Photoemission Study of Perovskite-Type Manganites with Stripe Ordering

We have studied the chemical potential shift and changes in the electronic density of states near the Fermi level (E _F) as functions of temperature and carrier concentration in Pr_1−x Ca _x MnO₃ (PCMO) and Nd_1−x Sr _x MnO₃ (NSMO) by measurements of photoemission spectra. Suppression of the chemical potential shift as a function of carrier concentration has been observed in PCMO and NSMO near and in the composition range where the CE-type antiferromagnetic charge-ordered (CO) phase appears at low temperatures. This result indicates that there is charge self-organization on a microscopic scale such as stripe formation in this composition range. In the ferromagnetic metallic phase of NSMO, we found a large temperature-dependent chemical potential shift at low temperatures and attributed this to double-exchange mechanism. Suppression of the temperature-dependent chemical potential shift near Curie temperature was observed, possibly associated with the formation of correlated polarons. In the valence band near the E _F of PCMO, spectral weight was transferred with hole doping, leading to a finite intensity at E _F even in the paramagnetic insulating phase above the CO phase for x≳0.3, and as the temperature was lowered, a clear gap opening was observed in the CO phase.     

Analysis of formaldehyde, acetaldehyde and oligomers in recycled polyethylene terephthalate

Formaldehyde (FA), acetaldehyde (AA) and oligomers in recycled polyethylene terephthalate (PET) were analyzed by HPLC. All of the physically recycled PET contained detectable levels of FA, AA and oligomers, and the levels were almost the same as in used bottles. Most superclean-like and chemically recycled PET contained lower levels than new pellets. These compounds showed no decrease upon physical recycling, but showed a marked decrease upon superclean-like recycling. In PET sheets made using physically recycled PET, FA was decreased, though AA was increased by the sheeting process as same as new one. FA, AA and oligomers originated from PET resin and their levels in recycled products were almost equivalent to those in new products. It was concluded that there is no particular safety concern about their presence in recycled PET.     

Fast reactor core deformation due to stainless steel swelling and thermal bowing with irradiation enhanced and thermal creep

In order to establish a technique which will properly account for the LMFBR core deformation under various reactor operating conditions, two separate computer programs have been developed, and coupled together. The first of the two, “FEMCRP”, is a finite element creep analysis code for a long, straight, hexagonal tube. The second program owes its origin to BOX-V developed by ANL, but was later modified considerably by the authors to include the effect of stainless steel swelling. The computer program, HICODEM, is the cross between the two. It can analyze the equilibrium configuration of the core consisting of fuel subassemblies of various burnup histories, with corresponding degree of swelling and creep. The code can assume a mechanical clamping on the periphery of the core during the power operation, and after a desired length of time, it can bring the entire core to the refueling temperature and unclamp the constraint, the resultant equilibrium core configuration being successively obtained.     

Bacteriology of mycobacteria: taxonomic and morphological characteristics

Bacteriological characteristics of organisms belonging to Genus Mycobacterium which involves more than 60 species are described. Mycobacterial organisms can be divided into the following groups having differential characteristics, on the basis of the results of biological, biochemical, and genetic investigations, including lipid analysis, DNA probe test, and comparative 16S ribosomal RNA sequencing. First, Mycobacterium tuberculosis complex (M. tuberculosis, M. bovis, M. africanum, etc.). Second, cultivable but slowly growing nontuberculous mycobacteria, including photochromogens (Runyon Group I) such as M. kansasii, M. marinum, M. simiae, M. intermedium, and M. asiaticum, scotochromogens (Runyon Group II) such as M. scrofulaceum, M. szulgai, M. injectum, M. lentiflavum, and M. gordonae, nonphotochromogenens (Runyon Group III) such as M. avium, M. intracellulare, M. xenopi, M. malmoense, M. genavense, M. celatum, and M. gastri. Third, cultivable rapidly growing nontuberculous mycobacteria (Runyon Group IV) including M. fortuitum, M. chenolae, M. abscessus, M. phlei, and M. smegmatis. Fourth, noncultivable mycobacteria including M. leprae. About 30 species of Mycobacterium cause pulmonary, dermal, lymphatic, and disseminated infections in human beings. This paper mainly deals with the taxonomic, morphological, and other biological characteristics of these mycobacterial organisms.     

Macrosegregation in continuously cast steel slabs: preliminary theoretical investigation on the effect of steady state bulging

Model for computation of macrosegregation in slabs due to bulging. Assumptions involved. Simplification for the case of no bulging. Introduction of a modified stream function for the mushy zone. Computation of macrosegregation profiles for various conditions.     

Periodic Galerkin finite element method of tidal flow

This paper presents the finite element method of the analysis of tidal flow. Assuming that tidal flow is periodic, the Galerkin approach is employed as the numerical integration procedure in time using a trigonometric function as the interpolation function. The present method has shown to be suitable for computation especially from the point of computing time and numerical stability.     

Ultra-thin GaxIn1−xAs/InP (0≤x≤0.47) layer growth by chemical beam epitaxy

Ga_xIn_1?xAs/InP (0≤x≤0.47) lattice-matched and compressively strained quantum wells were grown by all gas source chemical beam epitaxy (CBE). Their optical properties were investigated by photoluminescence (PL) and optical absorption measurements. The thinnest Ga_xIn_1?xAs layer was 6Å-thick (2 monolayers) for Ga_0.47In_0.53As and 3Å-thick (1 monolayer) for InAs. In PL measurements, we found that for strained materials (x<0.47) luminescence intensity dropped with decreasing barrier thickness. Optical absorption properties were measured at room temperature, and excitonic absorption peaks were clearly observed. The wavelengths of excitonic peaks were in good agreement with a theoretical estimation obtained by using an effective mass approximation including heavy and light hole energy splitting at the γ point.     

Channel deformation analysis for fast reactor fuel assemblies undergoing swelling and thermal bowing

Differential thermal expansion and swelling of fuel pins, hexagonal flow ducts and fuel spin spacers, fuel pin bowing between the spacers due to subchannel temperature differentials, and fuel pin bundle bowing due to the cambered hexagonal wrapper tube were analyzed for sodium-cooled fast reactor fuel assemblies.     

Triethylamine-sensitized photopolymerization of styrene

The photopolymerization of styrene in cyclohexane was accelerated by addition of triethylamine. The determination of the degree of polymerization of the polymer formed showed the acceleration was due to a concurrent sensitized initiation. Further kinetic studies revealed that the sensitization mechanism was analogous to that of the methyl methacrylate case reported earlier, in which an excited monomer and an amine formed an exciplex and gave an initiating radical species. The fluorescence of styrene was quenched effectively by addition of triethylamine in accordance with the kinetic argument.