Spray dryer processed graphene oxide/reduced graphene oxide for high-performance supercapacitor

This study deals with the utility of mini spray dryer process to improve the dispersibility, of graphene oxide(GO) and its application for high-performance supercapacitor. Initially, the neutral solution of GO was obtained using the modified Hummer's method. After this, the prepared GO solution was processed by mini spray dryer to obtain a more purified, lighter, and dispersed form of GO which is named as spray dryer processed GO (SPGO). The SPGO thus obtained showed excellent dispersibility behavior with various solvents, which is not found in case of conventional oven drying. Furthermore, utility of SPGO and its reduced form (r-SPGO) for supercapacitor applications have been investigated. Results obtained from the cyclic voltammetry(CV) analysis, impedance, and charge-discharge behavior of supercapacitor fabricated using r-SPGO shows enhanced features. Therefore, the simple spray dried GO and its reduced form, that is, r-SPGO can be utilized as a potential candidate for the supercapacitor application. Herein, as synthesized SPGO exhibited the specific capacitance of 12.07 and 37.6 F/g with PVA-H₃PO₄ and 1 mol/L H₃PO₄, respectively, at a scan rate of 5 mV/s. On the other hand, reduced form of SPGO, that is, r-SPGO showed the specific capacitance of 27.16 and 230 F/g with PVA-H₃PO₄ and 1 mol/L H₃PO₄, respectively.     

Design,Synthesis, and Self-Assembly Studies of a Suite of Monodisperse,Facially Amphiphilic,Protein–Dendron Conjugates

The custom design of protein–dendron amphiphilic macromolecules is at the forefront of macromolecular engineering. Macromolecules with this architecture are very interesting because of their ability to self-assemble into various biomimetic nanoscopic structures. However, to date, there are no reports on this concept due to technical challenges associated with the chemical synthesis. Towards that end, herein, a new chemical methodology for the modular synthesis of a suite of monodisperse, facially amphiphilic, protein–dendron bioconjugates is reported. Benzyl ether dendrons of different generations (G1–G4) are coupled to monodisperse cetyl ethylene glycol to form macromolecular amphiphilic activity-based probes (AABPs) with a single protein reactive functionality. Micelle-assisted protein labeling technology is utilized for site-specific conjugation of macromolecular AABPs to globular proteins to make monodisperse, facially amphiphilic, protein–dendron bioconjugates. These biohybrid conjugates have the ability to self-assemble into supramolecular protein nanoassemblies. Self-assembly is primarily mediated by strong hydrophobic interactions of the benzyl ether dendron domain. The size, surface charge, and oligomeric state of protein nanoassemblies could be systematically tuned by choosing an appropriate dendron or protein of interest. This chemical method discloses a new way to custom-make monodisperse, facially amphiphilic, protein–dendron bioconjugates.     

Separation of hematite from banded hematite jasper (BHJ) by magnetic coating

The separation of iron oxide from banded hematite jasper(BHJ) assaying 47.8% Fe, 25.6% Si O2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite,jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. Beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade BHJ iron ore under appropriate conditions.     

Lean philosophy: implementation in a forging company

This research addresses the implementation of lean philosophy in a forging company with a focus on radial forging production flow lines. Here, the prime motive is to evolve and test several strategies to eliminate waste on the shop floor. In this research, a systematic approach is suggested for the implementation of lean principles. This paper describes an application of value stream mapping (VSM). Consequently, the present and future states of value stream maps are constructed to improve the production process by identifying waste and its sources. Furthermore, Taguchi’s method of design of experiments is pursued here to minimize the forging defects produced due to imperfect operating conditions. A noticeable reduction in set-up time and work-in-process (WIP) inventory level is substantiated. Finally, we conclude with a discussion of managerial implications and the future scope of research.     

Fuzzy Multiobjective and Linear Programming Based Management Models for Optimal Land-Water-Crop System Planning

In this article, linear programming and fuzzy optimization models are developed for planning and management of available land-water-crop system of Mahanadi-Kathajodi delta in eastern India. The models are used to optimize the economic return, production and labour utilization, and to search the related cropping patterns and intensities with specified land, water, fertilizer and labour availability, and water use pattern constraints. Due to extreme backwardness of the study area, it has been decided to keep all the three objectives of the linear programming models at the same priority level to obtain the compromised solution in a fuzzy environment that incorporates the imprecision in fuzzy goals and fuzzy constraints. These non-structural models facilitate the conjunctive use of available surface water and groundwater resources. A comparative evaluation along with the benefit-cost ratios of the existing and proposed farming systems is also presented.     

Interfacial tension between low pressure argon plasma and molten copper and iron

The interfacial tension between the molten metal and the surrounding plasma environment affects the circulation of molten metal in the weld pool, heat transfer, and the eventual structure and properties of the weld metal. Since the effect of plasma on the interfacial tension of molten metals is not known, interfacial tension values between low pressure argon plasma and pure copper and iron were measured. The variables studied were temperature and the intensity of plasma emission.     

Progress in deep-UV photoresists

Higher resolution can be achieved in lithography by decreasing the wavelength of the exposure source. However, resist material and their processing are also important when we move to a shorter wavelength lithography technology. This paper reviews the recent development and challenges of deep-UV photoresists and their processing technology.     

Evaluation of effect of hydrogen on toughness of Zircaloy-2 by instrumented drop weight impact testing

Hydride-assisted degradation in fracture toughness of Zircaloy-2 was evaluated by carrying out instrumented drop-weight tests on curved Charpy specimens fabricated from virgin pressure tube. Samples were charged to 60 ppm and 225 ppm hydrogen. Ductile-to-brittle-transition behaviour was exhibited by as-received and hydrided samples. The onset of ductile-to-brittle-transition was at about 130 °C for hydrided samples, irrespective of their hydrogen content. Dynamic fracture toughness (K_ID) was estimated based on linear elastic fracture mechanics (LEFM) approach. For fractures occurring after general yielding, the fracture toughness was derived based on equivalent energy criterion. Results are supplemented with fractography. This simple procedure of impact testing appears to be promising for monitoring service-induced degradation in fracture toughness of pressure tubes.     

Evidence of Homogeneous Microstructures in Ti6Al4V Alloy During Shear Deformation

Metallurgical and Materials Transactions A - Free-end torsion tests were conducted for Ti6Al4V (Ti64) alloy at temperatures of 298 K, 673 K, and 873 K for different strains ranging from 0.22 to...     

Influence of ZnO nanoparticles on the cure characteristics and mechanical properties of carboxylated nitrile rubber

Zinc oxide (ZnO) nanoparticles assembled in one dimension to give rod‐shaped morphology were synthesized. The effect of these ZnO nanoparticles (average particle size ～ 50 nm) as the curing agent for carboxylated nitrile rubber was studied with special attention to cure characteristics, mechanical properties, dynamic mechanical properties, and swelling. These results were compared with those of the conventional rubber grade ZnO. The study confirmed that the ZnO nanoparticles gave a better state of cure and higher maximum torque with a marginal decrease in optimum cure time and scorch time. The mechanical properties also showed an improvement. There was an increase in tensile strength by ～ 120%, elongation at break by ～ 20%, and modulus at 300% elongation by ～ 30% for the vulcanizate cured with ZnO nanoparticles, as compared with the one containing rubber grade ZnO. Dynamic mechanical analysis revealed that the vulcanizates exhibited two transitions—one occurring at lower temperature due to the T_g of the polymer, while the second at higher temperature corresponding to the hard phase arising due to the ionic structures. The second transition showed a peak broadening because of an increase in the points of interaction of ZnO nanoparticles with the matrix. The tan δ peak showed a shift towards higher T_g in the case of ZnO nanoparticle‐cured vulcanizate, indicating higher crosslinking density. This was further confirmed by volume fraction of rubber in the swollen gel and infrared spectroscopic studies. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007