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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 324: 124875, 2025 Jan 05.
Article de Anglais | MEDLINE | ID: mdl-39137707

RÉSUMÉ

Lanthanide chelates with dimethyl(phenylsulfonyl)amidophosphate (labeled as HSP) and Lewis base ligands (bpy = 2,2;-bipyridine and phen = 1,10-phenanthroline) of formula Na[Ln(SP)4] (1Ln), [Ln(SP)3bpy] (2Ln); [Ln(SP)3phen] (3Ln) (Ln = Eu3+, Gd3+, Tb3+ and Lu3+) were obtained and characterized by the X-ray, photoluminescence spectroscopy at 293 and 77 K as well as by intrinsic (QLnLn) and overall (QLnL) luminescence quantum yields. These phosphors manifest a very strong emission after excitation in the UV range of the molecular singlet states (S1) and two of them have very high QLnL values (Eu3+ and Tb3+ chelates of the type 2Ln and 3Ln). The dynamics of the excited states are discussed based on the intramolecular energy transfer theory, considering the dipole-dipole, the dipole-multipole and the exchange mechanisms. From the calculated energy transfer rates, a rate equation model was constructed and, thus, the theoretical QLnL can be obtained. A good correlation between the experimentally determined and theoretically calculated QLnL values was achieved, with the triplet state (T1) playing a predominant role in the energy transfer process for Eu3+ compounds, while the sensitization for Tb3+ compounds is dominated by the energy transfer rates from the singlet state (S1).

2.
Foods ; 13(13)2024 Jul 05.
Article de Anglais | MEDLINE | ID: mdl-38998650

RÉSUMÉ

The popularity of the consumption of wellness herbal teas is due to the many health-promoting properties they seem to possess. Modern preparation methods using coffee machines are also popular today. Therefore, the purpose of this research was to evaluate differences in infusions obtained by the traditional method using filters and by espresso coffee machines using pods. In this regard, different herbal materials were selected and purchased in two different types of herbal containers, and the corresponding infusions were analyzed for the contents of total polyphenols and mineral elements. Results showed that filter infusions had higher polyphenol and mineral contents than pod infusions, excluding Cd and Pb. For each of the plant materials used, differences due to the method of infusion preparation are highlighted. From a qualitative point of view, both methods of infusion preparation are valid, but the filter infusion method allows a higher transfer of minerals and polyphenols into the infusion, improving quality. The analyzed infusions can be safely consumed with respect to As, Cd, Pb, and Hg contents. Good amounts of polyphenols and Mn can be obtained by drinking a cup of any of the infusions analyzed, especially the mate infusion obtained by the filter technique, with amounts of 429 mg for polyphenols and 69.27% of the RDA for manganese.

3.
Sci Total Environ ; 905: 166114, 2023 Dec 20.
Article de Anglais | MEDLINE | ID: mdl-37567284

RÉSUMÉ

The ingestion of contaminated tea involves the risk of human exposure to residues of neonicotinoids (NEOs). Nevertheless, there is little empirical research about this topic; to bridge the current knowledge gap, we collected 220 samples of various tea products from four geographical areas in China, including unfermented green tea, semi-fermented white tea and oolong tea, completely fermented black tea, and post-fermented dark tea. A total of six NEOs were detected from the tea leaves and infusions, namely, dinotefuran (DIN), thiamethoxam (THM), clothianidin (CLO), imidacloprid (IMI), acetamiprid (ACE), and thiacloprid (THI). The detection frequencies (DFs) and concentrations of all target NEOs were relatively high across the investigated tea samples, and the DIN, IMI and ACE residues measured in some samples exceeded the maximum residue level (MRL) standards for the European Union. Samples representing the Jiangnan area exhibited greater levels of total target NEOs (∑6NEOs) than samples representing the Jiangbei area (p < 0.001). Moreover, dark tea samples were found to have far higher levels of NEO residues than green (p < 0.001), white (p < 0.05), or oolong (p < 0.001) samples. The health risks associated with exposure to NEO residues via tea were small for both children and adults in terms of acute, chronic, and cumulative dietary exposure risk assessments. The transfer rates (TRs) of NEOs observed in white, black, and dark tea infusions gradually decreased after the third brewing time. As such, it is recommended to only consume tea that has been brewed at least three times. The presented results not only describe the extent of NEO contamination in Chinese tea leaves and infusions, but also provide tea drinking guidelines for consumers.


Sujet(s)
Camellia sinensis , Insecticides , Adulte , Enfant , Humains , Insecticides/analyse , Néonicotinoïdes/analyse , Composés nitrés/analyse , Thé/composition chimique , Camellia sinensis/composition chimique , Chine
4.
Waste Manag ; 165: 27-39, 2023 Jun 15.
Article de Anglais | MEDLINE | ID: mdl-37080015

RÉSUMÉ

The release rates of constituents of potential concern from solidified/stabilized cementitious waste forms are potentially impacted by drying, which, however, is not well understood. This study aimed to identify the impacts of drying on subsequent leaching from Cast Stone as an example of a solidified cementitious waste form. The release fluxes of constituents from monoliths after aging under 100, 68, 40, and 15 % relative humidity for 16, 32, and 48 weeks, respectively, were derived from mass transfer tank leaching tests following EPA Method 1315. A monolithic diffusion model was calibrated based on the leaching test results to simulate the leaching of major and redox-sensitive constituents from monoliths after drying. The reduction in physical retention of constituents (tortuosity-factor) in the unsaturated zone was identified as the primary impact from drying on subsequent leaching. Fluxes of both major (i.e., OH-, Na, K, Ca, Si, and Al) and redox-sensitive constituents (i.e., Tc, Cr, Fe, and S) from monoliths during leaching were well described by the model. The drying-induced reduction of tortuosity-factor and concomitant changes in porewater pH and redox conditions can significantly change the subsequent release fluxes of pH- and redox- sensitive constituents.

5.
ACS Appl Mater Interfaces ; 15(9): 12109-12118, 2023 Mar 08.
Article de Anglais | MEDLINE | ID: mdl-36813758

RÉSUMÉ

The charge transfer between the donor and acceptor determines the photogenerated carrier density in organic solar cells. However, a fundamental understanding regarding the charge transfer at donor/acceptor interfaces with high-density traps has not been fully addressed. Herein, a general correlation between trap densities and charge transfer dynamics is established by adopting a series of high-efficiency organic photovoltaic blends. It is found that the electron transfer rates are reduced with increased trap densities, while the hole transfer rates are independent of trap states. The local charges captured by traps can induce potential barrier formation around recombination centers, leading to the suppression of electron transfer. For the hole transfer process, the thermal energy provides a sufficient driving force, which ensures an efficient transfer rate. As a result, a 17.18% efficiency is obtained for PM6:BTP-eC9-based devices with the lowest interfacial trap densities. This work highlights the importance of interfacial traps in charge transfer processes and proposes an underlying insight into the charge transfer mechanism at nonideal interfaces in organic heterostructures.

6.
Bioresour Technol ; 362: 127845, 2022 Oct.
Article de Anglais | MEDLINE | ID: mdl-36031118

RÉSUMÉ

The practical application of anaerobic ammonium oxidation (anammox) technology was seriously limited by lack of anammox seeding sludge. In this work, a pilot-scale expanded granular sludge bed (EGSB) reactor was used for rapid proliferation of anaerobic ammonium oxidizing bacteria (AnAOB) using anammox-hydroxyapatite (anammox-HAP) technology. The excellent settleability of anammox-HAP granular sludge (with an excellent settling velocity of 395 m/h) supported the up-flow velocity of 9.6 m/h with recirculation ratio of 19. A high nitrogen loading rate (NLR) of 26.4 g N/L/d was achieved in the pilot-scale reactor, with a cell yield of 0.23 g VSS/g NH4+-N. The high recirculation ratio and up-flow velocity brought about the efficient mass transfer for anammox, eliminating free ammonia inhibition, resulting in the high NLR and cell yield. Results of microbial community revealed that the relative abundance of unclassified Brocadiaceae increased from 18.55% to 82.80%, illustrating the rapid proliferation of AnAOB.


Sujet(s)
Composés d'ammonium , Eaux d'égout , Oxydation anaérobie de l'ammonium , Anaérobiose , Bactéries anaérobies , Bioréacteurs/microbiologie , Prolifération cellulaire , Durapatite , Azote , Oxydoréduction , Eaux d'égout/microbiologie
7.
Micromachines (Basel) ; 12(11)2021 Oct 23.
Article de Anglais | MEDLINE | ID: mdl-34832714

RÉSUMÉ

Engineers, scientists and mathematicians are greatly concerned about the thermal stability/instability of any physical system. Current contemplation discusses the role of the Soret and Dufour effects in hydro-magnetized Carreau-Yasuda liquid passed over a permeable stretched surface. Several important effects were considered while modelling the thermal transport, including Joule heating, viscous dissipation, and heat generation/absorption. Mass transportation is presented in the presence of a chemical reaction. Different nanoparticle types were mixed in the Carreau-Yasuda liquid in order to study thermal performance. Initially, governing laws were modelled in the form of PDEs. Suitable transformation was engaged for conversion into ODEs and then the resulting ODEs were handled via FEM (Finite Element Method). Grid independent analysis was performed to determine the effectiveness of the chosen methodology. Several important physical effects were explored by augmenting the values of the influential parameters. Heat and mass transfer rates were computed against different parameters and discussed in detail.

8.
Front Neurorobot ; 14: 583641, 2020.
Article de Anglais | MEDLINE | ID: mdl-33328950

RÉSUMÉ

Brain-computer interface (BCI) for robotic arm control has been studied to improve the life quality of people with severe motor disabilities. There are still challenges for robotic arm control in accomplishing a complex task with a series of actions. An efficient switch and a timely cancel command are helpful in the application of robotic arm. Based on the above, we proposed an asynchronous hybrid BCI in this study. The basic control of a robotic arm with six degrees of freedom was a steady-state visual evoked potential (SSVEP) based BCI with fifteen target classes. We designed an EOG-based switch which used a triple blink to either activate or deactivate the flash of SSVEP-based BCI. Stopping flash in the idle state can help to reduce visual fatigue and false activation rate (FAR). Additionally, users were allowed to cancel the current command simply by a wink in the feedback phase to avoid executing the incorrect command. Fifteen subjects participated and completed the experiments. The cue-based experiment obtained an average accuracy of 92.09%, and the information transfer rates (ITR) resulted in 35.98 bits/min. The mean FAR of the switch was 0.01/min. Furthermore, all subjects succeeded in asynchronously operating the robotic arm to grasp, lift, and move a target object from the initial position to a specific location. The results indicated the feasibility of the combination of EOG and SSVEP signals and the flexibility of EOG signal in BCI to complete a complicated task of robotic arm control.

9.
Bioprocess Biosyst Eng ; 43(8): 1469-1478, 2020 Aug.
Article de Anglais | MEDLINE | ID: mdl-32266468

RÉSUMÉ

In the present study, the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by Azotobacter vinelandii was evaluated in shake flasks and bioreactors, utilizing different precursors and oxygen transfer rates (OTRs). In shake flask cultures, the highest PHBV yield from sucrose (0.16 g g-1) and 3-hydroxyvalerate (3HV) fraction in the PHA chain (27.4 mol%) were obtained with valerate (1.0 g L-1). In the bioreactor, the cultures were grown under oxygen-limited conditions, and the maximum OTR (OTRmax) was varied by adjusting the agitation rate. In the cultures grown at low OTRmax (4.3 mmol L-1 h-1), the intracellular content of PHBV (73% w w-1) was improved, whereas a maximum 3HV fraction (35 mol %) was obtained when a higher OTRmax (17.2 mmol L-1 h-1, to 600 rpm) was employed. The findings obtained suggest that the PHBV production and the content of 3HV incorporated into the polymer were affected by the OTR. Based on the evidence, it is possible to produce PHBV with a different composition by varying the OTR of the culture; thus, the approach in this study could be used to scale up PHBV production.


Sujet(s)
Azotobacter vinelandii/croissance et développement , Techniques de culture cellulaire en batch , Bioréacteurs , Polyesters/métabolisme
10.
Lipids Health Dis ; 18(1): 185, 2019 Oct 25.
Article de Anglais | MEDLINE | ID: mdl-31653257

RÉSUMÉ

BACKGROUND: Cholesterol is an essential component in human development. In fetuses affected by intrauterine growth restriction (IUGR), fetal blood cholesterol levels are low. Whether this is the result of a reduced materno-fetal cholesterol transport, or due to low fetal de novo synthesis rates, remains a matter of debate. By analyzing cholesterol interbolites and plant sterols we aimed at deeper insights into transplacental cholesterol transport and fetal cholesterol handling in IUGR with potential targets for future therapy. We hypothesized that placental insufficiency results in a diminished cholesterol supply to the fetus. METHODS: Venous umbilical cord sera were sampled post-partum from fetuses delivered between 24 weeks of gestation and at full term. IUGR fetuses were matched to 49 adequate-for-age delivered preterm and term neonates (CTRL) according to gestational age at delivery. Cholesterol was measured by gas chromatography-flame ionization detection using 5a-cholestane as internal standard. Cholesterol precursors and synthesis markers, such as lanosterol, lathosterol, and desmosterol, the absorption markers, 5α-cholestanol and plant sterols, such as campesterol and sitosterol, as well as enzymatically oxidized cholesterol metabolites (oxysterols), such as 24S- or 27-hydroxycholesterol, were analyzed by gas chromatography-mass spectrometry, using epicoprostanol as internal standard for the non-cholesterol sterols and deuterium labeled oxysterols for 24S- and 27-hydroxycholesterol. RESULTS: Mean cholesterol levels were 25% lower in IUGR compared with CTRL (p < 0.0001). Lanosterol and lathosterol to cholesterol ratios were similar in IUGR and CTRL. In relation to cholesterol mean, desmosterol, 24S-hydroxycholesterol, and 27-hydroxycholesterol levels were higher by 30.0, 39.1 and 60.7%, respectively, in IUGR compared to CTRL (p < 0.0001). Equally, 5α-cholestanol, campesterol, and ß-sitosterol to cholesterol ratios were higher in IUGR than in CTRL (17.2%, p < 0.004; 33.5%, p < 0.002; 29.3%, p < 0.021). CONCLUSIONS: Cholesterol deficiency in IUGR is the result of diminished fetal de novo synthesis rates rather than diminished maternal supply. However, increased oxysterol- and phytosterol to cholesterol ratios suggest a lower sterol elimination rate. This is likely caused by a restricted hepatobiliary function. Understanding the fetal cholesterol metabolism is important, not only for neonatal nutrition, but also for the development of strategies to reduce the known risk of future cardiovascular diseases in the IUGR fetus.


Sujet(s)
Sang foetal/métabolisme , Retard de croissance intra-utérin/sang , Adulte , Cholestérol/analogues et dérivés , Cholestérol/sang , Femelle , Chromatographie gazeuse-spectrométrie de masse , Humains , Hydroxycholestérols/sang , Nouveau-né , Phytostérols/sang , Placenta/métabolisme , Grossesse , Sitostérol/sang
11.
BMC Bioinformatics ; 20(1): 470, 2019 Sep 14.
Article de Anglais | MEDLINE | ID: mdl-31521111

RÉSUMÉ

BACKGROUND: Neurogenesis in the murine cerebral cortex involves the coordinated divisions of two main types of progenitor cells, whose numbers, division modes and cell cycle durations set up the final neuronal output. To understand the respective roles of these factors in the neurogenesis process, we combine experimental in vivo studies with mathematical modeling and numerical simulations of the dynamics of neural progenitor cells. A special focus is put on the population of intermediate progenitors (IPs), a transit amplifying progenitor type critically involved in the size of the final neuron pool. RESULTS: A multiscale formalism describing IP dynamics allows one to track the progression of cells along the subsequent phases of the cell cycle, as well as the temporal evolution of the different cell numbers. Our model takes into account the dividing apical progenitors (AP) engaged into neurogenesis, both neurogenic and proliferative IPs, and the newborn neurons. The transfer rates from one population to another are subject to the mode of division (proliferative, or neurogenic) and may be time-varying. The model outputs are successfully fitted to experimental cell numbers from mouse embryos at different stages of cortical development, taking into account IPs and neurons, in order to adjust the numerical parameters. We provide additional information on cell kinetics, such as the mitotic and S phase indexes, and neurogenic fraction. CONCLUSIONS: Applying the model to a mouse mutant for Ftm/Rpgrip1l, a gene involved in human ciliopathies with severe brain abnormalities, reveals a shortening of the neurogenic period associated with an increased influx of newborn IPs from apical progenitors at mid-neurogenesis. Our model can be used to study other mouse mutants with cortical neurogenesis defects and can be adapted to study the importance of progenitor dynamics in cortical evolution and human diseases.


Sujet(s)
Cortex cérébral/croissance et développement , Modèles biologiques , Neurogenèse , Animaux , Cycle cellulaire , Division cellulaire , Cortex cérébral/physiopathologie , Protéines du cytosquelette , Modèles animaux de maladie humaine , Humains , Souris , Mutation , Cellules souches neurales/physiologie , Neurones/physiologie , Protéines/génétique
12.
Regul Toxicol Pharmacol ; 104: 163-199, 2019 Jun.
Article de Anglais | MEDLINE | ID: mdl-30858113

RÉSUMÉ

This publication is part of a series of three publications and describes the non-clinical assessment performed to fulfill the regulatory requirement per Art. 6 (2) of the EU Tobacco Products Directive 2014/40/EU under which Member States shall require manufacturers and importers of cigarettes and Roll Your Own tobacco containing an additive that is included in the priority list established by Commission Implementing Decision (EU) 2016/787 to carry out comprehensive studies (European Comission, 2016). This publication contains the results of a literature search, comprehensive smoke chemistry, additive transfer, and in vitro toxicity studies for the 13 priority additives (carob bean extract, cocoa powder, fenugreek extract, fig juice concentrate, geraniol, glycerol, guaiacol, guar gum, liquorice extract powder, maltol, l-menthol (synthetic), propylene glycol, and sorbitol) commissioned by the members of the Priority Additives Tobacco Consortium to independent Contract Research Organizations. Comparisons of the 39 World Health Organisation smoke emissions in smoke from cigarettes with and without priority additives identified some differences that, with few exceptions, were minor and well within the inherent variability of the analytical method observed for the 3R4F monitor cigarette. Most differences were not statistically significant and did not show consistent additive-related increases or decreases. However, test cigarettes with guar gum showed a statistically significant, additive-related increase in formaldehyde and cadmium; test cigarettes with sorbitol showed a statistically significant, additive-related increase in formaldehyde and acrolein; test cigarettes with glycerol showed a statistically significant, additive-related decrease in phenols, benzo[a]pyrene and N-nitrosoanabasine; and test cigarettes with propylene glycol showed a statistically significant, additive-related decrease in phenol and m + p-cresols. These changes were not observed when the additives were tested as a mixture. None of the increases or decreases in smoke chemistry translated into changes in the in vitro toxicity. Comparisons of the in vitro toxicity of smoke from cigarettes with and without priority additives gave some differences that were minor, well within the inherent variability of the assays, not statistically significant, and did not show consistent additive-related increases or decreases. Thus, it can be concluded that the addition of priority additives had no effect on the in vitro toxicity of the cigarette smoke. The results obtained in our studies are consistent with those in scientific literature.


Sujet(s)
Union européenne , Aromatisants/analyse , Aromatisants/normes , Fumée/effets indésirables , Fumée/analyse , Industrie du tabac/législation et jurisprudence , Produits du tabac/analyse , Produits du tabac/normes , Humains
13.
Bioresour Technol ; 256: 195-200, 2018 May.
Article de Anglais | MEDLINE | ID: mdl-29438920

RÉSUMÉ

The aim of this work was to study biologically reduced graphene oxide (RGO) for engineering the surface architecture of the bioelectrodes to improve the performance of Bioelectrochemical System (BES). Gluconobacter roseus mediates the reduction of graphene oxide (GO). The RGO modified bioelectrodes produced a current density of 1 mA/cm2 and 0.69 mA/cm2 with ethanol and glucose as substrates, respectively. The current density of RGO modified electrodes was nearly 10-times higher than the controls. This study, for the first time, reports a new strategy to improve the yield as well as efficiency of the BES by wrapping and wiring the electroactive microorganisms to the electrode surfaces using RGO. This innovative wrapping approach will decrease the loss of electrons in the microbe-electrolyte interfaces as well as increase the electron transfer rates at the microorganism-electrode interfaces.


Sujet(s)
Électrodes , Graphite , Bioréacteurs , Électrochimie , Glucose , Glucose oxidase , Oxydes
14.
China Pharmacy ; (12): 2564-2568, 2017.
Article de Chinois | WPRIM (Pacifique Occidental) | ID: wpr-619857

RÉSUMÉ

OBJECTIVE:To establish a method for simultaneous determination of 18 toxic elements from 10 ingredients of Modified xiaoyao formula and their extracts,and to study transport rates of above elements. METHODS:Microwave digestion-in-ductively coupled plasma mass (ICP-MS) was used to determine above elements. Radio-frequency power was 1.50 kW,atomiza-tion pressure was 720 kPa,sampling depth was 7 mm,plasma gas flow rate was 15.0 L/min,carrier gas flow rate was 1.00 L/min, spray chamber temperature was 2℃,He flow rate was 4.5 mL/min under collision mode,measurement points/peak was 3,data ac-quisition mode was jump mode. RESULTS:The linear ranges of As,Pb,Cu,Hg,Cd,Mo,V,Cr,Mn,Fe,Ni,Zn,Ru,Rh, Pd,Os,Ir,Pt was 0-500.17 ppb(r was 0.9994-09999);LOD was 0.0004-5.3410 ng/g;RSD of repeatability tests was all lower than 5.0%;average recoveries were 82.0%-117.9%(RSD=0.2%-5.7%,n=9). Ru,Rh,Pd,Os,Ir,Pt,Hg had not been detect-ed. The transfer rates of 11 metals in the extracts ranged 1.46%-31.90%. CONCLUSIONS:The method is simple,precise,stable and repeatable,and can be used for simultaneous determination of 18 toxic elements in 10 ingredients of Modified xiaoyao formula and their extracts. The contents of toxic elements are decreased during the preparation of Modified xiaoyao formula extract to guar-antee the safety of drug use to certain extent.

15.
Prehosp Disaster Med ; 31(6): 687-688, 2016 Dec.
Article de Anglais | MEDLINE | ID: mdl-27646490

RÉSUMÉ

Turris SA , Camporese M , Gutman SJ , Lund A . Mass-gathering medicine: risks and patient presentations at a 2-day electronic dance music event - year two. Prehosp Disaster Med. 2016;31(6):687-688.


Sujet(s)
Commémorations et événements particuliers , Danse , Services des urgences médicales/statistiques et données numériques , Comportement collectif , Musique , Adolescent , Adulte , Canada , Enfant , Médecine d'urgence , Femelle , Humains , Mâle , Jeune adulte
16.
J Dairy Sci ; 99(11): 9254-9262, 2016 Nov.
Article de Anglais | MEDLINE | ID: mdl-27568047

RÉSUMÉ

Colostrum formation is thought to occur slowly over an extended period (4wk) prepartum. Furthermore, colostrum formation is highly variable among cows in total volume, IgG1 concentration, and mass obtained at first postpartum milking. Recent work has suggested that a rapid transfer of IgG1 to secretions may occur if animals are milked prepartum. Our objective was to establish the concentration, mass, and mass transfer rates of IgG1 in multiparous Holstein cows (n=11, parity=3.6±1.1) milked prepartum (-74 to -1h) and again around 4h postpartum. Blood concentrations of IgG1 were very low (<1mg/mL) in 7 cows at prepartum milking and did not decline following prepartum milking. Cows showed variability in the capacity to recover total volume, IgG1 concentration, and IgG1 mass. Three groupings of cows were considered based on the time between the 2 milkings (prepartum + 4h postpartum): long-time (-74 to -54h, n=3), medium-time (-25 to -17h, n=4), and short-time (< -13h, n=4) groups. The average rates of transfer of these groups were 1.4±0.8, 3.0±1.3, and 25.1±15.8g/h, respectively. The data indicate that a longer time between prepartum and postpartum milking is not a main factor in IgG1 secretion transfer. Furthermore, because blood concentrations did not change after prepartum milking and the mass of blood plasma IgG1 was not sufficient to account for the mass occurring in postpartum colostrum, a source of IgG1 other than blood circulation appears to be present during colostrogenesis.


Sujet(s)
Colostrum , Lait/métabolisme , Animaux , Bovins , Femelle , Immunoglobuline G , Lactation , Parité , Période du postpartum
17.
ACS Appl Mater Interfaces ; 8(31): 20465-73, 2016 Aug 10.
Article de Anglais | MEDLINE | ID: mdl-27410765

RÉSUMÉ

Electrochemical charge transfer through multilayer thin films of zinc and nickel 5,10,15,20-tetra(4-ethynylphenyl) porphyrin constructed via copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) "click" chemistry was examined. Current rectification toward various outer-sphere redox probes is revealed with increasing numbers of layers, as these films possess insulating properties over the neutral potential range of the porphyrin, then become conductive upon reaching its oxidation potential. Interfacial electron transfer rates of mediator-dye interactions toward [Co(bpy)3](2+), [Co(dmb)3](2+), [Co(NO2-phen)3](2+), [Fe(bpy)3](2+), and ferrocene (Fc), all outer-sphere redox species, were measured by hydrodynamic methods. The ability to modify electroactive films' interfacial electron transfer rates, as well as current rectification toward redox species, has broad applicability in a number of devices, particularly photovoltaics and photogalvanics.

18.
Contrast Media Mol Imaging ; 11(4): 291-8, 2016 07.
Article de Anglais | MEDLINE | ID: mdl-27060676

RÉSUMÉ

Following the injection of hepatobiliary contrast agents, MRI detects all molecules included in a region of interest but cannot estimate true concentrations in sinusoids, interstitium, hepatocytes or bile canaliculi. The aim of the study was to measure true concentrations in hepatocytes and to show how transfer rates across sinusoidal and canalicular membranes generate these concentrations. We perfused livers isolated from normal rats with 200 µM Gd-DTPA and Gd-BOPTA and measured clearances from sinusoids to liver and from hepatocytes to bile canaliculi or back to interstitium. We detected Gd-BOPTA with a gamma probe and determined true concentrations in each liver compartment knowing their liver volumes. No pharmacokinetic modelling was applied. Gd-BOPTA clearance from sinusoids to liver (2.5 ± 0.4 mL/min) was 50 times higher than that of Gd-DTPA (0.05 ± 0.02 mL/min) when portal flow rate was 30 mL/min (p < 0.0001). Gd-BOPTA clearance from sinusoids to liver was always superior to hepatocyte clearance, and hepatocyte Gd-BOPTA concentrations measured by the probe increased over time. Gd-BOPTA concentrations reached 439 ± 83 µM in hepatocytes and 15 × 700 ± 3100 µM in bile canaliculi, while concentrations in sinusoids were 200 µM. Gd-BOPTA true concentrations in hepatocytes depend on the simultaneous clearances from sinusoids to hepatocytes and from hepatocytes to bile canaliculi and back to sinusoids. The study better defines how signal intensities are generated when hepatobiliary contrast agents are injected in clinical imaging. Copyright © 2016 John Wiley & Sons, Ltd.


Sujet(s)
Produits de contraste/analyse , Foie/imagerie diagnostique , Imagerie par résonance magnétique/méthodes , Méglumine/analogues et dérivés , Composés organométalliques/analyse , Animaux , Canalicules biliaires/métabolisme , Voies biliaires , Transport biologique , Vaisseaux capillaires/métabolisme , Produits de contraste/pharmacocinétique , Acide gadopentétique/pharmacocinétique , Hépatocytes/métabolisme , Membranes intracellulaires/métabolisme , Foie/ultrastructure , Méglumine/analyse , Méglumine/pharmacocinétique , Composés organométalliques/pharmacocinétique , Rats
19.
Int J Mol Sci ; 17(3): 337, 2016 Mar 04.
Article de Anglais | MEDLINE | ID: mdl-26959010

RÉSUMÉ

Phenolic compounds are responsible of the nutritional and sensory quality of extra-virgin olive oil (EVOO). The composition of phenolic compounds in EVOO is related to the initial content of phenolic compounds in the olive-fruit tissues and the activity of enzymes acting on these compounds during the industrial process to produce the oil. In this work, the phenolic composition was studied in six major cultivars grown in the same orchard under the same agronomical and environmental conditions in an effort to test the effects of cultivars on phenolic composition in fruits and oils as well as on transfer between matrices. The phenolic fractions were identified and quantified using high-performance liquid chromatography-diode array detector-time-of-flight-mass spectrometry. A total of 33 phenolic compounds were determined in the fruit samples and a total of 20 compounds in their corresponding oils. Qualitative and quantitative differences in phenolic composition were found among cultivars in both matrices, as well as regarding the transfer rate of phenolic compounds from fruits to oil. The results also varied according to the different phenolic groups evaluated, with secoiridoids registering the highest transfer rates from fruits to oils. Moreover, wide-ranging differences have been noticed between cultivars for the transfer rates of secoiridoids (4.36%-65.63% of total transfer rate) and for flavonoids (0.18%-0.67% of total transfer rate). 'Picual' was the cultivar that transferred secoiridoids to oil at the highest rate, whereas 'Changlot Real' was the cultivar that transferred flavonoids at the highest rates instead. Principal-component analysis confirmed a strong genetic effect on the basis of the phenolic profile both in the olive fruits and in the oils.


Sujet(s)
Fruit/composition chimique , Olea/croissance et développement , Huile d'olive/composition chimique , Phénols/composition chimique , Chromatographie en phase liquide à haute performance/méthodes , Flavonoïdes/analyse , Fruit/classification , Fruit/croissance et développement , Iridoïdes/analyse , Spectrométrie de masse/méthodes , Olea/composition chimique , Olea/classification , Analyse en composantes principales
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