Indian Journal of Materials Science
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Open Access journal
ISSN (Online) 2314-7490
Published by Hindawi [333 journals]
- On the Mechanical Properties of Hybrid Aluminium 7075 Matrix Composite
Abstract: Metal matrix composites are widely used in components of various components of industrial equipment because of their superior material properties like high stiffness to weight ratio and high impact strength and fracture toughness while compared to the conventional material. Due to the concepts of high strength to low weight ratio, Al 7075 was extensively applied in aircraft engine and wings. Even if Al 7075 has higher hardness, higher strength, excellent wear resistance, and high-temperature corrosion protection, it is in need of further enhancement of properties for increasing its applicability. This paper presents the mechanical behavior of aluminium 7075 reinforced with Silicon Carbide (SiC) and Titanium Carbide (TiC) through powder metallurgy route. These specimens were produced by powder metallurgy method. The hybrid composite was made by Al 7075 alloy as the matrix with Silicon Carbide and Titanium Carbide as reinforcement. Silicon Carbide and Titanium Carbide are mixed in different weight ratio based on the design matrix formulated through a statistical tool, namely, Response Surface Methodology (RSM). Enhanced mechanical properties have been obtained with 90% of Al 7075, 4% of TiC, and 8% of SiC composition in the composite. Coefficient of friction appears to be more which has been determined by ring compression test.
PubDate: Mon, 23 Jan 2017 00:00:00 +000
- Coalescing Aid Influences on Acrylic Latexes Property and Film Formation
Abstract: The coalescing aid of propylene glycol phenyl ether (PPh) influences on the latexes system and its film formation process have been demonstrated in this paper. The latexes with different are synthesized by seeded semicontinuous emulsion polymerization. The PPh have a significant impact on the water evaporation stage, in which PPh decreased the water evaporation rate for a low latex system but accelerated the rate for a high latex. This result was quantified using Routh-Russel model which was a useful model for the prediction of the latex particle deformation mechanisms. The different amounts of PPh can change the latex particle deformation mechanisms. The TGA results show that the PPh still exist in the latexes films during drying. The microstructures of the latex film which dry under 70°C with the PPh for different time display that the PPh can accelerate the polymer molecules motion and the diffusion rate for the latex coalescence stage.
PubDate: Mon, 26 Dec 2016 08:53:07 +000
- Investigating the Relationship between Knitted Fabric Porosity and Light
Abstract: The present paper attempts to investigate the relationship between fabric porosity and light permeability of the knitted structures, namely, rib 1 × 1, rib 2 × 1, single jersey, and plain structure. The rationale is that pores (in a fabric) would allow light to pass through but at the same time provide a quantitative assessment of the UV light permeability of the knitted fabrics, an indication of the protective capacity of the fabrics against UV radiation. The porosity and corresponding light permeability of the knitted structures were measured after varying the following knitting parameters: stitch length, stitch density, and tension on the machine. Furthermore, this work has enabled the development of an apparatus that can measure the amount of light transmitted through the knitted fabrics. The results generated by the equipment were validated through the use of regression equations.
PubDate: Tue, 25 Oct 2016 08:29:59 +000
- Process to Improve the Adherences of Copper to a PTFE Plate
Abstract: A simple low plasma power and roughness free process for improving the adherence of Cu to PTFE is presented. The results show that low pressure and Ar flow combination are the drivers of this improved adherence. Copper Peel Strength Tensile values up to 60 kg/m are obtained which are comparable to those shown in commercial composite dielectrics for high-frequency applications Printed Circuit Boards.
PubDate: Thu, 01 Sep 2016 07:57:38 +000
- Preparation of Paper Mulberry Fibers and Possibility of Cotton/Paper
Mulberry Yarns Production
Abstract: The novelty of yarn production from cotton/paper mulberry fiber blends was reported. The objective of this research was to prepare the paper mulberry fibers and study the possibility of production of yarns from cotton/paper mulberry fibers. For preparation of paper mulberry fibers, the inner bark was first immersed in water for 24 h. Then, the fibers were treated with sodium hydroxide at concentration of 5–10% (w/v) for 1–3 h. After that, the bleaching process was conducted with hydrogen peroxide at concentration of 5–25% (v/v) for different temperature and time. Finally, the fibers were washed with 10% (v/v) of nonionic surfactant at temperature of 90°C for 30 minute to remove the residual gum from the fibers. The results showed that optimum condition for scouring of the paper mulberry fibers was 15% (w/v) sodium hydroxide at 90°C for 2 h. The bleaching process with 15% (v/v) H2O2 at 90°C for 90 minute was suitable. The obtained fibers were blended with the cotton fibers to produce yarns by open-end spinning method. The % elongation and tenacity of the blended yarns increased with the increasing of the paper mulberry ratio. Also, the antifungal property of yarns was improved by the blending of cotton fibers with the paper mulberry fibers.
PubDate: Thu, 25 Aug 2016 16:52:00 +000
- Three-Dimensional Unsteady State Temperature Distribution of Thin
Rectangular Plate with Moving Point Heat Source
Abstract: This paper deals with the study of thermal stresses in thin rectangular plate subjected to point heat source which changes its place along -axis. Governing heat conduction equation has been solved by using integral transform technique. Results are obtained in the form of infinite series. As a special case, aluminum plate has been considered and results for thermal stresses have been computed numerically and graphically.
PubDate: Tue, 16 Aug 2016 14:18:01 +000
- Experimental Evaluation and Characterization of Electron Beam Welding of
Abstract: Aiming to reduce the weight of components, thus allowing a profit in terms of energy saving, automotive industry as well as aircraft industry extensively uses aluminum alloys. The most widely used joining technology in aircraft industry is riveting, while welding seems to be used in the car industry in the case of aluminum alloys. However, welding technology is characterized by many defects, such as gas porosity; oxide inclusions; solidification cracking (hot tearing); and reduced strength in both the weld and the heat affected zones which could limit its development. Many techniques are used for aluminum alloys welding, among them is electron beam welding (EBW), which has unique advantages over other traditional fusion welding methods due to high-energy density, deep penetration, large depth-to-width ratio, and small heat affected zone. The welding parameters that yield to optimal weld joint have been previously obtained. These optimal parameters were validated by welding a specimen using these parameters. To evaluate this optimal weld joint, complete, microstructural observations and characterization have been carried out using scanning electron microscopy, optical microscopy, and energy dispersive X-ray analysis. This evaluation leads to description and quantification of the solidification process within this weld joint.
PubDate: Mon, 15 Aug 2016 14:58:10 +000
- Influence of Milling Media on the Mechanical Alloyed W-0.5 wt. Ti
Abstract: The effects of milling atmosphere and mechanical alloying (MA) duration on the effective lattice parameter, crystallite size, lattice strain, and amorphization rate of the W-0.5 wt. Ti powders were investigated. W-0.5 wt. Ti powders were mechanically alloyed (MA’d) for 10 h and 20 h in a high energy ball mill. Moreover, morphology of the powders for various MA was analyzed using SEM microscopy. Their powder density was also measured by helium pycnometer. The dry milled agglomerated powders have spherical particle, while wet milled powders have layered morphology. Milling media and increasing of milling time significantly reduce the crystallite size. The smallest crystallite size is 4.93 nm which belonged to the dry milled powders measured by Lorentzian method after 20 hours’ MA. However, after 20 hours, MA’d powders show the biggest crystallite size, as big as 57.07 nm, measured with the same method in ethanol.
PubDate: Tue, 09 Aug 2016 14:23:10 +000
- Detection of Phenols from Industrial Effluents Using Streptomyces Mediated
Abstract: Extracellular gold nanoparticles synthesized by Streptomyces tuirus DBZ39 were explored for the detection of phenols in the effluent of fertilizer and distillery industries. An average size of 27–56 nm gold nanoparticles was produced and confirmed by UV-vis absorption spectrum, scanning electron microscopy, and energy dispersive X-ray analysis. In the present investigation visual detection of phenols in the effluent samples by gold nanoparticles is enhanced by sodium sulphate. The detection is achieved successfully within 2 min, with change in color of the effluent samples. Use of biologically originated gold nanoparticles along with salt for the detection of phenols from industrial effluents is a novel approach.
PubDate: Thu, 28 Jul 2016 07:21:05 +000
- Adsorption of 3-Chloroaniline on Potato Skin in Aqueous Solution
Abstract: The adsorption behaviour of aromatic amine 3-chloroaniline (3-CA) from aqueous solution on fresh potato skin was investigated. A series of batch experiments were conducted under different experimental conditions of contact time, 3-chloroaniline concentration, weight of potato skin, pH, temperature, and ionic strength using RP-HPLC analysis. Adsorption equilibrium of 3-chloroaniline at concentration of 10 µg/mL on 1 g weight of chopped potato skin was achieved in 24 hours. Using different varieties of potato skin showed that the adsorption of 3-CA on Nicola variety is higher compared to Sante and Maris Peer varieties. Adsorption on potato skin was found to be generally higher compared to cortex and pith tissues. Analysis of adsorption isotherm shows that equilibrium data was fitted to Freundlich model (). Maximum adsorption capacities of 3-chloroaniline were found in the pH range from 3 to 9, whereas low adsorption quantities were found in high acidic and high basic solutions (pH 2 and pH 13, resp.). Adsorption capacity increased with an increase in temperature from 4°C to 30°C but decreased with further increase of temperature to 40°C. Testing the ionic strength showed that increasing the concentration of electrolyte reduces the adsorption efficiency. This study indicated that the fresh potato skin (without any treatment) is possible to use as a new adsorbent for removal of 3-chloroaniline from industrial waste water.
PubDate: Mon, 25 Jul 2016 08:20:55 +000
- Graphene Oxide Reinforced Polycarbonate Nanocomposite Films with
Abstract: The incorporation of carbonaceous nanofillers into polymers can result in significant materials with improved physicochemical properties and novel composite functionalities. In this study, we have fabricated antibacterial, lightweight, transparent, and flexible graphene oxide (GO) reinforced polycarbonate thin films by a facile and low-cost methodology. Solution blending is employed to get a homogeneous mixture of PC-GO composites at various loading of GO, and the thin films are prepared by dry-wet phase inversion technique. Thermal studies and micrographs of the films revealed the incorporation of GO in PC matrix. Microstructure of the thin films showed the homogeneous dispersion of GO at micro- and nanoscales; however, at higher loading of GO (0.7%), significant agglomeration is observed. More importantly, PC-GO composite films exhibited excellent antibacterial activities against E. coli and S. aureus, owing to the antibacterial nature of GO nanoparticles.
PubDate: Mon, 18 Jul 2016 13:28:16 +000
- Detecting Safety Zone Drill Process Parameters for Uncoated HSS Twist
Drill in Machining GFRP Composites by Integrating Wear Rate and Wear
Abstract: The previous research investigations informed that the tool wear of any machining operation could be minimized by controlling the machining factors such as speed, feed, geometry, and type of cutting tool. Hence the present research paper aims at controlling the process parameters to minimize the drill tool wear, during the machining of Glass Fiber Reinforced Polymer (GFRP) composites. Experiments were carried out to find the tool wear rate and a wear mechanism map of uncoated High Speed Steel (HSS) drill of 10 mm diameter was developed for the drilling of GFRP composite laminates. The surface micrograph images on the drill land surface displayed dominant wear mechanisms induced on HSS drill during machining of GFRP and they were found to be adhesive wear, adhesive and abrasive wear, abrasive wear, and diffusion and fatigue wear. A “safety wear zone” was identified on the wear mechanism map, where the minimum tool wear of the HSS drill occurs. From the safety zone boundaries, it was inferred that the drill spindle speed should be set between 1200 and 1590 rpm and feed rate must be set within a range of 0.10–0.16 mm/rev for GFRP work and HSS tool combination to enhance the service life of 10 mm HSS drills and to minimize the tool wear.
PubDate: Mon, 11 Jul 2016 09:22:16 +000
- Review on Optical and Electrical Properties of Conducting Polymers
Abstract: We reviewed optical and electrical properties of conjugated polymers. The charge transport models to describe the hole and electron transport mechanism are also included in the electrical properties of conjugated polymers. The effect of optical and electrical properties after doping is also indexed in this paper.
PubDate: Tue, 21 Jun 2016 09:47:11 +000
- DFT Study on the Carrier Concentration and Temperature-Dependent
Thermoelectric Properties of Antimony Selenide
Abstract: We present the thermoelectric properties of Antimony Selenide (Sb2Se3) obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Thermoelectric properties were calculated using BoltzTrap code using the constant relaxation time () approximation at three different temperatures 300 K, 600 K, and 800 K. Seebeck coefficient () was found to decrease with increasing temperature, electrical conductivity () was almost constant in the entire temperature range, and electronic thermal conductivity () increased with increasing temperature. With increase in temperature decreased from 1870 μV/K (at 300 K) to 719 μV/K (at 800 K), electronic thermal conductivity increased from 1.56 × 1015 W/m K s (at 300 K) to 3.92 × 1015 W/m K s (at 800 K), and electrical conductivity decreased from 22 × 1019/Ω m s (at 300 K) to 20 × 1019/Ω m s (at 800 K). The thermoelectric properties were also calculated for different hole concentrations and the optimum concentration for a good thermoelectric performance over a large range of temperatures (from 300 K to 1000 K) was found for hole concentration around 1019 cm−3.
PubDate: Wed, 25 May 2016 13:53:38 +000
- Effect of Solvents on the Ultrasonic Velocity and Acoustic Parameters of
Polyvinylidene Fluoride Solutions
Abstract: Ultrasonic studies provide a wealth of information in understanding the molecular behavior and intermolecular interaction of polymer solvent mixtures. Attempts were made to measure ultrasonic velocity, density, and viscosity for the mixture of polyvinylidene fluoride (PVDF) in acetone and dimethylformamide (DMF) of various stoichiometric ratios at 300 K using crystal controlled ultrasonic interferometer (Mittal make), pyknometer (specific gravity bottle), and Ostwald viscometer, respectively. The acoustic parameters adiabatic compressibility (), intermolecular free path length (), acoustic impedance (), relative association (RA), ultrasonic attenuation (), and relaxation time () have been estimated using experimental data with well-known techniques. The variation of these acoustic parameters is explained in terms of solute-solvent molecular interaction in a polymer solution.
PubDate: Tue, 26 Apr 2016 08:24:59 +000
- Microstructure Evolution and Grain Growth Model of AZ31 Magnesium Alloy
under Condition of Isothermal
Abstract: Microstructure evolution of AZ31 magnesium alloy in annealing process had been investigated by experiment study at heating temperature range of 150°C–450°C and holding time range of 15 min–60 min. The effects of heating temperature and holding time on grain growth had been analyzed. The results presented that the grain size tends to grow up with the increase of holding time at a certain temperature. At a certain holding time, the grain size increased firstly and then decreased at the heating temperature range of 150–250°C. And when heating temperature is higher than 250°C, the grain grows up gradually with the increase of heating temperature. The grain growth model of AZ31 Mg alloy has been established by regression based on the experimental data at temperature of 250–450°C, and the relative error between model calculation results and experimental results is less than 19.07%. Activation energy of grain growth of AZ31 magnesium alloy had been determined.
PubDate: Wed, 30 Dec 2015 06:21:36 +000
- Wear and Corrosion of Cast Al Alloy Piston with and without Brake Oil
Abstract: The effects of wear and corrosion of cast AA6061 aluminium alloy were studied with and without brake fluid using a wear jig while the corrosion rate was determined in brake fluid for 70 days under two experimental set-ups. The tests, yielded 0.00000123 g/mm2/min highest wear rate at 147000 wear cycles and 0.0334 mg/mm2/yr as the highest corrosion rate within the early 39th day of immersion in oil, the values being considered comparatively lower than those obtained for Al alloy in most common wet abrasion test and corrosion in aqueous solutions as previously reported in literature. The material loss rates to wear and corrosion were determined from the equations relating to wear and corrosion based on the ASTM designations. The results show that the combined actions of wear and corrosion contribute to the total loss of piston material immersed in brake oil. This is greater than either of their effects individually on cast Al alloy in the brake oil.
PubDate: Sun, 01 Nov 2015 07:23:02 +000
- Effect of MgFeSi Inoculant on Properties of Cast 6061 Al Alloy for Brake
Master Piston Application
Abstract: The influence of varying amount of MgFeSi inoculant on properties of cast 6061 Al alloy for brake master piston application has been studied and reported in this paper. Cast samples were produced at three pouring temperatures (700, 750, and 800°C) with MgFeSi varied from 1 to 3%. Wear resistance tests were performed on cast alloy in brake oil. Wear resistance tests results were validated by nondestructive examinations using photomicroscopy, SEM, EDX, and XRD data. The addition of MgFeSi influenced both the mechanical (hardness, strength, and wear resistance) and metallurgical properties (microstructures) of the cast alloy. Al grains were more refined and yielded good strength properties. Inoculating the melt with MgFeSi forms insoluble compound particles and is responsible for grain refinement. The increased amount of MgFeSi from 1 to 3% improved the wear resistance of the cast piston under lubricating condition using brake oil.
PubDate: Sun, 18 Oct 2015 13:12:56 +000
- Synthesis, Characterization, and Investigation of Visible Light
Photocatalytic Activity of C Doped TiO2/CdS Core-Shell Nanocomposite
Abstract: Carbon (C) doped TiO2/CdS core-shell nanocomposite (C/TiO2/CdS) was synthesized using microemulsion method. Synthesized powder was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and UV-visible spectrophotometery. TEM images reveal that C/TiO2/CdS core-shell heterostructure is successfully prepared with CdS as a core and C doped TiO2 as a shell. UV-visible absorption spectra show that CdS nanoparticles act as a sensitizer and effectively enhance the photoabsorption capacity of C/TiO2/CdS nanocomposite in visible region. Visible light photocatalytic activity of synthesized nanocomposite was evaluated for the degradation of methylene blue. C/TiO2/CdS core-shell nanocomposite exhibits better photocatalytic activity as compared to bare TiO2, CdS, CdS/TiO2, and C doped TiO2.
PubDate: Mon, 05 Oct 2015 13:02:32 +000
- Thermoluminescence and Photoluminescence Study of Erbium Doped CaY2O4
Abstract: Phosphor doped with erbium ion with variable concentration (0.5–2 mol%) was synthesized by solid state reaction method. CaY2O4:Er3+ phosphor is characterized by X-ray diffraction technique for structural analysis and crystallite size calculation. Average crystallite size was found to be nearly 58 nm. Two prominent TL glow peaks found at 163°C associated with higher temperature peak 340°C. The peak intensity of higher temperature (340°C) peak was less as compared to lower temperature peak (163°C) because the deep trapping formation is less in case of UV irradiation. Sample shows good TL glow curve and for variable UV exposure time maximum TL intensity was found at 20 min UV exposure which is optimized UV exposure time. Sample was studied by photoluminescence emission spectra excited by xenon flash lamp with nearly 360 nm and four prominent peaks found at wavelengths 445, 525, 553, and 565 nm; here the 445 and 565 nm peak were intense as compared to others. From the PL emission spectra, it is concluded that the color tenability of prepared CaY2O4:Er3+ was blue-green and it is verified by CIE coordinate. Kinetic parameters of prepared phosphor were calculated by computerized glow curve deconvolution (CGCD) technique.
PubDate: Wed, 30 Sep 2015 16:38:02 +000
- Influencing Parameters in the Photocatalytic Degradation of Organic
Effluent via Nanometal Oxide Catalyst: A Review
Abstract: This paper aims to review the recent works on the photocatalytic degradation of organic pollutants in the presence of nanophotocatalyst. In this regard the effects of operation parameters which could influence the photocatalytic degradation of organic pollutants (such as catalyst preparation method, initial concentration of organic pollutants, presence of doping, catalyst loading, calcinations temperature, pH, presence of oxidants, UV intensity, temperature, and presence of supports) are discussed. Recent research suggests that the parameters mentioned above have great influence on the photocatalytic activity of prepared nanocatalyst. Also, the general mechanism of photocatalytic degradation and some recent synthesis methods are discussed here.
PubDate: Thu, 17 Sep 2015 14:03:44 +000
- Mechanical Characterization and Machinability Behavior of Annealed AISI D6
Cold Working Steel
Abstract: Tool steels in metal forming industry are exposed to complex and aggressive conditions due to multiple effects (mechanical, thermal, or tribological loading) and require defined mechanical properties. Also machining of tool steel with poor machinability like AISI D6 to manufacture form tools is an extremely difficult task. This paper investigates the microstructural, mechanical, and machining behavior of AISI D6 steel in annealed and hardened conditions. Various mechanical tests indicated good hardenability, improved surface hardness, and phenomenal improvement in tensile strength but extremely poor resistance to impact in both annealed and hardened condition for this steel. The machining characteristics of AISI D6 steel were evaluated using a 2k unreplicated full factorial design approach and statistical techniques have been used to assess and identify the significant factors, namely, cutting speed, feed, depth of cut, and approach angle, in minimizing surface roughness and main cutting force while machining this steel with a carbide tool. It was found that the depth of cut, feed, and approach angle are the most significant factors affecting the surface roughness and depth of cut and feed affect the main cutting force. Cutting speed has no effect on surface roughness and main cutting force in machining of the steel in annealed condition.
PubDate: Thu, 17 Sep 2015 06:59:47 +000
- Dynamics of Kaolinite-Urea Nanocomposites via Coupled DMSO-Hydroxyaluminum
Abstract: Kaolinite-urea nanocomposites were prepared via intercalation reactions in an attempt to investigate the dynamic nature of kaolinite morphology for advanced applications in controlled release systems (CRS). Characterization was done using SEM-EDX, XRF, ATR-FTIR, XRD, and DT/DTG; Andreasen pipette sedimentation technique was used to determine the grain size distribution of the raw kaolinite. The X-ray diffraction pattern revealed the existence of an FCC Bravais lattice where the intercalation ratios attained were 51.2%, 32.4%, 7.0%, and 38.4% for hydroxyaluminum oligomeric intercalated kaolinite, substituted urea intercalated kaolinite, calcined DMSO intercalated kaolinite, and hydroxyaluminum reintercalated kaolinite, respectively, along with their respective crystallite sizes of 33.51–31.73 nm, 41.92–39.69 nm, 22.31–21.13 nm, and 41.86–39.63 nm. The outcomes demonstrated that the employed intercalation routes require improvements as the intercalation reactions were in average only ≈32.3%. The observations unveiled that it is possible to manipulate kaolinite structure into various morphologies including dense-tightly packed overlapping euhedral pseudo hexagonal platelets, stacked vermiform morphologies, postulated forms, and unique patterns exhibiting self-assembled curled glomeruli-like morphologies. Such a diversity of kaolinite morphologies expedites its advanced applications in the controlled release systems (CRS) such as drug delivery systems and controlled release fertilizers (CRFs).
PubDate: Sun, 13 Sep 2015 13:10:56 +000
- Effect of Fly Ash and Carbon Reinforcement on Dry Sliding Wear Behaviour
of Red Mud
Abstract: This paper explains the sliding wear performance of red mud, fly ash, and carbon composite coating on mild steel. The complex mixture of red mud, fly ash, and carbon is plasma sprayed at 9 kW operating power level. The coatings are examined to study the coating morphology, XRD phase transformation, wear rate, and wear morphology. Wear rate (in terms of cumulative mass loss) with sliding time has been demonstrated in the study. At first pure red mud is plasma coated to observe the coating characteristics and then compounded with 20% carbon, 30% carbon, and 20% carbon + 30% fly ash, separately by weight and sliding wear test conducted using pin on disc wear tester. The trial was performed at fixed track diameter of 100 mm and at sliding speed of 100 rpm (0.523 m/s) at a load of 30 N. The results are compared. Declined cumulative mass loss by inclusion of fly ash and carbon is seen. This might be due to augmented interfacial tension and dense film build-up at boundary layer.
PubDate: Thu, 27 Aug 2015 14:59:45 +000
- Evaluation of Chitosan Based Polymeric Matrices for Sustained Stomach
Specific Delivery of Propranolol Hydrochloride
Abstract: The objective of the present investigation was to explore the potential of Chitosan based polymeric matrices as carrier for sustained stomach specific delivery of model drug Propranolol Hydrochloride. Briefly, single unit hydrodynamically balanced (HBS) capsule formulations were prepared by encapsulating in hard gelatin capsules, intimately mixed physical mixtures of drug, and cationic low molecular weight Chitosan (LMCH) in combination with either anionic medium viscosity sodium alginate (MSA) or sodium carboxymethylcellulose (CMCNa). The effect of incorporation of nonionic polymers, namely, tamarind seed gum (TSG) and microcrystalline cellulose (MCCP), was also investigated. It was observed that HBS formulations remained buoyant for up to 6 h in 0.1 M HCl, when LMCH : anionic/nonionic polymer ratio was at least 4 : 1. It was also observed that LMCH has formed polyelectrolyte complex (PEC) with MSA (4 : 1.5 ratio) and CMCNa (4 : 1 ratio) in situ during the gelation of HBS formulations in 0.1 M HCl. The retardation in drug release was attributed to the PEC formation between LMCH and MSA/CMCNa. Incorporation of MCCP (rapid gel formation) and TSG (Plug formation) was found to be innovative. From the data, it is suggested that Chitosan based polymeric matrices may constitute an excellent carrier for stomach specific drug delivery.
PubDate: Thu, 27 Aug 2015 08:43:21 +000
- Enhanced Catalytic Activity of Supported Gold Catalysts for Oxidation of
Noxious Environmental Pollutant CO
Abstract: Noble metal nanomaterials have attracted mounting research attention for applications in diverse fields of catalysis, biology, and nanotechnology. In the present study, we have undertaken a detailed investigation on synthesis, characterization, and catalytic activity studies for CO oxidation by nanogold catalysts supported over CeO2 and CeO2-ZrO2 (1 : 1 mole ratio). The support systems were prepared by modified, simple precipitation technique and the Au supported samples were synthesized using deposition-precipitation with urea method. The physicochemical characterization was performed by XRD, ICP-AES, BET surface area, FT-IR, UV-Vis DRS, Raman Spectroscopy, TEM, and XPS techniques. Au/CeO2 catalyst showed more than 80% CO conversions at 30°C, whereas Au/CeO2-ZrO2 exhibited ~100% CO conversion at that temperature. The catalytic performance of Au catalysts is highly dependent on the nature of the support.
PubDate: Thu, 27 Aug 2015 06:40:51 +000
- Synthesis and Optical Characterization of Europium Doped MY2O4 (M = Mg,
Ca, and Sr) Nanophosphors for Solid State Lightening Applications
Abstract: Trivalent europium doped yttriate nanophosphors were synthesized by rapid facile gel combustion technique. The photoluminescence (PL) properties of these Eu3+ activated MY2O4 (M = Mg, Ca, and Sr) nanophosphors showed red luminescence and exhibited excellent emission properties in their respective regions of color coordinates. Based on the excitation wavelengths multiple emission peaks were obtained. The main peak in the emission spectra was ascribed to 5D0→7F2 transition of Eu3+ ion. The structural and morphological studies were performed by the measurements of X-ray diffraction profiles, scanning electron microscope (SEM) images, and transmission electron microscope (TEM) micrographs. Furthermore, the effects of additional heating on the different host lattices of these phosphors were also studied.
PubDate: Mon, 17 Aug 2015 11:57:07 +000
- Combined Effect of Slip Velocity and Surface Roughness on a Magnetic
Squeeze Film for a Sphere in a Spherical Seat
Abstract: This investigation analyzes the performance of a magnetic fluid based squeeze film for a sphere in a rough spherical seat with slip velocity. The slip model of Beavers and Joseph has been deployed to study the effect of velocity slip while the stochastic model of Christensen and Tonder has been used to calculate the effect of surface roughness. The concerned statistically averaged Reynolds’ type equation is solved to derive the pressure distribution which results in the calculation of load carrying capacity. The results presented in graphical forms confirm that the adverse effect of slip velocity can be overcome to a large extent at least in the case of negatively skewed roughness. However, lower values of slip may be preferred for enhancing the performance characteristics of the bearing system. Besides, variance (−ve) provides a little support to improve the performance characteristics.
PubDate: Tue, 11 Aug 2015 07:46:44 +000
- Effects of M2+ (M = Ca, Sr, and Ba) Addition on Crystallization and
Microstructure of SiO2-MgO-Al2O3-B2O3-K2O-F Glass
Abstract: In understanding the effect of K+ substitution by M2+ (M = Ca, Sr, and Ba) on crystallization and microstructural properties of boroaluminosilicate glass system, the SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glasses were prepared by single-step melt-quenching at 1500°C. Density of base glass (2.64 g·cm−3) is found to be decreased in presence of CaO and SrO. is increased by 5–10°C and decreased by 13–20°C on addition of M2+. The variation of , and decrease of thermal expansion (CTE) from 7.55 to 6.67–6.97 (×10−6/K, at 50–500°C) in substituting K+ by M2+ are attributed to the higher field-strength of Ca2+, Sr2+, and Ba2+. Opaque mica glass-ceramics were derived from the transparent boroaluminosilicate glasses by controlled heat treatment at 1050°C (duration = 4 h); and the predominant crystalline phase was identified as fluorophlogopite (KMg3AlSi3O10F2) by XRD and FTIR study. Glass-ceramic microstructure reveals that the platelike mica flake crystals predominate in presence of K2O and CaO but restructured to smaller droplet like spherical shaped mica on addition of SrO and BaO. Wide range of CTE values (9.54–13.38 × 10−6/K at 50–800°C) are obtained for such glass-ceramics. Having higher CTE value after crystallization, the CaO containing SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glass can be useful as SOFC sealing material.
PubDate: Wed, 05 Aug 2015 16:57:35 +000
- Electronic Structure, Electronic Charge Density, and Optical Properties
Analysis of GdX3 (X = In, Sn, Tl, and Pb) Compounds: DFT Calculations
Abstract: The electronic properties of magnetic cubic AuCu3 type GdX3 (X = In, Sn, Tl, and Pb) have been studied using first principles calculations based on density functional theory. Because of the presence of strong on-site Coulomb repulsion between the highly localized 4f electrons of Gd atoms, we have used LSDA + U approach to get accurate results in the present study. The electronic band structures as well as density of states reveal that the studied compounds show metallic behavior under ambient conditions. The calculated density of states at the Fermi level N() shows good agreement with the available experimental results. The calculated electronic charge density plots show the presence of ionic bonding in all the compounds along with partial covalent bonding except in GdIn3. The complex optical dielectric function’s dispersion and the related optical properties such as refractive indices, reflectivity, and energy-loss function were calculated and discussed in detail.
PubDate: Mon, 03 Aug 2015 07:36:33 +000