Search Results (37)

Background: Long COVID is characterized by persistent symptoms following acute SARS-CoV-2 infection. This study aims to evaluate immune system markers, including antigen-specific antibodies, B cell subsets, and Th2-related cytokines, in individuals with long COVID and to investigate their potential impact on the development of this condition. Methods: We analyzed blood plasma from 63 individuals diagnosed with long COVID based on clinical presentation and 47 healthy individuals with COVID-19 history but no clinical symptoms. Antigen-specific IgG antibodies were measured using commercial ELISA kits. Lymphocyte subpopulations were assessed via flow cytometry and a gating strategy based on CD27 and CD38. Th2 cytokines (IL-4, IL-5, IL-13) were quantified using the xMAP multiplex assay. Results: We noted no significant differences in IgG levels between groups. Notably, individuals with long COVID demonstrated a higher percentage of naive mature B cells (CD27−CD38+), while transitional (CD27−CD38+++) and double-negative (DN, CD27−CD38-) cells were significantly reduced. Elevated levels of IL-5 and IL-13 were observed in long COVID patients. Classification analysis revealed that the percentage of transitional B cells (CD27−CD38+++) was a strong predictor of long COVID. Conclusions: Our findings highlight alterations in B cell dynamics among individuals with long COVID, which may contribute to autoimmune processes. Full article

Recent advancements have expanded the applications of fiber-optic distributed acoustic sensors (DAS), including their use in monitoring the acoustic activity of insects, which can be either harmful or beneficial to agriculture. Previous studies have demonstrated the capability of DAS to record and analyze insect-generated acoustic signals in real-world conditions; however, these studies primarily involved large insect colonies. In this work, a fiber-optic DAS is used for the first time to record the sounds produced by a single insect under controlled laboratory conditions. This was achieved using an optimized and cost-effective experimental setup designed and assembled, including a specially developed and manufactured sensing element. The results demonstrate that the fiber-optic DAS effectively captures the acoustic signals of the Madagascar hissing cockroach (Gromphadorhina portentosa), including both the mechanical interactions of the insect with the optical fiber and the characteristic hissing sound produced in response to external stimulation. Full article

John Cottingham argues that traditional university modules in the philosophy of religion take us into a ‘very abstract domain that is often far removed from religion as it actually operates in the life of the believer’. This paper makes four moves based on Cottingham. First, it argues that the application of Ludwig Wittgenstein’s methods supports and facilitates a shift to the anthropological in the philosophy of religion (as evidenced in the work of Mikel Burley). Second, literature is examined as a tool for doing the philosophy of religion, following Danielle Moyal-Sharrock’s notion of the literary text as surveyable representation. Three works are investigated, namely Silence by Shūshaku Endō, The Brothers Karamazov by Fyodor Dostoevsky, and the Gospel of John. It is argued that, far from being merely illustrative of religion, story is (in its widest sense) constitutive of belief. Third, it is shown how Wittgenstein’s remarks on mysticism in the Tractatus Logico-Philosophicus can be read as a transmutation of literary writing that creates a non-abstract mysticism of the world. Wittgenstein’s remarks are placed in dialogue with Angelus Silesius’s poetry and Leo Tolstoy’s The Gospel in Brief. Fourth, the relevance of Wittgenstein to the current debate on cultural Christianity is brought out. Philosophers of religion must take leave of the abstract, if only to return to it and to view it differently. Wittgenstein’s thought is too important to ignore in this venture. Full article

Standard single-mode telecommunication optical fiber is still one of the most popular in distributed acoustic sensing. Understanding the acoustic, mechanical and optical features of various fibers available currently can lead to a better optimization of distributed acoustic sensors, cost reduction and adaptation for specific needs. In this paper, a study of the performances of seven fibers with different coatings and production methods in a distributed acoustic sensor setup is presented. The main results include the amplitude–frequency characteristic for each of the investigated fibers in the range of acoustic frequencies from 100 to 7000 Hz. A single-mode fiber fabricated using the modified chemical vapor deposition technique together with a polyimide coating has shown the best sensitivity to acoustic events in the investigated range of frequencies. All of this allows us to both compare the studied specialty fibers with the standard single-mode fiber and choose the most suitable fiber for a specific application, providing an enhancement for the performance of distributed acoustic sensors and better adaptation for the newly aroused potential applications. Full article

In this review, we summarize the latest advances in the design of optical frequency-domain reflectometers (OFDRs), digital signal processing, and sensors based on special optical fibers. We discuss state-of-the-art approaches to improving metrological characteristics, such as spatial resolution, SNR, dynamic range, and the accuracy of determining back reflection coefficients. We also analyze the latest achievements in the OFDR-based sensors: the accuracy of spatial localization of the impact, the error in detecting temperatures, deformation, and other quantities, and the features of separate measurement of various physical quantities. We also pay attention to the trend of mutual integration of frequency-domain optical reflectometry methods with time-domain optical reflectometry, which provides completely new sensing possibilities. We believe that this review may be useful to engineers and scientists focused on developing a lab setup, complete measurement instrument, or sensing system with specific requirements. Full article

The present study investigates the photocatalytic properties of hydrothermally synthesized TiO₂ nanowires (NWs) for CO₂ reduction in H₂O vapor. It has been demonstrated that TiO₂ NWs, thermally treated at 500–700 °C, demonstrate an almost tenfold higher yield of products compared to the known commercial powder TiO₂ P25. It has been found that the best material is a combination of anatase, TiO₂-B and rutile. The product yield increases with increasing heat treatment temperature of TiO₂ NWs. This is associated with an increase in the degree of crystallinity of the material. It is shown that the best product yield of the CO₂ reduction in H₂O vapor is achieved when the TiO₂ NW photocatalyst is heated to 100 °C. Full article

Background: The problem of identifying vaccine-specific T-cell responses is still a matter of debate. Currently, there are no universal, clearly defined, agreed upon criteria for assessing the effectiveness of vaccinations and their immunogenicity for the cellular component of immunity, even for healthy people. But for patients with inborn errors of immunity (IEI), especially those with antibody deficiencies, evaluating cellular immunity holds significant importance. Aim: To examine the effect of one and two doses of inactivated adjuvanted subunit influenza vaccines on the expression of endosomal Toll-like receptors (TLRs) on the immune cells and the primary lymphocyte subpopulations in patients with common variable immunodeficiency (CVID). Materials and methods: During 2018–2019, six CVID patients received one dose of a quadrivalent adjuvanted influenza vaccine; in 2019–2020, nine patients were vaccinated with two doses of a trivalent inactivated influenza vaccine. The proportion of key lymphocyte subpopulations and expression levels of TLRs were analyzed using flow cytometry with monoclonal antibodies. Results: No statistically significant alterations in the absolute values of the main lymphocyte subpopulations were observed in CVID patients before or after vaccination with the different immunization protocols. However, after vaccination, a higher expression of TLR3 and TLR9 in granulocytes, monocytes, and lymphocytes was found in those patients who received two vaccine doses rather than one single dose. Conclusion: This study marks the first instance of using a simultaneous two-dose vaccination, which is associated with an elevated level of TLR expression in the immune cells. Administration of the adjuvanted vaccines in CVID patients appears promising. Further research into their impact on innate immunity and the development of more effective vaccination regimens is warranted. Full article

Interest in fullerene-based polymer structures has renewed due to the development of synthesis technologies using thin C₆₀ polymers. Fullerene networks are good semiconductors. In this paper, heterostructure complexes composed of C₆₀ polymer networks on atomically thin dielectric substrates are modeled. Small tensile and compressive deformations make it possible to ensure appropriate placement of monolayer boron nitride with fullerene networks. The choice of a piezoelectric boron nitride substrate was dictated by interest in their applicability in mechanoelectric, photoelectronic, and electro-optical devices with the ability to control their properties. The results we obtained show that C₆₀ polymer/h-BN heterostructures are stable compounds. The van der Waals interaction that arises between them affects their electronic and optical properties. Full article

We have demonstrated a simple all-fiber thulium (Tm) laser Q-switched by stimulated Brillouin scattering (SBS). The maximum output pulse energy was 80 μJ. This allowed us to generate a broadband spectrum directly at the laser outputs. For the first time, we measured the fine structure of the output pulses with a resolution of less than 100 ps. It was found that the SBS Q-switched laser is capable of generating bunches of picosecond pulses. The effect of modulation instability on the pulse decay is discussed. The potential application of the investigated laser radiation for producing destructive effects on soft biological tissues has been demonstrated. Full article

Pulse wave measurement is a highly prominent technique used in biomedical diagnostics. The development of novel cost-effective pulse wave sensors will pave the way to more advanced healthcare technologies. This work reports on a pulse wave optical fiber sensor interrogated by a smartphone. The sensor performance was tested in terms of signal to noise ratio, repeatability of demodulated signal and suitability of demodulated signals for the extraction of information about direct and reflected waves. The analysis showed that the observed fluctuations of signal parameters are caused by variability of the state of the cardiovascular system and not by the system noise. Full article

This work studies the application of low-cost noise reduction algorithms for the data processing of distributed acoustic sensors (DAS). It presents an improvement of the previously described methodology using the activation function of neurons, which enhances the speed of data processing and the quality of event identification, as well as reducing spatial distortions. The possibility of using a cheaper radiation source in DAS setups is demonstrated. Optimal algorithms’ combinations are proposed for different types of the events recorded. The criterion for evaluating the effectiveness of algorithm performance was an increase in the signal-to-noise ratio (SNR). The finest effect achieved with a combination of algorithms provided an increase in SNR of 10.8 dB. The obtained results can significantly expand the application scope of DAS. Full article

We report on a model of a fiber frequency comb generator that develops an approach to harmonically mode-locked fiber laser design based on dissipative four-wave mixing. In our version of this approach, we assume an amplifying one-dimensional photonic crystal as a key cavity element combining the properties of an intra-cavity filter and a power amplifier. Using standard equations describing the signal transformation in the ring cavity and the output fiber cascade, we have demonstrated the possibility of the application of the proposed model as a generator of broadband frequency comb with controllable line spacing. Full article

This study demonstrates the ability to control the properties of TiO₂–CuO_x composite layers for photocatalytic applications by using a simple electrophoretic deposition method from isopropanol-based suspension. To obtain uniform layers with a controlled composition, the surfactant sodium lauryl sulfate was used, which influenced the electrophoretic mobility of the particles and the morphology of the deposited layers. The TiO₂–CuO_x composite layers with different CuO_x contents (1.5, 5.5, and 11 wt.%) were obtained. It is shown that the optical band gap measured by UV–VIS–NIR diffuse reflectance spectra. When CuO_x is added to TiO₂, two absorption edges corresponding to TiO₂ and CuO_x are observed, indicating a broadening of the photosensitivity range of the material relative to pure TiO₂. An open-circuit potential study shows that by changing the amount of CuOx in the composite material, one can control the ratio of free charge carriers (n and p) and, therefore, the catalytic properties of the material. As a result, the TiO₂–CuO_x composite layers have enhanced photocatalytic activity compared to the pure TiO₂ layer: methanol yield grows with increasing CuO_x content during CO₂ photoreduction. Full article

Moving differential and dynamic window moving averaging are simple and well-known signal processing algorithms. However, the most common methods of obtaining sufficient signal-to-noise ratios in distributed acoustic sensing use expensive and precise equipment such as laser sources, photoreceivers, etc., and neural network postprocessing, which results in an unacceptable price of an acoustic monitoring system for potential customers. This paper presents the distributed fiber-optic acoustic sensors data processing and noise suppression techniques applied both to raw data (spatial and temporal amplitude distributions) and to spectra obtained after the Fourier transform. The performance of algorithms’ individual parts in processing distributed acoustic sensor’s data obtained in laboratory conditions for an optical fiber subjected to various dynamic impact events is studied. A comparative analysis of these parts’ efficiency was carried out, and for each type of impact event, the most beneficial combinations were identified. The feasibility of existing noise reduction techniques performance improvement is proposed and tested. Presented algorithms are undemanding for computation resources and provide the signal-to-noise ratio enhancement of up to 13.1 dB. Thus, they can be useful in areas requiring the distributed acoustic monitoring systems’ cost reduction as maintaining acceptable performance while allowing the use of cheaper hardware. Full article

The present study aimed to improve the optical sensing performance of tapered optical fiber sensors toward aqueous Rhodamine B solution of different concentrations by applying single-walled carbon nanotubes (SWCNTs). The functional coating was formed on the surface of the tapered optical fiber sensor using an aerosol layer-by-layer deposition method. Before deposition, the SWCNTs were processed with multistage liquid-phase treatment in order to form a stable dispersion. The effect of SWCNT treatment was investigated through Raman spectroscopy. The deposition of 220 layers caused a reduction of up to 60% of the initial optical power of radiation propagating through the optical fiber core. The optical fiber sensor coated with SWCNTs demonstrated significantly higher sensitivity compared to a non-coated sensor in the range of 2–32 mg/L of Rhodamine B concentration in an aqueous solution. The experimental results demonstrated that the sensitivity was increased 10 times from 32 (mg/L)⁻¹, for the non-coated sensor, up to 317 (mg/L)⁻¹ after SWCNT coating deposition. Moreover, the SWCNT-coated sensor demonstrated high repeatability that allowed for the evaluation of the concentration regardless of the previously analyzed dye concentration. Full article