Preparation and identification of a novel peptide with high antioxidant activity from corn gluten meal.

The antioxidant activity of corn peptides is related to their molecular weight and structure. Corn gluten meal (CGM) was hydrolyzed using a combination of Alcalase, Flavorzyme and Protamex, and the hydrolysates were subjected to antioxidant activity analysis after further fractionation. Corn peptides with molecular weights less than 1 kDa (CPP1) exhibited excellent antioxidant activity. A novel peptide, Arg-Tyr-Leu-Leu (RYLL), was identified from CPP1. RYLL displayed preferable scavenging capacities for ABTS radicals and DPPH radicals, with IC50 values of 0.122 mg/ml and 0.180 mg/ml, respectively. Based on quantum calculations, RYLL had multiple antioxidant active sites, and tyrosine was the main active site due to the highest energy of the highest occupied molecular orbit (HOMO). Moreover, the simple peptide structure and hydrogen bond network of RYLL contributed to the exposure of the active site. This study elucidated the antioxidant mechanism of corn peptides, which could provide an understanding for CGM hydrolysates as natural antioxidants.

Study on Self-Assembled Morphology and Structure Regulation of α-Zein in Ethanol-Water Mixtures.

α-Zein has received widespread attention owing to its unique solubility, amphipathic, and self-assembly properties, which is because of its high proportion of nonpolar amino acids and unique amino acid sequence. The protein self-assembly is a significant and widely observed phenomenon in many scientific areas such as food and biomedicine, among many industries. In this study, we investigated the self-assembly behavior of α-zein and regulated the morphology and structure of the self-assembled α-zein by varying the experimental parameters like pH, ethanol content, induction time, and α-zein concentration during the self-assembly process in ethanol-water mixtures. The nanospheres and nanofibers were observed under different conditions [nanospheres observed under acidic and strongly alkaline (pH > 10.5) conditions or for ethanol content lower than 65% and higher than 75%; nanofibers observed under weakly alkaline (pH 9.5-10.5) conditions or for 65-75% ethanol concentration for induction duration longer than 24 h]. The morphological and structural analyses of the self-assembled α-zein showed that the self-assembly process was accompanied by the transformation of the morphology and conformation of α-zein. The studies on the self-assembly process and mechanism revealed that α-zein first self-assembled into nanospheres, followed by the nanospheres adhering to shape-beaded fibers and finally fibers, accompanied by a structural transformation from the disordered into ordered state. The nanosphere formation is noted to follow the nucleation-based polymerization, and the nanosphere-mediated mechanisms lead to the formation of nanofibers. Moreover, the hydrophobic interactions, hydrogen bonds, and electrostatic interactions are concluded to drive the α-zein self-assembly. The findings from this study are expected to provide a theoretical basis for expanding the commercial applications of α-zein.

Modified melamine-formaldehyde resins improve tensile strength along with antifouling and flame retardancy in impregnation of cellulose paper.

In this study, polyvinyl alcohol (PVA) and benzoguanamine (BG) modified melamine-formaldehyde (MF) resins were used to prepare two high-pressure laminates (HPLs) as well as a pure cellulose paper laminate and core sandwich laminates with the core material of aramid paper (AP) or polypropylene non-woven fabric (PPNF). The tensile strength, flame retardancy and antifouling properties of the modified MF resin laminates were studied and compared with the MF resin laminate. The tensile test results showed that the MF resins modified with BG and PVA improved the tensile strength of the impregnated paper. In comparison with pure kraft cellulose paper laminates, the aramid paper core laminates displayed comparatively higher tensile strength. Antifouling test results indicated that modified MF resin laminates had no obvious change while the MF resin laminate was stained. Thermal stability of the modified resins was investigated by thermogravimetric (TG) analysis and the results showed that the char yield of modified MF resin was higher than that of the unmodified MF resin due to the addition of BG. The modified MF resin laminates exhibited better flame retardancy properties through the analysis of limiting oxygen index (LOI), vertical burning and cone calorimetry (CONE) compared to the MF resin laminate. In addition, the flame retardancy of laminates was further enhanced when prepared with core materials of aramid paper. Scanning electron microscopy analysis of residue char after CONE tests showed that the AP-core laminate formed a dense and stable char layer compared with the loose char layer of the PPNF-core laminate. This study shows a new direction to develop sustainable high-performance flame retardant laminates for commercial decoration application.

Bioinspired catecholic activation of marine chitin for immobilization of Ag nanoparticles as recyclable pollutant nanocatalysts.

Being one type of the most abundant marine polysaccharides in nature, chitin has inert chemical properties and thus prolonged been hindered for high-value utilization. A mussel-inspired catecholic chemistry was found to be able to confer nature-derived mesoporous chitin aerogels with high and tunable surface activities. When further combining with their high porosity, high specific surface area, mechanical toughness and unique nanofibrous architecture, these catechol-activated chitin aerogels could be used as a unique supporting matrix to immobilize Ag nanoparticles. Besides the mild synthesis conditions and the merits inherited from pristine chitin, the resultant chitin-Ag hybrid aerogels further exhibited high catalytic activity, excellent recyclability, super solvent endurance and fast regeneration ability. Their high mechanic properties and porous structures also enabled a convenient membrane process to remove organic dyes from water.

Enhancing reducing ability of α-zein by fibrillation for synthesis of Au nanocrystals with continuous flow catalysis.

Green low-cost synthesis and efficient recyclability are two major hindrances for Au nanocrystals as catalysts applying in diverse industrial reaction processes. By the use of low-cost α-zein (i.e. a major storage protein of corn) as the reductant, capping agent and stabilizer, Au nanocrystals with tunable catalytic activity were synthesized in a wet-chemical approach. Fibrillation of α-zein further enhanced its reducing ability due to larger specific surface area and more hydrophilic groups exposed on the surfaces. The obtained Au nanocrystals had biocompatibility, high stability in various solvents, unique solubility in aqueous alcohol and high catalytic ability, being able to detect ethanol composition in aqueous ethanol as well as H2O2 for diagnosis of diabetes mellitus. These advantages also enable efficient recyclability of Au nanocrystals with continuous flow catalysis in different solvents and environments. Thus, the use of α-zein offered Au nanocrystals not only with green low-cost synthesis, but also with tunable catalytic activities, ethanol-responsiveness and efficient recyclability, which may be applicable in diverse fields.

Single-crystal Au microflakes modulated by amino acids and their sensing and catalytic properties.

Single-crystal Au microflakes with the planar area over 10(3)µm(2) (i.e. being accessible to the human eye resolution) were synthesized in an environment-friendly route by directing two-dimensional growth of Au nanocrystals into macroscopic scales with amino acids as both reducing agents and capping agents. Side groups of amino acids were found to be a determinant parameter to tune the dimension and size of Au single crystals. The successful synthesis of Au microflakes provides an unprecedented opportunity to bridge nanotechnology and macroscopic devices, and hereby to start a new scenario of exploring their unique properties and applications in optoelectronic devices and bio-sensing fields across multiple length scales. For example, Au microflakes respond to air humidity upon depositing on films of chitin nanofibrils, and sense various physiological molecules as electrode materials of biosensors.

Analysis of backscattering characteristics of objects for remote laser voice acquisition.

This study is focused on numerical simulation analysis and experimental study regarding the influence of backscattering characteristics of objects for long-range laser voice acquisition. Based on theoretical analysis, three parameters, including surface roughness of an object, incident angle, and refractive index, which will influence the performance of remote scattered reflection laser interference voice acquisition, are investigated and analyzed. After analysis and simulation, an experimental system is set up to demonstrate the influence of backscattering characteristics of an object. The results show that the restored amplitude of a voice signal decreases gradually, corresponding to an increase of surface roughness from 0.4 to 12.5 µm; the incident angle of the measured laser shall reside between 57.32 deg (1 rad) and -57.32 deg (-1 rad); the optimal incident angle is 0 deg for all kinds of objects; and the metal object is a better choice of material selection. In addition, the restored amplitude of a voice signal rises with the attenuation coefficient of metal increasing. It also increases with the refractive index for a nonmetallic object. Comparing a metal to a nonmetallic object, the amplitude of voice signal varies significantly.

Sustainable, heat-resistant and flame-retardant cellulose-based composite separator for high-performance lithium ion battery.

A sustainable, heat-resistant and flame-retardant cellulose-based composite nonwoven has been successfully fabricated and explored its potential application for promising separator of high-performance lithium ion battery. It was demonstrated that this flame-retardant cellulose-based composite separator possessed good flame retardancy, superior heat tolerance and proper mechanical strength. As compared to the commercialized polypropylene (PP) separator, such composite separator presented improved electrolyte uptake, better interface stability and enhanced ionic conductivity. In addition, the lithium cobalt oxide (LiCoO2)/graphite cell using this composite separator exhibited better rate capability and cycling retention than that for PP separator owing to its facile ion transport and excellent interfacial compatibility. Furthermore, the lithium iron phosphate (LiFePO4)/lithium cell with such composite separator delivered stable cycling performance and thermal dimensional stability even at an elevated temperature of 120°C. All these fascinating characteristics would boost the application of this composite separator for high-performance lithium ion battery.

Renewable and superior thermal-resistant cellulose-based composite nonwoven as lithium-ion battery separator.

A renewable and superior thermal-resistant cellulose-based composite nonwoven was explored as lithium-ion battery separator via an electrospinning technique followed by a dip-coating process. It was demonstrated that such nanofibrous composite nonwoven possessed good electrolyte wettability, excellent heat tolerance, and high ionic conductivity. The cells using the composite separator displayed better rate capability and enhanced capacity retention, when compared to those of commercialized polypropylene separator under the same conditions. These fascinating characteristics would endow this renewable composite nonwoven a promising separator for high-power lithium-ion battery.

Synthesis of nitrogen-doped MnO/graphene nanosheets hybrid material for lithium ion batteries.

Nitrogen-doped MnO/graphene nanosheets (N-MnO/GNS) hybrid material was synthesized by a simple hydrothermal method followed by ammonia annealing. The samples were systematically investigated by X-ray diffraction analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy. N-doped MnO (N-MnO) nanoparticles were homogenously anchored on the thin layers of N-doped GNS (N-GNS) to form an efficient electronic/ionic mixed conducting network. This nanostructured hybrid exhibited a reversible electrochemical lithium storage capacity as high as 772 mAh g(-1) at 100 mA g(-1) after 90 cycles, and an excellent rate capability of 202 mA h g(-1) at a high current density of 5 A g(-1). It is expected that N-MnO/GNS hybrid could be a promising candidate material as a high capacity anode for lithium ion batteries.

Synthesis of nanostructured fibers consisting of carbon coated Mn3O4 nanoparticles and their application in electrochemical capacitors.

Nanostructured composite fibers consisting of carbon coated Mn3O4 nanoparticles (Mn3O4@C) were prepared from thermal decomposition of manganese alginate fibers produced by wet-spinning technique, and investigated with SEM, TEM, XRD, nitrogen adsorption-desorption isotherms, and electrochemical tests toward energy storage. It is found that the as-obtained Mn304@C fibers consist of plenty of nano-sized Mn3O4 crystals with even diameter of 10-15 nm and carbon coating layer with a thickness of 1-2 nm. The composite fibers exhibit also a porous structure consisting of both micropores and mesopores. The electrochemical performances of Mn3O4@C fibers were examined by cyclic voltammetry and galvanostatic charge-discharge techniques. The results indicate that Mn3O4@C fibers possess a higher specific capacitance and superior rate capability when used as electrode materials for supercapacitor compared with commercial Mn3O@4. The improved performances of Mn3O4C fibers can be attributed to the nano-dimension of Mn3O4 particles, the thin carbon coating layer and the nanopores existing among Mn304@C nanoparticles.

Preparation and li storage properties of hierarchical porous carbon fibers derived from alginic acid.

One-dimensional (1D) hierarchical porous carbon fibers (HPCFs) have been prepared by controlled carbonization of alginic acid fibers and investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, nitrogen adsorption-desorption isotherms, and electrochemical tests toward lithium storage. The as-obtained HPCFs consist of a 3D network of nanosized carbon particles with diameters less than 10 nm and exhibit a hierarchical porous architecture composed of both micropores and mesopores. Electrochemical measurements show that HPCFs exhibit excellent rate capability and capacity retention compared with commercial graphite when employed as anode materials for lithium-ion batteries. At the discharge/charge rate of 45 C, the reversible capacity of HPCFs is still as high as 80 mA h g(-1) even after 1500 cycles, which is about five times larger than that of commercial graphite anode. The much improved electrochemical performances could be attributed to the nanosized building blocks, the hierarchical porous structure, and the 1D morphology of HPCFs.