Charakterystyka nanorurek węglowych modyfikowanych kobaltem, miedzią i bromem

The paper presents results of studies on carbon nanotubes – as received, after cleaning and also after modification. Functional groups as well as metal nanoparticles have been attached, originating from cobalt sulphate, copper acetate and a mixture of hydrogen bromide and bromide. The surface studies on an atomic forces microscope (AFM), X-ray studies (phase composition analysis, crystallite sizes determination) as well as Raman spectroscopy studies were carried out on such nanotubes. The surface topography studies have shown that after the modification the diameter and length of nanotubes change. Also the surface development changes, which has been determined through roughness parameter measurements. The change of intensity, of crystallite size and of half-value width of main reflections originating from carbon for nanotubes modified in various ways have been determined using the X-ray analysis

Proteomic Modeling for HIV-1 Infected Microglia-Astrocyte Crosstalk

Background: HIV-1-infected and immune competent brain mononuclear phagocytes (MP; macrophages and microglia) secrete cellular and viral toxins that affect neuronal damage during advanced disease. In contrast, astrocytes can affect disease by modulating the nervous system’s microenvironment. Interestingly, little is known how astrocytes communicate with MP to influence disease. Methods and Findings: MP-astrocyte crosstalk was investigated by a proteomic platform analysis using vesicular stomatitis virus pseudotyped HIV infected murine microglia. The microglial-astrocyte dialogue was significant and affected microglial cytoskeleton by modulation of cell death and migratory pathways. These were mediated, in part, through F-actin polymerization and filament formation. Astrocyte secretions attenuated HIV-1 infected microglia neurotoxicity and viral growth linked to the regulation of reactive oxygen species. Conclusions: These observations provide unique insights into glial crosstalk during disease by supporting astrocytemediated regulation of microglial function and its influence on the onset and progression of neuroAIDS. The results open new insights into previously undisclosed pathogenic mechanisms and open the potential for biomarker discovery an

Specific Bending and Compressive Strenght of Poly(Vinyl Alcohol)-CNT Composites

Carbon nanotubes are one of the strongest materials of unique mechanical, optical, electrical and electronic properties. Because of that they are mainly used as semiconductor materials constituting the reinforcing phase in composite materials. The paper presents properties of polymer composites reinforced with carbon nanotubes (CNT) containing various mixtures of dispersion. Produced composites featured various content carbon nanotubes: 20%, 30%, 40% i 50%. Macroscopic observations were carried out on ready to check composites, if pores exist in the structure and whether the reinforcement has been distributed in the entire volume. Bending and compressive strengths tests were performed and densities of individual composites were measured to determine the specific strength. Composite materials strengthened with carbon nanotubes feature a very low density and a very good mechanical strength, which makes them a good structural material

Analiza zmian wielkości krystalitów i odkształceń sieciowych w warstwie tlenków na stali P91

The paper contains results of studies on X-ray diffraction analysis XRD (studying the phase composition, crystallite sizes and lattice deformations) of oxide layers on P91 steel, operated for a long time at an elevated temperature (T = 535°C, t = 70,000 h). X-ray studies were carried out on the inner surface of a tube, and then the layer surface was polished down to 3.5 um and the diffraction measurements were performed again to determine individual oxide layers. It has been found that a three-zone oxide layer is formed as a result of long-term operation of P91 steel at the temperature of 535°C. Hematite occurs on the inner surface of the tube. Then magnetite appears below hematite. Going deeper into the layer there is a spinel, i.e. a mixture of magnetite and chromite. A visible decay of total intensity for Fe2O3 is observed already at the polishing depth of 3.5 um. In the case of Fe3O4 and FeCr2O4 an increase in total intensity is observed already from 7 um, what manifests in narrowing the diffraction line and hence in increasing the crystallites size and in the relaxation of stresses in this oxide layer. The broadening of a diffraction line caused by a small size of crystallites is expressed by the Scherrer relationship. Instead, the beta2 broadening resulting from lattice distortions (relaxation of stresses) was determined from the Taylor relationship.Praca zawiera wyniki badań dotyczących rentgenowskiej analizy dyfrakcyjnej XRD (badanie składu fazowego, wielkości krystalitów i odkształceń sieciowych) warstw tlenkowych na stali P91 długotrwale eksploatowanej w podwyższonej temperaturze (T=535 C, t=70000h). Badania rentgenograficzne przeprowadzono na powierzchni wewnętrznej rury, następnie powierzchnie warstwy spolerowywano na głebokość 3,5 um i ponownie wykonywano pomiary dyfrakcyjne w celu określenia poszczególnych warstw tlenkowych. Stwierdzono, ze w wyniku długotrwałej eksploatacji stali P91 w temperaturze 535 C powstaje trójstrefowa warstwa tlenków. Na powierzchni wewnętrznej rury występuje hematyt. Następnie poniżej hematytu pojawia sie magnetyt. Idąc dalej w głąb warstwy występuje spinel, tj. mieszanina magnetytu i chromitu. Widoczny zanik intensywności całkowitej dla Fe2O3 obserwuje się już na głębokości polerowania 3,5 um. W przypadku Fe3O4 i FeCr2O4 od 7 _m obserwuje się już wzrost intensywności całkowitej, co przejawia się zwężeniem linii dyfrakcyjnej, a tym samym zwiększeniem wielkości krystalitów i relaksacja naprężeń w tej warstwie tlenków. Poszerzenie linii dyfrakcyjnej spowodowane mała wielkością krystalitów wyraża się zależnością Scherrera. Natomiast zwężenie wynikające ze zniekształceń sieciowych (relaksacji naprężeń) wyznaczono z zależności Taylora

Specific Bending and Compressive Strenght of Poly(Vinyl Alcohol)-CNT Composites

Carbon nanotubes are one of the strongest materials of unique mechanical, optical, electrical and electronic properties. Because of that they are mainly used as semiconductor materials constituting the reinforcing phase in composite materials

The dependence of magnetic properties on crystallographic structure of electrochemically deposited Ni/Cu superlattices

Ni/Cu superlattices have been grown by electrodeposition from a single sulfamate bath (based on Ni(SO₃NH₂)₂ and CuSO₄) by using the potentiostatic method. Chemical composition of single layers was investigated with SIMS. The Cu layers were almost pure (99.85% Cu) while Ni layers contained 2 ÷ 5% Cu. The lambda period (L) and crystallographic structure of the superlattices were established by X-ray investigations. Good quality of the Ni-Cu interface was indicated, by the presence of second-order satellite peaks around the main multilayer peak. The changes of crystallographic orientation as a function of the total thickness of the deposit demonstrate also the influence of the preferential crystallographic orientation of the multilayers on the size and nature of the magnetoresistance effect. The giant magnetoresistance effect (GMR) was dominant in samples with strong (111) texture and the anisotropy magnetoresistance (AMR) effect was observed in sampIes without any preferential crystallographic orientation

Analiza korozyjna materiałów spiekanych przeznaczonych do niskotemperaturowych ogniw paliwowych

A significant part of proton exchange membrane fuel cells (PEMFC) stack is the bipolar plates (BPs), which account for about 80% of total weight and 45% of stack cost. They are designed to accomplish many functions, e.g. they distribute reactants uniformly over the active areas, remove heat from active areas, carry current from cell to cell and prevent leakage of reactants and coolant. Furthermore, the plates must be of inexpensive, lightweight materials and must be easily manufactured. Materials designed for interconnectors must, among other things, be characterized by resistance to corrosion in the environment with pH= 2-3. This study presents opportunities of use of sintered stainless steel for this part of fuel cells. Resistance to corrosion of sintered materials was compared to properties of material (with the same ferritic phase composition) manufactured in conventional way (plastic forming), i.e. X20Cr13 stainless steel.Ważnym elementem budowy ogniw paliwowych z membraną jonowymienną są okładki/interkonektory. Okładki ogniw paliwowych stanowią około 80% masy całkowitej oraz 45% ceny ogniwa. Okładki do ogniw paliwowych muszą być zaprojektowane tak, aby spełniały wiele funkcji, takich jak jednorodna dystrybucja reagentów w obszarach aktywnych, przewodzenie prądu pomiędzy ogniwami i zabezpieczenie przed wyciekiem reagentów i medium chłodzącego. Poza tym okładki muszą być wykonane z tanich, łatwych w produkcji materiałów o małej masie. Materiały przeznaczone na interkonektory muszą między innymi charakteryzować się odpornością na korozję w środowiskach o pH= 2-3. W pracy przedstawiono możliwości zastosowania spiekanej stali nierdzewnej na ten element ogniwa paliwowego. Odporność na korozję materiału spiekanego porównano z własnościami materiału (posiadającego jednakową strukturę fazową, tj. ferrytyczną) wytwarzanego w sposób tradycyjny (tj. po obróbce plastycznej) - stali nierdzewnej X20Cr13

The Effect of Water Acrylate Dispersion on the Properties of Polymer-Carbon Nanotube Composites / Wpływ Wodnej Dyspersji Akrylanowej Na Właściwości Kompozytów Polimer-Nanorurki Węglowe

The paper presents properties of polymer composites reinforced with carbon nanotubes (CNT) containing various mixtures of dispersion. Acrylates of different particle size and viscosity were used to produce composites. The mechanical strength of composites was determined by three-point bending tests. The roughness parameter of composites was determined with a profilometer and compared with the roughness parameter determined via atomic force microscopy (AFM). Also X-ray studies (phase composition analysis, crystallite sizes determination) were carried out on these composites. Measurements of the surface topography using the Tapping Mode method were performed, acquiring the data on the height and on the phase imaging. The change of intensity, crystallite size and half-value width of main reflections originating from carbon within the composites have been determined using the X-ray analysis. The density of each obtained composite was determined as well as the resistivity at room temperature. The density of composites is quite satisfactory and ranges from 0.27 to 0.35 g/cm3. Different composites vary not only in strength but also in density. Different properties were achieved by the use of various dispersions. Carbon nanotubes constituting the reinforcement for a polymer composite improve the mechanical properties and conductivity composite

Aerology unconventional plasma nitriding of austenitic steels (304 and 316L)

W pracy dokonano oceny wpływu azotowania jarzeniowego na własności warstwy wierzchniej stali austenitycznej gatunku 304 i 316L. Proces azotowania jarzeniowego przeprowadzono w urządzeniu do azotowania typu JON-600. Azotowanie przeprowadzono w temperaturze 733 K (460 stopni Celsjusza), przy ciśnieniu p=150 Pa i w czasie t=64,8 ks (18 h). Do realizacji procesu azotowania zastosowano atmosferę reaktywną składającą się z mieszaniny 25% azotu, 75% wodoru (natężenie przepływu 250ml/min N2+750ml/minH2).The influence of plasma nitriding on properties of surface layer of 304 and 316L austenitic steels was evaluated in this paper. The process of plasma nitriding was carried out in a JON-600 nitriding installation. The nitriding was performed at 733 K (460 degrees of Celsius) at pressure p=150 Pa and during 64.8 ks of 25% of nitrogen and 75% of hydrogen (rate of flow 250ml/min N2+750ml/min H2) was used to carry out the nitriding