Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calcula...Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calculations indicated that the Raman bands in the wavenumber region of 250–500 cm-1 are related to Mo–O bending vibrations in MoO4 tetrahedra,while the Raman bands in the wavenumber region of 650–950 cm-1 are attributed to stretching vibrations of Mo–O bonds.The temperature-dependent Raman spectra reveal that K_2 Sr（MoO_4）2 exhibits two sets of modifications in the Raman spectra at ～ 150？C and ～ 475？C, attributed to structural phase transitions. The large change of the Raman spectra in the temperature range of 150？C to 475？C suggests structural instability of the medium-temperature phase β-K_2 Sr（MoO_4）2.展开更多
FMS-like tyrosine kinase 3(FLT3)mutation is strongly associated with poor prognosis in acute myeloid leukemia(AML).Though many FLT3 inhibitors have been developed for clinical application with 34%-56%complete remissio...FMS-like tyrosine kinase 3(FLT3)mutation is strongly associated with poor prognosis in acute myeloid leukemia(AML).Though many FLT3 inhibitors have been developed for clinical application with 34%-56%complete remission rate,patients would develop resistance sooner or later after initial response to tyrosine kinase inhibitors(TKIs),such as gilteritinib.And increasing studies have shown that several resistance related mutations of FLT3 emerged during the AML progression.Thus,further investigation is warranted for these FLT3mu,AML patients to achieve a better treatment outcome.4-Hydroxyphenyl retinamide(4-HPR)has been investigated extensively in animal models and clinical trials as an anticancer/chemopreventive agent and is currently used for protection against cancer development/recurrence,with minimal side effects.In this study,we performed gene-set enrichment analysis and found that down-regulated genes induced by 4-HPR were associated with FLT3-ITD gene sets.CD34+ AML stem/progenitor cells separated from 32 AML samples were treated with 4-HPR.Correlation analysis showed that AML cells with FLT3-ITD genetic alteration were more sensitive to 4-HPR treatment than those without FLT3-ITD.Next,we treated 22 primary AML cells with 4-HPR and found that 4-HPR was more toxic to AML cells with FLT3-ITD.These results indicated that 4-HPR was preferentially cytotoxic to all FLT3-ITD AML cells irrespective of stem/progenitor cells or blast cells.4-HPR-induced reactive oxygen species(ROS)production and NF-kB inhibition might be the reason of 4-HPR selectivity on FLT3 mutated AML cells.展开更多
The insulator-metal transition triggered by pressure in charge transfer insulator NiS2 is investigated by combining high-pressure electrical transport,synchrotron x-ray diffraction and Raman spectroscopy measurements ...The insulator-metal transition triggered by pressure in charge transfer insulator NiS2 is investigated by combining high-pressure electrical transport,synchrotron x-ray diffraction and Raman spectroscopy measurements up to40-50 GPa.Upon compression,we show that the metallization firstly appears in the low temperature region at^3.2 GPa and then extends to room temperature at^8.0 GPa.During the insulator-metal transition,the bond length of S-S dimer extracted from the synchrotron x-ray diffraction increases with pressure,which is supported by the observation of abnormal red-shift of the Raman modes between 3.2 and 7.1 GPa.Considering the decreasing bonding-antibonding splitting due to the expansion of S-S dimer,the charge gap between the S-ppπ* band and the upper Hubbard band of Ni-3 d eg state is remarkabl.y decreased.These results consistently indicate that the elongated S-S dimer plays a predominant role in the insulator-metal transition under high pressure,even though the p-d hybridization is enhanced simultaneously,in accordance with a scenario of charge-gap-controlled type.展开更多
PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and ind...PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and indirect-to-direct gap transition under strain; however, these properties have not been verified experimentally. Here we report the first experimental exploration of its optoelectronic properties under external pressure. We find that the photocurrent is weakly pressuredependent below 3 GPa but increases significantly in the pressure range of 3 GPa–4 GPa, with a maximum ～ 6 times higher than that at ambient pressure. X-ray diffraction data shows that no structural phase transition can be observed up to26.8 GPa, which indicates a stable lattice structure of PtS2 under high pressure. This is further supported by our Raman measurements with an observation of linear blue-shifts of the two Raman-active modes to 6.4 GPa. The pressure-enhanced photocurrent is related to the indirect-to-direct/quasi-direct bandgap transition under pressure, resembling the gap behavior under compression strain as predicted theoretically.展开更多
The relationship between structural and electronic phase transitions in V_(2)O_(3)thin films is of critical importance for understanding of the mechanism behind metal–insulator transition(MIT)and related technologica...The relationship between structural and electronic phase transitions in V_(2)O_(3)thin films is of critical importance for understanding of the mechanism behind metal–insulator transition(MIT)and related technological applications.Despite being extensively studied,there are currently no clear consensus and picture of the relation between structural and electronic phase transitions so far.Using V_(2)O_(3)thin films grown on r-plane Al2O3 substrates,which exhibit abrupt MIT and structural phase transition,we show that the electronic phase transition occurs concurrently with the structural phase transition as revealed by the electrical transport and Raman spectra measurements.Our result provides experimental evidence for clarifying this issue,which could form the basis of theoretical studies as well as technological applications in V_(2)O_(3).展开更多
Atomically thin two-dimensional(2D) materials are the building bricks for next-generation electronics and optoelectronics, which demand plentiful functional properties in mechanics, transport, magnetism and photorespo...Atomically thin two-dimensional(2D) materials are the building bricks for next-generation electronics and optoelectronics, which demand plentiful functional properties in mechanics, transport, magnetism and photoresponse.For electronic devices, not only metals and high-performance semiconductors but also insulators and dielectric materials are highly desirable. Layered structures composed of 2D materials of different properties can be delicately designed as various useful heterojunction or homojunction devices, in which the designs on the same material(namely homojunction) are of special interest because preparation techniques can be greatly simplified and atomically seamless interfaces can be achieved. We demonstrate that the insulating pristine ZnPS_3, a ternary transition-metal phosphorus trichalcogenide, can be transformed into a highly conductive metal and an n-type semiconductor by intercalating Co and Cu atoms, respectively. The field-effect-transistor(FET) devices are prepared via an ultraviolet exposure lithography technique. The Co-ZnPS_3 device exhibits an electrical conductivity of 8 × 10^(4) S/m, which is comparable to the conductivity of graphene. The Cu-ZnPS_3 FET reveals a current ON/OFF ratio of 1-05 and a mobility of 3 × 10^(-2 )cm^(2)·V^(-1)·s^(-1). The realization of an insulator, a typical semiconductor and a metallic state in the same 2D material provides an opportunity to fabricate n-metal homojunctions and other in-plane electronic functional devices.展开更多
Main observation and conclusion An HPLC-UV-guided separation was performed and four pairs of unprecedented macathiohydantoin dimers,lepithiohydimerins A—D(1—4)bearing a rare disulfide bond were isolated from the tub...Main observation and conclusion An HPLC-UV-guided separation was performed and four pairs of unprecedented macathiohydantoin dimers,lepithiohydimerins A—D(1—4)bearing a rare disulfide bond were isolated from the tubers of Maca.Their structures were unambiguously confirmed by NMR spectroscopic,X-ray crystallographic and electronic circular dichroism(ECD)analyses.At the concentration of 20μmol/L,compounds 2-1,2-2,and 4-1 increased the viability of PC12 cells with the cell viability at(72.06±1.14)%,(72.64±1.49)%,and(70.93±1.22)%,respectively.Furthermore,the serial concentration experiment showed that they can protect PC12 cells in a dose-dependent manner.展开更多
In this paper, the dilution effects of non-magnetic Y ions on spin-ice compound Dy_2Ti_2O_7 by infrared and Raman spectra and magnetization measurements were investigated. An anomalous phonon softening with temperatur...In this paper, the dilution effects of non-magnetic Y ions on spin-ice compound Dy_2Ti_2O_7 by infrared and Raman spectra and magnetization measurements were investigated. An anomalous phonon softening with temperature decreasing is found in both the parent and diluted compounds, and Y doping can relax the softening of phonons except that of the IR mode near 233 cm^-1, indicating a strong phonon–phonon coupling in the spin-ice material.The magnetization measurements reveal that the nonmagnetic impurities do not severely influence the spin-ice rules in the ground state when the level of dilution is not very high. However, a large amount of dilution enhance the disorder and break the spin-ice state because the collective spin-flip clusters are no longer available.展开更多
Recently,laser ablation assisted spark induced breakdown spectroscopy(LA-SIBS)has been growing rapidly and continue to be extended to a broad range of materials analysis.Characterized by employ-ing a speifically desig...Recently,laser ablation assisted spark induced breakdown spectroscopy(LA-SIBS)has been growing rapidly and continue to be extended to a broad range of materials analysis.Characterized by employ-ing a speifically designed high voltage and pulse discharge cireuit to generate a spark and used to enhance plasma emission produced by laser ablation,allows direct analysis of materials without prior sample preparation.This paper reviews recent development and application of laser ablation assisted spark induced breakdown spectrosoopy for material analysis.Following a summary of fundamentals and instrumentation of the LA-SIBS analytical techmique,the development and applications of laser ablation assisted spark induced breakdown spectroscopy for the analysis of conducting materials and insulating materials is described.展开更多
基金Project supported by the Natural Science Foundation of Anhui Province,China(Grant Nos.KJ2018A0588 and KJ2017A625)
文摘Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calculations indicated that the Raman bands in the wavenumber region of 250–500 cm-1 are related to Mo–O bending vibrations in MoO4 tetrahedra,while the Raman bands in the wavenumber region of 650–950 cm-1 are attributed to stretching vibrations of Mo–O bonds.The temperature-dependent Raman spectra reveal that K_2 Sr（MoO_4）2 exhibits two sets of modifications in the Raman spectra at ～ 150？C and ～ 475？C, attributed to structural phase transitions. The large change of the Raman spectra in the temperature range of 150？C to 475？C suggests structural instability of the medium-temperature phase β-K_2 Sr（MoO_4）2.
基金This work was partially funded by the National Natural Science Foundation of China(No.81300401)St.Baldrick’s Foundation International Scholar(No.581580)+1 种基金Natural Science Foundation of Guangdong Province(No.2015A030313460)Guangzhou Women and Children’s Medical Center(No.IP-2008-001 and No.GCP-2019-006).
文摘FMS-like tyrosine kinase 3(FLT3)mutation is strongly associated with poor prognosis in acute myeloid leukemia(AML).Though many FLT3 inhibitors have been developed for clinical application with 34%-56%complete remission rate,patients would develop resistance sooner or later after initial response to tyrosine kinase inhibitors(TKIs),such as gilteritinib.And increasing studies have shown that several resistance related mutations of FLT3 emerged during the AML progression.Thus,further investigation is warranted for these FLT3mu,AML patients to achieve a better treatment outcome.4-Hydroxyphenyl retinamide(4-HPR)has been investigated extensively in animal models and clinical trials as an anticancer/chemopreventive agent and is currently used for protection against cancer development/recurrence,with minimal side effects.In this study,we performed gene-set enrichment analysis and found that down-regulated genes induced by 4-HPR were associated with FLT3-ITD gene sets.CD34+ AML stem/progenitor cells separated from 32 AML samples were treated with 4-HPR.Correlation analysis showed that AML cells with FLT3-ITD genetic alteration were more sensitive to 4-HPR treatment than those without FLT3-ITD.Next,we treated 22 primary AML cells with 4-HPR and found that 4-HPR was more toxic to AML cells with FLT3-ITD.These results indicated that 4-HPR was preferentially cytotoxic to all FLT3-ITD AML cells irrespective of stem/progenitor cells or blast cells.4-HPR-induced reactive oxygen species(ROS)production and NF-kB inhibition might be the reason of 4-HPR selectivity on FLT3 mutated AML cells.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2018YFA0305700 and2016YFA0401804the National Natural Science Foundation of China under Grant Nos 11574323,11704387,11874362,11804344,11804341,61774136,11605276 and U1632275+3 种基金the Major Program of Development Foundation of Hefei Center for Physical Science and Technology under Grant No 2018ZYFX002the Users with Excellence Project of Hefei Science Center of Chinese Academy of Sciences under Grant No 2018HSC-UE012the Natural Science Foundation of Anhui Province under Grant Nos 1808085MA06,1908085QA18 and 1708085QA19the Director’s Fund of Hefei Institutes of Physical Science of Chinese Academy of Sciences under Grant No YZJJ201621
文摘The insulator-metal transition triggered by pressure in charge transfer insulator NiS2 is investigated by combining high-pressure electrical transport,synchrotron x-ray diffraction and Raman spectroscopy measurements up to40-50 GPa.Upon compression,we show that the metallization firstly appears in the low temperature region at^3.2 GPa and then extends to room temperature at^8.0 GPa.During the insulator-metal transition,the bond length of S-S dimer extracted from the synchrotron x-ray diffraction increases with pressure,which is supported by the observation of abnormal red-shift of the Raman modes between 3.2 and 7.1 GPa.Considering the decreasing bonding-antibonding splitting due to the expansion of S-S dimer,the charge gap between the S-ppπ* band and the upper Hubbard band of Ni-3 d eg state is remarkabl.y decreased.These results consistently indicate that the elongated S-S dimer plays a predominant role in the insulator-metal transition under high pressure,even though the p-d hybridization is enhanced simultaneously,in accordance with a scenario of charge-gap-controlled type.
基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0305700 and 2016YFA0401804)the National Natural Science Foundation of China(Grant Nos.11574323,11704387,U1632275,11304321,11604340,and 61774136)+1 种基金the Natural Science Foundation of Anhui Province,China(Grant No.1708085QA19)the Director’s Fund of Hefei Institutes of Physical Science,Chinese Academy of Sciences(Grant No.YZJJ201621)
文摘PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and indirect-to-direct gap transition under strain; however, these properties have not been verified experimentally. Here we report the first experimental exploration of its optoelectronic properties under external pressure. We find that the photocurrent is weakly pressuredependent below 3 GPa but increases significantly in the pressure range of 3 GPa–4 GPa, with a maximum ～ 6 times higher than that at ambient pressure. X-ray diffraction data shows that no structural phase transition can be observed up to26.8 GPa, which indicates a stable lattice structure of PtS2 under high pressure. This is further supported by our Raman measurements with an observation of linear blue-shifts of the two Raman-active modes to 6.4 GPa. The pressure-enhanced photocurrent is related to the indirect-to-direct/quasi-direct bandgap transition under pressure, resembling the gap behavior under compression strain as predicted theoretically.
基金Supported by the National Key R&D Program of China(Grant No.2017YFA0403600)Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences Large-Scale Scientific Facility(Grant No.U1532149).
文摘The relationship between structural and electronic phase transitions in V_(2)O_(3)thin films is of critical importance for understanding of the mechanism behind metal–insulator transition(MIT)and related technological applications.Despite being extensively studied,there are currently no clear consensus and picture of the relation between structural and electronic phase transitions so far.Using V_(2)O_(3)thin films grown on r-plane Al2O3 substrates,which exhibit abrupt MIT and structural phase transition,we show that the electronic phase transition occurs concurrently with the structural phase transition as revealed by the electrical transport and Raman spectra measurements.Our result provides experimental evidence for clarifying this issue,which could form the basis of theoretical studies as well as technological applications in V_(2)O_(3).
基金Supported by the National Key Research and Development Program of China (Grant Nos.2017YFA0403600 and 2016YFA0300404)the National Natural Science Foundation of China (Grant Nos.11874363,11974356 and U1932216)the Collaborative Innovation Program of Hefei Science Center,CAS (Grant No.2019HSC-CIP002)。
文摘Atomically thin two-dimensional(2D) materials are the building bricks for next-generation electronics and optoelectronics, which demand plentiful functional properties in mechanics, transport, magnetism and photoresponse.For electronic devices, not only metals and high-performance semiconductors but also insulators and dielectric materials are highly desirable. Layered structures composed of 2D materials of different properties can be delicately designed as various useful heterojunction or homojunction devices, in which the designs on the same material(namely homojunction) are of special interest because preparation techniques can be greatly simplified and atomically seamless interfaces can be achieved. We demonstrate that the insulating pristine ZnPS_3, a ternary transition-metal phosphorus trichalcogenide, can be transformed into a highly conductive metal and an n-type semiconductor by intercalating Co and Cu atoms, respectively. The field-effect-transistor(FET) devices are prepared via an ultraviolet exposure lithography technique. The Co-ZnPS_3 device exhibits an electrical conductivity of 8 × 10^(4) S/m, which is comparable to the conductivity of graphene. The Cu-ZnPS_3 FET reveals a current ON/OFF ratio of 1-05 and a mobility of 3 × 10^(-2 )cm^(2)·V^(-1)·s^(-1). The realization of an insulator, a typical semiconductor and a metallic state in the same 2D material provides an opportunity to fabricate n-metal homojunctions and other in-plane electronic functional devices.
基金supported by grants from the National Natural Science Foundation of China(No.31872675)Fund of State Key Laboratory of Phytochemistry and Plant Resources in West China(P2020-KF02).
文摘Main observation and conclusion An HPLC-UV-guided separation was performed and four pairs of unprecedented macathiohydantoin dimers,lepithiohydimerins A—D(1—4)bearing a rare disulfide bond were isolated from the tubers of Maca.Their structures were unambiguously confirmed by NMR spectroscopic,X-ray crystallographic and electronic circular dichroism(ECD)analyses.At the concentration of 20μmol/L,compounds 2-1,2-2,and 4-1 increased the viability of PC12 cells with the cell viability at(72.06±1.14)%,(72.64±1.49)%,and(70.93±1.22)%,respectively.Furthermore,the serial concentration experiment showed that they can protect PC12 cells in a dose-dependent manner.
基金financially supported by the State Key Project of Fundamental Research of China (Nos. 2010CB923403 and 2011CBA00111)the National Natural Science Foundation of China (Nos. 11174290 and U1232142)the Hundred Talents Program of the Chinese Academy of Sciences (No. 2010A1175)
文摘In this paper, the dilution effects of non-magnetic Y ions on spin-ice compound Dy_2Ti_2O_7 by infrared and Raman spectra and magnetization measurements were investigated. An anomalous phonon softening with temperature decreasing is found in both the parent and diluted compounds, and Y doping can relax the softening of phonons except that of the IR mode near 233 cm^-1, indicating a strong phonon–phonon coupling in the spin-ice material.The magnetization measurements reveal that the nonmagnetic impurities do not severely influence the spin-ice rules in the ground state when the level of dilution is not very high. However, a large amount of dilution enhance the disorder and break the spin-ice state because the collective spin-flip clusters are no longer available.
基金the National Natural Science Foundation of China(Grant No.61975186).
文摘Recently,laser ablation assisted spark induced breakdown spectroscopy(LA-SIBS)has been growing rapidly and continue to be extended to a broad range of materials analysis.Characterized by employ-ing a speifically designed high voltage and pulse discharge cireuit to generate a spark and used to enhance plasma emission produced by laser ablation,allows direct analysis of materials without prior sample preparation.This paper reviews recent development and application of laser ablation assisted spark induced breakdown spectrosoopy for material analysis.Following a summary of fundamentals and instrumentation of the LA-SIBS analytical techmique,the development and applications of laser ablation assisted spark induced breakdown spectroscopy for the analysis of conducting materials and insulating materials is described.
