Characterization of angiotensin receptors in rabbit isolated atria

Bremsstrahlung x-rays are produced when energetic beta-particles are emitted and absorbed. Measurements of total-body bremsstrahlung efficiencey (x-ray photon output per muCi 90Sr in the body, relative to that in water) have been made in the intact mouse, rat, rabbit, and dog sacrificed 2 weeks after the injection of 90Sr + 85Sr. Efficiencies were determined by a comparison of the bremsstrahlung output from 90Sr + its daughter 90Y and the gamma-ray emission of 85Sr. Results were checked by a beta-assay of the ashed animals. Bremsstrahlung efficiencies averaged 1.10 in a 0.04 kg mouse, 1.14 in a 0.13 kg rat, 1.23 in a 2.6 kg rabbit, and 1.32 in an 8.5 kg beagle. Extrapolating to a 70 kg human, a relative bremsstrahlung efficiency of about 1.4 is predicted. An estimate was made of the 90Sr body content in a former dial painter based on in vivo counting and a bremsstrahlung efficiency of 1.39 predicted for a 55 kg human female by these animal data. Our value of 1.42 +/- 0.08 muCi 90Sr was in good agreement with corresponding results reported for this subject by 8 other laboratories.     

Measurement of 90Sr in bone ash

Bone is a critical organ for the accumulation of many radionuclides, including 90Sr. A bone ash has been prepared by NIST to become a standard reference material and the assaying of the 90Sr activity concentration is reported. A radiochemical procedure, based on extraction chromatography using a crown ether, has been developed to separate Sr from the bone ash. The natural Sr content of the bone ash has been determined by isotope dilution inductively coupled plasma mass spectrometry. The 90Sr activity concentration has been measured by low-level liquid scintillation counting.     

A Study on the Dissolving Loss of Nd in the NdCl_3-Containing Systems

The Dissolving loss of Nd in the systems NdCl_3-MCl_n(M=Li,Na,K,Ca,Sr,Ba;n=1 or 2)and the NdCl_3-rich NdCl_3-LiF motlen salts,and in the system of NdCl_3-(90 wt% KCl,10 wt%MCl_n) wasdetermined.It was found that the dissolving loss of Nd (B_(Nd)) in the NdCl_3-KCl,NdCl_3-CaCl_2 andNdCl_3-(90 wt%KCl,10 wt%CaCl_2) melts is rather insignificant.The dissolving loss of Nd in theNdCl_3-KCl system increases with temperature,yet it is only 1/3 of that in pure NdCl_3 when the content ofNdCl_3 was less than 50 wt% in the mixture.Addition of LiF to NdCl_3 can diminish the dissolving loss ofNd.The nature of interaction between metallic Nd and its salts was also discussed.     

土壤中~(90)Sr的测定统计报告

在<土壤中90Sr的分析方法>行业标准修订过程中,为了验证分析方法的可靠性,4家分析单位共同合作开展了一次比对工作.介绍了比对工作中的数据统计过程,包括数据汇总、数据检验、重复性和再现性的计算.     

土壤样品中90Sr测定的前处理

用硝酸沉淀法处理环境土壤样品时,经多次沉淀和溶解过程,使^90Sr有部分损失。跟踪^90Sr的损失过程,可从中找出提高^90Sr浸出率的方法。在生成碳酸盐沉淀后,用离心法在3OOOr／min条件下,分离出含有腐殖酸的上层清液。土壤前处理过程中,^90Sr浸出率下降最大的是在草酸盐沉淀生成过程中,特别是在pH为4.O、生成褐色沉淀时,下降得更为明显。加入过量的草酸使生成白色沉淀并对上层澄清液进行再沉淀,可将^90Sr回收率提高到80％～90％。     

Radionuclides in the Kara sea bottom sediments

The contents and distribution of natural (214Pb, 214Bi, 228Ac, and 208Tl) and technogenic (90Sr, 137Cs, and 60Co) radionuclides in the Kara Sea bottom sediments was analyzed by using the materials collected by R/V "Pomor" (Murmansk Marine Biological Institute). In 1994, no high (critical) concentrations of technogenic radioisotopes were found in the sea sediments, while the spots (regions) of elevated 137Cs content found in 1984 were not confirmed in 1994. It was proposed that the main sources of entry of technogenic radionuclides in the sea sediments in the last years are the flow of the Ob'-Yenisei waters and container burials of radioactive waste in the sea, which appeared to have been markedly corroded. The latter is confirmed by detection in some places of 60Co, which was not previously found in the sediments.     

Biological effects of acute external or internal irradiation of rats in the framework of nitrite intoxication

The material presented provides evidence that high nitrite doses have a various effect under the condition of external or internal radiation. Thus, nitrite protector properties were observed in male rats exposed to external radiation using the LD50/30 while following 90Sr exposure male rats of the same age showed a higher sensitivity to the radionuclide. The nitrite combined with optimum carcinogenic 90Sr dose had a potentiating effect on both life-span shortening and increase in osteosarcoma rate in the animals.     

Influence of Extrusion on the Microstructure and Mechanical Behavior of Mg-9Li-3Al-xSr Alloys

Mg-9Li-3Al-xSr (LA93-xSr, x = 0, 1.5, 2.5, and 3.5 wt pct) alloys were cast and extruded at 533 K (260 °C) with an extrusion ratio of 28. The microstructure and mechanical response are reported and discussed paying particular attention to the influence of extrusion and Sr content on phase composition, strength, and ductility. The results of the current study show that LA93-xSr alloys contain both α-Mg (hcp) and β-Li (bcc) matrix phases. Moreover, the addition of Sr refines the grain size in the as-cast alloys and leads to the formation of the intermetallic compound (Al₄Sr). Our results show significant grain refinement during extrusion and almost no influence of Sr content on the grain size of the extruded alloys. The microstructure evolution during extrusion is governed by continuous dynamic recrystallization (CDRX) in the α-Mg phase, whereas discontinuous dynamic recrystallization (DDRX) occurs in the β-Li phase. The mechanical behavior of the extruded LA93-xSr alloy is discussed in terms of grain refinement and dislocation strengthening. The tensile strength of the extruded alloys first increases and then decreases, whereas the elongation decreases monotonically with increasing Sr; in contrast, hardness increases for all Sr compositions studied herein. Specifically, when Sr content is 2.5 wt pct, the extruded Mg-9Li-3Al-2.5Sr (LAJ932) alloy exhibits a favorable combination of strength and ductility with an ultimate tensile strength of 235 MPa, yield strength of 221 MPa, and an elongation of 19.4 pct.     

Effect of Sr^2＋ on Properties of Li0.2375＋xLa0.5875-xSrxTiO3-LaPO4 System

Ionicconductingsolidmaterialshavereceivedconsiderableattentioninthelastfewyearsduetotheirpotentialutilityinhighenergybatteriesandotherelec trochemicaldevices .SeveralsystemsoflithiumfastionconductorsareknowntoshowhighlithiumionconductivitysuchasγLi3PO4 typesolidsolution[1] ,LiTi2 (PO4 ) 3anditsderivations[2～4 ] andLi14 Zn(GeO4 ) 3solidsolution[5] .However ,exceptforlowpowerapplications ,onemajorproblemwiththepracticalapplicationsisitslowconductivityatroomtemperature .Recentyears ,morean…     

Hot-Tearing Susceptibility of Ternary Mg-Al-Sr Alloy Castings

The susceptibility of Mg-Al-Sr alloys to hot tearing during permanent mold casting was investigated using constrained rod casting (CRC) in a steel mold. The alloys included Mg-xAl-1.5Sr and Mg-xAl-3Sr, where x = 4, 6, or 8 wt pct. The hot-tearing susceptibility (HTS) was determined based on the widths and locations of the cracks in the rods. With the Mg-xAl-1.5 Sr alloys, the HTS decreased significantly with increasing Al content. With the Mg-xAl-3Sr alloys, the trend was similar but not as significant. At the same Al content, the HTS was significantly lower at 3 wt pct Sr than at 1.5 wt pct Sr. To help understand the HTS of these alloys, the solidification path and phase fractions were calculated for each alloy. The HTS was found to increase with increasing fraction solid at the end of primary solidification.     

The individual characteristics of 90Sr accumulation in the body of 2 species of the common vole inhabiting the territory of the eastern Urals radioactive trace

Individual peculiarities of 90Sr skeleton deposition in voles M. gregalis and M. arvalis inhabiting at the territory of East Ural Radioactive Trace were investigated. More high accumulation of radionuclide in the organism of M. gregalis was registered. Considerable variations (3-6 times more, than in linear mice ones) of individual indices of radionuclide accumulation exceeding interspecies level are found. Possible reasons of both interspecies differences and an individual deposition' variability were discussed.     

SrCl2-KCl-SrF2体系中熔盐电解法制备铝锶合金

以SrCl2为原料,在70%SrCl2-29%KCl-1%SrF2体系中电解生产Al-Sr合金。考察了电解温度、电流密度和电解时间等条件对电流效率和合金锶含量的影响。通过控制工艺条件,可以生产锶含量在0～10%的Al-Sr合金,其物相主要为Al与Al4Sr。     

Aquatic Assessment of the Chernobyl Nuclear Accident and Its Remediation

This modeling study evaluated the aquatic environment affected by the Chernobyl nuclear accident and the effectiveness of remediation efforts. The study results indicate that radionuclide concentrations in the Pripyat and Dnieper rivers were well above the drinking water limits immediately after the Chernobyl accident but have decreased significantly in subsequent years due to flushing, burying, and decaying. Because high concentrations of 90Sr and 137Cs, the major radionuclides affecting human health through the aquatic pathways, are associated with flooding, two earthen dikes were constructed along the Pripyat River. The left-bank dike alone was successful in reducing the 90Sr concentration in the river by half. The 100-m-high, movable New Safe Confinement (NSC), which will cover the current Chernobyl Shelter, will reduce radionuclide contamination further in these rivers and nearby groundwater. If the Chernobyl Shelter should collapse before the NSC is built, the resulting peak radionuclide concentrations in the Dnieper River are expected to still remain below the drinking water limits. The radionuclide influx to groundwater through the NSC should not have any effect on concentrations in the Pripyat River.     

Schematic model of genesis of osteosarcoma induced by Sr-90

The development of radiation osteosarcoma genesis scheme induced by 90Sr was the subject of the present study. The production of cancer cells after exposure to a specific dose-rate of emitting 90Sr incorporated in the skeleton are typical for the initiation period. However not all the cells remain in the mutant DNA. In some of them DNA reparation occurs, other cells are killed in the process of the subsequent divisions, and only a few of them containing mutant DNA are preserved in the state of repression up to the end of life time. Disorders of homeostasis due to exhausted of physiological reserves - (natural or early aging) are manifested as a promoter. In that period the derepression of mutant DNA occurs and malignant growth of tumor starts.     

Cold exposure enhances nitroxidergic nerve-mediated vasodilatation in canine nasal mucosa

An intercomparison using two popular survey meters was arranged to assess the ability of participants to test surface contamination monitors in compliance with the requirements of the Ionising Radiations Regulations 1985. The instruments were circulated and the data returned were compared with the NRPB values. The major inconsistencies were caused by differences in the interpretation of what constitutes 1 Bq of 90Sr+ 90Y and in the conversion of the emission rate from (129)I plaques into a value of equivalent (125)I activity.     

铝锶比对合成铝酸锶铕发光性能及水解稳定性的影响

合成铝酸锶铕绿色荧光粉时,当改变Al/Sr加料比时,产物的物相组成、发光特性和抗水稳定性均有变化。合成产物主要由两相组成,当Al/Sr比为1.5时,合成产物的主晶相为Sr4Al4O2(Al10O23),同时SrAl2O4相的含量也较高。由于SrAl2O4相易于水解,所以其抗水稳定性差。提高Al/Sr比,抗水稳定性逐渐增强。     

The role of solute in grain refinement of magnesium

The effect of separate solute additions of Al, Zr, Sr, Si, and Ca on grain size of Mg has been investigated. Increasing the Al content in hypoeutectic Mg-Al alloys resulted in a continuous reduction in grain size up to 5 wt pct Al, reaching a relatively constant grain size for higher Al contents (above 5 wt pct). The effect of Sr additions was investigated in both low- and high-Al content magnesium alloys, and it was found that Sr had a significant grain refining effect in low-Al containing alloys but a negligible effect on grain size in Mg-9Al. Additions of Zr, Si, and Ca to pure magnesium resulted in efficient grain refinement. The grain refinement is mainly caused by their growth restriction effects, i.e., constitutional undercooling, during solidification, but the effect of nucleant particles, either introduced with the alloying additions or as secondary phases formed as a result of these additions, may enhance the grain refinement. A brief review of grain refinement of magnesium alloys is included in this article to provide an update on research in this field.     

A New Hot Tearing Assessment by Using Stepped Ring Core Mold and the Effect of Strontium on the Hot-Tearing Resistance of Al–6 wt% Zn Based Alloy

Automobile and aerospace industries use thin wall aluminium alloy castings which provide lighter structures with excellent mechanical properties. Production of thin wall castings is more challenging due to hot tear formation. Lack of fluidity in molten alloy causes hot tears and must be addressed in thin wall castings of Al-alloys. The present study is focused on a new technique known as stepped ring mould casting. It is possible to assess the hot tear susceptibility of Al–6Zn alloys by varying ring thickness to find out the critical thickness for occurrence of hot tears. The alloy was cast using different strontium (Sr) concentrations (0.2, 0.4, 0.6%). Effects of strontium concentrations were studied in terms of fluidity, porosity content, microstructure and tensile properties of Al–6Zn alloy. In the present work, unmodified and Sr modified alloy casts were characterized by SEM, EDS and XRD respectively. Al–6Zn ingots were procured by master alloy route. Repetition of stepped ring test on the critical thickness showed that hot tear were successfully eliminated significantly due to the addition of Sr. On the other hand, 0.6% Sr also exhibited a good amount of porosity and decrease in elongation. Shorter fluidity length was observed in 0.2% Sr modified alloy. Mechanical and metallographic tests revealed that the alloy castings modified with 0.4% Sr offered better results in yield strength, less porosity and an improved hot tear resistance at micro and macro levels.     

Properties of La0.9Sr0.1MnO3 and tourmaline compound catalytic materials for methane combustion

A novel catalytic material Lao.9Sr0.1MnO3 and tourmaline compound catalytic material was synthesized in the base of traditional catalytic material La0.9Sr0.1MnO3 which exhibited excellent catalytic activity for methane combustion. Different contents of toumaaline were added to give a series ofLa0.9Sr0.1MnO3 and tourmaline catalytic material through a sol-gel method. Samples above were characterized and analyzed by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, Brunauer-Emmett-Teller method （BET）, temperaalre programmed reduction （TPR）, catalytic activity test and contact angle test. The as-prepared sample with 2% （m/m） tourmaline showed good homogeneity surface morphology and displayed the optimal catalytic activity. The light-off temperature reduced by 10 ℃ and the T90 decreased by 15 ℃. In addition, the mechanism of the reinforcement of catalytic activity was explored.     

Eutectic nucleation and growth in hypoeutectic Al-Si alloys at different strontium levels

The effects of different levels of strontium on nucleation and growth of the eutectic in a commercial hypoeutectic Al-Si foundry alloy have been investigated by optical microscopy and electron backscattering diffraction (EBSD) mapping by scanning electron microscopy (SEM). The microstructural evolution of each specimen during solidification was studied by a quenching technique at different temperatures and Sr contents. By comparing the orientation of the aluminum in the eutectic to that of the surrounding primary aluminum dendrites by EBSD, the eutectic formation mechanism could be determined. The results of these studies show that the eutectic nucleation mode, and subsequent growth mode, is strongly dependent on Sr level. Three distinctly different eutectic growth modes were found, in isolation or sometimes together, but different for each Sr content. At very low Sr contents, the eutectic nucleated and grew from the primary phase. Increasing the Sr level to between 70 and 110 ppm resulted in nucleation of independent eutectic grains with no relation to the primary dendrites. At a Sr level of 500 ppm, the eutectic again nucleated on and grew from the primary phase while a well-modified eutectic structure was still present. A slight dependency of eutectic growth radially from the mold wall opposite the thermal gradient was observed in all specimens in the early stages of eutectic solidification.