Encouraging and astonishing developments have recently been achieved in image-based diagnostic technology.Modern medical care and imaging technology are becoming increasingly inseparable.However,the current diagnosis ...Encouraging and astonishing developments have recently been achieved in image-based diagnostic technology.Modern medical care and imaging technology are becoming increasingly inseparable.However,the current diagnosis pattern of signal to image to knowledge inevitably leads to information distortion and noise introduction in the procedure of image reconstruction(from signal to image).Artificial intelligence(AI)technologies that can mine knowledge from vast amounts of data offer opportunities to disrupt established workflows.In this prospective study,for the first time,we develop an AI-based signal-toknowledge diagnostic scheme for lung nodule classification directly from the computed tomography(CT)raw data(the signal).We find that the raw data achieves almost comparable performance with CT,indicating that it is possible to diagnose diseases without reconstructing images.Moreover,the incorporation of raw data through three common convolutional network structures greatly improves the performance of the CT models in all cohorts(with a gain ranging from 0.01 to 0.12),demonstrating that raw data contains diagnostic information that CT does not possess.Our results break new ground and demonstrate the potential for direct signal-to-knowledge domain analysis.展开更多
Camouflaged people are extremely expert in actively concealing themselves by effectively utilizing cover and the surrounding environment. Despite advancements in optical detection capabilities through imaging systems,...Camouflaged people are extremely expert in actively concealing themselves by effectively utilizing cover and the surrounding environment. Despite advancements in optical detection capabilities through imaging systems, including spectral, polarization, and infrared technologies, there is still a lack of effective real-time method for accurately detecting small-size and high-efficient camouflaged people in complex real-world scenes. Here, this study proposes a snapshot multispectral image-based camouflaged detection model, multispectral YOLO(MS-YOLO), which utilizes the SPD-Conv and Sim AM modules to effectively represent targets and suppress background interference by exploiting the spatial-spectral target information. Besides, the study constructs the first real-shot multispectral camouflaged people dataset(MSCPD), which encompasses diverse scenes, target scales, and attitudes. To minimize information redundancy, MS-YOLO selects an optimal subset of 12 bands with strong feature representation and minimal inter-band correlation as input. Through experiments on the MSCPD, MS-YOLO achieves a mean Average Precision of 94.31% and real-time detection at 65 frames per second, which confirms the effectiveness and efficiency of our method in detecting camouflaged people in various typical desert and forest scenes. Our approach offers valuable support to improve the perception capabilities of unmanned aerial vehicles in detecting enemy forces and rescuing personnel in battlefield.展开更多
Existing lithospheric velocity models exhibit similar structures typically associated with the first-order tectonic features,with dissimilarities due to different data and methods used in model generation.The quantifi...Existing lithospheric velocity models exhibit similar structures typically associated with the first-order tectonic features,with dissimilarities due to different data and methods used in model generation.The quantification of model structural similarity can help in interpreting the geophysical properties of Earth's interior and establishing unified models crucial in natural hazard assessment and resource exploration.Here we employ the complex wavelet structural similarity index measure(CW-SSIM)active in computer image processing to analyze the structural similarity of four lithospheric velocity models of Chinese mainland published in the past decade.We take advantage of this method in its multiscale definition and insensitivity to slight geometrical distortion like translation and scaling,which is particularly crucial in the structural similarity analysis of velocity models accounting for uncertainty and resolution.Our results show that the CW-SSIM values vary in different model pairs,horizontal locations,and depths.While variations in the inter-model CW-SSIM are partly owing to different databases in the model generation,the difference of tomography methods may significantly impact the similar structural features of models,such as the low similarities between the full-wave based FWEA18 and other three models in northeastern China.We finally suggest potential solutions for the next generation of tomographic modeling in different areas according to corresponding structural similarities of existing models.展开更多
Complex plasma widely exists in thin film deposition,material surface modification,and waste gas treatment in industrial plasma processes.During complex plasma discharge,the configuration,distribution,and size of part...Complex plasma widely exists in thin film deposition,material surface modification,and waste gas treatment in industrial plasma processes.During complex plasma discharge,the configuration,distribution,and size of particles,as well as the discharge glow,strongly depend on discharge parameters.However,traditional manual diagnosis methods for recognizing discharge parameters from discharge images are complicated to operate with low accuracy,time-consuming and high requirement of instruments.To solve these problems,by combining the two mechanisms of attention mechanism(strengthening the extraction of the channel feature)and shortcut connection(enabling the input information to be directly transmitted to deep networks and avoiding the disappearance or explosion of gradients),the network of squeeze and excitation convolution with shortcut(SECS)for complex plasma image recognition is proposed to effectively improve the model performance.The results show that the accuracy,precision,recall and F1-Score of our model are superior to other models in complex plasma image recognition,and the recognition accuracy reaches 97.38%.Moreover,the recognition accuracy for the Flowers and Chest X-ray publicly available data sets reaches 97.85%and 98.65%,respectively,and our model has robustness.This study shows that the proposed model provides a new method for the diagnosis of complex plasma images and also provides technical support for the application of plasma in industrial production.展开更多
With the acceleration of urbanization and the improvement of people’s living standards,people have increasingly higher requirements for the living environment,especially in the design of outdoor balconies.However,exi...With the acceleration of urbanization and the improvement of people’s living standards,people have increasingly higher requirements for the living environment,especially in the design of outdoor balconies.However,existing landscape balconies generally suffer from insufficient shading and rainwater drainage problems,which affects people’s living experience.In response to this problem,this article proposes a new design scheme for building landscape balconies to solve the existing problems of landscape balconies.This design plan fully considers the user’s usage needs and scenarios,improves the use value and comfort of the balcony through technical means,and achieves intelligence and functionality.展开更多
AIM： To investigate the anti-tumor activity of ursolic acid （UA） and its derivatives isolated from Aralia decaisneana on hepatocellular carcinoma both in vitro and in vivo. METHODS： In vivo cytotoxicity was first ...AIM： To investigate the anti-tumor activity of ursolic acid （UA） and its derivatives isolated from Aralia decaisneana on hepatocellular carcinoma both in vitro and in vivo. METHODS： In vivo cytotoxicity was first screened by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide （MTT） assay. Morphological observation, DNA ladder, flow cytometry analysis, Western blot and real time PCR were employed to elucidate the cytotoxic mechanism of UA. Implanted mouse hepatoma H22 was used to evaluate the growth inhibitory effect of UA in vivo . RESULTS： UA could significantly inhibit the proliferation of HepG2 and its drug-resistance strain, R-HepG2 cells, but had no inhibitory effect on primarily cultured normal mouse hepatocytes whereas all the six derivatives of UA could not inhibit the growth of all tested cell lines. Further study on mechanism demonstrated that apoptosis and G0/G1 arrest were involved in the cytotoxicity and cleavage of poly-（ADP-ribose）- polymerase （PARP）. Downregulation of cyclooxygenase-2 （COX-2） protein and upregulation of heat shock protein （HSP） 105 mRNA correlated to the apoptosis of HepG2 cells treated with UA. In addition, UA also could inhibit the growth of H22 hepatoma in vivo. CONCLUSION： UA is a promising anti-tumor agent, but further work needs to be done to improve its solubility.展开更多
Piezocatalytic materials have been widely used for catalytic hydrogen evolution and purification of organic contaminants.However,most studies focus on nano-size and/or polycrystalline catalysts,suffering from aggregat...Piezocatalytic materials have been widely used for catalytic hydrogen evolution and purification of organic contaminants.However,most studies focus on nano-size and/or polycrystalline catalysts,suffering from aggregation and neutralization of internal piezoelectric field caused by polydomains.Here we report a single crystal ZnO of large size and few bulk defects crafted by a hydrothermal method for piezocatalytic hydrogen generation from pure water.It is noteworthy that single-side surface areas of both original as-prepared ZnO and Ga-doped ZnO bulk crystals are larger than 30 cm^(2).The high quality of ZnO and Ga-doped ZnO bulks are further uncovered by high-resolution transmission electron microscope(HRTEM),photoluminescence(PL)and X-ray diffraction(XRD).Remarkably,an outstanding hydrogen production rate of co-catalyst-free Ga-doped ZnO bulk crystal(i.e.,a maximum rate of 5915μmol h^(-1) m^(-2))is observed in pure water triggered by ultrasound in dark,which is over 100 times higher than that of its powder counterpart(i.e.,52.54μmol h^(-1) m^(-2)).The piezocatalytic performance of ZnO bulk crystal is systematically studied in terms of varied exposed crystal facet,thickness and conductivity.Different piezocatalytic performances are attributed to magnitude and distribution of piezoelectric potential,revealed by the finite element method(FEM)simulation.The density functional theory(DFT)calculations are employed to investigate the piezocatalytic hydrogen evolution process,indicating a strong H_(2)O adsorption and a low energy barrier for both H_(2)O dissociation and H2 generation on the stressed Znterminated(0001)ZnO surface.展开更多
BACKGROUND Hepatectomy is the main treatment for patients with hepatocellular carcinoma(HCC)and it has a high possibility for long-term cure potential.But the postoperative mortality and recurrence rates remain high.S...BACKGROUND Hepatectomy is the main treatment for patients with hepatocellular carcinoma(HCC)and it has a high possibility for long-term cure potential.But the postoperative mortality and recurrence rates remain high.Since the long-term prognosis of HCC patients is strongly linked to liver function,preoperative assessment of liver function is very important for HCC patients.AIM To compare the predictive power of the modified Child-Pugh(MCP)and albumin-bilirubin(ALBI)grades for the long-term outcome of HCC.METHODS From January 2010 to June 2017,a total of 204 patients with HCC who underwent surgery at the Second Affiliated Hospital of Chongqing Medical University were enrolled in this retrospective study.Multivariate Cox regression analysis was used to determine the independent predictive factors of survival and relapse.The area under the curve(AUC)was used to evaluate the discriminative performance of the MCP grade and ALBI grade to predict the postoperative overall survival(OS)time and recurrence-free survival(RFS)time.RESULTS The median OS and RFS times were 44.0 mo(range:22.0-74.0 mo)and 22.0 mo(range:5.0-45.0 mo),respectively.The median OS and RFS times of MCP grades 1,2,and 3 patients were 60.0,39.0,and 18.0 mo(P<0.001)and 36.0,15.0,and 7.0 mo(P<0.001),respectively.The median OS and RFS times of ALBI grades 1,2,and 3 patients were 56.0,26.0,and 6.0 mo(P<0.001)and 25.0,10.0,and 3.0 mo(P=0.003),respectively.Both the MCP and ALBI grades were more accurate than the Child-Pugh grade for predicting long-term prognosis.Further analysis demonstrated that for both predicting OS and RFS,the MCP grade performed better than the ALBI grade(AUC:0.642 vs 0.605 for OS;0.659 vs 0.594 for RFS).CONCLUSION The MCP grade is more accurate than the ALBI grade for predicting long-term outcome of patients with HCC.展开更多
The effects of Ga N/In Ga N asymmetric lower waveguide(LWG)layers on photoelectrical properties of In Ga N multiple quantum well laser diodes(LDs)with an emission wavelength of around 416 nm are theoretically investig...The effects of Ga N/In Ga N asymmetric lower waveguide(LWG)layers on photoelectrical properties of In Ga N multiple quantum well laser diodes(LDs)with an emission wavelength of around 416 nm are theoretically investigated by tuning the thickness and the indium content of In Ga N insertion layer(In Ga N-IL)between the Ga N lower waveguide layer and the quantum wells,which is achieved with the Crosslight Device Simulation Software(PIC3D,Crosslight Software Inc.).The optimal thickness and the indium content of the In Ga N-IL in lower waveguide layers are found to be 300 nm and 4%,respectively.The thickness of In Ga N-IL predominantly affects the output power and the optical field distribution in comparison with the indium content,and the highest output power is achieved to be 1.25 times that of the reference structure(symmetric Ga N waveguide),which is attributed to the reduced optical absorption loss as well as the concentrated optical field nearby quantum wells.Furthermore,when the thickness and indium content of In Ga N-IL both reach a higher level,the performance of asymmetric quantum wells LDs will be weakened rapidly due to the obvious decrease of optical confinement factor(OCF)related to the concentrated optical field in the lower waveguide.展开更多
基金supported by the National Key Research and Development Program of China (2017YFA0205200,2023YFC2415200,2021YFF1201003,and 2021YFC2500402)the National Natural Science Foundation of China (82022036,91959130,81971776,62027901,81930053,81771924,62333022,82361168664,62176013,and 82302317)+5 种基金the Beijing Natural Science Foundation (Z20J00105)Strategic Priority Research Program of Chinese Academy of Sciences (XDB38040200)Chinese Academy of Sciences (GJJSTD20170004 and QYZDJ-SSW-JSC005)the Project of High-Level Talents Team Introduction in Zhuhai City (Zhuhai HLHPTP201703)the Youth Innovation Promotion Association CAS (Y2021049)the China Postdoctoral Science Foundation (2021M700341).
文摘Encouraging and astonishing developments have recently been achieved in image-based diagnostic technology.Modern medical care and imaging technology are becoming increasingly inseparable.However,the current diagnosis pattern of signal to image to knowledge inevitably leads to information distortion and noise introduction in the procedure of image reconstruction(from signal to image).Artificial intelligence(AI)technologies that can mine knowledge from vast amounts of data offer opportunities to disrupt established workflows.In this prospective study,for the first time,we develop an AI-based signal-toknowledge diagnostic scheme for lung nodule classification directly from the computed tomography(CT)raw data(the signal).We find that the raw data achieves almost comparable performance with CT,indicating that it is possible to diagnose diseases without reconstructing images.Moreover,the incorporation of raw data through three common convolutional network structures greatly improves the performance of the CT models in all cohorts(with a gain ranging from 0.01 to 0.12),demonstrating that raw data contains diagnostic information that CT does not possess.Our results break new ground and demonstrate the potential for direct signal-to-knowledge domain analysis.
基金support by the National Natural Science Foundation of China (Grant No. 62005049)Natural Science Foundation of Fujian Province (Grant Nos. 2020J01451, 2022J05113)Education and Scientific Research Program for Young and Middleaged Teachers in Fujian Province (Grant No. JAT210035)。
文摘Camouflaged people are extremely expert in actively concealing themselves by effectively utilizing cover and the surrounding environment. Despite advancements in optical detection capabilities through imaging systems, including spectral, polarization, and infrared technologies, there is still a lack of effective real-time method for accurately detecting small-size and high-efficient camouflaged people in complex real-world scenes. Here, this study proposes a snapshot multispectral image-based camouflaged detection model, multispectral YOLO(MS-YOLO), which utilizes the SPD-Conv and Sim AM modules to effectively represent targets and suppress background interference by exploiting the spatial-spectral target information. Besides, the study constructs the first real-shot multispectral camouflaged people dataset(MSCPD), which encompasses diverse scenes, target scales, and attitudes. To minimize information redundancy, MS-YOLO selects an optimal subset of 12 bands with strong feature representation and minimal inter-band correlation as input. Through experiments on the MSCPD, MS-YOLO achieves a mean Average Precision of 94.31% and real-time detection at 65 frames per second, which confirms the effectiveness and efficiency of our method in detecting camouflaged people in various typical desert and forest scenes. Our approach offers valuable support to improve the perception capabilities of unmanned aerial vehicles in detecting enemy forces and rescuing personnel in battlefield.
基金supported by the National Natural Science Foundation of China(Nos.42174063,92155307,41976046)Guangdong Provincial Key Laboratory of Geophysical High-resolution Imaging Technology under(No.2022B1212010002)Project for introduced Talents Team of Southern Marine Science and Engineering Guangdong(Guangzhou)(No.GML2019ZD0203)。
文摘Existing lithospheric velocity models exhibit similar structures typically associated with the first-order tectonic features,with dissimilarities due to different data and methods used in model generation.The quantification of model structural similarity can help in interpreting the geophysical properties of Earth's interior and establishing unified models crucial in natural hazard assessment and resource exploration.Here we employ the complex wavelet structural similarity index measure(CW-SSIM)active in computer image processing to analyze the structural similarity of four lithospheric velocity models of Chinese mainland published in the past decade.We take advantage of this method in its multiscale definition and insensitivity to slight geometrical distortion like translation and scaling,which is particularly crucial in the structural similarity analysis of velocity models accounting for uncertainty and resolution.Our results show that the CW-SSIM values vary in different model pairs,horizontal locations,and depths.While variations in the inter-model CW-SSIM are partly owing to different databases in the model generation,the difference of tomography methods may significantly impact the similar structural features of models,such as the low similarities between the full-wave based FWEA18 and other three models in northeastern China.We finally suggest potential solutions for the next generation of tomographic modeling in different areas according to corresponding structural similarities of existing models.
基金This study was supported by a grand from the National Natural Science Foundation of China(No.12075315).
文摘Complex plasma widely exists in thin film deposition,material surface modification,and waste gas treatment in industrial plasma processes.During complex plasma discharge,the configuration,distribution,and size of particles,as well as the discharge glow,strongly depend on discharge parameters.However,traditional manual diagnosis methods for recognizing discharge parameters from discharge images are complicated to operate with low accuracy,time-consuming and high requirement of instruments.To solve these problems,by combining the two mechanisms of attention mechanism(strengthening the extraction of the channel feature)and shortcut connection(enabling the input information to be directly transmitted to deep networks and avoiding the disappearance or explosion of gradients),the network of squeeze and excitation convolution with shortcut(SECS)for complex plasma image recognition is proposed to effectively improve the model performance.The results show that the accuracy,precision,recall and F1-Score of our model are superior to other models in complex plasma image recognition,and the recognition accuracy reaches 97.38%.Moreover,the recognition accuracy for the Flowers and Chest X-ray publicly available data sets reaches 97.85%and 98.65%,respectively,and our model has robustness.This study shows that the proposed model provides a new method for the diagnosis of complex plasma images and also provides technical support for the application of plasma in industrial production.
基金School-level innovation training project of Chongqing Institute of Technology-New Building Landscape Balcony(No.CXCY2023066)School-level project of Chongqing Institute of Technology:Research on Urban Waterfront Landscape Design Based on the Concept of River Ecological Restoration-Taking the Chongqing Institute of Technology Section of Huaxi River as an Example(No.2022xskz02)。
文摘With the acceleration of urbanization and the improvement of people’s living standards,people have increasingly higher requirements for the living environment,especially in the design of outdoor balconies.However,existing landscape balconies generally suffer from insufficient shading and rainwater drainage problems,which affects people’s living experience.In response to this problem,this article proposes a new design scheme for building landscape balconies to solve the existing problems of landscape balconies.This design plan fully considers the user’s usage needs and scenarios,improves the use value and comfort of the balcony through technical means,and achieves intelligence and functionality.
基金Supported by the National Natural Science Foundation of China,No.30470195
文摘AIM： To investigate the anti-tumor activity of ursolic acid （UA） and its derivatives isolated from Aralia decaisneana on hepatocellular carcinoma both in vitro and in vivo. METHODS： In vivo cytotoxicity was first screened by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide （MTT） assay. Morphological observation, DNA ladder, flow cytometry analysis, Western blot and real time PCR were employed to elucidate the cytotoxic mechanism of UA. Implanted mouse hepatoma H22 was used to evaluate the growth inhibitory effect of UA in vivo . RESULTS： UA could significantly inhibit the proliferation of HepG2 and its drug-resistance strain, R-HepG2 cells, but had no inhibitory effect on primarily cultured normal mouse hepatocytes whereas all the six derivatives of UA could not inhibit the growth of all tested cell lines. Further study on mechanism demonstrated that apoptosis and G0/G1 arrest were involved in the cytotoxicity and cleavage of poly-（ADP-ribose）- polymerase （PARP）. Downregulation of cyclooxygenase-2 （COX-2） protein and upregulation of heat shock protein （HSP） 105 mRNA correlated to the apoptosis of HepG2 cells treated with UA. In addition, UA also could inhibit the growth of H22 hepatoma in vivo. CONCLUSION： UA is a promising anti-tumor agent, but further work needs to be done to improve its solubility.
基金the financial support from the National Natural Science Foundation of China(No.21905317)the financial support from the National Natural Science Foundation of China(No.91833301)the Youth Talent Promotion Project from China Association for Science and Technology。
文摘Piezocatalytic materials have been widely used for catalytic hydrogen evolution and purification of organic contaminants.However,most studies focus on nano-size and/or polycrystalline catalysts,suffering from aggregation and neutralization of internal piezoelectric field caused by polydomains.Here we report a single crystal ZnO of large size and few bulk defects crafted by a hydrothermal method for piezocatalytic hydrogen generation from pure water.It is noteworthy that single-side surface areas of both original as-prepared ZnO and Ga-doped ZnO bulk crystals are larger than 30 cm^(2).The high quality of ZnO and Ga-doped ZnO bulks are further uncovered by high-resolution transmission electron microscope(HRTEM),photoluminescence(PL)and X-ray diffraction(XRD).Remarkably,an outstanding hydrogen production rate of co-catalyst-free Ga-doped ZnO bulk crystal(i.e.,a maximum rate of 5915μmol h^(-1) m^(-2))is observed in pure water triggered by ultrasound in dark,which is over 100 times higher than that of its powder counterpart(i.e.,52.54μmol h^(-1) m^(-2)).The piezocatalytic performance of ZnO bulk crystal is systematically studied in terms of varied exposed crystal facet,thickness and conductivity.Different piezocatalytic performances are attributed to magnitude and distribution of piezoelectric potential,revealed by the finite element method(FEM)simulation.The density functional theory(DFT)calculations are employed to investigate the piezocatalytic hydrogen evolution process,indicating a strong H_(2)O adsorption and a low energy barrier for both H_(2)O dissociation and H2 generation on the stressed Znterminated(0001)ZnO surface.
基金Supported by National Natural Science Foundation of China,No.81572888
文摘BACKGROUND Hepatectomy is the main treatment for patients with hepatocellular carcinoma(HCC)and it has a high possibility for long-term cure potential.But the postoperative mortality and recurrence rates remain high.Since the long-term prognosis of HCC patients is strongly linked to liver function,preoperative assessment of liver function is very important for HCC patients.AIM To compare the predictive power of the modified Child-Pugh(MCP)and albumin-bilirubin(ALBI)grades for the long-term outcome of HCC.METHODS From January 2010 to June 2017,a total of 204 patients with HCC who underwent surgery at the Second Affiliated Hospital of Chongqing Medical University were enrolled in this retrospective study.Multivariate Cox regression analysis was used to determine the independent predictive factors of survival and relapse.The area under the curve(AUC)was used to evaluate the discriminative performance of the MCP grade and ALBI grade to predict the postoperative overall survival(OS)time and recurrence-free survival(RFS)time.RESULTS The median OS and RFS times were 44.0 mo(range:22.0-74.0 mo)and 22.0 mo(range:5.0-45.0 mo),respectively.The median OS and RFS times of MCP grades 1,2,and 3 patients were 60.0,39.0,and 18.0 mo(P<0.001)and 36.0,15.0,and 7.0 mo(P<0.001),respectively.The median OS and RFS times of ALBI grades 1,2,and 3 patients were 56.0,26.0,and 6.0 mo(P<0.001)and 25.0,10.0,and 3.0 mo(P=0.003),respectively.Both the MCP and ALBI grades were more accurate than the Child-Pugh grade for predicting long-term prognosis.Further analysis demonstrated that for both predicting OS and RFS,the MCP grade performed better than the ALBI grade(AUC:0.642 vs 0.605 for OS;0.659 vs 0.594 for RFS).CONCLUSION The MCP grade is more accurate than the ALBI grade for predicting long-term outcome of patients with HCC.
基金the National Natural Science Foundation of China(Grant Nos.62004180 and 61805218)the Science Challenge Project,China(Grant No.TZ20160032-1)the National Key Research and Development Program of China(Grant Nos.2017YFB0403100 and 2017YFB0403103)。
文摘The effects of Ga N/In Ga N asymmetric lower waveguide(LWG)layers on photoelectrical properties of In Ga N multiple quantum well laser diodes(LDs)with an emission wavelength of around 416 nm are theoretically investigated by tuning the thickness and the indium content of In Ga N insertion layer(In Ga N-IL)between the Ga N lower waveguide layer and the quantum wells,which is achieved with the Crosslight Device Simulation Software(PIC3D,Crosslight Software Inc.).The optimal thickness and the indium content of the In Ga N-IL in lower waveguide layers are found to be 300 nm and 4%,respectively.The thickness of In Ga N-IL predominantly affects the output power and the optical field distribution in comparison with the indium content,and the highest output power is achieved to be 1.25 times that of the reference structure(symmetric Ga N waveguide),which is attributed to the reduced optical absorption loss as well as the concentrated optical field nearby quantum wells.Furthermore,when the thickness and indium content of In Ga N-IL both reach a higher level,the performance of asymmetric quantum wells LDs will be weakened rapidly due to the obvious decrease of optical confinement factor(OCF)related to the concentrated optical field in the lower waveguide.
