A fluorescent microspheres-based microfluidic test system for the detection of immunoglobulin G to SARS-CoV-2

Background: The pandemic of the new coronavirus infection, COVID-19, is currently ongoing in the world. Over the years, the pathogen, SARS-CoV-2, has undergone a series of mutational genome changes, which has led to the spread of various genetic variants of the virus. Meanwhile, the methods used to diagnose SARS-CoV-2, to establish the disease stage and to assess the immunity, are nonspecific to SARS-CoV-2 variants and time-consumable. Thus, the development of new methods for diagnosing COVID-19, as well as their implementation in practice, is currently an important direction. In particular, application of systems based on chemically modified fluorescent microspheres (with a multiplex assay for target protein molecules) opens great opportunities. Aim: development of a microfluidic diagnostic test system based on fluorescent microspheres for the specific detection of immunoglobulins G (IgG) to SARS-CoV-2. Methods: A collection of human serum samples was characterized using enzyme-linked immunosorbent assay (ELISA) and commercially available reagent kits. IgG to SARS-CoV-2 in the human serum were detected by the developed immunofluorescent method using microspheres containing the chemically immobilized RBD fragment of the SARS-CoV-2 (Kappa variant) viral S-protein. Results: The level of IgG in the blood serum of recovered volunteers was 9-300 times higher than that in apparently healthy volunteers, according to ELISA (p0.001). Conjugates of fluorescent microspheres with the RBD-fragment of the S-protein, capable of specifically binding IgG from the blood serum, have been obtained. The immune complexes formation was confirmed by the fluorescence microscopy data; the fluorescence intensity of secondary antibodies in the immune complexes formed on the surface of microspheres was proportional to the content of IgG (r 0.963). The test system had a good predictive value (AUC 70.3%). Conclusion: A test system has been developed, based on fluorescent microspheres containing the immobilized RBD fragment of the SARS-CoV-2 S-protein, for the immunofluorescent detection of IgG in the human blood serum. When testing the system on samples with different levels of IgG to SARS-CoV-2, its prognostic value was shown. The obtained results allow us to present the test system as a method to assess the level of immunoglobulins to SARS-CoV-2 in the human blood serum for the implementation in clinical practice. The test system can also be integrated into various microfluidic systems to create chips and devices for the point-of-care diagnostics

Alignment of the ALICE Inner Tracking System with cosmic-ray tracks

37 pages, 15 figures, revised version, accepted by JINSTALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 micron in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10^5 charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.Peer reviewe

Transverse momentum spectra of charged particles in proton-proton collisions at s=900\sqrt{s} = 900 GeV with ALICE at the LHC

The inclusive charged particle transverse momentum distribution is measured in proton-proton collisions at $\sqrt{s} = 900$ GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region $(|\eta|<0.8)$ over the transverse momentum range $0.15<p_{\rm T}<10$ GeV/$c$. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for $|\eta|<0.8$ is $\left<p_{\rm T}\right>_{\rm INEL}=0.483\pm0.001$ (stat.) $\pm0.007$ (syst.) GeV/$c$ and \left_{\rm NSD}=0.489\pm0.001 (stat.) $\pm0.007$ (syst.) GeV/$c$, respectively. The data exhibit a slightly larger $\left<p_{\rm T}\right>$ than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET.Comment: 20 pages, 8 figures, 2 tables, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/390

The ALICE experiment at the CERN LHC

ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries. Its overall dimensions are 161626 m3 with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008

История, ее истоки и конец в контексте философии освобождения

The article concerns history, its origins, goals, and end. The article focuses on two concepts of historical development. One is the concept of the “end of history” by Francis Fukuyama. The article’s authors consider in detail the main provisions of this concept. However, the main emphasis is on the critical reception of this concept within the framework of the philosophy of liberation (represented by Arturo Andrés Roig). Roig’s criticism reveals the Eurocentrism inherent in this concept and shows that it carries the main features inherent in the European worldview and European mentality, which is why it is initially perceived as unsuitable for the Latin American continent. The second concept of historical development analyzed in this article is the earlier concept of the “Axial Age” by K. Jaspers. This concept is often perceived as one of the most striking anti-Eurocentric concepts. At the same time, Jaspers himself is regarded as the founder of the dialogue of cultures and intercultural philosophy and a supporter of civilizational pluralism. The article consistently analyzes three aspects of this concept - the motivation for its creation (presented by Jaspers himself), the criteria for identifying historical and prehistoric cultures (and the associated identification of three centers of the axial period), and the question of the possibility of a new axial age. The article argues that Jaspers’ concept can rightly be called Eurocentric rather than anti-Eurocentric, since both in the initial motivation for creating this concept and in the process of its development and vision of the prospects for the possibility of a new axial age, Jaspers proceeds from the presuppositions characteristic of the European worldview, which is universalized by him and presented as objective and the only correct ones. Ultimately, the study shows that the fight against Eurocentrism is a logical continuation of the latter and carries all the main features of the European mentality.Статья посвящена рассмотрению истории, ее истоков, целей и конца. В статье в центре внимания оказываются две концепции исторического развития. Одна из них - концепция «конца истории» Ф. Фукуямы. Авторы статьи подробно рассматривают основные положения данной концепции, однако основной акцент делается на критической рецепции данной концепции в рамках философии освобождения (в лице одного из ведущих ее представителей - Роига). Критика Роига позволяет вскрыть присущую данной концепции европоцентричность и показывает, что она несет в себе основные черты, присущие европейскому мировосприятию и европейской ментальности, в силу чего изначально воспринимается как неподходящая для латиноамериканского континента. Вторая анализируемая концепцияи сторического развития, анализируемая в данной статье - это более ранняя концепция «осевого времени» К. Ясперса. Данная концепция нередко воспринимается как одна из наиболее ярких антиевропоцентристских концепций, тогда как самого Ясперса записывают в основатели диалога культу и интеркультурной философии и убежденные сторонники цивилизационного плюрализма. В статье последовательно анализируются три аспекта данной концепции - мотивация ее создания (представляемая самим Ясперсом в своей работе), критерии выделения исторических и доисторических культур (и связанное с этим выделение трех центров осевого времени), а также вопрос о возможности новой оси времени. В статье аргументированно показывается, что концепция Ясперса с большим правом может называться европоцентристской, нежели антиевропоцентристской, так как как в исходной мотивации создания данной концепции, так и в процессе ее развития и видении перспектив возможности новой оси времени Ясперс исходит из предпосылок, характерных для европейского мировоззрения, которые им универсализируются и представляются как объективные и единственно правильные. В конечном итоге, проведенное исследование показывает, что борьба с европоцентризмом является логичным продолжением самого европоцентризма и несет в себе все основные черты европейской ментальности

Developing A Method for Determining the Dynamic Parameters of the Operator of A Mobile Fire Engine Based on A Segway

A method for determining the dynamic parameters of the operator of a mobile fire engine based on a segway, which fully characterize its dynamic properties – delay time and inertia was developed. The development of the method includes four stages. At the first stage, the problem of obtaining analytical relationships for determining the dynamic parameters of the operator is solved. These relationships include the frequency characteristics of the operator at a fixed frequency and its static parameter. At the second stage, the choice of a fixed frequency is substantiated using a criterion that minimizes errors in determining the dynamic parameters. It is shown that the fixed frequency for the characteristic parameters of the operator does not exceed 0.5 Hz. The third stage includes substantiation of the procedure for determining the frequency characteristics of the operator and its static parameter. The frequency characteristics of the operator at a fixed frequency and its static parameter are determined numerically. This procedure is based on using the data obtained by measuring the values of the operator's transfer function at fixed time intervals. To obtain data, an interactive analog engine is used, which can also perform the functions of a simulator. The time intervals are chosen according to the Kotelnikov-Nyquist-Shannon theorem. At the last stage, the procedure for determining the dynamic parameters of the operator of a segway-based mobile fire engine is described. It is shown that the error in determining the dynamic parameters of the operator of a mobile fire engine does not exceed 9.0 %, if the error in determining its frequency characteristics at a frequency of 2.5 s–1 does not exceed 2.0

Size-dependent hydrogen uptake behavior of Pd nanoparticles revealed by photonic crystal surface waves

We present an optical method of study of nanoparticle properties using photonic crystal surface waves. Palladium nanoparticles were deposited on a surface of a one-dimensional photonic crystal, which supports the propagation of p-polarized optical surface waves. The changes in the nanoparticle properties, such as its dimension and refractive index, were monitored through angle interrogation of the photonic crystal surface waves. The interaction of palladium nanoparticles with hydrogen was detected with this method. The size-different hydrogen uptake behavior by 2 and 6 nm diameter Pd nanoparticles results in qualitatively different response of the optical signal, viz., in the different signs of such a response. This not only confirms the absence of the alpha- to beta-phase transformation for the smallest palladium nanoparticles, but is a plausible indication that hydrogen donates its electrons to a collective electron band of the metal. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3690085

Determining the Source Data to Form a Control Algorithm for Hydrogen Generators

Constructing an algorithm to control the technical condition of hydrogen generators employs using their amplitude-frequency and phase-frequency characteristics as the source data. Applying the classic method for defining such characteristics predetermines several drawbacks. One of the significant disadvantages is the long time required to form an array of source data. To shorten this time, determining the frequency characteristics of a hydrogen generator is carried out based on the results of measuring its transition function over discrete moments of time. During these time moments, the transition function is approximated by the Heaviside functions. Such an approach reduces the time for determining the frequency characteristics of a hydrogen generator by 1–2 orders. Applying the Kotelnikov–Nyquist–Shannon theorem for determining these discrete time moments is due to uncertainty about the maximum frequency of the test-signal spectrum.To avoid this uncertainty, discrete time moments for measuring the transitional function of a hydrogen generator are chosen under condition for the permissible error of its approximation.The error of approximation is determined based on the result from solving a test-problem that uses model characteristics as a standard for the frequency characteristics. It has been shown that at a sampling interval of (0.25¸2.5) ms the magnitude of such an error does not exceed 1.7 %.Inertial properties of the device that forms a test-impact have been taken into consideration. It has been shown that it is appropriate to apply such a procedure if the equivalent time constant of such a device exceeds the magnitudes of time constants for a hydrogen generator. The inertial properties are taken into consideration by introducing an additional multiplier, which contains the equivalent time constant of the device, to the analytical expressions for the frequency characteristics of a hydrogen generato

Estimating the Influence of the Wind Exposure on the Motion of an Extinguishing Substance

One of the tasks to be solved when deploying fire extinguishing systems is to determine the range of the fire extinguishing agent supply to the combustion center. This problem is solved using data on the trajectory of the fire-extinguishing agent in the combustion center. The presence of wind impact on the process of supplying a fire extinguishing agent will lead to a change in its trajectory. To take into account wind impact, it becomes necessary to assess the result of such impact. Using the basic equation of dynamics for specific forces, a system of differential equations is obtained that describes the delivery of a fire extinguishing agent to the combustion center. The system of differential equations takes into account the presence of wind impact on the movement of the extinguishing agent. The presence of wind action is taken into account by the initial conditions. To solve such a system, the integral Laplace transform was used in combination with the method of undefined coefficients. The solution is presented in parametric form, the parameter of which is time. For a particular case, an expression is obtained that describes the trajectory of the supply of the extinguishing agent into the combustion center. Nomograms are constructed, with the help of which the operative determination of the estimate of the maximum range of the fire-extinguishing agent supply is provided. Estimates are obtained for the time of delivery of a fire-extinguishing agent to the combustion center, and it is shown that for the characteristic parameters of its delivery, this value does not exceed 0.5 s. The influence of wind action on the range of supply of a fire extinguishing agent is presented in the form of an additive component, which includes the value of the wind speed and the square of the time of its delivery. To assess the effect of wind impact on the movement of the fire extinguishing agent, an analytical expression for the relative error was obtained and it was shown that the most severe conditions for supplying the fire extinguishing agent to the combustion center, the value of this error does not exceed 5.5%. Taking into account the wind effect when assessing the range of supply of a fire-extinguishing agent makes it possible to increase the efficiency of fire-extinguishing systems due to its more accurate delivery to the combustion cente