基矛电磁波的低流速测量中干扰因素分析研究

介绍了电磁渡测量流速的基本原理一多普勒效应．分析了影响低流速测量的主要干扰因素一发射泄漏干扰和旁瓣干扰。根据接收信号中发射泄漏干扰不变的特性,提出了去均值滤波的方法来消除干扰,对数据进行预处理;根据旁瓣干扰的信号特性,提出了通过频谱加窗和二次加权平均法构造频域带通滤波器来抑制干扰的方法,在仿真比较完各个窗函数的性能之后,选定布莱克曼窗来进行频谱加窗。仿真分析表明,旁瓣干扰经频域带通滤波后得到了很好的抑制。最后通过实验测试验证了这些方法在流速测量中的显著效果。     

Gamma irradiation-induced modifications in the structural,thermal, and optical properties of polyvinyl alcohol-polyethylene glycol/cobalt oxide nanocomposite films

Cobalt oxide nanoparticles (NPs) are highly consistent dispersed into the blend polymers rather than other NPs. Also, the ability of polyvinyl alcohol-polyethylene glycol (PVA-PEG) to form homogenous blend attained it essential characteristics that allow it to be suitable candidate for numerous industrial applications. Thus in the present work, Co₃O₄ nano-oxide, was synthesized by the sol-gel procedure and PVA-PEG/Co₃O₄ nanocomposite NCP films were synthesized by the casting technique. Samples from the synthesized NCP were exposed to γ doses between 20 and 230 kGy. The induced alterations in the synthesized NCP due to gamma irradiation have been illustrated using X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA), Fourier transform infrared (FTIR), and UV spectroscopes. Further, Color divergence between the blank and the irradiated films has been estimated. Gamma doses between 60 and 230 kGy lead to the prevalence of intermolecular crosslinking, which enhances the disordered phase. This is reflected in a rise in the degradation temperature values from 225°C to 236°C indicating an improvement in the thermostability of the NCP samples. Moreover, the γ-radiation induces defects that split the ordered portion, reducing T_m from 238°C to 229°C. In addition, the band gap decreases from 5.24 to 4.61 eV with increasing the γ doses to 230 kGy, signifying disorder character. Finally, the NCP samples showed a color change by γ radiation, as ΔE raised with increasing dose. The resultant improvements in the optical properties of the NCP samples allow it to be used in optoelectronic and dosimetric applications.     

Assessment of antifungal activities of fluconazole and amphotericin B administered alone and in combination against Candida albicans by using a dynamic in vitro mycotic infection model

We evaluated the pharmacodynamic activities of fluconazole and amphotericin B given alone and in combination against Candida albicans by using an in vitro model of bloodstream infection that simulates human serum pharmacokinetic parameters for these antifungals. Fluconazole was administered as a bolus into the model to simulate regimens of 200 mg every 24 h (q24 h) and 400 mg q24 h. Amphotericin B was administered at doses producing the peak concentration (2.4 micrograms/ml) observed with a regimen of 1 mg/kg of body weight q24 h. A combination regimen of fluconazole (400 mg q24 h) and amphotericin B (1 mg/kg q24 h) administered simultaneously and as a staggered regimen (amphotericin B bolus given 8 h after fluconazole bolus) was also simulated in the model to characterize possible antagonism between these agents. Fluconazole alone and amphotericin B alone demonstrated fungistatic (< 99.9% reduction in numbers of CFU per milliliter from the starting inoculum) and fungicidal (> 99.9% reduction) activity, respectively. When fluconazole and amphotericin B were administered simultaneously, fungicidal activity similar to that observed with amphotericin B alone was observed. Staggered administration of fluconazole and amphotericin B, however, resulted in a substantial reduction of the fungicidal activity of amphotericin B, producing fungistatic activity similar to that observed with noncombination fluconazole regimens. These results demonstrate the usefulness of this model for comparing the in vitro pharmacodynamic characteristics of different antifungal regimens and support the theory of azole-polyene antagonism. The effects of this antagonism on the in vivo activity and clinical usefulness of combination antifungal therapy, however, remain to be determined.     

Developing a brief measure of smoking in the home: description and preliminary evaluation

The insulin-like growth factors (IGF-I and IGF-II) play a key role in cellular proliferation and are involved in cellular transformation. The expression of the IGF-I receptor has been demonstrated in a variety of human tumor cell lines including ovarian cancer cells. Phosphorothioate antisense oligodeoxynucleotides (S-ODNs) were analyzed for their potential to suppress the IGF-I receptor in the NIH: OVCAR-3 ovarian cancer cell line. The application of the antisense S-ODN reduced potently the cell growth of unstimulated NIH:OVCAR-3 cells, whereas sense and mismatch S-ODNs were without any effect. This effect resembled that of the monoclonal antibody (MAb) alphaIR-3. In contrast to the antisense compound, this MAb only partially inhibited the IGF-I-induced proliferation of ovarian cancer cells. The concentration of the antisense S-ODN to exhibit an identical inhibition of cell proliferation was reduced to 50 nM when the oligonucleotides were delivered by the cationic lipid formulation lipofectin. The specificity of the antisense S-ODN action was confirmed by reduction of the receptor protein and of the receptor mRNA, as assayed by flow cytometry and by Northern blot hybridizations. Our data demonstrate the potency of antisense S-ODNs to target the IGF-I receptor message and show that antisense strategies against the IGF-I receptor may provide new strategies for the therapy of ovarian cancer.     

Experimental Investigation of the Mixing Between Hot and Cold Gas in Two Cooling Processes

The mixing between a hot turbulent flow and a cold fluid, injected through a porous plate or using a discrete injection, is experimentally investigated. The blowing is shown to dramatically modify the dynamic and thermal fields, whereas the discrete injection has a weaker effect. The influence on the average quantities and fluctuating parts are found to be different. The effect of the main flow temperature is addressed and a discussion for the mixing in the blowing and discrete injection cases is proposed.     

Abnormalities in the p34cdc2-related PITSLRE protein kinase gene complex (CDC2L) on chromosome band 1p36 in melanoma

Recently, several clusters of hepatitis A have been observed among hemophiliacs linked to factor VIII concentrates treated for virus inactivation solely with the solvent/detergent (S/D) method, a procedure that does not affect nonenveloped viruses such as the hepatitis A virus (HAV). A new outbreak of hepatitis A in six hemophiliacs treated with the same lot of a factor VIII preparation occurred recently in Germany. The objective of the study was to clarify whether these diseases were caused by the administration of the S/D-treated plasma product, rather than a community-acquired infection. Polymerase chain reactions designed to detect HAV nucleic acid have been carried out in the implicated factor VIII lots, in the corresponding plasma pools, and in serum samples of four out of six infected individuals. The nucleic acid sequences were determined in samples that resulted in positive amplification products. HAV sequences were found in one of the two plasma pools used for manufacture of the incriminated product, in the incriminated lot itself, and in all recipient sera tested so far, although the latter were collected up to 7 weeks after the onset of jaundice. The sequences obtained were completely identical, revealing a unique HAV strain of genotype IA. This study provides conclusive evidence that hepatitis A can be transmitted by factor VIII concentrates treated solely by the S/D procedure for virus inactivation. This inactivation method is not effective against nonenveloped viruses. Since a number of hepatitis A transmission episodes have been described with such preparations during the past 10 years, their continued use seems to be questionable unless additional virus removal or inactivation steps are introduced to prevent the transmission of nonenveloped viruses. Molecular approaches again proved to be reliable tools for elucidating the chain of virus transmission.     

Crucial role of FcgammaRIIa (CD32) in assessment of functional anti-Streptococcus pneumoniae antibody activity in human sera

Immunoglobulin G (IgG)-mediated phagocytosis by polymorphonuclear leukocytes (PMNL) constitutes the main defense against Streptococcus pneumoniae. Two leukocyte IgG receptors, FcgammaRIIa and FcgammaRIIIb, are constitutively expressed on PMNL. Blocking experiments showed FcgammaRIIa is crucial for opsonophagocytosis of serum-opsonized S. pneumoniae. The biallelic, genetically determined FcgammaRIIa polymorphism (FcgammaRIIa-R131 vs. IIa-H131) determines the capacity of IgG2-mediated phagocytosis via this receptor. Comparative studies with PMNL from donors either homozygous for FcgammaRIIa-R131 or IIa-H131 showed the latter had higher phagocytic capacity. These results were confirmed in FcgammaRIIa-R131- and FcgammaRIIa-H131-transfected IIA1.6 cells. The performance of FcgammaRIIa-transfected cells in S. pneumoniae phagocytosis was validated using sera from adults and children. Serum-induced phagocytic activity depended mainly on anti-pneumococcal IgG2 antibodies. Results obtained with PMNL and IIA1.6 cells showed high correlation (r=0.94; P<.001), and support that FcgammaRIIa transfectants are a good alternative to PMNL as effector cells in opsonophagocytosis assays.