Inactive Substrate Research Articles

#2283 Vitamin D metabolism in end stage kidney failure: people receiving haemodialysis can still synthesise 1,25-dihydroxyvitamin D

Abstract Background and Aims A large proportion of haemodialysed patients remain vitamin D deficient, contributing to the development, and severity, of chronic kidney disease-mineral bone disorder (CKD-MBD). This study aimed to investigate the effect of vitamin D (cholecalciferol) supplementation on serum levels of 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 in a group of people receiving haemodialysis. Method Eighty-one haemodialysis patients (dialysis vintage ≥1 month) with low serum total 25(OH)D consented to participate. 40,000IU cholecalciferol was given weekly for 12-weeks followed by a maintenance dose of 20,000IU fortnightly (administered by dialysis nursing staff as part of routine care). Patients remained on active vitamin D (1,25(OH)2D3 and analogues) as part of routine care (clinician prescribed for management of calcium and PTH). Baseline and 12-month data were compared using related-samples Wilcoxon signed rank test (Table 1). NHS research ethics committee approval was received. Results Complete data were available and analysed for 55 patients. 1,25(OH)2D3 levels were low at baseline (48.3pmol/L, IQR 35.9-57.9pmol/L) despite 44 of 55 patients (80%) being prescribed an active vitamin D analogue (normal range 60-120pmol/L). Cholecalciferol supplementation normalised both serum 25(OH)D3 and 1,25(OH)2D3 and significantly increased 24,25(OH)2D3 (Table 1). Conclusion Synthesis of 1,25(OH)2D3 is maintained (in kidney failure) but is substrate dependent, and low serum 25(OH)D was evident at baseline. 1,25(OH)2D3 deficiency is therefore partly a consequence of 25(OH)D deficiency, rather than solely due to elevated FGF23 and reduced renal 1α-hydroxylase activity (which is shown to be present in kidney failure). Cholecalciferol supplementation increases the inactive substrate 25(OH)D3 rather than directly increasing 1,25(OH)2D3. Increases in 25(OH)D3 and 24,25(OH)2D3 are disproportionate to 1,25(OH)2D3 increases, demonstrating the known tight regulation of 1,25(OH)2D3 synthesis and secretion (in response to calcium and parathyroid hormone). Conventional oral vitamin D supplementation may provide a cheap and safe strategy for the management of vitamin D homeostasis in chronic kidney disease.

The adrenomedullin system and risk of cardiogenic shock or death complicating acute coronary syndromes

Abstract Introduction Cardiogenic shock (CS) is the leading cause of death due to acute coronary syndromes (ACS) and mortality remained nearly unchanged over the past two decades. Immediate revascularization of the infarct-related artery is the treatment strategy of choice to reduce CS-related mortality, but early identification of patients at high risk of CS and death is challenging. The adrenomedullin (ADM) system modulates vascular tone and endothelial barrier function and monitoring its activity may enhance early risk assessment of ACS patients prone to experience CS and ultimately death. Methods In 4293 ACS patients, prospectively recruited at 4 Swiss university hospitals, the 3 major ADM system components were assessed in plasma at the time of acute presentation by blinded study personnel: ADM-glycine (its inactive substrate), peptidylglycine α-amidating monooxygenase (PAM; the ADM-amidating enzyme), and the biologically active ADM-amide (bio-ADM). Patients were monitored for in-hospital development of CS and followed at 30 days and 1 year with external event adjudication. The relationship of each ADM system component with features of CS pathophysiology (such as proxies for the decrease in cardiac contractile mass, increase in cardiac stress or systemic inflammation) was estimated by means of partial correlation coefficients. Multivariable-adjusted regression models were fit to assess their independent association with CS development and death. Results Baseline ADM-glycine, PAM and bio-ADM levels were tightly linked to features of CS (Fig. 1), with each ADM system component associating with in-hospital CS (odds ratio, 95% confidence interval [CI] per doubling in each, 2.04, 1.79-2.33, P<.001; 1.91, 1.63-2.23, P<.001; 1.72, 1.11-2.66, P=.016). The association of each marker with CS remained robust after adjusting for established risk factors for in-hospital development of CS, including all hemodynamic-, patient-, and procedure-related variables informing the ORBI risk score (1.65, 1.35-2.00, P<.001; 1.50, 1.26-1.77, P<.001; and 1.87, 1.13-3.11, P=.015). Notably, integration of ADM-glycine, PAM, and bio-ADM into the ORBI risk prediction model conferred increased discriminative performance for the prediction of in-hospital CS (AUC, 0.76 vs. 0.81, P<.001), ranking the ADM system second among all variables informing the score (Fig. 2). While both ADM-glycine and bio-ADM independently associated with mortality risk at 30-days (multivariable-adjusted hazard ratio per doubling, 95% CI, 1.93, 1.54-2.42, P<.001; and 1.81, 1.34-2.44, P<.001) and 1-year (1.41, 1.18-1.68, P<.001; and 1.52, 1.24-1.87, P<.001), PAM showed no association with these outcomes (P>.05). Conclusions Monitoring key regulators of the ADM system improves early risk assessment of ACS patients at high risk of CS, with admission ADM-glycine and bio-ADM representing independent risk factors for 30-day and 1-year mortality post-ACS.

Loading IrOx Clusters on MnO2 Boosts Acidic Water Oxidation via Metal-Support Interaction.

Noble metal-based electrocatalysts are crucial for efficient acidic water oxidation to develop green hydrogen energy. However, traditional noble metal catalysts loaded on inactive substrates show limited intrinsic catalytic activity, and their large sizes have compromised the atom efficiency of these noble metals. Herein, IrOx nanoclusters with sizes below 2 nm, displaying high atom-utilization efficiency of Ir species, were supported on a redox-active MnO2 nanosubstrate (IrOx/MnO2) with different phases (α-MnO2, δ-MnO2, and ε-MnO2) to explore the optimal combination. Electrochemical measurements showed that IrOx/ε-MnO2 had excellent OER performance with a low overpotential of 225 mV at 10 mA cm-2 in 0.5 M H2SO4, superior to its counterpart, IrOx/α-MnO2 (242 mV) and IrOx/δ-MnO2 (286 mV). Moreover, it also delivered robust stability with no obvious change in operating potential at 10 mA cm-2 during 50 h of continuous operation. Combining the XPS results and Bader charge analysis, we demonstrated that the strong metal-support interactions of IrOx/ε-MnO2 could effectively regulate the electronic structures of the active Ir atoms and stabilize IrOx nanoclusters on supports to suppress their detachment, resulting in significantly enhanced catalytic activity and stability for acidic OER. DFT calculations further supported that the enhanced catalytic OER performance of IrOx/ε-MnO2 could be ascribed to the appropriate strength of interactions between the active Ir sites and the reaction intermediates of the potential-determining step (*O and *OOH) regulated by the redox-active substrates.

Development of sustainable green catalysts for oxidation of alcohols via decorated palladium nanoparticles on magnetic carbon nanotube/MOF

Using a straightforward method, this study fabricated an eco-friendly low-cost magnetic nanocomposite consisting of magnetic carbon nanotube/MOF as a stabilizer. Pd nanoparticles (Pd NPs) were then decorated on the designed magnetic carbon nanotube/MOF microspheres, and the resulting magnetic carbon nanotube/MOF/Pd NPs nanocomposite were employed as heterogeneous catalysts in Aerobic oxidation of primary and secondary alcohols. The attractiveness of this work is in the selective oxidation of several types of active and inactive alcohol substrates. The most important feature of this catalyst is its successful recovery and simple separation repeatedly without reducing its activity and selectivity. The active surface area of this Nanocatalyst is very large due to its structural properties, and as a result, it provides more available catalytic sites, which increases its activity. The identification techniques used to investigate the structural properties of this Nanocatalyst confirm its successful synthesis and appropriate palladium loading into the catalyst sites. The oxidation of alcohols was determined by Gas Chromatography (GC). The 100% selectivity, excellent turnover number (TON), high yield, almost complete and fast conversion of alcohol to the desired aldehydes and ketones without more oxidation, and easy and no-trouble isolation of product and catalyst are outstanding features of this catalytic system. The use of picolinaldehyde lead to the high loading of Pd NPs, reducing the catalyst content needed for the reaction. Regarding the high catalyst loading, using a small amount of catalyst is recommended for proceeding with the reaction efficiently.

Integration of atomic Co-N5 sites with defective N-doped carbon for efficient zinc-air batteries

Transition metal single-atom catalysts have attracted considerable attention for their applicability in electrocatalytic oxygen reduction reactions (ORR), but it is still very challenging to regulate the interaction between the active sites and oxygen-containing intermediates. In this study, atomically dispersed Co-N5 sites integrated with defective N-doped carbon (Co-N5/DHC) were developed using a facile templating approach, followed by NH3 treatment. NH3 can simultaneously etch inactive amorphous substrates on the surfaces of metal sites and construct intrinsic carbon defects, thereby increasing the number of both metal and metal-free active sites. By bridging the intrinsic carbon defects and metal sites, the optimized Co-N5/DHC catalyst exhibited significantly improved electrocatalytic ORR performance compared to the pristine Co-Nx/HC sample (cobalt-nitrogen sites anchored on heteroatom-doped carbon). Density functional calculations revealed that the strong interaction between the Co-N5 sites and carbon defects modified the electronic localization, thus optimizing the binding energy with oxygen-containing intermediates and resulting in significantly improved ORR catalytic activity with a half-wave potential of 0.877 V. In addition, a zinc-air battery assembled with the Co-N5/DHC as the cathode achieves a maximum power density of 160.7 mW cm−2 and affords a specific capacity of 766.2 mA h gZn−1.

Insight into the Mechanism Underlying Dehalococcoides mccartyi Strain CBDB1-Mediated B12-Dependent Aromatic Reductive Dehalogenation.

Anaerobic bacteria transform aromatic halides through reductive dehalogenation. This dehalorespiration is catalyzed by the supernucleophilic coenzyme vitamin B12, cob(I)alamin, in reductive dehalogenases. So far, the underlying inner-sphere electron transfer (ET) mechanism has been discussed controversially. In the present study, all 36 chloro-, bromo-, and fluorobenzenes and full-size cobalamin are analyzed at the quantum chemical density functional theory level with respect to a wide range of theoretically possible inner-sphere ET mechanisms. The calculated reaction free energies within the framework of CoI···X (X = F, Cl, and Br) attack rule out most of the inner-sphere pathways. The only route with feasible energetics is a proton-coupled two-ET mechanism that involves a B12 side-chain tyrosine (modeled by phenol) as a proton donor. For 12 chlorobenzenes and 9 bromobenzenes with experimental data from Dehalococcoides mccartyi strain CBDB1, the newly proposed PC-TET mechanism successfully discriminates 16 of 17 active from 4 inactive substrates and correctly predicts the observed regiospecificity to 100%. Moreover, fluorobenzenes are predicted to be recalcitrant in agreement with experimental findings. Conceptually, based on the Bell-Evans-Polanyi principle, the computational approach provides novel mechanistic insights and may serve as a tool for predicting the energetic feasibility of reductive aromatic dehalogenation.

Photoelectrochemical Deposition of Silicon–Carbon Layer on P-Type Semiconductors and Aluminum–Copper Alloy in Ionic Liquid

Electrochemical deposition of silicon at room temperature is problematic due to the intrinsically low conductivity of the deposits. This study reports the photoelectrochemical (PEC) deposition of silicon (Si) and silicon–carbon (Si–C) layers from an ionic liquid at 40 °C using silicon tetrachloride (SiCl4) as a silicon precursor. Amorphous layers are deposited on p-type silicon (p-Si), p-type gallium arsenide (p-GaAs), and aluminum–copper alloy AA2024. The semiconductor substrates are activated by white LED illumination, which generates photoelectrons, thereby making the substrate conductive with respect to the cathodic reaction. The photoresponsiveness of the deposits is proven by the light-induced photocurrents on an optically inactive substrate made of the alloy AA 2024. The proposed method paves the way for the electrochemical modification of semiconductors and metals with Si and Si–C structures, which are applicable in various fields, such as batteries, anti-corrosion coatings, photovoltaics, or PEC electrodes for hydrogen production.

Pd-Coordinated Salinidol-Modified Mixed MOF: An Excellent Active Center for Efficient Nitroarenes Reduction and Selective Oxidation of Alcohols.

Selective oxidation of active and inactive alcohol substrates and reduction of nitroarenes is a highly versatile conversion that remains a challenge in controlling functionality and adjustments in metal-organic frameworks (MOFs). On the other hand, it offers an attractive opportunity to expand their applications in designing the next generation of catalysts with improved performance. Herein, a novel mixed MOF consisting of supported 2-hydroxybenzamide (mixed MOF-salinidol) has been fabricated by post-synthetic modifications of mixed MOF. Subsequently, the prepared nanocomposites were modified to impart catalytic sites using palladium chloride ions mixed with MOF-salinidol/Pd (II). After successfully designing and structurally characterizing nanocomposites, we evaluated their activity in oxidizing primary and secondary alcohols using aerobic conditions with molecular oxygen and an air atmosphere. In addition, the stability of (mixed MOF-salinidol/Pd (II)) catalysts under catalytic conditions was also demonstrated by comparing the Fourier-transform infrared spectrum, scanning electron microscopy image, and ICP-OES method before and after catalysis. Based on the results, the active surface area of the synthesized nanocatalyst is large, which highlights its unique synergistic effect between post-synthetic modified MOF and Pd, and furthermore, the availability of catalytic sites from Pd, as demonstrated by outstanding catalytic activity.

Controlled Membrane Transport in Polymeric Biomimetic Nanoreactors.

Polymersome-based biomimetic nanoreactors (PBNs) have generated great interest in nanomedicine and cell mimicry due to their robustness, tuneable chemistry, and broad applicability in biologically relevant fields. In this concept review, we mainly discuss the state of the art in functional polymersomes as biomimetic nanoreactors with membrane-controlled transport. PBNs that use environmental changes or external stimuli to adjust membrane permeability while maintaining structural integrity are highlighted. By encapsulating catalytic species, PBNs are able to convert inactive substrates into functional products in a controlled manner. In addition, special attention is paid to the use of PBNs as tailored artificial organelles with biomedical applications in vitro and in vivo, facilitating the fabrication of next-generation artificial organelles as therapeutic nanocompartments.

A sustainable protocol for selective alcohols oxidation using a novel iron-based metal organic framework (MOF-BASU1).

The selective oxidation of active and inactive alcohol substrates is a highly versatile conversion that poses a challenge in controlling the functionality and adjustments on MOFs. On the other hand, it offers an attractive opportunity to expand their applications in designing the next generation of catalysts with improved performance. Herein, a novel iron-based MOF containing sulfonamide (MOF-BASU1) has been fabricated by the reaction of 1,3-benzene disulfonylchloride linker and FeCl3·6H2O. Based on the results, the active surface area of the synthesized MOF is large, which highlights its unique catalytic activity. Optimum conditions were reached after 0.5-2 h, with 15 mg loading of the synthesized MOF under optimal conditions. Furthermore, the turnover frequency was 18-77.6 h-1, which is comparable to values previously reported for this process. Overall, the high catalytic activity observed for MOF-BASU1 might be because of the obtained high surface area and the Lewis acidic Fe nodes. Furthermore, the MOF-BASU1 revealed a remarkable chemoselectivity for aldehydes in the presence of aliphatic alcohols. Overall, the high product yields, facile recovery of nanocatalysts, short reaction times, and broad substrate range make this process environmentally friendly, practical, and economically justified.

The role of vitamin D in periodontal health and disease.

Vitamin D plays an essential role in calcium and bone metabolism, immune regulation and possesses profound anti-inflammatory effects. Evidence suggests that low serum vitamin D is associated with increased severity of periodontitis, a chronic inflammatory condition characterised by destruction of the supporting tissues surrounding the tooth, which has several shared risk factors with other chronic non-communicable diseases. The biological functions of vitamin D are mediated by its strong anti-microbial, anti-inflammatory, and host modulatory properties. Experimental periodontitis models involving targeted deletion of 1α-hydroxylase, the enzyme responsible for the conversion of inactive substrate to active 1,25(OH)2 D3 (calcitriol), showed augmented alveolar bone loss and gingival inflammation. Vitamin D receptor (VDR) gene polymorphisms have also been associated with increased severity of periodontitis. Thus, the involvement of vitamin D in the pathogenesis of periodontitis is biological plausible. Clinical studies have consistently demonstrated an inverse relationship between serum 25OHD3 and periodontal disease inflammation. However, due to the paucity of well-designed longitudinal studies, there is less support for the impact of vitamin D status on periodontal disease progression and tooth loss. The evidence emphasises the importance of maintaining vitamin D sufficiency in supporting periodontal health. This review aims to first examine the biological mechanisms by which vitamin D might influence the pathogenesis of periodontal disease and second, discuss the clinical evidence which implicate the role of vitamin D in periodontal disease.

Nanomaterial-based sandwich-type electrochemical aptasensor platform for sensitive voltammetric determination of leptin.

A sandwich-type electrochemical aptasensor was designed for sensitive detection of leptin in biological samples, including human serum and human plasma. The developed aptasensor was produced by electrodeposition of gold nanoparticles on a screen-printed electrode modified with zinc oxide nanoparticles. The synergy effect of zinc oxide and gold nanoparticles improved the electrocatalytic activity of the aptasensor. The obtained high surface area allowed more aptamer molecules to be loaded on the electrode surface. Signal amplification significantly increases the detection sensitivity of a developed biosensor. Although the use of nanomaterials is the most preferred detection tool for this purpose, as an alternative, enzyme-catalyzed signal amplification is widely used in the construction of a biosensor due to its specificity and high catalytic efficiency. Therefore, both nanomaterial-supported and an alkaline phosphatase-based aptasensor design were developed, which can produce in situ electroactive product by enzymatic hydrolysis of the inactive substrate to achieve a higher signal-to-background ratio. Under optimal conditions, the developed aptasensor exhibited a wide linear concentration range from 0.01 pg mL-1 to 100.0 pg mL-1 with a detection limit of 0.0035 pg mL-1. While the developed aptasensor provided excellent selectivity in the presence of some interfering compounds, it possessed outstanding reproducibility and stability. In addition, the developed aptasensor has been applied with good recoveries in the range 96.31 to 108.79% in human serum and plasma samples. In conclusion, all the obtained results showed the feasibility of the developed aptasensor for practical applications.

Functional Chemical Motor Coatings for Modular Powering of Self-Propelled Particles.

Inspired by the locomotion of semiaquatic insects, a variety of surface swimming microrobots propelled by surface tension Marangoni forces have been developed over the years. However, most Marangoni micromotor systems present limitations in their applications due to poor performance, short lifetime, low efficiency, and toxicity. We have developed a functional chemical motor coating consisting of protein microfilms with entrapped fuel to functionalize inactive substrates or particles. This motor material system generates large Marangoni propulsive forces with extremely small amounts of fuel due to a self-regulated fuel release mechanism based on dynamic nanostructural changes in the protein matrix, enhancing the lifetime and efficiency performance over other material systems and motors. These motor functional coatings offer great versatility as they can be coated on a wide array of substrates and materials across length scales, with opportunities as modular power sources for microrobots and small-scale devices. The synergy between the protein motor matrix and the chemical fuel enables the wider design of self-powered surface microrobots without previous limitations in their fabrication and performance, including the new design of hybrid microrobots with protein functional coatings as a modular power source.

Array of Interdigitated Bipolar Electrodes for the Selective Capture and Analysis of Melanoma Cells

In this work, we develop an array of biosensors for the selective dielectrophoretic capture and electrochemical detection of single to few melanoma cells. Each biosensor in the array consists of a gold thin film interdigitated bipolar electrode (IDBPE) patterned on a glass substrate. Microwells are patterned over the interdigitated end of each IDBPE to restrict the number of cells captured and to retain cells on the electrodes for subsequent analysis. An overlying microfluidic channel controls delivery of the cell sample to the microwells. Cells are attracted to the interdigitated electrode by a positive dielectrophoretic force, thereby pulling them into the microwells, where they remain trapped during the next step – introduction of reagents for electrochemical enzyme-linked immunosorbent assay (eELISA). The dimensions of the wells, solution flow rate, and AC voltage applied all support the retention of the cells on the electrodes once they are captured.A bipolar electrode (BPE) is a conductor, which in the presence of an externally applied electric field, facilitates electrically coupled faradaic reactions at its opposing ends. In the context of analysis, a sensing reaction at one pole of the BPE is coupled to a reporting reaction, which produces a visual signal at the opposite pole. Because of their wireless operation, arrays of tens to thousands of BPEs can be operated in parallel with a single power supply – an advantageous feature for parallel analysis of few or single cells. However, traditional BPEs with electrogenerated chemiluminescence (ECL) as the reporting reaction do not provide sufficient sensitivity for biologically relevant detection limits, and therefore, require a means of signal amplification for such applications. To address this issue, we previously developed IDBPEs, which facilitate redox cycling by interdigitation of the sensing pole of each BPE of an array with a shared driving electrode, thereby yielding more intense ECL at the reporting pole.1 In the present study, the interdigitated end of the IDBPE is utilized for eELISA to quantify the expression of a cell surface antigen, melanoma cell adhesion marker (MCAM). Cells are labelled with biotinylated anti-human MCAM and alkaline phosphatase (ALP) conjugated streptavidin. Once cells are captured, the redox inactive substrate, para-aminophenyl phosphate (PAPP), is flowed through the microchannels and ALP catalyzes its conversion to the redox active species para-aminophenol (PAP). The amplified current obtained at each IDBPE by the redox cycling of PAP and its oxidized form, quinone imine (QI), is reported by an ECL reaction on its opposing pole. The ECL signal obtained at each IDBPE is correlated to the expression level of MCAM on the melanoma cells isolated in the corresponding well. This work is significant because it allows for the sensitive detection of melanoma cells in a device amenable to point-of-care application by combining selective enrichment of malignant cells by dielectrophoresis with the amplification and facile arraying afforded by IDBPEs. Borchers, J.S., Campbell, C.R., Van Scoy, S.B., Clark, M.J. and Anand, R.K. (2021), Redox Cycling at an Array of Interdigitated Bipolar Electrodes for Enhanced Sensitivity in Biosensing. ChemElectroChem. https://doi.org/10.1002/celc.202100523

Three-Dimensional Monolithically Self-Grown Metal Oxide Highly Dense Nanonetworks as Free-Standing High-Capacity Anodes for Lithium-Ion Batteries.

Transition metal oxides (TMOs) have been widely studied as potential next-generation anode materials, owing to their high theoretical gravimetric capacity. However, to date, these anodes syntheses are plagued with time-consuming preparation processes, two-dimensional electrode fabrication, binder requirements, and short operational cycling lives. Here, we present a scalable single-step reagentless process for the synthesis of highly dense Mn3O4-based nanonetwork anodes based on a simple thermal treatment transformation of low-grade steel substrates. The monolithic solid-state chemical self-transformation of the steel substrate results in a highly dense forest of Mn3O4 nanowires, which transforms the electrochemically inactive steel substrate into an electrochemically highly active anode. The proposed method, beyond greatly improving the current TMO performance, surpasses state-of-the-art commercial silicon anodes in terms of capacity and stability. The three-dimensional self-standing anode exhibits remarkably high capacities (>1500 mA h/g), a stable cycle life (>650 cycles), high Coulombic efficiencies (>99.5%), fast rate performance (>1.5 C), and high areal capacities (>2.5 mA h/cm2). This novel experimental paradigm acts as a milestone for next-generation anode materials in lithium-ion batteries, and pioneers a universal method to transform different kinds of widely available, low-cost, steel substrates into electrochemically active, free-standing anodes and allows for the massive reduction of anode production complexity and costs.

Reprint of: 1-Aminocyclopropanecarboxylate Synthase, a Key Enzyme in Ethylene Biosynthesis

1-Aminocyclopropanecarboxylate (ACC) synthase, which catalyzes the conversion of S-adenosylmethionine (SAM) to ACC and methylthioadenosine, was demonstrated in tomato extract. Methylthioadenosine was then rapidly hydrolyzed to methylthioribose by a nucleosidase present in the extract. ACC synthase had an optimum pH of 8.5, and a Km of 20 μM with respect to SAM. S-Adenosylethionine also served as a substrate for ACC synthase, but at a lower efficiency than that of SAM. Since S-adenosylethionine had a higher affinity for the enzyme than SAM, it inhibited the reaction of SAM when both were present. S-Adenosylhomocysteine was, however, an inactive substrate. The enzyme was activated by pyridoxal phosphate at a concentration of 0.1 μM or higher, and competitively inhibited by aminoethoxyvinylglycine and aminooxyacetic acid, which are known to inhibit pyridoxal phosphate-mediated enzymic reactions. These results support the view that ACC synthase is a pyridoxal enzyme. The biochemical role of pyridoxal phosphate is catalyzing the formation of ACC by α,γ-elimination of SAM is discussed.

Non-Vent Megafaunal Communities on the Endeavour and Middle Valley Segments of the Juan de Fuca Ridge, Northeast Pacific Ocean

There has been increasing interest in mining polymetallic sulfide deposits at deep-sea inactive hydrothermal vents, leading to the development of regulations to minimize risk to the marine environment. While an extensive body of literature exists on the ecological communities at active vents, fauna at inactive hydrothermal vents and the vent periphery are poorly described and their vulnerability to disturbance is unknown. We examined patterns in abundance of non-vent epibenthic megafauna on two segments of the Juan de Fuca Ridge, Northeast Pacific Ocean. Video footage was collected by the remotely operated vehicle ROPOS during four dives at the Endeavour Segment and two dives at Middle Valley in August 2016. At the Endeavour Segment, the substrate is characterized predominantly by basalt and edifices of hydrothermal sulfide that range in hydrothermal activity from inactive to vigorous, high-temperature venting. In contrast, Middle Valley is heavily sedimented and most hydrothermal activity is low-temperature diffuse flow. While inactive substrates at both sites harboured slow-growing sessile fauna, the dominant members of the community differed between sites. At Endeavour, the most abundant morphotaxa included rossellid vase sponges, alcyonacean corals, and crinoids. Estimated richness and total abundance of morphotaxa was higher on hard substrates than sedimented substrates and highest on inactive chimneys. At Middle Valley, the most abundant morphotaxa included antipatharian corals, anemones, and ascidians. Species richness was higher on inactive chimneys and mixed substrates than sediment. The abundance of some megafauna varied with proximity to active vents. At Endeavour, deep-water corals were nearly absent within 25 m of active chimneys and very few occurred between 26 and 50 m from active chimneys. Rossellid vase sponges were in low abundance within 25 m of active chimneys but were more abundant than corals at 26-50 m from active chimneys. This project contributes baseline data on megafaunal assemblages on inactive hydrothermal vents and can provide the basis for more focused research on the structure and function of inactive vent ecosystems.

UV‐Induced C−H Functionalization of Alkanes with NO2 in Supercritical Carbon Dioxide

AbstractA novel catalyst‐free method for functionalization of unbranched alkanes via radical nitration with UV‐activated nitrogen oxide (IV) in supercritical carbon dioxide medium has been developed. The method allows to transform these inactive substrates into corresponding nitrates and nitro compounds with outstanding yields (up to 65 %), using available reagents (NO2, O2) under mild reaction conditions (35–50 °C), and exhibits lower hazards compared to conventional analogues. An improved selectivity towards the nitrates has been achieved by adding pure oxygen to the reaction. Based on changes in reaction rate and product composition, the plausible reaction mechanism for the UV‐induced C−H functionalization of alkanes with nitrogen oxide (IV) and pure oxygen has been proposed.

Operando Monitoring of Electrode Temperatures During Overcharge‐Caused Thermal Runaway

Lithium‐ion batteries’ (LIBs) failure due to abusive cycling conditions can result in thermal runaway, which calls for reliable real‐time battery thermal safety monitoring. Herein, an effective method for LIB thermal runaway detection using a resistant temperature detector (RTD) is compared with a conventional battery surface temperature measurement. A direct electrode temperature measurement technique based on additive manufacturing‐enabled application of miniature RTDs for measurement of internal temperature within large‐capacity Li‐ion pouch cells is used. The miniature RTDs are embedded in a customized electrochemically inactive polymeric substrate for real‐time thermal safety monitoring during overcharge abuse. Electrode temperature profiles under different conditions of overcharge (at 1 and 5 C rate, charged until battery explosion) are analyzed and mechanisms of heat generation in LIBs during overcharge‐induced thermal runaway are investigated. The internal RTDs detect the onset temperature of the solid−electrolyte interface decomposition ≈10 s earlier than the sensors attached to the battery surface. A maximum temperature gradient of ≈200 °C is observed between the electrode and the battery surface during overcharge‐induced thermal runaway. The internal RTDs are shown as a possible guide for sensor placement location to capture the maximum temperature within the LIBs during abuse events.

Ni(II) Schiff-Base Complexes as Chiral Electroauxiliaries and Methodological Platform for Stereoselective Electrochemical Functionalization of Amino Acids.

The concept of chiral electroauxiliary based on the redox active chiral platform to perform transformations of a redox inactive substrate is suggested and discussed in the context of the targeted stereoselective electrochemical functionalization of amino acids. Tailor-made amino acids are essential structural features of modern medicinal chemistry and drug design; the development of efficient synthetic approaches to these compounds is of topical interest. The modified substrate (an amino acid) is included as a structural motif in the redox active complex (with a possibility to be released after modification) that integrates "a bifunctional linker" (the structural motif capable to "catch" a substrate) and a chiral moiety responsible for asymmetry induction. The amino acid, being included as a part of such ensemble, becomes stable towards redox destruction and its targeted electrochemical modification saving the amino acid skeleton is possible, thus developing new modes of reactivity for well-known compounds.