A Model of the Relationship Between Psychosocial Variables and Diurnal Cortisol Rhythm Under Chronic Stress by Using Structural Equations

By using structural equations, we investigated the effect of chronic stress on salivary cortisol rhythm and proposed a causal model of chronic stress by using psychosocial and physiological data. First, 111 healthy workers (48 males, 63 females) completed questionnaires on chronic stress and lifestyle habits. Then, they provided saliva samples and answered questionnaires that were prepared to assess their psychological states 5 times (on waking up and at 10:00, 11:40, 14:00, and 16:00) on workdays. Structural equation modeling (SEM) revealed that chronic stress and longer commuting time resulted in sleep irregularities and this disrupted the cortisol circadian rhythm. This suggests that chronic stress disrupts the cortisol circadian rhythm even in healthy individuals, and sleep regularity mediates the effect of chronic stress on the cortisol rhythm.

     

Development and applications of a compact hybrid tabletop terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser for x-ray lasing and harmonic generation

A hybrid tabletop (2 m x 3 m) terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser (1054 nm, 475 fs, 500 mJ, 9 x 10(17) W cm(-2)) has been developed for laser-matter experiments. An overall gain factor of 10(10) was achieved for the laser. The results of laser applications in the studies of soft-x-ray Ni-like Mo 18.9-nm lasing and of harmonic generation from solid surfaces are presented.     

Quantum-Mechanical Properties of Protons in Solid Molecular Hydrogen at Megabar Pressures

Quantum distributions of protons in three high-pressure phases of solid molecular hydrogen are investigated by the first-principles path integral molecular dynamics (FP-PIMD) method, in which interatomic forces are calculated precisely based on the density functional theory. The distributions have entirely different symmetries from those predicted by conventional simulation with classical treatment of protons. Especially in phase II, we found that molecular rotation is hindered by quantum fluctuation of protons, having a strong resemblance to a quantum distribution of impurity muonium in crystalline silicon. The mechanism of this “quantum localization” is clarified by a detailed study of the potential energy surface for the molecular rotation.     

Characteristics of a Nonstoichiometric Gd3+δ(Al,Ga)5−δO12:Ce Garnet Scintillator

We have developed a new nonstoichiometric Gd_3+δ(Al,Ga)_5−δO₁₂:Ce garnet scintillator for an X-ray CT scanner. For commercially used scintillators, reproducible luminescence properties are of great importance. We have found that the afterglow properties of the garnet change drastically in the vicinity of the stoichiometric compositions. The most suitable properties are obtained at slightly excess (Gd,Ce) compositions from the stoichiometry. In order to investigate the afterglow properties, crystallography arrangements, phase equilibrium relationship between crystal phases, and luminescence characteristics of host material doped with different valence ions have been examined. The luminescence properties are explained by isoelectronic traps based on the difference in the electronegativity of the dopant and host ions, which would act as electron trap centers and hole trap centers within the band gap.     

Hydrogen-bond-assisted isotactic-specific radical polymerization of N-isopropylacrylamide with pyridine N-oxide

Radical polymerization of N-isopropylacrylamide (NIPAAm) in CHCl₃ at low temperatures in the presence of pyridine N-oxide (PNO) was investigated. An isotactic poly(NIPAAm) with meso diad content of 61% was successfully prepared at −60 °C in the presence of a two-fold amount of PNO. Thermodynamic analysis suggested that the isotactic-specificity was entropically induced, probably due to conformational fixation near the propagating chain-end through coordination by PNO.     

Hyperbranched Acrylate Copolymer via Initiator‐Fragment Incorporation Radical Copolymerization of Divinylbenzene and Ethyl Acrylate: Synthesis,Characterization, Hydrolysis,Dye‐Solubilization,Ag Particle‐Stabilization,and Porous Film Formation

Summary: Soluble hyperbranched acrylate copolymers were prepared by the copolymerization of divinylbenzene (0.10 mol · L^?1) and ethyl acrylate (0.50 mol · L^?1) using dimethyl 2,2′‐azoisobutyrate of high concentrations (0.30–0.50 mol · L^?1) as initiator at 70 and 80 °C in benzene. The copolymer formed at 80 °C for 1 h showed the weight‐average molecular weight of 2.5 × 10⁵, the small radius of gyration of 10 nm, the low second virial coefficient of 5.7 × l0^?7 mL · g^?2 as shown by the MALLS measurements at 25 °C in tetrahydrofuran, and also the very low intrinsic viscosity of 0.10 dL · g^?1 at 30 °C in benzene. The hyperbranched copolymer exhibited an upper critical solution temperature (35 °C on cooling) in an acetone‐water (60:11 v/v). The copolymer showed an ability to encapsulate and transfer Rhodamine 6G as a dye probe and could stabilize Ag nanoparticles. The porous film was prepared by simply casting an acetone solution of the hyperbranched copolymer on a cover glass. The copolymer molecules radially arranged on the surface layer of the spherical pores as observed by the polarized optical microscope. The hyperbranched acrylate copolymer was hydrolyzed by KOH to yield poly(carboxylic acid).

Optical microscope image (crossed polarizers) of a porous film from copolymer solution in acetone.     

Contact between catalyst and carbon in the tin- and lead- catalyzed gasification of carbon with carbon dioxide

The wettability and distribution of tin and lead metals on a phenol-folmaldehyde resin char were investigated by means of contact angle measurement and microscopic analysis. The wettability on the pelletized char was not so significant. However, stannic oxide was found to be distributed around a tin catalyst particle. This can be considered a result of the vapor phase transport of stannous oxide and its oxidation by CO₂. Stannous oxide was formed through a red-ox type catalysis cycle. On the other hand, in the case of lead-catalyzed gasification, the mobile species was the lead metal itself. Thus, the high catalytic activity of tin and lead metals was appropriately ascribed to an intimate contact between the catalyst and the carbon substrate caused by the vapor phase transportation of stannous oxide and lead metal.     

A simple facility to measure the scalar neutron spectrum in an assembly

An inexpensive, simple and safe facility was constructed to measure the neutron spectrum in an assembly, by setting a neutron source outside the assembly. A normalization technique for the neutron spectrum and error analyses are mentioned. The error of the calculated spectrometer efficiency is cancelled at the final spectrum normalization. The error caused by the present method is within acceptable levels.