Role of coherent nuclear motion in the ultrafast intersystem crossing of ruthenium complexes.

Ultrafast intersystem crossing (ISC) in transition metal complexes leads to a long-lived active state with a high yield, which leads to efficient light energy conversion. The detailed mechanism of ISC may lead to a rational molecular design of superior transition metal complexes. Coherent nuclear wave packets observed in femtosecond time-resolved spectroscopies provide important information on the excited-state dynamics. In particular, analyzing the nuclear wave packets in both the reactant and the product may unveil the molecular dynamics of an ultrafast reaction. In this study, experimental evidence proving the reaction coordinates of the ultrafast ISC of ruthenium(ii) complexes is presented using coherent vibrational spectroscopy with a quantum chemical simulation of coherent vibrational motion. We observed vibrational modes strongly coupled to the ISC, whose vibrational coherences undergo remarkable attenuation after the ISC. The coupled modes contain metal-ligand stretching or symmetry breaking components, and the faster ISC rates of lower-symmetry ruthenium(ii) complexes support the significance of the latter.

Engineering Reaction Kinetics by Tailoring the Metal Tips of Metal-Semiconductor Nanodumbbells.

Semiconductor-metal hybrid nanostructures are one of the best model catalysts for understanding photocatalytic hydrogen generation. To investigate the optimal structure of metal cocatalysts, metal-CdSe-metal nanodumbbells were synthesized with three distinct sets of metal tips, Pt-CdSe-Pt, Au-CdSe-Au, and Au-CdSe-Pt. Photoelectrochemical responses and transient absorption spectra showed that the competition between the charge recombination at the metal-CdSe interface and the water reduction on the metal surface is a detrimental factor for the apparent hydrogen evolution rate. For instance, a large recombination rate (krec) at the Pt-CdSe interface limits the quantum yield of hydrogen generation despite a superior water reduction rate (kWR) on the Pt surface. To suppress the recombination process, Pt was selectively deposited onto the Au tips of Au-CdSe-Au nanodumbbells in which the krec was diminished at the Au-CdSe interface, and the large kWR was maintained on the Pt surface. As a result, the optimal structure of the Pt-coated Au-CdSe-Au nanodumbbells reached a quantum yield of 4.84%. These findings successfully demonstrate that the rational design of a metal cocatalyst and metal-semiconductor interface can additionally enhance the catalytic performance of the photochemical hydrogen generation reactions.

Improved spectral resolution of the femtosecond stimulated Raman spectroscopy achieved by the use of the 2nd-order diffraction method.

Prolongation of the picosecond Raman pump laser pulse in the femtosecond stimulated Raman spectroscopy (FSRS) setup is essential for achieving the high spectral resolution of the time-resolved vibrational Raman spectra. In this work, the 2nd-order diffraction has been firstly employed in the double-pass grating filter technique for realizing the FSRS setup with the sub-5 cm-1 spectral resolution. It has been experimentally demonstrated that our new FSRS setup gives rise to a highly-resolved Raman spectrum of the excited trans-stilbene, which is much improved from those reported in the literatures. The spectral resolution of the present FSRS system has been estimated to be the lowest value ever reported to date, giving Δν = 2.5 cm-1.

Femtosecond-Resolved Excited State Relaxation Dynamics of Copper (II) Tetraphenylporphyrin (CuTPP) After Soret Band Excitation.

Excited state relaxation dynamics of Copper (II) tetraphenylporphyrin (CuTPP) after Soret band excitation have been investigated in various solvents by femtosecond broadband transient absorption spectroscopy. Significant role of charge transfer state has been confirmed from fast relaxation of triplet CuTPP in pyridine, giving τ ~ 26.5 ps. In piperidine, the transient measured at 480 nm shows biexponential behavior with distinct time constants of 300 fs and 27.4 ps. The fast component with τ ~ 300 fs is attributed to relaxation of the CuTPP-piperidine adduct populated in the ground state, giving the intrinsic relaxation rate of the CuTPP exciplex for the first time. For CuTPP in O-coordinating solvents of 1,4-dioxane and tetrahydrofuran (THF), a completely new relaxation channel via the 2[dz2, dx2-y2] state is opened. As the exciplex formation is diffusion controlled, triplet CuTPP lifetimes in pure solvents employed here are all measured to be more or less same to give ~30 ps, whereas the 2[dz2, dx2-y2] exciplex formed by the ligation with O-coordinating solvents is found to relax much slowly to the ground state, giving lifetimes of ~360 and ~270 ps in 1,4-dioxane and THF, respectively.

Effect of myocardial protection of intracoronary adenosine and nicorandil injection in patients undergoing non-urgent percutaneous coronary intervention: a randomized controlled trial.

BACKGROUND: Several studies have demonstrated that adenosine and nicorandil protect the myocardium against angioplasty-related myocardial injury. We conducted a prospective study to investigate the myocardial protective effects of combination therapy with intracoronary adenosine and nicorandil. METHODS: We enrolled 213 consecutive patients with stable or unstable angina who were scheduled for non-urgent PCI for de-novo coronary lesions. Patients were randomized into group I (control saline, n=55), group II (adenosine 50 µg, n=54), group III (nicorandil 4 mg, n=54), or group IV (adenosine-nicorandil combination, n=50). Serial assessments of CK-MB were used to assess myocardial necrosis before and after PCI. The primary endpoint was the incidence of myocardial necrosis (elevation of CK-MB), and the secondary endpoints were the changes in serum CK-MB and cTnI levels and the incidence of post-procedural myocardial infarction (MI). RESULTS: No significant differences were observed among the four groups with regard to baseline or angiographic characteristics. No major adverse events related to adenosine and nicorandil were observed. There were no significant differences in the incidence of post-procedural myocardial necrosis among the four groups (10.9, 14.8, 14.8, and 14.0%, respectively, p=0.9). There were no significant differences in the incidence of post-procedural MI among groups (p=0.6). In multivariate regression analysis, multivessel stenting, median stent length, and the presence of a compromised side branch were independent predictors of myonecrosis. CONCLUSIONS: Pretreatment with intracoronary adenosine, nicorandil, or the combination of the two drugs did not reduce the incidences of myocardial necrosis or MI after non-urgent PCI in patients with low-risk angina pectoris.

Changes in Adenosine Deaminase Activity in Patients with Type 2 Diabetes Mellitus and Effect of DPP-4 Inhibitor Treatment on ADA Activity.

BACKGROUND: Dipeptidyl peptidase 4 (DPP-4, also known as CD26) binds with adenosine deaminase (ADA) to activate T lymphocytes. Here, we investigated whether ADA activity is specifically affected by treatment with DPP-4 inhibitor (DPP4I) compared with other anti-diabetic agents. METHODS: Fasting ADA activity, in addition to various metabolic and biochemical parameters, were measured in 262 type 2 diabetes mellitus (T2DM) patients taking various anti-diabetic agents and in 46 non-diabetic control subjects. RESULTS: ADA activity was increased in T2DM patients compared with that in non-diabetic control subjects (mean±standard error, 23.1±0.6 U/L vs. 18.6±0.8 U/L; P<0.05). ADA activity was correlated with fasting plasma glucose (r=0.258, P<0.05), HbA1c (r=0.208, P<0.05), aspartate aminotransferase (r=0.325, P<0.05), and alanine aminotransferase (r=0.248, P<0.05). Compared with the well-controlled T2DM patients (HbA1c<7%), the poorly controlled group (HbA1c>9%) showed significantly increased ADA activity (21.1±0.8 U/L vs. 25.4±1.6 U/L; P<0.05). The effect of DPP4I on ADA activity in T2DM patients did not differ from those of other oral anti-diabetic agents or insulin. T2DM patients on metformin monotherapy showed a lower ADA activity (20.9±1.0 U/L vs. 28.1±2.8 U/L; P<0.05) compared with that of those on sulfonylurea monotherapy. CONCLUSION: Our results show that ADA activity is increased in T2DM patients compared to that in non-diabetic patients, is positively correlated with blood glucose level, and that DPP4I has no additional specific effect on ADA activity, except for a glycemic control- or HbA1c-dependent effect.

Clinical Characteristics of Type 2 Diabetes Patients according to Family History of Diabetes.

BACKGROUND: Type 2 diabetes mellitus (T2DM) has a strong genetic component, and its prevalence is notably increased in the family members of T2DM patients. However, there are few studies about the family history of T2DM. We carried out this study to assess the influences of family history on clinical characteristics in T2DM patients. METHODS: This is a cross-sectional study involving 651 T2DM patients. Patient history and physical examination were performed and fasting blood was taken. If any first degree relative was diabetic, a family history of diabetes was considered to exist. RESULTS: Among the total 621 patients, 38.4% had a family history of diabetes. Patients with a family history had a younger age, higher weight, younger age at diagnosis and higher triglyceride level than did those without a family history. Dyslipidemia medication and metabolic syndrome were more prevalent in familial diabetes. Sex, blood pressure, previous treatment for diabetes, HbA1c, C-peptide, total cholesterol, high density lipoprotein cholesterol, and low density lipoprotein cholesterol were not different between familial and non-familial diabetes. Upon multiple linear regression analysis, the family history of diabetes remained significantly associated with serum triglyceride level. CONCLUSION: In T2DM patients with a family history of diabetes, the disease tended to develop earlier. Metabolic syndrome and cardiovascular risk factors are more prevalent in familial T2DM than they were in non-familial T2DM. These results support the necessity of earlier screening for diabetes in family members of T2DM patients and more active prevention against cardiovascular disease in T2DM patients with a family history.