The risk of radiation-induced second cancer and the late tissue loss due to Off-field doses in radiotherapy remain a serious concern. Monte Carlo (MC) simulation is currently one of the most accurate methods for calcu...The risk of radiation-induced second cancer and the late tissue loss due to Off-field doses in radiotherapy remain a serious concern. Monte Carlo (MC) simulation is currently one of the most accurate methods for calculating these doses. MC simulation model based on the Particle Simulation Tool (TOPAS) has been developed to simulate the off-field dose of an Elekta Synergy linear accelerator (Linac) emitting 6 MV photons. Measurements were taken in a water phantom using an ionization chamber to validate this model. The Percentage Depth Dose (PDD) at the depth of 0.0, 5.0, 10.0 and 15.0 cm from the beam axis for a 10 × 10 cm2 field size was measured and simulated. Off-field dose profiles at the depth of 1.5 (dmax), 5.0 and 10.0 cm for field sizes of 5 × 5, 10 × 10, 15 × 15, and 20 × 20 cm2 respectively were measured and simulated. Comparison of measured and simulated off-field dose values showed a good agreement. The average gamma passing rate of the PDDs and profiles curves for off-field doses were 87.5% and 98.11% respectively. The local dose difference based on the PDD curve between the measured and simulated was less than 6.0 % for all locations. For all field size considered in this study, the average difference between profile curves for off-field dose measured and simulated was 9.1%. PDDs and Profiles curves for off-field dose simulation uncertainties were less than 2.0% and 1.0% respectively. TOPAS-MC simulation model developed is a good representation of our 6 MV Linac Elekta Synergy for assessing off-field dose, which would be the primary cause of some secondary cancers.展开更多
The quadratic boost is studied under its real model. The equations, of the continuous conduction mode, descriptive of this model are established. From these equations, the expressions of the voltage gain and the effic...The quadratic boost is studied under its real model. The equations, of the continuous conduction mode, descriptive of this model are established. From these equations, the expressions of the voltage gain and the efficiency are extracted. These two quantities are plotted as a function of the duty cycle in order to appreciate them in different operating points of the transistor. The values of the different components have also been extracted for the fabrication of a prototype of the converter. Thanks to a set of experimental measurements at the input as well as at the output of the prototype converter, the voltage gain and the efficiency could also be observed. These were also plotted for different loads to observe converter behavior. The theoretical curves were compared with the experimental curves which allowed to validate the proposed mathematical models on a large range of duty cycles.展开更多
Ultra low carbon steels by the thermal mechanical control process（TMCP） with less Ni,Cr,and Mo contents have been developed for 550 MPa grade heavy gauge ship hulls and offshore structures.The relationships among mi...Ultra low carbon steels by the thermal mechanical control process（TMCP） with less Ni,Cr,and Mo contents have been developed for 550 MPa grade heavy gauge ship hulls and offshore structures.The relationships among microstructures,process,and properties of the studied steel have been investigated.A series of accurate control technologies have been developed for this kind of steel.Cu microalloying and TMCP＋relaxation precipitation control（RPC）＋accelerated cooling process were employed to optimize the mechanical properties and ensure the homogeneity of the 80-mm thick plate.The microstructures of thin plates slightly changed from surface to center,but the micro-structures of the heavy gauge plate（80 mm） changed notably.Adopting the simple composition,it can meet the requirement of thin plates by adopting a few microalloys.As for thick plates（80 mm）,a little higher Cu and Ni contents should be adopted.These steels can meet the needs without tempering.By these ways,the properties of the steels can be optimized,and the cost can be decreased notably.展开更多
Two new isostructure nickel（Ⅱ） coordination polymers, [Ni2（5-Me-ip）（1,2- Bie）（H2O）2]n （1） and [Ni2（5-Br-ip）（1,2-Bie）（H2O）2]n （2） （5-Me-H2ip = 5-methylisophthalic acid, 5-Br-H2ip = 5-mromoisophthali...Two new isostructure nickel（Ⅱ） coordination polymers, [Ni2（5-Me-ip）（1,2- Bie）（H2O）2]n （1） and [Ni2（5-Br-ip）（1,2-Bie）（H2O）2]n （2） （5-Me-H2ip = 5-methylisophthalic acid, 5-Br-H2ip = 5-mromoisophthalic acid, 1,2-Bie = 1,2-bis（imidazole）ethane）, have been synthesized and structurally characterized by single-crystal X-ray diffraction. The result shows that complexes 1 and 2 crystallize in orthorhombic system, space group Pna21 with a = 16.3602（13）, b = 10.1465（8）, c = 21.8803（17）A^°, V = 3632.1（5） A^°3, Z = 4, Dc = 1.525 g/cm3, F（000） = 1728, R = 0.0292 and wR = 0.0668 for 6646 observed reflections （I 〉 2σ（I）） for complex 1 and a = 16.409（3）, b = 10.1625（17）, c = 21.918（4）A^°, V = 3654.9（11） A^°3, Z = 4, Dc = 1.752 g/cm^3, F（000） = 1936, R = 0.0309 and wR = 0.0600 for 6809 observed reflections （I 〉 2σ（I）） for complex 2. They both feature zigzag 2D layer structures, which are further staked along the a-axis through π…π and hydrogen interactions to form 3D supramolecular structures.展开更多
The compound [Cd（L）2（NO3）]NO3·0.5H2O （L = N-benzyl-2-（quinolin-8-yloxy）aceta- mide） 1 has been synthesized and structurally determined by single-crystal X-ray diffraction, elemental analysis, IR and UV sp...The compound [Cd（L）2（NO3）]NO3·0.5H2O （L = N-benzyl-2-（quinolin-8-yloxy）aceta- mide） 1 has been synthesized and structurally determined by single-crystal X-ray diffraction, elemental analysis, IR and UV spectroscopy. The crystal belongs to the triclinic system, space group P1 with a = 11.7175（13）, b = 11.8873（13）, c = 14.0958（16） A, α = 74.889（2）, β= 78.228（2）, γ = 78.831（2）°, V= 1835.0（4） A3, Z= 1, Dc= 1.502 Mg/m3, Mr = 1660.17,μ = 0.662 mm-1, F（000） = 846, 2（MoKa） = 0.71073 A, the final R = 0.0585 and wR = 0.0577 for all observed reflections. The results show that the Cd（II） ion with a square antiprismatic geometry is coordinated by a N206 donor set, two NO2 sets from two ligands and two O atoms from a bidendate nitrate group. In the crystal, the O-H...O and N-H...O hydrogen bonds are helpful to consolidate the three- dimensional network.展开更多
A novel lanthanum（III） complex, [LaL2（NO3）3].H2O （1） based on L （L = N-（na- phthalene-l-yl）-2-（quinolin-8-yloxy）acetamide）, was synthesized and characterized by X-ray diffraction. The crystal of I belongs ...A novel lanthanum（III） complex, [LaL2（NO3）3].H2O （1） based on L （L = N-（na- phthalene-l-yl）-2-（quinolin-8-yloxy）acetamide）, was synthesized and characterized by X-ray diffraction. The crystal of I belongs to the monoclinic system, space group C2c with Mr= 1017.69, a = 25.1438（17）, b = 13.5950（9）, c = 18.2349（12） A, β= 132.4980（10）° V= 4595.8（5） A3, Z= 4, Dc = 1.471 Mg/m3, F（000） = 2056,μ= 1.004 mm-1, R = 0,0588 and wR = 0.1402. The central La（lI1） ion is coordinated to four oxygen atoms, two nitrogen atoms from two independent acetarnide ligands and six oxygen atoms from three nitrate anions, possessing a distorted icosahedron coordination geometry. In the crystal of 1, intermolecular N-H……O hydrogen bonds linked the molecules into chains along the c axis. In solid state and CH3CN solution, complex 1 exhibits stronger fluorescent emission than the ligand L.展开更多
A new 3D copper（Ⅱ） coordination polymer, {[Cu_2（tbip）_2（1,3,5-tib）]×2H_2O}n（1, H_2 tbip = 5-tert-butyl isophthalic acid, 1,3,5-tib = 1,3,5-tris（1-imidazolyl）benzene）, has been synthesized by hydrotherm...A new 3D copper（Ⅱ） coordination polymer, {[Cu_2（tbip）_2（1,3,5-tib）]×2H_2O}n（1, H_2 tbip = 5-tert-butyl isophthalic acid, 1,3,5-tib = 1,3,5-tris（1-imidazolyl）benzene）, has been synthesized by hydrothermal reaction of Cu（OAc）_2·4H_2O, H_2 tbip and 1,3,5-tib. It has been structurally characterized by element analysis, IR and magnetic measurement. X-ray single-crystal analysis was carried out for 1, which crystallizes in the triclinic system, space group P1 with a = 7.822（3）, b = 15.854（6）, c = 17.553（6） ？, a = 113.033（4）, β = 90.694（4）, g = 101.006（4）°, V = 1957.3（12） ？~3, Z = 1, D_c = 1.493 g/cm^3, M_r = 1759.70, F（000） = 908, R = 0.0721 and w R = 0.1978 with I 〉 2s（I）. The single-crystal X-ray diffraction studies reveal that compound 1 exhibits 2D [Cu（tbip）] layers which are further pillared by 1,3,5-tib ancillary ligand with terminal tridentate coordination mode to generate the final 3D structure. Magnetic susceptibility data for 1 have been measured in the range of 2~300 K. There are antiferromagnetic interactions between copper ions of the compound.展开更多
The pit morphology and growth kinetics of commercially pure aluminium in naturally aerated NaCl solutions were studied using an image processing method based on reflected light microscopy. In order to distinguish betw...The pit morphology and growth kinetics of commercially pure aluminium in naturally aerated NaCl solutions were studied using an image processing method based on reflected light microscopy. In order to distinguish between pits and pre-existing cavities, metallographic examination and statistical analysis were carried out before and after corrosion testing. The results show that the pit shapes and sizes are more dependent on the immersion time than the chloride concentration. Pits are predominantly hemispherical, but they undergo reasonable geometric transitions associated with increased immersion time and occur without significant depth variation. The role of chloride ions is more closely associated with the pit nucleation phenomenon.展开更多
We report in this paper the ground-state energy 2s^(2)^(1)S and total energies of doubly excited states 2p^(2)^(1)D,3d^(2)^(1)D,4f^(2)^(1)I of the Helium isoelectronic sequence from H-to Ca^(18+).Calculations are perf...We report in this paper the ground-state energy 2s^(2)^(1)S and total energies of doubly excited states 2p^(2)^(1)D,3d^(2)^(1)D,4f^(2)^(1)I of the Helium isoelectronic sequence from H-to Ca^(18+).Calculations are performed using the Modified Atomic Orbital Theory(MAOT)in the framework of a variational procedure.The purpose of this study required a mathematical development of the Hamiltonian applied to Slater-type wave function[1]combining with Hylleraas-type wave function[2].The study leads to analytical expressions which are carried out under special MAXIMA computational program.This first proposed MAOT variational procedure,leads to accurate results in good agreement as well as with available other theoretical results than experimental data.In the present work,a new correlated wave function is presented to express analytically the total energies for the 2s21S ground state and each doubly 2p^(2)^(1)D,3d^(2)^(1)D,4f^(2)^(1)I excited states in the He-like systems.The present accurate data may be a useful guideline for future experimental and theoretical studies in the(nI^(2))systems.展开更多
The compound [Cu2（bpy）2（PDIAla）（H2O）2]（ClO4）2·H2O（H2PDIAla = N,N＇-（p-xylylene）dialanine,bipy = 2,2＇-bipyridine） 1 has been synthesized and structurally determined by single-crystal X-ray diffraction...The compound [Cu2（bpy）2（PDIAla）（H2O）2]（ClO4）2·H2O（H2PDIAla = N,N＇-（p-xylylene）dialanine,bipy = 2,2＇-bipyridine） 1 has been synthesized and structurally determined by single-crystal X-ray diffraction,elemental analyses and IR spectroscopy.The crystal belongs to the monoclinic system,space group P21 with a = 10.9772（6）,b = 18.5464（9）,c = 11.0790（6） ,β = 116.3110o,V = 2021.87（18） 3,Z = 2,Dc = 1.594 Mg/m3,Mr = 970.70,μ = 1.260 mm-1,F（000） = 996,λ（MoKα） = 0.71073 ,the final R = 0.0400 and wR = 0.1050 for all observed reflections.In the structure,the O（5）-H（52）…O（4） hydrogen bonding between aqua ligand and carbonyl oxygen of the H2PDIAla ligand along the c axis produce hydrogen-bonded helices which are assembled along the b axis through O（61）-H（61）…O（2） and N（6）-H（6N）…O（2） interactions to form 2-D layers that are further linked by π···π interactions between bpy ligands to yield a three-dimensional supramolecular network.展开更多
According to the related theory about gas discharge, the numerical model of a gas discharge tube is established. With the help of particle simulation method, the curve of relationship between gas ignition voltage, gas...According to the related theory about gas discharge, the numerical model of a gas discharge tube is established. With the help of particle simulation method, the curve of relationship between gas ignition voltage, gas pressure and electrode distance product is studied through computer simulation on physical process of producing plasma by DC neon discharge, and a complete consistence between the simulation result and the experimental curve is realized.展开更多
This study was carried out to investigate the interaction of oxalic acid with hydrochloric acid to attain the better performance for iron dissolution in comparison to absence of oxalic acid. The effects of oxalic acid...This study was carried out to investigate the interaction of oxalic acid with hydrochloric acid to attain the better performance for iron dissolution in comparison to absence of oxalic acid. The effects of oxalic acid on ratio of hydrochloric acid, acid concentration, ratio of liquid to solid, temperature and dissolution time are investigated for the dissolution of Fe and Ti from ilmenite to produce synthetic rutile. The DX7 software basing on an experimental design method with the central composite of response surface design is applied to specify the effects of the parameters and to optimize the leaching process. The optimum condition was determined by analysis of variance (ANOVA), indicating that the ratio of oxalic acid to hydrochloric acid for Fe dissolution and acid concentration for Ti dissolution were the most effective parameters. The results showed that the dissolution of Fe and Ti in 30% (w/w) hydrochloric acid solution was only 48.65% and 5.14%, respectively, while at the same condition and in the presence of oxalic acid with twice the ratio, these values are increased to 78.65% and 12.06%, respectively. The optimum values of parameters were as follows: oxalic acid to hydrochloric acid ratio (2:1), acid concentration (30%), ratio of liquid to solid (10), temperature (160 °C), and dissolution time (3 h). By applying the optimized parameters, Fe and Ti dissolution of 97.15% and 2.8% were predicted by the software with a desirability of 0.745. The results of leaching tests indicated that the Fe and Ti dissolution of 97.58% and 2.43%, were achieved, respectively, which are very close to the predicted value.展开更多
Background: Accumulating reactive oxygen species (ROS) is involved in cellular signaling and function disturbances due to the oxidative stress, which contributes to several diseases. The consequences of ROS activity r...Background: Accumulating reactive oxygen species (ROS) is involved in cellular signaling and function disturbances due to the oxidative stress, which contributes to several diseases. The consequences of ROS activity represent an im-portant mechanism on the pathogenesis of vascular diseases, such as hypertension. Increased blood pressure observed in renal hypertension of the 2 kidneys-1 clip (2K-1C) model involves increased ROS levels in the cardiovascular system. Resveratrol, a polyphenolic compound primarily found in red wine, has many biological and pharmacological proper-ties. Considering the antioxidant properties of resveratrol, the present study was aimed to investigate the effects of the chronic treatment with resveratrol on cardiovascular system from renal hypertensive rats. Results: 2K-1C hypertension presented increased blood pressure, which was reduced at the end of the fifth week of resveratrol treatment. The cardiac hypertrophy index and the basal levels of ROS in rat aortic rings were also reduced by resveratrol treatment. Conclusions: The present findings clearly show the protective effects from resveratrol on the blood pressure, the car-diac growth and the vascular ROS generation in renal hypertension.展开更多
Systematic optimization of the photocatalyst and investigation of the role of each component is important to maximizing catalytic activity and comprehending the photocatalytic conversion of CO_(2) reduction to solar f...Systematic optimization of the photocatalyst and investigation of the role of each component is important to maximizing catalytic activity and comprehending the photocatalytic conversion of CO_(2) reduction to solar fuels.A surface-modified Ag@Ru-P25 photocatalyst with H_(2)O_(2) treatment was designed in this study to convert CO_(2) and H_(2)O vapor into highly selective CH4.Ru doping followed by Ag nanoparticles(NPs)cocatalyst deposition on P25(TiO_(2))enhances visible light absorption and charge separation,whereas H_(2)O_(2) treatment modifies the surface of the photocatalyst with hydroxyl(–OH)groups and promotes CO_(2) adsorption.High-resonance transmission electron microscopy,X-ray photoelectron spectroscopy,X-ray absorption near-edge structure,and extended X-ray absorption fine structure techniques were used to analyze the surface and chemical composition of the photocatalyst,while thermogravimetric analysis,CO_(2) adsorption isotherm,and temperature programmed desorption study were performed to examine the significance of H_(2)O_(2) treatment in increasing CO_(2) reduction activity.The optimized Ag1.0@Ru1.0-P25 photocatalyst performed excellent CO_(2) reduction activity into CO,CH4,and C2H6 with a~95%selectivity of CH4,where the activity was~135 times higher than that of pristine TiO_(2)(P25).For the first time,this work explored the effect of H_(2)O_(2) treatment on the photocatalyst that dramatically increases CO_(2) reduction activity.展开更多
We fabricate flexible conductive and transparent graphene films on position-emission-tomography substrates and prepare large area graphene films by graphite oxide sheets with the new technical process. The multi-layer...We fabricate flexible conductive and transparent graphene films on position-emission-tomography substrates and prepare large area graphene films by graphite oxide sheets with the new technical process. The multi-layer graphene oxide sheets can be chemically reduced by HNO3 and HI to form a highly conductive graphene film on a substrate at lower temperature. The reduced graphene oxide sheets show a high conductivity sheet with resistance of 476Ω/sq and transmittance of 76% at 550nm （6 layers）. The technique used to produce the transparent conductive graphene thin film is facile, inexpensive, and can be tunable for a large area production applied for electronics or touch screens.展开更多
A small electrical explosion of wire （EEW） setup for nanopowder production is constructed. It consists of a low inductance capacitor bank of 2 μF–4 μF typically charged to 8 kV–30 kV, a triggered gas switch, and...A small electrical explosion of wire （EEW） setup for nanopowder production is constructed. It consists of a low inductance capacitor bank of 2 μF–4 μF typically charged to 8 kV–30 kV, a triggered gas switch, and a production chamber housing the exploding wire load and ambient gas. With the EEW device, nanosize powders of titanium oxides, titanium nitrides, copper oxides, and zinc oxides are successfully synthesized. The average particle size of synthesized powders under different experimental conditions is in a range of 20nm–80nm. The pressure of ambient gas or wire vapor can strongly affect the average particle size. The lower the pressure, the smaller the particle size is. For wire material with relatively high resistivity, such as titanium, whose deposited energy Wd is often less than sublimation energy W s due to the flashover breakdown along the wire prematurely ending the Joule heating process, the synthesized particle size of titanium oxides or titanium nitrides increases with overheat coefficient k （k = W d /Ws ） increasing.展开更多
A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-...A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-PDMAEMA-grafted-Fe3O4 magnetic nanoparticles with amino and epoxy groups were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermo-gravimetric analysis, and scanning electron microscopy. Lipase from Burkholderia cepacia was successfully immobilized onto the magnetic nanoparticles by physical adsorption and covalent bonding. The immobilization capacity of the magnetic particles is 0.5 mg lipase per mg support, with an activity recovery of up to 43.1% under the optimum immobilization condition. Biochemical characterization shows that the immobilized lipase exhibits improved thermal stability, good tolerance to organic solvents with high lg P, and higher p H stability than the free lipase at p H 9.0. After six consecutive cycles, the residual activity of the immobilized lipase is still over55% of its initial activity.展开更多
The interactions between four high bioactive diperoxovanadate complexes Kn[OV(O2)2L]mH2O (n = 1~3, m = 1~5, L = oxalate (abbr. oxa), picolinate (abbr. pic), bipyridine (abbr. bipy) and 1,10-phenanthroline (abbr. phen)...The interactions between four high bioactive diperoxovanadate complexes Kn[OV(O2)2L]mH2O (n = 1~3, m = 1~5, L = oxalate (abbr. oxa), picolinate (abbr. pic), bipyridine (abbr. bipy) and 1,10-phenanthroline (abbr. phen); their corresponding complexes abbreviated as bpV(oxa), bpV(pic), bpV(bipy) and bpV(phen), respectively) and imidazole (abbr. imi) in solution were studied by several NMR techniques: multinuclear (1H, 13C and 51V) and variable temperature 51V NMR. Competitive coordination interactions were observed and the order of the interaction strength of the four complexes with imidazole is as follows: bpV(oxa) > bpV(pic) > bpV(bipy) > bpV(phen), which is deeply affected by the identity of the ligands and has the same order as their inhibition effect toward bovine heart phosphotyrosyl protein phosphatase. The species [OV- (O2)2(imi)]- was formed in all cases. Both of the NMR data and equilibrium constants of the interaction systems were reported. The experimental results indicate that the species of bpV(oxa) and [OV(O2)2(imi)]- are six-coordinated, while bpV(pic), bpV(bipy) and bpV(phen) are seven- coordinated in solution. ESI-MS results support the conclusions obtained by NMR.展开更多
The use of carbon‐based materials is an appealing strategy to solve the issue of excessive CO_(2) emis‐sions.In particular,metal‐free nitrogen‐doped carbon materials(mf‐NCs)have the advantages of convenient synth...The use of carbon‐based materials is an appealing strategy to solve the issue of excessive CO_(2) emis‐sions.In particular,metal‐free nitrogen‐doped carbon materials(mf‐NCs)have the advantages of convenient synthesis,cost‐effectiveness,and high conductivity and are ideal electrocatalysts for the CO_(2) reduction reaction(CO_(2)RR).However,the unclear identification of the active N sites and the low intrinsic activity of mf‐NCs hinder the further development of high‐performance CO_(2)RR electrocat‐alysts.Achieving precise control over the synthesis of mf‐NC catalysts with well‐defined active N‐species sites is still challenging.To this end,we adopted a facile synthesis method to construct a set of mf‐NCs as robust catalysts for CO_(2)RR.The resulting best‐performing catalyst obtained a Far‐adaic efficiency of CO of approximately 90%at−0.55 V(vs.reversible hydrogen electrode)and good stability.The electrocatalytic performance and in situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy measurements collectively revealed that graphitic and pyridinic N can synergistically adsorb CO_(2) and H_(2)O and thus promote CO_(2) activation and protonation.展开更多
The catalytic performance of Molybdenum disulfide(MoS_(2)) has been still far from that of Pt-based catalysts for inadequate active sites and sluggish electron transfer kinetics. Through engineering the interface betw...The catalytic performance of Molybdenum disulfide(MoS_(2)) has been still far from that of Pt-based catalysts for inadequate active sites and sluggish electron transfer kinetics. Through engineering the interface between MoS_(2)-based materials and supported substrates, hybrid Ru-doped MoS_(2) on carbonized lignin(CL) is designed and prepared as efficient catalyst for hydrogen evolution reaction(HER). The CL substrate not only facilitates the growth of MoS_(2) nanoflowers, but also promotes the electron transfer. Ru doping increases active sites greatly for HER. The hybrid catalyst achieves a low onset overpotential of 25 mV and a low Tafel slope of 46 m V dec^(-1). The favorable HER activity ascribes to the interfacial interaction between MoS_(2) and CL. Density functional theory calculations further confirm the improved HER performance with doped Ru atoms. This study presents a prototype application to design electrocatalysts with enhanced carrier mobility and high-density active sites based on interface effect.展开更多
文摘The risk of radiation-induced second cancer and the late tissue loss due to Off-field doses in radiotherapy remain a serious concern. Monte Carlo (MC) simulation is currently one of the most accurate methods for calculating these doses. MC simulation model based on the Particle Simulation Tool (TOPAS) has been developed to simulate the off-field dose of an Elekta Synergy linear accelerator (Linac) emitting 6 MV photons. Measurements were taken in a water phantom using an ionization chamber to validate this model. The Percentage Depth Dose (PDD) at the depth of 0.0, 5.0, 10.0 and 15.0 cm from the beam axis for a 10 × 10 cm2 field size was measured and simulated. Off-field dose profiles at the depth of 1.5 (dmax), 5.0 and 10.0 cm for field sizes of 5 × 5, 10 × 10, 15 × 15, and 20 × 20 cm2 respectively were measured and simulated. Comparison of measured and simulated off-field dose values showed a good agreement. The average gamma passing rate of the PDDs and profiles curves for off-field doses were 87.5% and 98.11% respectively. The local dose difference based on the PDD curve between the measured and simulated was less than 6.0 % for all locations. For all field size considered in this study, the average difference between profile curves for off-field dose measured and simulated was 9.1%. PDDs and Profiles curves for off-field dose simulation uncertainties were less than 2.0% and 1.0% respectively. TOPAS-MC simulation model developed is a good representation of our 6 MV Linac Elekta Synergy for assessing off-field dose, which would be the primary cause of some secondary cancers.
文摘The quadratic boost is studied under its real model. The equations, of the continuous conduction mode, descriptive of this model are established. From these equations, the expressions of the voltage gain and the efficiency are extracted. These two quantities are plotted as a function of the duty cycle in order to appreciate them in different operating points of the transistor. The values of the different components have also been extracted for the fabrication of a prototype of the converter. Thanks to a set of experimental measurements at the input as well as at the output of the prototype converter, the voltage gain and the efficiency could also be observed. These were also plotted for different loads to observe converter behavior. The theoretical curves were compared with the experimental curves which allowed to validate the proposed mathematical models on a large range of duty cycles.
基金supported by the National High-Tech Research and Development Program of China(No.2006AA03Z057)
文摘Ultra low carbon steels by the thermal mechanical control process（TMCP） with less Ni,Cr,and Mo contents have been developed for 550 MPa grade heavy gauge ship hulls and offshore structures.The relationships among microstructures,process,and properties of the studied steel have been investigated.A series of accurate control technologies have been developed for this kind of steel.Cu microalloying and TMCP＋relaxation precipitation control（RPC）＋accelerated cooling process were employed to optimize the mechanical properties and ensure the homogeneity of the 80-mm thick plate.The microstructures of thin plates slightly changed from surface to center,but the micro-structures of the heavy gauge plate（80 mm） changed notably.Adopting the simple composition,it can meet the requirement of thin plates by adopting a few microalloys.As for thick plates（80 mm）,a little higher Cu and Ni contents should be adopted.These steels can meet the needs without tempering.By these ways,the properties of the steels can be optimized,and the cost can be decreased notably.
基金supported by the Natural Science Foundation of Henan Province(122300410418,132200410404)
文摘Two new isostructure nickel（Ⅱ） coordination polymers, [Ni2（5-Me-ip）（1,2- Bie）（H2O）2]n （1） and [Ni2（5-Br-ip）（1,2-Bie）（H2O）2]n （2） （5-Me-H2ip = 5-methylisophthalic acid, 5-Br-H2ip = 5-mromoisophthalic acid, 1,2-Bie = 1,2-bis（imidazole）ethane）, have been synthesized and structurally characterized by single-crystal X-ray diffraction. The result shows that complexes 1 and 2 crystallize in orthorhombic system, space group Pna21 with a = 16.3602（13）, b = 10.1465（8）, c = 21.8803（17）A^°, V = 3632.1（5） A^°3, Z = 4, Dc = 1.525 g/cm3, F（000） = 1728, R = 0.0292 and wR = 0.0668 for 6646 observed reflections （I 〉 2σ（I）） for complex 1 and a = 16.409（3）, b = 10.1625（17）, c = 21.918（4）A^°, V = 3654.9（11） A^°3, Z = 4, Dc = 1.752 g/cm^3, F（000） = 1936, R = 0.0309 and wR = 0.0600 for 6809 observed reflections （I 〉 2σ（I）） for complex 2. They both feature zigzag 2D layer structures, which are further staked along the a-axis through π…π and hydrogen interactions to form 3D supramolecular structures.
基金supported by the National Natural Science Foundation of China(21001040)
文摘The compound [Cd（L）2（NO3）]NO3·0.5H2O （L = N-benzyl-2-（quinolin-8-yloxy）aceta- mide） 1 has been synthesized and structurally determined by single-crystal X-ray diffraction, elemental analysis, IR and UV spectroscopy. The crystal belongs to the triclinic system, space group P1 with a = 11.7175（13）, b = 11.8873（13）, c = 14.0958（16） A, α = 74.889（2）, β= 78.228（2）, γ = 78.831（2）°, V= 1835.0（4） A3, Z= 1, Dc= 1.502 Mg/m3, Mr = 1660.17,μ = 0.662 mm-1, F（000） = 846, 2（MoKa） = 0.71073 A, the final R = 0.0585 and wR = 0.0577 for all observed reflections. The results show that the Cd（II） ion with a square antiprismatic geometry is coordinated by a N206 donor set, two NO2 sets from two ligands and two O atoms from a bidendate nitrate group. In the crystal, the O-H...O and N-H...O hydrogen bonds are helpful to consolidate the three- dimensional network.
基金supported by the National Natural Science Foundation of China(21001040)Education Department of Henan Province(No.12B150011 and 14B150029)
文摘A novel lanthanum（III） complex, [LaL2（NO3）3].H2O （1） based on L （L = N-（na- phthalene-l-yl）-2-（quinolin-8-yloxy）acetamide）, was synthesized and characterized by X-ray diffraction. The crystal of I belongs to the monoclinic system, space group C2c with Mr= 1017.69, a = 25.1438（17）, b = 13.5950（9）, c = 18.2349（12） A, β= 132.4980（10）° V= 4595.8（5） A3, Z= 4, Dc = 1.471 Mg/m3, F（000） = 2056,μ= 1.004 mm-1, R = 0,0588 and wR = 0.1402. The central La（lI1） ion is coordinated to four oxygen atoms, two nitrogen atoms from two independent acetarnide ligands and six oxygen atoms from three nitrate anions, possessing a distorted icosahedron coordination geometry. In the crystal of 1, intermolecular N-H……O hydrogen bonds linked the molecules into chains along the c axis. In solid state and CH3CN solution, complex 1 exhibits stronger fluorescent emission than the ligand L.
基金supported by the National Natural Science Foundation of China(Nos.21271098 and 21371089)Science and Technology Research Key Project of the Education Department of Henan Province(No.14B150034)
文摘A new 3D copper（Ⅱ） coordination polymer, {[Cu_2（tbip）_2（1,3,5-tib）]×2H_2O}n（1, H_2 tbip = 5-tert-butyl isophthalic acid, 1,3,5-tib = 1,3,5-tris（1-imidazolyl）benzene）, has been synthesized by hydrothermal reaction of Cu（OAc）_2·4H_2O, H_2 tbip and 1,3,5-tib. It has been structurally characterized by element analysis, IR and magnetic measurement. X-ray single-crystal analysis was carried out for 1, which crystallizes in the triclinic system, space group P1 with a = 7.822（3）, b = 15.854（6）, c = 17.553（6） ？, a = 113.033（4）, β = 90.694（4）, g = 101.006（4）°, V = 1957.3（12） ？~3, Z = 1, D_c = 1.493 g/cm^3, M_r = 1759.70, F（000） = 908, R = 0.0721 and w R = 0.1978 with I 〉 2s（I）. The single-crystal X-ray diffraction studies reveal that compound 1 exhibits 2D [Cu（tbip）] layers which are further pillared by 1,3,5-tib ancillary ligand with terminal tridentate coordination mode to generate the final 3D structure. Magnetic susceptibility data for 1 have been measured in the range of 2~300 K. There are antiferromagnetic interactions between copper ions of the compound.
基金This research was supported by FUNDUNESP(process 01258/2008 and 00601/2011-DFP)CNPq(processes 305224/2004-2 and 307271/2007-2).
文摘The pit morphology and growth kinetics of commercially pure aluminium in naturally aerated NaCl solutions were studied using an image processing method based on reflected light microscopy. In order to distinguish between pits and pre-existing cavities, metallographic examination and statistical analysis were carried out before and after corrosion testing. The results show that the pit shapes and sizes are more dependent on the immersion time than the chloride concentration. Pits are predominantly hemispherical, but they undergo reasonable geometric transitions associated with increased immersion time and occur without significant depth variation. The role of chloride ions is more closely associated with the pit nucleation phenomenon.
文摘We report in this paper the ground-state energy 2s^(2)^(1)S and total energies of doubly excited states 2p^(2)^(1)D,3d^(2)^(1)D,4f^(2)^(1)I of the Helium isoelectronic sequence from H-to Ca^(18+).Calculations are performed using the Modified Atomic Orbital Theory(MAOT)in the framework of a variational procedure.The purpose of this study required a mathematical development of the Hamiltonian applied to Slater-type wave function[1]combining with Hylleraas-type wave function[2].The study leads to analytical expressions which are carried out under special MAXIMA computational program.This first proposed MAOT variational procedure,leads to accurate results in good agreement as well as with available other theoretical results than experimental data.In the present work,a new correlated wave function is presented to express analytically the total energies for the 2s21S ground state and each doubly 2p^(2)^(1)D,3d^(2)^(1)D,4f^(2)^(1)I excited states in the He-like systems.The present accurate data may be a useful guideline for future experimental and theoretical studies in the(nI^(2))systems.
基金supported by the National Natural Science Foundation of China (20571035)the Ministry of Education,Singapore through NUS (FRC Grant No. R143-000-371-112)
文摘The compound [Cu2（bpy）2（PDIAla）（H2O）2]（ClO4）2·H2O（H2PDIAla = N,N＇-（p-xylylene）dialanine,bipy = 2,2＇-bipyridine） 1 has been synthesized and structurally determined by single-crystal X-ray diffraction,elemental analyses and IR spectroscopy.The crystal belongs to the monoclinic system,space group P21 with a = 10.9772（6）,b = 18.5464（9）,c = 11.0790（6） ,β = 116.3110o,V = 2021.87（18） 3,Z = 2,Dc = 1.594 Mg/m3,Mr = 970.70,μ = 1.260 mm-1,F（000） = 996,λ（MoKα） = 0.71073 ,the final R = 0.0400 and wR = 0.1050 for all observed reflections.In the structure,the O（5）-H（52）…O（4） hydrogen bonding between aqua ligand and carbonyl oxygen of the H2PDIAla ligand along the c axis produce hydrogen-bonded helices which are assembled along the b axis through O（61）-H（61）…O（2） and N（6）-H（6N）…O（2） interactions to form 2-D layers that are further linked by π···π interactions between bpy ligands to yield a three-dimensional supramolecular network.
文摘According to the related theory about gas discharge, the numerical model of a gas discharge tube is established. With the help of particle simulation method, the curve of relationship between gas ignition voltage, gas pressure and electrode distance product is studied through computer simulation on physical process of producing plasma by DC neon discharge, and a complete consistence between the simulation result and the experimental curve is realized.
文摘This study was carried out to investigate the interaction of oxalic acid with hydrochloric acid to attain the better performance for iron dissolution in comparison to absence of oxalic acid. The effects of oxalic acid on ratio of hydrochloric acid, acid concentration, ratio of liquid to solid, temperature and dissolution time are investigated for the dissolution of Fe and Ti from ilmenite to produce synthetic rutile. The DX7 software basing on an experimental design method with the central composite of response surface design is applied to specify the effects of the parameters and to optimize the leaching process. The optimum condition was determined by analysis of variance (ANOVA), indicating that the ratio of oxalic acid to hydrochloric acid for Fe dissolution and acid concentration for Ti dissolution were the most effective parameters. The results showed that the dissolution of Fe and Ti in 30% (w/w) hydrochloric acid solution was only 48.65% and 5.14%, respectively, while at the same condition and in the presence of oxalic acid with twice the ratio, these values are increased to 78.65% and 12.06%, respectively. The optimum values of parameters were as follows: oxalic acid to hydrochloric acid ratio (2:1), acid concentration (30%), ratio of liquid to solid (10), temperature (160 °C), and dissolution time (3 h). By applying the optimized parameters, Fe and Ti dissolution of 97.15% and 2.8% were predicted by the software with a desirability of 0.745. The results of leaching tests indicated that the Fe and Ti dissolution of 97.58% and 2.43%, were achieved, respectively, which are very close to the predicted value.
文摘Background: Accumulating reactive oxygen species (ROS) is involved in cellular signaling and function disturbances due to the oxidative stress, which contributes to several diseases. The consequences of ROS activity represent an im-portant mechanism on the pathogenesis of vascular diseases, such as hypertension. Increased blood pressure observed in renal hypertension of the 2 kidneys-1 clip (2K-1C) model involves increased ROS levels in the cardiovascular system. Resveratrol, a polyphenolic compound primarily found in red wine, has many biological and pharmacological proper-ties. Considering the antioxidant properties of resveratrol, the present study was aimed to investigate the effects of the chronic treatment with resveratrol on cardiovascular system from renal hypertensive rats. Results: 2K-1C hypertension presented increased blood pressure, which was reduced at the end of the fifth week of resveratrol treatment. The cardiac hypertrophy index and the basal levels of ROS in rat aortic rings were also reduced by resveratrol treatment. Conclusions: The present findings clearly show the protective effects from resveratrol on the blood pressure, the car-diac growth and the vascular ROS generation in renal hypertension.
基金supported by the Ministry of Science and ICT in Korea(2021R1A2C2009459)X-ray absorption spectra were obtained from Pohang Accelerator Laboratory(PAL)10C beamlinesupported by the US Department of Energy,Office of Science,Office of Advanced Scientific Computing Research,and Scientific Discovery through Advanced Computing(SciDAC)program under Award Number DE-SC0022209.
文摘Systematic optimization of the photocatalyst and investigation of the role of each component is important to maximizing catalytic activity and comprehending the photocatalytic conversion of CO_(2) reduction to solar fuels.A surface-modified Ag@Ru-P25 photocatalyst with H_(2)O_(2) treatment was designed in this study to convert CO_(2) and H_(2)O vapor into highly selective CH4.Ru doping followed by Ag nanoparticles(NPs)cocatalyst deposition on P25(TiO_(2))enhances visible light absorption and charge separation,whereas H_(2)O_(2) treatment modifies the surface of the photocatalyst with hydroxyl(–OH)groups and promotes CO_(2) adsorption.High-resonance transmission electron microscopy,X-ray photoelectron spectroscopy,X-ray absorption near-edge structure,and extended X-ray absorption fine structure techniques were used to analyze the surface and chemical composition of the photocatalyst,while thermogravimetric analysis,CO_(2) adsorption isotherm,and temperature programmed desorption study were performed to examine the significance of H_(2)O_(2) treatment in increasing CO_(2) reduction activity.The optimized Ag1.0@Ru1.0-P25 photocatalyst performed excellent CO_(2) reduction activity into CO,CH4,and C2H6 with a~95%selectivity of CH4,where the activity was~135 times higher than that of pristine TiO_(2)(P25).For the first time,this work explored the effect of H_(2)O_(2) treatment on the photocatalyst that dramatically increases CO_(2) reduction activity.
基金Supported by the Basic Research Program of Nanjing University of Posts and Telecommunications under Grant No NY212002the Innovative Research Team in University under Grant No IRT1148the 2014 Shuangchuang Program of Jiangsu Province
文摘We fabricate flexible conductive and transparent graphene films on position-emission-tomography substrates and prepare large area graphene films by graphite oxide sheets with the new technical process. The multi-layer graphene oxide sheets can be chemically reduced by HNO3 and HI to form a highly conductive graphene film on a substrate at lower temperature. The reduced graphene oxide sheets show a high conductivity sheet with resistance of 476Ω/sq and transmittance of 76% at 550nm （6 layers）. The technique used to produce the transparent conductive graphene thin film is facile, inexpensive, and can be tunable for a large area production applied for electronics or touch screens.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50677034)the State Key Laboratory of Control and Simulation of Power System and Generation Equipment, China (Grant No. SKLD11M04)the State Key Laboratory of Electrical Insulation and Power Equipment, China (Grant No. EIPE12201)
文摘A small electrical explosion of wire （EEW） setup for nanopowder production is constructed. It consists of a low inductance capacitor bank of 2 μF–4 μF typically charged to 8 kV–30 kV, a triggered gas switch, and a production chamber housing the exploding wire load and ambient gas. With the EEW device, nanosize powders of titanium oxides, titanium nitrides, copper oxides, and zinc oxides are successfully synthesized. The average particle size of synthesized powders under different experimental conditions is in a range of 20nm–80nm. The pressure of ambient gas or wire vapor can strongly affect the average particle size. The lower the pressure, the smaller the particle size is. For wire material with relatively high resistivity, such as titanium, whose deposited energy Wd is often less than sublimation energy W s due to the flashover breakdown along the wire prematurely ending the Joule heating process, the synthesized particle size of titanium oxides or titanium nitrides increases with overheat coefficient k （k = W d /Ws ） increasing.
基金Supported by the National Basic Research Program of China(2009CB724706)
文摘A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-PDMAEMA-grafted-Fe3O4 magnetic nanoparticles with amino and epoxy groups were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermo-gravimetric analysis, and scanning electron microscopy. Lipase from Burkholderia cepacia was successfully immobilized onto the magnetic nanoparticles by physical adsorption and covalent bonding. The immobilization capacity of the magnetic particles is 0.5 mg lipase per mg support, with an activity recovery of up to 43.1% under the optimum immobilization condition. Biochemical characterization shows that the immobilized lipase exhibits improved thermal stability, good tolerance to organic solvents with high lg P, and higher p H stability than the free lipase at p H 9.0. After six consecutive cycles, the residual activity of the immobilized lipase is still over55% of its initial activity.
基金NNSFC (Nos. 10234070 and 10104011) NSF of Fujian Province (No. E0110003) and State Key Laboratory of Structural Chemistry (020058)
文摘The interactions between four high bioactive diperoxovanadate complexes Kn[OV(O2)2L]mH2O (n = 1~3, m = 1~5, L = oxalate (abbr. oxa), picolinate (abbr. pic), bipyridine (abbr. bipy) and 1,10-phenanthroline (abbr. phen); their corresponding complexes abbreviated as bpV(oxa), bpV(pic), bpV(bipy) and bpV(phen), respectively) and imidazole (abbr. imi) in solution were studied by several NMR techniques: multinuclear (1H, 13C and 51V) and variable temperature 51V NMR. Competitive coordination interactions were observed and the order of the interaction strength of the four complexes with imidazole is as follows: bpV(oxa) > bpV(pic) > bpV(bipy) > bpV(phen), which is deeply affected by the identity of the ligands and has the same order as their inhibition effect toward bovine heart phosphotyrosyl protein phosphatase. The species [OV- (O2)2(imi)]- was formed in all cases. Both of the NMR data and equilibrium constants of the interaction systems were reported. The experimental results indicate that the species of bpV(oxa) and [OV(O2)2(imi)]- are six-coordinated, while bpV(pic), bpV(bipy) and bpV(phen) are seven- coordinated in solution. ESI-MS results support the conclusions obtained by NMR.
文摘The use of carbon‐based materials is an appealing strategy to solve the issue of excessive CO_(2) emis‐sions.In particular,metal‐free nitrogen‐doped carbon materials(mf‐NCs)have the advantages of convenient synthesis,cost‐effectiveness,and high conductivity and are ideal electrocatalysts for the CO_(2) reduction reaction(CO_(2)RR).However,the unclear identification of the active N sites and the low intrinsic activity of mf‐NCs hinder the further development of high‐performance CO_(2)RR electrocat‐alysts.Achieving precise control over the synthesis of mf‐NC catalysts with well‐defined active N‐species sites is still challenging.To this end,we adopted a facile synthesis method to construct a set of mf‐NCs as robust catalysts for CO_(2)RR.The resulting best‐performing catalyst obtained a Far‐adaic efficiency of CO of approximately 90%at−0.55 V(vs.reversible hydrogen electrode)and good stability.The electrocatalytic performance and in situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy measurements collectively revealed that graphitic and pyridinic N can synergistically adsorb CO_(2) and H_(2)O and thus promote CO_(2) activation and protonation.
基金supported by National Natural Science Foundation of China (21705036, 21975067, 11974105, and 11634001)National Basic Research Programs of China (2016YFA0300901)+3 种基金Natural Science Foundation of Hunan Province, China (2018JJ3035)Fundamental Research Funds for the Central Universities from Hunan Universityfinancially supported by the fund of Prof. Hong from University of Macao (SRG201600092-IAPME, MYRG2018-00079-IAPME, MYRG2019-00115-IAPME)the Science and Technology Development Fund, Macao SAR (FDCT081/2017/A2, FDCT0059/2018/A2, FDCT009/2017/AMJ)
文摘The catalytic performance of Molybdenum disulfide(MoS_(2)) has been still far from that of Pt-based catalysts for inadequate active sites and sluggish electron transfer kinetics. Through engineering the interface between MoS_(2)-based materials and supported substrates, hybrid Ru-doped MoS_(2) on carbonized lignin(CL) is designed and prepared as efficient catalyst for hydrogen evolution reaction(HER). The CL substrate not only facilitates the growth of MoS_(2) nanoflowers, but also promotes the electron transfer. Ru doping increases active sites greatly for HER. The hybrid catalyst achieves a low onset overpotential of 25 mV and a low Tafel slope of 46 m V dec^(-1). The favorable HER activity ascribes to the interfacial interaction between MoS_(2) and CL. Density functional theory calculations further confirm the improved HER performance with doped Ru atoms. This study presents a prototype application to design electrocatalysts with enhanced carrier mobility and high-density active sites based on interface effect.
