Study of Nano h-BN Impact on Lubricating Properties of Selected Oil Mixtures.

Our experiments aimed to study the influence of layered materials with nanometric-scale particles, which are part of lubricant oils, on their tribological properties. The object of this study was a lubricant oil made using base oil PAO4, which contained nanoparticle hexagonal boron nitride (nano h-BN) and a dispersant based on succinic acid imide. Comparative tests for engine oil (CB30) were also performed. The paper presents the method of preparing the test material and the tribological test results, including wear spot diameter (wear mark), limit wear load, and seizure load. The test results obtained demonstrate that nano-hexagonal boron nitride improves the tribological properties of lubricant oils. However, oil preparation and the quantitative selection of components markedly influence the results.

Research on the Influence of the Manufacturing Process Conditions of Iron Sintered with the Addition of Layered Lubricating Materials on its Selected Properties.

The purpose of the conducted experiments was to test the selected properties of materials intended for porous sintered bearings containing layered materials in the form of powders with an average particle size of 0.5-1.5 µm, with very good tribological properties. The subject of the research was a sinter based on iron powder with the addition of layered materials; molybdenum disulfide MoS2 (average particle size 1.5 µm), tungsten disulfide WS2 (average particle size 0.6 µm), hexagonal boron nitride, h-BN (average particle size 0.5 and 1.5 µm) with two different porosities. The article presents the results of density and porosity tests, compressive strength, metallographic and tribological tests and the assessment of changes in the surface condition occurring during the long storage period. The use of layered additives allows for an approximately 20% lower coefficient of friction. In the case of sulfides, the technological process of pressing 250 MPa, 350 MPa, and sintering at a temperature of 1120 °C allows us to obtain a material with good strength and tribological properties, better than in the case of h-BN. However, the main problem is the appearance of elements from the decomposition of sulfide compounds in the material matrix, which results in rapid material degradation. In hexagonal boron nitride, such disintegration under these conditions does not occur; the material as observed does not degrade. In this case, the material is characterized by lower hardness, resulting from a different behavior of hexagonal boron nitride in the pressing and sintering process; in this case, pressing at a pressure of 350 MPa seems to be too low. However, taking into account that even with these technological parameters, the obtained material containing 2.5% h-BN with an average grain size of 1.5 µm allowed obtaining a coefficient of friction at the level of 0.41, which, with very good material durability, seems to be very positive news before further tests.

Influence of Manufacturing Technology on the Structure of 80W-20Re Heavy Sinters.

Preliminary measurement results of 80W-20Re heavy sinters are presented in this paper. Tested samples were taken from three different technology processes, i.e., resistance sintering (RS), pulse plasma sintering (PPS), and conventional sintering in a vacuum furnace. In the first two cases, the obtained sinters were of similar usable properties (porosity and microhardness), while for vacuum sintering, the material with high porosity was obtained. At the same time, it was found that sintering with the use of electric current (RS, PPS) generates microstructures with highly elongated grains.

The Amphoteric and Hydrophilic Properties of Cartilage Surface in Mammalian Joints: Interfacial Tension and Molecular Dynamics Simulation Studies.

In this paper, we explain the amphoteric character of the cartilage surface by studying a lipid bilayer model built from phospholipids. We examined the interfacial tension values and molecular dynamics simulation in solutions of varying pH. The effects of negative and positive charge density (or fixed charges) on the (cartilage/cartilage) friction coefficient were investigated. In physiological (or synovial) fluid, after the isoelectric point (pI), the curve of interfacial tension decreases rapidly as it reaches pH 7.4 and then approaches a constant value at higher pH. It was shown that the curve of the interfacial tension curve exhibits a maximum value at the isoelectric point with a Gaussian shape feature. The phospholipid bilayers facilitate an almost frictionless contact in the joint. Moreover, the slippage of the bilayer and the short-range repulsion between the surfaces of the negatively charged cartilage surfaces are the main determinants of the low frictional properties of the joint.

Production of High-Purity Anhydrous Nickel(II) Perrhenate for Tungsten-Based Sintered Heavy Alloys.

This paper presents a method for the production of high-purity anhydrous nickel(II) perrhenate. The method comprises sorption of nickel(II) ions from aqueous nickel(II) nitrate solutions, using strongly acidic C160 cation exchange resin, and subsequent elution of sorbed nickel(II) ions using concentrated perrhenic acid solutions. After the neutralization of the resulting rhenium-nickel solutions, hydrated nickel(II) perrhenate is then separated and then dried at 160 °C to obtain the anhydrous form. The resulting compound is reduced in an atmosphere of dissociated ammonia in order to produce a Re-Ni alloy powder. This study provides information on the selected properties of the resulting Re-Ni powder. This powder was used as a starting material for the production of 77W-20Re-3Ni heavy alloys. Microstructure examination results and selected properties of the produced sintered heavy alloys were compared to sintered alloys produced using elemental W, Re, and Ni powders. This study showed that the application of anhydrous nickel(II) perrhenate in the production of 77W-20Re-3Ni results in better properties of the sintered alloys compared to those made from elemental powders.

[An attempt to identify to cryptogamic plants in Syreniusz's herbal]. / Próba identyfikacji roslin zarodnikowych (z wyjatkiem paprotników) wymienionych w dziele Syreniusza zielnik (1613).

The current paper constitutes an attempt to identify the algae, fungi, lichens and liverworts mentioned in the extensive Herbal by Syreniusz, published in Cracow in 1613. All four algae mentioned are maritime species. As for fungi, Syreniusz described the fungus Fomitopsis officinalis, which was then used in medicine, and he listed several Polish names of edible and poisonous macromycetes, and also mentioned rust on wheat. The lichen that has been identified is the species Lobaria pulmonaria, and the liverwort is Marchantia polymorpha, both used in medicine.

[Adenocarcinoma of the lung with metastases to the pituitary and both adrenal glands]. / Gruczolakorak pluca z przerzutami do przysadki mózgowej i obu nadnerczy.

A case of lung adenocarcinoma with metastases in both adrenals and pituitary gland in 52-year old patient is presented. Adrenal glands metastases were diagnosed on a base of CT scans. Pituitary metastases caused gradual loss of vision. MR imaging showed a lesion in the sella and suprasellar areas and suggested meningioma. Right frontal craniotomy with the partial removal of the tumor was performed. Three days later the patient died. Histopathological results of the pituitary masses revealed adenocarcinoma.

Selected cytokines and soluble forms of cytokine receptors in coronary artery disease.

Background: Cytokines may play a role in the pathogenesis of atherosclerosis and coronary artery disease (CAD). Methods: We examined serum concentrations of selected pro- (TNFalpha, IL-2) and anti-inflammatory (IL-10) cytokines, and soluble forms of TNF receptors (sTNFR 1 and sTNFR 2) by ELISA in 45 patients with stable exertional angina (group 1), 32 patients with unstable angina (group 2), and 20 healthy subjects (group C). Results: Serum concentrations of both TNFalpha (group 1, 18.3; group 2, 17.2 pg/ml; P<0.001) and IL-10 (group 1, 46.1; group 2, 41.5 pg/ml; P<0.05) were significantly higher in patients with CAD than in group C (8.3 and 14.3 pg/ml, respectively). sTNFR 1 serum level was higher in group 1 (1399.6; P<0.05) than in healthy volunteers (1093.9 pg/ml). In turn, the serum level of IL-2 was significantly higher in unstable patients than it was in groups 1 and C (89.4, 59.8 and 52.8 pg/ml, respectively). In group 1, both TNFalpha and IL-2 correlated with serum lipids. Conclusions: Patients with CAD, irrespective of the form of the disease, have higher serum levels of pro- and anti-inflammatory cytokines than control subjects. Increased concentrations of IL-2 in unstable angina may suggest additional immunologic activation. The pro-inflammatory cytokine levels seem to be related to lipid disturbances.