Purification and characterization of keratinase from a new Bacillus subtilis strain

The aim of this study was to purify and characterize a keratinase produced by a new isolated Bacillus subtilis KD-N2 strain. The keratinase produced by the isolate was purified using ammonium sulphate precipitation, Sephadex G-75 and DEAE （diethylaminoethyl）-Sepharose chromatographic techniques. The purified enzyme was shown to have a molecular mass of 30.5 kDa, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE） analysis. The optimum pH at 50 ℃ was 8.5 and the optimum temperature at pH 8.5 was 55 ℃. The keratinase was partially inactivated by some metal ions, organic solvents and serine protease inhibitor phenylmethanesulfonyl fluoride （PMSF）. Sodium dodecyl sulfate （SDS） and ethylene diamine tetraacetic acid （EDTA） had positive effect on the keratinase activity. Reducing agents including dithiothreitol （DTT）, mercaptoethanol, L-cysteine, sodium sulphite, as well as chemicals of SDS, ammonium sulfamate and dimethylsulfoxide （DMSO） stimulated the enzyme activity upon a feather meal substrate. Besides feather keratin, the enzyme is active upon the soluble proteins ovalbumin, bovine serum albumin （BSA）, casein and insoluble ones as sheep wool and human hair. Calf hair, silk and collagen could not be hydrolyzed by the keratinase.     

碳/碳复合材料新基体—聚芳基乙炔研究Ⅰ.芳基乙炔的合成与表征

用溴化—脱溴化氢一步法制备二乙炔基苯，研究碱、催化剂、反应温度及反应时间等因素对产率的影响。结果表明，以聚乙二醇－４００为相转移催化剂，二乙炔基苯的产率达６８．６％。用气相色谱、红外光谱、核磁共振和质谱对产物进行了分析表征。     

Characterization of medical ultrasonic transceivers. Gain transfer characteristics and their applications.

The concept of gain transfer characteristics of medical ultrasonic transceivers is presented. Transfer characteristics relate the peak echo amplitude at the output of the receiver to the attenuation of a reproducible reference echo, at discrete time gain compensation (TGC) voltage levels. A method is shown for the determination of the transfer characteristics, and their numerous applications are described.     

重组长链脂肪酸醇氧化酶的分离纯化及特性研究

目的：从fao基因转化的E．coli BL21／DE3菌分离纯化重组酿酒酵母长链脂肪酸醇氧化酶,并对其理化性质进行研究。方法：应用硫酸铵分级沉淀、phenyl-sepharose HR5／5层析等方法分离纯化长链脂肪酸醇氧化酶,应用SDS-PAGE电泳测定其相对分子量,并对其Km、酸碱稳定性及其底物特异性进行分析。结果：应用上述分离方法得到电泳呈单一条带的酶蛋白,相对分子量大约为64000,得率为17．6％以上;该酶对十二烷醇的Km在2．5和3．0μmol／L之间,最适pH值为8．5,在pH7．0环境中,酶活性为pH8．5时的60％;对十二烷醇催化的相对活性较其它一些长链的二醇和脂肪酸醇为高。结论：从fao基因转化的E．coli BL21／DE3菌分离出重组酿酒酵母长链脂肪酸醇氧化酶,该酶为碱性酶,其最适底物为十二烷醇,但也可氧化一些长链的二醇和脂肪酸醇。     

中华眼镜蛇蛇毒神经生长因子生物活性和理化性质测定

目的：控制中华眼镜蛇蛇毒神经生长因子产品质量,研究其理化性质及生物学活性的定性和定量。方法：通过离子交换色谱、凝胶过滤及FPLC色谱分高纯化得到中华眼镜蛇蛇毒神经生长因子,按国家新药审批有关要求对其进行了SDS－PAGE电泳,N端蛋白质序列规定,HPLC色谱分析,UV光谱图谱扫描,并利用PC12细胞培养法和鸡胚背根神经节培养法检测其生物活性。结果：电泳为一条带,亚基分子量为13500,N端蛋白质序列测定后确证为神经生长因子（NGF）,HPLC为单峰,相对百分含量为95％以上,279．6nm处呈现出蛋白质样特征吸收峰。生物活性测定为,PC12细胞培养法灵敏度可达1ng／ml,鸡胚背根神经节培养法需30ng／ml的浓度梯度才能在神经节上有所反应。结论：此实验样品为具有较高生物活性的高纯度NGF多肽。     

用于放疗剂量验证的新型片状Presage胶体剂量计特性研究

目的 明确用于放疗剂量验证的新型片状Presage胶体剂量计的吸收光谱、剂量线性、量程、稳定性等关键剂量响应特性。方法 使用放疗加速器对同批次片状Presage剂量计进行系列照射实验，使用分光光度计测量照射前后剂量计在400~700 nm可见光范围内的吸收光谱，使用胶片平板扫描仪测量照射前后R-G-B 3通道的吸光度变化。结果 片状Presage在628 nm处有明显吸收峰且峰值吸光度随受照剂量呈显著线性变化趋势（R²=0.999 9），而在490 nm附近存在平缓吸收谷且谷区吸光度随受照剂量变化不大。胶体平板扫描仪R通道的吸光度测量灵敏度远大于G与B通道，在<10 Gy范围内，R通道吸光度随受照剂量呈高度线性变化（R²=0.999 9），而在大量程范围则呈显著二次变化趋势（R²=0.999 9）。该剂量计的量程范围>94.6 Gy，在照射后1 h内吸光度变化可忽略，之后则呈现缓慢上升趋势，上升速度与受照剂量呈正相关，同时，未发现剂量梯度区出现梯度模糊现象。结论 新型片状Presage胶体剂量计在一定范围内具有良好剂量线性，量程大、梯度保持性好、无分割效应，提示在大分割多靶点放疗的积分剂量验证中具有潜在应用优势。     

Optical Density Value and Ratio as Novel Indexes for Nanoemulsion Sterile Filtration Process Control or Characterization

Sterile filtration is an effective method to remove any microorganisms present during nanoemulsion preparation. However, it lacks effective control parameters. Here, we established a simple and rapid approach for the process control of nanoemulsion sterile filtration by utilizing optical density detection as a process control parameter. During sterile filtration, the optical density or optical density ratio of the filtrate were continuously monitored to explore the correlation between optical density and the emulsion content and the change in the optical density ratio before and after sterile filtration. In the emulsion stability test, the optical density ratio was determined. A good correlation was obtained between the optical density and the nanoemulsion content during sterile filtration, thereby reducing sterile filtration loss. The optical density ratio changed significantly after sterile filtration, indicating that it could be used as a process control parameter to monitor leakage during emulsion sterile filtration. The optical density ratio can be a characterization index for stability monitoring as it is more sensitive than particle size detection and more convenient than large particle detection. These parameters may be used for sterile filtration process control and as an index for nanoemulsion characterization. This approach overcomes the limitations of existing nanoemulsion characterization methods.     

诗词负性情绪及心理表征研究

目的：了解古代诗词的负性情绪及心理表征。方法：运用汉字联想心理分析388首古代诗词。结果：初步证明诗词中的情绪词、汉字重叠、同字、疑问词（或疑问句）是反映诗词负性情绪的表征。结论：诗词负性情绪表征不仅仅能诊断心理障碍,也可以成为心理治疗的一种方法。情绪表征法也可作为诗词的一种修辞手法加以创新。     

Ultrasound Imaging and Characterization of Biofilms Based on Wavelet De-noised Radiofrequency Data

The ability to non-invasively image and characterize bacterial biofilms in children during nasopharyngeal colonization with potential otopathogens and during acute otitis media would represent a significant advance. We sought to determine if quantitative high-frequency ultrasound techniques could be used to achieve that goal. Systematic time studies of bacterial biofilm formation were performed on three preparations of an isolated Haemophilus influenzae (NTHi) strain, a Streptococcus pneumoniae (Sp) strain and a combination of H. influenzae and S. pneumoniae (NTHi + Sp) in an in vitro environment. The process of characterization included conditioning of the acquired radiofrequency data obtained with a 15-MHz focused, piston transducer by using a seven-level wavelet decomposition scheme to de-noise the individual A-lines acquired. All subsequent spectral parameter estimations were done on the wavelet de-noised radiofrequency data. Various spectral parameters—peak frequency shift, bandwidth reduction and integrated backscatter coefficient—were recorded. These parameters were successfully used to map the progression of the biofilms in time and to differentiate between single- and multiple-species biofilms. Results were compared with those for confocal microscopy and theoretical evaluation of form factor. We conclude that high-frequency ultrasound may prove a useful modality to detect and characterize bacterial biofilms in humans as they form on tissues and plastic materials.     

Artificial Intelligence Allows Leaving-In-Situ Colorectal Polyps

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