Preparation and characterization of molybdenum trioxide from spent hydrodesulfurization catalyst

An approach to produce molybdenum trioxide from spent hydrodesulfurization (HDS) catalyst, obtained from a petroleum refinery, is presented here. The spent catalyst was devolatilized at 600 °C so as to make it free from oils, organics and other volatile species. It was then roasted with sodium carbonate at a temperature of 850 °C for 30 min. The leaching efficiency for 20% soda roasted sample at 10% pulp density was 99.8%. From the solution molybdenum was precipitated out as ammonium molybdate at pH 1.0 with HCl and ammonium chloride. This ammonium molybdate was calcined at 750 °C to get MoO₃. The product was characterized by XRD. Its purity was determined titrimetrically and by ICP-AES.     

n-Hexadecane hydroisomerization over Pt/ZSM-12: role of Si/Al ratio on product distribution

The crystallization of pure ZSM-12 phase was accomplished at Si/Al ratios ranging from 45 to 120 using tetraethylammonium bromide as the structure directing agent. The obtained samples were characterized by X-ray diffraction, scanning electron microscopy, temperature programmed desorption of ammonia, and nitrogen adsorption–desorption measurements at 77 K, respectively. The well characterized samples were used to prepare Pt (0.5 wt%)/ZSM-12 hydroisomerization catalysts which were employed to perform n-hexadecane isomerization reaction. The catalysts were compared in terms of their activity, selectivity and product distribution at different conversion levels obtained through variation in temperature and residence times. Thus, obtained trend for product distribution over Pt/ZSM-12 system has been discussed in terms of framework Si/Al ratio to understand its role in determining the product selectivity. ZSM-12 with Si/Al ratio of 120 depicted the highest overall selectivity and favored mono-branching while those having Si/Al ratio of 45, 60 and 90 were found to favor mutlti-branching.     

A review of technology diffusion models with special reference to renewable energy technologies

Diffusion of renewable energy technologies (RETs) are driven by policies and incentives due to their inherent characteristics such as high upfront costs, lack of level playing field but distinct advantages from energy security, environmental and social considerations. Even after three decades of their promotion, only 20–25% of their potential has been realized. The theory of diffusion modeling allows analysis of diffusion processes and study of growth rates of different technologies and underlying diffusion factors. Their applications have focused on commercial and consumer products such as television, automobiles and IT products and their applications to RETs have been limited. Diffusion analysis of RETs have been based on barriers’ to RET adoption and techno–economic, learning and experience curve approaches. It is observed that these diffusion models when applied to commercial products do not deal with the issues of policy influences which are critical to RET diffusion. Since policies drive RET diffusion, the models for analyzing RET diffusion should allow establishing explicit relationships between the diffusion parameters and policies and their impact on diffusion rates. Given the potential of renewable energy technologies for sustainable development, the aim of this paper is to review different diffusion theory based models and their applicability to RET diffusion analysis.     

Preparation and characterization of spray-deposited Cu2ZnSnS4 thin films

Thin films of Cu₂ZnSnS₄ (CZTS), a potential candidate for absorber layer in thin film heterojunction solar cell, have been successfully deposited by spray pyrolysis technique on soda-lime glass substrates. The effect of substrate temperature on the growth of CZTS films is investigated. X-ray diffraction studies reveal that polycrystalline CZTS films with better crystallinity could be obtained for substrate temperatures in the range 643-683 K. The lattice parameters are found to be a=0.542 and c=1.085 nm. The optical band gap of films deposited at various substrate temperatures is found to lie between 1.40 and 1.45 eV. The average optical absorption coefficient is found to be >10⁴ cm⁻¹.     

Modeling material property heterogeneity in fiber‐reinforced injection molded plastic parts

Fiber reinforced plastic parts manufactured by injection molding have heterogeneous stiffness and strength behavior due to the molding process influence on the fiber orientations. This paper presents a methodology for determining the process‐dependent anisotropic and inhomogeneous mechanical properties of injection‐molded parts using a thickness‐wise layered homogenization technique. This technique produces an equivalent laminated meso‐scale representation at any location in the part and enables point‐wise application of the existing laminated plate and shell theories. The methodology is demonstrated by illustrating property variations in edge‐gated and center‐gated plaques. Spatial variations of elastic moduli, shear modulus, and Poisson's ratio are modeled. The model can be conveniently embedded within finite element structural analyses accounting for the process‐dependent material heterogeneities within the structure. POLYM. COMPOS., 26:98–113, 2005. © 2004 Society of Plastics Engineers     

Exploitation of microbial antagonists for the control of postharvest diseases of fruits: a review

Fungal diseases result in significant losses of fruits and vegetables during handling, transportation and storage. At present, post-production fungal spoilage is predominantly controlled by using synthetic fungicides. Under the global climate change scenario and with the need for sustainable agriculture, biological control methods of fungal diseases, using antagonistic microorganisms, are emerging as ecofriendly alternatives to the use of fungicides. The potential of microbial antagonists, isolated from a diversity of natural habitats, for postharvest disease suppression has been investigated. Postharvest biocontrol systems involve tripartite interaction between microbial antagonists, the pathogen and the host, affected by environmental conditions. Several modes for fungistatic activities of microbial antagonists have been suggested, including competition for nutrients and space, mycoparasitism, secretion of antifungal antibiotics and volatile metabolites and induction of host resistance. Postharvest application of microbial antagonists is more successful for efficient disease control in comparison to pre-harvest application. Attempts have also been made to improve the overall efficacy of antagonists by combining them with different physical and chemical substances and methods. Globally, many microbe-based biocontrol products have been developed and registered for commercial use. The present review provides a brief overview on the use of microbial antagonists as postharvest biocontrol agents and summarises information on their isolation, mechanisms of action, application methods, efficacy enhancement, product formulation and commercialisation.     

In vitro and in vivo degradability,biocompatibility and antimicrobial characteristics of Cu added iron-manganese alloy

In recent years,iron(Fe)based degradable metal is explored as an alternative to permanent fracture fixation devices.In the present work,copper(Cu)is added in Fe-Mn system to enhance the degradation rate and antimicrobial properties.Fe-Mn-xCu(x=0.9,5 and 10 wt.％)alloys are prepared by the melting-casting-forging route.XRD analysis confirms austenite phase stabilization due to the presence of Mn and Cu.As predicted by Thermo-Calc calculations,Cu rich phase precipitations are noticed along the austen-ite grain boundaries.Degradation behaviours of Cu added Fe-Mn alloys are investigated through static immersion and electrochemical polarization where enhanced degradation is found for higher Cu added alloys.When challenged against E.Coli bacteria,the Fe-Mn-Cu alloy media extract shows a significant bac-tericidal effect compare to the base alloy.In vitro cytocompatibility studies,as determined using MG63 and MC3T3-E1 cell lines,indicate increased cell density as a function of time for all the alloys.When implanted in rabbit femur,the newly developed alloy does not show any kind of tissue necrosis around the implants.Better osteogenesis and higher new bone formation are observed with Fe-Mn-10Cu alloy as evident from micro-computed tomography(μ-CT)and fluorochrome labelling.     

Cross flow on transient double‐diffusive natural convection in inclined porous trapezoidal enclosures

This paper investigates the cross‐diffusion effects subject to exponential variable boundary conditions on transient double‐diffusive natural convection flow in an enclosure. The flow domain is a two‐dimensional inclined trapezoidal cavity filled with a porous medium. The top wall is assumed to be insulated and permeable, while the enclosure's bottom wall is subject to exponential varying temperature and concentration. The prescribed temperature and concentration are different at the vertical walls. Conservation equations are used as the governing equations. The finite element Galerkin weighted residual method, in association with the Newton‐Raphson scheme is employed to solve the system of coupled nondimensional equations. The numerical tests are confirmed with existing literature and are found to be in excellent agreement. The simulations results for stream functions, isotherms, and isoconcentrations are discussed for the various flow parameters. A sensitivity analysis using the response surface method suggests that the average Nusselt and Sherwood numbers are more sensitive to the cross‐diffusion effects. It is further observed that the cross‐diffusion terms stabilize the sensitivity to the angle of inclination.     

Effect of mixing on the properties of nanocarbon containing Al2O3-C continuous casting refractories

The functional refractories used in steel casting operations are usually made up of alumina-carbon compositions having graphite as the major source of carbon. In recent times, to reduce the carbon content and to enhance the performance by designing microstructure at nano-sized level, several nano carbon sources and organic binders are introduced to traditional carbon-based refractories. The homogenous distribution of nano carbon sources within the refractory composition is important to get the advantages of its use. In the present work, nanocarbon black is used along with graphite in the alumina-carbon system. Three different mixing procedures are followed and how mixing effects the physical and mechanical properties is evaluated. The mixing order with proper nanocarbon distribution throughout the batch composition provided significant improvement in the properties. The microstructural analysis and in situ phase developments in the samples at different temperatures are also studied.