Lead-free halide double perovskites(HDPs)provide a promising platform for high-performance thermoelectric due to their intrinsically ultralow lattice thermal conductivity k_(l).In this study,we comprehensively investi...Lead-free halide double perovskites(HDPs)provide a promising platform for high-performance thermoelectric due to their intrinsically ultralow lattice thermal conductivity k_(l).In this study,we comprehensively investigate the lattice dynamics of Cs_(2)AgInCl_(6)using first-principles calculations.By explicitly incorporating four-phonon scattering and wave-like phonon tunneling,we predict a k_(l)of 0.52 W·m^(-1)·K^(-1)with a remarkably weak temperature dependence(k_(l)∝T^(-0.31)),confirming the intrinsically glass-like ultralow k_(l)in Cs_(2)AgInCl_(6).Further analyses reveal that hierarchical chemical bonds,loosely bonded rattling atoms and a mixed crystalline-liquid state collectively induce strong anharmonicity manifested in flat phonon modes.These factors dominate the glass-like thermal transport component of k_(l).This work uncovers the underlying mechanisms governing the unusual thermal transport properties in lead-free HDPs and offers guiding principles for designing novel energy conversion technologies.展开更多
Cortex Moutan (Paeonia suffruticosa Andr.) is a common traditional Chinese medicine and has been widely used in clinic for 2000 years in China. As sources for this crude drug are always mixed with other species, many ...Cortex Moutan (Paeonia suffruticosa Andr.) is a common traditional Chinese medicine and has been widely used in clinic for 2000 years in China. As sources for this crude drug are always mixed with other species, many cultivars on herbal market may lead to quality instability. Multi-component quantitative analysis is an efficient method to reflect chemical profiles of herb medicine and is always taken as the main method for quality evaluation. So, the aim of this work is to develop analytical method to quantify paeonol, paeoniflorin, gallic acid, oxypaeoniflorin, benzoylpaeoniflorin and paeonolide in Cortex Moutan (CM) to evaluate the chemical qualities of CM from different species or cultivars. Besides, we also study the intestinal absorption characteristics of paeonol and paeoniflorin for further pharmacological evaluation. In the present study, all of the standard markers were performed on an Ecosil C18 (250 mm × 4.6 mm, 5 μM, Lubex Co., Guangzhou, China) with linear gradient elution of 0.2% formic acid water and acetonitrile. The proposed method was applied to analyze 50 batches of samples with acceptable linearity (R2, 0.9995 - 0.9999), precisions (RSD, 0.47% - 2.08%), repeatability (RSD, 039% - 2.63%), stability (RSD, 0.52% - 2.45%), and recovery (RSD, 0.72% - 3.03%) of the six compounds. Furthermore, the Hierarchical Cluster Analysis was applied to classify the 50 samples based on contents of the six compound markers. The results obtained from multi-component quantification of CM clearly indicated that CM originated from P. suffruticosa and P. ostii presented different chemical properties, and that samples from the two materials could be gathered into one branch, respectively, while CM sourced from cultivars of P. suffruticosa showed great variety on chemical quality. The results from Hierarchical Cluster Analysis implied that the established method could be used as a powerful tool for the quality evaluation of CM. The intestinal absorption study indicated that the intestinal absorption activities for paeoniflorin and paeonol showed an increasing absorption with time. Paeonol had lower absorption rate (6.69% - 15.93%) than that of paeoniflorin (19.0% - 30.70%). As a result, the established method is suitable for the quality evaluation of CM. The results of intestinal absorption characteristics of paeonol and paeoniflorin offer an insight for pharmacological evaluation and clinical efficacy research of CM.展开更多
We investigate the negative transconductance effect in p-GaN gate AlGaN/GaN high-electron-mobility transistor(HEMT) associated with traps in the unintentionally doped GaN buffer layer. We find that a negative transcon...We investigate the negative transconductance effect in p-GaN gate AlGaN/GaN high-electron-mobility transistor(HEMT) associated with traps in the unintentionally doped GaN buffer layer. We find that a negative transconductance effect occurs with increasing the trap concentration and capture cross section when calculating transfer characteristics.The electron tunneling through AlGaN barrier and the reduced electric field discrepancy between drain side and gate side induced by traps are reasonably explained by analyzing the band diagrams, output characteristics, and the electric field strength of the channel of the devices under different trap concentrations and capture cross sections.展开更多
The optical polarization characteristics of surface plasmon(SP)coupled Al Ga N-based light emitting diodes(LEDs)are investigated theoretically by analyzing the radiation recombination process and scattering process re...The optical polarization characteristics of surface plasmon(SP)coupled Al Ga N-based light emitting diodes(LEDs)are investigated theoretically by analyzing the radiation recombination process and scattering process respectively.For the Al_(0.5)Ga_(0.5)N/Al/Al_(2)O_(3)slab structure,the relative intensity of TE-polarized and TM-polarized spontaneous emission(SE)rate into the SP mode obviously depends on the thickness of the Al layer.The calculation results show that TM dominated emission will be transformed into TE dominated emission with the decrease of the Al thickness,while the emission intensities of both TE/TM polarizations will decrease significantly.In addition,compared with TM polarized emission,TE polarized emission is easier to be extracted by SP coupling.For the Al_(0.5)Ga_(0.5)N/Al nano-particle structure,the ratio of transmittance for TE/TM polarized emission can reach~3.06,while for the Al free structure,it is only 1.2.Thus,the degree of polarization of SP coupled LED can be improved by the reasonable structural design.展开更多
The optical properties of AlGaN-based quantum well(QW)structure with two coupled thin well layers are investigated by the six-by-six K-P method.Compared with the conventional structure,the new structure,especially the...The optical properties of AlGaN-based quantum well(QW)structure with two coupled thin well layers are investigated by the six-by-six K-P method.Compared with the conventional structure,the new structure,especially the one with lower Al-content in the barrier layer,can enhance the TE-/TM-polarized total spontaneous emission rate due to the strong quantum confinement and wide recombination region.For the conventional QW structure,the reduction of well thickness can lead the degree of polarization(DOP)to decrease and the internal quantum efficiency(IQE)to increase.By using the coupled thin well layers,the DOP for the structure with high Al-content in the barrier layer can be improved,while the DOP will further decrease with low Al-content in the barrier layer.It can be attributed to the band adjustment induced by the combination of barrier height and well layer coupling.The IQE can also be further enhanced to 14.8%-20.5%for various Al-content of barrier layer at J=100 A/cm^(2).In addition,the efficiency droop effect can be expected to be suppressed compared with the conventional structure.展开更多
Eight 16,17-pyrazo-annulated steroidal derivatives were synthesized and evaluated in vitro vascular endothelial growth factor （VEGF） inhibitory activity with 2-methoxyestradiol （2-ME） as the reference compound. Mo...Eight 16,17-pyrazo-annulated steroidal derivatives were synthesized and evaluated in vitro vascular endothelial growth factor （VEGF） inhibitory activity with 2-methoxyestradiol （2-ME） as the reference compound. Most of the compounds showed potent VEGF inhibitory activity with ECs0 values of micromolar or submicromolar range. Among them, the compounds 3 and 8 exhibited similar EC50 values and obviously better TI values compared with 2-ME.展开更多
The efficacy of chemotherapy is thought to be direct killing of tumor cells, but documented studies have been shown that immunity plays a role in its effectiveness. In a pilot study to observe the bone marrow suppress...The efficacy of chemotherapy is thought to be direct killing of tumor cells, but documented studies have been shown that immunity plays a role in its effectiveness. In a pilot study to observe the bone marrow suppression and regeneration in tumor bearing mice induced by single dose injection of 5-fluorouracil (5-FU), we unexpectedly found that tumors grew fast as bone marrow mononuclear cells (BMC) and peripheral white blood cells (PWBC) were decreased quickly during myelosuppression meanwhile significantly slow as repopulating of BMC and PWBC during bone marrow regeneration after 5-FU treatment, no matter whether in low or high dose administration, but the higher the dose was, the lower of the nadir of BMC and PWBC were reached to, as well as the much more powerful duration and strength of the repopulated BMC and PWBC, suggested that the immunity might be a predominant drive in 5-FU chemotherapy. Due to the fact that BMC is the source of PWBC which is its final maturational and functional form, it could be proposed that the anti-proliferative effect of 5-FU on tumor is highly associated with the renewal of PWBC.展开更多
Left ventricular noncompaction(LVNC)is a heterogeneous disorder with undlear genetic causes and an unknown mechanism.elF3a,an important member of the Eukaryotic translation initiation factor 3(elF3)family,is involved ...Left ventricular noncompaction(LVNC)is a heterogeneous disorder with undlear genetic causes and an unknown mechanism.elF3a,an important member of the Eukaryotic translation initiation factor 3(elF3)family,is involved in multiple biological processes,indluding cell prolif eration and migration during myocardial development,suggesting it could play a role in LVNC development.To investigate the association between a novel variant(C.1145 A->G)in elF3a and LVNC,and explore potential mechanisms that could lead to the development of LVNC.A novel elF3a variant,C.1145 A->G,was identified by whole-exome sequencing in a familial pedigree with LVNC.Adenovirus vectors containing wild-type elF 3a and the mutated version were constructed and co-infected into H9C2 cells.Cell proliferation,apoptosis,cell migration,and differentiation,as well as phosphorylation of ERK1/2 were stud-ied and were measured by proliferation assays,flow cytometry,real-time PCR and Westem blot,respectively.The elF3a mutation inhibited the proliferation of H9C2 cells,induced apoptosis,promoted cell migration,and inhibited the dif ferentiation of human induced plurip-otent stem cell-derived cardiomyocytes(hiPSC-CMs).The effect of the elF3a mutation may be attributed to a decrease in expression of p-ERK1/2.A novel elF3a gene mutation disrupted the p-ERK1/2 pathway and caused decreased myocardium proliferation,differentiation,acceler-ated migration.This finding may provide some insight into the mechanism involved in LVNC development.展开更多
Pristinamycin,produced by Streptomyces pristinaespiralis,which is a streptogramin-like antibiotic consisting of two chemically unrelated components:pristinamycin I(PI)and pristinamycin II(PII),shows potent activity ag...Pristinamycin,produced by Streptomyces pristinaespiralis,which is a streptogramin-like antibiotic consisting of two chemically unrelated components:pristinamycin I(PI)and pristinamycin II(PII),shows potent activity against many antibiotic-resistant pathogens.However,so far pristinamycin production titers are still quite low,particularly those of PI.In this study,we constructed a PI single component producing strain by deleting the PII biosynthetic genes(snaE1 and snaE2).Then,two metabolic engineering approaches,including deletion of the repressor gene papR3 and chromosomal integration of an extra copy of the PI biosynthetic gene cluster(BGC),were employed to improve PI production.The final engineered strain DPIIDpapR3/PI produced a maximum PI level of 132 mg/L,with an approximately 2.4-fold higher than that of the parental strain S.pristinaespiralis HCCB10218.Considering that the PI biosynthetic genes are clustered in two main regions in the 210 kb“supercluster”containing the PI and PII biosynthetic genes as well as a cryptic polyketide BGC,these two regions were cloned separately and then were successfully assembled into the PI BGC by the transformation-associated recombination(TAR)system.Collectively,the metabolic engineering approaches employed is very efficient for strain improvement in order to enhance PI titer.展开更多
Van der Waals(vdW)heterostructures composed of different two-dimensional(2D)materials offer an easily accessible way to combine properties of individual materials for applications.Owing to the discovery of a set of un...Van der Waals(vdW)heterostructures composed of different two-dimensional(2D)materials offer an easily accessible way to combine properties of individual materials for applications.Owing to the discovery of a set of unanticipated physical phenomena,the twisted 2D vdW heterostructures have gained considerable attention recently.Here,we report enhanced valley splitting in twisted 2D vdW WSe_(2)/CrI_(3)heterostructures.In particular,the splitting can be 1200%(or 5.18 meV)of the value for a non-twisted heterostructure.According to the k·p model,this value is equivalent to a~20 T external magnetic field applied perpendicular to the 2D sheet.The thermodynamic stability of 2D vdW WSe_(2)/CrI_(3)heterostructures,on the other hand,depends linearly on the interlayer twisting angle.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12204482),the Natural Science Foundation of Shanxi Province(Grant No.202403021221164)Higher education teaching reform and innovation project of Shanxi Province(Grant No.J20220480)the Natural Science Foundation of Hainan Province(Grant Nos.525MS080 and 225MS076).
文摘Lead-free halide double perovskites(HDPs)provide a promising platform for high-performance thermoelectric due to their intrinsically ultralow lattice thermal conductivity k_(l).In this study,we comprehensively investigate the lattice dynamics of Cs_(2)AgInCl_(6)using first-principles calculations.By explicitly incorporating four-phonon scattering and wave-like phonon tunneling,we predict a k_(l)of 0.52 W·m^(-1)·K^(-1)with a remarkably weak temperature dependence(k_(l)∝T^(-0.31)),confirming the intrinsically glass-like ultralow k_(l)in Cs_(2)AgInCl_(6).Further analyses reveal that hierarchical chemical bonds,loosely bonded rattling atoms and a mixed crystalline-liquid state collectively induce strong anharmonicity manifested in flat phonon modes.These factors dominate the glass-like thermal transport component of k_(l).This work uncovers the underlying mechanisms governing the unusual thermal transport properties in lead-free HDPs and offers guiding principles for designing novel energy conversion technologies.
文摘Cortex Moutan (Paeonia suffruticosa Andr.) is a common traditional Chinese medicine and has been widely used in clinic for 2000 years in China. As sources for this crude drug are always mixed with other species, many cultivars on herbal market may lead to quality instability. Multi-component quantitative analysis is an efficient method to reflect chemical profiles of herb medicine and is always taken as the main method for quality evaluation. So, the aim of this work is to develop analytical method to quantify paeonol, paeoniflorin, gallic acid, oxypaeoniflorin, benzoylpaeoniflorin and paeonolide in Cortex Moutan (CM) to evaluate the chemical qualities of CM from different species or cultivars. Besides, we also study the intestinal absorption characteristics of paeonol and paeoniflorin for further pharmacological evaluation. In the present study, all of the standard markers were performed on an Ecosil C18 (250 mm × 4.6 mm, 5 μM, Lubex Co., Guangzhou, China) with linear gradient elution of 0.2% formic acid water and acetonitrile. The proposed method was applied to analyze 50 batches of samples with acceptable linearity (R2, 0.9995 - 0.9999), precisions (RSD, 0.47% - 2.08%), repeatability (RSD, 039% - 2.63%), stability (RSD, 0.52% - 2.45%), and recovery (RSD, 0.72% - 3.03%) of the six compounds. Furthermore, the Hierarchical Cluster Analysis was applied to classify the 50 samples based on contents of the six compound markers. The results obtained from multi-component quantification of CM clearly indicated that CM originated from P. suffruticosa and P. ostii presented different chemical properties, and that samples from the two materials could be gathered into one branch, respectively, while CM sourced from cultivars of P. suffruticosa showed great variety on chemical quality. The results from Hierarchical Cluster Analysis implied that the established method could be used as a powerful tool for the quality evaluation of CM. The intestinal absorption study indicated that the intestinal absorption activities for paeoniflorin and paeonol showed an increasing absorption with time. Paeonol had lower absorption rate (6.69% - 15.93%) than that of paeoniflorin (19.0% - 30.70%). As a result, the established method is suitable for the quality evaluation of CM. The results of intestinal absorption characteristics of paeonol and paeoniflorin offer an insight for pharmacological evaluation and clinical efficacy research of CM.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFB0402900)the National Natural Science Foundation of China(Grant No.61634002)+1 种基金the Scientific Research Foundation of Graduate School of Nanjing University,China(Grant No.2016CL03)the Key Project of Jiangsu Province,China(Grant No.BE2016174)
文摘We investigate the negative transconductance effect in p-GaN gate AlGaN/GaN high-electron-mobility transistor(HEMT) associated with traps in the unintentionally doped GaN buffer layer. We find that a negative transconductance effect occurs with increasing the trap concentration and capture cross section when calculating transfer characteristics.The electron tunneling through AlGaN barrier and the reduced electric field discrepancy between drain side and gate side induced by traps are reasonably explained by analyzing the band diagrams, output characteristics, and the electric field strength of the channel of the devices under different trap concentrations and capture cross sections.
基金the National Nature Science Foundation of China(Grant Nos.62004109,61874168,and 62074086)Jiangsu Provincial Double-Innovation Doctor Program,Development of antibacterial multifunctional PVC facing new material technology(Grant No.21ZH626)。
文摘The optical polarization characteristics of surface plasmon(SP)coupled Al Ga N-based light emitting diodes(LEDs)are investigated theoretically by analyzing the radiation recombination process and scattering process respectively.For the Al_(0.5)Ga_(0.5)N/Al/Al_(2)O_(3)slab structure,the relative intensity of TE-polarized and TM-polarized spontaneous emission(SE)rate into the SP mode obviously depends on the thickness of the Al layer.The calculation results show that TM dominated emission will be transformed into TE dominated emission with the decrease of the Al thickness,while the emission intensities of both TE/TM polarizations will decrease significantly.In addition,compared with TM polarized emission,TE polarized emission is easier to be extracted by SP coupling.For the Al_(0.5)Ga_(0.5)N/Al nano-particle structure,the ratio of transmittance for TE/TM polarized emission can reach~3.06,while for the Al free structure,it is only 1.2.Thus,the degree of polarization of SP coupled LED can be improved by the reasonable structural design.
基金Project supported by the National Natural Science Foundation of China(Grant No.61874168)the Jiangsu Province I-U-R Cooperation Project,China(Grant No.BY2019114)the Nantong Science and Technology Project,China(Grant No.JC2019006)。
文摘The optical properties of AlGaN-based quantum well(QW)structure with two coupled thin well layers are investigated by the six-by-six K-P method.Compared with the conventional structure,the new structure,especially the one with lower Al-content in the barrier layer,can enhance the TE-/TM-polarized total spontaneous emission rate due to the strong quantum confinement and wide recombination region.For the conventional QW structure,the reduction of well thickness can lead the degree of polarization(DOP)to decrease and the internal quantum efficiency(IQE)to increase.By using the coupled thin well layers,the DOP for the structure with high Al-content in the barrier layer can be improved,while the DOP will further decrease with low Al-content in the barrier layer.It can be attributed to the band adjustment induced by the combination of barrier height and well layer coupling.The IQE can also be further enhanced to 14.8%-20.5%for various Al-content of barrier layer at J=100 A/cm^(2).In addition,the efficiency droop effect can be expected to be suppressed compared with the conventional structure.
基金supported by grants from the National Natural Science Foundation of China awarded to P.Xia (No.20272010) and Y.Chen(No.30200348 and 30873164)the National Drug Innovative Program(No.2009ZX09301-011) for partial support
文摘Eight 16,17-pyrazo-annulated steroidal derivatives were synthesized and evaluated in vitro vascular endothelial growth factor （VEGF） inhibitory activity with 2-methoxyestradiol （2-ME） as the reference compound. Most of the compounds showed potent VEGF inhibitory activity with ECs0 values of micromolar or submicromolar range. Among them, the compounds 3 and 8 exhibited similar EC50 values and obviously better TI values compared with 2-ME.
文摘The efficacy of chemotherapy is thought to be direct killing of tumor cells, but documented studies have been shown that immunity plays a role in its effectiveness. In a pilot study to observe the bone marrow suppression and regeneration in tumor bearing mice induced by single dose injection of 5-fluorouracil (5-FU), we unexpectedly found that tumors grew fast as bone marrow mononuclear cells (BMC) and peripheral white blood cells (PWBC) were decreased quickly during myelosuppression meanwhile significantly slow as repopulating of BMC and PWBC during bone marrow regeneration after 5-FU treatment, no matter whether in low or high dose administration, but the higher the dose was, the lower of the nadir of BMC and PWBC were reached to, as well as the much more powerful duration and strength of the repopulated BMC and PWBC, suggested that the immunity might be a predominant drive in 5-FU chemotherapy. Due to the fact that BMC is the source of PWBC which is its final maturational and functional form, it could be proposed that the anti-proliferative effect of 5-FU on tumor is highly associated with the renewal of PWBC.
基金This work was supported by the National Natural Science Foundation of China[grant number:81570218].
文摘Left ventricular noncompaction(LVNC)is a heterogeneous disorder with undlear genetic causes and an unknown mechanism.elF3a,an important member of the Eukaryotic translation initiation factor 3(elF3)family,is involved in multiple biological processes,indluding cell prolif eration and migration during myocardial development,suggesting it could play a role in LVNC development.To investigate the association between a novel variant(C.1145 A->G)in elF3a and LVNC,and explore potential mechanisms that could lead to the development of LVNC.A novel elF3a variant,C.1145 A->G,was identified by whole-exome sequencing in a familial pedigree with LVNC.Adenovirus vectors containing wild-type elF 3a and the mutated version were constructed and co-infected into H9C2 cells.Cell proliferation,apoptosis,cell migration,and differentiation,as well as phosphorylation of ERK1/2 were stud-ied and were measured by proliferation assays,flow cytometry,real-time PCR and Westem blot,respectively.The elF3a mutation inhibited the proliferation of H9C2 cells,induced apoptosis,promoted cell migration,and inhibited the dif ferentiation of human induced plurip-otent stem cell-derived cardiomyocytes(hiPSC-CMs).The effect of the elF3a mutation may be attributed to a decrease in expression of p-ERK1/2.A novel elF3a gene mutation disrupted the p-ERK1/2 pathway and caused decreased myocardium proliferation,differentiation,acceler-ated migration.This finding may provide some insight into the mechanism involved in LVNC development.
基金This work was sponsored by the National Natural Science Foundation of China(31430004,31421061,31630003,31370081 and 31570072)the Science and Technology Commission of Shanghai Municipality(16490712100).
文摘Pristinamycin,produced by Streptomyces pristinaespiralis,which is a streptogramin-like antibiotic consisting of two chemically unrelated components:pristinamycin I(PI)and pristinamycin II(PII),shows potent activity against many antibiotic-resistant pathogens.However,so far pristinamycin production titers are still quite low,particularly those of PI.In this study,we constructed a PI single component producing strain by deleting the PII biosynthetic genes(snaE1 and snaE2).Then,two metabolic engineering approaches,including deletion of the repressor gene papR3 and chromosomal integration of an extra copy of the PI biosynthetic gene cluster(BGC),were employed to improve PI production.The final engineered strain DPIIDpapR3/PI produced a maximum PI level of 132 mg/L,with an approximately 2.4-fold higher than that of the parental strain S.pristinaespiralis HCCB10218.Considering that the PI biosynthetic genes are clustered in two main regions in the 210 kb“supercluster”containing the PI and PII biosynthetic genes as well as a cryptic polyketide BGC,these two regions were cloned separately and then were successfully assembled into the PI BGC by the transformation-associated recombination(TAR)system.Collectively,the metabolic engineering approaches employed is very efficient for strain improvement in order to enhance PI titer.
基金Work in China was supported by the National Natural Science Foundation of China(12074235)S.Z.acknowledges the support by the U.S.Department of Energy(DOE)under Grant no.DESC0002623C.S.also acknowledges support by the open research fund program of the state key laboratory of low dimensional quantum physics(KF202103).
文摘Van der Waals(vdW)heterostructures composed of different two-dimensional(2D)materials offer an easily accessible way to combine properties of individual materials for applications.Owing to the discovery of a set of unanticipated physical phenomena,the twisted 2D vdW heterostructures have gained considerable attention recently.Here,we report enhanced valley splitting in twisted 2D vdW WSe_(2)/CrI_(3)heterostructures.In particular,the splitting can be 1200%(or 5.18 meV)of the value for a non-twisted heterostructure.According to the k·p model,this value is equivalent to a~20 T external magnetic field applied perpendicular to the 2D sheet.The thermodynamic stability of 2D vdW WSe_(2)/CrI_(3)heterostructures,on the other hand,depends linearly on the interlayer twisting angle.
