RESUMEN
The FeOOH/Zn(OH)2/CoS (FZC) nanocomposites are synthesized and show the outstanding electrochemical properties in both supercapacitor and catalytic hydrogen production. The specific area capacitance reaches 17.04 F cm-2, which is more than ten times higher than that of FeOOH/Zn(OH)2 (FZ) substrate: 1.58 F cm-2). FZC nanocomposites also exhibit the excellent cycling stability with an initial capacity retention rate of 93.6% after 10 000 long-term cycles. The electrolytic cell (FZC//FZC) assembled with FZC as both anode and cathode in the UOR (urea oxidation reaction)|| HER (hydrogen evolution reaction) coupled system requires a cell voltage of only 1.453 V to drive a current density of 10 mA cm-2. Especially, the electrochemical performances of FZC nanocomposites are enhanced in magnetic field, and the mechanism is proposed based on Stern double layer model at electrode-electrolyte interface (EEI). More electrolyte ions reach the surface of FZC electrode material under Kelvin force, moreover, the warburg impedance of FZC nanocomposites decrease under magnetic field action, which results in the enhanced behaviors for both the energy storage and urea oxidation reaction .
RESUMEN
Self-healing polymer materials (SHPM) have aroused great interests in recent years. Ideal SHPM should have not only simple operations, but also high elongations at break, tensile strain and self-healing properties at room temperature. Herein, the amidated carbon fibers (CFs) reinforced self-healing polymer composites were designed by hydrogen bonding interaction between functionalized CFs and hyperbranched polymers. The amidated CFs were prepared by transformation of hydroxyl to acylamino through a one-step amidation. By introducing amidated CFs, amidated CFs self-healing polymer composites (called AD-CF) exhibited many desirable characteristics compared to pure polymer composites, such as a better elasticity, lower healing temperatures, and higher self-healing efficiencies. The stress-strain test was selected to carefully study the self-healing property of the AD-CF. The observed same recovery condition, i.e. without any mechanical breakdown after the 10 sequential cycles of cutting and healing indicates no aging of the AD-CF. The ability of AD-CF to exhibit a soft state and rapid self-healing at room temperature makes it possible for much wider applications.
RESUMEN
Heating under low solar radiation intensity is demonstrated to facilitate the cleaning of crude oil by the hydrophobic nanocomposite adsorbents of reduced graphene oxide (RGO) melamine sponge (MS@RGO) foams. The heat generated by the irradiation reduces the viscosity of the crude oil, and consequently increases the oil-diffusion coefficient of the pores of the MS@RGO foams and speeds up the oil-sorption rate. Even under a solar radiation intensity as low as 2 kW m-2, the temperature of crude oil rapidly rises to 68 °C or higher within 10 min. It only takes 29 s to completely absorb 6 g of crude oil at 60 °C by three tiny pieces of MS@RGO foam. This work makes better use of the excellent photothermal conversion characteristics of crude oil, and its photothermal conversion mechanism under simulated solar radiation is also discussed. This methodology can be adopted to clean up viscous crude oil or extract other chemicals effectively at a large scale, and provides a complete solution for the cleanup of crude oil in the sea or on the beach for actual engineering applications.
RESUMEN
BACKGROUND: Previous performance evaluations among community health service centres (CHSCs) have been mainly based on absolute indicators, while the operation index, a more comprehensive evaluation method, has been rarely used in evaluation. This study aimed to develop a set of operation index suitable for the evaluation of CHSCs in Pudong. METHODS: The operation index system, developed based on a literature review, focus group, and factor analysis, was applied to all 45 CHSCs in Pudong. The data were mainly derived from the Pudong Health Statistics Information System from 2010 to 2014. The analysis included a descriptive analysis, t tests, variance analysis, and repeated measures analysis of variance. RESULTS: Different aspects of the operation index showed different developing trends during 2010 to 2014. The overall operation, service operation, management condition, and comprehensive satisfaction index were significantly different in different years (P < 0.05). However, the differences in the development foundation index were not obvious (P > 0.05). Moreover, the regional factor and medical association influenced the performance of service operation index, and the informatization level affected the performance of overall operation and management condition index (P < 0.05), with different family GP programmes level affecting management condition index (P < 0.05). CONCLUSION: Changes in the management condition index led to fluctuations in overall operation in the CHSCs. Since regional factors, family GP programmes, and medical associations promoted the operation of CHSCs, we advocate a multi-dimensional evaluation combining horizontal performance appraisal and vertical index evaluation to focus on these factors.
Asunto(s)
Centros Comunitarios de Salud/organización & administración , Eficiencia Organizacional , Indicadores de Calidad de la Atención de Salud , China , Eficiencia Organizacional/estadística & datos numéricos , Grupos Focales , Reforma de la Atención de Salud , Indicadores de Calidad de la Atención de Salud/estadística & datos numéricosRESUMEN
To tackle the shortage of health personnel in the rural areas of Pudong New Area of Shanghai, the local government issued an incentive policy as one of the medical reforms. The current investigation focused on the relevant incentive measures and their corresponding effects and problems with a view to providing referential and useful experiences for those who are engaged in addressing the same problem at home and abroad. The details of the incentive policy were derived from the government document, and the related data about the flow of the rural community health care providers, from the institutional investigation. As indicated by the current investigation, the incentive policy produced some positive effect in attracting health care providers to work in the rural community health centers, especially general practitioners, nurses, MS/MD degree holders, and intermediate professional title holders to be employed in the farther ones. However, it was turned out that the population of high quality health care providers was still not sufficient enough to cover the whole rural areas, which suggested that it was still hard to draw such qualified medical individuals. To conclude in the current investigation, we made three recommendations for the policymakers to take into account in terms of policy maintenance, benefits for health personnel, and guarantee of their lawful rights and interests.
Asunto(s)
Personal de Salud , Selección de Personal , Reorganización del Personal , Servicios de Salud Rural , China , Servicios de Salud Comunitaria/organización & administración , Personal de Salud/organización & administración , Humanos , Área sin Atención Médica , Política Organizacional , Selección de Personal/métodos , Médicos/organización & administración , Estudios Retrospectivos , Servicios de Salud Rural/organización & administración , Población RuralRESUMEN
The public hospital reform has lasted 5 years in China; however, the operation development status and trends of public hospitals have not been systematically evaluated in Pudong New District. We first applied the technology of longitudinal index to assess the development of public hospitals there. The quantitative data were mainly gathered by taking health statistics database from 2009 to 2014. The results showed that overall operating index presented a down-up trend, with the highest point in 2014 and the lowest point in 2012. Overall operating index, development foundation index, and management condition index were found to be statistically different ( P = .010, P = .016, P = .031) in different years, whereas the service operation index and financial risk index were not so ( P = .543, P = .228). Moreover, the results demonstrated that no obvious difference was observed in the overall operating index between the general and specialized hospitals ( P = .327), which was the same in the 4 first-class indexes. However, there were statistical differences in the overall operating index and development foundation index among these 5 years ( P = .018, P = .036), but none in the service operation index, management condition index, and financial risk index ( P = .503, P = .062, P = .177). No interaction effects were discovered between year and hospital categories in the current study ( P = .673, P = .375, P = .885, P = .152, P = .288).
Asunto(s)
Reforma de la Atención de Salud , Hospitales Públicos/estadística & datos numéricos , Indicadores de Calidad de la Atención de Salud/estadística & datos numéricos , China , Personal de Salud , Humanos , Estudios Longitudinales , Modelos EstadísticosRESUMEN
We designed and prepared the ZnSe/CoSe2@NC/CNTs (ZCNC) cathode material for aluminum batteries (ABs). The ZCN (ZnSe/CoSe2@NC) is connected by the interwoven carbon nanotube (CNT) conductive network to form a beaded structure. CNTs and the carbon formed by carbonization of organic ligands is beneficial to improving the electrical conductivity of the material and reducing structural damage during cycling. The internal electric field generated at the interface of heterostructures can promote the transfer of electrons/ions. This special structure promotes ZCNC excellent electrochemical properties. At 100 mA/g, the specific capacity of the first discharge reaches 338 mAh/g, while the specific capacity after 500 cycles still reaches 217 mAh/g. Compared with ZCN and CN(CoSe2@NC), it demonstrates a great advantage.
RESUMEN
Electrocatalytic reduction of nitric oxide (NO) to ammonia (NH3 ) is a clean and sustainable strategy to simultaneously remove NO and synthesize NH3 . However, the conversion of low concentration NO to NH3 is still a huge challenge. In this work, the dilatation strain between Cu and Co interface over Cu@Co catalyst is built up and investigated for electroreduction of low concentration NO (volume ratio of 1%) to NH3 . The catalyst shows a high NH3 yield of 627.20 µg h-1 cm-2 and a Faradaic efficiency of 76.54%. Through the combination of spherical aberration-corrected transmission electron microscopy and geometric phase analyses, it shows that Co atoms occupy Cu lattice sites to form dilatation strain in the xy direction within Co region. Further density functional theory calculations and NO temperature-programmed desorption (NO-TPD) results show that the surface dilatation strain on Cu@Co is helpful to enhance the NO adsorption and reduce energy barrier of the rate-determining step (*NO to *NOH), thereby accelerating the catalytic reaction. To simultaneously realize NO exhaust gas removal, NH3 green synthesis, and electricity output, a Zn-NO battery with Cu@Co cathode is assembled with a power density of 3.08 mW cm-2 and an NH3 yield of 273.37 µg h-1 cm-2 .
RESUMEN
Advances in cathode material design and understanding of intercalation mechanisms are necessary to improve the overall performance of aluminum ion batteries. Therefore, we designed ZnSe/SnSe2 hollow microcubes with heterojunction structure as a cathode material for aluminum ion batteries. ZnSe/SnSe2 hollow microcubes with an average size of about1.4 µm were prepared by selenization of ZnSn(OH)6 microcubes successfully. The shell thickness of ZnSe/SnSe2 hollow microcubes is about 250 nm. On one hand, the hollow cubic structure can effectively alleviate the volume effect, provide shorter ion diffusion paths, and increase the contact area with the electrolyte. On the other hand, ZnSe/SnSe2 heterojunction structure can establish a built-in electric field to facilitate ion transport. The synergistic effect of the two leads to the improved electrochemical performance of ZnSe/SnSe2 as the cathode of aluminum ion batteries. The material delivered a reversible capacity of 124 mAh/g after 150 cycles at a current density of 100 mA/g. Meanwhile, coulombic efficiency remained above 98% in almost all cycles. In addition, the electrochemical reaction mechanism and kinetic process of Al3+ and ZnSe/SnSe2 were studied.
RESUMEN
We report a low-cost, high theoretical specific capacity π-conjugated organic compound (PTCDA) with CâO active centers as the cathode material in aluminum organic batteries. In addition, in order to improve the electron transport rate of PTCDA, a new method is proposed in this paper, which uses physical vapor deposition (PVD) method to make PTCDA recrystallize and grow on stainless steel and quartz glass substrates to improve its crystallinity. The increase of crystallinity expands the PTCDA π-π-conjugated system, making electrons more delocalized, which is beneficial to the transmission rate of electrons and ions, thereby enhancing the conductivity of the material. The experimental results show that compared with pristine PTCDA, PTCDA(Ss) and PTCDA(G) with higher crystallinity have better cycling stability and rate capability. The DFT (density functional theory) results indicated that the electron-deficient carbonyl group in the PTCDA molecule could reversibly coordinate/dissociate with the positively charged Al complex ions (AlCl2+). This research work provides insights into the rational design of low-dimensional, high-crystallinity, high-performance cathode materials for green aluminum organic batteries.
RESUMEN
Porous CoSe2 nanosheets are prepared on nickel foam by the hydrothermal method using Se powder as the selenium source and a zeolitic imidazolate framework (ZIF-67) as the template. The impact of hydrothermal temperature on the morphological structure and electrochemical performance of the CoSe2 materials is investigated by characterization with HRTEM, SEM, XRD, and so on, and CV and GCD electrochemical tests. The results show that the CoSe2-180 electrode material exhibits excellent electrochemical performance, and its unique nanosheet array structure can provide a highly active surface, large superficial area and fast ion transport channels. This is mainly attributed to the fact that the reaction at different hydrothermal temperatures can provide different nanosheet structures. An ordered array structure is most clearly observed at a hydrothermal temperature of 180 °C. In addition, the incorporated ZIF-67 backbone provides a pathway for rapid electron transfer and accommodates the volume expansion of the selenide during charge-discharge processes. Due to the distinct porous structure, the CoSe2-180 electrode shows a high specific capacity of 269.4 mA h g-1 at 1 A g-1 and a distinguished retention rate of 83.7% at 20 A g-1. After 5000 cycles, the specific capacity can be maintained at 83.4% of the initial value. Moreover, the asymmetric supercapacitor (ASC) device is assembled with CoSe2-180 as the positive electrode. It displays favorable electrochemical performance with the maximum specific energy of 45.6 W h kg-1 at a specific power of 800.8 W kg-1 and an original capacitance retention rate of 81.5% after 5000 cycles.
RESUMEN
Aluminum batteries (ABs) have triggered increasing interest due to the geochemically abundant aluminum, high theoretical energy density, and excellent safety characteristics. Organic materials with engineered active groups have the advantages of low cost, flexible structural design, and benignity to the environment. Herein, we report an appropriately heat treated aromatic carbonyl derivative PTCDA/500 °C as an organic cathode material for ABs. The constructed aluminum organic batteries exhibited excellent cycling stability, with a capacity retention rate of 91% (111 mAh/g) after 200 cycles at a current density of 1000 mA/g and also displayed the more excellent rate capability at different current densities. In addition, the electrochemical reaction mechanism of AlCl2+ and PTCDA was studied based on density functional theory (DFT) as well as the ion diffusion behavior on the electrode surface being probed. The research results provide new ideas for the development of green and sustainable aluminum organic batteries.
RESUMEN
In this study, CoS/MnCo2O4-MnO2 (CMM) nanocomposites were synthesized by hydrothermal and then electrochemical deposition. Their electrochemical properties were systematically investigated for supercapacitors and energy-saving H2 production. As an electrode material for supercapacitor, CMM demonstrates a specific capacitance of 2320F g-1 at 1 A/g, and maintains a specific capacitance of 1216F g-1 at 10 A/g. It also shows 72.8 % capacitance retention after 8000 cycles. The aqueous asymmetric supercapacitor exhibited high energy storage capacity (887.86F g-1 specific capacitance at a current density of 1 A/g), good rate performance and cycling stability. Besides, CMM shows outstanding urea oxidation reaction(UOR) and glycol oxidation reaction (MOR) performances for H2 production. Compared to oxygen evolution reaction (OER) (1.635 V) at 20 mA cm-2, the potentials were reduced by 213 mV for UOR and 233 mV for MOR, respectively. Therefore, this study shows the promising practical applications of CMM nanocomposites for energy storage and energy-saving H2 production.
RESUMEN
Formaldehyde (HCHO) sensing plays a critical role for indoor environment monitoring in smart home systems. Inspired by the unique hierarchical structure of cactus, we have prepared a ZnO/ANS-rGO composite for room-temperature (RT) HCHO sensing, through assembling hollow cactus-like ZnO nanorods with 5-aminonaphthalene-1-sulfonic acid (ANS)-modified graphene nanosheets in a facile and template-free manner. Interestingly, it was found that the ZnO morphology could be simply tuned from flower clusters to hollow cactus-like nanostructures, along with the increase of the reaction time during the assembly process. The ZnO/ANS-rGO-based sensors exhibited superior RT HCHO-sensing performance with an ultrahigh response (68%, 5 ppm), good repeatability, long-term stability, and an outstanding practical limit of detection (LOD: 0.25 ppm) toward HCHO, which is the lowest practical LOD reported so far. Furthermore, for the first time, a 30 m3 simulation test cabinet was adapted to evaluate the practical gas-sensing performance in an indoor environment. As a result, an instantaneous response of 5% to 0.4 ppm HCHO was successfully achieved in the simulation test. The corresponding sensing mechanism was interpreted from two aspects including high charge transport capability of ANS-rGO and the distinct gas adsorbability derived from nanostructures, respectively. The combination of a biomimetic hierarchical structure and supramolecular assembly provides a promising strategy to design HCHO-sensing materials with high practicability.
RESUMEN
Magnesium alloys can work as biomedical materials due to their Young's modules similar to that of bone. Nevertheless, in a human plasma, one of the major drawbacks of these materials is the low corrosion resistance. Here, AZ80 corrosion in the solutions containing chloride, bicarbonate, sulphate and hydrogen phosphate ions were investigated by a short-term immersion test and electrochemical techniques. The results showed that bicarbonate and hydrogen phosphate could retard corrosion rate, while chloride and sulphate accelerated corrosion rate. During the early immersion stage, the corrosion rate increased with the presence of bicarbonate. It was caused by the reaction of bicarbonate and hydroxide promoting the dissolution of magnesium and accelerating corrosion. In the later stage, the reduced corrosion rate was due to the formation of various protective films. The sample formed a new sparse porous MgSO4·5H2O compounds in the sulphate ion solution, which could not effectively prevent chloride ions from entering the matrix and thus accelerated the dissolution of magnesium. With the presence of hydrogen phosphate, magnesium phosphate with a much lower solubility was formed, preferentially precipitated on the surface and was not influenced by the chloride ions. The corrosion mechanisms of magnesium alloys in above ions were proposed.
Asunto(s)
Aleaciones , Magnesio , Materiales Biocompatibles , Corrosión , Humanos , Iones , Ensayo de Materiales , Propiedades de SuperficieRESUMEN
Mixed-valence metal-organic frameworks (MOFs) have exhibited unique potential in fields such as catalysis and gas separation. However, it is still an open challenge to prepare mixed-valence MOFs with isolated Ce(IV, III) arrays due to the easy formation of CeIII under the synthetic conditions for MOFs. Meanwhile, the performance of Li-S batteries is greatly limited by the fatal shuttle effect and the slow transmission rate of Li+ caused by the inherent characteristics of sulfur species. Here, we report a mixed-valence cerium MOF, named CSUST-1 (CSUST stands for Changsha University of Science and Technology), with isolated Ce(IV, III) arrays and abundant oxygen vacancies (OVs), synthesized as guided by the facile and elaborate kinetic stability study of UiO-66(Ce), to work as an efficient separator coating for circumventing both issues at the same time. Benefiting from the synergistic function of the Ce(IV, III) arrays (redox couples), the abundant OVs, and the open Ce sites within CSUST-1, the CSUST-1/CNT composite, as a separator coating material in the Li-S battery, can remarkably accelerate the redox kinetics of the polysulfides and the Li+ transportation. Consequently, the Li-S cell with the CSUST-1/CNT-coated separator exhibited a high initial specific capacity of 1468 mA h/g at 0.1 C and maintained long-term stability for a capacity of 538 mA h/g after 1200 cycles at 2 C with a decay rate of only 0.037% per cycle. Even at a high sulfur loading of 8 mg/cm2, the cell with the CSUST/CNT-coated separator still demonstrated excellent performance with an initial areal capacity of 8.7 mA h/cm2 at 0.1 C and retained the areal capacity of 6.1 mA h/cm2 after 60 cycles.
RESUMEN
The increasing demand for energy and environmental protection has stimulated intensive interest in fundamental research and practical applications. Nickel dichalcogenides (Ni3S2, NiS, Ni3Se2, NiSe, etc.) are promising materials for high-performance electrochemical energy storage and conversion applications. Herein, 3D Ni3S2 nanorod arrays are fabricated on Ni foam by a facile solvothermal route. The optimized Ni3S2/Ni foam electrode displays an areal capacity of 1602 µA h cm-2 at 5 mA cm-2, excellent rate capability and cycling stability. Besides, 3D Ni3S2 nanorod arrays as electrode materials exhibit outstanding performances for the overall water splitting reaction. In particular, the 3D Ni3S2 nanorod array electrode is shown to be a high-performance water electrolyzer with a cell voltage of 1.63 V at a current density of 10 mA cm-2 for overall water splitting. Therefore, the results demonstrate a promising multifunctional 3D electrode material for electrochemical energy storage and conversion applications.
RESUMEN
Antifouling biocides releasing restricts the longevity of antifouling coatings. Compared with the anchoring state, the releasing behavior of agents is much faster on the voyage, while the biofouling process is tougher. In this work, a series of capsaicin-based pH-triggered polyethylene glycol/capsaicin@chitosan (PEG/CAP@CS), polyvinyl alcohol (PVA)/CAP@CS and alginate (ALG)/CAP@CS multilayer films are prepared with controlling antimicrobial properties in marine environments. There are 23.70, 23.35 and 22.06â¯ppb CAP releasing from (PVA/CAP@CS)20, (PEG/CAP@CS)20 and (ALG/CAP@CS)20 films after immersing in pH 4 solutions for 60 days, while only 13.07, 12.95 and 11.55â¯ppb CAP have been found in alkaline solutions after immersing for the same time, respectively. All these three types of films exhibit extraordinary pH responsive properties. They can control the CAP release at a low level in alkaline solutions, and make the CAP release fast in acid solutions. Moreover, the antibacterial properties against P.aeruginosa are outstanding about 95.84%, 95.0% and 96.91% for (PVA/CAP@CS)20, (PEG/CAP@CS)20 and (ALG/CAP@CS)20 films, respectively. The bacteriostasis of (ALG/CAP@CS)20 film keeps 92.73% after 60 days in alkaline solution, which means it is steadily controlled in the marine environment. Although with similar antibacterial properties to those of (PEG/CAP@CS)20 film, (PVA/CAP@CS)20 film displays the maximum decrease with about 92% in acid solution after 60 days. The ALG/CAP@CS film with the best-controlled release performance and long-term antibacterial properties provides novel guidance for developing new antifouling coatings application in the marine environment.
Asunto(s)
Antibacterianos/farmacología , Incrustaciones Biológicas , Capsaicina/farmacología , Ecosistema , Alginatos/química , Quitosano/química , Concentración de Iones de Hidrógeno , Conformación Molecular , Nanocápsulas/química , Imagen Óptica , Polietilenglicoles/química , Alcohol Polivinílico/química , Pseudomonas aeruginosa/efectos de los fármacos , Espectroscopía Infrarroja por Transformada de Fourier , Electricidad EstáticaRESUMEN
TiO2 nanorod (NR) array for perovskite solar cells (PSCs) has attained great importance due to its superb power conversion efficiency (PCE) compared to that of the traditional mesoporous TiO2 film. A TiO2 compact layer for the growth of TiO2 NR array via spin-coating cannot meet the requirements for efficient NR-based PSCs. Herein, we have developed and demonstrated the insertion of a bifunctional extrathin TiO2 interlayer (5 nm) by atomic layer deposition (ALD) at the interface of the fluorine-doped tin oxide (FTO)/TiO2 compact layer to achieve alleviated electron exchange and a reduced energetic barrier. Thus, an accelerated extraction of electrons from TiO2 NR arrays via the compact layer and their transfer to the FTO substrate can improve the PSC efficiency. The thickness of the spin-coated TiO2 compact layer on the ALD-deposited TiO2 layer is spontaneously optimized. Finally, an outstanding efficiency of 20.28% has been achieved from a champion PSC with negligible hysteresis and high reliability. To the best of our knowledge, this is the first study demonstrating the superiority of TiO2-NR-based PSCs withstanding the dry heat and thermal cycling tests. The results are of great importance for the preparation of efficient and durable PSCs for real-world applications.
RESUMEN
In this work, nitrogen and sulfur dual-doped carbon quantum dots (N,S-CDs) from naturally renewable biomaterial fungus fibers were prepared by a biosynthesis and hydrothermal method. The N,S-CDs displayed good water solubility, excellent stability, high quantum yield (QYâ¯=â¯28.11%) as well as remarkable features for fluorescence quenching-based detection and cellular imaging of cancer cells. It was worth mentioning that the heteroatoms doped carbon quantum dots made from the fungus fibers had a satisfactory QY and could be used as a selective, efficient, and sensitive fluorescent probe to determine tetracyclines by the synergistic effects of static quenching and internal filtration effect. The probe demonstrated a wide linear range and low detection limit. For tetracycline, the linear range was 0.5⯵M to 47.6⯵M, and the corresponding detection limit was 15.6â¯nM. Significantly, the test papers prepared by using N,S-CDs could detect tetracyclines in aquiculture wastewater rapidly. The produced N,S-CDs did not affect the cell viability and showed great promises for cellular imaging.