Formation of Phosphorylated 3H‐Pyrroles from NefIsocyanidePerkow Adducts and Tosylmethyl Isocyanide

Imidoyl chlorides, generated from isocyanides and acyl chlorides, react with trialkyl phosphites, in a Perkow‐type reaction, to afford 3‐(alkylimino)‐2‐[(dialkyloxyphosphoryl)oxy]acrylates, which undergo a smooth reaction with tosylmethyl isocyanide (TsMIC) to furnish 4‐(alkylamino)‐3‐[(dialkyloxyphosphoryl)oxy]‐5‐[(4‐methylphenyl)sulfonyl]‐3H‐pyrrole‐3‐carboxylates in moderate‐to‐good yields.     

Outage Probability Based Robust Distributed Beam-Forming in Multi-User Cooperative Networks with Imperfect CSI

In this paper, a new robust problem is proposed for relay beamforming in relay system with stochastic perturbation on channels of multi user and relay network. The robust problem aims to minimize the transmission power of relay nodes while the imperfect channel information (CSI) injects stochastic channel uncertainties to the parameters of optimization problem. In the power minimization framework, the relays amplification weights and phases are optimized assuming the availability of Gaussian channel distribution. The power sum of all relays is minimized while the outage probability of the instantaneous capacity (or SINR) at each link is above the outage capacity (or SINR) for each user. The robust problem is a nonconvex SDP problem with Rank constraint. Due to the nonconvexity of the original problem, three suboptimal problems are proposed. Simulation and numerical results are presented to compare the performance of the three proposed solutions with the existing worst case robust method.     

Thermal Decomposition Kinetics of Ethane Halides and Derivatives（C_2H_（6-n）X_n（n = 1～3）;X = F,Cl,Br）：DFT Study and NBO Analysis

A theoretical study of the thermal decomposition kinetics of ethane halides(C2H6-nXn(n = 1～3);X = F,Cl,Br) has been carried out at the B3LYP/6-31++G** and B3PW91/631++G** levels of theory.Among these methods and comparison of activation parameters with available experimental values,the B3PW91/6-31++G** method is in good agreement with the experimental data.The analysis of bond order and natural bond orbital(NBO) charges,bond indexes,and synchronicity parameters suggest the elimination of HX in reactions 1～9(HF:compounds 1～3,HCl:compounds 4～6,and HBr:compounds 7～9) occur through a concerted and slightly asynchronous four-membered cyclic transition state type of mechanism.     

Fabrication of carbon nanofiber by pyrolysis of freeze-dried cellulose nanofiber

The possibility of fabricating carbon nanofibers from cellulose nanofibers was investigated. Cellulose nanofiber of ~50 nm in diameter was produced using ball milling in an eco-friendly manner. The effect of the drying techniques of cellulose nanofibers on the morphology of carbon residue was studied. After pyrolysis of freeze-dried cellulose nanofibers below 600 °C, amorphous carbon fibers of ~20 nm in diameter were obtained. The pyrolysis of oven-dried precursors resulted in the loss of original fibrous structures. The different results arising from the two drying techniques are attributed to the difference in the spatial distance between cellulose nanofiber precursors.     

Phytochemical analysis and antimicrobial activities of methanolic extracts of leaf, stem and root from different varieties of Labisa pumila Benth

A local herb, Kacip Fatimah, is famous amongst Malay women for its uses in parturition; however, its phytochemical contents have not been fully documented. Therefore, a study was performed to evaluate the phenolics, flavonoids, and total saponin contents, and antibacterial and antifungal properties of the leaf, stem and root of three varieties of Labisia pumila Benth. Total saponins were found to be higher in the leaves of all three varieties, compared to the roots and stems. Leaves of var. pumila exhibited significantly higher total saponin content than var. alata and lanceolata, with values of 56.4, 43.6 and 42.3 mg diosgenin equivalent/g dry weight, respectively. HPLC analyses of phenolics and flavonoids in all three varieties revealed the presence of gallic acid, caffeic acid, rutin, and myricetin in all plant parts. Higher levels of flavonoids (rutin, quercitin, kaempferol) were observed in var. pumila compared with alata and lanceolata, whereas higher accumulation of phenolics (gallic acid, pyrogallol) was recorded in var. alata, followed by pumila and lanceolata. Antibacterial activities of leaf, stem and root extracts of all varieties determined against both Gram positive (Micrococcus luteus, Bacillus subtilis B145, Bacillus cereus B43, Staphylococcus aureus S1431) and Gram negative (Enterobacter aerogenes, Klebsiella pneumonia K36, Escherichia coli E256, Pseudomonas aeruginosa PI96) pathogens showed that crude methanolic extracts are active against these bacteria at low concentrations, albeit with lower antibacterial activity compared to kanamycin used as the control. Antifungal activity of methanolic extracts of all plant parts against Fusarium sp., Candida sp. and Mucor using the agar diffusion disc exhibited moderate to appreciable antifungal activities compared to streptomycin used as positive control.     

Effect of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> phases on the enhancement of thermal conductivity and viscosity of nanofluids in engine oil

Thermal conductivity of α-Al₂O₃ was measured using hot wire method. α-Al₂O₃ (20 nm in size) was synthesized by microwave method for which, the results were compared with commercially available γ-Al₂O₃. Thermal conductivity of nanofluids was investigated considering, it is dependency on Al₂O₃ phase. It was observed that by adding 3 wt% of nano γ-Al₂O₃ and α-Al₂O₃ to the engine oil, thermal conductivity increases by 37 and 31%, respectively. The corresponding viscosity increase for the same amount of nano γ-Al₂O₃ and α-Al₂O₃ were 36 and 38%, respectively. It was concluded that the differences in thermal conductivity originate from higher specific surface area of γ-Al₂O₃ compared to the α-Al₂O₃ which is the result of porosity difference, obtained during the synthesis process.     

A novel numerical scheme for the investigation of surface tension effects on growth and collapse stages of cavitation bubbles

In the present study the effects of surface tension on the growth and collapse stages of cavitation bubbles are studied individually for both spherical and nonspherical bubbles. The Gilmore equation is used to simulate the spherical bubble dynamics by considering mass diffusion and heat transfer. For the collapse stage near a rigid boundary, the Navier–Stokes and energy equations are used to simulate the flow domain, and the VOF method is adopted to track the interface between the gas and the liquid phases. Simulations are divided into two cases. In the first case, the collapse stage alone is considered in both spherical and nonspherical situations with different conditions of bubble radius and surface tension. According to the results, surface tension has no significant effects on the flow pattern and collapse rate. In the second case, both the growth and collapse stages of bubbles with different initial radii and surface tensions are considered. In this case surface tension affects the growth stage considerably and, as a result, the jet velocity and collapse time decrease with increasing surface tension coefficient. This effect is more significant for bubbles with smaller radii.     

Deconstructing the Effects of Matrix Elasticity and Geometry in Mesenchymal Stem Cell Lineage Commitment

A wide variety of environmental factors including physical and biochemical signals are responsible for stem cell behavior and function. In particular, matrix elasticity and cell shape have been shown to determine stem cell function, yet little is known about the interplay between how these physical cues control cell differentiation. For the first time, by using ultraviolet (UV) lithography to pattern poly(ethylene) glycol (PEG) hydrogels, it is possible to manufacture microenvironments capable of parsing the effects of matrix elasticity, cell shape, and cell size in order to explore the relationship between matrix elasticity and cell shape in mesenchymal stem cell (MSC) lineage commitment. These data show that cells cultured on 1000 μm² circles, squares, and rectangles are primarily adipogenic lineage regardless of matrix elasticity, while cells cultured on 2500 and 5000 μm² shapes more heavily depend on shape and elasticity for lineage specification. It is further characterized how modifying the cell cytoskeleton through pharmacological inhibitors can modify cell behavior. By showing MSC lineage commitment relationships due to physical signals, this study highlights the importance of cell shape and matrix elasticity in further understanding stem cell behavior for future tissue engineering strategies.     

Newtonian and Shear-thinning Taylor flow heat transfer in wavy micro-tubes: a numerical study

Meccanica - In the present study, the two-phase gas–liquid convective heat transfer is numerically studied inside uniformly heated wavy micro-tubes in the Taylor flow regime. Both Newtonian...     

Rock Porous Structure Characterization: A Critical Assessment of Various State-of-the-Art Techniques

Transport in Porous Media - The porous structure of geomaterials is of utmost importance for various industrial and natural processes. In this study, various conventional porous structure...