新疆某高硫高砷金精矿的预处理氰化浸金试验研究

对新疆某高硫高砷金精矿.加入ZOD助浸剂预处理后氰化浸出,金氰化浸出率由未经ZQD预处理的47.5%增加到89.1 %;加入固化剂CaO-Na2CO3二段焙烧(一段450℃,焙烧1h,二段650℃,焙烧2 h)后,再进行助浸预处理氰化,金氰化浸出率可达95.1%,硫固化率达到80.5%.     

A compact positron annihilation lifetime spectrometer

Using LYSO scintillator coupled on HAMAMATSU R9800 （a fast photomultiplier） to form the small size γ-ray detectors, a compact lifetime spectrometer has been built for the positron annihilation experiments. The system time resolution FWHM=193 ps and the co     

Determination of the time resolution for neutron scintillation detectors by multi-coincidence measurement

Based on the multi-coincidence measurement, the time resolution of three liquid scintillation detectors （BC501A） were determined strictly by solving the coincidence equations, where the influence from electronics estimated by self coincidence measurement     

NaI （Tl） calorimeter calibration and simulation for Coulomb sum rule experiment in Hall-A at Jefferson Lab

A precision measurment of inclusive electron scattering cross sections is carried out at Jefferson Lab in the quasi-elastic region for 4 He, 12 C, 56 Fe and 208 Pb targets. The longitudinal （R L ） and transverse （R T ） response functions of the nucleon ne     

Positron annihilation in powder metallurgical materials of various degrees of porosity

Conclusions A material with a well-developed surface is characterized by a narrowing of its AAPD curve and by the appearance of a narrow component in the small-angle region. The positron annihilation parameters of nickel powder compacts are greater than those of cast and worked nickel and grow with increasing degree of porosity, which is evidence for preferential positron localization on the pore surfaces. Using experimental data and a model of positron trapping by defects, estimates were made of the effective pore size¯R_v and pore concentration C_v as functions of the degree of porosity.Translated from Poroshkovaya Metallurgiya, No. 1(217), pp. 48–52, January, 1981.     

Paradigms and expectations: the nature of research and diagnostics

OBJECTIVES: Our purpose was to evaluate the long-term benefit of myocardial viability assessment for stratifying risk and selecting patients with low ejection fraction for coronary artery bypass grafting and to determine the relation between the severity of anginal symptoms, the amount of ischemic myocardium, and clinical outcome. METHODS: We studied 93 consecutive patients with severe coronary artery disease and low ejection fraction (median, 25%) who underwent positron emission tomography to delineate the extent of perfusion-metabolism mismatch (reflecting hibernating myocardium) for potential myocardial revascularization. Median follow-up was 4 years (range, 0 to 6.2 years). RESULTS: Fifty patients received medical therapy, and 43 patients underwent bypass grafting. In Cox survival models, heart failure class, prior myocardial infarction, and positron emission tomographic mismatch were the best predictors of survival. Patients with positron emission tomographic mismatch receiving bypass grafting had improved 4-year survival compared with those on medical therapy (75% versus 30%; P =.007) and a significant improvement in angina and heart failure symptoms. In patients without positron emission tomographic mismatch, bypass grafting tended to improve survival and symptoms only in those patients with severe angina (100% versus 60%; P =.085), whereas no survival advantage was apparent in patients with minimal or no anginal symptoms (63% versus 52%; P =.462). CONCLUSIONS: Patients with low ejection fraction and evidence of viable myocardium by positron emission tomography have improved survival and symptoms with coronary bypass grafting compared with medical therapy. In patients without evidence of viability, survival and symptom improvement with bypass grafting are apparent only among those patients with severe angina.     

Early diagnosis of rapidly progressive glomerulonephritis

Functional neuroimaging with positron emission tomography previously demonstrated reduced caudate glucose metabolism in virtually all symptomatic patients with Huntington's disease (HD). Single-photon emission computed tomography studies of brain blood flow also have shown caudate abnormalities in patients with HD. The present study compared these two functional imaging modalities in 6 patients with HD who had been symptomatic for fewer than 5 years. All patients had significantly impaired caudate-thalamus and caudate-whole-slice glucose metabolism ratios as measured by positron emission tomography. However, only 3 had clearly abnormal caudate-thalamus activity ratios and 2 had clearly abnormal caudate-whole-slice ratios on single-photon emission computed tomography. These findings indicate that single-photon emission computed tomography imaging of caudate blood flow is a less sensitive indicator of caudate dysfunction in early HD than is positron emission tomography imaging of caudate glucose metabolism.     

A review of positron studies of the annealing of the cold worked state

This review will present examples of the application of positron annihilation to studies of cold work and annealing. For the most part the examples will not reveal new metallurgical factsper se, but rather will serve to introduce the metallurgist or materials specialist to a relatively new and possibly advantageous type of measurement which he (or she) may wish to apply to particular studies. The examples cited include ones from conventional cold rolling and annealing, oriented single crystal bending and subsequent polygonization, fatigue of ferrous and nonferrous materials, tensile work hardening of various grain size samples, electron radiation and annealing, shot peening, age hardening retardation by cold work and influence of the cold worked state upon hydrogen charging. The reader is referred to the preceeding article by Dr. K. G. Lynn for a more detailed explanation of the two positron techniques utilized in gathering the results described, namely positron lifetime measurements and Doppler broadening of the positron annihilation gamma ray energies. The author is indebted to the many former and current students and research associates whose work is to be described and who will be cited in the text at the appropriate times. This paper is based on a presentation made at a symposium on “Recovery Recrystallization and Grain Growth in Materials” held at the Chicago meeting of The Metallurgical Society of AIME, October 1977, under the sponsorship of the Physical Metallurgy Committee.     

Effects of strenuous exercise on serum myosin heavy chain fragments in male triathletes

The brewing yeast having glucoamylase activity was constructed by integrating glucoamylase cDNA from Asapergillus niger into the genome of brewing yeast B48. The integration was achieved by cotransformation of YEP type plasmid pKG1 carrying glucoamylase expression-secretion element and was verified by Southern blot analysis. The engineered yeast was stable, and the fermentation test demonstrated that the lower residual dextrin level was obtained compared with control strain B48. Thus the fermentation rate was raised to 80.5%. No alteration of growth and brewing properties was observed. Beer quality was judged to be good.     

Compliance with hormone replacement therapy in postmenopausal women. A comparative study

OBJECTIVE: To assess compliance with hormone replacement therapy in postmenopausal women. METHOD: Two groups were compared prospectively: 100 women who sought treatment for menopausal symptoms, and 82 women who had undergone a total abdominal hysterectomy with bilateral salpingo-oophorectomy and were using estrogen replacement therapy. RESULTS: Compliance rates after 6 months were 81.0% and 84.1% in the two groups, respectively, and after 12 months, 73.0% and 80.5%. CONCLUSIONS: The high rates are attributed to our investment in patient education of the benefits of treatment and repeated and close follow-up.     

Positron spectroscopy for materials characterization

One of the more active areas of research on materials involves the observation and characterization of defects. The discovery of positron localization in vacancy-type defects in solids in the 1960’s initiated a vast number of experimental and theoretical investigations which continue to this day. Traditional positron annihilation spectroscopic techniques, including lifetime studies, angular correlation, and Doppler broadening of annihilation radiation, are still being applied to new problems in the bulk properties of simple metals and their alloys. In addition, new techniques based on tunable sources of monoenergetic positron beams have, in the last five years, expanded the horizons to studies of surfaces, thin films, and interfaces. In the present paper, we briefly review these experimental techniques, illustrating them with some of the important accomplishments in the field. This paper is based on a presentation made in the symposium “Irradiation-Enhanced Materials Science and Engineering” presented as part of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25–29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD.     

Positron spectroscopy for materials characterization

One of the more active areas of research on materials involves the observation and characterization of defects. The discovery of positron localization in vacancy-type defects in solids in the 1960’s initiated a vast number of experimental and theoretical investigations which continue to this day. Traditional positron annihilation spectroscopic techniques, including lifetime studies, angular correlation, and Doppler broadening of annihilation radiation, are still being applied to new problems in the bulk properties of simple metals and their alloys. In addition, new techniques based on tunable sources of monoenergetic positron beams have, in the last five years, expanded the horizons to studies of surfaces, thin films, and interfaces. In the present paper, we briefly review these experimental techniques, illustrating them with some of the important accomplishments in the field. This paper is based on a presentation made in the symposium “Irradiation-Enhanced Materials Science and Engineering” presented as part of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25–29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD.     

Our experience in the surgery of otosclerosis

A retrospective study of 613 operations on 495 patients with otosclerosis was made in the Department of Otorhinolaryngology of Hospital General Universitario of Alicante between 1974 to 1992. The clinical-pathological characteristics of this series were studied. Statistical analysis of the results was made. The improvement in air-bone gap for conversational frequencies was 27 dB. Closure of the postoperative air-bone gap for conversational frequencies was 7.6 dB and the overall percentage of closure of this gap was 80.5%. Better auditory results were obtained with partial platinectomy than with stapedectomy. Nothing was inserted between the prosthesis and the vestibule, permitting a shorter, easier operation with no occurrence of perilympathic fistule.     

Liquid xenon scintillators for imaging of positron emitters

The current understanding of xenon scintillation physics is summarized and keyed to the use of xenon as a gamma-ray detector in medical radioisotope imaging systems. Liquid xenon has a short scintillation pulse (approximately 10(8) sec) and high gamma-ray absorption and scintillation efficiencies. The fast pulse may facilitate imaging in vivo distributions of hot positron sources and allow recovery of additional spatial information by time-of-flight techniques. We begin by describing our own study of the feasibility of making a practical positron scanning system, and consider the problems of scintillation decay time, linearity, efficiency, purity, and electricfield amplifcation. The prospects for a practical instrument are considered.     

Preparation of monoclonal antibodies against chicken liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase and their effects on enzyme activities

The identification of hibernating myocardium in patients with poor ventricular function has become increasingly important as investigators demonstrate an improvement in ventricular performance in patients with injured but viable myocardium who undergo surgical revascularization. Modifications of 201Tl redistribution protocols and rest/stress 99mTc-labeled hexakis-2-methoxy-2-methyl propylisonitrile perfusion studies continue to underestimate myocardial viability compared with resting 18F-labeled fluorodeoxyglucose (18FDG) positron emission tomography. The combined data from multiple investigators suggest that 18FDG single-photon emission computed tomography used in combination with cardiac perfusion agents, either sequentially or with simultaneous dual-isotope acquisition, may provide an acceptable alternative to positron emission tomographic imaging for the detection of hibernating myocardium.     

The influence of Li on the nucleation of defects of quenched AlLi alloys

The nucleation and kinetics of defects formed by quenching in two AlLi alloys having Li content of 1.7 and 3.74 at.%Li have been studied by positron annihilation spectroscopy. It has been found that the defect formation is sensitive to the aging time at the temperature from which the samples are quenched. This fact has been related to the Li loss experienced by the alloys aged at high temperature. The quenched-in defects have been identified as vacancy-Li clusters and dislocation loops. The latter are formed by the collapse of the Li-rich vacancy complexes and are very sensitive to the Li content; as a consequence, the loops are decorated by Li-rich zones and are revealed as very effective positron traps in comparison to the vacancy-Li complexes, giving rise to an enhanced trapping.     

Bile duct variations in partial liver transplantations from living-related donors

The aim of this paper was to present anatomic variations of bile ducts and their effect on the perioperative course of living-related donors in partial liver transplantations in children. Liver fragments for partial transplantation were harvested from 41 related donors. Segments II and III were harvested from 35 and segments II, III, and IV from 6 donors. During the procedure, cholangiography through cystic duct was performed revealing a normal anatomy of the bile ducts in 33 (80.5%) cases. The rest of the donors showed anatomic variations. There was only one case of complications related to the bile duct. The intraoperative diagnosis of anatomic variations allowed for safe partial liver harvesting.     

Comparative study on the assay for IgE antibodies specific for Chamaecyparis obtusa pollen between AlaSTAT and CAP-RAST

Titers of IgE antibody specific for the pollen of Chamaecyparis obtusa (C. obtusa) were determined by AlaSTAT and CAP-RAST in 221 patients with Japanese cedar pollinosis. IgE antibody to C. obtusa tested positive by CAP-RAST at a higher rate (80.5%) than by AlaSTAT (52.6%). The results obtained from the two assays were compared with those from intradermal skin test. CAP-RAST had a higher sensitivity than that of AlaSTAT. Because the two methods showed no differences in the determination of IgE antibody specific for Cryptomeria japonica, the above differences between AlaSTAT and CAP-RAST are surmised to be ascribable to the differences of C. obtusa antigen used in the both assays.