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We interrogated C6H and C8H produced separately from the reactions C3 + C3H2/C3H + C3H/C3H2 + C3 → C6H + H and C4 + C4H2/C4H + C4H/C4H2 + C4 → C8H + H using product translational and photoionization spectroscopy. Individual contributions of the three reactions to the product C6H or C8H were evaluated with reactant concentrations. Translational-energy distributions, angular distributions, and photoionization efficiency curves of products C6H and C8H were unraveled. The product C6H (C8H) was recognized as the most stable linear isomer by comparing its photoionization efficiency curve with that of l-C6H (l-C8H), produced exclusively from the reaction C2 + C4H2 → l-C6H + H (C2 + C6H2 → l-C8H + H). The ionization threshold after deconvolution was determined to be 9.3 ± 0.1 eV for l-C6H and 8.9 ± 0.1 eV for l-C8H, which is in good agreement with theoretical values. Quantum-chemical calculations indicate that the reactions of C3 + C3H2 and C3H + C3H (C4 + C4H2 and C4H + C4H) incur no energy barriers that lie above the corresponding reactant and the most stable product l-C6H (l-C8H) with H on the lower-lying potential-energy surfaces. The theoretical calculation is in accord with the experimental observation. This work implies that the reactions of C3 + C3H2/C3H + C3H and C4 + C4H2/C4H + C4H need to be taken into account for the formation of interstellar C6H and C8H, respectively. [ABSTRACT FROM AUTHOR]

The IR and UV absorption spectra of CO 2 + isolated in solid neon were studied by using our newly built mass-selective matrix isolation system. The IR absorption spectrum revealed the formation of CO2 in both cationic and anionic forms in solid Ne, since neutral CO2 was also used to serve as an electron scavenger in this study. Subsequently, we recorded the UV absorption spectrum of the same matrix sample in the spectral region 270−400 nm, encompassing the electronic transitions of CO 2 + from the ground state to the first two electronic excited states. Notably, the observation of the electronic transition A 2 Π u ← X 2 Π g was dominated by the vibrational progression of the symmetric CO stretching mode, while a single sharp band was observed in the electronic transition B 2 Σ u + ← X 2 Π g. The presented spectra might be useful for future studies on terrestrial and astrochemical conjunctions. [ABSTRACT FROM AUTHOR]

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The infrared (IR) spectrum of monobridged Si2H4 (denoted as mbr-Si2H4) isolated in solid Ar was recorded, and a set of lines (in the major matrix site) observed at 858.3 cm−1, 971.5 cm−1, 999.2 cm−1, 1572.7 cm−1, 2017.7 cm−1, 2150.4 cm−1, and 2158.4 cm−1 were characterized. The species was produced by the electron bombardment of an Ar matrix sample containing a small proportion of SiH4 during matrix deposition. Upon photolysis of the matrix samples using 365 nm and 160 nm light, the content of mbr-Si2H4 increased. The band positions, relative intensity ratios, and D-isotopic shift ratios of the observed IR features are generally in good agreement with those predicted by the B3LYP/aug-cc-pVTZ method. In addition, the photochemistry of the observed products was discussed. [ABSTRACT FROM AUTHOR]

Diabetes mellitus (DM) is often accompanied by clinical complications such as sarcopenia. Previous studies have indicated that oxidative stress and insulin resistance (IR) are highly associated with the pathogenesis of diabetic myopathy. α‐lipoic acid (ALA), a potent biological antioxidant, exists abundantly in a variety of plants and vegetables. This study aimed to investigate the ameliorative effect of ALA on muscle atrophy in type 2 diabetic rats induced by high‐fat diet feeding (HFD) plus streptozotocin (STZ) injection. The HFD/STZ‐induced diabetic rats were orally administered 50, 100, or 200 mg/kg body weight ALA once a day for 13 weeks. The results showed that ALA at the tested concentrations significantly increased the soleus muscle mass and muscle fibers in diabetic rats. Proinflammatory cytokines, such as tumor necrosis factor (TNF)‐α, were found to decrease in both the serum and muscle of ALA‐treated diabetic rats. ALA significantly reduced the protein‐expression levels of phosphorylated c‐Jun N‐terminal kinase (pJNK)/JNK, forkhead box O3 (FOXO3), and muscle ring‐finger protein‐1 (Murf1); whereas, it enhanced the protein‐expression levels of phosphoinositide 3‐kinase (PI3K), phosphorylated protein kinase B (pAKT)/AKT, myogenin determination gene D (MyoD), the mechanistic target of rapamycin (mTOR), and myosin heavy chain (MyHC) in the soleus muscle of diabetic rats. The results from this study suggested that ALA treatment may preserve soleus muscle mass, alleviate muscle atrophy by suppressing the TNF‐α/JNK pathway, and ameliorate the PI3K/AKT pathway in HFD/STZ‐induced type 2 diabetic rats. [ABSTRACT FROM AUTHOR]

Two product channels C3H2F + H and C3H3 + F were identified in the reaction of C(3P) atoms with vinyl fluoride (C2H3F) at collision energy 3.7 kcal mol-1 in a crossed molecular-beam apparatus using selective photoionization. Time-of-flight (TOF) spectra of products C3H2F and C3H3 were measured at 12-16 laboratory angles as well as a TOF spectrum of atomic F, a counter part of C3H3, was recorded at single laboratory angle. From the best simulation of product TOF spectra, translational-energy distributions at seven scattering angles and a nearly isotropic (forward and backward peaked) angular distribution were derivable for exit channel C3H2F + H (C3H3 + F) that has average kinetic-energy release of 14.5 (4.9) kcal mol-1. Products C3H2F + H and C3H3 + F were estimated to have a branching ratio of ∼53:47. Furthermore, TOF spectra and photoionization spectra of products C3H2F and C3H3 were measured at laboratory angle 62° with photoionization energy ranging from 7 eV to 11.6 eV. The appearance of TOF spectra is insensitive to photon energy, implying that only single species overwhelmingly contributes to products C3H2F and C3H3. HCCCHF (H2CCCH) was identified as the dominant species based on the measured ionization threshold of 8.3 ± 0.2 (8.6 ± 0.2) eV and the maximal translational-energy release. The C/H and C/F exchange mechanisms are stated. [ABSTRACT FROM AUTHOR]

We investigated the reaction N(4S,2D,2P)+SiH4 in crossed molecular beams at a collision energy of 4.7 kcal mol-1 with a time-of-flight mass spectrometer and selective photoionization. Ion signals were observed at m/z=42–45, associated with two product channels, HSiNH/SiNH2+H+H and HSiN/HNSi+H2+H. The species producing the signal at m/z=43 is assigned to product HSiN/HNSi and that at m/z=44 to product HSiNH/SiNH2. The signal observed at m/z=42 is attributed to daughter ions of those two products and that at m/z=45 to 29Si and 30Si isotopic variants. We report time-of-flight spectra as a function of laboratory angle and simulations for the two products, from which both kinetic-energy and angular distributions of products in the center-of-mass (c.m.) frame were derived. The dependence of release of kinetic energy on the c.m. scattering angle is weak. The average translational energy released is 7.7 kcal mol-1 for product channel HSiNH/SiNH2+H+H and 30.3 kcal mol-1 for product channel HSiN/HNSi+H2+H. Through consecutive triple fragmentation, the angular distribution is slightly anisotropic for product HSiNH/SiNH2 but isotropic for product HSiN/HNSi. Assuming equal efficiencies of detection, we estimate the branching ratios of products HSiNH/SiNH2 and HSiN/HNSi to be roughly 15:85. To facilitate an understanding of the reaction mechanisms, we calculated the potential-energy surface for reaction N(2D)+SiH4 with quantum-chemical methods. Reactions N(2D)+SiH4→SiNH2+H+H and N(2D)+SiH4→HNSi+H2+H account satisfactorily for the present experimental results. Isomeric products HSiNH and HSiN are minor in this work. [ABSTRACT FROM AUTHOR]

Using photofragment translational spectroscopy and tunable vacuum-ultraviolet ionization, we measured the time-of-flight spectra of fragments upon photodissociation of vinyl fluoride (CH2CHF) at 157 and 193 nm. Four primary dissociation pathways—elimination of atomic F, atomic H, molecular HF, and molecular H2—are identified at 157 nm. Dissociation to C2H3+F is first observed in the present work. Decomposition of internally hot C2H3 and C2H2F occurs spontaneously. The barrier heights of CH2CH→CHCH+H and cis-CHCHF→CHCH+F are evaluated to be 40±2 and 44±2 kcal mol-1, respectively. The photoionization yield spectra indicate that the C2H3 and C2H2F radicals have ionization energies of 8.4±0.1 and 8.8±0.1 eV, respectively. Universal detection of photoproducts allowed us to determine the total branching ratios, distributions of kinetic energy, average kinetic energies, and fractions of translational energy release for all dissociation pathways of vinyl fluoride. In contrast, on optical excitation at 193 nm the C2H2+HF channel dominates whereas the C2H3+F channel is inactive. This reaction C2H3F→C2H2+HF occurs on the ground surface of potential energy after excitation at both wavelengths of 193 and 157 nm, indicating that internal conversion from the photoexcited state to the electronic ground state of vinyl fluoride is efficient. We computed the electronic energies of products and the ionization energies of fluorovinyl radicals. [ABSTRACT FROM AUTHOR]