Two low-cost digital camera-based platforms for quantitative creatinine analysis in urine

In clinical analysis creatinine is a routine biomarker for the assessment of renal and muscular dysfunctions. Although several techniques have been proposed for a fast and accurate quantification of creatinine in human serum or urine, most of them require expensive or complex apparatus, advanced sample preparation or skilled operators. To circumvent these issues, we propose two home-made platforms based on a CD Spectroscope (CDS) and Computer Screen Photo-assisted Technique (CSPT) for the rapid assessment of creatinine level in human urine. Both systems display a linear range (r² = 0.9967 and 0.9972, respectively) from 160 μmol L⁻¹ to 1.6 mmol L⁻¹ for standard creatinine solutions (n = 15) with respective detection limits of 89 μmol L⁻¹ and 111 μmol L⁻¹. Good repeatability was observed for intra-day (1.7–2.9%) and inter-day (3.6–6.5%) measurements evaluated on three consecutive days. The performance of CDS and CSPT was also validated in real human urine samples (n = 26) using capillary electrophoresis data as reference. Corresponding Partial Least-Squares (PLS) regression models provided for mean relative errors below 10% in creatinine quantification.     

Photon echoes in single- and trilayer semiconductor films of different nanosized thicknesses and their properties

A femtosecond stimulated photon echo is detected for the first time in thin semiconductor films with thicknesses of 100, 800, and 2400 nm. It is established that relaxation time T ₁ varies with ZnO film thickness, taking values of 0.96, 2.96, and 4.312 ps at thicknesses of 2400, 800, and 100 nm, respectively. For ZnO/Si⁺/Si^? trilayer films, the relaxation time is T ₁ = 12.73 ps.     

Structural variation in palladium nanoparticles of the C-Pd system when dissolving hydrogen in them

The structure of nanocomposites of the C-Pd system has been studied by X-ray diffraction analysis and transmission electron microscopy. Variations in the lattice period of nanosized palladium, the average amount of hydrogen dissolved in it, and the size distribution of palladium nanoparticles have been analyzed as functions of the nanocomposite fabrication temperature. Based on the structural data, the solubility of hydrogen in nanosized palladium has been estimated.     

Phase formation in nanocomposites of the C-Pd-Fe system

Metal-carbon nanocomposites consisting of a carbon matrix with dispersed nanosize bimetallic Pd-Fe particles were obtained. It was established that at 500–700°C, the bimetallic particles form a solid solution of iron in palladium. It was concluded that raising the intensity of infrared pyrolysis to 800–1100°C leads to the formation of intermetallic compounds whose composition depends on the temperature of nano-composite fabrication.     

Complex chromatographic determination of the adulteration of dairy products: A new approach

A new approach to complex chromatographic determination of the adulteration of dairy products was proposed, based on the determination of not only the total fatty acid composition but also the composition of the sterol fraction and the concentration of trans-isomers of fatty acids. Procedures for the chromatographic identification of low-fat dairy products were developed, including the extraction of a water-milkalcohol emulsion with a hexane-ether mixture followed by the chromatographic determination of the sterol fraction and trans-isomers.     

A prototype of a high-voltage platform for the KRION ion source

A high-voltage platform that has been developed for the KRION ion source is described. The platform design concept is explained. The calculations that have been performed of the influence of the design and materials on the source magnetic field make it possible to define a range of materials suitable for manufacturing the platform. The major components of the high-voltage platform, such as a high-voltage power supplier, and decoupling insulators of the high-voltage power source, and the main and supplementary platforms, are chosen and described. It is determined that, to exclude electric breakdowns and corona discharges, one should use an electrically shielded channel with a cryocooler and power supplies for the KRION-source coupling cables.     

On the structural and magnetic properties of amorphous Fe84−x W x B16 alloys in dependence of W content

A series of rapidly solidificated amorphous Fe_84?x W _x B₁₆ (x=0–5) alloys have been studied. A strictly linear decrease ofH _eff versus concentration of W has been observed by Mössbauer spectroscopy.     

Development and validation of a LC-MS/MS method for d-cycloserine determination in human plasma for bioequivalence study

A reliable and high throughput high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and validated for determining levels of the antitubercular drug-d -cycloserine in human plasma. Plasma samples analyte with an internal standard (IS) (niacin) were prepared by solid-phase extraction using Waters Oasis MCX cartridges. The chromatographic separation was performed using the HILIC mode on a YMC-Pack SIL-06 column (150?×?4.6 mm; 3 μm) under isocratic conditions. The run time of analysis was 5 min. The mobile phase consisted of methanol, propanol-2 and 0.075 % trifluoroacetic acid (66.5:28.5:5, v/v/v). Protonated ions formed by turbo ion spray in positive mode were used to detect the analyte and the IS. MS/MS detection was used to monitor the fragmentation of 103–75?m/z for cycloserine and 124 to 80?m/z for niacin (IS) on an API 4000 (AB Sciex) triple quadrupole mass spectrometer. A linear dynamic range of 0.3–30 μg/mL was established for cycloserine using 0.2 mL human plasma and a 1 μL injection volume. The mean relative recovery of cycloserine and niacin were 77.2 and 82.4 %, respectively. The procedure of sample preparation was consistent and reproducible (precision, 0.8–3.4 %; accuracy, 93.8–104.9 %). The method was validated in accordance with requirements of the European Medicines Agency and successfully applied to a bioequivalence study of 250 mg tablet formulations in 23 healthy human subjects.     

Determination of Rhein in blood plasma by HPLC with UV detection and its application to the study of bioequivalence

A method is proposed for determining rhein (an active metabolite of diacerein) in human blood plasma by reversed-phase high-performance liquid chromatography with UV detection. The analyte was selectively extracted from blood plasma by liquid-liquid extraction with a 5% solution of tert-butyl methyl ether in ethyl acetate. The recovery of rhein is 68 ± 3%, LOQ 100 ng/mL. The stability of the analytes and linearity, selectivity, sensitivity, reproducibility, and accuracy of the developed method are evaluated. The pharmacokinetics of diacerein in the oral administration of drug formulations by 18 healthy volunteers is studied.