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1.
Adv Mater ; : e2000121, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32613674

RESUMO

Kesterite Cu2 ZnSnS4 is a promising photovoltaic material containing low-cost, earth-abundant, and stable semiconductor elements. However, the highest power conversion efficiency of thin-film solar cells based on Cu2 ZnSnS4 is only about 11% due to low open-circuit voltage and fill factor mainly caused by antisite defects and unfavorable heterojunction interface. In this work, a postannealing procedure is proposed to complete a Cd-alloyed Cu2 ZnSnS4 device. The postannealing to complete the device significantly enhances the performance of the indium tin oxide and promotes the moderate interdiffusion of elements between the layers in the device. As a result of the diffusion of Cu, Zn, In, and Sn, the interfacial electron and hole densities are improved, leading to the achievement of a suitable band alignment for carrier transport. The postannealing also reduces the interface traps and deep-level defects, contributing to decreased nonradiative recombination. Therefore, the open-circuit voltage and fill factor are both improved, and an efficiency over 12% for pure sulfide-based kesterite thin-film solar cells is obtained.

2.
ACS Appl Mater Interfaces ; 12(20): 22825-22834, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32326702

RESUMO

The one-dimensional photovoltaic absorber material Sb2S3 requires crystal orientation engineering to enable efficient carrier transport. In this work, we adopted the vapor transport deposition (VTD) method to fabricate vertically aligned Sb2S3 on a CdS buffer layer. Our work shows that such a preferential vertical orientation arises from the sulfur deficit of the CdS surface, which creates a beneficial bonding environment between exposed Cd2+ dangling bonds and S atoms in the Sb2S3 molecules. The CdS/VTD-Sb2S3 interface recombination is suppressed by such properly aligned ribbons at the interface. Compared to typical [120]-oriented Sb2S3 films deposited on CdS by the rapid thermal evaporation (RTE) method, the VTD-Sb2S3 thin film is highly [211]- and [121]-oriented and the performance of the solar cell is increased considerably. Without using any hole transportation layer, a conversion efficiency of 4.73% is achieved with device structure of indium tin oxide (ITO)/CdS/Sb2S3/Au. This work provides a potential way to obtain vertically aligned thin films on different buffer layers.

3.
Artigo em Inglês | MEDLINE | ID: mdl-32143412

RESUMO

Haze pollution in China is a serious environmental issue, which does harm both to people's health and to economic development. Simultaneously, as an important industrial development law, agglomeration may result in the increased concentration of manufacturing firms and, consequently, an increase in haze pollution. However, the positive externalities of agglomeration can also improve the efficiency of regional innovation, which curbs haze pollution. In this paper, we construct both theoretical and empirical models to investigate the effects of industrial manufacturing agglomeration on haze pollution. The results reveal the following: (1) By incorporating the effect of agglomeration and haze pollution into a general endogenous growth model, we show an inverted-U relationship between agglomeration and haze pollution on the balance growth path. (2) Based on data concerning haze pollution (PM2.5) and data from 285 Chinese cities, the empirical results verify the findings of the theoretical model. Further, we calculated the values of agglomeration variables, with respect to the inflection points of the inverted-U, which the cities need to reach in order to gain the specific agglomeration values required to enjoy the inhibition effect of agglomeration on haze pollution. (3) A heterogeneity analysis shows that the inverted-U relationship is more obvious among the cities in the middle and northeastern areas of China, as well as medium-size cities. (4) Cities' environmental regulation policies and high-quality institutional environments can restrain the positive effect of agglomeration on haze pollution. (5) Using three measures of innovation, it is also empirically found that innovation is the mechanism (mediator) between agglomeration and haze pollution.

4.
Artigo em Inglês | MEDLINE | ID: mdl-30961815

RESUMO

Primary sclerosing cholangitis (PSC) is a chronic, cholestatic liver disease of unknown cause. In the study, we found that duck circovirus (DuCV) induces PSC in natural and reproductive cases. PSC in DuCV naturally infected ducks was investigated by PCR and histopathology. A model of PSC was developed in one-day old duck by infection of DuCV. Effects on serum levels of liver enzymes and histology were evaluated, and DuCV tropism for bile duct in liver was analyzed by immuohistochemistry. Pathology observation of natural or reproductive DuCV infected ducks showed that the lesion of liver were characterized by cholangiocytic injuries and progressive fibrous obliteration of the biliary tree associated with lymphocytes infiltration. ALT, AST, ALP, GGT, ALB, TBIL and TP were significantly increased in serum of DuCV infected ducks. DuCV showed higher tropism for epithelial cells of bile duct than other cells in PSC.


Assuntos
Ductos Biliares/virologia , Doenças das Aves/fisiopatologia , Colangite Esclerosante/fisiopatologia , Colangite Esclerosante/virologia , Circovirus/fisiologia , Tropismo Viral/fisiologia , Animais , Ductos Biliares/citologia , Doenças das Aves/virologia , Colangite Esclerosante/imunologia , Circovirus/imunologia , Patos , Humanos , Fígado/patologia , Fígado/virologia , Linfócitos/imunologia
5.
Transbound Emerg Dis ; 65(5): 1170-1174, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29923685

RESUMO

Gyrovirus 3 (GyV3) has been identified in faeces from children with acute gastroenteritis. However, whether GyV3 is prevalent in poultry has not been determined to date. To the best of our knowledge, this study is the first to isolate GyV3 from commercial broiler chickens with transmissible viral proventriculitis (TVP) in China. The complete genome of the virus shares 98.4% sequence identity with the FecGy strain that causes acute gastroenteritis in children. Epidemiological investigation from 2013 to 2017 revealed that the infection rate of GyV3 reached 12.5% (42/336) in commercial broiler chickens with TVP, indicating that the infection of GyV3 was ubiquitous in chickens. The emergence of GyV3 in commercial broiler chickens should be highly concerning for public health.


Assuntos
Galinhas/virologia , Infecções por Circoviridae/veterinária , Gyrovirus/isolamento & purificação , Doenças das Aves Domésticas/virologia , Proventrículo/virologia , Animais , China/epidemiologia , Infecções por Circoviridae/epidemiologia , Fezes/virologia , Doenças das Aves Domésticas/epidemiologia
6.
ACS Appl Mater Interfaces ; 9(39): 34093-34100, 2017 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-28898576

RESUMO

A low-temperature solution-based process for depositing silver nanowire (AgNW) networks for use as transparent conductive top electrode is demonstrated. These AgNWs when applied to Cu2ZnSnS4 solar cells outperformed indium tin oxide as the top electrode. Thinner nanowires allow the use of lower temperatures during processing, while longer wires allow lowered sheet resistance for the same surface coverage of NWs, enhancing the transmittance/conductance trade-off. Conductive atomic force microscopy and percolation theory were used to study the quality of the NW network at the microscale. Our optimized network yielded a sheet resistance of 18 Ω/□ and ∼95% transmission across the entire wavelength range of interest for a deposition temperature as low as of 60 °C. Our results show that AgNWs can be used for low-temperature cell fabrication using cheap solution-based processes that could also be promising for other solar cells constrained to low processing temperatures such as organic and perovskite solar cells.

7.
ACS Appl Mater Interfaces ; 9(30): 25073-25081, 2017 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-28700216

RESUMO

Metal halide perovskite solar cells (PSCs) have undergone rapid progress. However, unstable performance caused by sensitivity to environmental moisture and high temperature is a major impediment to commercialization of PSCs. In the present work, a low-temperature, glass-glass encapsulation technique using high performance polyisobutylene (PIB) as the moisture barrier is investigated on planar glass/FTO/TiO2/FAPbI3/PTAA/gold perovskite solar cells. PIB was applied as either an edge seal or blanket layer. Electrical connections to the encapsulated PSCs were provided by either the FTO or Au layers. Results of a "calcium test" demonstrated that a PIB edge-seal effectively prevents moisture ingress. A shelf life test was performed and the PIB-sealed PSC was stable for at least 200 days. Damp heat and thermal cycling tests, in compliance with IEC61215:2016, were used to evaluate different encapsulation methods. Current-voltage measurements were performed regularly under simulated AM1.5G sunlight to monitor changes in PCE. The best results we have achieved to date maintained the initial efficiency after 540 h of damp heat testing and 200 thermal cycles. To the best of the authors' knowledge, these are among the best damp heat and thermal cycle test results for perovskite solar cells published to date. Given the modest performance of the cells (8% averaged from forward and reverse scans) especially with the more challenging FAPbI3 perovskite material tested in this work, it is envisaged that better stability results can be further achieved when higher performance perovskite solar cells are encapsulated using the PIB packaging techniques developed in this work. We propose that heat rather than moisture was the main cause of our PSC degradation. Furthermore, we propose that preventing the escape of volatile decomposition products from the perovskite solar cell materials is the key for stability. PIB encapsulation is a very promising packaging solution for perovskite solar cells, given its demonstrated effectiveness, ease of application, low application temperature, and low cost.

8.
Nat Commun ; 8: 15138, 2017 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-28469175

RESUMO

Innate immunity plays a pivotal role in virus infection. RIG-I senses viral RNA and initiates an effective innate immune response for type I interferon production. To transduce RIG-I-mediated antiviral signalling, a mitochondrial protein MAVS forms prion-like aggregates to activate downstream kinases and transcription factors. However, the activation mechanism of RIG-I is incompletely understood. Here we identify two ubiquitin enzymes Ube2D3 and Ube2N through chromatographic purification as activators for RIG-I on virus infection. We show that together with ubiquitin ligase Riplet, Ube2D3 promotes covalent conjugation of polyubiquitin chains to RIG-I, while Ube2N preferentially facilitates production of unanchored polyubiquitin chains. In the presence of these polyubiquitin chains, RIG-I induces MAVS aggregation directly on the mitochondria. Our data thus reveal two essential polyubiquitin-mediated mechanisms underlying the activation of RIG-I and MAVS for triggering innate immune signalling in response to viral infection in cells.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteína DEAD-box 58/metabolismo , Imunidade Inata/genética , RNA Viral/imunologia , Enzimas de Conjugação de Ubiquitina/genética , Ubiquitina-Proteína Ligases/genética , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Animais , Proteína DEAD-box 58/imunologia , Células HEK293 , Humanos , Imunidade Inata/imunologia , Camundongos , Agregados Proteicos , Enzimas de Conjugação de Ubiquitina/imunologia , Ubiquitina-Proteína Ligases/imunologia , Vesiculovirus/genética
9.
ACS Appl Mater Interfaces ; 8(13): 8520-6, 2016 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-26954448

RESUMO

An electron transport layer is essential for effective operation of planar perovskite solar cells. In this Article, PW12-TiO2 composite was used as the electron transport layer for the planar perovskite solar cell in the device structure of fluorine-doped tin oxide (FTO)-glass/PW12-TiO2/perovskite/spiro-OMeTAD/Au. A proper downward shift of the conduction band minimum (CBM) enhanced electron extraction from the perovskite layer to the PW12-TiO2 composite layer. Consequently, the common hysteresis effect in TiO2-based planar perovskite solar cells was significantly reduced and the open circuit voltage was greatly increased to about 1.1 V. Perovskite solar cells using the PW12-TiO2 compact layer showed an efficiency of 15.45%. This work can contribute to the studies on the electron transport layer and interface engineering for the further development of perovskite solar cells.

10.
Zhongguo Dang Dai Er Ke Za Zhi ; 18(1): 51-4, 2016 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-26781413

RESUMO

OBJECTIVE: To investigate the distribution of respiratory viruses on throat swabs in hospitalized children with acute lower respiratory tract infection (ALRTI). METHODS: A total of 5,150 children with ALRTI who were admitted to Hebei Children's Hospital between March 2014 and February 2015 were enrolled to investigate the distribution of respiratory viruses in children with ALRTI. Direct immunofluorescence assay was performed for throat swabs from these children to detect influenza virus A (FA), influenza virus B (FB), adenovirus (ADV), respiratory syncytial virus (RSV), and parainfluenza virus types 1, 2, and 3 (PIV-1, PIV-2, and PIV-3). RESULTS: Of all the 5,150 throat swabs from hospitalized children, 2,155 (41.84%) had positive virus detection results. RSV had the highest detection rate (1,338 cases/25.98%), followed by PIV-3 (439 cases/8.52%) and FA (166 cases/3.22%), and 29 patients had mixed infection with 2 viruses. With the increasing age, the detection rates of viruses tended to decrease (χ2=279.623; P<0.01). The positive rate of RSV increased gradually from September, and reached the peak value (60.09%) in November; the lowest positive rate occurred in June (1.51%). The positive rate of PIV-3 was the highest in May (21.38%) and the lowest in November (1.77%). CONCLUSIONS: The distribution of viruses in children with ALRTI varies with age and season, with RSV prevalence in autumn and winter and PIV-3 prevalence in spring and summer. RSV is the most common viral pathogen that causes ALRTI in hospitalized children.


Assuntos
Infecções Respiratórias/virologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Orthomyxoviridae/isolamento & purificação , Vírus da Parainfluenza 3 Humana/isolamento & purificação , Vírus Sinciciais Respiratórios/isolamento & purificação , Estações do Ano
11.
ACS Appl Mater Interfaces ; 7(41): 22868-73, 2015 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-26418196

RESUMO

Back contact modification plays an important role in improving energy conversion efficiency of Cu2ZnSnS4 (CZTS) thin film solar cells. In this paper, an ultrathin carbon layer is introduced on molybdenum (Mo)-coated soda lime glass (SLG) prior to the deposition of CZTS precursor to improve the back contact and therefore enhance CZTS solar cell efficiency. By introducing this layer, the short circuit current (Jsc) and device conversion efficiency increase for both nonvacuum (sol-gel) and vacuum (sputtering) methods. Specifically, for the sol-gel based process, Jsc increases from 13.60 to 16.96 mA/cm(2) and efficiency from 4.47% to 5.52%, while for the sputtering based process, Jsc increases from 17.50 to 20.50 mA/cm(2) and efficiency from 4.10% to 5.20%. Furthermore, introduction of this layer does not lead to any deterioration of either open circuit voltage (Voc) or fill factor (FF).

12.
ACS Appl Mater Interfaces ; 7(26): 14376-83, 2015 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-26080031

RESUMO

A facile sol-gel and selenization process has been demonstrated to fabricate high-quality single-phase earth abundant kesterite Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaic absorbers. The structure and band gap of the fabricated CZTSSe can be readily tuned by varying the [S]/([S] + [Se]) ratios via selenization condition control. The effects of [S]/([S] + [Se]) ratio on device performance have been presented. The best device shows 8.25% total area efficiency without antireflection coating. Low fill factor is the main limitation for the current device efficiency compared to record efficiency device due to high series resistance and interface recombination. By improving film uniformity, eliminating voids, and reducing the Mo(S,Se)2 interfacial layer, a further boost of the device efficiency is expected, enabling the proposed process for fabricating one of the most promising candidates for kesterite solar cells.

13.
J Phys Chem Lett ; 6(19): 3931-4, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26722894

RESUMO

In this work, the use of a high bandgap perovskite solar cell in a spectrum splitting system is demonstrated. A remarkable energy conversion efficiency of 23.4% is achieved when a CH3NH3PbBr3 solar cell is coupled with a 22.7% efficient silicon passivated emitter rear locally diffused solar cell. Relative enhancements of >10% are demonstrated by CH3NH3PbBr3/CH3NH3PbI3 and CH3NH3PbBr3/multicrystalline-screen-printed-Si spectral splitting systems with tandem efficiencies of 13.4% and 18.8%, respectively. The former is the first demonstration of an all perovskite split spectrum system. The CH3NH3PbBr3 cell on a mesoporous structure was fabricated by the vapor-assisted method while the planar CH3NH3PbI3 cell was fabricated by the gas-assisted method. This work demonstrates the advantage of the higher voltage output from the high bandgap CH3NH3PbBr3 cell and its suitability in a tandem system.

14.
Asian-Australas J Anim Sci ; 27(4): 471-8, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25049976

RESUMO

Investigating gene expression of immune cells of whole blood or peripheral blood mononuclear cells (PBMC) under polyinosinic:polycytidylic acid (poly I:C) stimulation is valuable for understanding the immune response of organism to RNA viruses. Quantitative real-time PCR (qRT-PCR) is a standard method for quantification of gene expression studies. However, the reliability of qRT-PCR data critically depends on proper selection of reference genes. In the study, using two different analysis programs, geNorm and NormFinder, we systematically evaluated the gene expression stability of six candidate reference genes (GAPDH, ACTB, B2M, RPL4, TBP, and PPIA) in samples of whole blood and PBMC with or without poly I:C stimulation. Generally, the six candidate genes performed a similar trend of expression stability in the samples of whole blood and PBMC, but more stably expressed in whole blood than in PBMC. geNorm ranked B2M and PPIA as the best combination for gene expression normalization, while according to NormFinder, TBP was ranked as the most stable reference gene, followed by B2M and PPIA. Comprehensively considering the results from the two programs, we recommended using the geometric mean of the three genes, TBP, PPIA and B2M, to normalize the gene expression of whole blood and PBMC with poly I:C stimulation. Our study is the first detailed survey of the gene expression stability in whole blood and PBMC with or without poly I:C stimulation and should be helpful for investigating the molecular mechanism involved in porcine whole blood and PBMC in response to poly I:C stimulation.

15.
Nanotechnology ; 25(19): 195701, 2014 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-24762660

RESUMO

The mechanism of crystallization of Cu2ZnSnS4 (CZTS) made by the sulfurization of a sputtered Zn/CuSn stack was studied by transmission electron microscopy. At 250 °C, the Zn buried at the bottom of the metallic stack was found to be driven to the upper layer by alloying with Cu and reacting with S to form ZnS. At 500 °C, CZTS was found to be formed and elemental Sn was observed in the vicinity of the back contact region, while large quantities of Cu2S and ZnS were segregated at the film surface. At 575 °C, Cu2SnS3 was found, while all the elemental Sn had vanished. Upon extending the duration of the annealing to 10 min, at 575 °C, all the secondary phases except ZnS were consumed and the CZTS formation was completed, while around 200 nm of MoS2 was formed between the CZTS layer and Mo back contact. The finished solar cell exhibits an efficiency of 2.66%, an open-circuit voltage of 666.9 mV and a short-circuit current density of 9.14 mA cm⁻². The solar cell performance is possibly limited by the thick MoS2 layer and the large density of voids in the back contact region due to the Sn loss at high sulfurization temperatures.

16.
Nanoscale ; 5(16): 7499-504, 2013 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-23832085

RESUMO

All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction.


Assuntos
Pontos Quânticos , Silício/química , Energia Solar , Dióxido de Silício/química , Luz Solar
17.
Nanoscale Res Lett ; 7: 193, 2012 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-22436303

RESUMO

The concept of third-generation photovoltaics is to significantly increase device efficiencies whilst still using thin-film processes and abundant non-toxic materials. A strong potential approach is to fabricate tandem cells using thin-film deposition that can optimise collection of energy in a series of cells with decreasing band gap stacked on top of each other. Quantum dot materials, in which Si quantum dots (QDs) are embedded in a dielectric matrix, offer the potential to tune the effective band gap, through quantum confinement, and allow fabrication of optimised tandem solar cell devices in one growth run in a thin-film process. Such cells can be fabricated by sputtering of thin layers of silicon rich oxide sandwiched between a stoichiometric oxide that on annealing crystallise to form Si QDs of uniform and controllable size. For approximately 2-nm diameter QDs, these result in an effective band gap of 1.8 eV. Introduction of phosphorous or boron during the growth of the multilayers results in doping and a rectifying junction, which demonstrates photovoltaic behaviour with an open circuit voltage (VOC) of almost 500 mV. However, the doping behaviour of P and B in these QD materials is not well understood. A modified modulation doping model for the doping mechanisms in these materials is discussed which relies on doping of a sub-oxide region around the Si QDs.

18.
Nanoscale Res Lett ; 5(11): 1762-1767, 2010 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-21124642

RESUMO

As an important step towards the realisation of silicon-based tandem solar cells using silicon quantum dots embedded in a silicon dioxide (SiO(2)) matrix, single-junction silicon quantum dot (Si QD) solar cells on quartz substrates have been fabricated. The total thickness of the solar cell material is 420 nm. The cells contain 4 nm diameter Si quantum dots. The impacts of post-metallisation treatments such as phosphoric acid (H(3)PO(4)) etching, nitrogen (N(2)) gas anneal and forming gas (Ar: H(2)) anneal on the cells' electrical and photovoltaic properties are investigated. The Si QD solar cells studied in this work have achieved an open circuit voltage of 410 mV after various processes. Parameters extracted from dark I-V, light I-V and circular transfer length measurement (CTLM) suggest limiting mechanism in the Si QD solar cell operation and possible approaches for further improvement.

19.
Nanotechnology ; 19(24): 245201, 2008 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-21825804

RESUMO

Silicon (Si) quantum dot (QD) materials have been proposed for 'all-silicon' tandem solar cells. In this study, solar cells consisting of phosphorus-doped Si QDs in a SiO(2) matrix deposited on p-type crystalline Si substrates (c-Si) were fabricated. The Si QDs were formed by alternate deposition of SiO(2) and silicon-rich SiO(x) with magnetron co-sputtering, followed by high-temperature annealing. Current tunnelling through the QD layer was observed from the solar cells with a dot spacing of 2 nm or less. To get the required current densities through the devices, the dot spacing in the SiO(2) matrix had to be 2 nm or less. The open-circuit voltage was found to increase proportionally with reductions in QD size, which may relate to a bandgap widening effect in Si QDs or an improved heterojunction field allowing a greater split of the Fermi levels in the Si substrate. Successful fabrication of (n-type) Si QD/(p-type) c-Si photovoltaic devices is an encouraging step towards the realization of all-silicon tandem solar cells based on Si QD materials.

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