Insight into the Role of Rb Doping for Highly Efficient Kesterite Cu2ZnSn(S,Se)4 Solar Cells.

Various copper-related defects in the absorption layer have been a key factor impeding the enhancement of the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. Alkali metal doping is considered to be a good strategy to ameliorate this problem. In this article, Rb-doped CZTSSe (RCZTSSe) thin films were synthesized using the sol-gel technique. The results show that the Rb atom could successfully enter into the CZTSSe lattice and replace the Cu atom. According to SEM results, a moderate amount of Rb doping aided in enhancing the growth of grains in CZTSSe thin films. It was proven that the RCZTSSe thin film had the densest surface morphology and the fewest holes when the doping content of Rb was 2%. In addition, Rb doping successfully inhibited the formation of CuZn defects and correlative defect clusters and promoted the electrical properties of RCZTSSe thin films. Finally, a remarkable power conversion efficiency of 7.32% was attained by the champion RCZTSSe device with a Rb content of 2%. Compared with that of un-doped CZTSSe, the efficiency improved by over 30%. This study offers new insights into the influence of alkali metal doping on suppressing copper-related defects and also presents a viable approach for improving the efficiency of CZTSSe devices.

Up-regulation of growth-related gene expression in tobacco by volatile compounds released by Bacillus velezensis WSW007.

In order to investigate the mechanism of plant growth promoting (PGP) effects of strain Bacillus velezensis WSW007, its PGP traits and production of volatile organic compounds (VOCs) were tested. The effects of VOCs produced by strain WSW007 on plant growth were observed by co-culturing this strain with tobacco seedlings in I-plates. Meanwhile, the effects of VOCs on tobacco gene expression were analysed by a transcriptome analysis and VOCs were identified by solid phase micro extraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) analysis. As results, strains WSW007 produced acetic acid and siderophore, and could solubilize phosphate; while it also significantly increased the fresh weight of tobacco seedlings via production of VOCs. In transcriptome analysis, plants co-cultured with strain WSW007 presented the highest up-regulated expression for the genes involved in plant growth and development processes, implying that the bacterial VOCs played a role as regulator of plant gene expression. Conclusively, the up-regulation in expression of growth- and development-related genes via VOCs production is an important PGP mechanism in strain B. velezensis WSW007.

Genome sequence of Streptomyces sp. strain TOR3209, a rhizosphere microecology regulator isolated from tomato rhizosphere.

Streptomyces sp. strain TOR3209, isolated from tomato rhizosphere, can regulate the rhizosphere microecology of a variety of crops. Strain TOR3209 could improve plant systemic resistance and promote plant growth. Here, the genome sequence of strain TOR3209 is reported, providing the molecular biological basis of the regulation mechanism of rhizosphere microecology.

Optimization of the Selenization Temperature on the Mn-Substituted Cu2ZnSn(S,Se)4 Thin Films and Its Impact on the Performance of Solar Cells.

Cu2ZnSn(S,Se)4 (CZTSSe) films are considered to be promising materials in the advancement of thin-film solar cells. In such films, the amounts of S and Se control the bandgap. Therefore, it is crucial to control the concentration of S/Se to improve efficiency. In this study, Cu2MnxZn1-xSnS4 (CMZTS) films were fabricated using the sol-gel method and treated in a Se environment. The films were post-annealed in a Se atmosphere at various temperature ranges from 300 °C to 550 °C at intervals of 200 °C for 15 min to obtain Cu2MnxZn1-xSn(S,Se)4 (CMZTSSe). The elemental properties, surface morphology, and electro-optical properties of the CMZTSSe films were investigated in detail. The bandgap of the CMZTSSe films was adjustable in the scope of 1.11-1.22 eV. The structural propeties and phase purity of the CMZTSSe films were analyzed by X-ray diffraction and Raman analysis. High-quality CMZTSSe films with large grains could be acquired by suitably changing the selenization temperature. Under the optimized selenization conditions, the efficiency of the fabricated CMZTSSe device reached 3.08%.

Volatile Organic Compounds of Streptomyces sp. TOR3209 Stimulated Tobacco Growth by Up-Regulating the Expression of Genes Related to Plant Growth and Development.

To investigate the mechanism underlying the plant growth-promoting (PGP) effects of strain Streptomyces sp. TOR3209, PGP traits responsible for indoleacetic acid production, siderophore production, and phosphate solubilization were tested by culturing the strain TOR3209 in the corresponding media. The effects of volatile organic compounds (VOCs) produced by the strain TOR3209 on plant growth were observed by co-culturing this strain with tobacco seedlings in I-plates. Meanwhile, the effects of VOCs on tobacco gene expression were estimated by performing a transcriptome analysis, and VOCs were identified by the solid-phase micro-extraction (SPME) method. The results showed positive reactions for the three tested PGP traits in the culture of strain TOR3209, while the tobacco seedlings co-cultured with strain TOR3209 revealed an increase in the fresh weight by up to 100% when compared to that of the control plants, demonstrating that the production VOCs was also a PGP trait. In transcriptome analysis, plants co-cultured with strain TOR3209 presented the highest up-regulated expression of the genes involved in plant growth and development processes, implying that the bacterial VOCs played a role as a regulator of plant gene expression. Among the VOCs produced by the strain TOR3209, two antifungal molecules, 2,4-bis(1,1-dimethylethyl)-phenol and hexanedioic acid dibutyl ester, were found as the main compounds. Conclusively, up-regulation in the expression of growth- and development-related genes via VOCs production is an important PGP mechanism in strain TOR3209. Further efforts to explore the effective VOCs and investigate the effects of the two main VOCs in the future are recommended.

Insight into the Effect of Selenization Temperature for Highly Efficient Ni-Doped Cu2ZnSn(S,Se)4 Solar Cells.

Cu2Ni0·05Zn0·95Sn(S,Se)4 (CNZTSSe) films were synthesized on Mo-coated glass substrates by the simple sol-gel means combined with the selenization process, and CNZTSSe-based solar cells were successfully prepared. The effects of selenization temperature on the performance and the photoelectric conversion efficiency (PCE) of the solar cells were systematically studied. The results show that the crystallinity of films increases as the selenization temperature raises based on nickel (Ni) doping. When the selenization temperature reached 540 °C, CNZTSSe films with a large grain size and a smooth surface can be obtained. The Se doping level gradually increased, and Se occupied the S position in the lattice as the selenization temperature was increased so that the optical band gap (Eg) of the CNZTSSe film could be adjusted in the range of 1.14 to 1.06 eV. In addition, the Ni doping can inhibit the deep level defect of SnZn and the defect cluster [2CuZn + SnZn]. It reduces the carrier recombination path. Finally, at the optimal selenization temperature of 540 °C, the open circuit voltage (Voc) of the prepared device reached 344 mV and the PCE reached 5.16%.

Metagenomic assembly reveals hosts and mobility of common antibiotic resistome in animal manure and commercial compost.

BACKGROUND: Antibiotics and antibiotic resistance genes (ARGs) used in intensive animal farming threaten human health worldwide; however, the common resistome, ARG mobility, and ARG host composition in different animal manures and mixed manure composts remain unclear. In the present study, metagenomic assembly and cross-sample mapping were used to comprehensively decipher the common resistome and its potential mobility and hosts in animal manure and composts. RESULTS: In total, 201 ARGs were shared among different animal (layer, broiler, swine, beef cow, and dairy cow) manures and accounted for 86-99% of total relative abundance of ARGs. Except for multidrug, sulfonamide, and trimethoprim resistance genes, the relative abundance of most ARGs in composts was significantly lower than that in animal manure. Procrustes analysis indicated that antibiotic residues positively correlated with ARG composition in manure but not in composts. More than 75% ARG subtypes were shared between plasmids and chromosomes in our samples. Transposases could play a pivotal role in mediating the transfer of ARGs between different phyla in animal manure and composting. Cross-sample mapping to contigs carrying ARGs showed that the hosts of common resistome in manure had preference on animal species, and the dominant genus of ARG host shifted from Enterococcus in manure to Pseudomonas in composts. The broad host range and linking with diverse mobile genetic elements (MGEs) were two key factors for ARGs, such as sul1 and aadA, which could survive during composting. The multidrug resistance genes represented the dominant ARGs in pathogenic antibiotic-resistant bacteria in manure but could be effectively controlled by composting. CONCLUSIONS: Our experiments revealed the common resistome in animal manure, classified and relative quantified the ARG hosts, and assessed the mobility of ARGs. Composting can mitigate ARGs in animal manure by altering the bacterial hosts; however, persistent ARGs can escape from the removal because of diverse host range and MGEs. Our findings provide an overall background for source tracking, risk assessment, and control of livestock ARGs.

A Study on the Effects of Selenization Temperature on the Properties of Na-Doped Cu2ZnSn(S,Se)4 Thin Film and Its Correlation with the Performance of Solar Cells.

In this study, we prepared Na-doped Cu2ZnSn(S,Se)4 [noted as (Na0.1Cu0.9)2ZnSn(S,Se)4] films on the Mo substrate using a simple and cheap sol-gel method together with the post-annealing technique. The effects of selenization temperature on the properties of Na-doped Cu2ZnSn(S,Se)4 were surveyed. The results indicated that some sulfur atoms in the films were substituted by selenium atoms by increasing the selenization temperature, and all films selenized at different temperatures had a kesterite structure. As the selenization temperature increased from 520 to 560 °C, the band gaps of the film can be tuned from 1.03 to 1 eV. The film with better morphology and opto-electrical properties can be obtained at an intermediate selenization temperature range (e.g., 540 °C), which had the lowest resistivity of 47.7 Ω cm, Hall mobility of 4.63 × 10-1 cm2/Vs, and carrier concentration of 2.93 × 1017 cm-3. Finally, the best power conversion efficiency (PCE) of 4.82% was achieved with an open circuit voltage (Voc) of 338 mV, a short circuit current density (Jsc) of 27.16 mA/cm2 and a fill factor (FF) of 52.59% when the selenization temperature was 540 °C.

Enhancing the Performance of Aqueous Solution-Processed Cu2ZnSn(S,Se)4 Photovoltaic Materials by Mn2+ Substitution.

In this work, the Cu2MnxZn1-xSn(S,Se)4 (0 ≤ x ≤ 1) (CMZTSSe) alloy films were fabricated by a sol-gel method. Meanwhile, the effects of Mn substitution on the structural, morphological, electrical, optical, and device performance were studied systematically. The clear phase transformation from Cu2ZnSn(S,Se)4 (CZTSSe) with kesterite structure to Cu2MnSn(S,Se)4 (CMTSSe) with stannite structure was observed as x = 0.4. The scanning electron microscope (SEM) results show that the Mn can facilitate the grain growth of CMZTSSe alloy films. Since the x was 0.1, the uniform, compact, and smooth film was obtained. The results show that the band gap of the CMZTSSe film with a kesterite structure was incessantly increased in a scope of 1.024-1.054 eV with the increase of x from 0 to 0.3, and the band gap of the CMZTSSe film with stannite structure was incessantly decreased in a scope of 1.047-1.013 eV with the increase of x from 0.4 to 1. Meanwhile, compared to the power conversion efficiency (PCE) of pure CZTSSe device, the PCE of CMZTSSe (x = 0.1) device is improved from 3.61% to 4.90%, and about a maximum enhanced the open-circuit voltage (VOC) of 30 mV is achieved. The improvement is concerned with the enhancement of the grain size and decrease of the Cu instead of Zn (CuZn) anti-site defects. Therefore, it is believed that the adjunction of a small amount of Mn may be an appropriate approach to improve the PCE of CZTSSe solar cells.

Substitution of Ag for Cu in Cu2ZnSn(S,Se)4: Toward Wide Band Gap Absorbers with Low Antisite Defects for Thin Film Solar Cells.

Cation substitution is a promising approach to reduce the antisite defects and further improve the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) cells. In this paper, silver (Ag) has been introduced into Cu2ZnSn(S,Se)4 (CZTSSe) thin film to replace Cu partially and form (Cu1-xAgx)2ZnSn(S,Se)4 (0 ≤ x ≤ 1) (CAZTSSe) alloy films by combination of solution method and a rapid annealing technique. The fundamental properties of the mixed Ag-Cu kesterite compound are systematically reported as a function of the Ag/(Ag+Cu) ratio. The results show that band gap of kesterite CAZTSSe is incessantly increased by adjusting the Ag doping content, indicating that the CAZTSSe alloy film is a potentially applicable bandgap grading absorption layers material to obtain higher CZTSSe device. Furthermore, CAZTSSe alloy films with better electrical performance were also obtained by adjusting the Ag content during film fabrication. Finally, we also observed an increment in open circuit voltage (Voc) by 160 mV and an accompanying rise in device efficiency from 4.24 to 5.95%. The improvement is correlated to the improved grain size and decreased antisite defects of Cu instead of Zn site (CuZn) in the lattice. The Voc enhancement evidences that the solution method is facile and viable to achieve proper cation substitution toward higher efficiency kesterite solar cells. In addition, the CAZTSSe cell also displays better charge collection performance because of the higher fill factor (FF) and power conversion efficiency (PCE). Therefore, it can be concluded that the doping of Ag is a potentially appropriate method to reduce the Cuzn antisite defects of CZTSSe and improve efficiency of CZTSSe device.

Streptomyces sp. strain TOR3209: a rhizosphere bacterium promoting growth of tomato by affecting the rhizosphere microbial community.

Aiming at revealing the possible mechanism of its growth promoting effect on tomato, the correlations among Streptomyces sp. TOR3209 inoculation, rhizobacteriome, and tomato growth/production traits were investigated in this study. By analyses of Illumina sequencing and plate coating, differences in rhizosphere microbial communities were found in different growth stages and distinct inoculation treatments. The plant biomass/fruit yields and relative abundances of families Flavobacteriaceae, Sphingobacteriaceae, Polyangiaceae and Enterobacteriaceae in treatments T (tomato inoculated with TOR3209) and TF (tomato inoculated with TOR3209 + organic fertilizer) were higher than that in the controls (CK and CK+ organic fertilizer), respectively. The analysis of Metastats and LEfSe revealed that the genera Flavobacterium and Sorangium in seedling stage, Klebsiella in flowering stage, Collimonas in early fruit setting stage, and genera Micrococcaceae, Pontibacte and Adhaeribacter in late fruit setting stage were the most representative rhizobacteria that positively responded to TOR3209 inoculation. By cultivation method, five bacterial strains positively correlated to TOR3209 inoculation were isolated from rhizosphere and root endosphere, which were identified as tomato growth promoters affiliated to Enterobacter sp., Arthrobacter sp., Bacillus subtilis, Rhizobium sp. and Bacillus velezensis. In pot experiment, TOR3209 and B. velezensis WSW007 showed joint promotion to tomato production, while the abundance of inoculated TOR3209 was dramatically decreased in rhizosphere along the growth of tomato. Conclusively, TOR3209 might promote the tomato production via changing of microbial community in rhizosphere. These findings provide a better understanding of the interactions among PGPR in plant promotion.

Investigation on the Selenization Treatment of Kesterite Cu2Mg0.2Zn0.8Sn(S,Se)4 Films for Solar Cell.

High-selenium Cu2Mg0.2Zn0.8Sn(S,Se)4 (CMZTSSe) films were prepared on a soda lime glass substrate using the sol-gel spin coating method, followed by selenization treatment. In this work, we investigated the effects of selenization temperature and selenization time on the crystal quality, and electrical and optical properties of CMZTSSe films. The study on the micro-structure by XRD, Raman, X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS) analysis showed that all CMZTSSe samples had kesterite crystalline structure. In addition, the crystalline quality of CMZTSSe is improved and larger Se takes the site of S in CMZTSSe with the increase of selenization temperature and selenization time. When increasing the selenization temperature from 500 to 530 °C and increasing the annealing time from 10 to 15 min, the morphological studies showed that the microstructures of the films were dense and void-free. When further increasing the temperature and time, the crystalline quality of the films began to deteriorate. In addition, the bandgaps of CMZTSSe are tuned from 1.06 to 0.93 eV through adjusting the selenization conditions. When CMZTSSe samples are annealed at 530 °C for 15 min under Se atmosphere, the crystal quality and optical-electrical characteristics of CMZTSSe will be optimal, and the grain size and carrier concentration reach maximums of 1.5-2.5 µm and 6.47 × 1018 cm-3.

Investigation of Optimum Mg Doping Content and Annealing Parameters of Cu2MgxZn1-xSnS4 Thin Films for Solar Cells.

Cu2MgxZn1-xSnS4 (0 ≤ x ≤0.6) thin films were prepared by a simple, low-temperature (300 °C) and low-cost sol-gel spin coating method followed by post-annealing at optimum conditions. We optimized the annealing conditions and investigated the effect of Mg content on the crystalline quality, electrical and optical performances of the Cu2MgxZn1-xSnS4 thin films. It was found that the Cu2MgxZn1-xSnS4 film annealed at 580 °C for 60 min contained large grain, less grain boundaries and high carrier concentration. Pure phase kesterite Cu2MgxZn1-xSnS4 (0 ≤ x ≤ 0.6) thin films were obtained by using optimal annealing conditions; notably, the smaller Zn2+ ions in the Cu2ZnSnS4 lattice were replaced by larger Mg2+ ions. With an increase in x from 0 to 0.6, the band gap energy of the films decreased from 1.43 to 1.29 eV. When the ratio of Mg/Mg + Zn is 0.2 (x = 0.2), the grain size of Cu2MgxZn1-xSnS4 reaches a maximum value of 1.5 µm and the surface morphology is smooth and dense. Simultaneously, the electrical performance of Cu2MgxZn1-xSnS4 thin film is optimized at x = 0.2, the carrier concentration reaches a maximum value of 3.29 × 1018 cm-3.

Synthesis of simple, low cost and benign sol-gel Cu2In x Zn1-x SnS4 alloy thin films: influence of different rapid thermal annealing conditions and their photovoltaic solar cells.

Cu2In x Zn1-x SnS4 (x = 0.4) alloy thin films were synthesized on soda lime glass (SLG) substrate by a simple low-cost sol-gel method followed by a rapid annealing technique. The influence of sulfurization temperature and sulfurization time on the structure, morphology, optical and electrical properties of Cu2In x Zn1-x SnS4 thin films was investigated in detail. The XRD and Raman results indicated that the crystalline quality of the Cu2In x Zn1-x SnS4 alloy thin films was improved, accompanied by metal deficiency, particularly tin loss with increasing the sulfurization temperature and sulfurization time. From absorption spectra it is found that the band gaps of all Cu2In x Zn1-x SnS4 films are smaller than that (1.5 eV) of the pure CZTS film due to In doping, and the band gap of the Cu2In x Zn1-x SnS4 films can be tuned in the range of 1.38 to 1.19 eV by adjusting the sulfurization temperature and sulfurization time. Hall measurement results showed that all Cu2In x Zn1-x SnS4 alloy thin films showed p-type conductivity characteristics, the hole concentration decreased and the mobility increased with the increase of sulfurization temperature and sulfurization time, which is attributed to the improvement of the crystalline quality and the reduction of grain boundaries. Finally, the Cu2In x Zn1-x SnS4 film possessing the best p-type conductivity with a hole concentration of 9.06 × 1016 cm-3 and a mobility of 3.35 cm2 V-1 s-1 was obtained at optimized sulfurization condition of 580 °C for 60 min. The solar cell using Cu2In x Zn1-x SnS4 as the absorber obtained at the optimized sulfurization conditions of 580 °C for 60 min demonstrates a power conversion efficiency of 2.89%. We observed an increment in open circuit voltage by 90 mV. This work shows the promising role of In in overcoming the low V oc issue in Cu-kesterite thin film solar cells.

Summary of 32 patients with cardiac syndrome X treated by TCM therapy of regulating qi relieving chest stuffiness and promoting blood circulation.

OBJECTIVE: To evaluate the clinical effect of Liqi Kuanxiong Huoxue method LKH, traditional Chinese medicine, TCM therapeutic method for regulating qi, relieving chest stuffiness and promoting blood circulation) in treating patients with cardiac syndrome X (CSX). METHODS: The prospective, non-randomized controlled study was conducted on 51 selected patients with CSX, who were non-randomly assigned to 2 groups, the treated group treated with LKH in addition to the conventional treatment (32 patients), and the control group treated with conventional treatment (19 patients) like nitrate, diltiazem hydrochloride, etc. The treatment course was 14 days. The changes of such symptoms as angina pectoris, TCM syndrome and indexes of treadmill exercise test before and after treatment were observed. RESULTS: After treatment, such symptoms as chest pain and stuffy feeling and palpitation in the treated group were improved more than those in the control group (P<0.05); the total effective rate on angina pectoris and TCM syndrome in the treated group was better than that in the control group (P<0.05). The treadmill exercise test showed that the maximal metabolic equivalent (Max MET), the time of angina onset and ST segment depression by 0.1 mV were obviously improved after treatment in both groups, but the improvement in the treated group was better than that in the control group respectively (P<0.05). CONCLUSION: The LKH method could reduce the frequency of angina attacks and improve the clinical condition of patients with CSX.

[Comparative analysis on results of treadmill test in patients of coronary heart disease caused angina pectoris with Qi-Yin deficiency syndrome with or without accompanied phlegm and blood stasis syndrome].

OBJECTIVE: To explore the objective special features and role of various indexes of treadmill exercise test (TET) in patients of coronary heart disease (CHD) caused angina pectoris with Qi-Yin deficiency syndrome (QYD) with or without accompanied phlegm and blood stasis syndrome (PBS), to provide references for preventing and treating CHD in clinical practice. METHODS: One hundred and one patients, whose diagnosis measured to the diagnostic standard and the inclusion criteria of angina pectoris and CHD, were classified according to their TCM syndrome type to two groups, the QYD without PBS group (49 cases) and the QYD with PBS group (52 cases). TET was conducted on all the patients. The relative parameters were measured and compared. RESULTS: As compared with the QYD without PBS group, in the QYD with PBS group, (1) the TET positive rate was higher; (2) total exercise time was lesser; (3) the maximal metabolic equivalent (Max MET) was lower; (4) the average depression of ST segment at the exercise endpoint of test (mV) was higher; (5) the time of ST segment depressed for 0.1mV (min) was longer; (6) the metabolic equivalent during ST-segment depressed by 0.1mV was shorter; and (7) the change of QRS wave time-limit before and immediately after TET was more evident. Moreover, in the testing time more patients revealed angina episode after exercise, and less patients had their heart rate reached the requirement in the QYD with PBS group than those in the QYD without PBS group. Comparison between the two groups in all the above-mentioned indices showed significant difference respectively (P < 0.01 or P < 0.05). CONCLUSION: Patients with CHD caused angina pectoris of QYD with PBS are worse in the tolerance for exercise and severer in pathological change of coronary artery than those in those without PBS, they belong to the severe phase of TCM syndrome.