Effect of adhesive on the morphology and mechanical properties of electrospun fibrous mat of cellulose acetate

Ultrafine fibers of cellulose acetate/poly(butyl acrylate) (CA/PBA) composite in which PBA acted as an adhesive and CA acted as a matrix, were successfully prepared as fibrous mat via electrospinning. The morphology observation from the electrospun CA/PBA composite fibers, after treatment with heat hardener, revealed that the fibers were cylindrical and had point-bonded structures. SEM, FT-IR spectra, Raman spectra, TGA analysis, and mechanical properties measurement were used to study the different properties of hybrid mats. The tensile strength of blend fibrous electrospun mats was found to be effectively increased. This resultant enhancement of the mechanical properties of polymer fibrous mats, caused by generating the point-bonded structures (due to adhesive), could increase the number of potential applications of mechanically weak electrospun CA fibers.     

人、猴、兔BPI活性部位基因的克隆和序列分析

为比较不同动物来源杀菌／通透性增加蛋白（BPI）的活性部位在基因组成上的差异,为今后对人BPI进行分子改构打下基础,分别从人、恒河猴和家兔外周血白细胞中克隆出BPI全长或活性部位基因,进行序列分析和比较,并进行蛋白二级结构预测。结果发现：猴、兔BPI活性部位序列与人序列在核苷酸水平的同源性分别为94％和77％,在氨基酸水平的同源性分别为88％和62％;人氨基酸序列中包含一个糖基化位点,而猴、兔序列没有;兔序列比人、猴序列少一个氨基酸;3种BPI活性部位有近似的二级结构。     

Preparation and bactericidal activity of oxidation derivatives of austroeupatol,an ent-nor-furano diterpenoid of the labdane series from Austroeupatorium inulifolium

From aerial parts of Austroeupatorium inulifolium was obtained austroeupatol (1). The treatment of 1 with IBX generated the ketone 2 and keto-aldehyde 3. Due to the structural features of 1, the hydroxy group corresponding to the primary alcohol (at C-19) is less reactive than the oxymethine hydroxy groups of the structure. The oxidative cleavage of 1 produced the hemiacetal 4, since this reaction is quantitative and only this compound was detected, was proposed a reaction mechanism that involves the formation of a transition state that explain the generation of 4. The bactericidal activity of these oxidation derivatives was evaluated against four (4) bacterial strains [two Gram-positive (+) and two Gram-negative (-)]: Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa.     

Dual-mode security authentication of SrAl2O4:Eu,Dy phosphor encapsulated in electrospun cellulose acetate nanofibrous films

Photochromic inks have been an attractive authentication strategy to improve the anti-counterfeiting efficiency of commercial products. However, recent reports have shown significant disadvantages with photochromic inks, including poor durability and high cost. In this context, we developed novel photochromic nanofibres for advanced anti-counterfeiting applications. Lanthanide-doped strontium aluminate (LdSA) nanoparticles (NPs) were prepared and immobilized into electrospun cellulose acetate nanofibres (CANF). Authentication materials immobilized with inorganic photochromic agents can warranty durability and photostability. Therefore, the ultraviolet-stimulated photochromism of LdSA-encapsulated cellulose acetate nanofibres (LdSA@CANF) demonstrated high reversibility and photostability. A broad range of cellulose acetate nanofibres with unique emission characteristics was developed when applying different ratios of LdSA NPs. LdSA@CANF appeared colourless under visible daylight, whereas a green emission was monitored under ultraviolet-light illumination. The shape and chemical content of the photochromic fibrous films were examined using various analytical techniques. The mechanical characteristics of LdSA@CANF-coated paper were investigated. The emission wavelength was detected at 514 nm to designate green colour, whereas the excitation wavelength was detected at 369 nm to indicate transparency. The prepared cellulose acetate nanofibrous film can be described as an efficient strategy for the anti-counterfeiting of commercialized items.     

Green synthesis and characterization of Carica papaya leaf extract coated silver nanoparticles through X-ray diffraction,electron microscopy and evaluation of bactericidal properties

The evolution of nanotechnology and the production of nanomedicine from various sources had proven to be of intense value in the field of biomedicine. The smaller size of nanoparticles is gaining importance in research for the treatment of various diseases. Moreover the production of nanoparticles is eco-friendly and cost effective. In the present study silver nanoparticles were synthesized from Carica papaya leaf extract (CPL) and characterized for their size and shape using scanning electron microscopy and transmission electron microscopy, respectively. Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDS/EDX) and X-ray diffraction spectroscopy (XRD) were conducted to determine the concentration of metal ions, the shape of molecules. The bactericidal activity was evaluated using Luria Bertani broth cultures and the minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) were estimated using turbidimetry. The data analysis showed size of 50–250 nm spherical shaped nanoparticles. The turbidimetry analysis showed MIC and MBC was >25 μg/mL against both Gram positive and Gram negative bacteria in Luria Bertani broth cultures. In summary the synthesized silver nanoparticles from CPL showed acceptable size and shape of nanoparticles and effective bactericidal activity.     

Effect of aeration rate on the anti-biofouling properties of cellulose acetate nanocomposite membranes in a membrane bioreactor system for the treatment of pharmaceutical wastewater

Abstract

The adhesiveness and stability of ubiquitously distributed biofilms is a significant issue in many areas such as ecology, biotechnology and medicine. The magnetic particle induction (MagPI) system allows precise determinations of biofilm adhesiveness at high temporal and spatial resolution on the mesoscale. This paper concerns several technical aspects to further improve the performance of this powerful experimental approach and enhance the range of MagPI applications. First, several electromagnets were built to demonstrate the influence of material and geometry with special regard to core remanence and magnetic strength. Secondly, the driving force to lift up the particles was evaluated and it was shown that both the magnetic field strength and the magnetic field gradient are decisive in the physics of the MagPI approach. The intricate combination of these two quantities was demonstrated with separate experiments that add permanent magnets to the MagPI system.     

Optical resolution and mechanism using enantioselective cellulose,sodium alginate and hydroxypropyl‐β‐cyclodextrin membranes

Chiral solid membranes of cellulose, sodium alginate, and hydroxypropyl‐β‐cyclodextrin were prepared for chiral dialysis separations. After optimizing the membrane material concentrations, the membrane preparation conditions and the feed concentrations, enantiomeric excesses of 89.1%, 42.6%, and 59.1% were obtained for mandelic acid on the cellulose membrane, p ‐hydroxy phenylglycine on the sodium alginate membrane, and p ‐hydroxy phenylglycine on the hydroxypropyl‐β‐cyclodextrin membrane, respectively. To study the optical resolution mechanism, chiral discrimination by membrane adsorption, solid phase extraction, membrane chromatography, high‐pressure liquid chromatography ultrafiltration were performed. All of the experimental results showed that the first adsorbed enantiomer was not the enantiomer that first permeated the membrane. The crystal structures of mandelic acid and p ‐hydroxy phenylglycine are the racematic compounds. We suggest that the chiral separation mechanism of the solid membrane is “adsorption – association – diffusion,” which is able to explain the optical resolution of the enantioselective membrane. This is also the first report in which solid membranes of sodium alginate and hydroxypropyl‐β‐cyclodextrin were used in the chiral separation of p ‐hydroxy phenylglycine.     

Interplay of Optical,Morphological, and Electronic Effects of ZnO Optical Spacers in Highly Efficient Polymer Solar Cells

Optical spacers based on metal oxide layers have been intensively studied in poly(3‐hexylthiophene) (P3HT) based polymer solar cells for optimizing light distribution inside the device, but to date, the potential of such a metal oxide spacer to improve the electronic performance of the polymer solar cells simultaneously has not yet be investigated. Here, a detailed study of performance improvement in high efficient polymer solar cells by insertion of solution‐processed ZnO optical spacer using ethanolamine surface modification is reported. Insertion of the modified ZnO optical spacer strongly improves the performance of polymer solar cells even in the absence of an increase in light absorption. The electric improvements of the device are related to improved electron extraction, reduced contact barrier, and reduced recombination at the cathode. Importantly, it is shown for the first time that the morphology of optical spacer layer is a crucial parameter to obtain highly efficient solar cells in normal device structures. By optimizing optical spacer effects, contact resistance, and morphology of ZnO optical spacers, poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6diyl] [3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl] thieno[3,4‐b]thiophenediyl]] (PTB7):[6,6]‐phenyl‐C71‐butyric acid (PC₇₀BM) bulk heterojunction solar cells with conversion efficiency of 7.6% are obtained in normal device structures with all‐solution‐processed interlayers.     

Solution properties of starch nanoparticles in water and DMSO as studied by dynamic light scattering

Solution properties of starch nanoparticles dispersed in DMSO and in water were studied using dynamic light scattering. The particle size distribution had two main peaks in both solvents at all scattering angles studied. They were at around 40 and 300 nm, ascribed to isolated starch nanoparticles and their aggregates, respectively. From the excess scattering intensity by the 40-nm particles, the molecular weight of the nanoparticle was estimated as 2.2–2.6×10⁶ g/mol. When the concentration was increased, another peak appeared at around 1 μm. Raising the temperature from 25 to 65 °C did not change the distribution, indicating a purely entropic process in dynamic equilibrium of the aggregation. In DMSO, an oscillatory behavior was observed in the autocorrelation function at high temperatures.     

Purification, characterization and bactericidal activities of basic phospholipase A2 from the venom of Agkistrodon halys (Chinese pallas)

Agkistrodon snake venoms contain a variety of phospholipases (PLA(2)), some of which are myotoxic. In this study, we used reverse-phase HPLC to purify PLA(2) from the venom of Agkistrodon halys. The enzyme named as AgkTx-II, a basic Asp49 PLA(2), has a molecular masses of 13,869.05. The amino acid sequence and molecular mass of AgkTx-II was identical to those of an Asp49 basic myotoxic PLA(2) previously isolated from this venom. Antibacterial activities were tested by susceptibility and broth-dilution assays. AgkTx-II exerted a potent antibacterial activity against Staphylococcus aureus, Proteus vulgaris, Proteus mirabilis, and Burkholderia pseudomallei. The MIC values of AgkTx-II ranged between 85 and 2.76muM and was most effective against S. aureus, P. vulgaris, P. mirabilis (MIC of 21.25muM) and B. pseudomallei (MIC of 10.25muM). This AgkTx-II rapidly killed S. aureus, P. vulgaris and B. pseudomallei in a dose-dependent manner. The effect of the AgkTx-II on bacterial membranes was evaluated by scanning and transmission electron microscopy. AgkTx-II caused morphological alterations apparent on their cellular surfaces, suggesting a killing mechanism based on membrane permeabilization and damage. Cytotoxicity was measured by XTT tetrazolium (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) and lactate dehydrogenase (LDH) assays using U-937 cells (monocytes). The AgkTx-II did not affect cell viability up to 500muM concentrations but cell death was evident at 1000muM concentration after 24 and 48h. Furthermore, the repeated exposure of AgkTx-II (2-14muM) treated mice showed different tissue alterations, mainly at the brain and kidney; the toxicological potential of AgkTx-II remains to be elucidated. The AgkTx-II exhibits no hemolytic action even at high doses (10-100muM) in human erythrocytes. However, the AgkTx-II is believed to exert its bactericidal effect by permeabilizing the bacterial membrane by forming pores. In addition, the basic PLA(2) AgkTx-II displays a bactericidal effect, which may be either dependent or independent of catalysis.     

Exploiting the exceptional biosynthetic potency of the endophytic Aspergillus terreus in enhancing production of Co3O4, CuO,Fe3O4, NiO,and ZnO nanoparticles using bioprocess optimization and gamma irradiation

Developing a suitable applicative process and scaling up the microbial synthesis of nanomaterials is an attractive and emerging prospect for a future sustainable industrial production. In this paper, optimization of fermentation conditions for enhanced production of Co₃O₄, CuO, Fe₃O₄, NiO, and ZnO nanoparticles by the endophytic A. terreus ORG-1 was studied. Different cultivation conditions were evaluated. Then, a response surface methodology program was used to optimize physical conditions controlling the biosynthesis of these NPs. Finally, the use of gamma irradiation for improvement of NPs’ production was adopted. Under the optimum conditions and after gamma irradiation, the final yields of the respective NPs reached 545.71, 651.67, 463.19, 954.88, 1356.42 mg L⁻¹. To the best of our knowledge, this is the first report on the production and enhancement of different types of nanomaterials from one microbial culture that can open up the way towards the industrialization of the microbial production of nanomaterials.     

Synthesis and properties of polyaniline–cellulose acetate blends: The use of sugarcane bagasse waste and the effect of the substitution degree

Membranes of blends of polyaniline (PANi) and cellulose acetate (CA) produced from sugarcane bagasse with different degrees of substitution were produced and characterized using various techniques. Results showed that incorporation of PANi into the CA matrices leads to significant alterations of the blend morphologies, with phase separation, and that these differences are less significant for PANi/cellulose triacetate blends. The blends also showed a significant increase in electrical conductivity, with that of PANi/cellulose diacetate demonstrating an almost 200-fold increase.     

Synthesis and properties of pullulan acetate. Thermal properties, biodegradability, and a semi-clear gel formation in organic solvents

Pullulan acetate (AcPL) with various degree of substitution (DS: 1.0–3.0) was synthesized by the reaction of pullulan with acetyl chloride in the presence of pyridine. The product was characterized by gel permeation chromatography (GPC), infra-red (IR) and ¹H NMR spectroscopy. The weight average molecular weights of the products did not decrease less than 190,000 (GPC) in the acetylation reaction. Thermogravimetric analysis (TGA) revealed that AcPL has a higher decomposition temperature (306–363 °C) than unmodified pullulan (295 °C). Differential scanning calorimetry analysis (DSC) revealed that all the AcPLs exhibit a clear T_g, which decreased with increasing DS value in the range of DS 1.0–2.4. The AcPL with DS 2.4 showed the lowest T_g (153 °C), and the AcPL with DS 3.0 had a slightly higher T_g (163 °C). Tensile modulus of AcPL films was comparable to that of a popular cellulose acetate film. The biodegration rate of AcPL decreased with increasing degree of acetylation. The AcPL with DS 3.0 was found to form a semi-clear gel in organic solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and 1,4-dioxane.     

The alteration of mRNA expression of SOD and GPX genes,and proteins in tomato (Lycopersicon esculentum Mill) under stress of NaCl and/or ZnO nanoparticles

Five cultivars of tomato having different levels of salt stress tolerance were exposed to different treatments of NaCl (0, 3 and 6 g L⁻¹) and ZnO-NPs (0, 15 and 30 mg L⁻¹). Treatments with NaCl at both 3 and 6 g L⁻¹ suppressed the mRNA levels of superoxide dismutase (SOD) and glutathione peroxidase (GPX) genes in all cultivars while plants treated with ZnO-NPs in the presence of NaCl, showed increments in the mRNA expression levels. This indicated that ZnO-NPs had a positive response on plant metabolism under salt stress. Superior expression levels of mRNA were observed in the salt tolerant cultivars, Sandpoint and Edkawy while the lowest level was detected in the salt sensitive cultivar, Anna Aasa. SDS–PAGE showed clear differences in patterns of protein expression among the cultivars. A negative protein marker for salt sensitivity and ZnO-NPs was detected in cv. Anna Aasa at a molecular weight of 19.162 kDa, while the tolerant cultivar Edkawy had two positive markers at molecular weights of 74.991 and 79.735 kDa.     

太湖水体漫射衰减系数的光学特性及其遥感反演模型

利用2007年11月8—22日太湖实测光谱数据和水质分析数据,分析了秋季太湖水体漫射衰减系数（K_d）的光谱特性及其影响因子,并在此基础上,利用水面以上遥感反射率, 以490 nm波长的漫射衰减系数［K_d(490)］作为中间变量,建立了漫射衰减系数与水面以上遥感反射率的遥感反演模型.结果表明：在可见光波段范围内,秋季太湖水体大部分点位的漫射衰减系数随波长的增加呈指数递减趋势;由于部分点位浮游藻类的含量较高,对漫射衰减系数影响较大,导致这些点位的漫射衰减系数在波长675 nm附近出现峰值;无机悬浮物对漫射衰减系数的影响大于有机悬浮物,主要是由于悬浮物中无机悬浮物的含量远大于有机悬浮物.漫射衰减系数与遥感反射率具有很好的相关性,以R_rs(550)、R_rs(675)、R_rs(731)作为自变量,与K_d(490)进行回归分析,得出K_d(490)与R_rs(731)具有很好的线性关系,而利用R_rs(550)、R_rs(675)、R_rs(731)进行多元线性回归的效果（R²>0.96）好于单波段［R_rs731)］算法.     

Effects of cellulose derivatives and carrageenans on the pasting, paste, and gel properties of rice starches

Effects of different cellulose derivatives and carrageenans on the pasting, rheological, and textural properties of normal (NRS) and waxy (WRS) rice starches were investigated. When suspensions of both NRS and WRS were heated in a Rapid Visco Analyser (RVA) in the presence of the hydrocolloids, increases in apparent pasting temperatures and peak and final viscosities in the following decreasing order were observed: methylcellulose (MC) > carboxymethylcellulose (CMC) for cellulose derivatives and λ- > í- > κ-carregeenan for carrageenans. Slight decreases in peak and final viscosities were observed when hydroxypropylmethylcellulose (HPMC) was the hydrocolloid. Dynamic viscoelasticity measurements indicated that NRS–hydrocolloid pastes were less solid-like than the control, as evidenced by their higher tan δ values, whereas tan δ values of WRS–hydrocolloid pastes were the same as that of the control. Steady shear rheological measurements showed that addition of the different hydrocolloids used increased the apparent viscosity (η_a,100) and consistency coefficient (K) values of both starches with the same trend as that observed during pasting, whereas the opposite trend was observed for the flow behavior index (n) values. The hardness and adhesiveness of NRS pastes were significantly increased by addition of κ- and í-carrageenans, but were unaffected by the other hydrocolloids. A similar effect was observed for WRS, with the exception of κ-carregeenan, in which the hardness of the mixed paste was decreased. The starch–hydrocolloid pastes exhibited a phase-separated microstructure in which amylose- and amylopectin-rich domains were dispersed in a hydrocolloid-rich continuous phase.     

三种金属氧化物纳米颗粒的水生态毒性

参考国际经济合作与发展组织(OECD)化学品生态毒性测试标准方法,以绿藻(Scenedesmus oblignus)和大型蚤(Daphnia magna)为受试生物,研究了3种金属氧化物纳米颗粒(纳米氧化锌nZnO、纳米二氧化钛nTiO2、纳米氧化铝nAl2O3)水悬浮液的水生生态毒性.结果发现,不同的纳米颗粒具有不同的毒性:nZnO、nTiO2和nAl2O3对斜生栅藻生长的 96 h半效应浓度(EC50)值分别为1.049、15.262、>1000 mg · L-1,而对大型蚤活动抑制的 48 h EC50 值则分别为0.622、35.306 mg · L-1和114.357 mg · L-1.据此可得到3 种金属氧化物纳米颗粒水悬浮液的毒性大小顺序为:nZnO ＞nTiO2 ＞ nAl2O3.此外,不同的生物对金属氧化物纳米颗粒的敏感性也不同,除nTiO2以外,大型蚤对另外2种纳米颗粒的敏感性强于斜生栅藻.实验结果表明,人工纳米材料的生态毒性和环境效应不容忽视,应重视并深入研究此类纳米材料的毒性作用机制和影响因子,以便能对其进行更好的风险管理.     

Vitrification of carnation in vitro: Changes in cell wall mechanical properties,cellulose and lignin content

Vitrification of internodes of carnation was brought about by culturing in liquid medium. Cell wall extensibility of these internodes was kinetically followed in comparison to that of normal plants using the constant stress method. Liquid culture induced increased immediate and total deformation capacities of the walls from the second day. Measurements indicated that these deformation capacities involved plastic properties rather than elastic ones. These changes were paralleled by decreased relative levels of cellulose and lignin.