Distribution by Scientific Domains
Distribution within Chemistry

Terms modified by Kcal

  • kcal g
  • kcal kg
  • kcal min
  • kcal mol

  • Selected Abstracts

    New Beverage for Cardiovascular Health, Proposal Based on Oriental and Occidental Food Culture from a World-Wide Epidemiological Study

    Emilio Hideyuki Moriguchi
    Objectives: To investigate whether combined isoflavones and antioxidants in oriental and occidental drinks reduce the risk of cardiovascular disease (CVD) in high-risk Japanese immigrants living in Brazil. Materials and methods: From among over 100 Japanese immigrants thirty-seven females aged 45,60 years in Porto Alegre, Brazil, were randomized after informed consent into two groups to drink 200 ml of whole soy cell juice (S) containing 7.5 g soy protein and 10 mg of isoflavones (aglycone) in peach juice or placebo peach juice (P) with 80 Kcal for 12 weeks. Health survey including 24-hour urine (24 U) examination were carried out before the randomization and after the double blind placebo controlled intervention study. Results: Both weight and body mass index (BMI) were significantly (p < 0.05, 0.01) decreased from the baseline only in the S group. Systolic blood pressure (SBP) was decreased significantly (p < 0.05) from the baseline in the S group with elevated 24 U isoflavone excretion (>10 µmol), and there was a significant (p < 0.05) inter-group difference between the S and P groups after intervention. Total and low density lipoprotein (LDL)-cholesterol (C) decreased significantly (p < 0.05) in the S group from the baseline and there was a significant difference (p < 0.05) between the S and P groups after intervention. HbA1c and atherogenic index (non-high density lipoprotein (HDL)-C/HDL-C) were significantly (p < 0.05) decreased in both groups. Conclusions: Soy isoflavones combined with fruit antioxidants, the combination of which might potentiate local nitric oxide (NO) affect, decreased SBP, total cholesterol and LDL-C. Peach juice itself improved blood glucose levels and the atherogenic index of the high-risk Japanese population in Brazil. [source]

    Obesity and associated modifiable environmental factors in Iranian adolescents: Isfahan Healthy Heart Program , Heart Health Promotion from Childhood

    RoYA Kelishadi
    Abstract Objective:,To evaluate the prevalence of overweight and obesity among Iranian adolescents and their relationship with modifiable environmental factors. Methods:,The subjects of the present study were 1000 girls and 1000 boys, aged between 11 and 18 years selected by multistage random sampling, their parents (n = 2000) and their school staff (n = 500 subjects) in urban and rural areas of two provinces in Iran. Data concerning body mass index (BMI), nutrition and the physical activity of the subjects were analyzed by SPSSV10/Win software. Results:,The prevalence of 85th percentile , body mass index (BMI) < 95th percentile and BMI > 95th percentile in girls was significantly higher than boys (10.7 ± 1.1 and 2.9 ± 0.1%vs 7.4 ± 0.9 and 1.9 ± 0.1%, respectively; P < 0.05). The mean BMI value was significantly different between urban and rural areas (25.4 ± 5.2 vs 23.2 ± 7.1 kg/m2, respectively; P < 0.05). A BMI> 85th percentile was more prevalent in families with an average income than in high-income families (9.3 ± 1.7 vs 7.2 ± 1.4%, respectively; P < 0.05) and in those with lower-educated mothers (9.2 ± 2.1 vs 11.5 ± 2.4 years of mothers education, respectively). The mean total energy intake was not different between overweight or obese and normal-weight subjects (1825 ± 90 vs 1815 ± 85 kCal, respectively; P > 0.05), but the percentage of energy derived from carbo­hydrates was significantly higher in the former group compared with the latter (69.4 vs 63.2%, respectively; P < 0.05). Regular extracurricular sports activities were significantly lower and the time spent watching tele­vision was significantly higher in overweight or obese than non-obese subjects (time spent watching telelvision: 300 ± 20 vs 240 ± 30 min/day, P < 0.05). A significant linear association was shown between the frequency of consumption of rice, bread, pasta, fast foods and fat/salty snacks and BMI (, = 0.05,0.06; P < 0.05). A significant correlation was shown between BMI percentiles and serum triglyceride, high-density lipoprotein,cholesterol and systolic blood pressure (Pearson's r = 0.38, ,0.32 and 0.47, respectively). Conclusions:,Enhanced efforts to prevent and control overweight from childhood is a critical national priority, even in developing countries. To be successful, social, cultural and economic influences should be considered. [source]

    Effect of a nutritional liquid supplement designed for the patient with diabetes mellitus (Glucerna SR) on the postprandial glucose state, insulin secretion and insulin sensitivity in healthy subjects

    M. González-Ortiz
    Aim:, To identify the effect of a nutritional liquid supplement designed for the patient with diabetes mellitus (Glucerna SR) in single administration on the postprandial glucose state, insulin secretion and insulin sensitivity in healthy subjects. Methods:, A randomized, single-blind, cross-over, clinical trial was carried out in 14 young, healthy, non-obese, volunteers. A basal metabolic profile, which included glucose level, insulin, total cholesterol, high-density lipoprotein and low-density lipoprotein cholesterol, triglycerides, creatinine, and uric acid, was measured. Subjects received a single administration of 300 kcal, gauged with water at 350 ml, of each of the following (at least 3 days apart): glucose 75 g, polymeric supplement (Ensure high calcium) 315 ml or Glucerna SR 323 ml. At the beginning of each administration and 30, 60, 90 and 120 min later, glucose and insulin concentrations were measured. Areas under the curve of glucose and insulin were calculated. First-phase and total insulin secretions and insulin sensitivity were also estimated. Results:, Glucose level at 120 min was significantly lower after receiving Ensure high calcium or Glucerna SR. Administration of Glucerna SR resulted in a significant reduction in the areas under the curve of glucose and insulin, as well as in total insulin secretion with a tendency to be lower in their first phase. Insulin sensitivity was increased. Conclusions:, A single administration of Glucerna SR to healthy subjects decreased the postprandial glucose and insulin states, as well as the insulin secretion; insulin sensitivity increased. [source]

    Short-term nocturnal hypoglycaemia increases morning food intake in healthy humans

    DIABETIC MEDICINE, Issue 2 2008
    S. M. Schmid
    Abstract Aims Hypoglycaemia during wakefulness increases hunger and food intake. Patients with Type 1 diabetes mellitus are at high risk of recurrent hypoglycaemia and weight gain. Given the background of frequent hypoglycaemic episodes during night-time sleep in diabetic patients, we investigated morning food intake after nocturnal hypoglycaemia. Methods We tested 16 healthy normal-weight subjects (eight women) on three nights. A linear fall in plasma glucose to a nadir of 2.2 mmol/l within 60 min was induced by insulin infusion immediately after sleep onset (,early hypo') or after about 3.5 h of sleep (,late hypo'). On a control night, no hypoglycaemia was induced. Spontaneous food intake at a breakfast buffet was registered on the subsequent morning. Results Compared with the control condition (700 ± 93 kcal), subjects ate more after ,late hypo' (867 ± 108 kcal; P = 0.041), but not after ,early hypo' (852 ± 111 kcal; P = 0.130). Analyses of macronutrient fractions revealed that in comparison with the control condition, subjects ate significantly more carbohydrates after both ,late hypo' (277 ± 25 kcal vs. 206 ± 23 kcal, P < 0.001) and ,early hypo' (245 ± 23 kcal, P = 0.048), with this effect being more pronounced after late than early nocturnal hypoglycaemia (P = 0.026). Conclusions In healthy subjects, nocturnal hypoglycaemia during sleep stimulates spontaneous food intake the following morning, with carbohydrate intake being especially affected. Effects were more pronounced after ,late hypo', suggesting the influence of temporal dynamics. Although healthy non-diabetic subjects were studied, similar mechanisms may contribute to the frequently observed body weight gain in insulin-treated diabetic patients. [source]

    Mesomerization of S4 -Symmetric Tetrahedral Chelate Complex [In4(L3)4]: First-Time Monitored by Temperature-Dependent 1H NMR Spectroscopy,,

    Rolf W. Saalfrank
    Abstract VT 1H NMR spectroscopy proved that a non-dissociative and reversible mesomerization process links the tetranuclear indium(III) complexes meso -(,,,,,,,)(P,P,M,M)- 3 and meso -(,,,,,,,)(M,M,P,P)- 3,. During this process four tandem Bailar twists, resulting in the (,)/(,) isomerization at the indium centers, and the (P)/(M) inversion of the four coordinating face-centered, helical ligands (L3)3, are involved. In addition, gas-phase DFT calculations (B3LYP/LANL2DZp) revealed a C1 -symmetric transition state (+21.9 kcal,mol,1) for the mesomerization mechanism which connects 3 and 3,. [source]

    hypercloso -Hexa(amino)hexaboranes: Structurally Related to Known hypercloso -Dodecaboranes, Metastable with Regard to Their Classical Cycloisomers

    Wahid Mesbah
    Abstract B6(NMe2)6 (2a) is the first neutral hypercloso -hexaborane to be characterized by X-ray structural analysis. The geometry of 2a is in nice agreement with that of the Ci symmetric molecule computed at the B3LYP/6-311+G** level of theory. Two B3 triangles with long B···B distances in 2a are reminiscent of those in Hawthorne's benzyloxy-substituted hypercloso -dodecaboranes 6a,b. Upon heating to 200 °C, 2a transforms into Nöth's classical cyclohexaborane 1a. Computations at the B3LYP/6-311+G** + ZPE level of theory show 1a to be 21.6 kcal,mol,1lower in energy than 2a, that is, the latter is metastable. hypercloso -Hexaborane B6(NEt2)6 (2b), which was reported to be thermodynamically more stable than 1b, is computed to be 22.4 kcal,mol,1less stable than 1b. Pure 1b is shown here not to transform into 2b upon standing in solution, which is in contrast to reports in the literature for a mixture containing 1b. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    The Role of Amine,B(C6F5)3 Adducts in the Catalytic Reduction of Imines with H2: A Computational Study

    Timofei Privalov
    Abstract This study thoroughly examines the potential energy surfaces (PESs) of two possible mechanisms for reduction of imines by B(C6F5)3 and H2. The key reaction steps of the first catalytic mechanism, which is the focus of our study, are: (i) the uptake of H2 by a thermally activated amine,B(C6F5)3 species; (ii) proton transfer from the NH2+ moiety of [RNH2CH2R,]+[HB(C6F5)3], to the imine; (iii) nucleophillic attack of the C-center of the iminium ion by the BH, group. The potential energy barriers of the latter, as determined by calculating the evolution of the H-bonded complex of an imine and [RNH2CH2R,]+[HB(C6F5)3], in toluene, are around 10 kcal,mol,1 each. In the second mechanism, only imines serve as basic partners of B(C6F5)3 in the H2 activation, which affords an [RN(H)CHR,]+[HB(C6F5)3], ion pair; direct reduction then proceeds via nucleophilic attack of the C-center by the BH, in [RN(H)CHR,]+[HB(C6F5)3],. This route becomes catalytic when the product amine is released into the solvent and B(C6F5)3 is re-used for H2 activation. Upon taking into account the association energy of an amine,B(C6F5)3 adduct [,9.5 kcal,mol,1 for tBuN(H)CH2Ph and B(C6F5)3 in toluene], the potential energy barrier for H2 uptake by an imine and B(C6F5)3 increases to 14.5 kcal,mol,1. We report a somewhat lower potential energy barrier for H2 uptake by thermally activated amine,B(C6F5)3 adducts [12.7 kcal,mol,1 for the B-N adduct of tBuN(H)CH2Ph and B(C6F5)3 in toluene], although the difference between the two H2 activationbarriers is within the expected error of the computational method. Two catalytic routes are compared based on B3LYP-computed PESs in solvent (toluene).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    A Theoretical Study on the Reactivity of a Rhenium Hydroxo-Carbonyl Complex Towards ,-Lactams

    Violeta Yeguas
    Abstract The mechanism of the reaction between the complex [Re(OH)(CO)3(N2C2H4)] and azetidin-2-one or 3-formylamino- N -sulfonatoazetidin-2-one was investigated by using the B3LYP density functional theory methodology in conjunction with the PCM-UAHF model to take into account solvent effects. According to our calculations, the rate-determining energy barrier for the azetidin-2-one case of 38.8 kcal,mol,1, becomes 25.7 kcal,mol,1 in the case of the 3-formylamino- N -sulfonatoazetidin-2-one species. The presence of the sulfonato group is crucial for the cleavage of the ,-lactam N1,C2 bond by the Re complex thanks to the interaction of the sulfonato group with the hydroxy and bidentate ligands of the complex. This could be of interest for the synthesis of ,-amino acids and their derivatives from ,-lactams under mild conditions and in solvents of low polarity promoted by organometallic complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    Hierarchical Structures in Tin(II) Oxalates

    Padmini Ramaswamy
    Abstract Six new SnII oxalates exhibiting a hierarchy of structures have been prepared employing hydrothermal methods. The compounds I [C10N2H10][Sn(C2O4)2], II [C10N2H10][Sn2(C2O4)3], and III [C8N4H26][Sn(C2O4)2]2·2H2O possess zero-dimensional molecular structures; IV [C10N2H8]2[Sn(C2O4)]2 and V [C12N2H8][SnC2O4] have one-dimensional chain structures; and compound VI [C5N2H14]2[Sn4(C2O4)6]·7H2O has a two-dimensional layer structure. The SnII ions have 4- and 6-coordination with square-pyramidal or pentagonal-bipyramidal geometry, in which the lone pair of electrons also occupies one of the vertices. Weak intermolecular forces such as hydrogen-bond interactions, ,···, interactions, and lone-pair,, interactions have been observed and appear to lendstructural stability. Theoretical studies indicate that the ,···, interaction energy between the bound 1,10-phenanthroline molecules is of the order of 5,6 kcal,mol,1 in V. Natural bond orbital (NBO) analysis on two model compounds, II and IV, indicates reasonable lone-pair,, interactions. The close structural relationship between all the compounds indicates that a building-up process from the zero-dimensional monomer can be considered. The present structures provide opportunities for evaluating the structure-directing role of the lone pair of electrons of SnII.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    Monophosphanylcalix[6]arene Ligands: Synthesis Characterization, Complexation, and Their Use in Catalysis

    Yasushi Obora
    Abstract Novel phosphanylcalix[6]arenes having mono- O -diphenylphosphanylmethyl (3) and mono- O -(4-diphenylphosphanylphenyl)methyl substituents (5) have been synthesized. The structures of these monophosphanylcalix[6]arenes were determined by NMR spectroscopy, mass spectrometry, and X-ray crystal structure analysis. The X-ray structure reveals that 3 adopts a flattened 1,2,3-alternate conformation in the crystalline state, while the NMR spectra show that 3 and 5 have a cone conformation in solution. Structure optimization and energy calculations for 3 and 5 at the B3LYP/LANL2DZ-CONFLEX5/MMFF94s level of theory show that the cone conformation is slightly more stable than the 1,2,3-alternate conformation by 0.36 kcal,mol,1 for 3 and 0.96 kcal,mol,1 for 5. Complexation of 3 with [PtCl2(COD)] and [Rh(COD)2]BF4 gives cis -coordinated [PtCl2(3)2] and [Rh(COD)(3)2]BF4, respectively. The X-ray analysis of [PtCl2(3)2] shows that 3 adopts a cone conformation upon complexation. Combination of 3 and 5 with [Rh(COD)2]BF4 provides an active catalyst for the hydroformylation of a variety of terminal alkenes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    The Additive Nature of Energy Penalties in 10-Vertex nido -(Car)boranes

    Farooq A. Kiani
    Abstract A structural increment system, i.e. quantitative rules that govern the relative stabilities of 10-vertex nido -boranes and-carboranes, has been determined. Density functional theory computations at the B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level with ZPE corrections were carried out for 81 different boron hydride and carborane structures from [B10H12]2, to C3B7H11 to determine their relative stabilities. A set of eleven disfavored geometrical features that destabilize a cluster structure relative to a hypothetical ideal situation were identified and weighted by so-called energy penalties. The latter show good additive behavior and allow us to reproduce the DFT computed relative energies mostly with an accuracy of 6.0 kcal,mol,1. Some unknown 10-vertex nido- carboranes that are thermodynamically more stable than their known isomers are also identified. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    A Rearrangement of Azobenzene upon Interaction with an Aluminum(I) Monomer LAl {L = HC[(CMe)(NAr)]2, Ar = 2,6- iPr2C6H3}

    Hongping Zhu
    Abstract Reaction of LAl (1) or [LAl{,2 -C2(SiMe3)2}] (2) {L = HC[(CMe)(NAr)]2, Ar = 2,6- iPr2C6H3} with azobenzene affords a five-membered ring compound [LAl{N(H)- o -C6H4N(Ph)}] (3). In the formation of 3 a three-membered intermediate [LAl(,2 -N2Ph2)] (A) is suggested by a [1 + 2] cycloaddition reaction; A is not stable and further rearranges to 3. DFT calculations on similar compounds with modified L' {L' = HC[(CMe)(NPh)]2} show that the complexation energy of the reaction of L'Al with azobenzene to form [L'Al(,2 -N2Ph2)] is about,39 kcal,mol,1, and the best estimate of the energy difference between [L'Al(,2 -N2Ph2)] and [L'Al{N(H)- o -C6H4N(Ph)}] is,76 kcal,mol,1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    Kinetics of (Porphyrin)manganese(III)-Catalyzed Olefin Epoxidation with a Soluble Iodosylbenzene Derivative

    James P. Collman
    Abstract We examined the kinetics of a well-behaved system for homogeneous porphyrin-catalyzed olefin epoxidation with a soluble iodosylbenzene derivative 1 as the terminal oxidant and Mn(TPFPP)Cl (2) as the catalyst. The epoxidation rates were measured by using the initial rate method, and the epoxidation products were determined by gas chromatography. The epoxidation rate was found to be first order with respect to the porphyrin catalyst and zero order on the terminal oxidant. In addition, we found the rate law to be sensitive to the nature and concentration of olefin substrates. Saturation kinetics were observed with all olefin substrates at high olefin concentrations, and the kinetic data are consistent with a Michaelis,Menten kinetic model. According to the observed saturation kinetic results, we propose that there is a complexation between the active oxidant and the substrate, and the rate-determining step is thought to be the breakdown of this putative substrate,oxidant complex that generates the epoxidation products and the resting state porphyrin catalyst. Competitive epoxidations further indicate a reversible complexation of the active oxidant and the olefin substrate. The activation parameters ,H, and ,S, for the oxygen-transfer process (k2) in the cis -cyclooctene epoxidation were determined to be 12.3,±,0.9 kcal,mol,1 and,15.6,±,3.2 cal,mol,1,K,1, respectively. In addition, the Hammett constant ,+ was measured for the epoxidation of para -substituted styrenes, and the value of ,0.27,±,0.04 is too low to be consistent with the involvement of a discrete carbocation in the transition state. We also prepared a (porphyrin)manganese catalyst immobilized on silica support, and found the epoxidation of cis -cyclooctene catalyzed by this heterogeneous catalyst proceeds at virtually the same turnover frequency as by the homogeneous porphyrin catalyst. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Lewis Acid Induced [2+2] Cycloadditions of Silyl Enol Ethers with ,,,-Unsaturated Esters: A DFT Analysis

    Manuel Arnó
    Abstract The Lewis acid (LA) induced cycloaddition of trimethysilyl vinyl ether with methyl acrylate has been studied by DFT methods at the B3LYP/6-31G* level. In the absence of an LA, a [4+2] cycloaddition between the silyl enol ether and methyl acrylate in the s-cis conformation takes place through an asynchronous, concerted bond-formation process. This cycloaddition presents a large activation enthalpy of 21.1 kcal,mol,1. Coordination of the LA AlCl3 to the carbonyl oxygen atom of methyl acrylate yields a change of molecular mechanism from a concerted to a two-step mechanism and produces a drastic reduction of the activation energy. This stepwise mechanism is initialized by the nucleophilic attack of the enol ether at the ,-position of methyl acrylate in a Michael-type addition. The very low activation energy (7.1 kcal,mol,1)associated with this nucleophilic attack can be related to the increase of the electrophilicity of the LA-coordinated ,,,-unsaturated ester, which favors the cycloaddition through a polar process. The subsequent ring-closure allows the formation of the corresponding [2+2] and [4+2] cycloadducts. While the [4+2] cycloadduct is formed by kinetic control, the [2+2] cycloadducts are formed by thermodynamic control. The energetic results provide an explanation for the conversion of [4+2] cycloadducts into the thermodynamically more stable [2+2] ones. The cis/trans ratio found for the catalytic [2+2] process is in agreement with the experimental outcome. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    The histidine-phosphocarrier protein of Streptomyces coelicolor folds by a partially folded species at low pH

    FEBS JOURNAL, Issue 10 2003
    Gregorio Fernández-Ballester
    The folding of a 93-residue protein, the histidine-phosphocarrier protein of Streptomyces coelicolor, HPr, has been studied using several biophysical techniques, namely fluorescence, 8-anilinonaphthalene-1-sulfate binding, circular dichroism, Fourier transform infrared spectroscopy, gel filtration chromatography and differential scanning calorimetry. The chemical-denaturation behaviour of HPr, followed by fluorescence, CD and gel filtration, at pH 7.5 and 25 °C, is described as a two-state process, which does not involve the accumulation of thermodynamically stable intermediates. Its conformational stability under those conditions is ,G = 4.0 ± 0.2 kcal·mol,1 (1 kcal = 4.18 kJ), which makes the HPr from S. coelicolor the most unstable member of the HPr family described so far. The stability of the protein does not change significantly from pH 7,9, as concluded from the differential scanning calorimetry and thermal CD experiments. Conformational studies at low pH (pH 2.5,4) suggest that, in the absence of cosmotropic agents, HPr does not unfold completely; rather, it accumulates partially folded species. The transition from those species to other states with native-like secondary and tertiary structure, occurs with a pKa = 3.3 ± 0.3, as measured by the averaged measurements obtained by CD and fluorescence. However, this transition does not agree either with: (a) that measured by burial of hydrophobic patches (8-anilinonaphthalene-1-sulfate binding experiments); or (b) that measured by acquisition of native-like compactness (gel-filtration studies). It seems that acquisition of native-like features occurs in a wide pH range and it cannot be ascribed to a unique side-chain titration. These series of intermediates have not been reported previously in any member of the HPr family. [source]

    Comparison of some properties on the different types of pestil: a traditional product in Turkey

    Ozlem Cagindi
    Summary Pestil is a traditional dried fruit snack, which is consumed in Turkey. Wheat starch is mixed with different clarified fruit juices such as grape, mulberry, apricot or plum and cooked using traditional techniques. In this work the proximate chemical composition (moisture, ash, fat, crude protein and total carbohydrate), energy value and thickness of grape, apricot and mulberry pestils were investigated. The colour properties (Hunter L, a and b) were determined by a Minolta Chroma-Meter and the mineral content (Ca, Fe, K, Mg, Na, Cu, Zn, Mn) of each product was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The carbohydrate value of pestil samples ranged between 73.7 and 82.4% and energy value was between 321.5 and 356.4 kcal 100 g,1. Mulberry pestil was a better source of energy than grape and apricot pestils. Apricot pestils were rich in calcium, sodium and zinc, and mulberry pestil samples were rich in magnesium. [source]

    Hydrogenation of Phenol in Supercritical Carbon Dioxide Catalyzed by Palladium Supported on Al-MCM-41: A Facile Route for One-Pot Cyclohexanone Formation

    M. Chatterjee
    Abstract The hydrogenation of phenol has been carried out in supercritical carbon dioxide (scCO2) under very mild reaction conditions at the temperature of 50,°C over palladium supported Al-MCM-41 (metal loading ,1%). This palladium catalyst is shown to be highly active and promotes the selective formation of cyclohexanone (,98%), an industrially important compound, in a "one-pot" way. The effects of different variables like carbon dioxide and hydrogen pressure, reaction time and also silica/alumina ratio of the MCM-41 support along with palladium dispersion are presented and discussed. The pressure effect of carbon dioxide is significantly prominent in terms of conversion and cyclohexanone selectivity. Moreover, the silica/alumina ratio was also found to be an important parameter to enhance the effectiveness of the catalyst as it exhibits a remarkable increase in phenol conversion from 20.6% to 98.4% as the support changes from only silica MCM-41 to Al-MCM-41. A plausible mechanism for the hydrogenation of phenol to cyclohexanone over the palladium catalyst has been proposed. The proposition is validated by transition state calculations using density functional theory (DFT), which reveal that cyclohexanone is a favorable product and stabilized by <19,kcal,mol,1 over cyclohexanol in scCO2 medium. Under similar reaction conditions, phenol hydrogenation was also carried out with rhodium, supported on Al-MCM-41. In contrast to the palladium catalyst, a mixture of cyclohexanone (57.8%) and cyclohexanol (42.2%) was formed. Detailed characterization by X-ray diffraction and transmission electron microscopy confirmed the presence of metal nanoparticles (palladium and rhodium) between 10,20,nm. Both the catalysts exhibit strikingly different product distributions in solventless conditions compared to scCO2. This method can also be successfully applied to the other hydroxylated aromatic compounds. [source]

    Re-induction of obese body weight occurs more rapidly and at lower caloric intake in beagles

    D. Nagaoka
    Summary For the purpose of investigating the mechanism of obesity-induction/re-induction including weight-cycling in beagles, a study was conducted using commercially available dog food combined with human food to mimic at home-snacking and diet-supplementation behaviours. Adult female beagles, which had free access to water and exercise, were used (n = 9). All dogs were initially offered two times their daily calculated number of calories using a dry extruded diet plus blend of canola and soybean oils and allowed to eat ad libitum. After 3 weeks, Pecan shortbread cookies were added to the diet mixture. Obesity was induced during a 19-week period with 1875,2250 kcal/day consumed, on average, during this period. The dogs were then subjected to a weight-loss regimen while consuming 490,730 kcal/day. After weight loss, a similar degree of obesity was re-induced for 17 weeks even though dogs consumed only 1125,1250 kcal/day. Body weight, body condition scores, kcal consumption and food efficiency were recorded. Results indicated that less time and fewer kcal were required to re-induce the same degree of obesity compared with the initial obesity induction. Human snack foods appeared to stimulate appetite and thus contribute to the obese state. Food efficiency was also increased during the obesity-reinduction period compared with the induction period. This information may help pet owners better understand the need to limit table scraps and human-type food snacks in dogs prone to obesity as well as weight maintenance after weight loss. [source]

    Grafting emulsion polymerization of glycidyl methacrylate onto leather by chemical initiation systems

    K. A. Shaffei
    Abstract The kinetics of the grafting polymerization of glycidyl methacrylate (GMA) onto leather were studied with chemical initiation systems. The results showed that the rate of grafting of GMA onto leather was dependent on different rates in the chemical initiation systems; for ammonium persulfate (AmPS)/acetone sodium bisulfite (ASBS), potassium persulfate (PPS)/ASBS, and sodium persulfate (SPS)/ASBS, the powers were 1.06, 0.48, and 0.43 and 0.63, 0.46, and 0.43, respectively, with respect to the concentration of the emulsifier sodium dodecyl sulfate, whereas the powers were 1.41, 0.70, and 0.81, respectively, with respect to the monomer concentration. The apparent activation energy was calculated for each initiation system and was found to be 180.8, 361.63, and 542.45 kcal for the AmPS/ASBS, PPS/ASBS, and SPS/ASBS systems, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Role of UGT1A1 mutation in fasting hyperbilirubinemia

    Tomoaki Ishihara
    Abstract Background and Aim: Low-grade fasting hyperbilirubinemia is a common observation in healthy subjects (HS), whereas high-grade fasting hyperbilirubinemia is believed to be a characteristic finding of Gilbert's syndrome. This study was undertaken to assess the role of mutation in bilirubin UDP- glycosyltransferase gene (UGT1A1) on fasting hyperbilirubinemia. Methods: Analysis of UGT1A1 and a caloric restriction test (400 kcal for 24 h) were performed in 56 healthy subjects (25 males, 31 females), and 28 patients with Gilbert's syndrome (18 males, 10 females). There were 29 healthy subjects with no mutation in UGT1A1, and 27 healthy subjects and 26 Gilbert's syndrome patients with mutations in the coding and/or promoter (TATA box) regions of UGT1A1. Results: The mean increment of serum bilirubin (,SB) was 9.6 ,mol/L (males) and 4.1 ,mol/L (females) in subjects with no UGT1A1 mutation. Subjects with mutation in UGT1A1 showed higher levels of ,SB than individuals without mutation. Among healthy subjects, gender difference in ,SB values was observed only in individuals with the wild type of UGT1A1, but not in those with mutations in this gene. Conclusion: The results of the present study suggest that UGT1A1 mutation has a role in the development of high-grade fasting hyperbilirubinemia after caloric restriction. [source]

    Impact of some isoenergetic snacks on satiety and next meal intake in healthy adults

    E. Almiron-Roig
    Abstract Background:, Choosing small portions especially of low energy foods is a standard recommendation for weight management. However, this can result in rapid return of hunger or an increase in the next meal size. Enhancing the satiating capacities of low energy foods may help to overcome these effects. The present study compared the satiating properties of small servings of four low energy foods [465 kJ (111 kcal)] including a drinking yogurt enhanced for satiety. Methods:, Thirty volunteers attended the laboratory to consume isoenergetic preloads of: a fibre-enriched drinking yogurt, a regular drinking yogurt, plain crackers, fresh banana; or an isovolumetric serving of water. Satiety was analysed using visual analogue scales, before and every 15 min after consumption for 60 min, when ad libitum food intake was measured. Results:, The yogurts and the banana were more satiating than water and crackers (P < 0.001 for yogurts and banana versus crackers and water). Only the fibre-enriched yogurt produced higher satiety scores than crackers at 60 min (P < 0.05). Mean ± SD consumption at next meal was: fibre-enriched yogurt 2050 ± 787 kJ (490 ± 188 kcal); regular yogurt 2071 ± 575 kJ (495 ± 137 kcal); bananas 2178 ± 603 kJ (520 ± 144 kcal); crackers 2232 ± 590 kJ (533 ± 141 kcal); water 2519 ± 741 kJ (602 ± 177 kcal); (yogurts versus water: P = 0.001; bananas versus water: P = 0.013; crackers versus water: P = 0.064), demonstrating accurate energy compensation for the yogurts only. Conclusions:, Although there were no significant differences between the different foods' satiating capacity, a trend for the following ranking was found: fibre-enriched yogurt > regular yogurt > banana > crackers > water. Overall, the fibre-enriched drinking yogurt tended to be more satiating than the other foods. [source]

    A randomised, controlled trial of the effects of an energy-dense supplement on energy intake, appetite and blood lipids in malnourished community-based elderly patients

    G.P. Hubbard
    Background:, Disease-related malnutrition is common in the elderly and if left untreated may have severe consequences (Stratton & Elia, 2003). One of the strategies used to combat malnutrition is the use of high-energy, low-volume [18.8 kJ mL,1 (4.5 kcal ml,1)] nutritional supplements. This study aimed to investigate the effects of an energy dense supplement on energy intake, appetite and blood lipids in elderly patients at risk of malnutrition. Methods:, In this randomised, controlled, parallel study, 42 community-based patients (mean (SD) age: 84 (7.0) years, mean body mass index (BMI): 20.9 (3.5) kg m,2), identified as being at medium or high risk of malnutrition [Malnutrition Universal Screening Tool (MUST) (Elia, 2003)] were randomised (using standard randomisation methods) to receive either; (i) 1674 kJ day,1 (400 kcal day,1) (in 3 × 30 mL doses) of an energy-dense supplement (Calogen, Nutricia®) (n = 19) or (ii) dietary advice in the form of a standardised dietary advice sheet (n = 23), for 4 weeks. Energy intake, appetite, blood lipids [i.e. total cholesterol, low density lipoprotein (LDL) cholesterol (subset analysis only)], body weight, gastro-intestinal tolerance, product compliance and product acceptability were assessed during the 4 week study. Results are presented as mean (SD). Paired t -test and one way anova statistical analyses were undertaken using SPSS v15. Ethical approval for this study was obtained from the appropriate committee. Results:, Supplementation with the energy dense supplement significantly increased mean total daily energy intake by +1736 kJ (+415 kcal, P = 0.009) from 6456 (2330) kJ [1543 (557) kcal] to 8192 (1477) kJ [1958 (353) kcal], with no significant effect on voluntary food intake or appetite scores (for hunger, fullness and desire to eat). In the dietary advice group, although mean total daily energy intake was also significantly increased by +1105 kJ (+264 kcal, P = 0.026) from 5623 (2107) kJ [1344 (503) kcal] to 6728 (2029) kJ [1608 (485) kcal], it was significantly lower than in the energy dense group [-1464 kJ (-350 kcal), P = 0.012] at week 4. Both energy-dense and dietary advice groups maintained weight during the study. No significant adverse effects on blood lipid concentrations were observed in either group, with a significant decrease in total cholesterol concentrations [from 4.26 (1.0) mM to 3.96 (0.8) mM, P = 0.03] and LDL cholesterol concentrations [from 2.32 (0.6) mM to 2.06 (0.5) mM, P = 0.03] in the energy dense group (subset analysis, n = 9). Both supplementation with energy dense supplement and dietary advice were well tolerated with no gastro-intestinal side effects. The energy dense supplement was well accepted with >80% of patients rating it as pleasant and convenient, with an enjoyable taste. Compliance with the energy dense supplement was high, with 95% of patients consuming the recommended dose of 3 × 30 mL throughout the study. Discussion:, This study in elderly patients with or at risk of malnutrition suggests that the energy dense supplement is effective in significantly improving total intakes of energy with no suppression of appetite or voluntary dietary intake, enabling patients to maintain weight and that the energy dense supplement is well tolerated and accepted, with excellent compliance and no adverse effects on blood lipids. Conclusions:, This randomised controlled trial suggests that an energy-dense supplement is an effective, well tolerated and safe method of providing energy supplementation for the management of elderly patients with or at risk of malnutrition in clinical practice. References, Elia, M. (2003) The "MUST" report. Nutritional screening for adults: a multidisciplinary responsibility. Redditch, UK: BAPEN. Available at http://www.bapen.org.uk (accessed on 15 March 2008). Stratton, R.J., Green, C.J. & Elia, M. (2003) Disease-related malnutrition: an evidence-based approach. Oxford: CABI publishing. [source]

    Validation and reproducibility of a semi-quantitative Food Frequency Questionnaire for use in elderly Swiss women

    E. Wynn Dumartheray
    Abstract Objective, The principal aim of this study was to develop a Swiss Food Frequency Questionnaire (FFQ) for the elderly population for use in a study to investigate the influence of nutritional factors on bone health. The secondary aim was to assess its validity and both short-term and long-term reproducibility. Design, A 4-day weighed record (4 d WR) was applied to 51 randomly selected women of a mean age of 80.3 years. Subsequently, a detailed FFQ was developed, cross-validated against a further 44 4-d WR, and the short- (1 month, n = 15) and long-term (12 months, n = 14) reproducibility examined. Setting, French speaking part of Switzerland. Subjects, The subjects were randomly selected women recruited from the Swiss Evaluation of the Methods of Measurement of Osteoporotic Fracture cohort study. Results, Mean energy intakes by 4-d WR and FFQ showed no significant difference [1564.9 kcal (SD 351.1); 1641.3 kcal (SD 523.2) respectively]. Mean crude nutrient intakes were also similar (with nonsignifcant P -values examining the differences in intake) and ranged from 0.13 (potassium) to 0.48 (magnesium). Similar results were found in the reproducibility studies. Conclusion, These findings provide evidence that this FFQ adequately estimates nutrient intakes and can be used to rank individuals within distributions of intake in specific populations. [source]

    Nutrient intake of children consuming breakfast at school clubs in London

    S. Waddington
    Introduction: Research into the effectiveness of breakfast clubs has most commonly focused on social benefits to the child and school, such as improved attendance at school, punctuality and improved concentration levels in the classroom (UEA, 2002). Limited research has been undertaken to investigate the nutritional value of the breakfast foods on offer, or the nutritional content of foods consumed by the child. The aim of this study was to find out what children eat and drink at school breakfast clubs in London. Method: The sample population consisted of 98 children (39 boys and 59 girls) aged 5,11 years attending four primary schools in London. Data were collected about the food on offer and the pricing of different food items, demographic data about the children attending the school club, qualitative data on food preferences and a weighed food intake on two different occasions for each child. Statistical tests (anova and chi-squared tests) and nutrient analysis using Comp-Eat were carried out. Results: The average nutrient content of the breakfast meal consumed was 330 kcal, 12 g protein, 11 g fat and 49 g carbohydrate. Variation was seen between schools. Generally intakes of vitamin C, calcium and sodium were high and intakes of iron were average. anova between schools showed statistically significant results for a number of nutrients , protein, fat, saturated fat, carbohydrate, sugar, calcium and sodium. Boys were consuming statistically significantly more fat, saturated fat and calcium than girls. One in five children did not have a drink at breakfast. Menu options and pricing of food items varied between the schools and it was noted to influence children's food choice and consumption. Mean energy intakes equated to 18% of the estimated average requirement for boys and 20% for girls, with girls consuming more carbohydrate and sugar, and boys consumed more fat and protein. Discussion: The findings suggest that careful planning of menus should be undertaken with cereal-based options being offered daily and cooked options only occasionally, and that healthier eating messages can be incorporated effectively into school clubs when supported by the whole school approach to healthy eating. Conclusion: Food offered at school breakfast clubs can contribute substantial nutrients to a child's daily intake and therefore a varied menu, and guided food choices, should be developed incorporating healthier nutrient rich options. This work was supported by Brooke Bond working in partnership with the BDA Community Nutrition Group. [source]

    Determination of the electron affinities of ,- and ,-naphthyl radicals using the kinetic method with full entropy analysis.

    H bond dissociation energies of naphthalene, The C
    Abstract The C , H bond dissociation energies for naphthalene were determined using a negative ion thermochemical cycle involving the gas-phase acidity (,Hacid) and electron affinity (EA) for both the ,- and ,-positions. The gas-phase acidity of the naphthalene ,- and ,-positions and the EAs of the ,- and ,-naphthyl radicals were measured in the gas phase in a flowing afterglow,triple quadrupole apparatus. A variation of the Cooks kinetic method was used to measure the EAs of the naphthyl radicals by collision-induced dissociation of the corresponding ,- and ,-naphthylsulfinate adducts formed by reactions in the flow tube portion of the instrument. Calibration references included both , and , radicals, and full entropy analysis was performed over a series of calibration curves measured at collision energies ranging from 3.5 to 8 eV (center-of-mass). The measured EAs are 33.0 ± 1.4 and 31.4 ± 1.0 kcal mol,1 (1 kcal = 4.184 kJ) for the ,- and ,-naphthyl radicals, respectively. The gas-phase acidities for naphthalene were measured by the DePuy silane cleavage method, which utilizes the relative abundances of aryldimethylsiloxides and trimethylsiloxide that result from competitive cleavages from a proposed pentacoordinate hydroxysiliconate intermediate. The measured acidities are 394.0 ± 5.0 and 397.6 ± 4.8 kcal mol,1 for the ,- and ,- positions, respectively. The C , H bond dissociation energies calculated from the thermochemical cycle are 113.4 ± 5.2 and 115.4 ± 4.9 kcal mol,1 for the ,- and ,-positions, respectively. These energies are, to within experimental error, indistinguishable and are approximately the same as the first bond dissociation energy for benzene. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Substituent effects on conformational preference in , -substituted , -fluorophenylacetic acid methyl ester model systems for chiral derivatizing agents

    Riadh Sahnoun
    Abstract In connection with study of chiral derivatizing agents (CDAs) for NMR determination of absolute configuration of organic compounds, factors controlling the conformational preference between syn - and anti -forms in , -substituted , -fluorophenylacetic acid methyl ester (FC(X)(Ph)COOMe) model systems were theoretically investigated. Substituents X at the stereogenic carbon atom were X,=,H, CCH and CH3, the electronic and steric properties of which were significantly different from each other. The model system with X,=,CCH and that with X,=,CH3 were found to be possible candidates for fluorine-containing CDAs. The syn conformation is stable compared with the anti one by 0.7,kcal,mol,1 for the ester with X,=,CCH. On the other hand, the anti conformation is stable compared with the syn one by 0.5,kcal,mol,1 for the ester with X,=,CH3. Both natural bond orbital (NBO) analysis and deletion of selected orbitals based on the donor,acceptor NBO scheme were adopted for semi-quantitative estimation of factors responsible for the conformational preference as well as a qualitative inspection of occupied canonical molecular orbitals (MOs). It was shown that [,,(,*,+,,*)(CO)] and [,,,*(Ph) and ,(Ph),,*] hyperconjugations are the main factors controlling the conformational preferences between the syn and anti conformations. Other types of effects such as electrostatic effects were also investigated. The role of the fluorine atom was also clarified. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Effect of Lewis base coordination on boryl radical reactivity: investigation using laser flash photolysis and kinetic ESR

    Jacques Lalevée
    Abstract The effect of Lewis base coordination on boryl radical reactivity (L,BH where L is triethylamine, 2-picoline, 4-dimethylaminopyridine, quinoline and diphenyl phosphine) is examined. Direct detection of the different boryl radicals, their transient absorption spectra, their interaction with double or triple bonds, oxygen, oxidizing agent, alkyl halides and their hydrogen lability have been studied using laser flash photolysis (LFP), kinetic ESR (KESR), ESR spin trapping and MO calculations. For example, a strong decrease of both the bond dissociation energy (BDE)(BH) (33.8,kcal,mol,1) and the addition rate constant to MA (1300 105 to,>105 M,1,s,1) was noted when going from the triethylamine borane to the quinoline borane complex, in line with the spin delocalization (1.04 vs. 0.19). These structures are also proposed as new highly efficient co-initiators for the acrylate photopolymerization. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Anomeric effect plays a major role in the conformational isomerism of fluorinated pnictogen compounds

    Levindo E. Martins
    Abstract According to our theoretical studies, the anomeric effect, an stereoelectronic interaction between lone pair and a vicinal antibonding orbital, has shown to contribute decisively for the conformational isomerism of 1-fluoro- N,N -dimethylmethanamine (1) and of its corresponding P, As and Sb analogues (2,4). CX bonds in 2,4 are larger than in the parent compound 1, thus providing a LPX/CF* interaction progressively weaker on going from 1 to 4. However, such hyperconjugation contributed by more than 1.3,kcal,mol,1 for the stabilization of anti conformer in 4 (,LPXCF,=,180°), increasing to 24.1,kcal,mol,1 in 1. An isodesmic reaction model supported these findings. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    298,K enthalpies of formation of monofluorinated alkanes: theoretical predictions for methyl, ethyl, isopropyl and tert -butyl fluoride

    Bethany L. Kormos
    Abstract Experimentally measured 298,K enthalpies of formation are not well established for monofluoroalkanes. To supplement available experimental data, the multi-coefficient G3 (MCG3) quantum mechanical model has been applied to estimate this thermochemical quantity for methyl fluoride, ethyl fluoride, 2-fluoropropane (isopropyl fluoride) and 2-fluoro-2-methylpropane (tert -butyl fluoride). The following 298,K standard enthalpies of formation are suggested for these monofluoroalkanes: ,H (MeF),=,,57.1,±,0.2,kcal,mol,1, ,H (EtF),=,,66.5,±, 0.4,kcal,mol,1, ,H (i -PrF),=,,75.4±,0.5,kcal,mol,1, and ,H (t -BuF),=,,86.0,±,2.0,kcal,mol,1 (1,kcal,=, 4.184,kJ). Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Computational study of the chair,chair interconversion and stereoelectronic interactions in 1,2,3-trithiacyclo-hexane (1,2,3-trithiane)

    Fillmore Freeman
    Abstract Ab initio theory, density functional theory (DFT) and Mřller,Plesset perturbation theory (MP2) with the 6,31G(d), 6,31++G(d), 6,31G(d,p), 6,31+G(d,p), 6,31++G(d,p), 6,311G(d,p) and 6,311+G(d,p) basis sets were used to study stereoelectronic hyperconjugative interactions and the mechanism of the chair,chair conformational interconversion in 1,2,3-trithiacyclohexane (1,2,3-trithiane). The relative energies, enthalpies, entropies, free energies and structural parameters of the chair, 1,4-twist and 2,5-twist conformers, a distorted 1,4-boat transition state and a 2,5-boat transition state were calculated. The HF calculated energy difference (,E) between the chair conformer of 1,2,3-trithiane and the distorted 1,4-boat transition state was 10.59,kcal,mol,1 (1 kcal=4.184,kJ). The 1,4-twist conformer and the 2,5-boat transition state are close in energy, as are the 2,5-twist conformer and the distorted 1,4-boat transition state. B3LYP/6,311+G(d,p) calculated the chair conformer of 1,2,3-trithiane to be 5.83, 10.09, and 5.96,kcal,mol,1, respectively, lower in energy than the 1,4-twist conformer, 2,5-twist conformer and 2,5-boat transition state. Intrinsic reaction coordinate (IRC) calculations were used to connect the transition state between the chair conformer and the 1,4-twist conformer. B3LYP/6,31+G(d,p) and B3LYP/6,311+G(d,p) calculated this transition state to be 14.25,kcal,mol,1 higher in energy than the chair conformer. In the chair conformer, the respective C4,H and C6,H bond lengths are equal, but the C5,Heq bond is longer than the C5,Hax bond. In the 1,4-twist conformer, the C4,Hiso bond lengths are equal, the C5,H,eq bond is longer than the C5,H,ax bond and the C6,H bond lengths are equal. In the 2,5-twist conformer, equal C,H bond lengths are found at C4 and at C5, but the C6,H,eq bond is longer than the C6,H,ax bond. Copyright © 2003 John Wiley & Sons, Ltd. Additional material for this paper is available in Wiley Intersciene [source]