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1.
Inorg Chem ; 58(20): 14193-14203, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31584269

RESUMO

Topotactic reduction of the perovskite oxide TbBaCo2O5.5 with CaH2 leads to a new crystalline phase TbBaCo2O4.5, adopting a 2 × 2 × 1 superstructure compared to TbBaCo2O5.5. The structure consists of a corner-shared network of square pyramidal CoO5 and trigonal planar CoO3 units. Magnetic susceptibility and variable temperature neutron diffraction data reveal that TbBaCo2O4.5 adopts a G-type antiferromagnetically ordered structure (TN ∼ 322 K). The ordered moments are consistent with the presence of low-spin Co2+ (S = 1/2) in trigonal-planar coordination and high-spin Co2+ centers in square pyramidal coordination. TbBaCo2O4.5 shows lower conductivity than TbBaCo2O5.5, which is consistent with the p-type conduction behavior. The unique anion vacancy arrangements in TbBaCo2O4.5 further complement the role of A-cations in controlling the oxygen vacancy distribution in LnBaCo2O5+δ series and demonstrate more opportunity to tune the structural and physical properties based on cationic and anionic lattice coupling.

2.
Chem Commun (Camb) ; 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31633144

RESUMO

Transition metal layered double hydroxides (LDHs) have attracted wide public attention as highly promising non-precious metal electrocatalysts. Herein a ternary NiFeZr LDH was reported with excellent OER catalytic activity, benefiting from the rapid charge transfer caused by the synergistic effect of the doping of Zr and three-dimensional nanosheet structures.

3.
Glob Chang Biol ; 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31638295

RESUMO

The world's largest afforestation programs implemented by China made a great contribution to the global "greening up." These programs have received worldwide attention due to its contribution towards achieving the United Nations Sustainable Development Goals. However, emerging studies have suggested that these campaigns, when not properly implemented, resulted in unintended ecological and water security concerns at the regional scale. While mounting evidence shows that afforestation causes substantial reduction in water yield at the watershed scale, process-based studies on how forest plantations alter the partitioning of rainwater and affect water balance components in natural vegetation are still lacking at the plot scale. This lack of science-based data prevents a comprehensive understanding of forest-related ecosystem services such as soil conservation and water supply under climate change. The present study represents the first 'Paired Plot' study of the water balance of afforestation on the Loess Plateau. We investigate the effects of forest structure and environmental factors on the full water cycle in a typical multi-layer plantation forest composed of black locust, one of the most popular tree species for plantations worldwide. We measure the ecohydrological components of a black locust versus natural grassland on adjacent sites. The startling finding of this study is that, contrary to the general belief, the understory - instead of the overstory - was the main water consumer in this plantation. Moreover, there is a strict physiological regulation of forest transpiration. In contrast to grassland, annual seepage under the forest was minor in years with an average rainfall. We conclude that global long-term greening efforts in drylands require careful ecohydrologic evaluation so that green and blue water tradeoffs are properly addressed. This is especially important for reforestation-based watershed land management, that aims at carbon sequestration in mitigating climate change while maintaining regional water security, to be effective on a large scale.

4.
Eur J Med Chem ; 181: 111553, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31369932

RESUMO

A series of new 6-substituted aminocarbonyl benzimidazole derivatives with 1, 4-disubsituted or 1, 5-disubsituted indole moiety and benzoic acid moiety were designed, synthesized and pharmacologically evaluated. Most of the synthesized compounds could bind to the AT1 receptor and decrease blood pressure significantly. Notably, 2e and 1h could obviously decrease MBP in a dose dependent manner. The maximal response lowered 57.9 ±â€¯2.3 mmHg (2e) and 57.6 ±â€¯1.9 mmHg (1h) of MBP at 10 mg/kg after oral administration, and the antihypertensive effect lasted beyond 24 h, which performed better than Losartan (Fig. 1). These results indicate that 2e and 1h are effective and long-lasting anti-hypertension drug candidates and deserve further investigation for therapeutic application.

5.
Oral Dis ; 2019 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-31397928

RESUMO

OBJECTIVE: Epithelial-mesenchymal transition (EMT) is important in the tooth development and tumor invasion. We investigated the effect of interleukin-8 (IL-8) on the EMT process in primary-cultured ameloblastoma tumor cells (AM-P) and ameloblastoma immortalized tumor cells (AM-L) and its underlying mechanism. METHODS: IL-8 levels in ameloblastomas were detected by immunofluorescence staining and ELISA. AM-P cells and AM-L cells were stimulated with IL-8, and EMT transcription factors, total ß-catenin and phosphorylated-ß-catenin (p-ß-catenin) levels were determined by Western blot analysis and immunofluorescence staining. ß-catenin siRNA was used to knockdown ß-catenin expression in AM-P cells and AM-L cells stimulated with IL-8. RESULTS: IL-8 was highly expressed in the solid ameloblastomas. IL-8 promoted the EMT process in ameloblastoma tumor cells in vitro, as evidenced by decreased E-cadherin and increased vimentin, twist and zeb1 levels. IL-8 also increased total ß-catenin and p-ß-catenin expression in ameloblastoma tumor cells, and ß-catenin knockdown partially inhibited the EMT process in tumor cells, as evidenced by increased E-cadherin, and decreased vimentin and zeb1 levels. CONCLUSIONS: IL-8 could promote EMT in ameloblastoma tumor cells by activating ß-catenin and its downstream transcription factor zeb1.

6.
Toxins (Basel) ; 11(6)2019 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-31195636

RESUMO

Fusarium diseases, including corn root rot, sheath rot, stalk rot, and ear rot are frequently occurring in maize producing areas of China. Fusarium stalk rot and ear rot are the most serious diseases and often occur at the same time, but it is unclear whether there is a correlation between Fusarium composition and disease occurrence. This study was conducted to clarify the relationship between the two diseases. A total of 49 corn stalk rot samples were collected from 15 regions of eight provinces in China from 2016 to 2018. The pathogens were isolated and identified separately from stalks, ear stems, and kernels. The contents of the fumonisins (FB1 and FB2) were detected in kernels. The results showed that the main Fusarium species were found in corn kernels, ear stems and stalks at the same time. The results showed that 1201 strains of Fusarium verticillioides, 668 strains of Fusarium oxysporum, 574 strains of Fusarium graminearum species complex (FGSC), 318 strains of Fusarium equiseti, 95 strains of Fusarium proliferatum, and 40 strains of Fusarium subglutinans were isolated from 1470 corn kernels, 245 ear stems, and 1225 stalks randomly selected from 49 samples. The contamination rate of fumonisins in the 49 samples was 57.1% with an average content of 1.9 µg/g, of which four samples exhibited higher levels as set by the European Commission (4.0 µg/g). These results provide a certain association between stalk rot and ear rot and lay a foundation to study the relationships among Fusarium maize diseases.

7.
PLoS One ; 14(5): e0214491, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31091237

RESUMO

Ulva prolifera, a type of marine macroalgae, is the causative species behind green tides mainly in the Yellow Sea and adjacent regions. Nevertheless, it can be used as food or animal feed in South China. The vegetative fragments of U. prolifera are an important seed source for successive green tide blooms. Fragmentation shortens the transition time from the vegetative state to the reproductive state. However, the translation of the algal metabolites during gametogenesis is far from well understood. In this study, the dynamic metabolic profiles of U. prolifera thallus during fragmentation-induced proliferation were investigated using non-targeted metabolomics approach via a series of time course experiments in June 2017. After a 30 min low temperature shock, fragmentation induced a reproductive response of 91.57% of U. prolifera in 48 h, whereas the value was only 21.43% in the control group. A total of 156 chromatographic peaks were detected, and 63 metabolites were significantly changed in U. prolifera during reproduction. Aanlysis of the kinetic metabolic pattern showed that the fragments not only induced the formation of sporangia, but also led to complex metabolite accumulation. During fragmentation-induced proliferation, U. prolifera consumed different sugars at different time points. γ-Aminobutyric acid (GABA), glutamic acid, gallic acid, and malic acid may play important roles in germ cell formation and in the release of U. prolifera, whereas n-hexanol, 2-methyl-3-phenylindole, and 3-indoleacetonitrile may be beneficial for biotic stress resistance. Compared with the control group, in the treatment group, metabolites such as alcohols and organic acids also showed significant difference with the photoperiod at the initial stage of proliferation (before 60 h). In conclusion, changes in the levels of metabolites, including sugars, organic acids, and alcohol with photoperiod may be the strategy adopted by U. prolifera to cope with fragmentation in nature.

8.
Psychol Addict Behav ; 33(4): 360-370, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30985165

RESUMO

Cross-sectional studies have shown that both stressors and personality vulnerability are risk factors for adolescent problematic Internet use (PIU). However, little is known about how both categories of factors in combination may contribute to the longitudinal development of PIU among adolescents. The aims of this study were to document the developmental pattern of PIU among adolescents and to examine how stressful life events and the Big Five personality traits jointly affect the development of PIU. We tested three competing models: the additive, diathesis-stress, and social push models. A total of 1,365 adolescents participated in a 3-year longitudinal study. Hierarchical linear modeling indicated that PIU among adolescents increased over the 3-year period. After controlling for demographics and the Big Five personality traits, stressful life events (a time-varying predictor) were positively correlated with the initial level of, and the rate of change in, PIU. After controlling for demographics and stressful life events, four of the time-invariant Big Five personality dimensions had a significant effect on the initial level of PIU. Low Agreeableness, low Conscientiousness, high Openness, and high Neuroticism were positively associated with high initial PIU. In addition, Extraversion was negatively associated with and Conscientiousness was positively associated with the rate of change in PIU. The interaction effect between the personality and stressors was not significant. Therefore, the data provided support for the additive model, indicating that stressful life events and personality dimensions each make a unique contribution to PIU and that both should be considered in the prevention of adolescent PIU. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Assuntos
Comportamento do Adolescente/psicologia , Comportamento Aditivo/psicologia , Modelos Psicológicos , Personalidade , Estresse Psicológico/psicologia , Adolescente , Feminino , Humanos , Internet , Acontecimentos que Mudam a Vida , Estudos Longitudinais , Masculino
9.
Addict Behav ; 96: 43-49, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31035077

RESUMO

The role of social-environmental factors in adolescent problematic Internet use (PIU) has attracted considerable attention recently. Several studies have documented that peer victimization is positively associated with PIU. However, little is known about "how" (i.e., mediation mechanisms) and "under what conditions" (i.e., moderation mechanisms) peer victimization is associated with adolescent PIU. To contribute to this gap in the knowledge, this study used a large sample of Chinese adolescents (N = 2758; Mage = 13.53 years, SD = 1.06) to examine deviant peer affiliation (DPA) as a mediator and family functioning as a moderator in this relationship. Students completed anonymous questionnaires to measure the main variables. After controlling for important covariates related to PIU, the results indicated that (a) peer victimization was positively associated with PIU, (b) DPA partially mediated the link between peer victimization and PIU, and (c) family functioning moderated the association between peer victimization and DPA. Specifically, for adolescents with better family functioning, the relationship between peer victimization and DPA was weaker. The current research deepens our understanding of "how" and "under what conditions" peer victimization is related to PIU in adolescents.

10.
Sci Rep ; 9(1): 4697, 2019 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-30886244

RESUMO

Tree transpiration (T) is a major water budget component and varies widely due to the integrated effects of many environmental and vegetation factors. This study aimed to separate, quantify, and then integrate the effects of the main individual factors, to improve water use estimation and manage the hydrological impacts of forests. A field study was conducted at 3 plots of larch (Larix principis-rupprechtii) plantation in the semi-humid area of the Liupan Mountains, northwest China. The main influencing factors were the atmospheric evaporative demand expressed by potential evapotranspiration (PET), the soil water availability expressed by volumetric soil moisture (VSM) within the 0-100 cm layer, and the canopy transpiration capacity expressed by forest canopy leaf area index (LAI). The daily stand T was estimated through the up-scaling of sap-flow data from sampled trees. It displayed a high degree of scattering in response to PET, VSM and LAI, with an average of 0.76 mm·day-1 and range of 0.01-1.71 mm·day-1 in the growing season of 2014. Using upper boundary lines of measured data, the response tendency of T to each factor and corresponding function type were determined. The T increases firstly rapidly with rising PET, VSM and LAI, then gradually and tends to be stable when the threshold of PET (3.80 mm·day-1), VSM (0.28 m3·m-3) and LAI (3.7) is reached. The T response follows a quadratic equation for PET and saturated exponential function for VSM and LAI. These individual factor functions were coupled to form a general daily T model which was then fitted using measured data as: T = (0.793PET - 0.078PET2)·(1 - exp(-0.272LAI))·(1 - exp(-9.965VSM)). It can well explain the daily T variation of all 3 plots (R2 = 0.86-0.91), and thus can be used to predict the response of daily T of larch stands to changes in both environmental and canopy conditions.

11.
Medicine (Baltimore) ; 98(9): e14710, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30817612

RESUMO

Vitrectomy combined with internal limiting membrane peeling (ILMP) treats high myopic foveoschisis with good results, but there is a risk of iatrogenic macular holes, which may be reduced by preserving the internal limiting membrane of the central fovea. This study compared complete ILMP with partial ILMP, both combined with 25G vitrectomy, for the treatment of high myopic foveoschisis.Thirty-three cases (33 eyes) of high myopic foveoschisis were retrospectively analyzed. They underwent 25G vitrectomy combined with C3F8 gas filling; Group A (20 patients, 20 eyes) underwent complete ILMP, while Group B (13 patients, 13 eyes) underwent partial ILMP to preserve the internal limiting membrane of the central fovea. Patients were followed up for 6 months and underwent best corrected visual acuity (BCVA), intraocular pressure, diopter, slit lamp microscopy, indirect ophthalmoscope, A-mode and/or B-mode ultrasound, and optical coherence tomography. Surgical complications were recorded.Up to the last follow-up, the BCVA improved and central fovea thickness (CFT) was lower compared with before surgery in both groups (All P < .05). There were no significant differences in BCVA and CFT at each time point between the groups (P > .05). Most of the postoperative retinas of the 2 groups were completely reattached, with disappearance of the macular retinoschisis cavity. Two patients in the Group A and none in the Group B developed a macular hole during follow-up (P = .508).The results did not support the superiority of partial ILMP over complete ILMP in reduced incidence of macular hole. Both methods had a similar curative effect.


Assuntos
Miopia Degenerativa/cirurgia , Vitrectomia/métodos , Adulto , Fatores Etários , Feminino , Fóvea Central/patologia , Humanos , Pressão Intraocular , Masculino , Pessoa de Meia-Idade , Retina/patologia , Fatores Sexuais , Acuidade Visual
13.
Ther Apher Dial ; 23(5): 409-417, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30624012

RESUMO

The aim of this study is to evaluate the safety of low-volume tidal peritoneal dialysis (TPD) and intermittent peritoneal dialysis (IPD) in ESRD patients initiating automated peritoneal dialysis (APD) after an acute catheter insertion. Clinical outcomes of patients who received either TPD or IPD using an APD system were compared in a randomized, open-label, prospective control study in a single-center setting. From May 2011 to May 2013, 49 patients were enrolled and 27 patients received low-volume TPD treatment, whereas 22 patients underwent low-volume IPD right after Tenckhoff catheter insertion. The incidence of complications during the 14-day APD treatment were observed. After APD treatment, all the patients were transferred to continuous ambulatory peritoneal dialysis and followed up for 2 years. The IPD group demonstrated a significantly higher incidence of catheter-related complications (omental wrapping 27.3% vs. 0% and suction pain 18.2% vs. 0%) than the TPD group after adjusting for age, gender, baseline diabetes, systolic blood pressure, BMI, and the experience of the operators. However, the short duration of APD treatment with either IPD or TPD mode did not affect the long-time technical survival. In patients immediately after catheter insertion, low-volume TPD mode demonstrated a lower incidence of catheter-related complications compared to IPD. Although our results provided evidence that TPD is a preferable APD mode for this specific population, definitive conclusions about TPD benefit cannot be made, owing to early termination of the trial.

14.
Chemistry ; 25(18): 4767-4774, 2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30633386

RESUMO

An original, halide-free non-hydrolytic sol-gel route to mesoporous anatase TiO2 with hierarchical porosity and high specific surface area is reported. This route is based on the reaction at 200 °C of titanium(IV) isopropoxide with acetic anhydride, in the absence of a catalyst or solvent. NMR spectroscopic studies indicate that this method provides an efficient, truly non-hydrolytic and aprotic route to TiO2 . Formation of the oxide involves successive acetoxylation and condensation reactions, both with ester elimination. The resulting TiO2 materials were nanocrystalline, even before calcination. Small (about 10 nm) anatase nanocrystals spontaneously aggregated to form mesoporous micron-sized particles with high specific surface area (240 m2 g-1 before calcination). Evaluation of the lithium storage performances shows a high reversible specific capacity, particularly for the non-calcined sample with the highest specific surface area favouring pseudo-capacitive storage: 253 mAh g-1 at 0.1 C and 218 mAh g-1 at 1 C (C=336 mA g-1 ). This sample also shows good cyclability (92 % retention after 200 cycles at 336 mA g-1 ) with a high coulombic efficiency (99.8 %). Synthesis in the presence of a solvent (toluene or squalane) offers the possibility to tune the morphology and texture of the TiO2 nanomaterials.

15.
Arch Gerontol Geriatr ; 80: 53-57, 2019 Jan - Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30366226

RESUMO

AIMS: To comparatively analyze the usefulness of serum procalcitonin (PCT), C-reactive protein (CRP), soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) and Clinical Pulmonary Infection Score (CPIS) for assessing the severity and prognosis of community-acquired pneumonia (CAP) in the elderly. METHODS: A total of 214 elderly patients with CAP and 106 healthy persons were enrolled in this prospective study. On the admission day, serum inflammatory markers, including CRP, PCT, sTREM-1, and CPIS were analyzed. By severity, the CAP patients were subdivided into non-severe CAP group and severe CAP group. By outcome, the patients were classified into survival group and death group. The efficiency of three inflammatory markers and CPIS on predicting prognosis of pneumonia patients was then analyzed. RESULTS: The serum inflammatory markers and CPIS were significantly higher in CAP patients than in healthy controls. These biomarkers and CPIS were significantly higher in patients with severe CAP than in patients with non-severe CAP. Compared with patients who would survive, these markers and CPIS were significantly higher in patients who would die. Receiver operating characteristic curve analysis showed that the area under the curve and sensitivity were higher for serum sTREM-1 than for other indicators, while the specificity of serum PCT was the highest. CONCLUSIONS: Serum CRP, PCT, and sTREM-1 and CPIS determined on the admission day are effective indicators to evaluate the severity and prognosis of CAP in the elderly. The prognostic value of PCT and sTREM-1 is better than that of CRP and CPIS.


Assuntos
Biomarcadores/sangue , Proteína C-Reativa/análise , Infecções Comunitárias Adquiridas/diagnóstico , Pneumonia/diagnóstico , Pró-Calcitonina/sangue , Índice de Gravidade de Doença , Receptor Gatilho 1 Expresso em Células Mieloides/sangue , Idoso , Idoso de 80 Anos ou mais , Infecções Comunitárias Adquiridas/sangue , Feminino , Humanos , Masculino , Pneumonia/sangue , Prognóstico , Estudos Prospectivos
16.
Anal Chem ; 2018 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-30523683

RESUMO

Recent advances in analysis of proteins have increased the demand for more efficient techniques to separate intact proteins. Enhanced-fluidity liquid chromatography (EFLC) involves the addition of liquefied CO2 to conventional liquid mobile phases. The addition of liquefied CO2 increases diffusivity and decreases viscosity, which inherently leads to a more efficient separation. Herein, EFLC is applied to hydrophobic interaction chromatography (HIC) stationary phases for the first time to study the impact of liquefied CO2 to the chromatographic behavior of proteins. The effects of liquefied CO2 on chromatographic properties, charge state distributions (CSD) and ionization efficiencies were evaluated EFLC offered improved chromatographic performance compared to conventional liquid chromatography (LC) methods including a shorter analysis time, better peak shapes, and higher plate numbers. The addition of liquefied CO2 to the mobile phase provided an ESI-friendly and "supercharging" reagent without sacrificing chromatographic performance, which can be used to improve peptide and protein identification in large-scale application.

17.
J Insect Sci ; 18(6)2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30535417

RESUMO

Wing polymorphism is common in a wide variety of insect species. However, few studies have reported on adaptations in the wing polymorphism of insects at molecular level, in particular for males. Thus, the adaptive mechanisms need to be explored. The remarkable variability in wing morphs of insects is well represented in the water striders (Hemiptera: Gerridae). Within this family, Gigantometra gigas (China, 1925), the largest water strider known worldwide, displays macropterous and apterous males. In the present study, we used de novo transcriptome assembly to obtain gene expression information and compared body and leg-component lengths of adult males in different wing morphs. The analyses in both gene expression and phenotype levels were used for exploring the adaptive mechanism in wing polymorphism of G. gigas. After checking, a series of highly expressed structural genes were found in macropterous morphs, which were related to the maintenance of flight muscles and the enhancement of flight capacity, whereas in the apterous morphs, the imaginal morphogenesis protein-Late 2 (Imp-L2), which might inhibit wing development and increase the body size of insects, was still highly expressed in the adult stage. Moreover, body and leg-component lengths were significantly larger in apterous than in macropterous morphs. The larger size of the apterous morphs and the differences in highly expressed genes between the two wing morphs consistently demonstrate the adaptive significance of wing polymorphism in G. gigas. These results shed light on the future loss-of-function research of wing polymorphism in G. gigas.


Assuntos
Heterópteros/anatomia & histologia , Heterópteros/genética , Proteínas de Insetos/genética , Transcriptoma , Animais , China , Masculino , Asas de Animais/anatomia & histologia , Asas de Animais/fisiologia
18.
Molecules ; 23(11)2018 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-30453620

RESUMO

The development of powerful synthetic methodologies is paramount in the design of advanced nanostructured materials. Owing to its remarkable properties and low cost, nanostructured TiO2 is widely investigated for applications such as photocatalysis, energy conversion or energy storage. In this article we report the synthesis of mesoporous TiO2 by three different non-hydrolytic sol-gel routes, and we investigate the influence of the synthetic route and of the presence and nature of the solvent on the structure, texture and morphology of the materials. The first route is the well-known ether route, based on the reaction of TiCl4 with iPr2O. The second and third routes, which have not been previously described for the synthesis of mesoporous TiO2, involve the reaction of Ti(OiPr)4 with stoichiometric amounts of acetophenone and benzoic anhydride, respectively. All materials are characterized by XRD, N2 physisorption and SEM. By playing with the non-hydrolytic route used and the reaction conditions (presence of a solvent, nature of the solvent, calcination), it is possible to tune the morphology and texture of the TiO2. Depending on the reaction conditions, a large variety of mesoporous TiO2 nanostructures could be obtained, resulting from the spontaneous aggregation of TiO2 nanoparticles, either rounded nanoparticles, platelets or nanorods. These nanoparticle networks exhibited a specific surface area up to 250 m² g-1 before calcination, or up to 110 m² g-1 after calcination.

19.
Chem Sci ; 9(35): 7104-7114, 2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30310631

RESUMO

Microwave-assisted functionalization of the layered Aurivillius phase Bi2SrTa2O9 by alcohols is thoroughly investigated. The grafting of linear aliphatic and bulky alcohols is studied as a function of the starting material, underlining the importance of the prefunctionalization of the layered perovskite, for instance by butylamine. In addition, the functionalization by α,ω-alkanediols is explored. α,ω-alkanediols bearing long alkyl chains (n C > 3) adopt an unprecedented pillaring arrangement, whereas 1,3-propanediol and ethyleneglycol adopt a bilayer arrangement, only one out of the two hydroxyl groups being coordinated. Finally, the reactivities of alcohols and amines towards insertion are compared: the preferential reactivity of the two functional groups appears to be strongly dependent of the reaction conditions, and especially of the water content. This study is further extended to the case of amino-alcohol insertion. In this case, the amine group is preferentially bound, but it is possible to control the grafting of the alcohol moiety, thus going from a bilayer arrangement to a pillaring one. This work is of particular importance to be able to functionalize easily and rapidly layered oxides with elaborated molecules, bearing several different potentially reactive groups.

20.
ACS Appl Mater Interfaces ; 10(43): 37067-37078, 2018 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-30303009

RESUMO

A novel hybrid electrocatalyst of Co2B and Co nanoparticles immobilized on N-B-doped carbon derived from nano-B4C (Co2B/Co/N-B-C/B4C) is in situ synthesized by pyrolysis of nano-B4C supporting Co(OH)2 nanoparticles with melamine. The Co2B and Co nanoparticles are formed and anchored on the generated N and B codoped carbon and undecomposed B4C. The hybrid exhibits remarkable catalytic performances toward the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR)-a very small potential of 1.53 V at 10 mA cm-2 for the OER and a high catalytic kinetics and superior durability for the ORR-which are superior to the RuO2 and Pt/C catalyst, respectively. Most impressively, the hybrid delivers a very small potential gap of 710 mV, which is lower than those of most bifunctional electrocatalysts reported. In addition, the hybrid also shows a satisfying hydrogen evolution reaction performance offering a small overpotential of 220 mV at 10 mA cm-2 and wonderful stability. The excellent trifunctional catalytic performances issue from synergetic effects of Co2B, metal Co, Co/N-doped carbon, and B self-doped carbon coexisting in the hybrid with good interaction mutually. This work provides a new-type efficient multifunctional catalyst for regenerative fuel cell and overall water-splitting technologies.

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