A consideration on thermal stress of steel members reinforced with CFRP

In this study, the amount of thermal stress occurring in a CFRP-reinforced steel member subjected to axial force is evaluated, and a method for easily determining the cross-sectional area requirements for CFRP used for reinforcement is proposed. Furthermore, how the fatigue life of CFRP-reinforced steel members is affected by atmospheric temperature changes is evaluated by using the proposed formula in the case where live loads may be deemed constant and the case where loads from overloaded vehicles act as in the case of a highway bridge

Monitoring Water Reactions during the S-State Cycle of the Photosynthetic Water-Oxidizing Center: Detection of the DOD Bending Vibrations by Means of Fourier Transform Infrared Spectroscopy

Photosynthetic water oxidation takes place in the water-oxidizing center (WOC) of photosystem II (PSII). To clarify the mechanism of water oxidation, detecting water molecules in the WOC and monitoring their reactions at the molecular level are essential. In this study, we have for the first time detected the DOD bending vibrations of functional D2O molecules during the S-state cycle of the WOC by means of Fourier transform infrared (FTIR) difference spectroscopy. Flash-induced FTIR difference spectra upon S-state transitions were measured using the PSII core complexes from Thermosynechococcus elongatus moderately deuterated with D216O and D218O. D216O-minus-D218O double difference spectra at individual S-state transitions exhibited six to eight peaks arising from the D16OD/D18OD bending vibrations in the 1250−1150 cm−1 region. This observation indicates that at least two water molecules, not in any deprotonated forms, participate in the reaction at each S-state transition throughout the cycle. Most of the peaks exhibited clear counter peaks with opposite signs at different transitions, reflecting a series of reactions of water molecules at the catalytic site. In contrast, negative bands at ∼1240 cm−1 in the S2 → S3, S3 → S0, and possibly S0 → S1 transitions, for which no clear counter peaks were found in other transitions, can be interpreted as insertion of substrate water into the WOC from a water cluster in the proteins. The characteristics of the weakly D-bonded OD stretching bands were consistent with the insertion of substrate from internal water molecules in the S2 → S3 and S3 → S0 transitions. The results of this study show that FTIR detection of the DOD bending vibrations is a powerful method for investigating the molecular mechanism of photosynthetic water oxidation as well as other enzymatic reactions involving functional water molecules

Orientations of Carboxylate Groups Coupled to the Mn Cluster in the Photosynthetic Oxygen-Evolving Center As Studied by Polarized ATR-FTIR Spectroscopy

It is essential to clarify the structures and interactions of amino acids surrounding the Mn cluster in photosystem II (PSII) to understand the molecular mechanism of photosynthetic oxygen evolution. In this study, polarized attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was applied for the first time to PSII to investigate the orientation of carboxylate groups coupled to the oxygen-evolving Mn cluster. PSII membranes from spinach were oriented on the surface of a silicon ATR crystal, and flash-induced polarized ATR-FTIR difference spectra for the S1 → S2 transition (S2/S1 spectra) were obtained. The distribution of membrane orientations by mosaic spread was estimated from the semiquinone CO peak in polarized QA−/QA difference spectra recorded using the same oriented sample by buffer exchange. The orientations of carboxylate groups coupled to the Mn cluster were estimated from the dichroic ratios of the symmetric COO− bands in the polarized S2/S1 ATR-FTIR spectra. We found that most of the carboxylate groups perturbed during the S1 → S2 transition, due to direct ligation to the Mn cluster or though a hydrogen bond network, have orientations in a relatively narrow angle range of 34−48° with respect to the membrane normal. Implications of the obtained orientations and the changes upon formation of S2 are discussed on the basis of the information from previous FTIR studies and the X-ray structures. The results in this study show that polarized ATR-FTIR difference spectroscopy is a fruitful method for investigating the orientations and their reaction-induced changes in redox cofactors and coupled amino acid side chains in photosynthetic proteins

Monitoring Proton Release during Photosynthetic Water Oxidation in Photosystem II by Means of Isotope-Edited Infrared Spectroscopy

In photosynthetic water oxidation performed in the water oxidizing center (WOC) of photosystem II (PSII), two water molecules are converted into one oxygen molecule and four protons through a light-driven cycle of intermediates called S states (S0−S4). To understand the molecular mechanism of water oxidation and the chemical nature of substrate intermediates, it is essential to determine the stoichiometry of proton release from substrate water at individual S-state transitions. In this study, we have monitored proton release during water oxidation by means of isotope-edited Fourier transform infrared (FTIR) spectroscopy. FTIR difference spectra upon successive flash illumination were measured using PSII core complexes from a thermophilic cyanobacterium Thermosynechococcus elongatus, which were suspended in a high concentration (200 mM) Mes buffer at pH 6.0. The spectra involved, in addition to protein bands, the bands of the Mes buffer that trapped virtually all protons from the WOC. Mes-only signals were extracted by subtracting the spectra measured in deuterated-Mes (Mes-d12). The flash-number dependence of the intensity increase of the isotope-edited Mes signal showed a clear period-four oscillation. By simulating the oscillation with different assumptions about miss factors, the proton release pattern was estimated to be 0.8−1.0:0.2−0.3:0.9−1.2:1.5−1.6 for the S0→S1→S2→S3→S0 transitions. The effect of H/D exchange on the COOH region of proteins in FTIR difference spectra of the S-state cycle showed that protonation/deprotonation of carboxylic groups contributed little to the observed proton release pattern. Together with the present and previous FTIR results suggesting no involvement of also His and Cys side groups, it was concluded that proton release from substrate water takes place with a 1:0:1:2 stoichiometry, which is perturbed by partial protonation/deprotonation of side groups probably of Arg, Lys, or Tyr located nearby the WOC

LOV-Like Flavin-Cys Adduct Formation by Introducing a Cys Residue in the BLUF Domain of TePixD

LOV-Like Flavin-Cys Adduct Formation by Introducing a Cys Residue in the BLUF Domain of TePix

Flash-Induced FTIR Difference Spectroscopy Shows No Evidence for the Structural Coupling of Bicarbonate to the Oxygen-Evolving Mn Cluster in Photosystem II

Bicarbonate is known to be required for the maximum activity of photosystem II. Although it is well established that bicarbonate is bound to the nonheme iron to regulate the quinone reactions, the effect of bicarbonate on oxygen evolution is still controversial, and its binding site and exact physiological roles remain to be clarified. In this study, the structural coupling of bicarbonate to the oxygen-evolving center (OEC) was studied using Fourier transform infrared (FTIR) difference spectroscopy. Flash-induced FTIR difference spectra during the S-state cycle of OEC were recorded using the PSII core complexes from Thermosynechococcus elongatus in the presence of either unlabeled bicarbonate or 13C-bicarbonate. The H12CO3−-minus-H13CO3− double difference spectra showed prominent bicarbonate bands at the first flash, whereas no appreciable bands were detected at the second to fourth flashes. The bicarbonate bands at the first flash were virtually identical to those from the nonheme iron, which was preoxidized by ferricyanide and photoreduced by a single flash, recorded using Mn-depleted PSII complexes. Using the bicarbonate bands of the nonheme iron as an internal standard, it was concluded that no bicarbonate band arising from OEC exists in the S-state FTIR spectra. This conclusion indicates that bicarbonate is not affected by the structural changes in OEC upon the four S-state transitions. It is thus strongly suggested that bicarbonate is neither a ligand to the Mn cluster nor a cofactor closely coupled to OEC, although the possibility cannot be fully excluded that nonexchangeable bicarbonate exists in OEC as a constituent of the Mn-cluster core. The data also provide strong evidence that bicarbonate does not function as a substrate or a catalytic intermediate. Bicarbonate may play major roles in the photoassembly process of the Mn cluster and in the stabilization of OEC by a rather indirect interaction

Magnetic Properties of Bulk BiCrO₃ Studied with dc and ac Magnetization and Specific Heat

Single-phased powder BiCrO3 sample was prepared at 6 GPa and 1653 K. Its magnetic properties were investigated by dc/ac magnetization, magnetic relaxation, and specific heat measurements. Four anomalies of magnetic origin were found near 40, 75, 109, and 111 K. The long-range antiferromagnetic order with weak ferromagnetism occurs at TN = 109 K. The ac susceptibilities showed that the transition near TN is a two-step transition. Additional frequency-independent broad anomalies were observed on the real part of the ac susceptibilities near 75 K, likely, caused by the change in the magnetic easy axis. The dc magnetic susceptibilities also had anomalies at 75 K, and the isothermal magnetization curves and relaxation curves changed their behavior below 75 K. Below 40 K, frequency-dependent anomalies with very large temperature shifts were observed on both the real and imaginary parts of the ac susceptibilities. The monoclinic-to-orthorhombic structural phase transition near 420 K was investigated by magnetization and differential scanning calorimetry measurements

Supporting information from A Gallium-67/68–Labeled Antibody Fragment for Immuno-SPECT/PET Shows Low Renal Radioactivity Without Loss of Tumor Uptake

Table S1. Biodistribution of radioactivity in mice after injection of 67Ga-NOTA-Fab, 67Ga-NOTA-MI-Fab and 67Ga-NOTA-MVK-Fab. Table S2. Biodistribution of radioactivity in nude mice bearing SY cells after 3 h injection of 67Ga-NOTA-Fab, 67Ga-NOTA-MI-Fab and 67Ga-NOTA-MVK-Fab. Table S3. Stability of 67Ga-labeled Fab fragments in murine serum. Scheme S1. Synthetic procedure for NOTA-MVK-Mal. Scheme S2. Synthetic procedure for NOTA-MVK-Bzo.</p

Structure and Photochemistry of Nitrocobalt(III) Tetraphenylporphyrin with Axial Triphenylphosphine in Toluene Solutions

Thermal and photochemical reactions of nitroaquacobalt(III) tetraphenylporphyrin, (NO2)(H2O)CoIIITPP, have been investigated in toluene solutions containing triphenylphosphine, Pφ3. It is found that Pφ3 thermally abstracts an oxygen atom from the NO2 moiety of (NO2)(H2O)CoIIITPP with a rate constant 0.52 M-1 s-1, resulting in the formation of nitrosylcobalt porphyrin, (NO)CoTPP. The 355-nm laser photolysis of (NO2)(H2O)CoIIITPP at low concentrations of Pφ3 (-4 M) gives CoIITPP and NO2 as intermediates. The recombination reaction of CoIITPP and NO2 initially forms the coordinately unsaturated nitritocobalt(III) tetraphenylporphyrin, (ON−O)CoIIITPP, which reacts with Pφ3 to yield nitro(triphenylphosphine)cobalt(III) tetraphenylporphyrin, (NO2)(Pφ3)CoIIITPP. Subsequently, the substitution reaction of the axial Pφ3 with H2O leads to the regeneration of (NO2)(H2O)CoIIITPP. From the kinetic studies, the substitution reaction is concluded to occur via a coordinately unsaturated nitrocobalt(III) porphyrin, (NO2)CoIIITPP. At higher concentrations of Pφ3 (>4 × 10-3 M), (NO2)(H2O)CoIIITPP reacts with Pφ3 to form (NO2)(Pφ3)CoIIITPP:  the equilibrium constant is obtained as K = 4.3. The X-ray structure analysis of (NO2)(Pφ3)CoIIITPP reveals that the P−Co−NO2 bond angle is 175.0(2)° and the bond length Co−NO2 is 2.000(7) Å. In toluene solutions of (NO2)(H2O)CoIIITPP containing Pφ3 (>4 × 10-3 M), the major light-absorbing species is (NO2)(Pφ3)CoIIITPP, which yields (NO)CoTPP by continuous photolysis. The laser photolysis of (NO2)(Pφ3)CoIIITPP gives CoIITPP, NO2, and Pφ3 as initial products. The NO2 molecule is suggested to be reduced by Pφ3 to yield NO, and the reaction between NO and CoIITPP gives (NO)CoTPP. The quantum yield for the photodecomposition of (NO2)(Pφ3)CoIIITPP is determined as 0.56

Amino acid transport system - A substrate predicts the therapeutic effects of particle radiotherapy

<div><p>L-[methyl-¹¹C]Methionine (¹¹C-Met) is useful for estimating the therapeutic efficacy of particle radiotherapy at early stages of the treatment. Given the short half-life of ¹¹C, the development of longer-lived ¹⁸F- and ¹²³I-labeled probes that afford diagnostic information similar to ¹¹C-Met, are being sought. Tumor uptake of ¹¹C-Met is involved in many cellular functions such as amino acid transport System-L, protein synthesis, and transmethylation. Among these processes, since the energy-dependent intracellular functions involved with ¹¹C-Met are more reflective of the radiotherapeutic effects, we evaluated the activity of the amino acid transport System-A as an another energy-dependent cellular function in order to estimate radiotherapeutic effects. In this study, using a carbon-ion beam as the radiation source, the activity of System-A was evaluated by a specific System-A substrate, alpha-[1-¹⁴C]-methyl-aminoisobutyric acid (¹⁴C-MeAIB). Cellular growth and the accumulation of ¹⁴C-MeAIB or ¹⁴C-Met were evaluated over time <i>in vitro</i> in cultured human salivary gland (HSG) tumor cells (3-Gy) or <i>in vivo</i> in murine xenografts of HSG tumors (6- or 25-Gy) before and after irradiation with the carbon-ion beam. Post 3-Gy irradiation, <i>in vitro</i> accumulation of ¹⁴C-Met and ¹⁴C-MeAIB decreased over a 5-day period. In xenografts of HSG tumors in mice, tumor re-growth was observed <i>in vivo</i> on day-10 after a 6-Gy irradiation dose, but no re-growth was detected after the 25-Gy irradiation dose. Consistent with the growth results, the <i>in vivo</i> tumor accumulation of ¹⁴C-MeAIB did not decrease after the 6-Gy irradiation dose, whereas a significant decrease was observed after the 25-Gy irradiation dose. These results indicate that the activity of energy dependent System-A transporter may reflect the therapeutic efficacy of carbon-ion radiotherapy and suggests that longer half-life radionuclide-labeled probes for System-A may also provide widely available probes to evaluate the effects of particle radiotherapy on tumors at early stage of the treatment.</p></div