球状壳聚糖树脂对茶多酚的吸附热力学和动力学研究

采用反相悬浮交联法制备了球状壳聚糖树脂(RCM),通过静态吸附实验,研究了RCM对茶多酚的吸附热力学和动力学特性。结果表明:吸附等温线符合Laugmiur等温曲线,且平衡常数Kb随着温度升高而升高。吸附是非自发的、吸热的、熵增加的过程。吸附过程符合二级动力学吸附模型,吸附过程主要受粒子内扩散模型控制。     

澳洲坚果壳吸附3种阳离子染料的研究

以坚果壳为原料, 经粉碎制成不同粒径的粉末吸附剂。探究了坚果壳吸附亚甲基蓝、罗丹明B、碱性品红的性能。研究发现坚果壳吸附亚甲基蓝、罗丹明B、碱性品红最佳粒径为0.3 mm、最佳投加量分别为1.6、2.4、1.2 g,pH均为5、温度为30 ℃、震荡时间为30、60、60 min。利用准一级、准二级动力学方程模拟坚果壳吸附亚甲基蓝、罗丹明B和碱性品红的动力学过程,结果表明坚果壳吸附亚甲基蓝、罗丹明B和碱性品红的过程适合于准二级动力,学模型。文中计算了焓变（ΔH ⁰）、自由能（ΔG ⁰）、熵变（ΔS ⁰）等热力学参数,坚果壳吸附3种阳离子染料过程中ΔG ⁰均小于0,ΔS ⁰、ΔH ⁰均大于0,说明坚果壳吸附3种阳离子染料的过程是一个自发的趋于无序的吸热过程。     

棉铃壳生物炭对尼泊金乙酯吸附特性研究

为促进棉铃壳的资源化利用,以棉铃壳为材料,采用慢速热解技术于300 ℃、400 ℃、500 ℃条件下制备生物炭吸附剂（BC300、BC400、BC500）,检测其去除废水中尼泊金乙酯（Ethyl paraben,EP）的效果。吸附试验结果表明,生物炭的制备温度显著影响其对EP的吸附效果,3个温度制备的生物炭对EP的吸附能力表现为BC500＞BC400＞BC300。此外,废水中EP的初始质量浓度、吸附温度和时间等均能影响吸附效果。45 ℃下EP初始质量浓度为40 mg·L^－1时,BC500对EP去除率最高,达89.4%。生物炭对EP的吸附等温线符合Langmuir模式和Freundlich模式。研究结果探明了在3个温度下制备的棉铃壳生物炭去除废水中EP的最适条件,可为棉铃壳应用于EP等有机污染物的去除提供依据。     

Mechanical,Thermal, and Swelling Properties of Cross-linked Hydrogels Based on Oxidized Cellulose Nanowhiskers and Chitosan/poly(vinyl alcohol) Blends

Cross-linked hydrogels of chitosan/poly(vinyl alcohol) (PVA)/oxidized cellulose nanowhiskers (CNWs) were prepared by using oxidized CNWs as a cross-linker. The effects of the oxidation level of CNWs on the swelling behavior, thermal stability, viscoelastic properties and compressive strength of the hydrogels were studied. Chemical cross-links, hydrogen bonds, as well as nanofiller reinforcement between the three materials played a major role in determining the properties of the hydrogels. Swelling test results showed that the incorporation of oxidized CNWs decreased the water absorbability of the hydrogels due to the increase in cross-linking degree. Viscoelastic properties of the hydrogels with oxidized CNWs was increased by 537 % in storage modulus, from 4.65 kPa to 29.6 kPa. Compressive strength of 181.5 kPa at 50 % strain was observed from the cross-linked hydrogels, compared with 21.2 kPa of the non-cross-linked hydrogels. The thermal experiments showed that the chemical cross-linking slightly increase the resistance toward thermal degradation of the hydrogels.     

Recent Modifications of Chitosan for Adsorption Applications: A Critical and Systematic Review

Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012–2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).     

Preparation and Characterization of Microcrystalline Cellulose from Sacred Bali Bamboo as Reinforcing Filler in Seaweed-based Composite Film

Microcrystalline cellulose (MCC) isolated from cheap, fast-growing and abundant accessible Sacred Bali bamboo (Schizostachyum brachycladum) was utilized as reinforcement material in the seaweed-based composite film. Isolation of MCC was carried out by using a combination of pulping, bleaching and acid hydrolysis process. This study emphasized on the feasibility of MCC production from Sacred Bali bamboo by studying its properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The commercial-MCC (CMCC) was used as reference material. Results showed that the production yield, moisture content (MC) and fiber length of bamboo-MCC (BMCC) were 83.37±1.48 %, 4.50±0.5 %, and 0.47±0.02 mm, respectively. According to the chemical analysis by FTIR, both lignin and hemicellulose were completely removed from BMCC, and thus, improved the crystallinity (78 %) and thermal stability (≈325 °C) of BMCC. This study also revealed that MCC produced from Sacred Bali bamboo demonstrated strong mechanical reinforcement effect in the seaweed-based film. Hence, Sacred Bali bamboo-MCC could be used as reinforcement material in the polymer.     

Physicochemical and Biological Characterization of Fucoidan from Fucus vesiculosus Purified by Dye Affinity Chromatography

A comparative study concerning the physicochemical, monomeric composition and biological characters among different fucoidan fractions is presented. Common purification techniques for fucoidan usually involve many steps. During these steps, the important structural features might be affected and consequently alter its biological activities. Three purified fractions were derived from Fucus vesiculosus water extract which, afterwards, were purified by a recently-developed dye affinity chromatography protocol. This protocol is based on dye-sulfated polysaccharide interactions. The first two fractions were obtained from crude precipitated fucoidan at different pH values of the adsorption phase: pH 1 and 6. This procedure resulted in fucoidan_1 and 6 fractions. The other, third, fraction: fucoidan_M, however, was obtained from a buffered crude extract at pH 1, eliminating the ethanol precipitation step. All of the three fractions were then further evaluated. Results revealed that fucoidan_M showed the highest sulfur content (S%), 12.11%, with the lowest average molecular weight, 48 kDa. Fucose, galactose, and uronic acid/glucose dimers were detected in all fractions, although, xylose was only detected in fucoidan_1 and 6. In a concentration of 10 µg·mL⁻¹, Fucoidan_6 showed the highest heparin-like anticoagulant activity and could prolong the APTT and TT significantly to 66.03 ± 2.93 and 75.36 ± 1.37 s, respectively. In addition, fucoidan_M demonstrated the highest potency against HSV-1 with an IC₅₀ of 2.41 µg·mL⁻¹. The technique proved to be a candidate for fucoidan purifaction from its crude extract removing the precipitation step from common purification protocols and produced different fucoidan qualities resulted from the different incubation conditions with the immobilized thiazine toluidine blue O dye.     

茶叶黄酮类物质的双水相系统纯化及抗氧化研究

采用PEG/盐的双水相系统纯化茶叶黄酮,探究萃取机理及其抗氧化活性。以茶叶为原料,茶叶黄酮得率为指标;采用单因素和响应面法试验设计,研究PEG的种类和用量、盐的种类和用量、温度、pH对茶叶黄酮提取率的影响,根据Box-Behnken中心组合方法进行3因素（Na₂SO₄的质量分数、PEG600、MgCl₂添加量）3水平的试验设计,进行响应面（RSM）分析。通过分析还原力和DPPH体系,评估不同浓度黄酮的抗氧化活性,并与参照抗氧化剂BHT和Vc进行比较。结果显示最佳条件：pH为5,萃取温度30℃,5mL 15% Na₂SO₄,6g PEG600,MgCl₂的添加量为2.9%,萃取率为96.31%。本方法所形成双水相体系,操作简便,萃取率高,方法重现性好;茶叶黄酮有较强的铁还原能力和清除DPPH自由基能力,茶叶黄酮是一个潜在的天然安全的有效的抗氧化剂。     

A Review of the Chemical Extraction of Chitosan from Shrimp Wastes and Prediction of Factors Affecting Chitosan Yield by Using an Artificial Neural Network

There are two viable options to produce shrimp shells as by-product waste, either within the shrimp production phases or when the shrimp are peeled before cooking by the end user. This waste is considered a double-edged sword, as it is possible to be either a source of environmental pollution, through dumping and burning, or a promising source from which to produce chitosan as a biodegradable, biocompatible biopolymer which has a variety of agricultural, industrial, and biomedical applications. Chitosan is a deacetylated form of chitin that can be chemically recovered from shrimp shells through the three sequential stages of demineralization, deproteinization, and deacetylation. The main aim of this review paper is to summarize the recent literature on the chemical extraction of chitosan from shrimp shells and to represent the physicochemical properties of chitosan extracted from shrimp shells in different articles, such as chitosan yield, moisture content, solubility, ash content, and degree of deacetylation. Another aim is to analyze the influence of the main predictors of the chemical extraction stages (demineralization, deproteinization, and deacetylation) on the chitosan yield percentage by using a multilayer perceptron artificial neural network. This study showed that the deacetylation alkali concentration is the most crucial parameter, followed by the concentrations of acid and alkali of demineralization and deproteinization, respectively. The current review was conducted to be used in prospective studies for optimizing the chemical extraction of chitosan from shrimp wastes.     

Chitin and Chitosan: Prospective Biomedical Applications in Drug Delivery,Cancer Treatment,and Wound Healing

Chitin and its derivative chitosan are highly abundant polymers in nature, appearing in both the shells and exoskeletons of various marine and non-marine species. Since they possess favorable properties, such as biocompatibility, biodegradability, non-toxicity, and non-immunogenicity, they have gained recent attention due to their enormous potential biomedical applications. The polycationic surface of chitosan enables it to form hydrogenic and ionic bonds with drug molecules, which is one of its most useful properties. Because chitosan is biocompatible, it can therefore be used in drug delivery systems. The development of chitosan-based nanoparticles has also contributed to the significance of chitin as a drug delivery system that can deliver drugs topically. Furthermore, chitin can be used in cancer treatment as a vehicle for delivering cancer drugs to a specific site and has an antiproliferative effect by reducing the viability of cells. Finally, chitosan can be used as a wound dressing in order to promote the faster regeneration of skin epithelial cells and collagen production by fibroblasts. As discussed in this review, chitin and chitosan have diverse applications in the medical field. Recognizing the biomedical applications of these two polymers is essential for future research in tissue engineering and nanobiotechnology.     

Spherical Bacterial Cellulose/TiO<Subscript>2</Subscript> Nanocomposite with Potential Application in Contaminants Removal from Wastewater by Photocatalysis

Contaminants are often found in aquatic environments, for instance, heavy metals, dyes, parasites, pesticides, hormones and pharmaceuticals. Therefore, large amounts of these contaminants reaches wastewater via industrial and domestic effluents, causing major concern to human health. Heterogeneous photocatalysis is a technique for removing these contaminants in order to achieve better efficiency in water treatment. Then, bacterial cellulose (BC) produced in an agitated culture can form spherical bodies composed of nanofibers with high specific surface area. Moreover, Titanium dioxide (TiO₂) is a semiconductor containing high photocatalytic activity capacity. Thus, the main objective in this work was to produce spherical BC/TiO₂ nanocomposites for contaminants removal from wastewater by photocatalysis process. The incorporation of TiO₂ nanoparticles in the spherical BC matrix was performed by ex situ and in situ methods. In addition, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) were used as tools of morphological, chemical and thermal characterizations of the nanocomposites. Besides, photocatalysis tests were performed in order to evaluate the removal efficiency of methylene blue from aqueous solutions. The results of these tests exhibited a percentage of methylene blue removal of 70.83 and 89.58 % after 35 minutes for spherical BC/TiO₂ nanocomposites both, in situ and ex situ, respectively. Therefore, these results demonstrated that BC/TiO₂ to be a low cost material with high capacity of contaminants removing and a great potential for industrial applications.     

Preparation,Characterization and Properties of High-salt-tolerance Sodium Alginate/Krill Protein Composite Fibers

Sodium alginate (SA) and krill protein (AKP) were blended to obtain composite solution, and functional SA/AKP composite fibers were prepared via wet spinning. To further improve the salt tolerance, SA/AKP composite fibers were modified with copper sulfate aqueous solution as secondary coagulation bath because of the strong adsorption to copper ions. The CSA/AKP composite fibers with high salt tolerance have been successfully prepared. The intermolecular interaction of SA/AKP composite system and the two-order structure of protein in the composite system were characterized by Fourier transform infrared spectroscopy (FT-IR). Besides, the crystallinity, morphology, mechanical properties, salt tolerance and water resistance and thermal stability of SA/AKP composites were investigated respectively. The results showed that the adsorption rate and the adsorption capacity of the composite solution to copper ion were significantly higher than those to calcium ion. Under the effect of secondary solidification by copper sulfate, the β-sheet chain of the composite fibers increased from 41.48 % to 49.21 %, the intramolecular hydrogen bond increased from 38.18 % to 44.26 %, the intermolecular hydrogen bond decreased from 59.84 % to 54.70 % and free hydroxyl slightly decreased. The water resistance of the modified composite fibers was improved by about 22 %; when the swelling time was 25 min, the salt resistance increased by about 150 %; the number of grooves on the surface of the composite fibers obviously increased, and the grooves on the surface of CSA/AKP composite fibers and the fiber section structure were much denser; Meanwhile, copper sulfate had some influence on the crystallization, thermal stability and mechanical properties of the composite fibers.     

Isolation,Characterization, Kinetics,and Enzymatic and Nonenzymatic Microbicidal Activities of a Novel c-Type Lysozyme from Plasma of Schistocerca gregaria (Orthoptera: Acrididae)

A protein, designated as Sgl, showing a muramidase lytic activity to the cell wall of the Gram-positive bacterium Micrococcus lysodeikticus was isolated for the first time from plasma of Escherichia coli-immunized fifth instar Schistocerca gregaria. The isolated Sgl was detected as a single protein band, on both native- and SDS-PAGE, has a molecular weight of ∼15.7 kDa and an isoelectric point (pI) of ca 9.3 and its antiserum has specifically recognized its isolated form. Fifty-nine percentage of Sgl lytic activity was recovered in the isolated fractions and yielded ca 126-fold increase in specific activity than that of the crude. The partial N-terminal amino acid sequence of the Sgl has 55 and 40% maximum identity with Bombyx mori and Gallus gallus c-type lysozymes, respectively. The antibacterial activity against the Gram-positive and the Gram-negative bacteria were comparatively stronger than that of the hen egg white lysozyme (HEWL). The detected Sgl poration to the inner membrane that reach a maximum ability after 3 h was suggested to operate as a nonenzymatic mechanism for Gram-negative bacterial cell lysis, as tested in a permease-deficient E. coli, ML-35 strain. Sgl showed a maximal muramidase activity at pH 6.2, 30–50°C, and 0.05 M Ca²⁺ or Mg²⁺; and has a K_m of 0.5 μg/ml and a V_max of 0.518 with M. lysodeikticus as a substrate. The Sgl displayed a chitinase activity against chitin with a K_m of 0.93 mg/ml and a V_max of 1.63.     

Spray Drying of Chitosan Acid Salts: Process Development,Scaling Up and Physicochemical Material Characterization

We investigated a spray drying process for preparing water-soluble salts of high molecular weight chitosan (CH) intended for pharmaceutical excipient applications. CH was derived from chitin of marine lobster origin (Panulirus argus). The effects of organic acid (acetic or lactic acid) and the ratio (difference) of inlet/outlet air temperature (140/90 °C or 160/100 °C) on spray drying were studied. The yield of spray-dried CH salt powders ranged from 50% to 99% in laboratory and industrial-scale processes. The spray-dried dry powder of CH salts consisted of spherical agglomerated particles with an average diameter of 36.2 ± 7.0 µm (CH acetate) and 108.6 ± 11.5 µm (CH lactate). After dispersing the spray-dried CH salt powder samples in purified water, the mean particle sizes obtained for the CH acetate salts were 31.4 nm (batch A001), 33.0 nm (A002) and 44.2 nm (A003), and for the CH lactate salts 100.8 nm (batch L001), 103.2 nm (L002) and 121.8 nm (L003). The optimum process conditions for spray drying were found: an inlet air temperature of 160 ± 5 °C, an outlet temperature of 100 ± 5 °C and an atomizer disk rotational speed of 18,200 min⁻¹. The X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) results confirmed the amorphous state of the CH salts. The ¹H nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectra of CH acetate and lactate salts verified that the spray drying process does not affect the polymer backbone. In conclusion, both laboratory and industrial-scale spray drying methods for preparing water-soluble acid salts of CH are reproducible, and the physicochemical properties of the corresponding CH acid salts are uniform.     

Spectroscopic Analyses on Chain Structure and Thermal Stabilization Behavior of Acrylonitrile/Methyl Acrylate/Itaconic Acid-based Copolymers Synthesized by Aqueous Suspension Polymerization

We have synthesized a series of copolymers with different compositions of acrylonitrile (AN, 80–100 wt%), methyl acrylate (MA, 4–20 wt%) and itaconic acid (IA, 0–3 wt%) by using an efficient aqueous suspension polymerization, and have investigated the molecular structure and thermal stabilization behavior of PAN homopolymer, AN/MA-based bipolymers, and AN/MA/IA-based terpolymers by adopting ¹H/¹³C-NMR and thermal FT-IR analyses. The viscosity-average molecular weight of the synthesized polymers were measured to be ~263,000 g/mol. The reactivity ratios of AN and MA for all the copolymers were evaluated to be 0.99 and 1.05, respectively. Accordingly, the output compositions of the synthesized copolymers were quite consistent with the input monomer compositions. The ¹³C NMR analysis revealed that all the synthesized polymers have an atactic chain configuration, regardless of the feed composition. The structural evolutions during the thermal stabilization process of the copolymers in air environment were characterized by monitoring the temperature-dependent changes of characteristic absorbance bands at 2240 cm^-1 (C≡N), 1595 cm^-1 (C=N) and 1660 cm^-1 (C=O) with aid of thermal FT-IR spectroscopy. It was found that the IA unit in the terpolymers accelerated the oxidation and cyclization reactions, unlike the retarding effect of MA unit, and that the onset temperatures of the oxidation reaction of the copolymers with IA unit was lower than that of the cyclization reaction.     

Preparation of Doxorubicin-Loaded Carboxymethyl-β-Cyclodextrin/Chitosan Nanoparticles with Antioxidant,Antitumor Activities and pH-Sensitive Release

In this study, chitosan nanoparticles (HF-CD NPs) were synthesized by an ionic gelation method using negatively charged carboxymethyl-β-cyclodextrin and positively charged 2-hydroxypropyltrimethyl ammonium chloride chitosan bearing folic acid. The surface morphology of HF-CD NPs was spherical or oval, and they possessed relatively small particle size (192 ± 8 nm) and positive zeta potential (+20 ± 2 mV). Meanwhile, doxorubicin (Dox) was selected as model drug to investigate the prepared nanoparticles’ potential to serve as a drug delivery carrier. The drug loading efficiency of drug-loaded nanoparticles (HF-Dox-CD NPs) was 31.25%. In vitro release profiles showed that Dox release of nanoparticles represented a pH-sensitive sustained and controlled release characteristic. At the same time, the antioxidant activity of nanoparticles was measured, and chitosan nanoparticles possessed good antioxidant activity and could inhibit the lipid peroxidation inside the cell and avoid material infection. Notably, CCK-8 assay testified that the nanoparticles were safe drug carriers and significantly enhanced the antitumor activity of Dox. The nanoparticles possessed good antioxidant activity, pH-sensitive sustained controlled release, enhanced antitumor activity, and could be expected to serve as a drug carrier in future with broad application prospects.     

Adsorption of fibronectin, fibrinogen, and albumin on TiO2: time-resolved kinetics, structural changes, and competition study

An understanding of protein adsorption process is crucial for designing biomaterial surfaces. In this work, with the use of a quartz-crystal microbalance with dissipation monitoring, we researched the following: (a) the kinetics of adsorption on TiO(2) surfaces of three extensively described proteins that are relevant for metallic implant integration [i.e., albumin (BSA), fibrinogen (Fbg), and fibronectin (Fn)]; and (b) the competition of those proteins for adsorbing on TiO(2) in a two-step experiment consisted of sequentially exposing the surfaces to different monoprotein solutions. Each protein showed a different process of adsorption and properties of the adlayer-calculated using the Voigt model. The competition experiments showed that BSA displaced larger proteins such as Fn and Fbg when BSA was introduced as the second protein in the system, whereas the larger proteins laid on top of BSA forming an adsorbed protein bi-layer when those were introduced secondly in the system.     

Breeding by selective introgression:Theory,practices, and lessons learned from rice

Future demands for increased productivity and resilience to abiotic/biotic stresses of major crops require new technologies of breeding by design (BBD) built on...     

中国贵州芽串孢属一新种——火棘芽串孢

通过对采自贵州省习水自然保护区暗色丝孢真菌的处理,发现了一个芽串孢属新种——火棘芽串孢Blastocatena pyracanthae,并对其进行了形态学特征描述和图解。研究标本保存在遵义师范学院真菌标本室(HMZNC)。