The effects of density and artificial substrate on intensive shrimp Litopenaeus vannamei nursery production

Recirculating aquaculture systems (RAS) can be installed indoors, allowing year-round production of tropical animals in nearly any climate. A nursery phase is commonly used in Litopenaeus vannamei production since it allows for enhanced biosecurity and better quantification of animals while reducing space requirements. However, it is unclear whether animal density and inclusion of artificial substrate may improve shrimp performance during the nursery phase. In this experiment, we compared shrimp production parameters in two stocking densities with or without the use of an artificial substrate by creating four treatments: low-density LD; 1500 PL/m⁻³, low-density with substrate LDS, high-density HD; 3000 PL/m⁻³), and high-density with substrate (HDS). The LDS and HDS treatments included 0.46-m² of high-density polyethylene 2.5-cm mesh as a substrate, which increased the tank surface area by 21 %. Each treatment was randomly assigned to four 160-l culture tanks, each with a biofilter. The shrimp had an initial weight of 4 mg and were grown for 50 days. The low-density treatments had significantly higher dissolved oxygen (DO) and pH than the high-density treatments (P ≤ 0.001). Specifically, LDS had the highest DO and pH followed by the LD, HD, and HDS treatments, respectively. High-density treatments had significantly higher NO₂-N levels than low-density treatments during week 2 of the experiment when an unusually high concentration of nitrite was observed. FCR was significantly lower in both low-density treatments than in high-density treatments. At harvest, the total biomass (kg m⁻³) was significantly higher in high-density treatments than in low-density treatments (P ≤ 0.001), and the HDS treatment had a significantly greater biomass output than HD. Producers should consider artificial substrate and higher densities during nursery production to maximize shrimp production; however, the effects on water quality should also be taken into account.     

室内自然景观对室内环境调节、净化的作用

主要针对公共场所(酒店餐饮空间)的室内温度、相对湿度、CO2体积分数、甲醛(HCHO)和总挥发性有机物(TVOC)质量浓度等5个室内空气质量的重要参数进行了检测和分析。结果表明,设有植物、水景等自然景观的室内,其5项空气指标均明显优于不设自然景观的室内空间。由此说明,自然景观对室内环境具有显著的调节、净化等生态作用。     

农药飘移状况的室内模拟测定

以硫酸铜代替农药,采用室内恒定风速模拟,结合分光光度法测定和数学模型拟和,研究了不同农药喷雾量及喷雾溶液浓度接近地面飘移情况.结果表明,在本试验条件下,飘移路径上某一点收集到的有效成分比例为常数,该常数与飘移距离高度相关,与喷雾量和喷雾溶液浓度无关.     

木质居室环境综合评价

采用模糊数学理论研究人们对木质居室环境的综合评价,并将其与传统建筑物的室内环境进行了比较。通过调查研究表明,专家们对木质复合墙体结构住宅的室内环境的评价较高,这种结构的住宅在人们的主观意识中能得到认可。     

室内立体绿化方法探析

指出了室内环境质量直接影响人们的身心健康,通过运用立体绿化的方式,可以改善室内居住环境,调节人的情绪并提升室内综合美感。概括了室内立体绿化的概念和特点,论述了室内立体绿化的设计布局形式和种植要求,以及绿化植物的选择和种植方法,并对未来室内立体绿化的发展提出了建议。     

姬松茸的栽培技术

姬松茸(Agaricus blazei Murrill)是一种食药兼用真菌。本文介绍其食用、药用价值,生物学特性及室内外栽培、管理、加工技术。     

无公害室内灵芝栽培技术

报道了梅州无公害灵芝室内栽培技术特点,包括产地环境、栽培基质、生产季节、菌种、室内栽培技术、产品包装与保藏要求,供各地灵芝栽培者参考。     

七种杀菌剂对水稻纹枯病菌的室内毒力及田间防效评价

本研究评价了七种杀菌剂对水稻纹枯病菌的室内毒力及田间防效。室内毒力测定结果表明：30%肟菌.戊唑醇悬浮剂、35%噻呋.氟环唑悬浮剂、32%噻呋.戊唑醇悬浮剂、30%戊唑.嘧菌酯悬浮剂、500g/L苯甲.丙环唑乳油这5种杀菌剂混剂对水稻纹枯病菌均有较强的抑制作用,EC₅₀值在0.0572~0.2265 mg.L^_-1之间。田间防效试验结果表明：在药后7d,对水稻纹枯病防效最好的药剂为30%肟菌.戊唑醇悬浮剂,防效为95.02%,30%戊唑.嘧菌酯悬浮剂、32%噻呋.戊唑醇悬浮剂、35%噻呋.氟环唑悬浮剂和500g/L苯甲.丙环唑乳油的防效分别为93.15%、92.53%、92.26%、91.81%;在药后14d,30%肟菌.戊唑醇悬浮剂这5种杀菌剂混剂对水稻纹枯病的防效均达到93%以上。     

苏州市室内植物装饰现状

在调查苏州市现代商业空间、银行、医院、宾馆大厅、餐饮空间、图书馆、办公空间室内植物装饰现状的基础上,分析其特点,指出不足之处,并提出了合理的建议。     

定向结构板居室室内热环境的研究

运用温湿度自动记录仪对3种不同结构实体建筑的室内垂直空间的温湿度，墙体内外表面温度进行了监测，分析了建筑物的日平均温度变动比、衰减倍数。墙体内外表面以及室内垂直空间的温湿度分布，研究结果表明，内外表面均采用定向结构板，中间填充玻璃棉的复合墙体比传统砖墙的保温隔热性能好，能有效地抵抗外界大气环境对室内热环境影响的作用。