Local structure of amorphous tellurium studied by EXAFS

The local structure of an amorphous tellurium (a‐Te) film was investigated by extended X‐ray absorption fine‐structure analysis. The covalent bond length shortens and the Debye–Waller factor of the intra‐chain decreases in a‐Te compared with trigonal Te (t‐Te). The value of the intra‐chain coordination number is close to two, which is the value for t‐Te, and the inter‐chain interaction weakens. These results suggest that the primary chain structure remains intact, but the secondary structure is disrupted. The decrease in the inter‐chain interaction strengthens the intra‐chain interaction.     

A proteome-wide analysis of domain architectures of prokaryotic single-spanning transmembrane proteins

We performed a proteome-wide survey of the domain architectures in single-spanning transmembrane (TM) proteins (single-spannings) from 87 sequenced prokaryotic (Bacterial and Archaean) genomes by assigning Pfam domains to their N-tail and C-tail loops. Out of 14,625 single-spannings, 3,516 sequences have at least one domain assigned, and no domains were assigned to 7,850, with the remaining 3,259 with less reliable assignment. In the domain-assigned sequences, 3116 sequences are with at most two domains, and the other 400 sequences with more than two. The assigned domains distribute over 651 Pfam families, which account for 11.4% of the total Pfam-A families. Among the 651 families are mostly soluble-protein-originated ones, but only 21 families are unique to TM proteins. The occurrence frequency of the individual domain families follows a power-law, that is, 264 families occur only once, 106 just twice, and the families appeared more than 30 times are counted by only 39. It is found that the great majority of the sequences having one or two domains are of the type II topology with the C-tail loop containing domains on it. On the contrary, the N-tail loop of the same type topology seldom carries domains. Importantly, the assigned domains are always found on the tail loops longer than 60 residues, even for the small domains with less than 30 residues. There are still as many as 5,800 sequences without assigned domains in spite of having at least one long tail, on which no less than 1,000 novel domain families are expected most likely to lie concealed unknown yet. We also investigated the domain arrangement preference and the domain family combination patterns in 'singlets' (single-spannings with one assigned domain) and 'doublets' (with two domains).     

Commensurate supersolid of three-dimensional lattice bosons

Using an unbiased quantum Monte?Carlo method, we obtain convincing evidence of the existence of a checkerboard supersolid at a commensurate filling factor 1/2 (a commensurate supersolid) in the soft-core Bose-Hubbard model with nearest-neighbor repulsions on a cubic lattice. In conventional cases, supersolids are realized at incommensurate filling factors by a doped-defect-condensation mechanism, where particles (holes) doped into a perfect crystal act as interstitials (vacancies) and delocalize in the crystal order. However, in the model, a supersolid state is stabilized even at the commensurate filling factor 1/2 without doping. By performing grand canonical simulations, we obtain a ground-state phase diagram that suggests the existence of a supersolid at a commensurate filling. To obtain direct evidence of the commensurate supersolid, we next perform simulations in canonical ensembles at a particle density ρ=1/2 and exclude the possibility of phase separation. From the obtained snapshots, we discuss its microscopic structure and observe that interstitial-vacancy pairs are unbound in the crystal order.     

Synthesis of thiol-capped gold nanoparticle with a flow system using organosilane as a reducing agent

Synthesis of thiol-capped gold nanoparticle is carried out by mixing of a THF solution of HAuCl₄·4H₂O and ⁿC₁₂H₂₅SH with a THF solution of triethylsilane in a flow system that consists of polytetrafluoroethylene tubing. The effect of residence time and reaction temperature on the particle size is examined.     

Worst-Case Violation of Sampled Convex Programs for Optimization with Uncertainty

A deterministic approach called robust optimization has been recently proposed to deal with optimization problems including inexact data, i.e., uncertainty. The basic idea of robust optimization is to seek a solution that is guaranteed to perform well in terms of feasibility and near-optimality for all possible realizations of the uncertain input data. To solve robust optimization problems, Calafiore and Campi have proposed a randomized approach based on sampling of constraints, where the number of samples is determined so that only a small portion of the original constraints is violated by the randomized solution. Our main concern is not only the probability of violation, but also the degree of violation, i.e., the worst-case violation. We derive an upper bound of the worst-case violation for the sampled convex programs and consider the relation between the probability of violation and the worst-case violation. The probability of violation and the degree of violation are simultaneously bounded by a prescribed value when the number of random samples is large enough. In addition, a confidence interval of the optimal value is obtained when the objective function includes uncertainty. Our method is applicable to not only a bounded uncertainty set but also an unbounded one. Hence, the scope of our method includes random sampling following an unbounded distribution such as the normal distribution.     

Simple and rapid HPLC-UV method using an ultrafine particle octadecylsilane for determination of residual fentanyl in applied Durotep MT transdermal matrix patches and its clinical application

A few complicated and time-consuming methods are available for the determination of residual fentanyl in Durotep MT transdermal patches, however, their application to clinical settings is limited. The aim of this study was to develop a simple and rapid HPLC-UV method using an ultrafine particle octadecylsilane (ODS) for the determination of residual fentanyl in applied Durotep MT transdermal matrix patches. Patch extraction involved sonicating a shredded Durotep MT patch in acetonitrile for 15 min. Fentanyl separation was completed within 2 min using a 2.3-μm particle ODS column (50 × 4.6 mm i.d.) at a flow rate of 1.5 mL/min. No peaks interfering with fentanyl (1.27 min) and papaverine (0.89 min) as an internal standard were observed. The calibration curve for fentanyl was linear over the range of 0.015-9.0 mg as a Durotep MT patch. The intra- and inter-assay precisions and accuracies of each patch were within 5.3% and 103.9-110.5% and within 8.2% and 97.1-104.3%, respectively. The validated method was applied to determine residual fentanyl in Durotep MT patches used in 35 cancer patients. Although the plasma fentanyl concentration was significantly correlated with its measured absorption rate, the measured absorption rate normalized fentanyl concentration showed a large inter-individual variation. The validated simple and rapid HPLC-UV method established in the present study is helpful for evaluating the absorption rate of fentanyl in patients receiving Durotep MT patches.     

Absolute and convective instabilities of two-dimensional bluff body wakes in ground effect

Local and global instabilities are investigated of wakes of general two-dimensional bluff bodies placed near and parallel to a plane boundary or ground. A spatio-temporal linear stability analysis is first applied to a four-parameter family of local wake profiles to investigate the fundamental local stability characteristics of the wake in ground effect. The analysis shows significant dependencies of the stability characteristics of the wake on the distance from the wake centreline to the ground (normalised by the wake width), and also on the velocity ratio of the near- and far-ground sides of the wake. The analysis is then compared with earlier experiments on a circular cylinder to examine, according to the transition scenario of the steep global modes, the streamwise variation of the local stability characteristics of the wake in ground effect. The comparison indicates that the near wake region of the cylinder changes from being absolutely unstable to being convectively unstable when the cylinder comes down into the near-ground range in which the von Kármán-type vortex shedding from the cylinder is suppressed, being qualitatively consistent with the transition scenario for general wake-type flows. A possible explanation is also given for the counter-intuitive relation between the thickness of the boundary layer on the ground and the critical gap distance for the cessation of the von Kármán-type vortex shedding in ground effect.     

DESIGN AND PHOTOFUNCTIONS OF DENDRIMER-ENCAPSULATED POLY(PHENYLENEETHYNYLENE)S

A series of dendrimer-encapsulated poly(phenyleneethynylene)s 4～6 were Synthesize d. The light-harvesting antenna functions of dendrimer frameworks together with the blue-light emitting activities of 4～6 were highlighted.     

Luminescence of GaN single crystals prepared by heating a Ga melt in Na–N2 atmosphere

Colorless transparent prismatic crystals (0.5‐2.0 mm long) and hopper crystals (1.0‐2.5 mm long) of GaN were prepared by heating a Ga melt at 800°C in Na vapor under N₂ pressures of 7.0 MPa for 300 h. The photoluminescence (PL) spectrum of a prismatic crystal at 4 K showed the emission peaks of neutral donor‐bound exciton (D⁰‐X) and free exciton (X_A) at 3.472 eV and 3.478 eV, respectively, in the near band edge region. The full‐width at half‐maximum (FWHM) of (D⁰‐X) peak was 1.9 meV. The emission peaks of a donor–acceptor pair transition (D⁰‐A⁰) and its phonon replicas were observed in a lower energy range (2.9‐3.3 eV). The emission peaks of the D⁰‐A⁰ and phonon replicas were also observed in the cathodoluminescence (CL) spectrum at 20 K. The (D⁰‐X) PL peak of a hopper crystal at 4 K was at 3.474 eV (2.1 meV higher), having a FWHM of 6.1 meV which was over 3 times larger than that of the prismatic crystal. A strong broad band with a maximum intensity around 1.96 eV was observed for the hopper crystals in the CL spectrum at room temperature. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation of GaN crystals by heating a Li3N‐added Ga melt in Na vapor and their photoluminescence

GaN crystals were prepared by heating a Ga melt with 1 at% Li₃N against Ga at 750 °C in Na vapor under N₂ pressures of 0.4–1.0 MPa. The GaN crystals grown at 1.0 MPa of N₂ were colorless and transparent prismatic, having a size of approximately 0.7 mm in length. A secondary ion mass spectrometry (SIMS) showed the contaminant of lithium in the obtained crystals. A large broad yellow band emission peak of 2.28 eV was observed at room temperature in the photoluminescence spectrum in addition to the near band emission peak of GaN at 3.39 eV and a small broad satellite emission at 3.24 eV. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)