Tb^(3+)-nucleic acid probe-based label-free and rapid detection of mercury pollution in food

Mercury is a threatening pollutant in food,herein,we developed a Tb^(3+)-nucleic acid probe-based label-free assay for mix-and-read,rapid detection of mercury pollution.The assay utilized the feature of light-up fluorescence of terbium ions(Tb^(3+))via binding with single-strand DNA.Mercury ion,Hg^(2+)induced thymine(T)-rich DNA strand to form a double-strand structure(T-Hg^(2+)-T),thus leading to fluorescence reduction.Based on the principle,Hg^(2+)can be quantified based on the fluorescence of Tb^(3+),the limit of detection was 0.0689μmol/L and the linear range was 0.1-6.0μmol/L.Due to the specificity of T-Hg^(2+)-T artificial base pair,the assay could distinguish Hg^(2+)from other metal ions.The recovery rate was ranged in 98.71%-101.34%for detecting mercury pollution in three food samples.The assay is low-cost,separation-free and mix-to-read,thus was a competitive tool for detection of mercury pollution to ensure food safety.

Superior aggregation, morphology and photovoltaic performance enabled by fine tuning of fused electron-deficient units in polymer donors

Copolymerization of an electron-rich donor(D)unit with an electron-deficient acceptor(A)unit to construct efficient D-π-A-πtype donors is an effective strategy for organic solar cell applications.The electron-deficient unit fusion,endows extendedπ-conjugation plane and insures excellent photoelectronic property,has great advantages to build A moiety and gradually receives considerable attention.In this work,we adopt benzo[2,1-b:3,4-b’]dithiophene and benzopyrazine(BP),benzothiadiazole(BT)and benzoselenadiazole(BS)to cleverly construct a series of fused A units with different electrondeficient ability,and further synthesize three polymer donors PBDP-BP,PBDP-BT,and PBDP-BS,respectively.The relationships between structure and performance were systematically investigated.PBDPBT shows a moderate aggregation behavior in both solution and film,and the highest hole mobility among the three polymers.After blending with Y6,the PBDP-BT:Y6-based film has the strongest absorption,favorable compatibility,superior crystallinity,and uniform phase separation morphology compared with PBDP-BP or PBDP-BS based blend films.Thus,the device based on PBDP-BT:Y6 has the highest and balanced charge mobility,suppressive recombination,reduced energy loss and achieves an outstanding PCE of 15.14%,which is superior to PBDP-BP:Y6(8.55%)and PBDP-BS:Y6(6.85%).These results provide learnable guidelines for future fused electron-deficient unit-based donor design for photovoltaic application.

Biological properties of essential oil emphasized on the feasibility as antibiotic substitute in feedstuff

The discovery and application of antibiotics in animal feeds have boomed the development of intensive animal husbandry in the last century,until the emergence of antibiotics-resistant bacteria.To alleviate the risks aroused by antibiotics-resistant bacteria,effective antibiotic substitutes are urgently needed to replace antibiotics.Essential oils(EOs)derived from plants are illustrated as the promising antibiotic substitutes used in animal feeds,as same as their current views for poultry and livestock industries in the future.It has been widely demonstrated that the phytochemicals in EOs show multiple biofunctionability and are less likely to induce resistance in bacteria.The beneficial effects of EOs feed supplementation on the intestinal inflammation,intestinal flora,immunity,digestion,and growth performances have been already extensively examined.However,the cost-effectiveness,odor,volatility,instability and bioavailability are the challenges in effectively utilizing EOs in animal intestines.Based on previous researches,and these challenges can partially be resolved by microencapsulation and nanotechnology are promising techniques to deal with these challenges.This article presents the feasibility and foundation of EOs application as antibiotic substitutes in animal feeds,and illustrates the mechanisms,functional performances and superiority of EOs compared with antibiotics.

改性多层氧化石墨烯/二氧化硅材料的制备及对天然橡胶的增强作用

采用乳液共混与机械剪切法制备改性多层氧化石墨烯(MGO)/二氧化硅(SiO2)/天然橡胶(NR)复合材料。采用红外光谱、X射线衍射、扫描电镜等方法分析了改性MGO/SiO2的微观结构,研究了改性MGO/SiO2互配填料对天然橡胶的增强作用。结果表明,经双偶联剂改性的MGO/SiO2可以形成片球三维结构,可有效改善MGO的层叠现象,并减小SiO2粒子在橡胶基体中的分布粒径,提高填料与NR基体的界面相互作用,增加橡胶复合材料的结合胶含量,提高复合材料的综合力学性能。与MGO/SiO2(0/50)/NR复合材料相比,MGO/SiO2(3/47)/NR复合材料的拉伸强度、100%定伸应力和300%定伸应力分别提高了7%、50%、42%,耐切割实验的质量损失下降了43%。

Absorption and Transfer of Exogenous Selenium in Longan(Dimocarpus longan Lour.) and Its Effect

Different concentrations of sodium selenite and sodium selenate were applied to leaves and roots of longan( Dimocarpus longan Lour.) to study the absorption and transfer characteristics of exogenous selenium in longan,and the effects of nitrogen and phosphorus fertilizers on the absorption of selenium in longan were discussed. This study provides a theoretical basis and reference for the research and influence on the absorption and transfer mechanism of selenium in longan and the production of selenium-enriched longan.

Development of Acidification-resistant Organic Fertilizer for Improvement of Acid Red Soil in Guangxi

The soil in Guangxi has been severely acidified,restricting sustainable development of agriculture.In this paper,based on the screening of organic fertilizer additives,a method for the production of acidification-resistant organic fertilizer specific for acid red soil improvement was proposed,and the developed acidification-resistant organic fertilizer was used in sugarcane experiment.The results showed that in the treatment that the specific acidification-resistant organic fertilizer was applied,the yield of sugarcane significantly increased,the p H value of soil effectively increased,the physical and chemical properties of soil improved,and the contents of microorganisms and available nutrients in soil increased.

Development and Application of Special Fertilizer for Crops in Guangxi Region

Different crops need different kinds of nutrients. In this paper,formula of special fertilizer for common field crops in Guangxi is explored from the angle of grain crops,fruits,vegetables,sugar crops,oil crops,etc.,and corresponding production equipment and methods are provided,which could convenience for agricultural precision fertilization and theoretical basis and technical reference for cost saving and efficiency increasing of fertilizer.

Yield of Agricultural Eco-economic System in Dongting Rim

To analyze the efficiency of the agro-ecosystem of Dongting Rim in Hunan Province,this paper adopted the emergy theory to study the agricultural output of this region during 2001 to 2010.The results showed that the value of regional agricultural emergy output increased by44.68%to(6.50 E)sej,but lower than the growth of non-agricultural industry output.Compared with 2001,the emergy output of planting industry was(4.10E)sej in 2010 which occupied 63.09%of the total agricultural emergy output and got an increase of 2.93 percentage points,while the emergy output of stock farming got a decrease of 2.87 percentage points.The growth of fishery emergy output was not in conformity with the characteristics of Dongting Rim in Hunan.From the contrast between emergy output and economic output,we could find that the economic return ratio of planting industry and fishery industry were lower than those of forestry industry and stock farming industry,which indicated that it is necessary to improve the economic benefits of planting industry and fishery industry which were the traditional industries with advantages of the Dongting Rim in Hunan.

Emergy Analysis of the Agricultural Eco-economic System in Dongting Lake Area of Hunan Province

[ Objective] The reseamh aimed to discuss eco-efficiency of the agro-ecosystem in Dongting Lake area of Hunan. [ Method] By referring to emergy reseamh method, emergy structure, function and efficiency of the system were analyzed according to emergy input -output data of the system in 2009. [ Result] The system had developed economy, and mechanization and modernization degrees were higher. Emergy output of the system was unbalanced, and market pricing of the agricultural product was significantly lower, especially farming product. Seen from sustainable development index and environmental loading ratio of the system, the system was full of vitality and development potential. The pressure of natural resources and environment was not very great, but the system accommodated too many populations. [ Conclusion] Basic direction of the agricultur- al policy in the zone was further shortening industrial and agricultural price scissors, continuing to implement price protection of the farming product, adjusting agricultural and product structures and transferring surplus labor.

Crystallography,Packing Mode,and Aggregation State of Chlorinated Isomers for Efficient Organic Solar Cells

Revealing the molecular packing,intermolecular interactions,and aggregation behaviors in the nanocrystalline bulk heterojunction(BHJ)domains undertake the tasks for future materials design for efficient solar cells,especially in understanding the structure–property relationship of isomeric non-fullerene acceptors(NFAs).Theoretical calculations reveal that 2ClIC-βδ,withβ-andδ-chlorine-substituted terminal groups,achieves a relatively higher dipole moment for enhanced intermolecular interactions.More importantly,when comparing the single-crystal X-ray diffraction patterns of three isomeric NFAs,BTIC-BO4Cl-βδ,BTIC-BO4Cl-βγ,and BTIC-BO4Cl,the synergistic effect of chlorine atoms at theβ-andδ-positions endows BTIC-BO4Cl-βδbetter molecular planarity with a dihedral angle of 1.14°.In turn,this creates the shortestπ∙∙∙πdistance(3.28Å)and smallest binding energies(−51.66 kcal mol^(−1))of the three NFAs,resulting in the tightest three-dimensional network packing structure with a framework of L_(x)=14.0Åand L_(y)=13.6Å.Such a structure has multiple intermolecular interactions for better charge transfer.However,the chlorine atomat theγ-position in the other two isomers contributes to non-intermolecular interactions with subordinate packing arrangements.Subsequently,the red-shifted UV-absorption and higher electron mobility observed in neat films of BTIC-BO4Cl-βδagree well with its more ordered crystallinity.This leads to a more suitable fiber-like phase separation in the corresponding active blend,ultimately improving the device performance with superior charge transport.As a result,the highest power conversion efficiency of 17.04%with a current density of 26.07 mA cm^(−2)was obtained with the BTIC-BO4Cl-βδ-based device.The carrier dynamics test and grazing incidence wide-angle X-ray scattering measurement indicate that the packing arrangement of molecules in the nanocrystalline BHJ domains is consistent with their crystallinity.This work investigates the structure–property differences in three acceptors and emphasizes the effect of isomeric chlorine substitution,which suggests that changes in the crystal packing arrangement,especially the size of the framework,have a considerable influence on charge carrier transport and ultimately are reflected on the device efficiency elevation.

The calcium-dependent protein kinase ZmCDPK7 functions in heat-stress tolerance in maize

Global warming poses a serious threat to crops.Calcium-dependent protein kinases(CDPKs)/CPKs play vital roles in plant stress responses,but their exact roles in plant thermotolerance remains elusive.Here,we explored the roles of heat-induced ZmCDPK7 in thermotolerance in maize.ZmCDPK7-overexpressing maize plants displayed higher thermotolerance,photosynthetic rates,and antioxidant enzyme activity but lower H2 O2 and malondialdehyde(MDA)contents than wild-type plants under heat stress.ZmCDPK7-knockdown plants displayed the opposite patterns.ZmCDPK7 is attached to the plasma membrane but can translocate to the cytosol under heat stress.ZmCDPK7 interacts with the small heat shock protein sHSP17.4,phosphorylates sHSP17.4 at Ser-44 and the respiratory burst oxidase homolog RBOHB at Ser-99,and up regulates their expression.Site-directed mutagenesis of sHSP17.4 to generate a Ser-44-Ala substitution reduced ZmCDPK7’s enhancement of catalase activity but enhanced ZmCDPK7’s suppression of MDA accumulation in heat-stressed maize protoplasts.sHSP17.4,ZmCDPK7,and RBOHB were less strongly upregulated in response to heat stress in the abscisic acid-deficient mutant vp5 versus the wild type.Pretreatment with an RBOH inhibitor suppressed sHSP17.4 and ZmCDPK7 expression.Therefore,abscisic acid-induced ZmCDPK7 functions both upstream and downstream of RBOH and participates in thermotolerance in maize by mediating the phosphorylation of sHSP17.4,which might be essential for its chaperone function.

Tuning the Molecular Weight of Chlorine-Substituted Polymer Donors for Small Energy Loss

The molecular weight of polymers plays a major role in their aggregation and miscibility in active layer,which eventually dominate the energy loss and device performance.A series of chlorine-substituted PBD-CI polymers with controlled molecular weight have been synthesized as templates to discern a relationship between molecular weight and the optical properties,energy levels,morphologies,energy loss and photovoltaic performance.Although it has similar optical and electrochemical properties,when blended with acceptor N3,the low molecular weight polymer PBD-CI_(L) gives the biggest energy loss value,and a PCE of 12.06%.PBD-CI_(H) shows a moderate energy loss,but displays the lowest PCE of 9.00%as a result of excessive aggregation.PBD-CI_(M) with a medium molecular weight gives the smallest energy loss and achieves a PCE of 17.17%,which is among one of the highest values recorded to date for the C卜substituted polymer solar cells.Moreover,the molecular weight mainly affects the nonradiative energy loss(△E_(3)), PBD-CI_(M) also shows the smallest value of 0.252 eV among three polymer donors.These results show the effect of controlling the molecular weight to achieve a small energy loss and provide guidelines which can lead to an understanding of the real photovoltaic performance of new materials.

Precisely Controlled Two-Dimensional Rhombic Copolymer Micelles for Sensitive Flexible Tunneling Devices

Nanoscale two-dimensional(2D)organic materials have attracted significant interest on account of their unique properties,which result from their ultrathin and flat morphology.Supramolecular 2D nanomaterials prepared by bottom-up approaches have great potential in the creation of nanoscale devices with various applications,each controlled by the properties of its single-molecular components.Here,we report a uniform and controllable 2D rhombic micelles formed by block copolymers(BCPs)with poly(p-phenylenevinylene)(PPV)as core blocks.The supramolecular 2D nanostructures created in this way and driven byπ-πinteractions realize the precise separation of the semiconducting and insulating constituents of the constructed BCPs.With a vertical tunneling device design,the 2D rhombic micelles exhibited an on-off current ratio of>10^(4)and a high on-state current density of 6000 A cm^(−2)as the insulating layer was compressed by a conductive atomic force microscopy(C-AFM)probe.The tunneling device also shows a reproducible sensitivity on a flexible substrate,opening up potential flexible pressure sensor applications for such novel supramolecular 2D nanostructures.