Characterization of zein modified with a mild cross-linking agent

Zein, a predominant corn protein, is an alcohol-soluble protein extracted from corn and is an excellent film former. The characteristic brittleness of zein diminishes its usefulness as a film. It is well known that zein has a propensity for forming aggregates in solution. When zein molecules were cross-linked with 1-[3-dimethylaminopropyl]-3-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), it was found that the film-forming property was improved and the aggregation phenomenon in solution was suppressed. At the air/water interface, native zein forms brittle film with rough surface, whereas cross-linked zein forms rigid film with very smooth and even surface. Tensile strengths of the films were shown to be greatly increased by cross-linking. Objectives of this study are to determine the cross-linking mechanism of zein, the optimum reaction conditions, characteristics of the reaction product, and mechanical properties of cross-linked zein film. Through viscosity and dynamic light scattering, the cross-linking reaction was monitored. Optimum amount of EDC and NHS was determined to be 30 mg each per gram of zein. The cross-linking of zein with EDC and NHS seemed to be self-terminating because the cross-linking reaction did not proceed to precipitation.     

Synthesis of poly(hydroxamic acid) ligand from polymer grafted khaya cellulose for transition metals extraction

A cellulose-graft-poly(methyl acrylate) was synthesized by free radical initiating process and the ester functional groups were converted into the hydroxamic acid ligand. The intermediate and final products are characterized by FT-IR, FE-SEM, HR-TEM and XPS technique. The pH of the solution acts as a key factor in achieving optical color signals of metalcomplexation. The reflectance spectra of the [Cu-ligand]n+ complex was found to be a highest absorbance at 99.8 % at pH 6 and it was increased upon increasing of Cu²⁺ ion concentrations and a broad peak at 700 nm was observed which indicated the charge transfer (π-π transition) metals-Cu complex. The adsorption capacity of copper was found to be superior (336 mg g^?1) rather than other transition metals such as Fe³⁺, Co³⁺, Cr³⁺, Ni²⁺, Mn²⁺ and Zn²⁺ were 310, 295, 288, 250, 248 and 225 mg g^-1, respectively at pH 6. The experimental data of all metal ions fitted significantly with the pseudo-second-order rate equation. The transition metal ions sorption onto ligand were well fitted with the Langmuir isotherm model (R²>0.99), which suggested that the cellulose-based adsorbent known as poly(hydroxamic acid) ligand surface is homogenous and monolayer. The reusability of the poly(hydroxamic acid) ligand was checked by the sorption/desorption process up to ten cycles without any significant loss in its original sensing and removal performances.     

Evaluating the oil content of cellulose acetate fibers with the dielectric spectrum

The dielectric spectrums of the cellulose acetate fiber/air (C/A) samples and the cellulose acetate fiber/air/oil (C/A/O) samples were measured with a broad band dielectric spectrum measurement system at frequencies with a logarithmic distribution from 0.1 Hz to 20 MHz. The experimental results showed that for the C/A samples, the relative permittivity varied weakly with frequency for the C/A samples, especially in the high frequency band. Hence, the mass of the cellulose acetate fibers was estimated by the dielectric spectrums of the C/A samples at a high frequency. For the C/A/O samples, the relative permittivity increased rapidly while the frequency decreased in the low frequency band, but it had little interaction with the frequency at the high frequency band. Therefore, the oil mass was estimated by dielectric spectrums of the C/A and C/A/O samples using the low frequency band. The oil content of cellulose acetate fibers was then calculated along with the estimated oil mass and cellulose acetate fibers mass.     

Properties of flame-retardant cellulose fibers with ionic liquid

Flame-retardant cellulose fibers were prepared by dissolving cellulose in tetrabutylammonium acetate and dimethyl sulfoxide, and blending with amino silicone oil (ASO). The ASO was used as a novel fabric softener and flame retardant for cellulose fibers. Fourier-transform infrared spectroscopy showed that blending with ASO did not adversely affect the cellulose fibers. The flame retardancy of the cellulose fibers blended with ASO was determined based on the limiting oxygen index (LOI). Cellulose fibers blended with 8 wt% (add-on) ASO gave the best flame retardancy, with an LOI of 28, which was higher than that of the virgin fibers. The thermal properties of the flame-retardant cellulose fibers were investigated using differential scanning calorimetry and thermogravimetric analysis. The results showed that ASO prevented degradation of the cellulose fibers, hindered the formation of volatile species, and favored char formation. The mechanical properties of the flame-retardant cellulose fibers were better than those of virgin cellulose fibers.     

Fabrication and characterization of porous cellulose acetate films by breath figure incorporated with capric acid as form-stable phase change materials for storing/retrieving thermal energy

Porous cellulose acetate (CA) films by breath figure (BF) incorporated with capric acid as form-stable phase change materials (PCMs) were fabricated and characterized for storing and retrieving thermal energy. Effects of different solvents, CA concentration and film thickness on morphology, microstructure and thermal energy storage property of formstable PCMs were investigated by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analyzer and differential scanning calorimetry (DSC), respectively. The results indicated that the prepared CA films were porous with DMF, acetone, and dichloromethane (DCM) as the solvents, and capric acid absorption capacity was as high as 86.9, 75.0 and 82.2 % with the specific surface area of 4.8, 2.8 and 1.8 m²/g. Moreover, porous CA film with 5 % CA concentration and 0.5 mm thickness prepared by using DMF as solvent had larger specific surface area and higher thermal energy storage properties. The fabricated form-stable PCMs could well maintain their PCM characteristics and demonstrated great temperature regulation ability and had potential applications in building energy conservation.     

Thermal and structure properties of biobased cellulose nanowhiskers/poly (lactic acid) nanocomposites

Cellulose nanowhiskers were used to improve the performance of poly (lactic acid) (PLA). The nanocomposites mixed with three different molecular weight of poly (ethylene glycol) (PEG) were characterized by mechanical testing, thermal gravimetry and differential scanning calorimetry. The tensile test showed an increase in tensile strength and elongation at break with the addition of PEG to PLA/CNW nanocomposites, the thermal analysis results showed an increase of crystallization temperature (T _c) and crystallization compatibility (larger crystallization and melting areas), which indicated that the cellulose nanowhiskers (CNW) and PEG or CNW alone should not be considered as nucleating agents for the PLA matrix; The CNW was homo-dispersed which contributed to decreasing mobility of polymer chain segments. The compatibility between hydrophobic PLA matrix and the hydrophilic CNW was improved by the addition of different molecular weight polymeric-PEG. The thermo gravimetric analysis indicated that the thermal stability of the different composites were reflected well in the region between 25 °C and 245 oC. The structure of the PLA/CNW/PEG composites was characterized by AFM, which showed that the CNW dispersed in the PLA matrix evenly.     

蔗糖脂肪酸三酯在菜籽油脱磷工艺中的应用及蔗糖酯磷脂复合物的制备

本文以蔗糖脂肪酸三酯（sucrose fatty acid triester,STE）和磷脂酰胆碱（phosphatidylcholine,PC）为原料制备蔗糖酯磷脂复合物,并通过傅里叶红外光谱分析（Fourier infrared spectrum,FT-IR）、热重分析（thermogravimetric analysis,TGA）和差示扫描量热分析（differential scanning calorimetry,DSC）对制备的蔗糖酯磷脂复合物进行表征分析;以STE为吸附脱磷剂,考察STE在菜籽油脱磷工艺中的应用。研究结果表明,STE与PC在无水乙醇体系中形成了新型的STE-PC复合物,与STE和PC相比,STE-PC复合物具有更低的相变熔融温度;另外,STE对菜籽油中的磷脂有一定的吸附脱除作用,在脱磷温度为55oC、STE添加量为3.5%、脱磷时间为30min条件下,脱磷率可达37.2%。     

Improving the barrier and mechanical properties of corn starch-based edible films: Effect of citric acid and carboxymethyl cellulose

The films produced from pure starch are brittle and difficult to handle. Chemical modifications (e.g. cross-linking) and using a second biopolymer in the starch based composite have been studied as strategies to produce low water sensitive and relatively high strength starch based materials. A series of corn starch films with varying concentrations (0-20%, W/W) of citric acid (CA) and carboxymethyl cellulose (CMC) were produced by casting method. The effects of CA and CMC on the water vapor permeability (WVP), moisture absorption, solubility and tensile properties were investigated. The water vapor barrier property and the ultimate tensile strength (UTS) were improved significantly (p < 0.05) as the CA percentage increased from 0 to 10% (W/W). At the level of 15% (W/W) CMC, the starch films showed the lowest WVP values (2.34 × 10⁻⁷ g Pa⁻¹ h⁻¹ m⁻¹) and UTS increased from 6.57 MPa for the film without CMC to 16.11 MPa for that containing 20% CMC.     

人参皂苷代谢产物M1及其脂肪酸酯EMl抗肿瘤活性研究进展

目的:介绍人参皂苷代谢产物20—O—β—D—吡喃葡萄糖—20(S)—原人参二醇皂苷(M1)及其脂肪酸酯(EM1)抗肿瘤活性和EMl合成的研究进展,为其深入研究提供参考。方法:对近年来有代表性的文献进行分析、归纳。结果:人参皂苷代谢产物及其脂肪酸酯有抗肿瘤活性。结论:EM1抑制肿瘤作用比M1强,EM1可能是人参皂苷在体内的真正的活性形式。EM1的药代动力学和生理学需进一步深入研究。     

Evaluation of thermomechanical pretreatment for enzymatic hydrolysis of pure microcrystalline cellulose and cellulose from Brewers’ spent grain

Microcrystalline cellulose (Avicel PH102) and Brewers’ spent grain (BSG) were subjected to Détente Instantanée Contrôlée (DIC) thermomechanical pre-treatment before exposure to cellulases (Celluclast 1.5 L). In a first part, we showed that the addition of β-glucosidase (Novozym-188) increased the hydrolysis yield of Avicel. A maximal theoretical yield (100%), was obtained for 5 and 10 g/L of Avicel using a mixture of Celluclast 1.5 L/Novozym-188. After DIC pre-treatments, the initial rate and final yield of hydrolysis decreased in comparison with those from untreated microcrystalline cellulose. This phenomenon may be due to the modification of the crystallinity of pure cellulose and the formation of inhibitors during the pre-treatment. In a second part, BSG was thermomechanically pre-treated and hydrolyzed. The results showed that the hydrolysis yield of BSG treated at pressure levels between 2 and 7 bar during 15 min was strongly improved compared to hydrolysis yield of untreated BSG. The optimized hydrolysis process, under intensive DIC conditions, achieved a glucose yield corresponding to 100% of the theoretical cellulose value. The morphology of BSG samples was studied with Scanning Electronic Microscopy (SEM) and highlighted that the structure of pre-treated BSG showed an important disruption compared to the rigid structure of untreated BSG.     

Functionalizing cellulose scaffold prepared by ionic liquid with bovine serum albumin for biomedical application

The present study reports the preparation of a cellulose scaffold for tissue engineering directly from cellulose fiber using ionic liquid (IL) by the NaCl leaching method with bovine serum albumin (BSA), which is well known protein utilized for biomedical applications like degradation of polymer, cell attachment and proliferation on scaffold. The 1-n-allyl-3-methylimidazolium chloride (AmimCl) IL was used as a solvent for cellulose. The morphology of the scaffold was studied by scanning electron microscopy (SEM) and the images showed that the pore sizes of the scaffolds were about 200 µm. In addition, the water uptake (WU) and degree of degradation of the cellulose scaffold were measured. Meanwhile, the biocompatibility and bioactivity of the scaffold were determined via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenytetrazolium bromide (MTT) assay and the Live/Dead viability test. The various results demonstrated the ability of the Mesenchymal stem cells (MSC) to attach to the surface of the scaffolds amplified as percentage of BSA increased in cellulose scaffold.     

Optimization of acid cellulose enzyme concentration to reduce pilling of bamboo fabric: An objective assessment approach

Enzymes are being extensively used in industry as they are environmentally friendly. They show a variety of advantages over chemicals, like their specificity, high efficiency and eco-friendliness. Nowadays different kinds of cellulase enzyme mixtures are commercially formulated for the finishing of cellulosic fabrics. This study investigated the effect of acid cellulase treatment on bamboo knitted-fabric to reduce pill. It has been observed that specific range of concentration only can effectively reduce pills with substantial weight loss. The common process and method followed by a textile chemist to optimize or standardize the concentration of enzyme treatment to reduce pill is still cumbersome and doubtful. A quicker and objective method is proposed to optimize the concentration of enzyme. The effectiveness is evaluated using standard Martindale tester and the weight loss of the fabric.     

Oxidation of regenerated cellulose with nitrogen dioxide/carbon tetrachloride

This paper explores the influence of oxidation time on selective oxidation of regenerated cellulose with NO₂/CCl₄ as oxidation system. FTIR and other testing methods are used to characterize the structure of oxidized regenerated cellulose (ORC), showing that the regenerated cellulose is oxidized at C6 by the NO₂/CCl₄ system with extremely high selectivity. With the extension of oxidation duration, the carboxyl content in ORC increases gradually from 12.11 to 21.29 % while the degree of polymerization (DP) decreases from 92.86 to 53.40 and the strength of monofilament decreases gradually. In case of the reaction duration of 24 h, the performance of oxidation product can satisfy the requirement of absorbing hemostatic materials, i.e., with good hemostatic performance, while it is also provided with excellent antibacterial activity, which the reduction in colony forming units (CFU) is more than 99.9 %.     

Electrospinning of cellulose nanofibers mat for laminated epoxy composite production

In this study, a new approach consisting of chemical treatment steps followed by electrospinning process was applied to produce cellulose nanofibers from wheat straws. Wheat straws were initially pretreated by NaOH solution to open the complex structure of raw materials and remove non-cellulosic materials. Then, acid and alkali hydrolysis was separately performed to eliminate hemicellulose and soluble lignin. Also, bleaching processes were implemented to remove the insoluble lignin. Cellulose nanofibers were produced by electrospinning of various concentrations of cellulose in different solvents including sodium hydroxide/urea/thiourea, pure trifluoroacetic acid (TFA), and TFA/methylene chloride. Images obtained by Scanning Electron Microscope (SEM) showed long and uniform nanofibers produced from electrospinning of cellulose/TFA/methylene chloride solution. An epoxy based laminated composite was prepared by a lamina of cellulose microfiber and electrospun nanofiber mat using hand lay-up composite manufacturing method. The fracture surface of the epoxy nanocomposite was analyzed by SEM images. In addition, the mechanical properties of laminated epoxy composites were compared with pure epoxy by conducting tensile and impact tests. Tensile test results showed that the ultimate tensile strength, elongation, and modulus of laminated epoxy nanocomposites were significantly increased. Moreover, it was found that by adding a nanofiber lamina in the epoxy composite, the impact resistance was significantly improved as a result of crack growth prevention.     

Isolation of cellulose with ionic liquid from steam exploded rice straw

Isolation of cellulose from straw is a bottleneck for exploiting such biomass resources. In recent years, considerable concerns have arisen over new efficient and environmentally friendly way for this purpose. A novel method for cellulose isolation has been proposed by dissolving steam exploded rice straw in 1-allyl-3-methylimidazolium chloride ionic liquid (IL), following regeneration of crude cellulose by diluting the cellulose-ionic liquid solution adequately after separation of insoluble residues. The crude cellulose was then bleached by 2% hydrogen peroxide aqueous solution with low-flux ozone blowing into. No acid-insoluble lignin and only 0.85% hemicelluloses were detected in the bleached cellulose. The isolated cellulose was analyzed by SEM, FT-IR, ¹³C CP/MAS solid state NMR, XRD spectroscopes, and the results indicated that high quality cellulose preparation could be isolated in this manner from rice straw.     

Evaluation of the dyeability of the new eco-friendly regenerated cellulose

Three commercial dyes-direct, reactive, and vat dye-were applied to the new regenerated cellulose fiber which was prepared from cellulose acetate fiber through the hydrolysis of acetyl groups with an environmentally friendly manufacturing process. The effect of salt, alkali, liquor ratio, temperature, and leveling agent on the dyeing behavior and fastness were evaluated and compared with regular viscose rayon. From the results, we found that new regenerated cellulose fiber exhibited better dyeability and fastness than regular viscose rayon.     

Phytate negatively influences wheat dough and bread characteristics by interfering with cross-linking of glutenin molecules

The influence of added phytate on dough properties and bread baking quality was studied to determine the role of phytate in the impaired functional properties of whole grain wheat flour for baking bread. Phytate addition to refined flour at a 1% level substantially increased mixograph mixing time, generally increased mixograph water absorption, and reduced the SDS-unextractable protein content of dough before and after fermentation as well as the loaf volume of bread. The added phytate also shifted unextractable glutenins toward a lower molecular weight form and increased the iron-chelating activity of dough. It appears that phytate negatively affects gluten development and loaf volume by chelating iron and/or binding glutenins, and consequently interfering with the oxidative cross-linking of glutenin molecules during dough mixing. Phytate could be at least partially responsible for the weak gluten network and decreased loaf volume of whole wheat flour bread as compared to refined flour bread.     

粗纤维、透光率、pH值与乌龙茶品质关系初探

成品乌龙荣中的色、香、昧、形等品质因素的形成,是通过选择最佳嫩度的鲜叶,结合它的特殊制造工艺来实现的。鲜叶是茶叶品质的基础,做青时要求老微度适当,偏激或过于租者,咸菜品质都不好。人们通常是依靠感官审评来鉴定茶叶品质,本文拟通过测定菜叶粗纤维含量、茶汤的酸碱度及造光率,探讨它们与茶叶品质的关系。这对于开展菜叶的理化分析,减少人为审评误差且有现实意义。1材料与方法（1）主要测试仪器PHS－2型欧度计测定茶场的PH值;721型分光光度计（波长440微毫米）测定茶汤的透光率;用恒温干燥箱及分析天平测定茶叶粗纤维含量…     

Effect of glycols and catalysts on cotton fabrics treated with glyoxal

The optimum conditions for durable press treatment of cotton fabrics using glyoxal as a nonformaldehyde crosslinking agent were investigated. Crosslinking reaction was conducted in the presence of different catalysts such as aluminum sulfate, magnesium chloride, or magnesium chloride-citric acid mixture at various mole ratios of catalyst to glyoxal. Aluminum sulfate was proven the most effective one among those used. Glycol addition into a glyoxal padding bath increased the wrinkle recovery angle(WRA) and whiteness of treated fabrics. The optimum mole ratio of glycol to glyoxal was 1:1. Diethylene glycol addition produced better overall performance to the glyoxal-crosslinked fabric compared to ethylene glycol addition.