•DOM chemistry was investigated in the Three Gorges Reservoir•Higher terrestrial input, molecular and isomeric complexity of DOM were detected in storage period•Hydrological management of reservoirs ...shifts the DOM chemistry•Hydrological management would affect DOM mineralization and CO2 emission in young reservoirs
Reservoirs are well known as a far-reaching human modification on the functions of natural river networks. However, changes in the chemistry and reactivity of dissolved organic matter (DOM) responding to hydrological management for water retention structures, and its influence on the river carbon cycle, remain poorly understood. Here we show that hydrological management does shape the molecular composition of DOM in the world's largest Three Gorges Reservoir, as revealed by optical spectroscopy and ultrahigh-resolution mass spectrometry. Relatively higher terrestrial input, molecular complexity, isomeric complexity, and environmental stability of DOM were observed during the storage period, whereas the inverse occurred during the drainage period. The results demonstrate that the hydrodynamic processes, which are mainly controlled by water intrusion from mainstream to tributaries, are likely the underlying mechanism controlling DOM chemistry. Integrated with observations from worldwide river reservoirs, the DOM degradation experiments suggest that reservoir hydrological management would enhance DOM mineralization, thereby increase CO2 emission and change the river carbon cycle.
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•A refrigerant composition matching method for N2–CH4 expansion processes.•Efficiency improvements for propane pre-cooled N2–CH4 expansion processes.•The process shows good adaptability to varying ...natural gas compositions.
An expansion process with a pre-cooling system is simulated and optimised by Aspen HYSYS and MATLAB™. Taking advantage of higher specific refrigeration effect of methane and easily reduced refrigeration temperature of nitrogen, the designed process adopts N2–CH4 as a mixed refrigerant. Based on the different thermodynamic properties and sensitivity difference of N2 and CH4 over the same heat transfer temperature range, this work proposes a novel method of matching refrigerant composition which aims at single-stage or multi-stage series expansion liquefaction processes with pre-cooling systems. This novel method is applied successfully in propane pre-cooled N2–CH4 expansion process, and the unit power consumption is reduced to 7.09 kWh/kmol, which is only 5.35% higher than the global optimised solutions obtained by genetic algorithm. This novel method can fulfil the accomplishments of low energy consumption and high liquefaction rate, and thus decreases the gap between the mixed refrigerant and expansion processes in energy consumption. Furthermore, the high exergy efficiency of the process indicates good adaptability to varying natural gas compositions.
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Large rivers transport a significant amount of terrestrially derived dissolved organic matter (DOM) to coastal oceans, consisting of a critical component of the global biogeochemical cycle. Although ...high flow events usually introduce more terrestrial DOM than baseflow, the underlying molecular complexity and lability of DOM during high discharge are not well constrained, especially in large river ecosystems. By combining ultraviolet and fluorescent spectroscopy, and ultrahigh-resolution mass spectrometry, we found that stronger terrestrial DOM signal was detected during high discharge than normal discharge in the Yangtze River mainstream. The averaged DOC concentration was higher during high discharge than normal discharge. Optical properties confirmed higher aromaticity and relatively higher humic-like fluorescent components in DOM during high discharge. The molecular composition showed significantly higher molecular complexity, averaged molecular weight, aromaticity, relative abundances of polyphenols and highly unsaturated compounds of DOM during high discharge than normal discharge. A large set of unique molecular formulae (up to 4927) was only detected during high discharge. These unique molecular formulae were mostly lignin degradation products, likely due to more intensive soil leaching during high discharge. By comparing with incubation experiments and the Yangtze River mouth and East China Sea DOM molecular composition, some of these unique molecular formulae during high discharge are resistant to both bio- and photo-degradation, and persist during their transport to the East China Sea. Therefore, we suggest that high discharge will additionally introduce a relatively recalcitrant pool of DOM into the Yangtze River mainstream and persist during its journey to the ocean. Considering the projected increase of flood frequency, this study provides a preliminary foundation for further studies to better assess the underlying mechanisms how hydrology affect the biogeochemical cycling of DOM in large rivers.
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•Complex sources of DOM during high discharge was investigated in the Yangtze River.•A pool of unique refractory molecules during high discharge was investigated.•Floods likely enhance the transport of refractory compounds from river to sea.
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Mitochondria are the “power plant” of the cell, providing a constant source of energy, and are involved in a variety of intracellular signaling pathways. Among these pathways, Ca2+ homeostasis is ...closely related to the normal function of mitochondria. By destroying the Ca2+ steady state of mitochondria and disrupting their multiple cellular activities, tumor cell killing can be achieved. In addition, the presence of an intracellular oxidative stress state triggers the closure of cellular calcium channels, which leads to intracellular Ca2+ retention and enrichment. We designed a targeted and tumor microenvironment (TME)-responsive CaO2-based nanosystem that can selectively target cancer cells for pH-controlled degradation and drug release, alter cellular physiological mechanisms by disrupting Ca2+ homeostasis in an artificial manner, and introduce mitochondrial Ca2+ excess-mediated apoptosis. Meanwhile, the production of Ca(OH)2 will raise the pH of the microenvironment and subsequently promote the oxidation process of glutathione by H2O2 released from CaO2 degradation, achieving the goal of remodeling TME. Moreover, calcium overload of tumor cells and calcification of tissues can both inhibit tumor growth and act as a contrast agent for computed tomography imaging.
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Proper understanding and evaluation of a metal production process is crucial for its further optimization. Economic evaluation is frequently used to estimate the practicality of a specific process ...based on the product life cycle assessment. However, it encounters difficulties to identify the importance of materials efficiency coupling with pollution control during evaluation on the effectiveness of process optimization. In this research, a factor defining the material recirculation is introduced to economic evaluation. Typical vanadium oxide production processes in China were evaluated by the economic evaluation model considering the whole production process, through defining a range of parameters, i.e., the materials cost, water cost, energy cost, waste treatment cost and auxiliary cost. Three V2O5 production processes are analyzed and compared to each other. The production process of high purity V2O5 has the best cost-effective products with high purity, the simplest production, the highest materials efficiency and the lowest cost for waste treatment. It is noticed that materials efficiency tends to be inversely proportional to waste treatment cost. Under comprehensive environmental assessment, proper pollutant control improves material recirculation percentage and reduces the expense for waste treatment which is an important aspect of economic evaluation. With this research, an optimization scheme is illustrated for the economic evaluation of typical metal production process which may provide guidance to industrial factories to optimize relevant production processes.
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•A material recirculation factor is introduced to economic evaluation model.•Typical vanadium oxide production processes were evaluated.•Comprehensive environmental assessment analyzed environmental impact of the waste.•The high recirculation percentage can effectively decrease the total cost.
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The complexity of dissolved organic matter (DOM) limits our understanding of the estuarine carbon cycle. This study adopted a combination of bulk carbon isotope, optical techniques and ultra-high ...resolution mass spectrometry to study the spatial heterogeneity and compositional variations of DOM across a latitudinal transect of the Yangtze River Estuary (YRE). Results show that the whole section of YRE received high abundance of protein-like C4 fluorescent component (0.66 ± 0.08 R.U.) and high relative abundance of aliphatic compounds and peptides (8.28 ± 1.46%) from phytoplankton, which would contribute to the bioavailable DOM pool of the Eastern China Sea (ECS). However, multivariate analysis indicated that polycyclic aromatics and polyphenols from the Yangtze River experienced a significant decrease of 5% within the turbidity zone, creating a significant decrease of 0.08 in aromaticity index and modulating DOM content and compositions within the YRE. 1837 molecular formulae were identified to track dynamic behaviors of terrestrial DOM in the YRE. Molecular imprints showed the removal of terrestrial molecules in the turbidity zone indicated by the decrease of 753 in molecular quantity, when water masses mixing diluted the abundance of aromatic compounds. Adsorption and flocculation could serve important mechanisms to remove terrestrial DOM, promoting the burial of terrestrial DOM within estuarine sediments. Besides, some terrestrial molecular formulae were also detected in the ECS, suggesting the potential contribution of terrestrial DOM to the carbon stock of open seas after experiencing physical and photochemical transformations. This research provides a comprehensive insight into spatial variations of estuarine DOM composition, underlining the important role of estuaries in sorting and transporting DOM.
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•Aliphatic compounds and peptides were enriched in the YRE.•DOM characteristics of YRE are mainly modulated by input of terrestrial DOM.•Decreased terrestrial DOM of turbidity zone could supplement organic matter to estuarine sediments.•The YRE contribute refractory terrestrial formulae to the Eastern China Sea.
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Coastal wetlands are active transitional ecotones between land and ocean, and are considered as hot spots of organic matter processing within the global carbon cycle, which dissolved organic matter ...(DOM) plays a critical role. In this study, combined use of ultrahigh-resolution mass spectrometry (FT-ICR MS) and complementary optical techniques was conducted to assess the detailed molecular composition of DOM in the temperate Liaohe coastal wetland (LCW), NE China in respect to the differences in DOM composition from surface water to sediment pore water. Significant positive correlations between salinity and dissolved organic carbon (DOC) concentrations were observed in both surface waters and pore waters. Pore water DOM is generally characterized by lower protein-like fluorescence and biological index, but higher humification and humic-like fluorescent components than those in surface water DOM. Corresponding to the optical properties, FT-ICR MS measurements show that pore water DOM has higher proportions of heteroatoms, aromaticity index, O/C ratios, unsaturated aliphatics, and peptides, but lower average H/C ratios compared to surface water DOM across locations with different marsh plant species (rice (Oryza sativa), reed (Phragmites australis), Seablite (Suaeda Salsa)) and salinity (0.5 to 51.5 psu). The results suggest that selective preservation for polyphenols, lignin degradation intermediates (highly unsaturated compounds), and microbial resynthesis of heteroatomic compounds are involved in the processing of DOM from surface water to pore water, leading to the formation of higher molecular weight and sulfur-containing molecules. The abundant CHOS compounds could be related to the early diagenetic sulfurization of DOM in sediments. Our unique data set should provide new clues for a comprehensive understanding of the molecular dynamics of DOM in coastal wetlands.
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•Different molecular compositions occur in DOM between surface and sediment pore water.•Pore water DOM contains higher heteroatomic compounds and recalcitrant material.•Surface water DOM shows higher aliphatic and lower O/C signatures.•Early microbial diagenesis contributes to the accumulation of refractory DOM in pore waters.
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Ultrasensitive and reliable conductive hydrogels are significant in the construction of human–machine twinning systems. However, in extremely cold environments, freezing severely limits the ...application of hydrogel-based sensors. Herein, building on biomimetics, a zwitterionic hydrogel was elaborated for human–machine interaction employing multichemical bonding synergies and experimental signal analyses. The covalent bonds, hydrogen bonds, and electrostatic interactions construct a dense double network structure favorable for stress dispersion and hydrogen bond regeneration. In particular, zwitterions and ionic conductors maintained excellent strain response (99 ms) and electrical sensitivity (gauge factor = 14.52) in the dense hydrogel structure while immobilizing water molecules to enhance the weather resistance (−68 °C). Inspired by the high sensitivity, zwitterionic hydrogel-based strain sensors and remote-control gloves were designed by analyzing the experimental signals, demonstrating promising potential applications within specialized flexible materials and human–machine symbiotic systems.
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•A bilayer actuator was bionically designed by imitating the structure of water lily.•An efficient actuator with a unique light/thermal response mechanism was constructed.•The smart ...soft actuator was integrated with machine recognition capability.•Multiple networks and the MXene were synergized to enhance mechanical properties.
Inspired by the natural stimulus–response of plants and animals, a range of soft equipment has been extensively developed and used in intelligent human–computer interaction, editable remote drives, and machine learning. Poly(N-isopropyl acrylamide) (PNIPAM) hydrogels have gained popularity thanks to their low phase transition temperature and excellent flexibility. However, the PNIPAM hydrogels suffer from poor mechanical properties, low electrical conductivity, and lack of self-responsiveness. Herein, a bilayer light/thermal cascaded-driven anisotropic poly acrylamide/poly(N-isopropylacrylamide-co-acrylamide)-polyvinyl alcohol-MXene (P/PP-M) actuator was prepared by a simple two-step polymerization method. The unique bionic light/thermal response mechanism enables rapid conversion of energy forms and the construction of remote editable actuators. Concretely, the mechanical properties of hydrogels (strain: 1014 %, stress: 94 KPa) have been greatly improved by copolymerizing MXene nanosheets and multiplex hydrogels through two-by-two interpenetrating molecular chains. MXene nanosheets formed dynamic networks conferring the hydrogel system with high conductivity and light/thermal conversion efficiency. The P/PP-M soft actuator features high sensitivity (Gauge factor = 3.62), fast response time (400 ms), and cycling durability (>500 cycles). Finally, the energy transfer mechanism from light to thermal energy to kinetic energy was corroborated by preparing a series of bionic equipment. Manual clips were prepared on this basis, which enables the transportation of objects and realizes the real-time reflection of the operating status of remotely driven soft manual clips through changes in electrical signals. Thus, the proposed efficient editable remote-driven machine recognition soft equipment provides new insights for developing intelligent flexible robots and wearable smart devices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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