Increase In Reduction Rate Research Articles

Refinement of coarse AlN by the shear effect of dislocation slip during cold rolling in low-temperature grain-oriented silicon steel

The transition behavior of coarse AlN during cold rolling in the low-temperature grain-oriented silicon steel normalized sheet was investigated using field emission scanning electron microscopy (SEM) and field emission transmission electron microscopy (TEM). The SEM observation results showed that the size of AlN decreased with the increase of the cold rolling reduction rate, and the average sizes of AlN in the normalized specimen and the cold-rolled specimens with the cold rolling reduction rates of 14%, 23%, 30%, 40%, and 89% were approximately 1734, 771, 742, 582, 490, and 96 nm, respectively. The morphology of AlN nearly transformed from rectangle to irregular polygon when the cold rolling reduction rate exceeded 23%. Meanwhile, the mechanism of the refinement of AlN during cold rolling was characterized by TEM. The high-resolution transmission electron microscopy (HRTEM) analysis results confirmed that the refinement of coarse AlN during cold rolling was caused by the shear effect of dislocation slip because lots of slip traces, which were produced by dislocation slip along some slip systems of AlN, such as (011‾0)[21‾1‾0], (01‾11)[21‾1‾0], and (0001)[21‾1‾0] slip systems, were observed in AlN. Moreover, it was also found that after a coarse AlN was sheared to become two parts, the orientations of them would be slightly different when the slip plane of AlN was not completely parallel to that of the matrix before shearing. Therefore, based on these results, it was confirmed for the first time that the coarse AlN precipitated in low-temperature grain-oriented silicon steel normalized sheet was shearable and could be refined after cold rolling. The possible mechanisms were summarized as follows: the orientation relationship between AlN and matrix might be randomly changed during cold rolling owing to the considerable stress concentration around AlN, making it possible that the slip plane of AlN matched with that of the matrix, at this time, the dislocations slipping in the matrix could glide into and shear AlN with the slip system of matrix changing into the slip system of AlN.

Microtexture and Rolling Deformation Behavior Analysis of the Formation Mechanism Fe3O4 at the Interface Formed on Hot-Rolled High-Strength Steel

In order to better understand the formation mechanism of tertiary oxide scale in high-strength steel during hot rolling, the microtexture of the oxide layer has been characterized and analyzed by the electron backscatter diffraction (EBSD) method. The results show that the Fe3O4 phase in the oxide layer has a two-phase heterogeneous morphology, Fe3O4 in the oxide layer comprises columnar grains, and Fe3O4 near the substrate comprises spherical grains. As the reduction rate increases, the Fe2O3 layer is gradually wedged into the surface of the Fe3O4 layer. Fe3O4 forms a <110> fiber texture at a reduction rate of 10%. The inner layer of the oxide scale comprises spherical grains, and Fe3O4 is preferentially nucleated and precipitated in the direction of Fe surface grains <110> texture. With the increase in the reduction rate, the {112}<−1−21> directional slip system shows the lowest Schmidt factor value, so the grains with a low Schmidt factor exhibit higher stored strain energy. The formation of the spherical Fe3O4 seam layer close to the steel matrix is the result of the combined effect of the stress state at the matrix and ion diffusion.

Study on influence characteristics of shield tunnel depth and spacing on settlement in clay strata

The surrounding ground disturbance and surface settlement induced by shield construction are the key problems of tunnelling control and necessary to be studied. Taking the shield tunnel project of Beijing Subway Line 14 as the research background, this paper studies the influence of tunnel spacing and depth on surface settlement distribution by numerical simulation method, and analyzes the relationship between the two factors and maximum settlement. The results indicate that the increase of tunnel depth or tunnel spacing leads to the decrease of the maximum settlement and the settlement reduction rate increases. With the increase of tunnel depth, the settlement trough presents approximately symmetrical distribution, and the symmetry axis is inclined to the first tunnel. With the increase of tunnel spacing, the superposition effect of twin tunnel excavation decreases, and the settlement trough transits from U-shaped to W-shaped with the maximum settlement decreasing relatively from single peak to double peaks. Also, the tunnel depth or spacing is highly correlated with the maximum settlement in a certain range, and the tunnel depth has a stronger linear correlation than the tunnel spacing. The research results provide certain theoretical guidance and references for the prediction of ground deformation and settlement control of shield construction.

Numerical simulation and experimental study of heat and mass transfer in cylinder-like vegetables during vacuum cooling

Vacuum cooling is an established technology widely applied on the processing of harvested vegetables. For the purpose of investigating heat and mass transfer in vacuum cooling of cylindrical vegetables, a mathematical model was established and eggplants were selected as research target. Comparison of simulated and experimental data was conducted for the validation of the mathematical model. Additional simulation was carried out to study the influence of pressure reduction rate on the temperature variation. The results show that the maximum error of temperature and weight loss are 14.2% and 18.3%. It is also found that temperature difference tends to be smaller when the pressure reduction rate increases. Data obtained from the simulation are consistent with experimental value, and the present study on influence of pressure reduction rate is helpful to the optimization of vacuum cooling process.

Thermodynamic analysis of chromium reduction from oxide Cr<sub>2</sub>O<sub>3</sub>

Thermodynamic analysis of chromium reduction from its oxide in gas phase Н2 – Н2О – СО – СО2 in contact with carbon was performed. Oxidation potential (pO2 ) was determined by two nomograms in the coordinates and taking into account condition normalizations xH2O + xH2 + xCO2+ xCO = 1. In calculations, possible parameters of reduction of chromium from Cr2O3 oxide were determined by ratio of dissociation elasticity of the oxide and oxidation potential of the gas phase. In the СО – СО2 – С system, chromium is reduced at temperature of 1505 K if xCO > 0.9995. At this temperature, Cr2O3 compound is reduced in water gas of the following composition xH2 = 0.0186, xH2O = 0.28·10–4, xCO = 0.9809, xCO2 = 4.86·10–4, for which the oxidation potential is equal to dissociation elasticity of oxide With an increase in hydrogen concentration from 0.0186 to 0.99, oxidation potential of water gas in contact with carbon decreases by four orders of magnitude to This should lead to a significant increase in reduction rate. In such a gaseous atmosphere, it is possible to reduce chromium at temperature of 1230 K. It is technologically simple to obtain reducing water gas and at the lowest cost, for example, by heating water vapor in contact with carbon. It is shown that at temperature of 1500 K water gas is obtained with traces of Н2О and СО2 compounds with parameters xH2 = 0.4999, xCO = 0.4996, Oxidizing potential of such a gas is less than that of chromium oxide, and this difference significantly increases with increasing temperature.

The Effect of Manganese Ore Iron Content on Carbothermic Reduction Rates at Low Temperatures

Extensive studies on the carbothermic reduction of manganese ores from the Kalahari Manganese Field (KMF) in South Africa illustrated an increase in reduction rates with increased iron content in the ore (as oxides). This observation is most noticeable in stage two reduction, ranging from approximately 33% to 70% reduction at temperatures of 1200°C - 1350°C. These studies illustrated the complex mineralogy changes which occur as the ore reduction process proceeds. Manganese ore reduction is complex at intermediate reaction temperatures of 1100°C - 1400°C due to the formation of liquid oxide and/or alloy phases in varying phase proportions and distributions. The results prompt the question: how important is increased iron content in manganese ores in setting low temperature ore reduction rates, both for manganese ores of different mineralogy, and also within the same type of manganese ore? This important aspect is explored in this work by considering both literature evidence and reporting results from simplified experiments which simulate increased iron content in MnO-Fe-C mixtures. The MnO-Fe-C mixtures serve as a simplified reaction system because liquid oxide formation is excluded, allowing the work to be focused on alloy phase formation and its effect on MnO reduction. Furthermore, the results illustrate how the MnO reduction rate equation may be updated to incorporate the effect of manganese ore iron content.

How Do International Trade Shocks Propagate Through Domestic Supply Chains? Connecting World Input-Output Tables and Firm-Level Supply Chain Data

This study shows how import and export shocks propagate through domestic supply chains by using actual Japanese supply chain data and a world input-output table based on firm-level agent-based simulations. We propose three different models to connect the domestic firm-level supply chain to the world input-output table. Then, we estimate the value-added losses of Japanese firms caused by shocks of different magnitudes and durations originating in China, in the EU and US, and globally. The losses caused by Chinese and European and US shocks are comparable to those caused by global shocks, which indicates the importance of China and the EU and US for Japanese supply chains, although their trade volumes are 21.2% and 25.9%, respectively. The volume and the rates at which losses increase are very different across the connection models, which indicates that the assignment of international connections to firms matters greatly and that it is not appropriate to make naive assumptions, such as that sectoral-level supply chain models are equivalent to firm-level supply chain models. The losses increase sublinealy as the duration expands, which indicates that the shock propagation ultimately saturates the economy. The speeds of saturation differ substantially depending on the assignment of international connections. Finally, the losses increase superlinearly as the initial reduction rate increases. This is because there is a greater probability of one supplier being replaced by other suppliers if the reduction is smaller.

Tailoring Carbon Nanotubes to Enhance their Efficiency as Electron Shuttle on the Biological Removal of Acid Orange 10 Under Anaerobic Conditions.

Anaerobic treatments have been described for the biodegradation of pollutants. However, the reactions proceed slowly due to the recalcitrant nature of these compounds. Carbon nanomaterials (CNM) intermediate in, and favor, the electron transfer, accelerating the anaerobic reduction of pollutants, which act as final electron acceptors. In the present work, different carbon nanotubes (CNT) with modified surface chemistry, namely CNT oxidized with HNO3 (CNT_HNO3) and CNT doped with nitrogen in a ball milling process (CNT_N_MB) were prepared using commercial CNT as a starting material. The new CNM were tested as redox mediators (RM), 0.1 g L−1, in the biological reduction of the azo dye, Acid Orange 10 (AO10), with an anaerobic granular sludge, over 48 h of reaction. Methane production was also assessed to verify the microorganism’s activity and the CNM’s effect on the methanogenic activity. An improvement in the biological removal of AO10 occurred with all CNM (above 90%), when compared with the control without CNM (only 32.4 ± 0.3%). The best results were obtained with CNT_N_MB, which achieved 98.2 ± 0.1% biological AO10 removal, and an 11-fold reduction rate increase. In order to confer magnetic properties to the CNM, tailored CNT were impregnated with 2% of iron-samples: CNT@2%Fe, CNT@2%Fe_N_MB, and CNT@2%Fe_HNO3. The better performance of the CNT doped with nitrogen was confirmed with CNT@2%Fe_N_MB, and the magnetic character facilitated its recovery after treatment, and did not affect its good catalytic properties. No dye removal was observed in the abiotic assays, so the removal was not due to adsorption on the CNM. Furthermore, the microorganism’s viability was maintained during the assay and methane production was not affected by the presence of the CNM. Despite the toxic character of the aromatic amines formed, detoxification was observed after the biological process with thermally treated CNT.

Increase in CO2 reduction rate via optical near-field effect

To reduce the effects of global warming, visible and near-infrared light must be used more efficiently. Deep ultraviolet light (8 eV) is required for the direct dissociation of CO2 by light; however, the introduction of a metal complex has made it possible to realize CO2 reduction with visible light. We demonstrate that the optical near field (ONF) can increase the CO2 reduction rate. For this, we used gold clusters, because they can be a suitable source for ONFs, as their size and density can be controlled by the number of gold atoms. By attaching a metal complex near gold clusters with diameters of 1.0 to 1.3 nm, we confirm that the reduction rate of CO2 to CO increased by 1.5 to 2.1 times. The gold clusters were sufficiently small; therefore, there was no plasmonic resonant peak or heat generation. Because the near-field effect is based on a photochemical reaction, it can be applied to other metal complexes used in CO2 reduction, and it has other applications such as water splitting and water purification.

Sonochemical Catalyst Synthesis for HER and OER

Improvements on catalysts for electrochemical energy conversion is highly important if technologies such as fuel cells and electrolyzers are to become economically viable in the future. These improvements typically lie in the optimization of the catalyst’s particle size and available surface area, which means that nucleation and growth conditions during the synthesis must be controlled precisely. Common ways of producing such catalysts today involve chemical reduction methods were reducing agents like NaBH4 or ethylene glycol are used to reduce metal salts to their metallic state [1]. Even though such methods are fast and scalable, few ways are available for careful control over the nucleation and growth of the nanoparticles.To allow for better control over the nucleation and growth of nanoparticles, a sonochemical synthesis method can be employed instead [1]. In sonochemistry, high power ultrasound is applied to an aqueous metal precursor solution resulting in the formation of H-radicals and OH-radicals in the cavitation bubbles [1]. The highly reactive radicals will diffuse into the solution and reduce the metal ions to metallic nanoparticles. The nucleation and growth conditions can therefore simply be manipulated by controlling the rate of radical formation which is directly related to the ultrasound parameters. Several studies have found that the radical formation rate (or the metal reduction rate) is affected by the ultrasound frequency [2][3], ultrasound power [3], solution temperature [3], types of dissolved gasses [3], types of alcohols used [4], and types of surfactants used [5]. The ease of changing these parameters therefore ensures that nanoparticles of optimal sizes can be produced.In this project we have started to investigate exactly how ultrasound parameters influence the radical formation rate in aqueous systems. This information can therefore be used to synthesize electrocatalysts optimized for HER and OER. Initial investigations of how Ni- and Fe -precursors are affected by ultrasound have also been performed. Sonochemical assisted synthesis of NiFe nanoparticles with NaBH4 was also assessed as a potential hybrid solution.The results from the investigations of the ultrasound parameters suggested that the addition of ethanol effectively leads to a scavenging of the primary radicals in the solution. Consequently, more radicals become available for reducing metal ions, and the reduction rate increases. Higher ultrasonic power and lower ultrasonic frequency (580 kHz was the lowest frequency used in the experiment) increase the radical formation, which is supported by previous findings [2][3]. The effect of dissolved gasses showed that O2 saturation gave the highest radical yield. However, this can be traced to the sonolysis of O2 itself which lead to additional radical formation from the dissolved gas, and not just from the water vapor in the cavitation bubbles [3]. The ideal solution temperature was found to be dependent on the type of dissolved gas, with Ar exhibiting a higher ideal temperature than O2.The initial investigations of Ni- and Fe-precursors showed that the sonochemical reduction was not appreciable in the short time frame which was used (30 min). Longer sonication times will be attempted in future works.For the sonochemical assisted synthesis, NaBH4 was added as a reducing agent to aid the reduction, and an ultrasonic bath was used as the ultrasound source (42 kHz). Physical characterization of the resulting particles showed a significant decrease in the particle size due to the application of ultrasound. However, these changes were attributed to the mechanical effects most dominant at lower ultrasonic frequencies. Similar experiments will be attempted at higher frequencies to observe if the chemical effects of ultrasound act similarly.References Bruno G. Pollet. “The use of ultrasound for the fabrication of fuel cell materials”. International Journal of Hydrogen Energy 35.21 (2010). VIII symposium of the Mexican Hydrogen Society, pp. 11986–12004K Okitsu et al. “Sonochemical synthesis of gold nanoparticles: effects of ultrasound frequency”. The journal of physical chemistry. B109.44 (2005), p. 20673S Merouani et al. “Sensitivity of free radicals production in acoustically driven bubble to the ultrasonic frequency and nature of dissolved gases”. Ultrasonics – Sonochemistry 22.2 (2015), pp. 41–50Rachel A Caruso et al. “Sonochemical formation of colloidal platinum”. Colloids and Surfaces A: Physicochemical and Engineering Aspects 169.1-3 (2000), pp. 219–225K Okitsu et al. “Sonochemical preparation of ultrafine palladium particles”. Chemistry of Materials (USA) 8.2 (1996), pp. 315–317

A Case Study on Energy Consumption and Calibration of Green Remodeling Buildings

Ministry of Land, Infrastructure and Transport (MOLIT) has increased reduction rate from 18.1% to 32.7% in Building sector compared to BAU of the national greenhouse gas emission according to the 2030 Greenhouse Gas Reduction Road map Amendment. For this purpose, MOLIT has been activating the green remodeling projects for existing buildings. Considering that 15 year old buildings after completion are 74% (5.25 million buildings) among about 7 million existing building stocks in Korea, reduction of building energy consumption by green remodeling is urgently needed, However, it is a major difficulty of activation for green remodeling projects because there are few case studies on Before and After building energy consumption of actual green remodeling projects. Considering that building energy performance and value increase after green remodeling through previous researches, additional studies of the energy consumption assessment on actual green remodeling projects are essential. Therefore, this study aims to propose results on Before and After building energy consumption of actual green remodeling projects.

Effect of different concentration of functionalized graphene on charging time reduction in thermal energy storage system

Abstract The experimental work was carried out on the thermal energy storage system to test the thermal performance with the use of carboxyl functionalized Graphene (–COOH) doped with phase change material (Paraffin wax). The volume concentrations were varied from 0.25 to 1% at an increment of 0.25%. The HTF (Heat transfer fluid) which was water had its temperature varied between 80 °C and 90 °C at a 5 °C interval and the flow rate of water (HTF) was kept as 12.5 ml/sec or 50 ml in 4 s. In this experiment charging time reduces with increase of the Graphene concentration in terms of vol%. This research also included measuring nanofluid thermal properties at varying concentration and inlet temperature of HTF. Based on research from the experiments. It is observed that, due to an increase in thermal conductivity, the charge time reduction rate increase by up to 20% to 30% because of variance in the HTF inlet temperature when used with doped PCM material. Better performance metrics such as charging power, greater overall efficiency and increased energy amount are all recorded. When the charging time is reduced by 30% to 50% using the nanomaterial in PCM at 1 vol%, the large amount of energy was stored in the short duration of the time.

Effect of Ag/ZnO-Graphitic Carbon Nitride on Antimicrobial Activity under Visible Light

Zinc oxide-graphitic carbon nitride (ZnO/g-C3N4) composites were synthesized by precipitation method in order to improve photocatalytic activity under visible light. To enhance antimicrobial activity, silver was added into zinc oxide-graphitic carbon nitride (Ag/ZnO/g-C3N4). Ultrastructures of the composite were analyzed by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Photocatalytic activity of the composites was carried out by degradation of methylene blue solution as a function of contact time. The results revealed that ZnO/g-C3N4 was capable of dye degradation at 96.65%. Addition of Ag into ZnO/g-C3N4 resulted in increase of dye reduction rate. For antibacterial test, Ag/ZnO/g-C3N4 exhibited bactericidal activity against Pseudomonas aeruginosa and Bacillus cereus. For antifungal test, Ag/ZnO/g-C3N4 showed resistance to Aspergillusniger for 7 days. Ag/ZnO-g-C3N4 composite exhibited better photocatalytic and antimicrobial activities compare to ZnO and g-C3N4. These results indicate that precipitation method is a cheap, rapid and efficient method that can be used to synthesize Ag/ZnO-g-C3N4 composites. For further studies, applications of this Ag/ZnO-g-C3N4 composites in microbiological and agricultural fields will be carried out.

Nitrogen availability influences microbial reduction of ferrihydrite-organic carbon with substantial implications for exports of iron and carbon from peatlands

While iron (Fe) has been proposed to constrain dissolved organic carbon (DOC) export by forming precipitation (Fe-OC) in peatlands, uncertainties remain about the potential interactions between Fe and nitrogen. Such interactions are important for Fe and carbon exports as they can dissolve the Fe-OC through Fe reduction. Here we studied the reduction of ferrihydrite-OC (Fh-OC) following incubation with microbes from agricultural and natural peatlands under differing nitrogen availability, with high-throughput sequencing to identify microbial mechanisms. Our results showed that in agricultural peatlands, high nitrogen levels (>100 mg kg−1) modified the composition and abundance of iron-reducing bacteria, increasing reduction rates of Fh-OC (0.09–0.20 kg Fe day−1 ha−1) above the low N treatments (<100 mg kg−1) (p < 0.05). However, reduction rates of Fh-OC and iron-reducing community in natural peatlands were far less affected. Our findings suggest that N-induced microbial reduction of Fe-OC may create the potential for greater Fe and carbon exports from agricultural peatlands to aquatic systems.

Reduction and carburization of iron oxides for Fischer–Tropsch synthesis

Abstract The activation of iron oxide Fischer–Tropsch Synthesis (FTS) catalysts was investigated during pretreatment: reduction in hydrogen followed by carburization in either CO or syngas mixture, or simultaneously reduction and carburization in syngas. A combination of different complementary in situ techniques was used to gain insight into the behavior of Fe-based FTS catalysts during activation. In situ XRD was used to identify the crystalline structures present during both reduction in hydrogen and carburization. An increase in reduction rate was established when increasing the temperature. A complete reduction was demonstrated in the ETEM and a grain size dependency was proven, i.e. bigger grains need higher temperature in order to reduce. XPS and XAS both indicate the formation of a small amount of carbonaceous species at the surface of the bulk metallic iron during carburization.

Fracture criterion for predicting edge-cracking in Hot rolling of twin-roll casted AZ31 Mg alloy

Edge-cracking as one of main defects for rolled Mg alloy sheets is inevitable due to the combined characteristics of the material and process. This study aims to quantitatively analyze the damage distributions induced by rolling deformation in transverse direction (TD) for twin-roll casted (TRCed) AZ31 Mg alloy, and optimize the Freudenthal fracture criterion to predict the crack initiation and propagation during the hot rolling. FEM simulations and laboratory experiments of edge-cracking behaviors during the rolling process were carried out at temperatures of 250∼400 °C and reduction rates of 30%∼45%. Overall cracking indexes, including temperature- and reduction-dependent transverse depth of edge-cracking, distributions of damage based on the Freudenthal criterion, and critical damage values to fracture were discussed. Results show that the fracture mode of edge cracks is dominated by 45° crossed shear cracking in the longitudinal (RD–ND) section of rolled sheets, and the cracking depth along the TD increases as the rolling temperature decreases and reduction rate increases. The transverse damage decreases linearly from the edge to the interior during the rolling when using the Freudenthal criterion, which can be attributed to the combined effects of temperature difference and effective stress difference along the TD. The critical damage value of Freudenthal criterion was successfully obtained for establishing the criterion for edge-cracking prediction in AZ31 Mg alloy rolling, which is within the range of 0.59∼0.88 and has a clear linear relationship with Ln(Zener-Hollomon parameter, Z).

Improvement of Drag Reduction for Water Flow in Pipe Based Nanofluid

In the present work, the effect of Nano fluids as drag reducing agents for water flowing in pipelines was studied. Tap water was chosen to be the tested liquid and the Nano fluid was a dilute solution of water and titanium dioxide (TiO2) Nano particles which was used at five different concentrations (50, 100, 150, 200, and 250) ppm. The test section of the experimental setup consisted of a stainless steel pipe of 29.6 mm I.D (DN25) and 1.2 m long. Water was pumped with eight different flow rates (1.0 - 8.0 m3/hr) through the pipe at room temperature (35±1) o C. The effect of the nano particle concentration and the flow rate (or Reynolds number) on percentage drag reduction (%Dr) and flow rate increases (%FI) was examined. Generally, a gradual increase of %Dr &amp;%FI was observed with increasing the NP concentration and bulk velocity. The highest TiO2 concentration of 250 ppm and Re.No. of 106230 offered the maximum drag reduction which was 29.7%. Friction factors were also calculated from experimental data. Their values for pure water transported lies near or at Blasuis asymptote. While by introducing the additives, their values were positioned below Blasuis asymptotes towards Virk maximum drag reduction asymptotes.

CO2 reduction in a microchannel electrochemical reactor with gas-liquid segmented flow

Abstract Electrochemical CO2 reduction is suffered from mass transfer limitation at high current densities, owing to the low carbon dioxide concentration over the surface of the catalyst. To enhance mass transfer, a novel annular microchannel electrochemical reactor was established, which consists of a cylindrical cation exchange membrane at the outside and an oxide-derived Cu foam rod as the electrode in the middle. The results show that, due to the enhanced gas–liquid mass transfer of CO2 in the channel, the limiting current density can increase by 49.3% from 6.7 mA cm−2 to 10.0 mA cm−2 and CO2 reduction rate increase by 55.3% from 21.5 × 10−9mol s−1 cm−2 to 33.4 × 10−9mol s−1 cm−2, compared when Cu electrode is in the open space. It further shows the limiting current density is influenced by the annulus channel width and gas–liquid ratio, and width of 1 mm gives the best performance at a gas–liquid ratio of 2:1. This work demonstrates the great potential of utilizing microchannel to intensify the mass transfer for efficient electrochemical CO2 reduction.

Electrogenic sulfide oxidation mediated by cable bacteria stimulates sulfate reduction in freshwater sediments.

Cable bacteria are filamentous members of the Desulfobulbaceae family that oxidize sulfide with oxygen or nitrate by transferring electrons over centimeter distances in sediments. Recent studies show that freshwater sediments can support populations of cable bacteria at densities comparable to those found in marine environments. This is surprising since sulfide availability is presumably low in freshwater sediments due to sulfate limitation of sulfate reduction. Here we show that cable bacteria stimulate sulfate reduction in freshwater sediment through promotion of sulfate availability. Comparing experimental freshwater sediments with and without active cable bacteria, we observed a three- to tenfold increase in sulfate concentrations and a 4.5-fold increase in sulfate reduction rates when cable bacteria were present, while abundance and community composition of sulfate-reducing microorganisms (SRM) were unaffected. Correlation and ANCOVA analysis supported the hypothesis that the stimulation of sulfate reduction activity was due to relieve of the kinetic limitations of the SRM community through the elevated sulfate concentrations in sediments with cable bacteria activity. The elevated sulfate concentration was caused by cable bacteria-driven sulfide oxidation, by sulfate production from an indigenous sulfide pool, likely through cable bacteria-mediated dissolution and oxidation of iron sulfides, and by enhanced retention of sulfate, triggered by an electric field generated by the cable bacteria. Cable bacteria in freshwater sediments may thus be an integral component of a cryptic sulfur cycle and provide a mechanism for recycling of the scarce resource sulfate, stimulating sulfate reduction. It is possible that this stimulation has implication for methanogenesis and greenhouse gas emissions.

Optimal Decisions for Two Risk-Averse Competitive Manufacturers under the Cap-and-Trade Policy and Uncertain Demand

With the increasingly serious problem of environmental pollution, reducing carbon emissions has become an urgent task for all countries. The cap-and-trade (C&T) policy has gained international recognition and has been adopted by several countries. In this paper, considering the uncertainty of market demand, we discuss the carbon emission reduction and price policies of two risk-averse competitive manufacturers under the C&T policy. The two manufacturers have two competitive behaviors: simultaneous decision making and sequential decision making. Two models were constructed for these behaviors. The optimal decisions, carbon emission reduction rate, and price were obtained from these two models. Furthermore, in this paper the effects of some key parameters on the optimal decision are discussed, and some managerial insights are obtained. The results show that the lower the manufacturers’ risk aversion level is, the higher their carbon emission reduction rate and utilities. As the carbon quota increases, the manufacturers’ optimal carbon reduction rate and utilities increase. Considering consumers’ environmental awareness, it is more beneficial for the government to reduce the carbon quota and motivate manufacturers’ internal enthusiasm for emission reduction. The government can, through macro control of the market, make carbon trading prices increase appropriately and encourage manufacturers to reduce carbon emissions.