通用弹药集装方法研究

阐述了弹药包装的作用，对可能用于弹药包装上的常见集装方法进行了具体的技术分析，提出了实用性的通用弹药集装方法。     

Si/SiGe/Si HBT频率特性的解析模型与模拟

用解析的方法模拟了T＝300K和77K时，fT和fmax与集电极电流密度Jc的关系，在大电流下考虑了异质结势垒效应的影响。模拟结果和用数值方法以及实验所得到的结果一致。同时，还建立了与之相应的Si／SiGeeb异质结和SiGe／Sibc异质结电容模型。     

Folding dynamics and mechanism of beta-hairpin formation

Protein chains coil into alpha-helices and beta-sheet structures. Knowing the timescales and mechanism of formation of these basic structural elements is essential for understanding how proteins fold. For the past 40 years, alpha-helix formation has been extensively investigated in synthetic and natural peptides, including by nanosecond kinetic studies. In contrast, the mechanism of formation of beta structures has not been studied experimentally. The minimal beta-structure element is the beta-hairpin, which is also the basic component of antiparallel beta-sheets. Here we use a nanosecond laser temperature-jump apparatus to study the kinetics of folding a beta-hairpin consisting of 16 amino-acid residues. Folding of the hairpin occurs in 6 micros at room temperature, which is about 30 times slower than the rate of alpha-helix formation. We have developed a simple statistical mechanical model that provides a structural explanation for this result. Our analysis also shows that folding of a beta-hairpin captures much of the basic physics of protein folding, including stabilization by hydrogen bonding and hydrophobic interactions, two-state behaviour, and a funnel-like, partially rugged energy landscape.     

Recurrent type III membranoproliferative glomerulonephritis after kidney transplantation

The first well-documented case of recurrent type III membranoproliferative glomerulonephritis after kidney transplantation is reported in this article. A 48-year-old man was admitted to the hospital because of nephrotic syndrome and moderate renal failure. The renal biopsy showed double-contour images at light microscopy. Electron microscopy revealed electron-dense deposits in the mesangium and in both the subepithelial and subendothelial sides of the basement membrane. Subepithelial deposits were sometimes hump-like and produced an irregular disruption of the lamina densa. A diagnosis of type III membranoproliferative glomerulonephritis was suggested. The patient had a rapid decrease in renal function and received dialysis in 3 months. Three years later, he received a cadaveric kidney transplant, and subsequently recovered normal renal function. Proteinuria appeared after 13 months, and a biopsy of the graft demonstrated recurrence of the original disease. Seven years after transplantation, he returned to hemodialysis.     

Influence of ZnCl2 on the structure and mechanical properties of polyacrylonitrile fibers

The structure and mechanical properties of polyacrylonitrile fibers containing small amounts of Zn²⁺ were investigated. It is possible to interpret the influence of ZnCl₂ on the fibers by diffusion. Fibers spun from spinning dope containing ZnCl₂ may have a denser and finer structure because ZnCl₂ in the spinning dope retards the coagulation rate. The tensile strength and modulus of the fibers are much improved because of the retardation of coagulation. It is probable that the complexation between Zn²⁺ and CN groups does not contribute to the improvement of the mechanical properties because the amount of ZnCl₂ added in a spinning dope is extremely small.     

Trachoma: the forgotten cause of blindness

The effects of two fungicides (carbendazim and chlorothalonil) on the induction of DNA damage in human peripheral blood lymphocytes (human PBL) have been investigated using the single cell gel electrophoresis assay (SCGE assay or comet assay) immediately after a 1-h treatment and after a 24-h post-treatment incubation. The assessment of etoposide (an effective antitumour agent) effects on human PBL in terms of cell viability and dose-DNA damage relationships was made and etoposide selected as a positive control. The results indicate that etoposide induces significant (p < 0.01) dose-dependent DNA damages for concentrations at which the loss of cell viability is low. After a 24-h recuperation period, all observed DNA damages has disappeared. With SCGE assay performed after a 1-h treatment, similar positive results were observed with chlorothalonil alone or in association with carbendazim, without any loss of cell viability. However, a dramatic loss of cell viability was measured after 24 h and was associated with a large proportion of highly damaged cells. In contrast, carbendazim was not cytotoxic on human PBL and did not induced DNA damage using the SCGE assay either immediately after treatment or after a 24-h post-treatment incubation. These results point to the necessity of an adequate evaluation of immediate and long-term cytotoxicity of compounds that are to be assessed by the SCGE assay.     

Recombinant antigens for specific and sensitive serodiagnosis of Latin American tegumentary leishmaniasis

The diagnostic potential of recombinant leishmanial antigens for Latin American tegumentary leishmaniasis (LATL) was examined. Two Leishmania (Viannia) peruviana recombinant proteins, T26-U2 and T26-U4, were assessed by their reactivity to detect specific anti-leishmanial antibodies. Seventy-eight individual sera from persons with LATL, 39 from those with other diseases, and 10 negative control sera were tested by Western blotting and enzyme-linked immunosorbent assay. The sensitivity of the test using T26-U2 plus T26-U4 was similar to that obtained with whole parasite extract (92%). However, the specificity obtained using both recombinant antigens (87%) was higher than that of the whole parasite extract (65%). All tests using recombinant proteins (T26-U2, T26-U2 plus T26-U4 or T26-U4) had a higher positive predictive value (89%, 92% and 98%, respectively) than the value obtained using total parasites (81%). Eleven Colombian sera were also tested, and the results indicated that T26-U2 plus T26-U4 could be used successfully in Peru and in other Latin American countries.     

Radiofrequency ablation of type I atrial flutter: combination of electrophysiological and anatomical techniques

Atrial flutter type I (FLA) is one of the most common arrhythmias found in clinical practice. Reentry into the right atrium (AD) is the mechanism of this arrhythmia. The reentry mechanism has critical sites where radiofrequency (RF) can act blocking the circuit. Both, electrophysiological and anatomical approaches using RF to FLA have demonstrated a success rate above 80%. Our group combined both techniques treating 35 patients with FLA type I (22 men and 13 women), with mean age of 40.8 +/- 15 years old (range 9-70). In 21 patients (60%) this arrhythmia was associated with cardiopathy. All patients had failed to respond to different antiarrhythmic therapy. The success rate was 82.8% (29/35). When compared failure vs success we observed that patients who failed were older (51.8 vs 38.5 years old, p < 0.05), had structural cardiopathy (83.3% vs 55.1%, p = NS), had FLA type I with P waves with shorter cycle length (195 vs 254 ms, p = 0.052), had the arrhythmia chronically (129.6 vs 68.1 month, p = NS), had great left atrium diameter (41.2 vs 36.7 mm, p = 0.052) and frequently had been associated with atrial fibrillation (33.3% vs 3.4%, p = 0.02). There were no complications. Six (20.6%) patients reverted to FLA. We followed our patients during mean time 8.37 +/- 8.8 months (1-36). Our results support the notion that FLA type I can be treated with high percentage of success and low risk of complications when both RF techniques are combined. Our predictors of failure were: gender and associated atrial fibrillation (p < 0.05). We conclude that RF is the treatment of choice in every patient with FLA type I who had failed to antiarrhythmic therapy. We recommend RF as soon as FLA has been diagnosed because the probability of success is higher in such instances.     

Hanle Effect Measurements of Spin Lifetime in Zn<Subscript>0.4</Subscript>Cd<Subscript>0.6</Subscript>Se Epilayers Grown on InP

We use the Hanle effect to study spin relaxation in Zn_xCd_1–xSe epilayers grown on lattice-matched InP substrates. We study three samples with a fixed composition (x = 0.4) and with varying levels of n-doping, as well as an undoped sample with x = 0.5. Our measurements show that the spin relaxation time changes non-monotonically as a function of carrier density, with a maximum transverse spin lifetime of ~10.5 ns at low temperatures for a sample doped near the metal–insulator transition.