead to the development of a priori tools that can identify the solvents that will be gelled and not gelled by molecular gelators. These tools will greatly aid in the development of novel gelators without solely relying on serendipitous discoveries. These tools illustrate that the quest for the universal gelator should be left in the hands of Don Quixote and as researchers we must focus identifying gelators capable of gelling classes of solvents as there is likely no one gelator capable of gelling all solvents.


Link to article: http://pubs.rsc.org/en/content/articlelanding/2015/cs/c5cs00136f#!divAbstract

[49]  Fondaco D.,  AlHasawi,  F.,  Lan, Y., Ben-Elazar, S., Connolly, K., and  Rogers, M.A. 2015. Biophysical Aspects of Lipid Digestion in Human Breast Milk and Similac™ Infant Formulas.  Food Biophysics. 10, 282-291.


Physico-chemical properties of human breast milk were compared to four Similac™ infant formulas, and correlated with in vitro free fatty acid bioaccessibility using a simulated gastrointestinal system (TIM-1). Viscoelastic measurements, as a function of pH (pH 6.5 to 3.0) and shear rate, showed lower viscosities in breast milk compared to infant formulas. Droplet size and distribution measurements showed distinct differences between the tested formulas and breast milk. During lipid digestion, a lag period was observed for only breast milk. The rate of lipolysis was found to be higher in breast milk compared to Similac™ formulas. The total bioaccessible free fatty acids for Advance infant formula and breast milk were not statistically different for the in vitro TIM- 1 model and the shifted-logistical model using one-way ANOVA (p<0.05) with a Tukey’s Multiple Comparison Test. All other infant formulas had significantly lower free fatty acid bioaccessibilities at the end of the simulated digestion. A positive correlation between rate of lipolysis and droplet surface area per gram for the Similac™ infant formulas was found. However, breast milk did not follow that trend, suggesting the possible involvement of other factors in rate of lipolysis for breast milk.


Link to article: http://link.springer.com/article/10.1007/s11483-014-9388-6

[48]  Liu, C. and Rogers, M.A.* 2015. Self-Assembly of 12-Hydroxystearic Acid Molecular Gels in Mixed Solvent Systems Rationalized using Hansen Solubility Parameters. Colloid & Polymer Science.  293, 975-983.


Recent advances in understanding the underlying mechanisms of self-assembly in molecular gels using Hansen solubility parameters (HSPs) have focused on gelator-single solvent mixtures. In this study, the effect of ternary solvent mixtures usingoctane, 1-octanol and 1-octylaminewere employed at different ratios to investigate the effects on structure, thermal and rheological properties of 12HSA/solvent blends. Solutions and precipitates resulted with high concentrations of 1-octanol ( 50%) with the exception of three systems that are solutions rich in 1-octane ( 50%). The CGC gradually increases as the proportion of 1-octanol increases. The lowest CGC (~ 0.4 wt%) is obtained at a 50:50 wt% ratio of octane and 1-octylamine. Linear correlations between CGC and p formed in specific regions where each reigon has the same proportion of octane with different ratios of either 1-octanol and 1-octylamine (i.e., Region 1, 60% octane, (1.12 <p < 1.22 MPa1/2); region 2, 50% octane (1.4 <p < 1.55 MPa1/2); region 3, 40% octane ( 1.68 <p < 1.88 MPa1/2), region 4, 30% octane (1.96 <p < 2.16 MPa1/2); and region 5, 20% octane (2.24 <p < 2.54 MPa1/2). CGC increases with an increasing proportion of 1-octanol and a decreasing proportion of 1-octylamine as p increases within each region. Both G' and breaking points decrease in a log-linear fashion as each individul HSP or total HSP increases, suggesting that 1-octanol-rich gels do not form strong gels because of hydrogen-bonding between 1-octanol and 12-HSA which is capable of impeding fiber growth. The interaction between 12-HSA and 1-octanol is more disruptive to fiber growth than 1-octylamine which arises because of the solvents ability to accept or donate a hydrogen-bond.


Link to Article: http://link.springer.com/article/10.1007/s00396-014-3480-9


[47] Rogers, M.A., and Weiss, R.G.* 2015. Alkane-Based Molecular Gelators and the Structures and Properties of their Gels. New Journal of Chemistry. 39, 785-799.


A systematic structural development of organic gelators based on n-alkanes is presented. It is shown that judicious substitution of the n-alkane ‘platform’ leads to gelators whose molecular gels have a variety of properties. Those properties can, in some cases, be correlated with the structures of the gelators and the natures of their self-assembled fibrillar networks as analyzed at different distance scales. A special emphasis is placed on 12-hydroxystearic acid, a well-studied molecular gelator, and its derivatives in which the placement and functionality of the hydroxyl group have been varied and the carboxylic head group has been modified systematically. The resulting correlations between molecular gelator structure and the various properties of their gels provides a basis for the design of structurally more complex gelators. However, the nuances of the systems explored demonstrates that additional factors, some of which are currently not well studied, must be considered before a priori design of molecular gelators with specific gelating abilities will be possible.


Link to Article: http://pubs.rsc.org/en/content/articlelanding/2015/nj/c4nj01439a#!divAbstract

2014

[46]  Du, H., Corradini, M.G., Ludescher, R., Rogers, M.A. 2014. Micro-Viscosity of Oil Confined in a Colloidal Fat Crystal Network. Soft Matter.  10, 8652-8658.


Molecular rotors may be utilized as non-invasive, non-disruptive and highly sensitive alternatives to conventional measures of bulk viscosity when the oil is entrained in a colloidal fat crystal network. Oil viscosity changes based on the molecular confinement of the oil, which is dependent on its molecular volume. Changes in micro-viscosity were not dependent on the solids content, but instead were strongly dependent on the box-counting fractal dimension in high-space filling colloidal fat crystal networks (i.e., D > 1.89). A bulk oil viscosity is often an overestimation of the actual viscosity of the entrained oil and may not be appropriate when predicting diffusion in multi-phase materials.


Link to Article: http://pubs.rsc.org/en/content/articlelanding/2014/sm/c4sm01632g#!divAbstract

[45]   Lan, Y., Corradini, M. G., Rogers, M.A.* 2014. Do Molecular Gelators Cluster in Hansen Space?  Crystal Growth & Design. 14, 4811-4818.


Hansen solubility parameters (HSP) aid in the a priori prediction of which low molecular weight molecules have the potential to act as low molecular weight organogelators (LMOGs) and can immobilize certain liquids. The hydrogen-bonding HSP parameter, individually has some predictive capacity on whether a molecule will form a gel, solution or precipitate in a known liquid; in the case of benzene, gelators with δh > 5 MPa0.5 form gels, while molecules with δh < 10 MPa0.5 gel ethanol. Small molecules, which gel or remain in a solution state tend to cluster in specific regions of Hansen space. Excellent confinement of solutions was observed within solubility sphere of benzene, ethanol and acetonitrile. Based on the LMOGs selected, both the magnitude and directionality of the vector in Hansen space are important in predicting the gelation capacity (i.e., a gelator tends to gel toluene ∆δp < -4 MPa0.5 when combining the role of ∆2δd and ∆δp and ignoring ∆δh).


Link to Article: http://pubs.acs.org/doi/abs/10.1021/cg500985e

[44] Rogers, M.A.,* Yan, Y.-F., Ben-Elazar, K., Lan, Y., Faig, J., and Uhrich, K.* 2014. Salicylic acid (SA) Bioaccessibility from SA-based Poly(anhydride-ester). Biomacromolecules.   15, 3406-3411.


The bioaccessibility of salicylic acid (SA) can be effectively modified by incorporating the pharmacological compound directly into poly(anhydride-esters) of salicylic acid (SADG-P) and salicylic acid diglycolylic acid (SADG). After simulated digestion conditions, the bioaccessibility of SA was observed to be statistically different (p<0.0001) in each sample: 40.3 ± 2.0 % for SA, 23.9 ± 1.3 % for SADG (polymer precursor), and 16.2 ± 1.1 % for SADG-P (polymer). The release rates followed a zero-order reaction rate that were dependent on several factors: 1) solubilization rate; 2) macroscopic erosion of the powdered polymer; 3) hydrolytic cleavage of the anhydride bonds and finally, 4) subsequent hydrolysis of the polymer intermediate (SADG) to SA and diglycolic acid.


Link to Article: http://pubs.acs.org/doi/abs/10.1021/bm500927r

[43] Lan,Y., Corradini, M.G., Liu, X., May, T., Borondics, F., Weiss, R.G., and Rogers, M.A., 2014.

Probing Solubility Parameters Governing Self-Assembly of Molecular Gels.  The case of 1,3:2,4-Dibenzylidene Sorbitol.  Langmuir. Feature Article.  30, 14128-14142.


Solvent properties play a central role in mediating the aggregation and self-assembly of molecular gelators and their growth into fibers. Numerous attempts have been made to correlate solubility parameters of solvents and gelation abilities of molecular gelators, but a comprehensive comparison of the most important parameters has yet to appear. Here, the degree to which partition coefficients (logP), Henry’s law constants (HLC), dipole moments, static relative permittivities (er), solvatochromic ET(30) parameters, Kamlet-Taft parameters (b, a and p), Catalan’s solvatochromic parameters (SPP, SB and SA), Hildebrand solubility parameters (di), and Hansen solubility parameters (dp, dd, dh) and the associated Hansen distance ( Rij) of 62 solvents (covering a wide range of properties) can be correlated with the self-assembly and gelation of 1,3:2,4-dibenzylidene sorbitol (DBS) gelation, a classic molecular gelator, is assessed systematically. The approach presented describes the basis for each of the parameters and how it can be applied. As such, it is an instructional ‘blueprint’ for how to assess the appropriate type of solvent parameter for use with other molecular gelators as well as with molecules forming other types of self-assembled materials. The results also reveal several important insights into the factors favoring gelation of solvents by DBS. The ability of a solvent to accept or donate a hydrogen bond is much more important than solvent polarity in determining whether mixtures with DBS become solutions, clear gels, or opaque gels. Thermodynamically derived parameters could not be correlated to the physical properties of the molecular gels unless they were dissected into their individual HSPs. The DBS-solvent phases tend to cluster in regions of Hansen space and are highly influenced by the hydrogen-bonding HSP, dh. It is also found that the fate of this molecular gelator, unlike that of polymers, is influenced not only by the magnitude of the distance between the HSPs for DBS and the HSPs of the solvent, Rij, but also by the directionality of Rij: if the solvent has a larger hydrogen bonding HSP (indicating stronger H-bonding) than that of the DBS, clear gels are formed; opaque gels form when solvent has a lower dh than that of the DBS.


Link to Article: http://pubs.acs.org/doi/abs/10.1021/la5008389?journalCode=langd5


 
[42] Rogers, M.A., Strober, T., Bot, A., Toro-Vazquez, J.F., Stortz, T., and Marangoni, A.G., 2014.  Edible Oleogels in Molecular Gastronomy.  2, 22-31.

Experimental chefs and researchers have limited options when structuring lipid-based materials present in foods to include: liquids, solids, foams or emulsions.  However, the application of gel technology for lipids is on the cusp of advancing into experimental culinary kitchens around the world.  The possibility of utilizing edible oils (and even ethanol) to extract a hydrophobic flavor and then gel the material in a similar fashion as hydrocolloids gel water is now a reality.  This review covers the three primary oleogels: ethyl cellulose, mixtures of g-oryzanol and b-sitosterol and candelilla wax.







Link to manuscript: http://www.sciencedirect.com/science/article/pii/S1878450X14000043

[41] Szakal, C., Roberts, S., Westerhoff, P., Bartholomaeus, A., Buck, N., Illuminato, I., Canady, R., and Rogers, M.A. 2014. Measurement of Nanomaterials in Foods: Integrative Consideration of Challenges and Future Prospects. ACS Nano. 8, 3128-3135.  


The risks and benefits of nanomaterials in foods and food contact materials receive

conflicting international attention across expert stakeholder groups as well as in news media coverage and published research. Current nanomaterial characterization is complicated by the lack of accepted approaches to measure exposure-relevant occurrences of suspected nanomaterials in food and by broad definitions related to food processing and additive materials. Therefore, to improve understanding of risk

and benefit, analytical methods are needed to identify what materials, new or traditional, are “nanorelevant” with respect to biological interaction and/or uptake during alimentary tract transit. Challenges to method development in this arena include heterogeneity in nano material composition and morphology, food matrix complexity, alimentary tract diversity, and analytical method limitations. Clear problem formulation is required to overcome these and other challenges and to improve understanding of biological fate in facilitating the assessment of nanomaterial safety or benefit, including sampling strategies relevant to food production/ consumption and alimentary tract transit. In this Perspective, we discuss critical knowledge gaps that must be addressed so that measurement methods can better inform risk management and public policy.


Link to manuscript: http://pubs.acs.org/doi/abs/10.1021/nn501108g

2013

[40] Xu, S., Cavera, V., Rogers, M.A., Huang, Q., Zubovskiy, K., and Chikindas, M.L.* 2013. Benzoyl Peroxide Formulated Polycarbophil/Carbopol 934P Hydrogel with Selective Antimicrobial Activity, Potentially Beneficial for Treatment and Prevention of Bacterial Vaginosis. 2013. Infectious Diseases in Obstetrics and Gynecology. 1-10.


The human vagina is colonized by a variety of indigenous microflora; in healthy individuals the predominant bacterial genus is Lactobacillus while those with bacterial vaginosis (BV) carry a variety of anaerobic representatives of the phylum Actinobacteria. In this study, we evaluated the antimicrobial activity of benzoyl peroxide (BPO) encapsulated in a hydrogel against Gardnerella vaginalis, one of the causative agents of BV, as well as indicating its safety for healthy human lactobacilli. Herein, it is shown that in well diffusion assays G. vaginalis is inhibited at 0.01% hydrogel-encapsulated BPO and that the tested Lactobacillus spp. can tolerate concentrations of BPO up to 2.5%. In direct contact assays (cells grown in a liquid culture containing hydrogel with 1% BPO or BPO particles), we demonstrated that hydrogels loaded with 1% BPO caused 6-log reduction of G. vaginalis. Conversely, three of the tested Lactobacillus spp. were not inhibited while L. acidophilus growth was slightly delayed. The rheological properties of the hydrogel formulation were probed using oscillation frequency sweep, oscillation shear stress sweep, and shear rate sweep. This shows the gel to be suitable for vaginal application and that the encapsulation of BPO did not alter rheological properties.


Link to manuscript: http://dx.doi.org/10.1155/2013/909354

[39] AlHasawi, F.M. and Rogers, M.A. 2013. Ternary Phase Diagram of b-Sitosterol-g-Oryzanol-Canola Oil.  2013. Journal of the American Oil Chemists' Society.  90. 1533-1540.

Abstract:

b-sitosterol and g-oryzanol have been shown to form unique structures in canola oil that have the potential to act as saturated and trans fat replacers [1-7]. The ternary phase, reported herein, illustrates numerous interesting physical systems. At high canola oil ratios with low b-sitosterol and g-oryzanol concentrations, the system has a crystal structure capable of mimicking fat crystal networks. Four mesophases are identified based on Bragg’s ratios using small angle x-ray scattering. Two mesophases are lamellar crystals, one is the cubic P phase, and the fourth is an amorphous material due to the low solids content. Wide-angle x-ray further subcategorized the phases based on polymorphic divisions of the hydrocarbon side chain packing. In all, six distinct phases are reported, ranging from lamellar crystals, to liquid crystals to what appears to be a lipid glass.


Link to Manuscript:



[38] Lee, P., and Rogers, M.A., 2013 Effect of Calcium Source and Exposure-Time on Basic Caviar Spherification Using Sodium Alginate. International Journal of Gastronomy and Food Science, 1, 96-100.

Abstract:

Gelation speed is directly proportional to the concentration of calcium.  Although the kinetics of gelation are altered by the source of calcium, the final alginate gel strength nor the resistance to calcium diffusion are altered. Calcium chloride reaches a gel strength plateau fastest (~100 seconds), followed by calcium lactate (~500 seconds) and calcium gluconoate (~ 2000 seconds).  Calcium chloride is the best option when the bitter taste can be masked and a fast throughput is required, while calcium gluconoate may have an advantage when the membrane thickness/hardness needs to be manipulated.


Link to manuscript: http://www.sciencedirect.com/science/article/pii/S1878450X13000073

[37]  Sparanzza, A., Corradini, M.G., Ribnicky, D., Oren, A. and Rogers, M.A. 2013. Influence of Emulsifier Structure on Lipid Bioaccessibility in Oil/Water Emulsions.  Journal of Agriculture and Food Chemistry, 61, 6505-6515. 


The influence of several nonionic surfactants (Tween-20, Tween-40, Tween-60, Span-20, Span-60, or Span-80) and anionic surfactants (sodium lauryl sulfate, sodium stearoyl lactylate, and sodium stearyl fumarate) showed drastic differences in the rank order of lipase activity/lipid bioaccessibility. The biophysical composition of the oil and water interface has a clear impact on the bioaccessibility of fatty acids (FA) by altering the interactions of lipase at the oil/water interface. It was found that the bioaccessibility was positively correlated with the hydrophilic/lipophilic balance (HLB) of the surfactant and inversely correlated to the surfactant aliphatic chain length. Furthermore, the induction time in the jejunum increased as the HLB value increased and decreased with increasing aliphatic chain length.  The rate of lipolysis slowed in the jejunum with increasing HLB and with increasing aliphatic chain length. 


Link to manuscript: http://pubs.acs.org/doi/abs/10.1021/jf401548r

[36] Wu, S., Gao, J., Emge, T.J., and Rogers, M.A. 2013. Influence of solvent on the supramolecular architectures in molecular gels.  Soft Matter. 9, 25, 5942-5950.


Abstract:

Elucidating the molecular structures, responsible for promoting self-assembly of low-molecular weight organogelators (LMOG) into supramolecular fibers, has been an extensive area of study.  Although this has been a fruitful endeavor, this study illustrates that the chemical nature of the solvent and solvent-gelator interactions are equally important.  The nanostructure, microstructure and supramolecular structures, of 12HSA molecules gels, are all influenced by the chemical nature of the solvent, which correlate to the hydrogen-bonding Hansen solubility parameter (∂h).  Depending on the solvent employed, the polymorphic form, arrangement of the carboxylic acid dimers, domain size, fiber morphology, microstructure, thermal properties and visual appearance of the gel all differ.  Solvents that have dh < 4.4 MPa1/2, result in a hexagonal polymorphic form, with an 001 hlk spacing greater than the extended bi-molecular length of 12HSA.  This nanoscale arrangement results in translucent gels that contain fibrillar aggregates corresponding to a higher crystallinity compared to molecular gels formed in solvents that have a dh > 4.4 MPa1/2.


Link to manuscript: http://pubs.rsc.org/en/content/articlelanding/2013/SM/C3SM50936B


[35] Pal, A., Abraham, S., Rogers, M.A., Dey, J., Weiss, R.G., 2013. Comparison of Dipolar, H-Bonding, and Dispersive Interactions on Gelation Efficiency of Positional Isomers of Keto and Hydroxy Substituted Octadecanoic Acids.  Langmuir.  29, 6467-6475.

A systematic study of the importance of functional group position and type on the gelator efficiencies of structurally simple, low molecular-mass gelators is reported. Thus, the gelation abilities of a series of positional isomers of ketooctadecanoic acid (n-KSA) are compared in a wide range of liquids. The gelation abilities of the n-KSA as a function of n, the keto group position along the chain, are characterized by several structural, thermal, and rheological techniques and are compared with those of the corresponding hydroxyoctadecanoic acid isomers (n-HSA) and the parent molecule, octadecanoic acid (SA). Analyses of the gels according to the strengths of functional group interactions along the alkyl chain in terms of group position and type are made. The conclusions derived from the study indicate that gel stability is enhanced when the functional group is located relatively far from the carboxylic headgroup and when group–group interactions are stronger (i.e., hydrogen-bonding interactions are stronger in the n-HSA than dipole interactions in the n-KSA, which are stronger than the London dispersion interactions in SA). Co-crystals of the keto- and hydroxy-substituted octadecanoic acids are found to be less efficient gelators than even the ketooctadecanoic acids, due to molecular packing and limited group interactions within the gelator networks.

Link to manuscript: http://pubs.acs.org/doi/abs/10.1021/la400664q

[34]  Gao, J., Wu, S., Emge, T.J., and Rogers, M.A. 2013. Nanoscale and Microscale Structural Changes Alter the Critical Gelator Concentration of Molecular Gels in Organic Solvents.  CrystEngComm, 15, 4507-4515.


Abstract:

It has been well established that self-assembled fibrillar networks require a meticulous balance between opposing molecular forces that control solubility and those intermolecular forces that direct epitaxial growth into axially symmetric elongated aggregates. The chemistry of the continuous phase (i.e., solvent) influences every level of structure in molecular gels. Solvent parameters induce low molecular weight gelators (LMOGs) to crystallize into different polymorphic forms, as well cause changes in the lamellar arrangement and domain size. These nanoscale alterations cause measureable differences in the microstructure, which induce physical macroscopic changes including the critical gelator concentration, melting temperature, melting enthalpy and opacity of the gel. Specifically, some solvents cause 12-hydroxyoctadecanoic acid (12HOA) to self-assemble into triclinic parallel polymorphic forms where the lamellar spacing indicates that 12HOA forms an interdigitated network (lamellar spacing <46 Å). The resulting molecular gels are opaque due to the presence of spherulitic crystals and have elevated critical gelator concentrations (i.e., greater than 1.5 wt%). Conversely, other solvents result in the formation hexagonal polymorphs and an extended bi-molecular length greater than 46 Å observed in the lamellar spacing. In these solvents, 12HOA forms translucent molecular gels, at concentrations less than 1.5 wt%, comprised of axially symmetric elongated crystals.


Link to Manuscript: http://pubs.rsc.org/en/content/articlepdf/2013/CE/C3CE40323H

[33] Lee, P., and Rogers, M.A. 2013. Phase Selective Sorbent Xerogels As Reclamation Agents for Oil Spills.  Langmuir. 29, 5617-5621


Abstract: 12-Hydroxystearic acid (12-HSA) xerogels derived from 12-HSA–acetronitrile organogels are highly effective sorbent materials capable of adsorbing apolar, spilled materials in aqueous environments. 12-HSA xerogels made from 12-HSA–acetronitrile organogels are more effective than 12-HSA xerogels made from 12-HSA–pentane organogels because of the highly branched fibrillar networks established in acetonitrile molecular gels. This difference arises because of dissimilarities in the network structure between 12-HSA in various solvents. These xerogels, being thermoreversible, allow for both the spilled oil to be reclaimed but also the gelator may be reused to engineer new xerogels for oil spill containment and cleanup.



Link to mauscript: http://pubs.acs.org/doi/abs/10.1021/la400805c

[32]  Wu, S., Gao, J., Emge, T.J., and Rogers, M.A. 2013. Solvent Induced Polymorphic Nanoscale Transitions for 12-Hydroxyoctadecanoic Acid Molecular Gels. Crystal Growth & Design. 13, 1360-1366.


Abstract:

12-Hydroxyoctadecanoic acid (12HSA) molecular gels have been reported to form self-assembled fibrillar network (SAFiNs) in organic solvents. For the first time, different polymorphic forms for 12HSA molecular gels have been reported. 12HSA, in alkanes and thiols, have a hexagonal subcell spacing (4.1 Å) and are arranged in a multilamellar fashion with a distance greater than the bimolecular length of 12HSA (54 Å). This polymorphic form corresponded to SAFiN with CGC less than 1 wt %. 12HSA, in nitriles, aldehydes, and ketones, have a triclinic parallel subcell (4.6, 3.9, and 3.8 Å) and interdigitation of the lamellar structure (38–44 Å). This polymorphic form corresponds to a less effective sphereultic supramolecular crystalline network, which immobilizes solvents at CGC greater than 1.5 wt %.


Link to manuscript: http://pubs.acs.org/doi/abs/10.1021/cg400124e?mi=17j3s74&af=R&pageSize=20&searchText=nano


2012

[31] Rogers, M.A., Abraham, S., Bodondics, F., and Weiss, R.G.  2012. Positional Isomers of Hydroxyoctadecanoic Acid Molecular Gels and Dispersions Influence Crystallization Kinetics and Activation Energies. Crystal Growth & Design. 12, 5497-5504.


Abstract:

Minor changes in molecular structure affect the ability of racemic hydroxyoctadecanoic acids (nHSA, where n is the position of the hydroxyl group) to form molecular gels in a low polarity liquid, mineral oil, and influence their supramolecular structures. The activation energy and energy released during crystallization of 2HSA and 3HSA from solutions or sols are significantly lower than those of 6HSA, 8HSA, 10HSA, 12HSA, and 14HSA. The lower activation energies are associated with the ease of molecules of 2HSA or 3HSA to add to a face of a growing crystal lattice or the ease in which the critical nuclei are reached; the change in the activation energies appears to be related, in part, to the critical size of the crystallites, which, in turn, depends on the energy associated with the creation of the new phase and the interfacial free energy of the nucleated species with the liquid component. When the polar groups are close in proximity, the crystal packing arrangements are able to sequester these groups away from an interface and reduce the contact with the low polarity solvent. As well, the energies released upon the formation of the new phases with 2HSA and 3HSA are less than those for the other nHSA isomers studied here because the former are unable to form strong carboxylic acid dimers.


Link to manuscript: http://pubs.acs.org/doi/abs/10.1021/cg301071x


[30] Gao, J., Wu, S., and Rogers, M.A. 2012. Harnessing Hansen Solubility Parameters To Predict Organogel Formation.  Journal of Materials Chemistry. 22, 12651-12658.


Abstract:

Hansen solubility parameters predict the capacity of molecular gels to form in a vast array of organic solvents. The prediction ability for 12-hydroxystearic acid is closely associated with the hydrogen-bonding Hansen solubility parameter (δh). Solvents with a hydrogen-bonding Hansen solubility parameter less than 4.7 MPa1/2 produce clear organogels, opaque organogel formed between 4.7 < δh < 5.1 MPa1/2 and solutions remained when the hydrogen-bonding Hansen solubility parameter is greater than 5.1 MPa1/2. Furthermore, the critical gelator concentration is linearly correlated with the hydrogen-bonding Hansen solubility parameter. Solvents with the same functional group, which varied only by chain length, have correlations between the static relative permittivity, Hansen solubility parameter, dispersive HSP, polar HSP and hydrogen-bonding HSP and the critical gelator concentration.


Link to manuscript: http://pubs.rsc.org/en/Content/ArticleLanding/2012/JM/c2jm32056h


[29] Abraham, S., Lan, Y., Lam, R.S.H., Grahame, D.A.S., Kim, J.J.H., Weiss, R.G., and Rogers, M.A.  2012. Influence of Positional Isomers on the Macroscale and Nanoscale Architectures of Hydroxyoctadecanoic Acid Molecular Gels.  Langmuir. 28. 4955-4964.

Abstract:
Inter/intramolecular hydrogen bonding of a series of hydroxystearic acids (HSAs) are investigated. Self-assembly of molecular gels obtained from these fatty acids with isomeric hydroxyl groups is influenced by the position of the secondary hydroxyl group. 2-Hydroxystearic acid (2HSA) does not form a molecular dimer, as indicated by FT-IR, and growth along the secondary axis is inhibited because the secondary hydroxyl group is unable to form intermolecular H-bonds. As well, the XRD long spacing is shorter than the dimer length of hydroxystearic acid. 3-Hydroxystearic acid (3HSA) forms an acyclic dimer, and the hydroxyl groups are unable to hydrogen bond, preventing the crystal structure from growing along the secondary axis. Finally, isomers 6HSA, 8HSA, 10HSA, 12HSA, and 14HSA have similar XRD and FT-IR patterns, suggesting that these molecules all self-assemble in a similar fashion. The monomers form a carboxylic cyclic dimer, and the secondary hydroxyl group promotes growth along the secondary axis.

Link to manuscript: http://pubs.acs.org/doi/full/10.1021/la204412t

[28] Rogers, M.A., and Kontogiorgos, V., 2012. Temperature dependence of relaxation spectra of self-assembled fibrillar networks of 12-hydroxystearic acid in canola oil organogels. Food Biophysics. 7, 132-137.


Abstract:

The temperature dependence, of the mechanical properties of 12-hydroxystearic acid (12HSA) molecular gels, was investigated by means of rheometry and electron microscopy. Application of Tikhonov regularization on the transients of stress relaxation data of 12HSA gels revealed the remarkable impact of fiber morphology on the relaxation spectrum. Relaxation processes with long characteristic times (i.e., τ > 10 sec) correspond to thick fibers whereas thin fibers relax on a much faster time scale (i.e., τ < 1 sec). Molecular gels crystallized at low temperatures, have variable fiber lengths and widths, show three relaxation events as opposed to the high crystallization temperature counterparts that have uniform fibers and result in fewer relaxation events. These relaxation events correspond exponentially to the fiber cross-sectional thickness.


Link to manuscript: http://link.springer.com/article/10.1007/s11483-012-9250-7

2011

[27] Rogers, M.A. 2011.  Co-operative self-assembly of cholesterol and γ-oryzanol composite crystals. CrystEngComm. 13, 7049-7057.


Abstract:

Cholesterol and γ-oryzanol co-crystallization occurs when equal ratios of the two compounds or excess γ-oryzanol is present in the solution. Excess cholesterol produces macroscopic fibrillar crystals from the melt prior to the co-crystallization and formation of radial fine fibers under slow cooling conditions. The cholesterol fibrillar crystals then facilitate cholesterol-γ-oryzanol co-crystallization producing fine fibers that nucleate from the surface of the cholesterol crystals. Equal ratios of cholesterol and γ-oryzanol or excess γ-oryzanol allow the radial fine fibers to nucleate from the melt without the need of an internal crystal template.



Link to manuscript: http://pubs.rsc.org/en/content/articlelanding/2011/CE/c1ce05818e

[26] Lam, R.S.H, Rogers, M.A. 2011. Activation Energy of Crystallization for Trihydroxystearic Acid, Stearic Acid and 12-Hydroxystearic Acid under Non-Isothermal Cooling Conditions.  Crystal Growth and Design.  11, 3593-3599.


Abstract:

The nucleation activation energy under nonisothermal cooling conditions was determined for 12-hydroxystearic acid (12HSA) (1-D crystals), stearic acid (2-D crystals), and trihydroxystearin (3-D crystals). The relative nucleation rates of trihydroxystearin and stearic acid were inversely proportional to the supercooling-time trajectory parameter (β), while 12HSA was linearly proportional to β. The differences in the proportionality to β are attributed to microscopic versus macroscopic phase separation. This suggests that both stearic acid and trihydroxystearin follow a probability density function for the number of molecules which crystallize as a function of supercooling (i.e., the greater the cooling rate, the greater the number of molecules which are incorporated into the crystal lattice). On the other hand, 12HSA molecules all crystallize when supercooled. The activation energies for stearic acid, 12HSA, trihydroxystearin, and triglycerides were 1.52, 5.40, 7.87, and 24.80 kJ/mol, respectively. The activation energy is partly affected by the polarity of the crystallizing molecules relative to the solvent. As the polarity of the crystallizing molecules increases, the activation energy decreases. However, this was not always observed because the activation energy for stearic acid was less than that of 12HSA. Therefore, the activation energy is not only a function of the molecular polarity but also due to a specific interaction between the nucleating molecules. The specific interaction affects the ability of the polar regions of the molecule to phase separate from the apolar solvent. As 12HSA and stearic acid dimerize, the carboxylic acid regions of the molecule are shielded from the solvent, but 12HSA cannot effectively shield the hydroxyl groups from the crystalline surface, resulting in a higher interfacial tension and, thus, higher activation energy.


Link to manuscript: http://pubs.acs.org/doi/abs/10.1021/cg200553t

[25] Grahame, D.A.S., Olauson, C. Lam, R.S.H., Pedersen, T., Borondics, F. Abraham, S. Weiss, R.G., Rogers, M.A. 2011. Influence of Chirality on the Modes of Self-Assembly of 12-Hydroxystearic Acid in Molecular Gels of Mineral Oil. Soft Matter. 7, 7359-7365.


Abstract:

The gelating abilities of enantiopure, racemic, and different enantio-enriched mixtures of 12-hydroxystearic acid (12HSA) have been compared in order to clarify conflicting reports in the literature (1) concerning their ability to gelate organic liquids. Less than 1.0 wt % of optically pure (D)-12HSA was found to gelate mineral oil. The gel matrix was comprised of high aspect ratio fibers in which the 12HSA molecules were organized as head-to-head dimers and the 12-hydroxyl groups formed an H-bonding network along the axis transverse to the longitudinal growth. Below 2 wt %, racemic 12HSA in mineral oil did not reach the percolation threshold. Its organogels were comprised of platelet-like crystals with a molecular arrangement of single, in-plane, hydrogen-bonded acyclic dimers that prevent longitudinal growth and limit the ability of the polar groups to phase separate during nucleation.


Link to Manuscript: http://pubs.rsc.org/en/Content/ArticleLanding/2011/SM/c1sm05757j


[24] Rutherford, H., Low, N.H., Borondics, F., Pedersen, T., Rogers, M.A. 2011. Dependence of Liquid Crystal Morphology on Phospholipid Hydrocarbon Length.  Colloids and Surfaces: Biointerfaces. 87, 116-121.


Abstract:

The liquid crystal morphologies of symmetrical diacy phosphatidylcholine liposomes examined in this research study were found to be dependent on saturated hydrocarbon chain length. Both powder X-ray diffraction and synchrotron mid-IR spectromicroscopy indicate that phosphatidylcholines with short hydrocarbon tails (i.e. ten and twelve carbons) are more likely to form unilamellar liposomes while those with long hydrocarbon tails (i.e. eighteen and twenty carbons) are more likely to form multilamellar liposomes. Hydrocarbon chain lengths of fourteen and sixteen represent a transitional zone between these two liquid crystal morphologies. The FTIR spectra where a shoulder develops on the peak at wavenumber 1750 cm−1 particularly highlights the change in the packing of adjacent molecules in the transitional zone.


Link to manuscript: http://www.sciencedirect.com/science/article/pii/S0927776511002682

[23] Rogers, M.A., and Kim, J.J.H. 2011. Rheological Assessment of the Sol-Gel Transition for Self-Assembling Low Molecular Weight Gelators. Food Research International.  44, 1447-1451.


Abstract: The complexity of the transition from solution to gel for low molecular weight gelators in apolar solvents makes it incredibly difficult to assess the gel point. Since both nucleation and crystal growth occurs prior to the formation of a continuous three dimensional network numerous techniques, such as calorimetry and inflection point of the complex modulus, are invalid when probing the gel point. However, monitoring the frequency dependence of G′ and G″ illustrates the transition from a dilute solution to a weak gel which may be differentiated from the gel point observed by the decreasing value of the complex viscosity as a function of frequency. For 3% 12-hydroxystearic acid in mineral oil once the gelator nucleates the material behaves as a dilute solution, upon crystal growth (67 °C) we observe the true cross over point which is independent of frequency and finally a strong gel is formed at 64 °C where G′ and G″ are independent of frequency.


Link to manuscript: http://www.sciencedirect.com/science/article/pii/S0963996911001712

[22] Lam, R. and Rogers, M.A. 2011. Experimental Validation of the Modified Avrami Model for Non-Isothermal Crystallization Condition.  CrystEngComm. 13, 866-875.


Abstract:

The modified Avrami model was found to accurately predict the induction time, maximum phase volume and dimensionality of crystal growth for stearic acid containing molecules when the experimental method employed measures as a function of phase volume. Four methods were examined to validate the model including: Fourier transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), small deformation rheology and polarized light microscopy (PLM). PLM and FT-IR were able to detect the nucleation event prior to DSC and rheology. FT-IR and PLM provided the most accurate data due to the similarities between the experimental and fitted induction times (x0), maximal phase change (ymax) and the Avrami exponent (n). Further, the Avrami exponent, obtained from FT-IR, was sensitive to both the mode of nucleation and the dimensionality of crystal growth. Therefore, the apparent rate constants (kapp) obtained by FT-IR and PLM are useful in providing further insights into the kinetics of non-isothermal crystallization. The calculated apparent rate constants suggest a diffusion limited crystallization at slow cooling rates (i.e., below 5–7 °C min−1) and at cooling rates greater than 5–7 °C min−1, the incorporation of the gelator molecules onto the crystal lattice becomes limited by the reaction rate constant.


Link to manuscript: http://pubs.rsc.org/en/Content/ArticleLanding/2011/CE/c0ce00523a

2010

[21] Rogers, M.A., Bot, A., Lam, R., Pedersen, T., and May, T.  2010. Multi-Component Hollow Tubules Formed Using Phytosterol and γ-Oryzanol Based Compounds: An Understanding of their Molecular Embrace.  Journal of Physical Chemistry A. 114, 8278-8285.


Abstract:

The formation kinetics of self-assembling tubules composed of phytosterol:gamma-oryzanol mixtures were investigated at the Canadian Light Source on the mid-IR beamline using synchrotron radiation and Fourier transform infrared spectroscopy (FT-IR). The Avrami model was fitted to the changing hydrogen bonding density occurring at 3450 cm(-1). The nucleation process was found to be highly dependent on the molecular structure of the phytosterol. The nucleation event for cholesterol:gamma-oryzanol was determined to be sporadic whereas 5alpha-cholestan-3beta-ol:gamma-oryzanol and beta-sitosterol:gamma-oryzanol underwent instantaneous nucleation. One-dimensional growth occurred for each phytosterol:gamma-oryzanol mixture and involved the evolution of highly specific intermolecular hydrogen bonds. More detailed studies on the cholesterol:gamma-oryzanol system indicated that the nucleation activation energy, determined from multiple rate constants, obtained using the Avrami model, was at a minimum when the two compounds were at a 1:1 weight ratio. This resulted in drastic differences to the microscopic structures and affected the macroscopic properties such as turbidity. The formation of the phytosterol:gamma-oryzanol complex was due to intermolecular hydrogen bonding, which was in agreement with the infrared spectroscopic evidence.


Link to manuscript: http://pubs.rsc.org/en/Content/ArticlePDF/2011/CE/c1ce05818e


[20] Lam, R.,  Pederson, T., and Quaroni, L., Rogers, M.A., 2010.  A Molecular Insight Into The Nature of Crystallographic Mismatches in Self-Assembled Fibrillar Networks Under Non-Isothermal Crystallization Conditions, Soft Matter; 6, 404-408.

Abstract:
The lengths of the 12-hydroxystearic acid (12HSA) fibers are influenced by crystallographic mismatches resulting from the incorporation of 12HSA monomers into the crystal lattice in an imperfect manner. On a molecular level, this can be differentiated using synchrotron Fourier transform infrared (FTIR) spectroscopy by monitoring the change in area of the 1700 cm−1 and 3200 cm−1 peaks, corresponding, respectively, to the dimerization of the carboxylic acid groups and hydroxyl non-covalent interactions, during crystallization. The crystallographic mismatch is attributed to a plateau in the apparent rate constant for the dimerization of the carboxylic acid head groups while the hydroxyl interactions linearly increase as a function of cooling rate (). The rate constant for hydroxyl interactions linearly increases as a function of cooling rate while a plateau is observed for the rate of dimerization at cooling rates between 5 and 7 °C min−1. At cooling rates greater than 5 to 7 °C min−1 12HSA monomers do not effectively dimerize before being incorporated into the crystal lattice causing crystal imperfections impeding linear epitaxial crystal growth and produces branched fibers. At slow cooling rates (i.e., less than 5 to 7 °C min−1), long fibers are produced with a fractal dimension between 0.95 and 1.05 and for rapid cooling rates (i.e., greater than 5 to 7 °C min−1) short branched fibers are produced with a fractal dimension between 1.15 and 1.32.

Link to manuscript: http://pubs.rsc.org/en/Content/ArticleLanding/2010/SM/b919477k

2009 and Older

[19] Rogers, M.A., Roos, Y.H., Goff, H.D. 2010.  Structural heterogeneity and its effects on the enzyme kinetics in sucrose solutions containing protein and polysaccharide.  Food Biochemistry.  1: 202-215


[18] Naomi E. Hughes, Alejandro G. Marangoni, Amanda J. Wright, Michael A. Rogers, James W. Rush. 2009.  Potential Food Applications of Edible Oil Organogels. 2010. Trends in Food Science. 20; 470-480.


[17] Rogers, M.A., 2009.  Novel Structuring Strategies for Unsaturated Fats-- Meeting the Zero-Trans, Zero-Saturated Fat Challenge: A Review.  Food Research International. 42, 747-753.


[16] Lam, R., Rogers, M.A., and Marangoni, A.G., 2009.  Thermo-mechanical method for the determination of the fractal dimension of fat.  Journal of Thermal Analysis and Calorimetry. 98; 7-12.


[15] Rogers, M.A., Pederson, T., and Quaroni, L.  2009. Hydrogen Bonding Density of Supramolecular Structures for Self-Assembled Fibrillar Networks Probed Using Synchrotron Infrared Spectromicroscopy. Crystal Growth & Design. 9,3621-3625 


[14] Rogers, M.A., and Marangoni, A.G.  2009.  Solvent modulated nucleation and crystallization kinetics of 12-hydroxystearic acid:  a non-isothermal approach. Langmuir’s special issue on Self-Assembled Fibrillar Networks. 25, 5886-5896


[13] Rogers, M.A., Wright, A.J., Maranoni, A.G., 2009.  Oil Organogels: The Fat of the Future.  Soft Matter. 5, 8, 1594-1596.


[12] Rogers, M.A. 2009.  Solidfying Unsaturated Oils Without Trans or Satuarted Fats: The Hardstock of the Future Food Engineering & Ingredients.  34; 23-25.


[11] Rogers, M.A., Wright, A.J., and Marangoni, A.G.  2009.  Nanostructuring fibre morphology and solvent inclusions for 12 hydroxystearic acid/canola oil organogels.  Current Opinion in Colloid and Interface Science.  14, 33-42.


2008


[10] Rogers, M.A., and Marangoni, A.G. 2008.  Non-isothermal nucleation and crystallization of 12HSA in vegetable oil. Crystal Growth and Design.  8; 4596-4601.


[9] Rogers, M.A., and Marangoni, A.G., 2008. Effect of enthalpy and entropy on SAFiN structure.  Journal of Physics D. 41; 215501.


[8] Rogers, M.A., Wright, A.J., and Marangoni, A.G. 2008.  Crystalline stability of self-assembled fibrillar networks of 12-hydroxystearic acid in edible oils.  Food Research International. 41, 1026-1034.


[7] Rogers, M.A., Wright, A.J., and Marangoni, A.G.  2008.  Engineering the oil binding capacity and crystallinity of self-assembled fibrillar networks of 12-hydroxysteric acid in edible oils.  Soft Matter.  4; 1483-1490.


2007


[6] Rogers, M.A., Smith, A.S., Wright, A.J., and Marangoni, A.G. 2007.  A Novel Imaging Technique for Vegetable Based Organogels.  Journal of American Oil Chemists Society. 84; 899-906.


[5]  Marilyn Griffith, Mary Timonin, Annie C.E. Wong, Gordon R. Gray, Sajjad R. Akhter, Marsha Saldanha, Michael A. Rogers, Elizabeth A. Weretilnyk, Barbara Moffatt.  2007.  Adaptation of Thellungiella salsuginea to cold temperatures.  Plant Cell and Environment.  Vol. 30; 529-538


2006


[4] Rogers, M.A., Roos, Y.H., Goff, H.D. 2006.  Structural heterogeneity and its effects on the glass transition in sucrose solutions containing protein and polysaccharide.  Food Hydrocolloids.  Vol. 20. pp. 774-779.


[3] Rogers, M.A., Wright, A.J., and Marangoni, A.G. 2005.  Microstructure of fat crystallizing on a collagenous surface.  Special Issue on Lipid Structure and fat crystallization. European Journal of Lipid Science. 107; 684-688.


[2] Awad, T.S., Rogers, M.A., Marangoni, A.G.  2004.  Scaling behavior of the elastic modulus in colloidal networks of fat crystals.  Journal of Physical Chemistry B.  Vol. 108.  pp. 171-179.


[1] Marangoni, A.G. and Rogers, M.A., 2003.  Structural basis for the yield stress in plastic disperse systems.  Applied Physics Letters.  Vol. 82.  No. 19. pp. 3239-3241.



Book Chapter Contributions



[7] Rogers, M.A.,* 2014. Self-assembled fibrillar networks of low molecular weight oleogelators. In Edible Nanostructures: A Bottom-Up Approach. (A.G. Marangoni & D. Pink) Royal Society of Chemsitry. Cambridge, UK.


[6] Rogers, M.A.,* and Spagnuolo, P.A. 2014. Functional Foods. In Encyclopedia of Agriculture, Food and Biological Engineering, Second Edition. (D.R. Heldman & C.I. Moraru) Taylor & Francis. New York. Accepted.


[5] Rogers, M.A.,  12-Hydroxystearic Acid Oleogels.  2011.  In Edible Oleogels.  (A.G. Marangoni & N. Garti) AOCS Press.


[4] Rogers, M.A.,  Ceramide Oleogels.  2011.  In Edible Oleogels.  (A.G. Marangoni & N. Garti) AOCS Press.


[3] Rogers, M.A. Novel Lipid Substitutes. 2011. In Comprehensive Biotechnolgoy 2ed.  Vol 4: Agricultural and Related  Biotechnologies, Section 3: Food Systems. (M. Moo-Young). Elsevier, Amsterdam.


[2] Rogers, M.A., Alhamdi, L. Tang, D., and Marangoni, A.G.  2007.  Fat Crystal Networks.  In Food Material Science.  (J.M. Aguilera & P.J. Lillford, editors). Springer Verlag, Germany.  Pp. 369-414.


[1] Awad, T.S., Rogers, M.A., Marangoni, A.G.  2004.  Scaling behavior of the elastic modulus in colloidal networks of fat crystals.  In:  “Fat Crystal Networks” A.G. Marangoni, ed.  New York. Pp. 349-380.



Conference Presentations


[25] Rogers, M.A., Lan, Y., Sparannza, A., Influence of Emulsifier Structure on Lipid Bioaccessibility in Oil-Water Nanoemulsions.
American Oil Chemists Society, San Antiano, TX, May 3-8, 2014.


[24] Du, H., and Rogers, M.A., The Effect of Liquid Oil on the Crystallization of Fat Crystal Networks. New York and Central New Jersey International Food Technologists Meeting. New Brunswick, NJ. February 20, 2014.


[23] Lan, Y., and Rogers, M.A. Comparing Solubility Parameters to Understand Self-Assembly in Molecular Gels. The Case of 1,3:2,4-Dibenzylidene Sorbitol (DBS), A Potential Fat Replacer. New York and Central New Jersey International Food Technologists Meeting. New Brunswick, NJ. February 20, 2014.


[22] Fondaco, D., AlHasawi, F., and Rogers, M.A. Viscoelastic Differences and Particle Size Distributions of Similac Infant Formulations and Breast Milk and their Implications for Obesity Risks. New York and Central New Jersey International Food Technologists Meeting. New Brunswick, NJ. February 20, 2014.


[21] Rogers, M.A. Probing Solubility Parameters Governing Self-Assembly of Molecular Gels. William Paterson University. Chemistry Seminar Series. Wayne, NJ. March 27, 2014.


[20]  Rogers, M.A., Spernaza, A.  Biophysics of Lipid Digestion.  TIM User Meeting.  Barcelona, Spain, March 14, 2013


[19] Gao, J. and Wu. S. and Rogers, M.A. 2013 Harnessing Hansen Solubility Parameters To Predict Organogel Formation. American Oil Chemists Society Meeting.  Montreal, Ontario, Canada.  April 28-May1, 2013.


[18]  AlHassawi, F. and Rogers, M.A. 2013 Ternary Phase Diagram of B-Sitosterol, G-Oryzanol and Canola Oil—A Gamut of Materials from Glasses to liquid Crystals.  American Oil Chemists Society Meeting.  Montreal, Ontario, Canada.  April 28-May1, 2013.


[17] Wu, S., Gao, J., and Rogers, M.A. Harnessing Solubility Parameters to Predict Organogel Formation.  American Chemical Society.  Philadelphia PA, USA, August 2012.


[16] Rutherford, H., Low, N.H., Rogers, M.A. Effect of chain length on liposome wall structure.  International Symposium on Colloids and Materials.  Amsterdam, The Neatherlands. May 8-11, 2011. 


[15] Lam, R.H.S., Pedersen, T., Bot A., May, T., Rogers, M.A. Multi-Component Hollow Nano-Tubes Formed Using Phytosterol and γ-Oryzanol Based Compounds.  Canadian Light Source Annual Users Meeting.  Saskatoon, SK. June 16-18, 2010


[14] Lam, R.H.S., Quaroni, L., Pedersen, T., T., Rogers, M.A. A Molecular Insight into the Nature of Crystallographic Mismatches in Self-Assembled Fibrillar Networks. Canadian Light Source Annual Users Meeting.  Saskatoon, SK. June 16-18, 2010


[14] Rogers, M.A. Food Grade Gelators: The Evolution of Lipid Structuring. American Oil Chemists Society.  Phoenix, Arizona, USA, May 16-20, 2010.


[13] Lam, R.H-S. And Rogers, M.A. Experimental Validation of the Modified Non-Isothermal Avrami Model for 1D Fibrillar, 2D Platelet and 3D Spherulitic Crystal Growths. American Oil Chemists Society.  Phoenix, Arizona, USA, May 16-20, 2010.


[12] Rutherford, H., Lam, R., Pederson, T., Quaroni, L. and Rogers, M.A. Engineering Crystallographic Mismatches of Self-Assembled Fibrillar Networks: Shedding Synchrotron Light on a Molecular Problem. American Oil Chemists Society.  Phoenix, Arizona, USA, May 16-20, 2010.


[11] Rogers, M.A. Ceramide Organogels.  American Oil Chemists Society.  Orlando, Florida, USA, May 3-6, 2009.


[10] Rogers, M.A., Wright, A.J., and Marangoni, A.G. 2008.  Gelled Oil: The Fat of the Future?  World Congress. International Union of Food Science and Technology.  Young Scientist Award Lecture.  Shanghai, China, October, 18-24, 2008.


[9] Rogers, M.A., Wright, A.J., and Marangoni, A.G.  2008.  Engineering Oil-Binding Capacity and Crystallinity of Organogels. Meeting of the American Oil Chemists Society. Seattle, USA, May 18-21, 2008.


[8] Hughes, N.E., Rogers, M.A., and Marangoni, A.G.  2008.  The Physical and Functional Properties of Vegetable Oil Organogels.  Annual Meeting of the American Oil Chemists Society. Seattle, USA, May 18-21, 2008.


[7] Marangoni, A.G., and Rogers, M.A.  2007.  Exploiting Small-Molecule Self-Assembly Properties to Create Edible Supramolecular Structures.  5th EuroFed Lipid Conference.  Gothenburg, Sweden, Sept 16-19, 2007.


[6] Rogers, M.A., Wright, A.J., Smith, S.A., and Marangoni, A.G.  A Novel Imaging Technique for Vegetable Oil Based Organogels.  Annual Meeting of the American Oil Chemists Society. Quebec, QC, Canada, May 12-16, 2007.


[5] Rogers, M.A., Wright, A.J., and Marangoni, A.G.  2006.  Structure and Properties of 12-Hydroxystearic Acid/Canola Oil Gels.  Annual Meeting of the American Oil Chemists Society. St. Louis, Missouri, USA, May 2-5, 2006.


[4] Rogers, M.A., and Marangoni, A.G.  2007.  Nanostructuring fiber morphology and solvent inclusions for 12-hydroxystearic acid/canola oil organogels.  ICMR program on polymeric and self assembled gels. University of California, Santa Barbara, USA, August 5-18, 2007.


[3] Rogers, M.A., Goff, H.D., Roos, Y.H.  Protein/polysaccharide induced structural heterogeneity:  the effect on the glass transition temperature and enzyme kinetics.  Annual Meeting for International Food Technology.  Las Vegas, Nevada, USA.  July 22-24, 2004.


[2] Awad, T., Rogers, M.A., Marangoni, A.G . Scaling behaviour of the elastic modulus with SFC in fats. Annual Meeting of the American Oil Chemists Society. Kansas City, Missouri, USA, May 4-7, 2003.


[1] Rogers, M.A. and Marangoni, A.G. Rheological determination of the fractal dimension of a fat crystal networks. Annual Meeting of the American Oil Chemists Society.  Montreal, QC, Canada, May 5-8, 2002.


Patents  


[2] Rogers, M.A., 2012. Thermo-reversible Phase Selevtive Xerogel Compositions. US Provisional Patent Application. No. 61/735731


[1] Rogers, M.A., Wright, A.J. and Marangoni, A.G. 2008. US Provisional Patent Application No.61/071761.  Organogelator.