Nested polymerase chain reaction (PCR) and multiple cloned antibody capture PCR for the examination of serum hepatitis B virus DNA in negative hepatitis B surface antigen patients suffering from liver diseases

In order to find out rapidly the causes of the liver diseases suffered by patients with negative hepatitis B surface antigen (HBsAg), nested polymerase chain reaction (PCR) and multiple cloned antibody capture PCR techniques were established to examine serum hepatitis B virus (HBV) DNA. By using both techniques along with the examination of hepatitis C virus (HCV) infection, the causes of chronic liver diseases with negative HBsAg were studied. It is found that nested-PCR can increase the sensitivity of single PCR more than 1,000 fold and multiple cloned antibody capture-PCR can detect concentration of HBV DNA as low as 0.1-0.01 pg/L. HBV DNA positive patients were found in 45.5%, 30.8%, 13.3% and 100% respectively of the patients suffering from liver cirhosis with negative HBsAg (group A, 22 cases), chronic hepatitis with negative HBsAg (group B, 13 cases), normal subjects with negative HBsAg and positive hepatitis B core antibody (HBcAb, group C, 30 cases) and liver cirhosis with positive HBsAg and negative HBeAg (group D, 12 cases). HBV DNA can be also found in the serum of HBsAb positive patients and subjects supposed to be healthy, 81.8% and 53.8% of the patients were infected with HBV and/or HCV in group A and group B respectively. All these results suggest that nested-PCR and multiple cloned antibody capture-PCR are rapid and highly sensitive methods for detection of serum HBV DNA. HBV infection is an important cause of chronic liver diseases in patients with negative HBsAg. The causes of most of the HBsAg-negative chronic liver diseases are related with infection of viruses. The clinical significance of serum HBsAb in naturally infected patients should be reconsidered.     

Microwave surface impedances of BCS superconducting thin films

The microwave propagation-dominated problem in the multilayer structure made of a BCS superconducting film and a dielectric substrate is investigated theoretically by using the modified two-fluid model and transmission line theory. The effective microwave surface impedances are studied as functions of temperature, frequency, and film thickness, as well as substrate thickness. Special attention is paid to the substrate resonance phenomenon in the resonant structure. The influence of BCS coherence effects on surface impedance and resonant behavior is clearly demonstrated. The resonant effect in the stack structure is well interpreted with the help of the transverse resonance technique in the microwave theory     

等温脉冲自由射流压力场动态特性的实验研究

针对冶金工业过程脉冲燃烧及脉冲流技术所进行研究的基础部分,借助于计算机辅助信号分析手段,运用湍流统计理论,对等温脉冲自由射流压力场动态特性进行了系统的实验研究。实验的Re范围为19486～93936,st范围为0～0.057,所对应的射流脉冲频率为0～25Hz。研究结果表明;脉冲射流极大地提高了射流区压力波动水平,任何受气体的动量、热量和质量传递制约的工业过程均可望通过适当地采用脉冲流技术加以强化.     

Responses of somatostatin, beta-endorphin and dynorphin A to a glucose load in two groups of women with polycystic ovarian syndrome

Since the late 1980s, the eight-component model of the comprehensive school health program (CSHP), has been adopted widely in the United States and internationally. While it is acknowledged that the eight program elements should be delivered in a coordinated, interactive manner, numerous issues regarding how this integration best can be achieved, including who at the school level should have this responsibility and how the eight components relate conceptually and logistically, have not been addressed adequately. In essence, a CSHP transforms several solo performers into an orchestra. This article proposes the school health coordinator as an essential element in the eight-component model of the CSHP--the maestro, without whom there can be no symphony. The coordinator's principal responsibilities include administration, integration of personnel and programs, evaluation, and direct intervention. Three program elements--staff wellness, healthy environment, and community/family involvement--are subsumed within the coordinator's role, effectively reducing the number of program elements from eight to five. Potential benefits in addition to issues regarding feasibility of the SHC, are discussed and studies examining the effectiveness of the SHC model are recommended.     

零点位于左扇区的多项式菱形族

本文考虑多项式菱形族的左扇区稳定性,证明了多项式族左扇区稳定的充分必要条件是的至多4q(q—1)条特殊棱边左扇区稳定;进一步,在一定条件下,只要检验的4q个顶点多项式就可确定的左扇区稳定性。     

Chemical-mechanical polishing of SiO2 thin films studied by X-ray reflectivity

Specular X-ray reflectivity from SiO₂ thin films prepared on silicon substrates by plasma-enhanced chemical vapor deposition showed the films to have a characteristic width of the decay in density at the free surface of 17 Å, to be about three-quarters the density of -quartz, and to have an interfacial layer at the silicon interface that was of the order of 100 Å wide and less dense than the bulk of the film. After chemical-mechanical polishing the characteristic width of the decay in density at the free surface was reduced to 10 Å; furthermore, the near-surface region to a depth of 30 Å had a greater density than the as-deposited film. Off-specular reflectivity confirmed that the decrease in characteristic width at the free surface was due to reduced roughness upon polishing and also revealed that the lateral correlation length in the limit of long wavelengths was the same for both polished and unpolished samples. The compression of the near-surface region during polishing is believed to enhance the dissolution of SiO₂ into the slurry which is necessary to achieve smooth surfaces.     

Ti_3Al金属间化合物的熔盐热腐蚀

采用电化学方法并结合扫描电镜、X 射线衍射、电子探针和能谱等物相分析技术研究了 Ti_3Al 金属间化合物在800℃熔融 NaCl-(Na,K)_2SO_4体系中的腐蚀行为。结果表明,Ti_3Al 合金耐熔盐腐蚀性能远低于 Ni 基 IN738合金。腐蚀时在合金表面形成外层为 TiO_2;内层为富 Nb 的Nb_2O_5,Al_2O_3,TiO_2的混合层和中间层为富 Al 的 TiO_2,Al_2O_3混合层的多层腐蚀层结构。Ti 快速向外扩散和氧向内扩散使合金表面腐蚀产物层迅速增厚。腐蚀产物内层的富 Nb 氧化物破坏了膜层与合金基体的粘附性。     

加速水保草业建设 提高生态经济效益

水保种草有山地治理、改土开发、松林改造、封禁培育四种类型，是水土保持主要植物措施之一，见效快，效果好，效益显著。要提高认识，建立基地。做好草的转化利用．