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G. Böhme 《Isotopes in environmental and health studies》2013,49(4):124-127
In der vorliegenden Arbeit wird zunächst der Aufbau der 85Kr-Bremsstrahlungsquellen behandelt. Die Anwendung für die Dickenmessung von Schwermetall- und Aluminiumbändern und die aus diesen Untersuchungen erhaltenen Meβbereiche für das Flächengewichtsmeβgerät mit Automatik VA-T-75 werden dargestellt. 相似文献
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混沌系统的未知系统参数估计是实现混沌控制和同步的首要问题,通过构造一个合理的适应度函数,可将其转化为一个多维搜索空间的优化问题.提出一种融合改进骨干粒子群算法与改进差分进化算法的混合群智能优化方法来解决上述优化问题.对骨干粒子群算法中的粒子位置更新机制以及差分进化算法中的变异操作、交叉操作、交叉概率因子的设计等进行改进,有效兼顾了种群的多样性与算法的收敛性.在此基础上,讨论骨干粒子群优化算法与差分进化的融合优化策略,实现两个算法的协同进化,进一步提高算法的综合优化性能.用6个基准测试函数以及Lorenz混沌系统为例进行仿真实验,结果表明该方法具有全局寻优能力强、收敛速度快、搜索精度高、稳健性好等优点. 相似文献
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Takuro Miki Takumi Ogawa Tetsuhiko Isobe Hocine Sfihi 《Journal of Sol-Gel Science and Technology》2004,32(1-3):73-77
Acetylcellulose (AC)/silica and polyvinylpyrrolidone (PVP)/silica composites were prepared by the sol–gel method from Si(OCH3)4-AC-HNO3-H2O-tetrahydrofuran-CH3OC2H4OH and Si(OCH3)4-PVP-(CH3COOH or NH3)-H2O-CH3OH-CH3OC2H4OH solutions. AC/silica composites were composed of micrometer-sized particles rich in silica and a matrix rich in AC, while PVP/silica composites were single-phase on the SEM length scale. The AC/silica composites exhibited elastic-plastic behavior, and had excellent machinability without chipping on cutting with an electric saw while the PVP/silica composites showed less plasticity and machinability. Youngs modulus and bending strength were increased by post-drying, 1.8–2.8 GPa and 49–88 MPa, respectively, for the AC/silica composites, and 1.0–3.9 GPa and 17–79 MPa, respectively, for the PVP/silica composites. 相似文献
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One of the biggest struggles of biological anthropology is to estimate the biological profile from burned human skeletal remains. Bioanthropological methods are seriously compromised due to bone heat-induced alterations in shape and size. Therefore, it is urgent to improve our ability to estimate sex, age at death, stature, and ancestrality, to recognize peri mortem traumas and differentiate them from fractures due to fire, and to determine what was the intensity of burning, namely maximum temperature and heat exposure length. This review focuses on different methodologies to assess heat prompted changes in bone submicrostructure. Some of these are extensively used in burned bones research, namely infrared and Raman spectroscopy and X-ray diffraction, while others such as neutron spectroscopy and diffraction are rarely applied to bone samples although their contribution may be crucial for establishing new bioanthropological methods for a reliable examination of burned victims. 相似文献
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Céline Martin Bruno Maureille Romain Amiot Alexandra Touzeau Aurélien Royer François Fourel 《Isotopes in environmental and health studies》2017,53(3):223-242
The oxygen isotope compositions of bones (n?=?11) and teeth (n?=?20) from 12 Sudanese individuals buried on Sai Island (Nubia) were analysed to investigate the registration of the evolution of the Nile environment from 3700 to 500 years BP and the potential effects of ontogeny on the oxygen isotope ratios. The isotopic compositions were converted into the composition of drinking water, ultimately originating from the Nile. δ18O values decrease during ontogeny; this is mainly related to breastfeeding and physiology. Those of neonates present very large variations. Neonates have a very high bone turnover and are thus able to record seasonal δ18O variations of the Nile waters. These variations followed a pattern very similar to the present one. Nile δ18O values increased from 1.4 to 4.4?‰ (Vienna Standard Mean Ocean Water) from the Classic Kerma (~3500 BP) through the Christian period (~1000 BP), traducing a progressive drying of Northeast Africa. 相似文献
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Pyrolysis of Animal Bones with Vitamin B12: A Facile Route to Efficient Transition Metal–Nitrogen–Carbon (TM‐N‐C) Electrocatalysts for Oxygen Reduction 下载免费PDF全文
Dr. Meiling Dou Duanpeng He Wenhao Shao Dr. Haijing Liu Prof. Feng Wang Prof. Liming Dai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):2896-2901
By pyrolyzing cattle bones, hierarchical porous carbon (HPC) networks with a high surface area (2520 m2 g?1) and connected pores were prepared at a low cost and large scale. Subsequent co‐pyrolysis of HPC with vitamin B12 resulted in the formation of three‐dimensional (3D) hierarchically structured porous cobalt–nitrogen–carbon (Co‐N‐HPC) electrocatalysts with a surface area as high as 859 m2 g?1 as well as a higher oxygen reduction reaction (ORR) electrocatalytic activity, better operation stability, and higher tolerance to methanol than the commercial Pt/C catalyst in alkaline electrolyte. 相似文献
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Camila de Carvalho Almança Lopes Pedro Henrique Justino Oliveira Limirio Veridiana Resende Novais 《应用光谱学评论》2018,53(9):747-769
Fourier transform infrared spectroscopy (FTIR) has been used extensively for chemical characterization of mineralized tissues in the past few decades. FTIR is an ideal technique to analyze chemical structural properties of natural materials, since the frequencies of several vibrational modes of organic and inorganic molecules are active in the infrared. This review discusses the use of FTIR methodology, highlighting the attenuated total reflection (ATR) sampling mode, particularly for characterization of enamel, dentin and bone tissues. Enamel, dentin and bone, are composed of an organic and a mineral phase. The mineral phase is characterized essentially as nonstoichiometric substituted apatite, being the carbonate and phosphate spectral peaks the main representative of these phase. Organic matrix of the post-eruptive enamel is small (~1% weight (wt)). The dentin and bone organic phases are mainly composed of type I collagen that appears as spectral bands of amide I, amide II, amide III bands. Furthermore, synthetic apatite materials are being designed for total or partial replacement, restoration or augmentation of these biological tissues with FTIR assistance. 相似文献
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利用气相色谱(GC)技术,采用酸水解提取脂质,比较了6种甲酯化法(乙酰氯-甲醇法、H2SO4-甲醇法、HCl-甲醇法、KOH-甲醇法、KOH-甲醇+H2SO4-甲醇法和KOH-甲醇+HCl-甲醇法)对脂肪酸测定的影响,优选牦牛骨中脂肪酸测定的最佳方法。37种脂肪酸标准样品在0.28~250.00 mg/L范围内线性关系良好,相关系数均大于0.99(除C4:0外)。碱酯化法和酸碱结合法几乎无法测出牦牛骨中的脂肪酸,其测得的总脂肪酸含量小于0.20 g/100 g。乙酰氯-甲醇法测得的总脂肪酸含量(13.61 g/100 g)显著高于H2SO4-甲醇法(总脂肪酸含量为11.68 g/100 g)和HCl-甲醇法(总脂肪酸含量为3.18 g/100 g)测得的结果。乙酰氯-甲醇法和H2SO4-甲醇法的日内和日间精密度分别为0.27%~8.60%和0.34%~2.64%,两种方法中脂肪酸的回收率为83.06%~105.54%。结果表明,酸水解-乙酰氯-甲醇法是牦牛骨中脂肪酸测定的最佳方法。C18:1n9c、C16:0、C18:0和共轭亚油酸(CLA)是牦牛骨的主要脂肪酸,其总和达脂肪酸总量的85%以上,饱和脂肪酸与不饱和脂肪酸含量比值约为1:2。牦牛骨中脂肪酸的研究为骨资源脂质的有效利用提供了重要依据。 相似文献
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Xiao Zhang Xiaochen Ma Qianming Lin Lin Xiao Shuhan Wang Han Yang Liqiong Liao Yuhong Liu Chao Zhang Jian Song 《Macromolecular bioscience》2023,23(5):2200548
The tribological behavior between orthopedic implants and cortical bone is important but usually neglected. Poly(ether-ether-ketone) (PEEK) is a promising material for orthopedic applications. To further understand and improve the interfacial tribological properties between PEEK implant and host bone tissue, a PEEK-cortical bone tribo-pair is designed and fabricated. The frictional and wear performance of such tribo-pair is investigated under different lubricants, i.e., simulated body fluid (SBF), calf serum (CS), hyaluronic acid (HA), and mucin (MUC). The results suggest that MUC solution can be utilized as an artificial natural synovial fluid to improve the tribological properties of PEEK-based implants. 相似文献