ICP-MS法分析过氧化氢、硝酸、硫酸中的金属杂质

Inductively coupled plasma mass spectrometry (ICP-MS) was used to detect trace metal impurities in reagents such as H2O2, HNO3and H2SO4. The limit of detection to metal elements can be down to 2-20 ng/L in H2O2 and HNO3 and 0.1-1.0 ng/L in H2SO4.     

硫酸-H2O2-罗丹明B-体系阻抑动力学光度法测定痕量EDTA的研究

研究阻抑动力学光度法测定痕量EDTA的新体系。在硫酸介质中,Fe（Ⅲ）催化H2O2氧化罗丹明B的反应可被微量EDTA有效地阻抑,被过量EDTA有效的终止,据此建立了测定痕量EDTA的动力学光度法,用固定时间法在555 nm波长处监测阻抑反应。在0～45.0μg/50mL范围为,线性关系良好,回归方程为ΔA=2.25×10^-2c（c：μg/50mL）,γ=0.9991,检出限为1.1×1 0^-6mg/mL。该方法用于罐头等食品中EDTA的测定,获得满意结果。     

Third ventricular pineal gland grafts in the gerbil: an electron microscopical and immunohistochemical investigation.

The superficial pineal gland was grafted into the third ventricle of adult Mongolian gerbils. Donor pineal glands from both neonatal and 3-4 week old gerbils were able to survive for at least 6 months. The pinealocytes of the grafted superficial pineal glands maintained the morphology and the S-antigen immunoreactivity of the in situ pineal complex. Synaptic ribbons and spherules were present but rare. Unlike the in situ pinealocytes, glycogen accumulations were common in the graft pinealocytes. Site specific modulation of structure was indicated as the ventricular surface of the grafts became covered with cerebrospinal fluid (CSF)-contacting pinealocytes typical of those seen in the deep pineal. The CSF-contacting pinealocytes of the graft had numerous processes that extended along the ventricular surface of the graft. The blood vessels of the grafts had non-fenestrated endothelium and wide perivascular areas typical of those seen in the in situ pineal complex. Tyrosine hydroxylase-immunopositive nerve fibers were present in the grafted tissue indicating reinnervation of the graft. The source of the fibers was not determined. The nerve fibers were present both within the perivascular area and within the parenchyma where they were associated with pinealocytes. The results demonstrate that the cerebral ventricles are an ideal location for the survival of superficial pineal gland grafts. It is suggested that pineal grafts may be a means to further study pineal development and innervation.     

Autoradiographic distribution of radioactivity from (14)C-GABA in the mouse

We investigated the distribution of radioactivity from (14)C-labeled gamma-aminobutyric acid (GABA) in the mouse by in vivo autoradiography to clarify the tissues that show GABA uptake and/or GABA binding. Male mice were injected intravenously with (14)C-GABA in both the absence and presence of an excess of unlabeled GABA, baclofen and isoguvacine. Whole-body autoradiography of (3)H-baclofen, a GABA(B) receptor agonist was also performed. At short intervals after (14)C-GABA injection ( 3 and 6 minutes), very high radioactivity was detected in the kidney cortex, liver, pineal gland, hypophysis, median eminence of the hypothalamus, and cervical ganglion. The hyaline cartilage and glandular part of the stomach showed moderate radioactivity. In the presence of an excess amount of unlabeled GABA, radioactivity in most of tissues decreased significantly, but no significant difference in radioactivity was observed in the presence of baclofen and isoguvacine, agonists of GABA(A) and GABA(B) receptors, respectively. Autoradiography of (3)H-baclofen showed that the kidney had high level of radioactivity, whereas the activity in other tissues and organs was similar or lower than in the blood except for the content of the urinary bladder and the pancreas at 15 minutes after injection. These data indicate that radioactivity from incorporated (14)C-GABA into a variety of cells is much higher than that from bound (14)C-GABA to the receptor sites. Our results suggest that GABA can be quickly localized in many organs of the mouse body after 3 minutes following injection, and GABA may serve multiple functions in those organs.     

CrNiMo钢腐蚀环境中的摩擦学性能研究

以CrNiMo钢和H96黄铜配副,研究了CrNiMo钢在室温蒸馏水润滑环境和H2SO3溶液性环境中的摩擦学性能.采用扫描电子显微镜(SEM)和能谱仪(EDS)对磨损表面进行表征.结果表明:在常温蒸馏水润滑条件和H2SO3溶液腐蚀条件下,摩擦因数均随滑动速度的增加而逐渐减小,而随接触压力的变化较小;H2SO3溶液腐蚀条件下的腐蚀质量损失随腐蚀时间的增加而增大,但其远小于试样的磨损质量损失;H2SO3溶液腐蚀条件下试样的磨损质量损失远大于蒸馏水润滑条件下的磨损质量损失.     

Determination of ZrO2 distribution in an Al2O3 matrix by digital image analysis and point-pattern analysis

Digital image analysis and point-pattern analysis were applied to the microstructures of Al₂O₃-ZrO₂ composites in order to evaluate and classify the distribution of ZrO₂ particles. Scanning electron microscopy micrographs of Al₂O₃-ZrO₂ microstructures were digitized and processed into binary images. Point-pattern analysis was performed using data for mass centers for each ZrO₂ particle and the calculated distribution functions were compared with defined point-pattern distributions—clustered, random, and ordered. Distribution functions for analyzed samples were classified into random groups with different degrees of homogeneity, arising due to the preparation routine. It was shown that the point-pattern analysis can be used to distinguish between the type of distribution and degree of homogeneity for Al₂O₃ ceramic composites.     

Digital PR and Communication with B2B Enterprises in the Digital Era

Russian Engineering Research - There is an evident need for the rapid introduction of digital public relations (PR) at Russian enterprises, so as to raise brand awareness. The essential features of...     

折叠臂式户外高压隔离开关中减振器的研究与设计

高压隔离开关在分闸时,动触头撞击静触头致使设备产生剧烈振动.针对这种冲击产生的振动,提出了一种较为有效的方案--带有位移放大器的减振器,其中耗能弹簧采用具有超弹性和耐腐蚀的形状记忆合金.与已有方案比较,设计的减振器能取得显著的减振效果,改善设备的振动现象,减振效果明显.     

Synchrotron radiation applied to the microscopical examination of solid state and biological materials in the X-ray region

The paper describes the properties of synchrotron radiation and makes some comparison with other X-ray sources. The use of synchrotron radiation for various types of X-ray imaging is discussed with reference to specific examples drawn from work carried out recently at the SERC Daresbury Laboratory.     

An improved method for combined autoradiography and histochemistry: the simultaneous detection of 6-3H thymidine and acid phosphatase activity in cryostat sections of mouse thymus and duodenum

A new method is described that enables the simultaneous detection of 6-³H thymidine incorporation and acid phosphatase activity in the same tissue section. Histochemically, naphthol AS B1 released by tissue based acid phosphatase activity from the substrate naphthyl AS B1 phosphoric acid is coupled with a range of diazonium salts to produce insoluble azo dyes. The azo dye tests result in a particulate localization of lysosomal acid phosphatase and also label diffuse sources associated with cell death. The tests selected permit the application of photographic emulsion without the necessity of an inert barrier layer to separate the emulsion from the histochemically treated cryosections. The localization of 6-³H thymidine incorporation and cell death in mouse thymus and duodenum is demonstrated and comparative counts estimating the distribution of 6-³H thymidine incorporation and hydrolase labelled cell death in the thymus are presented. Young mouse thymus (5 weeks) was found to contain 1·36 ± 0·12% dying cells and 6·78 ± 0·03% thymidine incorporating cells, whilst old mouse thymus (53 weeks) was found to contain 2·34 ± 0·6% dying cells and 5·29 ± 0·37% thymidine incorporating cells.     

Measuring the relative concentration of H2 and D2 in HD gas with gas chromatography

Frozen-spin polarized hydrogen deuteride (HD) targets are being prepared for photonuclear experiments at Jefferson Lab. The targets are frozen HD gas. To polarize and achieve the required spin-lattice relaxation times, the targets are made from high purity HD gas in which the residual H(2) and D(2) concentrations are known. To determine these residual concentrations, a gas chromatograph is used. The separation of the gas components is done in a column cooled to ≈120 K by immersing it in a mixture of liquid nitrogen and isopentane and using neon as the carrier gas. The different hydrogen isotopes have different transit times through the column and their arrival is registered by a thermal conductivity detector. The peaks in the chromatograms are fit using an exponentially modified Gaussian line shape to extract the areas of these peaks. The ratios of areas are corrected for differences in thermal conductivity to give the relative concentrations. Here, H(2) and D(2) concentrations on the order of a few percent have been measured with uncertainties of less than ± 5%. The linear response of the system is confirmed to within about ± 6.3%.     

Internal and platinum initiated crystallization in Na2O.2 CaO. 3 SiO2 glasses: early stages of growth

Transmission electron microscopy at 100, 900 and 1000 kV was used to study the early stages of growth of internally nucleated crystals of the phase Na₂O.2 CaO. 3 SiO₂ (‘NC₂S₃’) in glasses close to the NC₂S₃ composition. Glass samples were partially crystallized by heat treatment in the range 833–873 K and thin foils for electron microscopy were prepared by ion beam thinning. The phase identified by electron diffraction from a number of small crystals (the low temperature form of NC₂S₃) was the same as that determined by X-ray diffraction of fully crystallized glass ceramics. Selected area diffraction and bright and dark field microscopy showed that in the early stages of development the crystallization centres were essentially single crystals but contained a significant concentration of defects. These crystals were nucleated, probably homogeneously, at temperatures higher than the well-established low to high reversible polymorphic transformation of the NC₂S₃ crystalline phase. In a glass of similar composition to which platinum was deliberately added there was clear evidence for heterogeneous nucleation of NC₂S₃ crystals on platinum particles distributed in the glass. Also the contact angle between NC₂S₃ crystals and the rounded platinum particles could be measured directly.     

Combined autoradiography and histochemistry: the simultaneous detection of 6-3H thymidine and acid phosphatase activity in cryostate sections.

A method is described for the simultaneous demonstration of 6-3H thymidine incorporation and acid phosphatase activity in cryostae sections of mouse thymus. The method enables a comparison of mitosis and acid hydrolase activity to be made in the same tissue section. In 8-week-old mice acid phosphatase positive cells reprsent 1.23 +/- 0.06% of the total population and 8.4 +/- 0.27% of the cells incorporate tritiated thymidine. Acid phosphatase activity can be used to estimate cell autolysis and death. The implication of the method in relation to tissue dynamics is discussed.     

Analysis of H atoms in a negative ion source plasma with the non-equilibrium electron energy distribution function

In negative ion sources for the neutral beam injection, it is important to calculate H atom flux onto the plasma grid (PG) surface for the evaluation of H(-) production on the PG surface. We have developed a neutral (H(2) molecules and H atoms) transport code. In the present study, the neutral transport code is applied to the analysis of the H(2) and H transport in a NIFS-R&D ion source in order to calculate the flux onto the PG surface. Taking into account non-equilibrium feature of the electron energy distribution function (EEDF), i.e., the fast electron component, we have done the neutral transport simulation. The results suggest that the precise evaluation of the EEDF, especially in the energy range 15 eV < E < 30 eV is important for the dissociation rate of H(2) molecules by the electron impact collision and the resultant H atom flux on the PG.