Designed Patterning of Mesoporous Metal Films Based on Electrochemical Micelle Assembly Combined with Lithographical Techniques

Mesoporous noble metals and their patterning techniques for obtaining unique patterned structures are highly attractive for electrocatalysis, photocatalysis, and optoelectronics device applications owing to their expedient properties such as high level of exposed active locations, cascade electrocatalytic sites, and large surface area. However, patterning techniques for mesoporous substrates are still limited to metal oxide and silica films, although there is growing demand for developing techniques related to patterning mesoporous metals. In this study, the first demonstration of mesoporous metal films on patterned gold (Au) substrates, prefabricated using photolithographic techniques, is reported. First, different growth rates of mesoporous Au metal films on patterned Au substrates are demonstrated by varying deposition times and voltages. In addition, mesoporous Au films are also fabricated on various patterns of Au substrates including stripe and mesh lines. An alternative fabrication method using a photoresist insulating mask also yields growth of mesoporous Au within the patterning. Moreover, patterned mesoporous films of palladium (Pd) and palladium–copper alloy (PdCu) are demonstrated on the same types of substrates to show versatility of this method. Patterned mesoporous Au films (PMGFs) show higher electrochemically active surface area (ECSA) and higher sensitivity toward glucose oxidation than nonpatterned mesoporous Au films (NMGF).     

Novel type-2 fuzzy logic technique for handover problems in a heterogeneous network

Small cells are deployed in the long-term evolution—advanced (LTE-A) data standard to satisfy rapidly increasing data rates at hotspots and enhance coverage in buildings. Small cells are low-cost, low-power nodes with limited coverage. With small cells, the more sophisticated network architecture increases the difficulty of dealing with mobility management. The conflict between traffic demands and network resources is also very important, and the signalling overhead (ping-pong) in the handover procedure should be considered in mobility management. With the aim of solving these issues, efficient handover algorithms are being used to enhance mobility management in small-cell networks. This article presents a new handover optimization algorithm for LTE-A networks based on fuzzy logic. It consists of selecting the optimum handover margins for both macro and small cells which are required for the handover process to optimize the performance metrics. The proposed handover optimization technique is evaluated and compared with two well-known handover algorithms. The results show that it achieves a minimum call drop rate and has a minimum number of handovers.     

Enhanced thermo-mechanical and electrical properties of carbon-carbon composites using human hair derived carbon powder as reinforcing filler

In the present study, human hair derived carbon powder (HHC) synthesized in home laboratory is characterized via SEM, AFM, FT-IR, XRD, Raman, XPS, and TGA. Then HHC is used as a low cost reinforcing filler at 0–50?wt% with phenolic resin for fabricating carbon fabric reinforced polymer composites (CPCs) and its carbon-carbon composites (CCs). CPCs are fabricated via simple hand-lay techniques for resin-HHC slurry impregnation followed by hot pressing while CCs are obtained by carbonization of CPCs at 600 and 900?°C. Effects of HHC loading on CPCs and CCs are evaluated through static and dynamic mechanical thermal analysis, density, electrical conductivity, morphology, and microstructure studies. Tensile and flexural properties (strength and modulus) of CPCs and CCs improve significantly (～25 to 73%) at 30?wt% HHC loading. Storage modulus (E′) and loss modulus (E″) of CPCs increase up to 132 and 104%, respectively with addition of HHC up to 40?wt%. E′ and E″ of unfilled CCs increase with carbonization temperature, however they decrease with increasing HHC content. In addition to high specific properties, CCs also exhibit substantial increment (～233%) in electrical conductivity and thermal stability, which make HHC one of the most suitable material for high temperature-structural applications.     

Cell motion model for moving dielectrophoresis

Moving dielectrophoresis has been recently developed by the authors as an alternative method to achieve simultaneous cell fractionation and transportation. With an array of independently excitable microelectrodes, this method generates a moving electric field to sequentially fractionate and transport cells across a microchannel. Due to the peculiarity of this method, the motion of the cells is unsteady and there are interesting and distinct differences between cells experiencing positive or negative dielectrophoresis. For a proper understanding and design of a microdevice utilizing this methodology, this study presents a model for the equation of motion for a polarized cell and its unsteady motion under moving dielectrophoresis. The model considers the basic module to generate a moving electric field, where there is a finite-width top electrode and an infinite-width bottom electrode, in a parallel-plate configuration. The forces considered include dielectrophoretic force, fluid drag, buoyancy, and gravitational force. These forces are modeled as equivalent point forces acting at the center of mass of the cell. A parallel-plate wall correction factor is employed to account for the effect of the large cell size to microchannel height ratio. Various parameters are examined including the initial position of the cell relative to the electrodes, cell's Clausius-Mossotti factor, cell size, applied voltage, electrode width, interelectrode gap, microchannel height, number of energized electrodes, and types of electrode configurations. Reasonable agreements were obtained between simulated and experimental results. As the solution of the unsteady motion is rather tedious, a MATLAB algorithm, with all the associated files, for the prediction of the cell trajectory, is available on request.     

Laboratory simulation of karst development in carbonate rocks containing insoluble substances: a case study from west Iran

Karstification in carbonate rocks has caused numerous serious problems during construction projects, such as water escaping from beneath dams and reservoirs, dam foundation aging, and karst collapses. Identifying the main factors involved in carbonate dissolution processes and/or their dissolution potential could help with the development of practical approaches to common hazards associated with dam sites. Therefore, collecting data on dissolution potential and rate could be a very useful task. In this regard, the current study attempted to evaluate the rate of karst development in carbonate rocks with insoluble substances at a dam site in west Iran by performing simulated tests in the laboratory. In order to calculate the rate of chemical dissolution in the right abutment of the Patagh Dam site, we utilized appropriate equipment running in a closed system. A set of simulated laboratory experiments were conducted under predefined test conditions. Subsequently, the maximum EC change (82 μS/cm) was recorded at pH 6.5. Results also illustrated that both chemical dissolution and mechanical deterioration concurrently affected the weight reduction of the tested specimens. In addition, whenever chemical dissolution took place in a site with impure carbonates, the rate of physical deterioration increased. However, in the absence of chemical dissolution, the ratio of the rate of physical deterioration to the total weight of the samples remained virtually constant. Furthermore, due to the sensitivity of carbonate rocks to changes in pH, the ratio of the weight loss caused by physical deterioration to the total weight loss of the samples increased from 42 to 81 % as the alkalinity of the flowing water increased. The results show a relationship between chemical dissolution and mechanical deterioration, leading in turn to enhanced karst development rates.     

Development of pyrrolo[2,1-c][1,4]benzodiazepine beta-galactoside prodrugs for selective therapy of cancer by ADEPT and PMT

The pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) are a class of well-studied DNA-interactive agents with a potential for use in the treatment of cancer. The clinical utility of these molecules is limited because of the lack of selectivity for tumor tissues, high reactivity of the pharmacophoric imine functionality, low water solubility, and stability. To address the shortcomings, especially the lack of selectivity, associated with the molecules, two new beta-galactoside prodrugs of PBDs have been synthesized and evaluated for their potential use in selective therapy of solid tumors by ADEPT and PMT protocols. The preliminary studies reveal the prodrugs to be much less toxic compared to the parent moieties. These prodrugs are activated by E. coli beta-galactosidase (EC 3.2.1.23) to form the active cytotoxic moiety signifying their utility in ADEPT of cancer. One of the significant outcomes of the present study is the toxification of the prodrug 1 a by the endogenous beta-galactosidase of human liver cancer cells (Hep G2) to form the cytotoxic moiety, enabling selective therapy of hepatocellular carcinoma. Another important property of these molecules is their enhanced water solubility and stability, which are essential for a molecule to be an effective drug.     

3‐Hydroxy‐2‐[1′‐phenyl‐3′‐(p‐chlorophenyl)‐4′‐pyrazolyl]‐4‐oxo‐4H‐1‐benzopyran as a spectrophotometric reagent for trace determination of tungsten(vi)

3‐Hydroxy‐2‐[1′‐phenyl‐3′‐(p‐chlorophenyl)‐4′‐pyrazolyl]‐4‐oxo‐4H‐1‐benzopyran solution in acetone forms a yellow‐coloured complex with tungsten(vi ) in perchloric acid medium which is extractable into chloroform after equilibration. In this study, tests were carried out on this compound and it was found to be quite stable and to obey Beer’s law. Interactions with various ions were studied and the molar absorptivity, Sandell’s sensitivity and relative standard deviation were also investigated. Job’s method, the mole ratio method and the equilibrium‐shift method were also used. The ratio of metal to ligand was measured using a method that was simpler, more accurate, sensitive, rapid and selective as compared with existing methods. This method is applicable to the analysis of various samples of varied composition.     

Feasibility analysis of an epidermal glucose sensor based on time-resolved fluorescence

The goal of this study is to test the feasibility of using an embedded time-resolved fluorescence sensor for monitoring glucose concentration. Skin is modeled as a multilayer medium with each layer having its own optical properties and fluorophore absorption coefficients, lifetimes, and quantum yields obtained from the literature. It is assumed that the two main fluorophores contributing to the fluorescence at these excitation and emission wavelengths are nicotinamide adenine dinucleotide (NAD)H and collagen. The intensity distributions of excitation and fluorescent light in skin are determined by solving the transient radiative transfer equation by using the modified method of characteristics. The fluorophore lifetimes are then recovered from the simulated fluorescence decays and compared with the actual lifetimes used in the simulations. Furthermore, the effect of adding Poissonian noise to the simulated decays on recovering the lifetimes was studied. For all cases, it was found that the fluorescence lifetime of NADH could not be recovered because of its negligible contribution to the overall fluorescence signal. The other lifetimes could be recovered to within 1.3% of input values. Finally, the glucose concentrations within the skin were recovered to within 13.5% of their actual values, indicating a possibility of measuring glucose concentrations by using a time-resolved fluorescence sensor.     

Assuring process safety in the transfer of hydrogen cyanide manufacturing technology

This paper outlines the critical issues to be addressed in the transfer of hydrogen cyanide (HCN) manufacturing technology to a licensee. Process safety management (PSM) is of critical importance because of the toxicity, flammability and reactivity of HCN. The critical issues are based on experience that DuPont has gained (1) while safely manufacturing hydrogen cyanide for over 50 years, and (2) while DuPont has safely licensed HCN technology to other firms at locations around the world. DuPont's HCN experience has been combined with Aker Kvaerner's project engineering experience to insure the safe transfer of HCN technology to a licensee.     

Adiposity associated rise in leptin impairs ovarian activity during winter dormancy in Vespertilionid bat, Scotophilus heathi

The aim of the study was to evaluate the seasonal variation in serum leptin levels in a natural population of the female bat, Scotophilus heathi and their relationship to the changes in the body mass, serum insulin level, and ovarian activity. Circulating leptin level varied significantly over the season and correlated positively with the changes in body mass, and circulating insulin and androstenedione (A4) levels. Circulating leptin concentrations showed two peaks; one coincides with the maximum fat accumulation prior to winter dormancy, whereas the second shorter peak coincides with late pregnancy. The in vivo study in S. heathi showed that the increased circulating leptin level during winter dormancy coincides with the decreased expression of ovarian steroidogenic acute regulatory (StAR) protein, and low circulating estradiol (E2) level. At the same time, increased circulating leptin level coincides with increased expression of ovarian insulin receptor and high circulating A4 level. The low circulating leptin level during preovulatory period coincides with the increase in StAR protein but decrease in insulin receptor protein. The in vitro study confirmed the in vivo observations of inhibitory effect of leptin on LH induced StAR expression and E2 production, whereas the stimulatory effect of leptin (high dose) on LH induced expression of insulin receptor protein and A4 production. However, pharmacological dose of leptin produced inhibitory effect on the expression of insulin receptor protein. The results of the present study thus suggest that high circulating leptin level during winter dormancy promotes adiposity and impairs ovarian activity by suppressing StAR-mediated E2 production as well as by enhancing insulin receptor-mediated A4 synthesis thereby contributing anovulatory condition of delayed ovulation in S. heathi.