Absence Of CO Research Articles

Molecular Assembled Electrocatalyst for Highly Selective CO2 Fixation to C2+ Products.

In certain metalloenzymes, multimetal centers with appropriate primary/secondary coordination environments allow carbon-carbon coupling reactions to occur efficiently and with high selectivity. This same function is seldom realized in molecular electrocatalysts. Herein we synthesized rod-shaped nanocatalysts with multiple copper centers through the molecular assembly of a triphenylphosphine copper complex (CuPPh). The assembled molecular CuPPh catalyst demonstrated excellent electrochemical CO2 fixation performance in aqueous solution, yielding high-value C2+ hydrocarbons (ethene) and oxygenates (ethanol) as the main products. Using density functional theory (DFT) calculations, in situ X-ray absorption spectroscopy (XAS) and quasi-in situ X-ray photoelectron spectroscopy (XPS), and reaction intermediate capture, we established that the excellent catalytic performance originated from the large number of double copper centers in the rod-shaped assemblies. Cu-Cu distances in the absence of CO2 were as long as 7.9 Å, decreasing substantially after binding CO2 molecules indicating dynamic and cooperative function. The double copper centers were shown to promote carbon-carbon coupling via a CO2 transfer-coupling mechanism involving an oxalate (OOC-COO) intermediate, allowing the efficient production of C2+ products. The assembled CuPPh nanorods showed high activity, excellent stability, and a high Faradaic efficiency (FE) to C2+ products (65.4%), with performance comparable to state-of-the-art copper oxide-based catalysts. To our knowledge, our findings demonstrate that harnessing metalloenzyme-like properties in molecularly assembled catalysts can greatly improve the selectivity of CO2RR, promoting the rational design of improved CO2 reduction catalysts.

CO2-responsive surfactant for oil-in-water emulsification and demulsification from molecular perspectives

To economically and environmentally recover oil from reservoirs and promote CO2 utilization (CU) project, CO2 responsive surfactants have been developed to undertake multiple tasks including emulsification and demulsification during different production stages. Understanding the switching mechanisms from molecular perspectives is of great importance to the choice and design of high-performance CO2-responsive surfactants. In this work, we performed molecular dynamics (MD) simulations to study the emulsification and demulsification processes of a heptane/water mixture in the presence of a typical CO2-responsive surfactant-lauric acid (LA). Before injecting CO2, the deprotonated lauric acids (DLA) can stabilize O/W emulsions in an aqueous solution due to strong electrostatic repulsions and high interfacial activity of DLA, whereas the protonation of lauric acid (PLA) arising from CO2 injection would result in the coalescence of emulsion droplets thanks to the greatly reduced hydrophilicity of the polar groups of lauric acids and surface charge neutralization, which is unfavorable for emulsion stabilization. The potential mean force (PMF) results show a high energy barrier preventing the fusion process when two emulsions approach each other in the absence of CO2, indicating high stability of the emulsions. However, when DLA turns to be PLA, the energy barrier disappears and an attraction force emerges due to the entropic effect if two emulsions are close enough. Our study provides important insights into the structural properties of emulsions before and after CO2-triggered switching and sheds light on the switching mechanisms which may assist in selecting and designing efficient CO2-responsive surfactants.

Interplay between Surface-Adsorbed CO and Bulk Pd Hydride under CO2-Electroreduction Conditions

Palladium is an increasingly investigated electrocatalyst for the electrochemical reduction of carbon dioxide due to its unique ability to yield carbon monoxide or formate with large selectivities at high vs low overpotentials (i.e., ∼−0.5 to ∼−1.0 vs ∼−0.1 to ∼−0.4 V vs the reversible hydrogen electrode), respectively. While this behavior has been described multiple times on different Pd-electrocatalysts, previous studies disagree with regard to palladium’s ability to form a hydride phase (PdHx) under CO2 reduction reaction (CO2RR) conditions, as well as on the influence of this PdHx on its CO2RR-selectivity. These inconsistencies are partially related to the known poisoning of the Pd-surface during the CO2RR with adsorbed CO, whose precise influence on the formation of PdHx and corresponding effects on the CO2RR-mechanism and product selectivity remain poorly understood. With this motivation, herein we used an unsupported Pd-aerogel to investigate CO adsorption and PdHx formation at CO2RR potentials in electrolytes with different compositions (i.e., in the presence or absence of CO2 and bicarbonate) and as a function of the applied potential and duration of the potential hold. The results of these electrochemical measurements unveiled the strong influence of surface-adsorbed CO on the formation rate of Pd-hydride, for which the final stoichiometry was nevertheless found to be independent of the presence of CO2 or bicarbonate. This finding was supported by in situ X-ray absorption spectroscopy (XAS) measurements that confirmed the complete formation of β-phase PdHx (with x ≈ 0.6) at all applied potentials under CO2RR conditions, thus shedding light on the contradictory results in this regard reported in previous operando XAS studies.

Unraveling the Role of Glycine in K2CO3 Solvent for CO2 Removal

Carbon dioxide (CO2), a main composition of greenhouse gases, is believed to be responsible for global warming. Both potassium carbonate (K2CO3) and amino acids have been studied for CO2 removal. In this study, for the first time, carbamate formation in the absence of CO2 was discovered in K2CO3 solvents when small amounts of amino acids like glycine were added, and the mechanism of carbamate formation and CO2 absorption in such solvents are detailed and supported the observed fast CO2 absorption in the presence of amino acids. In the mixed solvent of K2CO3 and glycine, bicarbonate and hydroxide were formed from carbonate hydrolysis, and the deprotonated amino acid reacted with bicarbonate to form carbamate in the absence of CO2 and, in the presence of CO2, reacted with CO2 to form carbamate which could subsequently hydrolyze into bicarbonate. As a result, amino acid (even with a small amount) significantly enhanced the CO2 absorption kinetics in the mixed solvents, and a high CO2 loading (0.62 mol CO2/mol K2CO3) was achieved in multiple (e.g., 10) cycles. Such mixed solvents of K2CO3 and amino acid therefore may overcome the limitations of each individual component and may be ideal candidates for CO2 removal.

Boosting the activity of PdAg2/Al2O3 supported catalysts towards the selective acetylene hydrogenation by means of CO-induced segregation: A combined NAP XPS and mass-spectrometry study

Selective hydrogenation (or semi-hydrogenation) of acetylene into ethylene is an important industrial process. The aim of the present work is thus to learn regularities governing the CO-induced segregation and elaborate practical procedures for tuning the surface structure of Pd-Ag nanoparticles to improve their catalytic performance towards the selective hydrogenation of acetylene to ethylene. Utilizing NAP XPS the CO adsorption-induced Pd atoms segregation in supported PdAg2/Al2O3 catalysts already at room temperature has been shown. The surface enrichment with Pd further increases if the treatment temperature is increased up to 250 °C. This specific configuration with a redistributed Pd/Ag surface atomic ratio is appreciably stable and self-sustained even at the absence of CO at moderately elevated temperatures. Nevertheless, a reductive treatment in hydrogen at 450 °C reverts the nanoparticle surface structure to the pristine state. Catalytic properties of this peculiar CO-induced configuration of PdAg2/Al2O3 towards the selective acetylene hydrogenation was investigated using a combination of NAP XPS and MS techniques. The PdAg2/Al2O3 catalyst with the surface enriched with Pd due to the CO-induced segregation manifests improved activity with 100 % selectivity under the conditions used. The results obtained clearly demonstrate that CO adsorption-induced segregation is a powerful tool that can be used to optimize the surface composition and catalytic performance of bimetallic nanoparticles.

Activation of carbonated brine with surfactants and sulfate anion for enhanced oil recovery processes

CO2-based enhanced oil recovery (EOR) methods has gained special attention since they can extract trapped oil from depleted reservoirs and store CO2 in the ground. Considering these advantages, the current study aimed to investigate the effect of CO2 on the performance of both carbonated and activated (solution with tuned ions and surfactants) carbonated brine (CB) on the dynamic interfacial tension (DIFT) of crude oil, under constant temperature of 50 °C and pressure range of 0–3000 psi. In the first step, the IFT of CO2 and crude oil was measured to find the first and multiple contact miscibility (FCM and MCM) pressures. Then, two synthetic brines including synthetic sea water (SB) and tuned SB (called SB-2SO4, i.e. SB spiked with two times of SO42- and depleted from Na+ and Cl-) with the ionic strength of 0.8 M were prepared. Four surfactants including sodium luryl sulphate (SLS, anionic type), hexadecyltrimethyl ammonium bromide (CTAB, cationic type) and two ionic liquids (ILs) namely dodecyl-3-methyl imidazolium chloride ([C12 mim]Cl) and octadecyl-3-methyl imidazolium chloride ([C18 mim]Cl) were selected to examine the effect of surfactant type and alkyl chain length on the IFT concomitant with swelling factor in the presence and absence of CO2 in three different pressures including below, close to and higher than the MCM pressure. The best surface activity with very low IFT values and low adsorption time was obtained with C-SB-2SO4-CTAB, i.e. carbonated solution containing CTAB and tuned brine spiked with sulfate. Finally, the experimental data were used to model the dynamic IFT and to calculate the relaxation time.

Developing New Quinone Based Electrodes for Electrochemical Carbon Capture

The need for cost-effective carbon capture technology is rapidly increasing. To limit the global temperature increase to 1.5 degrees within the next century, the level of CO2 mitigation needs to be increased drastically [1]. Current technology, i.e., amine scrubbing, provides several challenges which limit their deployment: high regeneration energy, high operational costs and degradation at high temperatures [2]. An electrochemical approach avoids large energy losses and can selectively uptake CO2 by utilizing redox-active organic molecules. To compete with conventional chemical scrubbing, the electrochemical cell needs high power density, high CO2 uptake and long cycle stability. Redox-active molecules such as quinone-based molecules have been utilized in this area however suffer from low cycling stability due to organic molecules leaking into the electrolyte [3,4]. Quinone-polymer electrodes have shown a high efficiency for CO2 capture however are prone to quinone degradation and low active-material mass [5]. Here we present our work on a new class of quinone-based electrodes for electrochemical CO2 capture, and explore their electrochemistry in the presence and absence of CO2 and quantify their CO2 uptake capacities. This work paves the way for the design and discovery of improved electrode materials for electrochemical CO2 capture. The Intergovernmental Panel on Climate Change (2018), Global Warming of 1.5 degrees. Available at: https://www.ipcc.ch/sr15/ (Accessed: 10 December 2021)Rahimi, M., Zucchelli, F., Puccini, M. and Alan Hatton, T., 2020. Improved CO2 Capture Performance of Electrochemically Mediated Amine Regeneration Processes with Ionic Surfactant Additives. ACS Applied Energy Materials, 3(11), pp.10823-10830.Apaydin, D., Głowacki, E., Portenkirchner, E. and Sariciftci, N., 2014. Direct Electrochemical Capture and Release of Carbon Dioxide Using an Industrial Organic Pigment: Quinacridone. Angewandte Chemie International Edition, 53(26), pp.6819-6822.Ranjan, R., Olson, J., Singh, P., Lorance, E., Buttry, D. and Gould, I., 2015. Reversible Electrochemical Trapping of Carbon Dioxide Using 4,4′-Bipyridine That Does Not Require Thermal Activation. The Journal of Physical Chemistry Letters, 6(24), pp.4943-4946.Voskian, S and Hatton, T., 2019. Faradaic Electro-swing Reactive Adsorption for CO2 Capture. Energy and Environmental Science, 12(12), pp.3530-3547

Interplay between Surface-Adsorbed CO and Bulk Pd-Hydride at CO2 Electroreduction Conditions

Due to its potential to replace fossil fuels in chemical processes by converting carbon dioxide (CO2) to industrial base reactants, the electroreduction of CO2 is receiving tremendous attention. Among the large number of electrocatalysts currently under investigation for this reaction, palladium (Pd) is increasingly appealing due to its ability to produce both carbon monoxide (CO) and formate at high selectivities depending on the applied potential. This unique change in selectivity between CO and formate at high vs. low overpotentials (i.e., -0.5 to -1.0 vs. -0.1 to -0.4 V vs. the reversible hydrogen electrode (VRHE), respectively) has been described multiple times on different Pd-electrocatalysts [1-3]. Those mechanistic investigations mainly focused on understanding the ability of palladium to form hydride (PdHx) under CO2 electroreduction conditions. While β-PdH is usually found at high overpotentials, the formation of α-PdH is described at low overpotentials, and a mixed-phase between both compositions is generally reported at intermediate overpotentials [1,3-5]. As a result, the CO2 reduction reaction (CO2RR) is assumed to take place on β-PdH at the high overpotentials leading to CO production, while α-PdH or a mixed α/β-phase is believed to be the active phase at low overpotentials associated with high formate yields [1,3,4]. However, large differences between the potential of β-PdH formation, as well as the extent of the mixed hydride state (i.e., featured as a sudden transition between α- and β-phases [3,4], or extending over hundreds of millivolts [1,5]), have been reported. In parallel to this, Pd-surface poisoning with CO is known to influence palladium’s CO2RR selectivity [2,3] while also slowing down hydride formation [6]. However, the precise interplay between surface-adsorbed CO and the formation of PdH, along with their combined effects on the mechanism of CO2 electroreduction remains poorly understood.In light of this, in this work, we investigated these effects using an unsupported Pd-aerogel with a web thickness of ≈ 6 nm, synthesized via a novel ethanolic synthesis approach [7]. We first analyzed the influence of the electrolyte composition (i.e., presence vs. absence of CO2 and bicarbonate) on the formation of surface-adsorbed CO and PdH by performing potential holds followed by positive linear sweep voltammograms in a rotating disk electrode (RDE) setup. As shown in Fig. 1A, these voltammograms featured two oxidation peaks at ≈ 0.8 vs. ≈ 1.0 VRHE that we could assign to the desorption of absorbed hydrogen and the oxidation of adsorbed CO, respectively. This in turn allowed us to track the formation of both of these species in relation to the applied potential and duration of the potential holds. Under CO2 electroreduction conditions, a full monolayer of CO was found to form across the entire CO2 electroreduction potential range. Moreover, large differences in the rate of PdH formation as a function of the applied potential were found in the presence of CO2 and/or bicarbonate, while in CO2- and bicarbonate-free electrolytes hydride formation is quasi-instantaneous at all potentials relevant for CO2 electroreduction. Time-dependent RDE investigations at constant potentials also revealed an initial decrease in the hydride content of the PdH phase during the formation of the CO monolayer, hinting at the involvement of this hydride in a hydrogenation step previously described as part of the CO2 electroreduction mechanism at low overpotentials [2]. Finally, these experiments were complemented with time-resolved in-situ X-ray absorption measurements that confirmed the formation of full β-PdH at all applied overpotentials under CO2 electroreduction conditions (see Fig. 1B), however, differences in the time-dependence of PdH formation on the applied potential were revealed.In summary, this contribution showcases the potential- and time-dependent CO monolayer formation under CO2RR conditions and its influence on PdH-formation. Specifically, our results reveal the independence of the final PdH-stoichiometry on the applied potential, while exposing the effect of the latter variable on the rates of CO-monolayer and β-PdH formation. On this basis, the mechanisms of CO2 electroreduction on Pd that have been proposed so far should be revisited to consider the simultaneous presence of full β-PdH and a near-full monolayer of CO at all overpotentials unveiled by our results.

Evaluation of the Vapor Hydrolysis of Lithium Aluminum Hydride for Mobile Fuel Cell Applications.

The controlled vapor hydrolysis of LiAlH4 has been investigated as a safe and predictable method to generate hydrogen for mobile fuel cell applications. A purpose-built vapor hydrolysis cell manufactured by Intelligent Energy Ltd. was used as the reaction vessel. Vapor was created by using saturated salt solutions to generate humidity in the range of 46–96% RH. The hydrolysis products were analyzed by thermogravimetric analysis (TGA) and powder X-ray diffraction and compared with possible hydroxide-based phases characterized using the same methods. Analysis of the products of the LiAlH4 vapor hydrolysis reaction at a relative humidity in excess of 56% indicated complete decomposition of the LiAlH4 phase and formation of the hydrated layered double hydroxide, [LiAl2(OH)6]2CO3·3H2O, rather than the simple salts, LiOH and Al(OH)3, previously suggested by the literature. The high level of hydration of the layered double hydroxide (LDH) (12% wt water) and the presence of carbonate indicated that the feed stream was contaminated with CO2 and that the highly hydrated and hygroscopic product would be detrimental to the mobile hydrogen production process, restricting recyclability of the water fuel cell byproduct and lowering the gravimetric density of LiAlH4. Carrying out the vapor hydrolysis reaction in a glovebox in the absence of CO2 indicated that the hydroxide derivative of the LDH, [LiAl2(OH)6]OH·2H2O, could be formed instead, but the water content was even more significant, equating to 17% of the carried weight. TGA showed that water was retained up to 300 and 320 °C in the two phases, making thermal recycling of the water retained impractical and casting doubt on whether generating hydrogen on the move by vapor hydrolysis of LiAlH4 is practical.

Foaming and defoaming properties of CO2‐switchable surfactants

AbstractThe present study is about the foaming and defoaming properties of the CO2‐switchable surfactant N,N‐dimethyltetradecylamine (C14DMA) and its advantages compared with the non‐switchable counterpart tetradecyltrimethylammonium bromide (C14TAB). In the absence of CO2, C14DMA is a water insoluble organic molecule without any surface activity thus being unable to stabilize foams. In the presence of CO2, the head group becomes protonated which transforms the water insoluble molecule into a cationic surfactant. Comparing the surface properties and foamability of C14DMA and C14TAB one finds a very similar behavior. However, the foam stabilities differ depending on the gas. Foaming the two‐surfactant solutions with CO2 leads to very unstable foams in both cases. However, foaming the two surfactant solutions with N2 reveals the switchability of C14DMA: while the volume of foams stabilized with C14TAB hardly changes over 1600 s, the volume of foams stabilized with C14DMA decreases significantly in the same period of time. This difference is due to the fact that the surface activity, that is, the amphiphilic nature, of C14DMA is continuously switching off since CO2 is displaced by N2 thus deprotonating and deactivating the surfactant.

Degradation of parathion methyl by reactive sorption on the cerium oxide surface: The effect of solvent on the degradation efficiency

A simple and easily scalable “wet” procedure was used to prepare nanocrystalline cerium oxide capable of destroying the toxic organophosphate pesticide parathion methyl. The synthetic procedure consists of the direct precipitation of cerous salt with aqueous ammonia in the absence of CO 2 . The prepared cerium oxide was able to decompose the organophosphate compounds both in nonpolar (e.g., heptane) and polar aprotic (e.g., acetonitrile) solvents. However, in solvents with hydrogen-bond donating ability, the –OH groups on the cerium oxide surface were solvated and inactivated. The preferential solvation model was used to express the experimental dependencies of the cerium oxide degradation efficiency on the composition of the water-acetonitrile mixture. In certain solvent systems, some empirical polarity scales, such as the alpha-scale or the Dimrodth-Richardt parameter E T (30), may be correlated with the degradation efficiency of cerium oxide.

Construction of Synergistic Co and Cu Diatomic Sites for Enhanced Higher Alcohol Synthesis

Construction of Synergistic Co and Cu Diatomic Sites for Enhanced Higher Alcohol Synthesis

James A. Rand Young Investigator's Award: Questioning the “Nickel Free” Total Knee Arthroplasty

BackgroundA study was performed to measure metal ions present in the knee joint after performing a total knee arthroplasty (TKA) with standard cobalt chromium (CoCr) components as well as with “nickel-free” oxidized zirconium femoral and titanium tibial (OxZr/Ti) components. MethodsKnee joint fluid was collected prior to arthrotomy, and on postoperative day one to determine the amount of metal debris generated when performing a TKA with standard instrumentation from consecutive cases with CoCr components (n = 24) and OxZr/Ti components (n = 16). ResultsCoCr implant patients had statistically higher levels of nickel (Ni) (29.7%, P = .033), cobalt (Co), (1,100.7%, P < .0001) and chromium (Cr) (118.9%, P < .0001) postoperatively. The cutting blocks and sawblades do not contain Co, which therefore must have come from the components. The metal ions generated from the sawblades and cutting blocks, therefore, could be discerned from the OxZr/Ti whose components don’t contain Co, Cr, or Ni. The OxZr patients had significantly higher Cr (9.5×, P < .001) and Ni (5.1×, P < .001) post-TKA vs pre-TKA; Co levels were not significantly different as expected with the absence of Co in the components (P = .60). The Ni levels generated in performing an Oxinium TKA was 3.3 times higher than when performing a CoCr TKA (1.37 vs. 41 ppb, P < .001). ConclusionsThe substantial degree of Ni generation resulting from performing a hypoallergenic “nickel-free” TKA calls into questions the rationale of utilizing more expensive lower Ni components on the basis of known or suspected Ni or Cr allergy.

Carbon capture and storage investment: Fiddling while the planet burns

<h2>Summary</h2> Carbon capture and storage (CCS) has been recognized as a key technology in energy systems decarbonization. However, numerous attempts to deploy CCS failed, and the technology is still viewed as pre-commercial. Consequently, public investment in CCS has been largely limited to research, development, and demonstration (RD&D) in capture technology. While it is understood that private investment will typically focus on the development of intellectual property aimed at delivering a commercial advantage, there is a lack of evidence that public investment in CCS RD&D can deliver commercial viability. Here, we show that, while improved CCS technology in the electricity systems will deliver larger market shares to the technology developers, the benefit on overall system cost is negligible. Thus, public sector efforts should focus primarily on overcoming commercialization failures, such as the absence of CO₂ transport and storage infrastructures and other deployment barriers, leaving the development of intellectual property to the private sector.

Intrinsic weaknesses of Co-free Ni–Mn layered cathodes for electric vehicles

Co-free Li[NixMn1−x]O2 (NM) cathodes have received considerable attention owing to their cost competitiveness and cycling stability. However, Ni-rich, Co-free NM cathodes have not been extensively studied and the reasons for their poor performance at low temperatures remain unclear. Herein, the fundamental properties and electrochemical performances of Co-free Li[NixMn1−x]O2 and conventional Li[NixCoyMn1−x−y]O2 (NCM) cathodes (x = 0.8 and 0.9) at various temperatures are compared. Although the cycling stability and rate capabilities of Co-free NM cathodes are comparable with those of NCM cathodes at elevated operating temperatures, their performances are significantly inferior to those of NCM cathodes at low temperatures. The absence of Co in layered oxide cathodes not only increases diffusion-hindering cation disorder in their Li layers but also reduces the tolerance of their ionic diffusivities to low temperatures, leading to poor rate capabilities at high C-rates and low temperatures. To improve the practical viability of Co-free layered oxide cathodes, it is necessary to resolve their serious weakness of poor low-temperature performance.

A Green and Efficient Synthesis Method of Benzo[c]cinnolines: Electrochemical Reduction of 2,2’‐Dinitrobiphenyl in the Presence of CO2

AbstractBenzo[c]cinnolines are an essential framework material in medicinal chemistry owing to its promising anti‐cancer and antioxidant activity, and good pharmacological properties. Accordingly, benzo[c]cinnolines are synthesized through electrochemical reduction of 2,2’‐dinitrobiphenyl (DNBP) in aprotic solvents with CO2. Cyclic voltammetry (CV), cyclic voltabsorptometry (CVA), derivative cyclic voltabsorptometry (DCVA) techniques, and in‐situ FT‐IR spectroelectrochemistry are used to investigate the mechanism of electrochemical reduction of DNBP in the presence of CO2. It is a reversible 2‐electron‐transfer reaction in an aprotic solution of DMSO in the absence of CO2, while it turned into a completely irreversible 8‐electron process in the presence of CO2. Benzo[c]cinnolines were finally obtained by potentiostatic electrolysis with conversion rate of 99 %, indicating the high selectivity of this reaction. Above all, DNBP can be electrochemically reduced into BC in the presence of CO2, providing a theoretical and practical path for electrochemical synthesis of bioactive benzo[c]cinnolines (BC).

Identification and molecular characterization of Brucella abortus and Brucella melitensis isolated from milk in cattle in Azerbaijan

BackgroundAzerbaijan currently ranks thirteenth in global incidence of human brucellosis, with an estimated annual incidence through 2000 at over 50 cases per million. Brucella melitensis has been isolated from patients and is thought to have been acquired through contact with small ruminants or as a foodborne infection. To reduce the burden of human brucellosis, the Azerbaijani government began in 2002, a nationwide vaccination control campaign in small ruminants. There is serological evidence of bovine brucellosis (presumably due to Brucella abortus) in Azerbaijan, but no prevalence estimates were available when this study started in March 2017. The aim of this study was to isolate and identify Brucella spp. from cow milk in the Ganja region, where brucellosis takes a heavy toll on humans and livestock.ResultsBlood and milk samples were collected from cows (n = 1075) in early lactation (up to 90-days) in farms that had a history of previous positive serological results and abortions. Twenty-two out of 57 milk samples collected from seropositive cows, showed growth on Farrell’s media, when incubated with 5% CO2. Eight additional milk samples showed growth in the absence of CO2. The classical biotyping classified them as Brucella abortus (22) and Brucella melitensis (8). RT-PCR confirmed that strains belonged to the genus Brucella. MLVA profiles were obtained for DNA extracted from two B. abortus and six B. melitensis strains. While the B. abortus genetic profile was described in the MLVA database, matching the profile of B. abortus strains isolated in East Europe, Central Asia and China, we found a new genotype for the B. melitensis strains isolated in Azerbaijan, clustering with strains belonging to the American clade, rarely identified in the region.ConclusionDespite the implementation of the vaccination program in small ruminants, our results suggest that spill-over events of B. melitensis from small ruminants to cattle have occurred. However, cattle are likely to be primarily infected with B. abortus, which warranted the implementation of a bovine brucellosis program. Such a program started in fall 2017. In the Ganja region, cattle should be considered as a potential source of B. abortus and B. melitensis for humans.

How palladium inhibits CO poisoning during electrocatalytic formic acid oxidation and carbon dioxide reduction

Development of reversible and stable catalysts for the electrochemical reduction of CO2 is of great interest. Here, we elucidate the atomistic details of how a palladium electrocatalyst inhibits CO poisoning during both formic acid oxidation to carbon dioxide and carbon dioxide reduction to formic acid. We compare results obtained with a platinum single-crystal electrode modified with and without a single monolayer of palladium. We combine (high-scan-rate) cyclic voltammetry with density functional theory to explain the absence of CO poisoning on the palladium-modified electrode. We show how the high formate coverage on the palladium-modified electrode protects the surface from poisoning during formic acid oxidation, and how the adsorption of CO precursor dictates the delayed poisoning during CO2 reduction. The nature of the hydrogen adsorbed on the palladium-modified electrode is considerably different from platinum, supporting a model to explain the reversibility of this reaction. Our results help in designing catalysts for which CO poisoning needs to be avoided.

Low CO2 Levels Are Detrimental for In Vitro Plantlets through Disturbance of Photosynthetic Functionality and Accumulation of Reactive Oxygen Species

Photosynthesis of plantlets in tissue culture containers is not considered important, compared to photosynthesis of ex vitro plants, due to the exogenous source of carbohydrates present in tissue culture media. However, CO2 starvation can generate a burst of reactive oxygen species (ROS). We examined this phenomenon in tissue culture, since CO2 levels may become very low during the light period. The research was carried out with lily scales, regenerating adventitious bulblets, and with Arabidopsis seedlings. CO2 starvation was achieved by placing a small vial of concentrated KOH solution in the culture container. CO2 removal reduced the growth of regenerated lily bulblets by 33% or 23%, with or without sucrose in the medium, respectively. In Arabidopsis seedlings, CO2 removal decreased growth by 50% or 78% in the presence or absence of sucrose in the medium, respectively. Therefore, the addition of sucrose as a replacement for photosynthesis resulted in only partial recovery of growth. Staining with nitroblue tetrazolium (NBT) showed little to no ROS in ex vitro growing seedlings, while abundant ROS were detected in seedlings grown under in vitro CO2 starvation. Seedlings grown under normal tissue culture conditions (no CO2 withdrawal) showed low levels of ROS. In lily tissue culture, CO2 starvation decreased the maximum quantum efficiency of photosystem II (Fv/Fm) from 0.69 to 0.60, and in Arabidopsis from 0.76 to 0.62. Fv/Fm of ex vitro lily and Arabidopsis seedlings was 0.77 and 0.79, respectively. This is indicative of a disturbance in photosynthesis functionality and the occurrence of in vitro stress under reduced CO2 concentrations. We conclude that poor growth, in the absence of CO2, was partly due to strongly reduced photosynthesis, while the detrimental effects were most likely due to a burst of ROS.

Investigation on the electroreduction azo coupling mechanism of 1,4-dinitrobenzene in aprotic media containing CO2

The electrochemical behavior of 1,4-dinitrobenzene (PNB) in the aprotic solvent containing CO2 was investigated by using CO2 instead of proton donor to eliminate the interference of hydrogenation reaction. In the absence of CO2, the electrochemical behavior of PNB was a chemical reversible two-steps one-electron transfer process, but with the introduction of CO2, it was transformed into an irreversible 7-electrons transfer process. In the potential range between −0.3 V and −1.7 V, three reduction peaks were observed, and minutely studied by cyclic voltammetry, chronoamperometry, and in situ FT-IR spectroelectrochemistry methods, respectively. The results show that CO2 is involved in five steps reaction during the electroreduction process of PNB, which plays a key role in PNB electroreduction azo coupling. The electroreduction azo coupling mechanism of PNB in the presence of CO2 is exposed, which will provide a theoretical basis for precise control of the electroreduction degradation of dinitrobenzene. The product obtained by potentiostatic electrolysis is confirmed as 4,4′-dinitrosoazobenzene by 13C NMR, 1H NMR, MS and FTIR because of the instability of the final product, which is consistent with the mechanism inference. It has been well-proved that in situ FT-IR spectroelectrochemistry is an applicable method to study the wide range of complex electrochemical process.