Study of the ‘Raman spectroscopic signature of life’ in mitochondria isolated from budding yeast

The ‘Raman spectroscopic signature of life’ is a Raman band at 1602 cm⁻¹ that sharply reflects the metabolic activity of cell mitochondria. Here we report the study of thissignature in isolated yeast mitochondria. The existence and behaviour of the 1602 cm⁻¹ band in isolated mitochondria have been confirmed to be the same as in living yeast cells: the intensity of the band decreases with timewhen a respiration inhibitor, sodium azide, is added. The present study shows the significance of isolated mitochondria in elucidating the origin of this still unassigned Raman band. Copyright © 2009 John Wiley & Sons, Ltd.     

Bond strength-coordination number fluctuations and the fragility of some ion-conducting oxide and chalcogenide glass-forming liquids

The concept of fragility has been used widely to characterize the temperature dependence of the viscosity of glass-forming liquids. According to a model proposed by one of the authors, the fragility is determined by the relaxation of structural units that form the melt and is described in terms of the bond strength, coordination number, and their fluctuations. In the present contribution, the model is applied to investigate the temperature dependence of the viscosity of some ion-conducting oxide and chalcogenide glass-forming liquids. From the analysis of the model, physical quantities such as the number of bonds that must be broken to observe the viscous flow are obtained. The analysis suggests also that good ionic conductors have an intermediate value of fragility.     

Kinetic Simulations of Reversible Chain Transfer Catalyzed Polymerization (RTCP): Guidelines to Optimum Molecular Weight Control

Kinetic simulations of reversible chain transfer catalyzed polymerization (RTCP) were performed using the program package Predici. Mimicking the RTCP of styrene in bulk at 80 °C, the full molecular weight distributions, the polydispersities of resulting polymer and the time evolutions of monomer conversion and participating species were simulated. The influence of the kinetic coefficients governing the RTCP equilibrium – specifically, the rate coefficients of activation, k_a, and deactivation, k_da – on the controlled polymerization behavior was probed in detail by varying their respective simulation input values over five orders of magnitude. It was found that optimum results for molecular weight control are obtained for K = k_a/k_da in the range 1 to 10 and with k_a and k_da being of the order of 10⁶ L · mol⁻¹ · s⁻¹ or above. The influence of degenerative chain transfer on the process was found to be significant only in poorly controlled systems, but is small in well‐controlled RTCP. Based on the finding that the catalyst is depleting during the polymerization due to cross‐termination, guidelines for obtaining high molecular weight material via repeated addition of catalyst were developed.

     

Relationship between Helmholtz-resonance absorption and panel-type absorption in finite flexible microperforated-panel absorbers

Microperforated panels (MPPs) can provide wide-band absorption without fibrous and porous materials and are recognized as next-generation absorption materials. Although the fundamental absorbing mechanism of an MPP absorber is Helmholtz-resonance absorption, sound-induced vibration of an MPP itself can affects the absorption characteristics. There have been some studies considering the effects of the sound-induced vibration and there even is a proposal to widen the absorption bandwidth by positively utilizing the vibration of an MPP itself. On the other hand, in a previous study, the relationship between MPP absorbers and panel-type absorbers was investigated with infinite theory. However, the relationship between Helmholtz-resonance absorption and panel-type absorption in finite flexible MPP absorbers has not been clarified. Herein, from the viewpoint of an absorption-characteristics transition with the perforation ratio, the relationship between Helmholtz-resonance absorption and panel-type absorption including the effects of eigen-mode vibrations of the panel is theoretically and experimentally investigated. The analytical model considers a finite flexible MPP supported in a circular duct, and the predicted data for the absorption coefficient under normal incidence is validated by an experiment using an acoustic tube. From this investigation, it is found that panel-type absorption due to eigen-mode vibrations of the panel occurs independently from Helmholtz-resonance absorption, while panel-type absorption due to a mass-spring resonance of a panel and a back cavity has a trade-off relationship with Helmholtz-resonance absorption with respect to the perforation ratio.     

Influence of laser power on the orientation and microstructure of CeO2 films deposited on Hastelloy C276 tapes by laser chemical vapor deposition

CeO₂ films were prepared on LaMnO₃/MgO/Gd₂Zr₂O₇ multi-coated Hastelloy C276 tapes by laser chemical vapor deposition at different laser power (P_L) from 46 to 101 W. Epitaxial (1 0 0) CeO₂ films were prepared at P_L = 46-93 W (deposition temperature, T_dep = 705-792 K). Epitaxial CeO₂ films had rectangular-shaped grains at P_L = 46-77 W (T_dep = 705-754 K), while square-shaped grains were obtained at P_L = 85-93 W (T_dep = 769-792 K). CeO₂ films showed a columnar microstructure. Epitaxial (1 0 0) CeO₂ films with rectangular grains exhibited full width at half maximum of ω-scan on (2 0 0) reflection and ?-scan on (2 2 0) reflection of 3.4-3.2° and 6.0-7.2°, respectively. The deposition rate of the epitaxial (1 0 0) CeO₂ films had a maximum of 4.6 μm h⁻¹ at P_L = 77 W (T_dep = 754 K).     

Synthesis and spectral properties of polymethine-cyanine dye-nitroxide radical hybrid compounds for use as fluorescence probes to monitor reducing species and radicals

Various hybrid compounds comprised of two types of nitroxide radicals and either a pentamethine (Cy5) or trimethine cyanine (Cy3) were synthesized. The nitroxide radicals were linked either via an ester-bond to one or two N-alkyl carboxyl-terminated groups of Cy5, or via two amido-bonds (aminocarbonyl or carbonylamino group) to the 5-position of the indolenine moieties of Cy5 and Cy3. Changes in fluorescence and ESR intensities of the hybrid compounds were measured before and after addition of Na ascorbate in PBS (pH 7.0) to reduce the radicals. Among the hybrid compounds synthesized, those that linked the nitroxide radicals via an aminocarbonyl residue at the 5-position of the indolenine moieties on Cy5 and Cy3 exhibited a 1.8- and 5.1-fold increase in fluorescence intensity with the reduction of the nitroxide segment by the addition of Na ascorbate, respectively. In contrast, fluorescence intensity was not enhanced in the other hybrid compounds. Thus, the hybrid compounds which exhibited an increase in fluorescent intensity with radical reduction can be used in the quantitative measurement of reducing species such as Fe(2+) and ascorbic acid, and hydroxyl radicals. Because these hybrid compounds have the advantage of fluorescing at longer wavelengths-661 (Cy5) or 568 (Cy3)nm, respectively, they can be used to measure radical-reducing species or radicals either in solution or in vivo.     

Thermal decomposition behaviour of cobalt(II)-picolyl-terminated poly(dimethylsiloxane)

Thermal, chemical and rheological properties of ultraviolet aged asphalt binder were characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) and dynamic shear rheometer (DSR), respectively. Asphalt binder samples were made with different film thickness (50, 100, 200 and 500 μm) and suffered different ageing time (0, 48, 96 and 144 h), at a certain UV radiant intensity of 20 w m^–2 in a self-made accelerated ageing oven. The results indicate that the UV light ageing would lead to the improvement of thermal behavior and the growth of the glass transition temperature of asphalt binder. This type of ageing can be also reflected from the FTIR spectra in terms of the characteristic peaks of the carbonyl groups and sulphoxides. The UV light ageing can change some rheological parameters of asphalt binder, such as complex modulus and phase angle. The ageing degrees of asphalt binder by this type of ageing test are mainly related to the ageing time and film thickness of the sample.     

Curvilinear and surficial electron holes in atoms and molecules

The antisymmetric property of many-electron wave functions results in the well-known Fermi hole, which implies that any two electrons with the same spin cannot be at the same point in space. We here point out that for certain types of antisymmetric wave functions, there exist curvilinear and surficial electron holes which imply that two electrons cannot be on particular curves and surfaces in space.     

Study of neonatal exposure to androgenic endocrine disruptors, testosterone and dihydrotestosterone by normal-phase HPLC

Neonatal exposure to androgen induces developmental abnormalities in the male reproductive system. To investigate whether neonatal exposure affects spermatogenesis in juvenile and pubertal testis, Sprague-Dawley rat pups were given androgen or various androgenic endocrine disruptors by a single injection on the day of birth at concentrations ranging between 4 mm to 200 mm, and sacrificed on day 21 (juvenile) or 50 (puberty). The testes were weighed and examined histologically at each stage. Further, the metabolites of steroidogenesis were analyzed using normal-phase high-performance liquid chromatography. Neonatal exposure significantly reduced testis weights and steroidogenesis of juveniles. Neonatal exposure to testosterone and dihydrotestosterone still suppressed pubertal steroidogenesis, although testis weight was completely restored during puberty.