基于改进VMD的离心泵空化声发射信号特征提取

针对变分模态分解算法中分解层数和惩罚因子不易确定的问题,提出一种改进变分模态分解(improved variational mode decomposition,IVMD)算法,并将其应用于离心泵空化声发射信号特征提取.应用IVMD算法时,首先根据包络熵差异系数确定变分模态分解的分解层数;然后采用人工蜂群算法优化得出惩罚因子,并将其作为变分模态分解的最佳输入参数.利用IVMD算法对仿真信号进行分析,并与集合经验模态分解结果进行比较.以60%额定流量下采集到的离心泵进口处的声发射信号为例进行IVMD计算,分析携带原信号大量信息的信号分量的频域特征及其绝对能量随离心泵空化状态变化的关系.结果表明:IVMD算法能够择优确定分解层数和惩罚因子,实现非平稳信号的自适应分解.反映离心泵空化状态的声发射信号特征频率集中在50,100 kHz及其附近.随着离心泵空化从无到有、从弱到强的变化,这2个特征频率范围信号分量绝对能量值呈“基本保持不变-减小-增大”的变化规律.     

人工模拟增雨对油蒿种子形态性状和比叶面积的影响

【目的】研究油蒿的种子大小和比叶面积对不同增雨处理的响应,探明两者之间的关系,以期揭示油蒿植物功能性状对降水量变化的响应机制和演变趋势。【方法】根据内蒙古磴口县多年平均降水量,在植物生长季5—9月设计4个增雨梯度(25%,50%,75%和100%),对天然油蒿灌丛进行增雨试验,利用Winseedle种子和针叶图象分析软件系统,对比了油蒿种子表型形态特征和比叶面积对降水增多的响应,同时通过相关分析研究了油蒿种子大小与比叶面积的关系。【结果】不同增雨量对油蒿种子长度、宽度、体积、表面积及千粒重均有显著影响,在100%增雨处理下种子各性状指标达到最小值,其中种子宽度、体积、表面积与增雨量呈极显著负相关(P<0.01)。种子长度和千粒重与增雨量呈显著负相关(P<0.05),种子长宽比与增雨量的相关性不显著(P>0.05)。不同增雨量对油蒿比叶面积的影响差异性显著(P<0.05),且随着雨量的增加,比叶面积不断增大。种子大小与比叶面积呈负相关关系,但均未达到显著水平(P>0.05)。【结论】降水增加后油蒿种子会先增加后减小来适应环境变化,通过油蒿种子、比叶面积两大植物功能性状组合对增雨量处理响应的研究体现了荒漠植物应对未来气候变化的生存策略和适应机制。     

Comparative analysis of different methods revealing the involvement of proteins during ageing of rice seeds

Seed longevity is a very important characteristic controlling seed quality. However, the mechanism underlying this characteristic is poorly understood. In this study, 'FH7185', a storable rice variety, the germination rate of which was 66.63%, much higher than the control after artificial ageing under relative humidity 88% and 42°C for 21 days. Different methods were applied to reveal the involvement of proteins during ageing of rice seeds. In total, 35 differential proteins were identified from 2D‐PAGE, and 3,719 proteins from iTRAQ analysis. A comparison of these two methods showed that not all protein types could be detected on the 2D‐PAGE gels, and the dynamic range was somewhat limited. So the comprehensive proteome map from the iTRAQ analysis was used to identify the quantitatively regulated proteins that played roles in seed longevity, and found that the most marked change was the increased abundance of many metabolic enzymes, especially the ones involved in α‐linolenic acid metabolism in the embryos during ageing. OsLOX2 and OsLOX3 had a negative effect on seed longevity, which were lower in FH7185 than the control. The dehydrogenase (LOC_Os07g44430) which played a major catalytic role in lipid peroxidation, also changed significantly during ageing. Therefore, OsLOX2, OsLOX3 and Loc_OS 07G44430 may be involved in the regulation of seed longevity with a synergistic effect.     

Development of colchicine‐induced tetraploid St. Augustinegrass (Stenotaphrum secundatum) lines

St. Augustinegrass is well suited for lawns and commercial landscapes. While many genotypes are cross‐fertile, all cultivars are propagated vegetatively in sod production. To ensure varietal purity, development of sterile triploid hybrids by crossing tetraploid and diploid genotypes has been successfully used in other warm‐season turfgrasses. Applying this model in St. Augustinegrass would be beneficial to sod producers and turf managers who require purity for certification and uniformity for performance, respectively. This study was conducted to develop colchicine‐induced tetraploid lines of St. Augustinegrass. Seeds of cultivar ‘Raleigh’ were treated with four colchicine concentrations at four exposure times. A non‐treated control was included among the treatments. Seedlings that germinated were screened for genome size changes using flow cytometry. Line DSA 13005 and two progeny lines derived through selfing, DSA 16001 and DSA 16016, were corroborated as tetraploids (2n = 4x = 36) through chromosome counts. These lines will be used in future breeding efforts to attempt development of sterile triploid cultivars of St. Augustinegrass.     

Effect of Dimethyl sulfoxide (DMSO) and egg yolk on sperm motility,fertility and hatching rates of depik Rasbora tawarensis (Pisces: Cyprinidae) eggs after short‐term cryopreservation

Cryoprotectant is the crucial factor in the cryopreservation process. In general, there are two types of cryoprotectant, permeating and non‐permeating cryoprotectants. Dimethyl sulfoxide (DMSO) and egg yolk are common permeating and non‐permeating cryoprotectants respectively. Hence, the objective of the present study was to determine the best proportion of DMSO and egg yolk for the cryopreservation of Rasbora tawarensis sperm. A completely randomized experimental design was used in this study which involves two types of cryoprotectant and their combination at different concentrations, namely 5% DMSO, 5% egg yolk, 5% DMSO + 5% egg yolk and 2.5% DMSO + 2.5% egg yolk. Every treatment was conducted in three replicates. Combination of 5% DMSO + 5% egg yolk gave the best results cryoprotectant treatment had significant effects on sperm motility, fertilization and hatching rate of the R. tawarensis eggs (p < .05). It is concluded that the best proportion of cryoprotectants for sperm cryopreservation in this species is 5% DMSO + 5% egg yolk.     

基于不同人工鱼巢研究黄颡鱼的产卵偏好性

为探索黄颡鱼(Pelteobagrus fulvidraco)繁殖时期对人工鱼巢的偏好性, 2018年6—7月开展了不同水温条件下黄颡鱼对不同鱼巢颜色和材质产卵偏好性的对比实验。实验用产卵鱼巢为半球形棕榈空鱼巢(直径25 cm,深12 cm);同规格内部放置4～6枚碎石块的棕榈鱼巢和塑料鱼巢;折叠6层尼龙渔网(30cm×40cm)和棕榈片(30cm×40cm)鱼巢,于水泥池(290 cm×120 cm×100 cm)内开展两种温度区间条件下产卵偏好性实验。实验用黄颡鱼亲本雌雄比例为1:1,雌鱼体长(167.8±19.0)mm,体重(99.9±21.7)g;雄鱼体长(235.1±18.8)mm,体重(188.5±38.1)g。结果表明,在24～26℃水环境下,半球形棕色棕榈(无石子)鱼巢内个体平均附卵量为628.49粒/m2,个体单位面积平均附卵率为2.77%;28～32℃水环境下,半球形棕榈(无石子)个体平均附卵量为225.48粒/m2,个体单位面积平均附卵率为1.40%。结果分析发现, 24～26℃是黄颡鱼产卵的最适水温区间;黄颡鱼对棕色鱼巢产卵偏好显著(P0.05),而对灰色、粉色、黄色和绿色无明显偏好;黄颡鱼对半球形棕榈(无石子)鱼巢产卵偏好显著(P0.05),而对其他材质鱼巢的偏好性依次为:半球形棕榈(有石子)平铺棕榈片悬挂棕榈片半球形塑料水泥池。可见,黄颡鱼产卵的最佳偏好为24～26℃水环境下棕色半球形棕榈鱼巢。本研究结果对黄颡鱼的人工繁殖、产沉黏性卵鱼类产卵场的修复和资源增殖有重要的指导意义。     

长江口盐沼湿地鱼类群落优势种的时空生态位特征

为了解长江口盐沼湿地优势鱼类群落结构及其种间关系，采用插网调查，利用2019年5—10月的调查数据，基于生态位宽度和生态位重叠度指数对长江口崇明东滩（31°27''N，121°56''E）和九段沙盐沼湿地（31°10''N，121°57''E）鱼类群落的优势种生态位进行研究。研究结果表明，春、夏、秋3个季节共采获10个优势种，其中鮻（Liza haematocheila）、花鲈（Lateolabrax maculatus）和拉氏狼牙虾虎鱼（Odontamblyopus rubicundus）在3个季节中均为优势种。在10个优势种中，时间生态位宽度值变化范围为0.11~1.70，其中拉氏狼牙虾虎鱼时间生态位宽度值最大，小黄鱼（Larimichthys polyactis）值最小；空间生态位宽度值变化范围为0.57~1.53，其中棱鮻（Liza carinatus）空间生态位宽度值最大，小黄鱼值最小。长江口盐沼湿地鱼类优势种生态位宽度呈现显著的季节性变化趋势。长江口盐沼湿地鱼类优势种的时空生态位重叠值较高，其中具重叠意义的鱼种对（species pairs）高达73.33%，具有显著重叠意义的鱼种对高达48.89%。结论认为，长江口盐沼湿地鱼类优势种的时空分布具有相似性，存在明显的竞争关系。     

华木莲人工造林技术研究

主要对华木莲生长速度、施肥、不同坡位、初植造林打穴规格、除草方式、初植密度、适宜造林时间、适宜土壤pH值等人工造林技术进行探索研究。     

互花米草入侵对滨海湿地重金属的富集迁移效应

为探究互花米草（Spartina alterniflora）入侵对滨海湿地沉积物重金属的富集迁移效应,为滨海湿地生态保护与合理利用提供依据,在山东省日照市黄家塘湾滨海湿地选取不同互花米草入侵年限的斑块,以5 cm为间隔采集0～30 cm沉积物样品和互花米草样品,分析沉积物和互花米草不同部位中重金属元素Cu、Zn、Pb和Cd的含量,并采用地累积指数法、潜在生态风险评价法、生物富集系数及转运系数等方法进行评价。结果表明：湿地沉积物重金属Cu、Zn、Pb和Cd 的含量范围为5.94～31.94 mg(kg^-1,18.59～56.87 mg(kg^-1,4.76～30.36 mg(kg^-1,0.021～0.083 mg(kg^-1,整体低于研究区域重金属环境背景值;但Cu、Pb在0～15 cm内存在轻度污染;与光滩湿地相比,互花米草入侵湿地沉积物中重金属含量增加,且随互花米草入侵年限增加,沉积物重金属含量呈增加趋势,在上层（0～15 cm）表现尤为显著;互花米草不同部位对重金属的累积存在一定差异,大致表现根>叶>茎;不同重金属在根部的富集效应表现为Cd > Zn > Cu > Pb,互花米草对重金属转运效应为Pb > Zn > Cu > Cd。相关分析表明,沉积物中重金属的累积与互花米草入侵对湿地沉积物粒度组成、有机质含量及pH的改变密切相关。不同重金属在沉积物-植物体系的迁移转运差异则主要与互花米草各部位对重金属元素的吸收差异有关。