Single-Molecule DNA Analysis Reveals That Yeast Hop1 Protein Promotes DNA Folding and Synapsis: Implications for Condensation of Meiotic Chromosomes

During meiosis, long-range interaction between homologous chromosomes is thought to be crucial for homology recognition, exchange of DNA strands, and production of normal haploid gametes. However, little is known about the identity of the proteins involved and the actual molecular mechanism(s) by which chromosomes recognize and recombine with their appropriate homologous partners. Single-molecule analyses have the potential to provide insights into our understanding of this fascinating and long-standing question. Using atomic force microscopy and magnetic tweezers techniques, we discovered that Hop1 protein, a key structural component of Saccharomyces cerevisiae synaptonemal complex, exhibits the ability to bridge noncontiguous DNA segments into intramolecular stem-loop structures in which the DNA segments appear to be fully synapsed within the filamentous protein stems. Additional evidence suggests that Hop1 folds DNA into rigid protein DNA filaments and higher-order nucleoprotein structures. Importantly, Hop1 promotes robust intra- and intermolecular synapsis between double-stranded DNA molecules, suggesting that juxtaposition of DNA sequences may assist in strand exchange between homologues by recombination-associated proteins. Finally, the evidence from ensemble experiments is consistent with the notion that Hop1 causes rigidification of DNA molecules. These results provide the first direct evidence for long-range protein-mediated DNA DNA synapsis, independent of crossover recombination, which is presumed to occur during meiotic recombination.

Sharp tips from crumples and capillary bridges

We describe two techniques to create sharp tips. The first involves the buckling of thin metal films deposited on soft, stretchable substrates. The second involves the formation of narrow necked capillary bridges.

Multicomponent self-sorting of a Pd-7 molecular boat and its use in catalytic Knoevenagel condensation

Unique three-component self-assembly of a cis-blocked 90 degrees Pd(II) acceptor with amixture of tri- and tetra-imidazole donors led to the self-sorting of a Pd-7 molecular boat with an internal nanocavity, which catalyses the Knoevenagel condensation of a series of aromatic aldehydes with 1,3-dimethylbarbituric acid and Meldrum's acid in aqueous media.

An Easy Access to Benzofurans via DBU Induced Condensation Reaction of Active 2-Hydroxy Acetophenones with Phenacyl Chlorides: A Novel Class of Antioxidant Agents

A convenient and efficient one-pot synthesis of benzofurans 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, 3l, 3m, 3n, 3o, 3p, 3q, 3r, 3s, 3t has been described from 2-hydroxy acetophenones and phenacyl chlorides in the presence of DBU. The procedure was applicable for a variety of phenacyl chlorides and provides a variety of benzofurans with higher yields. DBU acts as a base and as well as nucleophiles. All the derivatives were subjected to in vitro antioxidant screenings against representative 2,2-diphenyl-1-picryl-hydrazyl and 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radicals and results worth for further investigations.

Evaporation-Condensation Synthesis and Optical Property of In(2)O(3)Octahedrons

Synthesis of In2O3 octahedrons is carried out successfully by heating Indium metal pieces in air ambient. The sample is characterized by scanning electron microscopy (SEM), Energy dispersive X-ray spectroscope (EDS), X-ray diffraction (XRD) and Raman spectroscopy. The as-prepared In2O3 octahedrons are highly crystalline and exhibit body centered cubic structure. Room temperature and temperature (293-453K) dependence photoluminescence reveals a deep levelbroad emission of yellowish-orange spectra centered around 605 nm. The emission is due to the presence of defect levels in the band gap of materials.

Experimental study on evaporation of pentane from a heated capillary slot

An experimental investigation of evaporation of a pentane meniscus from a heated capillary slot is presented. A novel aspect of this study is that both the wicking height and steady state evaporation mass flow rate are measured simultaneously. Based on a macroscopic force balance, the apparent contact angle of the evaporating meniscus is experimentally estimated from the wicking height and mass flow rate. This is compared with the results obtained using evaporating thin-film theory. The experimentally estimated contact angle is slightly larger than that obtained from the thin-film model but both show similar trends. Further, it is found that the reduction in the meniscus height is primarily due to an increase in the apparent contact angle. The liquid and vapor pressure drops in the capillary are insignificant relative to the capillary pressure. (C) 2015 Elsevier Ltd. All rights reserved.

两层流体热毛细对流空间实验研究=Space Experiments of Thermo Capillary Convection in Two-liquid Layers

1999年,在我国实践5号卫星上完成了两层流体空间实验,实验研究两层不相混合流体的纯Marangoni对流（温度梯度与界面垂直）与热毛细对流（温度梯度方向与流体界面平行）.前者存在发生Marangoni对流的最小临界温差值△Tc,低于该值流体系统处于静止状态;后者中只要存在沿界面的温度梯度便会产生热毛细对流.空间实验采用石蜡和氟化液两层流体新体系,实现了平整的液-液交界面,并从卫星上传回上万幅数字图像.通过多幅图像叠加处理得到了定量的流速场.数值模拟计算分析了相应工况时对流流动的速度场,两者的流场结构和速度大小基本一致,实验验证了理论模型.

Capillary Effect on Vertically Excited Surface Wave in Circular Cylindrical Vessel

In a vertically oscillating circular cylindrical container, singular perturbation theory of two-time scale expansions was developed in inviscid fluids to investigate the motion of single free surface standing wave including the effect of surface tension.

Characters of Surface Deformation and Surface Wave in Thermal Capillary Convection

In the field of fluid mechanics, free surface phenomena is one of the most important physical processes. In the present research work, the surface deformation and surface wave caused by temperature difference of sidewalls in a rectangular cavity have been investigated. The horizontal cross-section of the container is 52 mmx42 mm, and there is a silicon oil layer of height 3.5 mm in the experimental cavity. Temperature difference between the two side walls of the cavity is increased gradually, and the flow on the liquid layer will develop from stable convection to un-stable convection. An optical diagnostic system consisting of a modified Michelson interferometer and image processor has been developed for study of the surface deformation and surface wave of thermal capillary convection. The Fourier transformation method is used to interferometer fringe analysis. The quantitative results of surface deformation and surface wave have been calculated from a serial of the interference fringe patterns.The characters of surface deformation and surface wave have been obtained. They are related with temperature gradient and surface tension. Surface deformation is fluctuant with time, which shows the character of surface wave. The cycle period of the wave is 4.8 s, and the amplitudes are from 0 to 0.55 mu m. The phase of the wave near the cool side of the cavity is opposite and correlative to that near the hot side. The present experiment proves that the surface wave of thermal capillary convection exists on liquid free surface, and it is wrapped in surface deformation.

The Optical Methods on Measuring Surface Deformation and Surface Wave in The Thermal Capillary Convection

An optical diagnostic system consisting of the Michelson interferometer with the image processor has been developed for the study of the kinetics of the thermal capillary convection. The capillary convection, surface deformation, surface wave and the velocity field in a rectangular cavity with different temperature's sidewalls have been investigated by optical interference method and PIV technique. In order to calculate the surface deformation from the interference fringe, Fourier transformation is used to grating analysis. The quantitative results of the surface deformation and surface wave have been calculated from the interference fringe pattern.

Influence of surfactant solubility on the deformation and breakup of a bubble or capillary jet in a viscous fluid

In a previous study [M. Hameed, J. Fluid Mech. 594, 307 (2008)] the authors investigated the influence of insoluble surfactant on the evolution of a stretched, inviscid bubble surrounded by a viscous fluid via direct numerical simulation of the Navier-Stokes equations, and showed that the presence of surfactant can cause the bubble to contract and form a quasisteady slender thread connecting parent bubbles, instead of proceeding directly toward pinch-off as occurs for a surfactant-free bubble. Insoluble surfactant significantly retards pinch-off and the thread is stabilized by a balance between internal pressure and reduced capillary pressure due to a high concentration of surfactant that develops during the initial stage of contraction. In the present study we investigate the influence of surfactant solubility on thread formation. The adsorption-desorption kinetics for solubility is in the diffusion controlled regime. A long-wave model for the evolution of a capillary jet is also studied in the Stokes flow limit, and shows dynamics that are similar to those of the evolving bubble. With soluble surfactant, depending on parameter values, a slender thread forms but can pinch-off later due to exchange of surfactant between the interface and exterior bulk flow. © 2009 American Institute of Physics.

The Capillary Force In Micro- And Nano-Indentation With Different Indenter Shapes

The influence of the indenter shapes and various parameters on the magnitude of the capillary force is studied on the basis of models describing the wet adhesion of indenters and substrates joined by liquid bridges. In the former, we consider several shapes, such as conical, spherical and truncated conical one with a spherical end. In the latter, the effects of the contact angle, the radius of the wetting circle, the volume of the liquid bridge, the environmental humidity, the gap between the indenter and the substrate, the conical angle, the radius of the spherical indenter, the opening angle of the spherical end in the truncated conical indenter are included. The meniscus of the bridge is described using a circular approximation, which is reasonable under some conditions. Different dependences of the capillary force on the indenter shapes and the geometric parameters are observed. The results can be applicable to the micro- and nano-indentation experiments. It shows that the measured hardness is underestimated due to the effect of the capillary force. (c) 2008 Elsevier Ltd. All rights reserved.

Note on the instability of capillary jet with thermocapillarity

In this paper, we examine a new basic state of long axisymmetric liquid zone, subjected to axial temperature gradients which induce steady viscous flow driven by thermocapillarity. Axial velocity 1/4S-1/2R(B) of liquid zone connects pulling velocity of single crystal. The stability of liquid zone with pulling velocity 1/4S-1/2R(B) to small axisymmetric disturbance is examined The eigenvalue problems on the stability are derived. A special case (eta = 0) is discussed.

An application of adjoint variational method to the capillary instability in liquid

In this paper, applying the direct variational approach of first-order approximation to the capillary instability problem for the eases of rotating liquid column, toroid and films on both sides of cylinder, we have obtained the necessary and sufficient conditions for motion stability of the "cylindrical coreliquid-liquid-cylindrical shell" systems. The results obtained before are found to be special cases of the present investigation. At the same time, we have explained physical essence of rotating instability and settled a few disputes in previous investigations.

Experimental Study the Flow Pattern in Thermal Capillary Convection

In the present research work, the thermal capillary convection has been investigated and measured by particle image velocimetry (PIV) technique. There is one liquid layer in a rectangular cavity with different temperature’s sidewalls. The cavity is 52mm,42mm,20mm, 4mm in height of the silicon oil liquid layer. A sidewall of the cavity is heated by electro-thermal film, another sidewall is cooled by the semiconductor cooling sheet. The velocity field and the stream lines in cross section in liquid layer have been obtained at different temperature difference. The present experiment demonstrates that the pattern of the convection mainly relates with temperature difference.