The present study examines the toxicological effects and bioaccumulation of strontium(Sr^(2+))in two Moroccan wheat species,Triticum durum(Nachit)and Triticum aestivum(Ibtissam).Germination rates and seedling growth p...The present study examines the toxicological effects and bioaccumulation of strontium(Sr^(2+))in two Moroccan wheat species,Triticum durum(Nachit)and Triticum aestivum(Ibtissam).Germination rates and seedling growth parameters were evaluated under Sr^(2+)concentrations of 0,10,100,and 1000 mM.Results revealed a significant decline in germination rates as Sr^(2+)concentrations increased,with T.aestivum showing higher sensitivity compared to T.durum.Low Sr^(2+)concentrations(10 mM)initially promoted stem growth in T.aestivum,but growth declined sharply at higher concentrations.Both species sustained growth at moderate Sr^(2+)concentrations(100 mM),but experienced a substantial reduction at 1000 mM,with T.durum demonstrating slightly better tolerance.Elevated Sr^(2+)concentrations notably affected root length and stem branching,indicating severe phytotoxic effects.Enzyme activity assays showed that at low Sr^(2+)concentration(10 mM),GST,CAT,POD,and SOD activities were similar to the control.At moderate concentrations(100 mM),GST and POD activities increased,suggesting enhanced detoxification.At high concentrations(1000 mM),all enzyme activities were significantly elevated,reflecting a robust antioxidative defense mechanism.This study provides valuable insights into the toxicological impacts and physiological responses of these wheat species to Sr^(2+)stress.展开更多
Herein, the electrochemical behaviors of Sr on inert W electrode and reactive Zn/Al electrodes were systematically investig-ated in LiCl–KCl–SrCl2molten salts at 773 K using various electrochemical methods. The chem...Herein, the electrochemical behaviors of Sr on inert W electrode and reactive Zn/Al electrodes were systematically investig-ated in LiCl–KCl–SrCl2molten salts at 773 K using various electrochemical methods. The chemical reaction potentials of Li and Sr on re-active Zn/Al electrodes were determined. We observed that Sr could be extracted by decreasing the activity of the deposited metal Sr onthe reactive electrode, although the standard reduction potential of Sr(II)/Sr was more negative than that of Li(I)/Li. The electrochemicalextraction products of Sr on reactive Zn and Al electrodes were Zn13Sr and Al4Sr, respectively, with no codeposition of Li observed.Based on the density functional theory calculations, both Zn13Sr and Al4Sr were identified as stable intermetallic compounds with Zn-/Al-rich phases. In LiCl–KCl molten salt containing 3wt% SrCl2, the coulombic efficiency of Sr in the Zn electrode was ~54%. The depolar-ization values for Sr on Zn and Al electrodes were 0.864 and 0.485 V, respectively, exhibiting a stronger chemical interaction between Znand Sr than between Al and Sr. This study suggests that using reactive electrodes can facilitate extraction of Sr accumulated while elec-trorefining molten salts, thereby enabling the purification and reuse of the salt and decreasing the volume of the nuclear waste.展开更多
Delayed or non-healing of diabetic wounds is a significant complication,often attributed to high glucose-induced M1 macrophage accumulation,impaired angiogenesis,and reactive oxygen species(ROS)buildup.Addressing this...Delayed or non-healing of diabetic wounds is a significant complication,often attributed to high glucose-induced M1 macrophage accumulation,impaired angiogenesis,and reactive oxygen species(ROS)buildup.Addressing this,we introduced a strontium polyphenol network microneedle patch(SrC-MPNs@MN-PP)for percutaneous drug delivery.This patch,formulated with polymer poly(γ-glutamic acid)(γ-PGA)and epsilon-poly-l-lysine(ε-PLL),incorporates strontium polyphenol networks(SrC-MPNs).The release of chlorogenic acid(CGA)from SrC-MPNs not only neutralizes ROS,but strontium ions also foster angiogen-esis.Consequently,SrC-MPNs@MN-PP can ameliorate the diabetic wound microenvironment and expedite healing.展开更多
Understanding the hydrochemical characteristics and genesis mechanisms of strontium-rich groundwater is pivotal for supporting the exploitation and utilization of natural strontium-rich groundwater.In this research,27...Understanding the hydrochemical characteristics and genesis mechanisms of strontium-rich groundwater is pivotal for supporting the exploitation and utilization of natural strontium-rich groundwater.In this research,27 groundwater samples were collected.By analyzing major ion chemistry and strontium isotope data,and considering the hydrogeological context,various analytical approaches,including multivariate statistics,ion ratios,and isotopes,were used to reveal the characteristics and genesis mechanisms of strontium-rich groundwater in the study area.The findings indicate that the predominant hydrochemical type of groundwater is HCO_(3)-Ca,with Ca^(2+)and HCO_(3)^(-)as the primary cations and anions.The hydrochemistry of the strontium-rich groundwater is predominantly influenced by rock weathering processes.A combination of factors,including ion exchange,and anthropogenic activities,shapes the compositional characteristics of the groundwater in the region.The dissolution of calcite due to weathering emerges as the principal source of strontium in the groundwater.While ion exchange processes are not conducive to strontium enrichment in groundwater,their effect is relatively limited.The impact of human activities on the groundwater is minor.展开更多
Strontium-90,a highly radioactive isotope,accumulates within the food chain and skeletal structure,posing significant risks to human health.There is a critical need for a sensitive detection strategy for Strontium-90 ...Strontium-90,a highly radioactive isotope,accumulates within the food chain and skeletal structure,posing significant risks to human health.There is a critical need for a sensitive detection strategy for Strontium-90 in complex environmental samples.Here,solid-state nanochannels,modified with metal-organic frameworks(MOF)and specific aptamers,were engineered for highly sensitive detection of strontium ion(Sr^(2+)).The synergistic effect between the reduced effective diameter of the nanochannels due to MOF and the specific binding of Sr^(2+) by aptamers amplifies the difference in ionic current signals,enhancing detection sensitivity significantly.The MOF-modified nanochannels exhibit highly sensitive detection of Sr^(2+),with a limit of detection(LOD)being 0.03 nmol·L^(-1),whereas the LOD for anodized aluminum oxide(AAO)without the modified MOF nanosheets is only 1000 nmol·L^(-1).These findings indicate that the LOD of Sr^(2+) detected by the MOF-modified nanochannels is approximately 33,000 times higher than that by the nanochannels without MOF modification.Additionally,the highly reliable detection of Sr^(2+) in various water samples was achieved,with a recovery rate ranging from 94.00%to 118.70%.This study provides valuable insights into the rapidly advancing field of advanced nanochannel-based sensors and their diverse applications for analyzing complex samples,including environmental contaminant detection,food analysis,medical diagnostics,and more.展开更多
The dielectric properties and phase transition characteristics of La2O3- and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated. The microstructure was identified by X-ray d...The dielectric properties and phase transition characteristics of La2O3- and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated. The microstructure was identified by X-ray diffraction method and scanning electron microscope was also employed to observe the surface morphologies. It is found that （La,Sb）-codoped barium strontium titanate ceramics exhibit typical perovskite structure and the average grain size decreases dramatically with increasing the content of Sb2O3. Both La3＋ ions and Sb3＋ ions occupy the A-sites in perovskite lattice. The dielectric constant and dielectric loss of barium strontium titanate based ceramics are obviously influenced by La2O3 as well as Sb2O3 addition content. The tetragonal-cubic phase transition of La2O3 modified barium strontium titanate ceramics is of second order and the Curie temperature shifts to lower value with increasing the La2O3 doping content. The phase transition of （La,Sb）-codoped barium strontium titanate ceramics diffuses and the deviation from Curie-Weiss law becomes more obvious with the increase in Sb2O3 concentration. The temperature corresponding to the dielectric constant maximum of （La,Sb）-codoped barium strontium titanate ceramics decreases with increasing the Sb2O3 content, which is attributed to the replacement of host ions by the Sb3＋ ions.展开更多
To obtain an Sr-substituted hydroxyapatite thin film, sputter-coating was performed on a cellulose filter acting as a substrate from the mixture target of hydroxyapatite （HA） and strontium-apatite （SrAp） at an Ar ...To obtain an Sr-substituted hydroxyapatite thin film, sputter-coating was performed on a cellulose filter acting as a substrate from the mixture target of hydroxyapatite （HA） and strontium-apatite （SrAp） at an Ar pressure of 0.5-5.0 Pa. The ratio of the SrAp in the mixture target was varied from 25% to 100%. After coating, the films were heated at 700 ℃ to remove the cellulose filter substrate, and the crystalline phases were identified by X-ray diffraction （XRD）. The sputter-coated film was identified as the Sr-substituted /3-tri-calcium phosphate （TCP） and the Sr-substituted/3-calcium pyrophosphate （CPP） as well as the Sr-substituted HA. The weight ratio of the Sr-substituted HA decreased with increasing Ar pressure or with an increasing ratio of SrAp to HA in the target. The average Sr/（Ca ＋ Sr） molar ratio in the film was 1.9%-3.5% slightly lower than the initial SrAp ratio of the target, and the ratio was not influenced by the Ar pressure. In the （Sr ＋ Ca）/P ratio, the ratio decreased while increasing the SrAp ratio in the target.展开更多
The research on the trace elements of Ordovician carbonates plays an important part in the whole work on reservoir in Tazhong （塔中 ） area. This paper systematically studies the characteristics and sedimentary setti...The research on the trace elements of Ordovician carbonates plays an important part in the whole work on reservoir in Tazhong （塔中 ） area. This paper systematically studies the characteristics and sedimentary settings of Ordovician dolomites in Tazhong area, Tarim basin, and debates their enrichment of mechanisms and different element existing patterns. The study makes use of ICP-MS analysis technology to test the strontium and manganese content of 109 samples from four wells in the Tazhong area, Tarim basin and strontium isotope composition tests have also been done on 25 samples from wells Zhong-1 and Zhong-4 on VG354 solid isotope mass spectrograph. By means of analyzing contents of strontium and manganese elements, doing research on the strontium isotope composition characteristics from wells Zhong-1 and Zhong-4 and comparing the results of strontium analysis to the global Ordovician marine carbonate and its evolution trend, in the combination of sedimentary facies characteristics of isolated wells in this area, we can come to the following cognitions： （1） The marine carbonate strontium isotope curve in the Tazhong area of Tarim basin is consistent to the global evolution trend which is overall descending with time, the direct reason of which is the evolution of paleogeographic environment. The Ordovician paleogeographic environment goes through restricted platform to open platform and then shallow marine shelf in Tazhong area, Tarim basin. Dolomitization is another subordinate reason and the inversion of fluid with high manganese can lead to heavy strontium; （2） The fact that the 87 Sr/86 Sr ratios of the Upper Ordovician in Tazhong area have an apparent mono-decline trend with the time going by, which is similar to the global strontium isotope ratio, is suggesting that the variation of the Upper Ordo- vician sea level is starting, the overall trend of which is the rising of the sea level; （3） Compared to the global seawater strontium ratios, the ^87Sr/^86 Sr ratio of the Lower Ordovician is much high, and ^87Sr/^86Sr ratio of the Lower Ordovician is overall increasing with its maximum value reaching 0. 709 727, the reasons of which are dolomitization, evaporation of the supratidal and the reflux of high manganese haline, those reasons can lead to the increasing amount of the strontium and the rising of the ^87 Sr/^86 Sr ratio; （4） The manganese element content changes little. Dolomitization has little impact on it; （5） Big variation occurs in the strontium values of Ordovician carbonate in the region of Tazhong. Apart from paleogeographic environment and petrography, the factors which can affect the values of strontium are the content of the terrestrial clastics and the diagenesis modification which may result in the further changing of the strontium values.展开更多
238 marine carbonate samples were collected from seven sedimentary sections ofthe entire late Palaeozoic (Permian, Carboniferous and Devonian) in the Upper Yangtze Plat-form, southwest China. Based on the absence of c...238 marine carbonate samples were collected from seven sedimentary sections ofthe entire late Palaeozoic (Permian, Carboniferous and Devonian) in the Upper Yangtze Plat-form, southwest China. Based on the absence of cathodoluminescence and very low Mn (gener-ally<50 ppm) contents of the samples, it is thought that they contain information on the orig-inal sea water geochemistry. The results of isotopic analyses of these samples are presented interms of δ^(13)C and ^(87)Sr/^(86)Sr ratios versus geological time. The strontium data, consistent withother similar data based on samples from North America, Europe, Africa and other areas inAsia, support the notion of a global consistency in strontium isotope composition of marinecarbonates. The strontium data exhibit three intervals of relatively low ^(87)Sr/^(86)Sr ratios in thelate Middle Devonian to early Late Devonian, Early Carboniferous and Early Permian, corre-sponding to global eustatic high sea level stands. The lowest ^(87)Sr/^(86)Sr ratio recorded in theLate Permian was probably caused by substantial basalt eruptions in the Upper Yangtze Plat-form at the time. Three corresponding periods of relatively high δ^(13)C values at roughly the samethe intervals were caused by a relatively high rate of accumulation of organic carbon duringsea level rises at these times. The deposition of coal was probably responsible for the increaseof sea water δ^(13)C at other times. The δ^(13)C values drop dramatically near theDevonian/Carboniferous, Carboniferous/Permian and Permian/Triassic boundaries, con-sistent with other similar data, which further support the notion that geological time boundariesare associated with mass extinction and subsequent rejuvenation.展开更多
Groundwater from karst subterranean streams is among the world＇s most important sources of drinking water supplies, and the hydrochemical characteristics of karst water are impacted by both natural environment and pe...Groundwater from karst subterranean streams is among the world＇s most important sources of drinking water supplies, and the hydrochemical characteristics of karst water are impacted by both natural environment and people. Therefore, the study of hydrochemistry and its solutes＇ sources is very important to ensure the normal function of life support systems. In this paper, thirty-five representative karst groundwater samples were collected from different aquifers （limestone and dolomite） and various land use types in Chongqing to trace the sources of solutes and relative hydrochemical processes. Hydrogeochemical types of karst groundwater in Chongqing were mainly of the Ca-HCO3 type or Ca （Mg）-HCO3 type. However, some hydrochemical types of karst groundwater were the K＋Na＋Ca-SO4 type （G25 site） or Ca-HCO3＋SO4 type （G26 and G14 site）, indicating that the hydrochemistry of these sites might be strongly influenced by anthropogenic activities or unique geological characteristics. The dissolved Sr concentrations of the studied groundwater ranged from 0.57 to 15.06 ~tmmol/L, and the STSr/S6Sr varied from 0.70751 to 0.71627. The j34S-SO42- fell into a range of-6.8%o-21.5%o, with a mean value of 5.6%o. The variations of both 87Sr/S6Sr and Sr values of the groundwater samples indicated that the Sr element was controlled by the weathering of limestone, dolomite and silicate rock. However, the figure of STSr/S6Sr vs. Sr2＋/[K＋＋Na＋] showed that the anthropogenic inputs also obviously contributed to the Sr contents. For tracing the detailed anthropogenic effects, we traced the sources of solutes collected karst groundwater samples in Chongqing according to the j34S value of potential sulfate sources. The variations of both j34S and 1/ SO42- values of the groundwater samples indicated that the atmospheric acid deposition （AAD）, dissolution of gypsum （GD）, oxidation of sulfide mineral （OS） or anthropogenic inputs （SF： sewage or fertilizer） have contributed to solutes in karst groundwater. The influence of oxidation of sulfide mineral, atmospheric acid deposit and anthropogenic inputs to groundwater in Chongqing karst areas was much widespread.展开更多
We report the 87Sr optical lattice clock developed at the National Time Service Center. We achieved a closed-loop operation of the optical lattice clock based on 87Sr atoms. The linewidth of the spin-polarized clock p...We report the 87Sr optical lattice clock developed at the National Time Service Center. We achieved a closed-loop operation of the optical lattice clock based on 87Sr atoms. The linewidth of the spin-polarized clock peak is 3.9 Hz with a clock laser pulse length of 300 ms, which corresponds to a Fourier-limited linewidth of 3 Hz. The fitting of the in-loop error signal data shows that the instability is approximately 5 × 10 15τ-1/2, affected primarily by the white noise. The fractional frequency difference averages down to 5.7 × 10 ^-17 for an averaging time of 3000 s.展开更多
In a quest of search for a new burning rate modifier for composite propellant, strontium titanate (SrTiO3), a perovskite oxide has been chosen for evaluation in a composite propellant formulation based on its other ca...In a quest of search for a new burning rate modifier for composite propellant, strontium titanate (SrTiO3), a perovskite oxide has been chosen for evaluation in a composite propellant formulation based on its other catalytic applications. Initially, SrTiO3 was characterized for particle size, morphology and material/ phase identification (using XRD). By varying SrTiO3 content in a standard composite propellant, different compositions were prepared and their performance and processing parameters like the end of mix (EOM) viscosity, mechanical properties, density, burning rate, pressure exponent (n-value), etc. were measured. The results reveal that 2% SrTiO3 causes more than 12% enhancement in propellant burning rate (at 70 ksc pressure) in comparison to the standard propellant composition. The pressure exponent also increases to 0.46, whereas the standard composition was having its value as 0.35.展开更多
Doped strontium(Sr) hexaferrites appeared potential candidates for microwave absorber applications.Driven by this idea, we examined the influence of manganese(Mn) and yttrium(Y) co-substitution on the microstructures,...Doped strontium(Sr) hexaferrites appeared potential candidates for microwave absorber applications.Driven by this idea, we examined the influence of manganese(Mn) and yttrium(Y) co-substitution on the microstructures,morphology and magnetic properties of Sr nanohexaferrites(Sr1-xMnxFe12-yYyO19,where 0.0 ≤ x = y ≤ 0.5) synthesized via citrate sol-gel auto-combustion technique. As-prepared samples were thoroughly characterized using diverse analytical tools. X-ray diffraction pattern reveals a single Mhexagonal crystalline phase. FE-SEM, TEM, HR-TEM show a hexagonal platelet-like structure. The magnetic hysteresis loops(measured at room and low temperature) of the as-prepared nanohexaferrites exhibit ferromagnetic(FM) behavior. Magnetic parameters including the saturation magnetization,remanence, coercive and magneto-crystalline anisotropy field are found to decrease with the increase in Mn2+ and Y3+ contents. Zero-and normal-field cooled magnetization measurements in the range of 2-400 K display the complete absence of blocking temperature, confirming the characteristic ferromagnetic behavior of the proposed composition.展开更多
Pregnancy-induced hypertension(PIH),including gestational hypertension and preeclampsia,accounts for the majority of maternal and perinatal morbidity and mortality.Strontium(Sr)has been recently associated with preecl...Pregnancy-induced hypertension(PIH),including gestational hypertension and preeclampsia,accounts for the majority of maternal and perinatal morbidity and mortality.Strontium(Sr)has been recently associated with preeclampsia in a small group of women;however,the role of Sr in PIH is not fully understood and warrants further investigation.In this study,we examined the association between urinary Sr levels and PIH,and assessed the effect of maternal age on the association.Urinary Sr concentrations were measured in 5423 pregnant women before delivery by inductively coupled plasma mass spectrometry(ICP-MS).Logistic regression analysis adjusting for potential confounders was applied to explore the association between Sr and PIH,and to evaluate the Sr-PIH relationship stratified by maternal age.Among the participants,200(3.83%)women were diagnosed with PIH.Compared with non-PIH women,women who developed PIH had lower urinary Sr concentrations(131.26 us.174.98μg/L creatinine,P<0.01).With the natural log-transformed urinary creatinine-standardized Sr concentrations increasing,the risk of PIH decreased significantly[adjusted OR=0.60(95%CI:0.51,0.72)].Furthermore,the significant association of Sr with PIH was found among women under 35 years(P<0.01).Our finding suggested that Sr may play a potential protective role in the pathogenesis of PIH,especially among young pregnant women under 35 years old.展开更多
Strontium-induced stress in growth and chlorophyll contents of Platymonas subcordiformis was investigated under laboratory condition. The results showed that strontium exposure had little influ- ences in general on gr...Strontium-induced stress in growth and chlorophyll contents of Platymonas subcordiformis was investigated under laboratory condition. The results showed that strontium exposure had little influ- ences in general on growth and chlorophyll contents of the algae except for very high Sr concentrations. The maximum biosorption capacity of strontium ranged from 69.62 to 269.18 mg Sr2+/g dry weight. The algal biomass exhibited high uptake capacity of strontium. Total superoxide dismutase (SOD) activity and the content of lipid peroxidation products malondialdehyde (MDA) were significantly different in differ- ent treatments. SOD activity reached the highest level at 0.09 mmol/L that was about 55.8 % higher than that in the control. The MDA content increased significantly at 0.36 mmol/L, which was 2.15 times higher than that in the control, indicating a state of oxidative stress. With the increase of strontium concentration, the amount of fatty acids decreased.展开更多
Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study,...Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.展开更多
Nanoparticles of hydroxyapatite（HAP）, strontium half substituted hydroxyapatite （SrCaHAP） and strontium totally substituted hydroxyapatite （SrHAP） were prepared by sol-gel-supercritical fluid drying （SCFD） met...Nanoparticles of hydroxyapatite（HAP）, strontium half substituted hydroxyapatite （SrCaHAP） and strontium totally substituted hydroxyapatite （SrHAP） were prepared by sol-gel-supercritical fluid drying （SCFD） method. The nanoparticles were characterized by element content analysis, FT-IR, XRD and TEM, and the effects of strontium substitution on crystal structure, crystallinity, particle shape and antibacterial properties of the nanoparticles on Escherichia coli, Staphylococcus aureus, Lactobacillus were researched. Results show that strontium can half and totally substitute for calcium and enter the structure of apatite according to the initial atomic ratios of Sr/[Sr＋Ca] as 0.5, 1. The substitution decreases the IR wavenumbers of SrCaHAP and SrHAP, and changes the morphology of the nanoparticles from short rod shaped HAP to needle shaped SrCaHAP, and back to short rod shaped SrHAP. The crystallinity of HAP is higher than that of SrCaHAP, but is lower than that of SrHAP. Moreover, the antibacterial property of SrCaHAP and SrHAP are improved after the calcium is half and totally substituted by strontium.展开更多
The effects of heat treatment and strontium(Sr) addition on the microstructure and mechanical properties of ADC1_(2) alloys were investigated,and two-stage solution treatment was introduced.The results indicated that ...The effects of heat treatment and strontium(Sr) addition on the microstructure and mechanical properties of ADC1_(2) alloys were investigated,and two-stage solution treatment was introduced.The results indicated that the addition of Sr obviously refined the microstructure of ADC12 alloys.When 0.05 wt%Sr was added into the alloy,the eutectic Si phase was fully modified into fine fibrous structure;a-A1 andβ-A1_(5)FeSi phases were best refined;and the eutectic AlzCu phase was modified into block-like AlzCu phase that continuously distributed at the grain boundary.The ultimate tensile strength(UTS)(270.63 MPa)and elongation(3.19%)were increased by 51.2%and 73.4%respectively compared with unmodified alloys.After the two-stage solution treatment(500℃,6 h+520℃,4 h),for 0.05 wt%Sr modified ADC12 alloys,the Si phases transformed into fine particle structure and Al_(2)Cu phases were fully dissolved.The peak hardness value of the alloys processed by the two-stage solution treatment was increased by 8.3%and 6.8%respectively compared to solution treatment at 500℃and 520℃.After the aging treatment(175℃,7 h),the hardness and UTS were increased by 38.73%and 13.96%respectively when compared with the unmodified alloy.展开更多
The roles of different point defects in persistent luminescence of SrAl2O4：Eu,Dy phosphors were investigated. The research results showed that Dyer plays an important role in the persistent luminescence of SrA1EO4：E...The roles of different point defects in persistent luminescence of SrAl2O4：Eu,Dy phosphors were investigated. The research results showed that Dyer plays an important role in the persistent luminescence of SrA1EO4：Eu, Dy phosphors. It can serve as the electron trap of suitable depth for persistent luminescence. V~ does not serve as the electron trap of suitable depth, but its existence can increase the depth of electron traps. There is interaction between the Dy^3＋（ DySr ） and the Eu^2＋（Eu^x Sr ）, and only if the distance between the Dy^3＋（DySr） and the Eu^2＋ （Eu^x Sr） is close enough, the Dyer can work as an effective electron trap. The point defect of V＂ Sr can be hole trap, but the change of its density in crystal matrix does not arouse the obvious change of persistent luminescence.展开更多
PtSnSr/HZSM-5 catalysts with different amounts of strontium were prepared by sequential impregnation method, and characterized by BET analysis, TEM, NH3-TPD, Hz-TPR, TPO and TG techniques. The results showed that the ...PtSnSr/HZSM-5 catalysts with different amounts of strontium were prepared by sequential impregnation method, and characterized by BET analysis, TEM, NH3-TPD, Hz-TPR, TPO and TG techniques. The results showed that the addition of strontium could modify the characteristics and properties of both acid function and metal function of Pt-Sn-based cata- lysts. In this case, PtSnSr/HZSM-5 catalyst with an appropriate amount of Sr （1.2%） showed higher catalytic activity and lower amount of coke deposits than PtSn/HZSM-5 catalyst. However, excessive loading of Sr could facilitate the reduction of Sn, which was unfavorable to the reaction. Afterwards, 1.0 m% of Na was added into the PtSnSr（1.2%）/HZSM-5 catalyst to improve the catalytic performance in propane dehydrogenation, and this catalyst displayed the best catalytic performance during our experiments. After having been subjected to reaction for 5 h, the PtSnNa（1.0%）Sr（1,2%）/HZSM-5 catalyst had achieved a higher than 95% selectivity towards propene along with a corresponding propane conversion rate of 32.2%.展开更多
文摘The present study examines the toxicological effects and bioaccumulation of strontium(Sr^(2+))in two Moroccan wheat species,Triticum durum(Nachit)and Triticum aestivum(Ibtissam).Germination rates and seedling growth parameters were evaluated under Sr^(2+)concentrations of 0,10,100,and 1000 mM.Results revealed a significant decline in germination rates as Sr^(2+)concentrations increased,with T.aestivum showing higher sensitivity compared to T.durum.Low Sr^(2+)concentrations(10 mM)initially promoted stem growth in T.aestivum,but growth declined sharply at higher concentrations.Both species sustained growth at moderate Sr^(2+)concentrations(100 mM),but experienced a substantial reduction at 1000 mM,with T.durum demonstrating slightly better tolerance.Elevated Sr^(2+)concentrations notably affected root length and stem branching,indicating severe phytotoxic effects.Enzyme activity assays showed that at low Sr^(2+)concentration(10 mM),GST,CAT,POD,and SOD activities were similar to the control.At moderate concentrations(100 mM),GST and POD activities increased,suggesting enhanced detoxification.At high concentrations(1000 mM),all enzyme activities were significantly elevated,reflecting a robust antioxidative defense mechanism.This study provides valuable insights into the toxicological impacts and physiological responses of these wheat species to Sr^(2+)stress.
基金financially supported by the National Postdoctoral Program for Innovative Talents, China (No. BX2021327)the National Natural Science Foundation of China (Nos. 22206194 and U2267222)+1 种基金the Ningbo Natural Science Foundation of China (No. 2023J337)the Yongjiang Talent Introduction Programme, China (No. 2 021A-161-G)。
文摘Herein, the electrochemical behaviors of Sr on inert W electrode and reactive Zn/Al electrodes were systematically investig-ated in LiCl–KCl–SrCl2molten salts at 773 K using various electrochemical methods. The chemical reaction potentials of Li and Sr on re-active Zn/Al electrodes were determined. We observed that Sr could be extracted by decreasing the activity of the deposited metal Sr onthe reactive electrode, although the standard reduction potential of Sr(II)/Sr was more negative than that of Li(I)/Li. The electrochemicalextraction products of Sr on reactive Zn and Al electrodes were Zn13Sr and Al4Sr, respectively, with no codeposition of Li observed.Based on the density functional theory calculations, both Zn13Sr and Al4Sr were identified as stable intermetallic compounds with Zn-/Al-rich phases. In LiCl–KCl molten salt containing 3wt% SrCl2, the coulombic efficiency of Sr in the Zn electrode was ~54%. The depolar-ization values for Sr on Zn and Al electrodes were 0.864 and 0.485 V, respectively, exhibiting a stronger chemical interaction between Znand Sr than between Al and Sr. This study suggests that using reactive electrodes can facilitate extraction of Sr accumulated while elec-trorefining molten salts, thereby enabling the purification and reuse of the salt and decreasing the volume of the nuclear waste.
基金supported by the National Natural Science Foundation of China(No.31971271)The Natural Science Foundation of Fujian Province of China(No.2022J01794)The Science and Technology Plan Project of Quanzhou(No.2021N033S).
文摘Delayed or non-healing of diabetic wounds is a significant complication,often attributed to high glucose-induced M1 macrophage accumulation,impaired angiogenesis,and reactive oxygen species(ROS)buildup.Addressing this,we introduced a strontium polyphenol network microneedle patch(SrC-MPNs@MN-PP)for percutaneous drug delivery.This patch,formulated with polymer poly(γ-glutamic acid)(γ-PGA)and epsilon-poly-l-lysine(ε-PLL),incorporates strontium polyphenol networks(SrC-MPNs).The release of chlorogenic acid(CGA)from SrC-MPNs not only neutralizes ROS,but strontium ions also foster angiogen-esis.Consequently,SrC-MPNs@MN-PP can ameliorate the diabetic wound microenvironment and expedite healing.
基金supported by the Guangxi Natural Science Foundation(2020GXNSFAA297025)the Guangxi Natural Science Foundation(GuikeAB22080046)+3 种基金the Guangxi Natural Science Foundation(GuikeAB21196050)the National Natural Science Foundation of China(42177075)the Natural Resources Science and Technology Strategic Research Project(2023-ZL-23)the Survey and China Geological Survey(DD20221808 and DD20230547).
文摘Understanding the hydrochemical characteristics and genesis mechanisms of strontium-rich groundwater is pivotal for supporting the exploitation and utilization of natural strontium-rich groundwater.In this research,27 groundwater samples were collected.By analyzing major ion chemistry and strontium isotope data,and considering the hydrogeological context,various analytical approaches,including multivariate statistics,ion ratios,and isotopes,were used to reveal the characteristics and genesis mechanisms of strontium-rich groundwater in the study area.The findings indicate that the predominant hydrochemical type of groundwater is HCO_(3)-Ca,with Ca^(2+)and HCO_(3)^(-)as the primary cations and anions.The hydrochemistry of the strontium-rich groundwater is predominantly influenced by rock weathering processes.A combination of factors,including ion exchange,and anthropogenic activities,shapes the compositional characteristics of the groundwater in the region.The dissolution of calcite due to weathering emerges as the principal source of strontium in the groundwater.While ion exchange processes are not conducive to strontium enrichment in groundwater,their effect is relatively limited.The impact of human activities on the groundwater is minor.
基金supported by the National Natural Science Foundation of China(No.22090050,No.22090052,No.22176180)National Basic Research Program of China(No.2021YFA1200400)+1 种基金the Natural Science Foundation of Hubei Province(No.2024AFA001)Shenzhen Science and Technology Program(No.JCYJ20220530162406014)。
文摘Strontium-90,a highly radioactive isotope,accumulates within the food chain and skeletal structure,posing significant risks to human health.There is a critical need for a sensitive detection strategy for Strontium-90 in complex environmental samples.Here,solid-state nanochannels,modified with metal-organic frameworks(MOF)and specific aptamers,were engineered for highly sensitive detection of strontium ion(Sr^(2+)).The synergistic effect between the reduced effective diameter of the nanochannels due to MOF and the specific binding of Sr^(2+) by aptamers amplifies the difference in ionic current signals,enhancing detection sensitivity significantly.The MOF-modified nanochannels exhibit highly sensitive detection of Sr^(2+),with a limit of detection(LOD)being 0.03 nmol·L^(-1),whereas the LOD for anodized aluminum oxide(AAO)without the modified MOF nanosheets is only 1000 nmol·L^(-1).These findings indicate that the LOD of Sr^(2+) detected by the MOF-modified nanochannels is approximately 33,000 times higher than that by the nanochannels without MOF modification.Additionally,the highly reliable detection of Sr^(2+) in various water samples was achieved,with a recovery rate ranging from 94.00%to 118.70%.This study provides valuable insights into the rapidly advancing field of advanced nanochannel-based sensors and their diverse applications for analyzing complex samples,including environmental contaminant detection,food analysis,medical diagnostics,and more.
基金Project (11KJB430007) supported by the University Natural Science Research Program of Jiangsu Province, ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘The dielectric properties and phase transition characteristics of La2O3- and Sb2O3-doped barium strontium titanate ceramics prepared by solid state route were investigated. The microstructure was identified by X-ray diffraction method and scanning electron microscope was also employed to observe the surface morphologies. It is found that （La,Sb）-codoped barium strontium titanate ceramics exhibit typical perovskite structure and the average grain size decreases dramatically with increasing the content of Sb2O3. Both La3＋ ions and Sb3＋ ions occupy the A-sites in perovskite lattice. The dielectric constant and dielectric loss of barium strontium titanate based ceramics are obviously influenced by La2O3 as well as Sb2O3 addition content. The tetragonal-cubic phase transition of La2O3 modified barium strontium titanate ceramics is of second order and the Curie temperature shifts to lower value with increasing the La2O3 doping content. The phase transition of （La,Sb）-codoped barium strontium titanate ceramics diffuses and the deviation from Curie-Weiss law becomes more obvious with the increase in Sb2O3 concentration. The temperature corresponding to the dielectric constant maximum of （La,Sb）-codoped barium strontium titanate ceramics decreases with increasing the Sb2O3 content, which is attributed to the replacement of host ions by the Sb3＋ ions.
基金partially supported by the Japan Scienceand Technology Agency, A-STEP (AS232Z01193F)
文摘To obtain an Sr-substituted hydroxyapatite thin film, sputter-coating was performed on a cellulose filter acting as a substrate from the mixture target of hydroxyapatite （HA） and strontium-apatite （SrAp） at an Ar pressure of 0.5-5.0 Pa. The ratio of the SrAp in the mixture target was varied from 25% to 100%. After coating, the films were heated at 700 ℃ to remove the cellulose filter substrate, and the crystalline phases were identified by X-ray diffraction （XRD）. The sputter-coated film was identified as the Sr-substituted /3-tri-calcium phosphate （TCP） and the Sr-substituted/3-calcium pyrophosphate （CPP） as well as the Sr-substituted HA. The weight ratio of the Sr-substituted HA decreased with increasing Ar pressure or with an increasing ratio of SrAp to HA in the target. The average Sr/（Ca ＋ Sr） molar ratio in the film was 1.9%-3.5% slightly lower than the initial SrAp ratio of the target, and the ratio was not influenced by the Ar pressure. In the （Sr ＋ Ca）/P ratio, the ratio decreased while increasing the SrAp ratio in the target.
基金This paper is supported by the 973 Project of China ( No .2005CB422103) and by the China Petrochemical Corporation ( SI N-OPEC) .
文摘The research on the trace elements of Ordovician carbonates plays an important part in the whole work on reservoir in Tazhong （塔中 ） area. This paper systematically studies the characteristics and sedimentary settings of Ordovician dolomites in Tazhong area, Tarim basin, and debates their enrichment of mechanisms and different element existing patterns. The study makes use of ICP-MS analysis technology to test the strontium and manganese content of 109 samples from four wells in the Tazhong area, Tarim basin and strontium isotope composition tests have also been done on 25 samples from wells Zhong-1 and Zhong-4 on VG354 solid isotope mass spectrograph. By means of analyzing contents of strontium and manganese elements, doing research on the strontium isotope composition characteristics from wells Zhong-1 and Zhong-4 and comparing the results of strontium analysis to the global Ordovician marine carbonate and its evolution trend, in the combination of sedimentary facies characteristics of isolated wells in this area, we can come to the following cognitions： （1） The marine carbonate strontium isotope curve in the Tazhong area of Tarim basin is consistent to the global evolution trend which is overall descending with time, the direct reason of which is the evolution of paleogeographic environment. The Ordovician paleogeographic environment goes through restricted platform to open platform and then shallow marine shelf in Tazhong area, Tarim basin. Dolomitization is another subordinate reason and the inversion of fluid with high manganese can lead to heavy strontium; （2） The fact that the 87 Sr/86 Sr ratios of the Upper Ordovician in Tazhong area have an apparent mono-decline trend with the time going by, which is similar to the global strontium isotope ratio, is suggesting that the variation of the Upper Ordo- vician sea level is starting, the overall trend of which is the rising of the sea level; （3） Compared to the global seawater strontium ratios, the ^87Sr/^86 Sr ratio of the Lower Ordovician is much high, and ^87Sr/^86Sr ratio of the Lower Ordovician is overall increasing with its maximum value reaching 0. 709 727, the reasons of which are dolomitization, evaporation of the supratidal and the reflux of high manganese haline, those reasons can lead to the increasing amount of the strontium and the rising of the ^87 Sr/^86 Sr ratio; （4） The manganese element content changes little. Dolomitization has little impact on it; （5） Big variation occurs in the strontium values of Ordovician carbonate in the region of Tazhong. Apart from paleogeographic environment and petrography, the factors which can affect the values of strontium are the content of the terrestrial clastics and the diagenesis modification which may result in the further changing of the strontium values.
基金This study was supported by the National Natural Science Foundation of China Grant No.48970116
文摘238 marine carbonate samples were collected from seven sedimentary sections ofthe entire late Palaeozoic (Permian, Carboniferous and Devonian) in the Upper Yangtze Plat-form, southwest China. Based on the absence of cathodoluminescence and very low Mn (gener-ally<50 ppm) contents of the samples, it is thought that they contain information on the orig-inal sea water geochemistry. The results of isotopic analyses of these samples are presented interms of δ^(13)C and ^(87)Sr/^(86)Sr ratios versus geological time. The strontium data, consistent withother similar data based on samples from North America, Europe, Africa and other areas inAsia, support the notion of a global consistency in strontium isotope composition of marinecarbonates. The strontium data exhibit three intervals of relatively low ^(87)Sr/^(86)Sr ratios in thelate Middle Devonian to early Late Devonian, Early Carboniferous and Early Permian, corre-sponding to global eustatic high sea level stands. The lowest ^(87)Sr/^(86)Sr ratio recorded in theLate Permian was probably caused by substantial basalt eruptions in the Upper Yangtze Plat-form at the time. Three corresponding periods of relatively high δ^(13)C values at roughly the samethe intervals were caused by a relatively high rate of accumulation of organic carbon duringsea level rises at these times. The deposition of coal was probably responsible for the increaseof sea water δ^(13)C at other times. The δ^(13)C values drop dramatically near theDevonian/Carboniferous, Carboniferous/Permian and Permian/Triassic boundaries, con-sistent with other similar data, which further support the notion that geological time boundariesare associated with mass extinction and subsequent rejuvenation.
基金supported by the National Natural Science Foundation of China(No:41072192)the Natural Science Foundation Project of Chongqing,CSTC(No. CSTC2010BC7004)+2 种基金the Special Fund for Public Benefit Scientific Research of Ministry of Land and Resources of China(201111022)the Guangxi Natural Science Foundation Project(2012GXNSFBA053137)IGCP/ SIDA 598 Project
文摘Groundwater from karst subterranean streams is among the world＇s most important sources of drinking water supplies, and the hydrochemical characteristics of karst water are impacted by both natural environment and people. Therefore, the study of hydrochemistry and its solutes＇ sources is very important to ensure the normal function of life support systems. In this paper, thirty-five representative karst groundwater samples were collected from different aquifers （limestone and dolomite） and various land use types in Chongqing to trace the sources of solutes and relative hydrochemical processes. Hydrogeochemical types of karst groundwater in Chongqing were mainly of the Ca-HCO3 type or Ca （Mg）-HCO3 type. However, some hydrochemical types of karst groundwater were the K＋Na＋Ca-SO4 type （G25 site） or Ca-HCO3＋SO4 type （G26 and G14 site）, indicating that the hydrochemistry of these sites might be strongly influenced by anthropogenic activities or unique geological characteristics. The dissolved Sr concentrations of the studied groundwater ranged from 0.57 to 15.06 ~tmmol/L, and the STSr/S6Sr varied from 0.70751 to 0.71627. The j34S-SO42- fell into a range of-6.8%o-21.5%o, with a mean value of 5.6%o. The variations of both 87Sr/S6Sr and Sr values of the groundwater samples indicated that the Sr element was controlled by the weathering of limestone, dolomite and silicate rock. However, the figure of STSr/S6Sr vs. Sr2＋/[K＋＋Na＋] showed that the anthropogenic inputs also obviously contributed to the Sr contents. For tracing the detailed anthropogenic effects, we traced the sources of solutes collected karst groundwater samples in Chongqing according to the j34S value of potential sulfate sources. The variations of both j34S and 1/ SO42- values of the groundwater samples indicated that the atmospheric acid deposition （AAD）, dissolution of gypsum （GD）, oxidation of sulfide mineral （OS） or anthropogenic inputs （SF： sewage or fertilizer） have contributed to solutes in karst groundwater. The influence of oxidation of sulfide mineral, atmospheric acid deposit and anthropogenic inputs to groundwater in Chongqing karst areas was much widespread.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474282 and 61775220)the Key Research Project of Frontier Science of the Chinese Academy of Sciences(Grant No.QYZDB-SSW-JSC004)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21030700)
文摘We report the 87Sr optical lattice clock developed at the National Time Service Center. We achieved a closed-loop operation of the optical lattice clock based on 87Sr atoms. The linewidth of the spin-polarized clock peak is 3.9 Hz with a clock laser pulse length of 300 ms, which corresponds to a Fourier-limited linewidth of 3 Hz. The fitting of the in-loop error signal data shows that the instability is approximately 5 × 10 15τ-1/2, affected primarily by the white noise. The fractional frequency difference averages down to 5.7 × 10 ^-17 for an averaging time of 3000 s.
文摘In a quest of search for a new burning rate modifier for composite propellant, strontium titanate (SrTiO3), a perovskite oxide has been chosen for evaluation in a composite propellant formulation based on its other catalytic applications. Initially, SrTiO3 was characterized for particle size, morphology and material/ phase identification (using XRD). By varying SrTiO3 content in a standard composite propellant, different compositions were prepared and their performance and processing parameters like the end of mix (EOM) viscosity, mechanical properties, density, burning rate, pressure exponent (n-value), etc. were measured. The results reveal that 2% SrTiO3 causes more than 12% enhancement in propellant burning rate (at 70 ksc pressure) in comparison to the standard propellant composition. The pressure exponent also increases to 0.46, whereas the standard composition was having its value as 0.35.
基金Institute for Research & Medical Consultations(IRMC)of Imam Abdulrahman Bin Faisal University(IAU-Saudi Arabia) for supporting this study through the Projects application number: [2017-IRMC-S-3][2018-IRMC-S1]and[2018-IRMC-S-2]
文摘Doped strontium(Sr) hexaferrites appeared potential candidates for microwave absorber applications.Driven by this idea, we examined the influence of manganese(Mn) and yttrium(Y) co-substitution on the microstructures,morphology and magnetic properties of Sr nanohexaferrites(Sr1-xMnxFe12-yYyO19,where 0.0 ≤ x = y ≤ 0.5) synthesized via citrate sol-gel auto-combustion technique. As-prepared samples were thoroughly characterized using diverse analytical tools. X-ray diffraction pattern reveals a single Mhexagonal crystalline phase. FE-SEM, TEM, HR-TEM show a hexagonal platelet-like structure. The magnetic hysteresis loops(measured at room and low temperature) of the as-prepared nanohexaferrites exhibit ferromagnetic(FM) behavior. Magnetic parameters including the saturation magnetization,remanence, coercive and magneto-crystalline anisotropy field are found to decrease with the increase in Mn2+ and Y3+ contents. Zero-and normal-field cooled magnetization measurements in the range of 2-400 K display the complete absence of blocking temperature, confirming the characteristic ferromagnetic behavior of the proposed composition.
基金the National Natural Science Foundation of China(No.91743103)Program for HUST Academic Frontier Youth Team(No.2018QYTD12).
文摘Pregnancy-induced hypertension(PIH),including gestational hypertension and preeclampsia,accounts for the majority of maternal and perinatal morbidity and mortality.Strontium(Sr)has been recently associated with preeclampsia in a small group of women;however,the role of Sr in PIH is not fully understood and warrants further investigation.In this study,we examined the association between urinary Sr levels and PIH,and assessed the effect of maternal age on the association.Urinary Sr concentrations were measured in 5423 pregnant women before delivery by inductively coupled plasma mass spectrometry(ICP-MS).Logistic regression analysis adjusting for potential confounders was applied to explore the association between Sr and PIH,and to evaluate the Sr-PIH relationship stratified by maternal age.Among the participants,200(3.83%)women were diagnosed with PIH.Compared with non-PIH women,women who developed PIH had lower urinary Sr concentrations(131.26 us.174.98μg/L creatinine,P<0.01).With the natural log-transformed urinary creatinine-standardized Sr concentrations increasing,the risk of PIH decreased significantly[adjusted OR=0.60(95%CI:0.51,0.72)].Furthermore,the significant association of Sr with PIH was found among women under 35 years(P<0.01).Our finding suggested that Sr may play a potential protective role in the pathogenesis of PIH,especially among young pregnant women under 35 years old.
基金This work was supported by Natural Science Foundation of Jiangsu Province (No. 95021301).
文摘Strontium-induced stress in growth and chlorophyll contents of Platymonas subcordiformis was investigated under laboratory condition. The results showed that strontium exposure had little influ- ences in general on growth and chlorophyll contents of the algae except for very high Sr concentrations. The maximum biosorption capacity of strontium ranged from 69.62 to 269.18 mg Sr2+/g dry weight. The algal biomass exhibited high uptake capacity of strontium. Total superoxide dismutase (SOD) activity and the content of lipid peroxidation products malondialdehyde (MDA) were significantly different in differ- ent treatments. SOD activity reached the highest level at 0.09 mmol/L that was about 55.8 % higher than that in the control. The MDA content increased significantly at 0.36 mmol/L, which was 2.15 times higher than that in the control, indicating a state of oxidative stress. With the increase of strontium concentration, the amount of fatty acids decreased.
基金supported by the National Key Technology R&D Program (Nos. 2012BAC02B01, 2012BAC12B05, 2011BAE13B07, and 2011BAC10B02)the National High Technology Research and Development Program of China (No. 2012AA063202)+2 种基金the National Natural Science Foundation of China (Nos. 51174247 and 51004011)the Science and Technology Program of Guangdong Province, China (No. 2010A030200003)the Ph.D. Programs Foundation of the Ministry of Education of China (No. 2010000612003)
文摘Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.
文摘Nanoparticles of hydroxyapatite（HAP）, strontium half substituted hydroxyapatite （SrCaHAP） and strontium totally substituted hydroxyapatite （SrHAP） were prepared by sol-gel-supercritical fluid drying （SCFD） method. The nanoparticles were characterized by element content analysis, FT-IR, XRD and TEM, and the effects of strontium substitution on crystal structure, crystallinity, particle shape and antibacterial properties of the nanoparticles on Escherichia coli, Staphylococcus aureus, Lactobacillus were researched. Results show that strontium can half and totally substitute for calcium and enter the structure of apatite according to the initial atomic ratios of Sr/[Sr＋Ca] as 0.5, 1. The substitution decreases the IR wavenumbers of SrCaHAP and SrHAP, and changes the morphology of the nanoparticles from short rod shaped HAP to needle shaped SrCaHAP, and back to short rod shaped SrHAP. The crystallinity of HAP is higher than that of SrCaHAP, but is lower than that of SrHAP. Moreover, the antibacterial property of SrCaHAP and SrHAP are improved after the calcium is half and totally substituted by strontium.
基金Project(51364035)supported by the National Natural Science Foundation of ChinaProject(20133601110001)supported by the Ministry of Education Tied up with the Special Research Fund for the Doctoral Program for Higher School,China+1 种基金Project(KJLD14003)supported by the Loading Program of Science and Technology of College of Jiangxi Province,ChinaProject(2012-CYH-DW-XCL-002)supported by the Production and Teaching and Research Cooperation Plan of Naaachaaag Non-party Experts and Doctor,China
文摘The effects of heat treatment and strontium(Sr) addition on the microstructure and mechanical properties of ADC1_(2) alloys were investigated,and two-stage solution treatment was introduced.The results indicated that the addition of Sr obviously refined the microstructure of ADC12 alloys.When 0.05 wt%Sr was added into the alloy,the eutectic Si phase was fully modified into fine fibrous structure;a-A1 andβ-A1_(5)FeSi phases were best refined;and the eutectic AlzCu phase was modified into block-like AlzCu phase that continuously distributed at the grain boundary.The ultimate tensile strength(UTS)(270.63 MPa)and elongation(3.19%)were increased by 51.2%and 73.4%respectively compared with unmodified alloys.After the two-stage solution treatment(500℃,6 h+520℃,4 h),for 0.05 wt%Sr modified ADC12 alloys,the Si phases transformed into fine particle structure and Al_(2)Cu phases were fully dissolved.The peak hardness value of the alloys processed by the two-stage solution treatment was increased by 8.3%and 6.8%respectively compared to solution treatment at 500℃and 520℃.After the aging treatment(175℃,7 h),the hardness and UTS were increased by 38.73%and 13.96%respectively when compared with the unmodified alloy.
基金This study is financially supported by the Jiangxi University of Finance and Economy (Project No. 0421205) Jiangxi Provincial Department of Education (Project No. (2007) 260)
文摘The roles of different point defects in persistent luminescence of SrAl2O4：Eu,Dy phosphors were investigated. The research results showed that Dyer plays an important role in the persistent luminescence of SrA1EO4：Eu, Dy phosphors. It can serve as the electron trap of suitable depth for persistent luminescence. V~ does not serve as the electron trap of suitable depth, but its existence can increase the depth of electron traps. There is interaction between the Dy^3＋（ DySr ） and the Eu^2＋（Eu^x Sr ）, and only if the distance between the Dy^3＋（DySr） and the Eu^2＋ （Eu^x Sr） is close enough, the Dyer can work as an effective electron trap. The point defect of V＂ Sr can be hole trap, but the change of its density in crystal matrix does not arouse the obvious change of persistent luminescence.
基金The Production and Research Prospective Joint Research Project (BY2009153)The Science and Technology Support Program (BE2008129) of Jiangsu Province of Chinathe National Nature Science Foundation of China (50873026,21106017) for financial support
文摘PtSnSr/HZSM-5 catalysts with different amounts of strontium were prepared by sequential impregnation method, and characterized by BET analysis, TEM, NH3-TPD, Hz-TPR, TPO and TG techniques. The results showed that the addition of strontium could modify the characteristics and properties of both acid function and metal function of Pt-Sn-based cata- lysts. In this case, PtSnSr/HZSM-5 catalyst with an appropriate amount of Sr （1.2%） showed higher catalytic activity and lower amount of coke deposits than PtSn/HZSM-5 catalyst. However, excessive loading of Sr could facilitate the reduction of Sn, which was unfavorable to the reaction. Afterwards, 1.0 m% of Na was added into the PtSnSr（1.2%）/HZSM-5 catalyst to improve the catalytic performance in propane dehydrogenation, and this catalyst displayed the best catalytic performance during our experiments. After having been subjected to reaction for 5 h, the PtSnNa（1.0%）Sr（1,2%）/HZSM-5 catalyst had achieved a higher than 95% selectivity towards propene along with a corresponding propane conversion rate of 32.2%.
