An expression of reflectance of fluorescent dyes in emission region was used in this article. Through the analysis of the spectral radiance factor of fluorescent whitening agents(FWA), the color matching of FWA was st...An expression of reflectance of fluorescent dyes in emission region was used in this article. Through the analysis of the spectral radiance factor of fluorescent whitening agents(FWA), the color matching of FWA was studied and the three-region method of color matching method was put forward. The method was proved to be reliable for the dyes used and was easy to apply for the color matching of FWAs.展开更多
Radionuclide contents in imported rice are determined using the EG&G ORTEC photon spectrometer system. Most of the natural radionuclides are found to have specific activities below the detectable limit. 40K has va...Radionuclide contents in imported rice are determined using the EG&G ORTEC photon spectrometer system. Most of the natural radionuclides are found to have specific activities below the detectable limit. 40K has values ranging from 0.104to 32.97 Bq/kg; 137Cs from 0.009 to 0.52 Bq/kg; and 95Zr less than 0.077 Bq/kg. The annual effective dose for a male and a female adult is 18μSv and 12.7μSv, respectively. Both are less than the value recommended by the International Commission of Radiological Protection.展开更多
Electron beam lithography(EBL) is a key technology in the fabrication of nanoscale silicon optical waveguide. The influence of exposure dose, the main process parameter of EBL, on the structure profile of poly-methyl ...Electron beam lithography(EBL) is a key technology in the fabrication of nanoscale silicon optical waveguide. The influence of exposure dose, the main process parameter of EBL, on the structure profile of poly-methyl methacrylate(PMMA) after development was studied using a silicon on insulator(SOI) wafer with 220 nm top silicon as the substrate. The relationship between exposure dose and structure pattern width after development was analyzed according to the measurement results. The optimum exposure dose of 220 μC/cm^(2) was found to obtain a final structure consistent with the designed mask value through subsequent processes. At the same time, according to the image segmentation curve tracking technology, the contour extraction process of the dose test results was carried out, and the relationship among mask design value, exposure dose and two-dimensional roughness of boundary contour was analyzed, which can provide reference for the subsequent electron beam lithography of the same substrate material.展开更多
Objective We aimed to determine the ef ects of low- and high-energy intensity-modulated radiation therapy （IMRT） photon beams on the target volume planning and on the critical organs in the case of prostate can-cer....Objective We aimed to determine the ef ects of low- and high-energy intensity-modulated radiation therapy （IMRT） photon beams on the target volume planning and on the critical organs in the case of prostate can-cer. Methods Thirty plans were generated by using either 6 MV or 15 MV beams separately, and a combination of both 6 and 15 MV beams. Al plans were generated by using suitable planning objectives and dose con-straints, which were identical across the plans, except the beam energy. The plans were analyzed in terms of their target coverage, conformity, and homogeneity, regardless of the beam energy. Results The mean percentage values of V70 Gy for the rectal wal for the plans with 6 MV, 15 MV, and mixed-energy beams were 16.9%, 17.8%, and 16.4%, respectively, while the mean percentage values of V40 Gy were 53.6%, 52.3%, and 50.4%. The mean dose values to the femoral heads for the 6 MV, 15 MV, and mixed-en-ergy plans were 30.1 Gy, 25.5 Gy, and 25.4 Gy, respectively. The mean integral dose for the 6 MV plans was 10% larger than those for the 15 MV and mixed-energy plans.Conclusion These preliminary results suggest that mixed-energy IMRT plans may be advantageous with respect to the dosimetric characteristics of low- and high-energy beams. Although the reduction of dose to the organs at risk may not be clinical y relevant, in this study, IMRT plans using mixed-energy beams exhibited better OAR sparing and overal higher plan quality for deep-seated tumors.展开更多
Objective： The aim of our study was to assess and compare the potential dosimetric advantages and drawbacks of photon beams and electron beams as a boost for the tumor bed in superficial and deep seated early-stage b...Objective： The aim of our study was to assess and compare the potential dosimetric advantages and drawbacks of photon beams and electron beams as a boost for the tumor bed in superficial and deep seated early-stage breast cancer. Methods： We planned CTs of 10 women with early breast cancer underwent breast conservative surgery were selected. Tumor bed was defined as superficial and deep with a cut of point 4 cm, those with less than 4 cm were defined as superficial tumors representing 4 patients and those with depth of 4 cm or more were classified as deep tumors representing 6 patients. The clinical target volume （C＇I＇V） was defined as the area of architectural .distortion surrounded by surgical clips. The plan- ning target volume （PTV） was the C＇I＇V plus margin 1 cm. A dose of 10 Gy.in 2 Gy fractions was given concurrently at the last week of treatment. Organs at risk （OARs） were heart, lungs, contra-lateral breast and a 5 mm thick skin segment of the breast surface. Dose volume histograms were defined to quantify the quality of concurrent treatment plans assessing target coverage and sparing OARs. The following treatment techniques were assessed： photon beam with 3D-conformal technique and a single electron beam. Results： For superficial tumors better coverage for CTV and P＇I＇V with good homogeneity with better CI was found for the 3D conformal radiotherapy （3DCRT） but with no significant planning objectives over electron beam. For deep tumors, the 3DCRT met the planning objectives for C＇I＇V, PTV with better coverage and fewer hot spots with better homogeneity and CI. For superficial tumors, OARs were spared by both techniques with better sparing for the electron beam where as for deep tumors also OARs were well spared by both techniques. Conclusion： Boosting the tumor bed in early- stage breast cancer with optimized photon may be preferred to electron beam for both superficial and deep tumors. The OARs dose sparing effect may allow for a potential long-term toxicity risk reduction and better cosmesis.展开更多
Objective The treatment planning system currently represents one of the basics of radiation therapy,because it is the only method to estimate patient dose delivery fast forward and accurately represent estimated tumor...Objective The treatment planning system currently represents one of the basics of radiation therapy,because it is the only method to estimate patient dose delivery fast forward and accurately represent estimated tumor location of the tumor with the possibility of estimating densities in the tissue surrounding the tumor to overcome dose calculation defects but radial estimated the patient.Despite the flaws associated with the systems and calculates the dose of your programs in all programs currently existing in the world.Than necessary,to the existence of a review of the accuracy of accounts and how to confirm the radiation dose to the patient programs.Methods A total of 35 cancer patients were considered for this study,with 245 field measurements made with low-and high-energy diode detectors for brain and prostate cases.The treatments for all patients were planned using Eclipse Treatment Planning System version 13.6.Results Of the 105 field measurements made for the prostate cancer patients,16 included discrepancies outside the ±5% action level.Of the 145 measurements taken of the brain cases,there were four outside the ±5% action level.The results indicated a higher degree of accuracy.The study revealed that,for the prostate measurements,the higher discrepancy in the doses for the particular fields(exceeding the action level) may have been due to the isocenter being very close to the jaws and multi-leaf collimator of the linear accelerator machine.As a result,scatter from the jaws and the multi-leaf collimator could have contributed to the high dose delivered to the diode;hence,a probable higher discrepancy of the dose in more brain cases due highest quality of VMAT technique and fixation system.Conclusion A greater percentage of the observed discrepancies were well within the set tolerance level.However,it is recommended that the positioning of the diode on the patient's skin and the angular sensitivity of the diodes be reconsidered.It is also recommended that a more accurate calculation of expected diode values be performed,especially for fields that pass through the table.These efforts would achieve action levels of ±5%.展开更多
From Sep. 3 of 2005 to Oct. 26, the HL-2A tokamak experiment carded out 42 days discharge operation, and successfully completed many experiments. These experiments include divertor operation, high density, molecular b...From Sep. 3 of 2005 to Oct. 26, the HL-2A tokamak experiment carded out 42 days discharge operation, and successfully completed many experiments. These experiments include divertor operation, high density, molecular beam injection, LHCD, siliconizafion. Experimental results create new records. The parameters achieved in that year were as follows： plasma current Ip = 320 kA, toroidal magnetic field BT=2.2 T, plasma density ne = 4.2×10^19 m^-3, plasma exist time tp = 1580 ms, plasma current plateau time is 1200 ms, electron temperature is 900 eV, ion temperature is 800 eV. To protect worker and public and assess neutron radiation level, we monitored neutron dose in radiation controlled area by the pulse neutron dose monitoring system, which was made by institude of high energy physics, chinese academy of sciences and southwestern institute of physics, china nation nuclear corporation （ CNNC ）.展开更多
Photosensitizers constitute a crucial element in the process of triplet-triplet annihilation upconversion,necessitating robust absorption of visible or near-infrared light,high intersystem crossing efficiency,prolonge...Photosensitizers constitute a crucial element in the process of triplet-triplet annihilation upconversion,necessitating robust absorption of visible or near-infrared light,high intersystem crossing efficiency,prolonged triplet state lifetime,and minimal energy dissipation during intersystem crossing and vibrational relaxation.Nonetheless,conventional monomeric photosensitizers frequently fail to simultaneously meet these requirements.In recent years,researchers,including our group,have fabricated photosensitizers that incorporate multiple covalent linkages,such as dyads and triads,which are regarded more likely to achieve comprehensive performance optimization.This review article explores the design and characteristics of recently synthesized dyads and triads photosensitizers that operate on the principles of intramolecular singlet energy transfer and intramolecular triplet energy transfer,demonstrating their outstanding efficacy in high-efficiency triplet-triplet annihilation upconversion.We provide an exhaustive explanation of the design rationales,photophysical,and photochemical properties of these photosensitizers,along with suggestions for the creation of photosensitizers with enhanced performance.Moreover,we discuss potential avenues and opportunities for the future development of triplet-triplet annihilation upconversion technology.展开更多
The development of low cost, metal free semiconductor photocatalysts for CO2 reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2 emissions. In this work, blac...The development of low cost, metal free semiconductor photocatalysts for CO2 reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2 emissions. In this work, black phosphorus quantum dots（BPQDs） were successfully dispersed on a graphitic carbon nitride（g-C3N4） support via a simple electrostatic attraction approach, and the activities of BP@g-C3N4 composites were evaluated for photocatalytic CO2 reduction. The BP@g-C3N4 composites displayed improved carrier separation efficiency and higher activities for photocatalytic CO2 reduction to CO（6.54 μmol g^-1h^-1 at the optimum BPQDs loading of 1 wt%） compared with pure g-C3N4（2.65 μmol g^-1h^-1）. This work thus identifies a novel approach towards metal free photocatalysts for CO2 photoreduction.展开更多
Band offset is a dominant factor affecting the photocatalytic performance of heterostructure photocatalysts. Therefore, controlling the band gap structure of semiconductors is a key challenge in the development of eff...Band offset is a dominant factor affecting the photocatalytic performance of heterostructure photocatalysts. Therefore, controlling the band gap structure of semiconductors is a key challenge in the development of efficient photocatalysts. We used a typical in situ-method to prepare diverse graphite-phase carbon nitride(g-C_3N_4)samples from melamine, thiourea, and a mixture thereof,and found that they exhibited band gaps between2.3–2.8 e V. From UV–Vis spectra and X-ray photoelectron spectroscopy measurements, we determined that the g-C_3N_4 samples exhibited different band gap values and valence band positions. On this basis, we constructed g-C_3N_4/m-La VO_4 heterojunctions with different band offsets. UV–Vis spectra and X-ray photoelectron spectroscopy measurements revealed that the valence band offsets(VBOs) of the different heterojunctions were similar, but their conduction band offsets(CBOs) were significantly different. Photocatalytic experiments revealed that the reaction rate was enhanced with an increase in the CBO value. Furthermore, the three-phase g-C_3N_4/g-C_3N_4/mLa VO_4 heterojunction composed of m-La VO_4 and mixed g-C_3N_4 showed the highest photocatalytic activity, which was mainly due to the construction of a multilevel structure. This work investigates the influence of the band offset on heterojunction photoelectrochemical properties and provides a new strategy to improve the photocatalytic activity by constructing multilevel structures.展开更多
文摘An expression of reflectance of fluorescent dyes in emission region was used in this article. Through the analysis of the spectral radiance factor of fluorescent whitening agents(FWA), the color matching of FWA was studied and the three-region method of color matching method was put forward. The method was proved to be reliable for the dyes used and was easy to apply for the color matching of FWAs.
文摘Radionuclide contents in imported rice are determined using the EG&G ORTEC photon spectrometer system. Most of the natural radionuclides are found to have specific activities below the detectable limit. 40K has values ranging from 0.104to 32.97 Bq/kg; 137Cs from 0.009 to 0.52 Bq/kg; and 95Zr less than 0.077 Bq/kg. The annual effective dose for a male and a female adult is 18μSv and 12.7μSv, respectively. Both are less than the value recommended by the International Commission of Radiological Protection.
基金Project(52175445) supported by the National Natural Science Foundation of ChinaProject(ZZYJKT2020-09) supported by the State Key Laboratory of High Performance Complex Manufacturing (Central South University),China+1 种基金Projects(2020JJ4247, 2022JJ30743) supported by the Natural Foundation of Hunan Province,ChinaProject(1053320190337) supported by the Fundamental Research Funds for the Central University,China。
文摘Electron beam lithography(EBL) is a key technology in the fabrication of nanoscale silicon optical waveguide. The influence of exposure dose, the main process parameter of EBL, on the structure profile of poly-methyl methacrylate(PMMA) after development was studied using a silicon on insulator(SOI) wafer with 220 nm top silicon as the substrate. The relationship between exposure dose and structure pattern width after development was analyzed according to the measurement results. The optimum exposure dose of 220 μC/cm^(2) was found to obtain a final structure consistent with the designed mask value through subsequent processes. At the same time, according to the image segmentation curve tracking technology, the contour extraction process of the dose test results was carried out, and the relationship among mask design value, exposure dose and two-dimensional roughness of boundary contour was analyzed, which can provide reference for the subsequent electron beam lithography of the same substrate material.
文摘Objective We aimed to determine the ef ects of low- and high-energy intensity-modulated radiation therapy （IMRT） photon beams on the target volume planning and on the critical organs in the case of prostate can-cer. Methods Thirty plans were generated by using either 6 MV or 15 MV beams separately, and a combination of both 6 and 15 MV beams. Al plans were generated by using suitable planning objectives and dose con-straints, which were identical across the plans, except the beam energy. The plans were analyzed in terms of their target coverage, conformity, and homogeneity, regardless of the beam energy. Results The mean percentage values of V70 Gy for the rectal wal for the plans with 6 MV, 15 MV, and mixed-energy beams were 16.9%, 17.8%, and 16.4%, respectively, while the mean percentage values of V40 Gy were 53.6%, 52.3%, and 50.4%. The mean dose values to the femoral heads for the 6 MV, 15 MV, and mixed-en-ergy plans were 30.1 Gy, 25.5 Gy, and 25.4 Gy, respectively. The mean integral dose for the 6 MV plans was 10% larger than those for the 15 MV and mixed-energy plans.Conclusion These preliminary results suggest that mixed-energy IMRT plans may be advantageous with respect to the dosimetric characteristics of low- and high-energy beams. Although the reduction of dose to the organs at risk may not be clinical y relevant, in this study, IMRT plans using mixed-energy beams exhibited better OAR sparing and overal higher plan quality for deep-seated tumors.
文摘Objective： The aim of our study was to assess and compare the potential dosimetric advantages and drawbacks of photon beams and electron beams as a boost for the tumor bed in superficial and deep seated early-stage breast cancer. Methods： We planned CTs of 10 women with early breast cancer underwent breast conservative surgery were selected. Tumor bed was defined as superficial and deep with a cut of point 4 cm, those with less than 4 cm were defined as superficial tumors representing 4 patients and those with depth of 4 cm or more were classified as deep tumors representing 6 patients. The clinical target volume （C＇I＇V） was defined as the area of architectural .distortion surrounded by surgical clips. The plan- ning target volume （PTV） was the C＇I＇V plus margin 1 cm. A dose of 10 Gy.in 2 Gy fractions was given concurrently at the last week of treatment. Organs at risk （OARs） were heart, lungs, contra-lateral breast and a 5 mm thick skin segment of the breast surface. Dose volume histograms were defined to quantify the quality of concurrent treatment plans assessing target coverage and sparing OARs. The following treatment techniques were assessed： photon beam with 3D-conformal technique and a single electron beam. Results： For superficial tumors better coverage for CTV and P＇I＇V with good homogeneity with better CI was found for the 3D conformal radiotherapy （3DCRT） but with no significant planning objectives over electron beam. For deep tumors, the 3DCRT met the planning objectives for C＇I＇V, PTV with better coverage and fewer hot spots with better homogeneity and CI. For superficial tumors, OARs were spared by both techniques with better sparing for the electron beam where as for deep tumors also OARs were well spared by both techniques. Conclusion： Boosting the tumor bed in early- stage breast cancer with optimized photon may be preferred to electron beam for both superficial and deep tumors. The OARs dose sparing effect may allow for a potential long-term toxicity risk reduction and better cosmesis.
文摘Objective The treatment planning system currently represents one of the basics of radiation therapy,because it is the only method to estimate patient dose delivery fast forward and accurately represent estimated tumor location of the tumor with the possibility of estimating densities in the tissue surrounding the tumor to overcome dose calculation defects but radial estimated the patient.Despite the flaws associated with the systems and calculates the dose of your programs in all programs currently existing in the world.Than necessary,to the existence of a review of the accuracy of accounts and how to confirm the radiation dose to the patient programs.Methods A total of 35 cancer patients were considered for this study,with 245 field measurements made with low-and high-energy diode detectors for brain and prostate cases.The treatments for all patients were planned using Eclipse Treatment Planning System version 13.6.Results Of the 105 field measurements made for the prostate cancer patients,16 included discrepancies outside the ±5% action level.Of the 145 measurements taken of the brain cases,there were four outside the ±5% action level.The results indicated a higher degree of accuracy.The study revealed that,for the prostate measurements,the higher discrepancy in the doses for the particular fields(exceeding the action level) may have been due to the isocenter being very close to the jaws and multi-leaf collimator of the linear accelerator machine.As a result,scatter from the jaws and the multi-leaf collimator could have contributed to the high dose delivered to the diode;hence,a probable higher discrepancy of the dose in more brain cases due highest quality of VMAT technique and fixation system.Conclusion A greater percentage of the observed discrepancies were well within the set tolerance level.However,it is recommended that the positioning of the diode on the patient's skin and the angular sensitivity of the diodes be reconsidered.It is also recommended that a more accurate calculation of expected diode values be performed,especially for fields that pass through the table.These efforts would achieve action levels of ±5%.
文摘From Sep. 3 of 2005 to Oct. 26, the HL-2A tokamak experiment carded out 42 days discharge operation, and successfully completed many experiments. These experiments include divertor operation, high density, molecular beam injection, LHCD, siliconizafion. Experimental results create new records. The parameters achieved in that year were as follows： plasma current Ip = 320 kA, toroidal magnetic field BT=2.2 T, plasma density ne = 4.2×10^19 m^-3, plasma exist time tp = 1580 ms, plasma current plateau time is 1200 ms, electron temperature is 900 eV, ion temperature is 800 eV. To protect worker and public and assess neutron radiation level, we monitored neutron dose in radiation controlled area by the pulse neutron dose monitoring system, which was made by institude of high energy physics, chinese academy of sciences and southwestern institute of physics, china nation nuclear corporation （ CNNC ）.
基金supported by the National Natural Science Foundation of China(No.22203004 and No.21927814)the Anhui Normal University 2023 Scholarship and Supplementary Discipline Construction Project(No.2023GFXK160).
文摘Photosensitizers constitute a crucial element in the process of triplet-triplet annihilation upconversion,necessitating robust absorption of visible or near-infrared light,high intersystem crossing efficiency,prolonged triplet state lifetime,and minimal energy dissipation during intersystem crossing and vibrational relaxation.Nonetheless,conventional monomeric photosensitizers frequently fail to simultaneously meet these requirements.In recent years,researchers,including our group,have fabricated photosensitizers that incorporate multiple covalent linkages,such as dyads and triads,which are regarded more likely to achieve comprehensive performance optimization.This review article explores the design and characteristics of recently synthesized dyads and triads photosensitizers that operate on the principles of intramolecular singlet energy transfer and intramolecular triplet energy transfer,demonstrating their outstanding efficacy in high-efficiency triplet-triplet annihilation upconversion.We provide an exhaustive explanation of the design rationales,photophysical,and photochemical properties of these photosensitizers,along with suggestions for the creation of photosensitizers with enhanced performance.Moreover,we discuss potential avenues and opportunities for the future development of triplet-triplet annihilation upconversion technology.
基金supported by the National Natural Science Foundation of China (51502146, U1404506, 21671113, 51772305, 51572270, and U1662118)the International Partnership Program of Chinese Academy of Sciences (GJHZ1819)+1 种基金the Royal Society-Newton Advanced Fellowship (NA170422)supported by Open Fund (PEBM201702) of Key Laboratory for Photonic and Electric Bandgap Materials, Ministry of Education (Harbin Normal University)
文摘The development of low cost, metal free semiconductor photocatalysts for CO2 reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2 emissions. In this work, black phosphorus quantum dots（BPQDs） were successfully dispersed on a graphitic carbon nitride（g-C3N4） support via a simple electrostatic attraction approach, and the activities of BP@g-C3N4 composites were evaluated for photocatalytic CO2 reduction. The BP@g-C3N4 composites displayed improved carrier separation efficiency and higher activities for photocatalytic CO2 reduction to CO（6.54 μmol g^-1h^-1 at the optimum BPQDs loading of 1 wt%） compared with pure g-C3N4（2.65 μmol g^-1h^-1）. This work thus identifies a novel approach towards metal free photocatalysts for CO2 photoreduction.
基金supported by the National Natural Science Foundation of China(21173131)the Taishan Scholar Project of Shandong Province
文摘Band offset is a dominant factor affecting the photocatalytic performance of heterostructure photocatalysts. Therefore, controlling the band gap structure of semiconductors is a key challenge in the development of efficient photocatalysts. We used a typical in situ-method to prepare diverse graphite-phase carbon nitride(g-C_3N_4)samples from melamine, thiourea, and a mixture thereof,and found that they exhibited band gaps between2.3–2.8 e V. From UV–Vis spectra and X-ray photoelectron spectroscopy measurements, we determined that the g-C_3N_4 samples exhibited different band gap values and valence band positions. On this basis, we constructed g-C_3N_4/m-La VO_4 heterojunctions with different band offsets. UV–Vis spectra and X-ray photoelectron spectroscopy measurements revealed that the valence band offsets(VBOs) of the different heterojunctions were similar, but their conduction band offsets(CBOs) were significantly different. Photocatalytic experiments revealed that the reaction rate was enhanced with an increase in the CBO value. Furthermore, the three-phase g-C_3N_4/g-C_3N_4/mLa VO_4 heterojunction composed of m-La VO_4 and mixed g-C_3N_4 showed the highest photocatalytic activity, which was mainly due to the construction of a multilevel structure. This work investigates the influence of the band offset on heterojunction photoelectrochemical properties and provides a new strategy to improve the photocatalytic activity by constructing multilevel structures.
