Double Imaging Photoelectron Photoion Coincidence Sheds New Light on the Dissociation of State-Selected CH₃F⁺ Ions

The vacuum ultraviolet (VUV) photoionization and dissociative photoionization of methyl fluoride (CH₃F) in the 12.2–19.8 eV energy range were investigated by using synchrotron radiation coupled to a double imaging photoelectron photoion coincidence (i²PEPICO) spectrometer. The production of several fragment ions including CH₂F⁺, CHF⁺, CH₃⁺, and CH₂⁺ as a function of state and internal energy of CH₃F⁺ ions was identified and analyzed, with their individual appearance energies measured through threshold photoelectron spectroscopy. Dynamical information was inferred from electron and ion kinetic energy correlation diagrams measured at chosen fixed photon energies. The detailed mechanisms governing the dissociation of state-selected CH₃F⁺ ions prepared in the X²E, A²A₁, and B²E low-lying electronic states as well as outside the Franck–Condon region have been inferred based on the present experimental results and existing theoretical calculations. Both the CH₂F⁺ and CH₃⁺ primary fragment ions have three different channels of production from different electronic states of CH₃F⁺. The spin–orbit splitting states of the F fragment, ²P_3/2 and ²P_1/2, in the CH₃⁺ + F dissociation channels were assigned and adiabatically correlate to the X²E ground state and the A²A₁ electronic state, respectively, with the aid of previous theoretical results. The CH₃F⁺ ions in the high energy part of the X²E ground state are unstable and statistically dissociate to the CH₂F⁺(1¹A₁) and H­(²S) fragments along the potential energy curve of the X²E state. The A²A₁ electronic state is a repulsive state and exclusively dissociates to the CH₃⁺(1¹A₁′) and F­(²P_1/2) fragments. In addition, the CH₂F⁺, CHF⁺, CH₃⁺, and CH₂⁺ fragment ions are also produced in the B²E state and in the Franck–Condon gap by indirect processes, such as internal conversion or dissociative autoionization

Quenching of the Electrochemiluminescence of Tris(2,2′-bipyridine)ruthenium(II)/Tri‑<i>n</i>‑propylamine by Pristine Carbon Nanotube and Its Application to Quantitative Detection of DNA

In this study, we describe the quenching of electrochemiluminescence (ECL) of tris­(2,2′-bipyridine)-ruthenium­(II)­(Ru­(bpy)₃²⁺)/tri-<i>n</i>-propylamine­(TPA) at pristine multiwall carbon nanotube (MWNT) modified glassy carbon (GC) electrode. Even though the faradic current of the Ru­(bpy)₃²⁺/TPA system and the oxidation of TPA obtained at pristine MWNT-modified GC electrode is enhanced compared with those at the bare GC electrode, the intensity of ECL produced at MWNT electrode is smaller than that at GC electrode. For testing the possible reason of quenching, a comparison of ECL behavior of Ru­(bpy)₃²⁺/TPA at pristine MWNT and acid-treated, heat-treated, and polyethylene glycol (PEG)-wrapped MWNT-modified GC electrode is studied. The results demonstrate that the oxygen-containing groups at the surface of MWNT and the intrinsic electron properties of MWNT are considered to be the major reason for the suppression of ECL. The comparison also demonstrates that this quenching is related to the distance between MWNT and Ru­(bpy)₃²⁺/TPA. Utilizing this essential quenching mechanism, a new signal-on DNA hybridization assay is proposed on the basis of the MWNT modified electrode, where single-stranded DNA (ssDNA) labeled with Ru­(bpy)₃²⁺ derivatives probe (Ru-ssDNA) at the distal end is covalently attached onto the MWNT electrode. ECL signal is quenched where Ru-ssDNA is self-organized on the surface of MWNT electrode; however, the quenched ECL signal returns in case of the presence of complementary ssDNA. The developed approach for sequence-specific DNA detection has good selectivity, sensitivity, and signal-to-background ratio. Therefore, the quenching of the ECL of Ru­(bpy)₃²⁺/TPA system by the pristine MWNT can be an excellent platform for nucleic acid studies and molecular sensing

Hazard ratios for cause-specific mortality according joint categories of body mass index.

<p>Hazard ratios (95% CI) indicates the risk of body mass index (BMI) <18 kg/m² compared with the risk in all the other BMI groups. The adjusted model includes sex and age. The fully adjusted model includes smoking, drinking, physical activity, systolic blood pressure, history of cardiovascular disorders, serum lipid disturbance, diabetes mellitus and antihypertensive drug treatment additionally.</p>*<p>p<0.05,</p>§<p>p<0.01,</p>¶<p>p<0.001.</p

Multivariable-adjusted hazard ratios (95% CI) for all causes mortality, cardiovascular mortality and non-cardiovascular mortality across eight groups of body mass index (BMI).

<p>The hazard ratio express the risk in the BMI group compared with the average risk in the whole study population, which were adjusted for sex, age, smoking, drinking, physical activity, systolic blood pressure, history of cardiovascular disorders, serum lipid disturbance, diabetes mellitus and antihypertensive drug treatment.</p

Baseline characteristics of the community hypertensive patients by category of body-mass index.

<p>Data are No. (%) or mean±SD. SBP and DBP indicate systolic and diastolic blood pressures. P values are for the difference among the eight groups. P values less than 0.05 are shown in bold and italics.</p

Cumulative incidence of all causes mortality, cardiovascular mortality and non-cardiovascular mortality across eight groups of body mass index (BMI).

<p>G1 to G8 indicate ascending BMI groups. Cutoff points were 18, 20, 22, 24, 26, 28,30 kg/m².</p

Multivariable adjusted hazard ratios for all causes mortality, cardiovascular mortality and non-cardiovascular mortality of body mass index (BMI) <18 kg/m² in subgroup analysis.

<p>The Cox regression model were adjusted for sex, age, smoking, drinking, physical activity, systolic blood pressure, history of cardiovascular disorders, serum lipid disturbance, diabetes mellitus and antihypertensive drug treatment additionally. Subgroups of age were determined according to quintiles.</p>*<p>p<0.05,</p>§<p>p<0.01,</p>¶<p>p<0.001.</p

Cl-Loss Dynamics of Vinyl Chloride Cations in the B²A″ State: Role of the C²A′ State

The dissociative photoionization of vinyl chloride (C₂H₃Cl) in the 11.0–14.2 eV photon energy range was investigated using threshold photoelectron photoion coincidence (TPEPICO) velocity map imaging. Three electronic states, namely, A²A′, B²A″, and C²A′, of the C₂H₃Cl⁺ cation were prepared, and their dissociation dynamics were investigated. A unique fragment ion, C₂H₃⁺, was observed within the excitation energy range. TPEPICO three-dimensional time-sliced velocity map images of C₂H₃⁺ provided the kinetic energy release distributions (KERD) and anisotropy parameters in dissociation of internal-energy-selected C₂H₃Cl⁺ cations. At 13.14 eV, the total KERD showed a bimodal distribution consisting of Boltzmann- and Gaussian-type components, indicating a competition between statistical and non-statistical dissociation mechanisms. An additional Gaussian-type component was found in the KERD at 13.65 eV, a center of which was located at a lower kinetic energy. The overall dissociative photoionization mechanisms of C₂H₃Cl⁺ in the B²A″ and C²A′ states are proposed based on time-dependent density functional theory calculations of the Cl-loss potential energy curves. Our results highlight the inconsistency of previous conclusions on the dissociation mechanism of C₂H₃Cl⁺

Associations of Lp-PLA₂ mass with intracranial and extracranial arterial stenosis.

<p>OR, odds ratio. Model I adjusted for age and sex. Model II adjusted for age, sex, BMI, hypertension duration, current smoking and drinking status, diabetes, LDL, HDL, plasma glucose, mean arterial pressure, heart rate, neutrophil account, urine albumin creatinine ratio, serum creatinine, anti-hypertensive treatment, and statin use. The odds ratio expressed the risk in the ICAS and ECAS group compared with the non-stenosis group. Isolated ECAS, extracranial arterial stenosis only; Isolated ICAS, intracranial arterial stenosis only; COMB, combined extra- and intracranial arterial stenosis. Complex ICAS, intracranial arterial stenosis no matter how was the extracranial arteries; Hypertension duration, neutrophil account, serum creatinine, urine albumin creatinine ratio and Lp-PLA₂ are log-transformed.</p><p>Associations of Lp-PLA₂ mass with intracranial and extracranial arterial stenosis.</p

Prevalence of moderate to severe ECAS and ICAS (%) (A) and distribution of ICAS vessels (B) according to tertiles of Lp-PLA₂.

<p>ECAS, extracranial arterial stenosis; ICAS, intracranial arterial stenosis; Lp-PLA2, Lipoprotein-associated phospholipase A_<b>2</b>.</p