A metaheuristic analysis of heat transfer rates through porous fins of tapered and step profiles: a comparative study

Neural Computing and Applications - The advanced high-end gadgets and sophisticated machines require effective mechanism of transferring heat away from the sources. In a large number of...     

mRNA for cardiac calcium channel is expressed during development of skeletal muscle

During the early development of skeletal muscle, cardiac isotypes of several contractile proteins are known to be transiently expressed. We report here that skeletal muscle developing in vivo, as well as primary cultures derived from skeletal muscle, express mRNA encoding the cardiac dihydropyridine-sensitive calcium channel. The mRNA is detectable at high concentration at the earliest stage tested in vivo and diminishes rapidly in concentration as myofibers mature. The concentration of the cardiac calcium channel mRNA also diminishes during the in vivo development of skeletal muscle in a genetically paralyzed mouse (mdg), indicating that muscle contractile activity is not necessary for the down-regulation. In contrast, mRNA for the skeletal muscle-specific calcium channel accumulates gradually in developing skeletal muscle. A similar temporal pattern of expression is also seen in primary cultures of skeletal myotubes. These results raise the question of whether the cardiac calcium channel may be functionally important during the early development of skeletal myofibers.     

Kinetics of hydroformylation of 1-decene using homogeneous HRh(CO)(PPh3)3 catalyst: a molecular level approach

The kinetics of hydroformylation of 1-decene using homogenous HRh(CO)(PPh₃)₃ catalyst has been reported in the temperature range of 50–70 °C. The effect of catalyst,P _{H 2},P _CO, and 1-decene concentration on the rate of hydroformylation has been studied. Based on the analysis of initial rate data, a rate equation has been proposed and kinetic parameters evaluated. The activation energy was found to be 11.76 kcal/mol. A molecular level approach to kinetic modelling has also been illustrated. The rate equation derived assuming oxidative addition of H₂ as a rate determining step, has been found to represent the data satisfactorily. The rate parameters for the mechanistic model have been evaluated for the data at 60 °C.NCL Communication No. 5735.     

Novel Gas-Liquid-Solid Reactors

Multiphase reactors involving gas, liquid, and solid phases have several important applications in the chemical industry, particularly in catalytic processes. Some of the well-known examples are: hydrogenation and oxidation of organic compounds, hydro-processing coal-derived and petroleum oils, Fischer-Tropsch synthesis, and methanation reactions. Due to the presence of three phases, the problem of reactor design is often important to achieve effective mass and heat transfer as well as a mixing pattern favorable to the particular process. The reactors are mainly of two types: (a) solid catalyst is suspended either by mechanical agitation or gas-induced agitation and (b) solid catalyst is in a fixed bed with concurrent or countercurrent feed of gas and liquid re-actants. The reactor types conventionally used in industry are: (a) mechanically agitated or bubble column slurry reactors and (b) trickle-bed or packed-bed bubble reactor. The various design and modeling aspects of these reactors have been reviewed by Satterfield [1], Chaudhari and Ramachandran [2], Shah [3,4], Ramachandran and Chaudhari [5], Shah et al. [6], and Herskowitz and Smith [7]. In several industrial processes these reactor designs are modified to achieve a certain specific objective, such as better heat or mass transfer, higher catalyst efficiency, better reactor performance and selectivity, etc. Similarly, specially designed reactors are often used for laboratory kinetic studies or to understand a certain phenomenon. Thus, novel multiphase reactors are becoming important from both academic and industrial viewpoints. Some of the recently introduced novel gas-liquid-solid reactor types are: (a) loop recycle slurry reactors, (b) basket-type reactors, (c) ebullated-bed reactors, (d) internal or external recycle reactors, (e) multistage slurry or packed-bed reactors, (f) column reactors with sieve trays or multiple agitators, (g) gas-induced agitated reactors, and (h) horizontal-packed-bed reactors. are being used in several new commercial processes, and various design aspects, such as hydrodynamics and mass and heat transfer, have been the subject of investigations in the last few years. However, no attempt to review the scattered information on these novel gas-liquid-solid reactors has been made. Therefore, the main objective of this paper is to review important developments in novel gas-liquid-solid reactors. For each type of reactor, advantages, disadvantages, and applications are discussed. Further, the status of information on hydrodynamics and mass transfer parameters and scale-up considerations is reviewed. These novel reactor designs are being used in several new commercial processes, and various design aspects, such as hydrodynamics and mass and heat transfer, have been the subject of investigations in the last few years. However, no attempt to review the scattered information on these novel gas-liquid-solid reactors has been made. Therefore, the main objective of this paper is to review important developments in novel gas-liquid-solid reactors. For each type of reactor, advantages, disadvantages, and applications are discussed. Further, the status of information on hydrodynamics and mass transfer parameters and scale-up considerations is reviewed.     

Interpenetrating polymer network/functionalized-reduced graphene oxide nanocomposite: As an advanced functional material

In this report, smart polyurethane-polystyrene interpenetrating polymer network (IPN)-based nanocomposites were fabricated using simultaneous polymerization technique with different doses of functionalized reduced graphene oxide (f-RGO). RGO was functionalized with monoglyceride of sunflower oil in the presence of toluene diisocyanate. Successful functionalization of RGO was supported by Fourier-transform infrared spectroscopy, X-Ray diffraction, and transmission electron microscopy analyses. Most interestingly, the fabricated IPN-based nanocomposites showed significant enhancements in mechanical (tensile strength: 165%; elongation at break: 198%; toughness: 340%) and thermal (thermally stable up to 262°C) properties upon incorporation of 1 weight% of f-RGO. Moreover, the fabricated nanocomposites exhibited outstanding chemical resistance, self-cleaning behavior through surface hydrophobicity (static contact angle: 125.6–136.5°), multi-stimuli responsive shape memory effect (100% recovery within 33–44 s by microwave and 265–308 s by sunlight) and thermally actuated artificial muscle-like behavior. Therefore, the studied smart nanocomposites with the aforementioned properties hold significant potential for possible advanced applications.     

Language Structure Using Fuzzy Similarity

Learning of (context-free) grammar rules that are based on alignment between texts of a given collection of sentences has attracted the attention of many researchers. We define and study the alignment profile and formulate fuzzy similarity of alignment profiles for a given collection of sentences. Using the fuzzy-similarity-based profile alignment, we give a methodology to formulate stochastic context-free grammar (CFG) rules. We introduce profile-alignment-based dynamic sentence similarity threshold to formulate the rules of stochastic CFG. The proposed methodology is tested using Child Language Data Exchange System (CHILDES) dataset of sentences. The benefits of our approach are experimentally demonstrated. Since our approach does not make use of any domain knowledge, it is expected to be useful in wide variety of applications requiring model construction.     

1.55μm SiGe 2×3光开关

利用多模干涉效应和自由载流子等离子体色散效应设计和模拟了基于1.55μm波长的2×3 SiGe光开关.该光开关由两个单模输入端口、一个多模干涉区和三个单模输出端口构成.在多模干涉区,设有两个折射率调制区,可以利用来把从两个输入端口输入的光信号分别从三个输出端口输出.束传播法分析结果表明,该光开关的传输损耗小于1.43dB,串扰在-18～-32.8dB之间.     

Ilmenite phase nickel titanate nanowhiskers as highly sensitive LPG sensor at room temperature

The NiTiO₃ nanoparticles with ilmenite phase were synthesized by the sol gel method and investigated for sensing of various volatile organic compounds. The resistive type sensing by NiTiO₃ towards LPG was not reported earlier where the sensor showed fair response towards hydrogen sulfide gas, but the sensitivity towards LPG was very high. The response % for 150 ppm of LPG was approximately 3200% at room temperature. The high response towards LPG was due to the presence of some amount of rutile TiO₂ in the composites. The response and recovery times of these sensors were very less (about 2 s) which could be attributed to the whiskers like structure of NiTiO₃.