Kinetics of <Superscript>14</Superscript>C distribution after tracer dose of <Superscript>14</Superscript>C-lutein in an adult woman

Lutein is an oxygenated carotenoid (xanthophyll) found in dark green leafy vegetables. High intakes of lutein may lower the risk of age-related macular degeneration. Current understanding of human lutein metabolism as it might occur in vivo is incomplete. Therefore, we conducted a feasibility study where we dosed a normal adult woman with ¹⁴C-lutein (125 nmol, 36 nCi ¹⁴C), dissolved in olive oil (0.5 g/kg body weight) and mixed in a banana shake. Blood, urine, and feces collected before the dose was administered served to establish baseline values. There-after, blood was collected for 63 d following the dose, while feces and urine were collected for 2 wk post-dose. The ¹⁴C contents in plasma, urine, and feces were measured by accelerator MS. The ¹⁴C first appeared in plasma 1 h after dosing and reached its highest level,≈2.08% of dose/L plasma, at 14 h post-dose. The plasma pattern of ¹⁴C did not include a chylomicrons/VLDL (intestinal) peak like that when the same subject received ¹⁴C-β-carotene (a previous test), suggesting that lutein was handled differently from β-carotene by plasma lipoproteins. Lutein had an elimination half-life (t _1/2) of≈10 d. Forty-five percent of the dose of ¹⁴C was eliminated in feces and 10% in urine in the first 2 d after dosing. Quantifying human lutein metabolism is a fertile area for future research.     

Linseed oil and mixture with maleic anhydride: <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR

It was shown that ¹H NMR allowed a rapid determination of the ratio of the linolenic residues over all the others (linoleic + oleic + saturated) and ¹³C NMR allowed a rapid determination of the ratio of linolenic over (linoleic + oleic) residues as well as the linoleic/oleic ratio in a few minutes on less than 20 mg of crude LO. After thermal treatment (220°C for 2 h, followed by cooling to room temperature), a 1∶1 mixture of linseed oil (LO) and maleic anhydride (MA), which was a suspension, became limpid and remained limpid. Moreover, the viscosity of the mixture was higher than that of pure LO treated in the same way. It was shown by ¹³C NMR and quantitative recovery of the constituents (LO and MA) through solvent separation that no reaction occurred between LO and MA during this thermal treatment. This result is in accord with DSC analysis of such a 1∶1 LO/MA mixture that exhibited an exothermic effect too small (about 34 kcal/mol) to correspond to formation of a C−C bond.     

Subsoil <Superscript>15</Superscript>N-N<Subscript>2</Subscript>O Concentrations in a Sandy Soil Profile After Application of <Superscript>15</Superscript>N-fertilizer

Studies on emissions of nitrous oxide (N₂O) from agricultural soils mostly focus on fluxes between the soil and the atmosphere or are limited to the atmosphere in the topsoil. However, in soils with shallow water tables, significant N₂O formation may occur closer to the groundwater. The aims of this study were (i) to determine the importance of subsoil N₂O formation in a sandy soil; and (ii) to obtain a quantitative insight in the contribution of subsoil N₂O to the overall losses of N₂O to the environment. We applied ¹⁵N labeled fertilizer at a rate of 5.22 kg ¹⁵N ha⁻¹; 50% as Ca(NO₃)₂ and 50% as NH₄Cl, on a mesic typic Haplaquod seeded with potatoes (Solanum tuberosum L.), and traced soil N₂O concentrations and fluxes over a one-year period. Throughout the year, total N₂O and the amount of ¹⁵N recovered in soil N₂O were highest in the subsoil, with a maximum concentration at 48 cm depth in mid-February of 19900 μl m⁻³ and 24 μg ¹⁵N m⁻³, respectively. The maximum concentration coincided with the highest water-filled pore space of 71%. The cumulative flux of N₂O was 446 g N₂O-N ha⁻¹, the recovery of ¹⁵N in this flux was 0.06%. During the summer, maximum fluxes followed high soil N₂O concentrations. During winter, no such relation was found. We concluded that the formation of N₂O was the highest in the subsoil, largely controlled by water-filled pore space rather than NO₃⁻ concentration or temperature. Although high subsoil N₂O concentrations did not lead to high surface fluxes of N₂O in the winter, artificial draining may lead to high indirect N₂O emissions through supersaturated drainage water.     

<Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR characterization and stereochemical assignments of bile acids in aqueous media

The unconjugated bile acids cholic acid, deoxycholic acid, and chenodeoxycholic acid; their glycine and taurine conjugated glycocholic acid, glycodeoxycholic acid, glycochenodeoxycholic acid, taurocholic acid, taurodeoxycholic acid, and taurochenodeoxycholic acid; and a taurine conjugated ursodeoxycholic acid, tauroursodeoxycholic acid, were characterized through ¹H and ¹³C NMR in aqueous media under the physiological pH region (7.4±0.1). Assignments of ¹H and ¹³C signals of all the bile acids were made using a combination of several one- and two-dimensional, homonuclear (¹H−¹H) and heteronuclear (¹H−¹³C) correlations as well as spectral editing NMR methods. Stereochemical assignment of the five-membered ring of the bile acids is reported here for the first time. The complete characterization of various bile acids in aqueous media presented here may have implications in the study of the pathophysiology of biliary diseases through human biliary fluids using NMR spectroscopy.     

Field-assisted diffusion of K<Superscript>+</Superscript>, Rb<Superscript>+</Superscript>, Cs<Superscript>+</Superscript>, Ag<Superscript>+</Superscript>, and Tl<Superscript>+</Superscript> ions in sodium silicate glass

The composition of the diffusion zone formed during the interaction between 20Na₂O · 80SiO₂ glass and molten silver, rubidium, cesium, and thallium nitrates with and without imposition of a constant electric field was determined using X-ray microanalysis. The interdiffusion coefficients and values of electrical mobility were calculated, and the parameters of temperature dependence were determined. The electrical mobility was almost independent of the size and chemical nature of a cation and was determined by the mobility of the cation included into the initial glass.     

Visible up-conversion luminescence of CaWO<Subscript>4</Subscript>: Er<Superscript>3+</Superscript>,Yb<Superscript>3+</Superscript> and emission enhancement by tri-doping of Li<Superscript>+</Superscript> ions

Er³⁺,Yb³⁺ co-doped CaWO₄ polycrystalline powders were prepared by a solid-state reaction and their up-conversion (UC) luminescence properties were investigated in detail. Under 980 nm laser excitation, CaWO₄: Er³⁺,Yb³⁺ powder exhibited green UC emission peaks at 530 and 550 nm, which were due to the transitions of Er³⁺ (²H_11/2)→Er³⁺ (⁴I_15/2) and Er³⁺ (⁴S_3/2)→Er³⁺ (⁴I_15/2), respectively. Effects of Li+ tri-doping into CaWO₄: Er³⁺,Yb³⁺ were investigated. The introduction of Li⁺ ions reduced the optimum calcinations temperature about 100 °C by a liquid-phase sintering process and the UC emission intensity was remarkably enhanced by Li⁺ ions, which could be attributed to the lowering of the symmetry of the crystal field around Er³⁺ ions.     

Classification of vegetable oils by high-resolution <Superscript>13</Superscript>C NMR spectroscopy using chromatographically obtained oil fractions

¹³C NMR spectra of oil fractions obtained chromatographically from 109 vegetable oils were obtained and analyzed to evaluate the potential use of those fractions in the classification of vegetable oils and to compare the results with the NMR analysis of complete oils. The oils included the following: virgin olive oils from different cultivars and regions of Europe and north Africa; “lampante” olive, refined olive, refined olive pomace, hazelnut, rapeseed, high-oleic sunflower, corn, grapeseed, soybean, and sunflower oils; and mixtures of virgin olive oils from different geographical origins. Oils were divided into two sets of samples. The training set (98 samples) was employed to select the variables that resulted in significant discrimination among the different oil classes. By using stepwise discriminant analysis, more than 98% of correct validated assignments were obtained; these results were confirmed when applied to the test set (11 blind samples). Results suggest that the use of oil fractions considerably increases the discriminating power of NMR in the analysis of vegetable oils.     

Effect of Ni<Superscript>2+</Superscript>, V<Superscript>4+</Superscript> and Mo<Superscript>6+</Superscript> concentration on iron oxidation by <Emphasis Type="Italic">Acidithiobacillus ferrooxidans</Emphasis>

The ferrous oxidation ability of Acidithiobacillus ferrooxidans was studied in the presence of Ni²⁺, V⁴⁺ and Mo⁶⁺ in 9 K media in order to implement the culture in the bioleaching of spent catalyst. The rate of iron oxidation decreased with increasing concentration of metal ions, but the rate of inhibition was metal-ion dependent. The tolerance limit was critical at a concentration of 25 g/L Ni²⁺, 5 g/L V⁴⁺ and 0.03 g/L Mo⁶⁺. The growth rate of microorganisms was negligible at concentrations of 6 g/L V⁴⁺ and 0.04 g/L Mo⁶⁺. Levels and degree of toxicity of these ions have been quantified in terms of a toxicity index (TI). The toxicity order of metal ions was found to be Mo⁶⁺>V⁴⁺>Ni²⁺. The significance and relevance of multi-metal ion tolerance in Acidithiobacillus ferrooxidans has been highlighted with respect to bioleaching of spent refinery catalyst.     

Oxygen Isotope (<Superscript>18</Superscript>O<Subscript>2</Subscript>) Evidence on the Role of Oxygen in the Plasma-Driven Catalysis of VOC Oxidation

Abstract  

This paper reports isotopic evidence on nonthermal plasma-induced fixation of gas-phase oxygen on the surface of several catalysts such as TiO₂, Ag/TiO₂, Ag/γ-Al₂O₃ and Ag/MS-13X at atmospheric-pressure. On-line mass spectrometric analysis and stoichiometric comparison of reactants and products revealed that the fixed surface oxygen can be activated by nonthermal plasma. The fixed ¹⁸O by nonthermal plasma survived for a certain period of time (about 30 min), and involved in the formation of isotope-exchanged oxygen (¹⁸O¹⁶O) and isotope containing CO _x (CO and CO₂).     

Quantification of soybean oil ethanolysis with <Superscript>1</Superscript>H NMR

In this study, proton NMR spectroscopy (200 MHz) was used for quantifying the content of ethyl esters in known mixtures of soybean oil and ethyl soyate (biodiesel). For this purpose, the peak areas of ester ethoxy and glycerol methylenic peaks in the region of 4.05–4.40 ppm were measured and a calibration plot of the respective peak areas vs. the known composition of the oil/ethyl ester mixtures was used. The transesterification values determined in this way were compared with viscosity and total glycerol determinations and a good correlation was obtained. Therefore, for routine analysis, the conversion (in %) of oil to ethyl esters was determined. The methodology presented in this work proved to be quicker and simpler than others reported in the literature, such as GC and/or HPLC.     

Hydrothermal synthesis of zeolite L in a Na<Superscript>+</Superscript>/K<Superscript>+</Superscript> mixed alkali system

Zeolite L was prepared from the substrate system of Na₂O-K₂O-Al₂O₃-SiO₂-H₂O at temperatures of 373–443 K by hydrothermal crystallization. The influence of various synthesis parameters such as the concentration ratios of the components, starting raw materials, synthesis temperature, gel aging, and stirring on the crystallization was investigated. Investigations revealed that the crystallinity of zeolite L crystals depends on molar ratios of the components such as SiO₂/Al₂O₃, (K₂O+Na₂O)/SiO₂, Na₂O/(K₂O+Na₂O), and H₂O/(K₂O+Na₂O). Pure and highly crystalline zeolite L could be obtained from a gel with the molar composition 5.4K₂O–5.7Na₂O-Al₂O₃-30SiO₂-500H₂O after 24 h at 443 K. It was found that the silica source affected the crystal size of zeolite L, and as the synthesis temperature increased, the average crystal size became larger. The crystal size could be decreased significantly by stirring the gel or subjecting the substrate mixture to an aging treatment at room temperature prior to the hydrothermal treatment. Thermal stability of the zeolite L crystals obtained was also briefly investigated.     

<Superscript>1</Superscript>H- and <Superscript>13</Superscript>C-NMR Characterization of the Molecular Components of the Lipid Fraction of Pecorino Sardo Cheese

In this work the molecular fatty components of Pecorino Sardo Protected Designation of Origin (PS PDO) cheese were characterized through an exhaustive investigation of the ¹H- and ¹³C-NMR spectra of the extracted lipids. Several fatty acids (FA), such as long chain saturated, oleic, linoleic, linolenic, butyric, capric, caprylic, caproic, trans vaccenic, conjugated linoleic acid (cis9, trans11–18:2), and caproleic (9–10:1) were unambiguously detected. The positional isomery of some acyl groups in the glycerol backbone of triacylglycerols (TAG) was assessed. Furthermore, the NMR signals belonging to sn-1,2/2,3, sn-1,3 diacylglycerols (DAG), and free fatty acids (FFA) were analysed as a measure of lipolytic processes on cheese. Lastly, ¹H-NMR resonances of saturated aldehydes and hydroperoxides were detected, their very low intensity indicating that the lipid oxidation process can be considered to be of minor relevance in Pecorino Sardo cheese.     

Hydrogen filter press electrolyser modelled by coupling Fluent<Superscript><Emphasis Type="Bold">®</Emphasis></Superscript> and Flux Expert<Superscript><Emphasis Type="Bold">®</Emphasis></Superscript> codes

Mass production of hydrogen is a major issue for the coming decades particularly to decrease greenhouse gas production. The development of fourth-generation high-temperature nuclear reactors has led to renewed interest for hydrogen production. In France, the CEA is investigating new processes using nuclear reactors, such as the Westinghouse hybrid cycle. A recent study was devoted to electrical modeling of the hydrogen electrolyzer, which is the key unit of this process. In this electrochemical reactor, hydrogen is reduced at the cathode and SO₂ is oxidized at the anode with the advantage of a very low voltage cell. This paper describes an improved model coupling the electrical and thermal phenomena with hydrodynamics in the electrolyzer, designed for a priori computational optimization of our future pilot cell. The hydrogen electrolyzer chosen here is a filter press design comprising a stack of identical cathode and anode compartments separated by a membrane. In a complex reactor of this type the main coupled physical phenomena involved are forced convection of the electrolyte flows, the plume of evolving hydrogen bubbles that modifies the local electrolyte conductivity, and all the irreversible processes that contribute to local overheating (Joule effect, overpotentials, etc.). The secondary current distribution was modeled with a commercial FEM code, Flux Expert^®, which was customized with specific finite interfacial elements capable of describing the potential discontinuity associated with the electrochemical overpotential. Since the finite element method is not capable of properly describing the complex two-phase flows in the cathode compartment, the Fluent^® CFD code was used for thermohydraulic computations. In this way each physical phenomenon was modeled using the best numerical method. The coupling implements an iterative process in which each code computes the physical data it has to transmit to the other one: the two-phase thermohydraulic problem is solved by Fluent^® using the Flux-Expert^® current density and heat sources; the secondary distribution and heat losses are solved by Flux-Expert^® using the Fluent^® temperature field and flow velocities. A set of dedicated library routines was developed for process initiation, message passing, and synchronization of the two codes. The first results obtained with the two coupled commercial codes give realistic distributions for the electrical current density, gas fraction, and velocity in the electrolyzer. This approach allows us to optimize the design of a future experimental device.     

Preparation and characterization of layered silicate magadiite intercalated by Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> for antibacterial behavior

The purpose of this work is the synthesis of two series of layered silicate materials with different ratios (10, 30, 50, 80 and 100) of Cu(NO₃)₂, or Zn(NO₃)₂ by ion-exchange method. Several analysis techniques have been used such as X-ray diffraction, energy dispersive X-ray spectroscopy, thermogravimetric analysis, scanning electron microscope and Fourier transform infrared spectroscopy. The results revealed that ion-exchange method of copper and zinc with different ratios did not affect the structure of Na-magadiite. The gap between the theoretical and experimental ion-exchange are in agreement. Antibacterial activity test against Escherichia coli, Rhizobium sp. and Staphylococcus demonstrate that when ratio was (30, 50, 80 and 100) the antibacterial activity of the layered silicate materials showed high antibacterial activity.     

Controlled Synthesis of BaYF<Subscript>5</Subscript>:Er<Superscript>3+</Superscript>, Yb<Superscript>3+</Superscript> with Different Morphology for the Enhancement of Upconversion Luminescence

In this work, Er³⁺/Yb³⁺-codoped BaYF₅ with different sizes and shapes have been synthesized by a simple solvothermal method. By changing the fluoride source, pH value, solvent, surfactants, Yb³⁺ concentration, temperature, and reaction time, the optimum synthetic conditions of BaYF₅:Er³⁺, Yb³⁺ were found to improve the upconversion luminescent properties. It is found that the emission intensity of green and red light is enhanced for several times by the way of using NaBF₄ as a fluoride source with the comparison of NH₄F and NaF. Moreover, the effects of different surfactants are not the same. Adding 5% polyetherimide (PEI) as surfactant can also improve the upconversion emission. On the contrary, when sodium citrate (CIT) as another surfactant was used to add, the sizes of the nanocrystals were gradually increased and the luminous properties also declined.     

Thermal oxidation of A<Superscript>III</Superscript>B<Superscript>V</Superscript> semiconductors with V<Subscript>2</Subscript>O<Subscript>5</Subscript> nanolayers on the surface

The specific features of the interaction of vanadium(V) oxide nanofilms with the surface of gallium arsenide and indium phosphide semiconductors under thermal oxidation conditions have been considered. The kinetics and mechanism of thermal oxidation of GaAs and InP with deposited V₂O₅ layers 15 and 25 nm in thickness have been studied. It has been revealed that vanadium(V) oxide exerts a specific effect on the oxidation of gallium arsenide and indium phosphide as compared to other d-metal oxides. It has been established that the oxidation occurs with the formation of a phase predominantly consisting of indium phosphates or gallium arsenates and intermediate products based on vanadium compounds in different oxidation states. Schemes have been proposed for the development of the oxidation processes with due regard for the chemical nature of vanadium(V) oxide.     

Studies on the electrochemical reduction processes of HTeO<Subscript>2</Subscript><Superscript>+</Superscript> by CV and EIS

Electrochemical characterizations of the underpotential deposition of tellurium on Au substrate were investigated by cyclic voltammetry (CV) in this paper. The results showed that the irreversible underpotential deposition of Te could take place once the Au electrode was immersed into the HTeO₂ ⁺ solution. The redox behaviors of adsorbed HTeO₂ ⁺ were also studied and the results revealed that HTeO₂ ⁺ could only adsorb on Au electrode surface. The kinetics relating to the reduction of adsorbed HTeO₂ ⁺ could be affected by HTeO₂ ⁺ concentration but the charge consumed by the reduction of adsorbed HTeO₂ ⁺ was concentration-independent. Electrochemical impedance spectroscopy (EIS) analyses about the bulk formation process of Te⁰ indicated that during the bulk reduction of HTeO₂ ⁺ to Te⁰, four electrons were not obtained simultaneously in only one electrochemical step, some intermediate products, which need to be further detected and investigated in the future researches, might emerged in the intermediate processes.