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.
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.
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.
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).
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 different 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 buffer, 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 affected by depolymerization of the actin and tubulin cytoskeleton.
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.
Cell culture transplantation is very promising in the treatment of various diseases. Cells obtained from a number of sources have been analysed to provide a basis for further studies in the area of regenerative medicine. The objective of the study was to compare morphological and phenotypic changes in cat adipose tissue and bone marrow cell cultures from the first to fifth passages. Adipose tissue and bone marrow were used to obtain cell cultures (coming from 3 cats) using standard methods with own modification. Phenotype changes were monitored by CD-marker identification and CD pan-keratin. The cytogenetic analysis was performed on 50 metaphase plates of cell cultures from the first to fifth passage. Cytogenetic assays showed that the adipose tissue cell culture (ATCC) at all passages was more stable than the bone marrow cell culture (BMCC).
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.
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.
In this work, two thermal- and air-stable, hole transporting materials (HTM) in perovskite solar cells are analyzed. Those obtained and investigated materials were two polyazomethines: the first one with three thiophene rings and 3,3′-dimethoxybenzidine moieties (S9) and the second one with three thiophene rings and fluorene moieties (S7). Furthermore, presented polyazomethines were characterized by Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, atomic force microscopy (AFM) and thermogravimetric analysis (TGA) experiments. Both polyazomethines (S7 and S9) possessed good thermal stability with a 5% weight loss at 406 and 377°C, respectively. The conductivity of S7 was two orders of magnitude higher than for S9 polymer (2.7 × 10−8 S/cm, and 2.6 × 10−10 S/cm, respectively). Moreover, polyazomethine S9 exhibited 31 nm bathochromic shift of the absorption band maximum compared to S7.
Obtained perovskite was investigated by UV–vis and XRD. Electrical parameters of perovskite solar cells (PSC) were investigated at Standard Test Conditions (STC). It was found that both polyazomethines protect perovskite which is confirmed by ageing test where Voc did not decrease significantly for solar cells with HTM in contrast to solar cell without hole conductor, where Voc decrease was substantial. The best photoconversion efficiency (PCE = 6.9%), among two investigated in this work polyazomethines, was obtained for device with the following architectures FTO/TiO2/TiO2 + perovskite/S7/Au. Stability test proved the procreative effects of polyazomethines on perovskite absorber.