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1.
J Am Chem Soc ; 146(26): 17600-17605, 2024 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-38869355

RESUMO

Coupling two magnetic anisotropic lanthanide ions via a direct covalent bond is an effective way to realize high magnetization blocking temperature of single-molecule magnets (SMMs) by suppressing quantum tunneling of magnetization (QTM), whereas so far only single-electron lanthanide-lanthanide bonds with relatively large bond distances are stabilized in which coupling between lanthanide and the single electron dominates over weak direct 4f-4f coupling. Herein, we report for the first time synthesis of short Dy(II)-Dy(II) single bond (3.61 Å) confined inside a carbon cage in the form of an endohedral metallofullerene Dy2@C82. Such a direct Dy(II)-Dy(II) covalent bond renders a strong Dy-Dy antiferromagnetic coupling that effectively quenches QTM at zero magnetic field, thus opening up magnetic hysteresis up to 25 K using a field sweep rate of 25 Oe/s, concomitant with a high 100 s magnetization blocking temperature (TB,100s) of 27.2 K.

2.
Nurs Crit Care ; 2024 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-38763524

RESUMO

BACKGROUND: Although there are many reasons for extubation failure, maintaining negative or lower positive fluid balances 24 hours before extubation may be a key measure for successful extubation. AIM: To assess the predictive value of fluid balance before extubation and its outcome in mechanically ventilated cases in the intensive care unit (ICU). STUDY DESIGN: This retrospective cohort study involved collecting clinical data from patients undergoing mechanical ventilation in Lanzhou general adult ICU from January 2022 to December 2022. Based on extubation outcomes, the patients were divided into a successful extubation group and a failed extubation group. Their fluid balance levels 24 h before extubation were compared with analyse the predictive value of fluid balance on extubation outcomes in patients undergoing mechanical ventilation. RESULTS: In this study, clinical data from 545 patients admitted to a general adult ICU were collected. According to the inclusion and exclusion criteria, 265 (48.6%) patients were included, of which 197 (74.3%) were successfully extubated; extubation was unsuccessful in 68 (25.7%) patients. The total intake and fluid balance levels in patients in the failed extubation group 24 h before extubation were significantly higher than those in the successful extubation group, with a median of 2679.00 (2410.44-3193.50) mL versus 2435.40 (1805.04-2957.00) mL, 831.50 (26.25-1407.94) mL versus 346.00 (-163.00-941.50) mL. Receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off value for predicting extubation outcomes was 497.5 mL (sensitivity 64.7%, specificity 59.4%) for fluid balance 24 h before extubation. The area under the ROC curve was 0.627 (95% confidence interval [CI] 0.547-0.707). Based on the logistic regression model, cumulative fluid balance >497.5 mL 24 h before extubation could predict its outcomes in mechanically ventilated patients in the ICU (OR = 5.591, 95% CI [2.402-13.015], p < .05). CONCLUSIONS: The fluid balance level 24 h before extubation was correlated with the outcome of extubation in mechanically ventilated patients in the ICU. The risk of extubation failure was higher when the fluid balance level was >497.5 mL. RELEVANCE TO CLINICAL PRACTICE: Tracheal intubation is a crucial life support technique for many critically ill patients, and determining the appropriate time for extubation remains a challenge for clinicians. Although there are many reasons for extubation failure, acute pulmonary oedema caused by continuous positive fluid balance and volume overload is one of the main reasons for extubation failure. Therefore, it is very important to study the relationship between fluid balance and extubation outcome to improve the prognosis of patients with invasive mechanical ventilation in ICU.

3.
J Am Chem Soc ; 145(41): 22599-22608, 2023 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-37787921

RESUMO

Metal complexes bearing single-electron metal-metal bonds (SEMBs) exhibit unusual electronic structures evoking strong magnetic coupling, and such bonds can be stabilized in the form of dimetallofullerenes (di-EMFs) in which two metals are confined in a carbon cage. Up to now, only a few di-EMFs containing SEMBs are reported, which are all based on a high-symmetry icosahedral (Ih) C80 cage embedding homonuclear rare-earth bimetals, and a chemical modification of the Ih-C80 cage is required to stabilize the SEMB. Herein, by introducing 3d-block transition metal titanium (Ti) along with 4f-block lanthanum (La) into the carbon cage, we synthesized the first crystallographically characterized SEMB-containing 3d-4f heteronuclear di-EMFs based on pristine fullerene cages. Four novel La-Ti heteronuclear di-EMFs were isolated, namely, LaTi@D3h(5)-C78, LaTi@Ih(7)-C80, LaTi@D5h(6)-C80, and LaTi@C2v(9)-C82, and their molecular structures were unambiguously determined by single-crystal X-ray diffraction. Upon increasing the cage size from C78 to C82, the La-Ti distance decreases from 4.31 to 3.97 Å, affording fine-tuning of the metal-metal bonding and hyperfine coupling, as evidenced by an electron spin resonance (ESR) spectroscopic study. Density functional theory (DFT) calculations confirm the existence of SEMB in all four LaTi@C2n di-EMFs, and the accumulation of electron density between La and Ti atoms shifts gradually from the proximity of the Ti atom inside C78 to the center of the LaTi bimetal inside C82 due to the decrease of the La-Ti distance. The electronic properties of LaTi@C2n heteronuclear dimetallofullerenes differ apparently from their homonuclear La2@C2n counterparts, revealing the peculiarity of heteronuclear dimetallofullerenes with the involvement of 3d-block transition metal Ti.

4.
Angew Chem Int Ed Engl ; 62(24): e202301940, 2023 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-37071485

RESUMO

Despite significant progress in the preparation and characterization of two-dimensional (2D) materials, the synthesis of 2D organic materials remains challenging. Here, we report a novel space-confined polymerization method that enables the large-scale synthesis of 2D sheets of a functional conjugated polymer, namely, poly(3,4-ethylenedioxythiophene) (PEDOT). A key step in this method is the confinement of monomer to the boundaries of ice crystals using micelles. This spatial confinement directs the polymerization to form 2D PEDOT sheets with high crystallinity and controlled morphology. Supercapacitors prepared from the 2D PEDOT sheets exhibit outstanding performance metrics. In aqueous electrolyte, a high areal specific capacitance of 898 mF cm-2 at 0.2 mA cm-2 along with an excellent rate capability is achieved (e.g., capacitance retention of 67.6 % at a 50-fold higher current). Moreover, the 2D PEDOT-based supercapacitors exhibit outstanding cycling stability (capacitance retention of 98.5 % after 30,000 cycles). Device performance is further improved when an organic electrolyte is used.

5.
J Biol Inorg Chem ; 26(1): 123-133, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33449164

RESUMO

LCN2 (Lipocalins) was first identified as iron transporter through associating with its siderophores and also involved in many cancer metastases, but its function is still paradoxical. We questioned that whether LCN2 might also associate exogenous iron chelator as does in inherent way and the association may influence their respective function. To address this issue, we investigated the effect of LCN2 on action of DpdtC (2,2'-dipyridine ketone hydrazone dithiocarbamte), an iron chelator in proliferation and metastasis-related gene expression. The results showed that exogenous LCN2 and DpdtC could inhibit growth of HepG2 cells, while the combination treatment enhanced their inhibitory effect both in proliferation and colony formation. This encouraged us to investigate the effect of the interaction on metastasis-related gene expression. The results revealed that both LCN2 and DpdtC impaired the wound healing of HepG2, but the inhibitory effect of DpdtC was significantly enhanced upon association with LCN2. Undergoing epithelium-mesenchymal transition (EMT) is a crucial step for cancer metastasis, LCN2 and DpdtC had opposite effects on EMT markers, the binding of DpdtC to LCN2 significantly weakened the regulation of it (or its iron chelate) on EMT markers. To insight into the interaction between LCN2 and DpdtC-iron, fluorescence titration and molecular docking were performed to obtain the association constant (~ 104 M-1) and thermodynamic parameters (ΔG = - 26.10 kJ/mol). Importantly this study provided evidence that siderophores-loading state of LCN2 may influence its function, which be helpful for understanding the contradictory role of LCN2 in the metastasis of cancer.


Assuntos
Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Ditiocarb/análogos & derivados , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Quelantes de Ferro/farmacologia , Lipocalina-2/metabolismo , Autofagia/efeitos dos fármacos , Ditiocarb/farmacologia , Ferritinas/metabolismo , Células Hep G2 , Humanos , Hidrazonas/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Tiocarbamatos/farmacologia , Canais de Potencial de Receptor Transitório
6.
J Dent Sci ; 19(1): 626-630, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38303799

RESUMO

The existence of a comorbidity between diabetes mellitus (DM) as well as between thyroid diseases (TD) and oral lichen planus (OLP), respectively, was substantially demonstrated. However, there is not enough attention to the concurrent status of both TD and DM in OLP patients. Herein, this short communication aimed to compare 1) the prevalence of DM when TD was concurrently investigated and that of DM when TD status was ignored; 2) the prevalence of TD when DM was concurrently investigated and that of TD when DM status was ignored in the studies. The pooled prevalence (9.86 %; 95 % confidence intervals [CI], 9.22-10.53 %) of DM when TD was concurrently investigated was significantly higher than that (8.13 %; 95%CI, 8.03-9.12 %) when TD status was not investigated in OLP patients. The pooled prevalence (12.48 %; 95%CI, 11.77-13.22 %) of TD when DM was concurrently investigated was significantly higher than that (10.45 %; 95%CI, 9.52-11.46 %) when DM status was not investigated in OLP patients. Thus, it is logical to presume for the first time that there is possible interplay of DM and TD in OLP occurrence. TD and DM should serve as important confounding factors each other in clinical investigation on OLP and associated comorbidities.

7.
J Dent Sci ; 19(1): 614-619, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38303894

RESUMO

Background/purpose: 4-Nitroquinoline 1-oxide (4NQO)-induced tongue carcinoma and 7,12-dimethlybenz(a)anthracene (DMBA)-induced cheek pouch carcinoma are the most common and classical chemical carcinogen-induced animal models of oral carcinogenesis. The purpose of this study was to provide the research trends and characteristics of 4NQO- and DMBA-induced experimental oral carcinogenesis. Materials and methods: The papers on both 4NQO- and DMBA-induced experimental oral carcinogenesis were published since 1962. All the eligible papers were retrieved on 12 May 2023 from the Scopus database. Results: There were 506 and 349 papers on 4NQO- and DMBA-induced experimental oral carcinogenesis with 10,152 and 6306 citations, respectively. The common distinctive keywords such as rat, tongue neoplasms, drinking water, tumor microenvironment, and cyclooxygenase (COX)-2 were identified in the papers on 4NQO; and the common keywords such as hamster, cheek pouch, lipid peroxidation, glutathione, antioxidants, and topical drug administration were identified in the papers on DMBA. Importantly, 105 and 65 potential chemopreventive agents were identified from the papers on 4NQO and DMBA, respectively. Furthermore, 15 promising agents such as COX-2 inhibitor, curcumin, garlic were researched concurrently in both the two animal models. Conclusion: This study for the first time reports the scientometric characteristics of 4NQO- and DMBA-induced experimental oral carcinogenesis. Importantly, we identify a valuable profile for oral cancer chemopreventive agents, which will aid researchers and investigators in studying oral cancer chemoprevention.

8.
J Evid Based Med ; 17(1): 17-25, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38459781

RESUMO

AIM: This study aims to describe the citation patterns of Cochrane systematic reviews (CSR) in guidelines for managing breast cancer. METHODS: We searched for systematic reviews on breast cancer in The Cochrane Library from the date of inception to November 15, 2023, and identified guidelines that cited them. We described how systematic reviews were cited by the guidelines in each database and each year. Additionally, we presented the relationships between the conclusions of the systematic reviews and guideline recommendations and compared the consistency of the recommendations on the same topic across different guidelines. RESULTS: A total of 64 systematic reviews and 228 guidelines were included in this study. The average number of the 64 systematic reviews cited by the guidelines was 5.91. We found that the guideline recommendations were irrelevant or inconsistent with the conclusions of the systematic reviews in 56 (38.36%) cited entries. We grouped recommendations on the same topic across different guidelines into one group, of which only 5 groups (15.15%) had completely consistent recommendations, and the other 28 groups (84.85%) had inconsistent recommendations. CONCLUSION: The average number of citations for CSR on breast cancer in the guidelines was 5.91. There were also situations in which the guideline recommendations were inconsistent with the conclusions of the included systematic reviews, and recommendations on the same topic across different guidelines were inconsistent.


Assuntos
Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/terapia , Revisões Sistemáticas como Assunto , Bases de Dados Factuais
9.
Acta Crystallogr Sect E Struct Rep Online ; 69(Pt 5): o760, 2013 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-23723906

RESUMO

In the title hydrate, C19H15N3O3·H2O, the three aromatic groups in the quinoline derivative are close to coplanar: the central oxa-diazole fragment makes dihedral angles of 15.7 (2)° with the benzene ring and 5.30 (14)° with the quinoline ring system. In the crystal, the organic mol-ecules are connected with water mol-ecules by pairs of O-H⋯N hydrogen bonds involving the quinoline and oxa-diazole N atoms. The mol-ecules form stacks along the a axis, neighboring mol-ecules within each stack being related by inversion and the shortest distance between the centroids of the oxa-diazole and pyridine rings being 3.500 (2) Å. Mol-ecules from neighboring stacks are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional structure.

10.
Artigo em Inglês | MEDLINE | ID: mdl-24046611

RESUMO

In the title compound, C18H13N3O2·H2O, the oxa-diazole ring forms dihedral angles 7.21 (10) and 21.25 (11)° with the quinoline and benzene rings, respectively. The crystal structure features O-H⋯N hydrogen bonds and is further consolidated by C-H⋯O hydrogen-bonding inter-actions involving the water molecule of hydration.

11.
Behav Sci (Basel) ; 13(12)2023 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-38131843

RESUMO

BACKGROUND: This study investigates the effects of exercise intensity and duration on executive functions among college students in China. METHOD: Participants in this study were Chinese college students divided into four groups based on exercise duration and intensity. Each group engaged in physical exercise twice a week for six weeks. Group 1 performed low-intensity exercises for 10 min per session; Group 2 performed low-intensity exercises for 20 min per session; Group 3 performed high-intensity exercises for 10 min per session; and Group 4 performed high-intensity exercise for 20 min per session. Executive functions were assessed in all subjects before the experiment (time 1), after one exercise session (time 2), at the end of the exercise program (time 3), and six weeks after the exercise program (time 4). A mixed ANOVA with a 2 (exercise intensity: low/high) × 2 (duration: short/long) × 4 (time of measurement: time 1/time 2/time 3/time 4) design was employed, with exercise intensity and exercise duration as independent variables and executive functions as the dependent variable. RESULTS: Mixed ANOVA showed that the results revealed a significant main effect of measurement time on working memory accuracy (p < 0.001) and reaction time (p < 0.001); inhibition control accuracy (p < 0.001) and reaction time (p < 0.001); cognitive flexibility accuracy (p < 0.001) and reaction time (p < 0.001). A single session of high-intensity exercise significantly improved executive functions in college students. Both low-intensity and high-intensity exercise were effective in enhancing executive functions, with high-intensity exercise demonstrating better maintenance of the effect. CONCLUSION: Both exercise intensity and exercise duration were found to enhance executive functions in college students, with exercise intensity showing greater effectiveness than exercise duration.

12.
J Soc Psychol ; : 1-14, 2023 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-38055790

RESUMO

We verified whether social class shapes different models of the self in China, by integrating individuals' social mobility beliefs and exploring the mediating effect of sense of control. Participants were randomly assigned to one of 2 (subjective social class: upper vs. low class) × 2 (social mobility beliefs: high vs. low mobility) manipulation conditions. They then completed the sense of control questionnaire and self-focused attention task. High mobility belief could alleviate the difference in perception among different subjective social classes and improve lower classes' control perception. Sense of control mediates subjective social class effects and social mobility beliefs on self-focused attention.

13.
Sci Total Environ ; 865: 161246, 2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-36587686

RESUMO

The response of vegetation growth to soil moisture varies greatly from space and time under climate change and anthropogenic activities. As an important grain producer in China, the vegetation growth and grain production of North China are constrained by the region's water resources. With the significant increase in vegetation greenness in North China over the last 40 years, it is essential to explore the changes in soil moisture constraints on vegetation growth to water management. However, to what degree vegetation growth responds to soil moisture and how the response varies spatiotemporally in North China remain unclear. In this study, the response patterns of vegetation growth to soil moisture at different depths and the spatiotemporal trend patterns of their relationships were explored thoroughly based on long time series remote sensing data in North China over the past 40 years. The results showed that compared to forests, the growth of grasslands and crops with one maturity per year and two maturity per year in North China was more constrained by soil moisture. Due to the combined effects of climatic conditions and human activities, vegetation growth in North China has been significantly less constrained by soil moisture over the last 40 years. This was especially seen in one maturity per year crop and natural vegetation in Shanxi and central Shandong. However, with the significant increase in temperature, potential evapotranspiration and water demand of the crop, the moisture constraints on vegetation growth in North China have begun to show an increasing trend since the early 2000s, especially for irrigated crop in central and southern North China. These findings highlight a comprehensive understanding of the vegetation response to soil moisture from the time-varying perspective and provide a theoretical basis for water management and appropriate planning of agricultural water use in North China.


Assuntos
Agricultura , Solo , Humanos , Produtos Agrícolas , China , Mudança Climática , Água , Ecossistema
14.
Int J Biol Macromol ; 233: 123532, 2023 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-36740110

RESUMO

There are several factors that contribute to the mortality of people who suffer from unmanageable bleeding. Therefore, the development of rapid hemostatic materials is necessary. Herein, novel rapid hemostatic composite sponges were developed by incorporation of kaolin (K) into carboxymethyl chitosan (CMCS)/sodium alginate (SA) via a combination of methods that includes ionic crosslinking, polyelectrolyte action, and freeze-drying. The CMCS/SA-K composite sponges were cross-linked with calcium ions provided by a sustained-release system consisting of D-gluconolactone (GDL) and Ca-EDTA, and the hemostatic ability of the sponges was enhanced by loading the inorganic hemostatic agent-kaolin (K). It was demonstrated that the CMCS/SA-K composite sponges had a good porous structure and water absorption properties, excellent mechanical properties, outstanding biodegradability, and biocompatibility. Simultaneously, they exhibited rapid hemostatic properties, both in vitro and in vivo. Significantly, the hemostatic time of the CMCS/SA-K60 sponge was improved by 82.76 %, 191.82 %, and 153.05 %, compared with those of commercially available gelatin sponges in the rat tail amputation, femoral vein, and liver injury hemorrhage models respectively, indicating that its hemostatic ability was superior to that of commercially available hemostatic materials. Therefore, CMCS/SA-K composite sponges show great promise for rapid hemostasis.


Assuntos
Quitosana , Hemostáticos , Ratos , Animais , Quitosana/química , Caulim/química , Alginatos/química , Hemostasia , Hemostáticos/farmacologia , Hemostáticos/química , Hemorragia/tratamento farmacológico
15.
Intensive Crit Care Nurs ; 74: 103340, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36369190

RESUMO

OBJECTIVE: To assess risk factors of reintubation in intensive care unit patients on mechanical ventilation. METHODOLOGY: We conducted a systematic review of literature (inception to May 2022) and a meta-analysis. Data are reported as pooled odds ratios for categorical variables and mean differences for continuous variables. RESULTS: A total of 2459 studies were retrieved of which 38 studies were included in a meta-analysis involving 22,304 patients. Risk factors identified were: older age, higher APACHE II scores, COPD, pneumonia, shock, low SaO2, low PaO2, low PaO2/FiO2, low hemoglobin, low albumin, high brain natriuretic peptide, low pH, high respiratory rate, low tidal volume, a higher rapid shallow breathing index, a lower vital capacity, a higher number of spontaneous breathing trials, prolonged length of mechanical ventilation, weak cough, a reduced patient's cough peak flow and positive cuff leak test. Subgroup analysis showed that risk factors substantially overlap when reintubation was considered within 48 hours or within 72 hours after extubation. CONCLUSIONS: We identified 21 factors associated with increased risk for reintubation. These allow to recognize the patient at high risk for reintubation at an early stage. Future studies may combine these factors to develop comprehensive predictive algorithms allowing appropriate vigilance.


Assuntos
Unidades de Terapia Intensiva , Respiração Artificial , Humanos , Respiração Artificial/efeitos adversos , Desmame do Respirador , Extubação/efeitos adversos , Fatores de Risco
16.
Nat Commun ; 14(1): 5578, 2023 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-37907466

RESUMO

The dimensional limit of ferroelectricity has been long explored. The critical contravention is that the downscaling of ferroelectricity leads to a loss of polarization. This work demonstrates a zero-dimensional ferroelectricity by the atomic sliding at the restrained van der Waals interface of crossed tungsten disufilde nanotubes. The developed zero-dimensional ferroelectric diode in this work presents not only non-volatile resistive memory, but also the programmable photovoltaic effect at the visible band. Benefiting from the intrinsic dimensional limitation, the zero-dimensional ferroelectric diode allows electrical operation at an ultra-low current. By breaking through the critical size of depolarization, this work demonstrates the ultimately downscaled interfacial ferroelectricity of zero-dimensional, and contributes to a branch of devices that integrates zero-dimensional ferroelectric memory, nano electro-mechanical system, and programmable photovoltaics in one.

17.
Adv Mater ; 35(51): e2304121, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37805835

RESUMO

Encapsulating photoluminescent lanthanide ions like erbium (Er) into fullerene cages affords photoluminescent endohedral metallofullerenes (EMFs). Few reported photoluminescent Er-EMFs are all based on encapsulation of multiple (two to three) metal atoms, whereas mono-Er-EMFs exemplified by Er@C82 are not photoluminescent due to its narrow optical bandgap. Herein, by entrapping an Er-cyanide cluster into various C82 cages to form novel Er-monometallic cyanide clusterfullerenes (CYCFs), ErCN@C82 (C2 (5), Cs (6), and C2 v (9)), the photoluminescent properties of CYCFs are investigated, and obvious near-infrared (NIR) photoluminescence only is observed for ErCN@C2 (5)-C82 . Combined with a comparative photoluminescence study of three medium-bandgap di-Er-EMFs, including Er2 @Cs (6)-C82 , Er2 O@Cs (6)-C82 , and Er2 C2 @Cs (6)-C82 , this study proposes that the optical bandgap can be used as a simple criterion for switching the photoluminescence of Er-EMFs, and the bandgap threshold is determined to be between 0.83 and 0.74 eV. Furthermore, the photoluminescent patterns of these three di-Er-EMFs differ dramatically. It is found that the location of the Er atom within the same Cs (6)-C82 cage is almost fixed and independent on the endo-unit; thus the previous statement on the key role of metal position in photoluminescence of di-Er-EMFs seems erroneous, and the geometric configuration of the endo-unit, especially the bridging mode of two Er ions, is decisive instead.

18.
ACS Appl Mater Interfaces ; 15(9): 11713-11722, 2023 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-36802456

RESUMO

Red phosphorus (RP) is a promising anode material for use in lithium-ion batteries (LIBs) due to its high theoretical specific capacity (2596 mA h g-1). However, the practical use of RP-based anodes has been challenged by the material's low intrinsic electrical conductivity and poor structural stability during lithiation. Here, we describe a phosphorus-doped porous carbon (P-PC) and disclose how the dopant improves the Li storage performance of RP that was incorporated into the P-PC (designated as RP@P-PC). P-doping porous carbon was achieved using an in situ method wherein the heteroatom was added as the porous carbon was being formed. The phosphorus dopant effectively improves the interfacial properties of the carbon matrix as subsequent RP infusion results in high loadings, small particle sizes, and uniform distribution. In half-cells, an RP@P-PC composite was found to exhibit outstanding performance in terms of the ability to store and utilize Li. The device delivered a high specific capacitance and rate capability (1848 and 1111 mA h g-1 at 0.1 and 10.0 A g-1, respectively) as well as excellent cycling stability (1022 mA h g-1 after 800 cycles at 2.0 A g-1). Exceptional performance metrics were also measured when the RP@P-PC was used as an anode material in full cells that contained lithium iron phosphate as the cathode material. The methodology described can be extended to the preparation of other P-doped carbon materials that are employed in contemporary energy storage applications.

19.
ACS Appl Mater Interfaces ; 15(35): 41426-41437, 2023 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-37612260

RESUMO

Nonstoichiometric compounds are widely used in contemporary energy technologies due to their high surface polarity, tailored electronic structure, high electrical conductivity, and other enhanced properties. However, the preparation of such nonstoichiometric compounds can be complicated and, in some cases, uncontrollable and dangerous. Here, we report a "one-pot" strategy for synthesizing N-doped porous graphitic carbon that is hybridized with nonstoichiometric scandium oxide (denoted as ScO0.95@N-PGC) and show that the composite significantly promotes sulfur cathode kinetics in lithium-sulfur (Li-S) batteries. The synthesis of the ScO0.95@N-PGC composite entails heating a porous dry gel that consists of a C source (glucose), a N source (dicyandiamide), and a Sc source (Sc(NO3)3·H2O). Thermally decomposing the dicyandiamide creates a highly reductive atmosphere that simultaneously affords the hypoxic state of the ScO0.95 and dopes the carbon matrix with nitrogen. Density functional theory reveals the presence of oxygen vacancies that enable the ScO0.95 crystals to function as excellent electrical conductors, exhibit enhanced adsorption toward polysulfides, and accelerate the cathode reactions by lowering the corresponding activation energies. Moreover, Li-S cells prepared from the ScO0.95@N-PGC composite display a high specific capacity (1046 mA h g-1 at 0.5 C), an outstanding cycling stability (641 mA h g-1 after 1000 charge-discharge cycles at 0.5 C, a capacity decay of 0.038% per cycle), and a particularly outstanding rate capability (438 mA h g-1 at 8 C). The methodology described establishes a sustainable approach for synthesizing nonstoichiometric compounds while broadening their potential utility in a broad range of energy technologies.

20.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 7): o2029, 2012 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-22807855

RESUMO

In the crystal structure of the title compound, C(8)H(5)NO(4), essentially planar mol-ecules [largest deviation from the least-squares plane = 0.030 (2) Å] form stacks along the a-axis direction. Intercentroid separations between overlapping benzene rings within the stack are 3.6594 (12) Šand 3.8131 (12) Å. Mol-ecules from neighboring stacks are linked by weak C-H⋯O hydrogen bonds into inversion dimers.

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