Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments

Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China.Understanding the composition,distribution,and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion.In this study,based on laboratory rainfall simulation experiments,we analyzed rainfall-induced erosion processes on sand-covered loess slopes(SS)with different sand cover patterns(including length and thickness)and uncovered loess slopes(LS)to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion.The grain-size curves of eroded sediments were fitted using the Weibull function.Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS.The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed.The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS.Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes.The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage.Sand cover on loess slopes aggravates loess erosion,not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess,compared with the loess slopes without sand cover.The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount.Furthermore,given the same sand cover pattern,a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion.This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.     

Expression and mechanisms of hsa_circ_087631 in patients with primary biliary cholangitis

AIM To explore the expression and mechanisms of circular RNA hsa_circ_087631 in the patients with primary biliary cholangitis （PBC）. METHODS RT-qPCR was used to detect the expression of hsa_circ_087631 in PBC patients and healthy controls. Hsa-miR-346-overexpressing lentiviral vector pLenti-EF1a-EGFP-F2A-Puro-CMV-MCS was constructed and transfected into human acute T cell leukemia Jurkat cells， and then the expression levels of hsa_circ_087631， Bcl-6 mRNA and interleukin-21 （IL-21） mRNA were detected by RT-qPCR. Dual-luciferase reporter assay was performed to identify the interactions between hsa_circ_087631 and hsa-miR-346. RESULTS The expression of hsa_circ_087631 in the PBC patients was significantly increased compared with the healthy subjects. Hsa-miR-346-overexpressing lentiviral vector pLenti-EF1a-EGFP-F2A-Puro-CMV-MCS was successfully constructed. The expression of hsa-miR-346 was significantly increased after the hsa-miR-346-overexpressing lentiviral vector was transfected into the Jurkat cells， while the expression levels of hsa_circ_0087631， Bcl-6 mRNA and IL-21 mRNA were significantly decreased. After wild-type or mutant hsa_circ_087631 vector and hsa-miR-346 mimics were transfected into 293T cells， the results of dual-luciferase reporter assay showed that hsa-miR-346 significantly decreased the luciferase activity of wild-type hsa_circ_087631 （P<0.01）， but the regulation did not change significantly after mutation of the predicted binding site. CONCLUSION Peripheral blood hsa_circ_087631 level is elevated in the PBC patients. The hsa_circ_087631/hsa-miR-346/Bcl-6 signaling may take effect in human T cells. Hsa-miR-346 significantly reduces the expression of hsa_circ_087631， but it may not be regulated by predicted binding sites.     

重型轮式拖拉机燃油箱设计要点

重型轮式拖拉机通常采用滚塑燃油箱,能充分利用拖拉机侧方的空间,增大燃油箱容积,满足此种拖拉机农忙时较长时间工作的要求。燃油箱外形必须根据拖拉机整机结构和燃油箱周边零件外形进行设计,外形设计还需要考虑燃油箱自身强度和热膨胀的因素。加油口、通气孔、联通口和转角设计等设计细节也决定着燃油箱的设计质量。     

基于GRA-TOPSIS耦合的草莓品质综合评价

研究不同水肥滴灌条件对草莓品质的综合影响,为草莓高品质生产提供水肥管理依据.以灌水量(X1)和施肥量(X2)为试验因子,依据蒸腾量(ETc)设置4个灌水水平(W1:100％ETc、W2:85％ETc、W3:70％ETc、W4:55％ETc);依据目标产量(F0)设置3个施肥水平(F1:120％F0、F2:100％F0、F3:80％F0),完全组合共12个处理.测定草莓可溶性总糖、可溶性蛋白、维生素C、可溶性固形物、糖酸比、游离氨基酸、还原性糖、硝酸盐8个品质指标,解析水肥耦合对各品质指标的调控效应.各品质指标对水肥因素响应不一致,基于博弈论组合赋权中,单一指标权重最大是可溶性蛋白为0.1689,维生素C次之为0.1551,硝酸盐最小为0.0918;基于GRA-TOPSIS建立草莓品质综合评价,解析草莓综合品质对水肥因素响应模型,可知,水肥交互作用显著,且施肥效应强于灌水.当灌水量控制在2 003～2566m3.hm-2,施肥量控制在1 878～2 195 kg.hm-2时,草莓综合品质最佳.     

中国部分重点地区牛结核病的γ-干扰素试验流行病学调查

为调查部分省份牛结核病(bTB)的流行情况,我们在山东等14个省份34个历史上疫情较重的县共129个场户采集牛全血2 201份,采用CO2培养箱或蜡罐方法进行bTBγ-干扰素检测,结果显示样品的个体阳性率为6.4%,群阳性率为42.6%。饲养模式对bTB感染影响的统计显示较大规模场的个体阳性率(6.9%)和群阳性率(60%)均高于散养户(分别为5.7%和35.6%)。而牦牛样品的检测结果均为阴性。5个牛群的禽型PPD阳性统计结果显示牛型PPD阳性率越高,则禽型PPD阳性牛在牛型PPD阳性牛中的所占比率越低。在所有阳性牛群中,阳性率≥10%的牛群所占比例高达81.8%(45/55),bTB感染呈现出一个"群发性"的特征。     

硒对母猪氧化应激及其后代抗氧化能力的营养调控研究

硒作为的重要微量元素之一,可以通过胎盘和乳组织进行转移。仔猪可以从乳汁中获取硒源,提高硒含量,进而提高仔猪的初生重。同时,硒也能够调节母猪妊娠期间代谢速度,控制妊娠期自由基产生,进而提高胎盘输送营养功能。文章从母猪氧化应激体系角度来解析硒对母猪妊娠期氧化应激的调控机制、硒对哺乳母猪生产性能的调控作用。     

自动施肥系统开发与性能测试

目的 开发一种适应于以固态水溶肥为原料的自动施肥系统,测试分析自动施肥系统性能。方法 主控机采用ARM9电路控制模块可实现对轮灌编组、预搅拌时长、施肥开始与结束时间、施肥持续时长、施肥量等参数的设置;选择以蠕动泵为注肥装置,通过变频器控制注肥泵电机功率的方式控制注肥速率,控制施肥量。对装置核心部件搅拌器额定功率、计量方式、溶肥搅拌参数、排肥速度及固液相比例等主要参数等进行设计与测试。结果 电感脉冲计量方式标准误差最大值1.26%,误差小、性价比好,确定其为本装置采用的计量方式;搅拌器以1.5 Kw额定功率、38 r/min转速搅拌、肥液浓度在1.1~1.3 g/mL、预搅拌时间30 min时,罐内各液位输出肥液浓度值差异不显著(P< 0.05),达到对肥料浓度均匀性的设计要求。结论 将施肥开始前的预搅拌时间设为30 min、搅拌转速设为38 r/min、肥液浓度不高于1.3 g/mL,输出肥液浓度有较好的均匀性,实现精准施肥。     

奶山羊CIDEa基因的克隆、序列分析与组织表达

为获得奶山羊CIDEa基因序列并检测其在乳腺组织中的表达,采用RT-PCR技术从奶山羊乳腺组织扩增CIDEa基因序列,利用生物信息学软件对其进行预测分析,并采用荧光定量PCR检测CIDEa在干奶期和不同泌乳时期乳腺组织中的表达。结果表明:通过克隆测序得到奶山羊CIDEa基因CDS区660 bp,编码219个氨基酸,与GenBank公布的绵羊、牛、人和猪的核苷酸序列同源性分别为99%、96%、85%、85%。奶山羊CIDEa蛋白属于碱性、不稳定亲水蛋白,不存在跨膜结构和信号肽;蛋白主要定位在细胞质、线粒体和细胞核。CIDEa蛋白结构主要由α螺旋、β折叠和不规则卷曲组成。奶山羊CIDEa在泌乳前期、盛期和中期乳腺组织中表达量均显著高于干奶期(P<0.05)。说明CIDEa可能参与奶山羊乳腺的泌乳过程,为进一步研究其在奶山羊乳腺组织中的功能及对乳品质的调控作用奠定基础。