Tile photoelectron spectroscopy beamline at National Synchrotron Radiation Laboratory （NSRL） is equipped with a spherical grating monochromator with the included angle of 174. Three gratings with line density of 200...Tile photoelectron spectroscopy beamline at National Synchrotron Radiation Laboratory （NSRL） is equipped with a spherical grating monochromator with the included angle of 174. Three gratings with line density of 200, 700 and 1200 lines/mm are used to cover the energy region from 60 eV to 1000 eV. After several years＇ operation, the spectral resolution and flux throughput were deteriorated, and realignment was necessary to improve the performance. First, the wavelength scanning mechanism, the optical components position and the exit slit guide direction are aligned according to tile design value. Second, the gratings are checked by Atomic Force Microscopy （AFM） and then the gas absorption spectrum is measured to optimize the focusing condition of the monoehromator. The spectral resolving power E/AE is recovered to the designed value of 1000@244 eV. The flux at the end station for the 200 lines/ram grating is about 1010 photons/sec/200 mA, which is in accordance with the design. The photon flux for the 700 lines/mm grating is about 5 108 photons/sec/200mA, which is lower than expected. This poor flux throughput may be caused by carbon contamination on the optical components. The 1200 lines/ram grating has roughness much higher than expected so the diffraction efficiency is too low to detect any signal. A new grating would be ordered. After the alignment, the beamline has significant performance improvements in both the resolving power aim the flux throughput for 200 and 700 lines/ram gratings and is provided to users.展开更多
The use of medicinal plants occupies an important place in traditional Chadian medicine, this study was carried out with the aim of listing the medicinal plants sold in the markets of the city of N’Djamena, and knowl...The use of medicinal plants occupies an important place in traditional Chadian medicine, this study was carried out with the aim of listing the medicinal plants sold in the markets of the city of N’Djamena, and knowledge of the medicinal flora Chad, such as the leaves of Guiera senegalensis in Arabic called Khibeche, the roots of Cassia occidentalis called Am kwala-Kinkéliba in Arabic;the bark of Khaya senegalensis (Desv) A. Juss called Muraї in Arabic and the seeds of Trigonella foenum-graecum called Helbé in Arabic in order to treat the most frequently cited diseases such as malaria, the common cold, mother and newborn care, and typhoid. Ethnobotanical surveys were conducted from September to December 2022, in three markets in the city of N’Djamena, based on individual interviews using a semi-structured questionnaire, with 30 herbalists and traditional practitioners. Phytochemical screening analyses of the organs of four plants were carried out in the chemistry and biology laboratory of the Faculty of Exact and Applied Sciences (FSEA) following a standard protocol established by [1] and slightly modified by [2] [3]. The results of the surveys identified 68 species divided into fifty-five (55) genera and twenty-seven (27) families, the most represented of which were Caesalpiniaceae (10 species), Mimosaceae (5 species) and Combretaceae (4 species). The leaves were the most commonly used parts (43%), with decoction (70%) the most frequently used method of preparation. The oral route was the most popular with 73% of recipes. The phytochemical study revealed a wealth of secondary metabolites such as Trapezoidal Sterols, Alkaloids, Tannins, Flavonoids, Free Quinones, Anthocyane, Anthraquinones, Saponosides and Heterosides. These results can be considered as a source of information for scientific research in the field of phytochemistry and pharmacology.展开更多
The problem of access to quality water is a major challenge, as it has a major impact on the socio-economic conditions of people in developing countries. The water from the islands of Lake Fitri is one of the main sou...The problem of access to quality water is a major challenge, as it has a major impact on the socio-economic conditions of people in developing countries. The water from the islands of Lake Fitri is one of the main sources of drinking water for the population. The aim of this study is to characterise and assess the quality of the water and sediment from the islands (Moudou and Birguime) of Lake Fitri, and to confirm the strains isolated using the PCR method. A total of fifty (50) samples of water and fifty (50) sediments from the islands of Lake Fitri were analyzed. Standard methods of microbiological and biochemical analysis of water and sediments were used. Isolated Enterobacteriaceae strains were characterized by API 20 E and API Staph galleries and Salmonella was confirmed by PCR method. Antibiotic resistance was determined using a technique recommended by the antibiogram committee of the French microbiology society (CA-SFM, 2019). The microbiological results for the water showed an abundance of total aerobic mesophilic flora (TAMF) (4.31 × 106 ± 8.05 × 105 and 5.29 × 106 ± 2.55 × 105) on the Birguime and Moudou islands successively. The microbiological results for the sediment from Birguime and Moudou islands showed an abundance of thermotolerant coliforms (E. coli) (2.05 × 105 ± 5.43 × 104 and 2.27 × 105 ± 3.49 × 104) alternately. The results obtained after incubation of the biochemical tests by the API 20E, API Staph gallery and their numerical profile proposed by the Api software confirmed the contamination. The antibiogram results showed the emergence of certain resistances to the antibiotics Tobramycin, Flucytosine, Amikacin and Teicoplani. The PCR results for Salmonella spp strains were confirmed. As a result, strict monitoring of the water on the various islands of Lake Fitri must be carried out throughout the annual cycle, by specialized personnel, to ensure proper bio-monitoring of these ecosystems.展开更多
The parameters of beam transverse positions at HLS 200 MeV LINAC are very important to injection ef-ficiency. We have designed a new non-interceptive strip line beam position monitor (BPM) as a substitution for the or...The parameters of beam transverse positions at HLS 200 MeV LINAC are very important to injection ef-ficiency. We have designed a new non-interceptive strip line beam position monitor (BPM) as a substitution for the original interceptive fluorescent target. This paper gives out the theoretical analysis and bench test result of the strip line BPM. The BPM has a characteristic impedance of (50±5)?, a reflection coefficient of less than –4 dB, a band-width of 400 MHz, a coupling coefficient of less than -15 dB, and a sensitivity of 1.16 dB/mm. Additionally, the strip line BPM has a good linearity.展开更多
A data processing program has been applied for the new beam position monitor (BPM) system of the storage ring at Hefei Light Source (HLS). The new BPM system in the upgrade project will be equipped with Libera Brillia...A data processing program has been applied for the new beam position monitor (BPM) system of the storage ring at Hefei Light Source (HLS). The new BPM system in the upgrade project will be equipped with Libera Brilliance BPM processors to replace the old Bergoz MX-BPM processors. The embedded Linux system on Libera has completed some important work, including instrument status check,data acquisition, position calculation, EPICS IOC data release,and so on. A new EPICS record type has been developed to recalculate the beam position with log-ratio method. The property of the new position data was analyzed in the time and frequency domain. The results show that the rms value of beam position measurement resolution can be up to submicron. Preliminary studies have been carried out on the measurement of the tune and the beam lifetime with this new BPM system.展开更多
As an important part of the beam diagnostic system, the synchrotron light beam position measurement has a very high value in the high quality and high stability light source applied research. A new photon beam positio...As an important part of the beam diagnostic system, the synchrotron light beam position measurement has a very high value in the high quality and high stability light source applied research. A new photon beam position monitor based on position-sensitive detector (PSD) has been developed to measure the photon beam position in vertical and horizontal directions at the same time at HLS (Hefei Light Source). The new PBPM based on the PSD has fast response speed, high sensitivity and wide dynamic range. This PBPM system also includes the C4674 signal processing circuit, NI USB-9215 data acquisition device and the LABVIEW data acquisition program. This PBPM system has been calibrated vertically and horizontally on-line, and then has been applied in the beam line B3EA of HLS to measure the position of the synchrotron light. As the results shown, the resolution of the system is better than 3 mm.展开更多
Hydrostatic leveling system(HLS)is widely used in precision engineering survey,especially the alignment of particle accelerator,and the tidal effects on the measurement accuracy of HLS is non-ignorable,thus studies on...Hydrostatic leveling system(HLS)is widely used in precision engineering survey,especially the alignment of particle accelerator,and the tidal effects on the measurement accuracy of HLS is non-ignorable,thus studies on tidal effects on the HLS is vital.A set of HLS was installed in Jingxian seismostation for verifying the methods to handle the tidal effects on the readings of HLS.Harmonic analysis of the data recorded by HLS and DSQ water tube clinometers in Jingxian seismostation and contrastive analysis of the results are completed.The tilt tide can be well reflected in the data of the both instruments and the results are both reliable.The reasons of the difference between the results are analyzed in this paper.Besides,a validation study based on the measurement data of the HLS used in SPring-8 storage ring for tidal correction on the reading of HLS is completed.The research establishes a foundation for HLS to be applied in micron-level precision alignment of particle accelerator in the future.展开更多
The paper introduce the measurement of some beam parameters for Hefei Light Source (HLS) by frequency domain technique, which include the betatron tune, average beta function, natural chromaticity, corrected chroinati...The paper introduce the measurement of some beam parameters for Hefei Light Source (HLS) by frequency domain technique, which include the betatron tune, average beta function, natural chromaticity, corrected chroinaticity, and center frequency. Additionally, the measurement of the influence of DC clearing electrodes on the betatron tune shift is also described. Some measurement results are given. The measurement results are compared with the theoretical values and shown to be in good agreement.展开更多
Experimental results are given for the temperature dependence of the decay time of the emission at 430nm from PbWO_(4) crystal under vacuum-ultraviolet(82nm)photon excitation in the temperature range of 80-300K.The st...Experimental results are given for the temperature dependence of the decay time of the emission at 430nm from PbWO_(4) crystal under vacuum-ultraviolet(82nm)photon excitation in the temperature range of 80-300K.The structures in the curve are interpreted for the first time by studying the thermoluminescence of PbWO_(4),which originates from the traps in the crystal.展开更多
A Ultrafine amorphous NiB alloy was prepared via chemical reduction method;Its structures during the crystallizatioin precess was characterized by such techniques as Differential thermal analysis (DTA),X-ray absorptio...A Ultrafine amorphous NiB alloy was prepared via chemical reduction method;Its structures during the crystallizatioin precess was characterized by such techniques as Differential thermal analysis (DTA),X-ray absorption fine structure (XAFS) and X-ray diffraction(XRD),and correlated to the catalytic properties for benzene hydrogenation.It was found that the crystallization of amorphous NiB alloy was carried out in two steps,as indicated by two exothermic peaks centered at 598 and 652K respectively.During the first step.two metastable crystalline phases,i.e.,Ni3B and a noaocrstalline Ni phase(Ni-rich NiB alloy),were formed.Further annealing at higher temperature of 652 K may result in the decomposition of crystalline Ni3B and aggregation of nanocrystalline Ni,the benzene hydrogenation is optimized around the annealing temperature of 623K.It most probably results from the maximum amount of active site on nanocrystalline Ni formed by thermal treatment at appropriate annealing temperature.展开更多
Luminescence spectra of SrAl12O19：Pr^3＋,Mn^2＋ under VUV-UV excitation are investigated. The characteristic emissions between 4f levels and the excitation of 5d for Pr^3＋ are observed. The emission of Mn^3＋ peaks ...Luminescence spectra of SrAl12O19：Pr^3＋,Mn^2＋ under VUV-UV excitation are investigated. The characteristic emissions between 4f levels and the excitation of 5d for Pr^3＋ are observed. The emission of Mn^3＋ peaks at 517nm and the excitations clue to the ground to multiplets are observed at 276, 360, 386 and 426nm. However, the spectral overlap between the emission of Pr^3＋ and excitation of Mn^2＋ is absent, suggesting that the quantum splitting cannot be achieved via a Pr^3＋ Mn^2＋ ion pair in the host SrAl12O19.展开更多
By incorporating a limited number of precious metal atoms into the base metal,the single-atom alloy catalyst not only optimizes the electronic structure and stability of the catalyst but also emerges as an innovative ...By incorporating a limited number of precious metal atoms into the base metal,the single-atom alloy catalyst not only optimizes the electronic structure and stability of the catalyst but also emerges as an innovative material that enhances the efficiency and selectivity of catalytic reactions.RuCo single-atom alloy electrocatalyst supported on S,N co-doped carbon nanosheets(RuCo SAA/SNC)uniformly distributed on nitrogen,sulfur co-doped carbon nanosheets was prepared by two-step pyrolysis and carbonization.The incorporation of Ru not only optimizes the atomic utilization of Ru but also enhances the charge conduction properties of the surface Co species,thereby increasing the evolution and migration rates of hydrogen ions.In a 0.5 M H_(2)SO_(4) solution,the RuCo SAA/SNC catalyst demonstrates a tafel slope of 27.5 mV·dec^(-1) and an overpotential of merely 43 mV at 10 mA·cm^(-2).This work achieves enhanced catalytic performance and stability by precisely regulating the atomic-level structure of single-atom alloy catalysts,thereby promoting their widespread application in energy conversion and green chemistry.展开更多
The electrochemical CO_(2) reduction reaction(CO_(2)RR)holds significant promise in advancing carbon neutrality.Developing catalysts for the electrochemical CO_(2)RR to multi-carbon(C_(2+))products(e.g.,C_(2)H_(4))und...The electrochemical CO_(2) reduction reaction(CO_(2)RR)holds significant promise in advancing carbon neutrality.Developing catalysts for the electrochemical CO_(2)RR to multi-carbon(C_(2+))products(e.g.,C_(2)H_(4))under industrial-level current density is urgently needed and pivotal.Herein,we report the Cu_(2)O nanoparticles doped with interstitial carbon atoms(denoted as C-Cu_(2)O NPs)for the conversion of CO_(2) to C_(2+)products.The interstitial carbon promotes the C-Cu_(2)O NPs to possess abundant unsaturated Cu–O bonds,leading to a high-density Cu^(δ+)(0<δ<1)species.The obtained C-Cu_(2)O NPs exhibited significant Faradic efficiency(FE)of C_(2+) products approaching 76.9%and a partial current density reaching 615.2 mA·cm^(–2)under an industrial-level current density of 800 mA·cm^(–2).Furthermore,the efficient electrosynthesis of C_(2)H_(4) achieved an FE of 57.4%with a partial current density of 459.2 mA·cm^(–2).In situ electrochemical attenuated total reflection Fourier transform infrared spectroscopy and in situ Raman spectroscopy analyses revealed that C-Cu_(2)O NPs stabilized the intermediate*CO and facilitated C–C coupling,leading to increased selectivity towards C_(2+) products.展开更多
IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved question.Meanwhile,addressing the ...IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved question.Meanwhile,addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis(PEM-WE).Herein,we prepared an IrRuO_(x)nanomeshes(IrRuO_(x)NMs)with high coordination number(CN)of Ir-O-Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor.X-ray absorption spectroscopy analysis revealed that the IrRuO_(x)NMs possess high coordination number of Ir-O-Ru bonds(CNIr-O-Ru=5.6)with a distance of 3.18Å.Moreover,the nanomesh structures of IrRuO_(x)NMs provided hierarchical channels to accelerate the transport of oxygen and water,thus further improving the electrochemical activity.Consequently,the IrRuO_(x)NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm^(−2)and slightly increase by 70 mV over 650 h test.Differential electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_(x)NMs is the adsorbent evolution mechanism,which is beneficial for the robust structural stability.展开更多
Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confr...Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confronted with drawback of significantly increased cost. To maximize the atom efficiency and reduce the cost for practical industrial application, designing sensor material with noble metal isolated single atom sites (ISAS) doping is a desired option. Here, we report an atomically dispersed platinum on one-dimensional arranged porous γ-Fe2O3 nanoparticle composites as highly efficient ethanol gas sensor. The optimized sample (Pt1-Fe2O3-ox) exhibited a high response (Ra/Rg = 102.4) and good selectivity to ethanol gas. It is demonstrated only the Pt single atom sites with high valance can effectively promote the adsorption capacity to ethanol and consequently enhance the sensitivity of sensing process by changing the electrical structure of Fe2O3 support. This work indicates the single atom sites could play a vital role in improving the performance of conventional metal oxides gas sensors and pave way for the exploration of ISAS-enhanced gas sensor for other volatile organic compounds (VOCs).展开更多
For the HLS-II bunch current measurement system, in order to obtain the absolute value of bunch current, the calibration factor should be determined by using DCCT. At the HLS storage ring, the stretch effect of bunch ...For the HLS-II bunch current measurement system, in order to obtain the absolute value of bunch current, the calibration factor should be determined by using DCCT. At the HLS storage ring, the stretch effect of bunch length is observed and the change rate is about 19% when the bunch current decays over time and this will affect the performance of bunch current detection. To overcome the bunch stretch influence in the HLS-II bunch current measurement, an evaluation about pickup type and signal processing is carried out. Strip-line pickup and button pickup are selectable, and the theoretical analysis and demonstration experiment are performed to find out an acceptable solution for the bunch current measurement system at HLS-H. The experimental data analysis shows that the normalized calibration factor will change by about 27% when the bunch length changes by about 19% if using the button pickup and processing by peak value of bunch signal; the influence will be reduced to 2% less if adopting the strip-line pickup and integral.展开更多
Manipulating the oxidation state of Cu catalysts can significantly affect the selectivity and activity of electrocatalytic carbon dioxide reduction(CO_(2)RR).However,the thermodynamically favorable cathodic reduction ...Manipulating the oxidation state of Cu catalysts can significantly affect the selectivity and activity of electrocatalytic carbon dioxide reduction(CO_(2)RR).However,the thermodynamically favorable cathodic reduction to metallic states typically leads to catalytic deactivation.Herein,a defect construction strategy is employed to prepare crystalline/amorphous Cu_(2+1)O/CuO_(x)heterostructures(c/a-CuO_(x))with abundant Cu0 and Cuδ+(0<δ<1)sites for CO_(2)RR.The C^(2+)Faradaic efficiency of the heterostructured Cu catalyst is up to 81.3%,with partial current densities of 406.7 mA·cm−2.Significantly,real-time monitoring of the Cu oxidation state evolution by in-situ Raman spectroscopy confirms the stability of Cuδ+species under long-term high current density operation.Density functional theory(DFT)calculations further reveal that the adjacent Cu0 and Cuδ+sites in heterostructured c/a-CuO_(x)can efficiently reduce the energy barrier of CO coupling for C^(2+)products.展开更多
Heteroatom-doped carbon dots （CDs） with a high photoluminescent quantum yield （PLQY） have recently attracted attention due to their applications in chemical sensors, photocatalysis, bioimaging, and drug delivery. ...Heteroatom-doped carbon dots （CDs） with a high photoluminescent quantum yield （PLQY） have recently attracted attention due to their applications in chemical sensors, photocatalysis, bioimaging, and drug delivery. Nitrogen and phosphorus are in close proximity to carbon in the periodic table and are key tracking elements in the field of biomedical imaging. These two elements alter the optical and electronic properties of CDs and help improve the fundamental understanding of their PLQY. This can also lead to multifunctional usage in photoimaging and photothermal therapy. However, most PLQYs resulting from the synthesis of P-doped CDs are currently below 50%. These CDs have limited usefulness in the fields of bioimaging and drug delivery. In this study, a single-step, high-efficiency hydrothermal method was applied to synthesize nitrogen and phosphorous-doped carbon dots （（N,P）-CDs） with a PLQY of up to 53.8% with independent emission behavior. Moreover, the CDs presented high monodispersity, robust excitation-independent luminescence, and stability over a large pH range. Spectroscopic investigations indicated that the PLQY of the （N,P）-CDs was primarily due to the addition of P and the passivation effect of the oxidized surface. The excellent fluorescence properties of （N,P）-CDs can be effectively and selectively quenched by Hg2~ ions. Such systems show a linear response in the 0-900 nM concentration range with a short response time, indicating their potential for applications in the fields of chemistry and biology.展开更多
基金Supported by National Major Scientific Instruments Equipment Development Project(11YQ120023)
文摘Tile photoelectron spectroscopy beamline at National Synchrotron Radiation Laboratory （NSRL） is equipped with a spherical grating monochromator with the included angle of 174. Three gratings with line density of 200, 700 and 1200 lines/mm are used to cover the energy region from 60 eV to 1000 eV. After several years＇ operation, the spectral resolution and flux throughput were deteriorated, and realignment was necessary to improve the performance. First, the wavelength scanning mechanism, the optical components position and the exit slit guide direction are aligned according to tile design value. Second, the gratings are checked by Atomic Force Microscopy （AFM） and then the gas absorption spectrum is measured to optimize the focusing condition of the monoehromator. The spectral resolving power E/AE is recovered to the designed value of 1000@244 eV. The flux at the end station for the 200 lines/ram grating is about 1010 photons/sec/200 mA, which is in accordance with the design. The photon flux for the 700 lines/mm grating is about 5 108 photons/sec/200mA, which is lower than expected. This poor flux throughput may be caused by carbon contamination on the optical components. The 1200 lines/ram grating has roughness much higher than expected so the diffraction efficiency is too low to detect any signal. A new grating would be ordered. After the alignment, the beamline has significant performance improvements in both the resolving power aim the flux throughput for 200 and 700 lines/ram gratings and is provided to users.
文摘The use of medicinal plants occupies an important place in traditional Chadian medicine, this study was carried out with the aim of listing the medicinal plants sold in the markets of the city of N’Djamena, and knowledge of the medicinal flora Chad, such as the leaves of Guiera senegalensis in Arabic called Khibeche, the roots of Cassia occidentalis called Am kwala-Kinkéliba in Arabic;the bark of Khaya senegalensis (Desv) A. Juss called Muraї in Arabic and the seeds of Trigonella foenum-graecum called Helbé in Arabic in order to treat the most frequently cited diseases such as malaria, the common cold, mother and newborn care, and typhoid. Ethnobotanical surveys were conducted from September to December 2022, in three markets in the city of N’Djamena, based on individual interviews using a semi-structured questionnaire, with 30 herbalists and traditional practitioners. Phytochemical screening analyses of the organs of four plants were carried out in the chemistry and biology laboratory of the Faculty of Exact and Applied Sciences (FSEA) following a standard protocol established by [1] and slightly modified by [2] [3]. The results of the surveys identified 68 species divided into fifty-five (55) genera and twenty-seven (27) families, the most represented of which were Caesalpiniaceae (10 species), Mimosaceae (5 species) and Combretaceae (4 species). The leaves were the most commonly used parts (43%), with decoction (70%) the most frequently used method of preparation. The oral route was the most popular with 73% of recipes. The phytochemical study revealed a wealth of secondary metabolites such as Trapezoidal Sterols, Alkaloids, Tannins, Flavonoids, Free Quinones, Anthocyane, Anthraquinones, Saponosides and Heterosides. These results can be considered as a source of information for scientific research in the field of phytochemistry and pharmacology.
文摘The problem of access to quality water is a major challenge, as it has a major impact on the socio-economic conditions of people in developing countries. The water from the islands of Lake Fitri is one of the main sources of drinking water for the population. The aim of this study is to characterise and assess the quality of the water and sediment from the islands (Moudou and Birguime) of Lake Fitri, and to confirm the strains isolated using the PCR method. A total of fifty (50) samples of water and fifty (50) sediments from the islands of Lake Fitri were analyzed. Standard methods of microbiological and biochemical analysis of water and sediments were used. Isolated Enterobacteriaceae strains were characterized by API 20 E and API Staph galleries and Salmonella was confirmed by PCR method. Antibiotic resistance was determined using a technique recommended by the antibiogram committee of the French microbiology society (CA-SFM, 2019). The microbiological results for the water showed an abundance of total aerobic mesophilic flora (TAMF) (4.31 × 106 ± 8.05 × 105 and 5.29 × 106 ± 2.55 × 105) on the Birguime and Moudou islands successively. The microbiological results for the sediment from Birguime and Moudou islands showed an abundance of thermotolerant coliforms (E. coli) (2.05 × 105 ± 5.43 × 104 and 2.27 × 105 ± 3.49 × 104) alternately. The results obtained after incubation of the biochemical tests by the API 20E, API Staph gallery and their numerical profile proposed by the Api software confirmed the contamination. The antibiogram results showed the emergence of certain resistances to the antibiotics Tobramycin, Flucytosine, Amikacin and Teicoplani. The PCR results for Salmonella spp strains were confirmed. As a result, strict monitoring of the water on the various islands of Lake Fitri must be carried out throughout the annual cycle, by specialized personnel, to ensure proper bio-monitoring of these ecosystems.
基金Supported by Project of Building a High-level University Well-known Both in China and in the World (KY2901), and Project of Hi-tech Research and Development Program of China (863-410-8-2)
文摘The parameters of beam transverse positions at HLS 200 MeV LINAC are very important to injection ef-ficiency. We have designed a new non-interceptive strip line beam position monitor (BPM) as a substitution for the original interceptive fluorescent target. This paper gives out the theoretical analysis and bench test result of the strip line BPM. The BPM has a characteristic impedance of (50±5)?, a reflection coefficient of less than –4 dB, a band-width of 400 MHz, a coupling coefficient of less than -15 dB, and a sensitivity of 1.16 dB/mm. Additionally, the strip line BPM has a good linearity.
文摘A data processing program has been applied for the new beam position monitor (BPM) system of the storage ring at Hefei Light Source (HLS). The new BPM system in the upgrade project will be equipped with Libera Brilliance BPM processors to replace the old Bergoz MX-BPM processors. The embedded Linux system on Libera has completed some important work, including instrument status check,data acquisition, position calculation, EPICS IOC data release,and so on. A new EPICS record type has been developed to recalculate the beam position with log-ratio method. The property of the new position data was analyzed in the time and frequency domain. The results show that the rms value of beam position measurement resolution can be up to submicron. Preliminary studies have been carried out on the measurement of the tune and the beam lifetime with this new BPM system.
基金Supported by the National Science Foundation of China (10675118, 11175173)
文摘As an important part of the beam diagnostic system, the synchrotron light beam position measurement has a very high value in the high quality and high stability light source applied research. A new photon beam position monitor based on position-sensitive detector (PSD) has been developed to measure the photon beam position in vertical and horizontal directions at the same time at HLS (Hefei Light Source). The new PBPM based on the PSD has fast response speed, high sensitivity and wide dynamic range. This PBPM system also includes the C4674 signal processing circuit, NI USB-9215 data acquisition device and the LABVIEW data acquisition program. This PBPM system has been calibrated vertically and horizontally on-line, and then has been applied in the beam line B3EA of HLS to measure the position of the synchrotron light. As the results shown, the resolution of the system is better than 3 mm.
基金Supported by the National Natural Science Foundation of China(No.11075151)Ph.D.Program Foundation of Ministry of Education ofChina(No.20123402110002)
文摘Hydrostatic leveling system(HLS)is widely used in precision engineering survey,especially the alignment of particle accelerator,and the tidal effects on the measurement accuracy of HLS is non-ignorable,thus studies on tidal effects on the HLS is vital.A set of HLS was installed in Jingxian seismostation for verifying the methods to handle the tidal effects on the readings of HLS.Harmonic analysis of the data recorded by HLS and DSQ water tube clinometers in Jingxian seismostation and contrastive analysis of the results are completed.The tilt tide can be well reflected in the data of the both instruments and the results are both reliable.The reasons of the difference between the results are analyzed in this paper.Besides,a validation study based on the measurement data of the HLS used in SPring-8 storage ring for tidal correction on the reading of HLS is completed.The research establishes a foundation for HLS to be applied in micron-level precision alignment of particle accelerator in the future.
基金Supported by National Important Project on Science-Phase Ⅱ of National Synchrotron Radiation Laboratory
文摘The paper introduce the measurement of some beam parameters for Hefei Light Source (HLS) by frequency domain technique, which include the betatron tune, average beta function, natural chromaticity, corrected chroinaticity, and center frequency. Additionally, the measurement of the influence of DC clearing electrodes on the betatron tune shift is also described. Some measurement results are given. The measurement results are compared with the theoretical values and shown to be in good agreement.
基金Supported by the National Natural Science Foundation of China under Grant No.19774053Deutscher Akademischer Austauschdienste of GermanyJapan Science Promotion Society.
文摘Experimental results are given for the temperature dependence of the decay time of the emission at 430nm from PbWO_(4) crystal under vacuum-ultraviolet(82nm)photon excitation in the temperature range of 80-300K.The structures in the curve are interpreted for the first time by studying the thermoluminescence of PbWO_(4),which originates from the traps in the crystal.
文摘A Ultrafine amorphous NiB alloy was prepared via chemical reduction method;Its structures during the crystallizatioin precess was characterized by such techniques as Differential thermal analysis (DTA),X-ray absorption fine structure (XAFS) and X-ray diffraction(XRD),and correlated to the catalytic properties for benzene hydrogenation.It was found that the crystallization of amorphous NiB alloy was carried out in two steps,as indicated by two exothermic peaks centered at 598 and 652K respectively.During the first step.two metastable crystalline phases,i.e.,Ni3B and a noaocrstalline Ni phase(Ni-rich NiB alloy),were formed.Further annealing at higher temperature of 652 K may result in the decomposition of crystalline Ni3B and aggregation of nanocrystalline Ni,the benzene hydrogenation is optimized around the annealing temperature of 623K.It most probably results from the maximum amount of active site on nanocrystalline Ni formed by thermal treatment at appropriate annealing temperature.
基金Supported by the National Natural Science Foundation of China under Grant No 90201019.
文摘Luminescence spectra of SrAl12O19：Pr^3＋,Mn^2＋ under VUV-UV excitation are investigated. The characteristic emissions between 4f levels and the excitation of 5d for Pr^3＋ are observed. The emission of Mn^3＋ peaks at 517nm and the excitations clue to the ground to multiplets are observed at 276, 360, 386 and 426nm. However, the spectral overlap between the emission of Pr^3＋ and excitation of Mn^2＋ is absent, suggesting that the quantum splitting cannot be achieved via a Pr^3＋ Mn^2＋ ion pair in the host SrAl12O19.
基金supported by the National Natural Science Foundation of China(No.22201262).
文摘By incorporating a limited number of precious metal atoms into the base metal,the single-atom alloy catalyst not only optimizes the electronic structure and stability of the catalyst but also emerges as an innovative material that enhances the efficiency and selectivity of catalytic reactions.RuCo single-atom alloy electrocatalyst supported on S,N co-doped carbon nanosheets(RuCo SAA/SNC)uniformly distributed on nitrogen,sulfur co-doped carbon nanosheets was prepared by two-step pyrolysis and carbonization.The incorporation of Ru not only optimizes the atomic utilization of Ru but also enhances the charge conduction properties of the surface Co species,thereby increasing the evolution and migration rates of hydrogen ions.In a 0.5 M H_(2)SO_(4) solution,the RuCo SAA/SNC catalyst demonstrates a tafel slope of 27.5 mV·dec^(-1) and an overpotential of merely 43 mV at 10 mA·cm^(-2).This work achieves enhanced catalytic performance and stability by precisely regulating the atomic-level structure of single-atom alloy catalysts,thereby promoting their widespread application in energy conversion and green chemistry.
基金supported by the National Key R&D Program of China(No.2018YFA0702001)the National Natural Science Foundation of China(Nos.22371268 and 22301287)+4 种基金Fundamental Research Funds for the Central Universities(No.WK2060000016)Anhui Provincial Natural Science Foundation(Nos.2208085J09 and 2208085QB33)Collaborative Innovation Program of Hefei Science Center,CAS(No.2022HSC-CIP020)Youth Innovation Promotion Association of the Chinese Academy of Science(No.2018494)USTC Tang Scholar.
文摘The electrochemical CO_(2) reduction reaction(CO_(2)RR)holds significant promise in advancing carbon neutrality.Developing catalysts for the electrochemical CO_(2)RR to multi-carbon(C_(2+))products(e.g.,C_(2)H_(4))under industrial-level current density is urgently needed and pivotal.Herein,we report the Cu_(2)O nanoparticles doped with interstitial carbon atoms(denoted as C-Cu_(2)O NPs)for the conversion of CO_(2) to C_(2+)products.The interstitial carbon promotes the C-Cu_(2)O NPs to possess abundant unsaturated Cu–O bonds,leading to a high-density Cu^(δ+)(0<δ<1)species.The obtained C-Cu_(2)O NPs exhibited significant Faradic efficiency(FE)of C_(2+) products approaching 76.9%and a partial current density reaching 615.2 mA·cm^(–2)under an industrial-level current density of 800 mA·cm^(–2).Furthermore,the efficient electrosynthesis of C_(2)H_(4) achieved an FE of 57.4%with a partial current density of 459.2 mA·cm^(–2).In situ electrochemical attenuated total reflection Fourier transform infrared spectroscopy and in situ Raman spectroscopy analyses revealed that C-Cu_(2)O NPs stabilized the intermediate*CO and facilitated C–C coupling,leading to increased selectivity towards C_(2+) products.
基金The National Key Research and Development Program of China(Nos.2018YFA0702001 and 2021YFA1500400)the National Natural Science Foundation of China(Nos.22371268 and 22175163)+2 种基金Fundamental Research Funds for the Central Universities(No.WK2060000016)Anhui Development and Reform Commission(No.AHZDCYCX-2SDT2023-07)Youth Innovation Promotion Association of the Chinese Academy of Science(No.2018494)supported this work.
文摘IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved question.Meanwhile,addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis(PEM-WE).Herein,we prepared an IrRuO_(x)nanomeshes(IrRuO_(x)NMs)with high coordination number(CN)of Ir-O-Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor.X-ray absorption spectroscopy analysis revealed that the IrRuO_(x)NMs possess high coordination number of Ir-O-Ru bonds(CNIr-O-Ru=5.6)with a distance of 3.18Å.Moreover,the nanomesh structures of IrRuO_(x)NMs provided hierarchical channels to accelerate the transport of oxygen and water,thus further improving the electrochemical activity.Consequently,the IrRuO_(x)NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm^(−2)and slightly increase by 70 mV over 650 h test.Differential electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_(x)NMs is the adsorbent evolution mechanism,which is beneficial for the robust structural stability.
基金supported by the National Key Research and Development Program of China(2021YFA1500402)the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(XDB0450302)+3 种基金the National Natural Science Foundation of China(22161142001,U22A20401,and 22101269)International Partnership Program of CAS(123GJHZ2022028MI)the Fundamental Research Funds for the Central Universities(WK3450000007 and WK2060000038)the XAS supports from Beijing Synchrotron Radiation Facility(BSRF)。
基金This work was supported by the National Key R&D Program of China(No.2018YFA0702003)the National Natural Science Foundation of China(Nos.21890383 and 21971137)+1 种基金Science and Technology Key Project of Guangdong Province of China(No.2020B010188002)Beijing Municipal Science&Technology Commission(No.Z191100007219003).
文摘Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confronted with drawback of significantly increased cost. To maximize the atom efficiency and reduce the cost for practical industrial application, designing sensor material with noble metal isolated single atom sites (ISAS) doping is a desired option. Here, we report an atomically dispersed platinum on one-dimensional arranged porous γ-Fe2O3 nanoparticle composites as highly efficient ethanol gas sensor. The optimized sample (Pt1-Fe2O3-ox) exhibited a high response (Ra/Rg = 102.4) and good selectivity to ethanol gas. It is demonstrated only the Pt single atom sites with high valance can effectively promote the adsorption capacity to ethanol and consequently enhance the sensitivity of sensing process by changing the electrical structure of Fe2O3 support. This work indicates the single atom sites could play a vital role in improving the performance of conventional metal oxides gas sensors and pave way for the exploration of ISAS-enhanced gas sensor for other volatile organic compounds (VOCs).
基金Supported by National Natural Science Foundation of China(11105141)Fundamental Research Funds for the Central Universities(WK2310000015)
文摘For the HLS-II bunch current measurement system, in order to obtain the absolute value of bunch current, the calibration factor should be determined by using DCCT. At the HLS storage ring, the stretch effect of bunch length is observed and the change rate is about 19% when the bunch current decays over time and this will affect the performance of bunch current detection. To overcome the bunch stretch influence in the HLS-II bunch current measurement, an evaluation about pickup type and signal processing is carried out. Strip-line pickup and button pickup are selectable, and the theoretical analysis and demonstration experiment are performed to find out an acceptable solution for the bunch current measurement system at HLS-H. The experimental data analysis shows that the normalized calibration factor will change by about 27% when the bunch length changes by about 19% if using the button pickup and processing by peak value of bunch signal; the influence will be reduced to 2% less if adopting the strip-line pickup and integral.
基金supported by the National Key R&D Program of China(Nos.2017YFA0700104 and 2018YFA0702001)the National Natural Science Foundation of China(Nos.21871238 and 22175163)+1 种基金the Fundamental Research Funds for the Central Universities(No.WK2060000016)the Youth Innovation Promotion Association of the Chinese Academy of Science(No.2018494).
文摘Manipulating the oxidation state of Cu catalysts can significantly affect the selectivity and activity of electrocatalytic carbon dioxide reduction(CO_(2)RR).However,the thermodynamically favorable cathodic reduction to metallic states typically leads to catalytic deactivation.Herein,a defect construction strategy is employed to prepare crystalline/amorphous Cu_(2+1)O/CuO_(x)heterostructures(c/a-CuO_(x))with abundant Cu0 and Cuδ+(0<δ<1)sites for CO_(2)RR.The C^(2+)Faradaic efficiency of the heterostructured Cu catalyst is up to 81.3%,with partial current densities of 406.7 mA·cm−2.Significantly,real-time monitoring of the Cu oxidation state evolution by in-situ Raman spectroscopy confirms the stability of Cuδ+species under long-term high current density operation.Density functional theory(DFT)calculations further reveal that the adjacent Cu0 and Cuδ+sites in heterostructured c/a-CuO_(x)can efficiently reduce the energy barrier of CO coupling for C^(2+)products.
基金supported by the Natural Science Foundation of Shandong Province(ZR2020ZD10)the National Natural Science Foundation of China(21775142)Shenzhen Natural Science Fund(20200925154115001 and JCYJ20210324115809026).
基金We thank the Beijing Nova Program （No. Z171100001117058）, Beijing Nova program Interdisdplinary Studies Cooperative Project, Beijing Municipal Science and Technology Project （No. Z161100001316010）, State Key Laboratory of Silicate Materials for Architecture （No. SYSJJ2016-05）, Medical Science Youth Training Program （No. 16PNQ145）, Defense Technology Project Fund （No. 3408080）, Translational Medicine Project of PLAGH （No. 2016TM-019）, and the National Science Foundation for Young Scientists of China （No. 81402216） for the support.
文摘Heteroatom-doped carbon dots （CDs） with a high photoluminescent quantum yield （PLQY） have recently attracted attention due to their applications in chemical sensors, photocatalysis, bioimaging, and drug delivery. Nitrogen and phosphorus are in close proximity to carbon in the periodic table and are key tracking elements in the field of biomedical imaging. These two elements alter the optical and electronic properties of CDs and help improve the fundamental understanding of their PLQY. This can also lead to multifunctional usage in photoimaging and photothermal therapy. However, most PLQYs resulting from the synthesis of P-doped CDs are currently below 50%. These CDs have limited usefulness in the fields of bioimaging and drug delivery. In this study, a single-step, high-efficiency hydrothermal method was applied to synthesize nitrogen and phosphorous-doped carbon dots （（N,P）-CDs） with a PLQY of up to 53.8% with independent emission behavior. Moreover, the CDs presented high monodispersity, robust excitation-independent luminescence, and stability over a large pH range. Spectroscopic investigations indicated that the PLQY of the （N,P）-CDs was primarily due to the addition of P and the passivation effect of the oxidized surface. The excellent fluorescence properties of （N,P）-CDs can be effectively and selectively quenched by Hg2~ ions. Such systems show a linear response in the 0-900 nM concentration range with a short response time, indicating their potential for applications in the fields of chemistry and biology.
