高性能不饱和聚酯树脂的研究

本文以顺酐、苯酐和 1,2—丙二醇为主要原料 ,采用具有气干性基团的双环戊二烯作为改性剂 ,通过反应型改性将其接入不饱和聚酯链 ,以获得表干性。与同样条件下通用型树脂浇铸体的性能进行比较 ,实验结果表明 :双环戊二烯的引入 ,在保留树脂制品原有力学性能的基础上 ,赋予树脂优异的表干性 ,并提高了树脂的耐酸、碱、潮湿的能力。

Epigenetics and neural stem cell commitment

Neural stem cell is presently the research hotspot in neuroscience. Recent progress indicates that epigenetic modulation is closely related to the self-renewal and differentiation of neural stem cell. Epigenetics refer to the study of mitotical/meiotical heritage changes in gene function that cannot be explained by changes in the DNA sequence. Major epigenetic mechanisms include DNA methylation, histone modification, chromatin remodeling, genomic imprinting, and non-coding RNA. In this review, we focus on the new insights into the epigenetic mechanism for neural stem cells fate.

Expression of Neuropilin-1 Gene in Bone Marrow Stromal Cells from Patients with Myeloid Leukemia and Normal Individuals

Objective: To investigate the expression of neuropilin-1 (NP-1) gene in bone marrow stromal cells (BMSCs) from myeloid leukemia (AML and CML) and normal individuals. Methods: Mononuclear cells were isolated from bone marrow (BM) of CML (14 cases), AML (12 cases) and normal individuals (20 cases). Adherent cells (i.e. BMSCs) were collected after long-term culture in vitro. The expression of NP-1 gene in three groups was detected respectively by reverse-transcription polymerase chain reaction (RT-PCR). Results: The long-term culture of BMSCs was successfully established. The expression level of NP-1 gene was significantly lower in BMSCs from AML (47.1%) and CML (50%) than in normal individuals (85%). Conclusion: NP-1 gene is expressed in BMSCs from some AML or CML patients and most normal individuals. The low-expression of NP-1 gene in BMSCs from AML or CML patients might be related with abnormality of regulation in hematopoiesis.

Approximate Analytic Solution of Solitary Wave for a Class of Nonlinear Disturbed Long-Wave System

In this paper, the approximate expressions of the solitary wave solutions for a class of nonlinear disturbed long-wave system are constructed using the homotopie mapping method.

The P—representation on Nonlinear Coherent State Basis

Using the technique of integration within an ordered product of nonlinear Bose operators and by composing the nonlinear coherent state's over-completeness relation, we construct the corresponding P-representation theory. The generalized P-representation for some nonlinear Bose operators can be established.

Expression of bcl-2 protein in chronic hepatitis C:Effect of interferon alpha 2b with ribavirin therapy

AIM: Mechanisms responsible for persistence of HCV infection and liver damage in chronic hepatitis C are not clear. Apoptosis is an important form of host immune response against viral infections. Anti-apoptotic protein bcl-2 expression on liver tissue as well as the influence of interferon alpha 2b (IFNa2b) and ribavirin (RBV) were analyzed in patients with chronic hepatitis C. METHODS: In 30 patients with chronic hepatitis C (responders - R and non-responders - NR) treated with IFNα2b+RBV, protein bcl-2 was determined in hepatocytes and in liver associated lymphocytes before and after the treatment. RESULTS: The treatment diminished bcl-2 protein accumulation in liver cells in_patients with hepatitis C (P<0.05). Before and after the therapy, we detected bcl-2 protein in R in 87±15% and 83±20% of hepatocytes and in 28±18% and 26±10% of liver-associated lymphocytes, respectively. In NR, the values before treatment decreased from 94±32% to 88±21% of hepatocytes and 39±29% to 28±12% of lymphocytes with bcl-2 expression. There was no statistical correlation between bcl-2 expression on liver tissue with inflammatory activity, fibrosis and biochemical parameters before and after the treatment. CONCLUSION: IFNα2b+RBV treatment, by bcl-2 protein expression decrease, enables apoptosis of hepatocytes and associated liver lymphocytes, which in turn eliminate hepatitis C viruses.

Decreasing Pin1 suppressed the properties of migratory and invasive in colorectal carcinoma SW620 cells

Objective:The aim of our study was to investigate the effect of Pin1 on the expression of MMP-2 and MMP-9 in human colorectal carcinoma SW620 cells. Methods: We constructed a eukaryotic expression vector of RNA interfering (shRNA) for Pin1 gene (pGenesil-1-Pin1), and then observed its expression in SW620 cells by Western blotting. The cells motility were tested by wound healing assay and Boyden chamber assay. The protein levels and activity of MMP-2 and MMP-9 were tested by Western blotting and Gelatin zymography in SW620 cells after transfected with pGenesil-1-PIN1. Results: pGenesil-1-PIN1 was successfully constructed, which was confirmed by sequencing. Silencing the Pin1 by RNAi significantly decreased the cells motility from 96.4±3.9 per field (×10 objective) to 52.7±4.4 per field (P<0.05, Student's t-test) for SW620 cells transfected with pGenesil-1-PIN1 (SW620/p-shRNA) in Boyden chamber assay, and reduced the MMP-2 and MMP-9 expressions and activity in SW620 cells. The protein relative levels of MMP-2 were 0.32±0.04 for SW620/p-shRNA, and 0.76±0.03 for SW620/p-Con; MMP-9 were 0.41±0.09 for SW620/p-shRNA, and 0.94±0.07 for SW620/p-Con (p<0.05). Conclusion: Inhibited Pin1 expression may contribute to the suppression of the invasive and metastatic capacity of colon cancer cells in vitro.

Digital speckle pattern interferometric measurement of diffusion coefficients in hydrogels

The technique of real-time digital speckle pattern interferometry is p roposed to study diffusion of surfactants in hydrogel. The diffusion coefficient is simply and directly determined from the interferograms. An example of diffus ion coefficient measurement of surfactant in agarose gel demonstrates the useful ness of the method. The results obtained are compared with the theoretical simul ating values.

Investigation of MQL-Employed Hard-Milling Process of S60C Steel Using Coated-Cermented Carbide Tools

The application of cutting fluids in machining brings out many benefits, but their use is accompanied by health and enviroment hazards. MQL （Minimum Quantity Lubricant） has become a preciously alternative solution for lubrication against dry machinning and flood cooling lubricant, and this is a step toward green machining. This paper presents a comprehensively experiemental study on investigation of MQL performance in hard milling of S60C steel for multiple responses, including surface quality, cutting forces and tool wear. Compared to dry milling, even-enhanced surfaces finish quality, 20% less cutting force （Ft） and almost 112% prolonged tool lifetime are achieved by using MQL with 5% Emulsion in hard milling. In addition, this study compared the performances of MQL milling by using 5% Emulsion to the peanut oil completely harmless to the enviroment. This encouraging result, therefore, reveals that the MQL-employed hard milling can enable significant improvement in productivity, product quality, and overall machining economy even after covering the additional cost of designing and implementing MQL system. Moreover, this study also shows the limitation of peanut oils employed in MQL and proposes the further research in novel additives to enhance the performance of cooling lubricant for vegetable oils.

Understanding the Safety, Health and Environmental （SHE） Challenges of Xenobiotics and Their Remedial Approaches

With the use of over 100,000 industrially produced chemicals, there have been several concerns on human health and environment. Most of these chemicals are exposed into the natural environment during the life cycles of their production, transportation, storage, consumption, and as by-products and wastes. The rising rates of cancer, obesity, and infertility suggests that there are compounds recently introduced to the environment that have altered the chemistry of the human body, and it is only with the monitoring of xenobiotics such as Bisphenol A （BPA）, nonyphenols, estrogen （natural and synthetic） and other endocrine-disrupting compounds （EDCs） that patterns and links could be drawn. This paper investigates the safety, environmental and health （SHE） impacts caused by BPA, nonyphenols and estrogens. Derived from petroleum, bisphenol A is used in manufacturing plastic consumer products, including certain water bottles, in dental sealants for children＇s teeth, and in resins used to line tin cans. Nonyphenol is one of the by-products of alkylphenolpolyethoxilates which is widely used as nonionic surfactants. Synthetic estrogen used for birth control pills as well as natural estrogen excreted by women through urine enters the domestic wastewater streams. These compounds are considered to be EDCs and have severe SHE concerns. In this paper, the challenges of entry of these compounds （xenobiotics） into nature, health and environmental issues and their remediation have been reviewed in detail.

Three-dimensional porous graphene sponges assembled with the combination of surfactant and freeze-drying

With the combination of surfactant and freeze-drying, we have developed two kinds of graphene spongy structures. On the one hand, using foams of soap bubbles as templates, three-dimensional porous graphene sponges with rich hierarchical pores have been synthesized. Pores of the material contain three levels of length scales, including millimeter, micrometer and nanometer. The structure can be tuned by changing the freezing media, adjusting the stirring rate or adding functional additives. On the other hand, by direct freeze-drying of a graphene oxide/surfactant suspension, a porous framework with directionally aligned pores is prepared. The surfactant gives a better dispersion of graphene oxide sheets, resulting in a high specific surface area. Both of the obtained materials exhibit excellent absorption capacity and good compression performance, providing a broad range of possible applications, such as absorbents, storage media, and carriers.

Tissue-engineered composite scaffold of poly(lactide-co-glycolide) and hydroxyapatite nanoparticles seeded with autologous mesenchymal stem cells for bone regeneration

Objective： A new therapeutic strategy using nanocomposite scaffolds of grafted hydroxyapaUte （g-HA）/ poly（lactide-co-glycolide） （PLGA） carried with autologous mesenchymal stem cells （MSCs） and bone morphogenetic protein-2 （BMP-2） was assessed for the therapy of critical bone defects. At the same time, tissue response and in vivo mineralization of tissue-engineered implants were investigated. Methods： A composite scaffold of PLGA and g-HA was fabricated by the solvent casting and particulate-leaching method. The tissue-engineered implants were prepared by seeding the scaffolds with autologous bone marrow MSCs in vitro. Then, mineralization and osteogenesis were ob- served by intramuscular implantation, as well as the repair of the critical radius defects in rabbits. Results： After eight weeks post-surgery, scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDX） revealed that g-HNPLGA had a better interface of tissue response and higher mineralization than PLGA. Apatite particles were formed and varied both in macropores and micropores of g-HNPLGA. Computer radiographs and histological analysis revealed that there were more and more quickly formed new bone formations and better fusion in the bone defect areas of g-HNPLGA at 2-8 weeks post-surgery. Typical bone synostosis between the implant and bone tissue was found in g-HNPLGA, while only fibrous tissues formed in PLGA. Conclusions： The incorporation of g-HA mainly im- proved mineralization and bone formation compared with PLGA. The application of MSCs can enhance bone for- mation and mineralization in PLGA scaffolds compared with cell-free scaffolds. Furthermore, it can accelerate the absorption of scaffolds compared with composite scaffolds.

Relationship of atmospheric boundary layer depth with thermodynamic processes at the land surface in arid regions of China

The atmospheric boundary layer （ABL） is an important physical characteristic of the Earth＇s atmosphere. Compared with the typical ABL, the ABL in arid regions has distinct features and is formed by particular mechanisms. In this paper, the depth of the diurnal and nocturnal ABLs and their related thermodynamic features of land surface processes, including net radiation, the ground-air temperature difference and sensible heat flux, under typical summer and winter conditions are discussed on the basis of comprehensive observations of the ABL and thermodynamic processes at the land surface carried out in the extreme arid zone of Dunhuang. The relationships of the ABL depth in the development and maintenance stages with these thermodynamic features are also investigated. The results show that the depth of the ABL is closely correlated with the thermodynamic features in both development and maintenance stages and more energy is consumed in the development stage. Further analysis indicates that wind velocity also affects ABL development, especially the development of a stable boundary layer in winter. Taken together, the analysis results indicate that extremely strong thermodynamic processes at the land surface are the main driving factor for the formation of a deep ABL in an arid region.

Regional applicability of seven meteorological drought indices in China

The definition of a drought index is the foundation of drought research.However,because of the complexity of drought,there is no a unified drought index appropriate for different drought types and objects at the same time.Therefore,it is crucial to determine the regional applicability of various drought indices.Using terrestrial water storage obtained from the Gravity Recovery And Climate Experiment,and the observed soil moisture and streamflow in China,we evaluated the regional applicability of seven meteorological drought indices:the Palmer Drought Severity Index(PDSI),modified PDSI(PDSI_CN) based on observations in China,self-calibrating PDSI(scPDSI),Surface Wetness Index(SWI),Standardized Precipitation Index(SPI),Standardized Precipitation Evapotranspiration Index(SPEI),and soil moisture simulations conducted using the community land model driven by observed atmospheric forcing(CLM3.5/ObsFC).The results showed that the scPDSI is most appropriate for China.However,it should be noted that the scPDSI reduces the value range slightly compared with the PDSI and PDSI_CN;thus,the classification of dry and wet conditions should be adjusted accordingly.Some problems might exist when using the PDSI and PDSI_CN in humid and arid areas because of the unsuitability of empiricalparameters.The SPI and SPEI are more appropriate for humid areas than arid and semiarid areas.This is because contributions of temperature variation to drought are neglected in the SPI,but overestimated in the SPEI,when potential evapotranspiration is estimated by the Thornthwaite method in these areas.Consequently,the SPI and SPEI tend to induce wetter and drier results,respectively.The CLM3.5/ObsFC is suitable for China before 2000,but not for arid and semiarid areas after 2000.Consistent with other drought indices,the SWI shows similar interannual and decadal change characteristics in detecting annual dry/wet variations.Although the long-term trends of drought areas in China detected by these seven drought indices during 1961-2013 are consistent,obvious differences exist among the values of drought areas,which might be attributable to the definitions of the drought indices in addition to climatic change.

H_2/H_∞ CONTROL PROBLEMS OF BACKWARD STOCHASTIC SYSTEMS

This paper is concerned with the mixed H_2/H_∞ control problem for a new class of stochastic systems with exogenous disturbance signal.The most distinguishing feature,compared with the existing literatures,is that the systems are described by linear backward stochastic differential equations(BSDEs).The solution to this problem is obtained completely and explicitly by using an approach which is based primarily on the completion-of-squares technique.Two equivalent expressions for the H_2/H_∞ control are presented.Contrary to forward deterministic and stochastic cases,the solution to the backward stochastic H_2/H_∞ control is no longer feedback of the current state;rather,it is feedback of the entire history of the state.