Detection of mitochondrial DNA mutations using temporal temperature gradient gel electrophoresis

Mitochondrial disorders are a group of clinically and genetically heterogeneous diseases. Common recurrent mitochondrial DNA (mtDNA) point mutations account for the molecular defects of a small proportion of patients. In order to identify mtDNA mutations, comprehensive mutational analysis of the entire mitochondrial genome is necessary. We developed the temporal temperature gradient gel electrophoresis (TTGE) method to screen for mutations in mtDNA. The entire mitochondrial genome was amplified using 32 pairs of overlapping primers followed by TTGE analysis of the DNA fragments. TTGE method was first validated on 200 DNA fragments containing known mutations or polymorphisms. On TTGE, homoplasmic nucleotide substitutions show a single band shift and heteroplasmic mutations show multiple banding patterns. The known mutations or polymorphisms were correctly identified. TTGE was then used to screen for unknown mutations in the mitochondrial genome. DNA banding patterns, deviated from wild-type, suggestive of either homoplasmic or heteroplasmic mutations, were followed by direct DNA sequencing to identify the mutations. Numerous mutations and polymorphisms were detected. The results demonstrated that TTGE detects and distinguishes heteroplasmic mutations from homoplasmic polymorphisms. It also detects heteroplasmic changes in the background of a homoplasmic polymorphism. Overall, TTGE was proven to be a simple, rapid, sensitive, and effective mutation detection method.     

A three-layer structure model for the effect of a soft middle layer on Love waves propagating in layered piezoelectric systems

A three-layer structure model is proposed for investigating the effect of a soft elastic middle layer on the propagation behavior of Love waves in piezoelectric layered systems, with "soft" implying that the bulk-shear-wave velocity of the middle layer is smaller than that of the upper sensitive layer. Dispersion equations are obtained for unelectroded and traction-free upper surfaces which, in the limit, can be reduced to those for classical Love waves. Systematic parametric studies are subsequently carried out to quantify the effects of the soft middle layer upon Love wave propagation, including its thickness, mass density, dielectric constant and elastic coefficient. It is demonstrated that whilst the thickness and elastic coefficient of the middle layer affect significantly Love wave propagation, its mass density and dielectric constant have negligible influence. On condition that both the thickness and elastic coefficient of the middle layer are vanishingly small so that it degenerates into an imperfectly bonded interface, the three-layer model is also employed to investigate the influence of imperfect interfaces on Love waves propagating in piezoelectric layer/elastic substrate systems. Upon comparing with the predictions obtained by employing the traditional shear-lag model, the present three-layer structure model is found to be more accurate as it avoids the unrealistic displacement discontinuity across imperfectly bonded interfaces assumed by the shearlag model, especially for long waves when the piezoelectric layer is relatively thin.     

国产数字化电源控制器在SSRF直线电源上的应用

该国产数字化电源控制器采用先进的DSF和FPGA作为控制核心,采用了高精度的ADC作为数据采集单元,并且将模拟量和数字量进行有效的隔离,设计了较为先进的PID控制算法.控制器由DSP和ADC两块控制卡组?嵌入电源,和电源有机地融成一体.控制器通过光纤与远程IOC进行实时通讯,通过本地PC机串行口可灵活调节电源回路参数,具有高稳定性和高重复性等优点.迄今为止该控制器作为进口瑞士PSI控制卡的替换产品,主要应用在SSRF的静态的中小功率开关电源上(100ppm下),各项指标均能满足使用要求.与进口控制器相比,该控制器有较高的性价比.     

Investigation of the influence mechanisms of resin matrices on the strength of filamentary structures

The interrelationship between the burst strength of fiber-wound pressure vessels and resin properties has been investigated. Experimental results show that the effect of resin properties of the burst strength can be as large as 20–35 percent. Delamination occurring in the head region of a pressure vessel is identified as the main cause leading to the burst strength degradation, with help of the improved netting analysis. A special FORTRAN program is then developed to incorporate the spacial axisymmetric finite strain FEM approach, and the foregoing presupposition is further confirmed by numerical calculations. Interlaminar shear stresses are found to be the major cause in prompting the observed delaminations. It is argued then that the interlaminar shear strength (ILSS) of a composite should be considered as a fundamental parameter for vessel design and resin selection. Hydrostatic burst test results of glass fiber-wound pressure vessels correlate satisfactorily with this prediction. The best stress equilibrium coefficientK, being closely related to ILSS, is proposed as a proper criterion for resin matrix screening.     

声波在二维固/流声子晶体中的禁带特性研究

采用时域有限差分法(FDTD),分析了声波在二维四方点阵铝/空气组合声子晶体中的禁带特性,并利用实验测试验证了理论分析的正确性.在此基础上研究了两种不同声阻抗率比固(实心圆柱和空心圆管)/流系统声子晶体的禁带特性.对于实心圆柱体,分析了有限尺寸结构声子晶体在传播方向上的层数对声波传播特性的影响,得到了这两种系统在不同填充率下取得最大声波禁带宽度所需的最少层数.同时指出,在低声阻抗率比条件下,对于空心圆管填充物,通过选取适当的半径比,可以获得比实心柱体更宽的方向带隙.     

微穿孔蜂窝-波纹复合声学超材料吸声行为

民用及国防工业领域对工程材料结构提出了更高的应用需求.单一材料结构越来越难以满足实际应用需求,通过人工复合结构实现超常单一及多物理性能的超材料设计已经成为材料结构应用的重要发展方向.本文基于传统的蜂窝夹层结构,在其内部引入波纹结构,并在面板和波纹上分别进行微穿孔形成微穿孔蜂窝-波纹复合声学超材料,在其优异力学承载基础上,实现了低频段的宽频有效吸声降噪.应用微穿孔板吸声理论和声阻抗串并联理论,建立了微穿孔蜂窝-波纹复合声学超材料的吸声理论模型;发展了考虑黏热效应的声传播有限元模型,通过数值模拟验证了理论模型的准确性,并数值计算了声波在超材料微结构内的黏热能量耗散分布,发现超材料能量耗散主要集中于微穿孔处的黏性边界层;进一步开展了超材料吸声参数和尺度设计参数的分析讨论,阐明了不同尺度设计参数对超材料吸声性能的影响规律.本文工作对兼具力学承载与吸声降噪的新型材料结构设计有重要的理论指导价值.     

通孔金属泡沫表面的池沸腾实验研究

本文对烧结有厚度为30 mm的高孔隙率通孔铜泡沫的水平表面的池沸腾进行实验研究.并采用高速摄像仪对泡沫表面的汽泡生长形貌进行了可视化研究,研究了壁面过热度对热流密度、汽泡脱离直径、汽泡生长周期的影响关系.结果表明由于本文所研究的通孔泡沫厚度较大,限制了汽泡的脱离,使传热性能低于光表面,但是使沸腾起始点降低至3℃.     

Reactions of chromium(III) complexes with ferricyanide. Magnetism of K2[Cr(salen)(H2O)][Fe(CN)6]·H2O and the crystal structure of [trans-Cr(tn)2Cl2]3[Fe(CN)6]·6H2O [salen2− = N,N′-ethylenebis(salicylideneaminato) dianion,tn = 1,3-diaminopropane]

Two Cr^III–Fe^III complexes, K₂[Cr(salen)(H₂O)][Fe(CN)₆]·H₂O (1) and [trans-Cr(tn)₂Cl₂]₃[Fe(CN)₆]·6H₂O (2), have been prepared. Crystal structure determination shows that complex (2) possesses an ionic salt structure. General physical measurements and magnetic studies indicate that (1) assumes a cyanide-bridged dinuclear structure, and that the Cr^III–Fe^III magnetic coupling through the cyanide bridge is antiferromagnetic, which can be rationalized by the overlap of magnetic orbitals of the same symmetry.     

乙基紫-脱氧核糖核酸共振发光体系的研究及其分析应用

研究了碱性染料乙基紫与小牛胸腺脱氧核糖核酸(ctDNA)体系的结合反应及其共振发光光谱.在pH5.0～10.0范围内,乙基紫在595nm处有一特征吸收峰,加入DNA后,吸收峰消失,而在507nm处出现新的吸收峰,表明有新的结合物形成.在510nm处出现共振发光峰,其发光强度与DNA浓度呈线性关系,线性范围为0～500ng/mL;检出限(3σ)为1.54ng/mL.方法具有较高的灵敏度和准确度.将该体系用于核酸试样的测定,结果令人满意.     

辐射模型和弥散效应对多孔介质内燃烧影响的数值模拟

本文根据气固两相局部非热平衡假设,建立了甲烷/空气预混气在惰性多孔介质内的一维层流燃烧数学模型。分别采用附加导热、Rossland模型和二通量法模型求解固体能量方程中的辐射源项,研究了热辐射模型和弥散效应对多孔介质内燃烧火焰结构的影响。结果表明,多孔固体表面辐射的影响不可忽略,辐射模型对火焰温度的预测影响显著,而弥散效应对气体温度的分布及反应热影响则较小。