Deformation of drops in extensional viscoelastic flow

The deformation of nylon drops in polyethylene, with and without an interfacial agent, in an extensional flow has been studied. The presence of an interfacial agent reduces the size of the dispersed phase, and the deformation of the drop is reduced. An analysis is given, which accurately predicts the deformation for all values of the capillary number considered. The predicted and observed shapes are, however, only in agreement at low values of capillary number. Possible causes for this discrepancy are discussed. © 1996 John Wiley & Sons, Inc.     

Crack Initiation in Perforated Propellants under high strain rate impact conditions

The fracture behaviour of gun propellant grains during impact has been measured on a modified Hopkinson Bar which uses a projectile as the input bar. Evidence for the detection of initial minor crack formation in seven-perforated cylindrical specimens of single base, double base and triple base propellant is presented. Under compressive load (pressurization rates of 100 GPa/s-200 GPa/s), minor crack formation does not immediately result in large scale crack propagation or fragmentation of the specimens. The single base and triple base propellant are equally more resistant to crack initiation than the double base propellant when tested in either the end-on or side-on modes. Implications for munition survivability are discussed in terms of mechanical frictional effects caused during compressive loading of cracked propellant or compressive heating in propellant cracks during the ballistic cycle.     

结构有限元模型部分设计参数型修正方法

讨论了结构有限元分析模型部分设计参数型的修正方法，提出了一种利用非完备实测模态参数修正有限元分析模型的迭代修正方法，即振型自由度的扩充在每次迭代中进行，有效地改善了因振型自由度扩充引起的误差，被修正的参数为结构设计参数，所获模型的物理意义十分明确，并与动态设计相适应．实例表明，该方法修正效果良好．     

Synthesis and Properties of a Novel Intumescent Flame Retardant (IFR) and Its Application in Halogen-Free Flame Retardant Ethylene Propylene Diene Terpolymer (EPDM)

The PDP, a novel intumescent flame retardant (IFR) with high charred residue of 40.8% in N2 at 700°C by TGA was synthesized successfully for preparing halogen-free flame-retardant EPDM composites. The UL-94 V-0 rating was achieved for EPDM composites with 20 phrs carbon black at the same time by using only 60 phrs PDP. In situ FTIR spectroscopy reveals that P–N rich charred residues are formed through the interaction between hydrogen atom in weak base of P–NH–C and phosphate. SEM characterizes the formation of intumescent chars during burning. The mechanical properties of composites are also discussed.     

Magnetic-separable robust microbeads using a branched polymer for stable enzyme immobilization

Uniform magnetic separable robust microbeads using a branched polymer were successfully developed for stable enzyme immobilization. The changed morphology of the microbeads was shown by scanning electron microscopy (SEM) analysis. The aldehyde groups on the polymers and imine groups derived from the Schiff base reaction between the aldehyde and amine moiety were found as the evidence of these reactions based on Fourier transform infrared (FT-IR) spectroscopy. The amine groups of the enzyme react with the aldehyde groups on the glutaraldehyde polymer so that the stable conjugations are formed. The specific activity of the conjugated enzyme was found to be retained more than 50%, but the reaction rate constant, K_m value was not changed, compared to the free enzyme. In addition, the enzyme conjugated in the microbeads was found to be highly stable for more than 50 days, pertaining over 60% of its initial activity, even after being reused more than 15 times repeatedly. Furthermore, the magnetic-driven controllability provided facile separable characters for the repeated recycling. It is expected that these microbeads can be utilized as a key tool for successful realization not only in enzymatic conversion processes but also in extended fields; bio-based sensors or analytical devices, bioprocessing, bioremediation, to name only a few of numerous areas.     

多孔陶瓷的制备和性能研究

选用普通陶瓷原料粉为主要原料，适当添加造孔剂(有机细粉碳黑)和高温活性剂，制备出一种性能优良的多孔陶瓷。通过扫描电镜及性能测试分析，探讨了多孔陶瓷的微观结构及性能的影响因数。     

Engineering a pharmacologically superior form of leptin for the treatment of obesity

Leptin plays a central role in the homeostasis of body weight through its regulatory effects on appetite and energy expenditure, yet in trials as a therapeutic agent for the treatment of obesity in humans it has been disappointing. The poor clinical efficacy of leptin results from its short circulating half-life, low potency and poor solubility, necessitating large and frequent doses to obtain even modest clinical benefit. Engineered Fc-leptin immunofusins, consisting of the Fc fragment of an immunoglobulin gamma chain followed by leptin, exhibit improved pharmacological properties with very consistent and potent biological activities. Furthermore, in extending the circulating half-life of the protein in vivo from a few minutes for leptin to many hours for Fc-leptin, these proteins have the potential to reduce drastically the dosage and frequency of administration required to obtain clinical benefit. The results of this study show that the engineered leptin immunofusins described here have significantly enhanced pharmacological properties in comparison with the recombinant leptin that was used in clinical trials. As such, they could represent an important step towards a therapeutically superior form of leptin if the disappointing performance of leptin in early clinical trials was due to its poor pharmacological properties rather than any conceptual weakness in the strategy of using leptin for the treatment of obesity and its related disorders.