过渡金属Co2+离子掺杂ZnS硫化物纳米晶制备与中红外发光特性研究

利用不含有机相的简单水热法制备了Co^2+∶ZnS纳米晶,纳米晶具有立方闪锌矿结构,平均晶粒尺寸约为8.3 nm,在808 nm激光泵浦下具有2~5μm波段的中红外荧光发射,中心波长位于3400 nm和4700 nm,分别对应Co^2+离子的4T2(F)→4 A 1(F)和4T1(F)→4T2(F)的能级跃迁.进一步将制备的纳米晶在还原气氛下进行800℃热处理,获得立方闪锌矿和纤锌矿混合晶型的纳米晶,平均晶粒尺寸增大到22.5 nm左右,热处理后的纳米晶表面羟基含量更低,中红外荧光发射强度显著提高.该Co^2+∶ZnS纳米晶的制备方法简单、在制备过程中不引入有机相等荧光淬灭中心,同时证明通过后热处理过程可以进一步减少表面缺陷及羟基含量,使荧光强度得到大幅提升.     

Fabrication and characterization of cellulose nanoparticles from maize stalk pith via ultrasonic-mediated cationic etherification

In this study, parenchyma cellulose, which was extracted from maize stalk pith as an abundant source of agricultural residues, was applied for preparing cellulose nanoparticles (CNPs) via an ultrasound-assisted etherification and a subsequent sonication process. The ultrasonic-assisted treatment greatly improved the modification of the pith cellulose with glycidyltrimethylammonium chloride, leading to a partial increase in the dissolubility of the as-obtained product and thus disintegration of sheet-like cellulose into nanoparticles. While the formation of CNPs by ultrasonication was largely dependent on the cellulose consistency in the cationic-modified system. Under the condition of 25% cellulose consistency, the longer sono-treated duration yielded a more stable and dispersible suspension of CNP due to its higher zeta potential. Degree of substitution and FT-IR analyses indicated that quaternary ammonium salts were grafted onto hydroxyl groups of cellulose chain. SEM and TEM images exhibited the CNP to have spherical morphology with an average dimeter from 15 to 55 nm. XRD investigation revealed that CNPs consisted mainly of a crystalline cellulose Ι structure, and they had a lower crystallinity than the starting cellulose. Moreover, thermogravimetric results illustrated the thermal resistance of the CNPs was lower than the pith cellulose. The optimal CNP with highly cationic charges, good stability and acceptable thermostability might be considered as one of the alternatively renewable reinforcement additives for nanocomposite production.     

A comprehensive review on surface modification,structure interface and bonding mechanism of plant cellulose fiber reinforced polymer based composites

Abstract

Plant cellulose fiber polymer composites are readily applied in wide range of applications due to ecological and economical alternative to traditional materials. The considerable amount of residues and organic wastes from agricultural process are still employed as lower energy resource. Organic materials are generally disposed in composting, landfilling or anaerobic digestion. The utilization of these wastes in plant fiber composites shows significant alternative and environmental friendly in nature. The production of plant cellulose fiber composite with higher structural properties is optimized by interfacial bonding between polymer and reinforced fiber. The interface plays a vital role in regulating mechanical properties by distributing bonds and stress transferring, which is one of least understood element of composites. This paper presents the comprehensive review of fiber structures, different modification techniques to reduce the incompatibility between matrix and fiber, assessment of structure interface and bonding, clarifies the interfacial adhesion of cellulose fiber composites.     

Ultrasonic technology for enhanced oil recovery from failing oil wells and the equipment for its implemention

A new method for the ultrasonic enhancement of oil recovery from failing wells is described. The technology involves lowering a source of power ultrasound to the bottom of the well either for a short treatment before removal or as a permanent placement for intermittent use. In wells where the permeability is above 20 mD and the porosity is greater than 15% ultrasonic treatment can increase oil production by up to 50% and in some cases even more. For wells of lower permeability and porosity ultrasonic treatment alone is less successful but high production rates can be achieved when ultrasound is applied in conjunction with chemicals. An average productivity increase of nearly 3 fold can be achieved for this type of production well using the combined ultrasound with chemical treatment technology.     

Wastes Treatment: Hydrothermal electrolytic oxidation of wastewater

Abstract

Electrochemical evolution of hydrogen gas, oxygen gas and chlorine at the electrodes is the usual reaction in conventional electrolysis of aqueous salt solution. However, here we demonstrate that the electrolysis governing reaction in hydrothermal solutions is different from the electrolysis performed at atmospheric pressure and temperatures up to 100°C. Experimental electrolytic reaction of aqueous salt solution carried out inside a sealed 300-mL batch autoclave showed that; accumulation of hydrogen gas, oxygen gas and chlorine is highly suppressed under hydrothermal (250°C and 7 MPa) conditions. We have also observed that, when organics are present in the aqueous salt solution being hydrothermally electrolyzed, an effective oxidation of organics is accomplished. Furthermore, for hydrothermal electrolytic oxidation (HEO) with oxygen gas added, experimentally observed TOC removal profile demonstrates apparent anodic oxidation electrical current efficiency of almost 200% for highconcentrated acetic acid solutions.     

High-pressure treatment with silver carp (Hypophthalmichthys molitrix) protein and its allergic analysis

The allergenicity and structural changes of silver carp allergens influenced by high-pressure treatment were studied. We treated the allergens at 100, 200 and 300 MPa for 10, 30 and 60 min at 20° C, used SDS–PAGE to separate the proteins and recognized the allergens by western blotting. Circular dichroism analysis was performed to characterize the structural change. From our study, we can determine that high-pressure treatment did not change the subunit composition, molecular weight or the allergenicity of silver carp allergens, but it did change the structure of the allergens.     

A comparative in vitro study of the digestibility of heat- and high pressure-induced gels prepared from industrial milk whey proteins

We undertook this study to compare the digestibility of heat- and high pressure-induced gels produced from whey protein isolate (WPI). To simulate in vivo gastrointestinal digestion of WPI gels, a pepsin–trypsin digestion system was used. The in vitro protein digestibility of WPI gels induced by high pressure (400 MPa and 30 min; P-gel) and those induced by heat (80°C and 30 min; H-gel) was compared using a protein concentration of 0.14 g mL^?1. The in vitro protein digestibility of P-gels was significantly greater than that of H-gels (p<0.05). The size-exclusion chromatography profiles of the hydrolysates showed that the P-gel generated more and smaller peptides than natural WPI and H-gels. Furthermore, Sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis showed some soluble disulfide-mediated aggregation in the P-gel, while there was more insoluble aggregation in the H-gel than the P-gel. The P-gel was more sensitive to proteinase than the H-gel, which was related to the content of S–S bonds, and this in turn could be attributed to the differences in the gelation mechanism between the H-gel and P-gel.     

Surface modification of porous poly(tetrafluoraethylene) film by a simple chemical oxidation treatment

A simple, inexpensive and environmental chemical treatment process, i.e., treating porous poly(tetrafluoroethylene) (PTFE) films by a mixture of potassium permanganate solution and nitric acid, was proposed to improve the hydrophilicity of PTFE. To evaluate the effectiveness of this strong oxidation treatment, contact angle measurement was performed. The effects of treatment time and temperature on the contact angle of PTFE were studied as well. The results showed that the chemical modification decreased contact angle of as-received PTFE film from 133 ± 3° to 30 ± 4° treated at 100 °C for 3 h, effectively converting the hydrophobic PTFE to a hydrophilic PTFE matrix. The changes in chemical structure, surface compositions and crystal structure of PTFE were examined by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD), respectively. It was found that the F/C atomic ratio decreased from untreated 1.65-0.10 treated by the mixture at 100 °C for 3 h. Hydrophilic groups such as carbonyl (CO) and hydroxyl (OH) were introduced on the surface of PTFE after treatment. Furthermore, hydrophilic compounds K_0.27MnO₂·0.54H₂O was absorbed on the surface of porous PTFE film. Both the introduction of hydrophilic groups and absorption of hydrophilic compounds contribute to the significantly decreased contact angle of PTFE.     

质子治癌进展

一些国家利用质子治癌取得良好疗效，质子束的优良剂量分布特性使剂量集中于肝瘤，减少了对周围正常组织不必要的伤害。文章介绍了治疗装置，治疗过程及其最近的发展。