Stress compensation based on interfacial nanostructures for stable perovskite solar cells

The long-term stability issue of halide perovskite solar cells hinders their commercialization.The residual stress-strain affects device stability,which is derived from the mismatched thermophysical and mechanical properties between adjacent layers.In this work,we introduced the Rb_(2)CO_(3)layer at the interface of SnO_(2)/perovskite with the hierarchy morphology of snowflake-like microislands and dendritic nanostructures.With a suitable thermal expansion coefficient,the Rb_(2)CO_(3)layer benefits the interfacial stress relaxation and results in a compressive stress-strain in the perovskite layer.Moreover,reduced nonradiative recombination losses and optimized band alignment were achieved.An enhancement of open-circuit voltage from 1.087 to 1.153 V in the resultant device was witnessed,which led to power conversion efficiency(PCE)of 22.7%(active area of 0.08313 cm^(2))and 20.6%(1 cm2).Moreover,these devices retained 95%of its initial PCE under the maximum power point tracking(MPPT)after 2700 h.It suggests inorganic materials with high thermal expansion coefficients and specific nanostructures are promising candidates to optimize interfacial mechanics,which improves the operational stability of perovskite cells.

The long non-coding RNA DANA2 positively regulates drought tolerance by recruitingERF84 to promote JMJ29-mediated histone demethylation

Tens of thousands of long non-coding RNAs have been uncovered in plants,but few of them have been comprehensively studied for their biological function and molecular mechanism of their mode of action.Here,we show that the Arabidopsis long non-coding RNA DANA2 interacts with an AP2/ERF transcription factor ERF84 in the cell nucleus and then affects the transcription of JMJ29 that encodes a Jumonji C domain-containing histone H3K9 demethylase.Both RNA sequencing(RNA-seq)and genetic analyses demonstrate that DANA2 positively regulates drought stress responses through JMJ29.JMJ29 positively regulates the expression of ERF15 and GOLS2 by modulation of H3K9me2 demethylation.Accordingly,mutation of JMJ29 causes decreased ERF15 and GOLS2 expression,resulting in impaired drought tolerance,in agreement with drought-sensitive phenotypes of dana2 and erf84 mutants.Taken together,these results demonstrate that DANA2 is a positive regulator of drought response and works jointly with the transcriptional activator ERF84 to modulate JMJ29 expression in plant response to drought.

Heat source recognition sensor mimicking the thermosensation function of human skin

The human skin maintains a comfortable and healthy somatosensory state by sensing different aspects of the thermal environment,including temperature value,heat source,energy level,and duration.However,state-of-the-art thermosensors only measure basic temperature values,not the full range of the thermosensation function of human skin.Here,we propose a heat source recognition(hsr)sensor of poly(butyl acrylate)-lithium bis(n-fluoroalkylsulfonyl)imide(PBA-Li:nFSI;n=1,3,5),which enables response to temperature,pressure,and proximity stimulus signals based on the relaxation behavior of the ionic gel and distinguished between different types of heat sources(i.e.,radiation,convection,and conduction).The hsr sensor was integrated into a prosthetic limb covered by an e-skin with isothermal regulation,and experiments with a robot showed that it could achieve human-like thermosensation function,recognizing multidimensional information about thermal environments,such as temperature value,comfort level,and heat source signal.This work deeply mimics the human body’s thermosensation function and provides a reliable solution for the development of bionic e-skin for intelligent robots and prosthetics.

Effect of wastewater composition on the calcium carbonate precipitation in upflow anaerobic sludge blanket reactors

Calcium carbonate often precipitates in anaerobic reactors treating wastewater with high calcium content.The aim of this paper is to study the effect of wastewater composition on calcium carbonate precipitation in upflow anaerobic sludge blanket(UASB)reactors.Two laboratory-scale UASB reactors were operated with calcium-containing influents using acetate and carbohydrate as substrate,respectively.There was an obvious accumulation of inorganic precipitate observed in the biogranules.Observations via scanning electron microscope(SEM)and energy dispersive spectroscopy(EDS)showed that the acclimated biogranules in the two reactors differed in microstructure.Calcium carbonate was found to have precipitated on the surface of acetate-degrading biogranules,but precipitated at the core of the carbohydrate-degrading biogranules.The results indicated that substrates had significant influence on the location of calcium carbonate precipitation in anaerobic granular sludge,which was expected due to the different methanogens distribution and pH gradient within the granular sludge degrading various substrates.Moreover,the location of calcium carbonate precipitation substantially affected the specific methanogenic activity(SMA)of the granular sludge.The SMA of the acetate-degrading biogranules dropped from 1.96 gCODCH4·gVSS^(–1)·d^(–1)to 0.61 gCODCH4·gVSS^(–1)·d^(–1)after 180-d of operation in the reactor.However,the SMA of the carbohydrate-degrading biogranules was not adversely affected by calcium carbonate precipitation.

Regional Guanxi Culture and Entrepreneurs＇ Action Logic： A Multilevel Analysis

At the beginning of the reform period, though informal institutions as a substitute for formal institutions efficiently promoted the development of private enterprises, it eroded and destroyed the authority and execution efficiency of formal institutions with guanxi behaviors and implicit rules. With the progress of marketization, how to restrain and guide the evolution of informal institutions is an tmavoidable obstacle for the development of private enterprises-- transforming their competitive strategy from ＂non-market＂ dominance to ＂market＂ dominance. Based on survey data of 2,628 private enterprises from 31 provinces in China, we establish a regional commercial culture index to empirically investigate the different influences of guanxi behavior between entrepreneurs of different ages and regional guanxi culture. The results show that, compared with entrepreneurs who started businesses in recent years, i.e., after the 1990s, those who started businesses during the 1970s and the 1980s are more dependent on guanxi behaviors. Meanwhile, the higher the level of education, the less an entrepreneur is likely to be dependent on guanxi behaviors. However, compared with the constraint of the degree of regional marketization, regional guanxi culture promotes entrepreneurs＇ guanxi behaviors. Further research indicates that the more enterprises depart from regional guanxi culture, the stronger the ability to innovation. This study can not only enrich the institutional analysis of entrepreneurs＇ guanxi behaviors, but also provide a theoretical foundation for further expansion and deepening of reform.

Expanding the range of CRISPR/Cas9-directed genome editing in soybean

The CRISPR/Cas9 system has been widely applied for plant genome editing.The commonly used SpCas9 has been shown to rely on the protospacer adjacent motif(PAM)sequences in the canonical form NGG and non-canonical NAG.Although these PAM sequences are extensively distributed across plant genomes,a broader scope of PAM sequence is required to expand the range of genome editing.Here we report the adoption of three variant enzymes,xCas9,SpCas9-NG and XNG-Cas9,to produce targeted mutation in soybean.Sequencing results determined that xCas9 with the NGG and KGA(contains TGA and GGA)PAMs successfully induces genome editing in soybean genome.SpCas9-NG could recognize NGD(contains NGG,NGA and NGT),RGC(contains AGC and GGC),GAA and GAT PAM sites.In addition,XNG-Cas9 was observed to cleave soybean genomic regions with NGG,GAA and AGY(contains AGC and AGT)PAM.Moreover,off-target analyses on soybean editing events induced by SpCas9 and xCas9 indicated that two high-fidelity Cas9 variants including eSpCas9(enhanced specificity SpCas9)and exCas9(enhanced specificity xCas9)could improve the specificity of the GGA PAM sequence without reducing on-target editing ficiency.These findings significantly expand the scope of Cas9-mediated genome editing in soybean.

Flexible high-performance microcapacitors enabled by all-printed two-dimensional nanosheets

Chemically exfoliated nanosheets have exhibited great potential for applications in various electronic devices.Solution-based processing strategies such as inkjet printing provide a low-cost,environmentally friendly,and scalable route for the fabrication of flexible devices based on functional inks of twodimensional nanosheets.In this study,chemically exfoliated high-k perovskite nanosheets(i.e.,Ca_(2)Nb_(3)O_(10)and Ca_(2)NaNb_(4)O_(13))are well dispersed in appropriate solvents to prepare printable inks,and then,a series of microcapacitors with Ag and graphene electrodes are printed.The resulting microcapacitors,Ag/Ca_(2)Nb_(3)O_(10)/Ag,graphene/Ca_(2)Nb_(3)O_(10)/graphene,and graphene/Ca_(2)NaNb_(4)O_(13)/graphene,demonstrate high capacitance densities of 20,80,and 150 nF/cm^(2) and high dielectric constants of 26,110.and 200,respectively.Such dielectric enhancement in the microcapacitors with graphene electrodes is possibly attributed to the dielectric/graphene interface.In addition,these microcapacitors also exhibit good insulating performance with a moderate electrical breakdown strength of approximately 1 MV/cm,excellent flexibility,and thermal stability up to 200℃.This work demonstrates the potential of high-k perovskite nanosheets for additive manufacturing of flexible high-performance dielectric capacitors.

MOF-template derived hollow CeO_(2)/Co_(3)O_(4) polyhedrons with efficient cathode catalytic capability in Li-O_(2) batteries

Li-O_(2) batteries(LOBs) have been perceived as the most potential clean energy system for fast-growing electric vehicles by reason of their environmentally friendlier,high energy density and high reversibility.However,there are still some issues limiting the practical application of LOBs,such as the large gap between the actual capacity level and the theoretical capacity,low rate performance as well as short cycle life.Herein,hollow CeO_(2)/Co_(3)O_(4) polyhedrons have been synthesized by MOF template with a simple method.And it is was further served as a cathode catalyst in Li-O_(2) batteries.By means of the synergistic effect of two different transition metal oxides,nano-sized hollow porous CeO_(2)/Co_(3)O_(4) cathode obtained better capacity and cycle performance.As a result,excellent cyclability of exceeding 140 and 90 cycles are achieved at a fixed capacity of 600 and 1000 mAh/g,respectively.The successful application of this catalyst in LOBs offers a novel route in the aspect of the synthesis of other hollow porous composite oxides as catalysts for cathodes in LOBs systems by the MOF template method.

Electrical control of antiferromagnetic metal up to 15 nm

Manipulation of antiferromagnetic(AFM) spins by electrical means is on great demand to develop the AFM spintronics with low power consumption. Here we report a reversible electrical control of antiferromagnetic moments of FeMn up to 15 nm, using an ionic liquid to exert a substantial electric-field effect. The manipulation is demonstrated by the modulation of exchange spring in[Co/Pt]/FeMn system, where AFM moments in FeMn pin the magnetization rotation of Co/Pt. By carrier injection or extraction,the magnetic anisotropy of the top layer in FeMn is modulated to influence the whole exchange spring and then passes its influence to the [Co/Pt]/FeMn interface, through a distance up to the length of exchange spring that fully screens electric field. Comparing FeMn to IrMn, despite the opposite dependence of exchange bias on gate voltages, the same correlation between carrier density and exchange spring stiffness is demonstrated. Besides the fundamental significance of modulating the spin structures in metallic AFM via all-electrical fashion, the present finding would advance the development of low-power-consumption AFM spintronics.

Improving bifunctional catalytic activity of biochar via in-situ growth of nickel-iron hydroxide as cathodic catalyst for zinc-air batteries

Expanding the application scenarios of wood-derived biochar guided by the conversion of traditional energy to new energy shows great promise as a field.As thrilling energy conversion apparatus,zinc-air batteries(ZABs)require cathode catalysts with high oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)activities and stability.Herein,two-dimensional nickel-iron hydroxide nanosheets were creatively assembled in N-doped wood-derived biochar(NiFe-LDH@NC)by an in-situ growth method.The categorized porous organization in wood-derived biochar facilitates the rapid seepage of electrolytes and rapid diffusion of reaction gases.The unique interfacial structure of biochar and NiFe-LDH accelerates electron transfer during oxygen electrocatalysis,and endows NiFe-LDH@NC with first-class catalytic activity and durability for ORR and OER.The ZAB derived from NiFe-LDH@NC showed elevated discharge productivity and cycle endurance,making it promising for viable applications.This work provided a convenient way for the conversion of wood-derived biochar to high-value added electrocatalysts.