从化工原理干燥实验教学现状和问题出发,针对干燥实验设备功能简单、实验内容单一、教学方法陈旧等问题,对干燥实验设备和实验内容进行了更新和扩展,形成一个实验内容丰富、设备种类多、测控手段先进的干燥综合实验平台;并对干燥实验教学方法进行改革,采用强化预习要求、独立实验及实验后讨论等方式,调动了学生的主动性和学习兴趣,教学质量得到了明显改善.

Research and development of the ideal artificial bone-substitute materials to replace autologous and allogeneic bones for repairing bone defects is still a challenge in clinical orthopedics. Recently, poly(lactic-co-glycolic acid) (PLGA)-based artificial bone-substitute materials are attracting increasing attention as the benefit of their suitable biocompatibility, degradability, mechanical properties, and capabilities to promote bone regeneration. In this article, we comprehensively review the artificial bone-substitute materials made from PLGA or the composites of PLGA and other organic and inorganic substances, elaborate on their applications for bone regeneration with or without bioactive factors, and prospect the challenges and opportunities in clinical bone regeneration.

Tissue engineering is a promising strategy for the repair of large-scale bone defects, in which scaffolds and growth factors are two critical issues influencing the efficacy of bone regeneration. Unfortunately, the broad application of growth factors is limited by their poor stability in the scaffolds. In the present study, the strictly controlled expression of human bone morphogenetic protein-4 (hBMP-4) in the presence of doxycycline is achieved by adding an hBMP-4 gene fragment into a non-viral artificial restructuring plasmid vector (pSTAR) to form the pSTAR-hBMP-4 plasmid (phBMP-4). Furthermore, the controlled release of phBMP-4 is obtained with an electroactive tissue engineering scaffold, generated by combining a triblock copolymer of poly(l-lactic acid)-block-aniline pentamer-block-poly(L-lactic acid) (PLA-AP) with poly(lactic-co-glycolic acid)/hydroxyapatite (PLGA/HA). This PLGA/HA/PLA-AP/phBMP-4 composite scaffold, with controlled gene release and Dox-regulated gene expression upon electrical stimulation, operating synergistically, exhibits an improved cell proliferation ability, enhanced osteogenesis differentiation in vitro, and effective bone healing in vivo in a rabbit radial defect model. Taking these results together, the proposed smart PLGA/HA/PLA-AP/phBMP-4 scaffold lays a solid theoretical and experimental basis for future applications of such multi-functional materials in bone tissue engineering to help patients in need.

Poly(lactic acid) (PLA) microspheres are widely used in the field of tissue engineering. However, cell adhesion and proliferation on PLA microspheres is limited due to the lack of hydrophilicity and cell recognition sites on microspheres surface. Current methods used to modify PLA microspheres are either complicated or expensive. Aminolysis and hydrolysis are two simple and economical degradation methods. However, up to now, there are few studies using aminolysis or hydrolysis to directly modify PLA microspheres and alter the cell growth behaviour on microspheres. In this study, aminolysis and hydrolysis were used to modify the surface of porous PLA microspheres. After the surface modification, PLA microspheres showed a finely porous structure. Cell culture experiments showed that the modification successfully made the surface of porous PLA microspheres more favourable for cell binding and growth. The increases of porosity, polar groups, hydrophilicity and roughness on microspheres surface were good to cell attachment and proliferation. This study shows that the aminolysis and hydrolysis are simple and effective methods to modify porous PLA microspheres for promoting cell grow on them.

Polymer nanogels, which are nanosized particles of hydrogels formed by physically or chemically crosslinking polymers, are one of the most promising nanoplatforms for use in biomedical applications, including drug delivery, gene therapy, and bioimaging. Polypeptide nanogels exhibit many advantages for applications in biomedical fields, including stable 3D structures, high drug-loading efficiency, excellent biocompatibility, stimuli responsiveness, and so forth. More specifically, smart polypeptide nanogels undergo suitable transitions under endogenous (e.g., reduction, reactive oxygen species, pH, and enzymes) or exogenous stimuli (e.g., light, temperature, voltage, and magnetic fields) for on-demand drug delivery. Here, a comprehensive introduction to the preparation and applications of diverse stimuli-responsive polypeptide nanogels is given. Moreover, the opportunities and challenges of polypeptide nanogels for the development of biomedicine are briefly predicted.

在我国高等教育加快国际化步伐的背景下,化工仪表及自动化课程和相关实验教学结合国际化大趋势和本课程特点,在教学中进行了一系列、多方面的改革与探索,在教学中培养学生的国际化思维.

We report a novel fabrication method using melt-spun sacrificial microfibers to make 3D interconnected microchannel scaffolds for improved cellular infiltration. The uniformly distributed cells in the highly porous microchannel scaffold maintained high cellular viability and glycosaminoglycan secretion indicating the good inter-connectivity facilitates the smooth delivery of cells throughout the scaffold and allows sufficient oxygen and nutrient mass transport into the scaffold.

In order to architecturally and functionally mimic native Extracellular Matrix (ECM), a novel micro/nano-fibrous scaffold of hydroxyapetite/poly(lactide-co-glycolide) (HA/PLGA) composite was successfully prepared by melt-spinning method. A porous three-dimensional scaffold fabricated by melt-molding particulate-leaching method was used as control. This kind of scaffold comprising both nanofiber and microfiber had an original structure including a nano-network favorable for cell adhesion, and a micro-fiber providing a strong skeleton for support. The microfibers and nanofibers were blended homogeneously in scaffold and the compression strength reached to 6.27 MPa, which was close to human trabecular bone. The typical micro/nano-fibrous structure was more beneficial for the proliferation and differentiation of Bone Mesenchymal Stem Cells (BMSCs). The calcium deposition and Alkaline Phosphatase (ALP) activity were evaluated by the differentiation of BMSCs, and the results indicated that the temporary ECM was very beneficial for the differentiation of BMSCs into maturing osteoblasts. For repairing rabbit radius defects in vivo, micro/nano-fibrous scaffold was used for the purpose of rapid bone remodeling in the defect area. The results showed that a distinct bony callus of bridging was observed at 12 weeks post-surgery and the expression of osteogenesis-related genes (bone-morphogenetic protein-2, Osteonectin, collagen-I) increased because of the ECM-like structure. Based on the results, the novel micro/nano-fibrous scaffold might be a promising candidate for bone tissue engineering.

In this study, a novel electroactive tetreaniline-containing degradable polyelectrolyte multilayer film (PEM) coating [(poly(l-glutamic acid)-graft-tetreaniline/poly(l-lysine)-graft-tetreaniline)n, (PGA-g-TA/PLL-g-TA)n] was designed and fabricated by layer-by-layer (LbL) assembly method. Compared with the nongrafted PEMs, the tetreaniline-grafted PEMs showed higher roughness and stiffness in micro/nanoscale structures. The special surface characteristics and the typical electroconductive properties were more beneficial for adhesion, proliferation, and differentiation of preosteoblast MC3T3-E1 cells. Moreover, the enhanced effects were observed on the modulation of MC3T3-E1 cells that differentiated into maturing osteoblasts, when the electroactive PEMs were coupled with electrical stimulus (ES), especially in the early phase of the osteoblast differentiation. The alkaline phosphatase (ALP) activity, calcium deposition, immunofluorescence staining, and RT-qPCR were evaluated on the differentiation of preosteoblast. These data indicate that the comprehensive effects through coupling electroactive scaffolds with electrical stimulus are better to develop bioelectric strategies to control cell functions for bone regeneration.

The biodegradable porous composite scaffold, composed of poly(lactide-co-glycolide) (PLGA) and hydroxyapatite nanoparticles (n-HAP) surface-grafted with poly(L-lactide) (PLLA) (g-HAP) (g-HAP/PLGA), was fabricated using the solvent casting/particulate leaching method, and its in vivo degradation behavior was investigated by the intramuscular implantation in rabbits. The composite of un-grafted n-HAP/PLGA and neat PLGA were used as controls. The scaffolds had interconnected pore structures with average pore sizes between 137 μm and 148 μm and porosities between 83% and 86%. There was no significant difference in the pore size and porosity among the three scaffolds. Compared with n-HAP/PLGA, the thermo-degradation temperature (T c) of g-HAP/PLGA decreased while its glass transition temperature (T g) increased. The weight change, grey value analysis of radiographs and SEM observation showed that the composite scaffolds of g-HAP/PLGA and n-HAP/PLGA showed slower degradation and higher mineralization than the pure PLGA scaffold after the intramuscular implantation. The rapid degradation of PLGA, g-HAP/PLGA and n-HAP/PLGA occurred at 8–12 weeks, 12–16 weeks and 16–20 weeks, respectively. Compared with n-HAP/PLGA, g-HAP/PLGA showed an improved absorption and biomineralization property mostly because of its improved distribution of HAP nanoparticles. The levels of both calcium and phosphorous in serum and urine could be affected to some extent at 3–4 weeks after the implantation of g-HAP/PLGA, but the biochemical detection of serum AST, ALT, ALP, and GGT as well as BUN and CRE showed no obvious influence on the functions of liver and kidney.

In order to tune the surface properties of hydroxyapatite(HA) nanoparticles and prevent them from aggregation, an efficient method was proposed to graft chitosan(CS) molecules on the surface of HA via “click” reaction. Thermal gravimetric analysis(TGA) shows that CS was successfully grafted on the surface of HA nanoparticles and the grafting amount was about 8.9 g of CS on per hundred grams of HA. The grafted chitosan chains can prevent HA nanoparticles from aggregation and greatly enhance the colloidal stability of HA in water. The 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay demonstrats that the cytotoxicity of CS modified HA(HA-CS) is negligible and thus HA-CS may find potential application in biomedical fields.

The injectable electroactive and antioxidant hydrogels are prepared from mixing the tetraaniline functional copolymers and α-cyclodextrin (α-CD) aqueous solution. UV-vis and CV of the copolymer solution showed good electroactive properties. The antioxidant ability of the copolymer is also proved. The gelation mechanism and properties of the system are studied by WAXD, DSC, and rheometer. The encapsulated cells are highly viable in the hydrogels, suggesting that the hydrogels have excellent cytocompatibility. After subcutaneous injection, H&E staining study suggests acceptable biocompatibility of the materials in vivo. Moreover, data shows the injectable electroactive material can effectively accelerate the proliferation of encapsulated cells with electrical stimuli, and the mechanism is also elaborated. Such an injectable electroactive hydrogel would more closely mimic the native extracellular matrix, thereby combining a biomimetic environment of long-term cell survival and electrical signal to support the generation of functional tissue.

This paper establishes a short-term prediction model of weekly retail prices for eggs based on chaotic neural network with the weekly retail prices of eggs from January 2008 to December 2012 in China. In the process of determining the structure of the chaotic neural network, the number of input layer nodes of the network is calculated by reconstructing phase space and computing its saturated embedding dimension, and then the number of hidden layer nodes is estimated by trial and error. Finally, this model is applied to predict the retail prices of eggs and compared with ARIMA. The result shows that the chaotic neural network has better nonlinear fitting ability and higher precision in the prediction of weekly retail price of eggs. The empirical result also shows that the chaotic neural network can be widely used in the field of short-term prediction of agricultural prices.

自去年9月以来，全国鸡蛋价格持续走低。今年2月份，北京市场鸡蛋价格曾一度跌至每公斤5．81元，达到今年以来的最低价格。根据批发市场的监测数据．从12月份开始鸡蛋生产者已经处于亏损状态。在国内市场蛋价呈现下跌态势的情况下,国外市场，美国鸡蛋的批发价格环比呈现下降态势。专家预计，未来鸡蛋价格将继续下跌。针对目前情况，相关部门应采取措施保护养殖户的生产积极性和利益。

通过对2011年中国禽蛋市场形势的分析,指出全年鸡蛋价格高位运行,9月鸡蛋价格创下历史新高。蛋鸡养殖成本上升,但2011年养殖效益仍处于历史较好时期。养殖成本上升是推动蛋价走高的直接原因,市场供需基本平衡是维持蛋价高位的根本因素,农产品价格的普遍上扬是蛋价上涨的助推因素。2012年上半年,禽蛋市场供给充分,蛋价波动较常年一致,禽蛋养殖效益谨慎乐观。

The paper studies the relationship, adjustment ability, path, efficiency and intensity of price transmission in the swine industry chain in China, which consists of the prices of corn, compound feed for fattening pig, piglet, pig and pork. Monthly prices covering a period of 18 yr (1994-2011) are analyzed using a Market-Chain Cooperated Model (MCM). The empirical results show that there exists a stable long-term cointegration and short-term dynamic relationship in the price system. First, the adjustment speed of each price series is very slow and the transmission path is top-down and one-way significantly. Second, the price from upstream to downstream lags about 2 mon, while there is no lag in price transmission from midstream to downstream. Third, in terms of price transmission intensity, the price of pig impacted greatly on pork price, not only in the current period but also through the whole period. Besides, the price of corn has the largest lagged effects on pork price. According to the above empirical results, we suggest that government should strengthen monitoring and early warning of the swine industry chain, especially the upstream and midstream, attach great importance to the timely adjustment of feed prices and perfect the measures of price subsidy.

2011年,中国禽蛋市场零售价格高位运行,波动明显;禽蛋进出口形势持续好转,出口额大幅上升。国际方面,美国和加拿大鸡蛋批发价格高位运行,同比大幅上涨;2011年美国鸡蛋产量略增,1~10月美国鸡蛋出口明显增加。展望2012年,国内市场鸡蛋供给充足,价格将处于高位震荡回调阶段,禽蛋出口形势继续好转;美国鸡蛋价格将小幅下调,产量保持稳定,出口规模明显下降。

Enzymatic dephosphorylation of CDP-Star by ALP leads to CDP-Star decompose and continuously emit light. Optimal conditions for the determination of ALP by chemiluminescent method were investigated in this research. 125 mu mol/L CDP-Star reacted with ALP in the buffer solution of pH=9.5 and incubated for 10 min at 37 degrees C were selected as the optimal conditions for the determination of ALP. The amount of Delta RLU is proportional to ALP activity. Therefore, the method of chemiluminescent assay of ALP based on microplate was established. The results showed that the linear range for the determination of ALP was 0.05-10 U/L and 10-1000 U/L. This method was more rapid, sensitive and reproducible than that of traditional colorimetric method. Therefore, this method can be developed into a kit used in the high-throughput automatic biochemical analyzer.

Fluctuation and transmission in agro-product price is not only related to the development of agriculture,distribution of various stages' benefits in the whole agricultural chain,also affects the stability of the socio-economic order.During the period of economic and social transition in China,agricultural stability is related to the overall situation.Decision-makers in agricultural policy and macroeconomic regulation and control focus on how to ensure the smooth agricultural prices transmission and stable market price.In view of relatively weak on theoretical research in agricultural price transmission,the meaning,major influencing factors,suggestions for the relevant government departments to stabilize the market price were carried out in this paper,in order to promptly discover and predict the probability fluctuations in agricultural prices,make the early warning,maintain the market's healthy and orderly development.

The price transmission mechanism of the eggs supply chain in China was studied by designing a Market-chain Cooperated Model(MCM).Monthly price dates over the period from June 2000 to February 2012 were covered in this work which including legehenne compound feed,goods generation of chicks,Eggs wholesale price and retail price.The empirical results show the existence of a long-term cointegration relationship in the price system of eggs supply chain.The adjustment factor of each price in the system was less than 0.2,which meant that the price adjustment speed was very slow.Legehenne compound feed and eggs wholesale price both were the Granger causes of eggs retail price,but the eggs retail price was the only Granger cause of goods generation of chicks.Finally,we founded that the price of legehenne compound feed had the largest dynamic impact on eggs retail price and played an important role in the whole eggs supply chain.All of the findings implied that the government needed to increase the monitoring and warning for the prices in the supply chain,especially paid more attention to timely intervening and the control on the feed price.