Advances and Challenges in Large-Area Perovskite Light-Emitting Diodes.

Metal halide perovskite light-emitting diodes (PeLEDs) have shown promise for high-definition displays and flat-panel lighting because of their wide color gamut, narrow emission band, and high brightness. The external quantum efficiency of PeLEDs increased rapidly from ≈1% to more than 25% in the past few years. However, most of these high-performance devices are fabricated using a spin coating method with a small device area of <0.1 cm2, limiting their commercial applications. Recently, large-area PeLEDs have attracted growing attention and significant breakthroughs have been reported. This perspective first introduces the pros and cons of each technique in making large-area PeLEDs. The advances in the fabrication of large-area PeLEDs are then summarized using spin coating and mass-production methods such as inkjet printing, blade coating, and thermal evaporation. Moreover, the challenging issues will be discussed that are urgent to be solved for large-area PeLEDs.

Resolution of N-acetyl-DL-methionine methyl ester by the lipase from Brucella thiophenivorans.

In this study, lipase-catalyzed resolution of N-acetyl-DL-methionine methyl ester (N-Ac-DL-MetOMe) was evaluated. A lipase from Brucella thiophenivorans was prone to exhibit high activity and excellent enantioselectivity toward N-Ac-DL-MetOMe to produce the key chiral intermediate N-acetyl-L-methionine methyl ester (N-Ac-L-MetOMe). The results showed that the enzymatic reaction was carried out in 100 g/L racemic substrate for 2 h, the conversion reached 51.3%, the enantiomeric excess value N-Ac-L-MetOMe exceeded 99%, and the enantiomeric ratio value >200. Therefore, the lipase from B. thiophenivorans has potential prospects for the resolution of N-Ac-DL-MetOMe to produce the important intermediate N-Ac-L-MetOMe.

Bioelectro-barriers prevent nitrate leaching into groundwater via nitrogen retention.

Groundwater, the main freshwater resource for humans, has been widely contaminated with nitrate from fertilizers. Here, we report a new and chemical-free strategy to prevent nitrate leaching from soil based on the enrichment of electroactive bacteria, mainly of the genus Geobacter, with bioelectro-barriers, which leads to a nearly 100 % interception of nitrate and partly conserves reactive nitrogen in the form of weakly mobile ammonium by dissimilatory nitrate reduction to ammonium (DNRA). G. sulfurreducens was recognized to efficiently secrete nitrite reductase (NrfA) for rapid DNRA because it lacks nitrate reductase, which inhibits DNRA by competing with nitrite and producing toxic intracellular nitric oxide. With an increase in G. sulfurreducens abundance, near-zero nitrate leaching and 3-fold greater N retention was achieved. Periodic application of weak electricity to the bioelectro-barrier ensured the dominance of G. sulfurreducens in the microbial community and therefore its ability to consistently prevent nitrate leaching. The ability of G. sulfurreducens to intercept nitrate was further demonstrated in more diverse agricultural soils, providing a novel way to prevent nitrate leaching and conserve bioavailable nitrogen in the soil, which has broader implications for both sustainable agriculture and groundwater protection.

Significance tests for covariates in the diagnostic accuracy index of a biomarker against a continuous gold standard.

Receiver operating characteristic (ROC) curve is a popular tool to describe and compare the diagnostic accuracy of biomarkers when a binary-scale gold standard is available. However, there are many examples of diagnostic tests whose gold standards are continuous. Hence, Several extensions of receiver operating characteristic (ROC) curve are proposed to evaluate the diagnostic potential of biomarkers when the gold standard is continuous-scale. Moreover, in evaluating these biomarkers, it is often necessary to consider the effects of covariates on the diagnostic accuracy of the biomarker of interest. Covariates may include subject characteristics, expertise of the test operator, test procedures or aspects of specimen handling. Applying the covariate adjustment to the case that the gold standard is continuous is challenging and has not been addressed in the literature. To fill the gap, we propose two general testing frameworks to account for the covariates effect on diagnostic accuracy. Simulation studies are conducted to compare the proposed tests. Data from a study that assessed three types of imaging modalities with the purpose of detecting neoplastic colon polyps and cancers are used to illustrate the proposed methods.

Genetic and functional characterization of multiple thermophilic organosulfur-removal systems reveals desulfurization potentials for waste residue oil cleaning.

Heavy oil and petroleum refining residues usually contain high concentrations of recalcitrant hazardous organosulfur compounds, causing long-term serious global environmental pollution during leakage and combustion. Research conducted here identified a unique thermophilic bacterium Parageobacillus thermoglucosidasius W-36 with the notable ability of waste residue oil desulfurization, utilization and tolerance of multiplex hazardous organosulfur pollutants. Genome information mining revealed multiple desulfurization systems in three organosulfur-utilizing gene clusters. Enzymatic characterization, phylogenetic relationships, transcriptional performance and structural prediction indicated four novel key monooxygenases for diverse organosulfur removal. Importantly, all monooxygenases shared obvious commonalities in the predicted tertiary structure backbone and catalytic characteristics of C-S bond cleavage, implying the potential of genetic engineering for broad-spectrum hazardous organosulfur removal. Therefore, this work demonstrated the important application potential of thermophilic bacteria as a promising alternative biodesulfurization way for waste residue oil cleaning.

A methodological framework for assessing pastoral socio-ecological system vulnerability: A case study of Altay Prefecture in Central Asia.

Vulnerability analysis is important for enhancing sustainability, especially for highly interlinked pastoral socio-ecological systems. This study presents a modified methodological framework for assessing the vulnerability of pastoral socio-ecological systems based on the interactions between social and ecological subsystems and their vulnerabilities. Altay Prefecture (Northwest China), a typical pastoral area located in Central Asia, was chosen for the case study. The ecological vulnerability index (EVI) and socio-ecological vulnerability index (SEVI) of Altay Prefecture from 2001 to 2018 were assessed and classified into five levels. The results showed that the distribution pattern of EVI was spatially heterogeneous, with EVI increasing from north to south and from west to east. The EVI was high in low-altitude deserts, decreased with altitude rising from 1300 m to 2200 m, and increased when the altitude exceeded 2200 m. The average EVI increased from 2001 to 2010 and decreased from 2010 to 2018, with the highest EVI in 2010 and the lowest in 2018. The SEVI of western counties was lower than that of eastern counties; the SEVI of all counties continuously decreased from 2001 to 2018, with a higher rate from 2010 to 2018. Social adaptive capacity, increased by the policies that aim at protecting grasslands and improving livelihoods, was the main influencing factor of the SEVI dynamic. These results will help to identify key areas with high EVI for grassland ecosystem management and strengthen the adaptive capacity for addressing vulnerability. Furthermore, the presented methodological framework can be adopted in vulnerability assessments of similar pastoral areas or natural resource-based socio-ecological systems.

Bacterial diversity and competitors for degradation of hazardous oil refining waste under selective pressures of temperature and oxygen.

Oil refining waste (ORW) contains complex, hazardous, and refractory components, causing more severe long-term environmental pollution than petroleum. Here, ORW was used to simulate the accelerated domestication of bacteria from oily sludges and polymer-flooding wastewater, and the effects of key factors, oxygen and temperature, on the ORW degradation were evaluated. Bacterial communities acclimated respectively in 30/60 °C, aerobic/anaerobic conditions showed differentiated degradation rates of ORW, ranging from 5% to 34%. High-throughput amplicon sequencing and ORW component analysis revealed significant correlation between bacterial diversity/biomass and degradation efficiency/substrate preference. Under mesophilic and oxygen-rich condition, the high biomass and abundant biodiversity with diverse genes and pathways for petroleum hydrocarbons degradation, effectively promoted the rapid and multi-component degradation of ORW. While under harsh conditions, a few dominant genera still contributed to ORW degradation, although the biodiversity was severely restricted. The typical dominant facultative anaerobes Bacillus (up to 99.8% abundance anaerobically) and Geobacillus (up to 99.9% abundance aerobically and anaerobically) showed oxygen-independent sustainable degradation ability and broad-spectrum of temperature adaptability, making them promising and competitive bioremediation candidates for future application. Our findings provide important strategies for practical bioremediation of varied environments polluted by hazardous ORW.

Indefinite Mean-Field Stochastic Cooperative Linear-Quadratic Dynamic Difference Game With Its Application to the Network Security Model.

In this article, we show how to obtain all of the Pareto optimal decision vectors and solutions for the finite horizon indefinite mean-field stochastic cooperative linear-quadratic (LQ) difference game. First, the equivalence between the solvability of the introduced N coupled generalized difference Riccati equations (GDREs) and the solvability of the multiobjective optimization problem is established. However, it is difficult to obtain Pareto optimal decision vectors based on the N coupled GDREs because the optimal joint strategy adopted by all players to optimize the performance criterion of some players in the game is different from the strategies of other players, which rely on the weighted matrices of cost functionals that may be different among players. Second, a necessary and sufficient condition is developed to guarantee the convexity of the costs, which makes the weighting technique not only sufficient but also necessary for searching Pareto optimal decision vectors. It is then shown that the mean-field Pareto optimality algorithm (MF-POA) is presented to identify, in principle, all of the Pareto optimal decision vectors and solutions via the solutions to the weighted coupled GDREs and the weighted coupled generalized difference Lyapunov equations (GDLEs), respectively. Finally, a cooperative network security game is reported to illustrate the results presented. Simulation results validate the solvability, correctness, and efficiency of the proposed algorithm.

Fully Bridged Triphenylamine Derivatives as Color-Tunable Thermally Activated Delayed Fluorescence Emitters.

Three emissive bridged-triphenylamine derivatives are designed and synthesized by incorporating carbon (DQAO), oxygen (OQAO), and sulfur (SQAO) atoms with two carbonyl groups. The fully bridged geometry and unique frontier molecular orbital distribution reveal its potential as narrowband thermally activated delayed fluorescence emitters. DQAO-, OQAO-, and SQAO-based organic light-emitting diodes exhibit the maximum external quantum efficiency (EQEmax) of 15.2%, 20.3%, and 17.8% for blue, green, and yellow, respectively.

Genetically engineered thermotolerant facultative anaerobes for high-efficient degradation of multiple hazardous nitroalkanes.

Nitroalkanes are important industrial raw materials but also toxic pollutants, which are difficult to degrade once released into the environment. In this study, to significantly improve the degradation-efficiency of multiple nitroalkanes, a facultative anaerobe was genetically engineered, possible influencing factors and simulated application experiments of bioreactor were tested and evaluated. Among all engineered recombinants, the most effective strains NG-S1 (anaerobic) and NG-S2 (aerobic) displayed 2-fold and 2.8-fold final degradation rates higher than the wild type, respectively. Exogenous components, particularly those that enhance coenzyme synthesis, helped to increase the degradation rate, as the level of coenzymes affected full function of overexpressed nitroalkane oxidase. Importantly, simulated mixed-nitroalkane-wastewater bioreactor experiments proved excellent and sustainable degradation performance of the engineered strains for potential industrial applications. Collectively, these findings provide a promising thermophilic biological engineering platform and a new perspective for high-efficient and continuous environmental bioremediation of hazardous pollutants under aerobic and anaerobic conditions.

Highly Efficient Thermally Activated Delayed Fluorescence via an Unconjugated Donor-Acceptor System Realizing EQE of Over 30.

In this work, two novel thermally activated delayed fluorescence (TADF) emitters, 2tDMG and 3tDMG, are synthesized for high-efficiency organic light-emitting diodes (OLEDs), The two emitters have a tilted face-to-face alignment of donor (D)/acceptor (A) units presenting intramolecular noncovalent interactions. The two TADF materials are deposited either by an evaporation-process or by a solution-process, both of them leading to high OLED performance. 2tDMG used as the emitter in evaporation-processed OLEDs achieves a high external quantum efficiency (EQE) of 30.8% with a very flat efficiency roll-off of 7% at 1000 cd m-2 . The solution-processed OLEDs also display an interesting EQE of 16.2%. 3tDMG shows improved solubility and solution processability as compared to 2tDMG, and thus a high EQE of 20.2% in solution-processed OLEDs is recorded. The corresponding evaporation-processed OLEDs also reach a reasonably high EQE of 26.3%. Encouragingly, this work provides a novel strategy to address the imperious demands for OLEDs with high EQE and low roll-off.

Circularly Polarized Thermally Activated Delayed Fluorescence Emitters in Through-Space Charge Transfer on Asymmetric Spiro Skeletons.

This work describes a strategy to produce circularly polarized thermally activated delayed fluorescence (CP-TADF). A set of two structurally similar organic emitters SFST and SFOT are constructed, whose spiro architectures containing asymmetric donors result in chirality. Upon grafting within the spiro frameworks, the donor and acceptor are fixed proximally in a face-to-face manner. This orientation allows intramolecular through-space charge transfer (TSCT) to occur in both emitters, leading to TADF properties. The donor units in SFST and SFOT have a sulfur and oxygen atom, respectively; such a subtle difference has great impacts on their photophysical, chiroptical, and electroluminescence (EL) properties. SFOT exhibits greatly enhanced EL performance in doped organic light-emitting diodes, with external quantum efficiency (EQE) up to 23.1%, owing to the concurrent manipulation of highly photoluminescent quantum efficiency (PLQY, ∼90%) and high exciton utilization. As a comparison, the relatively larger sulfur atom in SFST introduces heavy atom effects and leads to distortion of the molecular backbone that lengthens the donor-acceptor distance. SFST thus has lower PLQY and faster nonradiative decay rate. The collective consequence is that the EQE value of SFST, i.e., 12.5%, is much lower than that of SFOT. The chirality of these two spiro emitters results in circularly polarized luminescence. Because SFST has a more distorted molecular architecture than SFOT, the luminescence dissymmetry factor (|glum|) of circularly polarized luminescence of one enantiomer of the former, namely, either (S)-SFST or (R)-SFST, is almost twice that of (S)-SFOT/(R)-SFOT. Moreover, the CP organic light-emitting diodes (CP-OLEDs) show obvious circularly polarized electroluminescence (CPEL) signals with gEL of 1.30 × 10-3 and 1.0 × 10-3 for (S)-SFST and (S)-SFOT, respectively.

Near-Infrared Electroluminescence beyond 800†nm with High Efficiency and Radiance from Anthracene Cored Emitters.

Derivatives based on anthryleno[1,2-b]pyrazine-2,3-dicarbonitrile (DCPA) are used as luminescent materials, to realize near-infrared (NIR) electroluminescence. By functionalizing DCPA with aromatic amine donors, two emitters named DCPA-TPA and DCPA-BBPA are designed and synthesized. Both molecules have large dipole moments owing to the strong intramolecular charge transfer interactions between the amine donors and the DCPA acceptor. Thus, compared with doped films, the emission of neat films of DCPA-TPA and DCPA-BBPA can fully fall into the NIR region (>700 nm) with increasing surrounding polarity by increasing doping ratio. Moreover, the non-doped devices based on DCPA-TPA and DCPA-BBPA provide NIR emission with peaks at 838 and 916 nm, respectively. A maximum radiance of 20707 mW Sr-1 m-2 was realized for the further optimized device based on DCPA-TPA. This work provides a simple and efficient strategy of molecular design for developing NIR emitting materials.

Comparative transcriptomic analysis revealed the key pathways responsible for organic sulfur removal by thermophilic bacterium Geobacillus thermoglucosidasius W-2.

Biodesulfurization is a promising method to desulfurize sulfur-containing compounds in oil with its unique advantages, such as environment-friendly treatments and moderate reaction conditions. In this study, a thermophilic bacterium Geobacillus thermoglucosidasius W-2 was reported to show nearly 40% and 55% desulfurization rates on heavy oil with 2.81% and 0.46% initial total sulfur content, respectively. Subsequently, comparative transcriptome analysis indicated that several possible key desulfurization-related genes of this strain were found to be differentially up-regulated induced by benzothiophene and dibenzothiophene, respectively. These desulfurization-related genes were considered to conduct key step to convert organic sulfur to inorganic sulfur. Moreover, the characterization of thermophilic alkanesulfonate monooxygenase systems SsuD1/SsuE1 and SsuD2/SsuE2 revealed that the enzymes exhibit considerable thermal and pH stability and wide substrates applicability. These enzymes probably endowed the strain W-2 with the ability to desulfurize oil and eliminate the sulfur-containing surfactants. Thus, this study provides novel alkanesulfonate monooxygenase systems that have the application potential for heavy oil biodesulfurization, oil demulsification and other biocatalytic processes.

Genome Sequence of Aeribacillus pallidus W-12, a Thermophilic Bacterium Containing Possible Biodesulfurization and Biodenitrification Pathways.

Aeribacillus pallidus W-12 is a thermophilic bacterium isolated from Dagang oil reservoir sewage in northern China. The genome sequence of this strain reported here may provide insights into genomic characteristics regarding the biodegradation of organosulfur and organic nitrogen compounds under elevated temperature.

Novel thermostable enzymes from Geobacillus thermoglucosidasius W-2 for high-efficient nitroalkane removal under aerobic and anaerobic conditions.

In this study, a thermophilic facultative anaerobic strain Geobacillus thermoglucosidasius W-2 was found to degrade nitroalkane under both aerobic and anaerobic conditions. Bioinformatical analysis revealed three putative nitroalkane-oxidizing enzymes (Gt-NOEs) genes from the W-2 genome. The three identified proteins Gt2929, Gt1378, and Gt1208 displayed optimal activities at high temperatures (70, 70, and 80 °C, respectively). Among these, Gt2929 exhibited excellent degradation capability, pH stability, and metal ion tolerance for nitronates under aerobic condition. Interestingly, under anaerobic condition, only Gt1378 still maintained high activity for 2-nitropropane and nitroethane, indicating that the W-2 strain utilized various pathways to degrade nitronates under aerobic and anaerobic conditions, respectively. Taken together, the first revelation of thermophilic nitroalkane-degrading mechanism under both aerobic and anaerobic conditions provides guidance and platform for biotechnological and industrial applications.

Synthesis, anionophoric activity and apoptosis-inducing bioactivity of benzimidazolyl-based transmembrane anion transporters.

In this paper we show that a series of 1,3-bis(benzimidazol-2-yl)benzene (m-Bimbe) derivatives exhibit excellent performance as transmembrane anion transporters with anticancer activity. The transport efficiency of m-Bimbe and its derivatives has been firstly optimized by adding a strong electron-withdrawing nitro group at the 5-position of the central phenyl subunits to enhance the CH···anion interactions. Evidences for the interactions were obtained from ESI MS, spectrophotometric and 1H NMR titrations. These compounds exhibit potent anionophoric activity in both liposomal models and live cells. In particular, the 5-nitrated derivatives having nitro or trifluoromethyl groups at the benzimidazoloyl subunits exhibit 2370- and 1721-fold enhanced anionophoric activity with the EC50 values as low as 36 and 50 nM, respectively. These compounds can disturb the cellular homeostasis of chloride anions, modify the intracellular pH and induce the basification of acidic organelles. Most of this series of m-Bimbe derivatives exhibit potent cytotoxicity toward the tested human solid tumor cell lines, and the 5-nitrated derivative bearing trifluoromethyl groups at the benzimidazoloyl subunits is the most active with the IC50 value in the low micromolar range. Mechanistic studies suggest that the transport of chloride anions across the cellular membranes plays a critical role in the cytotoxic effect and these compounds induce cell death probably via an apoptotic process.

Highly efficient anion transport mediated by 1,3-bis(benzimidazol-2-yl)benzene derivatives bearing electron-withdrawing substituents.

1,3-Bis(benzimidazol-2-yl)benzene exhibits potent anionophoric activity through a process of anion exchange with a minor level of proton/anion symport. Modification of 1,3-bis(benzimidazol-2-yl)benzene with strong electron-withdrawing substituents, such as trifluoromethyl and nitro groups, leads to up to 789-fold increase in the activity. The benzimidazolyl-NH fragments, the relative position and the number of the benzimidazolyl groups on the central phenyl scaffold play an essential role in the transport.

Olig2 regulates Purkinje cell generation in the early developing mouse cerebellum.

The oligodendrocyte transcription factor Olig2 plays a crucial role in the neurogenesis of both spinal cord and brain. In the cerebellum, deletion of both Olig2 and Olig1 results in impaired genesis of Purkinje cells (PCs) and Pax2(+) interneurons. Here, we perform an independent study to show that Olig2 protein is transiently expressed in the cerebellar ventricular zone (VZ) during a period when PCs are specified. Further analyses demonstrate that Olig2 is expressed in both cerebellar VZ progenitors and early-born neurons. In addition, unlike in the ganglionic eminence of the embryonic forebrain where Olig2 is mostly expressed in proliferating progenitors, Olig2(+) cells in the cerebellar VZ are in the process of leaving the cell cycle and differentiating into postmitotic neurons. Functionally, deletion of Olig2 alone results in a preferential reduction of PCs in the cerebellum, which is likely mediated by decreased neuronal generation from their cerebellar VZ progenitors. Furthermore, our long-term lineage tracing experiments show that cerebellar Olig gene-expressing progenitors produce PCs but rarely Pax2(+) interneurons in the developing cerebellum, which opposes the "temporal identity transition" model of the cerebellar VZ progenitors stating that majority of Pax2(+) interneuron progenitors are transitioned from Olig2(+) PC progenitors.

2,6-Bis(benzimidazol-2-yl)pyridine as a potent transmembrane anion transporter.

2,6-Bis(benzimidazol-2-yl)pyridine was shown to exhibit potent anionophoric activity via a process of both Cl(-)/NO3(-) antiport and H(+)/Cl(-) symport. This is in sharp contrast to the finding that its corresponding N-methylated analog exhibited negligible activity and reveals the importance of the imidazolyl-NH fragments in the anion-transport process.