Some studies show that cells are able to penetrate through pores that are smaller than cell size. It concerns especially Red Blood Cells but it also may concern different types of biological cells. Such penetration of small pores is a very significant problem in the filtration process, for example in micro- or ultrafiltration. Deformability of cells allows them to go through the porous membrane and contaminate permeate. This paper shows how cells can penetrate small cylindrical holes and tries to assess mechanical stress in a cell during this process. A new mathematical approach to this phenomenon was presented, based on assumptions that were made during the microscopic observation of Red Blood Cell aspiration into a small capillary. The computational model concerns Red Blood Cell geometry. The mathematical model allows to obtain geometrical relation as well as mechanical stress relations.
The article is a modified Polish version of my Director’s report published in the “Annual Report 2017–March 2018” of the International Institute of Molecular and Cell Biology in Warsaw (www.iimcb.gov.pl). After 20 years of being in charge of the Institute and a few months before the end of my final term as its director, I summarize our achievements, failures, lost opportunities and recall how it all began. I also give the names of people who formed organizing team of the Institute in the nineties, names of the first International Advisory Board members and names of the Institutes’ directors who will be in charge of it since July 2018.
Dendritic cells (DCs) due to their ability to present antigens are essential during the immune response to infections. The aim of the study was to evaluate the influence of bovine leukaemia virus (BLV) infection on DC properties. Cytokine profiles of myeloid, plasmacytoid and mono- cyte derived DCs from BLV infected cattle were analysed. Concentrations of IL-6, IL-10, IL-12, IFN-γ, and TNF-α in DC cultures were measured by flow cytometry. Obtained results indicated activation of pDCs population, where a significant increase in production of the IFN-γ was shown. Meanwhile, a decrease in production of IFN-γ and increase in production of IL-10 were shown in mDCs; the main population responsible for antigens presentation. This may indicate a contribu- tory role of the population during the process of persistent infection. In MoDCs population a significant elevation in secretion of proinflammatory cytokines – IL-6 and TNF-α was noted.
A year-round (3 March 1994 - 28 February 1995) phytoplankton study in Admiralty Bay revealed nanoplankton flagellates (< 20 μm) to be the major algae of the plankton, both in terms of cell numbers and carbon biomass. Their quantities fluctuated widely thoroughly the year showing several peaks, in May, April, December and January. Summer maximum of the group in December was mainly due to Cryptophyceae (4.9 x 106 cells l-1; 98.0 μg C 1-1) and Prasinophyceae (7.3 x 105 cells -1; 33.5 μg C -1). Diatoms were usually scarce (max. 6.8 x 105 cells -1; 7.82 p:g C 1-1) and were dominated by small species of Thalassiosira and by Nitzschia spp. (Pseudonitzschia); the domination structure somewhat differed from that observed in Admiralty Bay in the summer of 1977/78. Algal peaks were related to the surface water (4 m depth) temperature rise from +0.16 to +1.71˚C. Summer phytoplankton maxima were about 5-fold greater than those recorded in the summer of 1977/78.
Due to the unrecognized effect of tigecycline (TIG) on CD4+ and CD8+ T cells, the present study has been undertaken in order to determine whether the drug can affect these cells in respect of their counts, and the production of IFN-γ, IL-17 (pro-inflammatory and immune-protective cytokines), IL-4 (anti-inflammatory and immune-protective cytokine), IL-10 and TGF-β (anti-inflammatory and immune-suppressive cytokines). Murine lymphocytes were treated with TIG for 48 and 96 h at concentrations reflecting its plasma levels obtained in vivo at therapeutic doses, and at 10-fold lower concentrations. It was found that TIG neither affected substantially the percentage and absolute counts of entire CD4+ and CD8+ T cell populations nor influenced the Foxp3+CD25+CD4+ regulatory/suppressive T cell subset. Furthermore, the percentages of IL-4-, IL-10-, IL-17- and TGF-β-producing CD4+ T cells were not altered following the exposure to TIG. Similarly, TIG did not influence IFN-γ production by CD8+ T cells. Thus, with respect to the parameters evaluated, TIG does not seem to exert immune-suppressive and anti-inflammatory effects.
This paper presents an analysis of use of ultrasonic standing wave in cell separation from bodily fluids based on the example of erythrocyte separation from plasma. It describes movement of red blood cells in plasma under the influence of the acoustic field (whose forces result from interaction of red blood cells with plasma as the vibrating medium) and under the influence of resistance forces in Stokes’ and Oseen’s approximation. The general properties of solutions of the motion equation are given. The solutions for the parameters of the ultrasonic wave and blood cells which are interesting in terms of practical applications in medical diagnostics are discussed. Time constants of the cell transportation to the regions of stable equilibrium in the field of ultrasonic standing wave are estimated. The formulas which determine the time needed to obtain the assumed concentration increase in plasma in nodes and/or anti-nodes of the standing wave are derived.
Typically applied static (i.e. non-agitated) cultures do not provide sufficient conditions for efficient propagation of suspended non-adherent cells, in general. Feasibility of small-scale wave-type agitated single-use bioreactors for gentle agitation underlies applicability of such systems for scaling-up of fragile biomass of animal cells. The basic aim of the study was to compare the results of non-adherent HL-60 cell propagation performed referentially as the batch culture in typical static (i.e. non-agitated) disposable culture flasks (50 cm3 of culture medium) and in ReadyToProcess WAVETM25 bioreactor system (GE Healthcare) equipped with disposable culture bag (300 cm3 of culture medium) subjected to continuous wave-type agitation. The density and viability of HL-60 cells were significantly higher for the bioprocess subjected to wave-type agitation, than in the reference static culture. The values of the specific rate of glucose consumption per cell (rglc=cell) exhibited by HL-60 cells maintained in the system with continuous wave-type agitation was significantly lower (i.e. up to more than 42%) than the values noted for the static culture, for exactly the same time-points of two compared cultures. The results of the studies undoubtedly and comprehensively confirmed the applicability of the studied disposable bioreactor with wave-induced agitation as the right platform for proceeding the propagation of non- adherent HL-60 cells and for providing the culture conditions required by HL-60 cells for sustainable metabolism.
This article presents a critical mini-review of research conducted on bioelectrochemical reactors with emphasis placed on microbial fuel cells (MFC) and microbial electrolysis cells (MEC). The principle of operation and typical constructions of MFCs and MECs were presented. The types of anodes and cathodes, ion-selective membranes and microorganisms used were discussed along with their limitations.
This study aimed to determine the levels of milk cell total protein (TP), reduced nicotinamide adenine dinucleotide phosphate (NADPH), total glutathione (tGSH), activities of glucose-6-phos- phate dehydrogenase (G6PD) and glutathione peroxidase (GPx) in subclinical mastitic cows. Milk from each udder was collected and grouped by the California Mastitis Test. Then, a somatic cell count (SCC) was performed, and the groups were re-scored as control (5–87 × 103 cells), 1st group (154–381 × 103 cells), 2nd group (418–851 × 103 cells), 3rd group (914–1958 × 103 cells), and 4th group (2275–8528 × 103 cells). Milk cell TP, NADPH, tGSH levels, G6PD, and GPx ac- tivities were assessed. Microbiological diagnosis and aerobic mesophyle general organism (AMG, cfu/g) were also conducted. In mastitic milk, TP, NADPH, and tGSH levels, and G6PD and GPx activities were significantly reduced per cell (in samples of 106 cells). In addition, milk SCC was positively correlated with AMG (r=0.561, p<0.001), NADPH (r=0.380, p<0.01), TP (r=0.347, p<0.01) and G6PD (r=0.540, p<0.001). There was also positive correlation between NADPH (r=0.428, p<0.01), TP (r=0.638, p<0.001) and AMG. NADPH was positively correlated with TP (r=0.239, p<0.05), GPx (r=0.265, p<0.05) and G6PD (r=0.248, p=0.056). Total protein was positively correlated with tGSH (r=0.354, p<0.01) and G6PD (r=0.643, p<0.001). There was a negative correlation between tGSH and GPx activity (r=-0.306, p<0.05). The microbiological analysis showed the following ratio of pathogens: Coagulase-Negative Staphylococci 66.6%, Streptococcus spp 9.5%, Bacillus spp 9.5%, yeast 4.8%, and mixed infections 9.5%. As a conclusion, when evaluating the enzyme and oxidative stress parameters in milk, it is more suitable to assign values based on cell count rather than ml of milk. The linear correlation between the SCC and AMG, milk cell NADPH, TP and G6PD suggests that these parameters could be used as markers of mastitis.
Insulin receptor substrate 2 (IRS-2) modulates the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, which controls the suppression of gluconeogenic genes; IRS-2 is also a critical node of insulin signaling. Because of the high homology between pig and human IRS-2, we investigated the expression pattern and function of porcine IRS-2. QPCR and immunoblotting were used to detect the IRS-2 expression level in different tissues. There were high IRS-2 levels in the cerebral cortex, hypothalamus, and cerebellum in the central nervous system. In peripheral tissues, IRS-2 was expressed at relatively high levels in the liver. Immunohistochemistry analysis revealed that IRS-2 was mainly distributed in the hypothalamus and cerebral cortex. Furthermore, IRS-2 knockdown porcine hepatocytes and porcine aortic endothelial cells (PAECs) were generated. The IRS-2 knockdown induced abnormal expression of genes involved in glycolipid metabolism in hepatocytes and reduced the antiatherosclerosis ability in PAECs. In addition, we disrupted IRS-2 in porcine embryonic fibroblasts (PEFs) using the CRISPR/Cas9 genome editing system, before finally generating IRS-2 knockout embryos by somatic cell nuclear transfer (SCNT). Taken together, our results indicate that IRS-2 might be a valuable target to establish diabetes and vascular disease models in the pig.
This work presents a theoretical study for the distribution of nanocomposite structure of plasmonic thin-film solar cells through the absorber layers. It can be reduced the material consumption and the cost of solar cell. Adding nanometallic fillers in the absorber layer has been improved optical, electrical characteristics and efficiency of traditional thin film solar cells (ITO /CdS/PbS/Al and SnO2/CdS/CdTe/Cu) models that using sub micro absorber layer. Also, this paper explains analysis of J-V, P-V and external quantum efficiency characteristics for nanocomposites thin film solar cell performance. Also, this paper presents the effect of increasing the concentration of nanofillers on the absorption, energy band gap and electron-hole generation rate of absorber layers and the effect of volume fraction on the energy conversion efficiency, fill factor, space charge region of the nanocomposites solar cells.
In this work, a mid infrared thermography was used to study thermal behavior of solid oxide fuel cell (SOFC) with a circular shape and a diameter of 90 mm. The emissivity of the anodic surface of the fuel cell was determined to be from 0.95 to 0.46 in the temperature range 550-1200 K and the profile and temperature distribution of the anodic surface of the unloaded cell was given. The surface temperature of the cell was determined during operation and the polarity changes from open circuit voltage (OCV) to 0.0 V. It was found that the cell self-heating effect decreases with increasing temperature of the cell.
Photovoltaic cells have been used for a long time to supply the electrical devices of small power in areas without access to the electricity networks (or other sources of electric energy). The ecological aspect of the use of the renewable energy sources, together with the technology development and increasingly lower costs of production the photovoltaic cells, cause the increase of their application. The solar power plants are built in several places in the world, not necessarily in the areas of high light intensity. Nowadays, such developments mostly depend on the wealth of a particular country. The largest photovoltaic power stations have power of a several dozen of MW. The major disadvantage of the photovoltaic cells is that the energy production is possible only during the day. This causes a necessity of energy accumulation in large photovoltaic systems. One possibility of storing large amounts of energy gives a hydrogen fuel, generated in the electrolysers powered directly from photovoltaic cells. Hydrogen, stored in pressure tanks or in tanks with synthetic porous materials, can be again used to produce electricity in fuel cells. This paper introduces selected issues and test results associated with the use of photovoltaic cells to power the hydrogen generators. The possible connections of photovoltaic modules integrated with electrolysers were analyzed. In this article the results of the electricity daily production by polycrystalline photovoltaic cells, collected in the course of the entire year were also presented.
Taking bacterial virulence factors as targets is a new therapy for treating host bacterial infection. The aim of this study was to investigate the effect of matrine on α-hemolysin production of Staphylococcus aureus (S. aureus) and reducing the damage to bovine mammary epithelial cells (BMECs) induced by S. aureus α-hemolysin. Subinhibitory concentrations of matrine decreased the production of α-hemolysin in none dose-dependent manner and matrine exhibited a protective effect on S. aureus-induced BMECs injury. The results indicated that the structure of matrine may potentially be used as a basic structure for development of drugs aimed at curing and preventing dairy bovine mastitis.
The article presents a zero-dimensional mathematical model of a tubular fuel cell and its verification on four experiments. Despite the fact that fuel cells are still rarely used in commercial applications, their use has become increasingly more common. Computational Flow Mechanics codes allow to predict basic parameters of a cell such as current, voltage, combustion composition, exhaust temperature, etc. Precise models are particularly important for a complex energy system, where fuel cells cooperate with gas, gas-steam cycles or ORCs and their thermodynamic parameters affect those systems. The proposed model employs extended Nernst equation to determine the fuel cell voltage and steadystate shifting reaction equilibrium to calculate the exhaust composition. Additionally, the reaction of methane reforming and the electrochemical reaction of hydrogen and oxygen have been implemented into the model. The numerical simulation results were compared with available experiment results and the differences, with the exception of the Tomlin experiment, are below 5%. It has been proven that the increase in current density lowers the electrical efficiency of SOFCs, hence fuel cells typically work at low current density, with a corresponding efficiency of 45–50% and with a low emission level (zero emissions in case of hydrogen combustion).
The paper describes a fuel cell based system and its performance. The system is based on two fuel cell units, DC/DC converter, DC/AC inverter, microprocessor control unit, load unit, bottled hydrogen supply system and a set of measurement instruments. In the study presented in the paper a dynamic response of the proton exchange membrane (PEM) fuel cell system to unit step change load as well as to periodical load changing cycles in the form of semi-sinusoidal and trapezoidal signals was investigated. The load was provided with the aid of an in-house-developed electronic load unit, which was fully PC controlled. The apparatus was commissioned by testing the steady-state operation of the module. The obtained efficiency of the fuel cell shows that the test apparatus used in the study provides data in substantial agreement with the manufacturer’s data.
The application of modern scientific methods and measuring techniques can extend the empirical knowledge used for centuries by violinmakers for making and adjusting the sound of violins, violas, and cellos. Accessories such as strings and tailpieces have been studied recently with respect to style and historical coherence, after having been somehow neglected by researchers in the past. These fittings have played an important part in the history of these instruments, but have largely disappeared as they have been modernised. However, the mechanics of these accessories contribute significantly to sound production in ways that have changed over time with different musical aesthetics and in different technical contexts. There is a need to further elucidate the function and musical contribution of strings and tailpieces. With this research we are trying to understand the modifications of the cello's sound as a consequence of tailpiece characteristics (shape of the tailpiece and types of attachments). Modal analysis was used to first investigate the vibration modes of the tailpiece when mounted on a non-reactive rig and then when mounted on a real cello where it can interact with the modes of the instrument's corpus. A preliminary study of the effect of the tailpiece cord length will be presented.
The direct carbon fuel cell technology provides excellent conditions for conversion of chemical energy of carbon-containing solid fuels directly into electricity. The technology is very promising since it is relatively simple compared to other fuel cell technologies and accepts all carbon-reach substances as possible fuels. Furthermore, it makes possible to use atmospheric oxygen as the oxidizer. In this paper the results of authors' recent investigations focused on analysis of the performance of a direct carbon fuel cell supplied with graphite, granulated carbonized biomass (biocarbon), and granulated hard coal are presented. The comparison of the voltage-current characteristics indicated that the results obtained for the case when the cell was operated with carbonized biomass and hard coal were much more promising than those obtained for graphite. The effects of fuel type and the surface area of the cathode on operation performance of the fuel cell were also discussed.
Hybryd PLD method was used for deposition high quality thin Ti, TiN, Ti(C,N) and DLC coatings. The kinetic energy of the evaporated particles was controlled by application of variation of di#11;erent reactive and non reactive atmospheres during deposition. The purpose was to improve adhesion by building a bridge between the real ceramic coating and the substrate. A new layer composition layout was proposed by application of a bu#11;er, starting layer. Advanced HRTEM investigation based on high resolution transmission electron microscopy was used to reveal structure dependence on specific atmosphere in the reactive chamber. New experimental technique to examine the crystallographic orientation based on X-ray texture tomography was applied to estimate contribution of the atmosphere to crystal orientation. Using Dictyostelium discoideum cells as a model organism for specific and nonspecific adhesion, kinetics of shear flow-induced cell detachment was studied. For a given cell, detachment occurs for critical stress values caused by the applied hydrodynamic pressure above a threshold. Cells are then removed from the substrate with an apparent first-order rate reaction that strongly depends on the stress. The threshold stress depends on cell size and physicochemical properties of the substrate, but it is not a#11;ected by depolymerization of the actin and tubulin cytoskeleton.
Metallic foams are materials of which the research is still on-going, with the broad applicability in many different areas (e.g. automotive industry, building industry, medicine, etc.). These metallic materials have specific properties, such as large rigidity at low density, high thermal conductivity, capability to absorb energy, etc. The work is focused on the preparation of these materials using conventional casting technology (infiltration method), which ensures rapid and economically feasible method for production of shaped components. In the experimental part we studied conditions of casting of metallic foams with open pores and irregular cell structure made of ferrous and nonferrous alloys by use of various types of filler material (precursors).
Industrial engineers gather knowledge during their bachelor studies through lectures and practical classes. The goal of practical class might be an extension of knowledge and/or a consolidation and application of already gathered knowledge. It is observed that there exists a gap between theory learnt during lectures and practical classes. If practical classes require holistic approach and solving complex tasks (problems), students strive with understanding relations and connections between parts of knowledge. The aim of this article is to show an example of a simple practical assignment that can serve as a bridge between lectures and practical classes through discussion of interactions and relations between parts of theoretical knowledge. It is an example of in-class simulating of a line and cellular layout considering discussion of elements impacting and impacted by the type of layout (e.g. learning curve, changeovers, etc.). In-class verification of the presented approach confirmed its usability for teaching industrial engineers and bridging the gap between theory delivered through lectures and more advanced practical classes.
Cardiac Radiofrequency (RF) ablation is a commonly used clinical procedure for treating many cardiac arrhythmias. However, the efficacy of RF ablation may be limited by two factors: small ventricular lesions and impedance rise, leading to coagulum formation and desiccation of tissue. In this paper, a high frequency (HF) energy ablation system operating at 27.12 MHz based on an automated load matching system was developed. A HF energy matched probe associated to the automated impedance matching device ensures optimal transfer of the energy to the load. The aim of this study was to evaluate this energy for catheter ablation of the atrioventricular junction. In vivo studies were performed using 10 sheep to characterize the lesions created with the impedance matching system. No cardiac perforation was noted. No thrombus was observed at the catheter tip. Acute lesions ranged from 3 to 45 mm in diameter (mean ±SD = 10.3±10) and from 1 to 15 mm in depth (6.7±3.9), exhibiting a close relationship between HF delivered power level and lesion size. Catheter ablation using HF current is feasible and appears effective in producing a stable AV block when applied at the AV junction and large myocardial lesions at ventricular sites.
Based on mathematical modeling and numerical simulations, applicativity of various biofuels on high temperature fuel cell performance are presented. Governing equations of high temperature fuel cell modeling are given. Adequate simulators of both solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) have been done and described. Performance of these fuel cells with different biofuels is shown. Some characteristics are given and described. Advantages and disadvantages of various biofuels from the system performance point of view are pointed out. An analysis of various biofuels as potential fuels for SOFC and MCFC is presented. The results are compared with both methane and hydrogen as the reference fuels. The biofuels are characterized by both lower efficiency and lower fuel utilization factors compared with methane. The presented results are based on a 0D mathematical model in the design point calculation. The governing equations of the model are also presented. Technical and financial analysis of high temperature fuel cells (SOFC and MCFC) are shown. High temperature fuel cells can be fed by biofuels like: biogas, bioethanol, and biomethanol. Operational costs and possible incomes of those installation types were estimated and analyzed. A comparison against classic power generation units is shown. A basic indicator net present value (NPV) for projects was estimated and commented.
The subject of the study are alumina foams produced by gelcasting method. The results of micro-computed tomography of the foam samples are used to create the numerical model reconstructing the real structure of the foam skeleton as well as the simplified periodic open-cell structure models. The aim of the paper is to present a new idea of the energy-based assessment of failure strength under uniaxial compression of real alumina foams of various porosity with use of the periodic structure model of the same porosity. Considering two kinds of cellular structures: the periodic one, for instance of fcc type, and the random structure of real alumina foam it is possible to justify the hypothesis, computationally and experimentally, that the same elastic energy density cumulated in the both structures of the same porosity allows to determine the close values of fracture strength under compression. Application of finite element computations for the analysis of deformation and failure processes in real ceramic foams is time consuming. Therefore, the use of simplified periodic cell structure models for the assessment of elastic moduli and failure strength appears very attractive from the point of view of practical applications.