EQCN based cholinesterase biosensors

The binding of acetylcholinesterase (AChE) to a propidium-modified piezoelectric quartz crystal and its surface enzymatic activity have been investigated.Propidium binds to a site remote to the active center of AChE - the peripheral anionic site (PAS) - which is located on the rim of the gorge to the active site.The gold electrodes of the quartz crystal were first modified with 11-mercaptoundecanoic acid to which propidium was coupled. AChE binding was monitored by a quartz crystal nanobalance (QCN), followed by amperometric activity evaluation of the AChE loaded on the sensor. Interestingly, the binding is strong but does not inhibit AChE. However, an excess of propidium in solution inhibits the immobilized enzyme. The surface enzymatic activities observed depend on the amount of enzyme and differ according to the type and species, i.e. number of enzyme subunits (Electrophorus electricus tetrameric, Drosophila melanogaster mono- and dimeric form - DmAChE).The operational stability and regeneration, effect of propidium in solution and detection limit for substrate for various AChEs were investigated amperometrically.     

DESIGN OF A SIMPLE LOW-COST QUARTZ CRYSTAL MICROBALANCE SYSTEM

This article describes a simple design of a low-cost, real-time, and computerized quartz crystal microbalance system. The system measures resonance frequencies up to 6 MHz with a resolution of 1 Hz, i.e., it can monitor mass change in the range of nano-gram and thickness change in the range of micrometer. The designed system consists of three main parts: input circuitry, control, and counting parts. In the input circuitry, three separated input signals types are allowable: the first is direct TTL compatible, the second is analog signal, while the third is the signal that may come from the quartz crystal microbalance. The last two signals are converted to TTL signals using wave-shaping circuitry. The control part is interfaced with the status and control ports of the computer LPT1 parallel port. It consists of time base circuitry and different multiplexers to control data sending to computer according to the input signal under investigation. The counter consists of six binary counters in cascade and directly interfaced to the computer through the LPT1 data port; the transfer process was carried out by two different ways according to the measuring mode of the system. All parts were controlled by specially designed software. Finally, the frequency readings of the quartz crystal microbalance were found to be in good agreement with those of a frequency counter model GFC-8055G connected in parallel during an experiment performed to test the system.     

Reusable hydroxyapatite nanocrystal sensors for protein adsorption

Abstract

The repeatability of the adsorption and removal of fibrinogen and fetal bovine serum on hydroxyapatite (HAp) nanocrystal sensors was investigated by Fourier transform infrared (FTIR) spectroscopy and quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The HAp nanocrystals were coated on a gold-coated quartz sensor by electrophoretic deposition. Proteins adsorbed on the HAp sensors were removed by (i) ammonia/hydrogen peroxide mixture (APM), (ii) ultraviolet light (UV), (iii) UV/APM, (iv) APM/UV and (v) sodium dodecyl sulfate (SDS) treatments. FTIR spectra of the reused surfaces revealed that the APM and SDS treatments left peptide fragments or the proteins adsorbed on the surfaces, whereas the other methods successfully removed the proteins. The QCM-D measurements indicated that in the removal treatments, fibrinogen was slowly adsorbed in the first cycle because of the change in surface wettability revealed by contact angle measurements. The SDS treatment was not effective in removing proteins. The APM or UV treatment decreased the frequency shifts for the reused HAp sensors. The UV/APM treatment did not induce the frequency shifts but decreased the dissipation shifts. Therefore, we conclude that the APM/UV treatment is the most useful method for reproducing protein adsorption behavior on HAp sensors.     

大湖金矿金赋存状态的研究

大湖金矿为典型的石英脉型金矿，该矿含金8.7g/t，绝大多数金粒以微细粒状与黄铁矿和黄铜矿紧密连生，金粒以裂隙金和粒间金为主，包裹金所占比例较少，矿石中金的理论回收率为95.6%。     

高纯石英制备技术评述

石英砂提纯是通过预处理,初提纯及精提纯等选矿工艺除去石英砂中少量或微量杂质以获得高纯石英砂,本文从煅烧水淬处理、磨矿、擦洗、磁选、浮选、浸出等石英砂提纯工艺方面进行评述,并指出了石英提纯应遵循的基本原则,这对制备高纯石英砂具有重要的意义。     

Immobilization of Radioactive Wastes in Hydrothermal Synthetic Rock, (III)

The high-level radioactive waste form (21.8w/o waste, 47.7w/o α-quartz, 20.5w/o amorphous aluminosilicate, 10w/o Al(OH)₃) was produced with the addition of 10-N NaOH solution under hydrothermal hot-pressing conditions at 350°C and 66 MPa for 6 h. In order to characterize the waste form, following tests and measurements were performed: Soxhlet flow leach tests (97°C), static leach tests in deionized water at low temperatures (40, 90°C) and under hydrothermal conditions (100–350°C), crystalline phase determination, microstructure observation, compressive strength measurement, weight loss measurement by heat treatment and thermal conductivity measurement.

The waste form was mainly composed of α-quartz and had porous structure. As for leach rates determined by static low temperature leach tests, the leach rates of the waste form were much lower than a concrete form but slightly higher than a glass form. The waste form was stable under hydrothermal conditions in comparison with a glass form. It had high compressive strength and thermal resistance. Its thermal conductivity was higher at room temperature than that of a glass form.     

石英细脉型复杂钨钼多金属矿石工艺矿物学研究

结合传统工艺矿物学研究方法,采用MLA自动检测方法对某石英细脉型钨钼多金属矿石进行工艺矿物学研究,研究结果表明：该矿石中钨矿物以黑钨矿为主,并且白钨矿交代黑钨矿现象较普遍,形成有具黑钨矿外形,而化学组成为白钨矿的假象白钨矿。矿石中黑钨矿、白钨矿的嵌布粒度相似,以白钨矿略粗,嵌布粒度主要在0．02～0．32mm范围。钼主要以辉钼矿矿物形式存在,嵌布粒度较粗,主要在0．04～0．64mm范围。当磨矿细度为-0．074mm占38．17％时,钨矿物总解离度为79．61％,辉钼矿总解离度为88．34％。此外矿石中伴生铋和银,铋矿物种类复杂,并且是银的主要载体,银可随铋的富集得以回收。钨钼铋的赋存状态研究表明,该矿石钨的理论回收率较高。     

碱处理对脉石英酸浸提纯影响试验研究

随着光伏新能源、电子信息等领域的快速发展,高纯石英砂的应用领域越来越广泛,需求量逐年增大,可加工高纯石英砂的高品质石英矿原料逐渐减少,针对中低品质脉石英的选矿提纯技术的开发至关重要。论文在脉石英常规提纯方法基础上,使用碱浸辅助处理,以提高中低品质脉石英的纯度,对高纯石英砂的制备技术开发具有重要意义。论文开发出焙烧-水淬-磁选-浮选-碱处理-酸浸的提纯工艺,系统研究了碱处理条件对酸浸精矿质量的影响,结果表明,使用KOH溶液、碱处理温度为40℃、KOH溶液浓度为0.5mol/L、处理时间为4h的条件下,获得最佳提纯效果,石英精矿中Al含量由常规工艺获得的296.79μg/g降低为245.49μg/g。扫描电子显微镜分析得出,在经过碱处理之后,脉石英表面被碱溶液部分侵蚀,使得在酸处理过程中酸溶液可以更好的与杂质矿物接触,以对杂质矿物达到更好的去除效果。     

多羧基有机大分子抑制剂在赤铁矿反浮选脱硅中的应用

本文考察了HAPMA和ASPMA两种新型多羧基有机大分子抑制剂对赤铁矿和石英浮选行为的影响,同时考察了其对人工混合矿浮选分离的影响。研究发现当pH大于9时,80 mg/L的HAPMA和ASPMA均能够有效的选择性抑制赤铁矿纯矿物,且对石英纯矿物可浮性的影响不大;在pH 11时,60 mg/L的HAPMA和ASPMA即可实现人工混合矿的浮选分离,铁精矿Fe品位分别为58.25%和61.76%、回收率分别为90.8%和81.4%。基团电负性计算和Zeta电位测试结果证实HAPMA和ASPMA能够与赤铁矿作用并吸附于赤铁矿表面从而起到抑制赤铁矿的目的。     

冀东麻地岩体铷等稀有金属元素赋存特征

麻地岩体发生铷等稀有金属元素矿化,有形成大型稀有金属矿床的远景。为了查明麻地岩体稀有金属元素赋存特征,扩大找矿成果,依据区域地质资料和前人研究成果,开展野外地质调查与样品测试。在显微岩石学研究的基础上进行了电子探针分析,明确了麻地岩体稀有金属元素赋矿岩石的组构特征与矿物特征,分析了稀有金属元素的赋存状态,探讨了稀有金属元素富集机理。认为稀有金属元素偏向于在岩浆演化的晚期阶段富集,云母容纳稀有金属元素的能力强于钾长石,但钾长石的含量远大于云母,故岩体中钾长石的稀有元素总量高于云母。