Electrochemical behavior of labetalol at an ionic liquid modified carbon paste electrode and its electrochemical determination

Electrochemical behavior of labetalol (LBT) at carbon paste electrode (CPE) and an ionic liquid1-benzyl-3-methylimidazolehexafluorophosphate([BnMIM]PF6)modified carbon paste electrode([BnMIM]PF6/CPE)in Britton-Robinson buffer solution (pH 2.0) was investigated by cyclic voltammetry (CV) and square wave voltammetric (SWV). The experimental results showed that LBT at both the bare CPE and [BnMIM]PF6/CPEshowed an irreversible oxidation process, but at [BnMIM]PF6/CPE its oxidation peak current increased greatly and the oxidation peak potential shifted negatively. The electrode reaction process is a diffusion-controlled process involving one electron transferring accompanied by a participation of one proton at [BnMIM]PF6/CPE. At the same time, the electrochemical kinetic parameters were determined. Under the optimized electrochemical experimental conditions, the oxidation peak currents were proportional to LBT concentration in the range of 7.0 x 10-6-1.0 x 10-4 mol L-1 with the limit of detection(LOD, S/N=3) of 4.810 x 10-8 mol L-1and the limit of quantification(LOQ, S/N=10) of 1.60 x 10-7 mol L-1, respectively. The proposed method was successfully applied in the determination of LBT content in commercial tablet samples

Bis{μ-[4-(1,3-benzothia­zol-2-yl)phen­yl]methane­thiol­ato-κ4 S,S′:S,S′}bis­[tricarbonyl­iron(I)](Fe—Fe)

The title compound, [Fe2(C14H10NS2)2(CO)6], was synthesized as a structural and biochemical model for the active site of [FeFe]-hydrogenase. The bond lengths (Fe—Fe, Fe—S and Fe—C) and angles (C—Fe—Fe and Fe—S—Fe) are within expected ranges. The S⋯S distance [2.9069 (12) Å] and the dihedral angle between two Fe—S—Fe planes [78.5 (3)°] of the butterfly-shaped Fe2S2 core are enlarged compared with related bridged dithiol­ate diiron analogues. The calculated 4-benzothia­zolebenzyl best planes are almost parallel [dihedral angle = 3.7 (7)°]

Revisit of tensor-meson nonet in resonance chiral theory

We study the properties of the lowest multiplet of light-flavor tensor meson resonances, i.e. $f_2(1270)$, $a_2(1320)$, $K_2^*(1430)$, and $f_2'(1525)$, within the resonance chiral theory approach. The higher-order resonance chiral operators, including the light-quark mass and $1/N_C$ corrections, are simultaneously incorporated in our study. The use of resonance chiral expressions allows us to analyze not only the relevant experimental data but also in the meantime the lattice results at unphysical quark masses, including the masses of the lowest multiplet of tensor resonances and their decay widths into two pseudoscalar mesons. In addition, the radiative decays of the tensor resonances into one photon plus one pseudoscalar meson and two photons are also studied.Comment: 18 pages, 3 tables, 3 figures. To match the published versio

Electrochemical Behaviors and Electrochemical Determination of 1-naphthaleneacetic Acid at an Ionic Liquid Modified Carbon Paste Electrode

Electrochemical behaviors of 1-naphthaleneacetic acid (NAA) at an ionic liquid N-butyl-pyridinium hexafluorophosphate (BPPF6/CPE) modified carbon paste electrode was investigated by cyclic voltammetry (CV) and further used for NAA sample determination. The experimental results showed that NAA at both the bared and the modified electrode showed an irreversible oxidation process, but at the modified electrode it exhibited an enhanced electrochemical response towards its electrochemical oxi-dation. BPPF6/CPE was characterized by electrochemical impedance spectroscopy (EIS). At the same time, the electrochemical kinetic parameters were determined at both electrodes. The oxidation peak cur-rents increased linearly with NAA concentration range from 2.0 × 10–5 to 4.0 × 10–4 mol dm–3 with the detection limit (S/N = 3) of 1.690 × 10–7 mol dm–3 under the optimized experiment conditions. The pro-posed method was successfully applied for NAA content determination in both commercial formulations and the soil samples. (doi: 10.5562/cca1901

Electrochemical Behavior and Electrochemical Determination of Tiamulin Fumarate at an Ionic Liquid Modified Carbon Paste Electrode

The electrochemical behavior of tiamulin fumarate (TF) at ionic liquid N-Butylpyridinium hexafluorophosphate (BPPF6) modified carbon paste electrode (BPPF6/CPE) was investigated and further used for tiamulin fumarate sample determination. BPPF6/CPE showed an enhanced electrochemical response towards the electrochemical oxidation of TF. A well-defined and sensitive oxidation peak was observed at BPPF6/CPE in 0.10 M phosphate buffer solution (PBS, pH = 6.80). The oxidation peak current of TF increased significantly at BPPF6/CPE compared with that at carbon paste electrode and the BPPF6/CPE was characterized by the electrochemical impedance spectroscopy (EIS). At the same time, the electrochemical kinetics parameters of TF on the BPPF6/CPE were evaluated. Under the optimized conditions, the oxidation peak currents were linearly dependent on the concentration of TF in the range of 0.3–9.0 μM and 9.0–0.3 mM, with a detection limit of 0.16 μM (S/N = 3). The proposed method has been successfully applied in the electrochemical quantitative determination of TF content in commercial injection samples

Diaqua­bis(pyrimidine-2-carboxylic acid-κ2 N,O)cobalt(II) dichloride

In the title salt, [Co(C5H4N2O2)2(H2O)2]Cl2, the CoII ion is located on an inversion center. It is chelated by two neutral pyrimidine-2-carboxylic acid molecules and is coordinated by two water mol­ecules in an octa­hedral coordination geometry. The cations and anions are linked via O—H⋯Cl hydrogen bonds into a layer structure; an intra­molecular O—H⋯N hydrogen bond connects the carboxylic acid group to the pyrimidine N atom

Learning Knowledge-Enhanced Contextual Language Representations for Domain Natural Language Understanding

Knowledge-Enhanced Pre-trained Language Models (KEPLMs) improve the performance of various downstream NLP tasks by injecting knowledge facts from large-scale Knowledge Graphs (KGs). However, existing methods for pre-training KEPLMs with relational triples are difficult to be adapted to close domains due to the lack of sufficient domain graph semantics. In this paper, we propose a Knowledge-enhanced lANGuAge Representation learning framework for various clOsed dOmains (KANGAROO) via capturing the implicit graph structure among the entities. Specifically, since the entity coverage rates of closed-domain KGs can be relatively low and may exhibit the global sparsity phenomenon for knowledge injection, we consider not only the shallow relational representations of triples but also the hyperbolic embeddings of deep hierarchical entity-class structures for effective knowledge fusion.Moreover, as two closed-domain entities under the same entity-class often have locally dense neighbor subgraphs counted by max point biconnected component, we further propose a data augmentation strategy based on contrastive learning over subgraphs to construct hard negative samples of higher quality. It makes the underlying KELPMs better distinguish the semantics of these neighboring entities to further complement the global semantic sparsity. In the experiments, we evaluate KANGAROO over various knowledge-aware and general NLP tasks in both full and few-shot learning settings, outperforming various KEPLM training paradigms performance in closed-domains significantly.Comment: emnlp 202