Quasiclassical Trajectory Study of the Rotational Mode Specificity in the O(P-3) + CHD3(v(1)=0, 1, JK) -> OH + CD3 Reactions

Quasiclassical trajectory computations on an ab initio potential energy surface reveal that rotational excitation can significantly enhance the reactivity of the ground-state and CH stretching-excited O(P-3) + CHD3(v1 = 0,1, JK) -> OH + CD3 reactions. The state-specific rotational effects investigated up to J = 8 show that the K = 0 (tumbling rotation) enhancement factors can be as large as 1.5-3.5 depending on J and the collision energy, whereas the K = J (spinning rotation about the CH axis) excitations do not have any significant effect on the reactivity. The shapes of the opacity functions and scattering angle distributions depend on the initial vibrational state, but show virtually no JK dependence. The origin of the K = 0 rotational enhancements is that the tumbling rotation enlarges the range of the reactive initial attack angles, thereby increasing the reactivity

On equilibrium structures of the water molecule

Equilibrium structures are fundamental entities in molecular sciences. They can be inferred from experimental data by complicated inverse procedures which often rely on several assumptions, including the Born-Oppenheimer approximation. Theory provides a direct route to equilibrium geometries. A recent high-quality ab initio semiglobal adiabatic potential-energy surface (PES) of the electronic ground state of water, reported by Polyansky [ ibid. 299, 539 (2003)] and called CVRQD here, is analyzed in this respect. The equilibrium geometries resulting from this direct route are deemed to be of higher accuracy than those that can be determined by analyzing experimental data. Detailed investigation of the effect of the breakdown of the Born-Oppenheimer approximation suggests that the concept of an isotope-independent equilibrium structure holds to about 3x10(-5) A and 0.02 degrees for water. The mass-independent [Born-Oppenheimer (BO)] equilibrium bond length and bond angle on the ground electronic state PES of water is r(e)(BO)=0.957 82 A and theta(e)(BO)=104.48(5)degrees, respectively. The related mass-dependent (adiabatic) equilibrium bond length and bond angle of (H2O)-O-16 is r(e)(ad)=0.957 85 A and theta(e)(ad)=104.50(0)degrees, respectively, while those of (D2O)-O-16 are r(e)(ad)=0.957 83 A and theta(e)(ad)=104.49(0)degrees. Pure ab initio prediction of J=1 and 2 rotational levels on the vibrational ground state by the CVRQD PESs is accurate to better than 0.002 cm(-1) for all isotopologs of water considered. Elaborate adjustment of the CVRQD PESs to reproduce all observed rovibrational transitions to better than 0.05 cm(-1) (or the lower ones to better than 0.0035 cm(-1)) does not result in noticeable changes in the adiabatic equilibrium structure parameters. The expectation values of the ground vibrational state rotational constants of the water isotopologs, computed in the Eckart frame using the CVRQD PESs and atomic masses, deviate from the experimentally measured ones only marginally, especially for A(0) and B-0. The small residual deviations in the effective rotational constants are due to centrifugal distortion, electronic, and non-Born-Oppenheimer effects. The spectroscopic (nonadiabatic) equilibrium structural parameters of (H2O)-O-16, obtained from experimentally determined A(0)(') and B-0(') rotational constants corrected empirically to obtain equilibrium rotational constants, are r(e)(sp)=0.957 77 A and theta(e)(sp)=104.48 degrees

Diagnosis and treatment in chronic pancreatitis: an international survey and case vignette study

BACKGROUND: The aim of the study was to evaluate the current opinion and clinical decision-making process of international pancreatologists, and to systematically identify key study questions regarding the diagnosis and treatment of chronic pancreatitis (CP) for future research. METHODS: An online survey, including questions regarding the diagnosis and treatment of CP and several controversial clinical case vignettes, was send by e-mail to members of various international pancreatic associations: IHPBA, APA, EPC, ESGE and DPSG. RESULTS: A total of 288 pancreatologists, 56% surgeons and 44% gastroenterologists, from at least 47 countries, participated in the survey. About half (48%) of the specialists used a classification tool for the diagnosis of CP, including the Mayo Clinic (28%), Mannheim (25%), or Buchler (25%) tools. Overall, CT was the preferred imaging modality for evaluation of an enlarged pancreatic head (59%), pseudocyst (55%), calcifications (75%), and peripancreatic fat infiltration (68%). MRI was preferred for assessment of main pancreatic duct (MPD) abnormalities (60%). Total pancreatectomy with auto-islet transplantation was the preferred treatment in patients with parenchymal calcifications without MPD abnormalities and in patients with refractory pain despite maximal medical, endoscopic, and surgical treatment. In patients with an enlarged pancreatic head, 58% preferred initial surgery (PPPD) versus 42% initial endoscopy. In patients with a dilated MPD and intraductal stones 56% preferred initial endoscopic +/- ESWL treatment and 29% preferred initial surgical treatment. CONCLUSION: Worldwide, clinical decision-making in CP is largely based on local expertise, beliefs and disbeliefs. Further development of evidence-based guidelines based on well designed (randomized) studies is strongly encouraged

Isolated hypercholesterolemia leads to steatosis in the liver without affecting the pancreas

Abstract Background Lipid accumulation in the liver and pancreas is primarily caused by combined hyperlipidemia. However, the effect of isolated hypercholesterolemia without hypertriglyceridemia is not fully described. Therefore, our aim was to investigate whether hypercholesterolemia alone leads to alterations both in hepatic and pancreatic lipid panel and histology in rats. Methods Male Wistar rats were fed with 2% cholesterol +0.25% cholate-supplemented diet or standard chow for 12 weeks. Blood was collected at weeks 0, 4, 8 and 12 to measure serum cholesterol and triglyceride levels. At week 12, both the pancreas and the liver were isolated for further histological and biochemical analysis. Hepatic and plasma fatty acid composition was assessed by gas chromatography. Expression of mRNA of major enzymes involved in saturated/unsaturated fatty acid synthesis was analyzed by qPCR. In separate experiments serum enzyme activities and insulin levels were measured at week 9. Results At week 12, rats fed with 2% cholesterol +0.25% cholate-supplemented diet were characterized by elevated serum cholesterol (4.09 ± 0.20 vs. 2.89 ± 0.22 mmol/L, *p < 0.05) while triglyceride (2.27 ± 0.05 vs. 2.03 ± 0.03 mmol/L) and glucose levels (5.32 ± 0.14 vs. 5.23 ± 0.10 mmol/L) remained unchanged. Isolated hypercholesterolemia increased hepatic lipid accumulation, hepatic cholesterol (5.86 ± 0.22 vs. 1.60 ± 0.15 ng/g tissue, *p < 0.05) and triglyceride contents (19.28 ± 1.42 vs. 6.78 ± 0.71 ng/g tissue, *p < 0.05), and hepatic nitrotyrosine level (4.07 ± 0.52 vs. 2.59 ± 0.31 ng/mg protein, *p < 0.05). The histology and tissue lipid content of the pancreas was not affected. Serum total protein level, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities remained unchanged in response to isolated hypercholesterolemia while serum alkaline phosphatase activity (ALP) significantly increased. Plasma insulin levels did not change in response to isolated hypercholesterolemia suggesting an intact endocrine function of the pancreas. Isolated hypercholesterolemia caused a significantly increased hepatic and serum fatty acid level associated with a marked alteration of fatty acid composition. Hepatic expression of Δ9-desaturase (SCD1) was increased 4.92×, while expression of Δ5-desaturase and Δ6-desaturase were decreased (0.447× and 0.577×, respectively) due to isolated hypercholesterolemia. Conclusions Isolated hypercholesterolemia leads to hepatic steatosis and marked alterations in the hepatic lipid profile without affecting the pancreas. Altered fatty acid profile might mediate harmful effects of cholesterol in the liver

Inward and Outward FDI Country Profiles, Second Edition

This second edition contains a series of 77 standardized country profiles dealing with the inward and outward foreign direct investment (FDI) performance of 40 economies. The profiles have been peer-reviewed by a global network of experts. The publication is intended to contribute to the analysis of trends in foreign direct investment and policy issues related to them. More specifically, the individual profiles discuss FDI trends and developments (country-level developments, the corporate players); effects of the recent global crises; and the policy scene. Each profile contains a standard set of tables, including on FDI stocks and flows, sectoral and geographical FDI distributions, the largest M&As and greenfield investments, the principal foreign affiliates (for inward FDI), and the principal multinational enterprises (for outward FDI). The standardized template used to produce the profiles allows cross-country comparisons. The volume is meant to be a reference tool for anyone interested in foreign direct investment

Roadmap on dynamics of molecules and clusters in the gas phase

This roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics of molecules and clusters in the gas phase. It comprises nineteen contributions by scientists with leading expertise in complementary experimental and theoretical techniques to probe the dynamics on timescales spanning twenty order of magnitudes, from attoseconds to minutes and beyond, and for systems ranging in complexity from the smallest (diatomic) molecules to clusters and nanoparticles. Combining some of these techniques opens up new avenues to unravel hitherto unexplored reaction pathways and mechanisms, and to establish their significance in, e.g. radiotherapy and radiation damage on the nanoscale, astrophysics, astrochemistry and atmospheric science