池塘放养密度对施氏鲟幼鱼生长、摄食和肌肉组分的影响

在水温为14 ～ 17℃条件下,将大规格施氏鲟Acipenser schrenckii幼鱼（225.69 g±32.28 g）随机放入9个四边形水泥池（池底面积为18.23 m2）中流水饲养,分别设置5.5、8.0、11.0 kg/m3 3个放养密度组,每组设3个平行,养殖试验共进行70 d,观察并研究放养密度对施氏鲟幼鱼生长、摄食和肌肉组分的影响.结果表明：施氏鲟幼鱼的终末体质量、特定生长率、日增重和摄食率等均随养殖密度的增大而显著降低（P＜0.05）,饲料系数随养殖密度的增大而显著升高（P＜0.05）,密度为8.0 kg/m3的组生长效率最高;肌肉中的粗蛋白质和粗脂肪含量随养殖密度的增大而显著降低（P＜0.05）,雨水分和灰分含量的变化不明显（P＞0.05）;试验期间,水体中的溶解氧浓度随养殖密度的增大显著降低（P＜0.05）,而氨氮和化学耗氧量浓度则随养殖密度的增大而显著升高（P＜0.05）.研究表明,8.0 kg/m3的放养密度更适合大规格施氏鲟幼鱼的养殖,过高的放养密度会对施氏鲟幼鱼生长及其肌肉品质产生不利影响.     

菊芋的功能及其在食品中的应用

菊芋是一种具有多种生理功能的天然绿色食品,极具开发价值。论述了菊芋的营养功能、生理功能、生态功能及其在食品中的应用。     

具有排气功能的毛管末端自动冲洗阀设计与结构优化

该研究创制一种具备自动排气功能（Auto-Exhaust function, AE）的毛管末端自动冲洗阀,以提高冲洗时长和冲洗水量。选取延时流道齿长和齿宽、上腔体容积和冲洗阀进口压力共4个因素,采用L18（37）正交试验设计18种规格的AE冲洗阀,并设置4种无排气装置（Non-Exhaust function, NE）的冲洗阀为对照,探究排气装置提升冲洗阀水力性能的作用机理和AE冲洗阀性能参数对试验因素的响应规律。结果表明,当进口压力为0.06～0.14 MPa时,AE冲洗阀的冲洗时长、冲洗水量和冲洗流速分别为18.2～67.7 s、3 904～12 367 mL和0.88～1.40 m/s。冲洗时长和水量与流道齿长、齿宽和上腔体容积均为正相关关系,与进口压力为负相关关系,冲洗流速只与进口压力有关,为正相关关系。流道齿长、齿宽和上腔体容积对冲洗时长和水量影响显著,进口压力对冲洗时长和流速影响显著（P<0.05）。AE冲洗阀能自动排出上腔体中的空气,增加蓄水容积,使其冲洗时长和水量分别比NE冲洗阀提高83.5%与75.4%以上。综合考虑延时流道抗堵塞性能、冲洗时长和水量等因素,推荐AE冲洗阀流道齿长、齿宽、上腔体容积和进口压力分别为1.2 mm、2.2 mm、19.1 mL和0.06 MPa,其冲洗时长和水量分别是NE冲洗阀的2.8和2.7倍,是进口冲洗阀的7.4和7.0倍,为67.7 s、12 194 mL。研究结果可为具有排气功能的毛管末端自动冲洗阀的研发提供依据。     

辽宁省生长季气候变化及其对春玉米产量的影响

为了明确气候变化对辽宁省春玉米产量的影响,基于1968—2017年气象站点数据,结合标准化降水蒸散指数(Standardized Precipitation Evapotranspiration Index,SPEI),运用M-K趋势分析、相关分析及回归分析等数理统计方法研究了辽宁省春玉米生长季各气候要素、干湿变化特征及其与春玉米产量的关系。结果表明:降水量除丹东呈增加趋势外,其它地区呈现减少趋势; 大部分地区温度呈现升高趋势,风速呈显著减弱趋势,相对湿度变化趋势不显著; 日照时数除辽阳、本溪呈不显著增加外,其他地区呈减少趋势。降水、最高温和平均温是影响辽宁省春玉米产量的重要因子,尤其是朝阳、葫芦岛、锦州、阜新和大连地区,春玉米对这些要素更敏感,与降水量正相关,与最高温、平均温负相关,未来降水量减少、温度升高将不利于这些地区春玉米生长。随着位置东移降水量逐渐以负效应为主,温度逐渐表现为正效应。除阜新、抚顺、本溪等部分地区呈现干旱化外,其他地区表现为不显著的湿润化趋势。朝阳、葫芦岛、阜新等地区春玉米产量对6月、7月的干湿变化较敏感,易受旱减产; 干旱化将使阜新春玉米生产形势变得严峻,朝阳、锦州、大连地区湿润化对春玉米生长有利; 沈阳、鞍山、辽阳和营口地区5—9月的干湿状况均对春玉米产量有影响,抚顺、本溪、铁岭等地区则易受6—8月的干湿状况影响,这些地区当前较适宜春玉米生长; 丹东地区易受涝减产,且湿润化趋势将会对该地区玉米生产造成不利影响。辽宁省不同气候要素及干湿变化对不同地区春玉米产量的影响效应有正有负,程度也各不相同,各地应因地制宜采取合理措施促进玉米丰产。     

玉米旅欧群体评价及利用潜势分析

通过向玉米辽旅群体中导入血缘相近、脱水速率快的9份欧美种质,构建成含有不同比例欧美种质的3份旅欧群体,能显著改善收获时含水量、出籽率、生育期、穗粗和穗行数等重要性状,且保持原始群体优良的产量一般配合力,显著提高出籽率、穗长和行粒数的一般配合力。杂种优势分析结果表明,旅欧群体所配制的组合有效提升出籽率、收获时含水量、生育期和其他穗部性状的杂种优势,与塘四平头类群的杂优模式存在极高的产量应用潜力,为改良本土种质资源适宜机械化收获和探索欧美种质新的杂优模式奠定基础。     

Characterization of black locust (Robinia pseudoacacia L.) heartwood extractives: identification of resveratrol and piceatannol

Robinia pseudoacacia L. heartwood is characterized by a very high natural durability. However, a significant difference was observed between the mature and juvenile heartwood, the latter presenting less durability against fungi decay, which could be attributed to lower extractive content. In order to elucidate this idea, extractives from mature and juvenile heartwoods of black locust trees were investigated. Results showed that extractive and phenolic contents were higher in mature than in juvenile heartwoods. The identification of phenolic compounds by UPLC–DAD–MS/MS revealed, for the first time, the presence of resveratrol and piceatannol. These two stilbenes as well as the flavonoid dihydrorobinetin were present at the highest level in mature heartwood, and as they are known antifungals, they could account for the great durability of mature heartwood. The stilbenes were detected in significant amounts particularly in mature heartwood where piceatannol reached a level tenfold higher than that reported for Japanese knotweed roots, the primary natural source of these stilbenes, whereas resveratrol level was comparable with reported values. As resveratrol and piceatannol receive increasing demand for nutraceutical, cosmetic and, possibly, pharmaceutical purposes, due to their beneficial health effects, this study underlines the use of R. pseudoacacia as a promising sustainable and economical source of resveratrol and piceatannol.     

Soil water affects transpiration response to rainfall and vapor pressure deficit in poplar plantation

Influences of environmental factors on transpiration are interactive. Sensitivities of transpiration responses to both evaporative demand and rainfall under contrasting soil water conditions constitute the physiological basis of the drought tolerance of trees. Such knowledge is practically significant for plantation management, especially for irrigation management. We therefore conducted a 6-year study on the transpiration of a poplar plantation in temperate China to elucidate the existence and pattern of the influence of the soil water over stand transpiration responses to (1) vapor pressure deficit (VPD), the major indicator of air dryness and (2) the rainfall, in terms of total amount and event size. The results showed that the response of plantation transpiration (E _c ) to VPD was conditioned by soil moisture. There was a significant difference in the frequency distribution of maximum sap flux under contrasting soil relative extractable water. E _c after rainfall of different sizes varied under similar VPD. The increasing occurrences of only large rainfall events led to enhanced total E _c during the growing season, but prolonged rainless intervals did not lead to a continuous decrease of E _c , suggesting appreciable supplements from the soil water were present to sustain transpiration. In addition, the balance of soil water between replenishment and extraction also conditioned the influence of rainfall over subsequent E _c during the respective rainless intervals. Based on the E _c responses to VPD and rainfall under different soil moisture levels, irrigation that directly replenishes the deep soil layers in order to alleviate water stress on transpiration during the small-rain event-dominated growing season is an effective and water-saving approach to guarantee trees survival during drought period.     

甩挂运输车队运营组织模式分析

甩挂运输作为一种节能减排、低碳高效的运输方式,也是我国目前大力倡导推行的运输方式之一,甩挂运输不仅是发展低碳物流的手段,也是企业提高工作效率,获得更大的经济效益和社会效益的可行之举.在国家政策和行业发展的推动下,甩挂运输必将成为运输行业的发展趋势.本文对甩挂运输的工作原理进行介绍,并针对甩挂运输的车队运营组织模式进行分析,将其分为4大类.结合图像对每一类运营组织模式的特点进行研究,并通过实例分析,得出该类模式的适用情况.通过系统的比较和分析这4种不同的车队组织运营模式,从理论上为物流运输企业开展甩挂运输的车队运营组织模式选择提供决策依据.     

Patterns of Tetracapsuloides bryosalmonae infection of three salmonid species in large,deep Norwegian lakes

Proliferative kidney disease (PKD), caused by the myxozoan endoparasite Tetracapsuloides bryosalmonae, is of serious ecological and economical concern to wild and farmed salmonids. Wild salmonid populations have declined due to PKD, primarily in rivers, in Europe and North America. Deep lakes are also important habitats for salmonids, and this work aimed to investigate parasite presence in five deep Norwegian lakes. Kidney samples from three salmonid species from deep lakes were collected and tested using real-time PCR to detect PKD parasite presence. We present the first detection of T. bryosalmonae in European whitefish in Norway for the first time, as well as the first published documentation of the parasite in kidneys of Arctic charr, brown trout and whitefish in four lakes. The observed prevalence of the parasite was higher in populations of brown trout than of Arctic charr and whitefish. The parasite was detected in farmed, but not in wild, charr in one lake. This suggests a possible link with a depth of fish habitat and fewer T. bryosalmonae-infected and PKD-affected fish. Towards a warmer climate, cold hypolimnion in deep lakes may act as a refuge for wild salmonids, while cold deep water may be used to control PKD in farmed salmonids.     

Treatment Method Affects Color,Chemical, and Mineral Composition of Seabream (Sparus aurata) Fish Bone Powder from by-Products of Fish Fillet

ABSTRACT

Seabream fish bone powder was produced using different chemical methods and tap water. The effect of different chemical procedures (sodium hydroxide (NaOH); NaOH + citric acid; NaOH + sodium hypochlorite (NaOCl); NaOH + ethanol (EtOH); and NaOH + hydrogen chloride (HCl)) and tap water on proximate composition, yield, mineral composition, color, and sensorial odor was investigated. Despite its high bone powder yield (59.39%), tap water treatment was not an efficient method due to low calcium (Ca²⁺, 232.13 g/kg) and phosphorus (P, 111.63 g/kg) concentration and heavy fish odor. Sensorial odor analysis of seabream fish bone powder showed that tap water received the lowest scores (1.71/5), while chemically treated samples received sensorial odor scores higher than 4.00, with an average of 4.61, indicating that they had a very slight odor. The best fish bone powder yield was obtained using NaOH treatment (21.46%), where Ca²⁺ (276.73 g/kg) and P (147.23 g/kg) content was also high. The utilization of chemicals in combination with NaOH did not increase the sensorial odor score of seabream fish powders but resulted in a decrease in powder yield. Moreover, the mineral composition of all chemical processing techniques was comparable. Processing by-products of seabream fillet production with 8% NaOH will contribute to daily Ca²⁺ and P intake of individuals.