类维生素A与细胞因子

类维生素（Ｖｉｔ）Ａ能够促进免疫功能，本文综述了类ＶｉｔＡ通过调节细胞因子的表达而影响非特异性及特异性免疫功能，并指出了类ＴｉｔＡ调节细胞因子生成的可能机制──视黄酸受体途径。

Determination of phthalate esters in fat-containing foods by packed nanofiber solid-phase extraction column and gas chromatography

A new method for simultaneous determination of four phthalate esters （ PAEs） in commercial fat-containing foods was developed by the combination of a packed nanofibers column based on solid-phase extraction with gas chromatography-flame ionization detector （ GC-FID ）. Conditions for obtaining optimum extraction efficiency such as extraction solvents, morphologies of adsorbent, ion strength and pH were investigated and optimized in detail. Under the optimized conditions, the limits of detection （LODs） found for dibutyl phthalate （DBP） , butyl benzyl phthalate （BBP）, diethyl hexyl phthalate （DEHP） and di-n-octyl phthalate （DNOP） were 50, 25, 50 and 25 ng/g, respectively. Good linearity of four PAEs was achieved in the range of 50 to 4 000 ng/g. The proposed method was applied for analyzing different kinds of fat-containing samples. PAEs in commercial fat-containing samples can be highly extracted by a packed solid-phase extraction column of 5 mg polystyrene （ PS） nanofibers. The satisfactory average recoveries were obtained in the range of 96. 7% to 102. 3% , and the relative standard deviations （RSDs） below 5% were achieved. The proposed method reduces the organic solvent consumption, the complex and tedious procedures for sample pretreatment, and achieves high sensitivity and reproducibility for the investigated PAEs.

Effective production of γ-valerolactone from biomass-derived methyl levulinate over CuO_x-CaCO_3 catalyst

The production of?-valerolactone(GVL)from lignocellulosic biomass has become a focus of research owing to its potential applications in fuels and chemicals.In this study,(n)CuOx-CaCO3(where n is the molar ratio of Cu to Ca)compounds were prepared for the first time and shown to function as efficient bifunctional catalysts for the conversion of biomass-derived methyl levulinate(ML)into GVL,using methanol as the in-situ hydrogen source.Among the catalysts with varied Cu/Ca molar ratios,(3/2)CuOx-CaCO3 provided the highest GVL yield of 95.6% from ML.The incorporation of CaCO3 with CuO resulted in the formation of Cu+species in a CuOx-CaCO3 catalyst,which greatly facilitated the hydrogenation of ML.Notably,CuOx-CaCO3 also displayed excellent catalytic performance in the methanolysis products of cellulose,even in the presence of humins.Therefore,a facile two-step strategy for the production of GVL from cellulose could be developed over this robust and inexpensive catalyst,through the integration of cellulose methanolysis catalyzed by sulfuric acid,methanol reforming,and ML hydrogenation in methanol medium.

Properties of Surface Cyclic Oligomers Present on Polyester Fiber

The effects of different treatments, such as dry heat,wet heat, solvent vapor and ultrasonic, on propertiesof the cyclic oligomers on the surface of polyester fiberare studied. The components of surface oligomers areanalyzed through Thin-Layer Chromatograph. Theresult shows that: all of the treatment, especially solvent vapor treatment,call significantly increase the content of surface cyclic oligomers.The content of cyclic triIner is increased more considerably than other oligomers. Moreover,the morphology and thedistribution of surface cyclic oligomers are also different from different treatments:Dry heat and wet heat cause larger polygonal solids distributed evenly on the surface of fiber;solvent vapor nlakes fiber surface exhibit irregular rodlike crystal shapes randomly;ultrasonic treatment induces some obscureand smaller deposi^on the surface of fiber.

Microbubble ultrasound contrast agent with three esters and carboxylic methyl cellulose as main shell materials: Its preparation and imaging evaluation

Objective: To study on the preparation process of a new surfactant-based microbubble ultrasound contrast agent and to evaluate its contrast effects in vivo. Methods: Microbubble ultrasound contrast agent with three ester surfactants and other additives as its shell materials was prepared by sonication. Sulfur hexafluoride was adopted as the inner gas of the microbubbles. New methods through the combination of optical microscope and some softwares were used to measure the size distribution and the concentration of the microbubbles. Some parameters such as the pH value of the phosphate buffer, quantity of the carboxylic methyl cellulose in the shell materials, selection of the ultrasound power and process time, were studied. Six hybirded dogs were used to verify the in vivo contrast imaging of the contrast agent using second harmonic power Doppler modality. Safety and persistent time of the agent inner animal body were also investigated. Results: Ultrasound contrast agent prepared in the experiment had an average microbubble diameter of 3.95 microns with concentration of 3.6×109 microbubbles per millilitre. Carboxylic methyl cellulose was found as an important shell material which had obviously effect on the microbubble stability and production even with a little quantity. The buffer pH value also had a key role on the microbubble formation and the final production. When the buffer pH value reached 7.4, there was no microbubble produced. Under the approximate microbubble production, process time could be shorten with the increasing ultrasound power. The obvious ultrasound contrast imaging effects were detected in the dog's heart chamber and liver as well as kidney using only one millilitre agent when diluted. The agent was found safe to the dogs. At the same time, persistent time of the agent was found over 20 min in the dog's body. Conclusion: The new ultrasound contrast agent prepared in the experiment has high microbubble production and concentration, narrow microbubble size distribution ranging in several microns, well stability, little dosage needed in the contrast, well safety to the dogs and long persistent time, obvious contrast imaging effect in the dog's heart chamber, kidney and liver. These experiment data indicate that the new ultrasound contrast agent with three ester surfactants and carboxylic methyl cellulose as its main shell materials can be further developed for clinical purposes.

Evaluation of Impact Strength and Micro-Hardness of Denture Base Acrylic Resin （PMMA） Part Ⅱ

Poly （methyl methacrylate） is widely used as denture base material. During fabrication of a denture, the physical and mechanical properties are influenced by cure condition. Each cure cycle or fabrication technique is attempts to optimize the properties for a given application. The aim of this study was to compare two types of commercially available denture base materials （heat-cure and self-cure） in their mechanical properties. The samples were prepared according to the daily routine work for sample preparation in dental laboratories. After reaching dough stage the mix packed into dumbbell shaped of stainless steel mould and pressed in a hydraulic bench press for 25 mins at room temperature. For heat cure the polymerization cycle was carried out using water bath, while self cure was done at room temperature. The impact strength was evaluated using Charpy impact test. The hardness test was conducted using a calibrated Vickers hardness tester machine. The lowest impact strength was observed in self-cure denture base material （self cure material 6.2 kJ/m^2 while heat cure 12.69 kJ/m^2. It appears that the tendency of heat cure to fracture was lower than self-cure denture base materials. Heat cure denture base material has significantly higher hardness test values than self-cure denture base material. The observed VHN value of the heat-cure was 20.09 g/mm^2 while the self-cure value was 12.7 g/mm^2. This is may be due to the plasticizer effect of residual monomer which was higher in self curing material as reported in previous work. Generally, the heat cure material showed better properties compared to self cure material.

ESTMATION OF REALIZED HERITABILITY OF RESISTANCE TO FENPROPATHRIN,ABAMECTIN,PYRIDABEN AND THEIR MIXTURES IN ACARICIDE-SELECTED STRAINS OF TETRANYCHUS CINNABARINUS (BOIDUVAL)

Threshold trait analysis was used to estimate realized heritability (h 2) of re sistance to five acaricides (three single acaricide and two mixtures) and resistance risk in Tetranychus cinnabarinus (Boiduval). Tetranychus cinnabarinus collected from the field of Beibei, Chongqing reared more than 60 generations under pesticide free conditions and considered s usceptible. Successively selected for about 30 generations, the strain had a 65.55-, 5.82 - , 1.23-, 5.20- and 1.42-fold increase in resistance to fenpropathrin, abam ectin, pyridaben, pyridab en-abamectin (pyridaben: abamectin=7.4:0.1, m/m) and fenpropathrin-abamectin (fenpropathri n: abamectin=8.9:0.1, m/m), respectively. The realized heritability of resista nce t o fenpropathrin, abamectin, pyridaben, pyridaben-abamectin (pyridaben: abamectin=7.4:0.1, m/m) and fenpropathrin-abamectin (fenpropathrin: abamectin=8.9:0.1, m/m) is 0.2167, 0 .0967, 0.0130, 0.0800 and 0.0172, respectively. Under the selected condition, a 10-fold incr ease in resistance would be expected 15 generations for fenpropathrin, 34 generations for abamectin , 333 generations for pyridaben, 42 generations for pyridaben-abamectin (pyridaben: a bamectin=7.4:0.1, m/m) and 200 generations for fenpropathrin-abametcin (fenpropathrin: abamectin= 8.9:0.1, m/m). The highest resistance risk of the five acaricides in Tetranychus cinnabarinus was fenpropathrin, then abamection, pyridaben-abamectin (pyridaben: abamectin=7.4:0.1, m/m), fen propathrin- abamectin (fenpropathrin: abamectin=8.9:0.1, m/m) and that to py ridaben was the lowest. The mixture of pyridaben and abamectin is not useful in delaying development of resistance in the pest to the two single acaricide while the mixture of fenpropathrin and abamectin could do it.

Fabrication and characterization of electrospun biocompatible PU/PEGMA hybrid nanofibers by in-situ UV photopolymerization

Poly（ethylene glycol） methacrylate （PEGMA） was introduced into a polyurethane （PU） solution in order to prepare hemocom- patible electrospun membranes for potential application as small diameter vascular scaffolds. Crosslinked PU/PEGMA hybrid nanofibers were fabricated by a reactive electrospinning process with N,N＇-methylenebisacrylamide （MBAm） as erosslinker and benzophenone （BP） as photoinitiator. The photoinduced polymerization and crosslinking reaction took place simultane- ously during the electrospinning process. No significant difference in the membrane morphology was found by SEM when PEGMA content was less than 20 wt%. The crosslinked fibrous membranes of PU/PEGMA exhibit higher hydro- philicity and mechanical strength than PU membrane. These nanofibrous membranes are potential substitutes for artificial vascular scaffolds.

Biocompatibility Evaluation of Polyethylene Terephthalate Artificial Ligament Coating Hydroxyapatite by Fibroblasts Cells in Vitro

Hydroxyapatite(HA) based materials have been widely used in the field of ligament tissue engineering in the past decades.It has been previously reported that HA can increase the penetration of marrow-derived mesenchymal stem cells(MSCs) and MSCs cells into scaffolds due to increased cell differentiation in biological media.Additionally,it was found that there are much difference between MSCs and anterior cruciate ligament (ACL) cells.For that reason,we mainly evaluate the biocompatibility of polyethylene terephthalate(PET) silk scaffold with fibroblasts cells in vitro.We cultured mouse fibroblasts cells on the substrate of PET fiber and PET-HA scaffold,respectively,and then observed the morphology by using scanning electron microscopy.Our data indicate that PET-HA scaffold has good biocompatibility with fibroblasts cells and can potentially be useful in enhancing the fibroblasts cell differentiation and proliferation.