Biomass conversion offers an efficient approach to alleviate the energy and environmental issues.Electrochemical oxidation of 5-hydroxymethylfurfural(HMF)has attracted tremendous attention in the latest few years for ...Biomass conversion offers an efficient approach to alleviate the energy and environmental issues.Electrochemical oxidation of 5-hydroxymethylfurfural(HMF)has attracted tremendous attention in the latest few years for the mild synthesis conditions and high conversion efficiency to obtain 2,5-furan dicarboxylic acid(FDCA),but there still remain problems such as limited yield,short cycle life,and ambiguous reaction mechanism.Despite many reviews highlighting a variety of electrocatalysts for electrochemical oxidation of HMF,a detailed discussion of the structural modulation of catalyst and the underlying catalytic mechanism is still lacking.We herein provide a comprehensive summary of the recent development of electrochemical oxidation of HMF to FDCA,particularly focusing on the mechanism studies as well as the advanced strategies developed to regulate the structure and optimize the performance of the electrocatalysts,including heterointerface construction,defect engineering,single-atom engineering,and in situ reconstruction.Experimental characterization techniques and theoretical calculation methods for mechanism and active site studies are elaborated,and challenges and future directions of electrochemical oxidation of HMF are also prospected.This review will provide guidance for designing advanced catalysts and deepening the understanding of the reaction mechanism beneath electrochemical oxidation of HMF to FDCA.展开更多
The unit cell configuration of lattice structures critically influences their load-bearing and energy absorption performance.In this study,three novel lattice structures were developed by modifying the conventional FB...The unit cell configuration of lattice structures critically influences their load-bearing and energy absorption performance.In this study,three novel lattice structures were developed by modifying the conventional FBCCZ unit cell through reversing,combining,and turning strategies.The designed lattices were fabricated via laser powder bed fusion(LPBF)using Ti-6Al-4V powder,and the mechanical properties,energy absorption capacity,and deformation behaviors were systematically investigated through quasi-static compression tests and finite element simulations.The results demonstrate that the three modified lattices exhibit superior performance over the conventional FBCCZ structure in terms of fracture strain,specific yield strength,specific ultimate strength,specific energy absorption,and energy absorption efficiency,thereby validating the efficacy of unit cell modifications in enhancing lattice performance.Notably,the CFBCCZ and TFBCCZ lattices significantly outperform both the FBCCZ and RFBCCZ lattice structures in load-bearing and energy absorption.While TFBCCZ shows marginally higher specific elastic modulus and energy absorption efficiency than CFBCCZ,the latter achieves superior energy absorption due to its highest ultimate strength and densification strain.Finite element simulations further reveal that the modified lattices,through optimized redistribution and adjustment of internal nodes and struts,effectively alleviate stress concentration during loading.This structural modification enhances the structural integrity and deformation stability under external loads,enabling a synergistic enhancement of load-bearing capacity and energy absorption performance.展开更多
A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was develo...A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory （IMCT）. A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.展开更多
To mitigate secondary electromagnetic pollution,there is an urgent need to develop absorption-dominant electromagnetic interference(EMI)shielding materials with low density,reduced thickness,lightweight construction,f...To mitigate secondary electromagnetic pollution,there is an urgent need to develop absorption-dominant electromagnetic interference(EMI)shielding materials with low density,reduced thickness,lightweight construction,flexibility,exceptional mechanical strength,and superior electrothermal and photothermal properties,particularly for flexible and wearable electronics.In this regard,we designed an absorption-based composite film comprising carbon nanotubes(CNT)and α-Fe_(2)O_(3),featuring a CNT layer sandwiched between twoα-Fe_(2)O_(3)layers on the upper and lower surfaces.This composite film was fabricated through an electrodeposition process followed by a thermal annealing procedure to achieve enhanced EMI shielding performance along with improved electrothermal and photothermal properties.The strategically designed sandwich structure allows the rough surface of the upper α-Fe_(2)O_(3)layer to not only improve the impedance mismatch between free space and the composite film,facilitating the penetration of incident electromagnetic(EM)waves into the film and promoting increased EM absorption rather than reflection,but also to enhance electrical conductivity,thereby improving electron mobility and density.Consequently,the average total shielding effectiveness(SE)of the CNT/Fe_(16)-300 composite demonstrates remarkable EMI shielding effectiveness(EMI SE:56.8 dB).Furthermore,the alteration in the absorption-to-reflection ratio(A/R)signifies a transition in the EMI shielding mechanism from reflection(0.69 for the pristine CNT film)to absorption(1.86 for the CNT/Fe_(16)-300)with the incremental deposition of α-Fe_(2)O_(3)nanoparticles.This work presents a feasible manufacturing approach for developing composite films with a sandwich structure that exhibits absorption-dominant EMI shielding capabilities,contributing to advancements in thermal management and multifunctional electromagnetic shielding applications.展开更多
Thermodynamic models of calculating mass action concentrations for structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions were developed based on the ion and...Thermodynamic models of calculating mass action concentrations for structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions were developed based on the ion and molecule coexistence theory at 298.15 K.A transformation coefficient is needed to compare the calculated mass action concentration and the reported activity because they are obtained at different standard states and concentration units.The results show that the transformation coefficients between the calculated mass action concentrations and the reported activities of the same structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions change in a very narrow range.The transformed mass action concentrations of structural units or ion couples in RbCl-H2O binary system are in good agreement with the reported activities. The transformed mass action concentrations of RbCl and RbNO3 in RbCl-RbNO3-H2O ternary solution are also in good agreement with the reported activities,aRbCl and 3RbNOa,with different total ionic strengths as 0.01,0.05,0.1,0.5,1.0,1.5,2.0,3.0 and 3.5 mol/kg,respectively.All those results mean the developed thermodynamic model of strong electrolyte aqueous solutions can reflect structural characteristics of RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions and the mass action concentration also strictly follows the mass action law.展开更多
In this paper the pumping unit of type QLCJ14-6 is studied.Through the belt driving unit,the mo-tor drives the driving sprocket in which the rotation rate has been reduced by the reduction ge arbox.The locus chain mov...In this paper the pumping unit of type QLCJ14-6 is studied.Through the belt driving unit,the mo-tor drives the driving sprocket in which the rotation rate has been reduced by the reduction ge arbox.The locus chain moves between the driving sprocket and upper sprocket which are vertically set.There's a special chain element in the locus chain,which drives the reciprocating holster with the main shaft linchpin and slide block.The r reciprocating g holster could only move up and down when the locus chain moves in a circle.In this way the up and down stroke of the sucker rod and the mac hine is realized.The lower end of the reciprocating holster is con-nected with the equilibrium system to make the structure balance.The balancing cylinder is re-placed by the balancing block to make the structure simplified.展开更多
In this paper, by the transparent-component-decimation （TCD） method we obtain three kinds of new basic- components （BCs） through simplifying and decomposing the BCs of three-component Thue-Morse （3CTM） sequence....In this paper, by the transparent-component-decimation （TCD） method we obtain three kinds of new basic- components （BCs） through simplifying and decomposing the BCs of three-component Thue-Morse （3CTM） sequence. Based on these new BCs we propose a type of basic-structural-units （BSUs） and investigate the optical transmission of the one-dimensional （1D） superlattices composed of these BSUs. It is found that if the substrates of the 1D BSU superlattices are certain, the optical transmission at the central wavelength （CW） will be determined completely by the number and the type of BSUs and has nothing to do with the marshalling sequence. In particular, if the substrates are identical, the numbers of different types of BSUs are all the same and the middle two elements of BSUs constitute a cycle, then no matter whether the system is periodic, or quasiperiodic, or aperiodic, or unordered, or even random, it will be transparent at the CW. The conclusion is confirmed by the numerical results. Similar to the even layers of neighbourhood identical elements in TCD method, such a kind of optical BSU subsystem can also be decimated from the chain in the process of transmission investigation. There would be a potential application in the designing of some interesting optical devices.展开更多
A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexi...A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.展开更多
DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structu...DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics（CFD） and computational aerodynamic acoustics（CAA） simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures（i.e. the heat sink, the bell-mouth type shroud and the outlet grille） upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring＇s size and throat＇s depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %（i.e. 100 m3·h～（-1）） at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.展开更多
This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The inp...This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The input circuit of a conventional inverter consists of a thick-gate-oxide n-type MOSFET(NMOS).These conventional drivers can tolerate a total ionizing dose(TID)of up to 100 krad(Si).In contrast,the proposed comparator input circuit uses both a thick-gate-oxide p-type MOSFET(PMOS)and thin-gate-oxide NMOS to offer a high input voltage and higher TID tolerance.Because the thick-gate-oxide PMOS and thin-gate-oxide NMOS collectively provide better TID tolerance than the thick-gate-oxide NMOS,the circuit exhibits enhanced TID tolerance of>300 krad(Si).Simulations and experimental date indicate that the DSS structure reduces the probability of unwanted parasitic bipolar junction transistor activation,yielding a better single-event effect tolerance of over 81.8 MeVcm^(2)mg^(-1).The innovative strategy proposed in this study involves circuit and layout design optimization,and does not require any specialized process flow.Hence,the proposed circuit can be manufactured using common commercial 0.35μm BCD processes.展开更多
The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated,especially the inhibitory role of lignin in non-productive adsorption with enzymes.Milled wood lignin(MWL)was i...The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated,especially the inhibitory role of lignin in non-productive adsorption with enzymes.Milled wood lignin(MWL)was isolated from different hardwoods of poplar,eucalyptus and acacia.The isolated lignin samples were characterized by elemental analysis,gel permeation chromatography,nitrobenzene oxidation and fourier infrared spectroscopy.The mechanism of lignin structural units on enzymatic hydrolysis of cellulose was studied by quartz crystal microbalance(QCM).The results showed that different structural units of lignin had different adsorption capacity for enzymes.The results of nitrobenzene oxidation indicated that the S/G ratio(S:syringyl-like lignin structures;G:guaiacyl-like lignin structures)of lignin of poplar was 0.99,that of eucalyptus was 1.92 and that of acacia was 1.34.According to the results of QCM,the adsorption capacity of the three lignin films was as follows:Poplar MWL(S/G ratio 0.99)<Acacia MWL(S/G ratio 1.34)<Eucalyptus MWL(S/G ratio 1.92).Eucalyptus MWL with higher degree of condensation and S/G ratio showed stronger affinity to enzymes and more non-productive adsorption with enzymes,resulting in less adsorption between enzymes and cellulose,and lower enzymatic hydrolysis efficiency.展开更多
Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and ...Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.展开更多
The high strength and stability of the full-lamellar structure guarantee the industrial application of theβ-solidifyingγ-TiAl alloys.However,it is a huge challenge to design an alloy with good hot-deformability as w...The high strength and stability of the full-lamellar structure guarantee the industrial application of theβ-solidifyingγ-TiAl alloys.However,it is a huge challenge to design an alloy with good hot-deformability as well as the full-lamellar structure.The low-cost Ti-42.5Al-2Mn-0.4Mo-0.1B-0.1C(at.%)alloy was designed,which undergoes bothβandαsingle-phase region during the solidification.It is found that the full-lamellar structure can be obtained by the solution heat treatment at 1230℃ for 20 min and then aging treatment at 800℃ for 3 h.Interestingly,a new microstructure,namely,the pearlitic-like microstructure(PM)induced by theα_(2)/γ→βo+γcellular reaction was observed when the aging temperature is increased to above 800℃.The volume fraction of the PM is gradually increased from 0%to 25.5%,65%,and 94%according to elevated aging temperature from 800 to 900,1000,and 1050℃,respectively.The mechanism of the reducedα_(2)/γlamellae and PM formation was discussed regarding the heterogeneous distribution ofβstabilizing elements and the interface energy stored inα_(2)/γlamellae.展开更多
The Douala-Buea Region(DBR;4°-5°N,9°-10°30’E),a portion of the southern Cameroon passive margin,developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcanosedimenta...The Douala-Buea Region(DBR;4°-5°N,9°-10°30’E),a portion of the southern Cameroon passive margin,developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcanosedimentary cover,was explored in order to evaluate the lithology and tectonics controls on its landscape usingthequalitativeandquantitative geomorphological analyses based on 30 m resolution Digital Elevation Models(DEM)and field evidences.This area displays an uneven and complex landscape differentiated into four morphological units:Douala,Nkondjock,Kumba and Buea Units.The Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/Camposedimentarybasin.The Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic basement.The Kumba Unit matches with the southernmost volcanic Western Cameroon High Plateau.The Buea Unit corresponds to the Mount Cameroon stratovolcano.The relief analysis through mountain-front sinuosity(Smf,1.19–1.43)and relative relief ratio(Rr,0.10–2.31)vary from one unit to another.The drainage network analysis including drainage patterns,stepped longitudinalriverprofiles,theassociated morphometric indexes,notably the concavity index(IC,0.56–0.88),deviation(D,267–2912 m),basin asymmetry factor(A_(F),6.37–42.12),hypsometric integral(HI,0.10–0.29),valley floor width to valley height ratio(V_(f),0.36–2.75),elongation ratio(R_(e),0.30–0.50),watershed slope(S,6.88–88.88)and stream length gradient index(SL,0–3332)vary from one basin to another too.These results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active tectonics.The drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points,asymmetric basins,and fault reactivations,and highlights the tectonics activity that used to occur through the time and their control on the morphology.Together,they document the lithostructural controls on the DBR landscape evolution,extendable in the whole SW Cameroon margin.展开更多
Using first-principle calculations, we investigate the mechanical, structural, and electronic properties and formation energy of 25 kinds of Ⅲ–V binary monolayers in detail. A relative radius of the binary compound ...Using first-principle calculations, we investigate the mechanical, structural, and electronic properties and formation energy of 25 kinds of Ⅲ–V binary monolayers in detail. A relative radius of the binary compound according to the atomic number in the periodic table is defined, and based on the definition, the 25 kinds of Ⅲ–V binary compounds are exactly located at a symmetric position in a symmetric matrix. The mechanical properties and band gaps are found to be very dependent on relative radius, while the effective mass of holes and electrons are found to be less dependent. A linear function between Young’s modulus and formation energy is fitted with a linear relation in this paper. The change regularity of physical properties of B–V(V = P, As, Sb, Bi) and Ⅲ–N(Ⅲ = Al, Ga, In, Tl) are found to be very different from those of other Ⅲ–V binary compounds.展开更多
The distribution of Al （j） and the structural units distribution of Qi T in calcium aluminosilicate melts were studied by means of molecular dynamics simulation. The results show that provided there exists lower-fie...The distribution of Al （j） and the structural units distribution of Qi T in calcium aluminosilicate melts were studied by means of molecular dynamics simulation. The results show that provided there exists lower-field strength cation relative to Al3+, such as alkaline and alkaline earth metals, Al will be four-coordinated but not six-coordinated. Meanwhile, if there exist a large number of higher-field strength cations such as Si4+ and little lower-field strength cation, six-coordinated aluminum will be formed. The relation of structural units distribution of Qi T with chemical composition shift was also extracted, showing that as Ca2+ exists, the distributions of Qi Si, Qi Al or Qi T have the similar changing trend with the variation of component. Because of high-temperature effect, the Al-tetrahedral units in melts are greatly active and unstable and there exist dynamic transforming equilibria of Al（3）Al（4） and （Al（5））Al（4）. The three-coordinated oxygen and charge-compensated bridging oxygen are proposed to explain phenomena of the negative charge redundancy of AlO4 and location of network modifier with charge-compensated function in aluminosilicate melts.展开更多
Two new Cd（Ⅱ） coordination polymers, [Cd（PT）（1,4-BDC）0.5]n （1） and [Cd（PT） （1,3-BDC）0.5]n （2） （HPT = 3-（pyridin-2-yl）-1,2,4-triazole, 1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzene...Two new Cd（Ⅱ） coordination polymers, [Cd（PT）（1,4-BDC）0.5]n （1） and [Cd（PT） （1,3-BDC）0.5]n （2） （HPT = 3-（pyridin-2-yl）-1,2,4-triazole, 1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid）, have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction as well as elemental analysis and IR. Complexes 1 and 2 are both three-dimensional coordination polymers with two-dimensional sheet structures bridged by the deprotonated carboxylate ligands. In 1, 1,4-BDC2- bridges the layered network to generate a quadrangular framework, and 2 owns a sexangular framework, which was caused by the different steric hindrance between 1,4-BDC^2- and 1,3-BDC^2-. Their thermal stabilities and photoluminescent properties have been also investigated.展开更多
2,3-Bis（hydroxymethyl）-2,3-dinitro-1,4-butanediol（C6H12N2O8） was synthesized by condensation,cyclization,oxidative dimerization and deketalization of nitromethane with a total yield of 42.4%.The structure of the t...2,3-Bis（hydroxymethyl）-2,3-dinitro-1,4-butanediol（C6H12N2O8） was synthesized by condensation,cyclization,oxidative dimerization and deketalization of nitromethane with a total yield of 42.4%.The structure of the title compound was characterized by 1H NMR,13C NMR,FT-IR,elementary analysis,and X-ray single-crystal diffraction analysis,which reveals that the title compound crystallizes in triclinic,space group P with a = 0.6324（2）,b = 0.6454（3）,c = 0.7062（3） nm,α= 111.550（4）,β= 95.505（4）,γ= 113.395（4）°,V = 0.23595（16） nm3,Z = 1,Mr = 240.18,Dc = 1.690 g·cm-3,μ = 0.159 mm-1,F（000） = 126,R = 0.0304 and wR = 0.0907.展开更多
Three new dimethyltin complexes of N-（3-methoxysalicylidene）-α-amino acid,（CH3）2Sn（3-CH3O-2-OC6H3CH=NCHRCOO）（R = H,1;CH3,2;（CH3）2CH,3）,have been synthe-sized by treating dimethyltin dichloride with the pota...Three new dimethyltin complexes of N-（3-methoxysalicylidene）-α-amino acid,（CH3）2Sn（3-CH3O-2-OC6H3CH=NCHRCOO）（R = H,1;CH3,2;（CH3）2CH,3）,have been synthe-sized by treating dimethyltin dichloride with the potassium salt of the ligand and characterized by elemental analysis,IR and 1H NMR spectra.The crystal structure of [（CH3）2Sn（3-CH3O-2-OC6H3CH=NCH2COO）（CH3OH）]2 H2O（1a）,formed from methanol solution of 1,has been deter-mined.The crystal belongs to the monoclinic system,space group C/2c with a = 20.636（3）,b = 7.8854（9）,c = 20.668（2） ,β= 113.265（2）°,V = 3089.7（6） 3,Z = 4,Dc = 1.707 g/cm3,= 1.675 mm-1,F（000） = 1592,R = 0.0301 and wR = 0.0841.In complex 1a,the tin atom is six-coordinate and possesses a distorted [SnC2NO3] octahedral geometry with the two methyl groups occupying the trans positions.The weak Sn O interactions and intermolecular hydrogen bonds connected the molecules into an infinite chain.展开更多
Elemental analysis, Fourier transform infrared （FTIR）, 1H-NMR, fluorescence spectroscopy, and surface tension methods have been used to characterize the molecular structure and the aggregation behaviors of two aspha...Elemental analysis, Fourier transform infrared （FTIR）, 1H-NMR, fluorescence spectroscopy, and surface tension methods have been used to characterize the molecular structure and the aggregation behaviors of two asphaltenic fractions derived, respectively, from an Alge- rian petroleum well and a corresponding storage tank deposit. Elemental analysis, FTIR, ~H-NMR, and fluores- cence spectroscopy were used to investigate the chemical composition and structural parameters of asphaltenes, while the surface tension method was used to measure the critical micelle concentration （CMC） in organic solvents with different solubility parameters and polarities in order to characterize the asphaltenes＇ aggregation behaviors. Results show that the unstable asphaltenes fraction extracted from the storage tank deposit possesses a higher polarity （higher heteroatoms content） and a lower aro- maticity than stable asphaltenes from the petroleum well. The CMC results indicate that asphaltenes with high polarity and low aromaticity have a high solubility in polar solvents such as nitrobenzene, whereas asphaltenes with low polarity and high aromaticity are more soluble in solvents with weak polarity, like toluene. It is concludedthat the difference of structure of asphaltene samples and polarity of solvents can lead to difference of aggregation behaviors.展开更多
基金National Natural Science Foundation of China(22272150,22302177)Major Program of Zhejiang Provincial Natural Science Foundation of China(LD22B030002)+2 种基金Zhejiang Provincial Ten Thousand Talent Program(2021R51009)Public Technology Application Project of Jinhua City(2022-4-067)Self Designed Scientific Research of Zhejiang Normal University(2021ZS0604)。
文摘Biomass conversion offers an efficient approach to alleviate the energy and environmental issues.Electrochemical oxidation of 5-hydroxymethylfurfural(HMF)has attracted tremendous attention in the latest few years for the mild synthesis conditions and high conversion efficiency to obtain 2,5-furan dicarboxylic acid(FDCA),but there still remain problems such as limited yield,short cycle life,and ambiguous reaction mechanism.Despite many reviews highlighting a variety of electrocatalysts for electrochemical oxidation of HMF,a detailed discussion of the structural modulation of catalyst and the underlying catalytic mechanism is still lacking.We herein provide a comprehensive summary of the recent development of electrochemical oxidation of HMF to FDCA,particularly focusing on the mechanism studies as well as the advanced strategies developed to regulate the structure and optimize the performance of the electrocatalysts,including heterointerface construction,defect engineering,single-atom engineering,and in situ reconstruction.Experimental characterization techniques and theoretical calculation methods for mechanism and active site studies are elaborated,and challenges and future directions of electrochemical oxidation of HMF are also prospected.This review will provide guidance for designing advanced catalysts and deepening the understanding of the reaction mechanism beneath electrochemical oxidation of HMF to FDCA.
基金supported by National Key Lab of Aerospace Power System and Plasma Technology Foundation of China(Grant No.APSPT202301002)National Natural Science Foundation of China(Grant No.52001038)Natural Science Foundation of Chongqing,China(Grant Nos.cstc2019jcyj-msxm X0787 and cstc2021jcyj-msxm X0011)。
文摘The unit cell configuration of lattice structures critically influences their load-bearing and energy absorption performance.In this study,three novel lattice structures were developed by modifying the conventional FBCCZ unit cell through reversing,combining,and turning strategies.The designed lattices were fabricated via laser powder bed fusion(LPBF)using Ti-6Al-4V powder,and the mechanical properties,energy absorption capacity,and deformation behaviors were systematically investigated through quasi-static compression tests and finite element simulations.The results demonstrate that the three modified lattices exhibit superior performance over the conventional FBCCZ structure in terms of fracture strain,specific yield strength,specific ultimate strength,specific energy absorption,and energy absorption efficiency,thereby validating the efficacy of unit cell modifications in enhancing lattice performance.Notably,the CFBCCZ and TFBCCZ lattices significantly outperform both the FBCCZ and RFBCCZ lattice structures in load-bearing and energy absorption.While TFBCCZ shows marginally higher specific elastic modulus and energy absorption efficiency than CFBCCZ,the latter achieves superior energy absorption due to its highest ultimate strength and densification strain.Finite element simulations further reveal that the modified lattices,through optimized redistribution and adjustment of internal nodes and struts,effectively alleviate stress concentration during loading.This structural modification enhances the structural integrity and deformation stability under external loads,enabling a synergistic enhancement of load-bearing capacity and energy absorption performance.
基金supported by the Publication Foundation of China National Science and Technology Academic Books
文摘A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory （IMCT）. A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.
基金financially supported by the National Natural Science Foundation of China(Nos.52222202 and 51772310)Chinese Academy of Sciences Key Research Program of Frontier Sciences(No.QYZDY-SSWJSC031)Shanghai Pilot Program for Basic Research-Chinese Academy of Science,Shanghai Branch(No.JCYJ-SHFY-2021-001).
文摘To mitigate secondary electromagnetic pollution,there is an urgent need to develop absorption-dominant electromagnetic interference(EMI)shielding materials with low density,reduced thickness,lightweight construction,flexibility,exceptional mechanical strength,and superior electrothermal and photothermal properties,particularly for flexible and wearable electronics.In this regard,we designed an absorption-based composite film comprising carbon nanotubes(CNT)and α-Fe_(2)O_(3),featuring a CNT layer sandwiched between twoα-Fe_(2)O_(3)layers on the upper and lower surfaces.This composite film was fabricated through an electrodeposition process followed by a thermal annealing procedure to achieve enhanced EMI shielding performance along with improved electrothermal and photothermal properties.The strategically designed sandwich structure allows the rough surface of the upper α-Fe_(2)O_(3)layer to not only improve the impedance mismatch between free space and the composite film,facilitating the penetration of incident electromagnetic(EM)waves into the film and promoting increased EM absorption rather than reflection,but also to enhance electrical conductivity,thereby improving electron mobility and density.Consequently,the average total shielding effectiveness(SE)of the CNT/Fe_(16)-300 composite demonstrates remarkable EMI shielding effectiveness(EMI SE:56.8 dB).Furthermore,the alteration in the absorption-to-reflection ratio(A/R)signifies a transition in the EMI shielding mechanism from reflection(0.69 for the pristine CNT film)to absorption(1.86 for the CNT/Fe_(16)-300)with the incremental deposition of α-Fe_(2)O_(3)nanoparticles.This work presents a feasible manufacturing approach for developing composite films with a sandwich structure that exhibits absorption-dominant EMI shielding capabilities,contributing to advancements in thermal management and multifunctional electromagnetic shielding applications.
基金Project supported by Publication Foundation of National Science and Technology Academic Books of China
文摘Thermodynamic models of calculating mass action concentrations for structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions were developed based on the ion and molecule coexistence theory at 298.15 K.A transformation coefficient is needed to compare the calculated mass action concentration and the reported activity because they are obtained at different standard states and concentration units.The results show that the transformation coefficients between the calculated mass action concentrations and the reported activities of the same structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions change in a very narrow range.The transformed mass action concentrations of structural units or ion couples in RbCl-H2O binary system are in good agreement with the reported activities. The transformed mass action concentrations of RbCl and RbNO3 in RbCl-RbNO3-H2O ternary solution are also in good agreement with the reported activities,aRbCl and 3RbNOa,with different total ionic strengths as 0.01,0.05,0.1,0.5,1.0,1.5,2.0,3.0 and 3.5 mol/kg,respectively.All those results mean the developed thermodynamic model of strong electrolyte aqueous solutions can reflect structural characteristics of RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions and the mass action concentration also strictly follows the mass action law.
文摘In this paper the pumping unit of type QLCJ14-6 is studied.Through the belt driving unit,the mo-tor drives the driving sprocket in which the rotation rate has been reduced by the reduction ge arbox.The locus chain moves between the driving sprocket and upper sprocket which are vertically set.There's a special chain element in the locus chain,which drives the reciprocating holster with the main shaft linchpin and slide block.The r reciprocating g holster could only move up and down when the locus chain moves in a circle.In this way the up and down stroke of the sucker rod and the mac hine is realized.The lower end of the reciprocating holster is con-nected with the equilibrium system to make the structure balance.The balancing cylinder is re-placed by the balancing block to make the structure simplified.
基金supported by the National Natural Science Foundation of China (Grant No.10974061)the Program for Innovative Research Team of the Higher Education in Guangdong,China (Grant No.06CXTD005)
文摘In this paper, by the transparent-component-decimation （TCD） method we obtain three kinds of new basic- components （BCs） through simplifying and decomposing the BCs of three-component Thue-Morse （3CTM） sequence. Based on these new BCs we propose a type of basic-structural-units （BSUs） and investigate the optical transmission of the one-dimensional （1D） superlattices composed of these BSUs. It is found that if the substrates of the 1D BSU superlattices are certain, the optical transmission at the central wavelength （CW） will be determined completely by the number and the type of BSUs and has nothing to do with the marshalling sequence. In particular, if the substrates are identical, the numbers of different types of BSUs are all the same and the middle two elements of BSUs constitute a cycle, then no matter whether the system is periodic, or quasiperiodic, or aperiodic, or unordered, or even random, it will be transparent at the CW. The conclusion is confirmed by the numerical results. Similar to the even layers of neighbourhood identical elements in TCD method, such a kind of optical BSU subsystem can also be decimated from the chain in the process of transmission investigation. There would be a potential application in the designing of some interesting optical devices.
基金Project supported by Publication Foundation of National Science and Technology Academic Books of China
文摘A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.
基金Supported by Program for Changjiang Scholars and Innovative Research Team in University,Ministry of Education of China(PCSIRT)
文摘DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics（CFD） and computational aerodynamic acoustics（CAA） simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures（i.e. the heat sink, the bell-mouth type shroud and the outlet grille） upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring＇s size and throat＇s depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %（i.e. 100 m3·h～（-1）） at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.
基金supported by the National Natural Science Foundation of China(U2241221).
文摘This article introduces a novel 20 V radiation-hardened high-voltage metal-oxide-semiconductor field-effect transistor(MOSFET)driver with an optimized input circuit and a drain-surrounding-source(DSS)structure.The input circuit of a conventional inverter consists of a thick-gate-oxide n-type MOSFET(NMOS).These conventional drivers can tolerate a total ionizing dose(TID)of up to 100 krad(Si).In contrast,the proposed comparator input circuit uses both a thick-gate-oxide p-type MOSFET(PMOS)and thin-gate-oxide NMOS to offer a high input voltage and higher TID tolerance.Because the thick-gate-oxide PMOS and thin-gate-oxide NMOS collectively provide better TID tolerance than the thick-gate-oxide NMOS,the circuit exhibits enhanced TID tolerance of>300 krad(Si).Simulations and experimental date indicate that the DSS structure reduces the probability of unwanted parasitic bipolar junction transistor activation,yielding a better single-event effect tolerance of over 81.8 MeVcm^(2)mg^(-1).The innovative strategy proposed in this study involves circuit and layout design optimization,and does not require any specialized process flow.Hence,the proposed circuit can be manufactured using common commercial 0.35μm BCD processes.
基金National Natural Science Foundation of China(31730106,21704045).
文摘The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated,especially the inhibitory role of lignin in non-productive adsorption with enzymes.Milled wood lignin(MWL)was isolated from different hardwoods of poplar,eucalyptus and acacia.The isolated lignin samples were characterized by elemental analysis,gel permeation chromatography,nitrobenzene oxidation and fourier infrared spectroscopy.The mechanism of lignin structural units on enzymatic hydrolysis of cellulose was studied by quartz crystal microbalance(QCM).The results showed that different structural units of lignin had different adsorption capacity for enzymes.The results of nitrobenzene oxidation indicated that the S/G ratio(S:syringyl-like lignin structures;G:guaiacyl-like lignin structures)of lignin of poplar was 0.99,that of eucalyptus was 1.92 and that of acacia was 1.34.According to the results of QCM,the adsorption capacity of the three lignin films was as follows:Poplar MWL(S/G ratio 0.99)<Acacia MWL(S/G ratio 1.34)<Eucalyptus MWL(S/G ratio 1.92).Eucalyptus MWL with higher degree of condensation and S/G ratio showed stronger affinity to enzymes and more non-productive adsorption with enzymes,resulting in less adsorption between enzymes and cellulose,and lower enzymatic hydrolysis efficiency.
基金Open Research Foundation of "Anhui Key Laboratory of Textile Materials",China(No.2006F2003)
文摘Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.
基金the Jihua Laboratory Scientific Research Project(No.X210291TL210)the National Natural Science Foundation of China(No.51971215).
文摘The high strength and stability of the full-lamellar structure guarantee the industrial application of theβ-solidifyingγ-TiAl alloys.However,it is a huge challenge to design an alloy with good hot-deformability as well as the full-lamellar structure.The low-cost Ti-42.5Al-2Mn-0.4Mo-0.1B-0.1C(at.%)alloy was designed,which undergoes bothβandαsingle-phase region during the solidification.It is found that the full-lamellar structure can be obtained by the solution heat treatment at 1230℃ for 20 min and then aging treatment at 800℃ for 3 h.Interestingly,a new microstructure,namely,the pearlitic-like microstructure(PM)induced by theα_(2)/γ→βo+γcellular reaction was observed when the aging temperature is increased to above 800℃.The volume fraction of the PM is gradually increased from 0%to 25.5%,65%,and 94%according to elevated aging temperature from 800 to 900,1000,and 1050℃,respectively.The mechanism of the reducedα_(2)/γlamellae and PM formation was discussed regarding the heterogeneous distribution ofβstabilizing elements and the interface energy stored inα_(2)/γlamellae.
文摘The Douala-Buea Region(DBR;4°-5°N,9°-10°30’E),a portion of the southern Cameroon passive margin,developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcanosedimentary cover,was explored in order to evaluate the lithology and tectonics controls on its landscape usingthequalitativeandquantitative geomorphological analyses based on 30 m resolution Digital Elevation Models(DEM)and field evidences.This area displays an uneven and complex landscape differentiated into four morphological units:Douala,Nkondjock,Kumba and Buea Units.The Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/Camposedimentarybasin.The Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic basement.The Kumba Unit matches with the southernmost volcanic Western Cameroon High Plateau.The Buea Unit corresponds to the Mount Cameroon stratovolcano.The relief analysis through mountain-front sinuosity(Smf,1.19–1.43)and relative relief ratio(Rr,0.10–2.31)vary from one unit to another.The drainage network analysis including drainage patterns,stepped longitudinalriverprofiles,theassociated morphometric indexes,notably the concavity index(IC,0.56–0.88),deviation(D,267–2912 m),basin asymmetry factor(A_(F),6.37–42.12),hypsometric integral(HI,0.10–0.29),valley floor width to valley height ratio(V_(f),0.36–2.75),elongation ratio(R_(e),0.30–0.50),watershed slope(S,6.88–88.88)and stream length gradient index(SL,0–3332)vary from one basin to another too.These results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active tectonics.The drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points,asymmetric basins,and fault reactivations,and highlights the tectonics activity that used to occur through the time and their control on the morphology.Together,they document the lithostructural controls on the DBR landscape evolution,extendable in the whole SW Cameroon margin.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61564002 and 11664005)the Guizhou Normal University Innovation and Entrepreneurship Education Research Center Foundation(Grant No.0418010)the Joint Foundation of Guizhou Normal University(Grant No.7341)
文摘Using first-principle calculations, we investigate the mechanical, structural, and electronic properties and formation energy of 25 kinds of Ⅲ–V binary monolayers in detail. A relative radius of the binary compound according to the atomic number in the periodic table is defined, and based on the definition, the 25 kinds of Ⅲ–V binary compounds are exactly located at a symmetric position in a symmetric matrix. The mechanical properties and band gaps are found to be very dependent on relative radius, while the effective mass of holes and electrons are found to be less dependent. A linear function between Young’s modulus and formation energy is fitted with a linear relation in this paper. The change regularity of physical properties of B–V(V = P, As, Sb, Bi) and Ⅲ–N(Ⅲ = Al, Ga, In, Tl) are found to be very different from those of other Ⅲ–V binary compounds.
文摘The distribution of Al （j） and the structural units distribution of Qi T in calcium aluminosilicate melts were studied by means of molecular dynamics simulation. The results show that provided there exists lower-field strength cation relative to Al3+, such as alkaline and alkaline earth metals, Al will be four-coordinated but not six-coordinated. Meanwhile, if there exist a large number of higher-field strength cations such as Si4+ and little lower-field strength cation, six-coordinated aluminum will be formed. The relation of structural units distribution of Qi T with chemical composition shift was also extracted, showing that as Ca2+ exists, the distributions of Qi Si, Qi Al or Qi T have the similar changing trend with the variation of component. Because of high-temperature effect, the Al-tetrahedral units in melts are greatly active and unstable and there exist dynamic transforming equilibria of Al（3）Al（4） and （Al（5））Al（4）. The three-coordinated oxygen and charge-compensated bridging oxygen are proposed to explain phenomena of the negative charge redundancy of AlO4 and location of network modifier with charge-compensated function in aluminosilicate melts.
基金supported by the National Natural Science Foundation of China(21501012 and 51203012)
文摘Two new Cd（Ⅱ） coordination polymers, [Cd（PT）（1,4-BDC）0.5]n （1） and [Cd（PT） （1,3-BDC）0.5]n （2） （HPT = 3-（pyridin-2-yl）-1,2,4-triazole, 1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid）, have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction as well as elemental analysis and IR. Complexes 1 and 2 are both three-dimensional coordination polymers with two-dimensional sheet structures bridged by the deprotonated carboxylate ligands. In 1, 1,4-BDC2- bridges the layered network to generate a quadrangular framework, and 2 owns a sexangular framework, which was caused by the different steric hindrance between 1,4-BDC^2- and 1,3-BDC^2-. Their thermal stabilities and photoluminescent properties have been also investigated.
基金Supported by the National "973" project (No. 613740102)
文摘2,3-Bis（hydroxymethyl）-2,3-dinitro-1,4-butanediol（C6H12N2O8） was synthesized by condensation,cyclization,oxidative dimerization and deketalization of nitromethane with a total yield of 42.4%.The structure of the title compound was characterized by 1H NMR,13C NMR,FT-IR,elementary analysis,and X-ray single-crystal diffraction analysis,which reveals that the title compound crystallizes in triclinic,space group P with a = 0.6324（2）,b = 0.6454（3）,c = 0.7062（3） nm,α= 111.550（4）,β= 95.505（4）,γ= 113.395（4）°,V = 0.23595（16） nm3,Z = 1,Mr = 240.18,Dc = 1.690 g·cm-3,μ = 0.159 mm-1,F（000） = 126,R = 0.0304 and wR = 0.0907.
基金supported by the Natural Science Foundation of Shandong Province (ZR2010BL012)thescientific research projects of Binzhou University (BZXYG0901,BZXYQNLG200912,BZXYFB20100403)
文摘Three new dimethyltin complexes of N-（3-methoxysalicylidene）-α-amino acid,（CH3）2Sn（3-CH3O-2-OC6H3CH=NCHRCOO）（R = H,1;CH3,2;（CH3）2CH,3）,have been synthe-sized by treating dimethyltin dichloride with the potassium salt of the ligand and characterized by elemental analysis,IR and 1H NMR spectra.The crystal structure of [（CH3）2Sn（3-CH3O-2-OC6H3CH=NCH2COO）（CH3OH）]2 H2O（1a）,formed from methanol solution of 1,has been deter-mined.The crystal belongs to the monoclinic system,space group C/2c with a = 20.636（3）,b = 7.8854（9）,c = 20.668（2） ,β= 113.265（2）°,V = 3089.7（6） 3,Z = 4,Dc = 1.707 g/cm3,= 1.675 mm-1,F（000） = 1592,R = 0.0301 and wR = 0.0841.In complex 1a,the tin atom is six-coordinate and possesses a distorted [SnC2NO3] octahedral geometry with the two methyl groups occupying the trans positions.The weak Sn O interactions and intermolecular hydrogen bonds connected the molecules into an infinite chain.
文摘Elemental analysis, Fourier transform infrared （FTIR）, 1H-NMR, fluorescence spectroscopy, and surface tension methods have been used to characterize the molecular structure and the aggregation behaviors of two asphaltenic fractions derived, respectively, from an Alge- rian petroleum well and a corresponding storage tank deposit. Elemental analysis, FTIR, ~H-NMR, and fluores- cence spectroscopy were used to investigate the chemical composition and structural parameters of asphaltenes, while the surface tension method was used to measure the critical micelle concentration （CMC） in organic solvents with different solubility parameters and polarities in order to characterize the asphaltenes＇ aggregation behaviors. Results show that the unstable asphaltenes fraction extracted from the storage tank deposit possesses a higher polarity （higher heteroatoms content） and a lower aro- maticity than stable asphaltenes from the petroleum well. The CMC results indicate that asphaltenes with high polarity and low aromaticity have a high solubility in polar solvents such as nitrobenzene, whereas asphaltenes with low polarity and high aromaticity are more soluble in solvents with weak polarity, like toluene. It is concludedthat the difference of structure of asphaltene samples and polarity of solvents can lead to difference of aggregation behaviors.
