Isomerization of cyanopropyne in solid argon.

Cyanopropyne, CH3-C[triple bond, length as m-dash]C-CN, is a simple molecule whose photochemistry is still unexplored. Here we investigate the UV photolysis of this astrophysically significant nitrile trapped in solid argon. The FTIR study was assisted with 15N-isotopic substitution data and with DFT-level computations including the analyses of ground- and excited-state potential energy surfaces.

Cryogenic Photochemical Synthesis and Electronic Spectroscopy of Cyanotetracetylene.

HCN is a molecule of astrochemical interest. In this study, it was produced in cryogenic Ar and Kr matrices from UV-photolyzed diacetylene/cyanodiacetylene mixtures. Its strong phosphorescence was discovered and served for the identification of the compound.

Electronic Spectroscopy of Methylcyanodiacetylene (CH C N).

The results of a study devoted to the electronic spectroscopy of gaseous, solid, and cryogenic matrix-isolated methylcyanodiacetylene (CH C N) are reported. UV absorption and optical phosphorescence spectra of the compound are described here for the first time, and the corresponding vibronic assignments are proposed. UV absorption, studied directly or through the excitation of phosphorescence, revealed the B˜   E--X˜   A system, very weak A˜   A -X˜   A bands, and a strong, broad absorption feature, tentatively identified as D˜   E-X˜   A .

Infrared and Raman Spectroscopy of Methylcyanodiacetylene (CH C N).

A spectroscopic study combining IR absorption and Raman scattering is presented for methylcyanodiacetylene (CH C N). Gas-phase, cryogenic matrix-isolated, and pure solid-phase substance was analyzed. Out of 16 normal vibrational modes, 14 were directly observed.

Synthesis and spectroscopy of cyanotriacetylene (HC7N) in solid argon.

UV laser irradiations of cryogenic solid argon matrices doped with a mixture of acetylene and cyanodiacetylene (HC5N) resulted in the formation of a longer carbon-nitrogen chain, cyanotriacetylene (HC7N). The identification of this species was accomplished based on IR vibrational spectroscopy (including the study of isotopically labeled compounds), on electronic luminescence spectroscopy, and on theoretical predictions. Additionally, IR absorption bands recognized as due to HC7N were detected in photolysed Ar matrices doped with a cyanoacetylene/diacetylene mixture; this assignment was confirmed with the mass spectrometry of gases released upon the warm-up of the sample.

Quantitative comparison of 21 protocols for labeling hippocampal subfields and parahippocampal subregions in in vivo MRI: towards a harmonized segmentation protocol.

Objective: An increasing number of human in vivo magnetic resonance imaging (MRI) studies have focused on examining the structure and function of the subfields of the hippocampal formation (the dentate gyrus, CA fields 1-3, and the subiculum) and subregions of the parahippocampal gyrus (entorhinal, perirhinal, and parahippocampal cortices). The ability to interpret the results of such studies and to relate them to each other would be improved if a common standard existed for labeling hippocampal subfields and parahippocampal subregions. Currently, research groups label different subsets of structures and use different rules, landmarks, and cues to define their anatomical extents.

Quantum chemical study on HKrC₅N, HXeC₅N, and related rare gas compounds.

The recent identification of HRgC5N (Rg = Kr, Xe) in a cryogenic matrix calls for an in-depth theoretical study on these compounds. Here we present the results of CCSD(T), MP2, and DFT calculations concerning the molecular structure, stability, and vibrational spectroscopy. The procedure combining CCSD(T) calculations for variable H-Rg distances with the anharmonic description of the corresponding stretching vibration, based on a Morse-type potential energy function, was proposed and has led to good agreement between computational and experimental values for H-Rg stretching frequencies, at relatively low computational costs.

Formation and spectroscopy of dicyanotriacetylene (NC₈N) in solid Kr.

Thermally induced creation of dicyanotriacetylene (NC8N) was observed in solid krypton. Samples were obtained by cryogenic trapping of gaseous cyanoacetylene/Kr mixtures subjected to electric discharges. Strong a (3)Σ(+)(u) → X (1)Σ(+)(g) phosphorescence of NC8N is reported here for the first time; its vibronic structure permitted the measurement of several ground-state vibrational frequencies.

Calculation of optical and electronic properties of modeled titanium dioxide films of different densities.

The electronic and optical properties of TiO2 atomic structures representing simulated thin films have been investigated using density functional theory. Suitable model parameters and system sizes have been identified in advance by validation of the results with experimental data. Dependencies of the electronic band gap and the refractive index have been calculated as a function of film density.

Effects of cationic hydroxyethyl cellulose on dyslipidemia in hamsters.

Cationic hydroxyethyl cellulose (cHEC) was supplemented in a high-fat diet to determine if this new soluble fiber had an effect on hypercholesterolemia and dyslipidemia associated with cardiovascular disease using Golden Syrian hamster as an animal model. Supplementation of 3-5% cHEC in a high-fat diet for 4 weeks led to significant weight gain reduction in hamsters. In addition, significant decreases in adipose and liver weights, concentrations of plasma total, VLDL, and LDL cholesterol, and hepatic lipids were shown.

UV-induced growth of cyanopolyyne chains in cryogenic solids.

UV laser excitation of cryogenic solids doped with cyanoethyne, HC(3)N, led to an in situ creation of longer carbon-nitrogen chains, namely HC(5)N, C(4)N(2), and C(6)N(2), heralded by their strong visible luminescence. HC(5)N and C(4)N(2) molecules can form, most probably, within HC(3)N aggregates linked by hydrogen bonds, while the reaction occurring between two isolated, photochemically created C(3)N radicals yields C(6)N(2). This latter species, dicyanobutadiyne, is easily detected in Ar, Kr, N(2), as well as in parahydrogen solids.

Supplementation of hydroxypropyl methylcellulose into yeast leavened all-whole grain barley bread potentiates cholesterol-lowering effect.

We investigated in Syrian Golden hamsters the biological impact and its underlying mechanism of single whole grain breads supplemented with 2-3% hydroxypropyl methylcellulose (HPMC), a semisynthetic viscous soluble dietary fiber (SDF) as a substitute for gluten. Hamsters were fed high-fat diets supplemented with 48-65% (w/w) differently ground, freeze-dried single grain breads including whole grain wheat, barley, barley supplemented with HPMC, debranned oat, and oat supplemented with HPMC which were compared to a diet containing microcrystalline cellulose (control). All single grain breads significantly lowered plasma LDL-cholesterol concentrations compared to the control.

Electronic absorption and phosphorescence of cyanodiacetylene.

Electronic absorption and emission spectra have been investigated for cyanodiacetylene, HC(5)N, an astrophysically relevant molecule. The analysis of gas-phase absorption was assisted with the parallel rare gas matrix isolation experiments and with density functional theory (DFT) predictions concerning the excited electronic states. Mid-UV systems B (1)Delta<--X (1)Sigma(+) (origin at 282.

Dose-response characteristics of high-viscosity hydroxypropylmethylcellulose in subjects at risk for the development of type 2 diabetes mellitus.

Background: Hydroxypropylmethylcellulose (HPMC) is a modified cellulose fiber that creates a viscous solution in the gastrointestinal tract. The present study examined the dose-response characteristics of high-viscosity (HV)-HPMC consumption on postprandial glucose and insulin levels in men and women at increased risk for type 2 diabetes mellitus.

Methods: Subjects were a subset of participants in two trials with elevated peak postprandial glucose [>or=7.

Lipid-altering effects of different formulations of hydroxypropylmethylcellulose.

Background: Hydroxypropylmethylcellulose (HPMC), a viscous, soluble dietary fiber, has been shown to be efficacious for lowering total and low-density lipoprotein cholesterol (LDL-C) concentrations. The relative effects of various dosages and viscosities of HPMC have not been fully evaluated.

Objective: To examine the lipid-altering effects of several formulations of HPMC.

Hydroxypropylmethylcellulose lowers cholesterol in statin-treated men and women with primary hypercholesterolemia.

Background/objectives: Consumption of hydroxypropylmethylcellulose (HPMC), a viscous dietary fiber, lowers total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). However, HPMC had not previously been studied in individuals receiving lipid drug therapy.

Subjects/methods: This randomized, double-blind crossover trial examined the lipid effects of HPMC in subjects with hypercholesterolemia on statin therapy.

The C3N- anion: first detection of its electronic luminescence in rare gas solids.

The 193 nm laser irradiation of cyanoacetylene (HCCCN) that was isolated in rare gas solids led to a long-lived luminescence (origin at 3.58 eV), which was assigned to the a (3)Sigma(+)-X (1)Sigma(+) system of cyanoacetylide (CCCN(-)). The identification, which involved (15)N and (2)H isotopic substitution studies, is based on vibronic spacings in the phosphorescence spectrum (compared to previous infrared absorption measurements and to theoretical results regarding CCCN(-) vibrational frequencies), as well as on a BD(T)/cc-pVTZ prediction for the singlet-triplet energy gap in this anion (3.

C(5)N(-) anion and new carbenic isomers of cyanodiacetylene: a matrix isolation IR study.

Products of the vacuum-UV photolysis of cyanodiacetylene (HC(5)N) in solid argon -- the anion C(5)N(-), imine HNC(5), and the branched carbene C(4)(H)CN -- have been identified by IR absorption spectroscopy, in addition to the already discovered isonitrile HC(4)NC. Spectral assignments were assisted by deuterium substitution experiments, by BD(T) calculations, and by the results of a recent density functional theory study.

Hydroxypropylmethylcellulose and methylcellulose consumption reduce postprandial insulinemia in overweight and obese men and women.

Hydroxypropylmethylcellulose (HPMC) and methylcellulose (MC) are modified cellulose dietary fibers that generate viscous solutions in the gastrointestinal (GI) tract. This study assessed the effects of high viscosity (HV) HPMC, ultra-HV (UHV) HPMC, and medium viscosity MC on postprandial glucose and insulin responses in overweight and obese men and women (n = 50). After overnight fasts, subjects consumed 5 breakfast meals containing 75 g carbohydrate, each of which contained 1 of the following: 1 g HV-HPMC, 2 g HV-HPMC, 2 g UHV-HPMC, 4 g medium-viscosity MC or control (2 g cellulose).

Simultaneous characterization of bile acid, sterols, and determination of acylglycerides in feces from soluble cellulose-fed hamsters using HPLC with evaporative light-scattering detection and APCI-MS.

The rapid rise in obesity-related diseases has increased interest in oral and dietary agents that disrupt fat metabolism, resulting in the excretion of dietary lipids in the feces. In this study, a rapid and convenient liquid chromatography method to comprehensively analyze fecal lipids in a single injection was developed. An evaporative light-scattering detector (ELSD) for routine analysis or atmosphere pressure chemical ionization tandem mass spectrometry [(+)APCI-MS/MS] for structural confirmation and peak purity was used.

Hydroxypropylmethylcellulose significantly lowers blood cholesterol in mildly hypercholesterolemic human subjects.

Objective: To determine the cholesterol-lowering efficacy of hydroxypropylmethylcellulose (HPMC) in mildly hypercholesterolemic humans.

Subjects: Trial one: entry mean (range) total serum cholesterol values of eight female and four male subjects were 6.48 (5.

Determination of methylcellulose and hydroxypropyl methylcellulose food gums in food and food products: collaborative study.

A collaborative study was performed to determine the reproducibility of a method for the determination of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) in food. These widely used food gums possess unusual solubility characteristics and cannot accurately be determined by existing dietary fiber methods. The new method uses the enzyme-digestion procedure of AOAC Official Method 991.

Spectroscopy of cyanodiacetylene in solid argon and the photochemical generation of isocyanodiacetylene.

Following the measurements of UV and mid-IR spectra of cyanodiacetylene, H-(CC)2-CN, isolated in low temperature Ar matrices, the first photochemical study on this compound and on its 2H isotopomer was carried out with the laser light tuned to 267 nm and with far-UV discharge lamps. Evidence for the formation of isocyanodiacetylene, H-(CC)2-NC, was found in infrared absorption spectra interpreted with the aid of available theoretical predictions.

High-viscosity hydroxypropylmethylcellulose blunts postprandial glucose and insulin responses.

Objective: High-viscosity hydroxypropylmethylcellulose (HV-HPMC) is a modified cellulose fiber that produces a viscous gel in the gastrointestinal tract. Clinical trials demonstrate that consumption of HV-HPMC significantly lowers cholesterol, but limited information has been available on the influence of HV-HPMC on postprandial insulin and glucose responses. The objective of this investigation was to assess the influence of HV-HPMC on postprandial glucose and insulin responses in overweight and obese men and women.