In recent years, topological insulators have aroused the attention of a great number of scientists due to their unique electronic structures and peculiar physical properties. Triggered by the similar electronic struct...In recent years, topological insulators have aroused the attention of a great number of scientists due to their unique electronic structures and peculiar physical properties. Triggered by the similar electronic structures as graphene, the broadband nonlinear absorption properties of topological insulator were investigated. Moreover, the mode-locked or Q-switched fiber lasers based on topological insulator were realized for broadband operating wavelength. Here, we present an overview of the preparation, transferring, linear and nonlinear optical properties and their applications of topological insulators in pulsed fiber lasers. The pulsed fiber lasers towards mid- infrared regimes have been proposed.展开更多
Germ cell tumors complicated by hematological malignancy(HM)are a rare clinical phenomenon.Allogeneic hematopoietic stem cell transplantation(allo-HSCT)is a potentially effective therapy,but graft-versus-host disease(...Germ cell tumors complicated by hematological malignancy(HM)are a rare clinical phenomenon.Allogeneic hematopoietic stem cell transplantation(allo-HSCT)is a potentially effective therapy,but graft-versus-host disease(GVHD)is a life-threatening complication.We report a case of a 13-year-old female patient diagnosed with germ cell tumors followed by acute lymphoblastic leukemia.After chemotherapy,she received allo-HSCT and her chimerism rate decreased rapidly to near zero by 6 months without evidence of HM recurrence.However,she developed severe,multiorgan GVHD-like manifestations.DNA analysis revealed the pathogenesis of GVHD to be loss of HLA heterozygosity in recipient hematopoietic cells.展开更多
Nitrogen pollution is an increasingly severe worldwide problem because of drainage of nitrogen-containing wastewater and intensive application of nitrogen-containing fertilizers. Denitrification, a key process in nitr...Nitrogen pollution is an increasingly severe worldwide problem because of drainage of nitrogen-containing wastewater and intensive application of nitrogen-containing fertilizers. Denitrification, a key process in nitrogen cycles, is commonly employed for nitrogen removal in engineered wastewater treatment systems. Biological denitrification is performed by denitrifying microbes(bacteria) that use nitrate as terminal electron acceptor. Better understanding the functions of diverse microbial populations in denitrification-based wastewater treatment systems, and the interactions of these populations with operating environments, is essential for improving both treatment performance and system stability. Recent advances in "meta-omics"(e.g., genomics, transcriptomics, proteomics, metabolomics), other molecular biology tools, and microbiome analysis have greatly enhanced such understanding. This minireview summarizes recent findings regarding microbial community structure and composition, key functional microbes and their physiology, functional genes involved in nitrogen cycle, and responses of microbes and their genes to changes of environmental factors or operating parameters, in denitrification processes in wastewater treatment systems. Of particular interest are heterotrophic denitrification systems(which require alternative organic carbon sources) and the autotrophic denitrification systems(which do not require an external carbon source). Integrated microbiome and-omics approaches have great future potential for determination of optimal environmental and biotechnological parameters,novel process development, and improvement of nitrogen removal efficiency and system stability.展开更多
Doping, which is the intentional introducti on of impurities into a material, can improve the metal-semiconductor interface by reducing Schottky barrier width. Here, we prese nt high-quality two-dime nsional SnS2 nano...Doping, which is the intentional introducti on of impurities into a material, can improve the metal-semiconductor interface by reducing Schottky barrier width. Here, we prese nt high-quality two-dime nsional SnS2 nano sheets with well-controlled Sb dopi ng concen tration via direct vapor growth approach and following micromechanical cleavage process. X-ray photoelectro n spectroscopy (XPS) measureme nt dem on strates that Sb contents of the doped samples are approximately 0.22%, 0.34% and 1.21%, respectively, and doping in duces the upward shift of the Fermi level with respect to the pristi ne SnS2. Tran smissio n electro n microscopy (TEM) characterizatio n exhibits that Sb-doped SnS2 nano sheets have a high-quality hexagonal symmetry structure and Sb element is uniformly distributed in the nano sheets. The phototra nsistors based on the Sb-doped SnS2 mono layers show n-type behavior with high mobility which is one order of magn itude higher than that of pristi ne SnS2 phototra nsistors. The photorespo nsivity and exter nal quantum efficiency (EQE) of Sb-S nS2 mono layers phototra nsistors are approximately three orders of magnitude higher than that of pristine SnS2 phototransistor. The results suggest that the method of reducing Shottky barrier width to achieve high mobility and photoresp on sivity is effective, and Sb-doped SnS2 mono layer has significant potential in future nanoelectronic and optoelectronic applications.展开更多
Two-dimensional (2D) van der Waals (vdWs) metal-semiconductor heterostructures with atomically sharp interface and matched work functions have recently attracted great attention due to their unique electronic and opto...Two-dimensional (2D) van der Waals (vdWs) metal-semiconductor heterostructures with atomically sharp interface and matched work functions have recently attracted great attention due to their unique electronic and optoelectronic properties. Here we report the vapor phase epitaxial growth of large-scale vertical Sb/WSe2 metal-semiconductor vdWs heterostructures with uniform stacking orientation. Compared with the growth on S1O2/S1 substrate, the thick ness of Sb nan osheet on WSe2 can be reduced effectively to mono layer. We con struct Sb-WSe2-Au asymmetric electrodes photodiode based on the Sb/WSe2 heterostructures. Electrical transport measurements indicate that the photodiode show obvious rectifying effect. Optoelectronic characterizations show prominent photoresponse with a high photoresposivity of 364 mA/W, a fast response time of less than 8 ms, a large open-circuit voltage of 0.27 V and a maximum electrical power output of 0.11 nW. The direct growth of high-quality metal-semiconductor vdWs heterostructures may open up new realms in 2D functional electronics and optoelectronics.展开更多
Ultrafast fiber lasers are in great demand for various applications, such as optical communication, spectroscopy,biomedical diagnosis, and industrial fabrication. Here, we report the highly stable femtosecond pulse ge...Ultrafast fiber lasers are in great demand for various applications, such as optical communication, spectroscopy,biomedical diagnosis, and industrial fabrication. Here, we report the highly stable femtosecond pulse generation from a MXene mode-locked fiber laser. We have prepared the high-quality Ti_3C_2 T_x nanosheets via the etching method, and characterized their ultrafast dynamics and broadband nonlinear optical responses. The obvious intensity-and wavelength-dependent nonlinear responses have been observed and investigated. In addition, a highly stable femtosecond fiber laser with signal-to-noise ratio up to 70.7 dB and central wavelength of 1567.3 nm has been delivered. The study may provide some valuable design guidelines for the development of ultrafast, broadband nonlinear optical modulators, and open new avenues toward advanced photonic devices based on MXenes.展开更多
Gapless linear energy dispersion of graphene endows it with unique nonlinear optical properties, including broadband nonlinear absorption and giant nonlinear refractive index. Herein, we experimentally observed that f...Gapless linear energy dispersion of graphene endows it with unique nonlinear optical properties, including broadband nonlinear absorption and giant nonlinear refractive index. Herein, we experimentally observed that fewlayers graphene has obvious nonlinear absorption and large nonlinear refraction, as investigated by the Z-scan technique in the mid-infrared(mid-IR) regime. Our study may not only, for the first time to our knowledge, verify the giant nonlinear refractive index of graphene(~10-7cm2∕W) at the mid-IR, which is 7 orders of magnitude larger than other conventional bulk materials, but also provide some new insights for graphene-based mid-IR photonics,potentially leading to the emergence of several new conceptual mid-IR optoelectronics devices.展开更多
MXenes,a new class of 2D transition metal carbides,nitrides,and carbonitrides,have attracted much attention due to their outstanding properties.Here,we report the broadband spatial self-phase modulation of Ti2CTx MXen...MXenes,a new class of 2D transition metal carbides,nitrides,and carbonitrides,have attracted much attention due to their outstanding properties.Here,we report the broadband spatial self-phase modulation of Ti2CTx MXene nanosheets dispersed in deionized water in the visible to near-infrared regime,highlighting the broadband nonlinear optical(NLO)response of Ti2CTx MXene.Using ultrafast pulsed laser excitation,the nonlinear refractive index n2 and the thirdorder nonlinear susceptibility χ^(3)monolayer of Ti2CTx MXene were measured to be^10^−13 m^2/W and ~10^−10 esu,respectively.Leveraging the large optical nonlinearity of Ti2CTx MXene,an all-optical modulator in the visible regime was fabricated based on the spatial cross-phase modulation effect.This work suggests that 2D MXenes are ideal broadband NLO materials with excellent prospects in NLO applications.展开更多
Mid-infrared pulsed lasers operating around the 3 μm wavelength regime are important for a wide range of applications including sensing, spectroscopy, imaging, etc. Despite the recent advances in technology, the lack...Mid-infrared pulsed lasers operating around the 3 μm wavelength regime are important for a wide range of applications including sensing, spectroscopy, imaging, etc. Despite the recent advances in technology, the lack of a nonlinear optical modulator operating in the mid-infrared regime remains a significant challenge. Here, we report the third-order nonlinear optical response of gold nanorods(GNRs) ranging from 800 nm to the mid-infrared regime(2810 nm) enabled by their size and overlapping behavior-dependent longitudinal surface plasmon resonance. In addition, we demonstrate a wavelength-tunable Er3+-doped fluoride fiber laser modulated by GNRs, which can deliver pulsed laser output, with the pulse duration down to 533 ns, tunable wavelength ranging from 2760.2 to 2810.0 nm, and spectral 3 d B bandwidth of about 1 nm. The experimental results not only validate the GNRs’ robust mid-infrared nonlinear optical response, but also manifest their application potential in high-performance broadband optoelectronic devices.展开更多
基金supported by 2018 scientific and technological research projectsin Henan Province(192102310430)Special Project of Chinese Medicine Research in Henan Province(2019ZYZD06)。
基金supported by the National Natural Science Foundation of China under Grant No.61475102
文摘In recent years, topological insulators have aroused the attention of a great number of scientists due to their unique electronic structures and peculiar physical properties. Triggered by the similar electronic structures as graphene, the broadband nonlinear absorption properties of topological insulator were investigated. Moreover, the mode-locked or Q-switched fiber lasers based on topological insulator were realized for broadband operating wavelength. Here, we present an overview of the preparation, transferring, linear and nonlinear optical properties and their applications of topological insulators in pulsed fiber lasers. The pulsed fiber lasers towards mid- infrared regimes have been proposed.
文摘Germ cell tumors complicated by hematological malignancy(HM)are a rare clinical phenomenon.Allogeneic hematopoietic stem cell transplantation(allo-HSCT)is a potentially effective therapy,but graft-versus-host disease(GVHD)is a life-threatening complication.We report a case of a 13-year-old female patient diagnosed with germ cell tumors followed by acute lymphoblastic leukemia.After chemotherapy,she received allo-HSCT and her chimerism rate decreased rapidly to near zero by 6 months without evidence of HM recurrence.However,she developed severe,multiorgan GVHD-like manifestations.DNA analysis revealed the pathogenesis of GVHD to be loss of HLA heterozygosity in recipient hematopoietic cells.
基金supported by the projects of National Key Research and Development Program of China (2016YFD0501409)
文摘Nitrogen pollution is an increasingly severe worldwide problem because of drainage of nitrogen-containing wastewater and intensive application of nitrogen-containing fertilizers. Denitrification, a key process in nitrogen cycles, is commonly employed for nitrogen removal in engineered wastewater treatment systems. Biological denitrification is performed by denitrifying microbes(bacteria) that use nitrate as terminal electron acceptor. Better understanding the functions of diverse microbial populations in denitrification-based wastewater treatment systems, and the interactions of these populations with operating environments, is essential for improving both treatment performance and system stability. Recent advances in "meta-omics"(e.g., genomics, transcriptomics, proteomics, metabolomics), other molecular biology tools, and microbiome analysis have greatly enhanced such understanding. This minireview summarizes recent findings regarding microbial community structure and composition, key functional microbes and their physiology, functional genes involved in nitrogen cycle, and responses of microbes and their genes to changes of environmental factors or operating parameters, in denitrification processes in wastewater treatment systems. Of particular interest are heterotrophic denitrification systems(which require alternative organic carbon sources) and the autotrophic denitrification systems(which do not require an external carbon source). Integrated microbiome and-omics approaches have great future potential for determination of optimal environmental and biotechnological parameters,novel process development, and improvement of nitrogen removal efficiency and system stability.
基金the National Natural Science Foundation of China (Nos. 61804050, 51872086, 61622406, 11674310, and 61571415)the Double First-Class Initiative of Hunan University (No. 531109100004)the Fundamental Research Funds of the Central Universities (Nos. 531107051078 and 531107051055).
文摘Doping, which is the intentional introducti on of impurities into a material, can improve the metal-semiconductor interface by reducing Schottky barrier width. Here, we prese nt high-quality two-dime nsional SnS2 nano sheets with well-controlled Sb dopi ng concen tration via direct vapor growth approach and following micromechanical cleavage process. X-ray photoelectro n spectroscopy (XPS) measureme nt dem on strates that Sb contents of the doped samples are approximately 0.22%, 0.34% and 1.21%, respectively, and doping in duces the upward shift of the Fermi level with respect to the pristi ne SnS2. Tran smissio n electro n microscopy (TEM) characterizatio n exhibits that Sb-doped SnS2 nano sheets have a high-quality hexagonal symmetry structure and Sb element is uniformly distributed in the nano sheets. The phototra nsistors based on the Sb-doped SnS2 mono layers show n-type behavior with high mobility which is one order of magn itude higher than that of pristi ne SnS2 phototra nsistors. The photorespo nsivity and exter nal quantum efficiency (EQE) of Sb-S nS2 mono layers phototra nsistors are approximately three orders of magnitude higher than that of pristine SnS2 phototransistor. The results suggest that the method of reducing Shottky barrier width to achieve high mobility and photoresp on sivity is effective, and Sb-doped SnS2 mono layer has significant potential in future nanoelectronic and optoelectronic applications.
基金the National Natural Science Foundation of China (Nos. 61804050 and 51872086)the Double First-Class Initiative of Hunan University (No. 531109100004)the Fundamental Research Funds of the Central Universities (Nos. 531107051078 and 531107051055).
文摘Two-dimensional (2D) van der Waals (vdWs) metal-semiconductor heterostructures with atomically sharp interface and matched work functions have recently attracted great attention due to their unique electronic and optoelectronic properties. Here we report the vapor phase epitaxial growth of large-scale vertical Sb/WSe2 metal-semiconductor vdWs heterostructures with uniform stacking orientation. Compared with the growth on S1O2/S1 substrate, the thick ness of Sb nan osheet on WSe2 can be reduced effectively to mono layer. We con struct Sb-WSe2-Au asymmetric electrodes photodiode based on the Sb/WSe2 heterostructures. Electrical transport measurements indicate that the photodiode show obvious rectifying effect. Optoelectronic characterizations show prominent photoresponse with a high photoresposivity of 364 mA/W, a fast response time of less than 8 ms, a large open-circuit voltage of 0.27 V and a maximum electrical power output of 0.11 nW. The direct growth of high-quality metal-semiconductor vdWs heterostructures may open up new realms in 2D functional electronics and optoelectronics.
基金National Natural Science Foundation of China(NSFC)(11574079,61475102,61775056)Natural Science Foundation of Hunan Province(2017JJ1013)Ministry of Education of the People’s Republic of China(MOE)(6141A02033404)
文摘Ultrafast fiber lasers are in great demand for various applications, such as optical communication, spectroscopy,biomedical diagnosis, and industrial fabrication. Here, we report the highly stable femtosecond pulse generation from a MXene mode-locked fiber laser. We have prepared the high-quality Ti_3C_2 T_x nanosheets via the etching method, and characterized their ultrafast dynamics and broadband nonlinear optical responses. The obvious intensity-and wavelength-dependent nonlinear responses have been observed and investigated. In addition, a highly stable femtosecond fiber laser with signal-to-noise ratio up to 70.7 dB and central wavelength of 1567.3 nm has been delivered. The study may provide some valuable design guidelines for the development of ultrafast, broadband nonlinear optical modulators, and open new avenues toward advanced photonic devices based on MXenes.
基金supported by the National 973 Program of China (Grant No. 2012CB315701)the National Natural Science Foundation of China (Grant Nos. 61205125, 61222505, and 61475102)
文摘Gapless linear energy dispersion of graphene endows it with unique nonlinear optical properties, including broadband nonlinear absorption and giant nonlinear refractive index. Herein, we experimentally observed that fewlayers graphene has obvious nonlinear absorption and large nonlinear refraction, as investigated by the Z-scan technique in the mid-infrared(mid-IR) regime. Our study may not only, for the first time to our knowledge, verify the giant nonlinear refractive index of graphene(~10-7cm2∕W) at the mid-IR, which is 7 orders of magnitude larger than other conventional bulk materials, but also provide some new insights for graphene-based mid-IR photonics,potentially leading to the emergence of several new conceptual mid-IR optoelectronics devices.
基金National Science Foundation,Grant/Award Number:MoMS 1930881China Scholarship Council,Grant/Award Number:201706130028+6 种基金National Natural Science Fund Foundation of China,Grant/Award Number:61775056Natural Science Foundation of Hunan Province,Grant/Award Number:2017JJ1013Research Fund of Science and Technology on Plasma Physics Laboratory,Grant/Award Number:6142A0403050717This work was supported by the National Natural Science Foundation of China(NSFC)(61775056)Natural Science Foundation of Hunan Province(2017JJ1013)Research Fund of Science and Technology on Plasma Physics Laboratory(6142A0403050717)The support provided by China Scholarship Council(CSC)during a visit of Jun Yi to Clemson University is acknowledged.This material is based upon work supported by the National Science Foundation under Grant No.MoMS 1930881.
文摘MXenes,a new class of 2D transition metal carbides,nitrides,and carbonitrides,have attracted much attention due to their outstanding properties.Here,we report the broadband spatial self-phase modulation of Ti2CTx MXene nanosheets dispersed in deionized water in the visible to near-infrared regime,highlighting the broadband nonlinear optical(NLO)response of Ti2CTx MXene.Using ultrafast pulsed laser excitation,the nonlinear refractive index n2 and the thirdorder nonlinear susceptibility χ^(3)monolayer of Ti2CTx MXene were measured to be^10^−13 m^2/W and ~10^−10 esu,respectively.Leveraging the large optical nonlinearity of Ti2CTx MXene,an all-optical modulator in the visible regime was fabricated based on the spatial cross-phase modulation effect.This work suggests that 2D MXenes are ideal broadband NLO materials with excellent prospects in NLO applications.
基金National Natural Science Foundation of China(NSFC)(11474132,11574079,61378004,61527823,61605166,61605219,61775056)Science and Technology Project of Jilin Province(20160520085JH)+1 种基金Natural Science Foundation of Hunan Province(2017JJ1013)Youth Innovation Promotion Association of the Chinese Academy of Sciences
文摘Mid-infrared pulsed lasers operating around the 3 μm wavelength regime are important for a wide range of applications including sensing, spectroscopy, imaging, etc. Despite the recent advances in technology, the lack of a nonlinear optical modulator operating in the mid-infrared regime remains a significant challenge. Here, we report the third-order nonlinear optical response of gold nanorods(GNRs) ranging from 800 nm to the mid-infrared regime(2810 nm) enabled by their size and overlapping behavior-dependent longitudinal surface plasmon resonance. In addition, we demonstrate a wavelength-tunable Er3+-doped fluoride fiber laser modulated by GNRs, which can deliver pulsed laser output, with the pulse duration down to 533 ns, tunable wavelength ranging from 2760.2 to 2810.0 nm, and spectral 3 d B bandwidth of about 1 nm. The experimental results not only validate the GNRs’ robust mid-infrared nonlinear optical response, but also manifest their application potential in high-performance broadband optoelectronic devices.