CV Data Research Articles

Hematite Defect Development for Gallic Acid Sensing

AbstractNanostructured iron (III) oxide was prepared by a facile hydrothermal method using poly(triazine imide) (PTI) as a sacrificial template. The physicochemical properties of pristine iron oxide and its analogue obtained in the presence of PTI confirmed strong effect of the latter as the morphology improving agent. Moreover, application of nitrogen rich semiconducting polymer during hydrothermal synthesis increased number of defects. The obtained sample was used as an electroactive additive for carbon‐paste electrode. PTI‐modified sample demonstrated 1.52 times higher oxidation current, and 1.39 lower charge transfer resistance compared to hematite obtained without PTI, as was confirmed by CV and EIS data. Therefore, it was proposed to use the as a sensor for the detection of gallic acid. The developed method showed excellent linearity within a concentration range of 67 nM to 17.7 µM with a detection limit equal to 44 nM and limit of quantification of 132 nM. Stablitity and reproducibility tests, as well as real sample analysis confirmed applicability of the proposed sensor for practical application. Excellent electrochemical properties of the submicron hematite particles are attributed to the developed lattice defects, which served as reaction centers and charge transducing points.

Synthesis, Characterization and Electrochemical Performance of Bi2S3/Rice Husk-Based Activated Carbon Composites As Lithium Ion Battery Anodes

This study investigates the impact of hydrothermal duration on bismuth sulfide/activated carbon composites (Bi2S3/AC) by varying the duration to 8, 24, and 48 hours. The primary aim is to delineate the composite characteristics and electrochemical performance of Bi2S3/AC composites, aiming to produce anodes for lithium-ion batteries with high capacity, excellent cyclic stability, and minimal volume expansion. Activated carbon derived from rice husks was synthesized via a carbonization process and chemical activation using H3PO4 as an activator. Subsequently, the synthesis of Bi2S3/AC composites used bismuth nitrate pentahydrate and thiourea precursors through the hydrothermal method that involved three variations of hydrothermal duration: 8, 24, and 48 hours, denoted as BC8, BC24, and BC48, respectively. The FTIR test indicates the presence of Bi-S, C=C, and C-O groups in the three composite products, signifying the existence of bismuth sulfide and activated carbon. The XRD result reveals orthorhombic crystal forms in the composites, while the SEM-EDX mapping illustrates particle morphologies resembling flower-like shapes. These compositions comprise Bi 74.16%, S 11.37%, and C 10.43%. The GSA test suggests a mesoporous pore size in these composites. In final result, BC24 exhibits the highest electrical and ionic conductivity, measuring 2.12 × 10−3 S.cm−1 and 2.057 × 10−4 S.cm−1, respectively. The CV data of the BC24 composite indicates two reduction and oxidation peaks in the first cycle. Charge-discharge test on the BC24 composite exhibits a specific charge capacity of 445.51 mAh/g and a discharge capacity of 364.24 mAh/g.

Comparison of the impact of dimensionality reduction and data splitting on classification performance in credit risk assessment

Credit risk assessment (CRA) plays an important role in credit decision-making process of financial institutions. Today, developing big data analysis and machine learning methods have marked a new era in credit risk estimation. In recent years, using machine learning methods in credit risk estimation has emerged as an alternative method for financial institutions. The past demographic and financial data of the person whose CRA will be performed is important for creating an automatic artificial intelligence credit score prediction model based on machine learning. It is also necessary to use features correctly to create accurate machine learning models. This article aims to investigate the effects of dimensionality reduction and data splitting steps on the performance of classification algorithms widely used in the literature. In our study, dimensionality reduction was performed using Principal Component Analysis (PCA). Random Forest (RF), Logistic Regression (LR), Decision Tree (DT), Naive Bayes (NB) algorithms were chosen for classification. Percentage splitting (PER, 66–34%) and k-fold (k = 10) cross-validation techniques were used when dividing the data set into training and test data. The results obtained were evaluated with accuracy, recall, F1 score, precision, and AUC metrics. German data set was used in this study. The effect of data splitting and dimension reduction on the classification of CRA systems was examined. The highest ACC in PER and CV data splitting was obtained with the RF algorithm. Using data splitting methods and PCA, the highest accuracy was observed with RF and the highest AUC with NB, with 13 PCs in which 80% of the variance was obtained. As a result, the data set consisting of a total of 20 features, expressed by 13 PCs, achieved similar or higher success than the results obtained from the original data set.

Facile Synthesis of U2Ti Intermetallic by Direct Electrochemical Reduction of UO2-TiO2 Composite in LiCl-Li2O Melt

Alloys of U with Ti are of importance in nuclear industry as fuel for Gen IV fast reactors, hydrogen isotope storage medium for fusion reactors, super conductors, and also as corrosion resistant material for use in various applications. Here, preparation of U2Ti intermetallic compound was investigated by the direct electrochemical reduction of mixed oxide of UO2-TiO2 in LiCl-0.5% Li2O molten salt at 650 °C. The mixed oxide pellet of UO2-TiO2 sintered at 1500 °C was found to be a mixture of UTi2O6 and UO2 as evidenced by X-ray diffraction (XRD) analysis. Direct electro-lithiothermic reduction of UO2, TiO2, and a mixture of sintered UO2-TiO2 and UTi2O6 coupled with cyclic voltammetry of these oxides in the melt was performed to understand the electro-reduction mechanism. Potentials of reduction of these oxides in the melt, w.r.t Ni/NiO reference electrode, obtained by analysis of CV data of these oxides contained in metallic cavity electrodes and XRD analysis of partially electro-reduced oxides were used to arrive at the electro-reduction mechanism. Results indicate that U2Ti can be prepared conveniently by the electro-lithiothermic reduction of sintered pellet of UO2-TiO2 cathode by constant current electrolysis in a two-electrode cell.

Contrast Volume-to-Estimated Glomerular Filtration Rate Ratio as a Predictor of Short-Term Outcomes Following Transcatheter Aortic Valve Implantation.

Background/Objectives: Contrast-induced acute kidney injury (AKI) is associated with early mortality and adverse events. However, in the setting of transcatheter aortic valve implantation (TAVI), previous literature has failed to establish a correlation between the absolute volume of contrast media administered and mortality. We aimed to investigate the impact of contrast volume administered normalised to estimated glomerular filtration rate (CV/eGFR) on the development of AKI and on 30-day all-cause mortality in TAVI patients. Methods: We retrospectively analysed a cohort of 1150 patients who underwent TAVI at our unit between 2015 and 2018. Results: Follow-up was complete for 1064 patients. There were 23 deaths within the follow-up period and 76 cases of AKI, 9 of which required new renal replacement therapy (RRT). Receiver-operating characteristic (ROC) curve analysis showed fair discrimination for 30-day all-cause mortality at a CV/eGFR ratio of 3.6 (area under the ROC curve (AUC) 0.671). Of patients in whom CV data were available, 86.0% (n = 757) had a CV/eGFR < 3.6 and 14.0% (n = 123) had a CV/eGFR ≥ 3.6. In multivariate logistic regression analysis, CV/eGFR ≥ 3.6 was the strongest predictor of 30-day all-cause mortality (odds ratio 5.06, 95% confidence interval [1.61-15.7], p = 0.004). Other independent predictors were procedural urgency (3.28 [1.04-10.3], p = 0.038) and being under general anaesthesia (4.81 [1.10-17.3], p = 0.023). CV/eGFR ≥ 3.6 was also independently associated with significantly increased odds of AKI (2.28 [1.20-4.17], p = 0.009) alongside significant non-left main stem coronary artery disease (2.56 [1.45-4.66], p = 0.001), and diabetes (1.82 [1.03-3.19], p = 0.037). In supplementary ROC curve analysis, a similar CV/eGFR cut point of 3.6 was found to be an excellent predictor for new RRT (AUC 0.833). Conclusions: In conclusion, a CV/eGFR ≥ 3.6 post-TAVI was found to be a strong predictor of 30-day mortality and AKI. The maximum contrast volume that can be safely administered in each patient without significantly increasing the risk of mortality and AKI can be calculated using this ratio.

Moving in Academia: Who Moves and What Happens After?

We study labor mobility among academic economists in the United States. Analyzing CV data from over 6,000 economists at Research 1 institutions, we document that female assistant and associate professors are 8 percentage points less likely to move with promotion than their male counterparts. Women are also more likely than men to relocate to lower-ranked institutions. Event study graphs reveal that men working in departments that receive a new faculty member see their publication output increase by more than twice as much as that of women in these departments. Our findings highlight significant gender differences in who moves and what happens after.

Giving and receiving: Gendered service work in academia

Deploying the perspective of ‘relational work’, this article investigates the mechanisms behind the gender-unequal distribution of academic service. The concept of relational work is used to analyse how men and women in academia balance collective against individual interests when agreeing or disagreeing on service tasks. Four types of relational work are identified: compliance, evasiveness, barter and investment, with compliance being more common among women, evasiveness and barter being more common among men and investment being tied to temporality in a gendered pattern. The article shows that men are more successful in pursuing individual interests against service demands and how this depends on their relational work as well as organisational role expectations, reducing women’s prospects of ‘saying no’. The study is based on qualitative interviews with 163 associate and full professors in the social sciences and CV data on their service contributions.

Composition-dependent band structure parameters and band-gap bowing effect in a caesium lead mixed halide system: a cyclic voltammetry investigation.

Cyclic voltammetry techniques have been employed to study the effect of halide substitution on the band edge parameters and band gap bowing effect in the case of CsPbX3 [X = I, Br, Cl] perovskite nanocrystals (PNCs). A series of compositions, viz. CsPbI3, CsPb(I-Br)3, CsPbBr3, CsPb(Br-Cl)3 and CsPbCl3, have been prepared by a hot injection method. From powder XRD and HR-TEM analysis, the formation of a highly crystalline, cubic phase of the perovskite having size in the range from 7-20 nm has been confirmed. Sharp peaks in the photoluminescence spectra suggest the formation of quantum dots with narrow-size distribution. The composition-dependent optical band gap (εopgap) for CsPbX3 displays a systematic shift towards shorter wavelengths from I to Br to Cl substitutions. The cyclic voltammetry investigation on the dispersion of PNCs in nonaqueous solvents yielded prominent cathodic and anodic peaks. These are correlated to conduction (e1) and valence band edge (h1) positions, respectively. The h1 has been decreased substantially with I to Br to Cl in CsPbX3. Meanwhile, e1 shows a marginal increase. The values derived from CV data demonstrated an excellent match with UVPS results, reported for a similar system. From these results, the quasi-particle gap (εqpgap) and exciton binding energy have been estimated for all the compositions. The negative band gap bowing effect noted in these PNCs is attributed to the size quantization effect. The band-edge parameters reported in this work will be valuable in matching these heterojunctions with suitable electron/hole transport materials for optimum device-performance.

Synthesis and study of rare earth(Dy3+) doped CoCr2O4 ceramics for supercapacitor applications

Rare earth doped Cobalt Chromates are exhibits a significant interest among other materials for supercapacitors Applications. In the present work we reported Dysprosium(Dy3+) doped Cobalt Chromate(CoCr2O4) for possible application in supercapacitors. Samples were prepared by solution combustion method with the general formula CoCr2-xDyxO4 (where x = 0, 0.01, 0.03, and 0.05) using glucose and urea as fuels. As prepared samples were characterized by using “X-ray diffractometer”(XRD), “Transmission electron microscopy”(TEM), and “field emission scanning electron microscopy(FESEM) techniques to study the analytical and morphological structure of the CoCr2-xDyxO4. For the first time, the electrochemical fabrication of CoCr2-xDyxO4 were reported. Using “cyclic voltammetry”(CV), “galvanostatic charge–discharge’(GCD), electrochemical impedance spectroscopy (EIS), and cyclic stability testing, the electrochemical capabilities of CoCr2-xDyxO4 were explored in great detail. The behavior of capacitance was evaluated utilizing CV at a variety of scan speeds, GCD at a selection of constant current densities, and EIS at a selection of frequencies. CV and GCD data for tested electrodes showed their capacitive behavior. The calculated capacitance was 0.29–0.38 F cm−2. It is found increasing with Dy3+ concentration. Based on CV testing results at a scan rate of 1 mV s−1. At a current density of 3 mA cm2, the obtained capacitance was 0.21, 0.22 and 0.23 F cm−2 respectively. The analysis of the compared Nyquist plots of complex impedance revealed that the actual part of the impedance dropped as the Dy3+ content increased. This pointed to an increase in conductivity, which was advantageous for the storage of charge, as also supported by density of states calculations, which demonstrated the remarkable distribution of density of states across the fermi level after Dy3+ doping in CoCr2O4, indicating improved electronic features of CoCr2-xDyxO4.

Revealing the surface modification effect on Li-ion insertion into Ni-rich NCM cathode material by cyclic voltammetry

This article presents a new approach to the determination of electrochemical parameters characterizing the degradation behavior of electrodes based on LiNi0.85Co0.10Mn0.05O2 (Ni-rich NCM) using the method of cyclic voltammetry with a linear scan of the electrode potential (CV). To establish the relationship between electrochemical, structural, and morphological characteristics, XRD, synchrotron XRD (SXRD) in the operando mode, and SEM were used. The results of the galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) were used to verify the CV data. The features of the irreversible phase transition in NCM during the first cycle of extraction-insertion of lithium ions and its influence on the further behavior of the material during cycling were studied. It was found that the nature of the slope variation of capacity and coulomb efficiency dependences on the cycle number with an increase in the electrode potential scan rate is a criterion for the ratio of reversible and irreversible components of the electrode capacity degradation. Reversible electrode capacity degradation is due to the difference between the diffusion coefficients of lithium ions in the anodic and cathodic processes, irreversible degradation is due to the structural degradation of the material. For NCM samples with different particle surface conditions (with different composition of Cathode Electrolyte Interphase (CEI)) the values of Li+ ions diffusion coefficient (D) for each stage of the intercalation process were found in the range 4.5·10−14 – 1.2·10−13 cm2·s−1 for the anodic process, 1.7·10−14 – 5.6·10−14 cm2·s−1 for the cathodic process. It has been established that the reversible and irreversible degradation components of electrodes based on Ni-rich NCM in the potential range corresponding to the H2-H3/H3-H2 interphase transition correlate with each other. Therefore, the difference in D values in the anodic and cathodic processes, which correspond to the current peaks of the cyclic voltammogram in this region, is a criterion for the irreversible degradation of the material’s capacity: the greater the difference in the D values for these peaks, the higher the irreversible degradation of the material’s capacity.

Comparison of Antiaromatic Properties in a Series of Structurally Isomeric Naphthothiophene-fused s-Indacenes.

Fusion of aromatic subunits to stabilize an antiaromatic core allows the isolation and study of otherwise unstable paratropic systems. A complete study of a series of six naphthothiophene-fused s-indacene isomers is herein described. Additionally, the structural modifications resulted in increased π-π overlap in the solid state, which was further explored through changing the sterically blocking mesityl group to (triisopropylsilyl)ethynyl in three derivatives. The computed antiaromaticity of the six isomers is compared to the observed physical properties, such as NMR chemical shift, UV-vis, and CV data. We find that the calculations predict the most antiaromatic isomer and give a general estimation of the relative degree of paratropicity for the remaining isomers, when compared to the experimental results.

Synthesis and characterization of CoX2O4 nanostructured oxides

In this manuscript, four cobalt-based oxides (in the form of CoX2O4, where X was either Fe,Cu, Ni or Zn) were synthesized via sol-gel methodology. The four oxides were characterized by XRD, showing the quality of these materials, the crystal structure of each one of them and the anticipated scale size of their particles. TGA was applied to investigate their thermal stability, and CoFe2O4 showed the best stability. SEM was utilized to see the morphology of these oxides, where the images of each material was in good agreement with the XRD data. SEM images confirmed that the synthesized oxides in this work were nanomaterials. Magnetism behavior of CoFe2O4 and CoNi2O4 was noticed due to the agglomeration of particles. Electrochemical analysis was done on these oxides. CV results showed how CoZn2O4 performed the best among the other composites, showing a high-quality demonstration of EDL capacitive behavior. Discharge data of CoZn2O4 was in great alignment with its CV data in proving the outstanding electron movement. The discharge behavior also showed how the electrical stability or capacitance of CoZn2O4 was excellent. LSV results represented the performance of each composite, and how CoNi2O4 gave the best behavior in this test, which suggested the possibility of an excellent performance in water splitting experiments.

Investigation of the Electrochemical Behaviour of Al Current Collector Material Polarised Highly Anodically and Located in Butyltrimethylammonium Bis(trifluoromethylsulfonyl)imide Room-Temperature Ionic Liquid

The electrochemical behaviour of Al, used as a current collector in supercapacitors and in Li-ion and Na-ion electrochemical power sources, was investigated for the first time using the in situ soft X-ray photoelectron spectroscopy (XPS) method, collecting the information directly at the electrolyte-covered Al current collector polarised electrochemically at high anodic potentials. Cyclic voltammetry, electrochemical impedance spectroscopy, and synchrotron in situ soft XPS methods were applied to collect physical and electrochemical information characterising the electrochemically polarised Al-current-collector RTIL interface soaked into the butyltrimethylammonium bis(trifluoromethylsulfonyl)imide (N4111(TFSI)) room-temperature ionic liquid. The obtained data show the start of intensive oxidation processes, including aluminium oxidation and the formation of an insoluble Al(TFSI)3 surface layer in N4111(TFSI) at E ≥ 3.0 V (vs. Ag-QRE). Very intensive electro-oxidation of TFSI− anions at E ≥ 6.5 V (vs. Ag-QRE) has been observed. CV data indicate that the electrochemical oxidation of once-activated Al is possible in N4111(TFSI) at 1.1 V &lt; E &lt; 1.6 V (vs. Ag-QRE). Therefore, the oxidation of Al starts at E ≥ 2.05 V (vs. Ag-QRE) if the Al surface is modified with electro-oxidation products of TFSI− anions.

Toward a Novel RESTFUL Big Data-Based Urban Traffic Incident Data Web Service for Connected Vehicles

Abstract Connected vehicles (CVs) are an emerging technology in intelligent transportation systems. Currently, many data-driven intelligent transportation systems (D2ITS) use CV data. Unfortunately, these D2ITS still need serious improvement before they meet higher-level visualization needs. Thus, we aim to develop a new, intelligent data-driven transportation system framework. We focus on visualizing real-time CV data using a big data analytic system in urban areas. In response, we first propose an effective real-time data distribution approach within the Vehicular Ad-hoc NETwork. Second, we develop novel strategies for aggregating, extracting and ingesting data. We provide scalable and fault-tolerant delivery methods without interruption or delay. Finally, we proposed a novel visualization REpresentational State Transfer (REST) web service. We used Simulation of Urban MObility, OMNET++ and Veins to simulate a traffic incident dataset. Then, we tested the Basic Safety Messages in an experimental big data cluster. We used NIFI, Kafka and Cassandra for ingestion, distribution, delivery and storage. The results show accurate performance for packet loss, packet delivery and communication delay. Also, it indicates high throughput and low latency for distributed data delivery systems. Additionally, we obtained the smallest response time for the RESTFUL visualization web service.

Simultaneous electro-generation/polymerization of Cu nanocluster embedded conductive poly(2,2′:5′,2′′-terthiophene) films at micro and macro liquid/liquid interfaces

Cu nanoparticles (NPs) have been shown to be excellent electrocatalysts, particularly for CO2 reduction – a critical reaction for sequestering anthropogenic, atmospheric carbon. Herein, the micro interface between two immiscible electrolyte solutions (ITIES) is exploited for the simultaneous electropolymerization of 2,2′:5′,2′′-terthiophene (TT) and reduction of Cu2+ to Cu nanoparticles (NPs) generating a flexible electrocatalytic composite electrode material. TT acts as an electron donor in 1,2-dichloroethane (DCE) through heterogeneous electron transfer across the water|DCE (w|DCE) interface to CuSO4 dissolved in water. The nanocomposite formation process was probed using cyclic voltammetry as well as electrochemical impedance spectroscopy (EIS). CV and EIS data show that the film forms quickly; however, the interfacial reaction is not spontaneous and does not proceed without an applied potential. At high [TT] the heterogeneous electron transfer wave was recorded voltammetrically but not at low [TT]. However, probing the edge of the polarizable potential window was found to be sufficient to initiate electrogeneration/electropolymerization. SEM and TEM were used to image and analyze the final Cu NP/poly-TT composites and it was discovered that there is a concomitant decrease in NP size with increasing [TT]. Preliminary electrocatalysis results at a nanocomposite modified large glassy carbon electrode saw a > 2 × increase in CO2 reduction currents versus an unmodified electrode. These data suggest that this strategy is a promising means of generating electrocatalytic materials for carbon capture. However, films electrosynthesized at a micro and ~ 1 mm ITIES demonstrated poor reusability.

Non-invasive electrochemical immunosensor for reverse iontophoretic determination of cardiac troponins (cTnT & cTnI) in a simulated artificial skin model. Significance of raw DPV and CV data for chemometric discrimination

Electrochemical immunosensors coupled with reverse iontophoresis (RI) for noninvasive determination of cardiac troponins were developed and validated according to ICH Q2 (R1) guideline. Linearity was in 0.01–10 and 100–500 ng/mL ranges. LODs (ng/mL) were in 6–25 × 10-4, while LOQs (μg/mL) were in 18–7.5 × 10-4 range. Chemometric evaluation was performed on raw data simply by principle component analysis and cluster analysis to discriminate stages of immunosensors. This is the first demonstration of RI determination of cardiac troponins so far. Findings of the current manuscript have great potential to develop point of care diagnostic systems for major cardiac events, where high sensitivity and specificity are required.

Enhancing the Resistive Switching Behavior of WORM Memory Devices Using D-π-A Based Ester-Flanked Quinolines.

Donor-Acceptor systems are highly appreciated in the field of organic memory devices due to their efficient charge transport within the systems. In this work, we have designed and synthesized a D-π-A system constituting ester-flanked quinolines and functionalized triarylamines (TAA) through a single-step cross-coupling reaction to fabricate memory devices via Write-Once Read-Many times (WORM) non-volatile memory. Structure-property relationships are reconnoitered for these conjugated D-π-A systems through a series of UV, fluorescence, XRD, DFT, and memory characterizations. The UV and CV data show efficient charge transfer with intramolecular charge transfer occurring at 407-417 nm and a short band gap of 2.56-2.65 eV. An enhancement in the resistive switching behavior of the memory devices is observed for the compounds with simple TAA-quinoline and tert-butylphenyl substituted TAA and fluorophenyl substituted quinoline due to balanced charge distribution in the compounds. This enhanced switching induces an on/off ratio of 103 by generating a highly ordered arrangement in the thin films. The HOMO, LUMO levels, and the ESP images together estimate a charge transfer and charge trapping as the plausible mechanism for the solution-processable WORM memory devices. The longer retention time (103 s) and lower threshold voltages (-1.21--2.12 V) of the devices makes them intriguing compounds for memory applications.

Lamellar Hierarchical Porous Carbon Prepared from Coal Tar Pitch through a Lamellar Hard Template Combined with the Precarbonization and Activation Method for Supercapacitors

The lamellar porous carbon favors the diffusion and penetration of electrolyte ions and presents a fantastic advantage as an energy storage electrode material. In this work, the lamellar Mg5(OH)4(CO3)2·4H2O template is synthesized via a simple precipitation method in the low-temperature hydrothermal condition. Lamellar hierarchical porous carbon (LHPC) is successfully synthesized through the Mg5(OH)4(CO3)2·4H2O hard template and the KOH activation method using coal tar pitch (CTP) as the carbon source. The effects of activation temperature and activator dosage on the morphology, microstructure, and supercapacitor performance are researched at length. LHPCs-1–700 displays a good lamellar structure and an abundant mesoporous structure, so as to exhibit superior capacitive performance compared with other carbon electrodes. The specific capacitance for LHPCs-1–700 reaches 298 F g–1 at 1 A g–1 and still maintains 234 F g–1 at 50 A g–1 with a high capacitance retention of 78.5% in the three-electrode system. The kinetic behavior of the LHPCs-1–700 electrode was also analyzed according to the CV data obtained at different scan rates, and it was found that the fast kinetic capacitance contribution was up to 87% at 200 mV s–1. The assembled LHPCs-1–700 symmetric supercapacitor delivered an energy density of 16.73 W h kg–1 with a power density of 859.4 W kg–1 in 1 M Na2SO4 solution. Besides, the specific capacitance retention rate could still reach 95.8% after 8000 cycles.

Electrocatalytic Ammonia Oxidation by a Low-Coordinate Copper Complex.

Molecular catalysts for ammonia oxidation to dinitrogen represent enabling components to utilize ammonia as a fuel and/or source of hydrogen. Ammonia oxidation requires not only the breaking of multiple strong N-H bonds but also controlled N-N bond formation. We report a novel β-diketiminato copper complex [iPr2NNF6]CuI-NH3 ([CuI]-NH3 (2)) as a robust electrocatalyst for NH3 oxidation in acetonitrile under homogeneous conditions. Complex 2 operates at a moderate overpotential (η = 700 mV) with a TOFmax = 940 h-1 as determined from CV data in 1.3 M NH3-MeCN solvent. Prolonged (>5 h) controlled potential electrolysis (CPE) reveals the stability and robustness of the catalyst under electrocatalytic conditions. Detailed mechanistic investigations indicate that electrochemical oxidation of [CuI]-NH3 forms {[CuII]-NH3}+ (4), which undergoes deprotonation by excess NH3 to form reactive copper(II)-amide ([CuII]-NH2, 6) unstable toward N-N bond formation to give the dinuclear hydrazine complex [CuI]2(μ-N2H4). Electrochemical studies reveal that the diammine complex [CuI](NH3)2 (7) forms at high ammonia concentration as part of the {[CuII](NH3)2}+/[CuI](NH3)2 redox couple that is electrocatalytically inactive. DFT analysis reveals a much higher thermodynamic barrier for deprotonation of the four-coordinate {[CuII](NH3)2}+ (8) by NH3 to give the copper(II) amide [CuII](NH2)(NH3) (9) (ΔG = 31.7 kcal/mol) as compared to deprotonation of the three-coordinate {[CuII]-NH3}+ by NH3 to provide the reactive three-coordinate parent amide [CuII]-NH2 (ΔG = 18.1 kcal/mol) susceptible to N-N coupling to form [CuI]2(μ-N2H4) (ΔG = -11.8 kcal/mol).

Abstract 15828: Baseline Hs-ctnt Concentrations Within the Sex-Specific Reference Range and Index Mortality in Emergency Department Patients

Background: High-sensitivity (hs) cardiac troponin (cTn) assays quantifies cTn in most healthy men and women. Whether quantifiable cTn concentrations below the 99 th percentile upper-reference limit have short term prognostic implications in emergency department (ED) patients remains uncertain. Methods: Multicenter (n=22) United States (US) cohort of ED patients undergoing at least one hs-cTnT measurement (CV Data Mart Biomarker cohort). For this assay, the lowest reportable concentration is &lt;6 ng/L. Sex-specific 99 th percentiles of 10 ng/L for women and 15 ng/L for men were used. The primary outcome was index hospitalization mortality. Results: A total of 85610 patients were examined, including 43043 women and 42567 men. A total of 775 index hospitalization deaths (0.91%) occurred, including 361 (0.84%) in women and 414 (0.97%) in men. Among women, baseline hs-cTnT concentrations were non-quantifiable (&lt;LoQ) in 37.5%, quantifiable (LoQ-99 th ) in 21.6%, and increased &gt;99 th percentile in 40.9%. Among men, baseline hs-cTnT concentrations were non-quantifiable (&lt;LoQ) in 20.0%, quantifiable (LoQ-99 th ) in 37.4%, and increased &gt;99 th percentile in 42.6%. Patients with higher concentrations were more likely to be older and had more comorbidities. Continuous baseline hs-cTnT (log) were associated with a higher odds of index hospitalization mortality (OR 1.26, 95% CI 1.24-1.28). Following multivariable analyses, quantifiable hs-cTnT (LoQ-99 th ) also were associated with index hospitalization mortality in all patients (OR 2.07, 95% 1.22-3.53), and in both women (OR 3.13, 95% CI 1.51-6.50) and men (OR 2.17, 95% 1.28-3.69) (Figure). Conclusions: Hs-cTnT concentrations within the reference range are more common in men than in women. Quantifiable hs-cTnT concentrations within the sex-specific reference range are associated with a higher risk of index hospitalization mortality, with a larger prognostic effect in women than in men.