The effects of washing a collagen sample prior to TEM examination

Transmission electron microscopy (TEM) is an important analysis technique to visualize (bio)macromolecules and their assemblies, including collagen fibers. Many protocols for TEM sample preparation of collagen involve one or more washing steps to remove excess salts from the dispersion that could hamper analysis when dried on a TEM grid. Such protocols are not standardized and washing times as well as washing solvents vary from procedure to procedure, with each research group typically having their own protocol. Here, we investigate the influence of washing with water, ethanol, but also methanol and 2-propanol, for both mineralized and unmineralized collagen samples via a protocol based on centrifugation. Washing with water maintains the hydrated collagen structure and the characteristic banding pattern can be clearly observed. Conversely, washing with ethanol results in dehydration of the fibrils, often leading to aggregation of the fibers and a less obvious banding pattern, already within 1 min of ethanol exposure. As we show, this process is fully reversible. Similar observations were made for methanol and propanol. Based on these results, a standardized washing protocol for collagenous samples is proposed.     

基质囊泡及其在骨矿化过程中的作用

基质囊泡(Matrix vesicles,MVs)是骨矿物初始形核生长的场所。骨矿化过程中,钙、磷酸根等离子经通道蛋白跨膜运输进入MVs内,当局部浓度达到一定值时,磷酸钙晶体开始沉积。磷酸钙的存在形态包括无定形磷酸钙、磷酸八钙及羟基磷灰石等。MVs可以调节细胞内外基质中的钙和磷酸根离子的稳态及无机磷酸盐/无机焦磷酸盐的比值,提供磷酸钙晶体成核位点,在骨矿化的初始启动过程中发挥重要作用。本文概述了MVs的生物来源、分子组分、提取方法,MVs介导的骨矿化过程,以及近年来利用囊泡作为体外矿化模型模拟MVs矿化过程的研究进展。     

Development of Core-Shell Nanoparticle Drug Delivery Systems Based on Biomimetic Mineralization

Among various drug-delivery systems, core-shell nanoparticles have many advantages. Inspired by nature, biomimetic synthesis has emerged as a new strategy for making core-shell nanoparticles in recent years. Biomimetic mineralization is the process by which living organisms produce minerals based on biomolecule templating that leads to the formation of hierarchically structured organic–inorganic materials. In this minireview, we mainly focus on the synthesis of core-shell nanoparticle drug-delivery systems by biomimetic mineralization. We review various biomimetic mineralization methods for fabricating core-shell nanoparticles including silica-based, calcium-based and other nanoparticles, and their applications in drug delivery. We also summarize strategies for drug loading in the biomolecule-mineralized core-shell NPs. Current challenges and future directions are also discussed.     

贵州三穗地区钒矿地质特征及成矿规律研究

总结贵州省三穗地区钒矿矿区地层、区域构造和区域岩浆岩特征，探讨矿区钒矿成矿规律。研究表明：区内钒矿赋存在陡山沱组白云岩的上部以及老堡组和九门冲组的下部，含矿岩性为黑色炭质黏土岩；成矿来源主要是由于海底裂谷的热气流作用，携带深部钒等多金属元素向陆棚与台地运动、迁移，出现钒的横向分导现象；沉积下来的钒金属又在后期低温热液作用下，以水云母的形式存在，而炭质吸附的部分钒元素进入水云母晶格中，形成钒矿。     

基于地球化学的水热还原矿化稳定砷的技术思路

砷作为有色金属矿物的共伴生元素,在有色金属冶炼过程中以含砷“三废”形式大量产出。由于砷具有强致癌性及毒性,导致砷的安全处置问题严重困扰着有色金属冶炼企业。本文通过阐述含砷废水中砷的两种稳定化工艺的研究进展,对比了现有稳定化工艺的优缺点,结合药剂稳定化和矿物稳定化的优点,借鉴砷元素在地球化学中的成矿规律,提出了硫化沉砷?水热还原矿化稳定砷的技术思路。首先采用硫化法脱除含砷废水中的砷,砷的沉淀率高达99.65%,硫化沉淀物在TCLP毒性检测中砷的浓度达到212.9 mg/L。然后采用As-S系一元水热还原矿化法和As-Fe-S系二元水热还原矿化方法稳定砷,稳定化产物分别为雌黄和雌黄?铁硫系(黄铁矿、硫化亚铁)混合物,在TCLP毒性检测中砷的浸出浓度分别为3.86 mg/L和2.65 mg/L。水热还原矿化工艺实现了含砷废水中砷的脱除及稳定化的目的,为水溶液中砷的脱除和稳定化提供了新的思路。     

粤东桃源地区中新生代构造演化与铀成矿

利用节理构造、擦痕滑动矢量反演法等构造应力场研究方法,结合区内地质特征及区域构造演化,系统分析了桃源地区构造应力作用的方向和期次,进行构造应力场期次的划分,推测区内由早至晚经历了近SN向挤压、近EW向挤压、近EW向拉张、NW-SE向的挤压、NW-SE向拉张等主要构造应力作用。初步探讨了区域构造应力场演化与铀成矿作用之间的关系,进而预测铀富集成矿的有利构造部位。认为区内的NEE、NWW向断裂为近EW向挤压应力产生的一组共轭断裂,具有相似的成矿潜力。前人探索较少的NWW向断裂,为下步找矿重点。     

青海也日更金铜镍多金属矿地质特征与找矿远景

青海省海西地区是中国西北一个非常重要的金属及非金属成矿区。也日更金铜镍多金属矿床周边古老变质岩系发育,华里西期、印支期构造岩浆活动频繁并且强度大,构造作用较复杂,近EW向和NWW向断裂构造及受其控制的中酸性脉岩发育,围岩蚀变现象明显,局部地段显示了较为明显的金、铜、镍等多金属矿化,同时有1∶50000及1∶25000化探综合异常显示,1∶5000地物化剖面异常清晰,最后通过探槽工程揭露,显示出该区具有较好的成矿远景。     

The unreliability of the kinetic approach to measuring bacterial mineralization activities at low in situ temperatures in an acidic aquatic environment

This paper concerns the kinetic approach to measuring glucose mineralization by planktonic bacteria in Whitson Lake, a moderately acidic lake. For all three samplings, plots of the amount of glucose mineralized vs time of incubation were linear at both high and low concentrations of added glucose. When sample water buffered around the in situ pH was used in these time studies, linear relationships were again evident, but there was a reduction in the rates of glucose mineralization activity. Nevertheless, the kinetic approach usually failed to generate the Michaelis—Menten response at the necessary level of statistical significance to justify calculations of turnover times and V_max values. And, buffering the pH around the in situ pH did not insure that the Michaelis—Menten response would be obtained.These observations are discussed in the light of our earlier observations involving an extremely acid-stressed lake.     

Precipitation recovery of boron from wastewater by hydrothermal mineralization

It is well known that boric acid exhibits various toxic effects on plant, animal and human beings even at very low concentrations. Thus, the development of boron-removal technique from wastewater has been intensively investigated. In this study, a new hydrothermal treatment technique was developed to recover boron as recyclable precipitate Ca(2)B(2)O(5).H(2)O from aqueous solutions. As a result, it was found that the hydrothermal treatment using calcium hydroxide as a mineralizer converted boron in the aqueous media effectively into calcium borate, Ca(2)B(2)O(5).H(2)O. In the optimal hydrothermal condition, more than 99% of boron was collected from the synthetic wastewater of 500 ppm. Thus, the present hydrothermal treatment in the presence of calcium hydroxide is recommended as one of the effective techniques to recover boron from aqueous media.