Water and Salt Transports in the Hengsha Channel of Changjiang Estuary

In a multilevel bifurcated estuary, the channels between the bifurcated branches play important roles in the exchanges of water and salt. In the Changjiang Estuary, the Hengsha Channel (HC) connects the North Channel (NC) and the North Passage (NP). In this paper, based on a two-way nesting unstructured quadrilateral grid, finite-differencing, three-dimensional estuarine and coastal ocean model, the tidal and seasonal variations in the water and salt transports in the HC were simulated, and their dynamic mechanism was analyzed. The residual water and salt transports in the HC both flow southward from the NC to the NP. In wet season, the residual water transport in the HC is 677 m3/s during neap tide and 245 m3/s during spring tide, and the residual salt transport is 0. In dry season, the residual water and salt transports in the HC are 1278 m3/s and 0.38 t/s during neap tide, respectively, and 1328 m3/s and 12.61 t/s during spring tide. Affected by the northerly wind and the southeastward baroclinic gradient force, the water and salt fluxes in dry season are much larger than those in wet season. The dynamic mechanism responsible for the water transport in the HC was numerically simulated and analyzed.

Phase Transfer Catalysts and Role of Reaction Environment in Nucleophilc Radiofluorinations in Automated Synthesizers

Incorporation of [18F]fluorine into PET radiotracer structure has traditionally been accomplished via nucleophilic pathways. The [18F]fluoride is generated in an aqueous solution via proton irradiation of oxygen-18 enriched water and must to be introduced into water-free organic solutions in order to generate reactive species. Thus nucleophilic 18F-fluorination traditionally included steps for [18F]fluoride concentration on the anion exchange resin, followed by removal of residual water via azeotropic distillation with MeCN, a time-consuming process associated with radioactivity losses and difficult automation. To circumvent this, several adsorption/elution protocols were developed based on the minimization of water content in traditional kryptofix-based [18F]fluoride eluents. The use of pre-dried KOH/kryptofix solutions, tertiary alcohols, and strong organic bases was found to be effective. Advances in transition metal-mediated SNAr approaches for radiolabeling of non-activated aromatic substrates have prompted development of alternative techniques for reactive [18F]fluoride species generation, such as organic solutions of non-basic alkyl ammonium and pyridinium sulfonates, etc. For radiofluorinations of iodonium salts precursors, a “minimalist” approach was introduced, avoiding the majority of pitfalls common to more complex methods. These innovations allowed the development of new time-efficient and convenient work-up procedures that are easily implementable in modern automated synthesizers. They will be the subject of this review.

Effect of Tea Waste on Cracking of Foundation Soil

Desiccation cracks form on the surface of foundation soils due to matric suction and surface shrinkage with water loss. This paper investigates the effect of tea waste on the change of water content and cracking characteristics of foundation soil during drying. Digital image processing was carried out based on laboratory experiments. The characteristics are monitored with a variation in water content. The effects of different amounts of tea waste on soil drying and cracking were obtained, in order to provide an efficient and new green sustainable material for improving soil evaporation cracking under drought conditions. The results show that the development of cracks of soil samples with tea waste can be categorized into three stages in accordance with the fractal dimension of the desiccation cracks: Stages I, II, and III. The desiccation cracks in Stage III are wider and longer than those in Stages I and II, however, the maximum fractal dimension and stability are also obtained in Stage III. The residual water content of the sample without tea waste is 1.5%. The residual water content of the samples containing 4% and 8% tea waste is 4.6% and 5.4%, respectively, which shows that the tea waste can effectively improve the residual water content of the foundation soil and the water holding capacity of the soil. The fractal dimension of cracks on the soil samples increases gradually with drying. The total length of cracks increases and the development of cracks is more complex. The cracking time of soil samples with different tea waste contents is different. The soil samples with 8% tea waste content crack first. Combined with the variation characteristics of water content, tea waste has water absorption and improves the water holding capacity and stability of foundation soil.

Study on some features of water exchange of local varieties of hard wheat

This article discusses the main physiological indicators of water exchange in winter wheat varieties Makus-3, Istiklal and Istiklal-20. There were revealed indicators of daily and residual water deficit of leaves, as well as the water potential of leaves.As you are aware, drought resistance of plants depends on a number of factors. In particular, it is largely determined by the biological characteristics of plants.In this regard, the identification of the features of the physiological processes of the water regime and the associated metabolic processes that determine the resistance to drought in various varieties and hybrids of wheat is of great interest not only in scientific but also in practical terms, because the research results can be used to develop recommendations for selection of source forms for breeding work. We have studied a number of indicators of the water regime of local varieties of winter wheat -Istiklal, Istiklal-20 and Makus-3. The research was carried out on plants grown under the conditions of vegetation and field experiments in the phases of booting, earing, flowering and waxy ripeness.

The impact of raindrops on Salvinia molesta leaves: effects of trichomes and elasticity

The floating leaves of the aquatic fern Salvinia molesta are covered by superhydrophobic hairs (=trichomes) which are shaped like egg-beaters. These trichomes cause high water repellency and stable unwettability if the leaf is immersed. Whereas S. molesta hairs are technically interesting, there remains also the question concerning their biological relevance. S. molesta has its origin in Brazil within a region exposed to intense rainfall which easily penetrates the trichome cover. In this study, drop impact on leaves of S. molesta were analysed using a high-speed camera. The largest portion of the kinetic energy of a rain drop is absorbed by elastic responses of the trichomes and the leaf. Although rain water is mostly repelled, it turned out that the trichomes hamper swift shedding of rain water and some residual water can remain below the ‘egg-beaters’. Drops rolling over the trichomes can, however, ‘suck up’ water trapped beneath the egg-beaters because the energetic state of a drop on top of the trichomes is—on account of the superhydrophobicity of the hairs—much more favourable. The trichomes may therefore be beneficial during intense rainfall, because they absorb some kinetic energy and keep the leaf base mostly free from water.

Numerical Modelling of Moisture Loss during Controlled Drying of Marine Archaeological Wood

If left to dry uncontrollably following excavation, marine archaeological wood suffers significant and irreparable damage. Conservation treatments are required to consolidate degraded wood and to remove residual water. Drying must be controlled to eliminate erratic and heterogeneous water removal. Monitoring and understanding the drying process progression is invaluable information to garner real-time knowledge to correlate with chemical and physical material properties, and to develop future conservation strategies. Here, polyethylene glycol (PEG) consolidated marine archaeological wood was periodically sampled during drying to determine the moisture content as a function of location, time, and sample depth. The heterogeneous nature of the material leads to significant noise across spatial and temporal measurements, making it challenging to elucidate meaningful conclusions from visual observation of the raw data. Therefore, the spatiotemporal data was computationally analysed to produce a representative model of the ship’s drying, illustrated by a dynamic simulation. From this we can quantitatively predict the drying rate, determine the depth-dependence of drying, and estimate the resulting equilibrium moisture content. This is the first time such simulations have been carried out on this material and conservation process, demonstrating the power of applying numerical modelling to further our understanding of complex heritage data.

Estimation of quantitative criteria of carbonate reservoirs of triassic deposits

This paper discusses the boundary values of the reservoir properties of carbonate rocks of the Triassic sediments of South Mangyshlak, which are important for the interpretation of production geophysical data and for perforating and blasting operations. In terms of lithological composition, Triassic deposits are represented by two types of commercial reservoirs terrigenous and carbonate. Carbonate reservoirs are localized in the volcanic-dolomite and volcanic-limestone strata of the Middle Triassic. These rocks are characterized by a complex type of reservoir: porous-fractured, porous-cavernous and fractured. Sediments of the Upper Triassic occur with erosion on the Middle Triassic sedimentary complex and are represented by alternating tuffaceous, silt-sandy and mudstone rocks. Polymictic sandstones are oil-saturated to varying degrees; oil deposits are confined to them. To substantiate the quantitative criteria of the reservoir, the results obtained during special laboratory studies of the core were used. Filtration studies were carried out, where physical and hydrodynamic characteristics were determined when oil was displaced by displacing reagents. The obtained parameters were used to construct correlations collector non-collector. Using the relationships between the reservoir properties of the reservoir, the dependence of the porosity and permeability on the residual water content, as well as open porosity and permeability on the dynamic porosity, the boundary values were determined.

Intraluminal Behavior of Various Transporter Substrates in the Rat Gastrointestinal Tract

Purpose: The aim of this study was to evaluate the intraluminal behavior of various transporter substrates in different regions of the gastrointestinal (GI) tract. Methods: Drug solutions containing non-absorbable FITC-dextran 4000 (FD-4), were orally administered to rats. Residual water was sampled from the GI regions to measure the luminal drug concentration. Results: Cephalexin (CEX), a substrate of the proton-coupled oligopeptide transporter, was absorbed rapidly, and no drug was detected in the lower small intestine. Saquinavir (SQV) was primarily absorbed in the upper region. However, unlike CEX, SQV was detected even in the lower segment probably due to the efflux of SQV via P-glycoprotein (P-gp). The concentration of methotrexate (MTX) showed a similar pattern to that of non-absorbable FD-4. The low absorption of MTX was probably due to efflux via several efflux transporters, and the limited expression of proton-coupled folate transporter, an absorptive transporter for MTX, in the upper region. Conclusion: This study revealed that the luminal concentration pattern of each drug differed considerably depending on the site because of the different absorption properties and luminal volumes. Although further investigation using a specific transporter inhibitor or transporter-knockout animals are necessary to clarify the actual contribution of each transporter to the drug absorption, this information will be valuable in evaluating transporter-mediated drug absorption in in vitro transport studies for ensuring optimal drug concentrations.

Removal of nutrients from aquaculture residual water: A review

Aquaculture plays an important role in providing protein-rich foods, meeting the growing demand for fish. However, aquaculture is a potentially polluting activity, especially with regard to water pollution, due to the improper disposal of wastewater from the production process. Aquaculture wastewater is rich in nutrients (ammonia, nitrate, nitrite and phosphorus) and organic matter, and is commonly discharged into the environment without proper treatment. This can cause a series of environmental impacts and aggravate the current water crisis. Due to the importance and need to reduce environmental impacts, plan the use of water resources and achieve an efficient and sustainable production process, many researchers have focused their studies on effluent treatment techniques designed to remove these nutrients. This article therefore presents an updated review of the main physicochemical and biological techniques used in the removal of nutrients, which can mitigate environmental problems arising from aquaculture activities and contribute to the sustainability of the activity. Keywords: biological removal, nitrogen compounds, sustainable activity.