Assessment of Reclamation Treatments of Abandoned Farmland in an Arid Region of China

Reclamation of abandoned farmland is crucial to a sustainable agriculture in arid regions. This study aims to evaluate the impact of different reclamation treatments on abandoned salinized farmland. We investigated four artificial reclamation treatments, continuous cotton (CC), continuous alfalfa (CA), tree-wheat intercropping (TW) and trees (TS), which were conducted in 2011–2012 in the Manasi River Basin of Xinjiang Province, China. Soil nutrient, microorganism and enzyme activity were examined in comparison with natural succession (CK) in an integrated analysis on soil fertility improvement and soil salinization control with these reclamations. Results indicate that the four artificial reclamation treatments are more effective approaches than natural restoration to reclaim abandoned farmland. TW and CA significantly increased soil nutrient content compared to CK. CC reduced soil salinity to the lowest level among all treatments. TW significantly enhanced soil enzyme activity. All four artificial reclamations increased soil microbial populations and soil microbial biomass carbon. TW and CA had the greatest overall optimal effects among the four treatments in terms of the ecological outcomes. If both economic benefits and ecological effects are considered, TW would be the best reclamation mode. The findings from this study will assist in selecting a feasible method for reclamation of abandoned farmland for sustainable agriculture in arid regions.This research was supported by the Special Fund for Agro-scientific Research in the Public Interest (201503120); Science and Technology Research and Achievement Transformation Project of The Xinjiang Production and Construction Crops (2016AD022); and the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (2014BAC14B03)

Advanced glycation end products accelerate ischemia/reperfusion injury through receptor of advanced end product/nitrative thioredoxin inactivation in cardiac microvascular endothelial cells.

The advanced glycation end products (AGEs) are associated with increased cardiac endothelial injury. However, no causative link has been established between increased AGEs and enhanced endothelial injury after ischemia/reperfusion. More importantly, the molecular mechanisms by which AGEs may increase endothelial injury remain unknown. Adult rat cardiac microvascular endothelial cells (CMECs) were isolated and incubated with AGE-modified bovine serum albumin (BSA) or BSA. After AGE-BSA or BSA preculture, CMECs were subjected to simulated ischemia (SI)/reperfusion (R). AGE-BSA increased SI/R injury as evidenced by enhanced lactate dehydrogenase release and caspase-3 activity. Moreover, AGE-BSA significantly increased SI/R-induced oxidative/nitrative stress in CMECs (as measured by increased inducible nitric oxide synthase expression, total nitric oxide production, superoxide generation, and peroxynitrite formation) and increased SI/R-induced nitrative inactivation of thioredoxin-1 (Trx-1), an essential cytoprotective molecule. Supplementation of EUK134 (peroxynitrite decomposition catalyst), human Trx-1, or soluble receptor of advanced end product (sRAGE) (a RAGE decoy) in AGE-BSA precultured cells attenuated SI/R-induced oxidative/nitrative stress, reduced SI/R-induced Trx-1 nitration, preserved Trx-1 activity, and reduced SI/R injury. Our results demonstrated that AGEs may increase SI/R-induced endothelial injury by increasing oxidative/nitrative injury and subsequent nitrative inactivation of Trx-1. Interventions blocking RAGE signaling or restoring Trx activity may be novel therapies to mitigate endothelial ischemia/reperfusion injury in the diabetic population

From Transistors to Phototransistors by Tailoring the Polymer Stacking

It is universally acknowledged that highly photosensitive transistors are strongly dependent on the high carrier mobility of polymer-based semiconductors. However, the polymer π–π stacking and aggregation, required to increase the charge mobility, conversely inhibit the dissociation of photogenerated charge carriers, in turn accelerating the geminate recombination of electron-hole pairs. To explore the effects of charge mobility and polymer stacking on the photoresponsivity of the phototransistors, here, two alternating copolymers are synthesized, namely P-PPAB-IDT and P-PPAB-BDT, by palladium-catalyzed Stille coupling of PPAB with indaceodithiophene (IDT) or benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl) (BDT) monomers. The polymer P-PPAB-IDT demonstrates a nearly 20 times enhancement in the hole mobility compared to P-PPAB-BDT. Yet, P-PPAB-IDT surprisingly shows no response to white light illumination, whereas P-PPAB-BDT exhibits a significant photoresponse to the same light source with a high light-current/dark-current (Ilight/Idark) ratio of 21.6 in the p-type area and a low current ratio of just 5.2 in the n-type area. It is believed that this work will provide an effective strategy to develop highly photosensitive polymer semiconductors by reducing polymer stacking and aggregation rather than improving the charge carrier mobility.acceptedVersionPeer reviewe

1,6-Naphthodipyrrolidone-based donor acceptor polymers with low bandgap

Donor acceptor CD A) copolymers P1-P4 containing 1,6-naphthodipyrrolidone as acceptor unit are synthesized and characterized. Copolymers P1 and P2 are prepared upon Suzuki coupling of 3,8-di(4bromophenyl)-1.6-bis(dodecyl)-2,7-dioxo-1,2,6,7-tetrahydronaphtho[1,2-b:5,6-b']dipyrrole (M1) or 3,8di-(4-bromophenyl)-1.6-bis(2-octyldodecyl)-2,7-dioxo-1,2,6,7-tetrahydronaphtho[1,2-b:5,6-b']dipyrrole (M2) with the donor comonomer 2,2-(9,9-dioctyl-9H-fluoren-2,7-diyl)-bis-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (M3). Polymers P3 and P4 are prepared upon Stille coupling of M1 or M2 with the donor comonomer 4,8-bis(2-ethylhexyloxy)benzo[1,2-6:4,5-6]dithiophene-2,6-diyl-bistrimethyl-stannane M4. The two monomers M1 and M2 exhibit a deep purple color in dichloromethane with high extinction coefficients up to 4.9*10(4) L mol(-1) cm(-1). Optical, electrochemical and thermal properties of the polymers are characterized. The polymers exhibit a broad UV/vis absorption range from 400 to 850 nm, low optical bandgaps (1.27-1.47 eV), low LUMO levels (especially for P1 and P2), a high thermal stability with glass temperature T-g up to 224 degrees C, and 5% weight loss up to 402 degrees C. Density functional theory calculations indicate that the backbone of the 1,6-NDP-polymers is rather planar. Photostability studies indicate a high stability against UV-irradiation in the solid state, but only a moderate stability upon UV irradiation in solution. (C) 2015 Elsevier Ltd. All rights reserved

Synthesis and characterization of 1,3,4,6-tetraarylpyrrolo[3,2-b]-pyrrole-2,5-dione (isoDPP)-based donor-acceptor polymers with low band gap

The synthesis of new pi-conjugated donor-acceptor (D-A) polymers containing tetraaryl-diketopyrrolo[3,2-b]-pyrrole (isoDPP) as the building block is described. Polymers were prepared upon palladium-catalyzed Stille coupling of 3,6-bis(5-bromothien-2-yl)-1,4-diphenyl-pyrrolo[3,2-b]pyrrole-2,5-dione (M1) with 4,4'-bis(2-ethylhexyl)-5,5'-bis(trimethyltin)dithieno[3,2-b:2',3'-d]silole (M2) or (4,8-bis-(2-ethylhexyloxy)benzo [1,2-b:4,5-b]dithiophene-2,6-diyl)bis(trimethylstannane) (M3). The polymers exhibit low band gaps of 1.53 and 1.67 eV, broad absorption bands with maxima of 523 nm and 620 nm, and high extinction coefficients of 6.5 x 10(4) L mol(-1) cm(-1), and 2.6 x 10(4) L mol(-1) cm(-1), respectively. Low fluorescence quantum yields between 0.13% and 0.82% were detected. Quantum chemical calculations indicated a nearly planar backbone with highly delocalized HOMO orbitals and localization of the LUMO electrons at the thienyl-isoDPP units. The X-ray structure analysis of M1 indicated a dihedral angle of 14.1 degrees between the thienyl groups and the isoDPP core, and a 76.6 degrees dihedral angle of the lactam phenyl group and the isoDPP core, the latter preventing any pi-stacking of the monomers. The polymers show high glass transitions (T-g) and excellent thermal stability. Photoirradiation studies indicate that the polymers are extremely stable to UV and visible light in solution. Spectroelectrochemical studies indicated a reversible electrochromism with isosbestic point near 710 nm

Effects of reclamation years on composition and diversity of soil bacterial communities in Northwest China

The objective of this study was to evaluate bacterial community structure and diversity in soil aggregate fractions when salinized farmland was reclaimed after > 27 yr of abandonment and then farmed again for 1, 5, 10, and 15 yr. Illumina MiSeq high-throughput sequencing was performed to characterize the soil bacterial communities in five aggregate size classes in each treatment. The results indicated that reclamation significantly increased macro-aggregation (> 0.25 mm), as well as soil organic C, available N, and available P. The 10-yr field had the largest proportion (93.9%) of soil in the macro-aggregate size classes (i.e., >0.25 mm) and the highest soil electrical conductivity. The five most dominant phyla in the soil samples were Proteobacteria, Actinobacteria, Gemmatimonadetes, Acidobacteria, and Bacteroidetes. The phylogenetic diversity, Chao1, and Shannon indices increased after the abandoned land was reclaimed for farming, reaching maximums in the 15-yr field. Among aggregate size classes, the 1â 0.25 mm aggregates generally had the highest phylogenetic diversity, Chao1, and Shannon indices. Soil organic C and soil electrical conductivity were the main environmental factors affecting the soil bacterial communities. The composition and structure of the bacterial communities also varied significantly depending on soil aggregate size and time since reclamation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Thionation Enhances the Performance of Polymeric Dopant‐Free Hole‐Transporting Materials for Perovskite Solar Cells

To date, the most efficient perovskite solar cells (PSCs) require hole‐transporting materials (HTMs) that are doped with hygroscopic additives to improve their performance. Unfortunately, such dopants negatively impact the overall PSCs stability and add cost and complexity to the device fabrication. Hence, there is a need to investigate new strategies to boost the typically modest performance of dopant‐free HTMs for efficient and stable PSCs. Thionation is a simple and single‐step approach to enhance the carrier‐transport capability of organic semiconductors, yet still completely unexplored in the context of HTMs for PSCs. In this work, a novel polymeric semiconductor, P1, based on a diketopyrrolopyrrole (DPP) moiety, is proposed as a dopant‐free HTM. Its modest performance in PSCs (power conversion efficiency (PCE) = 7.1%) is significantly enhanced upon thionation of the DPP moiety. The resulting dithioketopyrrolopyrrole‐based HTM, P2, leads to PSCs with nearly 40% performance improvement (PCE = 9.7%) compared to devices based on the nonthionated HTM (P1). Furthermore, thionation also remarkably boosts the shelf‐storage and thermal stability with respect to traditional 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene‐based PSCs. This work provides useful insights to further design effective dopant‐free HTMs employing the straightforward one‐step thionation strategy for efficient and stable PSCs.acceptedVersionPeer reviewe