Thermodynamic controls on rates of iron oxide reduction by extracellular electron shuttles.

Anaerobic microbial respiration in suboxic and anoxic environments often involves particulate ferric iron (oxyhydr-)oxides as terminal electron acceptors. To ensure efficient respiration, a widespread strategy among iron-reducing microorganisms is the use of extracellular electron shuttles (EES) that transfer two electrons from the microbial cell to the iron oxide surface. Yet, a fundamental understanding of how EES-oxide redox thermodynamics affect rates of iron oxide reduction remains elusive. Attempts to rationalize these rates for different EES, solution pH, and iron oxides on the basis of the underlying reaction free energy of the two-electron transfer were unsuccessful. Here, we demonstrate that broadly varying reduction rates determined in this work for different iron oxides and EES at varying solution chemistry as well as previously published data can be reconciled when these rates are instead related to the free energy of the less exergonic (or even endergonic) first of the two electron transfers from the fully, two-electron reduced EES to ferric iron oxide. We show how free energy relationships aid in identifying controls on microbial iron oxide reduction by EES, thereby advancing a more fundamental understanding of anaerobic respiration using iron oxides.

Atomic Ordering Engineering of Precious Metal Alloys in Liquid Phase Synthesis.

Atomic ordering of noble metal alloys is an effective strategy for improving catalytic performance, yet the low-temperature synthesis of ordered alloys still faces significant challenges. The low-temperature liquid phase method has enormous potential for the synthesis of alloys; however, the atomic ordering mechanism of this process has not been thoroughly studied. Herein, we investigate the mechanism of the influence of metal precursors, reducing agents, solvents, and mixing modes of reactant regulating strategies on precious metal alloy ordering using this method. These regulating strategies are designed to change the coordination structure of metal complexes, affect the reduction potential of metals, and thus change the reduction order of metals and their arrangement in the alloy products. Notably, the reduction potential differences between metal complexes can be used to predict the ordering of the synthetic products (Pd-Cu, Pd-Cd, Pd-Sn, Pd-Pb, and Pt-Sn). This work provides an excellent platform for investigating atomic arrangement engineering.

Influence Mechanism of Interfacial Oxidation of Li3YCl6 Solid Electrolyte on Reduction Potential.

Halide-based solid electrolytes are promising candidates for all solid-state lithium-ion batteries (ASSLBs) due to their high ionic conductivity, wide electrochemical window, and excellent chemical stability with cathode materials. However, when tested in practice, their intrinsic electrochemical stability windows do not well match the conditions for stable operation of ASSBs. Existing literature reports halide-based ASSBs that still operate well outside the electrochemical stability window, while ASSBs that do not operate within the window are not well studied or the studies are based on the cathode material interface. In this study, we aim to elucidate the mechanism behind all-solid-state battery failure by investigating how the reduction potential of Li3YCl6 solid-state electrolyte itself changes under overcharging conditions. Our findings demonstrate that in Li-In|Li3YCl6|Li3YCl6-C half-cells during the first state of charge, Cl ions participate in charge compensation, resulting in a depletion of ligands. This phenomenon significantly affects the reduction potential of Y3+, causing it to be reduced to Y2Cl3 and ultimately to Y0 at conditions far exceeding its actual reduction potential. Furthermore, we analyze the interfacial impedance induced by this process and propose a novel perspective on battery failure.

Preparation and bioevaluation of a novel 99mTc-labelled propylene amine oxime (PnAO) containing two 4-methyl-2-nitroimidazole groups as a promising tumor hypoxia imaging agent.

Hypoxia is a common phenomenon in solid tumors, and its presence inhibits the efficacy of tumor chemotherapy and radiotherapy. Accurate measurement of hypoxia before tumor treatment is essential. Three propylene amine oxime (PnAO) derivatives with different substituents attached to 2-nitroimidazole were synthesized in the work, they are 3,3,9,9-tetramethyl-1,11-bis(4-bromo-2-nitro-1H-imidazol-1-yl)-4,8-diazaundecane-2,10-dione dioxime (Br2P2), 3,3,9,9-tetramethyl-1,11-bis(4-methyl-2-nitro-1H-imidazol-1-yl)-4,8-diazaundecane-2,10-dione dioxime (Me2P2) and 3,3,9,9-tetramethyl-1,11-bis(4,5-dimethyl-2-nitro-1H-imidazol-1-yl)-4,8-diazaundecane-2,10-dione dioxime (2Me2P2). The three compounds were radiolabeled with 99mTc to give three complexes([99mTc]Tc-Br2P2, [99mTc]Tc-Me2P2 and [99mTc]Tc-2Me2P2) with good in vitro stability. [99mTc]Tc-Me2P2 with a more suitable reduction potential had the highest hypoxic cellular uptake, compared with [99mTc]Tc-2P2 that have been previously reported, [99mTc]Tc-Br2P2 and [99mTc]Tc-2Me2P2. Biodistribution results in S180 tumor-bearing mice demonstrated that [99mTc]Tc-Me2P2 had the highest tumor-to-muscle (T/M) ratio (12.37 ± 1.16) at 2 h in the four complexes. Autoradiography and immunohistochemical staining results revealed that [99mTc]Tc-Me2P2 specifically targeted tumor hypoxic regions. The SPECT/CT imaging results showed that [99mTc]Tc-Me2P2 could target the tumor site. [99mTc]Tc-Me2P2 may become a potential hypoxia imaging agent.

Mechanistic and Kinetic Consideration of the Photochemically Generated Oxidative Organic Radicals in Dissolved Black Carbon Solutions under Simulated Solar Irradiation.

The photochemically generated oxidative organic radicals (POORs) in dissolved black carbon (DBC) was investigated and compared with that in dissolved organic matter (DOM). POORs generated in DBC solutions exhibited higher one-electron reduction potential values (1.38-1.56 V) than those in DOM solutions (1.22-1.38 V). We found that the photogeneration of POORs from DBC is enhanced with dissolved oxygen (DO) increasing, while the inhibition of POORs is observed in reference to DOM solution. The behavior of the one-electron reducing species (DBC•-/DOM•-) was employed to explain this phenomenon. The experimental results revealed that the DO concentration had a greater effect on DBC•- than on DOM•-. Low DO levels led to a substantial increase in the steady-state concentration of DBC•-, which quenched the POORs via back-electron reactions. Moreover, the contribution of POORs to the degradation of 19 emerging organic contaminants (EOCs) in sunlight-exposed DBC and DOM solutions was estimated. The findings indicate that POORs play an important role in the photodegradation of EOCs previously known to react with triplets, especially in DBC solutions. Compared to DOM solutions, POOR exhibits a lower but considerable contribution to EOC attenuation. This study enhances the understanding of pollutant fate in aquatic environments by highlighting the role of DBC in photochemical pollutant degradation and providing insights into pollutant transformation mechanisms involving POORs.

Study on Carbon Emission Influencing Factors and carbon emission reduction potential in China's food production industry.

Climate warming has become a global issue of close concern, and China, as a significant agricultural country, has an increasing demand for food, which requires China to increase carbon reduction in this industry. This paper accounts for carbon emissions from the food production industry (CEFI) using the input-output method, then screens the influencing factors of CEFI based on Random Forest (RF), analyzes the heterogeneous effects of the influencing factors on CEFI in different clusters through K-means-SHAP, and finally explores the potential of carbon emissions from this industry for the period 2024-2040. The study's findings are as follows: First, there are apparent inequalities in CEFI, especially between provinces, which are gradually increasing. Second, addressing people's consumption awareness and behaviors is not the fundamental solution to alleviate CEFI; instead, it should focus on sustainable agricultural production transformation and "food miles" in the transportation phase. In addition, attention needs to be paid to the impacts of fertilizer application, transport modes, and livestock management on the CEFI of each cluster. Finally, the study suggests that around 2028, 70% of China's provinces will be at the "carbon peak" and that less developed and more developed regions have more significant potential to reduce emissions. In this regard, this paper encourages a series of policies that are key to promoting the sustainable development of CEFI, such as reducing the volume and efficiency of traditional fertilizers, vigorously developing organic fertilizer inputs, strengthening technological innovation and R&D inputs in the transportation sector, and steadily supporting germplasm innovation in the livestock sector.

The influence of pH on the efficacy of oxidation-reduction potential (ORP) to predict chlorine disinfection of surrogate bacteria, Escherichia coli O157:H7 and Listeria monocytogenes in oxidant demand free conditions and fresh produce wash water.

Oxidation-reduction potential (ORP) is commonly used as a rapid measurement of the antimicrobial potential of free chlorine during industrial fresh produce washing. The current study tested the hypothesis that ORP can act as a "single variable" measurement of bacterial (vegetative and endospores) inactivation effectiveness with free chlorine irrespective of the water pH value. This situation has on occasion been assumed but never confirmed nor disproven. Chlorine-dosed pH 6.5 and 8.5 phosphate buffer solutions were inoculated with Escherichia coli (E. coli), Listeria innocua (L. innocua), or Bacillus subtilis (B. subtilis) endospores. ORP, free chlorine (FC), and log reduction were monitored after 5 s (for E. coli and L. innocua) and up to 30 min (for B. subtilis spores) of disinfection. Logistic and exponential models were developed to describe how bacteria reduction varied as a function of ORP at different pH levels. Validation tests were performed in phosphate buffered pH 6.5 and 8.5 cabbage wash water periodically dosed with FC, cabbage extract and a cocktail of Escherichia coli O157:H7 (E. coli O157:H7) and Listeria monocytogenes (L. monocytogenes). The built logistic and exponential models confirmed that at equal ORP values, the inactivation of the surrogate strains was not consistent across pH 6.5 and pH 8.5, with higher reductions at higher pH. This is the opposite of the well-known free chlorine-controlled bacterial inactivation, where the antibacterial effect is higher at lower pH. The validation test results indicated that in the cabbage wash water, the relationship between disinfection efficiency and ORP was consistent with the oxidant demand free systems. The study suggests that ORP cannot serve as a reliable single variable measurement to predict bacterial disinfection in buffered systems. When using ORP to monitor and control the antibacterial effectiveness of the chlorinated wash water, it is crucial to take into account (and control) the pH.

Partial synthetic models of FeMoco with sulfide and carbyne ligands: Effect of interstitial atom in nitrogenase active site.

Nitrogen-fixing organisms perform dinitrogen reduction to ammonia at an Fe-M (M = Mo, Fe, or V) cofactor (FeMco) of nitrogenase. FeMco displays eight metal centers bridged by sulfides and a carbide having the MFe7S8C cluster composition. The role of the carbide ligand, a unique motif in protein active sites, remains poorly understood. Toward addressing how the carbon bridge affects the physical and chemical properties of the cluster, we isolated synthetic models of subsite MFe3S3C displaying sulfides and a chelating carbyne ligand. We developed synthetic protocols for structurally related clusters, [Tp*M'Fe3S3X]n-, where M' = Mo or W, the bridging ligand X = CR, N, NR, S, and Tp* = Tris(3,5-dimethyl-1-pyrazolyl)hydroborate, to study the effects of the identity of the heterometal and the bridging X group on structure and electrochemistry. While the nature of M' results in minor changes, the chelating, µ3-bridging carbyne has a large impact on reduction potentials, being up to 1 V more reducing compared to nonchelating N and S analogs.

The reduction of nitrobenzene by Fe(II)-goethite-hematite heterogeneous systems: Insight from thermodynamic parameters of reduction potential.

Determining the contaminants reduction rate by dissolved ferrous iron (Fe(II)aq) bound to iron oxides is curial for evaluating the abiotic attenuation of contaminants in aquifers. However, few studies have assessed the contaminants reduction rate controlled by thermodynamic parameters in heterogeneous systems with different iron oxides. In this study, a linear free energy relationship (LFER) was established between the nitrobenzene reduction rate and the thermodynamic driving force (reduction potential (EH) and pH) in Fe(II)aq-goethite-hematite co-existing systems. Results showed that the reduction rate of nitrobenzene correlated with the EH of the heterogeneous system. The standard reduction potential (EH0mix) of the mixed iron oxides could be obtained by a proportionate linear combination of the single iron oxide system EH0. Based on this, the EH of the heterogeneous systems could be calculated theoretically by combining EH0mix and the Nernst equation. Furthermore, a parallel LFER with the slope of 1 was established to associate the nitrobenzene reduction rate with EH and pH. The intercept term was related to the adsorption capacity of different iron oxides towards Fe(II)aq. The Fe(II)aq saturation adsorption capacity of hematite was 1.5 times higher than that of goethite. After normalizing the nitrobenzene reduction rate to the Fe(II)aq saturation adsorption capacity, the maximum difference in intercept terms was reduced from 37% to 15%. These findings would provide an important and feasible methodological support for the quantitative evaluation of abiotic attenuation of contaminants in groundwater.

Biogenically synthesized porous TiO2 nanostructures for advanced anti-bacterial, electrochemical, and photocatalytic applications.

This study develops environmentally benign capping technique to synthesize nanoparticles of Curcuma longa-coated titanium dioxide (CR-TiO2) from titanium isopropoxide by utilizing the extract of Rosa rubiginosa flowers as reducing and chelating agent. The biogenically synthesized nanoparticles revealed excellent anti-bacterial, electrochemical, and photocatalytic properties due to the presence of porous TiO2 nanostructures. The sharp peaks by XRD pattern showed the crystallinity and phase purity of TiO2 nanoparticles. BET analysis proved mesoporous nature of the materials with specific surface area of 134 m2 g -1. The vibrational spectra suggest hydroxyl groups from flavonoids of Curcuma longa acting as functionalizing agent for TiO2 nanoporous structures with visible luminescence, which is proven in fluorescence spectra and is applicable for photocatalytic studies. The anti-bacterial studies showed good inference on TiO2 nanoparticles against Pseudomonas auruginosa and proved it to be an excellent antipseudomonal agent with the oxidative potential. The maximum degradation of phenol red dye in the presence of TiO2 under visible light conditions was observed. The supercapacitor fabricated using the biogenic TiO2 three-electrode system exhibited a specific capacitance of 128 Fg-1 (10 mV s-1), suggesting it as an excellent electrode material. The LSV curve at 50 mV s-1 scan rate showed that oxygen reduction potential (ORR) of CR-TiO2 electrodes was 121 mV. The present study is a new application of nanoparticles in sustainability consideration of the environment as well as a solution to the power crisis with fewer limitations. The well-distinguished antidiabetic and BSA denaturation potential suggests that these porous TiO2 nanostructures can be useful for drug delivery as glucose inhibitors and oral anti-inflammatory drugs with the restriction of adverse side effects.

Are electric vehicles really the optimal option for the transportation sector in China to approach pollution reduction and carbon neutrality goals?

Profound worldwide fleet electrification is thought to be the primary route for achieving the target of carbon neutrality. However, when and how electrification can help mitigate environmental impacts and carbon emissions in the transport sector remains unclear. Herein, the overall life-cycle environmental impacts and carbon saving range of two typical A-class vehicles in China, including electric vehicle (EV) and internal combustion engine vehicle (ICEV), were quantified by the life cycle assessment model for endpoint damage with localization parameters. The results showed that the EV outperformed the ICEV for the total environment impact after a travel distance of 39,153 km and for carbon emissions after 32,292 km. The ICEV was more carbon-friendly only when the driving distance was less than 3229 km/a. Considering a full lifespan travel distance of 150,000 km, the whole life-cycle average environmental impacts of EV and ICEV were calculated as 8.6 and 17.5 mPt/km, respectively, but the EV had 2.3 times higher impacts than the ICEV in the production phase. In addition, the EV unit carbon emission was 140 g/km, 46.8% lower than that of the ICEV. Finally, three potential reduction scenarios were considered: cleaner power mix, energy efficiency improvement and composite scenario. These scenarios contributed 19.1%, 13.0% and 32.1% reductions, respectively. However, achieving carbon peak and neutrality goals in China remains a great challenge unless fossil fuels are replaced by renewable energy. The research can provide scientific reference for the method and practice of emission reduction link identification, eco-driving choice and emission reduction path formulation.

An Investigation of the Influence of Tyrosine Local Interactions on Electron Hopping in a Model Protein.

Multi-step electron transfer reactions are important to the function of many cellular systems. The ways in which such systems have evolved to direct electrons along specific pathways are largely understood, but less so are the ways in which the reduction-oxidation potentials of individual redox sites are controlled. We prepared a series of three new artificial variants of Pseudomonas aeruginosa azurin where a tyrosine (Tyr109) is situated between the native Cu ion and a Ru(II) photosensitizer tethered to a histidine (His107). Arginine, glutamine, or methionine were introduced as position 122, which is near to Tyr109. We investigated the rate of CuI oxidation by a flash-quench generated Ru(III) oxidant over pH values from 5 to 9. While the identity of the residue at position 122 affects some of the physical properties of Tyr109, the rates of CuI oxidation are only weakly dependent on the identity of the residue at 122. The results highlight that more work is still needed to understand how non-covalent interactions of redox active groups are affected in redox proteins.

Route-level carbon dioxide emissions in intercity multimodal passenger transport: analytical framework and characteristics.

Understanding the CO2 emission characteristics and key mitigation pathways of intercity passenger transport is crucial for achieving sustainable development in the transport system. Using origin-destination data on travel between city pairs by various transportation modes, we employ the life cycle assessment (LCA) method to estimate route-level CO2 emissions from intercity multimodal passenger transport corridors, considering infrastructure construction and vehicle operation phases. Subsequently, a sensitivity analysis is conducted to assess the impact of 39 parameters associated with the construction phase, operation phase, and transportation modes on CO2 emissions from corridors. Trend analysis is employed to explore the future emission mitigation potential for the parameters that have the most significant impact on corridor emissions. Four intercity multimodal passenger corridors in China are selected as case studies. Results indicate that the CO2 emissions per passenger-kilometer from these corridors exhibit an approximate negative linear relationship with corridor lengths. The proportion of construction-related CO2 emission intensity of various intercity passenger transport modes varies significantly, ranging from 2.5 to 32.9%. In the medium term, effective emission-mitigation strategies should focus on decreasing private car gasoline consumption in three corridors under 200 km in length, as well as decreasing private car gasoline consumption and promoting clean electricity in the Xi'an-Yan'an corridor. In the long term, efforts should be placed on increasing electric private car share and promoting clean electricity. This study lays a crucial foundation for the refined management of CO2 emissions from future intercity passenger transport.

Interference of reversible redox compounds in enzyme catalysed assays - Electrochemical limitations.

BACKGROUND: Several commercial assay kits exist with limited explanation of the kit components and reagent constituents, which greatly increases potential incompatibility issues resulting in the loss of samples, time, and data. Herein we explore such issues via the redox ion [Fe(CN)6]3/4- in two commercial l-lactate and pyruvate assay kits. RESULTS: We clearly demonstrate significant interference from redox compounds with the l-lactate and pyruvate assays; a significance in signal inhibition/mechanism restriction, and false/mechanism exhaustion, respectively. Potential mechanisms are explored to explain interference. CONCLUSION: The need for transparency is crucial for consistency of assay kit performance from lab to lab. There is a need for suppliers to list the components of kits and/or list the potential for interference from specific agents to ensure that results obtained from these kits are reliable and reproducible.

Electron Transfer Energy and Hydrogen Atom Transfer Energy-Based Linear Free Energy Relationships for Predicting the Rate Constants of Munition Constituent Reduction by Hydroquinones.

No single linear free energy relationship (LFER) exists that can predict reduction rate constants of all munition constituents (MCs). To address this knowledge gap, we measured the reduction rates of MCs and their surrogates including nitroaromatics [NACs; 2,4,6-trinitrotoluene (TNT), 2,4-dinitroanisole (DNAN), 2-amino-4,6-dinitrotoluene (2-A-DNT), 4-amino-2,6-dinitrotoluene (4-A-DNT), and 2,4-dinitrotoluene (DNT)], nitramines [hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and nitroguanidine (NQ)], and azoles [3-nitro-1,2,4-triazol-5-one (NTO) and 3,4-dinitropyrazole (DNP)] by three dithionite-reduced quinones (lawsone, AQDS, and AQS). All MCs/NACs were reduced by the hydroquinones except NQ. Hydroquinone and MC speciations were varied by controlling pH, permitting the application of a speciation model to determine second-order rate constants (k) from observed pseudo-first-order rate constants. The intrinsic reactivity of MCs (oxidants) decreased upon deprotonation, while the opposite was true for hydroquinones (reductants). The rate constants spanned ∼6 orders of magnitude in the order NTO ≈ TNT > DNP > DNT ≈ DNAN ≈ 2-A-DNT > DNP- > 4-A-DNT > NTO- > RDX. LFERs developed using density functional theory-calculated electron transfer and hydrogen atom transfer energies and reported one-electron reduction potentials successfully predicted k, suggesting that these structurally diverse MCs/NACs are all reduced by hydroquinones through the same mechanism and rate-limiting step. These results increase the applicability of LFER models for predicting the fate and half-lives of MCs and related nitro compounds in reducing environments.

Life cycle assessment of greenhouse gas emissions of typical sewage sludge incineration treatment route based on two case studies in China.

The rapidly increasing amount of municipal sewage sludge generated in China necessitates a thorough examination and evaluation of available treatment options. In recent years, thermal-drying and incineration technology has gained popularity, however, it may lead to significant greenhouse gas (GHG) emissions. Nevertheless, the differences in boundary conditions and technological characteristic across various cases may affect emission levels significantly. Therefore, this study utilizes a life cycle assessment to estimate the GHG emissions associated with two typical sludge incineration routes in China: direct thermal-drying combined with coal co-incineration incinerator in Case 1 and indirect thermal-drying and self-sustain combustion in Case 2. The entire treatment processes, containing different functional units, were comprehensively investigated. The results demonstrate that Case 1 and Case 2 produce 1133.33 and 350.89 kg CO2-eq/tDS (sludge dry solid) of GHG emissions, respectively. In Case 1, coal co-incineration produces 828.63 kg CO2-eq/tDS of GHG emissions, accounting for 73.1% of the total GHG emissions. Moreover, the exhaust gas treatment is a significant GHG emission source, accounting for 9.2% and 16.9% of the total GHG emissions in Case 1 and Case 2, respectively. Additionally, the sludge thickening and dewatering unit in Case 2 produces 213.75 kg CO2-eq/tDS of GHG emissions, accounting for 60.9% of the total GHG emissions. Analysis of energy flow and heat balance characteristics indicate that the indirect heat transfer method used in thermal-drying leads to significant heat loss, which limits heat recovery potential and hinders GHG emission reduction. This study proposed a scenario case based on Case 2, addressing the issues with the improvement of heat transfer process and reduction of electricity consumption, potentially reducing GHG emissions by 8.8%. Additionally, applying an exhaust gas heat recovery system could further offset up to 22.8% of the total GHG emission.

Prediction of carbon emissions peak and carbon neutrality based on life cycle CO2 emissions in megacity building sector: Dynamic scenario simulations of Beijing.

In order to design an optimal carbon peak and carbon neutralization pathway for the high-density building sector, a dynamic prediction model is established using system-dynamics coupled building life cycle carbon emission model (SD-BLCA) with consideration of future evolutionary trajectory and time constraints. The model is applied in Beijing using the SD-BLCA combined with scenario analysis and Monte Carlo methods to explore optimal trajectory for its building sector under 30-year timeframe. The results indicate that by increasing the proportion of renewable energy generation by 7% and retrofitting 60 million m2 of existing buildings, these two mature measures can offset the growth of carbon emissions and achieve the peak target by 2025. However, achieving carbon neutrality necessitates a shift from isolated technologies to a comprehensive net-zero emissions strategy. The study proposes a time roadmap that integrates a zero-carbon energy supply system and the carbon reduction measures of the whole life cycle. This strategy primarily relies on renewable sources to provide heat, power, and hydrogen, resulting in estimated reductions of 29.8 Mt, 28.1 Mt, and 0.7 Mt, respectively. Zero energy buildings, green buildings, and renovated buildings can reduce carbon emissions through their own energy-saving measures by 8.4, 18.2, and 11.8 kg/m2, respectively.

Influence of redox potential on the accumulation of poly(3-hydroxybutyrate) by Bacillus megaterium.

The main goal of the present study was to evaluate the oxidation-reduction potential (ORP) on the production of poly(3-hydroxybutyrate) (P(3HB)) by Bacillus megaterium. Each microorganism has an optimal ORP range, and changes to the culture medium's ORP may redistribute the cell's metabolic flux, as such, the measurement and control of the ORP profile allows one to, in a way, manipulate the microbial metabolism, affecting the expression of certain enzymes and allowing for better control over the fermentative process. The ORP tests were carried out in a fermentation vessel coupled with an ORP probe, containing 1 L of mineral medium added with agroindustry byproducts (60% v/v of confectionery wastewater, and 40% v/v of rice parboiling water). The system's temperature was kept at 30 °C, with an agitation speed of 500 rpm. The vessel's airflow rate was controlled via a solenoid pump based on the ORP probe's data. Different ORP values were evaluated to verify their impact on biomass and polymer production. Cultures using OPR levels of 0 mV displayed the highest amounts of total biomass (5.00 g L-1) when compared to - 20 mV and - 40 mV (2.90 g L-1 and 0.53 g L-1, respectively). Similar results were also found for P(3HB)-to-biomass ratio, with polymer concentration being reduced when using ORP levels below 0 mV and with a maximum amount of polymer-to-biomass ratio of 69.87% after 48 h of culture. Furthermore, it was possible to observe that the culture's pH can also affect total biomass and polymer concentration, albeit to a lesser extent. Thus, when considering the data found during this study, it is possible to observe that ORP values can greatly impact B. megaterium cell's metabolism. Furthermore, the measurement and control of ORP levels may be an invaluable asset when trying to maximize polymer production under different culture conditions.

Oxido-Reduction Potential as a Method to Determine Oxidative Stress in Semen Samples.

There are different estimates for the incidence of infertility. Its occurrence may vary from area to area, but on average, it affects 15% of couples and 10-12% of men worldwide. Many aspects of infertility can be linked to reactive oxygen species (ROS) and the process of oxidative stress (OS). The association between poor semen quality and OS is well known. Unfortunately, there is no accepted protocol for the diagnosis and treatment of OS in andrology. Oxido-reduction potential (ORP) measurement is a new method for determining the ratio between oxidant and antioxidant molecules. Currently, ORP measurement is one of the fastest and most user-friendly methods of andrological OS determination and our goals were to confirm published correlations between ORP values and sperm parameters, examine how sperm concentration influences these results, and investigate whether intracellular ROS formations are also manifested in the ORP values or not after artificial ROS induction. Intracellular ROS formations were induced by menadione (superoxide anion inducer), hydrogen peroxide, and tert-butyl hydroperoxide (lipid peroxidation inducer) treatments; sperm parameters like motility and viability were determined with an SCA Scope system, and ORP changes were recorded by the Mioxsys system. Significant correlations were noticed among the ORP, spermatozoa concentration, motility, progressive motility, and viability. Nevertheless, only the ORP value after normalization with the sperm count correlated with these parameters. Due to normalization, very low and very high sperm concentrations can give misleading results. The means of the non-normalized ORP values were almost the same. All of the applied treatments resulted in decreases in the viability, motility, and progressive motility, and interestingly, altered ORP levels were detected. In addition, it was determined that seminal plasma had a significant protective effect on spermatozoa. The elimination of seminal plasma caused higher sensitivity of spermatozoa against used OS inducers, and higher ORP levels and decreased viabilities and motilities were measured. The ORP level could be a good indicator of male OS; however, in cases of low and high sperm counts, its result can be misleading. Overall, the conclusion can be drawn that ORP determination is a suitable method for detecting intracellular ROS accumulation, but it has limitations that still need to be clarified.

Thermodynamics Evaluation of Selective Hydride Reduction for α,ß-Unsaturated Carbonyl Compounds.

The selective reduction of α,ß-unsaturated carbonyl compounds is one of the core reactions and also a difficult task for organic synthesis. We have been attempting to study the thermodynamic data of these compounds to create a theoretical basis for organic synthesis and computational chemistry. By electrochemical measurement method and titration calorimetry, in acetonitrile at 298 K, the hydride affinity of two types of unsaturated bonds in α,ß-unsaturated carbonyl compounds, their single-electron reduction potential, and the single-electron reduction potential of the corresponding radical intermediate are determined. Their hydrogen atom affinity, along with the hydrogen atom affinity and proton affinity of the corresponding radical anion, is also derived separately based on thermodynamic cycles. The above data are used to establish the corresponding "Molecule ID Card" (Molecule identity card) and analyze the reduction mechanism of unsaturated carbonyl compounds. Primarily, the mixture of any carbonyl hydride ions and Ac-tempo+ will stimulate hydride transfer process and create corresponding α,ß-unsaturated carbonyl compounds and Ac-tempoH from a thermodynamic point of view.