Abstract Groundwater discharge flux into rivers (riverine groundwater discharge or RGD) is essential information for the conservation and management of aquatic ecosystems and resources. One way to estimate area‐integrated groundwater discharge into surface water bodies is to measure the concentration of a groundwater tracer within the water body. We assessed groundwater discharge using 222 Rn, a tracer common in many surface water studies, through field measurements, surface water 222 Rn mass balance model, and groundwater flow simulation, for the seldom studied but ubiquitous setting of a flooding river corridor. The investigation was conducted at the dam‐regulated Lower Colorado River (LCR) in Austin, Texas, USA. We found that 222 Rn in both the river water and groundwater in the river bank changed synchronously over a 12‐hour flood cycle. A 222 Rn mass balance model allowed for estimation of groundwater discharge into a 500‐m long reach of the LCR over the flood. The groundwater discharge ranged between negative values (indicating recharge) to 1570 m 3 /h; groundwater discharge from groundwater flow simulations corroborated these estimates. However, for the dynamic groundwater discharge estimated by the 222 Rn box model, assuming whether the groundwater 222 Rn endmember was constant or dynamic led to notably different results. The resultant groundwater discharge estimates are also highly sensitive to river 222 Rn values. We thus recommend that when using this approach to accurately characterize dynamic groundwater discharge, the 222 Rn in near‐stream groundwater should be monitored at the same frequency as river 222 Rn. If this is not possible, the 222 Rn method can still provide reasonable but approximate groundwater discharge given background information on surface water‐groundwater exchange time scales.
An important direction in the field of computer science research is computer application technology research. For example, how to use advanced deep learning technology to process crime big data to quickly assist in the detection of drug-related cases. Profile of criminal case is important intelligen
Groundwater is a critical water resource for human survival and economic development in arid and semi-arid areas. It is crucial to understand the groundwater circulation and hydrochemical evolution for sustainable management and utilization of groundwater resources in those areas. To this end, an investigation of the hydrochemical characteristics of surface water and groundwater was conducted in Nomhon, an arid area located in the Qaidam Basin, northwest China, by using hydrochemical (major and trace elements) and stable isotopes (δD and δ18O) approaches. Stable isotopes and ion ratios were analyzed to determine the recharge sources, hydrochemistry characteristics, and major hydrogeochemical processes. Meanwhile, inverse geochemistry modeling was applied to quantitatively determine the mass transfer of hydrogeochemical processes. The results showed that groundwater in the study area is mainly recharged by atmospheric precipitation in mountainous areas, and the groundwater in the center of basin might originate from ancient water in cold and humid environments. Along the groundwater flow path, the TDS of groundwater increased gradually from fresh to salty (ranging from 462.50 to 19,604.40 mg/L), and the hydrochemical type changed from Cl·HCO3–Na·Mg·Ca to Cl–Na. Groundwater chemical composition and mass balance modeling results indicated that from alluvial fan to lacustrine plain, the main hydrogeochemical processes changed from the dissolution of halite and albite and the precipitation of dolomite and kaolinite to the dissolution of halite and gypsum, precipitation of calcite, redox (SO42− reduction), and cation exchange. This study would be helpful for water resources management in this area and other similar areas.
Abstract The oxygen evolution reaction (OER) involves the recombination of diamagnetic hydroxyl (OH) or water (H 2 O) into the paramagnetic triplet state of oxygen (O 2 ). The spin conservation of oxygen intermediates plays a crucial role in OER, however, research on spin dynamics during the catalytic process remains in its early stages. Herein, β ‐Ni(OH) 2 and Fe‐doped β ‐Ni(OH) 2 (Ni 5 Fe 1 (OH) 2 ) are utilized as model catalysts to understand the mechanism of spin magnetic effects at iron (III) sites during OER. Combined with magnetic characterization, it is founded that the introduction of Fe transforms the antiferromagnetic Ni(OH) 2 into a ferromagnetic material. Testing the magnetic response of the catalyst under an external magnetic field, the OER activity of Ni 5 Fe 1 (OH) 2 is significantly enhanced in comparison to Ni(OH) 2 . This improvement is likely due to the introduction of iron sites, which promote spin magnetic effects and enhance reaction kinetics, thereby increasing catalytic efficiency. Combining experimental and theoretical characterization, it is discovered that the iron sites accelerate the formation of heterogeneous dual‐site O─O bridging, represented as ─Ni─O─O─Fe─, thereby effectively enhancing the kinetics of the OER reaction. This study provides a magnetic perspective on the structure‐function relationship of magnetic iron‐based catalysts and has significant implications for the design of new catalysts.
Abstract Background Thermogravimetric analysis (TGA) is an important method to characterize the pyrolysis reaction characteristics of tobacco, reflecting the chemical composition of tobacco from the perspective of chemical reaction. However, quantitative analysis of tobacco chemical indexes based on TG curve has not yet been reported due to the complexity to the best of our knowledge. Results By the combination of TG curve and partial least squares (PLS) algorithm, we established quantitative analysis models of six routine chemical constituents in tobacco, including total sugar, reducing sugar, total nitrogen, total alkaloids, chlorine and potassium. We also performed an in-depth analysis of the chemical mechanism revealed by the result of the quantitative model, namely the regression coefficient which reflected the correlation degree between the six chemicals and different stages of tobacco thermal decomposition process. Conclusions The quantitative analysis model of chemical constituents in tobacco based on TG curve can be used for the rapid and accurate analysis of compound content. From the perspective of pyrolysis reaction mechanisms, the quantification of total sugar and reducing sugar mainly depended on the Maillard reaction in which carbohydrate compounds participate. The correlation of total nitrogen and total alkaloids with TG curves in the whole temperature range was affected by total sugar. Although chlorine was detrimental to Maillard reaction in general, it has different effects on the different elementary steps of the Maillard reaction. Potassium can promote the thermal decomposition of hemicellulose, pectin, and water-soluble carbohydrates such as glucose and fructose.
Parallel-plate flow chamber is a widely used equipment in studying cellular mechanics in vitro. Many researchers used parallel-plate flow chamber to provide shear stress and to mimic in vivo the environment of cancer cell growth. It is a versatile tool in understanding the mechnisms of proliferation,adhesion,and metastasis of cancer cell. Cancer-detecting devices were also developed based on parallel-plate flow chamber. A new field overlapping biomechanics and cancer research was developed. Application of parallel-plate flow chamber in cancer research is reviewed in this paper.
Environmental control and life support system (ECLSS) is a critical subsystem of manned spacecraft that has the most typical characteristics of manned space flight. It is an indispensable safeguard for the life of astronaut in space. This article reviewed the main techniques and developments of oxygen and water closed loop recycling in regenerative environmental control and life support system. Through comparing and analyzing the current state of its space application as well as the strong and weak points of different technique routes, the directions of research and development of oxygen and water recycling technique for space station are proposed.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)