有机相中脂肪酶催化合成乳酸乙酯

 考察了在双底物抑制下脂肪酶催化合成乳酸乙酯,最佳溶剂为叔丁醇,在所选的几种脂肪酶中,固定化于大孔丙烯酸树脂的南极假丝酵母脂肪酶B (Novozym 435)的催化活性最好. 对反应条件进行了优化,当酸醇摩尔比为1∶8, 反应温度60 ℃, 酸浓度0.3 mol/L, 酶浓度45 g/mol, 摇床转速200 r/min时产率达到77%, 脂肪酶Novozym 435重复使用6次后产率仍然可达到60%.     

Low frequency acoustic signals associated with rock falls,thunderstorms, and wind turbulences in field environment

This paper characterized the observed low frequency acoustic signals generated by rock falls, thunderstorm, and wind turbulence in large rocky landslide. A digital infrasonic recording system was deployed on site to capture real-time low frequency acoustic signals associated with rock falls. An advanced non-stationary signal analysis method, i.e. Empirical Mode Decomposition (EMD), was applied to get insight to the characteristics of the low frequency acoustic signals induced by the hazards. Joint time–frequency distribution spectra technique was used to detect distinctive features of the events. The study shows that the low frequency acoustic signals can be excited by rock falls, thunderstorm and wind turbulence in the field environment, but the signal varies in both time domain and frequency domain with different patterns depending on the physical processes. The results demonstrated that the EMD-based signal processing technique is capable of extracting distinctive features to differentiate acoustic signals in real environment.     

滚边法测量高能X射线源焦斑大小

应用于高能闪光X光照相技术的X射线源焦斑大小是闪光照相装置的关键参数, 直接影响成像的分辨能力。由于高能X射线的强穿透性和强辐射环境, 给焦斑测量带来一定困难。介绍了一种间接测量方法, 采用滚边装置(rollbar)成像得到X射线源的边扩展函数, 微分后得到光源的线扩展函数并计算调制传递函数(MTF), 而后从MTF为0.5所对应的空间频率之值确定出光源的光斑大小。给出了神龙二号加速器电子束聚焦调试实验中得到的X射线焦斑测量结果, 分析影响测量结果的因素并提出了解决方法。     

室温离子液体的研究进展

对室温离子液体的制备及性能的研究进展进行了评述。室温离子液体的阳离子多为有机含氮杂环阳离子，阴离子通常为体积较大的无机阴离子。室温离子液体用作溶剂，具有液态温度范围宽、溶解能力强、蒸气压低、粘度高、电化学窗口宽等特点，在有机合成、电化学、无机物溶液化学方面具有广阔的应用前景。     

珠宝首饰中的化学

介绍了珠宝首饰的有关知识,常见珠宝的化学组成、性质、鉴赏,以及钻石和珍珠首饰的养护.     

Synthesis and biological evaluation of benzomorpholine derivatives as novel EZH2 inhibitors for anti-non-small cell lung cancer activity

The histone lysine methyltransferase EZH2 has been reported to play important roles in cancer aggressiveness, metastasis and poor prognosis. In this study, a series of benzomorpholine derivatives were synthesized and biologically evaluated as EZH2 inhibitors. The target compounds were obtained in good yields from 3-amino-5-bromo-2-hydroxybenzoic acid via cyclization, Suzuki coupling and amidation as the key steps. A preliminary optimization study led to the discovery of several potent novel EZH2 inhibitors (6b, 6c, 6x and 6y). Moreover, 6y inhibited the A549 and NCI-H1975 cell lines (IC₅₀?=?1.1 µM and 1.1 µM, respectively). Further studies indicated that 6y can reduce EZH2 expression in intact cells and cause cell arrest in the G2/M phase.

     

Optical properties and chemical composition of PM2.5 in Shanghai in the spring of 2012

The semi-diurnal mean aerosol mass concentration, chemical composition, and optical properties of PM2.5were investigated in Shanghai during the spring of 2012. Slight pollution was observed during the study period. The average PM2.5 concentration was 64.11 土 22.83(xg/m3. The mean coefficients of extinction,scattering, and absorption at 532 nm were 125.9 士 78.5,91.1 士 56.3,and 34.9 士 23.6 Mm-1, respectively. A relatively low mean single scattering albedo at 532 nm(0.73 士 0.04) and low level of elemental carbon(EC,2.67 士 1.96 |xg/m3) suggested that the light absorption was enhanced due to the internal mixing of the EC.Sulfate contributed the most to aerosol light scattering in Shanghai. The chemical composition of PM2.5was dominated by particulate organic matter, sulfate, nitrate, ammonium, and EC. Anthropogenic sources made a significant contribution to the emission and loading of the particulate pollutants. A relatively good correlation between the aerosol chemical composition and the cloud condensation nuclei(CCN) activation indicated that aerosol chemistry is an important factor that influences the saturated hygroscopicity and growth of the aerosol.     

玉石的化学知识与人文内涵

介绍了玉石的概念、分类、形成,常见玉石的化学组成、性质,玉石的保健作用、玉石养护知识以及玉石文化。     

泡沫塑料分离富集技术的应用现状

对１９９２－１９９９年泡沫塑料分离富集技术的应用进行了综述 ;根据泡沫塑料的结构特性,对其负载,吸附和解脱过程的机理进行了探讨。     

Optimization of MR diffusion-weighted imaging acquisitions for pancreatic cancer at 3.0 T

Objectives

To investigate and optimize diffusion-weighted imaging (DWI) acquisitions for pancreatic cancer at 3.0 T.

Methods

Forty-five patients with pancreatic cancer were examined by four DWI acquisitions with b values = 0 and 600 s/mm² at 3.0 T, including breath-holding DWI (BH-DWI), respiratory-triggered DWI (TRIG-DWI), respiratory-triggered DWI with inversion–recovery technique (TRIGIR-DWI), and free-breathing DWI with inversion–recovery technique (FBIR-DWI). Artifacts, contrast ratio (CR), contrast-to-noise ratio (CNR) and apparent diffusion coefficient (ADC) of pancreatic cancer were statistically compared among DWI acquisitions.

Results

TRIGIR-DWI displayed the lowest artifacts and highest CR compared to other DWI acquisitions. CNRs of pancreatic cancer in TRIG-DWI and TRIGIR-DWI were statistically higher than that in FBIR-DWI and BH-DWI. Different ADCs between pancreatic cancer and noncancerous pancreatic tissues were noticed by a paired-samples T test in TRIG-DWI (p = 0.017), TRIGIR-DWI (p = 0.00001) and FBIR-DWI (p = 0.000041).

Conclusions

TRIGIR-DWI may be the optimal acquisition of DWI for pancreatic cancer at 3.0 T.