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71.
72.
竹荪子实体多糖的提取及化学组成 总被引:1,自引:0,他引:1
从天然竹荪中经脱脂、采用20、40、60、80℃四个不同温度热水梯度抽提、Sevage法脱蛋白、乙醇沉淀得到四种粗竹荪多糖。对其中在60℃下提取的多糖进行研究。经测定此多糖具有较高的粘度,再对其用丙酮进行分级得到纯度较高的竹荪多糖-3。用气相色谱对其单糖组成结构进行分析,结果表明荪多糖-3是一种以葡萄糖为主的多糖,通过刚果红实验证实此多糖可能具有三螺旋结构。 相似文献
73.
Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible biopolymers. These biomaterials have grown in importance in the fields of tissue engineering and tissue reconstruction for structural applications where tissue morphology is critical, such as bone, cartilage, blood vessels, and skin, among others. Furthermore, they can be used to accelerate the regeneration in combination with drugs, as drug delivery systems, thus reducing microbial infections. When cells are cultured under stress conditions, a wide variety of microorganisms produce them as a store of intracellular energy in the form of homo- and copolymers of [R]—hydroxyalkanoic acids, depending on the carbon source used for microorganism growth. This paper gives an overview of PHAs, their biosynthetic pathways, producing microorganisms, cultivation bioprocess, isolation, purification and characterization to obtain biomaterials with medical applications such as tissue engineering. 相似文献
74.
Bruno Hivert Sylvie Bouhanna Sylvie Diochot William Camu Govindan Dayanithi Christopher E. Henderson Jean Valmier 《International journal of developmental neuroscience》1995,13(5)
Only L- and N-type high voltage-activated calcium currents (HVA ICa) have been demonstrated in identified embryonic spinal motoneurons. However, pharmacological experiments suggest that other HVA ICa, including P-type, govern neurotransmitter release at the adult neuromuscular junction. We sought to analyse if embryonic motoneurons express these other ICa, using the whole-cell voltage-clamp method on motoneurons purified by a new metrizamide-panning technique from E15 rat embryos. In addition to L-type dihydropyridine-sensitive and N-type ω-GVIA-sensitive currents, motoneurons express two other HVA ICa. One has properties related to the P-type channel currents described in Purkinje cells: it is inhibited by the peptide ω-agatoxin-IVA with a maximal effect at 100–200 nM. The inhibited current has a characteristic sustained component during depolarizing test pulses. Furthermore, 50–100 nM concentration of ω-agatoxin-IVA reduce the increase in cytoplasmic calcium concentration observed after depolarization. The other HVA ICa is resistant to saturating concentrations of verapamil, ω-conotoxin GVIA and ω-agatoxin-IVA which block L, N and P-type HVAICa, respectively. These results suggest that it is now possible to dissect, using a simple method of purification, the properties of the ICa in embryonic mammalian motoneurons and to provide pharmacological evidence for multiple calcium channels which may be involved in regulation of their activity during development. 相似文献
75.
采用丙酮粉沉淀抽滤法、硫酸铵分级沉淀法及苯基琼脂糖疏水性层析法对高灌蓝越橘多酚氧化酶进行提取和纯化。在提取和纯化中,用加入不同的酚吸收剂和抑制剂并比较酶活性的高低来确认最佳方法。结果表明在粗提中加入酚吸收剂、增溶剂和抑制剂提取效果较好,苯基琼脂糖疏水性层析法对此类酶纯化效果较佳并为后来的辅酶的分离提供了较高的纯化倍数。 相似文献
76.
The general preparation method for V2O5 is ammonium salt vanadium precipitation, which inevitably produces large amounts of ammonia nitrogen wastewater. In this paper, we propose an environmentally friendly method for preparing high-purity V2O5 with low ammonium consumption. The purity of the V2O5 product reaches more than 99% while reducing the level of ammonium consumption. The vanadium precipitation efficiency reaches 99.23% and the V2O5 purity of the product reaches 99.05% under the following conditions: precipitation time of 1.5 h, precipitation temperature of 98 °C, initial precipitation pH of 2, ammonium addition coefficient of 2, purification time of 5 min with purification performed twice, purification temperature of 65 °C. In this study, compared with the use of ammonia spirit for vanadium precipitation and ammonium salt vanadium precipitation, the ammonia consumption levels are reduced by 79.80% and 80.00%, and the purity levels are increased by 0.70% and 1.01%, respectively. The compositions of the precipitated (NaV3O8∙xH2O) and purified ((NH4)2V6O16·1.5H2O) hydrolysis products are characterized via XRD. The TGA results show that NaV3O8∙xH2O contains 1.5 times the amount of crystal water. The FTIR results explain that the two V3O8− layers are combined end-to-end to form a V6O162− layer. The change of the product image indicates that the purification process includes three stages. Firstly, heating and NH4+ attack expand the V3O8− layer. NH4+ diffuses more easily into the V3O8− layer. Secondly, NH4+ destroys the electrostatic interaction between Na+ with the V3O8− layer and replacing Na+. Finally, V3O8− is polymerized into V6O162− to keep the crystal structure stable. 相似文献
77.
The contamination of potential mycotoxins in tea production and consumption has always been a concern. However, the risk monitoring on multiple mycotoxins remains a challenge by existing methods due to the high cost and complex operation in tea matrices. This research has developed a simple ultra-performance liquid chromatography-tandem mass spectrometry strategy based on our homemade purification column, which can be applied in the detections of mycotoxins in complex tea matrices with high-effectively purifying and removing pigment capacity for 16 mycotoxins. The limits of detection and the limits of quantification were in the ranges of 0.015~15.00 and 0.03~30.00 µg·kg−1 for 16 mycotoxins, respectively. Recoveries from mycotoxin-fortified tea samples (0.13~1200 µg·kg−1) in different tea matrices ranged from 61.27 to 118.46%, with their relative standard deviations below 20%. Moreover, this method has been successfully applied to the analysis and investigation of the levels of 16 mycotoxins in major categories of tea and the monitoring of multiple mycotoxins in processed samples of ripened Pu-erh. In conclusion, the proposed strategy is simple, effective, time-saving, and low-cost for the determination of a large number of tea samples. 相似文献
78.
介绍三聚磷酸二氢铝的性质、合成工艺及应用。采用湿法磷酸净化替代热法磷酸可降低成本,将成为今后此类防锈颜料的发展方向。特别提到昆明理工大学精细化工教研室,开展了肥料级磷酸一铵水溶液添加一定的净化剂,可使磷酸一铵水溶液达到合成三聚磷酸二氢铝的要求。该法称为磷酸一铵净化法,有望成为取代热法磷酸的理想方法。 相似文献
79.
《Vaccine》2018,36(22):3153-3160
The continuously increasing demand for potent and safe vaccines and the intensifying economic pressure on health care systems underlines the need for further optimization of vaccine manufacturing. Here, we focus on downstream processing of human influenza vaccines, investigating the purification of serum-free cell culture-derived influenza virus (A/PR/8/34 H1N1) using continuous chromatography. Therefore, quaternary amine anion exchange monoliths (CIM® QA) were characterized for their capacity to capture virus particles from animal cells cultivated in different media and their ability to separate virions from contaminating host cell proteins and DNA. The continuous chromatography was implemented as simulated moving bed chromatography (SMB) in a three zone open loop configuration with a detached high salt zone for regeneration.SMBs exploiting 10% and 50% of the monoliths’ dynamic binding capacity, respectively, allowed the depletion of >98% of the DNA and >52% of the total protein. Based on the hemagglutination assay (HA assay), the virus yield was higher at 10% capacity use (89% vs. 45%). Both SMB separations resulted in a ratio of total protein to hemagglutinin antigen (based on single radial diffusion assay, SRID assay) below the required levels for manufacturing of human vaccines (less than 100 µg of protein per virus strain per dose). The level of contaminating DNA was five-times lower for the 10% loading, but still exceeded the required limit for human vaccines. A subsequent Benzonase® treatment step, however, reduced the DNA contamination below 10 ng per dose. Coupled to continuous cultivations for virus propagation, the establishment of integrated processes for fully continuous production of vaccines seems to be feasible. 相似文献
80.
刘春峰 《中华实用儿科临床杂志》2020,(18):1365-1368
血液净化技术是重症患者治疗的一个有效手段,已从单纯肾替代扩展到多种疾病的治疗和多器官功能障碍的支持治疗,近来血液净化技术取得了长足的发展,杂交式血液净化技术可用于不同疾病和不同毒物的清除。重症患者由于病情复杂,疾病变化快,需要个体化地制定血液净化方案。虽然血液净化技术在儿科重症监护病房的使用普及度较高,但仍不够规范,也存在盲目或过度使用的情况,儿童相关的循证证据较少,需要今后进行更多的临床研究工作。 相似文献