Design and implementation of an efficient SDRAM controller for HDTV decoder

A high performance SDRAM controller for HDTV decoder is designed.MB-based (macro block)address mapping,adaptive-precharge and command interleaving are adopted in this controller.MB-based address mapping reduces the precharge operations of the video processing unit in one access;adaptiveprecharge avoids unnecessary precharge operations;while command interleaving inserts the precharge and activate commands of the next access into the command sequence of the current access,thus reduces the no operation(NOP)cycles.Combination of these three schemes effectively improves the SDRAM performance.Compared with precharge-all scheme,adaptive-precharge and command interleaving reduce the SDRAM overhead cycles by 70% and increases SDRAM performance by up to 19.2%in the best case.This controller has been implemented in an AVS SoC and the frequency is 200MHz.     

东北黑土区污染现状及研究进展

分析了东北黑土区典型污染物的污染现状及其危害,介绍了在黑土区的污染物生物有效性、化学污染物的迁移转化、有毒污染物生态毒理效应及其分子机制等方面的研究进展,并提出中国黑土区土壤污染防治必须重视管理措施的发展和应用,对今后研究的方向进行了探讨.参22.     

Antimicrobial peptides: natural templates for synthetic membrane-active compounds

The innate immunity of multicellular organisms relies in large part on the action of antimicrobial peptides (AMPs) to resist microbial invasion. Crafted by evolution into an extremely diversified array of sequences and folds, AMPs do share a common amphiphilic 3-D arrangement. This feature is directly linked with a common mechanism of action that predominantly (although not exclusively) develops upon interaction of peptides with cell membranes of target cells. This minireview reports on current understanding of the modes of interaction of AMPs with biological and model membranes, especially focusing on recent insights into the folding and oligomerization requirements of peptides to bind and insert into lipid membranes and exert their antibiotic effects. Given the potential of AMPs to be developed into a new class of anti-infective agents, emphasis is placed on how the information on peptide-membrane interactions could direct the design and selection of improved biomimetic synthetic peptides with antibiotic properties.     

Kras regulatory elements and exon 4A determine mutation specificity in lung cancer

Kras is the most frequently mutated ras family member in lung carcinomas, whereas Hras mutations are common in tumors from stratified epithelia such as the skin. Using a Hras knock-in mouse model, we demonstrate that specificity for Kras mutations in lung and Hras mutations in skin tumors is determined by local regulatory elements in the target ras genes. Although the Kras 4A isoform is dispensable for mouse development, it is the most important isoform for lung carcinogenesis in vivo and for the inhibitory effect of wild-type (WT) Kras on the mutant allele. Kras 4A expression is detected in a subpopulation of normal lung epithelial cells, but at very low levels in lung tumors, suggesting that it may not be required for tumor progression. The two Kras isoforms undergo different post-translational modifications; therefore, these findings can have implications for the design of therapeutic strategies for inhibiting oncogenic Kras activity in human cancers.     

Physical Property Influence on Foaming Index of Refining Slag

The foaming indexes of a group of refining slag were measured. The refining slag with better foaming ability was chosen,its composition (mass frachon in %) is CaO, 53.25, SiO₂, 17.75, MgO, 9; Al₂O₃, 15 and CaF₂, 5. The relationship between slag foaming index and physical properties of the slag was obtained by dimensional analysis, and the expression indicates that viscosity of slag is the most important factor which influences foaming index. The influence sequence of slap composition on foaming index was also obtained as follows: CaF₂→MgO→Al₂O₃→ B (CaO/SiO₂).     

Fabrication and characterization of laminated Ti-(TiB+La2O3)/Ti composite

The incorporation of ceramic particulate reinforcements into titanium alloys can improve the specific strength and specific stiffness,while inevitably reduce the plasticity and ductility.In this study,in situ synthesized multilayer Ti-(TiB +La_2O_3)/Ti composite was designed by learning from the microstructure of nature biological materials with excellent mechanical properties.The Ti-(TiB + La_2O_3)/Ti composite with unique characteristic of laminated structure was prepared by combined powder metallurgy and hot rolling.The method has the synthesize advantages with in-situ reaction of Ti and LaB_6 at high temperature and controllability of reinforcements size and constituent phases in composites.The result shows that the pores in the as sintered laminated structure composite completely disappeared after hot rolling at 1050℃.The agglomerated reinforcement particles were well dispersed and distributed uniformly along the rolling direction.The thickness of pure Ti layer and(TiB+La_2O_3)/Ti composite layer decreased from 1 mm to about 200 μm.Meanwhile,the grains size was refined obviously after rolling deformation.The room temperature tensile test indicates that the elongation of the laminated Ti-(TiB + La_2O_3)/Ti composite improved from 13%to 17%in comparison with the uniform(TiB + La_2O_3)/Ti composite,while the tensile strength had little change.It provides theoretical and experimental basis for fabricating the novel high performance laminated Ti-(TiB + La_2O_3)/Ti composites.     

Microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels

The microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile test. The results show that Si can promote the transformation of austenite (γ) to ferrite (α), enlarge the (α+γ) region, and increase the aging stability of martensite by inhibiting carbide precipitation. Adding Cr leads to the formation of retained austenite and martensite/austenite (M/A) constituents, as well as the decomposition of martensite during the overaging stage. Both of the steels show higher initial strain-hardening rates and two-stage strain-hardening characteristics. The C-Mn-Si-Nb steel shows the higher strain-hardening rate than the C-Mn-Cr-Nb steel in the first stage; however, there is no significant difference in the second stage. Although the tensile strength and elongation of the two steels both exceed 1000 MPa and 15%, respectively, the comprehensive mechanical properties of the C-Mn-Si-Nb steel are superior.