Mapping soil organic matter in cultivated land based on multi-year composite images on monthly time scales

Rapid and accurate acquisition of soil organic matter(SOM)information in cultivated land is important for sustainable agricultural development and carbon balance management.This study proposed a novel approach to predict SOM with high accuracy using multiyear synthetic remote sensing variables on a monthly scale.We obtained 12 monthly synthetic Sentinel-2 images covering the study area from 2016 to 2021 through the Google Earth Engine(GEE)platform,and reflectance bands and vegetation indices were extracted from these composite images.Then the random forest(RF),support vector machine(SVM)and gradient boosting regression tree(GBRT)models were tested to investigate the difference in SOM prediction accuracy under different combinations of monthly synthetic variables.Results showed that firstly,all monthly synthetic spectral bands of Sentinel-2 showed a significant correlation with SOM(P<0.05)for the months of January,March,April,October,and November.Secondly,in terms of single-monthly composite variables,the prediction accuracy was relatively poor,with the highest R^(2)value of 0.36 being observed in January.When monthly synthetic environmental variables were grouped in accordance with the four quarters of the year,the first quarter and the fourth quarter showed good performance,and any combination of three quarters was similar in estimation accuracy.The overall best performance was observed when all monthly synthetic variables were incorporated into the models.Thirdly,among the three models compared,the RF model was consistently more accurate than the SVM and GBRT models,achieving an R^(2)value of 0.56.Except for band 12 in December,the importance of the remaining bands did not exhibit significant differences.This research offers a new attempt to map SOM with high accuracy and fine spatial resolution based on monthly synthetic Sentinel-2 images.

Efficacy analysis and multi-factor retrospective study of third-line chemotherapy in 82 Chinese patients with small cell lung cancer

Objective As there is currently no clear recommendation for third-line chemotherapy for small cell lung cancer(SCLC), its efficacy is unknown. To date, there have rarely been reports of Chinese patients with SCLC who received third-line chemotherapy. Therefore, we investigated the efficacy, safety, and prognostic factors of Chinese patients with SCLC treated with third-line chemotherapy.Methods A retrospective analysis of patients with SCLC who received third-line chemotherapy was performed.Results Between 2007 and 2013, 82 patients [62 men(75.6%), 20 women(24.4%); median age at the time of diagnosis, 55 years] received third-line chemotherapy at our center. Of these patients, 44 had limited-stage disease and 38 had extensive-stage disease. On third-line chemotherapy, 55(67.1%) patients had an Eastern Cooperative Oncology Group performance status(ECOG PS) of 0–1, objective response rate of 15.9%, and median overall survival after third-line chemotherapy(OS-3) and median progression-free survival after third-line chemotherapy(PFS-3) of 5.6 months and 3.0 months, respectively. On univariate analysis, PFS-3 was significantly related with ECOG PS(P = 0.005), response to second-line chemotherapy(P = 0.002), response to third-line chemotherapy(P < 0.001), and PFS after second-line chemotherapy(P = 0.026). OS-3 was significantly related with ECOG PS(P < 0.001), response to thirdline chemotherapy(P = 0.033), PFS after first-line therapy(P = 0.044), and PFS after second-line therapy(PFS-2)(P = 0.007). On multivariate analysis, ECOG PS(P = 0.008) and response to third-line chemotherapy(P = 0.046) were independent prognostic factors for PFS-3, while ECOG PS(P = 0.007) and PFS-2(P < 0.001) were independent prognostic factors for OS-3.Conclusion Few patients with SCLC receive third-line chemotherapy. Our findings suggest that patients with an ECOG PS 0–1 and PFS-2 for >3 months will be benefit from third-line chemotherapy, which should be actively offered to them.

Long noncoding RNA TFAP2A-AS1 exerts promotive effects in non-small cell lung cancer progression via controlling the microRNA-548a-3p/CDK4 axis as a competitive endogenous RNA

In this study,we mainly focus on probing expression profile and detailed functions of long non-coding RNA TFAP2A antisense RNA 1(TFAP2A-AS1)in non-small cell lung cancer(NSCLC).Moreover,the mechanisms played by TFAP2A-AS1 were unraveled comprehensively.Herein,a notable overexpressed TFAP2A-AS1 in NSCLC was observed by TCGA and our own cohort.An increased TFAP2A-AS1 level displayed a negative correlation with the overall survival of patients with NSCLC.Loss-of-function approaches illustrated that the absence of TFAP2A-AS1 weakened NSCLC cell proliferation,colony formation,migration and invasion in vitro.Also,interference of TFAP2A-AS1 caused in vivo tumor growth suppression.Mechanistically,TFAP2A-AS1 could negative regulate microRNA-584-3p(miR-584-3p)as a competitive endogenous RNA.Furthermore,cyclin-dependent kinase 4(CDK4),a direct target of miR-584-3p,was positively controlled by TFAP2A-AS1 in a miR-5184-3p-dependent manner.Rescue function experiments corroborated that the anticancer activities of TFAP2A-AS1 deficient on the oncogenicity of NSCLC cells were reversed by downregulating miR-584-3p or overexpressing CDK4.To sum up,TFAP2A-AS1 exhibits cancerpromoting roles in NSCLC through the adjustment of miR-584-3p/CDK4 axis.

Incorporation of source contributions to improve the accuracy of soil heavy metal mapping using small sample sizes at a county scale

Estimating heavy metal(HM) distribution with high precision is the key to effectively preventing Chinese medicinal plants from being polluted by the native soil. A total of 44 surface soil samples were gathered to detect the concentrations of eight HMs(As, Hg, Cu, Cr, Ni, Zn, Pb, and Cd) in the herb growing area of Luanping County, northeastern Hebei Province, China. An absolute principal component score-multiple linear regression(APCS-MLR) model was used to quantify pollution source contributions to soil HMs. Furthermore, the source contribution rates and environmental data of each sampling point were simultaneously incorporated into a stepwise linear regression model to identify the crucial indicators for predicting soil HM spatial distributions. Results showed that 88% of Cu, 72% of Cr, and 72% of Ni came from natural sources;50% of Zn, 49% of Pb, and 59% of Cd were mainly caused by agricultural activities;and 44% of As and 56% of Hg originated from industrial activities. When three-type(natural, agricultural, and industrial) source contribution rates and environmental data were simultaneously incorporated into the stepwise linear regression model, the fitting accuracy was significantly improved and the model could explain 31%–86% of the total variance in soil HM concentrations. This study introduced three-type source contributions of each sampling point based on APCS-MLR analysis as new covariates to improve soil HM estimation precision, thus providing a new approach for predicting the spatial distribution of HMs using small sample sizes at the county scale.

晚期肺腺癌患者一线治疗前后EGFR基因突变差异性分析

背景与目的表皮生长因子受体(epidermal growth factor receptor, EGFR)靶向治疗能够显著提高EGFR突变的晚期肺腺癌患者预后生存,但治疗及异质性等因素可导致初次和疾病进展时EGFR基因状态发生改变。为了探讨真实世界中EGFR基因突变在疾病进展和基线时的差异,我们开展了此项研究。方法收集2015年1月-2017年12月在吉林省肿瘤医院进行EGFR基因检测的61例配对标本数据并进行分析。标本取材时间为治疗前和疾病进展时,所有标本均经病理学或细胞学证实,标本来源为肿瘤组织﹑恶性胸腔积液和血浆,患者为初治,一线接受化疗或靶向治疗,采用扩增阻滞突变系统法(Amplification Refractory Mutation System, ARMS)对29种EGFR基因突变进行检测。结果初次和再次活检相比(n=61),肿瘤组织、恶性胸腔积液和血浆标本所占的比例分别为90.2%vs 88.5%、6.6%vs 6.6%和3.2%vs 4.9%,其中标本类型前后一致的患者(n=50)EGFR突变差异率为72.0%,标本类型不一致患者(n=11)为36.3%;治疗前EGFR突变率为95.1%,治疗后为91.8%,二者的差异率为63.9%;化疗患者(n=13)治疗前EGFR突变率为69.2%,治疗后为92.3%,二者差异率为46.1%;靶向治疗患者(n=48)治疗前EGFR突变率为100%,治疗后为91.7%,二者差异率为70.8%。EGFR基因变化类型有4类:野生型变为突变型(4.9%)、突变消失(8.2%)、敏感突变类型互变(1.6%)和突变种类增加(49.1%)。结论临床实践中,晚期非小细胞肺癌(non-small cell lung cancer, NSCLC)患者由于标本取材部位和类型及治疗的影响,治疗前后EGFR基因突变具有较大差异性,动态检测并明确EGFR基因状态,可以为临床医生选择精准的后续靶向治疗方案提供参考。

Clinical characteristics and treatment strategies of acute ischemic stroke with internal carotid artery occlusion: a case report

Acute ischemic stroke has the characteristics of high disability,lethality and recurrence rate,which seriously threatens the health of middle-aged and elderly people.This article describes the acute ischemic stroke with internal carotid artery occlusion as the main clinical feature and discusses its treatment strategy.Treatment remedies:clinical diagnosis was carried out based on the present medical history,physical examination and craniocerebral CT(computed tomography).Neurological function was improved by intravenous thrombolysis,cerebrovascular angiography was used to clarify cerebrovascular occlusion,cerebral blood supply was identified by CT perfusion,and neurological function recovery was followed up.After intravenous thrombolysis,the patient’s consciousness turned clear and the right limb muscle strength recovery was not obvious,but the patient did not receive bridging therapy.Cerebral angiography showed about 90%stenosis at the beginning of the left internal carotid artery,and the blood flow terminated at the C7 segment.Cerebral CT perfusion imaging showed decreased perfusion in the left cerebral hemisphere,but the patient did not receive carotid endarterectomy and vascular bypass treatment.Post treatment evaluating:follow-up showed that NIHSS(National Institute of Health stroke scale)score was significantly decreased and limb function was significantly restored.Conclusion:early intravenous thrombolytic therapy can help reduce the area of ischemic penumbra and improve long-term prognosis.Severe vascular stenosis can stimulate vascular compensation,significantly reduce the range of ischemia when thrombus occurs,and effectively reduce the disability rate without bridging therapy.Whether vascular stenosis and occlusion are treated by vascular bypass,etc.,individualized plans should be made according to vascular compensation.

On the superplastic deformation mechanisms of near-αTNW700 titanium alloy

The new near-αTNW700 titanium alloy is a potential candidate material for high performance ultrasonic/hypersonic aircrafts,which is designed for short-term service at 700℃.This study systematically investigated the superplastic deformation microstructure evolution and mechanism of TNW700 alloy at different strain rates and true strains at 925℃.Results show that TNW700 alloy exhibits excellent superplastic behavior in a constant strain rate range of 0.0005-0.005 s^(-1) with elongation above 400%.The peak stress decreases with decreasing strain rate,which is related to the increase ofβ-phase volume fraction caused by the increase of thermal exposure time.In addition,significant strain hardening is observed in early-middle stage of superplastic deformation,and flow softening is followed in middle-late stage.To rationalize these complex flow behaviors,electron backscatter diffraction(EBSD)and high resolution transmission electron microscopy(HRTEM)were used to characterize the microstructure.Strain hardening is correlated to the synergistic effect ofβgrain growth,dislocation accumulation,silicide precipitate,and solid solution strengthening ofαphase.Continuous dynamic recrystallization(CDRX)induced the fragmentation of primaryαgrains in middle-late stage of superplastic deformation,and the refinement ofαgrains,the increase ofβphase volume fraction and dynamic dislocation recovery are main causes of high strain softening.In addition,EBSD and TEM observations confirmed texture randomization,fine equiaxed primaryαgrains and intragranular dislocation movement,indicating that grain boundary sliding(GBS)accommodated by dislocation sliding/climb is the dominant superplastic deformation mechanism of TNW700 alloy.

Highly efficient electrocatalytic nitrogen fixation enabled by the bridging effect of Ru in plasmonic nanoparticles

Plasmon-generated hot electrons show great potential for driving chemical reactions.The utilization efficiency of hot electrons is highly dependent on the interaction of the electronic states at the interfaces between plasmonic nanoparticles and other materials/molecules.Strong interaction can produce new hybridized electron states,which permit direct hot-electron transfer,a more efficient transfer mechanism.However,Au usually has very weak interaction with most molecules because of its inertness,which makes direct hot-electron transfer impossible.Herein,the improvement of the hot-electron transfer efficiency from Au to N_(2)is demonstrated by introducing a Ru bridging layer.Both the N_(2)fixation rate and Faradic efficiency(FE)are enhanced by the excitation of plasmons.The enhancement of the N_(2)fixation rate is found to arise from plasmon-generated hot electrons.Theoretical calculations show that the strong interaction of the Ru electronic states with the N_(2)molecular orbitals produces new hybridized electronic states,and the Ru d electrons also strongly couple with the Au sp electrons.Such a bridging role of Ru makes direct hot-electron transfer from Au to N_(2)possible,improving the FE of nitrogen fixation.Our findings demonstrate a new approach to increasing the utilization efficiency of plasmonic hot electrons for chemical reactions and will be helpful to the design of plasmonic catalysts in the future.

猪miR-331-3p过表达载体的构建及其对细胞增殖的影响

本研究旨在阐明猪miR-331-3p对细胞增殖的影响,探讨其对细胞增殖的作用机制首先构建了miR-331-3p的过表达载体pcDNA 3.1 (+)-miR-331-3p,并将将PK15细胞分为4组,分别为实验组、实验组对照组、抑制剂组和抑制剂对照组。实验组和对照组分别转染pcDNA 3.1(+)-miR-331-3p和pcDNA 3.1(+)。抑制剂组和抑制剂对照组分别转染miR-331-3p Inhibitor和miR-331-3p阴性对照(miR-331-3p NC)。通过在各组添加CCK-8试剂绘制细胞增殖曲线,并使用PI染色检测细胞所处周期比例。同时,利用实时荧光定量PCR(Quantitative real-time PCR,qPCR)检测生长抑制蛋白家族成员5 (Inhibitor of growth family member 5,ING5)、细胞周期蛋白依赖性激酶2 (Cyclin dependent kinase 2,CDK2)、细胞周期蛋白依赖性激酶3 (Cyclin dependent kinase 3,CDK3)、细胞周期蛋白依赖性激酶4 (Cyclin dependent kinase 4,CDK4)、细胞周期蛋白B (Cyclin B)和细胞周期蛋白依赖性激酶抑制剂1A(Cyclindependentkinaseinhibitor1A,CDKN1A)的表达变化。结果表明,实验组miR-331-3p表达量显著升高,细胞增殖曲线表明48 h和72 h时细胞数目均呈现出实验组>实验对照组和抑制剂对照组>抑制剂组的趋势(P<0.05)。与实验对照组相比,实验组处于G0/G1期的细胞比例下调,S期和G2/M细胞的比例上调,抑制剂对照组趋势与之相反;同时,实验组中与促进增殖的基因CDK2、CDK3、CDK4和CyclinB的mRNA表达水平均显著升高,而抑制增殖的基因ING5和CDKN1A均表现出显著下降的趋势。本研究成功构建了miR-331-3p过表达载体,且发现miR-331-3p具有促进猪肾上皮细胞增殖的能力,研究结果为深入研究miR-331-3p在猪生长发育中的作用机制奠定了基础。