用离子束技术研究稀磁半导体和纳米磁性材料

综述用离子束技术研究稀磁半导体和纳米磁性材料的构建、调控和改性的进展和现状。离子束注入是优选的构建和调控方法,测试结果表明在GaN和ZnO等新半导体光电材料中注入Mn、Ni和Co等过渡金属离子可得到低温和室温下的铁磁性。离子束分析技术给出这些新材料薄膜的微结构信息,透射电镜下观察到过饱和剂量Mn+注入GaN形成的纳米磁性颗粒。     

基于Visual Basic平台的钣金放样系统研究

本文介绍了基于Visual Basic平台的钣金放样系统,并以石油、化工行业广泛应用的直三通为例,全面系统的阐述了本软件系统的放样过程。经实践证明,本软件系统具有很好的稳定性、可靠性、准确性。     

消失模壳型铸造A356铸态和T6态铝合金的组织、性能及拉伸断口(英文)

对采用消失模壳型铸造制备的A356铝合金在铸态和T6热处理态下的微观组织、拉伸性能以及拉伸断口进行了研究,并与消失模铸造A356铝合金进行了对比分析。结果表明:消失模壳型铸造A356铝合金组织主要有α(Al)初生相、共晶硅相以及Mg2Si相组成。经过T6热处理后,共晶硅形貌更加球化,均匀地分布于晶界处;且共晶硅粒子的平均长度、宽度和长宽比都比铸态条件下的小。与消失模铸造相比,组织中的初生相和共晶硅相都明显细化。经T6处理后,消失模壳型铸造A356合金的力学性能得到明显提高,其中抗拉强度、延伸率和布氏硬度分别达到260.53MPa、6.15%和86.0,其与消失模铸造相比具有明显优势。此外,消失模壳型铸造A356铝合金拉伸断口为具有准解理面和韧窝形貌的混合断口,最终表现为穿晶断裂模式。而消失模铸造A356铝合金拉伸断口为明显的脆性断口。     

微波辐射干燥单水氢氧化锂的研究

本文研究了利用微波辐射干燥单水氢氧化铝的工艺，并分析了微波功率、辐射时间、物料重量和物料厚度对物料脱水率的影响。     

Ad-hING4联合~(125)I粒子对裸鼠胰腺癌移植瘤的抑癌增效作用

本工作探讨腺病毒介导的人ING4基因(Ad-hING4)联合~(125)I粒子对裸鼠胰腺癌移植瘤的抑癌增效作用及其可能的机制.将本室构建的Ad-hING4腺病毒感染QBI-293A细胞,扩增后获得高滴度的病毒.建立25只裸鼠胰腺癌PANC-1皮下移植瘤模型,分成PBS对照组、空病毒Ad组、~(125)I粒子近距离放疗组、Ad-hING4基因治疗组、~(125)I粒子和Ad-hING4联合治疗组,进行抑瘤治疗实验;此后每5天测量1次肿瘤体积,20天后处死,计算抑瘤率和金氏q值.常规病理切片观察细胞生长形态、组织损伤程度和范围,并进行凋亡细胞计数(AI);免疫组化SP法检测肿瘤标本中微血管密度(MVD)、生存素SurvⅣin和活化的Caspase-3凋亡相关蛋白的表达.结果发现, ~(125)I粒子组、Ad-hING4组、联合治疗组抑瘤率分别达到34.19%(P<0.01)、31.50%(P<0.01)、67.15%(P<0.01),联合治疗组抑瘤率明显高于~(125)I粒子和Ad-hING4治疗组(P<0.01);病理切片检查显示近粒子处肿瘤细胞变性坏死,远离粒子处可见存活肿瘤细胞;三个治疗组凋亡指数(AI)、Caspase-3阳性细胞数明显高于PBS组(P<0.05),且联合治疗组明显高于~(125)I粒子和Ad-hING4治疗组(P<0.01);三个治疗组MVD值、SurvⅣin阳性细胞明显低于PBS组(P<0.05),且联合治疗组明显低于~(125)I粒子和Ad-hING4治疗组(P<0.01);Ad组与PBS组的各指标无显著性差异(P>0.05).可见~(125)I粒子、Ad-hING4可显著抑制裸鼠PANC-1胰腺癌移植瘤的生长,两者联用具有抑癌增效的协同作用,Ad-hING4有望作为一种新的放疗增敏剂;其抑瘤机制可能是通过下调SurvⅣin和上调Caspase3的表达,以诱导肿瘤细胞凋亡、抑制肿瘤血管形成.     

电磁逆散射成像的一种混合正则化方法

电磁逆散射成像问题数值求解中,非线性逆散射方程及其对应的离散方程组具有明显的不适定性,针对求解通常所用Tikhonov正则化方法的参数选择在先验选取时缺乏有效的误差信息,而后验选取时需要更多计算量求解有关参数的方程的困难,本文中将小参数Tikhonov正则化方法与共轭梯度法结合,提出了不适定方程组的混合正则化方法。数据仿真表明,该方法既可保证正则化效果,也减少了计算量。     

Primary osteogenic sarcoma of the breast: a clinicopathologic analysis of 50 cases

Extraskeletal osteosarcomas are rare. Few primary mammary osteosarcomas have been reported; many of these have been described in association with a biphasic tumor. Fifty pure osteosarcomas of the breast, diagnosed between 1957 and 1995, were reviewed after excluding those of biphasic origin. The absence of epithelial differentiation was confirmed using a panel of immunohistochemical markers in 32 cases and using ultrastructural evaluation in an additional four cases. Tumors occurred in 49 women and one man; age ranged from 27 to 89 years (median, 64.5 years). One patient received radiotherapy for ipsilateral breast carcinoma 9 years before presentation. Patients were treated by excisional biopsy (n = 13), tylectomy (n = 5) or mastectomy (n = 32). All axillary nodes, dissected in 20 patients, were free of tumor. One patient had extramammary spread at diagnosis. The neoplasms were 1.4 cm to 13.0 cm (mean, 4.6 cm), and 60% were grossly circumscribed. Tumors were classified as fibroblastic (n = 28), osteoclastic (n = 14), or osteoblastic (n = 8). Of 39 patients with available follow-up information, locally recurrent (n = 11) and metastatic (n = 15) disease developed in 23 (59%) at a mean of 10.5 and 14.5 months from diagnosis. Eight (73%) patients in whom local recurrence developed were treated with excisional biopsy or tylectomy; of these, seven had a positive margin. Sixteen (41%) patients died of disease at a mean of 17.1 months, within 20 months of onset of metastases, most commonly to the lung. Mammary osteosarcomas are aggressive tumors with a propensity for blood-borne rather than lymphatic spread. Total excision without axillary dissection is advised.     

Weight loss in Alzheimer's disease: an international review of the literature

Alzheimer's disease affects an estimated 2 million elderly in the U.S. and challenges primary care physicians to assist caregivers in dealing with the daily management of these patients. To support the clinical observation of weight loss in Alzheimer patients despite adequate food intake, we reviewed the existing literature. To date, eight international studies have focused on nutrition in Alzheimer's disease and all have found weight loss. It is not clear whether this weight loss is a component of or a consequence of the disease. These findings suggest systemic, metabolic alterations in Alzheimer's disease. They require further investigation as to their nature and as to their appropriate recognition and management to retard the deteriorating effects of chronic weight loss and malnutrition. Finally, some reports lead to speculation that nutritional strategies may improve cognitive function.     

Decompression sickness in Ireland--a review

In the last decade there has been an increase in the incidence of decompression sickness in Ireland. The modern diver, equipped with specially developed diving equipment, is exposed to abnormal physiological conditions. This has resulted in a spectrum of medical conditions, which need to be recognised, diagnosed and treated. The department of Underwater Medicine at University College Hospital, Galway, is the only referral centre in the Republic of Ireland for patients suffering from decompression sickness. Early recognition and referral for treatment dramatically improves patient outcome. A one year's review of patients referred for treatment is presented.     

Finite-Element Modeling of Titanium Powder Densification

A powder-level, finite-element model is created to describe densification, as a function of applied stress during uniaxial hot pressing, of CP-Ti and Ti-6Al-4V powders with spherical or spheroidal shapes for various packing geometries. Two cases are considered: (1) isothermal densification (in the α- or β-fields of CP-Ti and in the β-field of Ti-6Al-4V) where power-law creep dominates and (2) thermal cycling densification (across the α/β-phase transformation of Ti-6Al-4V) where transformation mismatch plasticity controls deformation at low stresses. Reasonable agreement is achieved between numerical results and previously published experimental measurements and continuum modeling predictions.