Table of Content - JFBI 2.3

The most important parameters characterizing thermophysiological comfort of sport and protective garments are thermal resistance, water vapour permeability and air permeability. Contrary to common textiles, protective and functional garments and some technical textiles like textile dressings are also used in wet state, which affects their comfort properties. However, common measuring instruments mostly do not enable reliable measurement of wet fabrics, due to long time of measurement, during which the fabrics get dry. In this paper two fast measuring PC evaluated instruments ALAMBETA and PERMETEST commercial instruments are described, which provide reliable non-destructive measurement of thermal conductivity, thermal resistance and water vapour permeability of fabrics in dry and wet state. By means of these instruments, thermal resistance and water vapour permeability of heavy cotton and cotton/PES woven fabrics in wet state were experimentally determined and results were discussed. The effect of structure and composition on the above-mentioned properties of these fabrics has been investigated as well. Some surprising results were achieved: with increasing fabrics humidity, the air permeability almost linearly decreased, whereas the total cooling heat flow (due to water evaporation from the wet fabric surface) slowly increased.

Through the comparison and analysis of the angiogenesis conditions for different pathophysiologic states, such as growing process of the animal, tumor growth, and wound repair, an index of the hypoxia intensity is proposed to evaluate the environment of angiogenesis, based on which the mechanism of the angiogenesis patterns under different environment is discussed. A new concept of response effect is deduced for describing the reaction of the endothelial cell (EC)s towards the VEGF concentration in the microenvironment during the angiogenesis, and an explanation for different angiogenesis patterns of capillaries is given. At the same time the biological proofs cited from recent studies are provided to prove the response effect of the EC. With the results we try to show that in the pathophysiologic environment with high hypoxia intensity, the angiogenesis comes into being mainly by sprouting; while the hypoxia intensity is low, the angiogenesis mainly occurs through the intussusception. This concept shall offer a new basis and idea for the study of the capillary network construction, related clinical therapy, and induction of vascularization in the biomaterials.

This paper reports the study of rheological properties of the urea denatured soybean protein in concentrations of 10 % after 0 mol L-1 ～ 10 mol L-1 urea treatment using a programmable control revolving viscometer (Brookfield RVDV-II+/SSA-SCL27). A theoretical foundation is provided in this paper to study the exploitation and application of soybean protein. The results show that after urea denaturation the soybean protein solution was a typical pseudoplastic fluid while before it was a Bingham character fluid. The viscosity of both decreased with shear rates and increased with urea contents. The change was much obvious at the urea concentration of 4 mol L-1～6 mol L-1. After urea denaturation, the non-Newtonian index of soybean protein solution increased from 0.17 to 0.3 ~ 0.4 at 20°C, which was still fairly low. The stabitily of fluids was pretty bad. The viscosity dropped with temperature significantly.

A cross-linked porous silk fibroin (SF) material was prepared by freeze-drying. 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), N- hydroxysuccinimide (NHS) and 2-morpholinoethanesulfonic acid (MES) were added in different concentrations of SF solutions. The mixed solution was poured into aluminum vessels to make a layer of about 2 mm thickness. Then they were frozen for 6 h at -80, -50, -20 and -10 ìC, respectively, and lyophilized. After 36 h porous silk fibroin materials were obtained. Compared to the uncross-linked porous SF materials, cross-linked materials show an obvious decrease in water solubility, indicating that effective cross-linking reaction took place in silk fibroin. The results of FT-IR and Raman spectra show that EDC reacted with the carboxyl of SF, mediating acyl isourea or acid anhydride formation. The resultant acid anhydride may readily react with amino groups of SF to yield amide bonds. The influence of freezing temperature and concentration of the silk fibroin solution on the structure and properties of materials was also investigated. The porous SF materials, with average pore size 32.0-332.5 μm and porosity 59.7%- 90.9%, could be prepared by freeze-drying. Thicker solution and lower freezing temperature resulted in smaller pore size and porosity.

A series of novel type temperature and pH responsive hydrogels were synthesized by using hydroxypropylcellulose (HPC) as temperature sensitivity material and sodium alginate (SA) as pH sensitivity material. The effect of SA on lower critical solution temperature (LCST) has been studied and the influence mechanism is presented. In addition, the swelling ratio and control factors of swelling process are all researched in this paper. The main results obtained are as follows: the LCST of HPC/SA hydrogel decreased gradually as SA was added into HPC; this kind of hydrogel responded temperature and pH being double-sensitive; the swelling ratio reached the maximum value at pH of 6.

The strain rate sensitivity of Oxygen plasma treated Nano Silicon Dioxide particles sol-gel coated Vectran and concurrent microstructural evolution was investigated. Both the materials are strain rate sensitive and the change in index parameter of strain rate sensitivity with strain reflects the change in micromechanisms of deformation and modes of fracture. Helium plasma can reduce the surface energy of vectran fiber. Oxygen plasma and nano SiO2 particles will enhance the surface energy.. The activation volumes rise with Oxygen. Although either Helium or Oxygen has made the activation volumes exceed that of the neat Vectran, the SiO2 nano-particle makes the activation volume rise rapidly.

There are two major camouflage protections in modern military tactics: the UV-protection and the near infrared camouflage. However, not all natural and composite dyestuffs provide the mentioned properties. In this study, green leaves were chosen as the simulating object, and the camouflage properties of cotton dyed with Lithospermum were evaluated. It was observed that the dyed cotton fabric had good UV-protection and near-infrared camouflage properties. The UV- protection effect was strongly dependent on the absorption characteristics of Lithospermum of UV radiation. The near infrared camouflage effect was mainly dependent on the reflection spectrum characteristics of Lithospermum in the near infrared waveband.

In this study, poly(lactic acid) (PLA) and silk fibroin(SF)-gelatin were sequentially electrospun on the collector to prepare the PLA/SF-gelatin composite fiber membranes. Scanning electronic microscope (SEM) was used to observe the morphology of the membranes. The microstructure of the fiber membranes before and after treatment with methanol was characterized using Fourier transform infrared (FTIR) and differential thermal analysis (DTA), and then the effects of the microstructure change on the mechanical properties, dissolution rate and shrinkage were evaluated. Furthermore, SEM and MTT assays were preformed to assess the proliferation and adhesion of 3T3 mouse fibroblasts cultured on the PLA/SF-gelatin scaffolds. After chemical treatment with methanol, the findings suggested the microstructure of PLA fiber did not change obviously, whereas the β-sheets of SF and α-helix structures of gelatin in SF-gelatin blend nanofibers increased, consequently the diameter of electrospun PLA/SF- gelatin membranes, the dissolution rate declined by 64%, the strain at break electrospun PLA/SF-gelatin scaffolds, the shrinkage of the PLA/SF –gelatin composite scaffolds caused by chemical treatment decreased by 40%. The cells adhered on to the surface of blend layer fibers and formed a confluent monolayer after 12 days cultivation. The good mechanical properties and dimensional stability of the chemically treated PLA/SF -gelatin scaffolds, combined with the ability to support cell growth in vitro, suggested tremendous potential application in tissue engineering.

Puerarin particles were prepared in the process of solution-enhanced dispersion by supercritical CO2 (SEDS), where the dichloromethane was employed as an organic non-solvent to increase the saturation ratio of the initial puerarin solution in ethanol. A 23 factorial experiment was designed to investigate and identify the relative significance of the processing parameters on the yield of puerarin. In the range of the parameters studied, the yield increased with an increasing non-solvent/solvent ratio, and decreasing puerarin concentration or flow rate. The anti-oxidative activities of puerarin prepared under different parameters were also investigated, and the results show that there is no significant difference. The results indicate that the SEDS process combined with non-solvent could produce puerarin nanoparticles with a higher yield.

Based on the Hook’s law for infinitesimal strains and Newton’s law for infinitesimal rates of strain, the creep property of vortex spun yarn is studied by generalized Maxwell model connected in a row to a Hook’s spring. The results show that this model can effectively explain the creep property of vortex spun yarn. For different creep test conditions, firstly, the creep elongation increases sharply with the prolongation of creep time, and then slows down after a constant elongation period. The maximal creep elongation after being stressed by a constant force value increases with the increase of the elongation rate. When the tensile level is higher, the maximal elongation is larger under a constant elongation rate. Moreover, the maximal creep elongation is larger for a finer vortex spun yarn.