Intraparticle Charge Delocalization through Conjugated Metal-Ligand Interfacial Bonds:Effects of Metal d Electrons

Intraparticle charge delocalization occurs when metal nanoparticles are functionalized with organic capping ligands through conjugated rnetal-ligand interfacial bonds. In this study, metal nanoparticles of 5d metals （Ir, Pt, and Au） and 4d metals （Ru, Rh, and Pd） were prepared and capped with ethynylphenylacetylene and the impacts of the number of metal d electrons on the nanoparticle optoelectronic properties were examined. Both FTIR and photoluminescence measurements indicate that intraparticle charge delocalization was en- hanced with the increase of the number of d electrons in the same period with palladium being an exception.

Genetic and lipidomic analyses reveal the key role of lipid metabolism for cold tolerance in maize

Lipid remodeling is crucial for cold tolerance in plants.However,the precise alternations of lipidomics during cold responses remain elusive,especially in maize(Zea mays L.).In addition,the key genes responsible for cold tolerance in maize lipid metabolism have not been identified.Here,we integrate lipidomic,transcriptomic,and genetic analysis to determine the profile of lipid remodeling caused by cold stress.We find that the homeostasis of cellular lipid metabolism is essential for maintaining cold tolerance of maize.Also,we detect 210 lipid species belonging to 13 major classes,covering phospholipids,glycerides,glycolipids,and free fatty acids.Various lipid metabolites undergo specific and selective alterations in response to cold stress,especially mono-/di-unsaturated lysophosphatidic acid,lysophosphatidylcholine,phosphatidylcholine,and phosphatidylinositol,as well as polyunsaturated phosphatidic acid,monogalactosyldiacylglycerol,diacylglycerol,and triacylglycerol.In addition,we identify a subset of key enzymes,including ketoacyl-acyl-carrier protein synthase II(KAS II),acyl-carrier protein 2(ACP2),male sterility33(Ms33),and stearoyl-acyl-carrier protein desaturase 2(SAD2)involved in glycerolipid biosynthetic pathways are positive regulators of maize cold tolerance.These results reveal a comprehensive lipidomic profile during the cold response of maize and provide genetic resources for enhancing cold tolerance in crops.

Design and test of the key components for a combing-type tobacco harvester

In response to the problems of low efficiency,high labor intensity,and low mechanization in manual tobacco harvesting,a comb-off tobacco picking device for southern hilly tobacco areas was designed following the agronomic requirements and the principle of manual picking of tobacco harvesting in southern China.The device was composed of the power chassis,picking mechanism,and storage mechanism.This study involved the theoretical analysis,structural design,and modeling of the key components,such as chassis structure,combing-type picking mechanism,and power synchronization mechanism.The results of the motion analysis and calculation of the picking process demonstrated that the adjustment range of the comb chain elevation angles was from 12.4°to 20.9°,the comb rod installation distance was 76.2 mm,and the synchronizing mechanism transmission ratio was 3:10.One-factor test and three-factor three-level orthogonal test was performed with the forward speed of the chassis,the distance between the picking device baffles and the elevation angle of the chain with the combing bar as test factors,and the rate of broken and missed tobacco picking as evaluation indicators.It was revealed that the optimal combination of the forward speed of the chassis,the distance between the baffles,and the chain elevation angle were 1.5 km/h,75 mm,and 12.4°,respectively.Moreover,verification tests suggested that the breakage rate of tobacco leaves was 9.99%,and the probability of missed tobacco picking was 7.31%,both of which satisfy the agriculture requirements and the operational requirements in the agricultural machinery certification syllabus.

Cytokinin signaling promotes salt tolerance by modulating shoot chloride exclusion in maize

Excessive accumulation of chloride(Cl^(-))in the aboveground tissues under saline conditions is harmful to crops.Increasing the exclusion of Cl^(-) from shoots promotes salt tolerance in various crops.However,the underlying molecular mechanisms remain largely unknown.In this study,we demonstrated that a type A response regulator(ZmRR1)modulates Cl^(-) exclusion from shoots and underlies natural variation of salt tolerance in maize.ZmRR1 negatively regulates cytokinin signaling and salt tolerance,likely by interacting with and inhibiting His phosphotransfer(HP)proteins that are key mediators of cytokinin signaling.A naturally occurring non-synonymous SNP variant enhances the interaction between ZmRR1 and ZmHP2,conferring maize plants with a salt-hypersensitive phenotype.We found that ZmRR1 undergoes degradation under saline conditions,leading to the release of ZmHP2 from ZmRR1 inhibition,and subsequently ZmHP2-mediated signaling improves salt tolerance primarily by promoting Cl^(-) exclusion from shoots.Furthermore,we showed that ZmMATE29 is transcriptionally upregulated by ZmHP2-mediated signaling under highly saline conditions and encodes a tonoplast-located Cl^(-) transporter that promotes Cl^(-) exclusion from shoots by compartmentalizing Cl^(-) into the vacuoles of root cortex cells.Collectively,our study provides an important mechanistic understanding of the cytokinin signaling-mediated promotion of Cl^(-) exclusion from shoots and salt tolerance and suggests that genetic modification to promote Cl^(-) exclusion from shoots is a promising route for developing salt-tolerant maize.

Natural variations of ZmSRO1d modulate the trade-off between drought resistance and yield by affecting ZmRBOHC-mediated stomatal ROS production in maize

While crop yields have historically increased,drought resistance has become a major concern in the context of global climate change.The trade-off between crop yield and drought resistance is a common phenomenon;however,the underlying molecular modulators remain undetermined.Through genome-wide association study,we revealed that three non-synonymous variants in a drought-resistant allele of ZmSRO1d-R resulted in plasma membrane localization and enhanced mono-ADP-ribosyltransferase activity of ZmSRO1d toward ZmRBOHC,which increased reactive oxygen species(ROS)levels in guard cells and promoted stomatal closure.ZmSRO1d-R enhanced plant drought resilience and protected grain yields under drought conditions,but it led to yield drag under favorable conditions.In contrast,loss-of-function mutants of ZmRBOHC showed remarkably increased yields under well-watered conditions,whereas they showed compromised drought resistance.Interestingly,by analyzing 189 teosinte accessions,we found that the ZmSRO1d-R allele was present in teosinte but was selected against during maize domestication and modern breeding.Collectively,our work suggests that the allele frequency reduction of ZmSRO1d-R in breeding programs may have compromised maize drought resistance while increased yields.Therefore,introduction of the ZmSRO1d-R allele into modern maize cultivars would contribute to food security under drought stress caused by global climate change.

Neuro-regenerative imidazole-functionalized GelMA hydrogel loaded with hAMSC and SDF-1α promote stem cell differentiation and repair focal brain injury

Brain tissues that are severely damaged by traumatic brain injury(TBI)is hardly regenerated,which leads to a cavity or a repair with glial scarring.Stem-cell therapy is one viable option to treat TBI-caused brain tissue damage,whose use is,whereas,limited by the low survival rate and differentiation efficiency of stem cells.To approach this problem,we developed an injectable hydrogel using imidazole groups-modified gelatin methacrylate(GelMA-imid).In addition,polydopamine(PDA)nanoparticles were used as carrier for stromal-cell derived factor-1(SDF-1α).GelMA-imid hydrogel loaded with PDA@SDF-1αnanoparticles and human amniotic mesenchymal stromal cells(hAMSCs)were injected into the damaged area in an in-vivo cryogenic injury model in rats.The hydrogel had low module and its average pore size was 204.61±41.41 nm,which were suitable for the migration,proliferation and differentiation of stem cells.In-vitro cell scratch and differentiation assays showed that the imidazole groups and SDF-1αcould promote the migration of hAMSCs to injury site and their differentiation into nerve cells.The highest amount of nissl body was detected in the group of GelMA-imid/SDF-1α/hAMSCs hydrogel in the in-vivo model.Additionally,histological analysis showed that GelMA-imid/SDF-1α/hAMSCs hydrogel could facilitate the regeneration of regenerate endogenous nerve cells.In summary,the GelMA-imid/SDF-1α/hAMSCs hydrogel promoted homing and differentiation of hAMSCs into nerve cells,and showed great application potential for the physiological recovery of TBI.

Cytocompatible 3D chitosan/hydroxyapatite composites endowed with antibacterial properties:toward a self-sterilized bone tissue engineering scaffold

Bone tissue scaffolds based on bioactive polymer–hydroxyapatite composites have caused infections that seriously limit their extended application. In this study, we proposed a practical ion substitution method to synthesize in situ silver phosphate on the surface of a two-level, threedimensional chitosan/nano-hydroxyapatite scaffold. A release test of silver ions in a phosphate buffered saline(PBS) solution was performed to demonstrate that silver ions were released continuously from the silver phosphate during the initial 6 days of the study. The antibacterial property and cytocompatibility of the scaffolds treated with different concentrations of silver nitrate solution were assessed by in vitro assays with Escherichia coli and MC3T3-E1, respectively. The ability of the silver-containing scaffolds to induce bacteriostasis was confirmed by the inhibition zone(15 mm) and high bactericidal rate([99 %). Cell proliferation, morphology and the alkaline phosphatase activity of MC3T3-E1 cultured on the scaffold with low silver phosphate contents were comparable with those cultured on control samples.

Effects of Irradiance and Temperature on the Photosynthesis and Vegetative Propagation of Caulerpa serrulata

The photosynthetic oxygen evolution of Caulerpa serrulata was determined with oxygen electrodes. The effects of light and temperature on the growth and regeneration of fragmented C. serrulata thalli were analyzed. The regenerating rate and establishment of different sizes and portions of C. serrulata were studied. The results showed that the light saturation point of C. serrulata was 200 μmol photons/m^2 per s and the optimum growth temperature was 25-30 ℃. Under these conditions, the maximum photosynthetic oxygen evolution rate was 15.1 ± 0.29 mg O2/mg Chl alh, the growth rate and elongation rate reached the highest values, 4.67 ±0.09 mg FW/d and 0.78± 0.01 mm/d, respectively. The fragmented C. serrulata thalli was regenerated at 20-35℃ and survived at 15℃ and 200 μmol photons/m^2 per s. A different survival rate was detected according to fragment size. All of these results indicated that C. serrulata was a candidate to become an invasive species if introduced into a new place. Therefore, we should pay more attention to C. serrulata for its potential threat to marine ecosystem when it is sold for aquarium use.

医疗自我规制的形成:西方路径与中国借鉴

近二十年来,中国执业医师数量迅猛增长,同时出现了医疗腐败、医患矛盾升级等问题,医疗规制问题凸显。在西方医疗领域,专业自我规制发挥了重要作用,并且有其独特的历史渊源,通常被看做政府和市场之外的第三种逻辑。在西方专业社会学视角下,医学专业达到了专业化的顶峰,其表现就是自我规制,即通过医学专业团体的行业管理实现专业内部的自我规范和约束。在当代中国的医疗规制研究中,仍然缺乏对自我规制的构建模式的探讨。论文从路径分析的视角,对西方医疗自我规制的形成进行了系统文献梳理,并利用美国和法国两个案例,着力分析了自我规制的两种不同形成路径,为构建中国本土的医疗自我规制提供借鉴。