Cytophotometric determination of non-heme iron content in hepatocytes. I. Effect of cell separation techniques on iron content

To study conditions of the preservation of non-heme iron (3+) in hepatocytes, experiments were performed on rats fed with the diet supplemented with 2% carbonyl iron. The cells were isolated by a collagenase method (an enzymatic method) or by a treatment of the tissue with the phosphate buffer (a nonenzymatic method). When using the enzymatic method, the main steps of obtaining preparations-smears were analysed: perfusion of the organ, subsequent washing out of the cells from collagenase, mounting of the smear on the object glass. When using the non-enzymatic method, such steps were an incubation of the tissue pieces in the isolation solution and mounting of the smears. It has been found that the enzymatic isolation method results in practically no losses of iron from the cells if the perfusion lasts for 20 min. A slight loss (10-12%) of the Perls'-stained iron can occur during the initial 30 min of the washing out of the cells from collagenase. This step is not accompanied by any morphological changes of the cells; their viability, according to the trypan test, is 70-87%. The iron release from the cells rises with decrease in the viability of hepatocytes. It has been shown that the greatest losses of iron can occur at the mounting step when the cells are submitted to a substantial mechanical effect. When the nonenzymatic method is applied, the incubation of the cells in the phosphate buffer for up to 2 hr causes no marked morphological changes revealed in the light microscope; however, the cell viability is very low (about 1%). The preservation of iron in the cells is lower when using the nonenzymatic than the enzymatic method. Thus, for cytophotometric determinations of the iron content in hepatocytes, the collagenase method of isolation of cells is recommended.     

铁矿石中砷含量的测定国际标准研制

以铁矿石中测定砷含量的国内外技术现状、发展趋势为技术背景,介绍了我国开展铁矿石中砷含量的测定国际标准研制的情况。     

锌铁合金钢板镀层中铁含量的检测方法探讨

采用标准化学法和两种X射线荧光法对锌铁合金钢板镀层中的铁含量进行了测定研究.试验结果表明,对于锌铁合金样板镀层中铁含量的测定,标准化学法是准确性最佳的方法,但是该方法检测效率低,不适用于生产质控检测.X射线荧光法中的基本参数法和经验系数法均可用于锌铁合金钢板镀层中铁含量的生产质控检测,检测重复性分别可达0.2％和0.4％,均优于原子吸收法的0.6％.但是,这两种X射线荧光法均有各自的使用限制,对于不同机组生产的锌铁合金钢板的检测准确性较标准化学法差,需谨慎限制使用.     

The 2-His-1-carboxylate facial triad--an emerging structural motif in mononuclear non-heme iron(II) enzymes

PURPOSE: To determine in-line pressures generated in small-bore central venous catheters during power injection of computed tomographic (CT) contrast media. MATERIALS AND METHODS: Five 3.0-7.0-F central venous catheters for pediatric patients were tested at full and half lengths in vitro. In-line pressures were measured during power injection of three contrast media. Rates of injection were increased in steps from 0.1 to 5.0 mL/sec or until a peak pressure of 100 psi (700 kPa) was achieved. The maximum tolerated flow rate was determined with reference to the manufacturer's suggested operating pressure limit for each catheter. RESULTS: At full length, the maximum tolerated flow rates were as follows: 2-3 mL/sec for the large lumen and 1-1.4 mL/sec for the small lumen of the 7.0-F double-lumen catheter; 0.2-0.4 and 0.8-1.2 mL/sec for the 3.0- and 4.0-F peripherally inserted central catheters, respectively; 0.7-1.2 mL/sec for the 6.6-F catheter; and only 0.2 mL/sec for the 4.2-F catheter, which ruptured during testing at higher flow rates. CONCLUSION: Flow rates were documented at which certain small-bore central venous catheters should tolerate power injection of CT contrast media with peak pressures remaining below the manufacturer's recommended operating pressure limits. These data may serve as a guide for clinical use.     

Bicarbonate binding to the non-heme iron of photosystem II investigated by Fourier transform infrared difference spectroscopy and 13C-labeled bicarbonate

The binding site of the non-heme iron of photosystem II (PS II) is investigated by light-induced Fourier tranform infrared (FTIR) difference spectroscopy on Tris-washed membranes. The non-heme iron is oxidized (Fe3+) in the dark with ferricyanide and reduced (Fe2+) after light-induced charge separation by electron transfer from the semiquinone anion QA-. EPR experiments and IR modes of ferri- and ferrocyanide show that the electron donor side of PS II is reduced in less than 2 s after a flash and that ferricyanide reoxidizes the non-heme iron with a half-time of approximately 20 s. Recording FTIR spectra before and 2 s after flash illumination thus results in the Fe2+/Fe3+ difference spectrum. This spectrum shows band shifts and intensity changes of IR modes from ligands and neighboring residues of the non-heme iron. The IR modes of bicarbonate are revealed by comparison of Fe2+/Fe3+ spectra obtained on PS II membranes with 12C or 13C isotope labeled bicarbonate in H2O and in 2H2O. The nu as(CO) and nu s(CO) modes of bicarbonate in the Fe2+ state are assigned at 1530 +/- 10 and 1338 cm-1, respectively. The low frequency of the nu as(CO) mode is taken as experimental evidence that bicarbonate is a ligand of the non-heme iron. Furthermore, the small frequency difference (192 cm-1) between the nu as(CO) and nu s(CO) modes as compared to even hydrogen-bonded ionic bicarbonate strongly indicates that bicarbonate is a bidentate ligand of the non-heme iron in PS II. Upon iron oxidation, the bicarbonate modes are largely affected. The nu s(CO) mode is assigned at 1228 cm-1, while the nu as(CO) mode is tentatively assigned at 1658 +/- 20 cm-1. The strong up- and downshifts of the nu as and nu s(CO) modes of bicarbonate upon iron oxidation results in a frequency difference of 430 +/- 20 cm-1 that is not only explained by the increased charge on the iron but indicates that bicarbonate is a monodentate ligand of the oxidized iron. The sensitivity of the nu s(CO) mode of bicarbonate to 1H/2H exchange in both the Fe2+ and Fe3+ states and the presence in the Fe2+ state of a delta (COH) mode at 1258 cm-1 confirm that bicarbonate and not carbonate is the iron ligand and further exhibits hydrogen bond(s) with the protein. The 13C isotope-sensitive modes of bicarbonate are not affected by 15N labeling of the PS II membranes. 15N sensitive signals at 1111/1102 and 1094 cm-1 are assigned to side chain modes from histidine ligands of the iron. The latter signal is proposed to account for a histidine ligand that deprotonates upon iron oxidation. The involvement of protein peptide groups and side chains in the hydrogen-bond network around the iron is also discussed.     

高频燃烧红外吸收法测定铁矿石中硫

由于在采用ASTME1915-01<采用燃烧红外吸收光谱法分析金属矿石及相关原料的标准试验方法>标准[1]对铁矿石进行分析时,发现样品颜色不同硫的分析结果相差很大,为此我们进行了专门研究,发现红色与黑色的铁矿粉其结构上有所不同,所以熔样效果上就出现差异,一般的助熔剂,不能完全适应,有时会造成板流偏低,硫释放不完全,使测定结果不稳定而且偏低.     

铁水w（Si）对高炉碳排放量的影响

高炉炼铁排放CO2是钢铁行业温室气体排放的主要来源,CO2的产生与高炉内众多条件相关。应用物料平衡计算与热平衡计算,根据国内某高炉原料条件与冶炼参数,主要计算分析铁水w（Si）对焦比、碳排放量的影响,得出了定性定量的关系：在本文的计算条件下,铁水w（Si）每升高0.1%,焦比吨铁增加4.54 kg,碳排放量吨铁增加7....     

酸溶重铬酸钾容量法测定铁含量的分析与探讨

目前,铁含量的测定方法主要采用的是:酸溶或者碱熔分解试样,然后采用二氯化锡和三氯化钛作为还原剂,利用重铬酸钾作为标准溶液滴定测定铁含量的经典方法。本文在传统的重铬酸钾容量法基础之上,加以改进,经过反复多次实验,确定最佳实验反应条件,并对实验结果进行验证分析,确定改进方法的适用范围。     

Effect of phase transformation in higher iron silicide on the electrical conductivity of the multiphase system iron silicide-glass. II. Effect of structural transformation in lebeauite on the temperature dependence for composite resistivity

Annealing at the eutectoid decomposition temperature for higher iron suicide -phase is studied for its effect on the temperature dependence for resistance (T) of a composite based on cermet containing iron suicide and barium borosilicate glass. An attempt is made to distinguish the contribution of -FeSi₂ to the (T) dependence of the system on a background of the conductivity of the other phase components.Translated from Poroshkovaya Metallurgiya, No. 10, pp. 20–24, October, 1992.     

硫酸亚铁铵滴定法测定铁矿石中钒含量国家标准研究

通过对硫酸亚铁铵滴定法测定铁矿石中钒含量方法的研究,对原国家标准GB／T6730．32—1986进行修订,新国标增加了碳酸钠一硼酸混合熔剂熔融分解试样,优化了指示剂校正和空白测定及铬干扰的消除方法,同时进行了精密度试验,用精密度（重复性限和再现性限）代替了原标准的允许差。     

Cytophotometric determination of DNA concentration in the nuclei of the human placental trophoblast in late toxemias of pregnancy

The distribution of trophoblast nuclei of the human placenta by their ploidy was studied in normal pregnancy and in late pregnancy toxemias by the monowave emthod of cytophotometry in visible light. In the plasmodiotrophoblast a pronounced increase in the amount of nuclei in the S-phase (up to 40%) was noted in late toxemias which suggests a considerable activation of the DNA synthesis. The placenta cytotrophoblast in late toxemias is substantially different from that in normality. The Langhans cells disappear almost completely while in normality they are present in young terminal villi till the very end of pregnancy. The amount of the island cytotrophoblasts is much greater, the distribution of nuclei according t the DNA content being of absolutely different character than in normality. A great amount of hypodiploid nuclei (up to 36%) was observed which are absent in normal conditions as well as much greater fluctuations in the amount of diploid nuclei (from 4% to 37%) as compared with the normal amount (25.9%). These data show a high amitotic activity in the island cytotrophoblast in late toxemias. The above changes in the plasmodiotrophoblast and cytotrophoblast might be considered as a compensatory reaction of the placenta to a considerably increased vacuolization and deep atrophic processes in degenerating villi.     

Effect of the trivalent iron content in a pyrrhotine concentrate on the reaction mechanism of its sulfuric acid leaching

The laws of atmospheric sulfuric acid leaching of pyrrhotine concentrate are analyzed as a function of the redox potential of a reaction system, which is determined by the Fe(III) content in a solution.     

New methods for the determination of hydrogen content of aluminum and its alloys: Part II. Rapid determination by the nitrogen carrier fusion method

A method for determining hydrogen in steel by melting with nitrogen as a carrier gas was adapted for aluminum and its alloys. Dehydrogenationvs temperature was investigated in order to define an optimal sequence of operating conditions. The results obtained by the method were systematically compared to those given by the reference vacuum hot extraction method. The essential characteristics of this new method can be summarized as follows: 1) The detection limit is 0.02 ml/100 g (0.02 ppm H₂). 2) The method is valid for any alloy, even for those with high volatile constituent content such as Zn or Mg. 3) The bulk hydrogen content is not significantly different from that given by the vacuum hot extraction method. 4) “Surface” hydrogen could be eliminated by a thermal treatment at 400°C prior to melting. 5) Correlations appeared between changes in thermal and dehydrogenation curves, the last one representing a characteristic spectrum of the alloy studied. 6) A complete analysis requires 15 min instead of several hours for the hot extraction method. It is thus applicable in routine industrial work.