Aerodynamically Assisted Tip-Pen Direct Writing

Scaffolds require individual external shape and well-defined internal structure, which is of great importance for tissue engineering. Rapid prototyping (RP) uses layer-manufacturing strategies to create physical objects and has the advantage on scaffold fabrication. A new RP technology called aerodynamically assisted tip-pen direct writing was developed to construct the complex architectures. Compared with the traditional nozzle, the new nozzle has a micro-tip in the center of the micro-hole. The flow is determined by the gap between the micro-hole and micro-tip, which makes it practical for more accurate flow control. A highly accurate three-dimensional (3-D) micro-positioning system was employed with the new nozzle to deposit maltose structures. 3-D architectures had been made by this method, the width of fiber in which is about 120 μm. The results show that this method provides a possibility to construct 3-D scaffolds with tissue-scale features (i.e., 10-100 μm) without bad influence on the biological activities.     

论导座式升降脚手架选用及施工要点

简要介绍了高层建筑施工中的导座式升降脚手架的功能、形式、特点及工程应用，并结合南昌市某高层建筑的脚手架的施工，介绍了导座式升降脚手架的方案选择、施工工艺、架体的构造及安全措施，供广大工程技术人员参考。     

Effect of PLA Knitted Structure on the Mechanical Properties of Composite Vascular Scaffold

A new entire biodegradable scaffold has been developed which does not require precelluiarization before transplantation. This new kind of vascular scaffold prototype made from porous poly- e-caprolactone （PCL） membrane to provide three-dimensional environment for cell growth, and embedded with weft-knitted polylactic acid （PLA） fabric to support mechanics. The aim of this paper is to study the variation tendency of mechanical properties with the fabric spacing changing. The basic geometrical parameters were measured to characterize properties of the samples. The tensile and compressive elastic recovery of the samples were tested by the universal mechanical tester and radial compression apparatus, respectively. Both tensile and compressive properties enhanced when reducing the fabric spacing of the composite vascular scaffold.     

中学生物理前概念的成因及转化研究

前概念的普遍存在对中学生的物理学习既有积极的作用又有消极的影响.为把物理前概念转变为科学概念,论文在分析前概念的成因及其特点的基础上,提出了创设物理学习情境,引发认知冲突;因势利导,搭建"脚手架";建构概念图,强化科学概念等转化策略.     

关于染色体高层次结构的研究

染色体的高层次结构是个尚未解决的总是在已提出了级螺旋模型和骨架－－放射环模型得到了较多实验结果的支持，本文主要介绍了它们的研究进展。     

静电纺丝在组织工程支架材料制备中的应用

综述了静电纺丝的基本原理和过程参数,重点描述了静电纺丝及同轴共纺技术在组织工程支架材料领域的应用,最后对电纺技术在组织工程支架材料领域应用中存在的问题和面临的挑战进行了讨论.     

The odd couple: signal transduction and endocytosis

Cell surface receptors are used to transmit extracellular information. The activation of cell surface receptors initiates signal transduction and receptor endocytosis. Signal transduction and the endosomal transport of activated receptors require precise regulation. New concepts for the integration of endocytosis and signaling arise from recent findings that suggest bidirectional interplay of these two processes. This review discusses the following questions: (i) do activated cell surface receptors modify the endosomal system to promote internalization and endosomal traffic, and (ii) do internalized cell surface receptors use specifically localized signaling complexes to generate specific biological signals?     

复杂施工条件下,高层扣件式钢管脚手架的工程实践

介绍了以《建筑施工扣件式钢筋脚架安全技术规范》（JGJ130－2001）及其他规范、标准进行高层脚手架的设计、施工管理,在复杂施工条件下成功的方法和经验。     

Hcc-1 is a novel component of the nuclear matrix with growth inhibitory function

Hcc-1 is a novel nuclear protein containing the SAF-box DNA-binding domain. It binds to both double-stranded and single-stranded DNA with higher affinity for the single-stranded form. In addition, it also binds specifically to scaffold/matrix attachment region DNA. These nucleic acid-binding characteristics suggest a potential function for Hcc-1 as a component of the heterogeneous ribonucleoprotein complex. Using a yeast two-hybrid screen, two DEAD-box RNA helicases, BAT1 and DDX39, were identified as proteins that interact with Hcc-1. Interactions with these RNA helicases suggested a role for Hcc-1 in nucleic acid biogenesis. Expression of Hcc-1 in the HEK293 cell line resulted in a slower growth rate compared to controls (p = 0.0173) and an accumulation of cells at the G2/M phase (p = 0.0276 compared to control HEK293 cells). Taken together, these results suggest a role for Hcc-1 in growth regulation and nucleic acids metabolism.Received 13 May 2004; received after revision 30 June 2004; accepted 6 July 2004     

偏心荷载作用下扣件式钢管满堂支承体系承载性能研究

如何准确地对扣件式钢管满堂支承体系的稳定承载力进行计算是亟待解决的一个技术难题.现有的各种满堂支承体系承载力计算方法中,均没有考虑由于扣件的偏心连接而导致水平杆与立杆不在同一平面内的情况以及满堂脚手架通过水平杆将上部荷载偏心传递给立杆的影响(以上两种偏心情况统称为偏心荷载).在分析满堂支承体系结构特点的基础上,提出了考虑偏心荷载作用下的满堂支承体系数值计算模型.通过对大量不同搭设参数下的满堂支承体系分别进行是否考虑偏心荷载影响的非线性有限元模型分析及2个满堂脚手架的原型试验,证实了偏心荷载这一因素对扣件式钢管满堂支承体系承载性能的影响.所提出的计算模型合理、安全,可为今后满堂支撑架及满堂脚手架的设计提供有价值的参考.