Understanding the morphological effects of WO3 photocatalysts for the degradation of organic pollutants

Dimension and morphology of photocatalysts has extensive interest in order to use the effective concurrence of photon. Despite TiO₂ and ZnO, WO₃ has also been considered as a promising candidate in terms of remediation and purification that owes to its visible light absorption and non-toxic environmental friendliness. In this study, we report the preparation of nanostructured WO₃ with different morphologies for the photocatalytic degradation of organic pollutants without the presence of any sacrificial agents. The study envisages the effect of the aspect ratio of WO₃ particles on the photochemical process and their inherent reactive species mechanism. Mechanistic reasoning revealed that, apart from the hole and hydroxyl radicals as the participating species in both structures, a significant contribution from superoxide radicals takes place in the presence of nanorods and promotes the photochemical reaction. High aspect ratio facilitates the absorption coefficient and resultant efficiency. Both the catalysts retain its reactivity after regeneration and confirms the consistent catalytic reusability. Reactivity enhancement of any photocatalyst is possible through tuning the inherent structure of the material.     

Design and analysis of an efficient QoS improvement policy in cloud computing

Cloud computing offers the proficiency to use computing and storage resources on a metered basis and reduces the investments in Information Technology domain. This paper highlights a major research issue, i.e., providing good quality of service (QoS) to the cloud users. The QoS is associated with several parameters such as completion time, response time, turnaround time (TAT), waiting time (WT), bandwidth. A new cloudlet scheduling algorithm—improved round robin cloudlet scheduling algorithm—has been proposed which improves the TAT, WT and number of context switching. It enhances the resource utilization. The experimental results are obtained by CloudSim toolkit extending few base classes and compared by classical round robin algorithm.     

Activity measurements of bivalent cations singly and in mixture with resin membrane electrodes in aquo-organic media

Cation exchange resin membranes were used as electrodes for activity measurements in aquo-propanolic media for bivalent ions, e.g., Ca, Mg, Cu, Zn, either singly or in a mixture of two. From the results it may be concluded that ion exchange resin membranes can be satisfactorily utilized for measurement of these ion in such media when present singly or in a mixture.     

Curing characteristics and mechanical properties of alkali‐treated grass‐fiber‐filled natural rubber composites and effects of bonding agent

To improve adhesion between fiber and matrix, natural rubber was reinforced with a special type of alkali‐treated grass fiber (Cyperus Tegetum Rox b). The cure characteristics and mechanical properties of grass‐fiber‐filled natural rubber composites with different mesh sizes were studied with various fiber loadings. Increasing the amount of fibers resulted in the composites having reduced tensile strength but increased modulus. The better mechanical properties of the 400‐mesh grass‐fiber‐filled natural rubber composite showed that the rubber/fiber interface was improved by the addition of resorcinol formaldehyde latex (RFL) as bonding agent for this particular formulation. The optimum cure time decreased with increases in fiber loading, but there was no appreciable change in scorch time. Although the optimum cure time of vulcanizates having RFL‐treated fibers was higher than that of the other vulcanizates, it decreased with fiber loading in the presence of RFL as the bonding agent. But this value was lower than that of the rubber composite without RFL. Investigation of equilibrium swelling in a hydrocarbon solvent was also carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3151–3160, 2006     

Inhibition of corrosion of mild steel in acid media by N′-benzylidene-3-(quinolin-4-ylthio)propanohydrazide

In the present investigation a new corrosion inhibitor, N′-(3,4-dihydroxybenzylidene)-3-{[8-(trifluoromethyl)quinolin-4-yl]thio}propanohydrazide(DHBTPH) was synthesized, characterized and tested as a corrosion inhibitor for mild steel in HCl (1 M, 2 M) and H₂SO₄ (0·5 M, 1 M) solutions using weight-loss method, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. The corrosion inhibition efficiency measured by all the above three techniques were in good agreement with each other. The results showed that DHBTPH is a very good inhibitor for mild steel in acidic media. The inhibition efficiency in different acid media was found to be in the decreasing order 0·5 M H₂SO₄ > 1 M HCl > 1 M H₂SO₄ > 2 M HCl. The inhibition efficiency increases with increasing inhibitor concentration and with increasing temperature. It acts as an anodic inhibitor. Thermodynamic and activation parameters are discussed. Adsorption of DHBTPH was found to follow the Langmuir’s adsorption isotherm. Chemisorption mechanism is proposed. The mild steel samples were also analysed by scanning electron microscopy (SEM).     

Electrical and mechanical properties of MgO added 0.5Ba(Zr<Subscript>0.2</Subscript>Ti<Subscript>0.8</Subscript>)O<Subscript>3</Subscript>–0.5(Ba<Subscript>0.7</Subscript>Ca<Subscript>0.3</Subscript>)TiO<Subscript>3</Subscript> (BZT–0.5BCT) composite ceramics

MgO (0–2.0 vol%) added Ba(Zr_0.2Ti_0.8)O₃–0.5(Ba_0.7Ca_0.3)TiO₃ (BZT-0.5BCT) ceramics have been prepared by the conventional solid-state reaction method. The effects of MgO powder on the phase formation, densification, dielectric, piezoelectric and mechanical properties (flexural strength, hardness) of the BZT-0.5BCT ceramics have been studied systematically. The synthesized powder could be densified to 97 % of true density at a temperature of 1350 °C. The MgO addition also provided materials with better mechanical properties. The most interesting aspect of MgO added samples is their relative permittivity vs. temperature response. MgO additions effectively suppress the relative permittivity around phase transition temperature. The aging rate of d₃₃ observed for BZT-0.5BCT is 14 %/decade. MgO addition reduces the ageing rate and for 1 vol% MgO added, BZT-0.5BCT shows aging rate of 3 %/decade. BZT-0.5BCT/MgO ceramics possesses good mechanical properties viz., flexural strength 93 MPa, which is almost 25 % higher than that of monolithic BZT-0.5BCT (73 MPa).     

Jute felt composite from lignin modified phenolic resin

Raw and dewaxed jute felt composites were prepared with resol and lignin modified phenol formaldehyde resin. Four different types of lignin modified resins were used by replacing phenol with lignin. The lignin modified resins were prepared from purified lignin obtained from paper industry waste black liquor. To investigate bonding between jute and resin, IR spectroscopy of jute felts and composites was carried out. The thermal stability of the composites was assessed by DSC and TGA. It was found that the lignin resin jute composite is thermally more stable than resol composite. XRD of jute felt and composite shows that the crystallinity of the jute fiber increases after composite preparation. The lignin resin composites were tested for water absorption and thickness swelling, and it was found that the results are comparable with those of resol jute composite. Composites prepared from lignin phenol formaldehyde resin with 50% phenol replacement has shown 75% tensile strength retention to that of pure resol jute composite.     

Poly(dimethylsiloxane)/poly(hexamethylene oxide) mixed macrodiol based polyurethane elastomers. I. Synthesis and properties

The compatibilizing effect of poly(hexamethylene oxide) (PHMO) on the synthesis of polyurethanes based on α,ω‐bis(6‐hydroxyethoxypropyl) poly(dimethylsiloxane) (PDMS) was investigated. The hard segments of the polyurethanes were based on 4,4′‐methylenediphenyl diisocyanate (MDI) and 1,4‐butanediol. The effects of the PDMS/PHMO composition, method of polyurethane synthesis, hard segment weight percentage, catalyst, and molecular weight of the PDMS on polyurethane synthesis, properties, and morphology were investigated using size exclusion chromatography, tensile testing, and differential scanning calorimetry (DSC). The large difference in the solubility parameters between PDMS and conventional reagents used in polyurethane synthesis was found to be the main problem associated with preparing PDMS‐based polyurethanes with good mechanical properties. Incorporation of a polyether macrodiol such as PHMO improved the compatibility and yielded polyurethanes with significantly improved mechanical properties and processability. The optimum PDMS/PHMO composition was 80 : 20 (w/w), which yielded a polyurethane with properties comparable to those of the commercial material Pellethane™ 2363‐80A. The one‐step polymerization was sensitive to the hard segment weight percentage of the polyurethane and was limited to materials with about a 40 wt % hard segment; higher concentrations yielded materials with poor mechanical properties. A catalyst was essential for the one‐step process and tetracoordinated tin catalysts (e.g., dibutyltin dilaurate) were the most effective. Two‐step bulk polymerization overcame most of the problems associated with reactant immiscibility by the end capping of the macrodiol and required no catalysts. The DSC results demonstrated that in cases where poor properties were observed, the corresponding polyurethanes were highly phase separated and the hard segments formed were generally longer than the average expected length based on the reactant stoichiometry. Based on these results, we postulated that at low levels (∼ 20 wt %) the soft segment component derived from PHMO macrodiol was concentrated mainly in the interfacial regions, strengthening the adhesion between hard and soft domains of PDMS‐based polyurethanes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 2026–2040, 2000     

Advances of electronic nose and its application in fresh foods: A review

ABSTRACT

The science and technology aspects of electronic nose (E-nose) has been developed rapidly in last decade (2006–2016). This paper reviews of the publications that that cover the developments in science and technological aspects of electronic nose together with its application in fresh foods. The first part of this review covers the sensing and pattern recognition system (PR) of E-nose. The second part covers the application of E-nose in classification, flavor detection, and evaluation of spoilage in fresh foods area. With more new sensor materials to be found and more combination between E-nose and other analysis technologies, the usages of E-nose in fresh foods will have wider prospects.