Stable Extracellular Matrix Protein Patterns Guide the Orientation of Osteoblast‐like Cells

The development of a simple method for creating extracellular‐matrix‐protein patterns by microcontact printing to guide cell organization and alignment is reported. Substrates of glass and titanium are modified by a hydrophilic chitosan layer and then protein patterns with varying shapes and sizes are printed onto the surfaces. Confocal laser scanning microscopy shows that proteins (collagen type I, fibronectin, and gelatin) are accurately and effectively transferred from the stamp templates. These patterns are stable. Osteoblast‐like cells cultured on these micropatterned materials preferentially adhere and grow on the protein‐functionalized areas. The cell morphology and distribution direction are dependent on the widths and spaces of the protein patterns. It is possible to control the cell alignment by carefully designing the pattern shapes and sizes. This study suggests that the stable protein patterns can be used to modify biomaterials' surfaces and spatially control the organization of bone cells. Due to the high stability, easy preparation procedure and the precise control of the cell alignment, the current work may provide opportunities for the surface modification of implantable materials, such as titanium for bone repair, where specific bone‐cell alignment is needed.     

A novel simultaneous noise and input VSWR matching technique for broadband LNA

The Simultaneous Noise and Input Voltage Standing Wave Ratio (VSWR) Matching (SNIM) condition for Low Noise Amplifier (LNA), in principle, can only be satisfied at a single frequency. In this paper, by analyzing the fundamental limitations of the narrowband SNIM technique for the broadband application, the authors present a broadband SNIM LNA systematic design technique. The designed LNA guided by the proposed methodology achieves 10 dB power gain with a low Noise Figure (NF) of 0.53 dB. Meanwhile, it provides wonderful input matching of 27 dB across the frequency range of 3∼5 GHz. Therefore, broadband SNIM is realized.     

关于求解二维三温热传导问题的一点探讨

本文首先给出了二维三温热传导问题的数学模型和有关数据,在单层三角形网格剖分下,讨论了牛顿和固结系数两种线性化方法,经典的和保对称的两种有限体离散方法,并获得了对比数值结果.     

Preparation of three‐dimensional structure controllable nanofibers by electrospinning

The size of “bowl‐like” structures woven by nanofibers could be controlled by adjusting the distance from the nozzle to a modified collector and the voltage applied to the electrospinning device. More interestingly, the nanofibers in the side wall of the “bowl” could vibrate up and down with the changing of the voltage. This voltage‐induced vibration might have potential applications for bio‐mimic process and micro‐motor devices. Copyright © 2008 John Wiley & Sons, Ltd.     

“Click” coupling between alkyne‐decorated multiwalled carbon nanotubes and reactive PDMA‐PNIPAM micelles

Covalent functionalization of alkyne‐decorated multiwalled carbon nanotubes (MWNTs) with a well‐defined, azide‐derivatized, thermoresponsive diblock copolymer, poly(N,N‐dimethylacrylamide)‐poly(N‐isopropylacrylamide) (PDMA‐PNIPAM) was accomplished by the Cu(I)‐catalyzed [3 + 2] Huisgen cycloaddition. It was found that this reaction could simultaneously increase the molecular size and bonding density of grafted polymers when PDMA‐PNIPAM micelles were employed in the coupling system. On the other hand, attachment of molecularly dissolved unimers of high‐molecular weight onto the nanotube resulted in low‐graft density. The block copolymer bearing azide groups at the PDMA end was prepared by reversible addition–fragmentation transfer polymerization, which formed micelles with a diameter of ～40 nm at temperatures above its critical micelle temperature. Scanning electron microscopy was utilized to demonstrate that the coupling reaction was successfully carried out between copolymer micelles and alkyne‐bearing MWNTs. FTIR spectroscopy was utilized to follow the introduction and consumption of alkyne groups on the MWNTs. Thermogravimetric analysis indicated that the functionalized MWNTs consisted of about 45% polymer. Transmission electron microscopy was utilized to image polymer‐functionalized MWNTs, showing relatively uniform polymer coatings present on the surface of nanotubes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7187–7199, 2008     

An exact solution of start-up flow for the fractional generalized Burgers’ fluid in a porous half-space

Modified Darcy’s law for fractional generalized Burgers’ fluid in a porous medium is introduced. The flow near a wall suddenly set in motion for a fractional generalized Burgers’ fluid in a porous half-space is investigated. The velocity of the flow is described by fractional partial differential equations. By using the Fourier sine transform and the fractional Laplace transform, an exact solution of the velocity distribution is obtained. Some previous and classical results can be recovered from our results, such as the velocity solutions of the Stokes’ first problem for viscous Newtonian, second grade, Maxwell, Oldroyd-B or Burgers’ fluids.     

波前畸变的弱激光参与的简并四波混频的理论研究

针对四波混频技术在军事上的应用，计算了经过大气畸变的弱激光参与的简并四波混频过程，得到了共轭反射率的表示式，讨论了反射光与信号光近似100％共轭所需的条件。     

智能大屏幕显示屏的设计与制作

本文对大屏幕电子显示屏提出了新的显示控制方法，有利于发挥单片机的功能和新的功能扩展。本设计特别适合于中小型显示屏的制作，具有成本低、修改画面内容改变方便等特点。     

Lattice, magnetic and transport properties in antiperovskite compounds

The temperature-dependent magnetization, lattice, and transport properties of Mn₃Sn_1−xGe_xC (0≤x≤0.5) compounds are systematically investigated. The Mn–Mn atomic distance decreases as Ge content is increased, and the transition temperature from ferromagnetic (or ferrimagnetic) to paramagnetic state decreases too. Mn₃SnC has a large magnetovolume effect (MVE). However, Ge-doping in Mn₃SnC gradually reduces the MVE, till the MVE disappears. Whether there is an abnormal lattice change or not, there always exists an anomalous increase in resistivity near the magnetic phase transition point with decreasing temperature.