Spontaneous Ca2+ oscillations in vascular smooth muscle cells have been modeled using a single Ca2+ pool. This report describes spontaneous Ca2+ oscillations dependent on two separate Ca2+ sources for the nuclear vers...Spontaneous Ca2+ oscillations in vascular smooth muscle cells have been modeled using a single Ca2+ pool. This report describes spontaneous Ca2+ oscillations dependent on two separate Ca2+ sources for the nuclear versus cytoplas- mic compartments. Changes in free intracellular Ca2+ were monitored with ratiometric Ca2+- fluorophores using confo- cal microscopy. On average, spontaneous oscillations developed in 79% of rat aortic smooth muscle cells that were synchronous between the cytoplasm and nucleus. Reduction of extracellular Ca2+ (< 1 μM) decreased the frequency and amplitude of the cytoplasmic oscillations with 48% of the oscillations asynchronous between the nuclear and cytoplasmic compartments. Similar results were obtained with the Ca2+ channel blockers, nimodipine and diltiazem. Arg-vasopressin (AVP) induced a rapid release of intracellular Ca2+ stores that was greater in the nuclear compartment (4.20 ± 0.23 ratio units, n = 56) than cytoplasm (2.54 ± 0.28) in cells that had spontaneously developed prior oscillations. Conversely, cells in the same conditions lacking oscillations had a greater AVP-induced Ca2+ transient in the cytoplasm (4.99 ± 0.66, n = 17) than in the nucleus (2.67 ± 0.29). Pre-treatment with Ca2+ channel blockers depressed the AVP responses in both compartments with the cytoplasmic Ca2+ most diminished. Depletion of internal Ca2+ stores prior to AVP exposure blunted the nuclear response, mimicking the response of cells that lacked prior oscillations. Spontaneous oscillating cells had a greater sarcoplasmic reticulum network than cells that did not oscillate. We propose that sponta- neous nuclear oscillations rely on perinuclear sarcoplasmic reticulum stores, while the cytoplasmic oscillations rely on Ca2+ influx.展开更多
Mature eggs (at metaphase Ⅱ stage) produce a series of Ca2+ oscillation at fertilization. To define whether the fertilization-induced Ca2+ oscillation is restrict to the metaphase Ⅱ eggs and cell cycle dependent, mo...Mature eggs (at metaphase Ⅱ stage) produce a series of Ca2+ oscillation at fertilization. To define whether the fertilization-induced Ca2+ oscillation is restrict to the metaphase Ⅱ eggs and cell cycle dependent, mouse oocytes at prophase Ⅰ (arrested at germinal vesicle stage),metaphase Ⅰ, metaphase Ⅱ, as well as the pronuclear embryos at interphase of the first mitotic division derived from fertilization or parthenogenetic activation were inseminated after removal of zona pellucida. The results show that the fertilization-induced Ca2+ oscillation is not specific to metaphase Ⅱ eggs. This is supported by the fact that immature oocytes generated the Ca2+ oscillations at fertilization regardless of their nuclear progression from prophase Ⅰ to metaphase Ⅰ (in vitro matured) stage. More interestingly, it was first found that pronuclear embryos at interphase derived from parthenogenetic activation showed Ca2+ oscillations in response to fertilization while the zygotes at interphase did not after reinsemination or intracytoplasmic injection of sperm extracts which induce Ca2+ oscillations in MII eggs. This suggests that the ability of oocytes to generate Ca2+ oscillation in response to sperm penetration is not regulated in a cell cycle dependent manner but dependent on the cytoplasmic maturation.展开更多
Inhibitors are important for flotation separation of quartz and feldspar.In this study,a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp.Selective inhibition of the combined inhi...Inhibitors are important for flotation separation of quartz and feldspar.In this study,a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp.Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments.And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation reagents and put forward the synergistic strengthening mechanism.The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca^(2+)and SS in sequence under the optimal proportion of 1:5.A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired,and was found to be 90.70wt% and 83.70%,respectively.It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from Fourier-transform infrared(FT-IR)and adsorption capacity tests.The results of X-ray photoelectron spectroscopy(XPS)indicated that Ca^(2+)directly interacts with the surface of quartz to increase the adsorption of collectors.In contrast,the chemistry property of Al on the feldspar surface was altered by combined inhibitor due to Na^(+)and Ca^(2+)taking the place of K^(+),resulting in the composite inhibitor forms a hydrophilic structure,which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site.The combination of Ca^(2+)and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector,thus achieving the effect of efficient separation.A new strategy for flotation to separate quartz from feldspar in near-neutral pulp was provided.展开更多
Oscillations in temperatures of catalyst bed as well as concentrations of gas phase species at the exit of reactor were observed during the partial oxidation of methane to synthesis gas over Ru/Al2O3 in the temperatur...Oscillations in temperatures of catalyst bed as well as concentrations of gas phase species at the exit of reactor were observed during the partial oxidation of methane to synthesis gas over Ru/Al2O3 in the temperature range of 600 to 850℃. XRD, H2-TPR and in situ Raman techniques was used to characterize the catalyst. Two types of ruthenium species, i.e. the ruthenium species weakly interacted with Al2O3 and that strongly interacted with the support, were identified by H2-TPR experiment. These species are responsible for two types of oscillation profiles observed during the reaction. The oscillations were the result of these ruthenium species switching cyclically between the oxidized state and the reduced state under the reaction condition. These cyclic transformations, in turn, were the result of temperature variations caused by the varying levels of the strongly exothermic CH4 combustion and the highly endothermic CH4 reforming （with H2O and CO2） reactions （or the less exothermic direct partial oxidation of methane to CO and H2）, which were favored by the oxidized and the metallic sites, respectively. The major pathway of synthesis gas formation over the catalyst was via the combustion-reforming mechanism.展开更多
In order to investigate the effects of aconitine on [Ca2＋] oscillation patterns in cultured myocytes of neonatal rats, fluorescent Ca2＋ indicator Fluo-4 NW and laser scanning confocal micro- scope （LSCM） were used...In order to investigate the effects of aconitine on [Ca2＋] oscillation patterns in cultured myocytes of neonatal rats, fluorescent Ca2＋ indicator Fluo-4 NW and laser scanning confocal micro- scope （LSCM） were used to detect the real-time changes of [Ca2＋] oscillation patterns in the cultured myocytes before and after aconitine （1.0 μmol/L） incubation or antiarrhythmic peptide （AAP） and aconitine co-incubation. The results showed under control conditions, [Ca2＋] oscillations were irregu- lar but relatively stable, occasionally accompanied by small calcium sparks. After incubation of the cultures with aconitine, high frequency [Ca2＋] oscillations emerged in both nuclear and cytoplasmic regions, whereas typical calcium sparks disappeared and the average [Ca2＋] in the cytoplasm of the cardiomyocyte did not change significantly. In AAP-treated cultures, intracellular [Ca2＋] oscillation also changed, with periodic frequency, increased amplitudes and prolonged duration of calcium sparks. These patterns were not altered significantly by subsequent aconitine incubation. The basal value of [Ca2＋] in nuclear region was higher than that in the cytoplasmic region. In the presence or absence of drugs, the [Ca2＋] oscillated synchronously in both the nuclear and cytoplasmic regions of the same cardiomyocyte. It was concluded that although oscillating strenuously at high frequency, the average [Ca2＋] in the cytoplasm of cardiomyocyte did not change significantly after aconitine incuba- tion, compared to the controls. The observations indicate that aconitine induces the changes in [Ca2＋] oscillation frequency other than the Ca2＋ overload.展开更多
We present a systematical study on single crystalline FeSb2 using electrical transport and magnetic torque measurements at low temperatures. Nonlinear magnetic field dependence of Hall resistivity demonstrates a multi...We present a systematical study on single crystalline FeSb2 using electrical transport and magnetic torque measurements at low temperatures. Nonlinear magnetic field dependence of Hall resistivity demonstrates a multi-carrier transport instinct of the electronic transport. Current-controlled negative differential resistance(CC-NDR) observed in currentvoltage characteristics below ～ 7 K is closely associated with the intrinsic transition ～ 5 K of FeSb2, which is, however,mediated by extrinsic current-induced Joule heating effect. The antimony crystallized in a preferred orientation within the FeSb2 lattice in the high-temperature synthesis process leaves its fingerprint in the de Haas-Van Alphen(dHvA) oscillations, and results in the regular angular dependence of the oscillating frequencies. Nevertheless, possible existence of intrinsic non-trivial states cannot be completely ruled out. Our findings call for further theoretical and experimental studies to explore novel physics on flux-free grown FeSb_2 crystals.展开更多
文摘Spontaneous Ca2+ oscillations in vascular smooth muscle cells have been modeled using a single Ca2+ pool. This report describes spontaneous Ca2+ oscillations dependent on two separate Ca2+ sources for the nuclear versus cytoplas- mic compartments. Changes in free intracellular Ca2+ were monitored with ratiometric Ca2+- fluorophores using confo- cal microscopy. On average, spontaneous oscillations developed in 79% of rat aortic smooth muscle cells that were synchronous between the cytoplasm and nucleus. Reduction of extracellular Ca2+ (< 1 μM) decreased the frequency and amplitude of the cytoplasmic oscillations with 48% of the oscillations asynchronous between the nuclear and cytoplasmic compartments. Similar results were obtained with the Ca2+ channel blockers, nimodipine and diltiazem. Arg-vasopressin (AVP) induced a rapid release of intracellular Ca2+ stores that was greater in the nuclear compartment (4.20 ± 0.23 ratio units, n = 56) than cytoplasm (2.54 ± 0.28) in cells that had spontaneously developed prior oscillations. Conversely, cells in the same conditions lacking oscillations had a greater AVP-induced Ca2+ transient in the cytoplasm (4.99 ± 0.66, n = 17) than in the nucleus (2.67 ± 0.29). Pre-treatment with Ca2+ channel blockers depressed the AVP responses in both compartments with the cytoplasmic Ca2+ most diminished. Depletion of internal Ca2+ stores prior to AVP exposure blunted the nuclear response, mimicking the response of cells that lacked prior oscillations. Spontaneous oscillating cells had a greater sarcoplasmic reticulum network than cells that did not oscillate. We propose that sponta- neous nuclear oscillations rely on perinuclear sarcoplasmic reticulum stores, while the cytoplasmic oscillations rely on Ca2+ influx.
文摘Mature eggs (at metaphase Ⅱ stage) produce a series of Ca2+ oscillation at fertilization. To define whether the fertilization-induced Ca2+ oscillation is restrict to the metaphase Ⅱ eggs and cell cycle dependent, mouse oocytes at prophase Ⅰ (arrested at germinal vesicle stage),metaphase Ⅰ, metaphase Ⅱ, as well as the pronuclear embryos at interphase of the first mitotic division derived from fertilization or parthenogenetic activation were inseminated after removal of zona pellucida. The results show that the fertilization-induced Ca2+ oscillation is not specific to metaphase Ⅱ eggs. This is supported by the fact that immature oocytes generated the Ca2+ oscillations at fertilization regardless of their nuclear progression from prophase Ⅰ to metaphase Ⅰ (in vitro matured) stage. More interestingly, it was first found that pronuclear embryos at interphase derived from parthenogenetic activation showed Ca2+ oscillations in response to fertilization while the zygotes at interphase did not after reinsemination or intracytoplasmic injection of sperm extracts which induce Ca2+ oscillations in MII eggs. This suggests that the ability of oocytes to generate Ca2+ oscillation in response to sperm penetration is not regulated in a cell cycle dependent manner but dependent on the cytoplasmic maturation.
基金the financial support from the National Key Research and Development Program of China(No.2018YFC1903403)Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001).
文摘Inhibitors are important for flotation separation of quartz and feldspar.In this study,a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp.Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments.And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation reagents and put forward the synergistic strengthening mechanism.The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca^(2+)and SS in sequence under the optimal proportion of 1:5.A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired,and was found to be 90.70wt% and 83.70%,respectively.It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from Fourier-transform infrared(FT-IR)and adsorption capacity tests.The results of X-ray photoelectron spectroscopy(XPS)indicated that Ca^(2+)directly interacts with the surface of quartz to increase the adsorption of collectors.In contrast,the chemistry property of Al on the feldspar surface was altered by combined inhibitor due to Na^(+)and Ca^(2+)taking the place of K^(+),resulting in the composite inhibitor forms a hydrophilic structure,which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site.The combination of Ca^(2+)and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector,thus achieving the effect of efficient separation.A new strategy for flotation to separate quartz from feldspar in near-neutral pulp was provided.
基金supported by the Ministry of Science and Technology of China (2005CB221401)the National Natural Science Foundation of China(20873111)the Key Science & Technology Specific Projects of Fujian Province (2009HZ10102)
文摘Oscillations in temperatures of catalyst bed as well as concentrations of gas phase species at the exit of reactor were observed during the partial oxidation of methane to synthesis gas over Ru/Al2O3 in the temperature range of 600 to 850℃. XRD, H2-TPR and in situ Raman techniques was used to characterize the catalyst. Two types of ruthenium species, i.e. the ruthenium species weakly interacted with Al2O3 and that strongly interacted with the support, were identified by H2-TPR experiment. These species are responsible for two types of oscillation profiles observed during the reaction. The oscillations were the result of these ruthenium species switching cyclically between the oxidized state and the reduced state under the reaction condition. These cyclic transformations, in turn, were the result of temperature variations caused by the varying levels of the strongly exothermic CH4 combustion and the highly endothermic CH4 reforming （with H2O and CO2） reactions （or the less exothermic direct partial oxidation of methane to CO and H2）, which were favored by the oxidized and the metallic sites, respectively. The major pathway of synthesis gas formation over the catalyst was via the combustion-reforming mechanism.
文摘In order to investigate the effects of aconitine on [Ca2＋] oscillation patterns in cultured myocytes of neonatal rats, fluorescent Ca2＋ indicator Fluo-4 NW and laser scanning confocal micro- scope （LSCM） were used to detect the real-time changes of [Ca2＋] oscillation patterns in the cultured myocytes before and after aconitine （1.0 μmol/L） incubation or antiarrhythmic peptide （AAP） and aconitine co-incubation. The results showed under control conditions, [Ca2＋] oscillations were irregu- lar but relatively stable, occasionally accompanied by small calcium sparks. After incubation of the cultures with aconitine, high frequency [Ca2＋] oscillations emerged in both nuclear and cytoplasmic regions, whereas typical calcium sparks disappeared and the average [Ca2＋] in the cytoplasm of the cardiomyocyte did not change significantly. In AAP-treated cultures, intracellular [Ca2＋] oscillation also changed, with periodic frequency, increased amplitudes and prolonged duration of calcium sparks. These patterns were not altered significantly by subsequent aconitine incubation. The basal value of [Ca2＋] in nuclear region was higher than that in the cytoplasmic region. In the presence or absence of drugs, the [Ca2＋] oscillated synchronously in both the nuclear and cytoplasmic regions of the same cardiomyocyte. It was concluded that although oscillating strenuously at high frequency, the average [Ca2＋] in the cytoplasm of cardiomyocyte did not change significantly after aconitine incuba- tion, compared to the controls. The observations indicate that aconitine induces the changes in [Ca2＋] oscillation frequency other than the Ca2＋ overload.
基金supported by Guangdong Innovative and Entrepreneurial Research Team Program,China(Grant No.2016ZT06D348)the National Natural Science Foundation of China(Grant No.11874193)+1 种基金the Shenzhen Fundamental Subject Research Program,China(Grant Nos.JCYJ20170817110751776 and JCYJ20170307105434022)The work at Brookhaven is supported by the US Department of Energy,Office of Basic Energy Sciences as part of the Computational Material Science Program(material synthesis)
文摘We present a systematical study on single crystalline FeSb2 using electrical transport and magnetic torque measurements at low temperatures. Nonlinear magnetic field dependence of Hall resistivity demonstrates a multi-carrier transport instinct of the electronic transport. Current-controlled negative differential resistance(CC-NDR) observed in currentvoltage characteristics below ～ 7 K is closely associated with the intrinsic transition ～ 5 K of FeSb2, which is, however,mediated by extrinsic current-induced Joule heating effect. The antimony crystallized in a preferred orientation within the FeSb2 lattice in the high-temperature synthesis process leaves its fingerprint in the de Haas-Van Alphen(dHvA) oscillations, and results in the regular angular dependence of the oscillating frequencies. Nevertheless, possible existence of intrinsic non-trivial states cannot be completely ruled out. Our findings call for further theoretical and experimental studies to explore novel physics on flux-free grown FeSb_2 crystals.
