Evolution of microstructure and formation mechanism of Nd-Fe-B nanoparticles prepared by low energy consumption chemical method

Nd₂Fe₁₄B nanoparticles were successfully prepared by using a low-energy chemical method. The microscopic characteristics and formation mechanisms of the phases were investigated at each stage during the preparation of Nd-Fe-B nanoparticles. The Nd-Fe-B intermediates, Nd-Fe-B oxides and reduced Nd-Fe-B nanoparticles were detected and analyzed by using TEM, STEM, XRD, SEM, VSM and Rietveld calculations. The results showed that the intermediate of Nd-Fe-B consisted of Fe₃O₄ and Nd and Fe elements surrounded by nitrile organic compounds. The Nd-Fe-B oxide was composed of NdFeO₃ (48.619 wt%), NdBO₃ (31.480 wt%) and α-Fe (19.901 wt%), which was formed by the reaction among Nd, Fe₃O₄ and B₂O₃. NdFeO₃ and NdBO₃ exhibited a perovskite-like lamellar structure, and the grain size was smaller than that of α-Fe. Nd-Fe-B particles were mainly composed of Nd₂Fe₁₄B and α-Fe phases. The small particles of NdFeO₃ and NdBO₃ and the interstitial position between oxide particles and α-Fe were more favorable for the formation of Nd₂Fe₁₄B particles. At the same time, the surface of α-Fe particles can also diffuse to form Nd₂Fe₁₄B nanoparticles. The coercivity of Nd-Fe-B particles was 5.79 kOe and the saturation magnetization was 63.135 emu g⁻¹.

The Nd-Fe-B intermediate was successfully prepared by using a low-energy chemical method.     

Effect of Copper Sulfate and Sulfuric Acid on Blind Hole Filling of HDI Circuit Boards by Electroplating

Here, in a certain high density interconnect (HDI) printed circuit board, the effect of copper sulfate and sulfuric acid on the filling effect of a blind hole with a certain diameter and depth was investigated by making a blind hole using a CO₂ laser drilling machine, filling the blind hole via electroplating by simulating the electroplating line in a Halin cell, and observing the cross-section of a micro blind hole after polishing using metallographic microscope, as well as the effect of hole filling, are evaluated. The results show that, under the conditions of a certain plating solution formula and electroplating parameters (current density and electroplating time), the sag degree decreases with the increase in the copper sulfate concentration. When the concentration of copper sulfate increases from 210 g/L to 225 g/L, the filling effect is good and the sag degree is about 0. However, with the increase in sulfuric acid concentration, the sag increases gradually. When the sulfuric acid concentration is 25–35 g/L, both the sag and copper coating thickness are in a small range. Under appropriate electroplating conditions, a better blind hole filling effect can be obtained. The volume of blind hole has a certain effect on the diffusion and exchange of copper sulfate and sulfuric acid, as well as on the concentration distribution of additives.     

Experimental Investigation of Integrated Circular Triple-Wire Pulse GMAW of Q960E High-Strength Steel for Construction Machinery

Multi-wire welding has received much attention in the machinery industry due to its high efficiency. The aim of this study was to investigate a novel pulse gas metal arc welding (GMAW) that has circular triple-wire electrodes. The effect of the pulse phage angle on arc stability was particularly studied. Research showed that for typical phase angles the arc stability from low to high is 180°, 0°, and 120°, and the arcs are very stable at 120°. The triple-wire welding was used to weld a 9 mm thick Q960E steel, which is typically used for the arm of construction machinery. When the welding heat input was controlled at 1.26–1.56 kJ/mm, the weld zone was dominated by acicular ferrite, and the coarse-grained zone of the heat-affected zone was a mixed structure of lath martensite and lath bainite. The tensile strength of the welded joint reached 85% of the base metal and the impact toughness was above 62 J, which can meet the requirements of construction machinery. This indicates that the triple-wire welding has great potential to achieve efficient and high-quality welding for the construction machinery.     

Vaso-cutaneous fistula after vasectomy

Vaso-cutaneous fistulae occur rarely after vasectomy. We report three cases encountered in our hospital over the last 18 years and recommend technical considerations to avoid this complication.     

猪囊尾蚴刷状缘结构的冷冻蚀刻研究

应用透射电镜观察了猪囊尾蚴经冷冻蚀刻技术制备样品的刷状缘结构,尤其虫体的膜构造及膜内颗粒,并对皮层及焰细胞构造作了详细的描述。头节微毛分为两个部分,粗的微毛基部与细的棘样尖端,微毛基部PF面具有膜内颗粒,棘样尖端的4个膜面均很光滑,未见颗粒。微毛断面观可见微毛纤丝,呈颗粒状,不规则的分布于微毛基质之中。在实质层中靠近肌层处很易见到实质细胞、钙质小体及焰细胞。焰细胞由焰细胞体、焰细胞纤毛束及漏斗样滤管三部分组成。     

A 5-year surveillance of sensitivity in vivo of Plasmodium falciparum to pyronaridine/sulfadoxine/pyrimethamine in Diaoluo area, Hainan Province

The surveillance of sensitivity of P. falciparum to pyronaridine/sulfadoxine/pyrimethamine has been carried out in Diaoluo area in Hainan Province where chloroquine-resistant falciparum malaria is endemic, covering an area of 406 square kilometers, with a population of 3745 in 1986. From 1986 all outpatients diagnosed as falciparum malaria were administered with PND/S/P as the only antimalarial. In vivo sensitivity of P. falciparum was measured in some patients who were treated in hospital. It was demonstrated that P. falciparum in the Diaoluo area has retained its sensitivity to a single oral dose of PND/S/P of 500/1,000/50 mg with 100% cure rate for at least 5 years.     

Comparison of peginterferon and interferon in treating Chinese patients with chronic hepatitis C

BACKGROUND/AIMS: Higher virological and biochemical response rates were obtained in many clinical trials in Caucasian patients with chronic hepatitis C (CHC) after treating with peginterferon than in those with interferon. However, it is not clear whether this conclusion can be extrapolated to patients with Chinese ethnic origin and which type of peginterferon or interferon was more effective in treating Chinese CHC patients? The aim of this study was to perform a meta-analysis of randomized controlled trials (RCT) and compare peginterferon with interferon in treating Chinese patients with CHC. METHODOLOGY: The outcome measures were virological response (end-of-treatment virological response (ETVR) and sustained virological response (SVR)). Biochemical response (end-of-treatment biochemical response (ETBR) and sustained biochemical response (SBR) were also introduced as supplement to the evaluation on effect of peginterferon and interferon in treating Chinese patients with CHC. The measure of association employed was relative risk (RR) calculated by the random-effect model, with heterogeneity, sensitivity and subgroup analyses. RESULTS: Of the 110 studies screened, 5 RCTs including 499 patients (peginterferon 258, interferon 241) were analyzed. SVR and SBR obtained in patients treated with peginterferon were significantly higher than patients treated with interferon (60% vs. 35.53%, RR, 1.95; 95% confidence interval (CI), 1.17-3.24; p<0.05; 57.30% vs. 40.38%, RR, 1.36; 95% CI, 1.08-1.71; p<0.05), but the difference is not evident in ETVR and ETBR. In the subgroup analyses, ETVR and SVR obtained in patients treated with peginterferon alpha-2a (79.75% and 48.1%) were significantly higher than with interferon alpha-2a (35.37% vs. 19.05%, RR, 2.51; 95% CI, 1.74-3.63; p<0.05), but the difference is not evident between peginterferon alpha-2b and interferon alpha-2b. SBR obtained with peginterferon was also significantly higher than with interferon (57.3% vs. 40.38%, RR, 1.36; 95% CI, 1.08-1.71; p<0.05), but the difference is not evident in EBVR. Higher SVR were obtained in genotype 1 Chinese patients treated with peginterferon compared with those treated with interferon (48.45% vs. 23.24%, RR, 2.00; 95% CI, 1.48-2.7; p<0.01), but the ETVR were similar. The effects of peginterferon and interferon in genotype non-1 patients were also similar. Higher ETVR and SVR were obtained in patients treated with peginterferon alpha-2b compared with those treated with peginterferon alpha-2a (97.56% vs. 79.75% and 82.93% vs. 56.96%; p<0.05 and p<0.01, respectively). SVR obtained in patients treated with peginterferon alpha-2b were significantly higher than those treated with peginterferon alpha-2a (73.53% vs. 41.73%, p<0.01) in treating genotype 1 Chinese patients, but the superiority didn't appear in treating genotype non-1 patients. CONCLUSIONS: Both peginterferon alpha-2a and peginterferon alpha-2b might be recommended for Chinese ethnic original patients with CHC. Peginterferon alpha-2b might be more effective, with an expected relative higher virological response and biochemical response, in treating Chinese CHC patients.     

The use of noninvasive methods in the evaluation of left ventricular performance in coronary artery disease. I. Relation of systolic time intervals to angiographic assessment of coronary artery disease severity.

Determination of left ventricular performance by external STI was evaluated in 113 patients with possible coronary artery disease undergoing selective coronary artery disease undergoing selective coronary arteriography and left ventriculography. Angiographically determined significant coronary artery disease was considered as 70 per cent obstruction of a coronary vessel. PEPI and PEP/LVET increased with increasing severity of coronary artery disease. LVETI decreased with increasing coronary artery involvement. Presence of prior myocardial infarction or clinically apparent congestive heart failure did not significantly alter mean STI values when groups were compared according to severity of coronary artery disease. LVETI was significantly less for patients with three-vessel coronary artery disease than for those with no significant disease; PEPI and PEP/LVET were significantly greater in those with two- or three-vessel disease than in those without significant disease. Angiographically determined LVEF correlated directly with LVETI and inversely with PEPI and PEP/LVET. Abnormal left ventricular wall motion was associated with decreased LVETI and increased PEPI and PEP/LVET. LVEDP was not significantly different in any of the groups. These findings indicate that externally determined systolic time intervals reflect abnormalities in left ventricular performance which in turn appear more pronounced with increasingly extensive coronary artery disease.