DeepSVDNet:A Deep Learning-Based Approach for Detecting and Classifying Vision-Threatening Diabetic Retinopathy in Retinal Fundus Images

Artificial Intelligence(AI)is being increasingly used for diagnosing Vision-Threatening Diabetic Retinopathy(VTDR),which is a leading cause of visual impairment and blindness worldwide.However,previous automated VTDR detection methods have mainly relied on manual feature extraction and classification,leading to errors.This paper proposes a novel VTDR detection and classification model that combines different models through majority voting.Our proposed methodology involves preprocessing,data augmentation,feature extraction,and classification stages.We use a hybrid convolutional neural network-singular value decomposition(CNN-SVD)model for feature extraction and selection and an improved SVM-RBF with a Decision Tree(DT)and K-Nearest Neighbor(KNN)for classification.We tested our model on the IDRiD dataset and achieved an accuracy of 98.06%,a sensitivity of 83.67%,and a specificity of 100%for DR detection and evaluation tests,respectively.Our proposed approach outperforms baseline techniques and provides a more robust and accurate method for VTDR detection.

Single-center retrospective study of the diagnostic value of doubleballoon enteroscopy in Meckel’s diverticulum with bleeding

BACKGROUND The study aimed to analyze the characteristic clinical manifestations of patients with intestinal disease Meckel’s diverticulum(MD)complicated by digestive tract hemorrhage.Moreover,we aimed to evaluate the value of double-balloon enteroscopy(DBE)in MD diagnosis and the prognosis after laparoscopic diverticula resection.AIM To evaluate the value of DBE in the diagnosis and the prognosis after laparoscopic diverticula resection for MD with bleeding.METHODS The study retrospectively analyzed relevant data from 84 MD patients treated between January 2015 and March 2022 and recorded their clinical manifestations,auxiliary examination,and follow-up after laparoscopic resection of diverticula.RESULTS(1)Among 84 MD patients complicated with hemorrhage,77 were male,and 7 were female with an average age of 31.31±10.75 years.The incidence was higher in men than in women of different ages;(2)Among the 84 MD patients,65(78.40%)had defecated dark red stools,and 50(58.80%)had no accompanying symptoms during bleeding,indicating that most MD bleeding appeared a dark red stool without accompanying symptoms;(3)The shock index of 71 patients(85.20%)was<1,suggesting that the blood loss of most MD patients was less than 20%–30%,and only a few patients had a blood loss of>30%;(4)The DBE-positive rate was 100%(54/54),99mTcpertechnetate-positive scanning rate was 78%(35/45)compared with capsule endoscopy(36%)and small intestine computed tomography(19%).These results suggest that DBE and 99mTc-pertechnetate scans had significant advantages in diagnosing MD and bleeding,especially DBE was a highly precise examination method in MD diagnosis;(5)A total of 54 MD patients with hemorrhage underwent DBE examination before surgery.DBE endoscopy revealed many mucosal manifestations including normal appearance,inflammatory changes,ulcerative changes,diverticulum inversion,and nodular hyperplasia,with ulcerative changes being the most common(53.70%).This suggests that diverticular mucosal ulcer was the main cause of MD and bleeding;and(6)Laparoscopic dissection of diverticulae was performed in 76 patients,The patients who underwent postoperative follow-up did not experience any further bleeding.Additionally,follow-up examination of the 8 cases who had declined surgery revealed that 3 of them experienced a recurrence of digestive tract bleeding.These findings indicate that laparoscopic diverticula resection in MD patients complicated by bleeding had a favorable prognosis.CONCLUSION Bleeding associated with MD was predominantly observed in male adolescents,particularly at a young age.DBE was a highly precise examination method in MD diagnosis.Laparoscopic diverticula resection effectively prevented MD bleeding and had a good prognosis.

Research Progress of Assessment Tools for Peripheral Venous Access Difficulties in Children

Objective:To review the research progress of peripheral venous access difficulty assessment tools in children and to provide a reference for clinical nurses to select and develop appropriate assessment tools.Methods:Search the literature at home and abroad and summarize and analyze the existing evaluation tools.Results:There is no unified assessment tool about difficult venous access in children at home and abroad.The existing tools include the difficult venous access assessment scale and peripheral venous grading assessment tool.Conclusion:The current assessment tools for venous access difficulties in children have their own limitations,and it is necessary to develop further the assessment tools suitable for the cultural background of children's venous access difficulties.This paper summarized the current progress of research on peripheral venous access difficulty assessment tools.It also analyzed and summarized the shortcomings of existing tools to provide a reference for clinical staff to choose appropriate assessment tools.

Diagnostic Analysis of Potential Vorticity in a Heavy Precipitation Process in Qujing in September 2017

Based on the observation data from the automatic rainfall station and NCEP/NCAR reanalysis data,circulation analysis and diagnosis analysis of potential vorticity in a heavy rainfall process in September 2017 in Qujing were conducted.The results show that the heavy rainfall was mainly affected by the convergence zone between the two high pressures and shear line system,the precipitation area developed from the west to the southeast of Qujing,and the heavy rainfall area was concentrated in the central area.The southerly airflow in the middle and lower layers of the troposphere provided favorable water vapor conditions for heavy precipitation.The precipitation was characterized by high intensity,strong suddenness and small time scale.The heavy precipitation was concentrated from 04:00 to 06:00 on September 6.The high-and low-value centers of dry potential vorticity PV at 500 h Pa were indicative of the activities of cold and warm air in the process of heavy rainfall,and representative of the development of the convergence zone and the activities of shear line.That is to say,the high-value zone of dry potential vorticity PV at 500 h Pa was strengthened to penetrate into the center of Yunnan,leading the northerly airflow to the convergence zone.The deep southerly airflow in the relatively low-value zone of PV was uplifted to the north,converging the cold and warm air at the front of the convergence zone,resulting in heavy precipitation in Qujing.The high-value zone of wet potential vorticity MPV at 700 h Pa can also indicate the characteristics of unstable warm and humid air flow activity.MPV1<0,and MPV2>0,which easily caused the unstable energy release of wet convection and formed heavy precipitation.

Novel Analysis of Two Kinds Hybrid Models in Ferro Martial Inserting Variable Lorentz Force Past a Heated Disk:An Implementation of Finite Element Method

In this article,the rheology of Ferro-fluid over an axisymmetric heated disc with a variable magnetic field by considering the dispersion of hybrid nanoparticles is considered.The flow is assumed to be produced by the stretching of a rotating heated disc.The contribution of variable thermophysical properties is taken to explore themomentum,mass and thermal transportation.The concept of boundary layermechanismis engaged to reduce the complex problem into a simpler one in the form of coupled partial differential equations system.The complex coupled PDEs are converted into highly nonlinear coupled ordinary differential equations system(ODEs)and the resulting nonlinear flow problem is handled numerically.The solution is obtained via finite element procedure(FEP)and convergence is established by conducting the grid-independent survey.The solution of converted dimensionless problem containing fluid velocity,temperature and concentration field is plotted against numerous involved emerging parameters and their impact is noted.From the obtained solution,it is monitored that higher values of magnetic parameter retard the fluid flow and escalating values of Eckert number results in to enhance temperature profile.Ferro-fluid flow and heat energy for the case of the Yamada Ota hybrid model are higher than for the case of the Hamilton Crosser hybrid model.Developing a model is applicable to the printing process,electronic devices,temperature measurements,engineering process and food-making process.The amount of mass species is reduced vs.incline impacts of chemical reaction and Schmidt parameter.

Control Effect of UAV Low Volume Spray Technology on Thrips and Tomato Spotted Wilt Virus in Tobacco Field

[Objectives]The paper was to explore the influence of unmanned aerial vehicle(UAV)low volume spray technology on the control effect of viruliferous thrips and tomato spotted wilt virus(TSWV)under different pesticide concentrations,and to explore the effective control nodes and methods of thrips and TSWV.[Methods]According to the occurrence characteristics of thrips and TSWV,the field control effects of 4 pesticides on thrips and TSWV were tested by UAV with the thrips number and disease index as indicators,following the principle of regional and periodic control trials.[Results]In the groups of UAV and artificial prevention and control,4 agents were used alternatively,including 1%emamectin benzoate ME,1.7%abamectin imidacloprid ME,5%emamectin benzoate WDG,and 30%pyriproxyfen dinotefuran SL.There was no significant difference in the control effect of thrips and TSWV among treatment 1(recommended dosage of UAV agent),treatment 2(reduction of recommended dosage of UAV agent by 25%)and treatment 4(recommended dosage of artificial control agent),and the control effects on thrips were more than 83.16%in the 3 treatments.The disease index of TSWV in the 3 treatments decreased from 8.64±1.37 in the blank control group to less than 3,which reached the prevention and control threshold.But treatment 3(reduction of recommended dosage of UAV agent by 50%)did not reach the prevention and control threshold.The disease index of TSWV in the blank control area increased with the increase of the number of live nymphs of thrips,and there was a significant positive correlation,with good fitness.[Conclusions]UAV has a significant impact on the control effect of thrips and TSWV under different pesticide concentrations.In the actual flight control application,it is recommended that the amount of the pesticides is about 3/4 and not less than 1/2 of that of the artificial application.The control area should be extended to 100 m of the ridge of the tobacco field,and UAV is used periodically to control thrips and TSWV for 5 times from pre-transplanting stage to pre-squaring stage of flue-cured tobacco.The control effect is significantly different from the traditional artificial application.

Analysis of Characteristics of Hail Disaster and a Typical Hail Suppression Process in Qujing City

Based on the data of hail disaster in Qujing City and the detection data of the new generation of Doppler weather radar, the spatial and temporal distribution characteristics of hail disaster and hail suppression operations in Qujing City were analyzed statistically, and the hail suppression operations of a typical cell case was analyzed. The results showed that the number of hail days and hail frequency showed an increasing trend in Qujing City from 2017 to 2022, and the number of artificial hail suppression operations increased accordingly. Hail disaster occurred most frequently in Xuanwei City. Through the analysis of hail suppression operations of a typical cell case, it is found that the operations were timely, and the location was reasonable. The ammunition used was sufficient, and the overall effect of the hail suppression operations was good.

Causes of a Heavy Snowfall Process in Eastern Yunnan in 2022

Based on NCEP/NCAR reanalysis data, Micaps data and ground observation data, the physical characteristics of a heavy snowfall process in eastern Yunnan from January 31 to February 3, 2022 were analyzed. The results show that the circulation background of the heavy snowfall process was "north-ridge and south-trough" type, and the cold air accumulated in the deep East Asian transverse trough. The cold advection behind the trough moved southwards into eastern Yunnan under the movement of the transverse trough. The establishment of upper and lower air jet provided abundant water vapor, and the snowfall area coincided with the strong water vapor convergence area. The strong cold center near the ground was maintained, and the cold air moved southwards. As a result, the cold pad was lasting and deep, and the ground temperature was 0 ℃ or below, which was conducive to snow accumulation on the ground. Seen from the spatial distribution of pseudo-equivalent potential temperature, the low layer always had certain warm and wet conditions during the heavy snowfall, which was conducive to the establishment of unstable energy. The snowfall occurred near the θ se steep area and the warm and wet unstable area. The vertical distribution of temperature had a good indication of precipitation form. The upper layer was controlled by strong cold advection, while the middle and lower troposphere was controlled by warm advection, and there was a warm inversion layer, which was conducive to the transformation of ice crystals into snowflakes, so that ice crystals fell to the ground in the form of snowflakes.

Laparoscopic left hemihepatectomy guided by indocyanine green fluorescence: A cranial-dorsal approach

BACKGROUND Advancements in laparoscopic technology and a deeper understanding of intra-hepatic anatomy have led to the establishment of more precise laparoscopic hepatectomy(LH)techniques.The indocyanine green(ICG)fluorescence navi-gation technique has emerged as the most effective method for identifying hepatic regions,potentially overcoming the limitations of LH.While laparoscopic left hemihepatectomy(LLH)is a standardized procedure,there is a need for innova-tive strategies to enhance its outcomes.important anatomical markers,surgical skills,and ICG staining methods.METHODS Thirty-seven patients who underwent ICG fluorescence-guided LLH at Qujing Second People's Hospital between January 2019 and February 2022 were retrospectively analyzed.The cranial-dorsal approach was performed which involves dissecting the left hepatic vein cephalad,isolating the Arantius ligament,exposing the middle hepatic vein,and dissecting the parenchyma from the dorsal to the foot in order to complete the anatomical LLH.The surgical methods,as well as intra-and post-surgical data,were recorded and analyzed.Our hospital’s Medical Ethics Committee approved this study(Ethical review:2022-019-01).RESULTS Intraoperative blood loss during LLH was 335.68±99.869 mL and the rates of transfusion and conversion to laparotomy were 13.5%and 0%,respectively.The overall incidence of complications throughout the follow-up(median of 18 months;range 1-36 months)was 21.6%.No mortality or severe complications(level IV)were reported.CONCLUSION LLH has the potential to become a novel,standardized approach that can effectively,safely,and simply expose the middle hepatic vein and meet the requirements of precision surgery.

A Possible X-ray Quasi-periodic Oscillation in the Narrow-line Seyfert 1 Galaxy Mrk 142

A possible quasi-periodic oscillation(QPO) at frequency 7.045 × 10^(-5) Hz is found in the narrow-line Seyfert 1galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April 11.We find that the QPO signal is statistically significantly larger than the 5σ level and highly coherent with quality factor Q > 5 at the 0.3–10 keV band by using the method of the Lomb–Scargle Periodogram,the Weighted Wavelet Z-transform and the REDFIT.We analyze the data in 0.3–0.6 keV,0.6–1 keV,1–3 keV and 3–10 keV energy bands,and find obvious QPO signals at 0.3–0.6 keV and 1–3 keV bands.We then analyze the time-average spectra and time variability at the QPO frequency of 7.045 × 10^(-5) Hz,and use a model to fit them.We find that the QPO signal mainly comes from the X-ray hot corona.

A Situational Awareness Method for Initial Insulation Fault of Distribution Network Based on Multi-Feature Index Comprehensive Evaluation

Most ground faults in distribution network are caused by insulation deterioration of power equipment.It is difficult to find the insulation deterioration of the distribution network in time,and the development trend of the initial insulation fault is unknown,which brings difficulties to the distribution inspection.In order to solve the above problems,a situational awareness method of the initial insulation fault of the distribution network based on a multi-feature index comprehensive evaluation is proposed.Firstly,the insulation situation evaluation index is selected by analyzing the insulation fault mechanism of the distribution network,and the relational database of the distribution network is designed based on the data and numerical characteristics of the existing distribution management system.Secondly,considering all kinds of fault factors of the distribution network and the influence of the power supply region,the evaluation method of the initial insulation fault situation of the distribution network is proposed,and the development situation of the distribution network insulation fault is classified according to the evaluation method.Then,principal component analysis was used to reduce the dimension of the training samples and test samples of the distribution network data,and the support vector machine(SVM)was trained.The optimal parameter combination of the SVM model was found by the grid search method,and a multi-class SVM model based on 1-v-1 method was constructed.Finally,the trained multi-class SVM was used to predict 6 kinds of situation level prediction samples.The results of simulation examples show that the average prediction accuracy of 6 situation levels is above 95%,and the perception accuracy of 4 situation levels is above 96%.In addition,the insulation maintenance decision scheme under different situation levels is able to be given when no fault occurs or the insulation fault is in the early stage,which can meet the needs of power distribution and inspection for accurately sensing the insulation fault situation.The correctness and effectiveness of this method are verified.

Meta-analysis of new intervention measures for preventing side effects of artificial joint replacement

BACKGROUND Intertrochanteric fracture of the femur occurs mostly among older people,and seriously affects daily life and quality of life.At present,physical intervention,drug treatment,routine intervention and rehabilitation training are widely used for prevention of side effects,but it is still inconclusive which intervention has the best effect.AIM To compare the effects of new intervention measures for preventing side effects of artificial joint replacement.METHODS We searched the Chinese and English literatures for comparative studies on the prevention of side effects of new interventions for artificial joint replacement from July 2013 to June 2023 in China HowNet,PubMed,Wanfang,Weipu and other databases.Study quality was evaluated by improved Jadad scoring standard,and the effects of different interventions on preventing different complications were analyzed by meta-analysis of evidence-based medicine with Review Manager 5.0 software.RESULTS Ten articles,including 869 cases,were finally included.The preventive effects of different interventions on the side effects of artificial joint replacement were studied,and valid data were extracted.There were two articles on the preventive effects of drug intervention,four on comparison of the preventive effects of combined and single interventions,and three on the preventive effects of physical intervention,rehabilitation training and routine intervention.Meta-analysis showed that the preventive effect of rivaroxaban was significantly better than low molecular weight heparin calcium[mean difference(MD)=-0.16,95%CI:-0.28 to-0.04,P<0.05].The effect of combined intervention was significantly better than that of single intervention(MD=-0.08,95%CI:-0.16 to-0.01,P<0.001).Physical intervention was significantly better than routine intervention and rehabilitation training(MD=0.26,95%CI:0.16–0.36,P<0.001).CONCLUSION Rivaroxaban combined with rehabilitation training is preferred for preventing deep vein thrombosis after artificial joint replacement.In the prevention of pulmonary embolism,rivaroxaban drug intervention is given priority.The effect of combined intervention is better than that of single intervention.

Research and Practice of Cardiopulmonary Rehabilitation Training Programs

In today’s society, the incidence of cardiopulmonary diseases is increasing annually, seriously affecting patients’ quality of life. Therefore, developing a scientific and effective rehabilitation training program is of great significance. This study first analyzes the theoretical basis of cardiopulmonary rehabilitation training, including the effects of aerobic exercise, interval training, and strength training on cardiopulmonary function. Based on this, a comprehensive rehabilitation training program is designed, which includes personalized training plans, comprehensive interventions, multidisciplinary collaboration, patient education, and regular follow-up visits. The cardiopulmonary rehabilitation training plan developed in this study has certain scientific practicability, which provides a theoretical basis for cardiopulmonary rehabilitation training, and also provides a reference for medical institutions, rehabilitation centers and communities, which is helpful for promotion and application to a wider range of patients with cardiopulmonary diseases.

Impacts of different pancreatic resection ranges on endocrine function in Suncus murinus

BACKGROUND Surgical intervention involving the pancreas can lead to impaired glucose tolerance and other types of endocrine dysfunction.The scope of pancreatectomy and whether it includes the ventral pancreas are the key factors in the development of postoperative diabetes.The ventral and dorsal pancreases are almost separated in Suncus murinus(S.murinus).AIM To investigate the effects of different extents of pancreatic resection on endocrine function in S.murinus.METHODS Eight-week-old male S.murinus shrews were randomly divided into three experimental groups according to different pancreatic resection ranges as follows:ventral pancreatectomy(VPx)group;partial pancreatectomy(PPx)group;subtotal pancreatectomy(SPx)group;and a sham-operated group.Postprandial serum insulin,glucagon-like peptide-1(GLP-1),pancreatic polypeptide(PP),and somatostatin(SST)levels,as well as food intake,weight,blood glucose,and glucose tolerance were regularly measured for each animal.RESULTS S.murinus treated with PPx and SPx suffered from varying degrees of impaired glucose tolerance,but only a small proportion of the SPx group developed diabetes.Only S.murinus in the SPx group showed a significant decrease in food intake accompanied by severe weight loss,as well as a significant increase in postprandial serum GLP-1 levels.Postprandial serum PP levels decreased in both the VPx and PPx groups,but not in the SPx group.Postprandial serum SST levels decreased in both VPx and PPx groups,but the decrease was marginal.CONCLUSION Severe weight loss after pancreatectomy may be related to loss of appetite caused by compensatory elevation of GLP-1.PP and GLP-1 may play a role in resisting blood glucose imbalance.

Nutritional Support under the Neuman Systems Model for Stroke Patients

Objective: To explore nutritional support under the Neuman systems model in treating dysphagia in stroke patients. Methods: In this retrospective study, we enrolled 97 patients with dysphagia after stroke admitted to our hospital, and randomly divided them into the Neuman group (n = 51) given nursing intervention based on Neuman systems model and a control group (n = 46) given routine nursing intervention. Both groups received nutritional support for 3 months. Nutritional indexes (serum total protein, plasma albumin, serum albumin, hemoglobin and transferrin levels) and immune indexes (immunoglobulin (Ig) A, IgG, IgM and total lymphocyte count (TLC) in both groups were recorded and compared. Pulmonary function recovery, video fluoroscopic swallowing study score, water swallowing test score, complication rate, and health knowledge mastery level were also compared between the two groups. Results: After the intervention, the Neuman group showed less decrease in the nutritional and immune index scores (serum total protein, plasma albumin, hemoglobin, serum albumin;IgA, IgG, IgM, and TLC;all P Conclusion: For patients with stroke and dysphagia, comprehensive nursing intervention (e.g., nutritional support) under theNeuman systems model can promote the recovery of immune, swallowing, and pulmonary function, reduce complication incidence and facilitate comprehensive rehabilitation, ensuring adequate nutritional intake.

Intervention Effect of Lower Limb Rehabilitation Robot with Task-Oriented Training on Stroke Patients and Its Influence on KFAROM Score

Objective: To explore the effect of lower limb rehabilitation robot combined with task-oriented training on stroke patients and its influence on KFAROM score. Methods: 100 stroke patients with hemiplegia admitted to our hospital from January 2023 to December 2023 were randomly divided into two groups, the control group (50 cases) was given task-oriented training assisted by nurses, and the observation group (50 cases) was given lower limb rehabilitation robot with task-oriented training. Lower limb balance, lower limb muscle strength, motor function, ankle function, knee flexion range of motion and walking ability were observed. Results: After treatment, the scores of BBS, quadriceps femoris and hamstrings in the observation group were significantly higher than those in the control group (P Conclusion: In the clinical treatment of stroke patients, the combination of task-oriented training and lower limb rehabilitation robot can effectively improve the lower limb muscle strength, facilitate the recovery of balance function, and have a significant effect on the recovery of motor function, which can improve the walking ability of stroke patients and the range of motion of knee flexion, and achieve more ideal therapeutic effectiveness.

Roles of Aqueous Extract of Marigold on Arsenic-Induced Oxidative Damage in Pancreatic Islet β-Cells

Roles of Marigold extracts (ME) on arsenic trioxide (ATO)-induced oxidative damage to pancreatic β-cells need to be further elucidated. In this study, NIT-1 cells were treated with different concentrations of and/or ATO, following by the cell viability was detected by CCK8 assay. Then, intracellular reactive oxygen species (ROS) levels, lipid peroxide (MDA) contents and superoxide dismutase (SOD) activity were measured with a fluorescence probe method and colorimetric assay, respectively. The apoptosis rate and morphology was detected and observed with hoechst 33,258 staining assay. The mRNA levels and protein expressions of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were measured by real-time fluorescence quantitative polymerase chain reaction and protein immunoblotting assay, respectively. Our results indicated that Co-treatment with ME and ATO exacerbated the cell viability decreasing reduced by ATO, while the addition of ME after ATO treatment effectively promote the recovery of ATO reduced survival rates. The ATO group increased apoptosis (P P β-cells by modulating the activation of the Nrf2 signaling pathway.

Microwave-assisted ionothermal synthesis of hierarchical microcube-like BiOBr with enhanced photocatalytic activity

Bismuth oxybromide（BiOBr） with a hierarchical microcube morphology was successfully synthesized via microwave-assisted ionothermal self-assembly method. The as-obtained BiOBr was composed of regular multi-layered nanosheets, which were formed by selective adsorption of ionic liquids on the Br-terminated surface, followed by the formation of hydrogen bond-co-π-π stacking.The synthesized BiOBr exhibited high activity, excellent stability, and superior mineralization ability in the photocatalytic degradation of organic dyes under visible light owing to its enhanced light absorbance and narrow bandgap. Furthermore, photo-generated electrons were determined to be the main active species by comparison with different trapping agents used in the photocatalytic reactions.

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl_4 and SbCl_3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using： （1） an ion-exchange hydrolysis to remove chlorine ions, and （2） isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.

Plastid genome evolution of a monophyletic group in the subtribe Lauriineae(Laureae,Lauraceae)

Litsea,a non-monophyletic group of the tribe Laureae(Lauraceae),plays important roles in the tropical and subtropical forests of Asia,Australia,Central and North America,and the islands of the Pacific.However,intergeneric relationships between Litsea and Laurus,Lindera,Parasassafras and Sinosassafras of the tribe Laureae remain unresolved.In this study,we present phylogenetic analyses of seven newly sequenced Litsea plastomes,together with 47 Laureae plastomes obtained from public databases,representing six genera of the Laureae.Our results highlight two highly supported monophyletic groups of Litsea taxa.One is composed of 16 Litsea taxa and two Lindera taxa.The 18 plastomes of these taxa were further compared for their gene structure,codon usage,contraction and expansion of inverted repeats,sequence repeats,divergence hotspots,and gene evolution.The complete plastome size of newly sequenced taxa varied between 152,377 bp(Litsea auriculata)and 154,117 bp(Litsea pierrei).Seven of the 16 Litsea plastomes have a pair of insertions in the IRa(trnL-trnH)and IRb(ycf2)regions.The 18 plastomes of Litsea and Lindera taxa exhibit similar gene features,codon usage,oligonucleotide repeats,and inverted repeat dynamics.The codons with the highest frequency among these taxa favored A/T endings and each of these plastomes had nine divergence hotspots,which are located in the same regions.We also identified six protein coding genes(accD,ndhJ,rbcL,rpoC2,ycf1 and ycf2)under positive selection in Litsea;these genes may play important roles in adaptation of Litsea species to various environments.