Substituted hydroxyapatites for biomedical applications: A review

This review summarizes recent and very recent work on preparing substituted hydroxyapatites. Ease of atomic doping or substitution in apatite opens this mineral up for a wide range of biomedical applications. It can be used for repairing and replacing diseased and damaged parts of musculoskeletal systems, and also as a drug or gene delivery agent, as a bioactive coating on metallic osseous implants, biomagnetic particles and fluorescent markers. First, the physicochemical properties of bioapatites are described and discussed. Then a general summary on substitution reaction for hydroxyapatite is made. Special attention is paid to describing anionic, cationic and multisubstituted hydroxyapatites used for various biomedical applications. Finally, conclusions are drawn and future perspectives are discussed.     

Competitive substitution and technological diffusion for semiconductor foundry firms

To survive in an intensively competitive environment, semiconductor companies need to be more agile, responsive, and flexible than before. Generally, semiconductor industry consists of three business models: integrated design manufacturer, fabless chip design, and foundry business. In general, semiconductor firms are affected by three drivers: new entrants and rivals (competition), main customers (demand), and process technologies (R&D). Inspired by Michael Porter’s five-force analysis, a novel framework is presented to accomplish the following goals: (1) The interactions between the top three foundry firms, TSMC, Samsung, and Global Foundries, are analyzed to reveal managerial insights, (2) The main customers of TSMC including Apple, Huawei, Qualcomm, Mediatek, AMD, and NVidia are incorporated to into sales forecasting, and (3) Technological diffusion across the mature process (above 70 nm), the medium process (between 20 nm and 70 nm), and the advanced process (below 20 nm) is captured to predict sales revenues. Key findings are shown as follows: (1) a large-scale foundry frim benefits from the existence of a small-scale firm, (2) the inclusion of main customers significantly improves the performance of sales forecasting, (3) the advanced process gradually benefits from the mature process while it rapidly replaces the medium process in a “predator-prey” way.     

电能替代实施现状及发展趋势预判

20132019年电能替代得到大力实施,替代电量稳步增加,替代领域不断扩增,未来电能替代电量依然呈现增长趋势。本文首先对电能替代的实施现状及存在问题进行总结和梳理。其次,从技术、政策及市场等方面分析电能替代的发展趋势。最后,初步测算电能替代潜力,分不同情境给出电能替代量预测结果。     

An efficient and secure cipher scheme for images confidentiality preservation

In this paper, a novel image encryption scheme based on two rounds of substitution–diffusion is proposed. Two main objectives have guided the design of this scheme: (a) robustness against the most known type of attacks (statistical, chosen/known plaintext, ciphertext-only and brute force attacks) and (b) efficiency in terms of computational complexity (i.e., execution time reduction) in order to meet recent mobiles’ applications’ requirements. First, a dynamic key, changed for every input image is generated and used as the basis to construct the substitution and diffusion processes. Then, the encryption process is performed by the transmitter based on a non-linear S-box (substitution) and a matrix multiplication (diffusion), applied on each sub-matrix of the image. At the destination side, decryption is applied in the reverse order. We have conducted several series of experiments to evaluate the effectiveness of the proposed scheme. The obtained results validated the robustness of our scheme against all considered types of attacks and showed an improvement in terms of execution time reduction compared to the recent existed image-encryption schemes.     

Macro OL-systemsf macro

Macro OL-systems and two of their subclasses, called FMOL-systems and RMOL-systems are introduced. Macro OL-systems arc motivated by theoretical models for the development of biological organism. Various properties of the families of languages generated by FMOL-systems and RMOL-systems are studied. It is shown that the family of languages generated by RMOL-systems forms the minimal full abstract family of languages containing the family of OL-languages.     

高铋粗铅电解精炼生产控制条件浅析及实践

分析了铋在粗铅电解精炼中的行为,介绍了高铋粗铅电解精炼中存在的问题,通过采取合理搭配粗铅、控制电流密度及电解液成分、阳极泥洗水铅铋置换等有效措施,确保了铅电解生产平稳运行,析出铅合格。     

单甲氧基聚乙二醇氨基的制备

通过两步反应制备了相对分子质量(简称分子量)为5 000的单甲氧基聚乙二醇氨基(m PEG5k-EDA)。首先以单甲氧基聚乙二醇5 000(m PEG5k)和对甲苯磺酰氯(p-Ts Cl)为原料,反应得到活性中间体m PEG5k-OTs,然后通过与乙二胺的亲核取代反应获得目标产物,并通过正交实验确定了最佳反应条件:m PEG5k-OTs与乙二胺的摩尔比为1∶25、反应温度为80℃和反应时间为24 h。产物和中间体的结构通过IR和1HNMR进行表征,并通过SDS-PAGE碘染色法检测产物分子量的变化情况。结果表明,通过该方法能简便快捷地制备m PEG5k-EDA,在最优实验条件下,目标产物的总收率高达76.8%,且SDS-PAGE检测表明,产物纯度较高,不含交联副产物。     

On some families of languages related to developmental systems

OL systems and TOL systems are the simplest mathematical models for the study of the development of biological organisms with or without a variable environment, respectively. This paper contributes to the study of the properties of the languages generated by these systems and by their generalizations. Macro OL (TOL) languages are languages obtained by substituting languages of a given type in OL (TOL) languages. We study properties of certain families of macro OL (TOL) languages in particular we show that they are full AFL's.

We observe that OL, TOL systems and many of their generalizations can be viewed as special classes of index grammars.     

The elasticity of capital-labour substitution in Singapore construction

A central issue in improving construction productivity is the flexibility in which capital and labour may be substituted. Empirical estimation using Singapore data suggests that the hypothesis of a unitary elasticity of substitution cannot be rejected, thereby providing justification for policy measures to alter the relative prices of factor inputs to encourage mechanisation in construction. The finding is consistent with an earlier study on the American construction industry as well as numerous production function studies conducted for other industries.