Zr基块体非晶合金在过冷液相区的超塑性流变行为

研究了Zr41.25Ti13.75Ni10Cul2．5Be22.5(原子分数,%)块体非晶合金在玻璃转变终了温度Tg^end附近的4个特征温度点(616，636，656和676K)的等温拉伸行为．结果表明,块体非晶合金的超塑性能与环境温度及拉伸速度紧密相关．在656K，以5mm／min的速度拉伸时，获得了1625％的最大延伸率利用速度突变法测出了636，656及676K时的应力敏感指数分别为0．25，0．65和0．93．利用自由体积模型对块体非晶合金的超塑性流变行为的微观机制进行了分析．     

Copper (I) ion stabilized on fe3o4‐core ethylated branched polyethyleneimine‐shell as magnetically recyclable catalyst for ATRP reaction

Branched polyethyleneimine (bPEI) was used to modify the surface of Fe₃O₄ nanoparticles coated with silica layer, and then, it was treated with ethyl iodide to prepare Fe₃O₄@SiO₂@Ethylated‐bPEI. In the next step, the yolk–shell structure was gained by selectively etching the SiO₂ middle layer. Finally, copper(I) was introduced to the yolk–shell Fe₃O₄@Ethylated‐bPEI and the activity of the catalyst was evaluated for atom transfer radical polymerization (ATRP) of styrene, led to obtain the well‐defined polymer with relatively low polydispersity. The toxicity of the residual copper in the polymer product was a limiting issue for applicability of ATRP reactions especially for biological purposes. In this report, the copper content in the polymer was reduced to the excellent value of 1.1 ppm. Moreover, the magnetic isolation, recyclability, and remove the need for an external ligand were other advantages of the synthesized catalyst which makes it suitable for employing in ATRP reactions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42337.     

NiAl超塑性变形的正电子寿命研究

研究了B2型多晶NiAl的晶界结构对缺陷态正电子寿命的影响，并结合正电子谱探讨了热挤压及超塑性变形过程后的晶界结构，热挤压的NiAl合金具有有完全的再结晶组织，而超塑性变形过程中的动态回复和再结晶是一种不完全再结晶过程，所得到的晶界仍属于亚晶界或小角度晶界范畴，再结晶晶界在超塑性变形过程中不产生滑动。     

Dyeing of wool with antibiotics to develop novel infection resistance materials for extracorporeal end use

Two antibiotics, doxycycline (Doxy) and ciprofloxacin (Cipro), were applied under a variety of conditions to wool and to hydrolyzed wool at 40°C. Nylon was used as a synthetic control. Sorption of Doxy was much higher in wool than in nylon, whereas sorption of Cipro was similar in both fibers. FTIR spectroscopy confirmed that a drastic increase in sorption of antibiotics by hydrolyzed wool was attributed to an increase in polar functional groups by peptide scission and in oxidized sulfur groups by cystine oxidation. Both sorption and zone of inhibition (ZOI) values were improved by hydrolysis of wool. Wool hydrolyzed for 20 or 40 min at 40°C and dyed with Doxy at 45°C for 3.5 h maintained around 30 mm of ZOI after 24 h of challenge by a simulated flow of blood. Wool hydrolyzed for 60 min at 40°C and dyed with Cipro at 45°C for 3.5 h also maintained its antibiotic activity for an extended time. For the most part, ZOI values for nylon dyed by both antibiotics were zero within 24 h. This technique produced infection‐resistant biomaterials of potential use in extra‐corporeal biomedical and biological applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3343–3354, 2004     

冷铁的失效原因分析

本文采用金相显微分析，电子探针微区成分分析等手术对铸铁材质冷铁的失效原因进行了研究，并在此基础上提出了本试验条件下铸铁氧化过程的机理。     

Chemical and physical characterization of a novel poly(carbonate urea) urethane surface with protein crosslinker sites

A major complication which occurs with implantable polyurethane biomaterials is bioincompatibility between blood and the biomaterial surface. Development of a novel biodurable polyurethane surface to which biological agents, such as growth factors or anticoagulants could be covalently bound, would be beneficial. The purpose of this study was to synthesize a novel poly(carbonate urea) urethane polymer with carboxylic acid groups which would serve as "anchor" sites for protein attachment. Physical characteristics such as tensile strength, initial modulus, ultimate elongation, tear strength, water/alcohol uptake and water vapor permeation were then evaluated and compared to other biomedical-grade polyurethanes. Covalent linkage of the blood protein albumin to this novel surface was then examined. A biodurable polycarbonate-based polyurethane containing carboxylic acid groups (cPU) was synthesized using a two step procedure incorporating the chain extender 2,2-bis(hydroxymethyl)-propionic acid (DHMPA). Tensile strength of this cPU film was 2.7 and 2.6 fold greater than both a polycarbonate-based polyurethane synthesized with a 1,4-butanediol chain extender (bdPU) and Mitrathane (Mit) controls, respectively. The cPU polymer also possessed 7.8 and 31 fold greater structural rigidity upon evaluation of initial modulus as compared to the bdPU and Mit, respectively. Ultimate elongation for the bdPU films was slightly higher than the cPU and Mit films, which had comparable elongation properties. The force required to tear the bdPU film was 1.9 and 32 fold greater than the cPU and Mit films, respectively. Alcohol solution uptake by all of the polyurethane segments increased with increasing alcohol concentrations, with the cPU having the greatest uptake. Water uptake was minimal for all the polyurethanes examined and was not affected by altering pH. Water vapor permeation was lowest for the cPU films as compared to both bdPU and Mit. Swelling the cPU in 50% ethanol prior to evaluation slightly increased water vapor permeation through the films. Covalent linkage of the radiolabelled blood protein albumin (125I-BSA) to the cPU segments incubated with the heterobifunctional crosslinker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) was greatest in the higher percent of ethanol as compared to controls. These results serve as foundation for developing a novel poly(carbonate urea) urethane with physical characteristics comparable to other medical-grade polyurethanes while having protein binding capabilities.     

Neural network solution for a real-time no-reference video quality assessment of H.264/AVC video bitstreams

The ever-growing video streaming services require accurate quality assessment with often no reference to the original media. One primary challenge in developing no-reference (NR) video quality metrics is achieving real-timeliness while retaining the accuracy. A real-time no-reference video quality assessment (VQA) method is proposed for videos encoded by H.264/AVC codec. Temporal and spatial features are extracted from the encoded bit-stream and pixel values to train and validate a fully connected neural network. The hand-crafted features and network dynamics are designed in a manner to ensure a high correlation with human judgment of quality as well as minimizing the computational complexities. Proof-of-concept experiments are conducted via comparison with: 1) video sequences rated by a full-reference quality metric, and 2) H.264-encoded sequences from the LIVE video dataset which are subjectively evaluated through differential mean opinion scores (DMOS). The performance of the proposed method is verified by correlation measurements with the aforementioned objective and subjective scores. The framework achieves real-time execution while outperforming state-of-art full-reference and no-reference video quality assessment methods.

     

Hybrid nanocomposite membranes of sulfonated poly(ethersulfone)/1,1-carbonyl diimidazole/1-(3-aminopropyl)-silane/silica for direct methanol fuel cells

Composite membranes of sulfonated poly(ethersulfone)/1,1-carbonyl diimidazole/1-(3-aminopropyl)-silane/silica (SPES/CDI/AS/SiO₂) with silica of various contents (3, 5 and 8 wt%) were prepared as electrolytes for direct methanol fuel cells (DMFCs). Comparison was made with pure SPES and SPES/SiO₂. The properties of the composite membranes were studied by FTIR, TGA, XRD, water and methanol uptake, proton conductivity. SPES/CDI/AS/SiO₂ membranes were also characterized by scanning electron microscopy (SEM), which showed good adhesion between the modified sulfonic acid (-SO3H) groups of SPES and silica because of cross-linking with covalent bond formation and reduced cavities in the composites. This effect played an important role in reducing water uptake, methanol uptake and methanol permeability of the SPES/CDI/AS/SiO₂ composites. The water and methanol uptake and also methanol permeability of the SPES/CDI/AS/SiO₂ composite membrane with 8% SiO₂ were found in the order 3.58%, 2.48% and 1.91×10^?7 (cm²s^?1), lower than those of SPES and Nafion 117. In SPES membrane of 16.94% level of sulfonation, the proton conductivity was 0.0135 s/cm at 25 °C, which approached that of Nafion 117 under the same conditions. Also, the proton conductivity of the SPES/CDI/AS/SiO₂ 8% membrane was 0.0186 s/cm, which was higher than that of SPES at room temperature. The preparation of SPES/SiO₂ composites in the presence of AS and CDI, led to 63%, 56% and 64% reduction of water uptake, methanol uptake and methanol permeability, respectively without a sharp drop in proton conductivity of the composite membranes which featured a good balance between high proton conductivity, water and methanol uptake of SPES/CDI/AS/SiO₂ membranes.