Vertical distributions of VOCs in the Tibetan Plateau background region

Exploring the vertical variation in volatile organic compounds(VOCs)in background regions can provide infor-mation on the spatial distribution of pollutants,providing a scientific basis for atmospheric pollution prevention and control strategies.From 15 August to 5 September 2023,at the Southeast Tibet Mountain Comprehensive Environmental Observation Station(SETS),a tethered balloon was used to sample VOCs every 100 m from the ground to 1000 m.A total of 403 air bag samples were collected,and 39 vertical profiles of VOCs were obtained.Ninety-two VOC species were detected.The VOC concentration at the SETS did not change significantly verti-cally,and the average VOC concentration was 11.1±2.4 ppbv.The main components were alkanes(51.4%),alkenes(18.7%),and halohydrocarbons(18.1%).There was no obvious diurnal change in VOCs and no signif-icant difference between the different layers.When the surface VOC concentration was less than 10 ppbv,the concentrations,components,and sources of VOCs were evenly distributed vertically,and the main sources of VOCs at different heights were vehicle exhaust and background.When the surface VOC concentration exceeded 10 ppbv,the VOC concentration gradually decreased with height.The proportion of alkanes in surface VOCs in-creased,and the source was mainly vehicle exhaust.This study confirmed that VOCs are vertically homogeneous in the background of the Tibetan Plateau,emphasizing the importance of vehicle emissions as a potential source of VOCs.

Momentum distributions of symmetric(H_(2)^(+))and asymmetric(HeH^(2+))molecular ions in a circularly polarized laser field under different ionization mechanisms

By numerically solving the two-dimensional(2D)time-dependent Schrödinger equation(TDSE),we present photoelectron momentum distributions(PMDs)and photoelectron angular distributions(PADs)of symmetric(H_(2)^(+))and asymmetric(HeH^(2+))molecular ions in circularly polarized(CP)laser pulses.By adjusting the laser wavelength,two circumstances of resonance excitation and direct ionization were considered.The ionization mechanism of the resonance excitation was mainly investigated.The results show that the PMDs of H_(2)^(+)and HeH^(2+)in the y-direction gradually increase with increasing intensity,and the number of PMDs lobes is in good agreement with the results predicted by the ultrafast ionization model.In the resonance excitation scenario,the PMDs of are dominated by two-photon ionization,whereas the PMDs of HeH_(2)^(+)are dominated by three-photon ionization.Furthermore,the PMDs of HeH^(2+)are stronger in the resonance excitation scenario than those of H_(2)^(+),which can be explained by the time-dependent population of electrons.In addition,the molecular structure is clearly imprinted onto the PMDs.

Photoelectron momentum distributions of triatomic CO_(2)molecules by circularly polarized attosecond pulses

Molecular-frame photoelectron momentum distributions(MF-PMDs)have been studied for imaging molecular structures.We investigate the MF-PMDs of CO_(2)molecules exposed to circularly polarized(CP)attosecond laser pulses bysolving the time-dependent Schrodinger equations based on the single-active-electron approximation frames.Results showthat high-frequency photons lead to photoelectron diffraction patterns,indicating molecular orbitals.These diffractionpatterns can be illustrated by the ultrafast photoionization models.However,for the driving pulses with 30 nm,a deviationbetween MF-PMDs and theoretically predicted results of the ultrafast photoionization models is produced because theCoulomb effect strongly influences the molecular photoionization.Meanwhile,the MF-PMDs rotate in the same directionas the helicity of driving laser pulses.Our results also demonstrate that the MF-PMDs in a CP laser pulse are the superpositionof those in the parallel and perpendicular linearly polarized cases.The simulations efficiently visualize molecularorbital geometries and structures by ultrafast photoelectron imaging.Furthermore,we determine the contribution of HOMOand HOMO-1 orbitals to ionization by varying the relative phase and the ratio of these two orbitals.

Optical Modeling of Sea Salt Aerosols Using in situ Measured Size Distributions and the Impact of Larger Size Particles

Sea salt aerosols play a critical role in regulating the global climate through their interactions with solar radiation.The size distribution of these particles is crucial in determining their bulk optical properties.In this study,we analyzed in situ measured size distributions of sea salt aerosols from four field campaigns and used multi-mode lognormal size distributions to fit the data.We employed super-spheroids and coated super-spheroids to account for the particles’non-sphericity,inhomogeneity,and hysteresis effect during the deliquescence and crystallization processes.To compute the singlescattering properties of sea salt aerosols,we used the state-of-the-art invariant imbedding T-matrix method,which allows us to obtain accurate optical properties for sea salt aerosols with a maximum volume-equivalent diameter of 12μm at a wavelength of 532 nm.Our results demonstrated that the particle models developed in this study were successful in replicating both the measured depolarization and lidar ratios at various relative humidity(RH)levels.Importantly,we observed that large-size particles with diameters larger than 4μm had a substantial impact on the optical properties of sea salt aerosols,which has not been accounted for in previous studies.Specifically,excluding particles with diameters larger than 4μm led to underestimating the scattering and backscattering coefficients by 27%−38%and 43%−60%,respectively,for the ACE-Asia field campaign.Additionally,the depolarization ratios were underestimated by 0.15 within the 50%−70%RH range.These findings emphasize the necessity of considering large particle sizes for optical modeling of sea salt aerosols.

Citation distributions and research evaluations:The impossibility of formulating a universal indicator

Purpose:To analyze the diversity of citation distributions to publications in different research topics to investigate the accuracy of size-independent,rank-based indicators.The top percentile-based indicators are the most common indicators of this type,and the evaluations of Japan are the most evident misjudgments.Design/methodology/approach:The distributions of citations to publications from countries and journals in several research topics were analyzed along with the corresponding global publications using histograms with logarithmic binning,double rank plots,and normal probability plots of log-transformed numbers of citations.Findings:Size-independent,top percentile-based indicators are accurate when the global ranks of local publications fit a power law,but deviations in the least cited papers are frequent in countries and occur in all journals with high impact factors.In these cases,a single indicator is misleading.Comparisons of the proportions of uncited papers are the best way to predict these deviations.Research limitations:This study is fundamentally analytical,and its results describe mathematical facts that are self-evident.Practical implications:Respectable institutions,such as the OECD,the European Commission,and the U.S.National Science Board,produce research country rankings and individual evaluations using size-independent percentile indicators that are misleading in many countries.These misleading evaluations should be discontinued because they can cause confusion among research policymakers and lead to incorrect research policies.Originality/value:Studies linking the lower tail of citation distribution,including uncited papers,to percentile research indicators have not been performed previously.The present results demonstrate that studies of this type are necessary to find reliable procedures for research assessments.

Remaining Useful Life for Heavy-Duty Railway Cast Steel Knuckles Based on Crack Growth Behavior with Hypothetical Distributions

The current research on the integrity of critical structures of rail vehicles mainly focuses on the design stage,which needs an effective method for assessing the service state.This paper proposes a framework for predicting the remaining useful life(RUL)of in-service structures with and without visible cracks.The hypothetical distribution and delay time models were used to apply the equivalent crack growth life data of heavy-duty railway cast steel knuckles,which revealed the evolution characteristics of the crack length and life scores of the knuckle under different fracture failure modes.The results indicate that the method effectively predicts the RUL of service knuckles in different failure modes based on the cumulative failure probability curves for different locations and surface crack lengths.This study proposes an RUL prediction framework that supports the dynamic overhaul and state maintenance of knuckle fatigue cracks.

Spatiotemporal Distributions of Bacterioplankton Communities in the Qiantang River(Hangzhou Section),China

The spatial and temporal distribution of bacterioplankton communities plays a vital role in understanding the ecological dynamics and health of aquatic ecosystems.In this study,we conducted a comprehensive investigation of the bacterioplankton communities in the Qiantang River(Hangzhou section).Water samples were collected quarterly from seven sites over a one-year period.Physical and chemical parameters,including dissolved oxygen(DO),water temperature(WT),chemical oxygen demand(COD),nitrite(NO_(2)^(-)),active phosphate(PO_(4)^(3-))and other indices were determined.In this study,theαdiversity,βdiversity and abundance differences of bacterial communities were investigated using 16S rRNA high-throughput sequencing analysis.The spatial and temporal distribution characteristics and main driving factors of the bacterioplankton community structure and diversity were discussed.The results showed that a total of 57 phyla were detected in the bacterioplankton community,among which Proteobacteria and Actinomycetes were the two dominant groups with the highest relative abundance.The results of PCoA based on Bray-Curtis distance showed that the sampling season had a slightly greater effect on the changes in bacterioplankton community structure in the Qiantang River.Mantel and partial Mantel test showed that environmental variables(Mantel r=0.6739,P<0.0001;partial Mantel r=0.507,P=0.0001)were more important than geographical distance(Mantel r=0.5322,P<0.001;partial Mantel r=0.1563,P=0.001).The distance attenuation model showed that there was significant distance attenuation in all four seasons,and the maximum limit of bacterial community diffusion was found in spring.RDA analysis showed that nine environmental factors,including COD,WT and DO,significantly affected community distribution(P<0.05).This study provides valuable insights into the spatial and temporal distribution characteristics of bacterioplankton communities,shedding light on their ecological roles in the Qiantang River.The information obtained can guide future research on the interactions between bacterioplankton and their environment,enabling the development of effective conservation strategies and sustainable management practices for aquatic ecosystems.

Prevalence and Demographic Distributions of Pre-Eclampsia among Pregnant Women at Ho Teaching Hospital

Background: In Sub-Saharan Africa, pre-eclampsia remains a major health problem contributing to high rates of maternal mortality. Despite this condition having adverse effects on maternal and child health, its prevalence and associated risk factors are still significant, especially in developing countries including Ghana. This study aimed to assess the prevalence and demographic distributions associated with pre-eclampsia among pregnant women at the Ho Teaching Hospital. Methods: A facility-based retrospective study was conducted by reviewing available data or hospital records of pregnant mothers admitted to the labor and maternity wards from January 2018 to December 2020. All pregnant women who were diagnosed with pre-eclampsia within this period were included in the study. The data were collected using a structured checklist. Results: 5609 data on pregnant women from 2018 to 2020 were recorded. Out of the 5609 data recorded, 314 pre-eclampsia cases were recorded giving an overall prevalence of 5.6%. The yearly prevalence for 2018, 2019, and 2020 were 4.6%, 5.6%, and 6.6%, respectively. The most recorded pre-eclampsia cases were seen among women within the age group of 18 - 24 years. The data showed that 112 (35.7%) of the pregnant women who had pre-eclampsia were nulliparous. Pre-eclampsia-associated maternal and fetal complications were;preterm delivery 221 (70.4%), intrauterine fetal death 62 (19.7%), eclampsia 9 (2.9%), HELLP syndrome 5 (1.6%) and maternal death 17 (5.4%). Associated factors of pre-eclampsia were parity, level of education, and occupation (p ≤ 0.05). Conclusion: The findings of this study showed a rising trend in the incidence of pre-eclampsia over the years at the Ho Teaching Hospital. Parity, level of education, and occupation were found to be associated with developing pre-eclampsia.

Using Pearson’s System of Curves to Approximate the Distributions of the Difference between Two Correlated Estimates of Signal-to-Noise Ratios: The Cases of Bivariate Normal and Bivariate Lognormal Distributions

Background: The signal-to-noise ratio (SNR) is recognized as an index of measurements reproducibility. We derive the maximum likelihood estimators of SNR and discuss confidence interval construction on the difference between two correlated SNRs when the readings are from bivariate normal and bivariate lognormal distribution. We use the Pearsons system of curves to approximate the difference between the two estimates and use the bootstrap methods to validate the approximate distributions of the statistic of interest. Methods: The paper uses the delta method to find the first four central moments, and hence the skewness and kurtosis which are important in the determination of the parameters of the Pearsons distribution. Results: The approach is illustrated in two examples;one from veterinary microbiology and food safety data and the other on data from clinical medicine. We derived the four central moments of the target statistics, together with the bootstrap method to evaluate the parameters of Pearsons distribution. The fitted Pearsons curves of Types I and II were recommended based on the available data. The R-codes are also provided to be readily used by the readers.

Bivariate Analysis of Pollutants Monthly Maxima in Mexico City Using Extreme Value Distributions and Copula

In the present work, we are interested in studying the joint distributions of pairs of the monthly maxima of the pollutants used by the environmental authorities in Mexico City to classify the air quality in the metropolitan area. In order to obtain the joint distributions a copula will be considered. Since we are analyzing the monthly maxima, the extreme value distributions of Weibull and Fréchet are taken into account. Using these two distributions as marginal distributions in the copula a Bayesian inference was made in order to estimate the parameters of both distributions and also the association parameters appearing in the copula model. The pollutants taken into account are ozone, nitrogen dioxide, sulphur dioxide, carbon monoxide, and particulate matter with diameters smaller than 10 and 2.5 microns obtained from the Mexico City monitoring network. The estimation was performed by taking samples of the parameters generated through a Markov chain Monte Carlo algorithm implemented using the software OpenBugs. Once the algorithm is implemented it is applied to the pairs of pollutants where one of the coordinates of the pair is ozone and the other varies on the set of the remaining pollutants. Depending on the pollutant and the region where they were collected, different results were obtained. Hence, in some cases we have that the best model is that where we have a Fréchet distribution as the marginal distribution for the measurements of both pollutants and in others the most suitable model is the one assuming a Fréchet for ozone and a Weibull for the other pollutant. Results show that, in the present case, the estimated association parameter is a good representation to the correlation parameters between the pair of pollutants analyzed. Additionally, it is a straightforward task to obtain these correlation parameters from the corresponding association parameters.

白鲜不同生育时期营养元素积累规律及分配特征

以3年生白鲜(Dictamnus dasycarpus)为研究对象,通过测定白鲜不同生育时期根、茎、叶的干质量及营养元素含量,分析白鲜不同生育时期营养元素积累规律及分配特征,为白鲜科学精准施肥提供理论依据。结果表明:白鲜在生长过程中,不同营养元素的积累量由大到小的顺序为氮(N)、钙(Ca)、磷(P)、钾(K)、镁(Mg)、铁(Fe)、锰(Mn)、锌(Zn)、铜(Cu);在生长初期,N、P、K质量分数相对较高,植物对N、P、K元素的需求较大;出苗期至花蕾期,白鲜根中N、P、K的积累量分配比例明显降低,茎叶中积累量分配比例明显增加;从果前期开始,白鲜茎叶中Ca、Mg质量分数和积累量显著增加,在茎叶中分配比例相对较高;果前期和果中期茎叶中Fe、Mn质量分数显著增加,Fe、Mn元素积累量在果中期相对较高,茎叶中分配比例有所增加;根中Zn质量分数从果前期至果中期显著增加,整株积累量显著增大,果中期在根中分配比例达到最大,白鲜茎叶中Cu、Zn质量分数在花蕾期相对较高,在茎叶中的分配比例达到最大。因此,白鲜出苗期至花蕾期需要补充大量元素(N、P、K)及微量元素(Cu、Zn),果前期至果熟期需要补充中量元素(Ca、Mg)和微量元素(Fe、Mn、Zn)。

新疆冬小麦种质资源粒重基因的分布与育种适用性分析

小麦粒重是重要的产量构成因素之一,也是受遗传因素影响的数量性状。为了解粒重基因在新疆小麦的分布及相关分子标记在育种上的适用性,以253份新疆冬小麦品种为试验材料,利用KASP(竞争性等位基因特异性PCR)标记进行基因型检测,并与2个年份的株高、穗长、穗粒数、千粒重、粒长、粒宽等育种选择性状进行关联分析。结果表明,优异等位基因TaSus1-7A-Hap1、TaCwi-A1b、TaTGW-7Aa、TaGS5-A1b、TaGS2-A1b、TaGS-D1a、TaSus2-2B-HapH、TaTGW6-A1a、TaGW2-6B-Hap3和TaSus2-2A-HapA在参试材料的分布频率分别为100%、100%、84.98%、56.92%、51.78%、39.13%、33.20%、11.07%、3.16%和1.58%;14对等位基因在参试材料中共出现118种组合;标记GS5-2334-SNP、TaGS2-A1-239IND2、TGW7-986-SNP和GW2-6B-721SNP可应用于小麦粒重的辅助选择;被检测标记的连锁基因均与1个或1个以上育种性状显著相关;GS5-2334-SNP连锁基因TaGS5-A1对粒宽的效应达36.65%,对千粒重效应次之(27.76%),GS5-2334-SNP连锁基因TaGS5-A1对株高和穗粒重、GW2-6B-721SNP连锁基因TaGW2-6B和TGW7-986-SNP连锁基因TaTGW7对粒长、Sus2-2A-20SNP连锁基因TaSus2-2A对穗粒重、千粒重和粒宽的效应均达到10%以上。本研究结果可为分子标记辅助育种奠定基础。

质子入射In靶激发L系特征X射线的角分布研究

本论文实验测量并分析了发射角以10°为间隔,125°-155°范围内,入射能量为250 keV的质子束激发In靶产生的特征L系X射线谱,根据实验测得能谱结果,综合考虑探测器的探测效率后,计算了不同探测角度下特征X射线的相对强度比L_(ι)/L_(γ1);由相对强度比L_(ι)/L_(γ1)与二阶勒让德函数P_(2)(cosθ)之间的函数关系,发现特征X射线Lι在被测能量下呈各向异性发射,推得Lι特征X射线的各向异性参数β为-0.179±0.011,进而得到In靶L_(3)亚壳层的定向度A_(20)为-0.422±0.025,实验结果与理论预测一致.根据PWBA(Plane wave born approximation)模型和ECPSSR(Energy-loss coulomb-repulsion perturbed-stationary-state relativistic)模型,计算了250 keV质子入射下,In靶L亚壳层电离截面σ及Coster-Kronig跃迁矫正因子κ,在根据各向异性参数计算L_(3)亚壳层定向度的过程中考虑了Coster-Kronig跃迁的作用.分析认为本实验碰撞速度下,通过电子转移方式产生空穴的截面比直接电离小的多,所以没有对L_(3)亚壳层定向度进行电子转移因素的修正.

抗冻蛋白对冷冻猪肉品质的影响

研究抗冻蛋白(antifreeze proteins,AFP)对猪肉冷冻过程中品质变化的影响。以商业抗冻剂海藻糖(4 mg/m L)的抗冻效果为参考,以未添加AFP组为对照组,研究不同添加量(0.05、0.1、0.2、0.3 mg/mL)AFP对冷冻猪肉品质、肌原纤维蛋白理化性质、微观结构和水分分布的影响。结果表明:AFP可以减少冷冻猪肉的水分损失,有利于维持猪肉色泽和微观结构;在冷冻贮藏过程中,0.3 mg/mL AFP组猪肉的蒸煮损失、解冻损失及色泽的保护效果最好,其次是0.2 mg/mL AFP组和4 mg/mL海藻糖组;0.2、0.3 mg/mL AFP组剪切力和肌原纤维蛋白总巯基含量显著高于未添加AFP组(P<0.05);核磁共振成像验证了AFP的渗入降低了猪肉中结合水和不易流动水损失;扫描电子显微镜结果显示,0.2 mg/mL AFP使猪肉肌纤维排列整齐,更加紧凑和致密。总体而言,添加AFP对改善冷冻猪肉品质有积极作用,是一种潜在的安全、高效冷冻保护方法。

New Principle for Grounding Fault Feeder Detection in MV Distributions with Neutral Ineffectively Earthed

A new principle for grounding fault feeder detection based on negative sequence current variation and energy dissipated in the fault point is presented. It has high precision in both isolated systems and resonance earthed systems, even in full compensated systems. And it can be installed at the local control unit of feeder in distribution automation systems, such as field terminal unit (FTU). This principle is verified by EMTP simulator and experimentation.

Dissolved Inorganic Arsenic in the Yellow Sea and the East China Sea—Distributions and Seasonal Variations

The distributions and seasonal variations of total dissolved inorganic arsenic （TDIAs, [TDIAs] = [As^5＋]＋[As^3＋]） and arsenite （As3.） in the Yellow Sea and East China Sea are presented hero based on the observations of 9 cruises carried out in 2000 - 2003. The study area covers a broad range of hydrographic and chemical properties. The emphasis is put on a southeast transect from Changjiang Estuary to the Ryukyu Islands （i.e. PN section） in the East China Sea to discuss the impact of terrestdal input on the marginal seas of China. Arsenic species （TDlAs and arsenite） are determined by selective hydride generation - atomic fluorescence spectrometry （HG-AFS）. TDIAs concentrations were high in the coastal area of Changjiang Estuary and decreased slightly towards the shelf region. High concentratiOns of TDIAs were also existed in the near bottom layer of shelf edge of the East China Sea which indicated another source of arsenic from the incursion of Kuroshio Waters. The seasonal variations of TDIAs in the study area depend on the hydrographic stages of Changjiang and the incursion intensity of Kuroshio Waters. Arsenite showed opposite distributions with TDIAs, with higher concentrations appeared at the surface layer of shelf region, which was positive correlated with the chlorophyll a. Biological conversion of arsenate into arsenite was hypothesized for the observed distribution pattern and its seasonal variations. The stoichoimetric ratios of As to P were estimated to be about 2×10^3 at PN Section in summer. The concentrations of dissolved arsenic in the Yellow Sea and East China Sea were comparable with other areas in the world.

环境因子对渤海强壮滨箭虫四季种群结构的影响

为深入探究环境因子与渤海强壮滨箭虫四季种群结构动态的关系,并进一步丰富近年来渤海海域浮游动物的相关研究,本研究于2018年4月—2019年12月在渤海海区开展4个航次的海洋综合调查工作,对渤海强壮滨箭虫的时空分布以及生长繁殖状况进行了研究,并讨论了温度、盐度、深度以及饵料等环境因子对其种群结构产生的影响。研究结果显示:盐度与强壮滨箭虫的时空分布具有显著的相关性,在28.5~32.7的范围内,盐度的升高对强壮滨箭虫种群增长有抑制作用;温度通过影响强壮滨箭虫的摄食、代谢来影响其季节上的变化;桡足类作为强壮滨箭虫的主要饵料,也是影响强壮滨箭虫生长繁殖的重要因素。

基于概率的震级完备度方法评估云南地震台网的监测能力

为了科学评估云南地震台网的监测能力,分析云南地区的地震监测能力时空分布特征,采用基于概率的震级完备度(PMC)方法,利用2009-2023年云南地震台网地震目录、震相和台站信息等数据,计算了云南地震台网在云南地区的平均地震监测能力和在不同深度的监测能力,得到滇中、滇西局部地区的基于概率的完备性震级M_(P)=1.5,云南全境基本都能监测到2.5级地震。评估了研究时段内云南地震台网台站监测能力的演变,发现部分台站的监测能力持续下降。但自2018年增加20个台站后,云南2.0及2.5级地震的监测范围有一定的扩大,但微震监测能力提升不明显,可能是因为2018年以来云南一直处于小震弱活动状态。最后,对应用PMC方法规划提升台网监测能力进行了展望。

基于绕组首饼温度及温度梯度的变压器热点模型

变压器热点温度是衡量变压器负载潜力及运行安全性的重要指标,是变压器状态监测以及预测的重点。绕组底部首饼直接与散热片回流的冷油接触,周围油温与冷油近似相等,可以较为准确地分析其散热。该文从变压器传热原理出发,提出一种新的热点温度计算模型。首先,基于理论推导建立绕组首饼温度的控制方程,并使用热电类比方法建立可用于实际运行的绕组首饼局部热路模型。通过对一台内置传感光纤的110 kV油浸式变压器进行11级不同负载共21 h温升试验,获得不同负载率下绕组温度变化情况,并提出基于绕组首饼温度及绕组温度梯度的热点温度模型。基于局部热路模型,使用负载率及散热片进出口油温作为输入变量,成功预测绕组首饼温度。随后,建立绕组整体温度梯度的指数、差分方程模型,并基于提出的热点计算模型对连续变负载试验的结果进行预测。结果表明,模型预测均方根误差为4.02 K,相较传统模型,最大误差降低21%,验证所提计算模型的有效性。

Efficient and Stable Perovskite Solar Cells and Modules Enabled by Tailoring Additive Distribution According to the Film Growth Dynamics

Gas quenching and vacuum quenching process are widely applied to accelerate solvent volatilization to induce nucleation of perovskites in blade-coating method.In this work,we found these two pre-crystallization processes lead to different order of crystallization dynamics within the perovskite thin film,resulting in the differences of additive distribution.We then tailor-designed an additive molecule named 1,3-bis(4-methoxyphenyl)thiourea to obtain films with fewer defects and holes at the buried interface,and prepared perovskite solar cells with a certified efficiency of 23.75%.Furthermore,this work also demonstrates an efficiency of 20.18%for the large-area perovskite solar module(PSM)with an aperture area of 60.84 cm^(2).The PSM possesses remarkable continuous operation stability for maximum power point tracking of T_(90)>1000 h in ambient air.