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A new Janus-type cyclodextrin (CD) molecular tube bearing seven triisopropylsilyl (TIPS) groups at one end is synthesized from a heptakis(6-O-triisopropylsilyl)-β-cyclodextrin (TIPS-β-CD) dimer possessing multiple linkers through the selective removal of seven TIPS groups at the other end. This Janus-type CD tube exhibits a selective inclusion ability for a cis-fatty acid ester over the corresponding trans-fatty acid ester. In addition, the CD tube shows a twofold higher inclusion ability for unsaturated fatty acid esters than the corresponding CD tube bearing seven tert-butyldimethylsilyl (TBDMS) groups, indicating that the molecular size of the terminal substituents remarkably affects the inclusion ability of the CD tube.

International audience; Cell wall polysaccharides (CWPs) and phenolic substances, e.g., procyanidins, widely co-exist in fruit and vegetables and interact in complex patterns during chewing, food processing and in vivo digestion, impacting the food physicochemical and nutritional qualities. Interactions were characterized between two procyanidins and heterogeneous CWPs (four native and twelve modified) from apple, beet and kiwifruit presenting various chemical compositions and physical structures. ATR-FTIR discriminated the complexes from the initial purified procyanidins and CWPs. Langmuir isotherms and ITC indicated that native CWPs, from all botanical origins, had a higher affinity for procyanidins than the modified ones, which were all poorer in pectins. The CWPs thatinteract more with procyanidins were characterized by their high pectin content and linearity, and high porosity. Increasing the molecular size of procyanidins increased their complexation with CWPs. This work is an important guide to the encapsulation and controlled release of active compounds and the subsequent respective digestive behavior and human health.

A single-head/single-tail surfactant with a polymerizable group at each end is presented as a new simplified motif for intrinsically cross-linkable, gyroid-phase lyotropic mesogens. The resulting nanoporous polymer networks exhibit excellent structural stability in various solvents and are capable of molecular size discrimination.

Description, Cascaded microporosity localized on membrane surfaces markedly improved selective transport of small molecules., In membrane-based separation, molecular size differences relative to membrane pore sizes govern mass flux and separation efficiency. In applications requiring complex molecular differentiation, such as in natural gas processing, cascaded pore size distributions in membranes allow different permeate molecules to be separated without a reduction in throughput. Here, we report the decoration of microporous polymer membrane surfaces with molecular fluorine. Molecular fluorine penetrates through the microporous interface and reacts with rigid polymeric backbones, resulting in membrane micropores with multimodal pore size distributions. The fluorine acts as angstrom-scale apertures that can be controlled for molecular transport. We achieved a highly effective gas separation performance in several industrially relevant hollow-fibrous modular platform with stable responses over 1 year.

Understanding the relation between chemical characteristics and properties of synthetic polymers is one of the challenges faced by analytical chemists in industry. This is a complex task, as polymers are not synthesized as single molecule, but are populations of chemically similar compounds with distributions over several properties. The latter include, for example, molecular weight, nature of end-groups (functionality), and chemical composition. In this paper, comprehensive two-dimensional liquid chromatography was used to determine the combined functionality-type and molecular-weight distributions of hydroxy-functionalized propoxylates. Propoxylates derived from different initiators (one up to eight terminal hydroxyl groups) were separated in the first dimension using a gradient normal-phase LC separation (NPLC). In the second dimension ultra-high pressure size-exclusion chromatography separation (UHPSEC), further speciating distributions based on molecular size. The developed NPLC x SEC method with evaporative light-scattering detection can be used for the fast screening (< 30 min) of mutually dependent functionality-type and molecular weight distributions of unknown propoxylates. (C) 2021 The Authors. Published by Elsevier B.V.

Active-polymer attracted increasing interest as an enhancing oil recovery technology in oilfield development owing to the characteristics of polymer and surfactant. Different types of active functional groups, which grafted on the polymer branched chain, have different effects on the oil displacement performance of the active-polymers. In this article, the determination of molecular size and viscosity of active-polymers were characterized by Scatterer and Rheometer to detect the expanded swept volume ability. And the Leica microscope was used to evaluate the emulsifying property of the active-polymers, which confirmed the oil sweep efficiency. Results show that the Type I active-polymer have a greater molecular size and stronger viscosity, which is a profile control system for expanding the swept volume. The emulsification performance of Type III active-polymer is more stable, which is suitable for improving the oil cleaning efficiency. The results obtained in this paper reveal the application prospect of the active-polymer to enhance oil recovery in the development of oilfields.

Zeolites with ordered porous structure of molecular size are widely employed as commercial adsorbents and catalysts. On the other hand, the zeolite matrix is regarded as an ideal scaffold for hosting coordinatively unsaturated sites. Remarkable achievements have been made dealing with the construction, characterization and catalytic applications of coordinatively unsaturated sites in zeolite matrix. Herein, a literature overview of recent progresses on this important topic is presented from the specific view of coordination chemistry. Different strategies to construction coordinatively unsaturated sites in zeolite matrix, in zeolite framework or extraframework positions, are first introduced and their characteristics are compared. Then, spectroscopic techniques to determine the existing states of cation sites and their transformations in zeolite matrix are discussed. In the last section, the catalytic applications of coordinatively unsaturated sites in zeolite matrix for various important chemical transformations are summarized.

Oxidative stress initiates, accompanies and contributes to the development of several human diseases and injuries, including ocular diseases. Reactive oxygen species (ROS) can generate oxidative stress via excessive ROS production and/or decreased physiologically occurring antioxidants. To replace these weakened antioxidants, substances with effective antioxidant properties are needed in order to suppress oxidative stress and enable healing. Molecular hydrogen (H2) is very suitable for this purpose due to its unique properties. H2 is the only antioxidant that crosses the blood-brain and blood-ocular barriers. It quickly penetrates through tissue due to its small molecular size and effectively removes ROS, mainly hydroxyl radicals and peroxynitrite. Apart from its antioxidant effects, H2 also displays anti-inflammatory, antiapoptotic, cytoprotective and mitohormetic properties. A significant advantage of H2 is its nontoxicity, even when applied at high concentrations. In this review, we present the results of studies utilising H2 in the treatment of ocular diseases involving oxidative stress. These results, obtained in experimental animals as well as in human clinical studies, show that the suppression of oxidative stress by H2 treatment leads to the prevention or improvement of ocular diseases. In severe degenerative diseases, H2 slows disease progression.

Kafirin, sorghum prolamin, was investigated as a coprotein for zein as visco-elastic masses and in starch-based model doughs. Regular kafirin and kafirins from waxy and high protein digestibility (HD) sorghum crosses were studied. HPLC revealed that waxy-HD kafirin was of smaller molecular size and low in β-kafirin. It also had greater surface hydrophobicity. Kafirin addition to zein increased visco-elastic mass elasticity up to ≈50% stress-recovery, similar to wheat gluten. Waxy-HD kafirin gave the highest elasticity, possibly due to its hydrophobicity. Kafirin inclusion at 2:8 parts zein increased the tensile strength of model doughs. Maximum strength was, however, only 60% that of gluten-based dough. Kafirin from regular sorghum gave the highest strength, possibly because of greater disulphide-bonded polymerisation. Confocal laser scanning microscopy showed that zein-kafirin copolymers formed fairly linear fibrils in stretched doughs, indicating excellent compatibility between the proteins. Future research should establish how kafirin-zein copolymer performs in non-wheat flour products.

Dissolved organic matter (DOM) in sediments of polluted rivers significantly contributes to oxygen consumption and river blackening and odorization. However, the chemodiversity of DOM at different depths or river reaches is poorly known. Here, we studied the storage and molecular-level signatures of water-extractable organic matter (WEOM) in the sediment column (0–100 cm) of the upper, middle, and lower mainstream of Maozhou River (a polluted river in Shenzhen, China, with 40 years of urbanization) using optical spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. The sediment WEOM level increased from upstream to downstream. The relative abundances of sulfur-containing surfactants in all sediment WEOM were higher than those previously reported for surface water DOM. The WEOM in surface sediment had higher aromaticity, molecular size, and nominal oxidation state of carbon and greater signals from anthropogenic inputs than did deep sediment at the upper and middle mainstream sites. However, these characteristics varied little between surface and deep sediments at the lower mainstream site, probably due to intensive surface water and pore water interactions. The sediment WEOM at 0–40 cm in the middle mainstream showed a greater anthropogenic signature (e.g., more surfactant and dissolved black carbon contributions) than any other sediment. We demonstrate strong anthropogenic impacts on the surface sediment over decades of urbanization.

Plastics are synthetic polymers that are lightweight and exhibit a high tensile strength, durability, and chemical inertness, leading to a host of applications. However, these same properties make their degradation difficult and have resulted in significant accumulation in the environment. Plastic characteristics include hydrophobicity, degree of crystallinity, molecular size of the constituent polymer, etc. Each character plays a crucial role in plastic biodegradability. The low degradation rates and the subsequent effect on ecology is a major environmental concern. Considerable ongoing research is focusing on the biodegradation of plastics and bioplastics by various microorganisms and their constituent enzymes. These biocatalysts are specific to the constituent functional groups, degree of polymerization, etc. The breakdown rates and composition of the final products depend on several factors including physical and chemical pretreatments. Unlike recycling and composting, these studies aim to break down the plastics to monomeric or short-chain polymers that can be reused. The obtention of reusable “end-of-life” monomers or oligomers and re-introduction into the production cycle will help to complete the loop and the use of plastics from a linear to a circular bioeconomy. Such processes will reduce the original resource input with each complete cycle making the process much more sustainable. With this knowledge, the development of new plastics will move toward the products that can be broken down into reusable compounds after its end-use. This chapter will review the degradability potential of plastics and bioplastics to reusable materials that can be adapted by the plastic industry for a cascading circular bioeconomy.

This chapter describes the basic principles of viscometry using simple glass capillary viscometers and differential viscometers suitable for online use as chromatography detectors. Relationships between intrinsic viscosity and both molecular weight and molecular size are discussed, as are methods for using intrinsic viscosity data to estimate chain flexibility. Recent important developments in using viscosity data for molecular characterization of polymers are summarized.

Star-shaped polymers are very attractive because of their potential application ability in various technological areas due to their unique molecular topology. Thus, information on the molecular structure and chain characteristics of star polymers is essential for gaining insights into their properties and finding better applications. In this study, we report molecular structure details and chain characteristics of 17-armed polystyrenes in various molecular weights: 17-Arm(2k)-PS, 17-Arm(6k)-PS, 17-Arm(10k)-PS, and 17-Arm(20k)-PS. Quantitative X-ray scattering analysis using synchrotron radiation sources was conducted for this series of star polymers in two different solvents (cyclohexane and tetrahydrofuran), providing a comprehensive set of three-dimensional structure parameters, including radial density profiles and chain characteristics. Some of the structural parameters were crosschecked by qualitative scattering analysis and dynamic light scattering. They all were found to have ellipsoidal shapes consisting of a core and a fuzzy shell, such ellipse nature is originated from the dendritic core. In particular, the fraction of the fuzzy shell part enabling to store desired chemicals or agents was confirmed to be exceptionally high in cyclohexane, ranging from 74 to 81%, higher-molecular-weight star polymer gives a larger fraction of the fuzzy shell. The largest fraction (81%) of the fuzzy shell was significantly reduced to 52% in tetrahydrofuran, in contrast, the lowest fraction (19%) of core was increased to 48%. These selective shell contraction and core expansion can be useful as a key mechanism in various applications. Overall, the 17-armed polystyrenes of this study are suitable for applications in various technological fields including smart deliveries of drugs, genes, biomedical imaging agents, and other desired chemicals.

Humic substances (HS) are powerful natural plant biostimulants. However, there is still a lack of knowledge about the relationship between their structure and bioactivity in plants. We extracted HS (THE1-2) from two forest soils covered with Pinus mugo (1) or Pinus sylvestris (2). The extracts were subjected to weak acid treatment to produce size-fractionated HS (high molecular size, HMS1-2; low molecular size, LMS1-2). HS were characterized for total acidity, functional groups, element and auxin (IAA) contents, and hormone-like activity. HS concentrations ranging from 0 to 5 mg C L−1 were applied to garlic (Allium sativum L.) plantlets in hydroponics to ascertain differences between unfractionated and size-fractionated HS in the capacity to promote mineral nutrition, root growth and cell differentiation, activity of enzymes related to plant development (invertase, peroxidase, and esterase), and N (nitrate reductase, glutamine synthetase) and S (O-acetylserine sulphydrylase) assimilation into amino acids. A positive linear dose-response relationship was determined for all HS in the range 0–1 mg C L−1, while higher HS doses were less effective or ineffective in promoting physiological-biochemical attributes of garlic. Bioactivity was higher for size-fractionated HS according to the trend LMS1-2>HMS1-2>THE1-2, with LMS2 and HMS2 being overall more bioactive than LMS1 and HMS1, respectively. LMS1-2 contained more N, oxygenated functional groups and IAA compared to THE1-2 and HMS1-2. Also, they exhibited higher hormone-like activities. Such chemical properties likely accounted for the greater biostimulant action of LMS1-2. Beside plant growth, nutrition and N metabolism, HS stimulated S assimilation by promoting the enrichment of garlic plantlets with the S amino acid alliin, which has recognized beneficial properties in human health. Concluding, this study endorses that i) treating THE with a weak acid produced sized-fractionated HS with higher bioactivity and differing in properties, perhaps because of novel molecular arrangements of HS components that better interacted with garlic roots; ii) LMS from forest soils covered with P. mugo or P. sylvestris were the most bioactive; iii) the cover vegetation affected HS bioactivity iv); HS stimulated N and S metabolism with relevant benefits to crop nutritional quality.

Flavonoids are the main constituents of Goji berries and have good biological and pharmacological activities. The mixed-mode macroporous adsorption resins (MARs) for purification of flavonoids from Goji berries through computer-assisted calculation of the molecular size of flavonoids and the precise matching of MAR physical and chemical properties was firstly developed in the present study. Ten varieties of MARs with suitable molecular dimensions and polarities were used for investigating the adsorption/desorption behaviors of the flavonoids. Both AUKJ-1 and BWKX-1 showed higher separation efficiency than other MARs and then were mixed in different ratios to constitute a mixed-mode macroporous adsorption resin to obtain the optimal adsorption phase. Under optimal conditions, total flavonoid content of purified flavonoid (p-FLA) extract increased from 0.97% to 36.88% after one purification. The p-FLA extract from Goji berries significantly improved the expression of six genes with anti-aging effects and played an important role in aging-related Alzheimer&rsquo, s disease by down-regulating A&beta, expression.

Small-molecule crosslinkers could diffuse into and stabilize protein hydrogels without damaging their appearance, but they are absent from the food industry due to the high safety and efficacy requirements for foods. Oxidized oligosaccharides are non-toxic small polyaldehydes previously found capable of crosslinking proteins by premixing. In this study, we managed to diffuse various oxidized oligosaccharides into the protein wall of rehydrated sea cucumbers, and the texture profile analysis, total soluble material assay and SEM (scanning electron microscope) images all suggested the treated sea cucumbers acquired significantly enhanced stability against high-temperature-promoted deterioration. The stabilization was positively correlated with the aldehyde content of oxidized oligosaccharides but negatively correlated with molecular size. The mechanism of stabilization was found to include both covalent and hydrogen bond crosslinking. These results have demonstrated that oxidized oligosaccharides could enter food protein hydrogel by free diffusion and stabilize the 3D network effectively and thereby has great potential in food-related industry.

Ineffectiveness of the chemicals applied so far for waterlogged wood conservation created the need to develop new more, efficient and reliable agents. As an alternative, a new method with the use of organosilicon compounds differing in chemical composition and molecular weight has been investigated. The results obtained show the potential of organosilicons as consolidants in waterlogged wood conservation able to effectively stabilise wood dimensions upon drying. The best wood stabilisers were low-molecular organosilicons enable to penetrate the cell wall as well as chemicals with functional groups capable of interacting with wood polymers and forming stabilising coatings on the cell wall surface. The best anti-shrink efficiency values were obtained for (3-Mercaptopropyl)trimethoxysilane, (3-Aminopropyl)triethoxysilane, 1,3-Bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, reaching 98, 91 and 91%, respectively. Most of the applied organosilicons reduced wood hygroscopicity, which limits the risk of further dimensional changes of wood exposed to a variable air moisture content and potentially reduces wood biodegradation. In the light of our studies, the proposed method of waterlogged wood conservation with organosilicons is potentially reversible in the case of siloxanes and amino-silanes as well as retreatable, which complies with the requirements of the conservation ethics.

Impact of extrusion pretreatment (50, 70, 90, 110 and 130 °C) on physicochemical, emulsifying properties and water holding capacity (WHC) of transglutaminase (TGase) cross-linked whey protein isolate (WPI) were investigated in this study. The results of molecular size distribution and SDS-PAGE proved that there were more macromolecular polymers formed in TGase cross-linked WPI after extrusion pretreatment (E-WPI-TGase) and the consumption of free amino groups for E-WPI-TGase was the largest at the extrusion temperature of 50 °C and 70 °C. As the extrusion temperature increased from 90 °C to 130 °C, particle size of WPI after extrusion pretreatment (E-WPI) was not changed significantly, compared with that of E-WPI-TGase (p > 0.05). In addition, the emulsifying properties, surface hydrophobicity and WHC of E-WPI-TGase were higher than those of WPI cross-linked by TGase (WPI-TGase) (p

White wheat salted noodles containing oats have a slower digestion rate those without oats, with potential health benefits. Oat β-glucan may play an important role in this. Effects of sheeting and shearing during noodle-making and subsequent cooking on β-glucan concentration, solubility, molecular size and starch digestibility were investigated. The levels of β-glucan were reduced by 16% after cooking, due to the loss of β-glucan into the cooking water. Both the noodle-making process and cooking increased the solubility of β-glucan but did not change its average molecular size. Digestion profiles show that β-glucan in wholemeal oat flour did not change starch digestion rates compared with isolated starch, but reduced the starch digestion rate of oat-fortified wheat noodles compared to the control (wheat noodles). Confocal laser scanning microscopy suggests that interaction between β-glucan and protein contributes to the starch-protein matrix and changes noodle microstructure, and thus alters their digestibility.

A variety of bioactivities has been established for fucoidan extracted from sea cucumber, whereas its structure-activity relationships have been seldom investigated. In this study, sea cucumber ( Thelenota ananas) fucoidans with different molecular weights were prepared with enzymatic degradation. The chain stiffness and molecular size decreased with the decreasing of molecular weight. Fucoidans with molecular weight of 1380.0, 828.7, and 483.0 kDa exhibited random coil conformations, while fucoidan molecular weight of 215.0 kDa existed as sphere in solution. All examined fucoidans could effectively prevent the ethanol-induced gastric ulcer, of which mechanism involved antioxidation and anti-inflammation. Within the range of the study, the performance of fucoidans adopted random coil conformations declined with the decreasing of molecular weight, and the performance recovered when the chain conformation transited from coil to sphere, indicating the subtle influences of molecular weight and chain conformation on the gastric protective activity of sea cucumber fucoidan.

Fundamental knowledge of physicochemical properties of polymeric food materials is of practical importance in food and pharmaceutical industry. Effects of water, molecular weight, and lactose addition on glass transition temperature (Tg), α-relaxations, and relaxation time (τ) of amorphous poly (vinyl pyrrolidone) (PVP) and maltodextrin (MD) were studied at various aw and 25 °C. Water sorption behaviour of amorphous PVP and MD was Mwavg–dependent at aw ≤ 0.44, whereas the molecular size effects dominated the sorption process of MD at aw ≥ 0.56 and 25 °C. Fractional water sorption was confirmed in studied polymers/lactose mixtures at aw ≤ 0.44 in molecular scale, whilst collapsed structure of above mixtures were observed at aw ≥ 0.44 during storage up to 20 days at 25 °C. Despite of the calorimetric onset Tg of amorphous polymers/lactose mixtures showed a composition-independent at aw ≤ 0.44, Tg, α-relaxation, and τ of PVP and MD were disturbed by water, molecular weight and size, and adding lactose. Structural strength (S) of PVP was determined by its molecular weight at aw ≤ 0.44, whereas molecular size dominated the S of MD at 0.44 ≤ aw ≤ 0.76 due to water migration. The changes of aw and lactose addition significantly disturbed the S of studied polymers. Moreover, a combined use of water sorption isotherm and the relationship of S and aw gave a quantitative measurement of compositional effects and could be used to control the physicochemical properties of amorphous food polymers, such as collapse.

Herein, the Keggin structural phosphotungstic acid (HPW) has been successfully encapsulated within hollow microporous polymer nanospheres (H-MPNs) by a “ship-in-bottle” approach. The H-MPNs are formed by self-assembly induced by hyper-crosslinking of polylactide-b-polystyrene (PLA-b-PS). The obtained catalysts (HPW@H-MPNs) exhibit more sustainable availability than the previously reported HPW-supported catalysts in esterification reaction. This excellent sustainability can be attributed to the stable microporous channels in H-MPNs which are smaller than the molecular size of HPW, thereby effectively preventing the HPW from leaking out. Moreover, such catalysts also perform well in terms of catalytic activity and universality because of the combination of a hollow structure in the interior and permeable pore channels in the shells. This type of polymer carrier and general encapsulation method may provide a new strategy for developing more sustainable catalysts for various chemical reactions.

Enotannin and mannoprotein additives are applied to achieve protein, cold, or color stability in wine, or to modify wine sensory properties. In most cases, the manufacturer only provides basic compositional information and a proposed effect in wine. In this study, 14 grape-based enotannins and eight mannoproteins were sourced from the Australian market, and their composition and molecular size distribution were determined. Diverse product composition was observed for both categories, suggesting that a range of effects could potentially be achieved by applying different products. Moreover, some products showed good agreement between product composition and their designated material of origin, while others showed significant differences.

The aim of this study was to produce and characterize inclusion complexes (IC) between β-cyclodextrin (β-CD) and orange essential oil (OEO) or eucalyptus essential oil (EEO), and to compare these with their pure compounds and physical mixtures. The samples were evaluated by chemical composition, morphology, thermal stability, and volatile compounds by static headspace-gas chromatography (SH-GC). Comparing the free essential oil and physical mixture with the inclusion complex, of both essential oils (OEO and EEO), it was observed differences occurred in the chemical composition, thermal stability, and morphology. These differences show that there was the formation of the inclusion complex and demonstrate the necessity of the precipitation method used to guarantee the interaction between β-CD and essential oils. The slow loss of the volatile compounds from both essential oils, when complexed with β-CD, showed a higher stability when compared with their physical mixtures and free essential oils. Therefore, the results showed that the chemical composition, molecular size, and structure of the essential oils influence the characteristics of the inclusion complexes. The application of the β-CD in the formation of inclusion complexes with essential oils can expand the potential applications in foods.

Background: FSH, LH, and TSH are glycoprotein hormones secreted from the pituitary as fully and low-asparagine-glycosylated hormones. These glycoforms of the hormones exist as a large number of isoforms varying in their glycan contents of terminal anionic monosaccharides (AMS), i.e. sialic acid (SA) and sulfonated N-acetylgalactosamine (SU). Due to the immense heterogeneity and the low concentrations in serum it has been a challenge to develop reliable analytical methods to measure and characterize the circulating glycoforms of these hormones. Methods: The hormones were separated with respect to AMS content per molecule by calibrated 0.1% agarose suspension electrophoreses. Glycoforms in separated fractions were then analyzed with respect to size by 180 calibrated Sephadex G-100 gel filtrations. The hormones were measured with time-resolved sandwich fluoroimmunoassays. All separations and assays were performed in veronal buffer at pH 8.7. Sera and fractions were also analyzed after removal of terminal SA. Results: In addition to the fully glycosylated FSH, LH, and TSH, also tri-glycosylated FSH and di-glycosylated LH and TSH forms could be identified in serum samples. The low- and fully glycosylated hormones differed both with respect to size and to median number of AMS per molecule. Algorithms, based on the distributions by electrophoreses, were developed for each hormone to estimate percent low-glycosylated forms in serum. The median numbers of SA and SU per glycoform molecule were estimated using results obtained after desialylation. Conclusion: The methods can be used for identification and characterization of glycoforms of circulating FSH, LH, and TSH in physiological and clinical studies.

Carbohydrates and ginsenosides in ginseng are biologically interrelated. Their synchronous analysis is therefore essential in chemical research on ginseng to characterize its "holistic" quality. Here we investigated the processing chemistry of red ginseng (RG), a ginseng product processed by water-steaming, for which both carbohydrates and ginsenosides were qualitatively and quantitatively determined through multiple analytical techniques. Results revealed that the steam-processing not only qualitatively and quantitatively altered the ginsenosides but also affected the polymeric carbohydrates via changing their physiochemical parameters, i.e. water-solubility, molecular size, types and ratios of constituent monosaccharides. Potential mechanisms involved in the transformation of ginseng chemicals are proposed and discussed, including hydrolysis (deglycosylation, demalonylation, deacetylation), dehydration, polymerization, volatilization, reduction and the Maillard reaction. The study strengthens the research on the processing chemistry of RG, and therefore should be helpful for elucidating the scientific basis of RG preparation and application.

Polymer membranes are typically used to separate gas mixtures on the basis of molecular size differences (“sieving”). The gas purity is known to be inversely proportional to the membrane flux, and the slope of this plot in glassy polymers is empirically found to be determined by the sizes of the gas molecules being separated, λ = (dB/dA)2 – 1. Despite potential mechanistic differences, the separation performance of rubbery polymers is often discussed in the same framework as their glassy counterparts. Here we perform molecular dynamics simulations of spherical solutes in coarse-grained high-density, high temperature polymer melts to gain a molecular understanding of their transport and separation behavior. We find that the diffusion coefficient follows an exponential law D ∼ e–ad. Since this dependence results in λ = dB/dA – 1, these findings do not provide a direct understanding of the experimentally deduced slope of the Robeson plot.

Accurate characterization of hydrogel diffusional properties is of substantial importance for a range of biotechnological applications. The diffusional capacity of hydrogels has commonly been estimated using the average molecular weight between crosslinks (Mc ), which is calculated based on the equilibrium degree of swelling. However, the existing correlation linking Mc and equilibrium swelling fails to accurately reflect the diffusional properties of highly crosslinked hydrogel networks. Also, as demonstrated herein, the current model fails to accurately predict the diffusional properties of hydrogels when polymer concentration and molecular weight are varied simultaneously. To address these limitations, we evaluated the diffusional properties of 48 distinct hydrogel formulations using two different photoinitiator systems, employing molecular size exclusion as an alternative methodology to calculate average hydrogel mesh size. The resulting data were then utilized to develop a revised correlation between Mc and hydrogel equilibrium swelling that substantially reduces the limitations associated with the current correlation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1339-1348, 2018.

Adsorption equilibria of imidazolium-based ionic liquids (ILs), [Omim]Cl, [Hmim]Cl and [Bmim]Cl, onto activated carbon from aqueous solutions were measured using a dynamic fixed-bed method at temperatures from 303 to 323 K. The measured amount of adsorbed IL increased with an increase in alkyl chain length of cation as [Omim]Cl > [Hmim]Cl > [Bmim]Cl, and this trend can be explained by hydrophobicity of the IL. The amount of adsorbed ILs decreased with an increase in temperature and ranged from 0.70 to 0.61 mmol/g-adsorbent at a concentration of 1.2 mol/m3 for the case of [Omim]Cl. Fitting parameters in the Dubinin-Astakhov (DA) equation determined with correlation of the experimental data, E (interaction energy between IL and adsorbent) and q0 (saturated adsorption amount of IL), increased with an increase in the alkyl chain length of cation, and that could be clearly related to the physicochemical properties of the IL such as hydrophobicity and molecular size. Analysis of adsorption equilibrium data with the DA equation allows design of adsorption processes for ILs.

This study aimed to assess solar photocatalytic activity of Fe-doped TiO2 specimens for the degradation of natural organic matter (NOM) represented by a model humic acid (HA). Fe-doped TiO2 specimens (P-25 and UV-100) were prepared by a wet impregnation method. Humic acid (molecular size

This study aims to understand the environmental factors, focusing on rain and fungal infection, affecting the assembly of glutenin polymers during grain maturation. Spring wheat was grown in the field and grains were sampled from 50% grain moisture until maturity. Grain moisture content, protein content, size of glutenin polymers, the presence of proteases, and the amount of DNA from common wheat pathogenic fungi were analysed. Rain influenced the rate of grain desiccation that occurred parallel to the rate of glutenin polymer assembly. Rapid desiccation contributed to faster glutenin polymer assembly than gradual desiccation. Severe reduction in the glutenin polymer size coincided with increased grain moisture due to rain. Furthermore, increased fungal DNA followed by presence of gluten-degrading proteases was observed in the grain after humid conditions. The presence of gluten-degrading proteases was presumably involved in reducing the size of glutenin polymers in grain. Our study gave new insight into how environmental conditions could be associated with the assembly of glutenin polymers during grain maturation. The results suggest that rain and/or fungal proteases play an important role in reducing the molecular size of glutenin polymers.

ACE2 is an enzyme with a molecular size of more than 100 kDa which produces Angiotensin (1-7) from Angiotensin II (1-8). Attempts to target kidney RAS using ACE2 to treat kidney disease are hampered by its large molecular size which precludes its glomerular filtration and subsequent tubular uptake. We tested two ACE2 truncates (1-605 and 1-619AA) that we generated through truncation from the C terminus. ACE2 enzyme activity measured using Mca-APK-Dnp substrate was as high for each of them as native rACE2 (1-740 AA). The two truncates had an apparent MW of ~70 kDa, as expected from the amino acid sequence, as shown by western blot. For radioimaging each purified truncate was labeled with 99m Tc to study kidney uptake. After i.v. injection of Tc99m -labeled rACE2, there was kidney cortex retention for Tc99m 1-605 [8.6±0.7% of whole body (WB) radioactivity] and for Tc99m 1-619 (4.2±2.1% WB) as compared to only trace retention after injection of native Tc99m -rACE2 1-740 (1.2±0.2% WB)(figure). When infused to mice with genetic ACE2 deficiency, a single i.v. injection of 1-619 resulted in detectable ACE2 activity in urine and kidneys (23.1±4.3 and 1.96±0.73 RFU/ug prot/hr, respectively). In addition, the kidneys of ACE2-nul mice infused with 1-619 studied ex vivo formed more Ang (1-7) from exogenous Ang II than those of uninfused animals (p We conclude that our novel ACE2 truncates undergo glomerular filtration which is associated with kidney uptake of enzymatically active protein that can enhance formation of Angiotensin 1-7 from Angiotensin II (1-8). These truncates may offer a potentially useful approach to target kidney RAS overactivity to combat kidney disease.

Alkaline soda lignin (AL) was sequentially fractionated into six fractions of different molecular size by means of solvent extraction and their phenolic hydroxyl groups were chemoselectively methylated to determine their effect on nanoparticle formation of lignin polymers. The effect of the lignin structure on the physical properties of nanoparticles was also clarified in this study. Nanoparticles were obtained from neat alkaline soda lignin (ALNP), solvent-extracted fractions (FALNPs, i.d. 414–1214 nm), and methylated lignins (MALNPs, i.d. 516–721 nm) via the nanoprecipitation method. Specifically, the size properties of MALNPs showed a high negative correlation (R2 = 0.95) with the phenolic hydroxyl group amount. This indicates that the phenolic hydroxyl groups in lignin could be influenced on the nucleation or condensation during the nanoprecipitation process. Lignin nanoparticles exhibited high colloidal stability, and most of them also showed good in vitro cell viability. This study presents a possible way to control nanoparticle size by blocking specific functional groups and decreasing the interaction between hydroxyl groups of lignin.

While polysaccharides are the most abundant biomacromolecules widely distributed in nature, little is known in their chemical structures and functional mechanism. Compared with DNA and protein, polysaccharides possess more complex structures and composition with various molecular size, conformational shape and charge characteristic. Currently, the lack of a uniform and clear consensus of polysaccharide purity leads to low accuracy of structural analysis. In the present study, a new theory on polysaccharide purification named as “relative ordered structure” was proposed, which was used to purify the water-extracted polysaccharides from Hypsizygus marmoreus (SHMP), successfully giving five purified sub-fractions. Results showed that their major chemicals were similar, while molecular weights, monosaccharide compositions, surface morphology, solution properties as well as their structural features enormously varied. Methylation and 1D/2D NMR analysis indicated the presence of α-glucans, fucomannogalactans and galactoglucan in SHMP, further confirming the feasibility of this theory in isolation and purification of natural polysaccharides. Based on the results and previous reports, this work aims to introduce and generalize the “relative ordered structure” theory. Altogether, structural characterization of polysaccharides cannot simply “copy” the techniques on protein, more theories and methodology applicable to polysaccharide itself should be established.

Background: Previous studies have indicated that duck feet are a rich source of gelatin extractable from avian sources. In this study, the physicochemical and functional properties of avian gelatin extracted from duck feet (DFG) with acetic acid were compared with those of commercial bovine gelatin (BG).; Results: The yield of DFG obtained in this study was 7.01 ± 0.31%. High-performance liquid chromatography analysis indicated that the imino acid content was slightly lower for DFG compared with BG (P < 0.05). Differences in molecular size and amino acids between DFG and BG were also observed. The isoelectric points of DFG and BG were at pH 8 and 5 respectively, and the overall protein solubility of BG was higher than that of DFG. Gels prepared from BG exhibited higher bloom strength, viscosity and clarity and were darker in colour compared with DFG gels (P < 0.05). The gelling and melting points of BG were 21.8 and 29.47 °C respectively, while those of DFG were 20.5 and 27.8 °C respectively. BG exhibited slightly better emulsifying and foaming properties compared with DFG.; Conclusion: Although some differences between DFG and BG were observed, the disparities were small, which indicates that DFG could be exploited commercially as an alternative source of gelatin. © 2016 Society of Chemical Industry.; © 2016 Society of Chemical Industry.

Few studies have been conducted to examine the spatial heterogeneity of riverine sediment organic matter (SOM) at the molecular level. The present study explored the chemical and molecular heterogeneity of alkaline-extractable SOM from riverine sediments via multiple analytical tools including molecular composition, absorption and fluorescence spectra, and molecular size distributions. The riverine SOM revealed complex and diverse characteristics, exhibiting a great number of non-redundant formulas and high spatial variations. The molecular diversity was more pronounced for the sediments affected by a higher degree of anthropogenic activities. Unlike the cases of aquatic dissolved organic matter, highly-unsaturated structures with oxygen (HUSO) of SOM were more associated with the spectral and size features of humic-like (or terrestrial) substances than aromatic molecules were, cautioning the interpretation of the SOM molecules responsible for apparent indicators. Noting that a higher detection rate (DR) produces fewer common molecules, the common molecules of 23 different SOMs were determined at a reasonable DR value of 0.35, which accounted for a small portion (5.8%) of all detected molecules. They were mainly CHO compounds (>98%), which positively correlated with spectral indicators of biological production. Despite the low abundance, however, the ratios of aromatic to aliphatic substances could be indexed to classify the common molecules into several geochemical molecular groups with different degrees of the associations with the apparent spectral and size indicators.

In the 1940s, research by Baker established fundamental aspects of the breadmaking process while Finney showed that differences of quality resided in the gluten proteins of flour. Different lipid components have been found to affect loaf volume and texture but variation in lipid composition of current wheat varieties does not account for significant quality differences. Fundamental studies by Tipples and Kilborn showed that optimum dough development had two requirements – a critical mixing intensity and a critical amount of imparted energy. Expansion of a fermenting dough depends on two stabilizing mechanisms resulting from the gluten/starch matrix and the liquid lamellae surrounding the gas bubbles. In the 1970s, wheat cultivars were developed with poor baking properties, related to a dearth of insoluble protein, shown to comprise glutenins of large molecular size. Research by Payne and co-workers revealed that dough strength could be related to glutenin subunits and the genes controlling their synthesis. This has opened up new directions for determining composition-quality relationships and, in turn, has enabled strategies to be devised for improving quality based on wheat genetic composition.

The adsorption of a series of small alkanes was studied experimentally on H-ZSM-5 zeolites using calorimetric measurements in order to determine their interactions with the Bronsted sites. Differential heats measured on four ZSM-5 samples with different Si/Al2 ratio and with different defect concentrations were found to depend strongly on the Bronsted-site density but not on the presence of defects. The interactions for CH4 with the Bronsted sites were minimal but the effect was significant (up to 11 ± 2 kJ/mol extra heats) for larger alkanes, such as n-C6H14. The affinity of the alkanes with the Bronsted sites increased with the gas-phase proton affinity of the alkanes and the calculated affinity of the alkanes for the strong acid, fluorosulfonic acid. The extra heats of adsorption in H-ZSM-5 over its siliceous counterparts can therefore be associated with the strength of hydrogen bonding between the adsorbed alkane and the Bronsted sites, which in turn increases with molecular size. Specifically, extra ...

Aqueous solubility is a fundamental physical-chemical substance property that strongly influences the distribution, fate and effects of chemicals upon release into the environment. Experimental water solubility was determined for 18 selected C9-C18 normal, branched and cyclic alkanes. A slow-stir technique was applied to obviate emulsion formation, which historically has resulted in significant overestimation of the aqueous solubility of such hydrophobic liquid compounds. Sensitive GC-MS based methods coupled with contemporary sample extraction techniques were employed to enable reproducible analysis of low parts-per billion aqueous concentrations. Water solubility measurements for most of the compounds investigated, are reported for the first time expanding available data for branched and cyclic alkanes. Measured water solubilities spanned four orders of magnitude ranging from 0.3 μg/L to 250 μg/L. Good agreement was observed for selected alkanes tested in this work and reported in earlier literature demonstrating the robustness of the slow-stir water solubility technique. Comparisons of measured alkane water solubilities were also made with those predicted by commonly used quantitative structure-property relationship models (e.g. SPARC, EPIWIN, ACD/Labs). Correlations are also presented between alkane measured water solubilities and molecular size parameters (e.g. molar volume, solvent accessible molar volume) affirming a mechanistic description of empirical aqueous solubility results and prediction previously reported for a more limited set of alkanes.

The effects of the concentration of sodium chloride in an aqueous solution(cNaCl) and the temperature on the molecular size of poly(sulfobetaine methacrylate)(PSBMA) were studied via viscometry and dynamic light scattering( DLS). The morphology of single-chain PSBMA was determined by atomic force microscopy(AFM). The results demonstrate that the hydrodynamic diameter of PSBMA can be expressed as a continuous function of cNaCl, with the molecular size of PSBMA increasing and eventually approaching an asymptotic value with increasing cNaCl. The molecular size of PSBMA at a lower cNaCl(0.04 mol/L) increases with increasing temperature, which is the opposite of the temperature effect at a higher cNaCl(2.0 mol/L). Therefore, the internal structure of PSBMA chains in solutions with a low salt concentration differs from that in solutions with a high salt concentration. In addition, the morphology of single chains of PSBMA appears to be spherical, containing 89% void space, and the apparent size of the dried chains is almost identical to that in solution.

Protein-protein interactions (PPIs) are key elements of several important biological processes and have emerged as valuable targets in medicinal chemistry. Importantly, numerous specific protein-protein interactions (e.g., p53-HDM2 and Bcl-2-BH3 domains) were found to be involved in the development of several diseases, including various types of cancer. In general, the discovery of new synthetic PPI inhibitors is a challenging task because protein surfaces have not evolved in a manner that allows for specific binding of low molecular weight compounds. Here, we review the discovery strategies for peptide-based PPI inhibitors. Although peptide-based drug candidates exhibit significant drawbacks (in particular, low proteolytic stability), modifications of either the side chains or backbone could provide molecules of interest. Moreover, due to the large molecular size of peptide-based compounds, the discovery of molecules that specifically interact with extended protein surfaces is possible. Two major strategies for constructing peptide-based PPI inhibitors are as follows: (a) cyclization (e.g., stapled peptides) and (b) modification of the backbone structure (e.g., β-peptides and peptoids). These approaches for constructing PPI inhibitors enhance both the inhibitory activity and pharmacokinetic properties compared with non-modified α-peptides.

This study investigated the physicochemical and functional characteristics of citric acid (CA)-treated whey protein isolate (WPI) by dynamic high-pressure homogenization (DHPH) at different pressure levels (0, 25, 50, 75, and 100 MPa, 3 cycles). The number of macromolecular polymers increased in CA-treated WPI with DHPH at 0–100 MPa by the analysis of molecular size distributions. DHPH can reduce the particle size of WPI and CA-treated WPI. Additionally, the content of free sulfhydryl groups and surface hydrophobicity of WPI and CA-treated WPI increased after DHPH treatment (p

Previous studies have suggested that water-soluble polysaccharides from fermented carrot pulp (WSP-p) have stronger anti-diabetic effects than those from un-fermented carrot pulp (WSP-n). This study aimed to improve understanding of these functional differences by comparing their molecular structures. Weight-average molecular weights of WSP-p fractions were lower than those of the corresponding WSP-n fractions. While both WSPs had similar functional groups, more fragmented particles were observed on the surface of large particles of WSP-n than WSP-p. Monosaccharide composition and methylation analysis confirmed that both WSP-p and WSP-n were pectic polysaccharides, containing rhamnogalacturonan-I-type polysaccharides with 1,4-linked α-d-galacturonic acid residues and homogalacturonan regions with 1,4-GalpA linkages. 1H and 13C NMR showed that they had similar linkage patterns. These findings suggested that probiotic fermentation of WSP mainly cleaved the linkages between repeating units, and resulted in less polydisperse molecular size distributions.

While chemically and thermally modified citrus pectin (MCP) has already been studied for health benefits, it is unknown how size-fractionated oligo- and polysaccharides differentially affect cancer cell behavior. We produced thermally MCP and fractionated it by molecular size to evaluate the effect these polymers have on cancer cells. MCP30/10 (between 30 and 10 kDa) had more esterified homogalacturonans (HG) and fewer rhamnogalacturonans (RG-I) than MCP and MCP30 (higher than 30 kDa), while MCP10/3 (between 10 and 3 kDa) showed higher amounts of type I arabinogalactans (AGI) and lower amounts of RG-I. MCP3 (smaller than 3 kDa) presented less esterified HG and the lowest amount of AGI and RG-I. Our data indicate that the enrichment of de-esterified HG oligomers and the AGI and RG-I depletions in MCP3, or the increase of AGI and loss of RGI in MCP30/10, enhance the anticancer behaviors by inhibiting migration, aggregation, and proliferation of cancer cells.

Cassava starch has a remarkable importance in the food industry and it can be used either as ingredient or additive. The sour cassava starch is a product with a good oven-expansion capacity and several applications, being especially important as an alternative for gluten-based products. However, it is obtained through natural fermentation followed by solar drying, which hinders its production and application. In this context, this work proposed the ozone processing as an alternative to obtain cassava starch with good oven-expansion property. The effect of ozonation on starch granular and molecular structure was evaluated, as well as on the main starch properties. The ozone processing reduced the starch molecular size, also forming carbonyl and carboxyl groups. The structural changes led to pastes with higher clarity, better oven expansion and softer texture. The improvement in starch properties and technological aspects were related with the molecular changes. In conclusion, ozone oxidation was proved to be a viable and easier alternative for the conventional process.

Prebiotic oligosaccharides are short-chain carbohydrates that are not degraded by the enzymes of the human digestive tract. These molecules arrive intact to the lower gut to be selectively fermented by the probiotic bacteria, promoting several healthy effects to those who consume them. Prebiotic oligosaccharides are compounds of different nature: they can be extracted from plant tissues, principally by enzymatic hydrolysis of lignocelullosic material, or by using transglycosilation reactions mediated by carbohydrases. Regardless of their manufacturing strategy, the resulting solution is a mixture of oligosaccharides with different degree of polymerization as well as other not-desired contaminants of different molecular size that must be removed for improving the product purity. Therefore, membrane technology may offer interesting alternatives for such purpose. This chapter reports the main technological challenges, mechanisms, and advances, as well as trends and perspectives regarding the use of membrane technology as a strategy for manufacturing and purifying enzymatically produced oligosaccharides.

In this work, we briefly review a recently developed model to study the diffusion and rheology of associating polymers. The model describes successfully the experimental data, including an unexpected phenomenological superdiffusive scaling at distances which are larger than the molecular size. The understanding of the dynamics of associating polymers can have a big impact in applications such as biocompatible gels or self-healing materials.

Peptides are important compounds used in the development of functional biomaterials, functional foods and nutraceuticals. The functional and bioactive properties of peptides are directly linked to their structural features, including molecular size, presence or absence of charges, amino acid sequence, hydrophobicity, and hydrophilicity. The role of peptide structures in their bioactivities and functionalities is still emerging. Some bioactive peptides have undesirable taste, which can influence consumer interests in novel peptide-based food applications. In this review, we discussed the role of peptide hydrophobicity in their bioavailability, bioactivity, bitterness property, emulsion stability, aggregation and self-assembly for application in novel food formulations and nutraceutical/ drug delivery.

Amylose content as the key indicator in determining the viscoelasticity of starch gels has been widely accepted. In this study, 7 rice varieties are deliberately selected to investigate the structural basis of gel viscoelasticity of starches with similar amylose content. By quantifying starch molecular structure and rheological properties of starch gels, we find (i) starch with similar amylose content forms significantly different gel networks in terms of K*, n* and tan δ; (ii) molecular sizes of rice starches are significantly different between samples; (iii) the chain-length distributions (CLDs) of both amylopectin and amylose are parameterized by mathematic model fitting, and no large variations of these fitted parameters between samples are observed; (iv) amylopectin size are negatively correlated with K* (p 0.01) while positively correlated with tan δ (p 0.05). Molecular mechanisms are put forward to explain the role of amylopectin size in contributing to the strength of gel network.

Four varieties of barley starches, W.B. Merlin, glacier, high amylose glacier, and high amylose hull-less glacier, were isolated from barley seeds. Apparent and absolute amylose contents, molecular size distributions of amylose and amylopectin, amylopectin branch-chainlength distributions, and Naegeli dextrin structures of the starches were analyzed. W.B. Merlin amylopectin had the longest detectable chain length of DP 67, whereas glacier, high amylose glacier and high amylose hull-less glacier amylopectins had the longest detectable chain length of DP 82, 79, and 78, respectively. All the four starches displayed substantially reduced proportions of chains at DP 18-21. Amylopectins of high amylose varieties did not ' Journal Paper No. J-18096 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project No. 3258. ^ Graduate student and Professor, respectively. Department of Food Science and Human Nutrition and Center for Crops Utilization Research, Iowa State University. ^ Corresponding author