CO_(2) hydrogenation to methanol over the copper promoted In_(2)O_(3) catalyst

The metal promoted In_(2)O_(3) catalysts for CO_(2) hydrogenation to methanol have attracted wide attention because of their high activity with high methanol selectivity.However,there was still no experimental confirmation if copper could be a good promoter for In_(2)O_(3).Herein,the Cu promoted In_(2)O_(3) catalyst was prepared using a deposition-precipitation method.Such prepared Cu/In_(2)O_(3) catalyst shows significantly higher CO_(2) conversion and space time yield(STY)of methanol,compared to the un-promoted In_(2)O_(3) catalyst.The loading of Cu facilitates the activation of both H_(2) and CO_(2) with the interface between the Cu cluster and defective In_(2)O_(3) as the active site.The Cu/In_(2)O_(3) catalyst takes the CO hydrogenation pathway for methanol synthesis from CO_(2) hydrogenation.It exhibits a unique size effect on the CO adsorption.At temperatures below 250℃,CO adsorption on Cu/In_(2)O_(3) is stronger than that on In_(2)O_(3),causing higher methanol selectivity.With increasing temperatu res,the Cu catalyst aggregates,which leads to the formation of weak CO adsorption site and causes a decrease in the methanol selectivity.Compared with other metal promoted In_(2)O_(3) catalysts,it can be concluded that the catalyst with stronger CO adsorption possesses higher methanol selectivity.

Advances in the studies of the supported ruthenium catalysts for CO_(2) methanation

CO_(2) methanation has a potential in the large-scale utilization of carbon dioxide.It has also been considered to be useful for the renewable energy storage.The commercial pipeline for natural gas transportation can be directly applied for the methane product of CO_(2) methanation.The supported ruthenium(Ru)catalyst has been confirmed to be active and stable for CO_(2) methanation with its high ability in the dissociation of hydrogen and the strong binding of carbon monoxide.CO_(2) methanation over the supported Ru catalyst is structure sensitive.The size of the Ru catalyst and the support have significant effects on the activity and the mechanism.A significant challenge re-mained is the structural controllable preparation of the supported Ru catalyst toward a sufficiently high low-temperature activity.In this review,the recent progresses in the investigations of the supported Ru catalysts for CO_(2) methanation are summarized.The challenges and the future devel-opments are also discussed.

Selective hydrogenation of CO2 to methanol over Ni/In2O3 catalyst

An In2O3 supported nickel catalyst has been prepared by wet chemical reduction with sodium borohydride(NaBH4) as a reducing agent for selective hydrogenation of carbon dioxide to methanol. Highly dispersed Ni species with intense Ni-In2O3 interaction and enhanced oxygen vacancies have been achieved.The highly dispersed Ni species serve as the active sites for hydrogen activation and hydrogen spillover.Abundant H adatoms are thereby generated for the oxygen vacancy creation on the In2O3 surface. The enhanced surface oxygen vacancies further lead to improved CO2 conversion. As a result, an effective synergy between the active Ni sites and surface oxygen vacancies on In2O3 causes a superior catalytic performance for CO2 hydrogenation with high methanol selectivity. Carbon monoxide is the only by product detected. The formation of methane can be ignored. When the reaction temperature is lower than 225 ℃,the selectivity of methanol is 100%. It is higher than 64% at the temperature range between 225 ℃ and 275 ℃. The methanol selectivity is still higher than 54% at 300 ℃ with a CO2 conversion of 18.47% and a methanol yield of 0.55 gMeOHg-1cath-1(at 5 MPa). The activity of Ni/In2O3 is higher than most of the reported In2O3-based catalysts.

Effect of decomposition of catalyst precursor on Ni/CeO_2 activity for CO methanation

CO methanation on Ni/CeO2 has recently received increasing attention.However,the low-temperature activity and carbon resistance of Ni/CeO2 still need to be improved.In this study,plasma decomposition of nickel nitrate was performed at ca.150℃ and atmospheric pressure.This was followed by hydrogen reduction at 500 ℃ in the absence of plasma,and a highly dispersed Ni/CeO2 catalyst was obtained with improved CO adsorption and enhanced metal-support interaction.The plasma-decomposed catalyst showed significantly improved low-temperature activity with high methane selectivity(up to 100%)and enhanced carbon resistance for CO methanation.For example,at 250 ℃,the plasma-decomposed catalyst showed a CO conversion of 96.8% with high methane selectivity(almost 100%),whereas the CO conversion was only 14.7% for a thermally decomposed catalyst.

The feasibility study of the indium oxide supported silver catalyst for selective hydrogenation of CO_(2)to methanol

Silver catalyst has been extensively investigated for photocatalytic and electrochemical CO_(2) reduction.However,its high activity for selective hydrogenation of CO_(2) to methanol has not been confirmed.Here,the feasibility of the indium oxide supported silver catalyst was investigated for CO_(2) hydrogenation to methanol by the density functional theoretical(DFT)study and then by the experimental investigation.The DFT study shows there exists an intense Ag-In_(2)O_(3) interaction,which causes silver to be positively charged.The positively charged Ag species changes the electronic structure of the metal,facilitates the formation of the Ag-In_(2)O_(3) interfacial site for activation and dissociation of carbon dioxide.The promoted CO_(2) dissociation leads to the enhanced methanol synthesis via the CO hydrogenation route as CO_(2)^(*)→CO^(*)→HCO^(*)→H_(2)CO^(*)→H_(3)CO^(*)→H_(3)COH^(*).The Ag/In_(2)O_(3)catalyst was then prepared using the deposition-precipitation method.The experimental study confirms the theoretical prediction.The methanol selectivity of CO_(2) hydrogenation on Ag/In_(2)O_(3) reaches 100.0%at reaction temperature of 200℃.It remains more than 70.0%between 200 and 275℃.At 300℃and 5 MPa,the methanol selectivity still keeps 58.2%with a CO_(2) conversion of 13.6%and a space-time yield(STY)of methanol of 0.453 g_(methanol)g_(cat)^(-1)h^(-1),which is the highest methanol STY ever reported for silver catalyst.The catalyst characterization confirms the intense Ag-In_(2)O_(3)interaction as well,which causes high Ag dispersion,increases and stabilizes the oxygen vacancies and creates the active Ag-In_(2)O_(3)interfacial site for the enhanced CO_(2)hydrogenation to methanol.

Synergistic effect of the metal-support interaction and interfacial oxygen vacancy for CO_(2) hydrogenation to methanol over Ni/In_(2)O_(3) catalyst:A theoretical study

Indium oxide supported nickel catalyst has been experimentally confirmed to be highly active for CO_(2) hydrogenation towards methanol.In this work,the reaction mechanism for CO_(2) hydrogenation to methanol has been investigated on a model Ni/In_(2)O_(3) catalyst,i.e.,Ni_(4)/In_(2)O_(3),via the density functional theory(DFT)study.Three possible reaction pathways,i.e.,the formate pathway,CO hydrogenation and the reverse water-gas-shift(RWGS)pathways,have been examined on this model catalyst.It has been demonstrated that the RWGS pathway is the most theoretically-favored for CO_(2) hydrogenation to methanol.The complete RWGS pathway follows CO_(2)+6 H→COOH+5 H→CO+H_(2)O+4 H→HCO+H_(2)O+3 H→H_(2)CO+H_(2)O+2 H→H_(3)CO+H_(2)O+H→H_(3)COH+H_(2) O.Furthermore,it has been also proved that the interfacial oxygen vacancy can serve as the active site for boosting the CO_(2) adsorption and charge transfer between the nickel species and indium oxide,which synergistically promotes the consecutive CO_(2) hydrogenation towards methanol.

Prognostic significance of regional lymphadenectomy in T1b gallbladder cancer:Results from 24 hospitals in China

BACKGROUND Whether regional lymphadenectomy(RL)should be routinely performed in patients with T1b gallbladder cancer(GBC)remains a subject of debate.AIM To investigate whether RL can improve the prognosis of patients with T1b GBC.METHODS We studied a multicenter cohort of patients with T1b GBC who underwent surgery between 2008 and 2016 at 24 hospitals in 13 provinces in China.The logrank test and Cox proportional hazards model were used to compare the overall survival(OS)of patients who underwent cholecystectomy(Ch)+RL and those who underwent Ch only.To investigate whether combined hepatectomy(Hep)improved OS in T1b patients,we studied patients who underwent Ch+RL to compare the OS of patients who underwent combined Hep and patients who did not.RESULTS Of the 121 patients(aged 61.9±10.1 years),77(63.6%)underwent Ch+RL,and 44(36.4%)underwent Ch only.Seven(9.1%)patients in the Ch+RL group had lymph node metastasis.The 5-year OS rate was significantly higher in the Ch+RL group than in the Ch group(76.3%vs 56.8%,P=0.036).Multivariate analysis showed that Ch+RL was significantly associated with improved OS(hazard ratio:0.51;95%confidence interval:0.26-0.99).Among the 77 patients who underwent Ch+RL,no survival improvement was found in patients who underwent combined Hep(5-year OS rate:79.5%for combined Hep and 76.1%for no Hep;P=0.50).CONCLUSION T1b GBC patients who underwent Ch+RL had a better prognosis than those who underwent Ch.Hep+Ch showed no improvement in prognosis in T1b GBC patients.Although recommended by both the National Comprehensive Cancer Network and Chinese Medical Association guidelines,RL was only performed in 63.6%of T1b GBC patients.Routine Ch+RL should be advised in T1b GBC.

Improved activity of Ni/MgAl_2O_4 for CO_2 methanation by the plasma decomposition

CO2 methanation has been a hot topic because of its important application in the spacecraft and potential utilization of carbon dioxide. Nickel catalyst is active for this reaction. However, its activity still needs to be improved. Dielectric barrier discharge （DBD） plasma, initiated at ambient condition and operated at -150 ℃, has been employed in this work for decomposition of nickel precursor to prepare Ni/MgAl2O4. The plasma decomposition results in high dispersion, unique structure, enhanced reducibility of Ni particles and promoted catalyst-support interaction. An improved activity of CO2 methanation with a higher yield of methane has been achieved over the plasma decomposed catalyst, compared to the catalyst prepared thermally. For example, the methane yield of the plasma prepared catalyst is 71.8% at 300 ℃ but it is 62.9% over the thermal prepared catalyst. The catalyst characterization confirmed that CO2 methanation over the DBD plasma prepared catalyst follows pathway of CO methanation.

Electron-induced rapid crosslinking in supramolecular metal-peptide assembly and chemically responsive disaggregation for catalytic application

The applications of supramolecular metal-peptide assemblies as catalyst or catalyst precursor have recent attracted increasing attentions.In this work,a fragment of the amyloid β-peptide,NH_(2)-KLVFF-COOH,was assembled into nanofilms with encapsulated Pd,Pt and Au nanoparticles(NPs)via a one-step room temperature electron induction method.The effects of building block,intermolecular interaction,driving force and side-chain on the assembly were investigated.The assembly mechanism was thereby proposed.The crosslinking of peptide monomers results in mainly random and unordered structures.The obtained metal-peptide assemblies are extremely stable in water at neutral pH for long term.However,the metal NPs are able to be responsively released under basic and reductive conditions.The released NPs show a high activity to catalyze the reduction of 4-nitrophenol.The present studies on assembly mechanism and responsive release will be helpful for the design of organic skeletons and also for the future development of peptide stabilized metallic NPs with applications beyond catalysts.

Spatially distributed cytokinins:Metabolism,signaling,and transport

Cytokinins are mobile phytohormones that regulate plant growth,development,and environmental adaptability.The major cytokinin species include isopentenyl adenine(iP),trans-zeatin(tZ),cis-zeatin(cZ),and dihydrozeatin(DZ).The spatial distributions of different cytokinin species in different organelles,cells,tissues,and organs are primarily shaped by biosynthesis via isopentenyltransferases(IPT),cytochrome P450 monooxygenase,and 50-ribonucleotide phosphohydrolase and by conjugation or catabolism via glycosyltransferase or cytokinin oxidase/dehydrogenase.Cytokinins bind to histidine receptor kinases in the endoplasmic reticulum or plasma membrane and relay signals to response regulators in the nucleus via shuttle proteins known as histidine phosphotransfer proteins.The movements of cytokinins from sites of biosynthesis to sites of signal perception usually require long-distance,intercellular,and intracellular transport.In the past decade,ATP-binding cassette(ABC)transporters,purine permeases(PUP),AZA-GUANINE RESISTANT(AZG)transporters,equilibrative nucleoside transporters(ENT),and Sugars Will Eventually Be Exported transporters(SWEET)have been characterized as involved in cytokinin transport processes.This review begins by introducing the spatial distributions of various cytokinins and the subcellular localizations of the proteins involved in their metabolism and signaling.Highlights focus on an inventory of the characterized transporters involved in cytokinin compartmentalization,including long-distance,intercellular,and intracellular transport,and the regulation of the spatial distributions of cytokinins by environmental cues.Future directions for cytokinin research are also discussed.

A Cotton BURP Domain Protein Interacts With α-Expansin and Their Co-Expression Promotes Plant Growth and Fruit Production

Plant growth requires cell wall extension. The cotton AtRD22-Like I gene GhRDL1, predominately expressed in elongating fiber cells, encodes a BURP domain-containing protein. Here, we show that GhRDL1 is localized in cell wall and interacts with GhEXPA1, an α-expansin functioning in wall loosening. Transgenic cotton overexpressing GhRDL1 showed an increase in fiber length and seed mass, and an enlargement of endopleura cells of ovules. Expression of either GhRDL1 or GhEXPA1 alone in Arabidopsis led to a substantial increase in seed size; interestingly, their co-expression resulted in the increased number of siliques, the nearly doubled seed mass, and the enhanced biomass production. Cotton plants overexpressing GhRDL1 and GhEXPA1 proteins produced strikingly more fruits （bolls）, leading to up to 40% higher fiber yield per plant without adverse effects on fiber quality and vegetative growth. We demonstrate that engineering cell wall protein partners has a great potential in promoting plant growth and crop yield.

Deciphering the Enigma of Lignification： Precursor Transport, Oxidation, and the Topochemistry of Lignin Assembly

Plant lignification is a tightly regulated complex cellular process that occurs via three sequential steps： the synthesis of monolignols within the cytosol; the transport of monomeric precursors across plasma membrane; and the oxidative polymerization of monolignols to form lignin macromolecules within the cell wall. Although we have a reasonable understanding of monolignol biosynthesis, many aspects of lignin assembly remain elusive. These include the pre- cursors＇ transport and oxidation, and the initiation of lignin polymerization. This review describes our current knowledge of the molecular mechanisms underlying monolignol transport and oxidation, discusses the intriguing yet least- understood aspects of lignin assembly, and highlights the technologies potentially aiding in clarifying the enigma of plant lignification.

Characterization and Ectopic Expression of a Populus Hydroxyacid Hyd roxyci n nam oylt ra nsferase

Cutinized and suberized cell walls in plants constitute physiologically important environment interfaces. They act as barriers limiting the loss of water and nutrients and protecting against radiation and invasion of pathogens. The roles of cutin- and suberin polyesters are often attributed to their dominant aliphatic components, but the contri- bution of aromatic composition to their physiological function remains unclear. By functionally screening a subset of Populus trichocarpa BAHD/HXXXD acyltransferases, we identified a hydroxycinnamoyltransferase that shows specific transacylation activity on ~0-hydroxyacids using both feruloyl- and p-coumaroyl- CoA as the acyl donors. We named this enzyme P. trichocarpa hydroxyacid/fatty alcohol hydroxycinnamoyltransferase 1 （PtFHT1）. The ectopic expression of the PtFHT1 gene in Arabidopsis increased the incorporation of ferulate in root and seed suberins and in leaf cutin, but not that of p-coumarate, while the aliphatic load in both suberin and cutin polyesters essentially remained unaffected. The overaccumulation of ferulate in lipophilic polyester significantly increased the tolerance of transgenic plants to salt stress treatment; under sub-lethal conditions of salt stress, the ratios of their seed germination and seedling establishment were 50% higher than those of wild-type plants. Our study suggests that, although aromatics are the minor component of polyesters, they play important role in the sealing function of lipidic polymers in planta.

CO_(2) hydrogenation to methanol over Rh/In_(2)O_(3)–ZrO_(2)catalyst with improved activity

The In_(2)O_(3)supported rhodium catalyst has been previously confirmed to be active for CO_(2)hydrogenation to methanol.In this work,the In_(2)O_(3)–ZrO_(2)solid solution was prepared and employed to support the rhodium catalyst.The deposition-precipitation method was applied to make the Rh catalyst highly dispersed.The catalyst characterization confirms that the use of ZrO_(2)optimizes and stabilizes the oxygen vacancies of In_(2)O_(3),which causes the enhanced adsorption and activation of CO_(2).The highly dispersed Rh catalyst remarkably improves the hydrogenation ability of the In_(2)O_(3)–ZrO_(2)support.Compared to Rh/In_(2)O_(3),the In_(2)O_(3)–ZrO_(2)supported Rh catalyst shows significantly higher activity with high methanol selectivity.For instance,at 300℃ and 5 MPa,the methanol selectivity over Rh/In_(2)O_(3)–ZrO_(2)reaches 66.5%with a space-time yield(STY)of methanol of 0.684 g MeOH h^(-1) g cat-1 and a CO_(2)conversion of 18.1%.The methanol selectivity and methanol STY at 300℃ is 19% and 26% higher than that of the Rh/In_(2)O_(3)catalyst.

Templated synthesis of urchin-like zinc oxide particles by micro-combustion

Micro-combustion initiated by dielectric bar- tier discharge plasma has been applied for the removal of carbon template to prepare urchin-like ZnO particles. The combustion is operated at atmospheric pressure and low gas temperature （less than 150 ℃）, and the template is fully decomposed and rapidly removed. The obtained urchin-like ZnO possesses two distinct morphologies： nanosheets and sub-micro rods. The unique morphologies form on ZnO hexagonal nuclei with the template effect of activated carbon.

Photoelectrochemical performance of TiO_(2) nanotube arrays by in situ decoration with different initial states

Here,carbon dots(CDs) only or nanocomposites of CDs and TiO_(2)(CDs-TiO_(2)) were used to decorate titanium dioxide nanotube arrays(TiO_(2)NTs) in situ by solvothermal method.Two initial states of TiO_(2)NTs were prepared for contrast,including the amorphous TiO_(2)NTs(TiO_(2)NTs-0) just experienced anodic oxidation process and that further calcined TiO_(2)NTs(TiO_(2)NTs-450).It was found that the newborn CDs or CDs-TiO_(2)were more likely to anchor on TiO_(2)NTs-0 than the calcined TiO_(2)NTs-450,and more Ti-C bonds were found in the composites which were derived from TiO_(2)NTs-0 after the solvothermal treatment.An evident photocurrent could be demonstrated for either CDs or CDs-TiO_(2)decorated TiO_(2)NTs once exposed to visible light.And CDs-TiO_(2)NTs-0 showed the highest photocurrent density(4.51 μA·cm^(-2)).However,the results of photodegradation measurements revealed that CDs-TiO_(2)decorated TiO_(2)NTs with different initial states(especially CDs-TiO_(2)-TiO_(2)NTs-0) showed more excellent photocatalytic activity under both ultraviolet(UV) and visible light illumination.

Arabidopsis ABCG14 forms a homodimeric transporter for multiple cytokinins and mediates long-distance transport of isopentenyladeninetype cytokinins

Cytokinins(CKs),primarily trans-zeatin(tZ)and isopentenyladenine(iP)types,play critical roles in plant growth,development,and various stress responses.Long-distance transport of tZ-type CKs meidated by Arabidopsis ATP-binding cassette transporter subfamily G14(AtABCG14)has been well studied;however,less is known about the biochemical properties of AtABCG14 and its transporter activity toward iP-type CKs.Here we reveal the biochemical properties of AtABCG14 and provide evidence that it is also required for long-distance transport of iP-type CKs.AtABCG14 formed homodimers in human(Homo sapiens)HEK293T,tobacco(Nicotiana tabacum),and Arabidopsis cells.Transporter activity assays of AtABCG14 in Arabidopsis,tobacco,and yeast(Saccharomyces cerevisiae)showed that AtABCG14 may directly transport multiple CKs,including iP-and tZ-type species.AtABCG14 expression was induced by iP in a tZ-type CKdeficient double mutant(cypDM)of CYP735A1 and CYP735A2.The atabcg14 cypDM triple mutant exhibited stronger CK-deficiency phenotypes than cypDM.Hormone profiling,reciprocal grafting,and 2H6-iP isotope tracer experiments showed that root-to-shoot and shoot-to-root long-distance transport of iP-type CKs were suppressed in atabcg14 cypDM and atabcg14.These results suggest that AtABCG14 participates in three steps of the circular long-distance transport of iP-type CKs:xylem loading in the root for shootward transport,phloem unloading in the shoot for shoot distribution,and phloemunloading in the root for root distribution.We found that AtABCG14 displays transporter activity toward multiple CK species and revealed its versatile roles in circular long-distance transport of iP-type CKs.These findings provide newinsights into the transport mechanisms of CKs and other plant hormones.

Biological and Molecular Components for Genetically Engineering Biosensors in Plants

Plants adapt to their changing environments by sensing and responding to physical,biological,and chemical stimuli.Due to their sessile lifestyles,plants experience a vast array of external stimuli and selectively perceive and respond to specific signals.By repurposing the logic circuitry and biological and molecular components used by plants in nature,genetically encoded plant-based biosensors(GEPBs)have been developed by directing signal recognition mechanisms into carefully assembled outcomes that are easily detected.GEPBs allow for in vivo monitoring of biological processes in plants to facilitate basic studies of plant growth and development.GEPBs are also useful for environmental monitoring,plant abiotic and biotic stress management,and accelerating design-build-test-learn cycles of plant bioengineering.With the advent of synthetic biology,biological and molecular components derived from alternate natural organisms(e.g.,microbes)and/or de novo parts have been used to build GEPBs.In this review,we summarize the framework for engineering different types of GEPBs.We then highlight representative validated biological components for building plant-based biosensors,along with various applications of plant-based biosensors in basic and applied plant science research.Finally,we discuss challenges and strategies for the identification and design of biological components for plant-based biosensors.