Fullerene derived molecularly imprinted polymer for chemosensing of adenosine-5′-triphosphate (ATP)

For molecular imprinting of oxidatively electroactive analytes by electropolymerization, we used herein reductively electroactive functional monomers. As a proof of concept, we applied C₆₀ fullerene adducts as such for the first time. For that, we derivatized C₆₀ to bear either an uracil or an amide, or a carboxy addend for recognition of the adenosine-5′-triphosphate (ATP) oxidizable analyte with the ATP-templated molecularly imprinted polymer (MIP-ATP). Accordingly, the ATP complex with all of the functional monomers formed in solution was potentiodynamically electropolymerized to deposit an MIP-ATP film either on an Au electrode of the quartz crystal resonator or on a Pt disk electrode for the piezoelectric microgravimetry (PM) or capacitive impedimetry (CI) determination of ATP, respectively, under the flow-injection analysis (FIA) conditions. The apparent imprinting factor for ATP was ∼4.0. After extraction of the ATP template, analytical performance of the resulting chemosensors, including detectability, sensitivity, and selectivity, was characterized. The limit of detection was 0.3 and 0.03 mM ATP for the PM and CI chemosensor, respectively. The MIP-ATP film discriminated structural analogues of ATP quite well. The Langmuir, Freundlich, and Langmuir–Freundlich isotherms were fitted to the experimental data of the ATP sorption and sorption stability constants appeared to be nearly independent of the adopted sorption model.     

A satellite-borne experiment to study the fifth force

An experiment with a satellite-borne torsion balance capable of measuring the fifth force which couples to baryon number or lepton number with a strengtr gravity and range ~ 10⁹ cm is described.     

Mössbauer and esr studies on structural evolution of some iron (III) doped rare earth oxides

Fe (III) ions were coprecipitated as 3 wt % and 5 wt % with La (OH)₃, Pr (OH)₃ and Nd (OH)₃. These coprecipitates were heated for 4 hours to 24 hours in air at temperatures ranging from 100°C to 1100°C. Samples with 5 wt % of Fe (III) ions were investigated by Mössbauer resonance at 300 and 77 K and those with 3 wt % of Fe (III) ions were studied by ESR spectroscopy. Characterization of the valency, coordination and chemical identity of the iron ions in the initial and thermally treated coprecipitates permit to follow the nature of thermal and microstructural processes which lead to the formation of iron-doped rare earth oxides.     

Microstructure change in poly(ethersulfone) films by swift heavy ions

PES membrane of thickness 25 μm was irradiated by Cl⁹⁺ ions of energy 100 MeV at IUAC, New Delhi. Microstructure changes due to exposure to high-energy ions were investigated by Fourier transform infrared (FTIR) and ultraviolet/visible (UV/vis) absorption spectroscopies, X-ray diffraction technique and by dynamic mechanical analysis (DMA). A significant loss of crystallinity is observed by the XRD data. Particle size or grain size calculated using Scherrer formula indicates measurable change in particle size of irradiated samples. The polymer chain scissions and structure degradations are expected to occur for irradiated samples. Optical properties of the films were changed due to irradiation that could be clearly seen in the absorption spectra. FTIR does not show the remarkable change in the irradiated samples, but there is some change in the surface roughness observed by AFM.     

High-efficiency metal-semiconductor-metal photodetectors on heteroepitaxially grown Ge on Si

We demonstrate extremely efficient germanium-on-silicon metal-semiconductor-metal photodetectors with responsivities (R) as high as 0.85 A/W at 1.55 microm and 2V reverse bias. Ge was directly grown on Si by using a novel heteroepitaxial growth technique, which uses multisteps of growth and hydrogen annealing to reduce surface roughness and threading dislocations that form due to the 4.2% lattice mismatch. Photodiodes on such layers exhibit reverse dark currents of 100 mA/cm2 and external quantum efficiency up to 68%. This technology is promising to realize monolithically integrated optoelectronics.     

Studies on phenothiazines. Part 16 . Synthesis and spectral studies of substituted 1,2-dichlorophenothiazines

Synthesis of the title compounds by the Smiles rearrangement has been reported. 1,2-Dichloro-7-substituted phenothiazines have been prepared by the Smiles rearrangement of 3,4-dichloro-2-formamido-2′-nitro-4′-substituted-diphenyl sulphides. The latter were obtained by the formylation of the diphenyl sulphides obtained by the condensation of 2-amino-3,4-dichlorobenzenethiol with o-halogenonitrobenzenes. 9-Nitrophenothiazines have been prepared by the reaction of 2-amino-3,4-dichlorobenzenethiol with substituted o-halonitrobenzenes containing a nitro group at both ortho positions to the halo atom in which Smiles rearrangement occurs in situ. The ir, nmr and mass spectral studies are also included.     

Spreading properties of high polymers

Many linear polymers containing water-attracting groups spread uniformly at the airwater interface. The spreading property of polymethyl methacrylate is due to the ester groups which serve as anchors and promote spreading. The spreading of polystyrene, although it is a pure hydrocarbon, appears probably to be due to the end groups in each polymer molecule, introduced at the termination of the chains which act as anchors and facilitate spreading. The surface pressure extended by the films of the high polymers is a sort of two-dimensional swelling pressure. The distinguishing feature of these films is their high compressibility in the rectilinear portion of the F–A curve. The limiting areas for F–A curves are not independent of the concentrations of spreading solutions as might be expected. The primary cause of this phenomenon in the case of high polymers appears to be a more or less coherent sponge- or felt-like structure which develops at high concentration. The linear polymers, like polystyrene, become coiled up statistically and at higher concentration the coils become interlocked and produce an imperfectly spread film.     

SiGe optoelectronic metal-oxide semiconductor field-effect transistor

We propose a novel semiconductor optoelectronic switch that is a fusion of a Ge optical detector and a Si metal-oxide semiconductor field-effect transistor (MOSFET). The device operation is investigated with simulations and experiments. The switch can be fabricated at the nanoscale with extremely low capacitance. This device operates in telecommunication standard wavelengths, hence providing the surrounding Si circuitry with noise immunity from signaling. The Ge gate absorbs light, and the gate photocurrent is amplified at the drain terminal. Experimental current gain of up to 1000x is demonstrated. The device exhibits increased responsivity (approximately 3.5x) and lower off-state current (approximately 4x) compared with traditional detector schemes.     

Assessment of Five SGS Models for Low-Rem MHD Turbulence

Assessment of three regularization-based and two eddy-viscosity-based subgrid-scale (SGS) turbulence models for large eddy simulations (LES) are carried out in the context of magnetohydrodynamic (MHD) decaying homogeneous turbulence (DHT) with a Taylor scale Reynolds number (Re_λ) of 120 and a MHD transition-to-turbulence Taylor-Green vortex (TGV) problems with a Reynolds number of 3000, through direct comparisons to direct numerical simulations (DNS). Simulations are conducted using the low-magnetic Reynolds number approximation (Re_m<<1). LES predictions using the regularization-based Leray- α,LANS- α, and Clark- α SGS models, along with the eddy viscosity-based non-dynamic Smagorinsky and the dynamic Smagorinsky models are compared to in-house DNS for DHT and previous results for TGV. With regard to the regularization models, this work represents their first application to MHD turbulence. Analyses of turbulent kinetic energy decay rates, energy spectra, and vorticity fields made between the varying magnetic field cases demonstrated that the regularization models performed poorly compared to the eddy-viscosity models for all MHD cases, but the comparisons improved with increase in magnitude of magnetic field, due to a decrease in the population of SGS eddies within the flow field.