Applying Classical, Ab Initio, and Machine-Learning Molecular Dynamics Simulations to the Liquid Electrolyte for Rechargeable Batteries.

Rechargeable batteries have become indispensable implements in our daily life and are considered a promising technology to construct sustainable energy systems in the future. The liquid electrolyte is one of the most important parts of a battery and is extremely critical in stabilizing the electrode-electrolyte interfaces and constructing safe and long-life-span batteries. Tremendous efforts have been devoted to developing new electrolyte solvents, salts, additives, and recipes, where molecular dynamics (MD) simulations play an increasingly important role in exploring electrolyte structures, physicochemical properties such as ionic conductivity, and interfacial reaction mechanisms. This review affords an overview of applying MD simulations in the study of liquid electrolytes for rechargeable batteries. First, the fundamentals and recent theoretical progress in three-class MD simulations are summarized, including classical, ab initio, and machine-learning MD simulations (section 2). Next, the application of MD simulations to the exploration of liquid electrolytes, including probing bulk and interfacial structures (section 3), deriving macroscopic properties such as ionic conductivity and dielectric constant of electrolytes (section 4), and revealing the electrode-electrolyte interfacial reaction mechanisms (section 5), are sequentially presented. Finally, a general conclusion and an insightful perspective on current challenges and future directions in applying MD simulations to liquid electrolytes are provided. Machine-learning technologies are highlighted to figure out these challenging issues facing MD simulations and electrolyte research and promote the rational design of advanced electrolytes for next-generation rechargeable batteries.

Hydrothermal synthesis of long-chain hydrocarbons up to C24 with NaHCO3-assisted stabilizing cobalt.

Abiotic CO2 reduction on transition metal minerals has been proposed to account for the synthesis of organic compounds in alkaline hydrothermal systems, but this reaction lacks experimental support, as only short-chain hydrocarbons (

Observational analysis of the immunogenicity and safety of various types of spinal muscular atrophy vaccines.

BACKGROUND: This study aimed to evaluate the immunogenicity and safety of different types of poliovirus vaccines. METHODS: A randomized, blinded, single-center, parallel-controlled design was employed, and 360 infants aged ≥ 2 months were selected as study subjects. They were randomly assigned to bOPV group (oral Sabin vaccine) and sIPV group (Sabin strain inactivated polio vaccine), with 180 infants in each group. Adverse reaction events in the vaccinated subjects were recorded. The micro-neutralization test using cell culture was conducted to determine the geometric mean titer (GMT) of neutralizing antibodies against poliovirus types I, II, and III in different groups, and the seroconversion rates were calculated. RESULTS: Both groups exhibited a 100% seropositivity rate after booster immunization. The titers of neutralizing antibodies for the three types were predominantly distributed within the range of 1:128 to 1:512. The fold increase of type I antibodies differed markedly between the two groups (P < 0.05). Moreover, the fold increase of type II and type III antibodies for poliovirus differed slightly between the two groups (P > 0.05). The fourfold increase rate in sIPV group was drastically superior to that in bOPV group (P < 0.05). When comparing the post-immunization GMT levels of type I antibodies in individuals who completed the full course of spinal muscular atrophy vaccination, bOPV group showed greatly inferior levels to sIPV group (P < 0.05). For type II and type III antibodies, individuals in bOPV group demonstrated drastically superior post-immunization GMT levels to those in sIPV group (P < 0.05). The incidence of adverse reactions between the bOPV and sIPV groups differed slightly (P > 0.05). CONCLUSION: These findings indicated that both the oral vaccine and inactivated vaccine had good safety and immunogenicity in infants aged ≥ 2 months. The sIPV group generated higher levels of neutralizing antibodies in serum, particularly evident in the post-immunization GMT levels for types II and III.

Girdin acts as an oncogene in gastric cancer by regulating AKT/GSK3ß/ß-catenin signaling.

ThE present work focused on exploring Girdin expression within gastric cancer (GC), examining the effect of Girdin on the cell phenotype of GC, and clarifying the underlying mechanisms. Girdin expression in GC samples was identified by immunohistochemistry (IHC) and quantitative real-time PCR (qRT-PCR) assays. Girdin-targeting siRNAs were transfected into GC cells; later, we examined GC cell proliferation, migration, invasion, and apoptosis, respectively. Additionally, the protein expression was examined through Western blotting assay. Moreover, the tumor implantation experiment was conducted for examining Girdin knockdown in vivo. The results showed that Girdin expression elevated within GC samples, which was associated with the dismal prognostic outcome. Girdin knockdown suppressed GC cell proliferation, migration, and invasion, and enhanced apoptosis and cell cycle arrest. Girdin promoted the phosphorylation of AKT, GSK3ß, and ß-catenin. Moreover, Girdin inhibited the phosphorylation of ß-catenin. Girdin suppressed cell apoptosis and stimulated cell migration and invasion, while AKT inhibitor (MK2206) treatment reversed the effect of Girdin overexpression, and GSK3ß inhibitor (CHIR99021) treatment enhanced the effect of Girdin overexpression on GC cells. Besides, Girdin delayed tumor growth in vivo. In conclusion, Girdin was abnormally expressed in GC samples, which promoted the development of GC by regulating AKT/GSK3ß/ß-catenin signaling.

Diameter-dependent ultrafast lithium-ion transport in carbon nanotubes.

Ion transport in solids is a key topic in solid-state ionics. It is critical but challenging to understand the relationship between material structures and ion transport. Nanochannels in crystals provide ion transport pathways, which are responsible for the fast ion transport in fast lithium (Li)-ion conductors. The controlled synthesis of carbon nanotubes (CNTs) provides a promising approach to artificially regulating nanochannels. Herein, the CNTs with a diameter of 5.5 Å are predicted to exhibit an ultralow Li-ion diffusion barrier of about 10 meV, much lower than those in routine solid electrolyte materials. Such a characteristic is attributed to the similar chemical environment of a Li ion during its diffusion based on atomic and electronic structure analyses. The concerted diffusion of Li ions ensures high ionic conductivities of CNTs. These results not only reveal the immense potential of CNTs for fast Li-ion transport but also provide a new understanding for rationally designing solid materials with high ionic conductivities.

A Novel Fluorescent Aptasensor for Arsenic(III) Detection Based on a Triple-Helix Molecular Switch.

A novel aptamer-based fluorescent-sensing platform with a triple-helix molecular switch (THMS) was proposed as a switch for detecting the arsenic(III) ion. The triple helix structure was prepared by binding a signal transduction probe and arsenic aptamer. Additionally, the signal transduction probe labeled with fluorophore (FAM) and quencher (BHQ1) was employed as a signal indicator. The proposed aptasensor is rapid, simple and sensitive, with a limit of detection of 69.95 nM. The decrease in peak fluorescence intensity shows a linear dependence, with the concentration of As(III) in the range of 0.1 µM to 2.5 µM. The whole detection process takes 30 min. Moreover, the THMS-based aptasensor was also successfully used to detect As(III) in a real sample of Huangpu River water with good recoveries. The aptamer-based THMS also presents distinct advantages in stability and selectivity. The proposed strategy developed herein can be extensively applied in the field of food inspection.

Probing the Origin of Viscosity of Liquid Electrolytes for Lithium Batteries.

Viscosity is an extremely important property for ion transport and wettability of electrolytes. Easy access to viscosity values and a deep understanding of this property remain challenging yet critical to evaluating the electrolyte performance and tailoring electrolyte recipes with targeted properties. We proposed a screened overlapping method to efficiently compute the viscosity of lithium battery electrolytes by molecular dynamics simulations. The origin of electrolyte viscosity was further comprehensively probed. The viscosity of solvents exhibits a positive correlation with the binding energy between molecules, indicating viscosity is directly correlated to intermolecular interactions. Salts in electrolytes enlarge the viscosity significantly with increasing concentrations while diluents serve as the viscosity reducer, which is attributed to the varied binding strength from cation-anion and cation-solvent associations. This work develops an accurate and efficient method for computing the electrolyte viscosity and affords deep insight into viscosity at the molecular level, which exhibits the huge potential to accelerate advanced electrolyte design for next-generation rechargeable batteries.

α-Amino-iso-Butyric Acid Foldamers Terminated with Rhodium(I) N-Heterocyclic Carbene Catalysts.

To investigate how remotely induced changes in ligand folding might affect catalysis by organometallic complexes, dynamic α-amino-iso-butyric acid (Aib) peptide foldamers bearing rhodium(I) N-heterocyclic carbene (NHC) complexes have been synthesized and studied. X-ray crystallography of a foldamer with an N-terminal azide and a C-terminal Rh(NHC)(Cl)(diene) complex showed a racemate with a chiral axis in the Rh(NHC) complex and a distorted 310 helical body. Replacing the azide with either one or two chiral L-α-methylvaline (L-αMeVal) residues gave diastereoisomeric foldamers that each possessed point, helical and axial chirality. NMR spectroscopy revealed an unequal ratio of diastereoisomers for some foldamers, indicating that the chiral conformational preference of the N-terminal residue(s) was relayed down the 1 nm helical body to the axially chiral Rh(NHC) complex. Although the remote chiral residue(s) did not affect the stereoselectivity of hydrosilylation reactions catalysed by these foldamers, these studies suggest a potential pathway towards remote conformational control of organometallic catalysts.

The Anionic Chemistry in Regulating the Reductive Stability of Electrolytes for Lithium Metal Batteries.

Advanced electrolyte design is essential for building high-energy-density lithium (Li) batteries, and introducing anions into the Li+ solvation sheaths has been widely demonstrated as a promising strategy. However, a fundamental understanding of the critical role of anions in such electrolytes is very lacking. Herein, the anionic chemistry in regulating the electrolyte structure and stability is probed by combining computational and experimental approaches. Based on a comprehensive analysis of the lowest unoccupied molecular orbitals, the solvents and anions in Li+ solvation sheaths exhibit enhanced and decreased reductive stability compared with free counterparts, respectively, which agrees with both calculated and experimental results of reduction potentials. Accordingly, new strategies are proposed to build stable electrolytes based on the established anionic chemistry. This work unveils the mysterious anionic chemistry in regulating the structure-function relationship of electrolytes and contributes to a rational design of advanced electrolytes for practical Li metal batteries.

An Electrocatalytic Model of the Sulfur Reduction Reaction in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) battery is strongly considered as one of the most promising energy storage systems due to its high theoretical energy density and low cost. However, the sluggish reduction kinetics from Li2 S4 to Li2 S during discharge hinders the practical application of Li-S batteries. Although various electrocatalysts have been proposed to improve the reaction kinetics, the electrocatalytic mechanism is unclear due to the complexity of sulfur reduction reactions (SRR). It is crucial to understand the electrocatalytic mechanism thoroughly for designing advanced electrocatalysts. Herein an electrocatalytic model is constructed to reveal the chemical mechanism of the SRR in Li-S batteries based on systematical density functional theory calculations, taking heteroatoms-doped carbon materials as an example. The adsorption energy of LiSy ⋅ (y=1, 2, or 3) radicals is used as a key descriptor to predict the reaction pathway, rate-determining step, and overpotential. A diagram for designing advanced electrocatalysts is accordingly constructed. This work establishes a theoretical model, which is an intelligent integration for probing the complicated SRR mechanisms and designing advanced electrocatalysts for high-performance Li-S batteries.

Imaging Changes and Clinical Complications After Drug-Eluting Bead Versus Conventional Transarterial Chemoembolization for Unresectable Hepatocellular Carcinoma: Multicenter Study.

BACKGROUND. Drug-eluting bead transarterial chemoembolization (DEB-TACE) has emerged as an alternative to conventional TACE (cTACE) for treatment of hepatocellular carcinoma (HCC), although selection between the approaches remains controversial. OBJECTIVE. The purpose of this study was to compare DEB-TACE and cTACE in the treatment of patients with unresectable HCC in terms of hepatobiliary changes on imaging and clinical complications. METHODS. This retrospective study included 1002 patients (871 men, 131 women; mean age, 59 ± 12 years) from three centers who had previously untreated unresectable HCC and underwent DEB-TACE with epirubicin (780 procedures in 394 patients) or cTACE with ethiodized oil mixed with doxorubicin and oxaliplatin (1187 procedures in 608 patients) between May 2016 and November 2018. Among these patients 83.4% had hepatitis B-related liver disease, 57.6% had Barcelona Clinic Liver Cancer (BCLC) stage A or B HCC, and 42.4% had three or more nodules. Mean tumor size was 6.3 ± 4.2 cm. Hepatobiliary changes and tumor response were evaluated with CT or MRI 1 month after TACE. Clinical records were reviewed for adverse events. RESULTS. Bile duct dilatation (p < .001) and portal vein narrowing (p = .006) on imaging and liver failure (p = .03) and grade 3 abdominal pain (p < .001) in clinical follow-up occurred at higher frequency in the DEB-TACE group (15.5%, 4.6%, 2.3%, and 6.1%) than in the cTACE (7.4%, 1.6%, 0.7%, and 2.1%) group. Higher frequency of bile duct dilation in patients who underwent DEB-TACE was observed in subgroup analyses that included patients with BCLC stage A or B HCC (p = .001), with cirrhosis (p < .001), without cirrhosis (p = .04), and without main portal vein tumor thrombus (p = .002). Total bilirubin level 1 month after treatment was 1.5 ± 2.4 mg/dL (95% CI, 1.2-1.8 mg/dL) for DEB-TACE versus 1.3 ± 2.0 mg/dL (95% CI, 1.1-1.5 mg/dL) for cTACE (p = .02). The cTACE and DEB-TACE groups did not differ in other manifestations of postembolization syndrome or systemic toxicity (p > .05). Local tumor disease control rates did not differ between the cTACE and DEB-TACE groups (1 month, 96.7% vs 98.5%, p = .06; 3 months, 81.8% vs 82.4%, p = .87), but overall DCR was significantly higher in the cTACE than in the DEB-TACE group (1 month, 87.5% vs 80.0%, p = .001; 3 months, 78.5% vs 72.1%, p = .02). CONCLUSION. Compared with cTACE, DEB-TACE was associated with greater frequency of hepatobiliary injury and severe abdominal pain. CLINICAL IMPACT. Greater caution and closer follow-up are warranted for patients who undergo DEB-TACE for unresectable HCC than for those who undergo cTACE.

[Genetic diversity and antibacterial activity of endophytic fungi from Zanthoxylum nitidum].

In order to reveal the distribution and population characteristics of endophytic fungi from Zanthoxylum nitidum and the antibacterial potential,this study performed molecular identification and analyzed the genetic diversity and antibacterial activity of endophytic fungi from Z. nitidum in Guangxi. Through culture and molecular identification,35 strains,belonging to 15 genera,12 families,10 orders,4 classes,and 2 phyla,were isolated from various tissues of Z. nitidum,of which Colletotrichum and Fusarium were the dominant genera,respectively accounting for 20% of total strains. The diversity of endophytic fungi was significantly different among roots,stems,and leaves,as manifested by the significantly higher Shannon index( H') in stems( 1. 678) than in roots( 0. 882 1) and leaves( 0. 515 4). The antimicrobial activity analysis showed that 14. 28% of endophytic fungi inhibited at least one indicator pathogen. Among them,Fusarium sp. ZN-34 and Fusarium sp. ZN-26 separately demonstrated the strongest inhibitory effect on Escherichia coli and Staphylococcus aureus. In general,Fusarium sp. ZN-26 and Phialemoniopsis plurioloculosa ZN-35 were advantageous in suppressing the two bacteria owing to the broad spectrum and strong efficacy. In summary,Z. nitidum in Guangxi boasts rich endophytic fungi with the majority showing strong antibacterial activity,which can be used as candidates for the extraction and separation of basic antibacterial substances and the development of natural antibacterial agents.

An Atomic Insight into the Chemical Origin and Variation of the Dielectric Constant in Liquid Electrolytes.

The dielectric constant is a crucial physicochemical property of liquids in tuning solute-solvent interactions and solvation microstructures. Herein the dielectric constant variation of liquid electrolytes regarding to temperatures and electrolyte compositions is probed by molecular dynamics simulations. Dielectric constants of solvents reduce as temperatures increase due to accelerated mobility of molecules. For solvent mixtures with different mixing ratios, their dielectric constants either follow a linear superposition rule or satisfy a polynomial function, depending on weak or strong intermolecular interactions. Dielectric constants of electrolytes exhibit a volcano trend with increasing salt concentrations, which can be attributed to dielectric contributions from salts and formation of solvation structures. This work affords an atomic insight into the dielectric constant variation and its chemical origin, which can deepen the fundamental understanding of solution chemistry.

Oncogenic gene RGC-32 is a direct target of miR-26b and facilitates tongue squamous cell carcinoma aggressiveness through EMT and PI3K/AKT signalling.

Growing data have recognized the significance of Response Gene to Complement (RGC)-32 in numerous tumour developments. Notwithstanding, the functional role and underlying mechanism of it in tongue squamous cell carcinoma (TSCC) remain enigmatic. Here, to identify the impact of RGC-32 in TSCC, its expression in multiple TSCC cells was measured and loss-of-function experiments in cell lines were performed to illuminate the function of it induced TSCC progression, via si-RNA knockdown, CCK-8, colony formation, wound-healing, transwell, flow cytometry and western blot assays. To clarify potential mechanism, expressions of hallmarks in epithelial-mesenchymal transition (EMT) process and PI3K/AKT signalling were assessed, and the upstream miR regulator of RGC-32 was predicted and verified by applying bioinformatic approaches and dual-luciferase reporter assay, respectively. Finally, the rescue experiments were applied to better elucidate the effect of miR-26b/RGC-32 axis in TSCC behaviours. As a result, RGC-32 was upregulated in TSCC cells and knocking down of it abrogated cell proliferation, trans-migration and invasion, whilst promoted apoptosis in TSCC, which was regulated through repressing EMT and inactivation of PI3K/AKT signalling. Subsequently, miR-26b was predicted and identified as an upstream regulator of RGC-32, and the pro-tumorigenic effect of RGC-32 was reversed by miR-26b overexpression. Collectively, our results demonstrated that RGC-32 facilitated TSCC progression, which was modulated by activations of PI3K/AKT pathway and EMT process, and reduction of its negative regulator of miR-26b. These findings highlight a novel role of miR-26b/RGC-32 axis in TSCC and underlying mechanism, encouraging a potent usage in TSCC treatment. SIGNIFICANCE OF THE STUDY: We first uncovered that Response Gene to Complement-32 played a significantly pro-tumorigenic role in tongue squamous cell carcinoma (TSCC), which was closely regulated by downregulation of miR-26b and activations of epithelial-mesenchymal transition process and PI3K/AKT signalling. These findings contribute to better understand the molecular mechanism in carcinogenesis of TSCC, and shed some light on promising strategy for TSCC therapeutics.

COVID-19 Prevention and Control Public Health Strategies in Shanghai, China.

CONTEXT: COVID-19 was characterized as a pandemic by the World Health Organization on March 11, 2020. This research aims to analyze the public health strategies to prevent and control COVID-19 in Shanghai, China, and provide recommendations for public health policy and interventions in the United States. PROGRAM: Based on the Social-Ecological Model, this research collected information for public health strategies from the Shanghai Municipal Health Commission and various Chinese websites. EVALUATION: The daily confirmed new cases of COVID-19 decreased from 27 to 0 in 53 days since the first case of COVID-19 was confirmed in Shanghai on January 20, 2020. DISCUSSION: The pattern of daily confirmed new cases suggests the effectiveness of public health strategies. This research also provides recommendations on the development and improvements of public health strategies in the U.S. by acknowledging the differences in political and social systems between the two countries.

Genetic variants in IL-33/ST2 pathway with the susceptibility to hepatocellular carcinoma in a Chinese population.

Interleukin (IL)-33/ST2 pathway plays a pivotal role in tumorigenesis through influencing cancer stemness, tumor growth, metastasis, angiogenesis, and accumulation of regulatory T cells in tumor microenvironments. The aim of this study was to investigate the association of IL-33 rs7025417 and ST2 rs3821204 with the risk of hepatocellular carcinoma (HCC). Genotyping of IL-33 rs7025417 and ST2 rs3821204 was carried out using a Taqman assay. IL-33 and ST2 mRNA was examined using real-time PCR and plasma IL-33 and sST2 levels were measured using enzyme-linked immunosorbent assay. The ST2 rs3821204 CC genotype was associated with a significantly increased risk of HCC (CC vs. GG: adjusted OR = 2.29, 95% CI, 1.39-3.78; dominant model: adjusted OR = 1.58, 95% CI, 1.12-2.23; recessive model: adjusted OR = 1.88, 95% CI, 1.21-2.93; C vs. G: adjusted OR = 1.53, 95% CI, 1.20-1.95). Gene-environment interaction analysis showed that the risk effect of rs3821204 CG/CC genotypes was more evident in smokers (adjusted OR = 1.70, 95% CI, 1.13-2.55) and drinkers (adjusted OR = 1.57, 95% CI, 1.04-2.37). The increased risk was also observed in combined analysis. Moreover, HCC patients with ST2 rs3821204 CC genotype had higher levels of mRNA and protein expression (P < 0.05). These findings suggest that ST2 rs3821204 CC genotype may contribute to hepatocarcinogenesis by enhancing ST2 production at the transcriptional and translational level.

[Povidone-iodine versus the benzethonium chloride wipe for penile skin disinfection before semen collection from sperm donors].

Objective: To study the influence of povidone-iodine (PI) versus that of the benzethonium chloride wipe (BCW) on semen collection and semen quality of sperm donors undergoing penile skin disinfection and provide some evidence for the selection of disinfection methods for semen collection. METHODS: We used PI from August to December 2015 and BCWs from January to July 2016 for penile skin disinfection before semen collection, with two samples from each donor, one collected with and the other without penis skin disinfection (the blank control group). After semen collection, we conducted a questionnaire investigation on the influence of the two disinfection methods on semen collection and compared the semen parameters between the two groups of sperm donors. RESULTS: Totally, 185 sperm donors were included in this study, of whom 63 underwent penile skin disinfection with PI and the other 122 with BCWs before semen collection. Statistically significant differences were found between the PI and BCW groups in the adaptability to the disinfectant and rigid disinfection procedures (P <0.05), but not in the other items of the questionnaire (P >0.05). Compared with the sperm donors of the blank control group, those of the PI group showed statistically significant difference in the percentage of progressively motile sperm (PMS) (ï¼»63.02 ± 3.18ï¼½% vs ï¼»61.45 ± 4.78ï¼½%, P<0.05), but not in the abstinence time (ï¼»4.97 ± 1.79ï¼½ vs ï¼»4.7 ± 0.94ï¼½ d, P >0.05), semen volume (ï¼»4.11 ± 1.54ï¼½ vs ï¼»4.15 ± 1.61ï¼½ ml, P >0.05), sperm concentration (ï¼»110 ± 29.6ï¼½ vs ï¼»107.5 ± 31.79ï¼½ ×106/ml, P >0.05), or total sperm count (ï¼»439.10 ± 170.13ï¼½ vs ï¼»434.02 ± 186.91ï¼½ ×106/ejaculate, P >0.05), while those of the BCW group exhibited no remarkable difference in any of the above parameters (P >0.05). Among the samples with abnormal semen quality, significantly fewer were found with abnormal PMS in the BCW than in the PI group (1.64% ï¼»2/122ï¼½ vs 9.68% ï¼»6/62ï¼½, P <0.05). However, there were no significant differences between the PI and BCW groups in the abnormal semen volume, abnormal sperm concentration, or the rate of semen bacterial contamination (P >0.05). CONCLUSIONS: Before semen collection from donors, penile skin disinfection with povidone-iodine may affect both the semen collection process and the quality of donor sperm, while the benzethonium chloride wipe can reduce the influence on the semen collection process and does not affect the semen parameters.

Kinetic Studies on Formic Acid Dehydrogenation Catalyzed by an Iridium Complex towards Insights into the Catalytic Mechanism of High-Pressure Hydrogen Gas Production.

Kinetic studies on the catalytic reaction mechanism of formic acid (FA) dehydrogenation were performed in the presence of a water-soluble iridium complex bearing a 4,4'-dihydroxy-2,2'-bipyridine ligand. Determination of kinetic isotope effects revealed that a shift of the rate-limiting step at low and high concentrations of FA can be caused by the pH dependence of the reaction steps. The proposed equation for the reaction rate corresponds well with the experimental results concerning the shift phenomena. Towards industrial application in future hydrogen fueling stations, this will able the design of a dehydrogenation system catalyzed by the iridium complex.

Effect of the ortho-Hydroxyl Groups on a Bipyridine Ligand of Iridium Complexes for the High-Pressure Gas Generation from the Catalytic Decomposition of Formic Acid.

The hydroxyl groups of a 2,2'-bipyridine (bpy) ligand near the metal center activated the catalytic performance of the Ir complex for the dehydrogenation of formic acid at high pressure. The position of the hydroxyl groups on the ligand affected the catalytic durability for the high-pressure H2 generation through the decomposition of formic acid. The Ir complex with a bipyridine ligand functionalized with para-hydroxyl groups shows a good durability with a constant catalytic activity during the reaction even under high-pressure conditions, whereas deactivation was observed for an Ir complex with a bipyridine ligand with ortho-hydroxyl groups (2). In the presence of high-pressure H2 , complex 2 decomposed into the ligand and an Ir trihydride complex through the isomerization of the bpy ligand. This work provides the development of a durable catalyst for the high-pressure H2 production from formic acid.

Novel compounds that enhance Agrobacterium-mediated plant transformation by mitigating oxidative stress.

KEY MESSAGE: Agrobacterium tumefaciens caused tissue browning leading to subsequent cell death in plant transformation and novel anti-oxidative compounds enhanced Agrobacterium -mediated plant transformation by mitigating oxidative stress. Browning and death of cells transformed with Agrobacterium tumefaciens is a long-standing and high impact problem in plant transformation and the agricultural biotechnology industry, severely limiting the production of transgenic plants. Using our tomato cv. MicroTom transformation system, we demonstrated that Agrobacterium caused tissue browning (TB) leading to subsequent cell death by our correlation study. Without an antioxidant (lipoic acid, LA) TB was severe and associated with high levels of GUS transient expression and low stable transformation frequency (STF). LA addition shifted the curve in that most TB was intermediate and associated with the highest levels of GUS transient expression and STF. We evaluated 18 novel anti-oxidative compounds for their potential to enhance Agrobacterium-mediated transformation, by screening for TB reduction and monitoring GUS transient expression. Promising compounds were further evaluated for their effect on MicroTom and soybean STF. Among twelve non-antioxidant compounds, seven and five significantly (P < 0.05) reduced TB and increased STF, respectively. Among six antioxidants four of them significantly reduced TB and five of them significantly increased STF. The most efficient compound found to increase STF was melatonin (MEL, an antioxidant). Optimal concentrations and stages to use MEL in transformation were determined, and Southern blot analysis showed that T-DNA integration was not affected by MEL. The ability of diverse compounds with different anti-oxidative mechanisms can reduce Agrobacterium-mediated TB and increase STF, strongly supporting that oxidative stress is an important limiting factor in Agrobacterium-mediated transformation and the limiting factor can be controlled by these compounds at different levels.