Synthesis of γ-MnOOH nanorods by successive ionic layer deposition method and their capacitive performance

It was first shown in the present study that layers of manganite γ-Mn OOH can be deposited on the surface of a substrate by its multiple successive treatment by the solutions of MnSO_4 and K_2S_2O_8 using the successive ionic layer deposition(SILD) technique. Their analysis was carried out by the XRD, XPS, FT-IR,SEM and EDX methods. It has shown that the synthesized layers are formed by aggregates of nanorods up to 80–100 nm in length and approximately 8–10 nm in diameter. A probable sequence of chemical reactions leading to the formation of a layer of the given morphology is suggested. Testing of performance of supercapacitors with nickel foam electrodes incorporating the γ-Mn OOH layers in the 0.1 M KOH electrolyte at 1 A/g indicated the specific capacitance equal to 1120 F/g. After 1000 work cycles the observed degradation of this value was less than 3%.     

Quantitative determination of artemisinin in rat hemolyzed plasma by an HPLC–HRMS method

Iron present in hemolyzed plasma could cause the degradation of artemisinin by reductively cleaving the peroxide bridge of artemisinin during sample preparation, which is a significant technical challenge for artemisinin determination. In this paper, this issue was resolved by using sodium nitrite as methemoglobin-forming agent to oxidize hemoglobin to methemoglobin in the presence of acetic acid and prevent the degradation of artemisinin in hemolyzed plasma during the sample preparation procedure. Then, a high-performance liquid chromatography tandem high-resolution mass spectrometry method was developed and validated for the determination of artemisinin in normal and hemolyzed plasma. The linear range was validated over the concentration range of 5–500 ng ml⁻¹. The matrix effect and stability were also evaluated. This robust and sensitive assay was successfully applied to a pharmacokinetic study in rats after an oral administration of Artemisia annua L. extract.     

Analysis of optical absorption spectra of transition metal cluster ions by the spin-polarized DV-Xα method

Optical absorption spectra of cobalt cluster ions, Co _n ⁺ , and vanadium cluster ions, V _n ⁺ , were analyzed by a theoretical calculation based on the spin-polarized DV-Xα method, and their electronic and geometric structures were obtained. Relative absorption cross section associated with each electronic transition was calculated; the calculation enables a qualitative comparison of calculated spectrum with a measured one not only in its transition energy but also in its intensity profile. This analysis shows that Co ₄ ⁺ , Co ₃ ⁺ , and V ₄ ⁺ have, respectively, a tetrahedral structure with a bond distance of 2.00Å, an equilateral triangle with a bond distance of 2.30Å, and a distorted tetrahedral structure with five bonds having a distance of 2.34 Å and one of 2.89Å. The differences in the population between majority and minority spins (spin-difference) evaluated from the electronic structure thus obtained were 2.0, 1.7, and zero per atom in Co ₃ ⁺ , Co ₄ ⁺ , and V ₄ ⁺ , respectively. These spin differences indicate a ferromagnetic and an antiferromagnetic spin-coupling in the cobalt and vanadium cluster ions, respectively.     

Determination of tandospirone in human plasma by a liquid chromatography–tandem mass spectrometry method

A rapid, sensitive, and selective liquid chromatography–tandem mass spectrometry method for the detection of tandospirone in human plasma is described. It was employed in a pharmacokinetic study. The analyte and internal standard diphenhydramine were extracted from plasma using liquid–liquid extraction, then separated on a Zorbax XDB C₁₈ column using a mobile phase of methanol–water–formic acid (80:20:0.5, v/v/v). The detection was performed with a tandem mass spectrometer equipped with an electrospray ionization source. Linearity was established in the concentration range of 10.0-5,000 pg/ml. The lower limit of quantification was 10.0 pg/ml. The intraday and interday relative standard deviation across three validation runs over the entire concentration range was less than 13%. Accuracy determined at three concentrations (25.0, 200, and 4,000 pg/ml for tandospirone) ranged from 94.4 to 102.1%. Each plasma sample was chromatographed within 3.4 min. The method proved to be highly selective and suitable for bioequivalence evaluation of different formulations containing tandospirone and clinical pharmacokinetic investigation of tandospirone.     

Fabrication of functional nanostructured coatings by a combined sol–gel and plasma-enhanced chemical vapour deposition method

Nanostructures have a wide range of potential applications in industry because they can impart novel mechanical or functional properties to coatings such as abrasion resistance, UV shielding, superhydrophobicity. In this work we present a method for the fabrication of nanostructured coatings with improved mechanical properties, in which sol–gel nanoparticles are deposited on a surface and embedded in a ceramic film by plasma-enhanced chemical vapour deposition. This synthetic strategy is applied to the fabrication of transparent nanostructured antiscratch coatings.     

Controllable zeolite films on electrodes—comparing dc voltage electrophoretic deposition and a novel pulsed voltage method

We report here a novel application of pulsed voltage electrophoretic deposition (EPD) of zeolite 13X particles on glassy carbon surfaces. Our initial studies employing dc voltage EPD indicated that while adjustments of solution parameters (pH, supporting electrolyte concentration) and other experimental parameters (dc voltage, deposition time) allowed control of the amount of zeolite coated (from sub-monolayer to multilayer), difficulties of surface deactivation, controllability, uniformity, and reproducibility occurred under conditions suitable for the various films. These difficulties can be alleviated by utilizing a pulsed voltage program for EPD, an approach which has not been previously used for the fabrication of zeolite modified electrodes.     

Protein precipitation method for determination of clobazam and N-desmethylclobazam in human plasma by LC–MS/MS

A protein precipitation method for the determination of clobazam (CLB) and its major active metabolite N-desmethylclobazam (N-CLB) in human plasma by liquid chromatography tandem mass spectrometry (LC–MS/MS) was established. CLB and N-CLB were extracted from human plasma samples by protein precipitation with methanol. Analyte separation was done using a Phenomenex Kinetex™ Biphenyl (50 × 2.1 mm, 1.7 μm) column using isocratic elution with a mobile phase of 5 mm ammonium formate with 0.01% ammonium hydroxide (40%) and methanol (60%) at a flow rate of 0.4 mL/min and an injection volume of 10 μL. The detection was performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode to monitor the precursor-to-product ion transitions of m/z 301.1 → 259.0, 306.0 → 263.9 for CLB and CLB-D5 and 287.0 → 245.0, 292.0 → 250.0 for N-CLB and N-CLB-D5 in positive electrospray ionization mode, respectively. The method was validated over a concentration range of 2.0–750 ng/mL for CLB and 0.7–200 ng/mL for N-CLB on SCIEX Triple Quad 4500 MS System. Total run time was 5 min. This method has been designed for bioequivalence study for formulations containing 20 mg of CLB.     

A simple method for methylmercury,inorganic mercury and ethylmercury determination in plasma samples by high performance liquid chromatography–cold-vapor-inductively coupled plasma mass spectrometry

A simple and sensitive method with a fast sample preparation procedure is proposed for the determination of mercury species in plasma/serum. The method combines online high-performance liquid chromatography separation, Hg cold-vapor formation and inductively coupled plasma mass spectrometry detection. Prior to analysis, plasma (250 μL) was accurately pipetted into 15 mL conical tubes. Then, an extractant solution containing mercaptoethanol, L-cysteine and HCl was added to the samples following sonication for 10 min. Quantitative mercury extraction was achieved with the proposed procedure. Separation of mercury species was accomplished in less than 8 min on a C8 reverse phase column with a mobile phase containing 3% v/v methanol + 97% v/v (0.5% v/v 2-mercaptoethanol + 0.05% v/v formic acid). The method detection limits were found to be 12 ng L⁻¹, 5 ng L⁻¹ and 4 ng L⁻¹ for inorganic mercury, ethylmercury and methylmercury, respectively. Method accuracy is traceable to Standard Reference Material (SRM) 966 Toxic Metals in Bovine Blood from NIST. Additional validation was provided by the analysis of a secondary reference serum sample from the INSQ-Canada. Finally, the method was successfully applied for the speciation of mercury in plasma samples collected from volunteers exposed to methylmercury through fish consumption. For the first time to our knowledge, levels of different species of Hg in plasma samples from riverside populations exposed to MeHg were determined.     

New calculation method for asymmetric closed-loop liquid—liquid equilibria by lattice decoration

A new calculation method for the binary closed-loop coexistence curves of liquid—liquid equilibria has been developed in terms of lattice decoration and the UNIQUAC equation. Two-step renormalization was performed to evaluate the effective interaction energies of sites and the activities of binary mixtures in the decorated lattice consisting of primary and secondary cells. In application, the model reproduced fairly well temperature-composition diagrams which are asymmetric and closed in a loop or have lower consolute points.     

Americium/lanthanide separation enabled by a distinct polyoxometalate cluster

<正>Nuclear energy is viewed as a low carbon-emission electricity-generating technology with high-energy density,which has attracted extensive attention and shown broad development prospects [1]. However, to ensure sustainability and cleanability in the development of nuclear energy, one crucial challenge is to exploit efficient and economical technologies to simultaneously recover fissionable nuclides from nuclear waste and separate long-lived toxic fission products [2].     

Cu–ZnO nanocrystallites by aqueous thermolysis method

ZnO and different atomic percentages of Cu-doped ZnO nanocrystallites have been prepared by aqueous thermolysis method using Glycine as a fuel and encapsulating agent. Mechanism and formation of intermediate products have been given for the first time. All the findings given are for samples annealed at 800?°C. XRD of nanocrystalline ZnO and Cu?CZnO has been indexed to hexagonal wurtzite structure. Influence of temperature on thermal properties of gel precursor and Cu-doped ZnO nanoparticles have been investigated using thermogravimetric and differential thermal analysis. Accordingly, samples have been annealed at different temperatures. Infrared studies revealed formation of Cu?CZnO nanoparticles and removal of organic matter at higher temperature.     

Synthesis of α-eucryptite by the sol-gel method

New method is reported for synthesis of α-eucryptite LiAlSiO₄ whose framwork structure has voids that enable its doping with lanthanides. The optical parameters of this orthosilicate and results of introduction of europium ions into its composition to create a phosphor were studied.     

Simultaneous quantitative determination of liraglutide and insulin degludec in rat plasma by liquid chromatography–tandem mass spectrometry method and its application

A simple, fast and high-throughput LC–tandem mass spectrometry method was developed and validated to simultaneously measure liraglutide and insulin degludec in rat plasma. After protein precipitation, plasma samples were subjected to gradient elution using an InertSustain Bio C₁₈ column with 1000/20/1 water/acetonitrile/formic acid (v/v/v) and 1000/1 acetonitrile/formic acid (v/v) as the mobile phase. The method was validated from 1.00 to 500 ng/mL of liraglutide and insulin degludec. Further, the extraction recovery from the plasma was 41.8%–49.2% for liraglutide and 56.5%–69.7% for insulin degludec. Intra- and inter-day precision of liraglutide was 3.5%–9.4% and 8.4%–9.8%, respectively, whereas its accuracy was between −12.6% and −1.3%. Intra- and inter-day precision of insulin degludec was 5.2%–13.6% and 11.8%–19.1%, respectively, showing an accuracy between −3.0% and 9.9%. As a result, the method was successfully applied to a pharmacokinetics study of liraglutide and insulin degludec following a single-dose subcutaneous administration to rats.     

Determination of Evans blue as a blood–brain barrier integrity tracer in plasma and brain tissue by UHPLC/UV method

Blood–brain barrier changes are an integral part of many neurodegenerative diseases. Evans blue is an intravital dye that binds to albumin and can therefore be used to monitor extravasation of this plasma protein across blood–brain barrier in animal models of neurodegeneration. To monitor extravasation of albumin across blood–brain barrier, we developed and validated an ultrahigh-performance liquid chromatography method for the analysis of Evans blue in rat plasma and brain samples. Analyte was separated on ACQUITY UPLC BEH C18 column (2.1?mm?×?50?mm) using a 5-min gradient run and detected by a UV detector. The limits of quantification (LOQ) were 10?µg/mL in plasma and 0.5?µg/g in brain samples. The limits of detection (LOD) were 1?µg/mL in plasma and 0.015?µg/g in brain samples. The method showed excellent linearity with regression coefficients higher than 0.99. The accuracy was within the range of 91–105%. The inter-day precision was in the range of 1.3–8%. The benefits of using UPLC are selectivity, short analysis period, and thus, a very good sample throughput. Using this method, we analyzed albumin extravasation across blood–brain barrier in transgenic rat model for tauopathy SHR-72 and age-matched control animals.     

Mechanistic insights into the inhibition mechanism of cysteine cathepsins by chalcone-based inhibitors—a QM cluster model approach

Structural Chemistry - Cathepsins are the most abundant cysteine proteases involved in many physiological processes. The imbalance between the natural cysteine protease inhibitors and cathepsins...     

A novel method for quantification of sulfolane (a metabolite of busulfan) in plasma by gas chromatography–tandem mass spectrometry

The role of busulfan (Bu) metabolites in the adverse events seen during hematopoietic stem cell transplantation and in drug interactions is not explored. Lack of availability of established analytical methods limits our understanding in this area. The present work describes a novel gas chromatography-tandem mass spectrometric assay for the analysis of sulfolane (Su) in plasma of patients receiving high-dose Bu. Su and Bu were extracted from a single 100 μL plasma sample by liquid-liquid extraction. Bu was separately derivatized with 2,3,5,6-tetrafluorothiophenolfluorinated agent. Mass spectrometric detection of the analytes was performed in the selected reaction monitoring mode on a triple quadrupole instrument after electronic impact ionization. Bu and Su were analyzed with separate chromatographic programs, lasting 5?min each. The assay for Su was found to be linear in the concentration range of 20-400?ng/mL. The method has satisfactory sensitivity (lower limit of quantification, 20?ng/mL) and precision (relative standard deviation less than 15?%) for all the concentrations tested with a good trueness (100?±?5?%). This method was applied to measure Su from pediatric patients with samples collected 4?h after dose 1 (n?=?46), before dose 7 (n?=?56), and after dose 9 (n?=?54) infusions of Bu. Su (mean?±?SD) was detectable in plasma of patients 4?h after dose 1, and higher levels were observed after dose 9 (249.9?±?123.4?ng/mL). This method may be used in clinical studies investigating the role of Su on adverse events and drug interactions associated with Bu therapy.     

Iron—sulfur cluster micelle as a ferredoxin model

Iron—sulfur clusters having hydrophilic and hydrophobic L-cysteine derivative as their components were prepared. Electronic and CD spectra of these clusters as well as their oxidation—reduction potentials are very similar to those of native enzymes. These clusters incorporated in the micelles show satisfactory stability and electron transfer ability.     

Optimization of a method for the determination of a mustard gas biomarker in human blood plasma by liquid chromatography–high-resolution mass spectrometry

A method for the determination of a mustard gas biomarker (an S-hydroxyethylthioethyl adduct with albumin) in blood plasma was optimized with the use of HPLC with high-resolution tandem mass-spectrometric detection. This method is based on the hydrolysis of this adduct by the proteinase K enzyme with the formation of the following stable tripeptide with cysteine, proline, and phenylalanine: S-[HETE]-Cys- Pro-Phe. The conditions of the sample preparation of human plasma artificially contaminated by mustard gas (the selection of an aliquot portion volume and an enzyme for the hydrolysis), the mass-spectrometric detection (the selection of optimum pairs of ion reactions and high-resolution detection modes), and the gradient elution program in the HPLC separation of an analyzed mixture were optimized. The detection limit of mustard gas in human blood plasma was 1 ng/mL. The approach proposed was tested in the analysis of human blood plasma samples by the standard addition technique and also within the framework of the first official biomedical test carried out by the Organization for the Prohibition of Chemical Weapons (OPCW) in 2016, and it exhibited a good accuracy, reproducibility, and specificity of determination.     

Structural study of oriented non-crystalline PET by CDF method

The two-dimensional wide angle X-ray scattering (WAXS) intensities of oriented non-crystalline polyethylene terephthalate (PET) films extended umaxially are collected by the symmetrical transmission method; he-sides,the overlapped non-crystalline peaks at WAXS intensity curves,I(K) obtained at different azimuthal angles are also separated by computer,resulting in two peaks caused by interchain atomic scattering in the reciprocal space,KA(K=0.122),KB(K=0.171),and the other two peaks from intracham atomic scattering,Kc(K=0.310) and KD(K=0.548); their cylindrical distribution functions (CDF),CDF(R,α) in the real space are further calcu lated from the intensity functions,IE(K) using sampled transforms,thereof arising in turn the peaks in the real space as,RA(R=0.658),RB(R=0.456),RC(R=0.253) and RD(R=0.152),corresponding to KA,KP,K,and KD The equivalent relationships and distribution characteristics of the above-mentioned corresponding peaks in the reciprocal and real space,as well as their sources of struc     

Validated HPLC–MS–MS method for simultaneous determination of atorvastatin and 2-hydroxyatorvastatin in human plasma—pharmacokinetic study

Cholesterol-reducing statin drugs are the most frequently prescribed agents for reducing morbidity and mortality related to coronary heart disease. In this publication a validated, highly sensitive, and selective isocratic HPLC method is reported for quantitative determination of the major statin drug atorvastatin (ATV) and its metabolite 2-hydroxyatorvastatin (HATV). Detection was performed with an electrospray ionization triple-quadrupole mass spectrometer equipped with an ESI interface operating in positive-ionization mode. Multiple reaction monitoring (MRM) was used for MS–MS detection. The calibration plot was linear in the concentration range 0.10–40.00 ng mL⁻¹ for both ATV and HATV. Inter-day and intra-day precision and accuracy of the proposed method were characterized by measurement of relative standard deviation (RSD) and percentage deviation, respectively; both were less than 8% for both analytes. The limit of quantitation was 0.02 ng mL⁻¹ for ATV and 0.07 ng mL⁻¹ for HATV. The method was used for pharmacokinetic study of ATV and HATV. Pharmacokinetic data for all analytes are also reported.