Highly Stable Solid Contact Calcium Ion-Selective Electrodes: Rapid Ion-Electron Transduction Triggered by Lipophilic Anions Participating in Redox Reactions of CunS Nanoflowers.

Solid contact (SC) calcium ion-selective electrodes (Ca2+-ISEs) have been widely applied in the analysis of water quality and body fluids by virtue of the unique advantages of easy operation and rapid response. However, the potential drift during the long-term stability test hinders their further practical applications. Designing novel redox SC layers with large capacitance and high hydrophobicity is a promising approach to stabilize the potential stability, meanwhile, exploring the transduction mechanism is also of great guiding significance for the precise design of SC layer materials. Herein, flower-like copper sulfide (CunS-50) composed of nanosheets is meticulously designed as the redox SC layer by modification with the surfactant (CTAB). The CunS-50-based Ca2+-ISE (CunS-50/Ca2+-ISE) demonstrates a near-Nernstian slope of 28.23 mV/dec for Ca2+ in a wide activity linear range of 10-7 to 10-1 M, with a low detection limit of 3.16 × 10-8 M. CunS-50/Ca2+-ISE possesses an extremely low potential drift of only 1.23 ± 0.13 µV/h in the long-term potential stability test. Notably, X-ray absorption fine-structure (XAFS) spectra and electrochemical experiments are adopted to elucidate the transduction mechanism that the lipophilic anion (TFPB-) participates in the redox reaction of CunS-50 at the solid-solid interface of ion-selective membrane (ISM) and redox inorganic SC layer (CunS-50), thereby promoting the generation of free electrons to accelerate ion-electron transduction. This work provides an in-depth comprehension of the transduction mechanism of the potentiometric response and an effective strategy for designing redox materials of ion-electron transduction triggered by lipophilic anions.

Effects of yeast culture supplementation and the ratio of non-structural carbohydrate to fat on growth performance, carcass traits and the fatty acid profile of the longissimus dorsi muscle in lambs.

The effects of yeast culture (YC) supplementation and the dietary ratio of non-structural carbohydrate to fat (NSCFR) on growth performance, carcass traits and fatty acid profile of the longissimus dorsi (LD) muscle in lambs were determined in a 2 × 3 full factorial experiment. Thirty-six Small-tailed Han lambs were randomly divided into six groups with six replicates per group. The lambs were fed one of the six pelleted total mixed rations (TMRs) for 60 days after 15 adaption days. The six rations were formed by two NSCFRs (11.37 and 4.57) and three YC supplementation levels (0, 0.8 and 2.3 g/kg dietary dry matter). The average daily gain (ADG), dry matter intake (DMI) and feed conversion ratio (FCR) data of each lamb were recorded and calculated. All the lambs were slaughtered for determining carcass traits and fatty acid profile of the LD muscle. DMI was significantly increased (p < 0.05) in a quadratic fashion with 0.8 g/kg of YC supplementation. Carcass weight (CW) and dressing percentage (DP) were significantly increased (p < 0.05) in a linear fashion with 2.3 g/kg of YC supplementation. Animals fed with high-NSCFR diet had higher (p < 0.05) contents of myristoleic acid (C14:1), pentadecanoic acid (C15:0) and cis-10-heptadecenoic acid (C17:1), and lower (p < 0.05) stearic acid (C18:0) content in LD muscle than those fed with low-NSCFR diet. Moreover, ADG, growth rate (GR), backfat thickness (BFT), percentages of crude fat (CF) and crude protein (CP), SFAs, MUFAs and PUFAs in LD muscle, were significantly affected (p < 0.05) by interaction of dietary NSCFR and supplemental YC level. Overall, YC not only improved the growth performance and carcass traits of the animals but also modified the fatty acid profile of the LD muscle. Furthermore, the effects of YC supplementation may depend on dietary compositions.

In Situ Investigating of the Interaction of Phenanthrene and Alkyl Phenanthrene with Humic Acid with Laser Induced Nanoseconds Time Resolved Fluorescence Quenching Method.

Investigations both on the binding properties and mechanisms of parent polycyclic aromatic hydrocarbons (PAHs) and alkyl PAHs with humic acid (HA) are crucial to understand the environment behavior and bioavailability of PAHs in aquatic ecosystems. Thus, a novel approach for in situ investigation of the interactions between parent PAHs and alkyl PAHs, exemplified by Phenanthrene (Phe), 9-Ethylphenanthrene (9-EP) and Retene (Ret), and HA was established by using fluorescence quenching method with laser-induced nanosecond time-resolved fluorescence (LITRF). By changing the delay time of 50 ns, the fluorescent interference of HA can be eliminated effectively and the concentrations of free Phe, 9-EP and Ret can be determined directly. The binding characteristics of the dissolved HA and Phe, 9-EP and Ret were described by Freundlich nonlinear isothermal model. The results of the model parameters and the single point binding coefficients KOC of Phe, 9-EP and Ret with HA by LITRF quenching method were consistent with those of the conventional fluorescence quenching method. Nonlinear bindings of Phe, 9-EP and Ret to HA were also observed because of the parameter n values below 1, and the degree of nonlinearity of Phe was lower than 9-EP and Ret duo to the n value of Phe larger than 9-EP and Ret. At a same given equilibrium concentration, the KOC of Phe was lower than 9-EP and Ret, and that of 9-EP was near to Ret. The binding affinity of the three PAHs increased with decreasing the equilibrium concentration. The binding characteristics of PAHs with HA largely depends on their hydrophobicity, substituent groups and its ability to fit into hydrophobic cavities in HA. The fluorescence lifetimes of Phe, 9-EP and Ret in presence of HA were 36.90, 35.34 and 35.13 ns, meanwhile the fluorescence lifetimes of Phe, 9-EP and Ret in absence of HA were 36.36, 35.34 and 35.84 ns. There was no significant difference of three PAHs fluorescence lifetime with or without HA, indicating the quenching mechanism for Phe, 9-EP and Ret with HA were primarily static quenching. The LITRF quenching method could be used to in situ explore the interactions between PAHs and HA, which could be contribute to realize the PAHs risk assessment in real time.

Transforming crystal structures of cobalt molybdate to generate electron-rich sites for electrochemical detection of Pb(II).

BACKGROUND: Most of the investigations on distinct crystal structures of catalysts are individually focused on the difference of surface functional groups or adsorption properties, but rarely explore the changes of active sites to affect the electrocatalytic performance. Catalysts with diverse crystal structures had been applied to modified electrodes in different electrocatalytic reactions. However, there is currently a lack of an essential understanding for the role of real active sites in catalysts with crystalline structures in electroanalysis, which is crucial for designing highly sensitive sensing interfaces. RESULTS: Herein, cobalt molybdate with divergent crystal structures (α-CoMoO4 and ß-CoMoO4) were synthesized by adjusting the calcination temperature, indicating that α-CoMoO4 (800 °C) (60.00 µA µM-1) had the highest catalytic ability than ß-CoMoO4 (700 °C) (38.68 µA µM-1) and α-CoMoO4 (900 °C) (29.55 µA µM-1) for the catalysis of Pb(II). It was proved that the proportion of Co(II) and Mo(IV) as electron-rich sites in α-CoMoO4 (800 °C) were higher than ß-CoMoO4 (700 °C) and α-CoMoO4 (900 °C), possessing more electrons to participate in the valence cycles of Co(II)/Co(III) and Mo(IV)/Mo(VI) to boost the catalytic reduction of Pb(II). Specifically, Co(II) transferred a part of electrons to Mo(VI), promoting the formation of Mo(IV). Co(II) and Mo(IV), as the electron-rich sites, providing electrons to Pb(II), further accelerating the conversion of Pb(II) into Pb(0). SIGNIFICANCE: In the process of detecting Pb(II), the CoMoO4 structures under different temperatures have distinct content of electron-rich sites Co(II) and Mo(IV). α-CoMoO4 (800 °C), with the highest content are benefited to detect Pb(II). This work is conducive to understanding the effect of the changes of active sites resulting from crystal transformation on the electrocatalytic performance, and provides a way to construct sensitive electrochemical interfaces of distinct active sites.

Ion-Electron Transduction Layer of the SnS2-MoS2 Heterojunction to Elevate Superior Interface Stability for All-Solid Sodium-Ion Selective Electrode.

The high selectivity and fast ion response of all-solid sodium ion selective electrodes were widely applied in human sweat analysis. However, the potential drift due to insufficient interfacial capacitance leads to the deterioration of its stability and ultimately affects the potential accuracy of ion analysis. Designing a novel ion-electron transduction layer between the electrode and the ion selective membrane is an effective method to stabilize the interfacial potential. Herein, the SnS2-MoS2 heterojunction material was constructed by doping Sn in MoS2 nanosheets and used as the ion electron transduction layers of an all-solid sodium ion selective electrode for the first time, achieving the stable and efficient detection of Na+ ions. The proposed electrode exhibited a Nernst slope of 57.86 mV/dec for the detection of Na+ ions with a detection limit of 10-5.7 M in the activity range of 10-6-10-1 M. Via the electronic interaction at the heterojunction interfaces between SnS2 and MoS2 materials, the micro-nanostructure of the SnS2-MoS2 heterojunction was changed and SnS2-MoS2 as the ion-electron transduction layer acquired excellent capacitance (699 µF) and hydrophobicity (132°), resulting in a long-term potential stability of 1.37 µV/h. It was further proved that the large capacitance and high hydrophobicity of the ion-electron transduction layer are primary reasons for the excellent stability of the all-solid sodium ion selective electrode toward Na+ ions.

Bimodal interferences of Pb(II) induced by parallel deposition in Pb(II)-Cu(II) electrochemical detections: Voltammetric signals analysis combined with numerical simulations on transient interfacial phenomena.

The perplexity of double peaks in Pb(II) detections has been a threat to the reliability of Pb(II) electroanalysis results for a long term. For the complexity of electrode interfaces, rare studies were taken on mechanisms of Pb(II) double peaks through interfacial kinetics. In this work, analyses on experimental signals and interfacial simulations were working together to reveal that the generation of Pb(II) double peaks in Pb(II)-Cu(II) systems is the deposition of Pb(II) on Cu deposits occurring in parallel. By applying anode stripping voltammetry and cyclic voltammetry, a parallel deposition reaction was found to influence the shape of Pb(II) peaks, and the existence of the second peak was controlled through the adjustment of experimental conditions. A kinetic model was built to reveal the interference of electroanalysis signals caused by a parallel deposition reaction and simulations based on the model were combined with experiments to illustrate that double peaks of Pb(II) were caused by the parallel deposition on Cu(II) deposits. This work proposes another insight of Pb(II) double peaks from macroscale kinetics and pays more attention on the dynamic procedure of electroanalysis interfaces, which makes the study on environmental electroanalysis interface phenomena more clear and is enlightening to develop efficient electrical methods for pollutant monitoring.

Determination and Tissue Distribution Comparisons of Atractylodin after Oral Administration of Crude and Processed Atractylodes Rhizome.

BACKGROUND: Atractylodis rhizoma is one of the most often used drugs in traditional Chinese medicine. Stir frying with wheat bran is the most common processing method. To clarify the principle of processing, an experiment was carried out to compare the tissue distribution of typical constituent after oral administration of raw A. rhizoma and processed ones. OBJECTIVE: To compare the tissues distribution of atractylodin after oral administration of raw and processed A. rhizoma and clarify the processing principle of A. rhizoma. Materials and Methods: High-performance liquid chromatogram with ultraviolet detection was developed and validated for the determination of atractylodin in rat tissues. RESULTS: The atractylodin in raw and processed A. rhizoma was distributed in all tissues involved in this study. CONCLUSIONS: The concentration of atractylodin in it is the highest in the stomach and small intestine. SUMMARY: In this paper, a simple, specific, and rapid reversed phase-high-performance liquid chromatogram method with ultraviolet detection for quantification of atractylodin in rat tissue has been developed for the first time. The result indicates that the concentration of atractylodin in it is the highest in the stomach and small intestine. Abbreviations used: IS: Internal standard substance; A. rhizoma: Atractylodis rhizoma; RSD: Relative standard deviation; HPLC: High performance liquid chromatography.