CARBON WIRE AMPEROMETRIC FLOW THROUGH DETECTOR

A carbon wire amperometric flow through detector is described which is easily constructed at low cost for application to flow injection analysis,continuous stream analysis and liquid chromatography.The theoretical limiting current of the detector is 2.14×10~6nCD^(2/3)u_f^(1/3) with 36% actual current efficiency.By use of flow injection analysis,the detecting limits for Ag(I)and Cr(VI)had achieved 1 ppb and 0.4 ppb respectively with 1.2%(n=20)relative standard deviation after preliminary experiments.

Evaluation of Carbon and Electron Flow in Lactobacillus brevis as a Potential Host for Heterologous 1-Butanol Biosynthesis

Heterofermentative lactic acid bacterium Lactobacillus brevis may be considered as a promising host for heterologous butanol synthesis because of tolerance to butanol and ability to ferment pentose and hexose sugars from wood hydrolysates that are cheap and renewable carbohydrate source. Carbon and electron flow was evaluated in two L. brevis strains in order to assess metabolic potential of these bacteria for heterologous butanol synthesis. Conditions required for generation of acetyl-CoA and NADH which are necessary for butanol biosynthesis have been determined. Key enzymes controlling direction of metabolic fluxes in L. brevis in various redox conditions were defined. In anaerobic glucose fermentation, the carbon flow through acetyl-CoA is regulated by aldehyde dehydrogenase ALDH possessing low affinity to NADH and activity (KmNADH= 200 μM, Vmax= 0.03 U/mg of total cell protein). Aerobically, the NADH-oxidase NOX (KmNADH= 25 μM, Vmax = 1.7 U/mg) efficiently competes with ALDH for NADH that results in formation of acetate instead of acetyl-CoA. In general, external electron acceptors (oxygen, fructose) and pentoses decrease NADH availability for native ethanol and recombinant butanol enzymes and therefore reduce carbon flux through acetyl-CoA. Pyruvate metabolism was studied in order to reveal redirection possibilities of competitive carbon fluxes towards butanol synthesis. The study provides a basis for the rational development of L. brevis strains producing butanol from wood hydrolysate.

Multi-process production occurs in the iron and steel industry,supporting‘dual carbon'target:An in-depth study of CO_(2)emissions from different processes

Reducing CO_(2)emissions of the iron and steel industry,a typical heavy CO_(2)-emitting sector is the only way that must be passed to achieve the‘dual-carbon’goal,especially in China.In previous studies,however,it is still unknown what is the difference between blast furnace basic oxygen furnace(BF-BOF),scrap-electric furnace(scrap-EF)and hydrogen metallurgy process.The quantitative research on the key factors affecting CO_(2)emissions is insufficient There is also a lack of research on the prediction of CO_(2)emissions by adjusting industria structure.Based on material flow analysis,this study establishes carbon flow diagrams o three processes,and then analyze the key factors affecting CO_(2)emissions.CO_(2)emissions of the iron and steel industry in the future is predicted by adjusting industrial structure The results show that:(1)The CO_(2)emissions of BF-BOF,scrap-EF and hydrogen metallurgy process in a site are 1417.26,542.93 and 1166.52 kg,respectively.(2)By increasing pellet ratio in blast furnace,scrap ratio in electric furnace,etc.,can effectively reduce CO_(2)emissions(3)Reducing the crude steel output is the most effective CO_(2)reduction measure.There is still 5.15×10^(8)-6.17×10^(8) tons of CO_(2)that needs to be reduced by additional measures.

A Distributed Computing Algorithm for Electricity Carbon Emission Flow and Carbon Emission Intensity

The calculation of the indirect carbon emis-sion is essential for power system policy making,carbon market development,and power grid planning.The em-bedded carbon emissions of the electricity system are commonly calculated by carbon emission flow theory.However,the calculation procedure is time-consuming,especially for a country with 500-1000 thousand nodes,making it challenging to obtain nationwide carbon emis-sions intensity precisely.Additionally,the calculation procedure requires to gather all the grid data with high classified levels from different power grid companies,which can prevent data sharing and cooperation among different companies.This paper proposes a distributed computing algorithm for indirect carbon emission that can reduce the time consumption and provide privacy protection.The core idea is to utilize the sparsity of the nodes’flow matrix of the nationwide grid to partition the computing procedure into parallel sub-procedures exe-cuted in multiple terminals.The flow and structure data of the regional grid are transformed irreversibly for pri-vacy protection,when transmitted between terminals.A 1-master-and-N-slave layout is adopted to verify the method.This algorithm is suitable for large grid compa-nies with headquarter and branches in provinces,such as the State Grid Corporation of China.

The dilemma for China’s national carbon trading market:minimizing carbon abatement costs or maximizing net social benefits?

After a decade of planning and trials,China officially launched a national carbon trading in July 2021.Using a standard economic model,this study shows that an unconstrained carbon trading market would face a dilemma between minimizing pollution control costs and maximizing social benefits.We further show that this would be a significant challenge in China.Our results show that areas with higher population densities also would have higher costs for carbon reduction,and hence the polluters in those areas would be net buyers in the national market.Moreover,our analysis indicates a significantly high correlation between carbon dioxide emissions and other local pollutants.Therefore,cross-regional transactions may result in more emission of other pollutants in areas with higher population density under the unconstrained national cap-and-trade system and cause larger losses in social benefits.We call for more studies to address the issue.

Assessing urban low-carbon performance from a metabolic perspective

How to mitigate anthropogenic carbon emissions in cities determines to a large degree whether global temperature targets in this century are to be met.Using 12 cities in or outside China as case studies,we quantified the critical processes of carbon metabolism based on the urban carbon metabolism assessment framework(CMAF)proposed.The differences of sector contribution,and per capita and intensity among carbon throughflows,carbon inflows and carbon emissions were evaluated.Furthermore,we established an indicator system for CMAF consisting of flow-based and structural indicators to compare the low-carbon performances of cities.The results showed that the total carbon throughflow(TCT)and total carbon inflow(TCI)in Chinese cities were 7–12%higher than in European and American cities regarding the manufacturing and services sector on average,but 6–9%lower in the household consumption sector.Beijing,Tianjin,Nanjing and Guangzhou had lower per capita TCT and TCI than in European and American cities such as Paris and Los Angeles,while their carbon intensities were about three times as much.The per capita TCT in a city was found significantly correlated with per capita energy consumption and had a certain correlation with per capita building or housing area.This study found that TCT,TCI and carbon dioxide emission each provided unique information to measure the potential climatic impact of cities.The difference in the ranking of low-carbon performance between the investigated cities was significant both in terms of flow-based and structural indicators.We suggest these assessment indicators of carbon metabolism be integrated into urban resources management to reflect both the decarbonization status and future emission reduction potential more accurately and to provide systemic decision support for achieving the goal of carbon neutrality in cities.

Research on low carbon management using a scientific classification method

This research is aimed at the rapid development of a low-carbon economy, in which we propose the classification and application of relevant management measures to affect the development of environmental management ideas and measures of the low-carbon economy, which we called as low carbon management measures. According to scientific analysis of the lowcarbon economy, we can divide low-carbon management measures into three parts： measures for reduction of carbon sources, carbon flow planning, and increase of carbon sinks. Furthermore, we list the advantages that China can utilize to develop its own low-carbon management measures. In the end, necessary adjustments to environmental management measures in China can be made according to this scientific classification.

Influence of co-solvent hydroxyl group number on properties of water-based conductive carbon pastes

A series of water-based conductive carbon pastes were prepared by wet ball milling, followed by vacuum defoaming using isopropyl alcohol, propylene glycol or glycerin as co-solvents. Screen printing was then used to prepare conductive patterns. To determine the influence of co-solvent hydroxyl group number on the properties of water-based conductive carbon pastes, the rheological properties of the pastes and the surface morphologies and conductivities of the printed patterns were characterized. The results show that paste viscosity increased with the number of hydroxyl groups and the latter also affected thixotropy. In addition, the boiling points and surface tensions of the co-solvents increased consistently with hydroxyl group number, affecting the hydrodynamic flow. The conductive carbon paste created using propylene glycol as a co-solvent was the best for screen printing because of its weak coffee-ring effect and appro- priate rheological properties, resulting in a smooth coating surface and uniform deposition of the fillers. The resistivity of the pattern printed using paste PG, containing the closest packing of conductive carbon black particles, was 0.44 Ω cm.

Carbon flow analysis of China＇s agro-ecosystem from 1980 to 2013： A perspective from substance flow analysis

Research on carbon cycling has attracted attention from both scientists and policy-makers. Based on material flow analysis, this study systematically budgets the carbon inputs, outputs and balance from 1980 to 2013 for China＇s agro-ecosystem and its sub-systems, including agricultural land use, livestock breeding and rural life. The results show that from 1980 to 2013, both the carbon input and output were growing gradually, with the carbon input doubling from 1.6 Pg C/year in 1980 to 3.4 Pg C/year in 2013, while carbon output grew from 2.2 Pg C/year in 1980 to 3.8 Pg C/year in 2013. From 1980 to 2013, the crop production system in China has remained a carbon source, and the agricultural land uses were also almost all carbon sources instead of carbon sinks. As soil carbon stock plays a very important role in deciding the function of China＇s agro-ecosystem as a carbon sink or source, practices that can promote carbon storage and sequestration will be an essential component of low carbon agriculture development in China.

Evaporation-driven water flow induced electricity from porous carbon film

Subject code:E02 With the support by the National Natural Science Foundation of China,a collaborative study by the research group led by Prof.Zhou Jun(周军)from Wuhan National Laboratory for Optoelectronics,Huazhong University of Science and Technology,Prof.Guo Wanlin(郭万林)from Nanjing University

Adaptive strategies of high and low nucleic acid prokaryotes in response to declining resource availability and selective grazing by protozoa

Prokaryotes play a fundamental role in global ocean biogeochemical cycles.However,how the abundance and metabolic activity of ecologically distinct subgroups(i.e.,high nucleic acid(HNA)and low nucleic acid(LNA)cells),and their regulating factors,change in response to changing marine environmental conditions remains poorly understood.Here,we delved into the time-evolving dynamic responses of the HNA and LNA prokaryotic subgroups to declining resource availability and selective grazing by protozoa by conducting a 73-day incubation experiment in a large-volume(117,000 L)macrocosm that facilitates community-level exploration.We found that the metabolic activity of the HNA subgroup was higher than that of the LNA subgroup when the macrocosm was resource replete but that the HNA subgroup declined more rapidly than the LNA subgroup as the resources became increasingly scarce,leading to a steadily increasing contribution of LNA cells to prokaryotic activity.Meanwhile,as resources in the macrocosm became limited,protozoan grazing preference shifted from the HNA to the LNA subgroup and the contributions of the LNA subgroup to the carbon flow within the macrocosm increased.The findings highlight the resilience of LNA cells in resource-limited environments,illuminate the critical role of selective grazing by protozoa in balancing distinct prokaryotic subgroups under changing resource conditions,and demonstrate the complex and adaptive interactions between protozoa and prokaryotes across diverse environmental contexts.

Fluid Inclusion and Geochemistry Studies of Calcite Veins in Shizhu Synclinorium,Central China:Record of Origin of Fluids and Diagenetic Conditions

Calcite veins in carbonate fracture have been investigated by petrographic, fluid inclusion, geochemical analyses and coupled with basin modeling techniques to provide useful insights into fluid activity and deformation conditions of the Cambrian to Triassic Shizhu synclinorium from the western region of Mid-Yangtze, central China. The results of the fluid inclusion microthermometry show a wide range of homogenization temperatures（78.6–215.5 °C） and salinities（0.18–23.11 wt.% NaCl equivalent）, indicating the formation under diverse fluid conditions. All the calcite veins have negative Ce anomalies, which are the typical characteristic of marine carbonate sediments; it is therefore plausible that calcite veins were precipitated from the marine basin fluid. The stable carbon isotopic compositions of calcites（δ^（13）CV-PDB=-2.5‰–4.26‰） and host limestones（δ^（13）CV-PDB=-3.56‰–5.80‰） are very similar with a correlation coefficient of 0.86, however, four calcites from the Lower Permian and Lower Triassic show lower δ^（13）C values relative to the host limestones, and they are depleted in total REE concentrations（∑REE ratio varies from 0.74 to 2.06）, suggesting the derivation of dissolved carbon from marine carbonates hosting the calcite veins and, less commonly, from the degradation of organic matter. Calculated δ^（18）O of the fluids-precipitating calcites（δ^（18）OV-SMOW=-0.41‰–14.42‰）, ^（87）Sr/^（86）Sr ratios varying in the range of coeval seawater and the distinct REE pattern simultaneously suggest calcite-forming fluids in each stratigraphic unit could have formed from the involvement of fluids that originated from coeval seawater and evolved through different degrees of water rock interaction. However, the presence of more radiogenic ^（87）Sr/^（86）Sr ratios than coeval seawater and pronounced positive Eu anomalies in calcites of Lower to Middle Ordovician rocks indicate that terrestrial input from upper strata mudstone and siliciclastic rocks could be involved in the precipitation of the Ordovician calcite. Fluid-inclusion data combined with burial and thermal history modeling indicate there was large-scale flow of evolved basinal fluids through the carbonate formation fractures spanning a time frame from 135 to 50 Ma（Early Cretaceous–Eocene）. Therefore, the geochemical characteristics of calcite veins can provide the basis for deformation events in Late Yanshanian and Early Himalayan orogeny.

Compact fluidized bed sorber for CO_2 capture

Multiphase CFD is used to design a compact fluidized bed sorber for CO2 removal from flue gases using sodium or potassium carbonate pellets. The sorber sizes are much smaller than commercial amine absorbers and smaller than other proposed dry adsorbers. The size reduction is due to the elimination of dilute regions that cause bypassing. With proper solids feeding we eliminated the usual core-annular regime found in circulating fluidized beds.