A brief introduction to recent applications of several sediment-analysis techniques in palaeolimnological studies-dry bulk density and water content, mineral magnetism, carbonate content, and content of total organic carbon,nitrogen content and carbon/ni

Determination of dry bulk density and water content measurement of magnetic susceptibility (x) and saturation isothermal remanent magnetization (SIRM), determination of carbonate content, and determination of total organic carbon (TOC) content nitrogen content (N%) and carbon/nitrogen (C/N) ratio are some of the techniques which have been widely applied to lacustrine-sediment analyses. The techniques,complemented by others, are usually useful for revealing characteristics of lacustrine-sediments and thus for postulating hydrological regimes in the lake and environmental conditions and human activity around it in palaeolimnological studies. A very brief review is presented on recent applications of these techniques in palaeolimnological work with English literatures published mainly since 1985 and focus given on interpretations of results of these analyses related to palaeoenvironmental reconstructions. Low dry bulk density and high water content often imply relatively warm and wet conditions. High X and SIRM are usually resulted from reduced dilutions in the lake and intensified erosions on its catchment. both of which can be in turn attributed to environmental changes. While variations in patterns of X and SIRM may give further insight on mineral magnetism and thus implications on environmental conditions. Increased carbonate content seems likely to associate to warm and dry conditions.Increased TOC content is virtually used as one of indicators of warm and wet conditions and variations in C/N ratio may hint variations in relative contributions of different sources, aquatic and terrestrial, to the total organic matter in lake sediments and hence to lake-level fluctuations and climate changes.

Root length density distribution and associated soil water dynamics for tomato plants under furrow irrigation in a solar greenhouse

Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in water-limited regions. The objectives of this study are to analyze root length density distribution and to explore soil water dynamics by simulating soil water content using a HYDRUS-2D model with consideration of root water uptake for furrow irrigated tomato plants in a solar greenhouse in Northwest China. Soil water contents were also in-situ observed by the ECH_2O sensors from 4 June to 19 June and from 21 June to 4 July, 2012. Results showed that the root length density of tomato plants was concentrated in the 0–50 cm soil layers, and radiated 0–18 cm toward the furrow and 0–30 cm along the bed axis. Soil water content values simulated by the HYDRUS-2D model agreed well with those observed by the ECH_2O sensors, with regression coefficient of 0.988, coefficient of determination of 0.89, and index of agreement of 0.97. The HYDRUS-2D model with the calibrated parameters was then applied to explore the optimal irrigation scheduling. Infrequent irrigation with a large amount of water for each irrigation event could result in 10%–18% of the irrigation water losses. Thus we recommend high irrigation frequency with a low amount of water for each irrigation event in greenhouses for arid region. The maximum high irrigation amount and the suitable irrigation interval required to avoid plant water stress and drainage water were 34 mm and 6 days, respectively, for given daily average transpiration rate of 4.0 mm/d. To sum up, the HYDRUS-2D model with consideration of root water uptake can be used to improve irrigation scheduling for furrow irrigated tomato plants in greenhouses in arid regions.

ARTICLE Analyzing Potential Water Harvesting from Atmosphere in Near Coastal Area

Water is a basic need.However there are many near coastal regions which have very limited access to fresh water.The water in area close to coastal is mainly affected by ocean,indirectly by weather/climate conditions and directly from seawater intrusion.While abundant fresh water is actually available in the atmosphere in the form of moisture.Recent technology,such as Atmospheric Water Generator(AWG),is a possible solution to gain water from our atmosphere.However,comprehensive study is need­ed to understand the potential water harvesting in our atmosphere.Here,we examine the water availability in the atmosphere based on several parameters like temperature and humidity.The data are collected from observation using WS1040 Automatic Weather Station in a year of 2020 with a half-hour interval.Then,we calculate the availability of water con­tent during each season,especially in dry conditions.We also simulate the water harvesting to fulfil daily basic need of fresh water.The atmospheric parameters have shown a monsoonal pattern.Water content decrease in atmosphere during the dry season but the water deficit occurs after the dry season.Although water harvesting able to supply daily freshwater need,it is not recommended to be a single source as it requires massive water storage and high-efficient AWG.

Effect of discrete fibre reinforcement on soil tensile strength

The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to deter- mine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly in- crease soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0% to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m^3 is 2.8 times higher than that at 1.4 Mg/m^3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interracial mechanical interaction between fibre surface and soil matrix.

Protective effects of Bushen Tiansui decoction on hippocampal synapses in a rat model of Alzheimer's disease

Bushen Tiansui decoction is composed of six traditional Chinese medicines：Herba Epimedii,Radix Polygoni multiflori,Plastrum testudinis,Fossilia Ossis Mastodi,Radix Polygalae,and Rhizoma Acorus tatarinowii.Because Bushen Tiansui decoction is effective against amyloid beta（Aβ） toxicity,we hypothesized that it would reduce hippocampal synaptic damage and improve cognitive function in Alzheimer＇s disease.To test this hypothesis,we used a previously established animal model of Alzheimer＇s disease,that is,microinjection of aggregated Aβ25–35 into the bilateral brain ventricles of Sprague-Dawley rats.We found that long-term（28 days） oral administration of Bushen Tiansui decoction（0.563,1.688,and 3.375 g/m L;4 m L/day） prevented synaptic loss in the hippocampus and increased the expression levels of synaptic proteins,including postsynaptic density protein 95,the N-methyl-D-aspartate receptor 2 B subunit,and Shank1.These results suggested that Bushen Tiansui decoction can protect synapses by maintaining the expression of these synaptic proteins.Bushen Tiansui decoction also ameliorated measures reflecting spatial learning and memory deficits that were observed in the Morris water maze（i.e.,increased the number of platform crossings and the amount of time spent in the target quadrant and decreased escape latency） following intraventricular injections of aggregated Aβ25–35 compared with those measures in untreated Aβ_（25–35）-injected rats.Overall,these results provided evidence that further studies on the prevention and treatment of dementia with this traditional Chinese medicine are warranted.