An in-situ study of static recrystallization in Mg using high temperature EBSD

It has been a common method to improve the mechanical properties of metals by manipulating their microstructures via static recrystallization,i.e.,through heat treatment.Therefore,the knowledge of recrystallization and grain growth is critical to the success of the technique.In the present work,by using in-situ high temperature EBSD,the mechanisms that control recrystallization and grain growth of an extruded pure Mg were studied.The experimental results revealed that the grains of priority for dynamic recrystallization exhibit fading competitiveness under static recrystallization.It is also found that grain boundary movement or grain growth is likely to show an inverse energy gradient effect,i.e.,low energy grains tend to swallow or grow into high energy grains,and grain boundaries of close to 30°exhibit superior growth advantage to others.Another finding is that{10-12}tensile twin boundaries are sites of hardly observed for recrystallization,and are finally swallowed by adjacent recrystallized grains.The above findings may give comprehensive insights of static recrystallization and grain growth of Mg,and may guide the design of advanced materials processing in microstructural engineering.

Simulation of Stable Crack Growth for Welded Joints Including Strength Mismatching

A 3-D computational method to simulate stable growth of a macroscopic crack under model condition is described in this paper. The Gurson-Tvergaard plasticity model for voided materials describes the damage process. Fixed-sized, computational cell elements (containing voids) defined over a thin layer at the crack plane simulate the ductile crack extension. Outside of this layer, the material remains undamaged by the void growth, follows the conventional J2 flow theory. The micromechanics parameters controlling crack growth are D, the thickness of computational cell layer and f(0), the initial void porosity. Calibration of these parameters proceeds through analyses of ductile tearing to match R-curve obtained from testing of deep notch bend specimens for welded joints. The effect of the strength mismatching on ductile crack growth for welded joints is simulated also.

一种肺泡毛细血管发育不良伴十二指肠反常扩张的十二指肠闭锁的新合并症

Background/purpose The authors experienced 3 cases of persistent pulmonary hyp ertension of the neonate (PPHN)-associated with duodenal atresia with paradoxic al dilatation of the distal blind end of the duodenum. The aim of this study was to clarify the characteristics of this novel association. Methods The medical c harts of the patients were reviewed retrospectively. Results Case 1 was a 2, 862 -g male infant with a prenatal diagnosis of duodenal atresia. The dilated intes tine was identified as the distal blind end of the duodenum during duodeno-duod enostomy. PPHN developed after surgery, and the patient died despite treatment w ith inhaled nitric oxide (iNO) and extracorporeal membrane oxygenation (ECMO). L ung biopsy results showed alveolar capillary dysplasia (ACD) with misalignment o f pulmonary vessels. Case 2 was a 2, 244-g female infant with duodenal atresia. Surgery could not be performed because of refractory PPHN, which resulted in de ath. Autopsy results showed ACD with misalignment of pulmonary vessels and duode nal atresia associated with dilatation of the distal blind end. Case 3 was a 2, 462-g female infant with a prenatal diagnosis of duodenal atresia associated wi th dilatation of the distal blind end. Enlarged echogenic fetal lungs were noted antenatally. PPHN developed after surgery, and she was extubated successfully u nder combined therapy with iNO and intravenous prostacyclin. Unfortunately, she finally died of refractory PPHN. A retrospective review of the prenatal ultrason ographic findings showed enlarged echogenic fetal lungs as in the first 2 cases. Conclusions The characteristics of this novel association are enlarged echogeni c fetal lungs, duodenal atresia associated with paradoxical dilatation of the di stal blind end, and refractory PPHN resistant to iNO.

老年急性心肌梗死患者梗死相关动脉侧支循环减少

Objectives The purpose of this study was to investigate the hypothesis that ci rculation via collateral vessels to an infarctrelated artery (IRA) is impaired w ith aging in patients with acute myocardial infarction (AMI). Background Animal experiments have shown that advanced age blunts the development of new vessels i n response to angiogenic cytokines. Methods Of 3,573 consecutive patients with A MI, 1,934 patients who fulfilled the following criteria were enrolled in this st udy: 1) coronary angiograms were obtained within 72 h after the onset of AMI; an d 2) IRA showed complete occlusion (Thrombolysis In Myocardial Infarction <<TIMI>> flow grade 0 or 1). Collaterals to the IRA were angiographically evaluated usin g the Rentrop score. Rentrop scores 1 to 3 were defined as demonstrating significant collaterals. Results The prevalence of collaterals decreased with age, from 47.9%, 45.8%, 43.4%, to 34.0%in patients < 50 years, 50 to 59 year s, 60 to 69 years, ≥70 years, respectively (p < 0.001). Advanced age was an ind ependent factor predicting the absence of collateral circulation to the IRA. In contrast, time to catheterization, history of angina pectoris, and preinfarction angina were independent predictors for the presence of collaterals. Multivariat e analysis showed that the absence of collaterals was an independent predictor o f in-hospital mortality in elderly patients ≥70 years (odds ratio, 15.6; 95%c onfidence interval, 3.5 to 69.6), although this finding was not significant in p atients < 70 years. Conclusions Advanced age is associated with decreased angiog raphic presence of collaterals to the IRA in patients with AMI. This abnormality may contribute to the poor prognosis of elderly patients with AMI.

动脉注射5-氟尿嘧啶联合皮下注射α干扰素治疗晚期肝癌可导致间质性肺炎

Previously we reported combined chemoimmunotherapy, using interferon (IFN) αand 5-fluorouracil (5-FU) for patients with advanced hepatocellular carcinoma (HCC), and this regimen improved the prognosis. Recently, we experienced an HCC patient who died of severe interstitial pneumonia during the combined IFN αand 5-FU therapy. This is the first report of the occurrence of interstitial pneumonia during combined IFN αand 5-FU treatment. A 60-year old man was admitted to Osaka University Hospital to receive systemic chemo immunotherapy for recurrent HCC. In the second week of the chemo immunotherapy, he showed a decreased level of consciousness, and respiratory insufficiency. Emergency roentgenogram revealed diffuse infiltration in both lungs. Respiratory dysfunction due to interstitial pneumonia was suspected, and steroid pulse therapy was started. However, the patient showed respiratory failure, and he died 32 days after the start of the therapy. Autopsy findings showed atelectasis in the bilateral lungs, which showed elastic hard solidity and a dark red color; esophageal varices were also shown, and there was cirrhosis with a large tumor in the liver. Microscopically, the alveolar wall showed marked fibrous thickness and moderate inflammatory change, which is consistent with acute interstitial pneumonia, and the acute pulmonary change was suspected to have been the cause of death. The association of IFN with the development of interstitial pneumonia has been reported. However, the prognosis of IFN induced interstitial pneumonia has mostly been favorable when the medication was discontinued. It has been postulated that interstitial pneumonia induced by the combination of IFN and 5-FU may be therapy resistant. The combination of IFN αand 5-FU is a useful therapy for patients with advanced HCC, such as that with portal vein invasion or multiple metastatic foci. Thus, interstitial pneumonia in these patients should be carefully managed.

Effect of Elastic Energy due to Atomic Size Factor on Ordering and Decomposition Behaviour of Binary Solid Solutions

A theory recently developed by the present authors is applied to the study of the effect of elastic energy due to atomic size factor on the transformation behaviour of binary solid solutions. It is found that elastic interaction energy (EIE), which is a part of the total elastic energy, plays a key role in both ordering elastic interaction ordering (EIO) and spinodal decomposition. The present study gives a reasonable explanation to the historical dilemmas, ''elastic energy paradox'' and ''atomic size factor paradox''. By solving these confusing problems, the coexistence of ordering (EIO) and decomposition, which has been regarded as impossible by conventional theories, can be well understood. The mechanism is as follows: lowering of elastic energy demands EIO, and such an ordering provides a driving force for spinodal decomposition. Therefore, in alloys with large atomic size factor, spinodal decomposition is preceded and induced by ordering. Ordering and spinodal decomposition are thus closely related processes to each other.

Elastic Energy and Elastic Interaction Ordering of Binary Solid Solutions

A theory in the framework of continuum elasticity has been developed to calculate the total contribution of ''atomic size effect'' or ''strain energy effect'' to free energy of binary solid solutions. It is found that elastic free energy consists of two parts: elastic self energy (ESE), and elastic interaction energy(EIE). The former is a function of composition alone, the latter is also a function of atomic configuration. Minimization of total elastic free energy with respect to atomic arrangement results in an ordered arrangement of atoms, which is called elastic interaction ordering (EIO), as it originates from elastic interaction among atoms. EIO is a kind of local ordering within a ''characteristic range'', and it is found to be important in determining the state of solid solutions and structures of superlattices. The present theory also gives good explanation to the coexistence of ordering and decomposition which can not be understood in conventional theories.

Origin of Ordering Coupled Tweed Microstructures in Alloys with Large Atomic Size Factors

A theoretical study is developed on the evolution and mechanism of an ordering coupled phase separation, and on the origin of a resultant tweed microstructure. It is found that long-range elastic interaction among atoms with different atomic sizes plays a key role in the phase separation, and that the evolution of the phase separation is very similar to that of conventional spinodal decomposition except that the separation is dependent on an elastic interaction ordering (EIO). This ''EIO coupled spinodal decomposition'' is shown to exhibit a periodical or tweed microstructure being accompanied by an EIO. It is also found that a large atomic size factor yields a large positive contribution of EIO to spinodal decomposition. Generally, it is thermodynamically and kinetically favorable for the EIO to precede the onset of spinodal decomposition, though the former is not separable from the latter as a whole. We suggest that an initially disordered solid solution undergoes an EIO first, and then the partially ordered solid solution starts to decompose via a spinodal mechanism. Solute-enriched regions increase their degree of order along with an increase in solute content, and solute-depleted regions decrease their degree of order together with a decrease of solute content. The final microstructure is characterized by a periodical array of highly ordered solute-enriched regions and nearly disordered solute-depleted regions. The notion of EIO coupled spinodal decomposition is in general agreement with the transformation behaviour of a large number of alloy systems.

A NEW BICOUMARIN FROM PLEUROSPERMUM RIVULORUM (DIELS)

From the BtOAc extract of the underground parts of Pleurospermum rivulorum (Diels), a new bicoumarin, rivulobirin was isolated along with eight known furocoumarins.

苯丙氨酸呼吸试验测定苯丙氨酸羟化酶(PAH)活性能诊断四氢生物蝶呤敏感性PAH缺乏

四氢生物蝶呤(BH4)敏感性苯丙氨酸羟化酶(PAH) 缺乏的特点是,在BH4负荷试验后,患者血中的苯丙氨酸水平降低。大多数BH4敏感性PAH缺陷的患者都有轻度的苯丙酮尿症(PKU)和轻度的高苯丙氨酸血症(HPA),但并非所有轻度PKU患者对BH4敏感。笔者所做的苯丙氨酸呼吸试验是一种确定BH4敏感性的可靠方法。苯丙氨酸呼吸试验定量测定从L-[1-13C]苯丙氨酸到13CO2(羟苯丙氨酸)的转化。

PNAS:科学家发现新的精子运动调节器

南京医科大学生殖医学国家重点实验室、基础医学院组织胚胎学系刘明兮课题组与贝勒医学院MartinM．Matzuk课题组、大阪大学MasahitoIkawa课题组等共同解析了一个精子运动调节基因TCTE1，结果发表于《美国科学院院刊》（PNAs）。

Experimental platform for the investigation of magnetized-reverse-shock dynamics in the context of POLAR

The influence of a strong external magnetic field on the collimation of a high Mach number plasma flow and its collision with a solid obstacle is investigated experimentally and numerically. The laser irradiation （I - 2 × 10^14 W. cm-2） of a multilayer target generates a shock wave that produces a rear side plasma expanding flow. Immersed in a homogeneous 10 T external magnetic field, this plasma flow propagates in vacuum and impacts an obstacle located a few mm from the main target. A reverse shock is then formed with typical velocities of the order of 15-20 4- 5 km/s. The experimental results are compared with 2D radiative magnetohydrodynamic simulations using the FLASH code. This platform allows investigating the dynamics of reverse shock, mimicking the processes occurring in a cataclysmic variable of polar type.