2'-脱氧核糖胞苷的合成工艺

本文报道了2''-脱氧核糖胞苷的一条工业化生产的路线。该工艺路线以α-D-2-脱氧核糖和尿嘧啶为原料,经过甲苷化,酯化,氯代,亲核取代,高效氨化及水解脱保护等6个步骤,总收率44%,经一次重结晶纯化最终产品纯度达到99%以上。此路线条件温和,操作安全,终产物分离纯化简易。目前已经完成公斤级别的中试。     

Synchronous steady state response of an overhung rotor with squeeze film damping

An analytical method is developed for treatment of a typical system in which the outrigger bearing of an overhung rotor is provided with a squeeze film damper supported in a flexible casing. The rotor and stator of multiple degrees-of-freedom are handled with convenience by a “polar receptance matrix” method. A characteristic equation is derived which governs rotor-stator interaction either with dry contact or through a squeeze film damper. For the nonlinear squeeze film action solutions based on “mobility” information of a dynamically loaded journal bearing are obtained facilitating a general approach. A computer programme is written in Fortran for steady state response of the system in terms of whirl, position and force vectors, trial runs of which indicate complex behaviour of a squeeze film damped system.     

Discrete framelet transform based OFDM system using N-FRAT mapping over Rayleigh fading channel

This article proposes an N-finite Radon transform (N-FRAT) and a discrete framelet transform (FT) for the design of a new orthogonal frequency division multiplexing (OFDM) system. In the proposed system, the inverse FT (IFT) and FT were used instead of the inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) to realize multicarrier modulation and demodulation techniques, respectively. Simultaneously, it was suggested that the N-FRAT technique operate as a data mapper instead of the conventional phase shift keying (PSK) and quadrature amplitude mapping (QAM), which are usually used with the traditional OFDM system. The usage of the N-FRAT and FT in the proposed system led to an increase in the orthogonality between the subcarriers due to the application of IFFT in the N-FRAT, which was added to improve the orthogonality and time–frequency localization properties of the FT. Furthermore the proposed structure improved the bandwidth efficiency through the elimination of the cyclic prefix compared to the traditional system. The proposed system was simulated and compared with other OFDM systems, such as FFT based OFDM using N-FRAT mapping (N-FRAT-FFT-OFDM), FT based OFDM using QAM mapping (QAM-FT-OFDM), and FFT based OFDM using QAM mapping (QAM-FFT-OFDM). The simulation was performed over frequency selective fading channel using MATLAB technical programming language. The results of simulations showed that the new structure outperformed the other three systems by reducing the inter-symbol interference (ISI) and inter-carrier interference (ICI), which then improved the bit error rate (BER) performance.     

Multi-objectives TLBO hybrid method to select the related risk features with rheumatism disease

Neural Computing and Applications - Features subset selection was commonly used in data mining and artificial intelligence techniques to produce a model with a minimal set of features that enhances...     

Oscillatory flow in a stratified medium past an infinite porous plate with constant suction

An approximate solution to oscillatory flow past a porous horizontal plate was carried out under the following conditions

• (i) Constant suction
• (ii) Stratification of the medium due to change in density, viscosity and thermal conductivity
• (iii) Free-stream oscillation about a nonzero constant mean.

Solutions have been derived for the transient velocity, the transient temperature, the amplitude and the phase of skin friction and the amplitude and phase of the first and second harmonics of the rate of heat transfer. These are shown on the graphs. The effects of the suction parameter S, the stratification parameter λ, the frequency λ and the Eckert number E are discussed.     

Classification and Diagnosis of Lymphoma’s Histopathological Images Using Transfer Learning

Current cancer diagnosis procedure requires expert knowledge and is time-consuming, which raises the need to build an accurate diagnosis support system for lymphoma identification and classification. Many studies have shown promising results using Machine Learning and, recently, Deep Learning to detect malignancy in cancer cells. However, the diversity and complexity of the morphological structure of lymphoma make it a challenging classification problem. In literature, many attempts were made to classify up to four simple types of lymphoma. This paper presents an approach using a reliable model capable of diagnosing seven different categories of rare and aggressive lymphoma. These Lymphoma types are Classical Hodgkin Lymphoma, Nodular Lymphoma Predominant, Burkitt Lymphoma, Follicular Lymphoma, Mantle Lymphoma, Large B-Cell Lymphoma, and T-Cell Lymphoma. Our proposed approach uses Residual Neural Networks, ResNet50, with a Transfer Learning for lymphoma’s detection and classification. The model used results are validated according to the performance evaluation metrics: Accuracy, precision, recall, F-score, and kappa score for the seven multi-classes. Our algorithms are tested, and the results are validated on 323 images of 224 × 224 pixels resolution. The results are promising and show that our used model can classify and predict the correct lymphoma subtype with an accuracy of 91.6%.     

卷取温度对Q960热轧薄钢板组织与性能的影响

研究了中低温卷取温度对Q960热轧薄板钢显微组织和力学性能的影响。结果表明,随着卷取温度从562℃降至359℃,Q960热轧板的显微组织由粒状贝氏体+少量的珠光体转变为下贝氏体;渗碳体含量明显增加而MC相略有下降。低温或超低温卷取可以减轻或消除Q960热轧板的带状组织。采用非再结晶轧制和约350℃低温卷取可以使Q960热轧卷板获得1000 MPa以上的非比例延伸强度,同时冲击性能良好。     

A novel process for precipitation of ultra-fine particles using sub-critical CO2

Supercritical CO₂ has been utilized as solvent, cosolvent or antisolvent in several processes for production of ultra-fine solid particles with narrow size distribution. The key to the precipitation of such particles is to produce a very large, rapid and uniform supersaturation in the solution of a solid substance. This can be achieved either by a rapid and large reduction in the temperature of solution or by drastically increasing the CO₂ solubility for imparting the antisolvent effect. Most of these CO₂ processes require high-pressure pumps, specially designed nozzles and accurate control of process parameters. In order to obviate these requirements, a simple technique of precipitation by pressure reduction over the gas-expanded liquids (PPRGEL), such as CO₂-expanded organic solutions has been utilized to impart a large, uniform and rapid reduction of temperature in the solution for instantaneous precipitation of ultra-fine particles. This process utilizes sub-critical CO₂ at relatively low pressures of 40-70 bar and near ambient temperature of 303 K for creating a temperature drop of 30-70 K in the solution within seconds, without using any specially designed nozzle or high-pressure pumps. The present paper validates the process principle for precipitation of Zinc acetate (ZnAc) nanoparticles from its organic solution in a mixed solvent of acetone and dimethyl sulfoxide (DMSO). Nanoparticles are produced with the average size of 20-250 nm (from 100 ml of solution in a high-pressure vessel of 1.09 L working volume), and vary in shapes such as long needles, rods and near spherical depending on pressure (40-70 bar at 303 K), solid concentration (0.01-0.05 g/ml) and addition of stabilizer.     

A Web‐Based Instructional Module for Research and Learning in Design and Analysis of Enterprise Systems

This paper describes an instructional module designed to create a repository for introducing students and industry practitioners to enterprise systems. A web‐based design was used to make the module scalable, utilizing Internet capabilities and adapting a systemic approach to disseminate information on research projects. Important characteristics of a web site for organizing information are described. A generic web design problem is outlined and a case study on supply chain management is illustrated. Uses of the module on curricula that satisfy cognitive goals of enterprise system education are discussed. The module offers extensibility to incorporate live applications through the web site.