Naresuan University Journal
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Mass analyzed threshold ionization detected infrared spectroscopy: isomerization activity of the phenol-Ar cluster near the ionization threshold
No full textThe structure of the phenol-argon cluster (PhOH-Ar) in high-n Rydberg states is investigated by the newly developed technique of mass analyzed threshold ionization detected infrared (MATI-IR) spectroscopy. This method selectively measures IR spectra of molecular clusters in very high-n Rydberg states (n > 100) utilized in zero kinetic energy (ZEKE) photoelectron and MATI spectroscopy, whose ionic cores are essentially the same as the corresponding bare cation. The MATI-IR spectrum exhibits only the free OH stretching vibration (V-OH(pi)) when the pi-bound cluster of the neutral ground electronic state (S-0) is resonantly excited via the S-1 origin to Rydberg states converging to its adiabatic ionization energy level, IE0(pi). When Rydberg states converging to vibrationally excited levels of the local p-bound minimum are prepared, in addition to V-OH(pi) also the hydrogen-bonded OH stretching vibration (V-OH(H)) of the H-bonded global minimum is observed in the MATI-IR spectra, even for vibrational excitation of only 14 cm(-1) above IE0(pi). These results show that the pi -> H site switching reaction of the Ar ligand from the aromatic ring to the OH group proceeds only from vibrationally excited states in the p-bound cation core with a small barrier of less than 14 cm(-1) from IE0(pi). On the other hand, directly photoionized PhOH+-Ar shows both V-OH(H) and V-OH(pi) in the IR spectra, even when it is just ionized to IE0(pi). This result implies that the ionization-induced pi -> H site switching occurs without excess energy in the H-bound or pi-bound cations, in contrast to very high-n Rydberg states converging to levels of the pi-bound cation. The different efficiencies of the site switching for the Rydberg ion core and the bare ion and the mechanism for the pi -> H site switching are interpreted by direct ionization from the pi-bound to the H-bound structures in addition to the conventional vertical ionization and transitions to high-n Rydberg states
Estimating microstructural properties of a biomimetic tumour tissue phantom using diffusion-weighted MRI
No full textPhysical phantom experiments allow validation of microstructural models that seek to link the diffusion signal to specific tissue properties, and provide standard measurements for calibration and comparison of scanners in multi-site research. We have previously introduced biomimetic phantoms of axonal structure and here we introduce a novel phantom with microstructural characteristics mimicking tumour cellular structure. We also demonstrate how a model of the diffusion signal may be used to estimate the microstructural properties of the tumour tissue phantom, and provide an initial assessment of the accuracy and precision of these estimates by using independent scanning electron microscope (SEM) measurements and bootstrap simulations
Estimation of flux distribution in metabolic networks accounting for thermodynamic constraints: The effect of equilibrium vs. blocked reactions
No full textThermodynamically constrained stoichiometric-based models have been widely used for the estimation of feasible flux distributions of a metabolic network. The prediction of a zero net flux through a reaction indicates that this reaction is either blocked (the enzyme is absent) or at equilibrium (the enzyme is present but the Gibbs free energy change of the reaction is zero). The estimation of the thermodynamic equilibrium of a reaction requires the exact knowledge of environmental conditions and metabolites' concentrations. This information, however, is not always available. Here, the effect of considering that a reaction is at equilibrium instead of being blocked on the metabolic flux distribution is analysed. The central carbon metabolism of Actinobacillus succinogenes for the production of succinic acid from glycerol has been used as case study, based on results from experiments in 1.8. L batch bioreactors. The impact of changes in ionic strength (I), temperature (T), intracellular pH. c and medium pH. e was also investigated, revealing that only I and T affect the prediction of flux distributions compared with those obtained at standard biological conditions when zero flux reactions are considered either as blocked or at equilibrium. In general, the range of fluxes estimated for the equilibrium case is narrower than that for the blocked case
JNK-dependent downregulation of FoxO1 is required to promote the survival of fibroblast-like synoviocytes in rheumatoid arthritis.
No full textBACKGROUND: Forkhead box O (FoxO) transcription factors integrate environmental signals to modulate cell proliferation and survival, and alterations in FoxO function have been reported in rheumatoid arthritis (RA). OBJECTIVES: To examine the relationship between inflammation and FoxO expression in RA, and to analyse the mechanisms and biological consequences of FoxO regulation in RA fibroblast-like synoviocytes (FLS). METHODS: RNA was isolated from RA patient and healthy donor (HD) peripheral blood and RA synovial tissue. Expression of FoxO1, FoxO3a and FoxO4 was measured by quantitative PCR. FoxO1 DNA binding, expression and mRNA stability in RA FLS were measured by ELISA-based assays, immunoblotting and quantitative PCR. FLS were transduced with adenovirus encoding constitutively active FoxO1 (FoxO1ADA) or transfected with small interfering RNA targeting FoxO1 to examine the effects on cell viability and gene expression. RESULTS: FoxO1 mRNA levels were reduced in RA patient peripheral blood compared with HD blood, and RA synovial tissue FoxO1 expression correlated negatively with disease activity. RA FLS stimulation with interleukin 1β or tumour necrosis factor caused rapid downregulation of FoxO1. This effect was independent of protein kinase B (PKB), but dependent on c-Jun N-terminal kinase (JNK)-mediated acceleration of FoxO1 mRNA degradation. FoxO1ADA overexpression in RA FLS induced apoptosis associated with altered expression of genes regulating cell cycle and survival, including BIM, p27(Kip1) and Bcl-XL. CONCLUSIONS: Our findings identify JNK-dependent modulation of mRNA stability as an important PKB-independent mechanism underlying FoxO1 regulation by cytokines, and suggest that reduced FoxO1 expression is required to promote FLS survival in RA
CFD simulations of a full-scale tidal turbine: comparison of LES and RANS with field data
No full textCFD simulations have been performed for a geometry-resolved full-scale tidal-stream turbine and compared with experimental data from the EMEC test site in the Orkney Isles. The mesh comprises two regions: a rotating part, containing the turbine, and a stationary outer part, including the support tower. A sliding-mesh interface couples the two parts.Initially, Reynolds-averaged Navier-Stokes and large-eddy simulations were performed using an inflow velocity profile representative of the test site but low inflow turbulence, yielding satisfactory mean power coefficients. LES with synthetic turbulence prescribed at inlet was then employed to try to predict realistic load fluctuations. Load fluctuations (power, thrust and blade bending moments) may arise from onset mean velocity shear, influence of the support tower, blade-generated turbulence, approach-flow turbulence and waves. Inflow statistics were prescribed to match the vertical distribution of mean velocity, Reynolds stresses and length scales determined from a channel-flow simulation, with additional factoring of stresses and length scales to match as far as possible those measured on-site. LES simulations with synthetic turbulence at inflow satisfactorily reproduces the spectral distribution of blade bending moments provided that spectra are normalised by variance to reflect the relatively small number of rotations computed
Business strategies of incumbents in the market for electric vehicles: Opportunities and incentives for sustainable innovation.
No full textElemental Volatility During Vacuum Melting of Martian Meteorite NWA 8114
No full textWe show that vacuum melting of basaltic rocks results in severe depletion of U from silicate melts, comparable to Zn, quite contrary to its refractory behavior under reducing conditions
Search for Scalar Charm Quark Pair Production in Collisions at 8??????TeV with the ATLAS Detector
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Comparison between using longitudinal and shear waves in ultrasonic stress measurement to investigate the effect of post-weld heat-treatment on welding residual stresses
No full textFusion welding is a joining process widely used in the industry however, undesired residual stresses are produced once the welding process is completed. Post-weld heat-treatment (PWHT) is extensively employed in order to relieve the welding residual stresses. In this study, effect of PWHT time and temperature on the residual stresses of a ferritic stainless steel is investigated. Residual stress distributions in eight welded specimens were measured by using an ultrasonic method. Ultrasonic stress measurement is a non-destructive method based on acoustoelasticity law, which correlates mechanical stresses with velocity of an ultrasonic wave propagating within the subject material. The ultrasonic wave employed could be longitudinal or shear wave produced by the longitudinal (normal) or transverse (shear) transducers, respectively. Ultrasonic stress measurements based on longitudinal waves use longitudinal critically refracted (LCR) waves in this direction, while shear wave methods use an ultrasonic birefringence phenomenon. The results show that the effect of PWHT can be successfully inferred by both longitudinal and shear wave methods, but the former is found to be more sensitive to stress variation. Furthermore, the distribution of sub-surface residual stresses is found to be more distinguishable when the LCR method is employed