Similarity structure of wave-collapse

Similarity transformations of the cubic Schrödinger equation (CSE) are investigated. The transformations are used to remove the explicit time variation in the CSE and reduce it to differential equations in the spatial variables only. Two different methods for similarity reduction are employed and the significance of similarity in the evolution of a collapsing wave packet is investigated. Numerical solutions in radial symmetry demonstrate that the similarity behaviour is local in space and time, and that some similarity solutions must be classified as improper solutions. The nature of the collapsing singularity is reexamined.     

In vivo measurements of T1 relaxation times of 31P-metabolites in human skeletal muscle

The T1 relaxation times were estimated for 31P-metabolites in human skeletal muscle. Five healthy volunteers were examined in a 1.5 Tesla wholebody imaging system using an inversion recovery pulse sequence. The calculated T1 relaxation times ranged from 5.517 sec for phosphocreatine to 3.603 sec for -ATP.     

Doping effects in the Sr14Cu24O41-type structure: a Raman scattering study

Polarized micro-Raman spectra of different compounds belonging to the Sr₁₄Cu₂₄O₄₁-type structure were studied. In the spectra with parallel polarization along the plane crystal axes of the insulating samples Sr₉R₅Cu₂₄O₄₁ (R = La, Y) a broad peak near 3000 cm⁻¹, similar to the well-known two-magnon peak in the layered cuprates, was observed. In addition to the Raman lines characteristic for this structure, we observed only in the spectra with parallel to the chains numerous lines between 100 and 1200 cm⁻¹, probably originating from Raman-forbidden infrared-active only LO phonons and their combinations. In the spectra of the conducting compounds Sr_14−xCa_xCu₂₄O₄₁ (x = 0,7) these features were very weak or disappeared. We interpret these results as Raman evidence for hole doping of the Cu₂O₃ “spin-ladder” planes and for a redistribution of holes between chains and planes through Ca substitution in the case of the rare-earth-free samples.     

Far-infrared spectroscopy of the supreconductor YBa2Cu4O8

The frequencies of allB _1u (z) phonon modes predicted by a group-theoretical analysis were measured and found to agree well with recent lattice dynamical calculations for this compound. We report also the determination of two superconducting gap values in YBa₂Cu₄O₈ through phonon self-energy effects in the normal and superconducting conducting state. The gap-to-T _c ratios obtained from an analysis of these effects are 2 ₁/kT _c 2.5 and 5.82 ₂/kT _c 9.2. This coincides with previous results of both phononic and electronic Raman scattering where values of 2.1 and 6.3 were found. We further find anomalous softenings of two phonon modes 40 Kabove T _c , which correlate with an observed deviation from the linear temperature dependence of the average plasma frequency _p (T).     

Dual‐Function Cobalt–Nickel Nanoparticles Tailored for High‐Temperature Induction‐Heated Steam Methane Reforming

The tailored chemical synthesis of binary and ternary alloy nanoparticles with a uniform elemental composition is presented. Their dual use as magnetic susceptors for induction heating and catalytic agent for steam reforming of methane to produce hydrogen at temperatures near and above 800 °C is demonstrated. The heating and catalytic performance of two chemically synthesized samples of CoNi and Cu ? CoNi are compared and held against a traditional Ni‐based reforming catalyst. The structural, magnetic, and catalytic properties of the samples were characterized by X‐ray diffraction, elemental analysis, magnetometry, and reactivity measurements. For induction‐heated catalysts, the conversion rate of methane is limited by chemical reactivity, as opposed to the case of traditional externally heated reformers where heat transport limitations are the limiting factor. Catalyst production by the synthetic route allows controlled doping with miniscule concentrations of auxiliary metals.     

Energy transfer dynamics of nanocrystal-polymer composites

Steady-state and time-resolved photoluminescence spectroscopy are used to examine the photoluminescent properties of nanocrystal-polymer composites consisting of colloidal PbS nanocrystals blended with poly(2-methoxy-5(2-ethylhexyloxy)-p-phenylene vinylene). Quenching of the emission from the conjugated polymer due to the PbS nanocrystals is observed along with band edge emission from the ligand capped PbS nanocrystals. A decrease in the photoluminescence lifetime of MEH-PPV is also observed in the thin film nanocrystal-polymer composite materials. Photoluminescence excitation spectroscopy of the PbS nanocrystal emission from the composite shows features attributed to MEH-PPV providing evidence of a F?rster transfer process.     

Preliminary results on optimization of pilot scale pretreatment of wheat straw used in coproduction of bioethanol and electricity

The overall objective in this European Union-project is to develop cost and energy effective production systems for coproduction of bioethanol and electricity based on integrated biomass utilization. A pilot plan reactor for hydrothermal pretreatment (including weak acid hydrolysis, wet oxidation, and steam pretreatment) with a capacity of 100 kg/h was constructed and tested for pretreatment of wheat straw for ethanol production. Highest hemicellulose (C5 sugar) recovery and extraction of hemicellulose sugars was obtained at 190°C whereas highest C6 sugar yield was obtained at 200°C. Lowest toxicity of hydrolysates was observed at 190°C; however, addition of H₂O₂ improved the fermentability and sugar recoveries at the higher temperatures. The estimated total ethanol production was 223 kg/t straw assuming utilisation of both C6 and C5 during fermentation, and 0.5 g ethanol/g sugar.     

Studies on organophosphorus compounds XLVII preparation of thiated synthons of amides,lactams and imides by use of some new p,s-containing reagents

The thionation properties of 2,4-bismethylthio-1,3,2,4-dithiadiphosphetane 2,4-disulfide, $\text{1}$, 2,4-bis(4-phen-oxyphenyl)-1,3,2,4-dithiaphosphetan is that $\text{2}$, $\text{3}$ and thionate most amides and lactams In THF at room temperature (reaction time 5 min) to give the corresponding thionated compounds. Imides are easily thionated by $\text{2}$, $\text{3}$ and $\text{4}$ In DME at 60 °C. The reactions of $\text{1}$ with amides, imides and most lactams are run at 60°C to give good yields of the corresponding thionated compounds.     

Pre-equilibrium capillary zone electrophoresis or frontal analysis: advantages of plateau peak conditions in affinity capillary electrophoresis

The feasibility of using the affinity CE methodologies pre-equilibrium CZE and CE frontal analysis was tested on interaction systems exhibiting rapid on-and-off kinetics. Experimentally, the methodologies differ only with respect to the volume of sample introduced into the capillary. Pre-equilibrium CZE has been considered amendable to interactions with slow on-and-off kinetics only; however, it has recently been applied in studies of interactions with fast on-and-off kinetics. The effect of varying the sample volume introduced hydrodynamically into the capillary on the apparent degree of complexation was studied. For two different binding systems, the fraction of free analyte was found to be overestimated using pre-equilibrium CZE as compared to volumes providing plateau peak conditions as used with frontal analysis. Results indicate that frontal analysis conditions lead to more robust binding assays and thus more reliable data. The validity of data obtained by pre-equilibrium CZE may be low, thus the use of an experimental setup providing plateau peaks is highly recommended. It is suggested that the effect of altering the sample volume on the degree of binding should be investigated as part of method development and validation.