We demonstrate the transmission of a microwave frequency signal at 10 GHz over a 112-km urban fiber link based on a novel simple-architecture electronic phase compensation system.The key element of the system is the l...We demonstrate the transmission of a microwave frequency signal at 10 GHz over a 112-km urban fiber link based on a novel simple-architecture electronic phase compensation system.The key element of the system is the low noise frequency divider by 4 to differentiate the frequency of the forward signal from that of the backward one,thus suppressing the effect of Brillouin backscattering and parasitic reflection along the link.In terms of overlapping Allan deviation,the frequency transfer instability of 4.2×10-15 at 1-s integration time and 1.6×10-18 at one-day integration time was achieved.In addition,its sensitivity to the polarization mode dispersion in fiber is analyzed by comparing the results with and without laser polarization scrambling.Generally,with simplicity and robustness,the system can offer great potentials in constructing cascaded frequency transfer system and facilitate the building of fiber-based microwave transfer network.展开更多
We demonstrate the ultra-stable frequency sources aiming to improve the short-time instability of primary frequency standards.These sources are realized by using photonic generation approach,and composed of ultra-stab...We demonstrate the ultra-stable frequency sources aiming to improve the short-time instability of primary frequency standards.These sources are realized by using photonic generation approach,and composed of ultra-stable lasers,optical-frequency-combs,optical signal detecting parts,and synthesizers.Preliminary evaluation shows that the sources produce fixed-frequency at 9.54(/9.63)GHz,10 MHz,and tunable-frequency around 9.192 GHz with relative frequency instability of 10^(-15) for short terms.展开更多
The CaLaGa3O7:Eu3+ phosphor was prepared by a chemical co-precipitation method. Field emission scanning electron microscopy (FE-SEM), laser particle size analysis, X-ray diffraction (XRD), photoluminescence (PL...The CaLaGa3O7:Eu3+ phosphor was prepared by a chemical co-precipitation method. Field emission scanning electron microscopy (FE-SEM), laser particle size analysis, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence (CL) spectra were util- ized to characterize the synthesized phosphor. The results revealed that the phosphor was composed of microspheres with a slight agglomerate phenomenon and was spherically shaped. The average grain size was about 1.0 μm. Eu3+ ions, as luminescent centers, substituted La3+ ions into the single crystal lattice of CaLaGa307 with the sites of Cs. Although the CL spectrum was greatly different from the PL spectrum, it had the strongest red emission corresponding to the 5D0→7F2 transition of Eu3+. Under the excitation of UV light (287 nm) and electron beams (1.0-7.0 kV), the chromaticity coordinates of the phosphor were found to be in the nearly red and orange light regions, respec- tively.展开更多
In this paper, we demonstrate the residual phase noise of a few microwave frequency dividers which usually limit the performance of frequency synthesizers. In order to compare these dividers under different operation ...In this paper, we demonstrate the residual phase noise of a few microwave frequency dividers which usually limit the performance of frequency synthesizers. In order to compare these dividers under different operation frequencies, we calculate additional time jitters of these dividers by using the measured phase noise. The time jitters are various from -0.1 fs to 43 fs in a bandwidth from 1 Hz to 100 Hz in dependent of models and operation frequencies. The HMC series frequency dividers exhibit outstanding performance for high operation frequencies, and the time jitters can be sub-fs. The time jitters of SP8401, MC10EP139, and MC100LVEL34 are comparable or even below that of HMC series for low operation frequencies.展开更多
Objective: To systematically evaluate the clinical efficacy and safety of Masquelet technology and Llizarov group technology in the treatment of infectious bone defects by meta-analysis. Methods: The computer searched...Objective: To systematically evaluate the clinical efficacy and safety of Masquelet technology and Llizarov group technology in the treatment of infectious bone defects by meta-analysis. Methods: The computer searched China Knowledge Network (CNKI), Wanfang, VIP, Chinese Biomedical Literature Database (CBM), Pubmed, Medline, Cochrane Llibrary databases. The retrieval time was from the time of the establishment of the database to January 2020. According to the inclusion and exclusion criteria, randomized controlled trials on the treatment of infectious bone defects using Masquelet technology and Llizarov technology were collected, and the retrieved literature was independently screened, evaluated, and data extracted by two researchers, and then RevMan5.3 software was used so for meta-analysis. Results: A total of 10 RCT documents were included, with a total of 496 patients, including 242 in the Masquelet group and 254 in the Llizarov group. The results of the meta-analysis showed that: in terms of bone defect healing time, total weight bearing time, treatment cost, and complication rate, the Masquelet group was significantly different from the Llizarov group, and the Masquelet group was better than the Llizarov group (P <0.05);In terms of knee joint Lowa score and SF-36 score, Masquelet group has significant differences compared with Llizarov group, Llizarov group is better than Masquelet group (P <0.05);in excellent rate, number of operations, ankle Lowa score, infection control rate In terms of excellent rate of affected limb function, there was no significant difference between Masquelet group and Llizarov group (P> 0.05). Conclusion:Compared with Llizarov technology, Masquelet technology has obvious advantages in the treatment of infectious bone defects in terms of bone defect healing time, total weight-bearing time, treatment cost, and complication rate. In terms of scoring, it has advantages over Masquelet technology, but in terms of excellent treatment rate, number of operations, and ankle lowa score. In terms of infection control rate and excellent function of affected limbs, there was no significant difference between Masquelet technology and Llizarov technology,However, due to the low quality of the included studies and the small sample size, the exact efficacy still needs to be confirmed by higher quality RCT studies.展开更多
Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based composites.Inert ceramic nanoparticles are good ...Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based composites.Inert ceramic nanoparticles are good candidates for achieving this goal.In this study,we designed and prepared a series of p-type Bi_(0.5)Sb_(1.5)Te_(3)nanocomposites decorated with Y_(2)O_(3)ceramic nanoparticles via ball-milling dispersion and spark-plasma sintering.Owing to the chemical stability of the ceramics,no traces of atomic doping or interfacial reactions were observed.Transport measurements revealed that the Y_(2)O_(3)nanoparticles distributed along the grain boundaries acted as energy-dependent carrier-filtering centers to improve the scattering parameter and Seebeck coefficient,contributing to the elevated power factor even with a decreased electrical conductivity.Moreover,the incorporated Y_(2)O_(3)nanoparticles and various defect structures they induced effectively strengthened the phonon scattering and suppressed the lattice thermal conductivity.Consequently,a peak figure of merit(ZT)of 1.23 at 313 K was achieved for 0.4%Y_(2)O_(3)/Bi_(0.5)Sb_(1.5)Te_(3),which is 13%higher than that of the matrix.In addition,the Vickers hardness of the composite material was 35%higher than that of the matrix.This study demonstrates the effectiveness of ceramic nanoparticles in synergistic ally improving the thermoelectric and mechanical properties,which may be further extended to other thermoelectric systems.展开更多
The binary skutterudite CoSb_(3) is a narrow bandgap semiconductor thermoelectric(TE)material with a relatively flat band structure and excellent electrical performance.However,thermal conductivity is very high becaus...The binary skutterudite CoSb_(3) is a narrow bandgap semiconductor thermoelectric(TE)material with a relatively flat band structure and excellent electrical performance.However,thermal conductivity is very high because of the covalent bond between Co and Sb,resulting in a very low ZT value.Therefore,researchers have been trying to reduce its thermal conductivity by the different optimization methods.In addition,the synergistic optimization of the electrical and thermal transport parameters is also a key to improve the ZT value of CoSb_(3) material because the electrical and thermal transport parameters of TE materials are closely related to each other by the band structure and scattering mechanism.This review summarizes the main research progress in recent years to reduce the thermal conductivity of CoSb_(3)-based materials at atomic-molecular scale and nano-mesoscopic scale.We also provide a simple summary of achievements made in recent studies on the non-equilibrium preparation technologies of CoSb_(3)-based materials and synergistic optimization of the electrical and thermal transport parameters.In addition,the research progress of CoSb_(3)-based TE devices in recent years is also briefly discussed.展开更多
Permafrost degradation has been widely reported on the Tibetan Plateau(TP).However,directly observed evidence of permafrost thawing processes and degradation rates are very limited,although it is expected to be preval...Permafrost degradation has been widely reported on the Tibetan Plateau(TP).However,directly observed evidence of permafrost thawing processes and degradation rates are very limited,although it is expected to be prevalent near the periphery of a permafrost area.Here,we report permafrost changes and disappearance in the Qilian Mountains(northeastern TP)based on three boreholes instrumented along a 100 m transect during 2014–2021.Our results show that permafrost has significantly degraded in the study area:the mean downward thawing rate from the permafrost table was about 0.16 m per year while the mean upward thawing rate from the permafrost base was about 0.23 m per year.We estimate the mean lateral degradation rate of permafrost in this area was∼4.14 m per year.More dramatically,the 1.5 m thick permafrost layer at one of the boreholes thawed completely between April of 2018 and December of 2019.Our results indicate that changes in climatic condition may have played only a limited role in controlling the active layer thickness in the vicinity of the altitudinal limit of permafrost;moisture content and soil conditions play key roles in site-specific permafrost thawing.This study provides new quantitative insights for understanding changes near the altitudinal limit of permafrost,and we suggest that land surface models or Earth system model studies of the lateral heat exchanges should be implemented in order to better represent permafrost thawing processes.展开更多
Uncaria rhynchophylla has been widely used to treat central nervous system diseases for a long history.After investigation of U.rhynchophylla,eleven monoterpene indole alkaloids,including four new compounds uncarialin...Uncaria rhynchophylla has been widely used to treat central nervous system diseases for a long history.After investigation of U.rhynchophylla,eleven monoterpene indole alkaloids,including four new compounds uncarialins J-M(1-4)and seven known analogues(5-11),were isolated and identified.Their structural characterization was conducted using HRESIMS,1D and 2D NMR,electronic circular dichroism(ECD)spectra,and quantum chemical computations.Compounds 1,2,7,and 9-11 displayed significant ag-onistic effects towards 5-HT_(1A) receptor,and their EC_(50) values were 7.86,732,2.24,1.18,1.52,and 3.75μmol/L,respectively.Furthermore,in vivo experimental results fully revealed that hirsuteine(7)displayed a significant antidepression effect in unpredictable chronic mild stress(UCMS)-induced depression mice mainly via regulating 5-HT_(1A) signaling pathway.Molecular docking and site-directed amino acid mutation verified that amino acid residues Aspll6 and Asn386 were the binding sites of hirsuteine(7)with 5-HT_(1A) receptor.In addition,pre-treatment of mice with WAY 100635 also blocked the anti-depression effect of hirsuteine(7),which further demonstrated that 5-HT_(1A) receptor was a potential target of hirsuteine(7)to effectively treat depression.These findings indicated the therapeutic material basis of U.rhynchophylla and the anti-depression underlying mechanism of hirsuteine(7),and further provided the useful guidance for the development of hirsuteine(7)as a potential antidepressant candidate.展开更多
The investigation of Morinda officinalis led to the isolation of twelve compounds(1-12),including three new iridoid glycosides morindallns A-C(1-3)and nine known compounds(4-12).Their structural identifications were c...The investigation of Morinda officinalis led to the isolation of twelve compounds(1-12),including three new iridoid glycosides morindallns A-C(1-3)and nine known compounds(4-12).Their structural identifications were conducted using HRMS,1D and 2D NMR,and electronic circular dichroism(ECD)spectra as well as quantum chemical computations.Compound 6 displayed the most significantly agonistic activity against farnesoid X receptor(FXR)with an EC_(50) value of 7.18 μM,and its agonistic effect was verified through the investigation of FXR downstream target genes including small heterodimer partner 1(SHP1),bile salt export pump(BSEP),and organic solute transporter subunit alpha and beta(OSTα and OSTβ).The potential interaction of compound 6 with FXR was analyzed by molecular docking and molecular dynamics stimulation,revealing that amino acid residues Leu287;Thr288,and Ser332 played a crucial role in the activation of compound 6 towards FXR.These findings suggested that compound 6 could be regarded as a potential candidate for the development of FXR agonists.展开更多
基金National Natural Science Foundation of China(Grant Nos.61825505,91536217,and 61127901).
文摘We demonstrate the transmission of a microwave frequency signal at 10 GHz over a 112-km urban fiber link based on a novel simple-architecture electronic phase compensation system.The key element of the system is the low noise frequency divider by 4 to differentiate the frequency of the forward signal from that of the backward one,thus suppressing the effect of Brillouin backscattering and parasitic reflection along the link.In terms of overlapping Allan deviation,the frequency transfer instability of 4.2×10-15 at 1-s integration time and 1.6×10-18 at one-day integration time was achieved.In addition,its sensitivity to the polarization mode dispersion in fiber is analyzed by comparing the results with and without laser polarization scrambling.Generally,with simplicity and robustness,the system can offer great potentials in constructing cascaded frequency transfer system and facilitate the building of fiber-based microwave transfer network.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91536217,61127901,and 11775253)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2015334)The authors would like to thank special funds for scientific equipment development(YZ201518)from Chinese academy of sciences for the use of the developed equipment
文摘We demonstrate the ultra-stable frequency sources aiming to improve the short-time instability of primary frequency standards.These sources are realized by using photonic generation approach,and composed of ultra-stable lasers,optical-frequency-combs,optical signal detecting parts,and synthesizers.Preliminary evaluation shows that the sources produce fixed-frequency at 9.54(/9.63)GHz,10 MHz,and tunable-frequency around 9.192 GHz with relative frequency instability of 10^(-15) for short terms.
基金financially supported by the Natural Science Foundation Committee of Inner Mongolia (No.20080404MS0204)the "111 Talents Project" Foundation of Inner Mongolia,Chinathe Innovation Fund of Inner Mongolia University of Science and Technology (No.2010NC026)
文摘The CaLaGa3O7:Eu3+ phosphor was prepared by a chemical co-precipitation method. Field emission scanning electron microscopy (FE-SEM), laser particle size analysis, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence (CL) spectra were util- ized to characterize the synthesized phosphor. The results revealed that the phosphor was composed of microspheres with a slight agglomerate phenomenon and was spherically shaped. The average grain size was about 1.0 μm. Eu3+ ions, as luminescent centers, substituted La3+ ions into the single crystal lattice of CaLaGa307 with the sites of Cs. Although the CL spectrum was greatly different from the PL spectrum, it had the strongest red emission corresponding to the 5D0→7F2 transition of Eu3+. Under the excitation of UV light (287 nm) and electron beams (1.0-7.0 kV), the chromaticity coordinates of the phosphor were found to be in the nearly red and orange light regions, respec- tively.
基金supported by the National Natural Science Foundation of China under Grant No.91336101 and No.61127901the West Light Foundation of the Chinese Academy of Sciences under Grant No.2013ZD02
文摘In this paper, we demonstrate the residual phase noise of a few microwave frequency dividers which usually limit the performance of frequency synthesizers. In order to compare these dividers under different operation frequencies, we calculate additional time jitters of these dividers by using the measured phase noise. The time jitters are various from -0.1 fs to 43 fs in a bandwidth from 1 Hz to 100 Hz in dependent of models and operation frequencies. The HMC series frequency dividers exhibit outstanding performance for high operation frequencies, and the time jitters can be sub-fs. The time jitters of SP8401, MC10EP139, and MC100LVEL34 are comparable or even below that of HMC series for low operation frequencies.
基金The Science and Technology Project of Henan Province (182102310487)
文摘Objective: To systematically evaluate the clinical efficacy and safety of Masquelet technology and Llizarov group technology in the treatment of infectious bone defects by meta-analysis. Methods: The computer searched China Knowledge Network (CNKI), Wanfang, VIP, Chinese Biomedical Literature Database (CBM), Pubmed, Medline, Cochrane Llibrary databases. The retrieval time was from the time of the establishment of the database to January 2020. According to the inclusion and exclusion criteria, randomized controlled trials on the treatment of infectious bone defects using Masquelet technology and Llizarov technology were collected, and the retrieved literature was independently screened, evaluated, and data extracted by two researchers, and then RevMan5.3 software was used so for meta-analysis. Results: A total of 10 RCT documents were included, with a total of 496 patients, including 242 in the Masquelet group and 254 in the Llizarov group. The results of the meta-analysis showed that: in terms of bone defect healing time, total weight bearing time, treatment cost, and complication rate, the Masquelet group was significantly different from the Llizarov group, and the Masquelet group was better than the Llizarov group (P <0.05);In terms of knee joint Lowa score and SF-36 score, Masquelet group has significant differences compared with Llizarov group, Llizarov group is better than Masquelet group (P <0.05);in excellent rate, number of operations, ankle Lowa score, infection control rate In terms of excellent rate of affected limb function, there was no significant difference between Masquelet group and Llizarov group (P> 0.05). Conclusion:Compared with Llizarov technology, Masquelet technology has obvious advantages in the treatment of infectious bone defects in terms of bone defect healing time, total weight-bearing time, treatment cost, and complication rate. In terms of scoring, it has advantages over Masquelet technology, but in terms of excellent treatment rate, number of operations, and ankle lowa score. In terms of infection control rate and excellent function of affected limbs, there was no significant difference between Masquelet technology and Llizarov technology,However, due to the low quality of the included studies and the small sample size, the exact efficacy still needs to be confirmed by higher quality RCT studies.
基金financially supported by the National Natural Science Foundation of China(Nos.11834012 and 52130203)。
文摘Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based composites.Inert ceramic nanoparticles are good candidates for achieving this goal.In this study,we designed and prepared a series of p-type Bi_(0.5)Sb_(1.5)Te_(3)nanocomposites decorated with Y_(2)O_(3)ceramic nanoparticles via ball-milling dispersion and spark-plasma sintering.Owing to the chemical stability of the ceramics,no traces of atomic doping or interfacial reactions were observed.Transport measurements revealed that the Y_(2)O_(3)nanoparticles distributed along the grain boundaries acted as energy-dependent carrier-filtering centers to improve the scattering parameter and Seebeck coefficient,contributing to the elevated power factor even with a decreased electrical conductivity.Moreover,the incorporated Y_(2)O_(3)nanoparticles and various defect structures they induced effectively strengthened the phonon scattering and suppressed the lattice thermal conductivity.Consequently,a peak figure of merit(ZT)of 1.23 at 313 K was achieved for 0.4%Y_(2)O_(3)/Bi_(0.5)Sb_(1.5)Te_(3),which is 13%higher than that of the matrix.In addition,the Vickers hardness of the composite material was 35%higher than that of the matrix.This study demonstrates the effectiveness of ceramic nanoparticles in synergistic ally improving the thermoelectric and mechanical properties,which may be further extended to other thermoelectric systems.
基金supported by the National Natural Science Foundation of China(Grant No.51872006)High Level Doctoral Talent Program of Anhui University of Technology(DT17200008)National Undergraduate Training Programs for Innovation and Entrepreneurship(No.S201910360186).
文摘The binary skutterudite CoSb_(3) is a narrow bandgap semiconductor thermoelectric(TE)material with a relatively flat band structure and excellent electrical performance.However,thermal conductivity is very high because of the covalent bond between Co and Sb,resulting in a very low ZT value.Therefore,researchers have been trying to reduce its thermal conductivity by the different optimization methods.In addition,the synergistic optimization of the electrical and thermal transport parameters is also a key to improve the ZT value of CoSb_(3) material because the electrical and thermal transport parameters of TE materials are closely related to each other by the band structure and scattering mechanism.This review summarizes the main research progress in recent years to reduce the thermal conductivity of CoSb_(3)-based materials at atomic-molecular scale and nano-mesoscopic scale.We also provide a simple summary of achievements made in recent studies on the non-equilibrium preparation technologies of CoSb_(3)-based materials and synergistic optimization of the electrical and thermal transport parameters.In addition,the research progress of CoSb_(3)-based TE devices in recent years is also briefly discussed.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20100103)by the National Natural Science Foundation of China(41801028,42171120)。
文摘Permafrost degradation has been widely reported on the Tibetan Plateau(TP).However,directly observed evidence of permafrost thawing processes and degradation rates are very limited,although it is expected to be prevalent near the periphery of a permafrost area.Here,we report permafrost changes and disappearance in the Qilian Mountains(northeastern TP)based on three boreholes instrumented along a 100 m transect during 2014–2021.Our results show that permafrost has significantly degraded in the study area:the mean downward thawing rate from the permafrost table was about 0.16 m per year while the mean upward thawing rate from the permafrost base was about 0.23 m per year.We estimate the mean lateral degradation rate of permafrost in this area was∼4.14 m per year.More dramatically,the 1.5 m thick permafrost layer at one of the boreholes thawed completely between April of 2018 and December of 2019.Our results indicate that changes in climatic condition may have played only a limited role in controlling the active layer thickness in the vicinity of the altitudinal limit of permafrost;moisture content and soil conditions play key roles in site-specific permafrost thawing.This study provides new quantitative insights for understanding changes near the altitudinal limit of permafrost,and we suggest that land surface models or Earth system model studies of the lateral heat exchanges should be implemented in order to better represent permafrost thawing processes.
基金the Dalian Science and Technology Leading Talents Project(No.2019RD15)the Distinguished Professor of Liaoning Province,the Open Research Fund of the State Key Laboratory of Cognitive Neuroscience and Learning(No.CNLZD1801)+2 种基金the Natural Science Foundation of Liaoning Province(No.2020-MS-256)the Dalian Young Star of Science and Technology(No.2019RQ123)the Shanghai"Rising Stars of Medical Talent" Youth Development Program-Youth Medical Talents-Clinical Pharmacist Program(No.SHWJRS(2019)_072).
文摘Uncaria rhynchophylla has been widely used to treat central nervous system diseases for a long history.After investigation of U.rhynchophylla,eleven monoterpene indole alkaloids,including four new compounds uncarialins J-M(1-4)and seven known analogues(5-11),were isolated and identified.Their structural characterization was conducted using HRESIMS,1D and 2D NMR,electronic circular dichroism(ECD)spectra,and quantum chemical computations.Compounds 1,2,7,and 9-11 displayed significant ag-onistic effects towards 5-HT_(1A) receptor,and their EC_(50) values were 7.86,732,2.24,1.18,1.52,and 3.75μmol/L,respectively.Furthermore,in vivo experimental results fully revealed that hirsuteine(7)displayed a significant antidepression effect in unpredictable chronic mild stress(UCMS)-induced depression mice mainly via regulating 5-HT_(1A) signaling pathway.Molecular docking and site-directed amino acid mutation verified that amino acid residues Aspll6 and Asn386 were the binding sites of hirsuteine(7)with 5-HT_(1A) receptor.In addition,pre-treatment of mice with WAY 100635 also blocked the anti-depression effect of hirsuteine(7),which further demonstrated that 5-HT_(1A) receptor was a potential target of hirsuteine(7)to effectively treat depression.These findings indicated the therapeutic material basis of U.rhynchophylla and the anti-depression underlying mechanism of hirsuteine(7),and further provided the useful guidance for the development of hirsuteine(7)as a potential antidepressant candidate.
基金the National Natural Science Foundation of China(No.81703679)the Liaoning Provincial Key Research and Development Program(No.2019JH2/10300022)+1 种基金the Natural Science Foundation of Liaoning Province(No.2020-MS-256)the Dalian Young Star of Science and Tech nology(Nos.2019RQ123 and 2019RQ116).
文摘The investigation of Morinda officinalis led to the isolation of twelve compounds(1-12),including three new iridoid glycosides morindallns A-C(1-3)and nine known compounds(4-12).Their structural identifications were conducted using HRMS,1D and 2D NMR,and electronic circular dichroism(ECD)spectra as well as quantum chemical computations.Compound 6 displayed the most significantly agonistic activity against farnesoid X receptor(FXR)with an EC_(50) value of 7.18 μM,and its agonistic effect was verified through the investigation of FXR downstream target genes including small heterodimer partner 1(SHP1),bile salt export pump(BSEP),and organic solute transporter subunit alpha and beta(OSTα and OSTβ).The potential interaction of compound 6 with FXR was analyzed by molecular docking and molecular dynamics stimulation,revealing that amino acid residues Leu287;Thr288,and Ser332 played a crucial role in the activation of compound 6 towards FXR.These findings suggested that compound 6 could be regarded as a potential candidate for the development of FXR agonists.