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1.
Cell Tissue Res ; 2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33544212

RESUMO

Cardiovascular diseases are the leading cause of death in the world due to the high incidence of the diseases coupled with the limited therapeutic options. In recent years, advances in regenerative medicine have emerged as a promising treatment. Differentiation of induced pluripotent stem cells (iPSCs) into cardiac cells and emerging technologies allowing arrangement of cells into complex 3D tissue-like structures open new frontiers for transplantation and engraftment of these tissue patches onto the damaged heart. Despite the cells integrating and presenting initial neovascularization, the functional and electric properties of these patches are still not comparable with those of the host cardiac tissue. Future research optimizing maturation and integration of the iPSC-derived cardiomyocytes is paramount for cardiac cell therapy to attain clinical use. Herein, we will review the state of the art and the different approaches to constructing these 3D transplantable structures.

2.
J Am Chem Soc ; 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33535753

RESUMO

The inorganic lead-free Cs2AgBiBr6 double perovskite structure is the promising development direction in perovskite solar cells (PSCs) to solve the problem of the instability of the APbX3 structure and lead toxicity. However, the low short-circuit current and power conversion efficiency (PCE) caused by the low crystallization of Cs2AgBiBr6 greatly limit the optoelectronic application. Herein, we adopt a simple strategy to dope single-layered MXene nanosheets into titania (Ti3C2Tx@TiO2) as a multifunctional electron transport layer for stable and efficient Cs2AgBiBr6 double PSCs. The single-layered MXene nanosheets significantly improve the electrical conductivity and electron extraction rate of TiO2; meanwhile, the single-layered MXene nanosheets change the surface wettability of the electron transport layer and promote the crystallization of the Cs2AgBiBr6 double perovskite in solar cell devices. Therefore, the PCE went up by more than 40% to 2.81% compared to that of a TiO2 based device, and the hysteresis was greatly suppressed. Furthermore, the device based on Ti3C2Tx@TiO2 showed the long-term operating stability. After storing the device for 15 days under ambient air conditions, the PCE still remained a retention rate of 93% of the initial one. Our finding demonstrates the potential of Ti3C2Tx@TiO2 in electron transfer material of high-performance double PSCs.

3.
Science ; 371(6529): 636-640, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33542138

RESUMO

The band edges of metal-halide perovskites with a general chemical structure of ABX3 (A, usually a monovalent organic cation; B, a divalent cation; and X, a halide anion) are constructed mainly of the orbitals from B and X sites. Hence, the structural and compositional varieties of the inorganic B-X framework are primarily responsible for regulating their electronic properties, whereas A-site cations are thought to only help stabilize the lattice and not to directly contribute to near-edge states. We report a π-conjugation-induced extension of electronic states of A-site cations that affects perovskite frontier orbitals. The π-conjugated pyrene-containing A-site cations electronically contribute to the surface band edges and influence the carrier dynamics, with a properly tailored intercalation distance between layers of the inorganic framework. The ethylammonium pyrene increased hole mobilities, improved power conversion efficiencies relative to that of a reference perovskite, and enhanced device stability.

4.
Food Chem ; 339: 127885, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32866704

RESUMO

The current study develops an effective, convenient, low-cost, and environmentally friendly method for determining trans-resveratrol (TRA) in peanut oils, the unique proportion of peanut oil, by employing natural cotton fibers without any pretreatment as extraction sorbent and an in-syringe extraction device. The primary factors affecting the extraction recovery are optimized in detail. The condition of 200.0 mg of cotton fibers, six push-pull times, 2.0 mL of n-hexane as washing solvent and 2.0 mL of ethanol as desorption solvent is selected as the best. The linear range is demonstrated to be 10-1000 ng/g with a satisfactory correlation coefficient (R2 = 0.9995), while the limit of detection is calculated as 2.47 ng/g. In addition, the recoveries of TRA are obtained in the range of 93.8-104.4% with RSDs less than 5.5%. Finally, the developed method is successfully applied to determine TRA concentrations in commercial peanut oils and other edible oils.


Assuntos
Arachis/química , Cromatografia Líquida de Alta Pressão/métodos , Fibra de Algodão , Óleo de Amendoim/química , Resveratrol/análise , Adsorção , Arachis/metabolismo , Hexanos/química , Isomerismo , Limite de Detecção , Reprodutibilidade dos Testes , Resveratrol/isolamento & purificação , Extração em Fase Sólida/instrumentação , Extração em Fase Sólida/métodos , Espectrofotometria Ultravioleta
5.
Ying Yong Sheng Tai Xue Bao ; 31(9): 2977-2984, 2020 Sep 15.
Artigo em Chinês | MEDLINE | ID: mdl-33345498

RESUMO

Stellera chamaejasme is one of most common poisonous plant species in degraded grasslands of China. S. chamaejasme could dominate the community in some severely degraded grasslands, which is a serious threat to the sustainable development of animal husbandry in natural grasslands. In this study, S. chamaejasme population was divided into 10 age classes according to the number of branches. We investigated the age structure of S. chamaejasme population and population dynamic indices, and quantified the survival status of S. chamaejasme population by compiling a static life table, drawing a survival curve, conducting survival analysis. The age structure of S. chamaejasme population in the study area was growth type. The number of individuals in Ⅰ age class was sufficient but with relatively low survival rate. The population structure of S. chamaejasme was fitted the growing type. The development process of population was fluctuating. The number of individuals would drop sharply in Ⅱ and Ⅷ, indicating that these two age classes were the bottleneck period in the development of S. chamaejasme population. The survival curves of S. chamaejasme population was the Deevey-Ⅱ type. The results of survival analysis showed that the population had a sharp decrease in the early stage and was stable in the later stage, which was because the value of fx and λx of S. chamaejasme in Ⅰ or Ⅱ age class were the highest. In conclusion, sufficient young individuals (Ⅰ) was the basis for the expansion of S. chamaejasme population in the degraded typical steppe. The low transformation rate of young individuals to adults might be one of the reasons explaining why S. chamaejasme population could not expand rapidly in the early stage of grassland degradation. Therefore, it was suggested to intervene early when the number of S. chamaejasme was limited.


Assuntos
Thymelaeaceae , Animais , China , Humanos
6.
Sci Rep ; 10(1): 10306, 2020 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-32587358

RESUMO

The effects of increasing yield and quality of virus-free chewing cane seedlings and their physiological and molecular basis were studied in this study. Results showed that compared with infected seedlings (the control), the yield of chewing cane stems grown from virus-free seedlings increased by 21.81-29.93%, stem length increased by 28.66-34.49 cm, internode length increased by 2.16-2.68 cm, the single stem weight increased by 20.10-27.68%, the reducing sugar increased by 0.91-1.15% (absolute value), and sucrose increased by - 0.06-1.33% (absolute value). The decrease in sucrose content did not reach significant level, but all other parameters were reached significant level. The chlorophyll content, photosynthetic parameters such as stomatal conductance (Gs), net photosynthetic rate (Pn) and transpiration rate (Tr), the activity of photosynthetic key enzymes ribulose-1,5-bisphosphate carboxylase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC), and gene (pepc, rbcS, and rbcL) expression levels were all greater in virus-free seedlings than infected seedlings. The content of superoxide anion (O2-) and malondialdehyde (MDA) in virus-free seedlings was lower than infected seedlings at the main growth stage. With increased development, the activities of the antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were gradually higher in virus-free seedlings than infected seedlings. Our results indicate that virus-free seedlings may improve photosynthesis efficiency and promote photosynthesis by increasing chlorophyll content, photosynthetic key enzyme activity, and the gene expression levels in leaves. By increasing the activity of antioxidant enzymes, reducing the degree of membrane lipid peroxidation, and improving the stress resistance of chewing cane, the virus-free chewing cane seedlings increased yield and quality. Our findings provide a scientific and theoretical basis for the promotion and application of virus-free chewing cane seedlings.

7.
ACS Appl Mater Interfaces ; 12(19): 21772-21778, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32319284

RESUMO

Organic-inorganic halide perovskite solar cells (PSCs) still suffer from stability issues which are caused by possible erosions from moisture, ultraviolet (UV) light, heat, and so forth. An electron-transporting layer (ETL), that is, TiO2, is a key component for state-of-the-art PSCs. However, UV-caused desorption of O2- in TiO2 would accelerate the degradation of PSCs. Herein, we explored perovskite oxide, NaTaO3, for the first time as an alternative ETL in PSCs. NaTaO3 as an ETL can effectively avoid the damage from UV irradiation, inhibit the degradation of the perovskite layer, and improve the overall stability of the PSC. PSCs fabricated with NaTaO3 yielded a power conversion efficiency (PCE) of 21.07% with a retention of more than 80% of this initial PCE after 240 min UV irradiation in air while the reference device with a PCE of 20.16% can only retain about 53% of its initial PCE after the same testing condition. The developed stable perovskite oxide material of NaTaO3 provides the diversification of electron-selective contact for highly efficient and stable PSCs.

8.
Biosens Bioelectron ; 156: 112136, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32174561

RESUMO

Shewanella oneidensis MR-1, a model species of exoelectrogenic bacteria (EEB), has been widely applied in bioelectrochemical systems. Biofilms of EEB grown on electrodes are essential in governing the current output and power density of bioelectrochemical systems. The MR-1 genome is exceptionally dynamic due to the existence of a large number of insertion sequence (IS) elements. However, to date, the impacts of IS elements on the biofilm-forming capacity of EEB and performance of bioelectrochemical systems remain unrevealed. Herein, we isolated a non-motile mutant (NMM) with biofilm-deficient phenotype from MR-1. We found that the insertion of an ISSod2 element into the flrA (encoding the master regulator for flagella synthesis and assembly) of MR-1 resulted in the non-motile and biofilm-deficient phenotypes in NMM cells. Notably, such a variant was readily confused with the wild-type strain because there were no obvious differences in growth rates and colonial morphologies between the two strains. However, the reduced biofilm formation on the electrodes and the deteriorated performances of bioelectrochemical systems and Cr(VI) immobilization for the strain NMM were observed. Given the wide distribution of IS elements in EEB, appropriate cultivation and preservation conditions should be adopted to reduce the likelihood that IS elements-mediated mutation occurs in EEB. These findings reveal the negative impacts of IS elements on the biofilm-forming capacity of EEB and performance of bioelectrochemical systems and suggest that great attention should be given to the actual physiological states of EEB before their applications.

9.
J Am Chem Soc ; 142(5): 2364-2374, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31917562

RESUMO

Halide perovskites are a strong candidate for the next generation of photovoltaics. Chemical doping of halide perovskites is an established strategy to prepare the highest efficiency and most stable perovskite-based solar cells. In this study, we unveil the doping mechanism of halide perovskites using a series of alkaline earth metals. We find that low doping levels enable the incorporation of the dopant within the perovskite lattice, whereas high doping concentrations induce surface segregation. The threshold from low to high doping regime correlates to the size of the doping element. We show that the low doping regime results in a more n-type material, while the high doping regime induces a less n-type doping character. Our work provides a comprehensive picture of the unique doping mechanism of halide perovskites, which differs from classical semiconductors. We proved the effectiveness of the low doping regime for the first time, demonstrating highly efficient methylammonium lead iodide based solar cells in both n-i-p and p-i-n architectures.

10.
ACS Appl Mater Interfaces ; 12(1): 836-843, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31840488

RESUMO

Perovskite solar cells have attracted worldwide attention as one of the key research areas in the field of thin-film photovoltaics. Although they exhibit easy solution processability, it is important to effectively control the crystallization of the light-absorbing layer, which affects the performance and stability of devices. Here, we present lead oxalate (PbC2O4) as a nonhalide lead constituent of the perovskite precursor solution, which contributes to anion replacement during thin film annealing. This strategy limits the perovskite nucleation rate and retards crystallization. As a result, we achieved excellent perovskite films with larger grains and fewer defects. The open-circuit voltage of the optimal device under 1 sun illumination rose to 1.12 V with a power conversion efficiency (PCE) of 20.20%. In addition, the indoor PCE at 1000 lux can reach 34.86%. This nonhalide lead compound dopant provides a guide for the crystallization of perovskite materials and paves a way for the fabrication of nonhalide perovskite solar cells.

11.
Nano Lett ; 20(1): 715-721, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31870153

RESUMO

Bulk heterojunction (BHJ) structure based organic photovoltaics (OPVs) have recently showed great potential for achieving high power conversion efficiencies (PCEs). An ideal BHJ structure would feature large donor/acceptor interfacial areas for efficient exciton dissociation and gradient distributions with high donor and acceptor concentrations near the anode and cathode, respectively, for efficient charge extraction. However, the random mixing of donors and acceptors in the BHJ often suffers the severe charge recombination in the interface, resulting in poor charge extraction. Herein, we propose a new approach-treating the surface of the zinc oxide (ZnO) as an electron transport layer with potassium hydroxide-to induce vertical phase separation of an active layer incorporating the nonfullerene acceptor IT-4F. Density functional theory calculations suggested that the binding energy difference between IT-4F and the PBDB-T-2Cl, to the potassium (K)-presenting ZnO interface, is twice as strong as that for IT-4F and PBDB-T-2Cl to the untreated ZnO surface, such that it would induce more IT-4F moving toward the K-presenting ZnO interface than the untreated ZnO interface thermodynamically. Benefiting from efficient charge extraction, the best PCEs increased to 12.8% from 11.8% for PBDB-T-2Cl:IT-4F-based devices, to 12.6% from 11.6% for PBDB-T-2Cl:Y1-4F-based devices, to 13.5% from 12.2% for PBDB-T-2Cl:Y6-based devices, and to 15.7% from 15.1% for PM6:Y6-based devices.

12.
Science ; 366(6472): 1509-1513, 2019 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-31857483

RESUMO

Surface trap-mediated nonradiative charge recombination is a major limit to achieving high-efficiency metal-halide perovskite photovoltaics. The ionic character of perovskite lattice has enabled molecular defect passivation approaches through interaction between functional groups and defects. However, a lack of in-depth understanding of how the molecular configuration influences the passivation effectiveness is a challenge to rational molecule design. Here, the chemical environment of a functional group that is activated for defect passivation was systematically investigated with theophylline, caffeine, and theobromine. When N-H and C=O were in an optimal configuration in the molecule, hydrogen-bond formation between N-H and I (iodine) assisted the primary C=O binding with the antisite Pb (lead) defect to maximize surface-defect binding. A stabilized power conversion efficiency of 22.6% of photovoltaic device was demonstrated with theophylline treatment.

13.
J Am Chem Soc ; 141(44): 17610-17616, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31639300

RESUMO

The ideal charge transport materials should exhibit a proper energy level, high carrier mobility, sufficient conductivity, and excellent charge extraction ability. Here, a novel electron transport material was designed and synthesized by using a simple and facile solvothermal method, which is composed of the core-shell ZnO@SnO2 nanoparticles. Thanks to the good match between the energy level of the SnO2 shell and the high electron mobility of the core ZnO nanoparticles, the PCE of inorganic perovskite solar cells has reached 14.35% (JSC: 16.45 mA cm-2, VOC: 1.11 V, FF: 79%), acting core-shell ZnO@SnO2 nanoparticles as the electron transfer layer. The core-shell ZnO@SnO2 nanoparticles size is 8.1 nm with the SnO2 shell thickness of 3.4 nm, and the electron mobility is seven times more than SnO2 nanoparticles. Meanwhile, the uniform core-shell ZnO@SnO2 nanoparticles is extremely favorable to the growth of inorganic perovskite films. These preliminary results strongly suggest the great potential of this novel electron transfer material in high-efficiency perovskite solar cells.

14.
J Am Chem Soc ; 141(35): 13948-13953, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31403287

RESUMO

Surface effects usually become negligible on the micrometer or sub-micrometer scale due to lower surface-to-bulk ratio compared to nanomaterials. In lead halide perovskites, however, their "soft" nature renders them highly responsive to the external field, allowing for extended depth scale affected by the surface. Herein, by taking advantage of this unique feature of perovskites we demonstrate a methodology for property manipulation of perovskite thin films based on secondary grain growth, where tuning of the surface induces the internal property evolution of the entire perovskite film. While in conventional microelectronic techniques secondary grain growth generally involves harsh conditions such as high temperature and straining, it is easily triggered in a perovskite thin film by a simple surface post-treatment, producing enlarged grain sizes of up to 4 µm. The resulting photovoltaic devices exhibit significantly enhanced power conversion efficiency and operational stability over a course of 1000 h and an ambient shelf stability of over 4000 h while maintaining over 90% of its original efficiency.

15.
Nano Lett ; 19(8): 5176-5184, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31310720

RESUMO

All-inorganic-based perovskites achieved by replacing the organic component with cesium (Cs) have drawn more attention because of their intrinsic inorganic stability. However, the cell efficiency in all-inorganic perovskite solar cells is still far below that in organic-inorganic hybrid perovskite-based devices. Here, we develop a new strategy to mediate the CsPbI2Br crystallization by directly doping copper(II) bromide (CuBr2) into a perovskite precursor. The incorporation of CuBr2 played a role in retarding the crystallization dynamics process of CsPbI2Br film, resulting in a high-quality all-inorganic perovskite film with enlarged grain size, improved carrier mobilities, and reduced trap states. The fabricated perovskite solar cells delivered a champion power conversion efficiency of 16.15%, which is the highest efficiency in CsPbI2Br based all-inorganic perovskite solar cells and largely higher than 13.24% for pristine CsPbI2Br based device. The developed doping method paves a new route to fabricate high-performance all-inorganic perovskite solar cells.

16.
Zhongguo Zhong Yao Za Zhi ; 44(9): 1895-1903, 2019 May.
Artigo em Chinês | MEDLINE | ID: mdl-31342719

RESUMO

To establish a mouse model of premature ovarian insufficiency( POI) with kidney deficiency and blood stasis pattern by Tripterygium wilfordii polyglycoside( TWP) gavage,and to evaluate the ovarian function and fertility of the model,in order to find Bushen Culuan Decoction therapeutic mechanism. 60 SPF level Blab/c female mice with normal estrous cycle were randomly divided into 6 groups of 10 each: blank group 1( BG1),blank group 2( BG2),blank fertility group( BFG),model group( MG),model recovery group( MRG) and model fertility group( MFG). The mice in three model groups were treated by gastric gavage with TWP suspension 40 mg·kg-1 twice a day for 14 days,while the mice in three blank groups were treated by gastric gavage with same volume normal saline for 14 days. The mice in BG1 and MG were sacrificed and dissected on day 15. The mice in BG2,BFG,MRG and MFG were returned normal feeding from day 15 and were sacrificed and dissected on day 29. The mice in BFG and MFG were cohabited with male mice with a ratio of 2 ∶1( female ∶male) from day 15. The general situation and estrous cycles of all mice were observed every day. Serum sex hormone levels,ovarian index,uterine index,ovarian morphology,follicle count,ovarian VEGF and ES index were observed within the mice in BG1,BG2,MG and MRG. Pregnancy rate,litter size,survival number of newborn mice and male-female proportion were reported within the mice in BFG and MFG. In model establishing stage,the body weight of mice significantly decreased( P <0. 05) in MG and MFG. Compared with BG1,the mice in model group had irregular estrous cycle,decreased ovarian and uterine indexes,less primordial and developing follicles,more atretic follicles,increased VEGF expression and decreased ES expression( P <0. 05). Compared with blank group 2,the mice in model recovery group had irregular estrous cycle,increased FSH level,decreased ovarian indexes,less primordial and developing follicles,more atretic follicles,increased VEGF expression( P<0. 05). Compared with blank fertility group,the mice in model fertility group had smaller litter size and newborn mice survival count( P<0. 05). Gastric gavage with TWP 40 mg·kg-1 twice a day for 14 days is a feasible way to establish a POI kidney deficiency and blood stasis pattern mouse model. The mice ovarian functions didn't recovery on day 14 after stopping TWP intervening,which could suggest the effectiveness of subsequent therapeutic intervention.


Assuntos
Modelos Animais de Doenças , Medicamentos de Ervas Chinesas/farmacologia , Insuficiência Ovariana Primária/tratamento farmacológico , Tripterygium/efeitos adversos , Animais , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Gravidez , Insuficiência Ovariana Primária/induzido quimicamente , Distribuição Aleatória
17.
Carbohydr Polym ; 221: 127-136, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31227151

RESUMO

Hemicelluloses are ß-(1→4)-linked backbone polysaccharides found in plant cell walls that include xyloglucans, xylans, mannans and glucomannans, and play important roles in plant tissue configuration. In this study, hemicelluloses were isolated from the apical, middle and basal segments of 6 m Phyllostachys edulis culm using KOH and DMSO extraction procedures, respectively. Chemical composition and structural characterization of hemicellulosic fractions were comparatively investigated by a combination of HPLC, GPC, FT-IR, 1H-, 13C-, HSQC NMR and TGA techniques. Our results show that the main chain of hemicellulose in P. edulis consists of glucuronoarabinoxylans (GAXs) with backbone 1, 4-ß-d-Xyl, and side chain arabinose, glucuronic acid and acetylation. Hemicellulose content and molecular weight increased with culm xylogenesis in P. edulis. Our results provide new insights on the dynamics of hemicellulose structure in culm xylogenesis in P. edulis.


Assuntos
Polissacarídeos/metabolismo , Sasa/metabolismo , Xilema/metabolismo , Acetilação , Peso Molecular , Polissacarídeos/química , Sasa/química , Xilanos/química , Xilanos/metabolismo , Xilema/citologia
18.
Zhongguo Zhong Yao Za Zhi ; 44(6): 1099-1103, 2019 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-30989970

RESUMO

Infertility caused by salpingitis is one of the main causes of secondary infertility in women. In recent years,the incidence has been increasing year by year. Modern medicine believes that this disease is a complication due to incomplete or delayed treatment of acute and chronic salpingitis,with no satisfactory drug therapy at present. Clinical therapies mainly include surgical treatment,interventional treatment and assisted reproductive technology. After summarizing the experience of predecessors and the clinical practice of treating infertility for many years,the author considers that the disease location is the cell veins,and the nature is mostly mixed of deficiency and excess. Kidney deficiency and blood stasis are the main pathogenesis of infertility caused by salpingitis. Blood stasis is the pathological basis,while kidney deficiency is the fundamental pathogenesis. Long-term kidney deficiency will lead to blood stasis,and blood stasis will aggravate kidney deficiency. Both of them are cause and effect to each other. Infertility caused by salpingitis is difficult to cure. Based on the theory of kidney deficiency and blood stasis,the basic principles of clinical treatment are tonifying kidney and activating blood circulation,removing blood stasis and dredging collaterals. Oral administration with traditional Chinese medicine combined with external therapies,such as enema,external application,acupuncture and moxibustion,have been achieved a good efficacy in repairing fallopian tube function and improving pregnancy rate. Therefore,the treatment of infertility caused by salpingitis based on " kidney deficiency and blood stasis" is worthy of further discussion in both clinical and experimental aspects.


Assuntos
Terapia por Acupuntura , Infertilidade Feminina , Salpingite , Feminino , Humanos , Rim , Medicina Tradicional Chinesa , Gravidez
19.
Nano Lett ; 19(3): 2066-2073, 2019 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-30803237

RESUMO

Addressing the toxicity issue in lead-based perovskite compounds by seeking other nontoxic candidate elements represents a promising direction to fabricate lead-free perovskite solar cells. Recently, Cs2AgBiBr6 double perovskite achieved by replacing two Pb2+ with Ag+ and Bi3+ in the crystal lattice has drawn much attention owing to the convenient substitution of its chemical compositions. Herein, the dependence of the optoelectronic properties and corresponding photovoltaic performance of Cs2AgBiBr6 thin films on the deposition methods of vacuum sublimation and solution processing is investigated. Compared to the vacuum sublimation based one, the solution-processed Cs2AgBiBr6 shows inherently higher crystallinity, narrower electronic bandgap, longer photoexcitation lifetime, and higher mobility. The excellent optoelectronic properties are attributed to the accurate composition stoichiometry of Cs2AgBiBr6 films based on solution processing. These merits enable the corresponding perovskite solar cells to deliver a champion power conversion efficiency (PCE) of 2.51%, which is the highest PCE in the Cs2AgBiBr6-based double perovskite solar cells to date. The finding in this work provides a clear clue that a precise composition stoichiometry could guarantee the formation of high quality multicomponent perovskite films.

20.
Artigo em Inglês | MEDLINE | ID: mdl-30696036

RESUMO

Due to rapid increases in socioeconomic development and the human population over the past few decades, the shallow lakes in China have suffered from eutrophication and poor water quality. The conditions in Lake Dianchi Caohai, which is in the northern part of Lake Dianchi, are considered the most serious. The ecological restoration of Lake Dianchi Caohai began in the late 1980s. Lake managers and the public have been puzzled by the lack of a significant response of the water quality to the flow pattern despite the tremendous investment in water quality improvements. Therefore, lake managers desperately need to understand the responses of pollutant behaviors to proposed management measures. In this paper, a depth-averaged two-dimensional hydrodynamic and water quality model based on hydrological data, measured lake bed elevation, and water quality data is developed to simulate the flow field and water quality of Lake Dianchi Caohai. This model was validated using water quality data from the Caohaizhongxin site in 2016, and a close agreement was found between the model results and observations. Wind-driven circulation in Lake Dianchi Caohai was observed in the model results, which revealed that the lake flow pattern was dominated by wind-driven circulation, while the inflow/outflow played only a subsidiary role during this period. The formation of the wind-driven current in Lake Dianchi Caohai could be roughly divided into three stages. The hydrodynamic processes connected with the distribution of chlorophyll a are evaluated and discussed to adequately understand the hydraulic mechanisms driving the accumulation of cyanobacteria. Moreover, we designed three scenarios after comparing all possible operation scenarios to analyze the contributions of each different operation scenario to the water quality improvements. The optimal ecological operation scenario which has the best impacts on the water quality, especially the reduction in Chla and NH3-N concentration, is proposed based on our comprehensive analysis. The water quality improvement and management suggestions proposed in this paper are based on lake flow patterns and make up for previous studies that did not consider the effects of hydraulic characteristics on water quality improvement in Lake Dianchi Caohai.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Recuperação e Remediação Ambiental/métodos , Eutrofização , Lagos/química , Lagos/microbiologia , Poluentes da Água/análise , Qualidade da Água , China
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