Production of liquid biofuels from renewable resources

This article is an up-to-date review of the literature available on the subject of liquid biofuels. In search of a suitable fuel alternative to fast depleting fossil fuel and oil reserves and in serious consideration of the environmental issues associated with the extensive use of fuels based on petrochemicals, research work is in progress worldwide. Researchers have been re-directing their interests in biomass based fuels, which currently seem to be the only logical alternative for sustainable development in the context of economical and environmental considerations. Renewable bioresources are available globally in the form of residual agricultural biomass and wastes, which can be transformed into liquid biofuels. However, the process of conversion, or chemical transformation, could be very expensive and not worth-while to use for an economical large-scale commercial supply of biofuels. Hence, there is still need for much research to be done for an effective, economical and efficient conversion process. Therefore, this article is written as a broad overview of the subject, and includes information based on the research conducted globally by scientists according to their local socio-cultural and economic situations.     

Mechanism of charge recombination and IPCE in ZnO dye‐sensitized solar cells having I−/I and Br−/Br redox couple

The influence of intensity and wavelength variation on the solar cell parameters of two different ZnO‐based liquid state DSSCs named as Cell (A) ZnO/EosinY/LiI and Cell (B) ZnO/EosinY/LiBr was studied. It was found that V_oc and I_sc depend logarithmically and linearly on light flux, respectively, which indicates that light absorption and carrier diffusion do not limit the solar cell efficiency. The data was analyzed to ascertain the charge recombination mechanism between conduction band electrons and the electrolytes. The regeneration of dye due to I⁻/I₃ and Br⁻/Br redox couple was examined by studying the wavelength dependence of IPCE. An estimation of series and shunt resistance is made using two methods: (i) different illumination method (ii) single I–V curve, for the two cells in order to understand the role of the electrolyte in controlling the solar cell parameters. Copyright © 2010 John Wiley & Sons, Ltd.     

A new class of PANI-Ag core-shell nanorods with sensing dimensions

A single-step, cost-effective and eco-safe synthesis of a new class of homogeneous silver-polyaniline (PANI-Ag) core-shell nanorods is carried out via mild photolysis by ultraviolet radiation from sunlight (SUN UV-radiation). X-ray diffraction (XRD) of these core-shell nanorods gives two additional peaks from PANI centered at 2θ = 20.5° and 24. 9°. A validation of the core-shell structural information is given by transmission electron spectroscopy (TEM) whereas the tubular shape morphology is determined by scanning electron microscopy (SEM). UV-Vis. absorption shows a strong blue-shift along with photoluminescence emission. Fourier transform-infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDX) also support the core-shell formation. Thermogravimetric analysis (TGA) shows good thermal stability and allows excellent detection of hydrogen peroxide and hydrazine. The cyclic voltammetry (CV) results show excellent electro-activation, indicating its promising potential in sensing of clinical and environmental analytes.     

Effect of m‐nitroaniline doping on the optical humidity‐sensing characteristics of cobalt/poly(vinyl alcohol) nanocomposites

Cobalt (Co) nanoparticles (with different loadings, 1 and 2 wt %, of Co) were synthesized in situ in a poly(vinyl alcohol) (PVA) matrix with and without meta‐nitroaniline (m‐NA) as a dopant (2.5 wt %). The obtained nanocomposite films were characterized with various physicochemical techniques, including ultraviolet–visible spectrophotometry, X‐ray diffraction analysis, scanning electron microscopy, and Fourier transform infrared analysis. To study the effect of the humidity, the nanocomposite solutions were coated on planar glass substrates. The beam of an He–Ne laser was incident normal to the film surface and was subjected to variable relative humidities (RHs; 4–93%); the transmitted intensity was measured on a photovoltaic diode. Variations in the intensity of light caused by the changes in RH within the range 3–93% were recorded. We optimized the response by varying the film thickness by coating the solution layer by layer. We generated the RH (4–100%) by passing wet water vapors. The neat PVA film of similar thickness gave humidity sensing in the range 78–93% RH. The sensors with m‐NA‐doped Co/PVA gave better sensitivity (6.4 mV/% RH) than the undoped samples (1.78–2.45 mV/% RH), exhibiting a fast response of 3 s (2–93% RH) and a recovery of 10 s (93 to 2% RH). These samples also showed reversible behavior and long‐term stability (for nearly a year) with a good sensitivity and a large dynamic range (2–95% RH). An attempt was made to explain the results on the basis of a bulk mechanism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of pH‐sensitive hydrogels by graft polymerization of itaconic acid on tragacanth gum

Graft polymerization of itaconic acid on tragacanth gum (TG) was carried out using potassium persulfate as initiator to develop smart hydrogels for drug delivery systems. The effect of the grafting parameters on the degree of grafting was investigated. The grafting was significantly influenced by the reaction medium, the reaction temperature and the monomer concentration. The monomer dependency of the system was found to be 1.52. The hydrogels were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X‐ray diffraction. The grafted TG had an amorphous nature and exhibited excellent swelling in water and strong dependence on the pH of the medium. The grafted TG showed pH‐dependent release of ciprofloxacin which offers the possibility of using these materials in colon‐specific drug targeting for human healthcare systems. © 2018 Society of Chemical Industry     

Phonon dispersion and specific heat in <Emphasis Type=Italic>trans</Emphasis> 1,4, poly (2,3-dimethylbutadiene)

A comprehensive study of the normal modes and their dispersion for trans 1,4-poly (2,3 dimethylbutadiene) is described in the reduced zone scheme using Wilson’s GF matrix method as modified by Higg’s for an infinite polymeric chain. Urey Bradley force field is obtained by least square fitting of the observed IR and Raman bands. Optically active frequencies corresponding to the zone center and zone boundary are identified and discussed. Some of the characteristic features of dispersion curves are repulsion accompanied by exchange of character and Von Hove type singularities. The evaluation of normal modes and their dispersion has been taken to logical conclusion by calculating the heat capacity as a function of temperature. Specific heat has been obtained from dispersion curves via density of states in the range 10–400 K using Debye’s relation. The predictive values of specific heat show a typical variation for an one dimensional polymeric system.     

Seasonal variation in content,chemical composition and antimicrobial and cytotoxic activities of essential oils from four Mentha species

BACKGROUND: The aim of the present study was to appraise variation in the chemical composition, and antimicrobial and cytotoxic activities of essential oils from the leaves of four Mentha species—M. arvensis, M. piperita, M. longifolia and M. spicata—as affected by harvesting season. Disc diffusion and broth microdilution susceptibility assays were used to evaluate the antimicrobial activity of Mentha essential oils against a panel of microorganisms. The cytotoxicity of essential oils was tested on breast cancer (MCF‐7) and prostate cancer (LNCaP) cell lines using the MTT assay. RESULTS: The essential oil contents of M. arvensis, M. piperita, M. longifolia and M. spicata were 17.0, 12.2, 10.8 and 12.0 g kg^?1 from the summer and 9.20, 10.5, 7.00 and 9.50 g kg^?1 from the winter crops, respectively. Gas chromatographic–mass spectrometric analysis revealed that mostly quantitative rather than qualitative variation was observed in the oil composition of each species. The principal chemical constituents determined in M. arvensis, M. piperita, M. longifolia and M. spicata essential oils from both seasons were menthol, menthone, piperitenone oxide and carvone, respectively. The tested essential oils and their major components exhibited notable antimicrobial activity against most of the plant and human pathogens tested. The tested essential oils also exhibited good cytotoxicity potential. CONCLUSION: Of the Mentha essential oils tested, M. arvensis essential oil showed relatively better antimicrobial and cytotoxic activities. A significant variation in the content of most of the chemical components and biological activities of seasonally collected samples was documented. Copyright © 2010 Society of Chemical Industry     

Prickly Ni3S2 nanowires modified CdS nanoparticles for highly enhanced visible-light photocatalytic H2 production

The photocatalytic water splitting strategy is one of the most promising ways to achieve clean and renewable solar-to-hydrogen energy conversion. In this study, a highly enhanced photocatalytic H₂ production system has been achieved, using CdS nanoparticles (NPs) decorated on prickly Ni₃S₂ nanowires (NWs) as the light-driven photocatalyst. The photocatalyst was prepared by a co-precipitated method in which spiky Ni NWs were employed as starting material for prickly Ni₃S₂ NWs. Characterization analysis (XRD, TEM, XPS, etc.) show the high purity of Ni₃S₂/CdS hybrid structures and the well deposition of CdS NPs on prickly Ni₃S₂ NWs. Besides, the as synthesized Ni₃S₂/CdS photocatalyst exhibit reduced photoluminescence peak intensity, which means the Ni₃S₂ NWs functions as electron collector and transporter to quench the photoluminescence of CdS. This prickly Ni₃S₂/CdS nanocomposite demonstrates a 70 times higher H₂ production rate than that of pure CdS and a quantum efficiency of 12.3% at the wavelength of 400 nm in the absence of noble metals. This enhanced H₂ production activity is better than the one of CdS loaded with 0.5 wt% Pt. Our findings highlight the potential application of Ni₃S₂/CdS hybrid structures for visible light photocatalytic hydrogen yielding in the energy conversion field.     

Upgrading Information Security and Protection for Palm-Print Templates

Biometric systems proven to be one of the most reliable and robust method for human identification. Integration of biometrics among the standard of living provokes the necessity to vogue secure authentication systems. The use of palm-prints for user access and authentication has increased in the last decade. To give the essential security and protection benefits, conventional neural networks (CNNs) has been bestowed during this work. The combined CNN and feature transform structure is employed for mapping palm-prints to random base-n codes. Further, secure hash algorithm (SHA-3) is used to generate secure palm-print templates. The proficiency of the proposed approach has been tested on PolyU, CASIA and IIT-Delhi palm-print datasets. The best recognition performance in terms of Equal Error Rate (EER) of 0.62% and Genuine Acceptance Rate (GAR) of 99.05% was achieved on PolyU database.