Classical Determination Methods Research Articles

АНАЛИЗ ВОЗМОЖНОСТЕЙ ПРИМЕНЕНИЯ НОВОГО МЕТОДА ОПРЕДЕЛЕНИЯ УРОВНЯ D-ДИМЕРА В ПЛАЗМЕ КРОВИ У БОЛЬНЫХ С COVID-19 НА ГОСПИТАЛЬНОМ ЭТАПЕ

Introduction. The outbreak of the novel viral infection SARS-CoV-2 and its associated pandemic has generated significant interest among professionals regarding the role of D-dimer as a marker. D-dimer not only reflects the intensity of hemostatic and fibrinolytic reactions but also holds prognostic value. However, the standardization of D-dimer determination remains elusive, as the findings are known to depend on the completeness of fibrinolysis in the vasculature. Objective. This study aims to investigate the objective values of D-dimer levels, taking into consideration the concentration of its terminal fragments in plasma, specifically in patients with intravascular thrombosis associated with coronavirus infection. Materials and Methods. The study involved the examination of sodium citrate-stabilized plasma from 90 patients with severe COVID-19 who required respiratory support upon admission to the intensive care unit (ICU). The ICU mortality rate was 50% within 14 days. Additionally, a control group of 78 healthy individuals was included. The quantitative determination of D-dimer in human plasma was conducted using the Auto Red D-Dimer 700 (Helena Bioscience) and Sysmex CA1500 coagulation analyzer (Sysmex Corporation). Fibrinolysis was stimulated in vitro by streptokinase during sample preparation. The assessment was based on the analysis of blood plasma before and after the administration of the fibrinolysis activator. Results. Using the classical method of determination, D-dimer levels exceeded the cut-off value (300 ng/ml) in 61 out of 90 patients (67.8%). After fibrinolysis stimulation with streptokinase, this number increased to 66 (73.3%). Compared to the survival group, the fatal outcome group exhibited a 143.6% higher D-dimer level using the classical approach (p=0.2355). With the new approach involving streptokinase, the increase was 181.2% (p=0.0257). In one-fifth of fatal cases, the streptokinase-induced D-dimer concentration was more than twice the baseline obtained through the classical approach. Conclusion. The proposed approach for quantitatively determining D-dimer, which incorporates the use of streptokinase, provides more accurate data regarding the plasma concentration of D-dimer neoantigens. These findings establish a potential direction for standardizing such studies in clinical practice, particularly for determining treatment strategies for patients with COVID-19.

A fast and direct determination of bisphenol S in thermal paper samples using paper spray ionization mass spectrometry.

Concerns about human health regarding the large use of bisphenol A in thermal papers have led to its replacement by bisphenol S. Analyses of bisphenols require several sample pretreatment steps, which are laborious, expensive, and time-consuming. A paper spray ionization mass spectrometry (PSI-MS) was developed to detect and quantify bisphenol S in three different brands of thermal papers commercially available. Parameters such as paper size, and paper position relative to the mass spectrometer inlet were evaluated. The analyses were performed in selected ion monitoring mode on a linear ion trap mass spectrometer. The developed method presented absolute recovery values ranging from 92.2 to 109.04%, accuracy values from -1.2 to 9.0%, and inter assay precision from 1.8 to 5.6% and enabled LOD as low as 5 ng g-1. The concentration of bisphenol S in all of the three brands of BPA-free thermal papers evaluated ranged from 1.36 to 6.77 μg g-1, and the concentrarion of BPA ranged from 6.56 to 16.4 μg g-1 in all samples of thermal paper evaluated. The PSI-MS method described here was comparable to the conventional ones, such as liquid chromatography coupled with mass spectrometry and gas chromatography coupled with mass spectrometry described in the literature. The present study proved to be practical, fast, and efficient for the direct determination of bisphenol S in thermal papers. Furthermore, the methodology here described showed to be a promising alternative to replace the classical methods for determination of bisphenol S, due to its simplicity, and no needing of any sample pretreatment.

Klasične metode hemijske stabilnosti - komparativna analiza za barute

The main ingredient of gunpowder is nitrocellulose. For slowing down the catalytical decomposition process, predominated stabilizer diphenylamine is in use for single-base gunpowder, as well as for propellants. On the other hand, the stabilizer wears out over time, which causes changes in chemical stability of energetic materials. One of the classical methods for determination the chemical stability is the Bergman-Jung method, which has two subgroups. This paper presents comparative analyses for twelve NC and five NCD gunpowder. Namely, both subgroups are based on the calculation of the volume of nitric oxide gases, but the difference between them depend on the method of collecting and determining released gases.

Wavelength-Shift-Based Colorimetric Sensing for Peroxide Number of Edible Oil Using CsPbBr3 Perovskite Nanocrystals.

The peroxide number of edible oil relates to its quality. The classical determination methods for the peroxide number are still unsatisfactory due to their complexity and poor reproducibility in the analytical process and their incapability of field rapid detection. In this study, a novel wavelength-shift-based visual method has been developed for the peroxide number determination of edible oil using halide perovskite nanocrystals (CsPbBr3 NCs). In the analysis, the edible oil sample underwent redox reactions with a part of oleylammonium iodide (OLAM-I) in advance. Then, the halogen exchange occurred between the added CsPbBr3 NCs and the iodide ions from the residual OLAM-I. The resulting wavelength shift of the fluorescence emission reflects the peroxide number in the edible oil sample. Under the ultraviolet light excitation at 365 nm, the apparent color of the photoluminescence could directly be compared with a color chart to determine and qualify the peroxide number. Using the approach, the visual detection of the peroxide number of edible oil samples on site could be realized. The detection process takes only ∼15 min and is convenient and accurate.

Physiological responses and transcriptome analysis of the Kochia prostrata (L.) Schrad. to seedling drought stress.

Kochia prostrata is a good forage plant, which has important economic and ecological value in arid and semi-arid regions of China. Drought is one of the main factors affecting its productivity. At present, there are few studies on the mechanism of drought resistance. In order to reveal the changes of physiological and biochemical indexes, stomatal structure and gene expression profiles of Kochia prostrata under drought treatment, the classical determination method and high-throughput Illumina Hiseq sequencing platform were applied to the control group (CK) and drought treatment group of Kochia prostrata. The results showed that under the condition of moderate to mild drought stress, the SOD activity reached the maximum value of 350.68 U/g min on the 5th day of stress, and under the condition of severe drought stress, the SOD activity reached the maximum on the 2nd day of stress. The accumulation of Proline remained at a high level on the 5th day of stress, and there was at least one epidermal cell interval between the two adult stomatal of the leaf epidermis, so that the evaporation shell of each stomatal did not overlap, it ensures the efficient gas exchange of the stomatal, indicating that the Kochia prostrata has strong drought resistance. A total of 1,177.46 M reads were obtained by sequencing, with a total of 352.25 Gbp data and Q30 of 85%. In the differential gene annotation to the biological process (BP), a total of 261 GO terms were enriched in the up-regulated genes, and a total of 231 GO terms were enriched in the down-regulated genes. The differentially expressed genes (DEGs) were obtained in 27 KEGG metabolic pathways, which laid a foundation for revealing the molecular mechanism of drought tolerance.

Influence of compression on soil characterization by X ray fluorescence

The study of soil mineralogy has been highlighted in recent years, as well as the search for alternative analytical techniques for soil analysis. The classical methods for determination of total oxides in soil expose the analyst to chemical hazards and require time-consuming sample preparation and decomposition. XRF is being employed for this type of analysis, since it does not requires the use of chemical solvents. However, the technique requires samples with a smooth and homogeneous surface. The objective of this study was to verify if the soil compression (in 5 t, 10 t and 15 t) influenced the determination of the oxides content in soils of different municipalities of the state of Rio Grande do Sul (Passo Fundo and Cruz Alta). The experiments and the analysis of the data showed that the XRF technique presented low coefficients of variation and low standard deviation and did not have statistical difference between the samples of the same type of soil. The lower variations of these analytical criteria were obtained for soil analysed in the form of powder. Therefore, the most suitable form for the analysis of these soils is in the sedimentary form, however, it is still recommended the use of statistical tools to verify the reliability of the data obtained.

ABOUT TRACK CIRCUIT CALCULATION METHOD DEPENDENT ON FERROMAGNET PROPERTIES IN CONDITIONS OF TRACTION CURRENT NOISE INFLUENCE

Purpose. The work is intended to investigate the electromagnetic processes in impedance bond in order to improve noise immunity of track circuits (TC) for safe railway operation. Methodology. To achieve this purpose the methods of scientific analysis, mathematical modelling, experimental study, a large-scale simulation were used. Findings. The work examined the interference affecting the normal performance of track circuits. To a large extent, part of track circuit damages account for failures in track circuit equipment. Track circuit equipment is connected directly to the track line susceptible to traction current interference, which causes changes in its electrical characteristics and electromagnetic properties. Normal operability, performance of the main operating modes of the track circuit is determined by previous calculation of its performance and compilation of regulatory tables. The classical method for determination of track circuit parameters was analysed. The classical calculation method assumes representation of individual sections of the electrical track circuit using the quadripole network with known coefficients, usually in the A-form. Determining the coefficients of linear element circuit creates no metrological or mathematical difficulties. However, in circuits containing nonlinear ferromagnets (FM), obtaining the coefficients on the entire induction change range in the cores is quite a difficult task because the classical methods of idling (I) and short circuit (SC) are not acceptable. This leads to complicated methods for determining both the module and the arguments of quadripole network coefficients. Instead of the classical method, the work proposed the method for calculating the track circuit dependent on nonlinear properties of ferromagnets. Originality. The article examines a new approach to the calculation of TC taking into account the losses in ferromagnets (FM), without determination of equivalent circuit quadripole network coefficients. When building the FM reversal model in parallel magnetic fields, the most accurate methods are the approximation ones that take into account not only the changes in values and over time, but also their derivatives. The development of computer hardware and software makes real the mathematical methods for calculating TC with significant change in ferromagnetic inductance, including the saturation areas. Herewith, it is important to search for approximating analytical expression that describes the dynamic limit hysteresis loop (HL). Practical value. The changes in the electrical parameters of the same TC were analysed using the classical and the new calculation methods, the difference made less than 10%. The work introduced some measures to increase operational noise immunity of TC.

Pigmentos fotossintéticos em azevém suscetível e resistente ao herbicida glyphosate

O objetivo deste trabalho foi quantificar o teor de pigmentos fotossintéticos em biótipos de azevém (Lolium multiflorum) suscetíveis e resistentes ao glyphosate, por dois diferentes métodos, bem como, estabelecer uma correlação entre o índice de clorofila obtido pelo equipamento portátil e a metodologia clássica (clorofila extraível). Um experimento foi conduzido em casa de vegetação e laboratório da Universidade Federal de Santa Maria, Campus de Frederico Westphalen - RS - em esquema fatorial 2X4, em que o fator A equivaleu aos biótipos de azevém (resistente e suscetível a glyphosate) e o fator B a estádios de desenvolvimento das plantas (afilhamento, vegetativo I e II, e reprodutivo). O biótipo de azevém suscetível apresentou maiores teores de clorofila a, b, total e carotenoides, inferindo em um maior potencial competitivo frente ao biótipo resistente ao herbicida. A determinação do teor de clorofila pelo determinador portátil apresentou alta correlação com o método clássico de determinação de pigmentos fotossintéticos, podendo, assim, ser usado com precisão na avaliação deste, proporcionando economia de tempo bem como do uso de reagentes.

Determination of photosynthetic pigments in fleabane biotypes susceptible and resistant to the Herbicide Glyphosate

Chlorophylls and carotenoids are the main photosynthetic pigment in plants. In the weeds, the greatest amount of photosynthetic pigments can result in high competitiveness of the species. The aim of this study was to quantify the content of photosynthetic pigments in biotypes of fleabane (Conyza bonariensis) susceptible and resistant to glyphosate, by two different methods, as well as a correlation between chlorophyll content obtained by portable and classical methodology (extractable chlorophyll). An experiment was conducted in greenhouse and laboratory, 2 x 5 factorial scheme, where factor A was equivalent to biotypes of fleabane (resistant and susceptible to glyphosate) and factor B to developmental stages plants (rosette vegetative I, II and III and reproduction). At all stages of development, fleabane plants were evaluated with the portable determiner (chlorophyll content) and then the same leaves were subjected to classical methodology laboratory (extractable pigments). The resistant biotype of fleabane showed higher contents of chlorophyll a, b, and total carotenoids, inferring a greater competitive potential regarding the susceptible population to the herbicide. The portable determiner of chlorophyll showed high correlation with the classical method of determination of photosynthetic pigments, and can thus be used to accurately assess this, saving time and reagents.

Application of genetic algorithm in calculation of the phase behavior of binary and ternary polymer solutions

A genetic algorithm as an optimization procedure has been developed to predict the phase behavior of polymer solutions. The phase equilibrium diagrams of binary and ternary polymer solutions have been determined using the appropriate form of Flory–Huggins free-energy function for polymer solutions. A concentration and temperature dependent form of the interaction parameter has been used to reflect the effect of temperature and polymer properties in the free-energy form. The proposed genetic algorithm is applied to compare the phase behavior results of some typical polymer solutions with the results of the classical determination methods and then applied to some conventional ternary polymer solutions as polymer–solvent–nonsolvent systems. The proposed algorithm use a set of individual states as the initial chromosomes and uses the general rules as crossover, mutation, and with use of a fractional objective function determines the binodal points or the phase diagram boundaries of polymer solutions. The properties of an industrially relevant polymer solution, a polystyrene–cyclohexane solution, have been used to emphasize on the industrial application of the proposed algorithm. The algorithm has been used to predict the phase behavior of the two polymer–solvent–nonsolvent systems as polystyrene-butanone-methanol and polystyrene-butanone-propanol at three different temperatures and results show good agreement with the experimental observations. The algorithm also has the capability to predict both the concentration-independent and concentration-dependent interaction parameters among the different components. The genetic algorithm is an easy-to-use, state-of-art, and very fast optimization tool, and has very strong capability to solve nonlinear systems in chemical and polymer engineering topics.

Novel permittivity test for determination of yeast surface charge and flocculation abilities

Yeast flocculation has been found to be important in many biotechnological processes. It has been suggested that flocculation is promoted by decreasing electrostatic repulsion between cells. In this study, we used an unconventional rapid technique—permittivity test—for determination of the flocculation properties and surface charge values of three industrial yeast strains with well-known flocculation characteristics: Saccharomyces cerevisiae NCYC 1017 (brewery, ale), S. pastorianus NCYC 680 (brewery, lager), and Debaryomyces occidentalis LOCK 0251 (unconventional amylolytic yeast). The measurements of permittivity were compared with the results from two classical methods for determination of surface charge: Alcian blue retention and Sephadex DEAE attachment. The permittivity values for particular strains correlated directly with the results of Alcian blue retention (r = 0.9). The results also confirmed a strong negative relationship between the capacitance of yeast suspensions and their flocculation abilities. The highest permittivity was noted for the ale strain NCYC 1017, with weak flocculation abilities, and the lowest for the flocculating lager yeast NCYC 680. This paper is the first to describe the possibility of using a rapid permittivity test to evaluate the surface charge of yeast cells and their flocculation abilities. This method is of practical value in various biotechnological industries where flocculation is applied as a major method of cell separation.

Evaluation of Iron Core Quality for Resistance Spot Welding Transformers Using Current Controlled Supply

This paper reflects a newly developed method for evaluation of iron core quality for resistance spot welding (RSW) transformers. The classical methods for determination of the iron core quality are mostly based on a sinusoidal excitation. The proposed method is based on corresponding excitation by hysteresis controlled current in primary winding under no load operation, whereas consequently the primary current changes between its maximum and minimum value. Therefore, the operation point during the test is defined by the maximum magneto motive force (mmf) of the magnetic circuit. The tested iron core that reaches higher value of the magnetic flux density with the same maximum mmf, has lower average magnetic resistance and it is categorized as a better one, for the discussed RSW application. Furthermore, the value of the input reactive power is considered as an additional indicator for evaluation of the iron core quality. The proposed method is fully verified with numerical computations and laboratory measurements. The main advantage of the proposed method is that no extra equipment is required when testing the RSW systems.

Kinematical and dynamical analysis of closed kinematic chains using graphs and contour equations

AbstractThe classical method of determination of velocities and accelerations of the closed kinematical chains consists in calculation of derivatives of the position vector in relation to time. In the paper, the methods of kinematical and dynamical analysis of the closed kinematical systems based upon the graph representation are presented. Planetary gears are the exemplary mechanical systems which have been considered. Two types of graphs are assigned to the gears. Both graphs allow for derivation of systems of equations which constitute the kinematical analysis. The results of classical and graph‐based methods were compared. The graph based methods allow for further considerations like e.g. synthesis, enumeration of design solutions and even evolutionary design of mechanisms. Dynamical analysis is shown in graphical form, only. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

BOD analysis of industrial effluents: 5 days to 5 min

Abstract Wastewater generation and its subsequent treatment is a major problem for every industry and for the society as well. Prior to treatment, the wastewaters need to be monitored so as to permit their discharge into the local water resources. Amongst all the parameters for which the wastewaters are monitored, biochemical oxygen demand (BOD), is one of the most important and frequently used parameters for estimating the level of water pollution. The control of wastewater treatment plants is very difficult or even impossible using the classical determination method for BOD because of its high time consumption (3–5 days). The need for fast, portable and cost-effective methods for environmental monitoring has stimulated the production of a variety of field analytical tools such as biosensors. Biosensors are device that have several unique features such as compact size, simple to use, one step reagentless analysis, low cost and quick-real time results. The conventional BOD measurement requires 3–5 days, which a microbial BOD biosensor senses within minutes. A number of microbial BOD sensors have been developed nationally and internationally. The drawback of such developed sensors is that they cannot be used for all types of industrial and domestic wastewaters. Our developed BOD biosensor is based on a pre-tested, synergistic formulated microbial consortium. It is capable to sense the BOD load of a wide variety of synthetic as well as industrial wastewaters having low–moderate–high biodegradability within minutes. The sensor BOD values show a good linear relationship with the BOD values obtained using the conventional method upto a GGA concentration of 90 mg/l (r=0.938). BOD values of real wastewater samples from different industries viz, distillery dairy and tannery were analysed using the developed sensor. The BOD sensor results were found to be comparable with those obtained using the conventional 3-day method.

Critical appraisal of classical methods for determination of mesopore size distributions of MCM-41 materials

Abstract Classical methods for evaluation of the pore size distributions (PSD) from low temperature (77 K) nitrogen adsorption isotherms were compared by using a series of hexagonally ordered mesoporous silicas (MCM-41) of different pore sizes. This comparison involved the methods proposed by Barrett, Joyner and Halenda (BJH), Dollimore and Heal (DH) as well as Broekhoff and de Boer (BdB) simplified recently by Lukens et al. These methods were examined by using the statistical film thickness (t-curve) reported by Halsey (H), and Kruk, Jaroniec and Sayari (KJS). A detailed comparison of aforementioned methods shows that the BJH method with Kelvin-type equation and t-curve determined on the basis of MCM-41 materials as suggested by KJS provides the most reliable PSD. In contrast to other methods, the BJH–KJS method gives an accurate estimate of the pore width and reproduces the pore volume.

Determination of BOD-values of starch-containing waste water by a BOD-biosensor

The control of waste water plants is difficult or even impossible using the classical determination method for biological oxygen demand (BOD), because of its high time consumption of five days. A determination within some minutes is possible by microbial BOD-sensors. However, high molecular weight substances cannot be detected, a problem which can be overcome by the use of additional enzymes. For the application in a flow-through system to analyse starch containing waste water, α-amylase and amyloglucosidase were immobilized by adsorption to polystyrene or polypropylene carriers followed by crosslinking. Furthermore, covalent coupling to different nylon carriers, derivatives of chitin, silanized glass beads and silanized beads of foamed glass was tried. Chitin and Lewatit were the best suited carriers for the immobilization of α-amylase and amyloglucosidase. Two glass columns were filled with the immobilized enzymes and inserted into a commercial BOD-sensor containing the yeast Trichosporon cutaneum as biological component. The system was stable for more than two months under storage and one month under working conditions. A comparison of different starch types resulted in a hydrolysis of more than 80% in case of potato starch whereas grain starch was hydrolized only for 40–50%. Sensor-determined BOD-values of waste water with potato starch were nearly identical with BOD 5-values resulting from the classical method.

On the systematic errors of the determinations of the absolute orientation of the meridian marks

The classical method of determination of the absolute azimuth (or Bessel's parameter “n”) can secure sufficiently precision for RA from observations of stars at high geographical latitudes during polar night only.

Water phases in rat striated muscles as determined by T2 proton NMR relaxation times

The spin echo decay curve of NMR protons in in-vitro rat muscle is two or three exponential as Hazlewood demonstrated in 1974. This author hypothesized that the longer T 2 component is extracellular water and that the medium T 2 is intracellular water. Our purpose was to test the histological significance of these two T 2. Variations of water contents in two types of rat muscles were induced by electrical stimulation and osmotic diuresis and their incidence on the decomposition of the proton spin echo signal analysed. Decomposition of signal in resting muscles revealed two phases with T 2 values similar to the Hazlewood's: a short phase, S, with T 2 of 40 ms (20 MHz, 276°K) representing 90–97% of the total signal and a long one, L, with T 2 of 100–120 ms representing 3–10% of the signal. Increasing vascular volume appeared to increase the percentage of phase (L) in the total signal. Osmotic diuresis decreased the volume of the phase (S) and increased the volume of the phase (L). The use of Gd-DTPA allowed to differentiate the vascular compartment: Gd DTPA decreased in a great extent the T 2 values of phase (L) and in low extent the T 2 values of phases (S). From these results, it appears that phase (L) could correspond to vascular volume and that phase (S) would be interstitial and intracellular water. Elements of comparison with classical methods for determination of water compartmentation in tissues are given.

A modification of the classical quadrature method for locating zeros of analytic functions

The classical method for determination of a simple zeroa of an analytic functionf(z) inside a closed contourC by using the formulaa=(2πi)−1 e C [zf'(z)/f(z)]dz is reconsidered and modified. The modification consists in using the Cauchy theorem instead of the Cauchy formula and, further, evaluating numericallya as one of the zeros of an appropriate polynomial depending on the quadrature rule used. The case of circular contours with application of the trapezoidal rule is considered in detail and numerical results are presented.

Sur la thermogravimétrie des précipités analytiques: Dosage du cobalt

With the help of the CHEVENARD thermobalance, the authors have traced the pyrolysis curves used for the gravimetric determination of cobalt. A number of methods giving bad results have been rejected, and twelve methods are recommended for the automatic determination, in particular, the excellent anthranilate method of WENGER et al. Some remarks are made on the limits of stability of the various oxides. A critical investigation of purpureo-cobaltic molybdate has been carried out. Moreover, a discussion on the stability of the sulphate (the classical method of determination) and on the difference between the precipitates formed by α-nitroso β-naphthol with bivalent and trivalent cobalt is also given.