MPO4 (M=Sc, Lu, Y) :Ti3+ 自旋哈密顿参量的理论研究

利用高阶微扰方法和完全对角化方法分别计算了MPO4 (M=Sc, Lu, Y) ：Ti3+的自旋哈密顿参量（g 因子 g// , g和超精细结构常数A//, A),两种方法的计算结果非常接近,并且均和实验值吻合的很好,这表明这两种方法都是研究过渡金属离子自旋哈密顿参量的有效方法。另外,还对所研究的三种不同材料的共价性和芯极化常数性质进行了讨论。     

In vitro bioactivity and cytocompatibility of porous scaffolds of bioactive borosilicate glasses

The bioactive borosilicate scaffolds （R2O-RO-B2O3-SiO2-P2O5） with four different contents of borate were fabricated by replication technique. The bioactivity, degradability and the cytotoxicity of the scaffolds were studied in this paper. The porosity of the scaffolds was found to be 73%-80%, and the pore size was in the range of 200-300 μm. The porous scaffolds immersed in 0.02 mol.L^-1 K2HPO4 solution were transformed into hydroxyapatite. And it is notable that the D-AIk-2B, D-AIk-3B-scaffolds were covered by hydroxyapatite layers after 7 h-immersion, which proved their high bioactivity. In the cell adhesion test, cells could be seen growing well on the scaffolds, showing stretched morphology and obvious pseudopodia, and only the high cumulative concentration of B ions released from the D-AIk-3B-scaffold samples had an inhibition effect on cell proliferation. But the inhibition effect could be alleviated by diluting the extract solution to a certain concentration （dilution ratio： 1：8）. Therefore, after suitable pretreatment, the porous borosilicate bioactive glass scaffold can be a desirable candidate for bone tissue engineering.     

网络形成体对重金属氧化物玻璃形成的影响

利用红外吸收光谱和喇曼散射光谱考察了PbO-Bi2O3-B2O3,PbO-Bi2O3-B2O3-SiO2及PbO-Bi2O3-P2O5系统中B3+,Si4+,P5+离子的配位状态,比较了不同玻璃形成体氧化物在重金属氧化物玻璃形成中的作用.研究结果表明在上述各系统重金属氧化物玻璃中,B3+,Si4+,P5+分别以孤立的[BO3]三角体、[SiO4]四面体及不带PO双键的[PO4]四面体形式存在;重金属氧化物玻璃的形成主要取决于[BO3]三角体、[SiO4]和[PO4]四面体的含量,这些氧多面体的作用是对Pb2+,Bi3+,O2-的积聚起阻隔作用,使之难以排列成晶格结构,从而形成非晶态玻璃.     

稀相喷动流化床的流动特性

根据玻璃纤维毡增强热塑性树脂基复合材料(GMT)制备新工艺特点,提出了稀相喷动流化床的操作方式。测量了床内颗粒速度分布,考察了操作条件、体系结构等因素对流化床流动特性的影响。结果表明：稀相喷流床中环隙区颗粒的下降速度比传统喷动床高出一个数量级;床内颗粒的喷动和输送的主要影响因素是喷动气,亦受到流化气、导向管、喷嘴内径的影响。另外对中试装置内物料的流动特性进行了研究,为工艺的开发、设计和操作提供理论依据。     

短SiC纤维增强玻璃陶瓷氧化行为的研究

文章研究了单向短切碳化硅纤维增强玻璃陶瓷复合材料的氧化行为。结果表明：复合材料氧化过程中氧的扩散与复合材料中气孔或纤维基体热匹配微裂纹有关,早期氧化造成碳化硅纤维－基体界面富碳层消失和非晶态ＳｉＯ２的形成,非晶态ＳｉＯ２向玻璃陶瓷基体的扩散形成纤维－基体的强结合,导致复合材料整体脆化,强度降低２。     

Ni-Fe-Zr-Si-B非晶合金的形成和热稳定性研究

通过旋铸急冷工艺在真空中制备出了(Ni0.75Fe0.25)78-xZrxSi10B12(x=1、3、5、8、10)合金带材,获得了镍基非晶合金.采用XRD、DTA等测试手段分析了该工艺制备的合金非晶条带,研究了Zr对该合金体系的非晶形成能力和热稳定性的影响.X射线衍射分析表明,该合金体系皆为完全非晶.Diamond TG/DAT差热分析仪对非晶薄带的热稳定性及其相关参数Tg、Tx、Tm等的测量分析表明,该合金系中(Ni0.75Fe0.25)70Zr8Si10B12的过冷液相区温度范围ΔTx达58.62 K,约化玻璃转变温度trg约为0.666,表明该合金具有较高的非晶形成能力和热稳定性.当Zr原子分数较小(x≤8)时,Zr的添加提高Tg、Tx,并扩大过冷液相区ΔTx,使合金的非晶形成能力和热稳定性增加;Zr原子分数较大(x>8)时,Zr的添加诱导富Zr-Ni和Zr-Fe的原子团的形成,这些原子团会成为均质形核的核心,降低合金的非晶形成能力和热稳定性.     

Rheological behavior of mammalian cells

Rheological properties of living cells determine how cells interact with their mechanical microenvironment and influence their physiological functions. Numerous experimental studies have show that mechanical contractile stress borne by the cytoskeleton and weak power-law viscoelasticity are governing principles of cell rheology, and that the controlling physics is at the level of integrative cytoskeletal lattice properties. Based on these observations, two concepts have emerged as leading models of cytoskeletal mechanics. One is the tensegrity model, which explains the role of the contractile stress in cytoskeletal mechanics, and the other is the soft glass rheology model, which explains the weak power-law viscoelasticity of cells. While these two models are conceptually disparate, the phenomena that they describe are often closely associated in living cells for reasons that are largely unknown. In this review, we discuss current understanding of cell rheology by emphasizing the underlying biophysical mechanism and critically evaluating the existing rheological models. Received 25 May 2008; received after revision 19 June 2008; accepted 1 July 2008     

从物理发现到成功应用——兼谈2007年度诺贝尔物理学奖授予巨磁电阻效应发现者

法国科学家Albert Fert和德国科学家Peter Grünberg因发现巨磁电阻效应(GMR)而获得2007年度诺贝尔物理学奖。通过介绍他们的突出贡献及该领域的其他相关重要工作,梳理了近20年时间里,巨磁电阻效应和隧穿磁电阻效应(TMR)从物理发现到人工制备和优化多种纳米磁性多层膜、磁性隧道结(MTJ)材料,以及被成功应用于计算机磁读头、磁随机存储器和多种磁敏传感器的发展历程,展现了该领域现阶段有重要应用前景的一些热点课题。     

原子自旋进动检测技术

自旋是原子的内禀特性,自旋进动对磁场作用或相对惯性空间的转动敏感,通过检测原子的自旋进动可实现磁场或惯性转动的测量,进而形成原子磁强计、原子陀螺和其他原子传感器.基于原子无自旋交换弛豫(spin-exchange relaxation free,SERF)态的原子传感技术包括原子SERF态制备和原子自旋进动检测,其中原...     

光学玻璃荧光光谱测试与分析

通过测试玻璃样品的荧光光谱,分析和判断出玻璃产生荧光的原因,提出了解决的办法,并指出该玻璃可能产生荧光的波长。