Source and level of dietary iron influence semen quality by affecting inflammation, oxidative stress and iron utilization levels in boars

Background Boars fed a mixed form of inorganic and organic iron in excess of the NRC recommended levels still develop anemia,which suggested that the current level and form of iron supplementation in boar diets may be inappropriate.Therefore,56 healthy Topeka E line boars aged 15–21 months were randomly divided into 5 groups:basal diet supplemented with 96 mg/kg ferrous sulfate(FeSO_(4))and 54 mg/kg glycine chelated iron(Gly-Fe,control);80 mg/kg or 115 mg/kg Gly-Fe;80 mg/kg or 115 mg/kg methionine hydroxyl analogue chelated iron(MHA-Fe,from CalimetFe)for 16 weeks.The effects of dietary iron supplementation with different sources and levels on semen quality in boars were investigated.Results 1)Serum Fe and hemoglobin concentrations were not affected by reduced dietary iron levels in the 80 mg/kg or 115 mg/kg Gly-Fe and MHA-Fe groups compared with the control group(P>0.05).2)Serum interleukin-6(IL-6)and sperm malondialdehyde(MDA)levels in the 80 mg/kg or 115 mg/kg MHA-Fe groups were lower than those in the control group(P<0.05),and higher serum superoxide dismutase levels and lower MDA levels in the 115 mg/kg MHA-Fe group(P<0.05).3)Boars in the 80 mg/kg or 115 mg/kg Gly-Fe and MHA-Fe groups had lower serum hepcidin(P<0.01),ferritin(P<0.05),and transferrin receptor(P<0.01)concentrations,and boars in the 115 mg/kg MHA-Fe group had higher seminal plasma Fe concentrations compared with the control group.4)Boars in the 80 mg/kg and 115 mg/kg MHA-Fe groups had lower abnormal sperm rate and in situ oscillating sperm ratio compared to the control group at weeks 12 and/or 16 of the trial.However,the effect of Gly-Fe on improving semen quality in boars was not evident.5)Serum IL-6 level was positively correlated with hepcidin concentration(P<0.05),which in turn was significantly positively correlated with abnormal sperm rate(P<0.05).Furthermore,significant correlations were also found between indicators of iron status and oxidative stress and semen quality parameters.Conclusions Dietary supplementation with 80 mg/kg or 115 mg/kg MHA-Fe did not induce iron deficiency,but rather reduced serum inflammatory levels and hepcidin concentration,alleviated oxidative stress,increased body iron utilization,and improved semen quality in adult boars.

Application of Survival Quilts for prognosis prediction of gastrectomy patients based on the Surveillance,Epidemiology,and End Results database and China National Cancer Center Gastric Cancer database

Objective:Accurate prognosis prediction is critical for individualized-therapy making of gastric cancer patients.We aimed to develop and test 6-month,1-,2-,3-,5-,and 10-year overall survival(OS)and cancer-specific survival(CSS)prediction models for gastric cancer patients following gastrectomy.Methods:We derived and tested Survival Quilts,a machine learning-based model,to develop 6-month,1-,2-,3-,5-,and 10-year OS and CSS prediction models.Gastrectomy patients in the development set(n=20,583)and the internal validation set(n=5,106)were recruited from the Surveillance,Epidemiology,and End Re-sults(SEER)database,while those in the external validation set(n=6,352)were recruited from the China National Cancer Center Gastric Cancer(NCCGC)database.Furthermore,we selected gastrectomy patients with-out neoadjuvant therapy as a subgroup to train and test the prognostic models in order to keep the accuracy of tumor-node-metastasis(TNM)stage.Prognostic performances of these OS and CSS models were assessed using the Concordance Index(C-index)and area under the curve(AUC)values.Results:The machine learning model had a consistently high accuracy in predicting 6-month,1-,2-,3-,5-,and 10-year OS in the SEER development set(C-index=0.861,0.832,0.789,0.766,0.740,and 0.709;AUC=0.784,0.828,0.840,0.849,0.869,and 0.902,respectively),SEER validation set(C-index=0.782,0.739,0.712,0.698,0.681,and 0.660;AUC=0.751,0.772,0.767,0.762,0.766,and 0.787,respectively),and NCCGC set(C-index=0.691,0.756,0.751,0.737,0.722,and 0.701;AUC=0.769,0.788,0.790,0.790,0.787,and 0.788,respectively).The model was able to predict 6-month,1-,2-,3-,5-,and 10-year CSS in the SEER development set(C-index=0.879,0.858,0.820,0.802,0.784,and 0.774;AUC=0.756,0.827,0.852,0.863,0.874,and 0.884,respectively)and SEER validation set(C-index=0.790,0.763,0.741,0.729,0.718,and 0.708;AUC=0.706,0.758,0.767,0.766,0.766,and 0.764,respectively).In multivariate analysis,the high-risk group with risk score output by 5-year OS model was proved to be a strong survival predictor both in the SEER development set(hazard ratio[HR]=14.59,95%confidence interval[CI]:1.872-2.774,P<0.001),SEER validation set(HR=2.28,95%CI:13.089-16.293,P<0.001),and NCCGC set(HR=1.98,95%CI:1.617-2.437,P<0.001).We further explored the prognostic value of risk score resulted 5-year CSS model of gastrectomy patients,and found that high-risk group remained as an independent CSS factor in the SEER development set(HR=12.81,95%CI:11.568-14.194,P<0.001)and SEER validation set(HR=1.61,95%CI:1.338-1.935,P<0.001).Conclusion:Survival Quilts could allow accurate prediction of 6-month,1-,2-,3-,5-,and 10-year OS and CSS in gastric cancer patients following gastrectomy.

Physical activity and risk of lung cancer:A systematic review and dose-response meta-analysis of cohort studies

Objective:To synthesize the knowledge about the association of total physical activity(TPA),leisure-time phys-ical activity(LTPA),occupational physical activity(OPA)and lung cancer risk and explore the dose-response relationship between LTPA level and lung cancer.Methods:PubMed and Web of Science were searched up to 17 November 2021.The summary relative risks(RRs)and 95%confidence intervals(CIs)were calculated by random-effects or fixed-effects model.The dose-response analysis was conducted with restricted cubic splines.Results:We identified 25 articles(42 cohort studies)that assessed the physical activity-lung cancer association,including 9,983,295 study participants and 85,988 incident cases of lung cancer.When comparing the highest to the lowest level of TPA and LTPA,lung cancer risk reduced 22%(RR,0.78;95%CI:0.70,0.86)and 12%(RR,0.88;95%CI:0.83,0.93),respectively.We found an approximately U-shaped association between LTPA and lung cancer(P non-linearity<0.001),with the lowest risk at 15 metabolic equivalent of task hours per week(h/wk)of LTPA.Compared to participants with sitting occupations,lung cancer risk significantly increased among those being unemployed(RR,1.33;95%CI:1.17,1.51)or with standing occupations(RR,1.37;95%CI:1.15,1.63),but not among those with light or high OPA.Conclusions:Our meta-analysis supported a protective effect of TPA and LTPA,but not OPA,on lung cancer risk.The novel finding of a U-shaped association between LTPA and lung cancer risk warrants further investigation.

Shear strength of an unsaturated weakly expansive soil

To study the weakly expansive clay obtained from a slope along Wuhan—Shiyan expressway in Hubei Province,soil-water property tests and some unsaturated triaxial tests with suction control were conducted,and the soil-water retention curve（SWRC） and unsaturated shear strength of this soil were obtained.Results show that the air-entry suction and the residual degree of saturation of the tested soil are 106 kPa and 8%,respectively.The boundary effect zone and the transition zone can be identified on the desorption curve,but the residual zone is not so obvious.The unsaturated shear strength increases as suction increases within the range of controlled suction in the test,and friction angle,b,in the triaxial shear test is 17.6°.Based on the results,constitutive models for predicting the unsaturated shear strength using the SWRC were evaluated,and comparisons between prediction and measurement were made.It is concluded that for engineering purpose,the constitutive model should be carefully selected based on soil properties when predicting the unsaturated shear strength using the SWRC.

Prenatal Exposure to Polycyclic Aromatic Hydrocarbons and Birth Weight in China

Adverse birth outcomes are a leading cause of mortality in children in China, but the environmental influences of these conditions remain largely unexplained in this population. We aimed to evaluate the levels of polycyclic aromatic hydrocarbons (PAHs) in Chinese pregnant women and their newborns, and to examine the association between levels of PAHs and infant birth weight. We conducted a cross-sectional study including 81 pairs of mothers and newborns from four hospitals in four different cities in China. High Performance Liquid Chromatography was used to measure the concentration of nine PAHs in maternal and cord blood and multiple linear regression analyses were used to evaluate the associations of these PAHs with infant birth weight. Anthracene (ANT) had the highest average concentration and detection rate (geometric mean = 69.54 ng/g and 76.5%, respectively) in maternal serum samples, while fluoranthene (FLT) had the highest concentration and detection rate (geometric mean = 68.4 ng/g and 50.6%, respectively) in the cord blood. Most of the measured PAHs in maternal serum and three PAHs in cord blood were inversely but non-significantly associated with birth weight. The strongest associations were observed for higher concentrations of benzo (a) pyrene (BaP) in maternal serum (230.7 g decrease for levels > median vs. < LOD;p = 0.151) and for ANT in cord blood (153.1 g decrease for levels < median vs. < LOD;p = 0.208). Ant and FLT were the predominant PAHs in the maternal and cord blood serum. Serum concentrations of several measured PAHs were associated with a decreased birth weight, although not significantly, suggesting that further studies with larger sample sizes are needed to validate our findings.

Comparison of mini-probe endoscopic ultrasonography with computed tomography scan in preoperative staging of esophageal cancer

Objective:To compare mini-probe endoscopic ultrasonography(MCUS)with computed tomography(CT)in pre-operative T and N staging of esophageal cancer,and to find out the MCUS parameters to judge lymph nodes metastasis for esophageal cancer.Methods:Thirty-five patients received both MCUS and CT preoperatively,on both of which the T and N stages were determined.The accuracy,sensitivity,specificity,positive predicting value and negative predicting value were compared with the postoperative pathological results.Results:The accuracy of MCUS was 85.7% in T staging and 85.7% and 80.0% in N staging by two different methods,which were 45.7% and 74.3%,respectively,by CT.Conclusion:MCUS is better than CT in preoperative staging for esophageal cancer.The ratio of short to long axis(S/L)combined with short axis is a useful way to determine lymph nodes metastasis.

National Lottery Participation and Expenditure： Evidence from Hainan Province in China

Lottery has already been broadly used by countries to raise funds to construct the public organizations, but its function is decided by the rate of participation and expenditure levels. Using the lottery investigation data from Hainan Province, this paper analyzes the factors affecting the rate of participation and expenditure in Hainan Province by applying Probit and Tobit Model. It shows that factors such as gender, marriage, education level, attitude and the social environment have distinct influence on the individual lottery participation and expenditure decisions. Therefore, lottery is a restricted rational behavior affected by psychological and social environment variables. Publicity may play an important role in our country＇s lottery policy. Moreover, lottery policy in China should implement a development strategy which requires adjustment in product pattem and promotion approach.

International patterns and trends of childhood and adolescent cancer, 1978-2012

Background:This study aimed to provide a detailed analysis of the temporal trends of cancer incidence rates for individuals aged 0-19 years in selected regions globally from 1978 to 2012.Methods:Data were obtained from Volumes V-XI of Cancer Incidence in Five Continents(CI5),published by the International Agency for Research on Cancer.A total of 53 registries in 23 regions from the Americas,Asia,Europe,and Oceania that contained information on cancer incidence throughout 1978-2012(35 years)were included in this study.Joinpoint regression was used for the analysis of trends.Results:Most regions showed increasing trends in overall childhood cancer among children(aged 0-14 years)and adolescents(aged 15-19 years).Nearly all regions showed rising trends in childhood and adolescent leukemia incidence rates,whereas the incidence of lymphoma among children generally decreased.Only France,Australia,and New Zealand showed decreasing trends for malignant central nervous system(CNS)tumors among adoles-cents.Kidney cancer and bone cancer incidence rates remained stable for most regions.The incidence of thyroid cancer among adolescents increased in most regions and that of testicular cancer decreased in approximately one-half of the regions studied.Conclusion:The international temporal trends of cancer incidents among children and adolescents are varied by region,cancer type,age group,and gender,and have changed over time.

Etiology of lung cancer: Evidence from epidemiologic studies

Lung cancer is one of the leading causes of cancer incidence and mortality worldwide.While smoking,radon,air pollution,as well as occupational exposure to asbestos,diesel fumes,arsenic,beryllium,cadmium,chromium,nickel,and silica are well-established risk factors,many lung cancer cases cannot be explained by these known risk factors.Over the last two decades the incidence of adenocarcinoma has risen,and it now surpasses squamous cell carcinoma as the most common histologic subtype.This increase warrants new efforts to identify additional risk factors for specific lung cancer subtypes as well as a comprehensive review of current evidence from epidemiologic studies to inform future studies.Given the myriad exposures individuals experience in real-world settings,it is essential to investigate mixture effects from complex exposures and gene-environment interactions in relation to lung cancer and its subtypes.

Etiology of non-Hodgkin lymphoma: A review from epidemiologic studies

Non-Hodgkin lymphoma(NHL)contributes to significant cancer burden and mortality globally.In recent years,much insight into the causes of NHL has been gained by evaluating global differences through international collaboration and data pooling.NHL comprises different subtypes that are known to behave differently,exhibit different prognoses,and start in distinct cell types(B-cell,T-cell,and NK-cell,predominantly),and there is in-creasing evidence that NHL subtypes have different etiologies.Classification of NHL can be complex,with varying subtype frequencies,and is a consideration when evaluating geographic differences.Because of this,international pooling of well-executed epidemiologic studies has conferred power to evaluate NHL by subtype and confidence with minimal misclassification.Given the decreasing burden in some regions while cases rise in Asia,and espe-cially China,this report focuses on a review of the established etiology of NHL from the epidemiologic literature in recent decades,highlighting work from China.Topics covered include demographic patterns and genetic de-terminants including family history of NHL,as well as infection and immunosuppression,lifestyle,environment,and certain occupational exposures contributing to increased disease risk.

Microbial Diversity and Key Metabolic Pathways in Lignite-Promoted Anaerobic Fermentation with Residual Sludge

To enhance methane production efficiency in lignite anaerobic digestion and explore new ways for residual sludge utilization, this study employed the co-fermentation of lignite and residual sludge for biomethane conversion. The bacterial colony structure, metabolic pathways, and interactions between residual sludge and lignite in anaerobic methanogenic fermentation with different mass ratios were analyzed using macrogenomics sequencing. This study aimed to explore the mechanisms involved in the co-anaerobic fermentation of lignite and residual sludge. The results indicated that the addition of sludge enhanced the metabolic pathways in hydrolysis acidification, hydrogen-acetic acid production, and methanation phases. Notably, the enhancement of acetate- and carbon dioxide-nutrient metabolic pathways was more pronounced, with increased activity observed in related enzymes such as acetic acid kinase (k00925) and acetyl coenzyme synthetase (K01895). This increased enzymatic activity facilitated the microbial conversion of biomethane. The results of the study indicated that the sludge exhibited a promotional effect on the methane produced through the anaerobic fermentation of lignite, providing valuable insights for lignite and residual sludge resource utilization.

单纯型大疱性表皮松解症伴肌营养不良1例

单纯型大疱性表皮松解症伴肌营养不良(epidermolysis bullosa simplex with muscular dystrophy, EBS-MD)由PLEC基因变异引起, 主要特征为出生时或生后不久出现皮肤水疱及进行性肌无力。本文报道1例危重型EBS-MD患儿, 以提升儿科医生识别与诊治这类疾病的能力。

Beam homogenization structure for a laser illuminator design based on diode laser beam combining technology

With the rapid development of laser technology,laser as the light source of night vision illuminating can realize long-distance and clear imaging,which has been widely used in laser active illuminating field.A high-power diode laser with a wavelength of 808 nm was designed as the laser active illuminating source,and the output power of no less than100 W was obtained by spatial beam multiplexing,polarization multiplexing,and high efficiency fiber coupling techniques.In view of the beam homogenization of illuminating source,a novel beam homogenization system based on waveguide is proposed in this work.A square spot with a horizontal divergence angle of 40°,a vertical divergence angle of 10°,and an illuminating power ratio of 4:1 was obtained by a collimating lens.Comparing with the traditional circular illuminating beam,the square illuminating beam can match the illuminating angle of CCD camera better,and the energy utilization rate is higher.In addition,by optimizing the structure of waveguide and collimating lens,the illuminating angle can be changed to meet the illuminating requirements under different conditions theoretically.

Design and performance analysis of indoor calibration device for the forcemeasuring system of the tractor three-point hitch

The real-time monitoring of the load in farming by the sensor installed on the tractor's three-point hitch can effectively improve the farming efficiency and force-position combined control,reduce the compaction risk of the wheel on the soil and reduce the fuel consumption in farming process.However,the measurement and quantification of the loads on the three-point hitch have some problems remaining unresolved:testing the accuracy and reliability of a load measuring system is hard when the tractor works in a field,the mathematical model of spatial forces usually lacks a practical and effective validation,and the calibration process of the measurement system is inconvenient and incomplete while easily causing a low accuracy.Specifically,this paper builds a new spatial-force mathematical model based on the geometry of a three-point hitch.To eliminate the discrepancy of the geometric model with the actual structure and to refine the mathematical model,a calibration process is conducted by developing a calibration bench,which is equipped with a data acquisition system and a multi-parameter monitoring interface.The three-point hitch installed on this calibration bench is subject to steady-state loading.The loading force,angle of the lower drawbar,and three-component forces(three shaft pin sensors’forces)of the three-point hitch are well measured.With applying for the measured data to calibrate the theoretical mathematic model eventually derives the resultant force from all the three-component forces,a dynamical loading bench was developed to test the calculated resultant force for the three-point hitch during the sinusoidal and randomly variant dynamical loadings tests.A hitch force measurement system is also developed to collect real-time data and calculate the resultant force of measured three-component forces through the calibrated mathematical model.The results of the dynamical loading tests show that the average relative error MRE=1.09%with an average force measurement time delay beingΔt=0.5 s,the root mean square error RMSE=59.3 N,and the coefficient of determination R2=0.9903.As observed,the shape and the trend of the generated resultant force curve are basically the dynamical loading force.The dynamical loading test proves the high efficacy and reliability of the proposed indoor calibration method for calculating the load based on the three-component forces as measured on the three-point hitch.Besides,the preliminary study of the proposed method on the hitch load provides great potential to improve the indoor six-component measurement and quantification of both the force and momentum acting on the three-point hitch.

兰州市采暖期居民室内PM2.5污染水平初步研究

目的了解兰州市采暖期居民室内PM2.5污染水平,并初步分析不同居住条件和人群时间-活动模式下室内PM2.5污染水平的差异。方法采用固定便携式空气采样泵进行室内(厨房和卧室)PM2.5样品收集,重量法分析室内PM2.5污染水平;同时进行住户基本情况及时间-活动模式的问卷调查。结果被调查的53户厨房、卧室PM2.5平均浓度分别为124.75、118.91μg/m3;西固区(污染区)与对照区的厨房、卧室PM2.5平均浓度差异无统计学意义(P>0.05)。79.3%(42/53)的厨房空气样品PM2.5浓度超过GB 3095—2012《环境空气质量标准》二级标准,卧室超标率为77.4%(41/53)。独栋楼房厨房PM2.5平均浓度(171.32μg/m3)高于单元楼房(115.22μg/m3);集中供暖户的厨房和卧室PM2.5平均浓度(109.51、97.78μg/m3)均低于安装烟囱煤炉者(167.23、177.75μg/m3);燃煤厨房PM2.5平均浓度(203.56μg/m3)高于燃气厨房(113.58μg/m3)和用电厨房(107.31μg/m3);采样24 h内总做饭时间>1 h的厨房和卧室PM2.5平均浓度高于≤1 h者,差异均有统计学意义(P<0.05或P<0.01)。结论本次调查的兰州市采暖期居民室内PM2.5污染比较严重,其污染水平受到住房条件、取暖方式、燃料类型及做饭时间的影响。

替加环素不敏感鲍曼不动杆菌的分子流行病学及耐药机制

为探讨替加环素不敏感鲍曼不动杆菌Acinetobacter baumannii的耐药机制,为院内感染控制及临床合理用药提供理论依据,采用琼脂稀释法和微量肉汤稀释法检测全国多中心12个城市20家医院临床分离的94株非重复的替加环素不敏感鲍曼不动杆菌的最低抑菌浓度(Minimum inhibitory concentration,MIC),应用多位点序列分型(Multilocus sequence typing,MLST)技术进行分子流行病学研究,应用eBURST软件对MLST结果进行分析;用PCR和测序技术分析常见耐药基因(bla_(OXA-40-like)、bla_(OXA-58-like)、bla_(OXA-23-like)、bla_(OXA-51-like)、bla_(NDM-1)),与替加环素耐药相关的外排泵调控基因adeR和adeS的突变位点、trm的突变位点。经检测94株鲍曼不动杆菌除对多粘菌素B 100%敏感、对米诺环素敏感率25.5%外,其他抗菌药物的敏感率均低于3.5%,亚胺培南和美罗培南敏感率均只有1.1%。MLST分型得到12种ST分型,以ST195(45株,47.9%)、ST208(19株,20.2%)和ST457(10株,10.6%)为主,eBURST分析发现其中8个ST型均属于克隆复合体92(Clonal Complex 92,CC92);99%菌株bla_(OXA-23-like)型碳青霉烯酶基因阳性;均未扩增出bla_(NDM-1)基因;外排泵调控基因adeR和adeS的检出率分别是73.4%和91.5%,Asp26Asn和Ala97Glu分别为adeR和adeS的高频突变位点;在12株鲍曼不动杆菌中检测到了adeS基因的ISAba1,以北部地区为主;trm基因均在第240位核苷酸发生缺失突变。综上所述,替加环素不敏感鲍曼不动杆菌对除多粘菌素B外的大多数抗菌药物具有很高的耐药性,AdeABC外排泵上游的双组分调控系统adeR和adeS的缺失和突变,trm缺失突变是导致鲍曼不动杆菌对替加环素敏感性降低的主要原因。

Manganese methionine hydroxy analog chelated affects growth performance,trace element deposition and expression of related transporters of broilers

The present study aimed to evaluate the effects of manganese methionine hydroxyl analog chelated(Mn-MHAC)as a manganese(Mn)source on growth performance and trace element deposition in broilers.A total of 432 Arbor Acres commercial female broilers were fed a basal corn-soybean diet containing Mn at 25.64 mg/kg diet for 10 d.They were then randomly assigned to 6 groups,including a control group(the basal diet),a Mn sulfate group(the basal diet supplemented with Mn at 100 mg/kg diet),and 4 Mn-MHAC groups(the basal diet supplemented with Mn-MHAC at 25,50,75 and 100 mg Mn/kg diet,respectively).The results showed that compared with the control group,groups supplemented with Mn-MHAC had a positive effect on BW(quadratic,P=0.017)and ADG(quadratic,P=0.017).Moreover,the Mn-MHAC(50 mg Mn/kg diet)group had significantly greater BW and ADG(P<0.05)compared with the other Mn-MHAC groups.Trace element deposition results also showed that tibial Mn increased(linear or quadratic,P-0.002 and 0.009,respectively)in groups fed diets with increased levels of Mn-MHAC.In contrast,Fe deposition decreased both in the heart(linear,P-0.020)and tibia(P<0.05).In addition,the Mn-MHAC supplement noticeably lowered serum Mn-SOD activity(linear or quadratic,P-0.048 and 0.019,respectively).The relative mRNA levels of divalent metal transporter 1(DMT1)(P=0.024),ferro-portin 1(FPN1)(P=0.049),and Cu transporter-1(CTR1)(P<0.001)in the duodenum,as well as CTR1 in the jejunum and ileum(P=0.040 and 0.011,respectively)were higher in the Mn-supplemented group than in the control group.Furthermore,the relative mRNA level of DMT1 in the jejunum and ileum of broilers in the Mn-MHAC group(50 mg Mn/kg diet)did not differ from those in the control group,but was lower than those in the Mn sulfate group(P<0.05).In conclusion,Mn-MHAC dietary supplementation improved the growth performance and trace element deposition in broilers.From this study,we recommend the opti-mum Mn-MHAC level to meet the Mn requirement of broilers is 50 to 75 mg Mn/kg diet.

Ultralight and ordered lamellar polyimide-based graphene foams with efficient broadband electromagnetic absorption

The development of high-performance microwave absorption materials with strong absorption capacity and broad bandwidth is highly desirable in the field of electromagnetic pollution protection.Herein,ultralight polyimide-based graphene foam with ordered lamellar structure is precisely designed and controllably constructed by bidirectional freezing process.More lamellar interfaces formed inside the foam per unit volume effectively facilitate the layer-by-layer dissipation for the vertical incident electromagnetic waves,thereby endowing the foam with efficient broadband electromagnetic absorption performance.More importantly,electromagnetic absorption performance can be controllably adjusted by optimizing impedance distribution and microstructure of skeletons.As a result,the optimized foam with an ultralow density of 9.10 mg/cm^(3)presents a minimum reflection loss value of-61.29 dB at 9.25 GHz and an effective absorption bandwidth of 5.51 GHz(7.06-12.57 GHz,covering the whole X band) when the thickness is 4.75 mm.

High-power narrow-linewidth diode laser pump source based on high-efficiency external cavity feedback technology

In this research,the highly efficient external cavity feedback technology based on volume Bragg grating(VBG)is studied.By using the structure of a fast axis collimating lens,the beam transformation system,a slow axis collimating lens,and VBG,the divergence angle of the fast and slow axes of the diode laser incident on the VBG is reduced effectively,and the feedback efficiency of the external cavity is improved.Combined with beam combining technology,fiber coupling technology,and precision temperature control technology,a high-power and narrow-linewidth diode laser pump source of kilowatt class is realized for alkali metal vapor laser pumping.The core diameter of the optical fiber is 1000μm,the numerical aperture is 0.22,the output power from the fiber is 1013 W,the fiber coupling efficiency exceeds 89%,and the external cavity efficiency exceeds 91%.The central wavelength is 852.052 nm(in air),which is tunable from 851.956 nm to 852.152 nm,and the spectral linewidth is 0.167 nm.Research results can be used for cesium alkali metal vapor laser pumping.

A promising trend for field information collection:An air-ground multi-sensor monitoring system

Timely identifying and quantifying significant spatial and temporal variability in agricultural field has been a crucial factor for improving agricultural production and management.This paper focuses on the mainstream techniques and applications can be adopted to improve the field information collection method.In this paper,the development of wireless sensor networks(WSNs)and remote sensing(RS)technology were reviewed,especially the micro unmanned aerial vehicle(mUAV)-based WSNs and mUAV-based RS by analyzing its applications in field information collection,and pointed out its existing benefits and limitations.A system encompassed multiple technique approaches was proposed in this paper which is called air-ground multi-sensor monitoring system.With the diversification methods of in-field information collection and the improvement of detection precision,an infield information collection system will play an important role in controlling the farming operations of mechanized agriculture and optimizing the management of agricultural machinery group.In the future,the combination of mUAV,WSNs and RS for crop and soil monitoring will become a powerful tool to obtain field information,increase production,optimize the overall farming practices and input of resources and provide comprehensive reference for the study of soil-crops-machine relationships.