Effects of Different Potassium Stress on Leaf Photosynthesis and Chlorophyll Fluorescence in Maize (Zea Mays L.) at Seedling Stage

Leaf early senescence caused by nutrition deficiency is one of the major limitation reasons in the world crop production. Potassium (K) is one of important nutrient elements in crop growth, which modifies dozens of enzyme activations and controls stomatal movement of photosynthesis. The yield and quality of maize (Zea Mays L.) have been limited due to K deficiency in plough layer soil. However, the mechanism of K deficiency tolerance is not fully understood in maize. In this study, two inbred lines, 099 (tolerance to potassium deficiency) and 835 (sensitive to potassium deficiency) were carried out to investigate the variations of chlorophyll content, photosynthetic and chlorophyll fluorescence parameters related with senescence under different K+ concentrations in maize at seedling stage. The results showed that the Chlorophyll a, b and (a + b) of 835 were significantly decreased under different K deficiency treatments, whereas those of 099 were remained normal. In addition, 099 showed a lower stomatal restriction and higher electronic transition capacity under different K deficiency treatments. The variations of F0, Fv/Fm, ΦPSⅡ, qP and NPQ in 835 were largely higher than those in 099. These results indicated that the inbred line 099 tolerance to K deficiency could keep chlorophyll content to maintain photosynthesis and to alleviate the injury of PSII under K deficiency condition. This study should contribute to explaining the physiological mechanism tolerance nutrition deficiency and improving breeding program in maize.

Analysis of Seed Phenotypic and Metabolic Characteristics of Diploid and Tetraploid Tartary Buckwheat

Polyploid plants grow well,are stress tolerant,and are rich in nutrients and bioactive compounds.Thus,they are useful for improving crop quality and yield.In this study,we compared the seed characteristics and metabolite profiles of diploid and tetraploid tartary buckwheat,which was developed via an artificially induced chromosome doubling event.The length,width,area,and thousand-grain weight were greater for the tetraploid seeds than for the diploid seeds.However,the germination rate decreased for the tetraploid seeds.Additionally,there was a gap between the shell and kernel of the tetraploid seeds.Moreover,the water absorption rate was higher for the tetraploid than for the diploid seeds.Chromosome doubling increased the seed total flavonoid content and deepened the seed color.A principal component analysis of the ultrahigh-pressure liquid chromatography-high resolution mass spectrometry data revealed the clear separation between the diploid and tetraploid samples.An orthogonal partial least squares-discriminant analysis and other multivariate statistical analyses identified 83 differentially abundant compounds,with most of the flavonoid metabolites more abundant in the tetraploid than in the diploid seeds.Research on tartary buckwheat polyploidy may result in enhanced germplasm resources and may clarify the mechanism underlying the biosynthesis of bioactive compounds.

Computational uncertainty and optimal grid size and time step of the Lax-Friedrichs scheme for the 1D advection equation

本文对于应用Lax-Friedrichs格式数值求解一维平流方程,研究数值求解过程中产生的截断误差与舍入误差,以及两种误差逐层向高时间层传播的累积,得到新的数值解总误差上界的理论近似公式,以及最优格距和最优时间步长的理论公式.通过数值算例验证了所得公式的可靠性。然后,发现了两种不同机器精度下最优时间步长之比满足的一个仅与机器精度有关的普适关系.最后,理论验证了在网格比固定的情况下,此问题满足数值计算的不确定性原理,以及在机器有限精度下最优时间步长的必然存在。

Distribution of per-and polyfluoroalkyl substances in blood,serum,and urine of patients with liver cancer and associations with liver function biomarkers

Studies have shown that per-and polyfluoroalkyl substances(PFASs)may be hepatotoxic in animals or humans.However,data on clinical epidemiology are very limited.In this study,21PFASs were determined in patients with liver diseases,with the highest median concentrations detected in the serum sample(26.7 ng/mL),followed by blood(10.7 ng/mL)and urine(5.02 ng/mL).Higher total PFAS concentrations were found in hepatocellular carcinoma(HCC)patients compared to non-HCC patients,with significant discrepancies in serum and blood samples.Besides,significant correlations were also found among PFAS concentrations and age,gender,body mass index(BMI),and liver function biomarkers levels.For example,PFAS concentrations are significantly higher in males than in females;Several serum PFASs concentrations increase with age and BMI,while the serum perfluorohexane sulfonic acid(PFHxS)concentrations are negatively correlated with age.In addition,multiple regression models adjusted for age,gender and BMI found that increased serum perfluorobutane sulfonic acid(PFBS),perfluoroheptane sulfonic acid(PFHpS)and perfluorohexylphosphonic acid(PFHxPA)conentrations are correlated with elevated alkaline phosphatase(ALP),aspartate aminotransferase(AST),and alpha-fetoprotein(AFP)(p<0.05).Our results provide epidemiological support for the future study on the potential clinical hepatotoxicity of PFAS.

高质量和深度凹陷的PtPdNi纳米立方体作为高效氧还原反应的催化剂

聚合物电解质燃料电池阴极上的氧还原反应需要使用铂基催化剂,铂是地球上的贵金属之一.采用将不同的金属优化到核心中等多种策略可提高铂基催化剂的活性,从而降低铂的负载量.通过致力于高催化活性Pt_(2.7)Pd_(0.3)Ni凹面立方结构与高指数晶面的复合,表明凹面结构可以提供更多的活性位和高水平的催化活性,如果与其他金属复合,可以降低铂的比例,提高其质量活性.本文采用一锅法合成了PtPdNi凹立方体结构,并发现DMF和油胺的比例是影响PtPdNi凹陷程度的主要因素.通过对PtPdNi凹立方体的形态和组成进行详细表征,研究了PtPdNi凹立方体的形成机理,认为十六烷基三甲基溴化铵、油酸胺和二甲基甲酰胺的比例在PtPdNi凹立方体的合成中起着关键作用.本文还对Pt_(2.7)Pd_(0.3)Ni凹立方结构形成的理论和条件进行了探讨,并通过改变反应条件,考察了其所表现出的差异.电化学测试的氧还原性能结果表明,凹面立方体形状的PtPdNi催化剂在0.9 V下的质量活性为1.28 mg_(Pt)^(–1),最高质量活性和比活性分别是市售铂炭的8.20倍和8.68倍.铂钯镍三元纳米笼具有优异的结构稳定性,经稳定性测试,纳米结构没有明显的变化和性能退化.PtPdNi凹立方体对阴极具有很高的电催化活性和稳定性,燃料电池的氧还原反应由于高凹度、高空间利用率和PtPdNi凹立方体丰富的高指数表面以及PtPdNi之间的协同效应,为进一步控制铂基纳米催化剂的合成提供更多的思路和方法及未来工业应用的不同形态和结构.

Fabrication of micro-scale gratings for moiré method with a femtosecond laser

Fabrication of micro gratings using a femtosecond laser exposure system is experimentally investigated for the electron moiré method. Micro holes and lines are firstly etched for parameter study. Grating profile is theoretically optimized to form high quality moiré patterns. For a demonstration, a parallel grating is fabricated on a specimen of quartz glass. The minimum line width and the distance between two adjacent lines are both set to be 1 μm, and the frequency of grating is 500 lines/mm. The experimental results indicate that the quality of gratings is good and the relative error of the gratings pitch is about1.5%. Based on moiré method, scanning electron microscope(SEM) moiré patterns are observed clearly,which manifests that gratings fabricated with the femtosecond laser exposure is suitable for micro scale deformation measurement.

An Implementation of Full Cycle Strategy Using Dynamic Blending for Rapid Refresh Short-range Weather Forecasting in China

The partial cycle(PC)strategy has been used in many rapid refresh cycle systems(RRC)for regional short-range weather forecasting.Since the strategy periodically reinitializes the regional model(RM)from the global model(GM)forecasts to correct the large-scale drift,it has replaced the traditional full cycle(FC)strategy in many RRC systems.However,the extra spin-up in the PC strategy increases the computer burden on RRC and generates discontinuous smallscale systems among cycles.This study returns to the FC strategy but with initial fields generated by dynamic blending(DB)and data assimilation(DA).The DB ingests the time-varied large-scale information from the GM to the RM to generate less-biased background fields.Then the DA is performed.We applied the new FC strategy in a series of 7-day batch forecasts with the 3-hour cycle in July 2018,and February,April,and October 2019 over China using a Weather Research and Forecast(WRF)model-based RRC.A comparison shows that the new FC strategy results in less model bias than the PC strategy in most state variables and improves the forecast skills for moderate and light precipitation.The new FC strategy also allows the model to reach a balanced state earlier and gives favorable forecast continuity between adjacent cycles.Hence,this new FC strategy has potential to be applied in RRC forecast systems to replace the currently used PC strategy.

Prevalence and clinical characteristics of atrial fibrillation in hospitalized patients with coronary artery disease and hypertension: a cross-sectional study from 2008 to 2018

Background: The clinical characteristics of patients with the comorbidities of hypertension and coronary artery disease (HT-CAD) and atrial fibrillation (AF) are largely unknown. This study aimed to investigate the prevalence of AF in patients with HT-CAD and clinical characteristics of patients with both HT-CAD and AF. Methods: This cross-sectional study was conducted in Chinese People’s Liberation Army General Hospital in Beijing, China, and included 20,747 inpatients with HT-CAD with or without AF from August 2008 to July 2018. We examined the overall prevalence, clinical characteristics, comorbidity profiles, treatment patterns, and blood pressure (BP) control of patients with both HT-CAD and AF. Multivariate logistic regression was used to investigate the associations of cardiovascular risk factors with AF in patients with HT-CAD. Results: The overall prevalence of AF in patients with HT-CAD was 4.87% (1011/20,747), and this increased with age;to be specific, the prevalence in women and men increased from 0.78% (2/255) and 1.02% (26/2561) at the age of <50 years to 8.73% (193/2210) and 10.28 % (298/2900) at the age of ≥70 years, respectively. HT-CAD patients who had AF had a higher prevalence of cardiovascular-related comorbidities than those without AF. Multivariate logistic regression showed that age, gender (male), body mass index, heart failure, and chronic kidney disease were independently associated with the risk of AF in patients with HT-CAD. For those with both HT-CAD and AF, 73.49% (743/1011) had a CHA 2 DS 2 -VASc score of ≥4, and only about half of them had the BP controlled at <140/90 mmHg, which indicated a high risk of thromboembolism and stroke. The use of oral anticoagulation increased during the study period (10.00% [20/200] in 2008 to 2011 vs. 30.06% [159/529] in 2015 to 2018, P < 0.01), but remained at a relatively low level. Conclusions: AF is highly prevalent among patients with HT-CAD. Patients with both HT-CAD and AF have a higher prevalence of cardiovascular-related comorbidities, lower BP control rate, and lower use of oral anticoagulation.

Some considerations on the rheology of dense frictional cylindrical particles

Discrete element method simulations of granular shear flows of frictional cylindrical particles are performed. From the simulations, solid-phase pressure, shear stress, and bulk friction coefficient μ can be measured, allowing the investigation of the effects of particle properties on the macroscopic flow behaviors. Thus, the inertial number I based rheological models, which were frequently used for the spherical particles in the previous work, are examined for the applicability to cylindrical particles in the present study. It is found that the particle aspect ratio, interparticle friction coefficient, and particle size polydispersity all affect the bulk friction coefficient-inertial number correlation and the solid volume fraction-inertial number correlation, and their effects vary in different flow regimes, which exhibit different mechanical behaviors.

Successful Stenting for Pulmonary Vein Thrombosis Complicating Pulmonary Vein Stenosis Following Atrial Fibrillation Ablation:A Case Report

Pulmonary vein thrombosis is a rare disease and is usually represented as a complication of pulmonary tumors,lung lobectomy,and atrial fibrillation ablation.Although it is a potentially life-threatening condition,it is easily misdiagnosed because of non-specific symptoms and its characteristics on imaging modalities.Here,we report a case of thrombotic occlusion at the ostium of the left superior pulmonary vein resulting from pulmonary vein stenosis following radiofrequency ablation for atrial fibrillation.This report extends the available approach with anticoagulant therapy and interventional angioplasty to pulmonary vein thrombosis secondary to pulmonary vein stenosis.

Mesoporous silica stabilized MOF nanoreactor for highly selective semi-hydrogenation of phenylacetylene via synergistic effect of Pd and Ru single site

Selective semi-hydrogenation of phenylacetylene to styrene is a crucial step in the polystyrene industry.Although Pd-based catalysts are widely used in this reaction due to their excellent hydrogenation activity,the selectivity for styrene remains a great challenge.Herein,we designed a mesoporous silica stabilized Pd-Ru@ZIF-8(MS Pd-Ru@ZIF-8)nanoreactor with novel Pd and Ru single site synergistic catalytical system for semi-hydrogenation of phenylacetylene.The nanoreactor exhibited a superior performance,achieving 98%conversion of phenylacetylene and 96%selectivity to styrene.Turnover frequency(TOF)of nanoreactor was up to as high as 2,188 h^(−1),which was 25 times and 5 times more than the single metal species catalysts,mesoporous silica stabilized Pd@ZIF-8 nanoreactor(MS Pd@ZIF-8),and mesoporous silica stabilized Ru@ZIF-8 nanoreactor(MS Ru@ZIF-8).This catalytic activity was attributed to the synergistic effect of Pd and Ru single site anchored strongly into the framework of ZIF-8,which reduced the desorption energy of styrene and increased the hydrogenation energy barrier of styrene.Importantly,since the ordered mesoporous silica was introduced into the nanoreactor shell to stabilize ZIF-8,MS Pd-Ru@ZIF-8 showed excellent reusability and stability.After the five cycles,the catalytical activity and selectivity still remained.This work provides insights for a synergistic catalytic system based on single-site active sites for selective hydrogenation reactions.

Coronas around Olivine in the Miaowan Olivine Norite, Yangtze Craton, South China

Coronitic microstructures have been used to interpret the late-stage solidification history of igneous rocks and to constrain the corresponding chemical and/or physical changes. Coronas with three shells were also recognized in the Miaowan olivine norite, Yangtze Craton, South China. In our study, orthopyroxene intergrowth with vermicular magnetite in the inner shell is in optical continuity with magnetite-free orthopyroxene in the middle shell. In the outer shell of brown amphibole remaining magnetite-free orthopyroxene inclusions sporadically occur. Meanwhile Mg# values of orthopyroxene(76–80) in the inner and middle shells are basically consistent with olivine(78–81). In this paper, we propose a multi-stage genetic model for the formation of coronas in the Miaowan olivine norite. In the first stage, the magnetite-free orthopyroxene shell formed through reaction between primocrystal olivine with the residual Si-rich melt at 990–1 053 ℃ and 6.2–6.5 kbar. In the second stage, the orthopyroxene-magnetite symplectite shell formed when primocrystal olivine reacted with the late-stage residual Fe-rich melt promoted by high oxygen fugacity condition at 927–1 035 ℃ and 6.0–6.5 kbar. In the third stage, the brown amphibole shell formed as the presence of residual hydrous melt and replaced the middle shell at 821–900 ℃ and 5.5–6.0 kbar.

Identification of Expression Pattern and Clinical Significance of the Small Cajal Body-specific RNA SCARNA16 in Hepatocellular Carcinoma

Background and Aims:For high morbidity and mortality,hepatocellular carcinoma(HCC)becomes a major health issue worldwide.Nowadays,numerous non-coding RNAs(ncRNAs)are known to regulate the occurrence and patho-genesis of tumors.Some ncRNAs have also been developed as tumor biomarkers and therapeutic targets.However,the potential function of the small Cajal body-specific RNA(scaRNA)SCARNA16,a newly identified ncRNA,remains to be explored in HCC.Methods:In both HCC cell lines and specimens from 120 enrolled patients,the expression val-ues of SCARNA16 were detected.We divided patients into SCARNA16 high and low expression subgroups,and then analyzed the difference of various clinical characteristics and prognosis data between subgroups.Results:Compared to paired controls,SCARNA16 was significantly down-regulated in HCC cell lines and clinical specimens(p<0.01).Besides,HCC patients with lower SCARNA16 expression commonly presented with larger and more tumor lesions,more ves-sel carcinoma emboli,more capsular invasion and higher TNM stages(p<0.05).Moreover,SCARNA16 expression was negatively correlated with postoperative prognosis of HCC patients in 5-year follow-up,including tumor-free survival(TFS)(median time of low vs.high subgroups:14 vs.48 months,p=0.006)and overall survival(OS)(median time of low vs.high subgroups:39 vs.52 months,p=0.001).Besides,SCARNA16 acted as an independent prognostic bio-marker in TFS(hazard ratio[HR]:0.578,95%CI:0.345-0.969,p=0.038)and OS(HR:0.366,95%CI:0.178-0.752,p=0.006).Conclusions:Low expression patterns of SCAR-NA16 remarkably associated with severe clinical status and poor survival of patients,suggesting that SCARNA16 pos-sesses potency as a novel biomarker for HCC.

Enabling Breeding Selection for Biomass in Slash Pine Using UAV-Based Imaging

Traditional methods used to monitor the aboveground biomass(AGB)and belowground biomass(BGB)of slash pine(Pinus elliottii)rely on on-ground measurements,which are time-and cost-consuming and suited only for small spatial scales.In this paper,we successfully applied unmanned aerial vehicle(UAV)integrated with structure from motion(UAV-SfM)data to estimate the tree height,crown area(CA),AGB,and BGB of slash pine for in slash pine breeding plantations sites.

中国乳腺癌自然史参数选择的优化方法

乳腺癌是女性最常见的恶性肿瘤之一。为了提出有效的筛查策略并评估其效果,一个基本且重要的步骤是在中国乳腺癌自然史模型中选择合适的参数,即转移概率.选择合理的转移概率有两个挑战.首先,由于乳腺癌的流行病学特性,其他国家使用的转移概率不一定适用于中国.其次,可用的筛查样本数据很少,这使得传统的基于统计的方法(如极大似然估计法)失效.本文从优化角度提出一种乳腺癌自然史参数选择的方法,基于公布的统计数据建立数学优化模型.该模型的挑战在于目标函数高度非线性且无显式表达式,本文提出一种坐标下降算法来处理这个挑战.最后,本文提出一种最佳匹配方法来估计每个转移概率的分布.本文所提出的方法为进一步提出合理的中国乳腺癌筛查策略和分析乳腺癌的经济负担提供了坚实的基础.

Occurrence and infection risk of waterborne pathogens in Wanzhou watershed of the Three Gorges Reservoir, China

The Three Gorges Reservoir (TGR), formed by China's Yangtze Three Gorges Project, is the largest lake in the world, but there is too little information available about fecal contamination and waterborne pathogen impacts on this aquatic ecosystem. During two successive 1-year study periods (July 2009 to July 2011), the water quality in Wanzhou watershed of the TGR was tested with regard to the presence of fecal indicators and pathogens. According to Chinese and World Health Organization water quality standards, water quality in the mainstream was good but poor in backwater areas. Salmonella, Enterohemorrhagic Escherichia coli (EHEC), Giardia and Cryptosporidium were detected in the watershed. Prevalence and concentrations of the pathogens in the mainstream were lower than those in backwater areas. The estimated risk of infection with Salmonella, EHEC, Cryptosporidium, and Giardia per exposure event ranged from 2.9 × 10 -7 to 1.68 × 10-5 , 7.04 × 10-10 to 2.36 × 10-7 , 5.39 × 10-6 to 1.25 × 10-4 and 0 to 1.2 × 10-3 , respectively, for occupational divers and recreational swimmers exposed to the waters. The estimated risk of infection at exposure to the 95% upper confidence limit concentrations of Salmonella, Cryptosporidium and Giardia may be up to 2.62 × 10-5 , 2.55 × 10-4 and 2.86 × 10-3 , respectively. This study provides useful information for the residents, health care workers and managers to improve the safety of surface water and reduce the risk of fecal contamination in the TGR.

The Residual Strain Measurement of Thin Conductive Metal Wire after Electrical Failure with SEM Moir

In this study, the residual strain of a thin conductive metal wire on a polymer substrate after electrical failure is measured with SEM moir′e. Focused ion beam(FIB) milling is applied to fabricate micron moir′e gratings on the surfaces of constantan wires and the random phase shifting technique is used to process moir′e fringes. The virtual strain method is briefly introduced and used to calculate the real strain of specimens. In order to study the influence of a defect on the electrical failure of the constantan wire, experiments were conducted on two specimens, one with a crack, while the other one without any crack. By comparing the results, we found that the defect makes the critical beam current of electrical failure decrease. In addition, the specimens were subjected to compression after electrical failure, in agreement with the observed crack closure of the specimen. The successful results demonstrate that the moir′e method is effective to characterize the full-field deformation of constantan wires on the polymer membrane, and has a good potential for further application to the deformation measurement of thin films.

Spectrometric Prediction of Nitrogen Content in Different Tissues of Slash Pine Trees

The internal cycling of nitrogen(N)storage and consumption in trees is an important physiological mechanism associated with tree growth.Here,we examined the capability of near-infrared spectroscopy(NIR)to quantify the N concentration across tissue types(needle,trunk,branch,and root)without time and cost-consuming.The NIR spectral data of different tissues from slash pine trees were collected,and the N concentration in each tissue was determined using standard analytical method in laboratory.

ExtSpecR:An R Package and Tool for Extracting Tree Spectra from UAV-Based Remote Sensing

The development of unmanned aerial vehicle(UAV)remote sensing has been increasingly applied in forestry for high-throughput and rapid acquisition of tree phenomics traits for various research areas.However,the detection of individual trees and the extraction of their spectral data remain a challenge,often requiring manual annotation.Although several software-based solutions have been developed,they are far from being widely adopted.This paper presents ExtSpecR,an open-source tool for spectral extraction of a single tree in forestry with an easy-to-use interactive web application.ExtSpecR reduces the time required for single tree detection and annotation and simplifies the entire process of spectral and spatial feature extraction from UAV-based imagery.In addition,ExtSpecR provides several functionalities with interactive dashboards that allow users to maximize the quality of information extracted from UAV data.ExtSpecR can promote the practical use of UAV remote sensing data among forest ecology and tree breeding researchers and help them to further understand the relationships between tree growth and its physiological traits.