Supertough Hybrid Hydrogels Consisting of a Polymer Double‐Network and Mesoporous Silica Microrods for Mechanically Stimulated On‐Demand Drug Delivery

Despite their potential in various fields of bioapplications, such as drug/cell delivery, tissue engineering, and regenerative medicine, hydrogels have often suffered from their weak mechanical properties, which are attributed to their single network of polymers. Here, supertough composite hydrogels are proposed consisting of alginate/polyacrylamide double‐network hydrogels embedded with mesoporous silica particles (SBA‐15). The supertoughness is derived from efficient energy dissipation through the multiple bondings, such as ionic crosslinking of alginate, covalent crosslinking of polyacrylamide, and van der Waals interactions and hydrogen bondings between SBA‐15 and the polymers. The superior mechanical properties of these hybrid hydrogels make it possible to maintain the hydrogel structure for a long period of time in a physiological solution. Based on their high mechanical stability, these hybrid hydrogels are demonstrated to exhibit on‐demand drug release, which is controlled by an external mechanical stimulation (both in vitro and in vivo). Moreover, different types of drugs can be separately loaded into the hydrogel network and mesopores of SBA‐15 and can be released with different speeds, suggesting that these hydrogels can also be used for multiple drug release.     

Adaptable and Energy Efficacious Routing using Modified Emperor Penguin Colony Optimization Multi-faceted Metaheuristics Algorithm for MANETS

Wireless Personal Communications - In the field of computer science, the metaheuristics is a top level approach that is configured to discover, to yield or to pick a biased searching algorithm that...     

Biosorption of Trivalent Chromium from Wastewater: An Approach towards Green Chemistry

Chromium is one of the metals used in industry that create environmental toxicity and pollution problems. In the present study, chromium in wastewater was removed by a biosorption method using a bacterial culture of Bacillus pumilus. A mathematical model representing the biosorption kinetics was formulated, supporting the Langmuir isotherm for the adsorption of chromium. Fourier transform infrared and scanning electron microscopy studies were used to characterize the adsorption of chromium by the bacterial biomass. The analysis of pollution parameters (chemical oxygen demand, total organic content, total dissolved solid, total suspended solid) suggest a significant reduction of the pollution load. The results show that the method developed here is very effective for the removal of chromium from an aqueous environment.     

Bioaccumulation of chromium from tannery wastewater: an approach for chrome recovery and reuse

The presence of chromium in the effluent is a major concern for the tanning industry. Currently, chemical precipitation methods are practiced for the removal of chromium from the effluent, but that leads to the formation of chrome-bearing solid wastes. The other membrane separation and ion exchange methods available are unfeasible due to their cost. In this study, the removal of chromium from tannery effluent has been carried out using abundantly available brown seaweed Sargassum wightii. Simulated chrome tanning solution was used for the standardization of experimental trials. Various factors influencing the uptake of chromium, viz., quantity of seaweed, concentrations of chromium, pH of the chrome-bearing wastewater, and duration of treatment, have been studied. Chemical modification of the seaweed through pretreatment with sulfuric acid, magnesium chloride, and calcium chloride showed improved uptake of chromium. Langmuir and Freundlich isotherms have been fitted for various quantities of seaweed. The dynamic method of treatment of protonated seaweed with simulated chrome tanning solution at a pH of 3.5-3.8 for a duration of 6 h gave the maximum uptake of about 83%. A similar uptake has been established for commercial chrome tanning wastewater containing the same concentration of chromium. The Sargassum species exhibited a maximum uptake of 35 mg of chromium per gram of seaweed. Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis, and flame photometry studies have been carried out to understand the mechanistic pathway for the removal of chromium. The potential reuse of chromium-containing seaweed for the preparation of basic chromium sulfate (tanning agent) has been demonstrated.     

Exercise Pills for Drug Addiction: Forced Moderate Endurance Exercise Inhibits Methamphetamine-Induced Hyperactivity through the Striatal Glutamatergic Signaling Pathway in Male Sprague Dawley Rats

Physical exercise reduces the extent, duration, and frequency of drug use in drug addicts during the drug initiation phase, as well as during prolonged addiction, withdrawal, and recurrence. However, information about exercise-induced neurobiological changes is limited. This study aimed to investigate the effects of forced moderate endurance exercise training on methamphetamine (METH)-induced behavior and the associated neurobiological changes. Male Sprague Dawley rats were subjected to the administration of METH (1 mg/kg/day, i.p.) and/or forced moderate endurance exercise (treadmill running, 21 m/min, 60 min/day) for 2 weeks. Over the two weeks, endurance exercise training significantly reduced METH-induced hyperactivity. METH and/or exercise treatment increased striatal dopamine (DA) levels, decreased p(Thr308)-Akt expression, and increased p(Tyr216)-GSK-3β expression. However, the phosphorylation levels of Ser9-GSK-3β were significantly increased in the exercise group. METH administration significantly increased the expression of NMDAr1, CaMKK2, MAPKs, and PP1 in the striatum, and exercise treatment significantly decreased the expression of these molecules. Therefore, it is apparent that endurance exercise inhibited the METH-induced hyperactivity due to the decrease in GSK-3β activation by the regulation of the striatal glutamate signaling pathway.     

Fracture toughness of modified P91 weldments

There are efforts to develop modified P91 steel (9Cr-1Mo-V) consumables to optimize strength and fracture toughness in weldments for similar and dissimilar welding of 9Cr-1Mo (modified P91) for both new construction and replacement of serviced components. Fracture toughness is an important consideration which plays a vital role in determining the performance and life of the materials under the given service conditions. Toughness characterization was done by the Crack Tip Opening Displacement (CTOD) method. Welding results in a variety of non-equilibrium microstructures in the HAZ of 9Cr-lMo-V, modified P91 steel. These variations of microstructures from wrought base material through transformed HAZ to cast weld metal, may give rise to considerable inhomogeneity with respect to tensile & creep strength and ductility across the weld joints. However the mechanical properties of the individual regions of HAZ are difficult to obtain because of the small extent over which each region exists. Welded joints are used as structural parts of boilers and pressure vessels working at high temperatures, hence the main requirement is creep resistance. In the present investigation, the fracture toughness characteristics of base metal and weld metal have been evaluated by CTOD method as per the standard BS 7448. The fracture surfaces of the CTOD tested specimens were examined under Scanning Electron Microscope (SEM). Fractographic studies revealed the mode of failure and the characteristics of the fracture surface.     

Novel fulleropyrrolidines bearing π-conjugated thiophene derivatives as compatibilizing group for developing highly stable polymer solar cells

A series of new fulleropyrrolidines, which comprise one terthiophene (3T) or dithienyl thienothiophene (2TTT) conjugated segment along with two hexyl (H) or ethylhexyl (EH) chains, abbreviated as 3T-H-C₆₀, 3T-EH-C₆₀, 2TTT-H-C₆₀ and 2TTT-EH-C₆₀, were designed and synthesized to improve their structural compatibility with poly(3-hexylthiophene) (P3HT). These [60]fullerene monoadducts exhibit a characteristic UV–Vis absorption band, associated with the conjugated substituent, and similar optical bandgaps and lowest unoccupied molecular orbital (LUMO) levels of approximately 1.71 eV and −3.72 eV, respectively. The influence of the structure of the substituent in the fulleropyrrolidine on its intermolecular packing within a polymer matrix was investigated. Photoluminescence measurements of the blended films of such C₆₀ derivatives with P3HT reveal that the interfacial area between the two materials is larger in the 3T-based system than in the 2TTT-based system; moreover, the branched ethylhexyl chain is more effective than the linear hexyl group in reducing the size of the phase domains. Transmission electron microscopic images further confirm that relatively serious phase segregation occurs in the 2TTT-C₆₀/P3HT films. Accordingly, solar cells with 3T-C₆₀/P3HT as the active layer have an increased short-circuit current density owing to improved exciton dissociation efficiency, but 2TTT-C₆₀/P3HT devices have a boosted fill factor, owing to the formation of less obstructed pathways for the transport of charge carriers. More interestingly, both 3T-EH-C₆₀/P3HT and 2TTT-EH-C₆₀/P3HT exhibit highly stable blend morphology and the solar cells that are derived from them have extremely steady power conversion efficiency against long-term aging at high temperature.     

Morphological variations of Mn‐doped ZnO dilute magnetic semiconductors thin films grown by succesive ionic layer by adsorption reaction method

Transparent conducting Mn‐doped ZnO thin films have been prepared by successive ionic layer by adsorption reaction (SILAR) method. The deposition conditions have been optimized based on their structure and on the formation of smoothness, adherence, and stoichiometry. The results of the studies by X‐ray diffraction, scanning electron microscope (SEM), reveal the varieties of structural and morphological modifications feasible with SILAR method. The X‐ray diffraction patterns confirm that the ZnO:Mn has wurtzite structure. The interesting morphological variations with dopant concentration are observed and discussed. The films' quality is comparable with those grown with physical methods and is suitable for spintronic applications. Microsc. Res. Tech. 76:751–755, 2013. © 2013 Wiley Periodicals, Inc.