Modeling the austenite-ferrite transformation in microalloyed steel P510L

Based on experimental results, the transformation kinetics and cooling characteristics of low-carbon steel were analyzed and modeled to quantitatively link the operational parameters of a process with the properties. From the continuous cooling transformation results, comparisons of the start temperature of austenite-ferrite transformation among three models were analyzed, and the optimal lnk and n, which are the parameters in the Avrami equation, were determined by applying two regression models at different cooling rates. The transformation kinetics during continuous cooling was determined. Furthermore, reasonable agreements between experimental results and predictions were obtained, which can demonstrate the rationality of the established models.     

Fabrication and characterization of patterned carbon nanotube flow sensor cell

Patterned flow sensor cell consisting of single-walled carbon nanotubes (SWCNTs) network and polydimethylsiloxane (PDMS) are fabricated, based on the process of vacuum filtration, photolithography, and plasma etching. The sensor cell is a composite thin film and packaged to form a flow sensor, and then tested in different flow rates with different liquids, such as deionized (DI) water and NaCl solution. The induced-voltage increases with increasing flowing velocity and liquid concentration. The relation between induced-voltage and sensor cell conductivity is tested in the same liquid at the same flow rate. The higher the conductivity is, the higher the induced-voltage is. Some of the SWCNTs are fixed in the PDMS matrix, simultaneously some of them protrude above the composite thin film, which are exposed to the liquid and contribute to the voltage generation. The fabrication method can make the flow sensor scaled down to dimensions on the order of micrometers, which makes it suitable in very small liquid volumes.     

Improved electrical resistance-pressure strain sensitivity of carbon nanotube network/polydimethylsiloxane composite using filtration and transfer process

The electrical resistance-pressure strain sensitivity of carbon nanotube network (NTN)/polymer composite is investigated. In this research, polydimethylsiloxane (PDMS) is used as the polymer matrix. The composite of NTN embedded in PDMS matrix has been fabricated by using filtration and transfer process. The thickness of NTN/PDMS composite can be controlled. Electrical resistance and pressure strain of the NTN/PDMS composite are measured simultaneously. Electrical resistance of NTN/PDMS composite has been obtained as a function of pressure strain. The NTN/PDMS composite exhibits linear change in electrical resistance as a result of pressure strain and has improved electrical resistance-pressure strain sensitivity. The NTN/PDMS composite has 90.6% resistance change at 6% pressure strain. The electrical resistance-pressure strain sensitivity of NTN/PDMS composite using filtration and transfer process is 2.13 times of the traditional NTN/PDMS composite. The characteristic in electrical resistance change implies that NTN/PDMS composite can be used as pressure strain sensors and applied to sensor systems.     

Analysis for retrieval and validation results of FY-3 Total Ozone Unit (TOU)

Retrieval experiment was made for global total column ozone using the first year measurements of Total Ozone Unit (TOU) on board the second generation polar orbiting meteorological satellite of China, FY-3/A. The retrieval results were analyzed and validated by comparison with AURA/OMI, Meteop/GOME-2 global ozone products and ground-based ozone measurement data. The qualititative comparisons over the globe especially over Antarctica and the Tibetan Plateau show that the spatial and temporal distribution characteristics are consistent with OMI and GOME-2 products. The quantitative comparisons with ground-based measurements and AURA/OMI ozone product were made over 74 stations, the TOU total ozone retrieval has a 3% rms relative error compared with AURA/OMI ozone product and 4.2% rms relative error with ground-based measurements. The maximum difference between satellite retrieval and ground-based measurements was found in the Antarctica ozone hole. The TOU global ozone product is operational and distributed to all users.     

新型雌激素受体ERα36在张氏肝细胞和人肝癌细胞中的表达比较分析

研究新型雌激素受体ERα36在人肝细胞和肝癌细胞系中的差异表达具有重要的意义.以张氏肝(Chang Liv-er)、Caveolin-1基因沉默细胞株CAV7、人肝癌细胞系SMMC-7721和HepG2为实验材料,通过免疫印迹杂交法观察了不同细胞内ERα36蛋白的表达情况,并与典型雌激素受体亚型ERα66蛋白的表达进行了比较.结果发现:(1)几种细胞中均有ERα36蛋白的表达;(2)与张氏肝细胞相比,Caveolin-1基因沉默时ERα36表达明显增加(P0.01);(3)ERα36在SMMC-7721中表达水平较低,而在HepG2细胞中表达水平较高,与ERα66和Caveolin-1的表达水平相关.提示新型雌激素受体ERα36可能参与Caveolin-1介导的雌激素信号转导,而在肝细胞的恶性增殖过程中发挥一定的作用.     

Genetic dissection of an amygdala microcircuit that gates conditioned fear

The role of different amygdala nuclei (neuroanatomical subdivisions) in processing Pavlovian conditioned fear has been studied extensively, but the function of the heterogeneous neuronal subtypes within these nuclei remains poorly understood. Here we use molecular genetic approaches to map the functional connectivity of a subpopulation of GABA-containing neurons, located in the lateral subdivision of the central amygdala (CEl), which express protein kinase C-δ (PKC-δ). Channelrhodopsin-2-assisted circuit mapping in amygdala slices and cell-specific viral tracing indicate that PKC-δ(+) neurons inhibit output neurons in the medial central amygdala (CEm), and also make reciprocal inhibitory synapses with PKC-δ(-) neurons in CEl. Electrical silencing of PKC-δ(+) neurons in vivo suggests that they correspond to physiologically identified units that are inhibited by the conditioned stimulus, called CEl(off) units. This correspondence, together with behavioural data, defines an inhibitory microcircuit in CEl that gates CEm output to control the level of conditioned freezing.     

Encoding of conditioned fear in central amygdala inhibitory circuits

The central amygdala (CEA), a nucleus predominantly composed of GABAergic inhibitory neurons, is essential for fear conditioning. How the acquisition and expression of conditioned fear are encoded within CEA inhibitory circuits is not understood. Using in vivo electrophysiological, optogenetic and pharmacological approaches in mice, we show that neuronal activity in the lateral subdivision of the central amygdala (CEl) is required for fear acquisition, whereas conditioned fear responses are driven by output neurons in the medial subdivision (CEm). Functional circuit analysis revealed that inhibitory CEA microcircuits are highly organized and that cell-type-specific plasticity of phasic and tonic activity in the CEl to CEm pathway may gate fear expression and regulate fear generalization. Our results define the functional architecture of CEA microcircuits and their role in the acquisition and regulation of conditioned fear behaviour.     

Head swivel on the ribosome facilitates translocation by means of intra-subunit tRNA hybrid sites

The elongation cycle of protein synthesis involves the delivery of aminoacyl-transfer RNAs to the aminoacyl-tRNA-binding site (A?site) of the ribosome, followed by peptide-bond formation and translocation of the tRNAs through the ribosome to reopen the A?site. The translocation reaction is catalysed by elongation factor G (EF-G) in a GTP-dependent manner. Despite the availability of structures of various EF-G-ribosome complexes, the precise mechanism by which tRNAs move through the ribosome still remains unclear. Here we use multiparticle cryoelectron microscopy analysis to resolve two previously unseen subpopulations within Thermus thermophilus EF-G-ribosome complexes at subnanometre resolution, one of them with a partly translocated tRNA. Comparison of these substates reveals that translocation of tRNA on the 30S subunit parallels the swivelling of the 30S head and is coupled to unratcheting of the 30S body. Because the tRNA maintains contact with the peptidyl-tRNA-binding site (P?site) on the 30S head and simultaneously establishes interaction with the exit site (E?site) on the 30S platform, a novel intra-subunit 'pe/E' hybrid state is formed. This state is stabilized by domain?IV of EF-G, which interacts with the swivelled 30S-head conformation. These findings provide direct structural and mechanistic insight into the 'missing link' in terms of tRNA intermediates involved in the universally conserved translocation process.     

Bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment

Biodiversity is rapidly declining, and this may negatively affect ecosystem processes, including economically important ecosystem services. Previous studies have shown that biodiversity has positive effects on organisms and processes across trophic levels. However, only a few studies have so far incorporated an explicit food-web perspective. In an eight-year biodiversity experiment, we studied an unprecedented range of above- and below-ground organisms and multitrophic interactions. A multitrophic data set originating from a single long-term experiment allows mechanistic insights that would not be gained from meta-analysis of different experiments. Here we show that plant diversity effects dampen with increasing trophic level and degree of omnivory. This was true both for abundance and species richness of organisms. Furthermore, we present comprehensive above-ground/below-ground biodiversity food webs. Both above ground and below ground, herbivores responded more strongly to changes in plant diversity than did carnivores or omnivores. Density and richness of carnivorous taxa was independent of vegetation structure. Below-ground responses to plant diversity were consistently weaker than above-ground responses. Responses to increasing plant diversity were generally positive, but were negative for biological invasion, pathogen infestation and hyperparasitism. Our results suggest that plant diversity has strong bottom-up effects on multitrophic interaction networks, with particularly strong effects on lower trophic levels. Effects on higher trophic levels are indirectly mediated through bottom-up trophic cascades.