Single-step assembly of polymer-lipid hybrid nanoparticles for mitomycin C delivery

Mitomycin C is one of the most effective chemotherapeutic agents for a wide spectrum of cancers, but its clinical use is still hindered by the mitomycin C (MMC) delivery systems. In this study, the MMC-loaded polymer-lipid hybrid nanoparticles (NPs) were prepared by a single-step assembly (ACS Nano 2012, 6:4955 to 4965) of MMC-soybean phosphatidyhlcholine (SPC) complex (Mol. Pharmaceutics 2013, 10:90 to 101) and biodegradable polylactic acid (PLA) polymers for intravenous MMC delivery. The advantage of the MMC-SPC complex on the polymer-lipid hybrid NPs was that MMC-SPC was used as a structural element to offer the integrity of the hybrid NPs, served as a drug preparation to increase the effectiveness and safety and control the release of MMC, and acted as an emulsifier to facilitate and stabilize the formation. Compared to the PLA NPs/MMC, the PLA NPs/MMC-SPC showed a significant accumulation of MMC in the nuclei as the action site of MMC. The PLA NPs/MMC-SPC also exhibited a significantly higher anticancer effect compared to the PLA NPs/MMC or free MMC injection in vitro and in vivo. These results suggested that the MMC-loaded polymer-lipid hybrid NPs might be useful and efficient drug delivery systems for widening the therapeutic window of MMC and bringing the clinical use of MMC one step closer to reality.     

随机截尾机电设备三参数威布尔分布模型及其应用研究

针对某型飞机机电设备故障率较高的实际问题,提出首先采用平均秩次法进行故障数据预处理,其次假设数据服从三参数威布尔分布并采用相关系数优化法和最小二乘法相结合求得相关参数,最后采用K-S检验法和蒙特卡洛仿真模拟,对可靠性评估结果进行了检验.通过实例验证得出,提出的模型可以准确地描述机电设备在实际使用环境中的故障情况,计算过程简单,便于编程实现.     

Applied electric field on the reaction between submerged entry nozzle and alloy in the steel

In this study, the reactivity between nozzle and submerged entry nozzle and alloy elements in the steel (Al and Ce) under different electric field conditions was investigated. The results show that the decarburization of the nozzle is an important factor affecting the clogging behavior and steel quality. The external electric field directly affects and changes the decarburization, clogging, and reaction behavior between the nozzle and alloy in the steel. If the chemical reaction force between alloys and the nozzle is greater than the applied electric field force in actuality, the clogging will also occur on the submerged entry nozzle. In the future, this new method of controlling and changing the interfacial electric fields can be used to solve the problem of decarburization and clogging of the submerged entry nozzle.     

一种新型10 kV双环网结构

通过比对国内外配电网网架情况,提出一种新的10kV双环网结构,并应用在实际案例中,结果表明该结构在满足负荷、可靠性的要求下,能够有效降低线路半径、节约投资.     

社会交通发展的文化性与包容性思考

通过参加北京市交通委组织的交通行业节能减排国际高研班的学习交流,反思了目前社会交通存在的问题与制约瓶颈,通过对社会交通及交通行业发展的思考,得出如下结论:社会交通的发展,是社会文化发展的最终产物,社会文化的多元性决定了社会交通发展的综合性、集成性与包容性。     

Adaptive estimation and nonlinear variable gain compensation of the contouring error for precise parametric curve following

Contour following is one of the most important issues faced by many computer-numerical-control (CNC) machine tools to achieve high machining precision. This paper presents a new real-time error compensation method aiming at reducing the contouring error caused by facts such as servo lag and dynamics mismatch in parametric curved contour-following tasks. Due to the lack of high-precision contouring-error estimation method for free-form parametric curved toolpath, the error can hardly be compensated effectively. Therefore, an adaptive accurate contouring-error estimation algorithm is proposed first, where a tangential-error backstepping method based on Taylor’s expansion is developed to rapidly find the closest point on the parametric curve to the actual motion position. On this foundation, the contouring error is compensated using a proposed nonlinear variable-gain compensation method, where the compensation gain is obtained according to not only the contouring-error magnitude but also its direction variation. The stability of the system after compensation is analyzed afterwards according to the Jury stability criterion. By design of the compensator in accordance with the presented contouring-error compensation method as well as the stability analyzation result, the balance between the response speed and the contour control stability can be effectively made. Experimental tests demonstrate the feasibility of the presented methods in both contouring-error estimation and contour-accuracy improvement. Contributions of this research are significant for enhancing the contour-following performance of the CNC machine tools.     

Biodegradation of Potamogeton pectinatus biomass by hydrogen and methane coproduction: Effect of different pretreatments and parallel factor analysis

To enhance the hydrogen and methane coproduction potential, three pretreatments (i.e., acid, alkali and cellulase) were investigated during a two-stage anaerobic fermentation using Potamogeton pectinatus biomass. The fluorescence spectral characteristics of the dissolved organic matter (DOM) from the two-stage effluents, coupled with parallel factor analysis, were studied. The maximum hydrogen proportions (42.65%) and production rate (4.1 mL h^?1) were obtained under the 0.5 mol L^?1 HCl pretreatment. The highest methane proportions (52.82%) and production rate (14.2 mL h^?1) were observed under the 0.5 mol L^?1 HCl and 10 mg g^?1 cellulase pretreatments, respectively. Combined with fluorescence spectra and parallel factor analysis, three fluorescent components were identified, and the protein-like substances were determined to be dominant. Using the acid pretreatment, the change of the maximum fluorescence intensities in the DOM was the most significant among the three pretreatments, followed by that of the cellulose pretreatment. The result indicated that the macromolecular substances in P. pectinatus can be decomposed by effective pretreatment and thereby enhances the hydrogen and methane coproduction potential. This technique represents a promising method for improving cellulosic biomass biodegradation and green energy coproduction.     

黑龙江省新林—呼中地区水系沉积物地球化学特征及找矿意义

在新林—呼中地区森林沼泽-冻土景观区,开展1∶50 000水系沉积物测量,探讨该区水系沉积物中元素含量分布、元素组合特征和区域地球化学异常特征,为下一步划分成矿远景区,开展地球化学找矿提供依据。结果显示:该区具备中高温热液型Cu、Pb、Mo、Au多金属矿成矿条件;早白垩世二长花岗岩区和白音高老组火山岩区Cu、Pb、Zn、Mo、Au显著富集,强烈分异,是寻找Pb、Cu、Mo、Au多金属矿化(床)的有利地段;区域异常与燕山早期酸性侵入体密切相关,应是晚侏罗世—早白垩世岩浆侵入、喷发以及构造运动强烈作用的结果。     

Fabrication and electromagnetic wave absorption property of quartz ceramics with a gradient distribution of BaTiO3

Quartz ceramics with a uniform/gradient distribution of BaTiO₃ (U/G–SO–BTO) are fabricated by cold pressing a powder blend with BTO followed by sintering and using a combined technique of spreading the powder blends with gradually increased BTO layer–by–layer and sintering. The electromagnetic wave absorption properties of these two ceramics are studied in detail. For U–SO–BTO samples, the primary electromagnetic reflection is strong due to the aggravated impedance mismatch at their surfaces. The electromagnetic wave reflectivity of U–SO–BTO could only reach ?7.0?dB when the sample thickness is 6?mm and the BTO content is 8.0?wt%, and it decreases slightly to ?8.1?dB when the sample thickness is increased to 10.0?mm and the BTO content is decreased to 5.0?wt% simultaneously. For G–SO–BTO samples, electromagnetic waves could enter with little reflection due to the weak surface impedance mismatch, and the electromagnetic waves entering these samples could propagate forward while being absorbed gradually with little reflection because of the weak impedance mismatch at the interfaces. The G–SO–BTO samples are promising excellent electromagnetic absorbing materials because their electromagnetic wave reflectivity could reach a level lower than ?12.0?dB and could decrease further from –12.2 to ?13.1?dB as the layer thickness increases from 1.0 to 2.0?mm.     

Study on the dissolved oxygen control strategy in large‐scale vitamin B12 fermentation by Pseudomonas denitrificans

BACKGROUND: There are two different routes for vitamin B₁₂ biosynthesis, which results in discrepancies and uncertainties of the dissolved oxygen (DO) concentration for vitamin B₁₂ fermentation. In this paper, the DO control strategy was explored for industrial vitamin B₁₂ fermentation by Pesudomonas denitrificans in 120000‐L fermenter. RESULTS: A DO‐stat strategy was first successfully scaled up from a 9000 L fermenter to a 120 000 L fermenter. Then a multi‐stage DO control strategy was further established in the 120 000 L fermenter, in which the DO level was shifted from 8–10% (20–48 h) to 2–5% (49–106 h) and below 2% (107–168 h) by gradually reducing the rate of aeration and agitation. As a result, 198.80 mg L^?1 of vitamin B₁₂ was obtained, which was significantly higher than those obtained under the fermentations with one‐stage DO control. CONCLUSIONS: The comparatively low DO level was favorable for vitamin B₁₂ biosynthesis, but it would have an extremely negative effect on cell growth. Compared with the low DO level maintained at all times of the fermentation process, a multi‐stage DO control strategy could not only increase the biomass but also improve vitamin B₁₂ biosynthesis. Copyright © 2012 Society of Chemical Industry