Low-temperature processing of 'baroplastics' by pressure-induced flow

The manufacturing of plastics traditionally involves melt processing at temperatures typically greater than 200 degrees C-to enable extrusion or moulding under pressure into desired forms-followed by solidification. This process consumes energy and can cause substantial degradation of polymers and additives (such as flame retardants and ultraviolet stabilizers), limiting plastics performance and recyclability. It was recently reported that the application of pressure could induce melt-like behaviour in the block copolymer polystyrene-block-poly(n-butyl methacrylate) (PS-b-PBMA), and this behaviour has now been demonstrated in a range of other block copolymer systems. These polymers have been termed baroplastics. However, in each case, the order-to-disorder transition, which gives rise to the accompanying change in rheology from soft solid to melt, was observed at temperatures far exceeding the glass transition temperatures (T(g)) of both components. Here we show that baroplastic systems containing nanophase domains of one high-T(g) and one low-T(g) component can exhibit melt-like flow under pressure at ambient temperature through an apparent semi-solid partial mixing mechanism that substantially preserves the high-T(g) phase. These systems were shredded and remoulded ten times with no evident property degradation. Baroplastics with low-temperature formability promise lower energy consumption in manufacture and processing, reduced use of additives, faster production and improved recyclability, and also provide potential alternatives to current thermoplastic elastomers, rubber-modified plastics, and semi-crystalline polymers.     

Common and differential mechanisms of gonadotropin receptors

The gonadotropin receptors are G-protein-coupled receptors with unique structural and functional features, consisting of two halves. The N-terminal extracellular half (exodomain) binds the hormones, whereas the C-terminal membrane-associated half (endodomain) is responsible for receptor activation. In this review, the novel ternary interactions, contact points and mutual modulations among the exodomain, endodomain and hormone for hormone binding and signal generation are described based on the latest observations. This discussion is contrary to the view that the exodomain and endodomain are independent, at least functionally, and provides new insights into the receptor mechanisms for the gonadotropins and other G-protein-coupled receptors. Received 7 November 2001; received after revision 2 January 2002; accepted 3 January 2002     

The effects of microinjection of carbachol or hemicholinium into the amygdala on the levels of plasma and adrenal corticosterone in rats

Summary Microinjection of 0.4 g of carbachol into the amygdala caused a rise of corticosterone (CS) in the morning, when the prestimulating level of CS was lower. But the same procedure with a larger dose had no effect in the afternoon, when the prestimulating level of CS was higher.     

成组叶片振动特性的三维数值模拟及实验研究

采用三维8节点非协调单元，建立了成组叶片振动特性计算的三维有限元模型。该模型考虑到成组叶片位移约束的周期对称性，引入了斜边界条件和斜坐标系统来处理成组或整圈叶片的约束条件，从而可以准确地计算出三维复杂形状叶片组在动、静状态下的固有频率和振型。利用该方法对实例进行了计算，同时又在高速动平衡实验室进行了实验验证。计算结果和实验结果对比表明，用该方法计算的叶片振动特性精度较高，为计算复杂几何形状叶片组的振动特性提供了一种有效的手段。     

Relationship between the zonal displacement of the western Pacific subtropical high and the dominant modes of low-tropospheric circulation in summer

The zonal displacement of the western Pacific subtropical high remarkably influences the climate anomalies in China. In this paper, a new zonal index of the subtropical high is defined by modifying previous indices, and is used to investigate the relationship between the zonal displacement of the subtropical high and the dominant modes of 850-hPa circulations. It is found that the zonal displacement of the subtropical high is significantly correlated with the first two leading modes of circulations. In particular, the correlation coefficient between the index and the time series associated with the second mode is as high as 0.78 in 1958-2003 （46 years）. Since the second mode is not associated with significant anomalies of sea surface temperatures, the above results imply the difficulty in seasonal forecasting of the zonal displacement of the subtropical high. In addition, the interannual variability in the zonal displacement of the subtropical high has been considerably enhanced since 1978, due to the effects of both dominant modes, especially the second mode. This is likely to account for the frequent occurrence of anomalous climate in China during the recent two decades.     

Relationship between the zonal displacement of the western Pacific subtropical high and the dominant modes of low-tropospheric circulation in summer

The zonal displacement of the western Pacific subtropical high remarkably influences the climate anomalies in China. In this paper, a new zonal index of the subtropical high is defined by modifying previous indices, and is used to investigate the relationship between the zonal displacement of the subtropical high and the dominant modes of 850-hPa circulations. It is found that the zonal displacement of the subtropical high is significantly correlated with the first two leading modes of circulations. In particular, the correlation coefficient between the index and the time series associated with the second mode is as high as 0.78 in 1958-2003 (46 years). Since the second mode is not associated with significant anomalies of sea surface temperatures, the above results imply the difficulty in seasonal forecasting of the zonal displacement for the subtropical high. In addition, the interannual variability in the zonal displacement of the subtropical high is considerably enhanced since 1978, due to the effects of both dominant modes, especially the second mode. This is likely to account for the frequent occurrence of anomalous climate in China during the recent two decades.     

Interaction between PGE2 and EGF receptor through MAPKs in mouse embryonic stem cell proliferation

Identifying the small molecules that permit precise regulation of embryonic stem (ES) cell proliferation should further support our understanding of the underlying molecular mechanisms of self renewal. In the present study, we showed that PGE₂ increased [³H]-thymidine incorporation in a time and dose dependent manner. In addition, PGE₂ increased the expression of cell cycle regulatory proteins, the percentage of cells in S phase and the total number of cells. PGE₂ obviously increased E-type prostaglandin (EP) receptor 1 mRNA expression level compare to 2, 3, 4 subtypes. EP1 antagonist also blocked PGE₂-induced cell cycle regulatory protein expression and thymidine incorporation. PGE₂ caused phosphorylation of protine kinase C, Src, epidermal growth factor (EGF) receptor, phosphatidylinositol 3-kinase (PI3K)/Akt phosphorylation, and p44/42 mitogen-activated protein kinase (MAPK), which were blocked by each inhibitors. In conclusion, PGE₂-stimulated proliferation is mediated by MAPK via EP1 receptor-dependent PKC and EGF receptor-dependent PI3K/Akt signaling pathways in mouse ES cells. Received 30 January 2009; received after revision 03 March 2009; accepted 10 March 2009     

Bacterial peptide deformylase inhibitor PMT analogs inhibit cancer cell growth by interacting with human peptide deformylase

Potent inhibitors of human peptide deformylase （HsPDF） were screened using known PMT analog inhibi- tors of bacterial peptide deformylase. Forty-three species of PMT analogs that are non-peptidyl bacterial PDF inhibitors like actinonin were selected using virtual screening GOLD. Ten species out of 43 that could bind to HsPDF were selected and their antitumor activities were tested. Among them, four species （PMT-172, PMT-173, PMT-199, and PMT-201） showed excellent growth inhibition of cancer cell in the MTT assay. HsPDF-PMT binding was confirmed through a 1H-CPMG-T2 filter NMR experiment leading to a significant change in peak intensity for PMT-172 and PMT-199. These results suggest that PMT analogs could possibly interact with HsPDF and be a novel anticancer drug candidate.     

夏季西太副热带高压的东西偏移和对流层低层环流变化的主要模态的关系

夏季西太平洋副热带高压的东西偏移显著影响我国的气候异常．文中首先修订了原有的副高东西指数定义,并利用它分析了副高东西偏移和850 hPa环流主要变化模态之间的关系,发现副高东西偏移和环流变化的第一、第二模态均有显著的相关关系,特别是和第二模态在1958—2003年(46年)的相关系数高达0．78．由于第二模态没有对应明显的海温异常信号,上述结果意味着对夏季副高东西偏移的季度预测可能是一个比较困难的问题．此外,由于这两个模态的共同作用,特别是第二模态的作用,导致1978年以来副高东西偏移的年际变率明显变大,这可能是最近20多年我国气候异常频发的原因．