MicroRNAs are abundant in the brains of vertebrates and some show a brain-specific or brain-enriched expression pattern. Because microRNAs regulate the expression of hundreds of target genes, it is not surprising that they have profoundly important functions in brain development and pathological processes. For example, miR-124 plays an important role in inducing and maintaining neuronal identity through targeting at least two anti-neural factors. MicroRNAs have also been implicated in brain disorders, including brain tumors and neurodegenerative diseases. This review aims to present an overview of the expression profiles and functions of microRNAs in the developing brains of vertebrates.
Yanting QiYu ZhaoZhuyin ChenXiaona ChenMarie C. LinXiangfu KongLihui Lai
Paleo-sedimentary environment of Chang 7 Member of Upper Triassic Yanchang Formation in Ordos Basin, including the paleoclimate, paleo-salinity and paleo-redox conditions were restored through geochemical elements analysis of 289 samples collected from the outcrop sections around and wells drilled in the basin and using a series of identification indexes of paleo-climate, paleo-salinity and paleo-redox conditions, such as CaO/MgO?Al2 O3, Sr/Cu, Rb/Sr, Rb/K2 O, Th/U, V/(V+Ni), the content of element B tested from the mudstone. Comprehensive analysis shows that in sedimentary period of the Chang 7, the paleo-climate was warm temperate to subtropical climate with temperature higher than 15 ?C, the water body was continental brackish water to freshwater, and the sediments were deposited under strong reduction conditions. Suitable temperature, extensively deep lake basin and strongly reductive paleo-sedimentary environment led to the blooming, enrichment and preservation of organic matter in the submember Chang 73. As a result, a set of high-quality source rock was formed, laying material foundation for large-scale accumulation of shale oil.
A hybrid microsystem with separately functioned temperature controlling substrate and sample operating fluidic microchannel was developed to demonstrate a reconfigurable microfluidics scheme.The temperature controlling substrate integrated a micro heater and a temperature sensor by using traditional silicon-based micromechanical system(MEMS)technique,which guaranteed high performance and robust reliability for repeatable usage.The sample operating fluidic microchannel was prepared by poly-(dimethylsiloxane) (PDMS)based soft lithography technique,which made it cheap enough for disposable applications.The PDMS microchannel chip was attached to the temperature controlling substrate for reconfigurable thermal applications.A thin PDMS film was used to seal the microchannel and bridge the functionalized substrate and the sample inside the channel,which facilitated heat transferring and prevented sample contaminating the temperature controlling substrate.Demonstrated by a one dimensional thermal resistance model,the thin PDMS film was important for the present reconfiguration applications.Thermal performance of this hybrid microsystem was examined,and the experimental results demonstrated that the chip system could work stably over hours with temperature variation less than 0.1oC.Multiple PDMS microchannel chips were tested on one heating substrate sequentially with a maximum intra-chip temperature difference of 1.0oC.DNA extracted from serum of a chronic hepatitis B virus(HBV)patient was amplified by this hybrid microsystem and the gel electrophoresis result indicated that the present reconfigurable microfluidic scheme worked successfully.
LEI YinHua 1 ,XIE Fei 1 ,WANG Wei 1,2 ,WANG HaiBin 3 &LI ZhiHong 1,2 1 Institute of Microelectronics,Peking University,Beijing 100871,China
The 2008 Wenchuan earthquake in Sichuan of China was the result of quake-triggering along an active several hundred-kilometer-long fault. The subsequent landslides and debris flow geohazards are dominating factors in planning post-disaster recovery and rebuilding. This paper presents recommendations for coping with large-scale geohazards and disasters. It is essential to establish a national emergency management system for huge scale catastrophe and earthquake precursor identification. Town construction must be kept away from active faults, especially to improve town safety in areas with high risk of seismic and geological hazards, and it is important to improve geohazard investigation and remediation for mountain areas that have become loosened by earthquake activity. Geological factors must be better understood to reduce direct and secondary risks and effects of earthquakes. Site selections for public relocation require clear and informed analysis of geological and social risk reduction, so that relocation, infrastructure reconstruction, and commemorative relic-sites can be protected.
Reactive powder concrete(RPC) is vulnerable to explosive spalling when exposed to high temperature.The characteristics of micro pore structure and vapor pressure of RPC are closely related to the thermal spalling.Applying mercury intrusion porosimetry(MIP) and scanning electron microscopy(SEM) techniques,the authors probed the characteristics of micro pore structures of plain RPC200 when heated from 20-350℃.The pore characteristics such as specific pore volume,threshold pore size and most probable pore size varying with temperatures were investigated.A vapor pressure kit was developed to measure the vapor pressure and its variation inside RPC200 at various temperatures.A thin-wall spherical pore model was proposed to analyze the thermo-mechanical mechanism of spalling,by which the stresses varying with the vapor pressure q(T) and the characteristic size of wall(K) at any point of interest were determined.It is shown that the pore characteristics including specific pore volume,average pore size,threshold pore size and most probable pore size rise significantly with the increasing temperature.200℃ appears to be the threshold temperature above which the threshold pore size and the most probable pore size climb up dramatically.The increase in the specific pore volume results from the growth both in quantity and in volume of the transition pores and the capillary pores.The appearance of the explosive spalling in RPC200 is mainly attributed to being unable to form pathways in favor of releasing water steam in RPC and to the rapid accumulation of high vapor pressures as well.The thin-wall sphere domain where the vapor pressure governs the spalling is bounded through the pore model.
JU YangLIU HongBinTIAN KaiPeiLIU JinHuiWANG LiGE ZhiShun
As a 3-D display technology,stereoscopic imaging with lenticular lens sheet can only offer viewers the horizontal parallax.To reconstruct the 3-D image with parallax in both horizontal and vertical directions,the full parallax technique with micro-lens array was proposed.But due to the fabrication constraints and cost concerns of the micro-lens array,application of the full parallax technique is restricted in practice.In this paper we revisited the lenticular sheet method and cross-lenticular lens array formed by two lenticular sheets overlapped orthogonally.By analyzing the optical properties of this cross-lenticular lens array,we found that it has reasonable imaging qualities as a conventional micro-lens array.Besides,due to the poor optical property of the outskirt area of the cross-lenticular lens,the cross-lenticular lens array has better crosstalk suppression capability than the conventional one.Based on the analysis,in this paper,we used the proposed lens array to reconstruct a 3-D image and verified its practicability.The cross-lenticular lens array was found feasible to take the full parallax technique into commercial applications,with comparable advantages in terms of low-cost and easy fabrication over a large area.
Operant conditioning is one of the fundamental mechanisms of animal learning,which suggests that the behavior of all animals,from protists to humans,is guided by its consequences.We present a new stochastic learning automaton called a Skinner automaton that is a psychological model for formalizing the theory of operant conditioning.We identify animal operant learning with a thermodynamic process,and derive a so-called Skinner algorithm from Monte Carlo method as well as Metropolis algorithm and simulated annealing.Under certain conditions,we prove that the Skinner automaton is expedient,ε-optimal,optimal,and that the operant probabilities converge to the set of stable roots with probability of 1.The Skinner automaton enables machines to autonomously learn in an animal-like way.
Lysophosphatidic acid(LPA)is an important bioac-tive phospholipid involved in cell signaling through G-protein-coupled receptors pathways.It is also involved in balancing the lipid composition inside the cell,and modulates the function of lipid rafts as an intermediate in phospholipid metabolism.Because of its involvement in these important processes,LPA degradation needs to be regulated as precisely as its production.Lysophospha-tidic acid phosphatase type 6(ACP6)is an LPA-specifi c acid phosphatase that hydrolyzes LPA to monoacylglyc-erol(MAG)and phosphate.Here,we report three crystal structures of human ACP6 in complex with malonate,L-(+)-tartrate and tris,respectively.Our analyses revealed that ACP6 possesses a highly conserved Rossmann-fold-like body domain as well as a less conserved cap domain.The vast hydrophobic substrate-binding pocket,which is located between those two domains,is suitable for ac-commodating LPA,and its shape is different from that of other histidine acid phosphatases,a fact that is consistent with the observed difference in substrate preferences.Our analysis of the binding of three molecules in the active site reveals the involvement of six conserved and crucial residues in binding of the LPA phosphate group and its catalysis.The structure also indicates a water-supplying channel for substrate hydrolysis.Our structural data are consistent with the fact that the enzyme is active as a monomer.In combination with additional mutagenesis and enzyme activity studies,our structural data provide important insights into substrate recognition and the mechanism for catalytic activity of ACP6.
Jun LiYu DongXingru LüLu WangWei PengXuejun C.ZhangZihe Rao
