Analysis Of Reaction Products Research Articles

A Tool for Reaction Monitoring in Real Time, the Development of a "Walk-Up Automated Reaction Profiling" System.

Optimization of chemical reactions requires a thorough analysis of reaction products and intermediates over a given time course. Chemical reactions are often analyzed by liquid chromatography-mass spectrometry (LC-MS), but generating LC-MS samples and data analysis is time-consuming and produces a significant amount of waste. We sought to remove the sample preparation and data analysis steps by implementing an iChemExplorer/Agilent LC-MS instrument as our reactor and analysis tool, coupled with an automated report generator of reaction progress over time. Herein, we show that our easy-to-use walk-up automated reaction profiling (WARP) system can sample chemical reactions multiple times to produce a data-rich report of reaction progress over time.

Low feed intake at weaning reduces intestinal glutathione levels and promotes cysteine oxidation to taurine in pigs.

Weaning stress in pigs is associated with low feed intake and poor nutrient utilization. Cysteine is a sulfur amino acid with key roles in pig production, but how cysteine metabolism and requirements are affected by weaning stress should be better defined. The objective of this study was to determine the collective impact of weaning and feed restriction on tissue cysteine metabolism. Pigs were weaned at 21-d age without access to feed (W; 6.90 ± 0.81kg; n = 9; reflecting acute nutritional stress) or were not weaned and remained with the sow (NW; 6.81 ± 0.65kg; n = 8). At euthanasia (23-d age), blood, bile, and liver, jejunum, and ileum tissues were collected. Plasma, bile, and tissue amino acid and amino thiol concentrations were analyzed by HPLC. Activity of glutamate cysteine ligase (GCL) and glutathione synthetase (GSS), enzymes needed for glutathione (GSH) production, and cysteine dioxygenase 1 (CDO1) were determined with activity assays followed by HPLC analysis of reaction products. Plasma (271 versus 192 ± 19 µmol/L; P < 0.001) and liver (417 versus 298 ± 33 nmol/g; P < 0.05) Cys concentrations were increased in W compared to NW pigs. Despite greater plasma Cys, jejunum and ileum Cys content were not affected by weaning (P > 0.10), whereas γ-glutamylcysteine (γ-GlyCys), the immediate precursor of GSH, declined in both jejunum (14.3 versus 9.7 ± 1.4 nmol/g; P < 0.01) and ileum (11.2 versus 6.4 ± 0.8 nmol/g; P < 0.001) in W pigs. Glutathione content was lower in the jejunum (1379 versus 1720 ± 70 nmol/g; P < 0.05) and ileum (1497 versus 1740 ± 74 nmol/g; P < 0.05) in W pigs. In the jejunum, GCL activity tended to be greater (0.56 versus 0.39 ± 0.07 nmol γ-GluCys • mg-1 • min-1; P < 0.10), whereas GSS activity tended to be lower (1.11 versus 1.38 ± 0.10 nmol GSH • mg-1 • min-1; P < 0.10) in W compared to NW pigs. In the ileum, the activities of GCL and GSS were not affected by weaning (P > 0.10). Although liver CDO1 activity was not different between groups (P < 0.10), liver taurine was greater in W compared to NW pigs (5115 versus 2336 ± 912 nmol/g; P = 0.001). Bile concentrations of Cys (1203 versus 279 ± 103 µmol/L; P < 0.001) and cysteinylglycine (203 versus 117 ± 33 µmol/L; P < 0.10), the direct product of GSH degradation, were greater in W compared to NW pigs. Collectively, these results suggest that systemic Cys is not effectively utilized for gut GSH production in newly weaned pigs and is instead oxidized to taurine and eliminated in bile.

Synergistically achieving particulate matter reduction and production performance optimization for zinc electrolysis by ultrasonication coupling anode-coated MnO2

Abating particulate matter (PM) from electrolysis processes is significant because this PM poses occupational threats to workers and has a negative impact on air quality. However, it remains a challenge to synergize the reduction of PM production and the improvement of electrolysis performance. This study developed a green method, termed as the coupling of ultrasonication and pre-coating MnO2 anode treatment (UMT). The effects on PM generation rate and electrolysis performance indicators were estimated using the bench-scale zinc electrolysis device, and the synergistic mechanism of UMT was expanded from the perspective of electrochemical reactions and bubble characteristics using analysis of reaction products, camera technique, and PM generation prediction models. The results showed UMT not only overcame the degradation of deposited zinc quality caused by the ultrasonication treatment but also solved the increased PM generation by the pre-coating MnO2 film treatment. The UMT simultaneously reduced PM (33.9 %-57.5 %), decreased zinc impurity content by (11.2 %-54.3 %), improved current efficiency of zinc deposition (0.19 %-1.71 %), and conserved electrolysis energy (0.27 %-1.01 %). The optimal performance of UMT occurred at 80 kHz. The UMT suppressed the gas evolution reactions and prematurely bursting bubbles, in favor of reducing the number and size of bubbles, to reduce PM generation. Meanwhile, the UMT improved the electrolysis performance by inhibiting the corrosion of lead-based anodes, promoting the mass transfer rate of Zn2+, providing more active surfaces, and decreasing the overpotential of reactions. The findings may provide references for the green development of the metal electrolysis industry.

Pharmacogenetic Approach to Tramadol Use in the Arab Population.

Tramdol is one of most popular opioids used for postoperative analgesia worldwide. Among Arabic countries, there are reports that its dosage is not appropriate due to cultural background. To provide theoretical background of the proper usage of tramadol, this study analyzed the association between several genetic polymorphisms (CYP2D6/OPRM1) and the effect of tramadol. A total of 39 patients who took tramadol for postoperative analgesia were recruited, samples were obtained, and their DNA was extracted for polymerase chain reaction products analysis followed by allelic variations of CYP2D6 and OPRM A118G determination. Numerical pain scales were measured before and 1 h after taking tramadol. The effect of tramadol was defined by the difference between these scales. We concluded that CYP2D6 and OPRM1 A118G single nucleotide polymorphisms may serve as crucial determinants in predicting tramadol efficacy and susceptibility to post-surgical pain. Further validation of personalized prescription practices based on these genetic polymorphisms could provide valuable insights for the development of clinical guidelines tailored to post-surgical tramadol use in the Arabic population.

Comprehensive nontargeted analysis of fluorosurfactant byproducts and reaction products in wastewater from semiconductor manufacturing

Semiconductor manufacturing employs per- and polyfluoroalkyl substances (PFAS) as fluoroasurfactants to enhance the quality of photolithography lines. Our research, employing a fragment-based approach to investigate nontarget PFAS, overcomes conventional homologous series limitations. In a mixture of PFAS standards used as a quality control sample, 92% (36 out of 39 compounds spanning 11 compound classes) were detectable through the fragment-based nontarget procedure. This indicates the effectiveness of this approach in identifying the hydrophobic and hydrophilic characteristics of various fluorosurfactants. Eighty-three PFAS were detected in wastewater and effluent samples from semiconductor industry, including 29 newly discovered compounds, categorized into three groups. First, besides detecting perfluorobutane sulfonamido ethanol (FBSE), various fluoroalkyl chain structures of FBSE derivatives were initially identified in wastewater. These include perfluorobutyl ether sulfonamido ethanol, unsaturated FBSE, and hydrogen-substituted FBSE. These derivatives were also detected in trace amounts in commercial authentic standards of FBSE. To quantify their presence, we analyzed the FBSE derivatives from the authentic standard, and the relative proportions of these derivatives contribute to approximately 0.5%. This suggests that the FBSE derivative series detected in wastewater may arise from byproducts of chemical formulations used in the manufacturing of semiconductors. Second, transformation products from FBSE during oxidation, including the first identified intermediate transformation compounds, perfluorobutane sulfonamido acetaldehyde and its hydrate, were discovered. Third, diverse reaction products are generated from the intricate processes of semiconductor manufacturing, which utilize strong acids, bases, and solvents under UV light or heated conditions. These processes include the formation of PFAS-related compounds through hydration, sulfonation, oxidation, and nitrification. This study revealed 25 isomeric PFAS, encompassing headgroup isomers and functional tail group isomers. These findings underscore the importance of comprehending diverse reactions and the overall emission compositions of PFAS in semiconductor wastewater, highlighting its complexity and presenting challenges for subsequent wastewater treatment.

PEPICO analysis of catalytic reactor effluents towards quantitative isomer discrimination: DME conversion over a ZSM-5 zeolite.

The methanol-to-hydrocarbons (MTH) process involves the conversion of methanol, a C1 feedstock that can be produced from green sources, into hydrocarbons using shape-selective microporous acidic catalysts - zeolite and zeotypes. This reaction yields a complex mixture of species, some of which are highly reactive and/or present in several isomeric forms, posing significant challenges for effluent analysis. Conventional gas-phase chromatography (GC) is typically employed for the analysis of reaction products in laboratory flow reactors. However, GC is not suitable for the detection of highly reactive intermediates such as ketene or formaldehyde and is not suitable for kinetic studies under well defined low pressure conditions. Photoelectron-photoion coincidence (PEPICO) spectroscopy has emerged as a powerful analytical tool for unraveling complex compositions of catalytic effluents, but its availability is limited to a handful of facilities worldwide. Herein, PEPICO analysis of catalytic reactor effluents has been implemented at the FinEstBeAMS beamline of MAX IV Laboratory. The conversion of dimethyl ether (DME) on a zeolite catalyst (ZSM-5-MFI27) is used as a prototypical model reaction producing a wide distribution of hydrocarbon products. Since in zeolites methanol is quickly equilibrated with DME, this reaction can be used to probe vast sub-networks of the full MTH process, while eliminating or at least slowing down methanol-induced secondary reactions and catalyst deactivation. Quantitative discrimination of xylene isomers in the effluent stream is achieved by deconvoluting the coincidence photoelectron spectra.

Gas chromatography/mass spectrometry analysis of reaction products of Chemical Weapons Convention-related 2-(N,N-dialkylamino)ethylchlorides with 2-(N,N-dialkylamino)ethanols.

The Chemical Weapons Convention (CWC) mandates rigorous screening of chemical weapons and their potential degradation/reaction products, which is essential to identify such products in suspected samples. The reaction between 2-(N,N-dialkylamino)ethylchlorides and 2-(N,N-dialkylamino)ethanols (precursors/degradation products of VX agents) produces a new class of reaction products that are not explored. The reaction products, bis(2-N,N-dialkylaminoethyl)ethers (1-10), were synthesized using established synthetic procedures, and gas chromatography/mass spectrometry (GC/MS) (electron ionization [EI] and chemical ionization [CI]) methods were developed for their identification. The GC/MS experiments were performed on an Agilent GC/MSD system using an HP-5MS capillary column. Methane gas was used as the CI reagent gas for GC/CIMS experiments. GC/retention index (RI) values of 1-10 were calculated using the retention times of the hydrocarbon mixture and the analytes. The GC/EI spectra of 1-10 exhibited [M-H]+ ions and distinctive fragments that provided valuable structural information. The selective fragmentation of the alkyl groups on nitrogen facilitated the discrimination of possible isomeric compounds. Interpretation of EI fragments in the high mass region is important for unambiguous identification of 1-10, because the major ions significantly match other CWC-related compounds containing the 2-(N,N-dialkylaminoethyl) group. GC/CI (methane) spectra included M+., [M + H]+, [M-H]+, reagent-specific adduct ions, and a few structure-indicative fragments. The spiking experiments in soil and water samples revealed that the target analytes were stable, easily extractable, and detectable using GC/MS. The reaction products, 1-10, could be successfully synthesized and characterized using GC/MS (EI and CI). The GC/MS and GC/RI data provide important insights into the unambiguous identification of the target molecules in challenging CWC verification and are helpful in participation in the Organization for the Prohibition of Chemical Weapons proficiency tests.

Development of sustainable alkali-activated slag bricks with high content of carbonated recycled concrete fines: Strength, microstructure and environmental benefit

This research presents a novel method of recycling construction waste while capturing CO2 through the formation of mineral carbon. The technology uses carbonated recycled concrete fines (CRCF) as the primary raw material to produce sustainable, high-performance alkali bricks with high replacement rates. Firstly, a general assessment of the physical and chemical properties of CRCF was carried out, which revealed the formation of silica gel encapsulating the surface of CRCF during carbonation. Subsequently, alkali bricks were prepared utilizing CRCF. The study investigated the impact of various mix proportions, water-to-cement ratios, and manufacturing process parameters on brick strength. Additionally, an in-depth analysis of reaction products and brick microstructures was carried out. The results showed that the bricks produced from CRCF were stronger than those from RCF, indicating enhanced reactivity after carbonation. Finally, an analysis demonstrated that utilizing RCF from construction waste can significantly reduce carbon dioxide emissions, thereby mitigating the environmental impact associated with cement production.

Enzymatic one-step synthesis of natural 2-pyrones and new-to-nature derivatives from coenzyme A esters

The 2-pyrone moiety is present in a wide range of structurally diverse natural products with various biological activities. The plant biosynthetic routes towards these compounds mainly depend on the activity of either type III polyketide synthase-like 2-pyrone synthases or hydroxylating 2-oxoglutarate dependent dioxygenases. In the present study, the substrate specificity of these enzymes is investigated by a systematic screening using both natural and artificial substrates with the aims of efficiently forming (new) products and understanding the underlying catalytic mechanisms. In this framework, we focused on the in vitro functional characterization of a 2-pyrone synthase Gh2PS2 from Gerbera x hybrida and two dioxygenases AtF6’H1 and AtF6’H2 from Arabidopsis thaliana using a set of twenty aromatic and aliphatic CoA esters as substrates. UHPLC-ESI-HRMSn based analyses of reaction intermediates and products revealed a broad substrate specificity of the enzymes, enabling the facile "green" synthesis of this important class of natural products and derivatives in a one-step/one-pot reaction in aqueous environment without the need for halogenated or metal reagents and protective groups. Using protein modeling and substrate docking we identified amino acid residues that seem to be important for the observed product scope.

Hydrogenolysis of Poly(Ethylene-co-Vinyl Alcohol) and Related Polymer Blends over Ruthenium Heterogeneous Catalysts.

The hydrogenolysis of polymers is emerging as a promising approach to deconstruct plastic waste into valuable chemicals. Yet, the complexity of plastic waste, including multilayer packaging, is a significant barrier to handling realistic waste streams. Herein, we reveal fundamental insights into a new chemical route for transforming a previously unaddressed fraction of plastic waste - poly(ethylene-co-vinyl alcohol) (EVOH) and related polymer blends - into alkane products. We report that Ru/ZrO2 is active for the concurrent hydrogenolysis, hydrogenation, and hydrodeoxygenation of EVOH and its thermal degradation products into alkanes (C1-C35) and water. Detailed reaction data, product analysis, and catalyst characterization reveal that the in-situ thermal degradation of EVOH forms aromatic intermediates that are detrimental to catalytic activity. Increased hydrogen pressure promotes hydrogenation of these aromatics, preventing catalyst deactivation and improving alkane product yields. Calculated apparent rates of C-C scission reveal that the hydrogenolysis of EVOH is slower than low-density polyethylene. We apply these findings to achieve hydrogenolysis of EVOH/polyethylene blends and elucidate the sensitivity of hydrogenolysis catalysts to such blends. Overall, we demonstrate progress towards efficient catalytic processes for the hydroconversion of waste multilayer film plastic packaging into valuable products.

Polymorphism of Bis(benzimidazole)bis(thiocyanato-N)cobalt(II) and Its Relevance to Studies of the Chief Color Test for Cocaine

Cobalt(II) thiocyanate-based tests are routinely used to screen cocaine products, with the formation of a blue species interpreted as a positive response. Two popular candidates for the origin of the blue color are an ionic coordination compound, frequently referred to as an ion pair, of the general form (HL)2[Co(SCN)4] or the coordination compound [CoL2(SCN)2], where L represents select nitrogenous bases. Given the high number of nitrogenous bases documented to yield false positives for cobalt(II) thiocyanate-based tests, a reasonable hypothesis is that both candidates are possible but their preferential formation depends on the specific nitrogenous bases screened. This hypothesis was tested through the crystallographic and spectroscopic analysis of reaction products of cocaine hydrochloride, lidocaine monohydrate hydrochloride, and benzimidazole exposed to a classic cobalt(II) thiocyanate reagent. Single-crystal X-ray diffraction revealed that the blue product isolated from benzimidazole test vessels is a coordination compound, with comparative ultraviolet–visible and Raman spectroscopy validating that blue precipitates collected from cocaine hydrochloride and lidocaine monohydrate hydrochloride reaction containers are ionic coordination compounds. Peaks corresponding to π-π* transitions in UV-vis at around 320 nm (cocaine hydrochloride: 320 nm, lidocaine hydrochloride: 323 nm) shift to a higher wavelength of 332 nm for the coordinated benzimidazole, and the broader d-d transitions at 550–630 nm show both a shift and change in envelope for benzimidazole coordinated with cobalt(II). The compound is a new polymorph of bis(benzimidazole)bis(thiocyanato-N)Cobalt(II), γ-[Co(Hbzim)2(SCN)2] (Hbzim = benzimidazole), and the differences in the intermolecular interactions to the two previous polymorphs were clarified by graph set analysis and Hirshfeld surface analysis. Furthermore, the coordination of aromatic nitrogen bases (such as benzimidazole) with Co(II) and aliphatic bases was compared by analyzing the Cambridge Structural Database, and the aromatic bases were found to have a shorter Co-N bond length compared to the aliphatic bases by around 0.02 Å.

Case study on 4-Isopropyl-ortho-xylene production

We have experimentally studied the alkylation reaction of o-xylene with propylene under kinetic control conditions followed by realkylation under thermodynamic control conditions. The paper provides an analysis of the alkylation reaction products obtained under kinetic control as well as kinetic analysis and thermodynamic analysis of the overalkylation process. The authors have considered the methyl group migration reactions during overalkylation and have given kinetic analyses of these reactions. We found that the optimal method for the preparation of 4 isopropyl-o-xylene is to conduct the process in two stages. The first one is a liquid-phase alkylation of o-xylene under kinetic control at 353 K. The second stage is liquid-phase realkylation of the obtained alkylation reaction mass until reaching thermodynamic equilibrium at a temperature range of 303-353 K under certain conditions. These conditions should ensure minimal migration of methyl groups, i.e. with minimum contact time and alkyl-/aryl- &lt; 0.5 ratio in the reaction products.

Получение 4-изопропил-орто-ксилола

We have experimentally studied the alkylation reaction of o-xylene with propylene under kinetic control conditions followed by realkylation under thermodynamic control conditions. The paper provides an analysis of the alkylation reaction products obtained under kinetic control as well as kinetic analysis and thermodynamic analysis of the overalkylation process. The authors have considered the methyl group migration reactions during overalkylation and have given kinetic analyses of these reactions. We found that the optimal method for the preparation of 4 isopropyl-o-xylene is to conduct the process in two stages. The first one is a liquid-phase alkylation of o-xylene under kinetic control at 353 K. The second stage is liquid-phase realkylation of the obtained alkylation reaction mass until reaching thermodynamic equilibrium at a temperature range of 303-353 K under certain conditions. These conditions should ensure minimal migration of methyl groups, i.e. with minimum contact time and alkyl-/aryl- &lt; 0.5 ratio in the reaction products.

LC-MS/MS Analysis of Reaction Products of Arginine/Methylarginines with Methylglyoxal/Glyoxal.

Methylglyoxal (MGO) and glyoxal (GO) are toxic α-dicarbonyl compounds that undergo reactions with amine containing molecules such as proteins and amino acids and result in the formation of advanced glycation end products (AGEs). This study aimed at investigating the reactivity of arginine (Arg) or dimethylarginine (SDMA or ADMA) with MGO or GO. The solutions of arginine and MGO or GO were prepared in PBS buffer (pH 7.4) and incubated at 37 °C. Direct electrospray ionization-high-resolution mass spectrometry (ESI-HRMS) analysis of the reaction mixture of Arg and MGO revealed the formation of Arg-MGO (1:1) and Arg-2MGO (1:2) products and their corresponding dehydrated products. Further liquid chromatography (LC)-MS analyses revealed the presence of isomeric products in each 1:1 and 1:2 product. The [M + H]+ of each isomeric product was subjected to MS/MS experiments for structural elucidation. The MS/MS spectra of some of the products showed a distinct structure indicative fragment ions, while others showed similar data. The types of products formed by the arginines with GO were also found to be similar to that of MGO. The importance of the guanidine group in the formation of the AGEs was reflected in similar incubation experiments with ADMA and SDMA. The structures of the products were proposed based on the comparison of the retention times and HRMS and MS/MS data interpretation, and some of them were confirmed by drawing analogy to the data reported in the literature.

Investigation of the compaction product on a nickel/diatomaceous earth catalyst

The activity of the Ni/diatomaceous earth catalyst used in the process of obtaining acetone from isopropyl alcohol was studied in a laboratory setup over a wide temperature range (150–3500C) at atmospheric pressure. The analysis of raw materials and reaction products was carried out by the chromatographic method. In the process of isopropyl alcohol conversion on the Ni/diatomaceous earth catalyst surface, the formation of compaction products and the effect of oxygen and hydrogen on the catalyst surface were studied using a Mag-Ben setup equipped with a quartz-spring reactor. The formation of compaction products on the surface of the Ni/diatomaceous earth catalyst was determined by thermogravimetric and kinetic methods. The maximum amount of compaction products is formed at a temperature of 3000C and above on the Lewis sites. Thermogravimetric studies showed that the formation of compaction product on the surface of the Ni/diatomaceous earth catalyst is time and temperature dependent.

Degradation of 1,2,3-trichloropropane using peroxydisulfate activation by green tea iron nanoparticles

The pollution of groundwater with 1,2,3-Trichloropropane (TCP) has raised significant concerns due to its toxicity and resistance to degradation. In this study, the degradation of TCP using peroxydisulfate (PDS) activation by green tea iron nanoparticles (G-INPs) was investigated and compared with traditional PDS oxidation activated by citric acid-Fe2＋(CA-Fe), which was commonly used as an effective PDS activator. Oxidation experiments and theoretical analysis were conducted to reveal the degradation efficiency and mechanism. The results showed that the TCP degradation efficiency was significantly enhanced in the G-INPs/PDS oxidation system compared to CA-Fe/PDS oxidation. The degradation efficiency was more than 77% after 48 hours (h) in G-INPs/PDS oxidation (0.625 mM Fe, 25 mM PDS, and 25°C with no pH adjustment) at an initial TCP concentration of 100 mg/L. In contrast, only 59% of TCP was degraded by CA-Fe/PDS using the same ferrous ion (Fe2＋) amount. The addition of G-INPs promoted the generation of hydroxyl radical (OH⋅ ), sulfate radical (SO4−⋅ ), and superoxide radical (O2-⋅ ), among which OH⋅ played a crucial role in the degradation process. The concentration of Fe2＋ in the G-INPs/PDS system after 48 h was twice as high as that in the Fe2＋/PDS system. The increased Fe2＋ content in the system facilitated the production of radicals, leading to improved degradation efficiency of TCP. Reaction product analysis further demonstrated that carbon dioxide (CO2) and hydrochloric acid (HCl) were the oxidation products of TCP degraded by G-INPs/PDS, and only a tiny amount (<5.5 wt%) of less toxic organic by-products were generated, including 1,3-dichloro-2-acetone, 1,2-dichloroethane and 1,1,2-trichloroethane. Conclusively, the G-INPs/PDS oxidation method seems to be a promising technology for removing high TCP contamination from wastewater or polluted groundwater.

Quantitative Electrochemistry-Mass Spectrometry: Real-Time Detection of Volatile Products for Electrocatalysis and Batteries

A major challenge both within electrocatalysis and battery research concerns the real-time (i) identification and (ii) quantification of volatile reaction products as a function of the applied electrochemical parameters and the reaction conditions. Analysis of both steadily evolving gases and of fast- and transient reaction phenomena can reveal key insights into reaction mechanisms. To this end, methods like Differential Electrochemical Mass Spectrometry (DEMS)1 and On-line Electrochemical Mass Spectrometry (OLEMS)2 have been used successfully to study reaction mechanisms to an ever-increasing degree in recent years, primarily in aqueous electrolytes. Similarly, Online Electrochemical Mass Spectrometers (OEMS)3 have been essential for the study of gas evolution in batteries.However, to gain an in-depth understanding of these mechanisms, the ability to accurately relate the electrochemical charge transferred in the reaction to the amount of evolved product is essential. To this end, accurate calibration of MS signals is paramount. Calibration procedures available for DEMS systems are by themselves cumbersome and unreliable and full quantification is not possible for OLEMS.Herein, we show how a simple gas-based calibration procedure using chip-based Electrochemistry-Mass Spectrometry (EC-MS) can be used for reliable, fully quantitative real-time analysis of volatile electrochemical reaction products. We validate this calibration with electrochemistry-based calibration methods described previously.4,5 The new procedure allows to extend the quantitative analysis to systems with no a priori knowledge of faradaic efficiencies. We demonstrate calibration of important gases like H2, O2 and C2H4 in aqueous and non-aqueous electrolytes and exemplify the calibration methodology’s usefulness on standard electrochemical reactions. References H. Baltruschat, J Am Soc Mass Spectrom, 15, 1693–1706 (2004).A. H. Wonders, T. H. M. Housmans, V. Rosca, and M. T. M. Koper, J Appl Electrochem, 36, 1215–1221 (2006).N. Tsiouvaras, S. Meini, I. Buchberger, and H. A. Gasteiger, J Electrochem Soc, 160, A471–A477 (2013).D. B. Trimarco et al., Electrochim Acta, 268 (2018).S. B. Scott, PhD thesis, Technical University of Denmark (2019). Figure 1: a) Schematic of the MS inlet chip’s working principle. b) Uncalibrated M2 and M32 signals (dotted lines) and the same signals after calibration for H2 and O2 (full lines) in a cyclic voltammogram of PtPoly in 0.1 M HClO4 obtained at room temperature at 20 mV/s. Figure 1

Heterologous expression of α-1,3-glucanase Agn1p from Schizosaccharomyces pombe, and efficient production of nigero-oligosaccharides by enzymatic hydrolysis from solubilized α-1,3;1,6-glucan.

The glycoside hydrolase family 71 α-1,3-glucanase (Agn1p) of Schizosaccharomyces pombe was expressed in Escherichia coli Rosetta-gami B (DE3). Agn1p (0.5nmol/mL) hydrolyzed insoluble α-1,3-glucan (1%), and about 3.3mm reducing sugars were released after 1440min of reaction. The analysis of reaction products by high-performance liquid chromatography revealed that pentasaccharides accumulated in the reaction mixture as the main products, along with a small amount of mono-, di-, tri-, tetra-, and hexasaccharides. Soluble glucan was prepared from insoluble α-1,3;1,6-glucan by alkaline and sonication treatment to improve the hydrolytic efficiency. As a result, this solubilized α-1,3;1,6-glucan maintained a solubilized state for at least 6h. Agn1p (0.5nmol/mL) hydrolyzed the solubilized α-1,3;1,6-glucan (1%), and about 8.2mm reducing sugars were released after 240min of reaction. Moreover, Agn1p released about 12.3mm reducing sugars from 2% of the solubilized α-1,3;1,6-glucan.

Unexpected electrochemical oxidation of urea on a new NiCuGO composite catalyst

The NiCuGO composite catalyst for urea electrooxidation was prepared using the electrodeposition method. Prepared material has shown ipA of 5.88 mA cm−2 at 514 mV during CV scan and 10 mA cm−2 at 693 mV during LSV in 0.15 M urea in 1 M KOH solution. The reaction mechanism was examined during bulk electrolysis with the periodic sampling and reaction products analysis. We found that the reaction efficiency was higher for our catalyst, with lower clamping voltages with respect to pure nickel. However, analysis with IC has shown that UOR using a NiCuGO electrode has led to a higher content of NO2− ions. The presence of this type of by-product in wastewater is a major environmental threat, which is why further research is needed for catalyst optimisation. It also shows that the widely agreed mechanism of UOR with Ni-based catalysts leading to N2, CO2, and H2O is not accurate in some cases and how crucial product analysis is for the catalyst evaluation.

EvdS6 is a bifunctional decarboxylase from the everninomicin gene cluster

The everninomicins are bacterially produced antibiotic octasaccharides characterized by the presence of two interglycosidic spirocyclic ortho-δ-lactone (orthoester) moieties. The terminating G- and H-ring sugars, L-lyxose and C-4 branched sugar β-D-eurekanate, are proposed to be biosynthetically derived from nucleotide diphosphate pentose sugar pyranosides; however, the identity of these precursors and their biosynthetic origin remain to be determined. Herein we identify a new glucuronic acid decarboxylase from Micromonospora belonging to the superfamily of short-chain dehydrogenase/reductase enzymes, EvdS6. Biochemical characterization demonstrated that EvdS6 is an NAD+-dependent bifunctional enzyme that produces a mixture of two products, differing in the sugar C-4 oxidation state. This product distribution is atypical for glucuronic acid decarboxylating enzymes, most of which favor production of the reduced sugar and a minority of which favor release of the oxidized product. Spectroscopic and stereochemical analysis of reaction products revealed that the first product released is the oxidatively produced 4-keto-D-xylose and the second product is the reduced D-xylose. X-ray crystallographic analysis of EvdS6 at 1.51Å resolution with bound co-factor and TDP demonstrated that the overall geometry of the EvdS6 active site is conserved with other SDR enzymes and enabled studies probing structural determinants for the reductive half of the net neutral catalytic cycle. Critical active site threonine and aspartate residues were unambiguously identified as essential in the reductive step of the reaction and resulted in enzyme variants producing almost exclusively the keto sugar. This work defines potential precursors for the G-ring L-lyxose and resolves likely origins of the H-ring β-D-eurekanate sugar precursor.