Multiplex PCR-based strategy to detect contamination with mycotoxigenic Fusarium species in rice and fingermillet collected from southern India

BACKGROUND: The genus Fusarium comprises a diverse group of fungi including several species that produce mycotoxins in food commodities. In the present study, a multiplex PCR was standardised for the group‐specific detection of fumonisin‐producing and trichothecene‐producing strains of Fusarium species. Primers for genus‐level recognition of Fusarium spp. were designed from the internal transcribed spacer regions 1 and 2 of rDNA. Primers for group‐specific detection were designed from the tri5 and tri6 genes involved in trichothecene biosynthesis and the fum1 and fum13 genes involved in fumonisin biosynthesis. RESULTS: Among the various genera and their strains tested, all the 85 confirmed Fusarium strains were positive for rDNA gene and the rest stayed negative. From among the Fusarium strains, 15 had amplification for trichothecene‐ and 20 for fumonisin‐encoding genes. All PCR positive trichothecene chemotypes of Fusarium species tested were positive for chemical analysis but in the case of fumonisins, of the 20 PCR positive cultures, only 13 showed positive for chemical analysis by HPTLC. CONCLUSION: The assay described here provided a rapid and reliable detection of trichothecene‐ and fumonisin‐producing Fusarium directly from natural food grains and the results were always comparable with a conventional HPTLC detection method. It can, therefore, be used by the food industry to monitor quality and safety. Copyright © 2011 Society of Chemical Industry     

Properties of brush plated CdxZn1−xTe thin films

Cd_xZn_1−xTe (0  x  0.5) thin films were deposited for the first time by the brush plating technique using cadmium sulphate, zinc sulphate and tellurium dioxide precursors. The deposition current density was maintained at 100 mA cm⁻². X-ray diffraction studies indicated the formation of cubic phase with (1 1 1), (2 2 0), (3 1 1) orientations. From optical absorption measurements the band gaps of the films are found to be direct. AFM studies indicate a surface roughness around 54 Å. Density of the films of different composition has been estimated. Laser Raman studies indicated CdTe like LO and TO phonons.     

Synthesis of polymer stabilized silver and gold nanostructures

This review article is focused on the various approaches that have been made to synthesize metal nanoparticles with predetermined shape, size, and fair stability. Due emphasis has been given on polymer stabilized nanoparticles. In addition use of other varieties of stabilizers like inorganic salts, organic compounds, organic solvent, biological molecules, etc. have also been discussed. Finally, formation of two and three-dimensional nanostructures like nanowires, nanodiscs, nanoprisms has also been revealed.     

Synthesis,Characterization, and Evaluation of Mesoporous MCM-41-supported Molybdenum Hydrotreating Catalysts

Abstract

Mesoporous MCM-41 material with high surface area and narrow pore size distribution was synthesized and used as a support for Mo, CoMo, and NiMo catalysts. The molybdenum loading was varied from 2–14 wt% on MCM-41. On 10 wt% Mo/MCM-41, the promoter Co or Ni concentration was varied from 1–5 wt%. All the catalyst samples were characterized by surface area, low temperature oxygen chemisorption, x-ray diffraction (XRD), and temperature programmed reduction methods. Characterization results show that Mo is well dispersed on MCM-41 up to 10 wt%. The catalytic activities were evaluated for thiophene hydrodesulphurization (HDS), cyclohexene hydrogenation (HYD), and furan hydrodeoxygenation (HDO). All three catalytic functionalities vary in a similar manner to that of oxygen chemisorption as a function of Mo loading, indicating that there is a correlation between oxygen uptake and catalytic sites. The activities of these catalysts were compared with γ-Al₂O₃- and amorphous SiO₂-supported catalysts. It was found that MCM-41-supported Mo catalysts displayed superior activities.     

A Cost-Effective Ultrasonic Sensor-Based Driver-Assistance System for Congested Traffic Conditions

In urban areas, congested traffic results in a large number of accidents at low speeds. This paper describes an accurate and fast driver-assistance system (DAS) that detects obstacles and warns the driver in advance of possible collisions in such a congested traffic environment. A laboratory prototype of the system is built and tested by simulating different weather conditions in the laboratory. The proposed DAS is also suitable as a parking-assistance system. Ultrasonic sensors are used to detect obstacles in this paper because they have several advantages over other types of sensors in short-range object detection. Multiple sensors are needed to get a full-field view because of the limited lateral detectable range of ultrasonic sensors. Furthermore, crosstalk is a common problem when multiple ultrasonic sensors are used. A simple microcontroller-based method to reduce crosstalk between sensors is described, which is achieved by firing each transducer by a pseudorandom number of pulses so that the echo of each transducer can uniquely be identified. Existing DASs need more time to reliably detect the objects, making them unsuitable for DASs, where time is a critical factor. A method to reduce the obstacle detection time of the system is also proposed. The cost of this high-performance system is expected to be very reasonable. All the practical implementation details are included. Extensive experimentation has been carried out, and the results confirm the speed and reliability of the presented system.     

Composite-two-phase wavelength reservation scheme for dynamic optical networks

An enhanced hybrid scheme of wavelength reservation for dynamic wavelength routed optical networks is proposed. The performance of a newly introduced composite-two-phase reservation protocol (C2P-RP) is evaluated and compared with the existing hybrid reservation protocol. By offering connection requests an enhanced scope of finding an end-to-end available wavelength, the C2P-RP scheme shows improved connection-request blocking performance.     

Highly conductive and porous activated reduced graphene oxide films for high-power supercapacitors

We present a novel method to prepare highly conductive, free-standing, and flexible porous carbon thin films by chemical activation of reduced graphene oxide paper. These flexible carbon thin films possess a very high specific surface area of 2400 m(2) g(-1) with a high in-plane electrical conductivity of 5880 S m(-1). This is the highest specific surface area for a free-standing carbon film reported to date. A two-electrode supercapacitor using these carbon films as electrodes demonstrated an excellent high-frequency response, an extremely low equivalent series resistance on the order of 0.1 ohm, and a high-power delivery of about 500 kW kg(-1). While higher frequency and power values for graphene materials have been reported, these are the highest values achieved while simultaneously maintaining excellent specific capacitances and energy densities of 120 F g(-1) and 26 W h kg(-1), respectively. In addition, these free-standing thin films provide a route to simplify the electrode-manufacturing process by eliminating conducting additives and binders. The synthetic process is also compatible with existing industrial level KOH activation processes and roll-to-roll thin-film fabrication technologies.     

Properties of pulse plated SnSe films

In this work, the pulse electrodeposition technique has been employed for the first time to deposit SnSe films from a bath containing Analar grade 50?mM tin chloride (SnCl₄) and 5?mM SeO₂. The XRD profile of SnSe thin films deposited at different duty cycles indicate the peaks corresponding to SnSe. Atomic force microscopy studies indicated that the surface roughness increased from 0.5 to 1.5?nm with duty cycle. The transmission spectra exhibited interference fringes. The value of refractive index at 780?nm was 2.1, this value decreased to 1.95 with decrease of duty cycle. The room temperature resistivity increased from 0.1 to 10?Ωcm with decrease of duty cycle. Photo electrochemical cell studies were made using the films deposited at different duty cycles. For duty cycles greater than 15% photo output was observed. For a film deposited at 50% duty cycle, an open circuit voltage of 0.55?V and a short circuit current density of 5.0?mA?cm^?2 at 60 mW?cm^?2 illumination. Capacitance voltage measurements indicated V_fb?=?0.67?V (SCE) and p type, carrier density?=?6.98?×?10¹⁶?cm^?3.     

Synthesis, characterization, and nonlinear optical properties of donor–acceptor conjugated polymers and polymer/Ag nanocomposites

Two new donor–acceptor (D–A) conjugated polymers P1 and P2 containing 3,4-didodecyloxythiophene and 1,3,4-oxadiazole units are synthesized via Wittig reaction methodology. Cyclic voltammetry studies reveal that the polymers are both p and n dopable, and possess low-lying LUMO energy levels (?3.34?eV for P1 and ?3.46?eV for P2) and high-lying HOMO energy levels (?5.34?eV for P1 and ?5.27?eV for P2). The optical band gap of the polymers is in the range of 2.25–2.29?eV, calculated from the onset absorption edge. The polymers emit orange to yellow light in the film state when irradiated with a UV light. The synthesized polymers are used to prepare polymer nanocomposites with different wt% of silver nanoparticles. The polymer nanocomposites are characterized by UV–Vis absorption spectroscopy, field emission scanning electron microscopy, and thermogravimetric analysis. Both polymers and polymer/Ag nanocomposites show good thermal stability with onset decomposition temperature around 300?°C under nitrogen atmosphere. The nonlinear optical properties of polymers and polymer/Ag nanocomposites are measured by Z-scan technique. Both polymers and polymer nanocomposites show a good optical limiting behavior. Nearly five times enhancement in the nonlinear optical properties is observed for polymer/Ag nanocomposites. The value of effective two-photon absorption coefficient (β) is in the order of 10^?10–10^?11?m/W. These results indicate that the synthesized polymers (P1 and P2) and their Ag nanocomposites are expected to be good candidates for application in photonic devices.