Long-term continuous ammonia electrosynthesis.

Ammonia is crucial as a fertilizer and in the chemical industry and is considered to be a carbon-free fuel1. Ammonia electrosynthesis from nitrogen under ambient conditions offers an attractive alternative to the Haber-Bosch process2,3, and lithium-mediated nitrogen reduction represents a promising approach to continuous-flow ammonia electrosynthesis, coupling nitrogen reduction with hydrogen oxidation4. However, tetrahydrofuran, which is commonly used as a solvent, impedes long-term ammonia production owing to polymerization and volatility problems. Here we show that a chain-ether-based electrolyte enables long-term continuous ammonia synthesis. We find that a chain-ether-based solvent exhibits non-polymerization properties and a high boiling point (162 °C) and forms a compact solid-electrolyte interphase layer on the gas diffusion electrode, facilitating ammonia release in the gas phase and ensuring electrolyte stability. We demonstrate 300 h of continuous operation in a flow electrolyser with a 25 cm2 electrode at 1 bar pressure and room temperature, and achieve a current-to-ammonia efficiency of 64 ± 1% with a gas-phase ammonia content of approximately 98%. Our results highlight the crucial role of the solvent in long-term continuous ammonia synthesis.

Calcium-mediated nitrogen reduction for electrochemical ammonia synthesis.

Ammonia (NH3) is a key commodity chemical for the agricultural, textile and pharmaceutical industries, but its production via the Haber-Bosch process is carbon-intensive and centralized. Alternatively, an electrochemical method could enable decentralized, ambient NH3 production that can be paired with renewable energy. The first verified electrochemical method for NH3 synthesis was a process mediated by lithium (Li) in organic electrolytes. So far, however, elements other than Li remain unexplored in this process for potential benefits in efficiency, reaction rates, device design, abundance and stability. In our demonstration of a Li-free system, we found that calcium can mediate the reduction of nitrogen for NH3 synthesis. We verified the calcium-mediated process using a rigorous protocol and achieved an NH3 Faradaic efficiency of 40 ± 2% using calcium tetrakis(hexafluoroisopropyloxy)borate (Ca[B(hfip)4]2) as the electrolyte. Our results offer the possibility of using abundant materials for the electrochemical production of NH3, a critical chemical precursor and promising energy vector.

NH3 Electrosynthesis from N2 Molecules: Progresses, Challenges, and Future Perspectives.

Green ammonia (NH3), made by using renewable electricity to split nearly limitless nitrogen (N2) molecules, is a vital platform molecule and an ideal fuel to drive the sustainable development of human society without carbon dioxide emission. The NH3 electrosynthesis field currently faces the dilemma of low yield rate and efficiency; however, decoupling the overlapping issues of this area and providing guidelines for its development directions are not trivial because it involves complex reaction process and multidisciplinary entries (for example, electrochemistry, catalysis, interfaces, processes, etc.). In this Perspective, we introduce a classification scheme for NH3 electrosynthesis based on the reaction process, namely, direct (N2 reduction reaction) and indirect electrosynthesis (Li-mediated/plasma-enabled NH3 electrosynthesis). This categorization allows us to finely decouple the complicated reaction pathways and identify the specific rate-determining steps/bottleneck issues for each synthesis approach such as N2 activation, H2 evolution side reaction, solid-electrolyte interphase engineering, plasma process, etc. We then present a detailed overview of the latest progresses on solving these core issues in terms of the whole electrochemical system covering the electrocatalysts, electrodes, electrolytes, electrolyzers, etc. Finally, we discuss the research focuses and the promising strategies for the development of NH3 electrosynthesis in the future with a multiscale perspective of atomistic mechanisms, nanoscale electrocatalysts, microscale electrodes/interfaces, and macroscale electrolyzers/processes. It is expected that this Perspective will provide the readers with an in-depth understanding of the bottleneck issues and insightful guidance on designing the efficient NH3 electrosynthesis systems.

The unfolded protein response pathway as a possible link in the pathogenesis of COVID-19 and sepsis.

The global impact of the COVID-19 pandemic has been substantial. Emerging evidence underscores a strong clinical connection between COVID-19 and sepsis. Numerous studies have identified the unfolded protein response (UPR) pathway as a crucial pathogenic pathway for both COVID-19 and sepsis, but it remains to be investigated whether this signaling pathway operates as a common pathogenic mechanism for both COVID-19 and sepsis. In this study, single-cell RNA-seq data and transcriptome data for COVID-19 and sepsis cases were downloaded from GEO (Gene Expression Omnibus). By analyzing the single-cell transcriptome data, we identified B cells as the critical cell subset and the UPR pathway as the critical signaling pathway. Based on the transcriptome data, a machine learning diagnostic model was then constructed using the interleaved genes of B-cell-related and UPR-pathway-related genes. We validated the diagnostic model using both internal and external datasets and found the accuracy and stability of this model to be extremely strong. Even after integrating our algorithmic model with the patient's clinical status, it continued to yield identical results, further emphasizing the reliability of this model. This study provides a novel molecular perspective on the pathogenesis of sepsis and COVID-19 at the single-cell level and suggests that these two diseases may share a common mechanism.

Sulfur Vacancies in Pyrite Trigger the Path to Nonradical Singlet Oxygen and Spontaneous Sulfamethoxazole Degradation: Unveiling the Hidden Potential in Sediments.

Pharmaceutical residues in sediments are concerning as ubiquitous emerging contaminants. Pyrite is the most abundant sulfide minerals in the estuarine and coastal sediments, making it a major sink for pharmaceutical pollutants such as sulfamethoxazole (SMX). However, research on the adsorption and redox behaviors of SMX on the pyrite surface is limited. Here, we investigated the impact of the nonphotochemical process of pyrite on the fate of coexisting SMX. Remarkably, sulfur vacancies (SVs) on pyrite promoted the generation of nonradical species (hydrogen peroxide, H2O2 and singlet oxygen, 1O2), thereby exhibiting prominent SMX degradation performance under darkness. Nonradical 1O2 contributed approximately 73.1% of the total SMX degradation. The SVs with high surrounding electron density showed an advanced affinity for adsorbing O2 and then initiated redox reactions in the sediment electron-storing geobattery pyrite, resulting in the extensive generation of H2O2 through a two-electron oxygen reduction pathway. Surface Fe(III) (hydro)oxides on pyrite facilitated the decomposition of H2O2 to 1O2 generation. Distinct nonradical products were observed in all investigated estuarine and coastal samples with the concentrations of H2O2 ranging from 1.96 to 2.94 µM, while the concentrations of 1O2 ranged from 4.63 × 10-15 to 8.93 × 10-15 M. This dark-redox pathway outperformed traditional photochemical routes for pollutant degradation, broadening the possibilities for nonradical species use in estuarine and coastal sediments. Our study highlighted the SV-triggered process as a ubiquitous yet previously overlooked source of nonradical species, which offered fresh insights into geochemical processes and the dynamics of pollutants in regions of frequent redox oscillations and sulfur-rich sediments.

Development of Highly Enantio- and Z-Selective Grubbs Catalysts via Controllable C-H Bond Activation.

Asymmetric olefin metathesis is a powerful strategy for stereocontrolled synthesis that allows the formation of chiral elements in conjunction with carbon-carbon double bonds. Here, we report a new series of cyclometalated stereogenic-at-Ru catalysts that enable highly efficient asymmetric ring opening/cross-metathesis (AROCM) and asymmetric ring-closing metathesis (ARCM) reactions. Single enantiomers of these catalysts with either right-handed or left-handed configurations at the Ru center can be easily accessed via highly stereoselective C-H bond activation-based cyclometalation. Right-handed chiral Ru catalysts enabled the Z- and enantioselective AROCM of a wide range of norbornenes and terminal alkenes, generating densely functionalized cyclopentanes with excellent stereo- and enantioselectivities (99:1 Z/E, up to 99% ee). Left-handed chiral Ru catalysts enabled the facile ARCM of sterically unhindered, all-terminal prochiral trienes, which had not been achieved by previous Ru catalysts, providing simple cyclic ethers and amides with tertiary or quaternary carbon stereocenters with excellent enantioselectivities (up to 99% ee).

Dummy Template-Based Molecularly Imprinted Membrane Coating for Rapid Analysis of Malachite Green and Its Metabolic Intermediates in Shrimp and Fish.

A novel malachite green molecularly imprinted membrane (MG-MIM) with specific selectivity for malachite green (MG) and leucomalachite green (LMG) was prepared using a hydrophobic glass fiber membrane as the polymer substrate, methyl violet as a template analog, 4-vinyl benzoic acid as the functional monomer, and ethyleneglycol dimethacrylate as the crosslinking agent. MG-MIM and non-imprinted membrane (NIM) were structurally characterized using scanning electron microscopy, surface area analyzer, Fourier-transform infrared spectrometer and synchronous thermal analyzer. The results showed that MG-MIM possessed a fluffier surface, porous and looser structure, and had good thermal stability. Adsorption properties of MG-MIM were investigated under optimal conditions, and adsorption equilibrium was reached in 20 min. The saturated adsorption capacities for MG and LMG were 24.25 ng·cm-2 and 13.40 ng·cm-2, and the maximum imprinting factors were 2.41 and 3.20, respectively. Issues such as "template leakage" and "embedding" were resolved. The specific recognition ability for the targets was good and the adsorption capacity was stable even after five cycles. The proposed method was successfully applied for the detection of MG and LMG in real samples, and it showed good linear correlation in the range of 0 to 10.0 µg·L-1 (R2 = 0.9991 and 0.9982), and high detection sensitivity (detection limits of MG and LMG of 0.005 µg/kg and 0.02 µg·kg-1 in shrimp, and 0.005 µg/kg and 0.02 µg/kg in fish sample). The recoveries and relative standard deviations were in the range of 76.31-93.26% and 0.73-3.72%, respectively. The proposed method provides a simple, efficient and promising alternative for monitoring MG and LMG in aquatic products.

Comparison of calcium and ultrasonic treatment on fruit firmness, pectin composition and cell wall-related enzymes of postharvest apricot during storage.

This study was conducted to examine the effects of calcium treatment (2%, 20 min) and ultrasonic treatment (400 W, 20 min) on postharvest apricot fruit during storage. The results showed that after calcium and ultrasonic treatment, compared with the control, the firmness of apricot fruit increased by 41.53% and 3.83% at 16 d, but juice yield and water-soluble pectin (WSP) content decreased by 8.26% and 3.55%, 28.57% and 4.08%, respectively. Both calcium and ultrasonic treatment were more effective in reducing polygalacturonase (PG), ß-Galactosidase (ß-Gal), pectin methylesterase (PME), polyphenol oxidase (PPO) and peroxidase (POD) activity. Moreover, fruit firmness was significantly negatively correlated with juice yield, WSP and PPO, and positively correlated with PG and ß-Gal, PPO and POD. In contrast, calcium treatment was more effective than ultrasonic treatment in delaying postharvest softening of apricot.

The Osmotin-Like Protein Gene PdOLP1 Is Involved in Secondary Cell Wall Biosynthesis during Wood Formation in Poplar.

Osmotin-like proteins (OLPs) mediate defenses against abiotic and biotic stresses and fungal pathogens in plants. However, no OLPs have been functionally elucidated in poplar. Here, we report an osmotin-like protein designated PdOLP1 from Populus deltoides (Marsh.). Expression analysis showed that PdOLP1 transcripts were mainly present in immature xylem and immature phloem during vascular tissue development in P. deltoides. We conducted phenotypic, anatomical, and molecular analyses of PdOLP1-overexpressing lines and the PdOLP1-downregulated hybrid poplar 84K (Populus alba × Populus glandulosa) (Hybrid poplar 84K PagOLP1, PagOLP2, PagOLP3 and PagOLP4 are highly homologous to PdOLP1, and are downregulated in PdOLP1-downregulated hybrid poplar 84K). The overexpression of PdOLP1 led to a reduction in the radial width and cell layer number in the xylem and phloem zones, in expression of genes involved in lignin biosynthesis, and in the fibers and vessels of xylem cell walls in the overexpressing lines. Additionally, the xylem vessels and fibers of PdOLP1-downregulated poplar exhibited increased secondary cell wall thickness. Elevated expression of secondary wall biosynthetic genes was accompanied by increases in lignin content, dry weight biomass, and carbon storage in PdOLP1-downregulated lines. A PdOLP1 coexpression network was constructed and showed that PdOLP1 was coexpressed with a large number of genes involved in secondary cell wall biosynthesis and wood development in poplar. Moreover, based on transcriptional activation assays, PtobZIP5 and PtobHLH7 activated the PdOLP1 promoter, whereas PtoBLH8 and PtoWRKY40 repressed it. A yeast one-hybrid (Y1H) assay confirmed interaction of PtoBLH8, PtoMYB3, and PtoWRKY40 with the PdOLP1 promoter in vivo. Together, our results suggest that PdOLP1 is a negative regulator of secondary wall biosynthesis and may be valuable for manipulating secondary cell wall deposition to improve carbon fixation efficiency in tree species.

Surface-to-Bulk Redox Coupling through Thermally Driven Li Redistribution in Li- and Mn-Rich Layered Cathode Materials.

Li- and Mn-rich (LMR) layered cathode materials have demonstrated impressive capacity and specific energy density thanks to their intertwined redox centers including transition metal cations and oxygen anions. Although tremendous efforts have been devoted to the investigation of the electrochemically driven redox evolution in LMR cathode at ambient temperature, their behavior under a mildly elevated temperature (up to ∼100 °C), with or without electrochemical driving force, remains largely unexplored. Here we show a systematic study of the thermally driven surface-to-bulk redox coupling effect in charged Li1.2Ni0.15Co0.1Mn0.55O2. We for the first time observed a charge transfer between the bulk oxygen anions and the surface transition metal cations under ∼100 °C, which is attributed to the thermally driven redistribution of Li ions. This finding highlights the nonequilibrium state and dynamic nature of the LMR material at deeply delithiated state upon a mild temperature perturbation.

Electrochemically Driven Coordination Tuning of FeOOH Integrated on Carbon Fiber Paper for Enhanced Oxygen Evolution.

Coordination tuning of catalysts is a highly effective strategy for activating and improving the intrinsic activity. Herein, a Co-engineered FeOOH catalyst integrated on carbon fiber paper (Co-FeOOH/CFP) is reported, which realized a great improvement of the oxygen evolution activity by tuning the coordination geometry of the Fe species with an electrochemically driven method. Experiments and theoretical calculation demonstrate that the FeO bonds of FeOOH are partially broken, which is rooted in the Co incorporation, thus resulting in unsaturated FeO6 ligand structures and a relatively narrow bandgap. Consequently, the reorganized Fe sites on the surface show an enhanced capability for adsorbing OH- species and the Co-FeOOH exhibits an improved conductivity. As expected, the Co-FeOOH/CFP hybrids exhibit an extremely low overpotential of ≈250 mV at 10 mA cm-2 and a small Tafel slope, which far outperforms that of electrochemically sluggish FeOOH. The present work emphasizes the importance of local Fe coordination in catalysis and provides an in-depth insight into the mechanism of the enhanced catalytic activity.

Multilevel Coupled Hybrids Made of Porous Cobalt Oxides and Graphene for High-Performance Lithium Storage.

Metal oxide coupling with carbon materials holds great promise for lithium storage. Herein, multilevel coupled cobalt oxide-graphene (CoO/CO3 O4 -G) hybrids were fabricated by in situ assembly of Co hydroxide precursors and a calcination process. The oxygen-containing functional groups on the graphene surface act as bridging sites and tend to bond with Co2+ ions, effectively modifying the morphology and structure of the Co species. The as-obtained CoO/CO3 O4 -G hybrids are composed of unique CoO/CO3 O4 porous nanoparticles uniformly anchored on graphene sheets, as confirmed by a series of characterization analyses. Benefiting from these structural characteristics, the CoO/CO3 O4 -G hybrids used as an anode can deliver a high capacity of about 1080 mA h g-1 reversibly at 0.1 Ag-1 in the voltage range between 3.0 and 0.01 V, which is remarkably superior to that of the CoO hexagonal sheets in the absence of graphene. The high reversible capacity of the CoO/CO3 O4 -G hybrids is retained at elevated current densities, for example, a capacity of approximately 455 mA h g-1 can be achieved at a current rate as high as 4 A g-1 , indicative of its potential for high-performance lithium-ion batteries.

Ultrahigh-Capacity and Long-Life Lithium-Metal Batteries Enabled by Engineering Carbon Nanofiber-Stabilized Graphene Aerogel Film Host.

A safe, high-capacity, and long-life Li metal anode is highly desired due to recent developments in high-energy-density Li-metal batteries. However, there are still rigorous challenges associated with the undesirable formation of Li dendrites, lack of suitable host materials, and unstable chemical interfaces. Herein, a carbon nanofiber-stabilized graphene aerogel film (G-CNF film), inspired by constructional engineering, is constructed. As the host material for Li deposition, the G-CNF film features a large surface area, porous structure, and a robust skeleton that can render low local current density. This allows for dendrite-free Li deposition and mitigation of problems associated with large volume change. Importantly, the G-CNF film can keep high Li plating/stripping efficiency at nearly 99% for over 700 h with an areal capacity of 10 mA h cm-2 (the specific capacity up to 2588 mA h g-1 based on the total mass of carbon host and Li metal). The symmetric cells can stably run for more than 1000 h with low voltage hysteresis. The full cell with the LiFePO4 cathode also delivers enhanced capacity and lowered overpotential. As two-in-one host materials for both cathodes and anodes in Li-O2 batteries, the battery exhibits a capacity of 1.2 mA h cm-2 .

Phosphate Species up to 70% Mass Ratio for Enhanced Pseudocapacitive Properties.

The emerging phosphate species on the surface or near-surface of electrode materials are versatile and have an intriguing ability for dramatically enhanced electrochemical performance. Unfortunately, the distribution/dispersion of phosphate species still keeps at levels on the exterior not within the interior surface of materials, and the micro-/nanoscale tuning is commonly rarely concerned and its function remains poorly understood. Herein, for the first time, well-dispersed phosphate species up to 70% mass ratio implanted within Ni-doped CoP nanowire matrix are presented via an efficient low-temperature phosphorization strategy. The resultant nanohybrids possess kinetics-favorable open frameworks with abundant mesopores and a high degree covalency in the chemical bonds, thus leading to rapid mass transport/charge transfer and enhanced redox reaction kinetics. Remarkably, the phosphate species feature superwettability toward water and strong affinity for OH- in the electrolyte, evidenced by the shortened distance and reduced adsorption energy between the OH- and the nuclear Co atoms on the nanohybrids as revealed by density functional theory calculations. As such, the nanohybrids exhibit an ultrahigh specific capacity of 250 mAh g-1 even at 50 A g-1 . This work presents a deeper understanding of the dispersion and role of phosphate species for supercapacitors and other energy-related storage/conversion devices.

Microporous MOFs Engaged in the Formation of Nitrogen-Doped Mesoporous Carbon Nanosheets for High-Rate Supercapacitors.

Nitrogen-doped mesoporous carbon nanosheets (NMCS) have been fabricated from zinc-based microporous metal-organic frameworks (ZIF-8) by pyrolysis in a molten salt medium. The as-prepared NMCS exhibit significantly improved specific capacitance (NMCS-8: 232 F g-1 at 0.5 A g-1 ) and capacitance retention ratio (75.9 % at 50 A g-1 ) compared with the micropore-dominant nitrogen-doped porous carbon polyhedrons (NPCP-5: 178 F g-1 at 0.5 A g-1 , 15.9 % at 20 A g-1 ) obtained by direct pyrolysis of nanocrystalline ZIF-8. The excellent capacitive performance and high rate performance of the NMCS can be attributed to their unique combination of structure and composition, that is, the two-dimensional and hierarchically porous structure provides a short ion-transport pathway and facilitates the supply of electrolyte ions, and the nitrogen-doped polar surface improves the interface wettability when used as an electrode.

High-Stacking-Density, Superior-Roughness LDH Bridged with Vertically Aligned Graphene for High-Performance Asymmetric Supercapacitors.

The high-performance electrode materials with tuned surface and interface structure and functionalities are highly demanded for advanced supercapacitors. A novel strategy is presented to conFigure high-stacking-density, superior-roughness nickel manganese layered double hydroxide (LDH) bridged by vertically aligned graphene (VG) with nickel foam (NF) as the conductive collector, yielding the LDH-NF@VG hybrids for asymmetric supercapacitors. The VG nanosheets provide numerous electron transfer channels for quick redox reactions, and well-developed open structure for fast mass transport. Moreover, the high-stacking-density LDH grown and assembled on VG nanosheets result in a superior hydrophilicity derived from the tuned nano/microstructures, especially microroughness. Such a high stacking density with abundant active sites and superior wettability can be easily accessed by aqueous electrolytes. Benefitting from the above features, the LDH-NF@VG can deliver a high capacitance of 2920 F g-1 at a current density of 2 A g-1 , and the asymmetric supercapacitor with the LDH-NF@VG as positive electrode and activated carbon as negative electrode can deliver a high energy density of 56.8 Wh kg-1 at a power density of 260 W kg-1 , with a high specific capacitance retention rate of 87% even after 10 000 cycles.

Starch Derived Porous Carbon Nanosheets for High-Performance Photovoltaic Capacitive Deionization.

Capacitive deionization (CDI) is an emerging technology that uniquely integrates energy storage and desalination. In this work, porous carbon nanosheets (PCNSs) with an ultrahigh specific surface area of 2853 m2/g were fabricated by the simple carbonization of starch followed by KOH activation for the electrode material of photovoltaic CDI. The CDI cell consisting of PCNSs electrodes exhibited a high salt adsorption capacity (SAC) of 15.6 mg/g at ∼1.1 V in 500 mg/L NaCl as well as high charge efficiency and low energy consumption. KOH activation played a key role in the excellent CDI performance as it not only created abundant pores on the surface of PCNSs but also made it fluffy and improved its graphitization degree, which are beneficial to the transport of ions and electrons. PCNSs are supposed to be a promising candidate for CDI electrode materials. The combination of solar cells and CDI may provide a new approach to reduce the energy cost of CDI and boost its commercial competitiveness.

Effects of drought and salt-stresses on gene expression in Caragana korshinskii seedlings revealed by RNA-seq.

BACKGROUND: Drought and soil salinity are major abiotic stresses. The mechanisms of stress tolerance have been studied extensively in model plants. Caragana korshinskii is characterized by high drought and salt tolerance in northwestern China; unique patterns of gene expression allow it to tolerate the stress imposed by dehydration and semi-desert saline soil. There have, however, been no reports on the differences between C. korshinskii and model plants in the mechanisms underlying their drought and salt tolerance and regulation of gene expression. RESULTS: Three sequencing libraries from drought and salt-treated whole-seedling- plants and the control were sequenced to investigate changes in the C. korshinskii transcriptome in response to drought and salt stresses. Of the 129,451 contigs, 70,662 (54.12 %) were annotated with gene descriptions, gene ontology (GO) terms, and metabolic pathways, with a cut-off E-value of 10(-5). These annotations included 56 GO terms, 148 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and 25 Clusters of Orthologous Groups (COG). On comparison of the transcriptomes of the control, drought- and salt-treated plants, 1630 and 1521 contigs showed significant differences in transcript abundance under drought and salt stresses. Compared to the differentially expressed genes (DEGs) in drought- or salt-treated Arabidopsis in the database, 542 DEGs in drought-treated C. korshinskii and 529 DEGs in salt-treated samples were presumably unique to C. korshinskii. The transcription profiles revealed that genes related to transcription factors, protein kinases, and antioxidant enzymes are relevant to the tolerance of drought and salt stress in this species. The expression patterns of 38 randomly selected DEGs were confirmed by quantitative real-time PCR and were essentially consistent with the changes in transcript abundance identified by RNA-seq. CONCLUSIONS: The present study identified potential genes involved in drought and salt tolerance in C. korshinskii, as well as many DEGs uniquely expressed in drought- or salt-treated C. korshinskii samples compared to Arabidopsis. To our knowledge, this study is the first exploration of the C. korshinskii transcriptome under drought and salt conditions, and these results will facilitate the discovery of specific stress-resistance-related genes in C. korshinskii, possibly leading to the development of novel plant cultivars through genetic engineering.

Small GTP-binding protein PdRanBP regulates vascular tissue development in poplar.

BACKGROUND: Previous research has demonstrated that ectopic expression of Ran-binding protein (RanBP) in Arabidopsis results in more axillary buds and reduced apical dominance compared to WT plants. However, the function of RanBP in poplar, which has very typical secondary growth, remains unclear. Here, the Populus deltoides (Marsh.) RanBP gene (PdRanBP) was isolated and functionally characterized by ectopic expression in a hybrid poplar (P. davidiana Dode × P. bolleana Lauche). RESULTS: PdRanBP was predominantly expressed in leaf buds and tissues undergoing secondary wall expansion, including immature xylem and immature phloem in the stem. Overexpression of PdRanBP in poplar increased the number of sylleptic branches and the proportion of cells in the G2 phase of the cell cycle, retarded plant growth, consistently decreased the size of the secondary xylem and secondary phloem zones, and reduced the expression levels of cell wall biosynthesis genes. The downregulation of PdRanBP facilitated secondary wall expansion and increased stem height, the sizes of the xylem and phloem zones, and the expression levels of cell wall biosynthesis genes. CONCLUSIONS: These results suggest that PdRanBP influences the apical and radial growth of poplar trees and that PdRanBP may regulate cell division during cell cycle progression. Taken together, our results demonstrated that PdRanBP is a nuclear, vascular tissue development-associated protein in P. deltoides.

[Screening the Optimal Time of Sinusoidal Alternating Electromagnetic Field for the Bone Biomechanical Properties of Rat].

The present research is to investigate the time effect of sinusoidal electromagnetic fields(SEMFs)at different exposure time on the biomechanical properties in rats,and to find a best time for improving biomechanical properties.Forty female SD rats were randomly divided into five groups,i.e.control group,45 min SEMFs group,90 min SEMFs group,180 min SEMFs group,and 270 min SEMFs group.In addition to the control group,other groups were exposed to 50 Hz and 0.1mT magnetic field every day for the corresponding time periods.After eight weeks,bone mineral density(BMD),bone biomechanics,bone tissue morphology,micro-CT and pathological examination were performed.The results showed that there was no abnormal pathological finding in the experimental groups.In the 90 min SEMFs group,BMD,femur maximum load,elastic modulus,yield strength,trabecular number(Tb.N),trabecular thickness(Tb.Th)and trabecular area(Tb.Ar)percentage were all significantly higher than those in the control group(P<0.01),and trabecular separation(Tb.Sp)was significantly lower than that of the control group(P<0.01).However,for other experimental groups,some indices showed statistical significance compared to the control group(P<0.05),but some did not(P>0.05).This study showed that under 50 Hz and 0.1 mT SEMFs,90 min is the best time that can effectively increase bone mineral density,improve the bone tissue microstructure organization and the biomechanical properties.