Synthesis and characterization of acidic properties of Al-SBA-15 materials with varying Si/Al ratios

Al-SBA-15 of varying Si/Al ratios in the range 11.4–78.4 was synthesized using tri-block copolymer P123. The calcined materials were examined by XRD, pore size distribution, surface area, ²⁷Al NMR spectroscopy. The acidity and acid strength distribution were studied using microcalorimetric adsorption of NH₃. The acidic properties were also examined by cumene cracking reaction as a function of Si/Al ratios. Systematic variation of acidity and activity was observed as a function of Si/Al ratio. The initial heats of NH₃ adsorption correlated well with activity indicate that acid sites with ΔH > 100 kJ/mole is responsible for cumene cracking activity. Linear correlations were obtained with total acidity and cumene cracking activities. The tetrahedral aluminum was found to be responsible for the observed acidities and catalytic activities.     

利用串行RapidIO连接功能增强DSP协处理能力

SRIO IP解决方案提供真实双向数据流,大大增强连接功能。目前,对高速通信与超快计算的需求正与日俱增。有线和无线通信标准的应用随处可见,数据处理架构每天都在扩展。较为普遍的有线通信方式是以太网(LAN、WAN和MAN网络)。手机通信是最为常见的无线通信方式,由应用了DSP的     

A new chip-thickness model for performance assessment of silicon carbide grinding

The chip-thickness models, used to assess the performance of grinding processes, play a major role in predicting the surface quality. In the present paper, an attempt has been made to develop a new chip-thickness model for the performance assessment of silicon carbide grinding by incorporating the modulus of elasticities of the grinding wheel and the workpiece in the existing basic chip-thickness model to account for elastic deformation. The new model has been validated by conducting experiments, taking the surface roughness as a parameter of evaluation .     

The complex pathology of trinucleotide repeats

The expansion of trinucleotide repeat sequences has now been shown to be the underlying cause of at least ten human disorders. Unifying features among these diseases include the unstable behavior of the triplet repeat during germline transmission when the length of the repeat exceeds a critical value. However, the trinucleotide repeat disorders can be divided into two distinct groups. Type I disorders involve the expansion of CAG repeats, which encode an expanded polyglutamine, inserted into the open-reading frame of a gene that is usually quite broadly expressed. Recently, mouse models for type I disorders have been developed and the basis of pathology is under study, both in these models and through biochemical and cell biological approaches. The type II disorders involve repeat expansions in noncoding regions of genes. The mechanisms by which these repeat expansions lead to pathology may be quite diverse.     

Chrestenson函数序列的生成方法及其数学分析

本文提出了适于三种序号的Ｃｈｒｅｓｔｅｎｓｏｎ函数序列的复制方法，对其复制过程进行了数学分析，并指出当Ｃｈｒｅｓｔｅｎｓｏｎ函数退化为Ｗａｌｓｈ函数时，此方法即为复制理论中的平移复制方法。     

Antimicrobial effect of combinations of EDTA-Tris and amikacin or neomycin on the microorganisms associated with otitis externa in dogs

Combinations of EDTA-Tris and two aminoglycoside antibiotics (amikacin and neomycin) were tested for synergistic activities against the microorganisms associated with otitis externa in dogs and for the solutions' stability over time. Synergistic activity was observed when EDTA-Tris plus amikacin and EDTA-Tris plus neomycin were tested against Staphylococcus intermedius, Proteus mirabilis, Pseudomonas aeruginosa, and Escherichia coli, but not against Candida albicans. Stability studies over a 3-month period indicated that the test solutions were stable at room temperature and that their antimicrobial activity was maintained.     

Comparative efficacy of three indexes of left ventricular performance derived from pressure-volume loops in heart failure induced by tachypacing

OBJECTIVES: The purpose of this study was to serially evaluate the response and variability of the end-systolic pressure-volume relation, the left ventricular end-diastolic volume-peak positive first derivative of left ventricular pressure (dP/dt) relation and the left ventricular end-diastolic volume-stroke work relation in the development of progressive left ventricular dysfunction. BACKGROUND: Evaluation of systolic performance of the failing left ventricle may be enhanced by using relatively load-insensitive measures of left ventricular performance. The end-systolic pressure-volume, left ventricular end-diastolic volume-peak positive dP/dt and left ventricular end-diastolic volume-stroke work relations adequately define left ventricular performance under multiple loading conditions, but efficacy has not been fully assessed in the failing heart, particularly in the intact circulation. METHODS: Fourteen dogs underwent instrumentation and rapid pacing to heart failure. Variably loaded pressure-volume beats were produced by inferior vena cava occlusion. The dogs were evaluated at baseline and at three progressively more severe levels of left ventricular dysfunction. RESULTS: There was a progressive increase in left ventricular volumes at end-diastole ([mean value +/- SE] 60 +/- 28 to 73 +/- 29 ml, p < 0.001) and end-systole (39 +/- 19 to 61 +/- 27 ml, p < 0.001) during the 3 weeks of rapid pacing and a progressive decline in peak positive dP/dt (1,631 +/- 410 to 993 +/- 222 mm Hg/s, p < 0.001) and ejection fraction (37 +/- 8% to 16 +/- 11%, p < 0.001). There was a corresponding decline in the slope of each of the three relations: for end-systolic pressure-volume, 6.3 +/- 2.2 to 2.8 +/- 0.7 (p < 0.05); for left ventricular end-diastolic volume-stroke work, 61.9 +/- 9.1 to 26.5 +/- 2.4 (p < 0.05); and for left ventricular end-diastolic volume-peak positive dP/dt, 47.1 +/- 13.6 to 20.31 +/- 6.8 (p < 0.05). There was also a corresponding increase in position volumes: for end-systolic pressure-volume, 33.6 +/- 3.9 to 61.2 +/- 6.6 ml (p < 0.05); for left ventricular end-diastolic volume-stroke work, 46.2 +/- 3.6 to 89.3 +/- 7.6 ml (p < 0.05); and for left ventricular end-diastolic volume-peak positive dP/dt, 29.1 +/- 19.1 to 68.6 +/- 25.9 ml (p < 0.05). The relative degree of change in each of the three relations was similar as more severe heart failure developed. The coefficients of variation for position were significantly less than the variation for slopes. The response of volume intercepts was heterogeneous. For left ventricular end-diastolic volume-stroke work, the intercept increased as ventricular performance decreased. The intercept of the end-systolic pressure-volume relation was significantly more variable than the left ventricular end-diastolic volume-stroke work relation and did not change with progressive heart failure. The intercept for left ventricular end-diastolic volume-peak positive dP/dt was highly variable and showed no consistent changes as left ventricular function declined. CONCLUSIONS: All three relations consistently describe changes in left ventricular performance brought about by tachypacing. Evolution of left ventricular dysfunction causes a decline in slope and a rightward shift of these relations. The position of the relation is the most sensitive and least variable indicator of left ventricular systolic performance.