CFD study of self-cleaning system of multi-stage tangential roller threshing unit for precise buckwheat breeding.

Buckwheat is a globally recognized, nutritionally rich crop with robust adaptability, serving as a multi-purpose plant for its health benefits. Achieving precise and mechanized plot seed harvesting is a critical step in obtaining accurate results in breeding experiments. However, plot breeding requires no seed retention, no mixing, and ensures no accumulation of seed in the threshing unit. A self-cleaning technology was developed to prevent seed retention, mixing, and accumulation in the multistage tangential cylinder threshing unit. The newly designed cleaning system has five air inlets and a centrifugal fan for pneumatic cleaning. CFD simulations were conducted for each inlet position, coupled with four varying inlet velocities and the rotation speed of the main threshing cylinder. During the post-processing stage of the CFD modeling, a line consisting of fifty points was drawn beneath the threshing drums, and the air velocity at these points was recorded. The optimal configuration of inlet position, inlet air velocity, and main threshing drum rotation speed for efficient cleaning was identified based on the ratio of points beneath the drums where the airflow speed surpassed the suspension speed of buckwheat to the points where the airflow speed was lower than the suspension speed of buckwheat. The optimal configuration for "inlet_1" was identified based on the suspension velocity of buckwheat grain, with an inlet velocity of 4 m/s and a main threshing drum speed of 450 rpm.

Improving the electrochemical characteristics and performance of a neutral all-iron flow battery by using the iron reduction bacteria.

At present, the all-iron redox flow batteries (RFBs) have greater application potential due to high accessibility of electrolytes compared to traditional RFBs. Meanwhile, although electroactive bacteria can accelerate the electrons transfer, their potential to improve the performance of RFBs has been overlooked. Previously, we had confirmed that ferrous-oxidizing bacteria (FeOB) could enhance the performance of an all-iron RFB, therefore we conducted several batch experiments and chronopotentiometry experiments by using the ferric-reducing bacteria (FeRB) or mixed culture (FeOB and FeRB) to demonstrate whether they have the same or stronger effects on Fe3+-DTPA/Na4[Fe(CN)6] RFB. The results showed that the experimental reactors could achieve higher charging current density and initial cathodic potential during constant voltage charging process. The electrochemical impedance spectroscopy data and cyclic voltammetry curves demonstrated that the polarization impedance increased slower and reduction peak potential of experimental groups also emerged a positive shift compared to CK. According to chronopotentiometry experiments results, the microbes could function at maximum 0.3 M, 12 mA/cm2, and also improved the charging specific capacity. Combined the SEM pictures and microbial composition analysis, the main functional electroactive FeRB were Alcaligenes, Corynebacterium and Bacillus, which indicated to have important potential in improving the performance of RFBs.

Enhanced Microbial Protein Production from CO2 and Air by a MoS2 Catalyzed Bioelectrochemical System.

Carbon dioxide can be relatively easily reduced to organic matter in a bioelectrochemical system (BES). However, due to insufficient reduction force from in-situ hydrogen evolution, it is difficult for nitrogen reduction. In this study, MoS2 was firstly used as an electrocatalyst for the simultaneous reduction of CO2 and N2 to produce microbial protein (MP) in a BES. Cell dry weight (CDW) could reach 0.81±0.04 g/L after 14 d operation at -0.7 V (vs. RHE), which was 108±3 % higher than that from non-catalyst control group (0.39±0.01 g/L). The produced protein had a better amino acid profile in the BES than that in a direct hydrogen system (DHS), particularly for proline (Pro). Besides, MoS2 promoted the growth of bacterial cell on an electrode and improved the biofilm extracellular electron transfer (EET) by microscopic observation and electrochemical characterization of MoS2 biocathode. The composition of the microbial community and the relative abundance of functional enzymes revealed that MoS2 as an electrocatalyst was beneficial for enriching Xanthobacter and enhancing CO2 and N2 reduction by electrical energy. These results demonstrated that an efficient strategy to improve MP production of BES is to use MoS2 as an electrocatalyst to shift amino acid profile and microbial community.

Using ferrous-oxidizing bacteria to enhance the performance of a pH neutral all-iron flow battery.

Among various redox flow batteries (RFBs), the all-iron RFBs have greater application potential due to high accessibility of electrolytes. However, the potential of microaerobic ferrous-oxidizing bacteria (FeOB) to improve the performance of RFB has been neglected. Here, several experiments were conducted using Fe2+-diethylenetriaminepentaacetic acid (DTPA)/Na3[Fe(CN)6] as a redox couple for investigating the enhanced performance by FeOB in this RFB. Results showed that the maximum current density of experimental reactors could achieve 22.56 A/m2 at 0.1 M, whereas power density could still maintain 3.42 W/m2(16.96 A/m2 and 1.58 W/m2 for control group); meantime, the polarization impedance of anode increased slower and Fe2+-DTPA oxidation peak emerged maximum 494 mV negative shift. With increased electrolyte concentration in chronopotentiometry experiments, the experimental reactor achieved higher discharging specific capacity at 0.3 M, 10 mA/cm2. Microbial composition analysis showed maximum 75% is Brucella, indicating Brucella has ferrous-oxidizing electroactivity.

Effects of nitrogen supply on hydrogen-oxidizing bacterial enrichment to produce microbial protein: Comparing nitrogen fixation and ammonium assimilation.

To investigate the effects of nitrogen source supply on microbial protein (MP) production by hydrogen-oxidizing bacteria (HOB) under continuous feed gas provision, a sequencing batch culture comparison (N2 fixation versus ammonium assimilation) was performed. The results confirmed that even under basic cultivation conditions, N2-fixing HOB (NF-HOB) communities showed higher levels of CO2 and N2 fixation (190.45 mg/L Δ CODt and 11.75 mg/L Δ TNbiomass) than previously known, with the highest biomass yield being 0.153 g CDW/g COD-H2. Rich ammonium stimulated MP synthesis and the biomass accumulation of communities (increased by 7.4 ～ 14.3 times), presumably through the enhancement of H2 and CO2 absorption. The micro mechanism may involve encouraging the enrichment of species like Xanthobacter and Acinetobacter then raising the abundance of nitrogenase and glutamate synthase to facilitate the nitrogen assimilation. This would provide NF-HOB with ideas for optimizing their MP synthesis activity.

Prediction of Buckwheat Maturity in UAV-RGB Images Based on Recursive Feature Elimination Cross-Validation: A Case Study in Jinzhong, Northern China.

Buckwheat is an important minor grain crop with medicinal and edible functions. The accurate judgment of buckwheat maturity is beneficial to reduce harvest losses and improve yield. With the rapid development of unmanned aerial vehicle (UAV) technology, it has been widely used to predict the maturity of agricultural products. This paper proposed a method using recursive feature elimination cross-validation (RFECV) combined with multiple regression models to predict the maturity of buckwheat in UAV-RGB images. The images were captured in the buckwheat experimental field of Shanxi Agricultural University in Jinzhong, Northern China, from September to October in 2021. The variety was sweet buckwheat of "Jinqiao No. 1". In order to deeply mine the feature vectors that highly correlated with the prediction of buckwheat maturity, 22 dimensional features with 5 vegetation indexes, 9 color features, and 8 texture features of buckwheat were selected initially. The RFECV method was adopted to obtain the optimal feature vector dimensions and combinations with six regression models of decision tree regression, linear regression, random forest regression, AdaBoost regression, gradient lifting regression, and extreme random tree regression. The coefficient of determination (R2) and root mean square error (RMSE) were used to analyze the different combinations of the six regression models with different feature spaces. The experimental results show that the single vegetation index performed poorly in the prediction of buckwheat maturity; the prediction result of feature space "5" combined with the gradient lifting regression model performed the best; and the R2 and RMSE were 0.981 and 1.70 respectively. The research results can provide an important theoretical basis for the prediction of the regional maturity of crops.

Rapid detection of nitrite based on nitrite-oxidizing bacteria biosensor and its application in surface water monitoring.

Timely and sensitive detection of nitrite is of great significance for human health protection and water pollution treatment. However, many biosensors can only determine the comprehensive toxicity of the water, and there are few electroactive biofilm (EAB) sensors for the specific detection of pollutants. Biofilms formed by bacteria with specific functions can improve the specificity of nitrite identification by biosensors. This study developed a novel, rapidly responding, high sensitivity (958.6 µAµM-1cm-2), wide detection range and anti-interference electrochemical biosensor based on electroactive nitrite-oxidizing bacteria. The biosensor could accurately detect nitrite in the range of 0.3-100 mg/L within 3 min by the cyclic voltammetry (CV) method. The bioelectrode could perform stable detection of nitrite over 200 cycles. The specificity of the biosensor for detecting nitrite was demonstrated by the presence of nitrite oxidizing bacteria (NOB) and nitrite oxidase enzyme (NXR) on the electrode biofilm. The biosensor performed well in wetlands and rivers, with an RSD <14.8% in the detection of nitrite at low concentrations, and further revealed the nitrification occurrence. Our study provided a feasible way for the development of a highly sensitive, rapidly responding and stable electrochemical biosensor, which also exhibited potential applications for long-term detection of nitrite and assessment of ecological function in surface water (rivers, lakes, wetlands, marshes, etc.).

Improving electroautotrophic ammonium production from nitrogen gas by simultaneous carbon dioxide fixation in a dual-chamber microbial electrolysis cell.

Microbial electrosynthesis is a promising technology for high-value added products generation from organic and inorganic waste. In this work, autotrophic dual-chamber microbial electrolysis cells (MECs) were set up for N2 fixation at -0.9 V vs Ag/AgCl (sat. KCl) cathodic potential under ambient conditions. Higher NH4+ production yield (average value of 0.35 µmol h-1 cm-2, normalized to cathode surface area) and higher faradaic efficiency (FE, 20.25%) were obtained with intermittent addition of N2 and CO2, while the yield and FE were only 0.018 µmol h-1 cm-2 and 4.21% in the absence of CO2. Furthermore, cyclic voltammograms (CV) explained the bioelectrochemical behavior of N2 reduction was coupled with CO2 reduction in the autotrophic MECs. Microbial community analysis and functional prediction in the cathodic chamber revealed that Xanthobacter and Hydrogenophaga played as producers for N2 and CO2 fixation and Pannonibacter acting as a decomposer for converting organic nitrogen to ammonium. This work not only provided an optional bioelectrocatalytic method for N2 fixation with negative CO2-emissions but also revealed the mechanism of simultaneous fixation of N2 and CO2 via Calvin cycle in autotrophic MECs.

Butyryl/Caproyl-CoA:Acetate CoA-transferase: cloning, expression and characterization of the key enzyme involved in medium-chain fatty acid biosynthesis.

Coenzyme A transferases (CoATs) are important enzymes involved in carbon chain elongation, contributing to medium-chain fatty acid (MCFA) biosynthesis. For example, butyryl-CoA:acetate CoA transferase (BCoAT) is responsible for the final step of butyrate synthesis from butyryl-CoA. However, little is known about caproyl-CoA:acetate CoA-transferase (CCoAT), which is responsible for the final step of caproate synthesis from caproyl-CoA. In the present study, two CoAT genes from Ruminococcaceae bacterium CPB6 and Clostridium tyrobutyricum BEY8 were identified by gene cloning and expression analysis. Enzyme assays and kinetic studies were carried out using butyryl-CoA or caproyl-CoA as the substrate. CPB6-CoAT can catalyze the conversion of both butyryl-CoA into butyrate and caproyl-CoA into caproate, but its catalytic efficiency with caproyl-CoA as the substrate was 3.8-times higher than that with butyryl-CoA. In contrast, BEY8-CoAT had only BCoAT activity, not CCoAT activity. This demonstrated the existence of a specific CCoAT involved in chain elongation via the reverse ß-oxidation pathway. Comparative bioinformatics analysis showed the presence of a highly conserved motif (GGQXDFXXGAXX) in CoATs, which is predicted to be the active center. Single point mutations in the conserved motif of CPB6-CoAT (Asp346 and Ala351) led to marked decreases in the activity for butyryl-CoA and caproyl-CoA, indicating that the conserved motif is the active center of CPB6-CoAT and that Asp346 and Ala351 have a significant impact on the enzymatic activity. This work provides insight into the function of CCoAT in caproic acid biosynthesis and improves understanding of the chain elongation pathway for MCFA production.

Electrode-dependent ammonium oxidation with different low C/N ratios in single-chambered microbial electrolysis cells.

Alternative method should be found to solve the ammonia accumulation in anaerobic digestion. Herein, electrode-dependent ammonium oxidation was successfully achieved in anaerobic single-chambered microbial electrolysis cells (MECs)under different low C/N ratios (0, 1, and 1.5), with an applied voltage of 0.6 V as well as an initial NH4+-N and NO3--N concentration of 500 and 300 mg/L. The nitrogen removal performance of MECs and the controls indicated that applying a voltage stimulated nitrogen removal under low C/N ratios of 0, 1, and 1.5. However, the remaining organic carbon in MEC with a relatively higher C/N ratio of 3 inhibited the ammonium oxidation. Current changes and cyclic voltammetry demonstrated that the bioanode with several bioelectrochemical activities could promote ammonium oxidation. The dominant genera Truepera, Aquamicrobium, Nitrosomonas, Arenimonas, Comamonas, and Cryobacterium enriched on both electrodes could be the key functional taxa in MECs with C/N ratios of 0, 1, and 1.5. The remaining sodium acetate in MEC with C/N ratio of 3 inhibits microbial community structure and relative abundance, which may adversely affected nitrogen removal. Further caculation showed that nitrogen balance was essentially achieved, while electron balance was disrupted since electrons may be consumed through NO3--N recycle and cell synthesis, and finally caused low coulombic efficiency.

Integrative effect of citrate on Cr(â ¥) and total Cr removal using a sulfate-reducing bacteria consortium.

In controlling toxic Cr(Ⅵ) pollution, the sulfate-reducing bacteria (SRB) method-a bioresource technology-is considered more sustainable and stable than synthetic technologies; however, its mechanisms of metal removal are unclear. This study investigated the mechanism of the use of citrate as a carbon source in an SRB bioreactor for Cr(Ⅵ) removal by disassemble or simulation approach. We show that citrate can mask toxicity, whereby the IC50 value (inhibitory concentration affecting 50% of the test population) of citrate was higher than that of lactate, and that citrate can also protect water systems from oxidation. The anti-oxidation rate of citrate ranged from 76.00% to 90.92%; whereas for citrate‒Cr(Ⅲ), the oxidation rate was only 0.185%-0.587%. Citrate can up-regulate microbial genes and functions, causing acetate and sulfide (NaFeS2) accumulation. Acetate addition promoted Cr adsorption by sulfide (mainly NaFeS2) and promoted sulfide sedimentation. Moreover, in addition to Cr(Ⅵ) reduction and Cr(Ⅲ)‒sulfide generation, the addition of sulfide promoted sedimentation; the correlation coefficient between the sedimentation coefficient and the sulfur content was r = -0.88877 at p < 0.01. Therefore, citrate had a systemic radiative effect on every aspect of the SRB‒citrate system model for Cr(Ⅵ) removal. In addition to the reduction in the former simple model, an integrative effect (including adsorption, sedimentation, and metabolism) was combined with NaFeS2 for Cr removal, which was regulated by the SRB‒citrate system. Exploration and understanding of these mechanisms promote SRB‒citrate methods to be wider implications in practice.

Prediction of the Soil Organic Matter (SOM) Content from Moist Soil Using Synchronous Two-Dimensional Correlation Spectroscopy (2D-COS) Analysis.

This paper illustrates a simple yet effective spectroscopic technique for the prediction of soil organic matter (SOM) from moist soil through the synchronous 2D correlation spectroscopy (2D-COS) analysis. In the moist soil system, the strong overlap between the water absorption peaks and the SOM characteristic features in the visible-near infrared (Vis-NIR) spectral region have long been recognised as one of the main factors that causes significant errors in the prediction of the SOM content. The aim of the paper is to illustrate how the tangling effects due to the moisture and the SOM can be unveiled under 2D-COS through a sequential correlogram analysis of the two perturbation variables (i.e., the moisture and the SOM) independently. The main outcome from the 2D-COS analysis is the discovery of SOM-related bands at the 597 nm, 1646 nm and 2138 nm, together with the predominant water absorbance feature at the 1934 nm and the relatively less important ones at 1447 nm and 2210 nm. This information is then utilised to build partial least square regression (PLSR) models for the prediction of the SOM content. The experiment has shown that by discarding noisy bands adjacent to the SOM features, and the removal of the water absorption bands, the determination coefficient of prediction (Rp2) and the ratio of prediction to deviation (RPD) for the prediction of SOM from moist soil have achieved Rp2 = 0.92 and the RPD = 3.19, both of which are about 5% better than that of using all bands for building the PLSR model. The very high RPD (=3.19) obtained in this study may suggest that the 2D-COS technique is effective for the analysis of complex system like the prediction of SOM from moist soil.

Ammonia oxidation and denitrification in a bio-anode single-chambered microbial electrolysis cell.

In this study, anodic ammonia oxidation and denitrification were performed in single-chamber bioelectrochemical systems at a wide range of anodic potentials (-400 to +400 mV) versus Ag/AgCl. The low coulombic efficiencies (~30.84%) in reactors were mainly due to electrons being transferred to atmospheric oxygen through the electrode and reversal of the electrode. The removal efficiencies of acetate, ammonia, and total nitrogen were 100%, 100%, and 40.44% at +200 mV and 100%, 100%, and 50.24% at -200 mV, respectively. The nitrogen-removal mechanisms were nitrogen respiration/nitrate reduction at +200 mV and denitrification at -200 mV, and ammonia oxidation occurred by coupling with sulfate-reducing at -300 and -400 mV. Thauera, Comamonas, Alicycliphilus, Nitrosomonas, Desulforhabdus, Dethiosulfatibacter, and Desulfomicrobium were the dominant genera at the anode which participated in the nitrification/denitrification or sulfate-reducing processes. In summary, ammonia oxidation and denitrification could be coupled with carbon-removal or sulfur-reduction using a bio-anode with a suitable anodic potential.