Catalytic transfer reduction of conjugated alkenes and an imine using polymer-supported formates

An efficient and mild method for catalytic transfer hydrogenation of CC and CN double bonds with the aid of resin-supported formate (PSF) as the hydrogen donor and palladium acetate as the catalyst is reported.     

Charge storage and relaxation process of polymer film by thermally stimulated discharge current technique

Charge storage and relaxation process of the polymide film electret were investigated using the thermally stimulated discharge current technique. Homo- and heterocharges were mainly observed up to and above the polarization temperature.     

Sorption and immobilization of cellulase on silicate clay minerals

The interaction of organic molecules with mineral surfaces is a subject of interest in a variety of disciplines. Enzymes are able to be sorbed and immobilized by clay minerals and humic colloids in soil environment. The present study was done to elucidate some aspects of sorption and immobilization of cellulase on soil components by analysis of the sorption, and immobilization of cellulase on Avicel, a soil sample, illite, kaolinite, montmorillonite, and palygorskite. Palygorskite displayed the highest sorption capacity. Sorbents coated with hydroxyaluminum displayed significantly higher capacity than uncoated sorbents. The positive effects of Al(OH)(x) coating on sorption capacities of the different sorbents were not equal. The effect decreased in the order soil > palygorskite > kaolinite > Avicel > montmorillonite > illite. The amount of sorbed cellulase desorbed from external surfaces of soil was quite low (about 16%), especially in coated samples (about 6%). X-ray diffraction analysis of K-montmorillonite and Ca-montmorillonite showed that Al(OH)(x) was intercalated between the montmorillonite layers. Immobilization of cellulase on the sorbents did not result in expansion of their crystal structures. Therefore, it may be concluded that the amount of cellulase immobilized on internal surfaces of the sorbents was negligible.     

FT-Raman spectroscopic study of calcium-rich and magnesium-rich carbonate minerals

Calcium and magnesium carbonates are important minerals found in sedimentary environments. Although sandstones are the most common rock colonized by endolith organisms, the production of calcium and magnesium carbonates is important in survival strategies of organisms and as a source for the removal of oxalate ions. Extremophile organisms in some situations may convert or destroy carbonates of calcium and magnesium, which gives important information about the conditions under which these organisms can survive. The identification on the surface of Mars of 'White Rock' formations, in Juventae Chasma or Sabaea Terra, as possibly carbonate rocks makes the study of these minerals a prerequisite of remote Martian exploration. Here, we show the protocol for the identification by Raman spectroscopy of different calcium and magnesium carbonates and we present a database of relevance in the search for life, extinct or extant, on Mars; this will be useful for the assessment of data obtained from remote, miniaturized Raman spectrometers now proposed for Mars exploration.     

Life in the sabkha: Raman spectroscopy of halotrophic extremophiles of relevance to planetary exploration

The Raman spectroscopic biosignatures of halotrophic cyanobacterial extremophiles from sabkha evaporitic saltpans are reported for the first time and ideas about the possible survival strategies in operation have been forthcoming. The biochemicals produced by the cyanobacteria which colonise the interfaces between large plates of clear selenitic gypsum, halite, and dolomitized calcium carbonates in the centre of the salt pans are identifiably different from those which are produced by benthic cyanobacterial mats colonising the surface of the salt pan edges in the intertidal zone. The prediction that similar geological formations would have been present on early Mars and which could now be underlying the highly peroxidised regolith on the surface of the planet has been confirmed by recent satellite observations from Mars orbit and by localised traverses by robotic surface rovers. The successful adoption of miniaturised Raman spectroscopic instrumentation as part of a scientific package for detection of extant life or biomolecular traces of extinct life on proposed future Mars missions will depend critically on interpretation of data from terrestrial Mars analogues such as sabkhas, of which the current study is an example.     

Photoelectrochemistry of conducting polymers modified with electron-acceptor moieties

The photoelectrochemical behavior of two polymers of the polythiophene series containing electron-acceptor groups in the main chain was studied and compared to that of the nonmodified polymer, poly(2,2'-bithiophene), PBT. The acceptor groups were 2,2'-bipyridine and biphenyl, which are electron-deficient as compared to the bithiophene unit. All three polymers demonstrated a pronounced photovoltaic effect, which for PBT was consistent with data reported earlier. The introduction of the electron-acceptor moieties was found to significantly enhance the magnitude of the steady-state photocurrent as well as to drastically alter the dependencies of the photocurrent on the polymer film thickness and the external bias. These observations indicated that the mechanism of photocurrent generation in the modified polymers differs from that in nonmodified polymer and involves the electron transfer to the electron-acceptor moieties in the polymer main chain. The values of the external quantum efficiency were estimated in a liquid-cell arrangement to be 0.27 and 0.19% for modified and nonmodified polymers, respectively.     

Charged Dirac Particles’ Hawking Radiation via Tunneling of Both Horizons and Thermodynamics Properties of Kerr–Newman–Kasuya–Taub–NUT–AdS Black Holes

We investigate Hawking radiation of electrically and magnetically charged Dirac particles from a dyonic Kerr–Newman–Kasuya–Taub–NUT–Anti-de Sitter (KNKTN–AdS) black hole by considering thermal characters of both the outer and inner horizons. We apply Damour–Ruffini method and membrane method to calculate the temperature and the entropy of the inner horizon of the KNKTN–AdS black hole. The inner horizon admits thermal character with positive temperature and entropy proportional to its area. The inner horizon entropy contributes to the total entropy of the black hole in the context of Nernst theorem. Considering conservation of energy, charges, angular momentum, and the back-reaction of emitting particles to the spacetime, we obtain the emission spectra for both the inner and outer horizons. The total emission rate is obtained as the product of the emission rates of the inner and outer horizons. It deviates from the purely thermal spectrum with the leading term exactly the Boltzman factor and can bring some information out. The result thus can be treated as an explanation to the information loss paradox.     

Thermal recrystallization of physical vapor deposition based germanium thin films on bulk silicon (100)

We demonstrate a simple, low‐cost, and scalable process for obtaining uniform, smooth surfaced, high quality mono‐crystalline germanium (100) thin films on silicon (100). The germanium thin films were deposited on a silicon substrate using plasma‐assisted sputtering based physical vapor deposition. They were crystallized by annealing at various temperatures ranging from 700 °C to 1100 °C. We report that the best quality germanium thin films are obtained above the melting point of germanium (937 °C), thus offering a method for in‐situ Czochralski process. We show well‐behaved high‐κ /metal gate metal–oxide–semiconductor capacitors (MOSCAPs) using this film. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)