Measuring Receptor/Ligand Interaction at the Single-Bond Level: Experimental and Interpretative Issues

There is increased interest in measuring kinetic rates, lifetimes, and rupture forces of single receptor/ligand bonds. Valuable insights have been obtained from previous experiments attempting such measurements. However, it remains difficult to know with sufficient certainty that single bonds were indeed measured. Using exemplifying data, evidence supporting single-bond observation is examined and caveats in the experimental design and data interpretation are identified. Critical issues preventing definitive proof and disproof of single-bond observation include complex binding schemes, multimeric interactions, clustering, and heterogeneous surfaces. It is concluded that no single criterion is sufficient to ensure that single bonds are actually observed. However, a cumulative body of evidence may provide reasonable confidence. 0 2002 Biomedical Engineering Society.

Rayleigh-Taylor Instability of a Liquid Drop at High Bond Numbers

给出了高Bond数下黏性液滴表面Rayleigh-Taylor线性不稳定性的分析解,这种不稳定性对于超音速气流作用下液滴破碎的早期阶段起着至关重要的作用.基于稳定性分析的结果,导出了用于估算稳定液滴的最大直径及液滴无量纲初始破碎时间的计算式,这些计算式与相关文献给出的实验和分析结果比较显示了良好的一致.

Stress reduction and bond stability during thermal annealing of tetrahedral amorphous carbon

A comprehensive study of the stress release and structural changes caused by postdeposition thermal annealing of tetrahedral amorphous carbon (ta-C) on Si has been carried out. Complete stress relief occurs at 600-700°C and is accompanied by minimal structural modifications, as indicated by electron energy loss spectroscopy, Raman spectroscopy, and optical gap measurements. Further annealing in vacuum converts sp3 sites to sp2 with a drastic change occurring after 1100°C. The field emitting behavior is substantially retained up to the complete stress relief, confirming that ta-C is a robust emitting material. © 1999 American Institute of Physics.

Low Spring Constant Regulates P-Selectin-Psgl-1 Bond Rupture

Forced dissociation of selectin-ligand bonds is crucial to such biological processes as leukocyte recruitment, thrombosis formation, and tumor metastasis. Although the bond rupture has been well known at high loading rate r(f) (>= 10(2) pN/s), defined as the product of spring constant k and retract velocity v, how the low r(f) (< 10(2) pN/s) or the low k regulates the bond dissociation remains unclear. Here an optical trap assay was used to quantify the bond rupture at r(f) <= 20 pN/s with low k (similar to 10(-3)-10(-2) pN/nm) when P-selectin and P-selectin glycoprotein ligand 1 (PSGL-1) were respectively coupled onto two glass microbeads. Our data indicated that the bond rupture force f retained the similar values when r(f) increased up to 20 pN/s. It was also found that f varied with different combinations of k and v even at the same r(f). The most probable force, f

Aquecimento global : George Leuzinger e um alerta fotográfico

Descreve, tomando por base uma fotografia de 1865, algumas iniciativas para preservação da natureza realizadas no Brasil durante o século XIX. Resume dados biográficos do suíço George Leuzinger, dando ênfase a preocupação ecológica desse fotógrafo. Afirma a necessidade de transformar o ser humano em "parasita do Bem", extraindo do planeta Terra o seu sustento, mas retribuindo com a correção dos malefícios feitos até agora.

Influence of buoyancy on floating-zone convection of small bond number

Gravity may influence the velocity and temperature distributions, bouyancy may induce Rayleigh instability and the instability may be excited due to the change of free surface shape associating with gravity in the thermocapillary convection. These effects have been studied in the present paper. The results show that gravity may have an important effect in thermocapillary oscillatory convection even for the cases of small Bond number experiments either on the ground or in space.

The influence of buoyancy on the oscillatory thermocapillary convection with small bond number

This work is an experimental study of unidirectional bamboo-epoxy laminates of varying laminae number, in which tensile, compressive, flexural and interlaminar shear properties are evaluated. Further, the disposition of bamboo fibre, the parenchymatous tissue, and the resin matrix under different loading conditions are examined. Our results show that the specific strength and specific modulus of bamboo-epoxy laminates are adequate, the former being 3 to 4 times that of mild steel. Its mechanical properties are generally comparable to those of ordinary glass-fibre composites. The fracture behaviour of bamboo-epoxy under different loading conditions were observed using both acoustic emission techniques and scanning electron microscopy. The fracture mode varied with load, the fracture mechanism being similar to glass and carbon reinforced composites. Microstructural analyses revealed that natural bamboo is eligibly a fibre composite in itself; its inclusion in a plastic matrix will help solve the problems of cracking due to desiccation and bioerosion caused by insect pests. Furthermore, the thickness and shape of the composite can be tailored during fabrication to meet specific requirements, thereby enabling a wide spectrum of applications.

One possible way to promote the bond-selective chemical-reactions by frequency-modulated lasers

It is proposed in this paper that we can use frequency-modulated (FM) lasers to realize bond-selective chemical reactions or to raise the efficiency of molecular isotope separation. Examples are given for HF molecule and the C–H bond in some hydrocarbons.

História do movimento político, que no anno de 1842 teve lugar na provincia de Minas Geraes

José Antonio Marinho nasceu em Minas Gerais, em 1803, e morreu no Rio de Janeiro, em 1853. Em 1823, de passagem pela Bahia, envolveu-se nas lutas políticas daquele ano. Seguiu depois para Pernambuco, onde tomou parte, em 1824, na Confederação do Equador. Entrou para o Seminário de Olinda, mas denúncias de sua participação nos acontecimentos de 1824 impediram sua ordenação. Voltou, então, para Minas Gerais e conseguiu concluir sua formação sacerdotal. Ordenado em 1829, voltou às lides políticas, tornando-se advogado, jornalista e deputado provincial. Em 1836m elegeu-se deputado-geral por Minas Gerais, em 1842, tomou parte na Revolução Liberal, da qual foi primeiro historiador. Apesar de ter participado dos acontecimentos que historiou, tendo sido, por isso, acusado de parcial, o autor primou “pela verdade da exposição dos fatos”, como disse o Barão Homem de Melo. Com a autoridade de historiador da Revolução Liberal de 1842, Aluísio de Almeida afirmou que, sem a Historia do movimento politico, que no anno de 1842 teve lugar na Provincia de Minas Geraes, seria impossível escrever sobre aquele movimento. Obra rara, valorizada por treze litografias, que Aluísio de Almeida considera, com razão, “preciosas” : nove retratos, quatro vistas e uma planta, estas desdobradas. As litografias do primeiro volume se constituem de retratos do autor e de J. Feliciano, J. P. Dias de Carvalho e T. B. Ottoni, vistas da Praça de Barbacena, da Vila de Queluz e do Arraial da Lagoa Santa e planta do Arraial de Santa Luzia e suas imediações; e as do segundo volume de retratos de R. T. d’Aguiar, D.J. C. de Mendonça Franco, J. G. Teixeira de Carvalho, Diogo Antônio Feijó e Manuel Alves Branco e vista de Sabará.

Collecção das Leis do Imperio do Brasil de 1842

Parte 1 - Decisões