BACKGROUND^(68)Ga(gallium)-PSMA PET-CT(prostate-specific membrane antigen-directed Positron emission tomography-computed tomography)has established its role in prostate cancer management as targeted molecular imaging....BACKGROUND^(68)Ga(gallium)-PSMA PET-CT(prostate-specific membrane antigen-directed Positron emission tomography-computed tomography)has established its role in prostate cancer management as targeted molecular imaging.However,limited studies are available on the diagnostic accuracy of^(99m)Tc(Technetium)-PSMASPECT/CT.Due to its cost effectiveness and better feasibility,it needs to be explored more extensively for its incorporation into routine clinical practice.AIM To analyse the diagnostic accuracy of^(99m)Tc-PSMA-SPECT/CT for detection of primary prostate carcinoma.METHODS As a prospective study in a tertiary hospital,^(99m)Tc-PSMA-SPECT/CT was performed in 29 outpatients with suspected prostate cancer,with a median age of 66(range:50-82)years.The findings were compared to histopathology as the gold standard.RESULTS Nineteen of twenty-nine patients were positive on^(99m)Tc-PSMA-SPECT/CT,of which 16(84.2%)had prostate cancer on histopathology,while the remaining ten were negative on imaging,of which three had prostate cancer,leading to an overall sensitivity,specificity,and accuracy of 84.2%,70%,and 79.3%,respectively,on visual analysis.Prostate:background and prostate:liver ratios were 37.18±48.85 and 5.35±7.35 in the malignant group,while 6.65±5.17 and 1.14±0.56 in the benign group,respectively.The area under the curve values for prostate:background and prostate:liver ratios were 0.833(95%confidence interval[CI]:0.677-0.990,P=0.005)and 0.767(95%CI:0.596-0.937,P=0.024),respectively,on receiver operator curve analysis.A cut-off value>10.45 for prostate:background ratio(sensitivity 85%and specificity 88.9%),and>1.15 for prostate:liver ratio(sensitivity 75%and specificity of 77.8%respectively)was found to be pertinent to differentiate between the malignant vs benign groups.CONCLUSION^(99m)Tc-PSMA-SPECT/CT shows a promising role in the diagnosis of primary prostate cancer.展开更多
The mechanical properties and microstructural evolution of zircaloy-4 subjected to cumulative strains of 1.48,2.96,4.44 and 5.91 through multiaxial forging（MAF） at cryogenic temperature（77 K） were investigated.The...The mechanical properties and microstructural evolution of zircaloy-4 subjected to cumulative strains of 1.48,2.96,4.44 and 5.91 through multiaxial forging（MAF） at cryogenic temperature（77 K） were investigated.The mechanical properties of the MAF treated alloy were measured through universal tensile testing and Vickers hardness testing equipment.The zircaloy-4 deformed up to a cumulative strain of 5.91 showed improvement in both ultimate tensile strength and hardness from 474 MPa to 717 MPa and from HV 190 to HV 238,respectively,as compared with the as-received alloy.However,there was a noticeable decrement in ductility（from 18%to 3.5%） due to the low strain hardening ability of deformed zircaloy-4.The improvement in strength and hardness of the deformed alloy is attributed to the grain size effect and higher dislocation density generated during multiaxial forging.The microstructural evolutions of deformed samples were characterized by optical microscopy and transmission electron microscopy（TEM）.The evolved microstructure at a cumulative strain of 5.91 obtained after MAF up to 12 cycles depicted the formation of ultrafine grains with an average size of 150-250 nm.展开更多
Dominant phase during hot deformation in the two-phase region of Zr-2.5Nb-0.5Cu （ZNC） alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on...Dominant phase during hot deformation in the two-phase region of Zr-2.5Nb-0.5Cu （ZNC） alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on a two-phase ZNC alloy in the temperature range of 700-925 ℃ and strain rate range of 10-2-10 s-l, Flow stress data of the single phase were extrapolated in the two-phase range to calculate flow stress data of individual phases. Activation energies of individual phases were then calculated using calculated flow stress data in the two-phase range, Comparison of activation energies revealed that a phase is the dominant phase （deformation controlling phase） in the two-phase range. Constitutive equations were also developed on the basis of the deformation temperature range （or according to phases present） using a sine-hyperbolic type constitutive equation. The statistical analysis revealed that the constitutive equation developed for a particular phase showed good agreement with the experimental results in terms of correlation coefficient （R） and average absolute relative error （AARE）.展开更多
The present study explores an electroreduced graphene oxide-bismuth nanoparticles composite（ErGOBi） as an electrochemical sensor for the determination of an anticancer drug, gemcitabine hydrochloride（GMB）. The Er-...The present study explores an electroreduced graphene oxide-bismuth nanoparticles composite（ErGOBi） as an electrochemical sensor for the determination of an anticancer drug, gemcitabine hydrochloride（GMB）. The Er-GOBi interface was prepared by drop casting of bismuth nitrate-graphene oxide suspension on a glassy carbon electrode（GCE） followed by electro-reduction in the potential range of 0.6 V to 1.7 V. SEM, FTIR, EDAX and AFM techniques were employed for the characterization of prepared materials. Cyclic voltammetric and electrochemical impedance spectroscopic methods were used to understand the charge transfer properties of stepwise modification of Er-GOBi/GCE. GMB exhibited an irreversible oxidation peak at 1.144 V on Er-GOBi/GCE in phosphate buffer of p H 3. A 100-fold enhanced oxidation peak current was observed at Er-GOBi/GCE when compared to that at bare GCE.Sensing performance of Er GO-Bi/GCE was optimized by varying peak current dependent parameters.Linear relationship between the peak current and concentration of GMB was observed in the range of 0.1–51.1 mmol/L in differential pulse voltammetric method and 2.1–61.1 mmol/L in linear sweep voltammetric method. The practical utility of the proposed sensor, Er-GOBi/GCE was demonstrated by determining GMB in pharmaceutical formulations and spiked urine samples.展开更多
The texture and mechanical properties of cross-rolled zircaloy-2 at 77 and 300 K were investigated.Crossrolling at 77 K was performed to impart different thickness reductions of 25% and 50%,while at 300 K with 25%,50%...The texture and mechanical properties of cross-rolled zircaloy-2 at 77 and 300 K were investigated.Crossrolling at 77 K was performed to impart different thickness reductions of 25% and 50%,while at 300 K with 25%,50%,75% and 85% reductions to the sample.EBSD analysis of deformed sample showed that near-basal orientation is not deformed completely after 50% rolling reduction.The activation of prismatic silp,{1122} contraction twin and {1012} extension twin were evident from the deformed microstructure at 77 K.The propensity for activation of basal slip〈a〉 at77 K was also observed.The deformation of the sample at 300 K occurs by prismatic,basal 〈a〉 and pyramidal 〈c＋a〉slips,which were predicted by pole figures.After annealing,the tensile strengths（735 and 710 MPa） are almost the same for 50% cryo-cross-rolled and room-temperature cross-rolled zircaloy-2 with almost 2.7% difference in their ductility.KAM analysis of the deformed samples was made to estimate the stored strain energy and dislocation density.Annealing of deformed sample at 673 K for 30 min results in recrystallization,which leads to the formation of ultrafine grains.展开更多
The oxidation of aluminium was studied using optical emission spectroscopy （OES） during the evaporation of aluminium in traces of oxygen in a thermal plasma reactor. The ratio of the measured line intensities of Al-...The oxidation of aluminium was studied using optical emission spectroscopy （OES） during the evaporation of aluminium in traces of oxygen in a thermal plasma reactor. The ratio of the measured line intensities of Al-O with that of Al follows the exact trend as of that obtained from the corresponding line intensities in X-ray diffraction spectra of the synthesized samples. In this paper the inherent capacity of emission spectroscopy in evaluating the growth processes under plasma induced reactions is presented.展开更多
^222Rn and ^220Rn enter the atmosphere mainly by crossing the air interface of either soil-air or building materials. The existence of relatively high concentration maintains a large ^222Rn, ^220Rn concentration gradi...^222Rn and ^220Rn enter the atmosphere mainly by crossing the air interface of either soil-air or building materials. The existence of relatively high concentration maintains a large ^222Rn, ^220Rn concentration gradient between the materials and open air. The present paper deals with the experimental measurement of ^222Rn, ^220Rn concentrations and the associated inhalation dose rates due to them in the dwellings of different characteristics. Higher concentrations and dose rates were observed in lower volume houses and the houses with granite flooring.展开更多
Comparative investigations of gas sensing characteristics of Fe2O3 in both thin film as well as bulk forms have been performed. Thin film sensors were realized by first depositing Fe films using electron-beam evaporat...Comparative investigations of gas sensing characteristics of Fe2O3 in both thin film as well as bulk forms have been performed. Thin film sensors were realized by first depositing Fe films using electron-beam evaporation followed by thermal oxidation. Bulk sensors in the form of pellets were prepared by cold pressing commercial Fe2O3 powder with subsequent sintering. Both thin film and bulk Fe2O3 sensors exhibited a selective and reversible response characteristics towards H2S with maximum response at an operating temperature of 250°C and 200°C, respectively. A negligible response towards other interfering gases was observed. Thin film sensors exhibited an enhanced response in comparison to that of pellets.展开更多
New tungsten ion source is produced by using single and double-pulse laser ablation system. Combined collinear Nd：YAG laser beams（266＋1064 nm） are optimized to focus on the sample in air. Optimization of the exper...New tungsten ion source is produced by using single and double-pulse laser ablation system. Combined collinear Nd：YAG laser beams（266＋1064 nm） are optimized to focus on the sample in air. Optimization of the experimental parameters is achieved to enhance the signal-to-noise ratio of the emission spectra. The velocity distribution of the emitted plasma cloud is carefully measured. The influences of the potential difference between the bias electrodes, laser wavelength and intensity on the current signal are also studied. The results show that the increase in the tungsten ion velocity under the double-pulse lasers causes the output current signal to increase by about three folds. The electron density and temperature are calculated by using the Stark-broadened line profile of tungsten line and Boltzmann plot method of the upper energy levels, respectively. The signal intensity dependence of the tungsten ion angular distribution is also analyzed. The results indicate that the double-pulse laser ablation configuration is more potent technique for producing more metal ion source deposition, thin film formation, and activated plasma-facing component material.展开更多
Six phenolic compounds namely,quercetin-3-O-rutinoside(1),3-O-caffeoylquinic acid(2),luteolin-7-O-glucoside(3),apigenin-7-O-rutinoside(4),apigenin-7-O-b-D-glucopyranoside(5)and quercetin(6)were isolated from the whole...Six phenolic compounds namely,quercetin-3-O-rutinoside(1),3-O-caffeoylquinic acid(2),luteolin-7-O-glucoside(3),apigenin-7-O-rutinoside(4),apigenin-7-O-b-D-glucopyranoside(5)and quercetin(6)were isolated from the whole plant of Pilea microphylla using conventional opensilica gel column chromatography and preparative HPLC.Further,these compounds were characterized by 1D,2D NMR techniques and high-resolution LC–MS.Compounds 1–3 and 6 exhibited significant antioxidant potential in scavenging free radicals such as DPPH,ABTS and SOD with IC_(50) of 3.3–20.4 mmol/L.The same compounds also prevented lipid peroxidation with IC_(50) of 10.4–32.2 mmol/L.The compounds also significantly prevented the Fenton reagent-induced calf thymus DNA damage.Pre-treatment with compounds 1–3 and 6 in V79 cells attenuated radiation-induced formation of reactive oxygen species,lipid peroxidation,cytotoxicity and DNA damage,correlating the antioxidant activity of polyphenols with their radioprotective effects.Compounds 1,3 and 6 significantly inhibited lipid peroxidation,presumably due to 30,40-catechol ortho-dihydroxy moiety in the B-ring,which has a strong affinity for phospholipid membranes.Oxidation of flavonoids,with catechol structure on B-ring,yields a fairly stable ortho-semiquinone radical by facilitating electron delocalization,which is involved in antioxidant mechanism.Hence,the flavonoid structure,number and location of hydroxyl groups together determine the antioxidant and radioprotection mechanism.展开更多
Background:Rhizoma Dioscoreae bulbiferae could cause liver damage,which limited its application in the clinic.Aims and Objectives:To explore the mechanism of hepatotoxicity of Rhizoma Dioscoreae bulbiferae in mice.Mat...Background:Rhizoma Dioscoreae bulbiferae could cause liver damage,which limited its application in the clinic.Aims and Objectives:To explore the mechanism of hepatotoxicity of Rhizoma Dioscoreae bulbiferae in mice.Materials and Methods:In the present study,the water extraction of Rhizoma Dioscoreae bulbiferae(W.E.R)was administrated via intragastrical with Low(19.6 g/kg),Middle(28.0 g/kg),and High(40.0 g/kg)dose in mice.At each time point 14 days,21 days,and 28 days,the body weight,liver coefficient,indexes of liver function alkaline phosphatase(ALP),alanine aminotransferase(ALT)and aspartate transaminase(AST),various biochemical biomarkers of liver tissue and mitochondria were detected and analyzed.Results:We found that W.E.R could decrease the body weight,increase the liver coefficient and the expression levels of indexes of liver function in mice.Next,we investigated that W.E.R could increase the expression levels of reactive oxygen species(ROS)and malondialdehyde(MDA),decrease the expression levels of adenosine triphosphate(ATP)and improve the enzyme activities of total superoxide dismutase(SOD).Third,we found that W.E.R could increase the enzyme activities of manganese-superoxide dismutase,decrease the enzyme activities of sodium-potassium adenosine triphosphatase(Na+-K+-ATPase)and calcium-magnesium adenosine triphosphatase(Ca 2+-Mg 2+-ATPase).Finally,we analyzed that there were significant negative correlations between body weight,expression level of ATP,activity of Na+-K+-ATPase,activity of Ca 2+-Mg 2+-ATPase and time,dose.There were significant positive correlations between liver coefficient,ALP,ALT,AST,expression levels of ROS,MDA and time,dose.Conclusion:All the results above indicated that W.E.R could cause the hepatotoxicity based on the oxidative damage in mice,which and mitochondria might be the main targets.展开更多
Unicellular cyanobacteria Synechocystis 6803 were fixed using high-pressure freezing （HPF） and freeze substitution without any chemical cross-linkers. Immunoelectron microscopy of these cells showed that five sequen...Unicellular cyanobacteria Synechocystis 6803 were fixed using high-pressure freezing （HPF） and freeze substitution without any chemical cross-linkers. Immunoelectron microscopy of these cells showed that five sequential enzymes of the Calvin cycle （phosphoriboisomerase, phosphoribulokinase, ribulose-1,5-bisphosphate carboxylase/oxygenase （RuBisCO）, 3-phosphoglyceratekinase and glyceraldehyde-3-phosphate dehydrogenase） and the catalytic portion of the chloroplast H^＋-ATP synthase （CF1） are located adjacent to the thylakoid membranes. Cell-free extracts of Synechocystis were processed by ultracentrifugation to isolate thylakoid fractions sedimenting at 40 000, 90 000, and 150 000 g. Among these, the 150 000-g fraction showed the highest linked activity of the above five sequential Calvin cycle enzymes and also the highest coordinated activity of light and dark reactions as assessed by ribose-5-phosphate （R-5-P） ＋ADP dependent CO2 fixation. Immunogold labeling of this membrane fraction confirmed the presence of the above five enzymes as well as the catalytic portion of the CF1 ATP synthase. Notably, the protein A-gold labeling of the thylakoids was observed without use of chemical cross-linkers and in spite of the normal washing steps used during standard immunolabeling. The results showed that soluble Calvin cycle enzymes might be organized along the thylakoid membranes.展开更多
The topological insulators Bi_(2-x)Fe_(x)Se_(3-x)S_(x) have been investigated by the dc-magnetization,magnetotransport and angle resolved photoemission spectroscopy(ARPES)techniques.With doping of Fe and S,a negative ...The topological insulators Bi_(2-x)Fe_(x)Se_(3-x)S_(x) have been investigated by the dc-magnetization,magnetotransport and angle resolved photoemission spectroscopy(ARPES)techniques.With doping of Fe and S,a negative giant magneto-resistance(MR)is observed for parallel electric and magnetic fields(H||E).The MR behavior at lower magnetic field can be explained with the semi-classical theory whereas the MR behavior at higher field has been attributed to the axial anomaly.Interestingly,the system reached to the quantum limit at low magnetic field(~4.5T).The magnetic ordering can be explained with the presence of both the RKKY(surface)and van-Vleck(bulk)interaction.The ARPES study reveals that a surface gap is suppressed when the magnetic ordering changes from ferromagnetic to anti-ferromagnetic ordering.The ARPES study and the appearance of quantum oscillations(SdH)in the resistivity pattern reveal that the topological surface property is preserved with the co-doping of Fe and S.展开更多
文摘BACKGROUND^(68)Ga(gallium)-PSMA PET-CT(prostate-specific membrane antigen-directed Positron emission tomography-computed tomography)has established its role in prostate cancer management as targeted molecular imaging.However,limited studies are available on the diagnostic accuracy of^(99m)Tc(Technetium)-PSMASPECT/CT.Due to its cost effectiveness and better feasibility,it needs to be explored more extensively for its incorporation into routine clinical practice.AIM To analyse the diagnostic accuracy of^(99m)Tc-PSMA-SPECT/CT for detection of primary prostate carcinoma.METHODS As a prospective study in a tertiary hospital,^(99m)Tc-PSMA-SPECT/CT was performed in 29 outpatients with suspected prostate cancer,with a median age of 66(range:50-82)years.The findings were compared to histopathology as the gold standard.RESULTS Nineteen of twenty-nine patients were positive on^(99m)Tc-PSMA-SPECT/CT,of which 16(84.2%)had prostate cancer on histopathology,while the remaining ten were negative on imaging,of which three had prostate cancer,leading to an overall sensitivity,specificity,and accuracy of 84.2%,70%,and 79.3%,respectively,on visual analysis.Prostate:background and prostate:liver ratios were 37.18±48.85 and 5.35±7.35 in the malignant group,while 6.65±5.17 and 1.14±0.56 in the benign group,respectively.The area under the curve values for prostate:background and prostate:liver ratios were 0.833(95%confidence interval[CI]:0.677-0.990,P=0.005)and 0.767(95%CI:0.596-0.937,P=0.024),respectively,on receiver operator curve analysis.A cut-off value>10.45 for prostate:background ratio(sensitivity 85%and specificity 88.9%),and>1.15 for prostate:liver ratio(sensitivity 75%and specificity of 77.8%respectively)was found to be pertinent to differentiate between the malignant vs benign groups.CONCLUSION^(99m)Tc-PSMA-SPECT/CT shows a promising role in the diagnosis of primary prostate cancer.
基金BRNS,Bombay for their financial grant to this work through grant No.BRN-577-MMD
文摘The mechanical properties and microstructural evolution of zircaloy-4 subjected to cumulative strains of 1.48,2.96,4.44 and 5.91 through multiaxial forging（MAF） at cryogenic temperature（77 K） were investigated.The mechanical properties of the MAF treated alloy were measured through universal tensile testing and Vickers hardness testing equipment.The zircaloy-4 deformed up to a cumulative strain of 5.91 showed improvement in both ultimate tensile strength and hardness from 474 MPa to 717 MPa and from HV 190 to HV 238,respectively,as compared with the as-received alloy.However,there was a noticeable decrement in ductility（from 18%to 3.5%） due to the low strain hardening ability of deformed zircaloy-4.The improvement in strength and hardness of the deformed alloy is attributed to the grain size effect and higher dislocation density generated during multiaxial forging.The microstructural evolutions of deformed samples were characterized by optical microscopy and transmission electron microscopy（TEM）.The evolved microstructure at a cumulative strain of 5.91 obtained after MAF up to 12 cycles depicted the formation of ultrafine grains with an average size of 150-250 nm.
基金financial support(Grant No.2011/36/15)from Board of Research in Nuclear Science(BRNS),India
文摘Dominant phase during hot deformation in the two-phase region of Zr-2.5Nb-0.5Cu （ZNC） alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on a two-phase ZNC alloy in the temperature range of 700-925 ℃ and strain rate range of 10-2-10 s-l, Flow stress data of the single phase were extrapolated in the two-phase range to calculate flow stress data of individual phases. Activation energies of individual phases were then calculated using calculated flow stress data in the two-phase range, Comparison of activation energies revealed that a phase is the dominant phase （deformation controlling phase） in the two-phase range. Constitutive equations were also developed on the basis of the deformation temperature range （or according to phases present） using a sine-hyperbolic type constitutive equation. The statistical analysis revealed that the constitutive equation developed for a particular phase showed good agreement with the experimental results in terms of correlation coefficient （R） and average absolute relative error （AARE）.
基金the University Grant Commission, New Delhi, for providing financial support to carry out this study
文摘The present study explores an electroreduced graphene oxide-bismuth nanoparticles composite（ErGOBi） as an electrochemical sensor for the determination of an anticancer drug, gemcitabine hydrochloride（GMB）. The Er-GOBi interface was prepared by drop casting of bismuth nitrate-graphene oxide suspension on a glassy carbon electrode（GCE） followed by electro-reduction in the potential range of 0.6 V to 1.7 V. SEM, FTIR, EDAX and AFM techniques were employed for the characterization of prepared materials. Cyclic voltammetric and electrochemical impedance spectroscopic methods were used to understand the charge transfer properties of stepwise modification of Er-GOBi/GCE. GMB exhibited an irreversible oxidation peak at 1.144 V on Er-GOBi/GCE in phosphate buffer of p H 3. A 100-fold enhanced oxidation peak current was observed at Er-GOBi/GCE when compared to that at bare GCE.Sensing performance of Er GO-Bi/GCE was optimized by varying peak current dependent parameters.Linear relationship between the peak current and concentration of GMB was observed in the range of 0.1–51.1 mmol/L in differential pulse voltammetric method and 2.1–61.1 mmol/L in linear sweep voltammetric method. The practical utility of the proposed sensor, Er-GOBi/GCE was demonstrated by determining GMB in pharmaceutical formulations and spiked urine samples.
基金BRNS,Bombay for their financial grant to this work (No.BRN-577-MMD)
文摘The texture and mechanical properties of cross-rolled zircaloy-2 at 77 and 300 K were investigated.Crossrolling at 77 K was performed to impart different thickness reductions of 25% and 50%,while at 300 K with 25%,50%,75% and 85% reductions to the sample.EBSD analysis of deformed sample showed that near-basal orientation is not deformed completely after 50% rolling reduction.The activation of prismatic silp,{1122} contraction twin and {1012} extension twin were evident from the deformed microstructure at 77 K.The propensity for activation of basal slip〈a〉 at77 K was also observed.The deformation of the sample at 300 K occurs by prismatic,basal 〈a〉 and pyramidal 〈c＋a〉slips,which were predicted by pole figures.After annealing,the tensile strengths（735 and 710 MPa） are almost the same for 50% cryo-cross-rolled and room-temperature cross-rolled zircaloy-2 with almost 2.7% difference in their ductility.KAM analysis of the deformed samples was made to estimate the stored strain energy and dislocation density.Annealing of deformed sample at 673 K for 30 min results in recrystallization,which leads to the formation of ultrafine grains.
基金support rendered by BRNS (DAE, India) for the project
文摘The oxidation of aluminium was studied using optical emission spectroscopy （OES） during the evaporation of aluminium in traces of oxygen in a thermal plasma reactor. The ratio of the measured line intensities of Al-O with that of Al follows the exact trend as of that obtained from the corresponding line intensities in X-ray diffraction spectra of the synthesized samples. In this paper the inherent capacity of emission spectroscopy in evaluating the growth processes under plasma induced reactions is presented.
文摘^222Rn and ^220Rn enter the atmosphere mainly by crossing the air interface of either soil-air or building materials. The existence of relatively high concentration maintains a large ^222Rn, ^220Rn concentration gradient between the materials and open air. The present paper deals with the experimental measurement of ^222Rn, ^220Rn concentrations and the associated inhalation dose rates due to them in the dwellings of different characteristics. Higher concentrations and dose rates were observed in lower volume houses and the houses with granite flooring.
文摘Comparative investigations of gas sensing characteristics of Fe2O3 in both thin film as well as bulk forms have been performed. Thin film sensors were realized by first depositing Fe films using electron-beam evaporation followed by thermal oxidation. Bulk sensors in the form of pellets were prepared by cold pressing commercial Fe2O3 powder with subsequent sintering. Both thin film and bulk Fe2O3 sensors exhibited a selective and reversible response characteristics towards H2S with maximum response at an operating temperature of 250°C and 200°C, respectively. A negligible response towards other interfering gases was observed. Thin film sensors exhibited an enhanced response in comparison to that of pellets.
文摘New tungsten ion source is produced by using single and double-pulse laser ablation system. Combined collinear Nd：YAG laser beams（266＋1064 nm） are optimized to focus on the sample in air. Optimization of the experimental parameters is achieved to enhance the signal-to-noise ratio of the emission spectra. The velocity distribution of the emitted plasma cloud is carefully measured. The influences of the potential difference between the bias electrodes, laser wavelength and intensity on the current signal are also studied. The results show that the increase in the tungsten ion velocity under the double-pulse lasers causes the output current signal to increase by about three folds. The electron density and temperature are calculated by using the Stark-broadened line profile of tungsten line and Boltzmann plot method of the upper energy levels, respectively. The signal intensity dependence of the tungsten ion angular distribution is also analyzed. The results indicate that the double-pulse laser ablation configuration is more potent technique for producing more metal ion source deposition, thin film formation, and activated plasma-facing component material.
基金supported by a Grant Vide No.2007/37/53/BRNS from the Board of Research and Nuclear Sciences,Department of Atomic Energy,Government of India.
文摘Six phenolic compounds namely,quercetin-3-O-rutinoside(1),3-O-caffeoylquinic acid(2),luteolin-7-O-glucoside(3),apigenin-7-O-rutinoside(4),apigenin-7-O-b-D-glucopyranoside(5)and quercetin(6)were isolated from the whole plant of Pilea microphylla using conventional opensilica gel column chromatography and preparative HPLC.Further,these compounds were characterized by 1D,2D NMR techniques and high-resolution LC–MS.Compounds 1–3 and 6 exhibited significant antioxidant potential in scavenging free radicals such as DPPH,ABTS and SOD with IC_(50) of 3.3–20.4 mmol/L.The same compounds also prevented lipid peroxidation with IC_(50) of 10.4–32.2 mmol/L.The compounds also significantly prevented the Fenton reagent-induced calf thymus DNA damage.Pre-treatment with compounds 1–3 and 6 in V79 cells attenuated radiation-induced formation of reactive oxygen species,lipid peroxidation,cytotoxicity and DNA damage,correlating the antioxidant activity of polyphenols with their radioprotective effects.Compounds 1,3 and 6 significantly inhibited lipid peroxidation,presumably due to 30,40-catechol ortho-dihydroxy moiety in the B-ring,which has a strong affinity for phospholipid membranes.Oxidation of flavonoids,with catechol structure on B-ring,yields a fairly stable ortho-semiquinone radical by facilitating electron delocalization,which is involved in antioxidant mechanism.Hence,the flavonoid structure,number and location of hydroxyl groups together determine the antioxidant and radioprotection mechanism.
基金supported by The National Key Research and Development Plan 2019YFC1712403Major New Drug Discovery Science and Technology Major Projects 2017ZX09201002-006the Research Project of Capital Health and Development 2018-4-4231
文摘Background:Rhizoma Dioscoreae bulbiferae could cause liver damage,which limited its application in the clinic.Aims and Objectives:To explore the mechanism of hepatotoxicity of Rhizoma Dioscoreae bulbiferae in mice.Materials and Methods:In the present study,the water extraction of Rhizoma Dioscoreae bulbiferae(W.E.R)was administrated via intragastrical with Low(19.6 g/kg),Middle(28.0 g/kg),and High(40.0 g/kg)dose in mice.At each time point 14 days,21 days,and 28 days,the body weight,liver coefficient,indexes of liver function alkaline phosphatase(ALP),alanine aminotransferase(ALT)and aspartate transaminase(AST),various biochemical biomarkers of liver tissue and mitochondria were detected and analyzed.Results:We found that W.E.R could decrease the body weight,increase the liver coefficient and the expression levels of indexes of liver function in mice.Next,we investigated that W.E.R could increase the expression levels of reactive oxygen species(ROS)and malondialdehyde(MDA),decrease the expression levels of adenosine triphosphate(ATP)and improve the enzyme activities of total superoxide dismutase(SOD).Third,we found that W.E.R could increase the enzyme activities of manganese-superoxide dismutase,decrease the enzyme activities of sodium-potassium adenosine triphosphatase(Na+-K+-ATPase)and calcium-magnesium adenosine triphosphatase(Ca 2+-Mg 2+-ATPase).Finally,we analyzed that there were significant negative correlations between body weight,expression level of ATP,activity of Na+-K+-ATPase,activity of Ca 2+-Mg 2+-ATPase and time,dose.There were significant positive correlations between liver coefficient,ALP,ALT,AST,expression levels of ROS,MDA and time,dose.Conclusion:All the results above indicated that W.E.R could cause the hepatotoxicity based on the oxidative damage in mice,which and mitochondria might be the main targets.
文摘Unicellular cyanobacteria Synechocystis 6803 were fixed using high-pressure freezing （HPF） and freeze substitution without any chemical cross-linkers. Immunoelectron microscopy of these cells showed that five sequential enzymes of the Calvin cycle （phosphoriboisomerase, phosphoribulokinase, ribulose-1,5-bisphosphate carboxylase/oxygenase （RuBisCO）, 3-phosphoglyceratekinase and glyceraldehyde-3-phosphate dehydrogenase） and the catalytic portion of the chloroplast H^＋-ATP synthase （CF1） are located adjacent to the thylakoid membranes. Cell-free extracts of Synechocystis were processed by ultracentrifugation to isolate thylakoid fractions sedimenting at 40 000, 90 000, and 150 000 g. Among these, the 150 000-g fraction showed the highest linked activity of the above five sequential Calvin cycle enzymes and also the highest coordinated activity of light and dark reactions as assessed by ribose-5-phosphate （R-5-P） ＋ADP dependent CO2 fixation. Immunogold labeling of this membrane fraction confirmed the presence of the above five enzymes as well as the catalytic portion of the CF1 ATP synthase. Notably, the protein A-gold labeling of the thylakoids was observed without use of chemical cross-linkers and in spite of the normal washing steps used during standard immunolabeling. The results showed that soluble Calvin cycle enzymes might be organized along the thylakoid membranes.
基金Authors are grateful to CIF,IIT(BHU)for providing magnetic measurement facility.The ARPES measurements were performed with the approval of the Proposal Assessing Committee of the Hiroshima Synchrotron Radiation Center(Proposal Numbers:18AG029 and 18BG031).
文摘The topological insulators Bi_(2-x)Fe_(x)Se_(3-x)S_(x) have been investigated by the dc-magnetization,magnetotransport and angle resolved photoemission spectroscopy(ARPES)techniques.With doping of Fe and S,a negative giant magneto-resistance(MR)is observed for parallel electric and magnetic fields(H||E).The MR behavior at lower magnetic field can be explained with the semi-classical theory whereas the MR behavior at higher field has been attributed to the axial anomaly.Interestingly,the system reached to the quantum limit at low magnetic field(~4.5T).The magnetic ordering can be explained with the presence of both the RKKY(surface)and van-Vleck(bulk)interaction.The ARPES study reveals that a surface gap is suppressed when the magnetic ordering changes from ferromagnetic to anti-ferromagnetic ordering.The ARPES study and the appearance of quantum oscillations(SdH)in the resistivity pattern reveal that the topological surface property is preserved with the co-doping of Fe and S.
