Phase transformation on bone cement: Monocalcium phosphate monohydrate into calcium-deficient hydroxyapatite during setting

This study evaluated the phase transformation of calcium phosphate cement (CPC) using a mixture of monocalcium phosphate monohydrate (MCPM) and CaCO₃ as the solid phase and either water or a sodium phosphate buffer (SPB) solution (pH=7.0) as the liquid phase. The synthetic CPC was characterized by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The setting reaction in the SPB solution involved three phase transformations. Firstly, MCPM and CaCO₃ reacted with sodium phosphate immediately to form dicalcium phosphate dehydrate (DCPD) which continued to dissolve. Secondly, meanwhile, an intermediate amorphous calcium phosphate (ACP) was formed. Finally, ACP transformed into calcium-deficient hydroxyapatite (CDHA). In contrast, the reaction stopped at the first stage in water. Consequently, the SPB solution not only caused the dissolution of DCPD but also provided the buffering capacity to induce the conversion of the starting materials to CDHA.     

一水合硫酸氢钠催化合成乙酸异戊酯

以一水合硫酸氢钠为催化剂催化合成了乙酸异戊酯，探讨了酯化反应条件，酯收率达９７．２％。实验结果表明一水合硫酸氢钠催化性能优良，反应条件温和，方法简便，收率优良。     

高压微波催化合成对硝基苯甲酸乙酯

以一水合硫酸氢钠为催化剂，利用高压微波技术，快速合成了对硝基苯甲酸乙酯。用正交试验研究了各反应因素对产品收率的影响，确定最佳反应条件为：以2．0g对硝基苯甲酸为准，醇酸物质的量比为4：1，催化剂用量为1．0g，微波时间为9min，微波功率为522w，产率达97．8％。     

Various instrumental and biochemical parameters as ageing indicators of beef Longissimus dorsi muscle and their relation to creatine and creatinine content

The main dietary source of creatine is red meat. Its ageing is accompanied by deep changes in chemical composition and structure of muscle tissues. The effect of ageing (nonaged—i.e. 24 h post mortem vs. 14 and 28 days post mortem at 1 °C) on the content of creatine and creatinine, on the creatine/creatinine ratio and on other ageing indicators, such as instrumentally measured colour values, pH_ultimate values, length of myofibrilar fragments and total free amino acid content of beef Longissimus dorsi muscle. Muscles originated from eight commercially slaughtered Simmental bulls, 19–20 months old. Generally, all parameters measured were influenced by ageing time at the 5% level or less. Approximately 0.1 unit higher pH values and 1 unit higher colour L ^*, a ^* and b ^* values of ageing samples compared to nonaged was found. Length of myofibrilar fragments being in average the highest (69 μm) for nonaged samples, 34 μm for 14 days aged and the lowest (17 μm) for 28 days aged sample. Higher content of total free amino acids released during 14 and 28 days of storage (10.19 and 18.71 μmol/g) than from nonaged beef (19.75 μmol/g) was found. Creatine content significantly declined with increasing days of ageing (nonaged 6.05 mg/g, 14 days 5.86 mg/g, 28 days 5.66 mg/g). On the contrary, the total content of creatine (creatine + 1.159 × creatinine) was not markedly affected by 14 days of ageing (nonaged 6.27 mg/g, 14 days 6.14 mg/g), although significant difference between nonaged and 28 days aged groups (5.95 mg/g) was observed. It was assumed that the creatinine/creatine ratio might be a good indicator of ageing rate for beef (R ² = 0.974).     

The Regulation and Expression of the Creatine Transporter: A Brief Review of Creatine Supplementation in Humans and Animals

Creatine monohydrate has become one of the most popular ergogenic sport supplements used today. It is a nonessential dietary compound that is both endogenously synthesized and naturally ingested through diet. Creatine ingested through supplementation has been observed to be absorbed into the muscle exclusively by means of a creatine transporter, CreaT1. The major rationale of creatine supplementation is to maximize the increase within the intracellular pool of total creatine (creatine + phosphocreatine). There is much evidence indicating that creatine supplementation can improve athletic performance and cellular bioenergetics, although variability does exist. It is hypothesized that this variability is due to the process that controls both the influx and efflux of creatine across the cell membrane, and is likely due to a decrease in activity of the creatine transporter from various compounding factors. Furthermore, additional data suggests that an individual's initial biological profile may partially determine the efficacy of a creatine supplementation protocol. This brief review will examine both animal and human research in relation to the regulation and expression of the creatine transporter (CreaT). The current literature is very preliminary in regards to examining how creatine supplementation affects CreaT expression while concomitantly following a resistance training regimen. In conclusion, it is prudent that future research begin to examine CreaT expression due to creatine supplementation in humans in much the same way as in animal models.     

Size dependency of citric acid monohydrate growth kinetics

An experimental study concerned with the growth kinetics of citric acid monohydrate crystals is presented. Due to the properties of the system, which is very soluble, with low solid-liquid density difference and high liquid viscosity, two different techniques were used: large crystals (710-850 μm) were growtn in a fluidized bed crystallizer; small crystals, belonging to three size ranges from 90 to 355 μm, were grown in the cell of a laser light diffraction granulometer. A first order growth kinetics resulted in both cases; a comparative analysis of both the present data and those reported in the literature relevant to larger or smaller crystals, indicates that the system exhibits size-dependent growth, which increases linearly with the crystal size.     

脱水法制备无水N-羟基丁二酰亚胺

介绍了制备N 羟基丁二酰亚胺的一般方法 ,研究了采用丁二酸酐与盐酸羟胺制备N 羟基丁二酰亚胺水合物的工艺方法 ,以及从一水合N 羟基丁二酰亚胺出发制备高纯度无水N 羟基丁二酰亚胺的方法     

水合联氨还原法制备纳米Co粉的反应条件研究

以乙二醇做溶剂,采用水合联氨还原法制备了纳米Co粉。XRD实验分析结果表明制得了纯度良好的Co粉,且粒度为16.5 nm。根据反应时的反应体系的颜色变化,推导了简化的反应过程。同时,研究了反应物中的溶剂(乙二醇)的作用和反应物浓度、成核剂含量对纳米Co粉粒度的影响。     

Effect of pre-rigor temperature incubation on sarcoplasmic protein solubility,calpain activity and meat properties in porcine muscle

The aim of the study was to investigate the effect of pre-rigor temperature incubation on sarcoplasmic protein characteristics in relation to meat properties within porcine muscle. Porcine Longissimus dorsi muscles were incubated at temperatures of 0, 10, 20, 30 and 40 °C to 6 h post mortem. Incubation at 40 °C induced a significant decrease of sarcoplasmic protein solubility and an increase in proteins in the myofibrillar fraction. The protein relocation was followed till 72 h post mortem but had largely been completed by the end of the temperature incubation at 6 h. SDS-PAGE and Western blot analyses suggested that phosphorylase and creatine kinase precipitated onto the myofilaments during incubation at 40 °C. Drip loss increased following incubation at 40 °C, indicating that the precipitation of phosphorylase and creatine kinase may be a factor of reduced water-holding capacity at the combination of high temperature and low pH. Incubation at 40 °C resulted in substantially lower shear force in parallel with loss of extractable activity of μ- and m-calpain, suggesting a rapid activation of both enzymes at high temperatures and low pH early post mortem.