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991.
采用水溶液聚合法制备了低分子量聚丙烯酸钾(PAAK),并作为新型消焰剂加入单基发射药中。通过火焰原子吸收光谱法测试了PAAK中钾的含量;用乌氏黏度计测定了特性黏度;采用DSC法研究不同pH值的PAAK与硝化棉(NC)的相容性;利用充氮氧弹法对添加PAAK、硝酸钾KNO3、硫酸钾K2SO4的单基发射药的燃烧残渣进行了对比研究。结果表明,合成的PAAK中,钾的质量分数为15.21%,相对分子量在3 000左右,有利于和NC均匀混合,且在中性或微碱性(pH=7.0~7.5)的情况与NC相容性良好。与传统的KNO3、K2SO4消焰剂相比,PAAK能够和NC均匀混合,制备均质透明的单基发射药;PAAK发射药的燃烧残渣最少,占发射药质量的0.18%。 相似文献
992.
993.
《Drug development and industrial pharmacy》2013,39(9):1263-1272
In recent years, nanosponges (NS) have gained tremendous impetus in drug delivery through nanotechnology. Nanosponges are capable of providing solutions for several formulation related problems. Through this review, scientists working in the field of nanotechnology can have an insight into the techniques of preparation, characterization and applications of NS. Owing to their small size and porous nature they can bind poorly-soluble drugs within their matrix and improve their bioavailability. They can be crafted for targeting drugs to specific sites, prevent drug and protein degradation and prolong drug release in a controlled manner. This review attempts to elaborate different schemes of synthesis of NS and their characterization. Factors affecting drug loading and release have been enumerated. Due to their advantages, NS have not only been explored for their pharmaceutical applications but also have large popularity in allied sciences, especially in water purification. 相似文献
994.
《Journal of Nuclear Science and Technology》2013,50(8):669-677
An incineration method for plutonium recovery from α contaminated organic compounds in a flow of controlled oxygen gas is stated. The species of such thermal decomposition products as hydrocarbons, free carbon, carbon monoxide and hydrogen were determined by mass spectrography. The mixture of the products which are the source of tar or soot was converted to CO2 and H2O in contact with copper oxide catalyst without flaming. This incineration method is composed of two stages. The first stage is the decomposition of organic compounds in the streams of gas mixtures containing oxygen in low ratios. The second stage is the incineration of the decomposition products by catalytic reaction in the streams of gas with higher oxygen ratios. Plutonium was recovered as the form of plutonium dioxide from the incineration residues of the first stage. The behavior of oil was examined as a representative of liquid organic compounds. It was found to evaporate below ca. 500°C, but was completely incinerated by the catalytic reaction with copper oxide catalyst in the flow of gas with controlled oxygen amount and was changed to CO2 and H2O. 相似文献
995.
Xinguo Li 《国际能源研究杂志》2016,40(12):1624-1637
Based on organic Rankine cycle (ORC), a trapezoidal cycle with theoretical model is proposed and built according to the trapezoidal configuration and the thermodynamic relation in T–s diagram. Simulations show that the relative deviation between trapezoidal cycle and ORC is lower than 5% within evaporation temperature of 5 °C lower than the critical temperature of the working fluids. Empirical equations to calculate the optimal evaporation temperature, the maximum net power output and the corresponding thermal efficiency are built, which relative deviations from ORC are lower than 4%. Trapezoidal cycle can break through the restrictions of the actual working fluids and the configuration of the ORC to extend the study of the ORC and investigate the general principle of the ORC (or the trapezoidal cycle). Trapezoidal cycle can develop to trilateral cycle or Carnot cycle, which are the boundary cycles of the trapezoidal cycle. Trapezoidal cycle can be used as a general cycle to investigate the relations and principles among the trilateral cycle, Carnot cycle and trapezoidal cycle (or ORC). The performance of these three cycles at maximum power and their relations are investigated in the same conditions of finite heat source. Results show that the maximum power and the corresponding thermal efficiency of the trapezoidal cycle are bounded between Carnot cycle and trilateral cycle. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
996.
Degradation kinetics of total phenolic compounds,capsaicinoids and antioxidant activity in red pepper during hot air and infrared drying process 下载免费PDF全文
Jinfeng Bi Jianyong Yi Qinqin Chen Xinye Wu Mo Zhou 《International Journal of Food Science & Technology》2016,51(4):842-853
Degradation kinetics of total phenolic compounds, capsaicinoids and antioxidant activity in red pepper during both hot air drying and infrared drying were investigated, as well as the correlation between antioxidant compounds and antioxidant capacity was discussed in current study. The fractional conversion kinetic and first order kinetic models were proved to describe the changes of total phenolic compounds vs. drying time and moisture content, respectively. Degradation of capsaicinoids and antioxidant capacity vs. drying time and moisture content both followed fractional conversion kinetic model. Infrared drying accelerated the degradation rate of total phenolic compounds and capsaicinoids vs. drying time as compared with hot air drying at the same temperature; however, a contrary result was found that infrared drying decreased the degradation rate of both total phenolic compounds and capsaicinoids vs. moisture content. Total phenolic compounds exhibited a stronger relationship with antioxidant capacity of red pepper analysed by multiple linear regression analysis. 相似文献
997.
Cristina Porojan Simon M. Mitrovic Darren C. J. Yeo 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(10):1570-1586
Blue-green algae are responsible for the production of different types of toxins which can be neurotoxic, hepatotoxic, cytotoxic and dermatotoxic and that can affect both aquatic and terrestrial life. Since its discovery the neurotoxin β-methylamino-L-alanine (BMAA) has been a cause for concern, being associated with the neurodegenerative disease amyotrophic lateral sclerosis/Parkinsonism–dementia complex (ALS/PDC). The initial focus was on Guam where it was observed that a high number of people were affected by the ALS/PDC complex. Subsequently, researchers were surprised to find levels of BMAA in post mortem brains from Canadian patients who also suffered from ALS/PDC. Recent research demonstrates that BMAA has been found at different levels in the aquatic food web in the brackish waters of the Baltic Sea. There is emerging evidence to suggest that sand-borne algae from Qatar can also contain BMAA. Furthermore, there is now concern because BMAA has been found not only in warmer regions of the world but also in temperate regions like Europe. The aim of this review is to focus on the methods of extraction and analysis of the neurotoxic non-protein amino acid BMAA. We also consider the neurotoxicity, aetiology, and diverse sources and routes of exposure to BMAA. In recent years, different methods have been developed for the analysis of BMAA. Some of these use HPLC-FD, UPLC-UV, UPLC-MS and LC-MS/MS using samples that have been derivatised or underivatised. To date the LC-MS/MS approach is the most widely used analytical technique as it is the most selective and sensitive method for BMAA determination. 相似文献
998.
S. Yolcular 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(14):2031-2034
Dehydrogenation of organic chemical hydrides has been investigated with catalysts in which the economical Ni was adopted as catalytic component and SiO2 as support. In this work dehydrogenation of methylcyclohexane was performed as organic chemical hydride in a fixed-bed catalytic reactor in the temperature range of 653–713 K, having 5, 10, 15, and 20 wt.% Ni content. 相似文献
999.
AbstractThe quasi-two-dimensional molecular conductor α-(BEDT-TTF)2I3 exhibits anomalous transport phenomena where the temperature dependence of resistivity is weak but the ratio of the Hall coefficient at 10 K to that at room temperature is of the order of 104. These puzzling phenomena were solved by predicting massless Dirac fermions, whose motions are described using the tilted Weyl equation with anisotropic velocity. α-(BEDT-TTF)2I3 is a unique material among several materials with Dirac fermions, i.e. graphene, bismuth, and quantum wells such as HgTe, from the view-points of both the structure and electronic states described as follows. α-(BEDT-TTF)2I3 has the layered structure with highly two-dimensional massless Dirac fermions. The anisotropic velocity and incommensurate momenta of the contact points, ±k0, originate from the inequivalency of the BEDT-TTF sites in the unit cell, where ±k0 moves in the first Brillouin zone with increasing pressure. The massless Dirac fermions exist in the presence of the charge disproportionation and are robust against the increase in pressure. The electron densities on those inequivalent BEDT-TTF sites exhibit anomalous momentum distributions, reflecting the angular dependences of the wave functions around the contact points. Those unique electronic properties affect the spatial oscillations of the electron densities in the vicinity of an impurity. A marked behavior of the Hall coefficient, where the sign of the Hall coefficient reverses sharply but continuously at low temperatures around 5 K, is investigated by treating the interband effects of the magnetic field exactly. It is shown that such behavior is possible by assuming the existence of the extremely small amount of electron doping. The enhancement of the orbital diamagnetism is also expected. The results of the present research shed light on a new aspect of Dirac fermion physics, i.e. the emergence of unique electronic properties owing to the structure of the material. 相似文献
1000.