Improving the performance of metal-organic frameworks for thermo-catalytic CO_(2)conversion:Strategies and perspectives

Climate change caused by the increasing emission of CO_(2)to the atmosphere has become a global concern.To ameliorate this issue,converting CO_(2)into valuable chemicals is highly desirable,enabling a sustainable low-carbon future.To this end,developing efficient catalytic systems for CO_(2)conversion has sparked intense interests from both academia and industry.Taking advantage of their highly porous structures and unique properties,metal−organic frameworks(MOFs)have shown great potential as heterogeneous catalysts for CO_(2)conversion.Various transformations involving CO_(2)have been accomplished over MOFs-based materials.Here we provide a comprehensive and up-to-date review on recent advances of heterogeneous CO_(2)thermocatalysis using MOFs,highlighting relationships between structures and properties.Special attention is given to the design strategies for improving the catalytic performance of MOFs.Avenues available to enrich the catalytic active sites in MOF structures are stressed and their respective impacts on CO_(2)conversion efficiency are presented.The synergistic effects between each active site within the structure of MOFs and derivatives are discussed.In the end,future perspectives and challenges in CO_(2)conversion by heterogeneous catalysis with MOFs are described.

Copper‐doped zinc sulfide nanoframes with three‐dimensional photocatalytic surfaces for enhanced solar driven H_(2) production

Solar‐to‐chemical energy conversion is perceived as one of the most potential solutions to the current energy and environmental crisis,yet requires major scientific endeavors on the development of efficient and sustainable photocatalysts.Remolding the composition and morphology of a semiconductor jointly for the purpose of improving photocatalysis efficiency remains challenging.Herein,we rationally fabricated Cu‐doped ZnS nanoframes via a simple conjunct strategy of substitutional doping,chemical acidic etching,and sulfidation,aiming at enhancing the light utilization and charge separation/transfer efficiency for solar‐light‐driven hydrogen generation.Cu‐doped zeolitic imidazolate framework‐8(ZIF‐8)rhombic dodecahedrons are transformed to hollow Cu‐ZIF‐8 nanoframes converted to Cu‐ZnS nanoframes with three‐dimensional photocatalytic active surfaces via anisotropic chemical etching,which is further converted to Cu‐ZnS nanoframes.By combining the merits of optimal heteroatom doping and frame‐like open architecture,the obtained 1%Cu‐doped ZnS nanoframe exhibits high photocatalytic activity under solar light irradiation with improved hydrogen production rate up to 8.30 mmol h^(–1) g^(–1) and excellent stability in the absence of cocatalysts,which is significantly improved in comparison with those of the bare ZnS and Cu‐ZnS with different morphologies.This work inspired by merging the merits of metal doping and anisotropic chemical etching may shed light on the rational design and fabrication of advanced photocatalysts.

Transition metal (Mo, Fe, Co, and Ni)-based catalysts for electrochemical CO_2 reduction

The electrochemical conversion of CO2 into value-added chemicals and fuels has attracted wide-spread concern since it realizes the recycling of greenhouse gases. Production of new materials lies at the very core of this technology as it enables the improvement of developmental efficiency and selectivity by chemical optimization of morphology and electronic structure. Transition metal-based catalysts are particularly appealing as their d bands have valence electrons which are close to the Fermi level and hence overcome the intrinsic activation barriers and reaction kinetics. The study of Mo, Fe, Co, and Ni-based materials in particular is a very recent research subject that offers various possibilities in electrochemical CO2 reduction applications. Herein, we summarize the recent re-search progress of Mo, Fe, Co, and Ni-based catalysts and their catalytic behavior in electrochemical CO〈sub〉2 reduction. We particularly focus on the relationship between structures and properties, with examples of the key features accounting for the high efficiency and selectivity of the CO2 reduction process. The most significant experimental and theoretical improvements are highlighted. Finally, we concisely discuss the scientific challenges and opportunities for transition metal-based catalysts.

Stabilization of heterogeneous hydrogenation catalysts for the aqueous-phase reactions of renewable feedstocks

The conversion of biomass-derived products to fine chemicals and fuels is extremely important for the utilization of renewable energy sources.Water is not only a by-product formed during the hydrogenation of biomass-derived oxygenated chemicals,but also an inexpensive and nontoxic solvent.The instability of solid catalysts for aqueous-phase reactions caused by metal leaching and the collapse of a catalyst support represents a significant challenge.In this work,various catalyst stabilization strategies including the nanospace and interfacial confinements that prevent sintering and leaching of metal nanoparticles as well as modification methods for increasing the support stability are summarized and systemically discussed.In addition,feasible approaches to designing stable and efficient heterogeneous catalysts for aqueous-phase reactions are proposed.

Effects of organic acids on heavy metal release or immobilization in contaminated soil

In order to explicit the environmental activity of heavy metals affected by different organic acids in soil,a batch incubation experiment was explored to investigate the influence of high relative molecular mass organic acid(HMWOA)(humic acid and fulvic acid)and low relative molecular mass organic acid(LMWOA)(threonic acid and oxalic acid)on the release or immobilization of Pb,Cu and Cd in soils.Results showed that LMWOA,especially threonic acid,had a good performance in the release of Pb,Cu and Cd from soils,and decrease in the fractions of HOAc-extractable,reducible and oxidable Pb,Cu and Cd.Conversely,HMWOA,especially humic acid,decreased the release of Pb,Cu and Cd,while it increased the fractions of HOAc-extractable,reducible and oxidable Pb,Cu and Cd,indicating that HMWOA can immobilize heavy metals.The release of Pb,Cu and Cd caused by LMWOA was attributed to the dissociation of soil organic matter and amorphous iron oxides since the total organic carbon and the water-soluble iron increased.The immobilization of Pb,Cu and Cd by HMWOA was attributed to the adsorption onto HMWOA followed by amorphous iron since HMWOA resulted in a significant decrease of zeta potential and an increase of amorphous iron oxide.It can be concluded that LMWOA has a potential application in soil washing remediation,while HMWOA can be used in the immobilization remediation for heavy metals contaminated soils.

Species Transformation of Trace Elements and Their Distribution Prediction in Dyestuff Residue Incineration

The release of heavy metals from the combustion of hazardous wastes is an environmental issue of in-creasing concern.The species transformation characteristics of toxic heavy metals and their distribution are consid-ered to be a complex problem of mechanism.The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication.Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free en-ergy minimization.The results show that Ni,Zn,Mn,and Cr are more enriched in dyestuff residue incineration than other heavy metals(Hg,As,and Se)subjected to volatilization.The thermodynamic model calculation is used for explaining the experiment data at 800℃ and analyzing species transformation of heavy metals.These results of species transformation are used to predict the distribution and emission characteristics of trace elements.Although most trace element predictions are validated by the measurements,cautions are in order due to the complexity of incineration systems.

Study on the Effect of Catalyst Properties on Residue Hydroconversion

The effect of catalyst properties on residue oil hydroconversion was studied at moderate operating conditions(at a temperature of 400 ℃, an initial hydrogen pressure of 10 MPa, and a reaction time of 4 h) in a batch mode slurry phase with different catalyst samples. The results showed that the catalyst acidity had a good effect on residue conversion and MCR(micro carbon residue) conversion but brought about higher coke yield. Residue conversion was thermally induced but the catalyst acidity changed its conversion route. A catalyst with higher metal loading, higher hydrogenation activity and appropriate pore size had higher sulfur and metal removal rate, higher MCR conversion and also a lower coke formation. The activity of spent commercial catalyst AS1 and DS1 was slightly lower than the corresponding fresh ones but was still high enough for residue oil hydroconversion. It assumes that the role of the catalyst is to activate hydrogen species toward reaction with an aromatic carbon radical to yield a cyclohexadienyl type intermediate which will turn into liquid and also to absorb the mesophase which can easily aggregate to form coke.

Redox Controllable Switch of Crystalline Phase and Physical Property in SrVO_x Epitaxial Films

Transition-metal oxides have attracted much attention due to its abundant crystalline phases and intriguing physical properties. However, some of these compounds are difficult to be fabricated directly in film form due to the ease of valence variation of transition-metal elements.In this work, we reveal the reversible structural transition between SrVO3 and Sr2V2O7 films via thermal treatment in oxygen atmosphere or in vacuum. Based on this, Sr2V2O7 epitaxial films are successfully synthesized and studied. Property characterizations show that the semitransparent and metallic SrVO3 could reversibly switch into transparent and insulating Sr2V2O7, implying potential applications in controllable electronic and optical devices.

Targeting of RhoE inhibits epithelial-mesenchymal transition during colorectal cancer cell migration

Objective Despite microRNA （miR-200b） being proved to promote the proliferation of colorectal cancer （CRC） cells, the relationship between miR-200b and epithelial-mesenchymal transition （EMT） of CRC cells remains poorly understood. The aim of the study was to investigate the relationship between miR-200b and EMT during CRC cell migration. Methods The effect of miR-200b on EMT-associated markers E-cadherin and vimentin was evaluated by western blot in CRC cells （SW620 and HT-29） by treatment with miR-200b mimics and inhibitors. A lucifer- ase reporter assay was employed to detect downstream targets of miR-200b. Transwell migration assays were used to detect CRC cell migration. Results Westem blots revealed that treatment with miR-200b mimics led to up-regulation of E-cadherin and down-regulation of vimentin, metalloproteinase （MMP）-9, and MMP-2, whereas treatment with miR- 200b inhibitor exhibited opposite effects on expression of E-cadherin and vimentin. Luciferase reporter assays demonstrated that RhoE （RND3） was targeted by miR-200b. Two predicted target sites of miR-200b were present in the 3＇-UTR of RhoE. Predicted target site 1 was from nucleotides 1584 to 1591, and site 2 was from nucleotides 1729 to 1735. RhoE knockdown cell lines were also established to investigate the impact of RhoE and miR-200b on EMT and cell migration. RhoE knockdown enhanced the effect of miR- 200b mimics, up-regulating E-cadherin and down-regulating vimentin. RhoE knockdown also inhibited cell migration. Furthermore, miR-200b mimic treatment further promoted the inhibitory effect of RhoE knock- down on cell migration.

Pickering interfacial biocatalysis with enhanced diffusion processes for CO_(2) mineralization

Utilization of carbon dioxide(CO_(2))has become a crucial and anticipated solution to address environmental and ecological issues.Enzymes such as carbonic anhydrase(CA)can efficiently convert CO_(2) into various platform chemicals under ambient conditions,which offers a promising way for CO_(2) utilization.Herein,we constructed a Pickering interfacial biocatalytic system(PIBS)stabilized by CA‐embedded MOFs(ZIF‐8 and ZIF‐L)for CO_(2) mineralization.Through structure engineering of MOFs and incorporation of Pickering emulsion,the internal and external diffusion processes of CO_(2) during the enzymatic mineralization were greatly intensified.When CO_(2) was ventilated at a flow rate of 50 mL min^(–1) for 1 h,the pH value of PIBS dropped from~8.00 to~6.50,while the average pH value of free system only dropped to~7.15,indicating that the initial reaction rate of CO_(2) mineralization of PIBS is nearly twice that of the free system.After the 8^(th) cycle reaction,PIBS can still produce more than 9.8 mg of CaCO_(3) in 5 min,realizing efficient and continuous mineralization of CO_(2).

Antifibrotic effect of aloe vera in viral infection-induced hepatic periportal fibrosis

AIM:To investigate the anti-oxidative and anti-fibrotic effects of aloe vera in patients with liver fibrosis.METHODS:Aloe vera high molecular weight fractions(AHM) were processed by patented hyper-dry system in combination of freeze-dry technique with microwave and far infrared-ray radiation.Fifteen healthy volunteers as the control group and 40 patients were included.The patients were randomly subdivided into two equal groups:the conventional group was treated with placebo(starch),and AHM group was treated with 0.15 gm/d AHM,both for 12 consecutive weeks.The patients were investigated before and after treatment.Serum activity of aspartate aminotransferase(AST),alanine aminotransferase(ALT),alkaline phosphatase(ALP),hyaluronic acid(HA),transforming growth factor-β(TGF-β) and matrixmetalloproteinase-2(MMP-2) were determined.The reduced glutathione(GSH) and malondialdehyde(MDA) levels in liver were assayed and the expression of hepatic α-smooth muscle actin(α-SMA) was identified by immunohistochemistry.RESULTS:At the start of the study,the hematoxylin and eosin staining revealed fibro-proliferated bile ductules,thick fibrous septa and dense inflammatory cellular infiltration in the patients before treatment.The use of AHM for 12 wk significantly ameliorated the fibrosis,inhibited the inflammation,and resulted in minimal infiltration and minimal fibrosis compared to the conventional group.The enzyme activities of the liver(ALT,AST and ALP) were attenuated after treatment in both groups,and the decrease in the AHM group was more significant as compared with the conventional group.Similar to the AST,the MDA levels were significantly higher before treatment,and were attenuated after treatment in both groups.In contrast,the hepatic glutathione content in the patients were decreased significantly in the AHM group compared to the controls.The serum levels of the fibrosis markers(HA,TGF-β and MMP-2) were also reduced significantly after treatment.The expression of α-SMA was modified in patients before and after treatment as compared with the normal controls.In the conventional group,there was only thin and incomplete parenchymal α-SMA positive septum joining the thickened centrilobular veins,while in the AHM group,few α-SMA positive cells were present in sinusoid and lobule after treatment.CONCLUSION:Oral supplementation with AHM could be helpful in alleviating the fibrosis and inflammation of hepatic fibrosis patients.

New Level-Shift LDMOS Structure for a 600 V-HVIC on Thick SOl

A novel level-shift LDMOS （lateral double-diffused metal oxide semiconductor） structure with the HV （high voltage） -interconnection for a 600 V-HVIC （high voltage integrated circuit） on thick SOI （silicon on insulator） is proposed. There are two original points in the proposed structure. One is the formation of the double floating p-layers under the HV-interconnection to prevent potential distribution in the drift from disturbing due to the HV-interconnection, and the other is a good combination between the LDMOS structure and multiple trench isolation to obtain the isolation performance over 600 V. From the proposed structure, the high blocking capability of the LDMOS, including both off- and on-breakdown voltages over 600 V and high hot carrier instability, and the isolation performance over 1,200 V can be obtained successfully. This paper will show numerical and experimental results in detail.

Determination of Selected Toxic Elements in Apples from Organic Farming

Due to the elevated ecological awareness nowadays the consumption of products of organic agriculture is increasing. Organic farming means excluding the use of synthetic inputs, such as synthetic fertilizers and pesticides or genetically modified organisms, but there are only a few regulations regarding heavy metal concentrations in soils. Thus a not negligible uptake of metals from the soil where the apple trees are grown may occur. Furthermore inorganic copper compounds being traditional fertilizers for apple trees are not considered as synthetic fertilizers, thus they are still used in organic apple farming for soil or foliar application. Thus also apples produced by organic agriculture may contain toxic elements, such as cadmium, chromium, copper, and lead. The concentrations of these elements were determined in whole apples, as well as in the flesh and peel in order to estimate the possible risk for human health. Prior to analysis using ICP-AES samples underwent a microwave assisted digestion. The LODs obtained are below the recommended maximum levels in vegetables/fruits by WHO. In all samples no Cu, Cr, and Pb could be detected. Only Ca was found in the peel of about a third of samples investigated in concentrations between LOD and LOQ （1-3 μg/g）.

Integration of Power MOSFETs for Synchronous Buck Converters

Efficiency and power loss in the microelectronic devices is a major issue in power electronics applications. The engineers are challenged every year to increase power density and at the same time reduce the amount of power dissipated in the applications to keep the maximum temperatures under specifications. This situation drives a constant demand for better efficiencies in smaller packages. Traditional approaches to improve efficiency in DC/DC synchronous buck converters include reducing conduction losses in the MOSFETs （metal oxide semiconductor field effect transistors） through lower RDS （ON） （resistance drain to source in the ON state） devices and lowering switching losses through low-frequency operation. However, the incremental improvements in RDS （ON） are at a point of diminishing returns and low RDS （ON） devices have large parasitic capacitances that do not facilitate the high-frequency operation required to improve power density. The drive for higher efficiency and increased power in smaller packages is being addressed by advancements in both silicon and packaging technologies. The NexFET power block combines these two technologies to achieve higher levels of performance, and in half the space versus discrete MOSFETs. This article explains these new technologies and highlights their performance advantage.

Infrared Spectroscopy of CO2 Transformation by Group Ⅲ Metal Monoxide Cations

Infrared photodissociation spectroscopy of mass-selected[MO(CO2)n]^+(M=Sc,Y,La)complexes indicates that the conversion from the solvated structure into carbonate one can be achieved by the ScO^+ cation at n=5 and by the YO^+ cation at n=4,while only the solvated structures are observed for the LaO^+ cation.These findings suggest that both the ScO^+ and YO^+cations are able to fix CO2 into carbonate.Quantum chemical calculations are performed on[MO(CO2)n]^+ to identify the structures of the low-lying isomers and to assign the observed spectral features.Theoretical analyses show that the[YO(CO2)n]^+ complex has the smallest barrier for the conversion from the solvated structure into carbonate one,while[LaO(CO2)n]^+ exhibits the largest conversion barrier among the three metal oxide cations.The present system affords a model in clarifying the effect of different metals in catalytic CO2 transformation at the molecular level.

A 150 mV-1.2 V Fully-Integrated DC-DC Converter for Thermal Energy Harvesting

With the increasing use of low voltage portable devices and wireless systems, energy harvesting has become an attractive approach to overcome the problems associated with battery life and power source. Among the different types of microenergy scavengers, the TEG （thermoelectric generators） are one of the most commonly used one. Unfortunately, due to the very small amount of voltage delivered by the TEG, an efficient DC/DC （direct current/direct current） conversion and power management techniques are needed. In this paper, a CMOS （complementary metal oxide semiconductor） fully-integrated DC/DC convener for energy harvesting applications is presented. The startup-voltage of the converter is about 140 mV, the output voltage exceeds 1.5 V, with a 20% power efficiency at least. The architecture for boosting such extremely low voltages is based on an ultra-low-voltage oscillator cross connected to two phase charge pump. The overall circuit does not require any external components and can be fully integrated in a standard CMOS low voltage technology. A test-chip has been designed in UMC （united microelectronics corporation） 180 nm CMOS process.

Soil Heavy Metal Pollution and Bioavailability in Baoshantao Mining Area, China

In areas with a high geological background of heavy metals,some edible plants could pose a serious threat to human health.In order to find effective methods to remove heavy metals or reduce their harm,this study investigated the enrichment conditions of five soil heavy metals,Cd,Pb,Cu,Zn and Cr,in four edible plants in a mining area,Baoshantao,in eastern China that has a high geological background of metals,and two groups of experiments were designed to investigate the effects of passivators on their enrichment.The results showed that the soil heavy metal content in the study area has a certain degree of spatial variability.The five heavy metal element contaminants in the soil are in the order of Cd>Cu>Zn>Pb>Cr.The enrichment coefficients and the transfer coefficients of different edible plants were different for the different heavy metals.The two groups of passivators showed better passivating effects with an increase in passivating agent dosage.The smaller the enrichment coefficient of water spinach,the lower the bioavailability.The results of this study can provide a scientific basis for the restoration of soil heavy metal pollution and the safe use of land in areas with a high geological background of heavy metals.

亚铜催化芳基硼酸三氟甲基化反应的理论研究

本文运用密度泛函理论(DFT)计算研究了以Togni试剂为氟源,CuI/邻二氮菲催化的芳基硼酸三氟甲基化反应机理.计算结果表明,该反应经历转金属化-协同亲电取代路径,通过协同的五元环过渡态亲电取代过程实现三氟甲基转移.反应势能面分析显示,芳基硼酸与铜催化剂的转金属化是整个反应路径的决速步,其活化能是21.7 kcal/mol.在此基础上,对比计算了苯乙基硼酸与铜催化剂的转金属化过程,研究结果表明,与苯基硼酸相比,烷基硼酸的转金属化的能垒更高,是动力学不利的过程.

Hidden spin polarization in the 1T-phase layered transition-metal dichalcogenides MX_2(M = Zr, Hf; X = S, Se, Te)

The recent discovery of hidden spin polarization emerging in layered materials of specific nonmagnetic crystal is a fascinating phenomenon, though hardly explored yet. Here, we have studied hidden spin tex- tures in layered nonmagnetic 1 T-phase transition-metal dichalcogenides MX2 （M = Zr, Hf; X = S, Se, Te） by using first-principles calculations. Spin-layer locking effect, namely, energy-degenerate opposite spins spatially separated in the top and bottom layer respectively, has been identified. In particular, the hidden spin polarization of 13-band can be easily probed, which is strongly affected by the strength of spin-orbit coupling. The hidden spin polarization of k-band locating at high symmetry M point （conduction band minimum） has a strong anisotropy. In the bilayer, the hidden spin polarization is preserved at the upmost Se layer, while being suppressed if the ZrSe2 layer is taken as the symmetry partner. Our results on hidden spin polarization in 1 T-phase dichalcogenides, verifiable by spin-resolved and angle-resolved photoemis- sion spectroscopy （ARPES）, enrich our understanding of spin physics and provide important clues to search for specific spin polarization in two dimensional materials for spintronic and quantum informa- tion applications.

Effect of acupuncture plus thunder-fire moxibustion on MMP-3, TIMP-1 and TGF-β1 in rats with knee osteoarthritis

Objective： To observe the effect of acupuncture plus thunder-fire moxibustion on the expressions of matrix metalloproteinase-3 （MMP-3）, tissue inhibitor of metalloproteinase-1 （TIMP-1） and transforming growth factor-β1 （TGF-β1） in cartilage of knee osteoarthritis （KOA） rats, and to explore the mechanism of acupuncture plus thunder-fire moxibustion in the treatment of KOA. Methods： Thirty Sprague-Dawley （SD） rats were randomly divided into a blank control group, a model group and an acupuncture-moxibustion group by random digits table, 10 rats in each group. Rats in the model group and the acupuncture-moxibustion group were injected with papain in the right posterior knee joint to prepare the models. The levels of MMP-3 and TIMP-1 in rat synovium of each group were measured by enzyme-linked immunosorbent assay （ELBA） after 2 weeks of treatment. The level of TGF-β1 was determined by Motic B5 Micro-camera system. Results： The levels of MMP-3 and TIMP-1 in the cartilage of the model group were significantly higher than those in the blank control group （all P〈0.01）; the levels of MMP-3 and TIMP-1 in the acupuncture-moxibustion group were lower than those in the model group, and the between-group differences were statistically significant （all P〈0.05）. The levels of MMP-3 and TIMP-1 in the acupuncture-moxibustion group were higher than those in the blank control group, and the differences were statistically significant （all P〈0.05）. The level of TGF-β1 in cartilage tissues of the model group was significantly lower than that in the blank control group （P〈0.01）; the level of TGF-β1 in the acupuncture-moxibustion group was higher than that in the model group （P〈0.05）, but it was lower than that in the blank control group, and the between-group difference was statistically significant （P〈0.05）. Conclusion： Acupuncture plus thunder-fire moxibustion can effectively recover the abnormal expressions of MMP-3 and TIMP-1 in KOA model rats and somewhat up-regulate TGF-β1, which may be one of its mechanisms of acupuncture plus thunder-fire for KOA.