The photoacoustic cell is the heart of the nondestructive photoacoustic method. This article presents a new simple lumped-components CRLC model of the Helmholtz type photoacoustic cell. This model has been compared with the well known literature models describing the Helmholtz type cells for photoacoustic spectroscopy. Experimental amplitude and phase frequency data obtained for the two photoacoustic cells have been presented and interpreted in a series of models. Results of the fitting of theoretical curves, obtained in these models, to the experimental data have been shown and discussed.
The application of renewable energy sources poses the problems connected with output volatility. In order to decrease this effect the energy storage technologies can be applied, particularly fuel cells connected with hydrogen storage. In this paper the application of SOFC system for a household in Poland is proposed. Economic and technical analysis is performed. It was found that the proposed installation is profitable after 25 years of operation when compared with conventional solution - heat pumps and gas-fired boilers.
Feeder cells can promote cell proliferation and help overcome the developmental arrest of early embryos by producing growth factors. The objective of this study was to evaluate the effects of feeder cells on the development of all single porcine parthenogenetic embryos in vitro. Firstly, we showed that the cleavage and blastocyst formation rate of all single procine parthenogenetic embryos co-cultured with feeder cells increased in contrast to those cultured without feeder cells (p<0.05). However, no statistically significant differences were observed between the blastocyst formation rate in the embryos co-cultured with 3 different kinds feeder cells namely oviduct epithelial feeder cells, granulose feeder cells and porcine fetal fibroblast feeder cells (p>0.05). Secondly, highly significant differences were observed between the cleavage and blastocyst formation rate (p<0.05) when the embryos were co-cultured with oviduct epithelial feeder cells in different volume drops ranging from 3 to 20 μL and the cleavage rate were the highest when cultured in 5 μL drops. Thirdly, the tempospacial pattern of the development of single embryos co-cultured with oviduct epithelial feeder cells was consistent with that of traditional multi-embryo culture, indicating that the co-culturing does not affect the developmental competence of the porcine parthenogenetic embryos. Finally, highly significant differences were observed between the cleavage and blastocyst formation rate with and without zona pellucida in vitro (p<0.05). In this study, a new adaption of in vitro co-culture of single porcine parthenogenetic embryos using feeder cells has been successfully established and this will facilitate further investigations to discover the mechanistic mode of developmental arrest of porcine embryos.
Thin film solar cells based on multinary compound Cu(In,Ga)Se2 show record photovoltaic conversion efficiency approaching 20%. Investigation on defect physics in this compound is crucial for making further progress in the technology. In this work we present the results on photocapacitance (PC) and deep level optical spectroscopy (DLOS) for two types of cells – high efficiency Cu(In,Ga)Se2 cell with about 20% of gallium and pure gallium CuGaSe2 device. We show that PC and DLOS, employed as the techniques complimentary to deep level transient spectroscopy DLTS and admittance spectroscopy, are useful methods in providing information on defect levels in solar cells. In particular they are helpful in diffierentiating between levels belonging to the bulk of absorber and to the interface states. We tentatively assign some of the observed deep levels to InCu or GaCu antisites and Cu interstitials.
Malakoplakia is regarded as a chronic granulomatous infl ammatory disease with a good prognosis. It usually aff ects the urinary system, especially the urinary bladder. Bacterial infections, including E. coli are thought to be the main factor in pathogenesis. It frequently coexists with chronic diseases and immunosuppression state. Histopathological examination of aff ected tissue samples is thought to be the best diagnostic method. Th e basic microscopic feature is mixed infl ammatory infi ltration containing foamy histiocytes known as von Hansemann cells, frequently with basophilic inclusions known as Michaelis-Gutmann bodies. Symptoms and the clinical course of malakoplakia depend on location and the extent of the lesions. Th e lesion is treated successfully with antibiotic therapy and surgical excision.
Telocyte (TC) is an interstitial cell type with a small cellular body and extremely long tentacle-like extensions. TCs were discovered a decade ago and have specific morphological characteristics, immunohistochemical and secretome profi les, electrophysiological properties, microRNA expression. Moreover, they are different in gene expression from other cells. TCs play an important role in plenty of processes. Apparently, they are involved in homeostasis, remodelling, regeneration, repair, embryogenesis, angiogenesis and even tumorigenesis. “Telocytes need the world”, was emphasized by Professor Popescu and it will be actual at any time. This review summarizes particular features of TCs in different organs and systems, emphasizing their involvement in physiological and pathophysiological processes.
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.
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.
The paper describes factors influencing the development of electricity storage technologies.
The results of the energy analysis of the electric energy storage system in the form of hydrogen are
presented. The analyzed system consists of an electrolyzer, a hydrogen container, a compressor, and
a PEMFC fuel cell with an ion-exchange polymer membrane. The power curves of an electrolyzer
and a fuel cell were determined. The analysis took the own needs of the system into account, i.e. the
power needed to compress the produced hydrogen and the power of the air compressor supplying
air to the cathode channels of the fuel cell stack. The characteristics describing the dependence
of the efficiency of the energy storage system in the form of hydrogen as a function of load were
determined. The costs of electricity storage as a function of storage capacity were determined. The
energy aspects of energy accumulation in lithium-ion cells were briefly characterized and described.
The efficiency of the charge/discharge cycle of lithium-ion batteries has been determined. The
graph of discharge of the lithium-ion battery depending on the current value was presented. The key
parameters of battery operation, i.e. the Depth of Discharge (DoD) and the State of Charge (SoC),
were determined. Based on the average market prices of the available lithium-ion batteries for the
storage of energy from photovoltaic cells, unit costs of electrochemical energy storage as a function
of the DoD parameter were determined.
A microstructural model of Red Blood Cell (RBC) behaviour was proposed. The erythrocyte is treated as a viscoelastic object, which is denoted by a network of virtual particles connected by elastic springs and dampers (Kelvin-Voigt model). The RBC is submerged in plasma modelled by lattice Boltzmann fluid. Fluid – structure interactions are taken into account. The simulations of RBC behaviour during flow in a microchannel and wall impact were performed. The results of RBC deformation during the flow are in good agreement with experimental data. The calculations of erythrocyte disaggregation from the capillary surface show the impact of RBC structure stiffness on the process.
The aim of the presented research was to test different carbon supports, such as graphene oxide (GO), graphene oxide modified with ammonia (N-GO), and reduced graphene oxide (rGO) for catalysts used in a low-temperature fuel cell, specifically a proton exchange membrane fuel cell (PEMFC). Modification of the carbon supports should lead to different catalytic activity in the fuel cell. Reduction of GO leads to partial removal of oxygen groups from GO, forming rGO. Modification of GO with ammonia results in an enrichment of GO structure with nitrogen. A thorough analysis of the used supports was carried out, using various analytical techniques, such as FTIR spectroscopy and thermogravimetric (TGA) analysis. Palladium and platinum catalysts deposited on these supports were produced and used for the oxygen reduction reaction (ORR). Catalytic activity tests of the prepared catalysts were carried out in a home-made direct formic acid fuel cell (DFAFC). The tests showed that the enrichment of the GO structure with nitrogen caused an increase in the catalytic activity, especially for the palladium catalyst. However, reduction of GO resulted in catalysts with higher activity and the highest catalytic activity was demonstrated by Pt/rGO, because platinum is the most catalytically active metal for ORR. The obtained results may be significant for low-temperature fuel cell technology, because they show that a simple modification of a carbon support may lead to a significant increase of the catalyst activity. This could be useful especially in lowering the cost of fuel cells, which is an important factor, because thousands of fuel cells running on hydrogen are already in use in commercial vehicles, forklifts, and backup power units worldwide. Another method used for lowering the price of current fuel cells can involve developing new clean and cheap production methods of the fuel, i.e. hydrogen. One of them employs catalytic processes, where carbon materials can be also used as a support and it is necessary to know how they can influence catalytic activity.
The present study deals with modelling and validation of a planar Solid Oxide Fuel Cell (SOFC) design fuelled by gas mixture of partially pre-reformed methane. A 3D model was developed using the ANSYS Fluent Computational Fluid Dynamics (CFD) tool that was supported by an additional Fuel Cell Tools module. The governing equations for momentum, heat, gas species, ion and electron transport were implemented and coupled to kinetics describing the electrochemical and reforming reactions. In the model, the Water Gas Shift reaction in a porous anode layer was included. Electrochemical oxidation of hydrogen and carbon monoxide fuels were both considered. The developed model enabled to predict the distributions of temperature, current density and gas flow in the fuel cell.
By the method of modern physical material science (optic microscopy scanning and transmission electron microscopy) the analysis of structural phase states, the morphology of the second phase inclusions and defect substructure of Al-Si alloy (silumin) of hypoeutectic composition, subjected to electron beam processing was done with the following parameters: energy density 25-35 J/cm2, beam length 150 μs, pulse number – 3, pulse repetition rate – 0.3 Hz, pressure of residual gas (argon) 0.02 Pa. The surface irradiation results in the melting of the surface layer, the dissolution of boundary inclusions, the stricture formation of high speed cellular crystallization of submicron sizes, the repeated precipitation of the second phase nanodimentional particles. With the increased distance from the irradiation surface the layer containing the second phase inclusions of quasi-equilibrium shape along with the crystallization cells was revealed. It is indicative of the processes of Al-Si alloy structure globalization on electron beam processing.