Surface free energy of polyurethane coatings with improved hydrophobicity

The polarity of polyurethane coats was studied on the basis of the goniometric method for determination of wetting angle values, on the basis of calculated surface free energy (SFE) values by the van Oss–Good and Owens–Wendt methods, and on the basis of polarity measurements with the use of the 1H NMR spectra. Test polyurethanes were synthesised in the reaction of methylene diphenyl 4,4′-diisocyanate (MDI) or 3-izocyanatomethyl –3,5,5- trimethylcyclohexyl isocyanate (IPDI) and polyoxyethylene glycols or polyesters poly(ε-caprolactone) diols and poly(ethyleneadipate) diol with different molecular weights, and some diols as chain extenders, in dioxane. The type of raw material was found to significantly affect the phase structure of the obtained polyurethane elastomers and to control physical interactions within those structures, thus influencing the SFE values. Fundamental reduction in the SFE value of a coating below 28 mJ/m2 was achieved by the use of 2,2,3,3-tetrafluoro-1,4-butanediol as the urethane prepolymer chain extender

Exotic Smoothness and Quantum Gravity

Since the first work on exotic smoothness in physics, it was folklore to assume a direct influence of exotic smoothness to quantum gravity. Thus, the negative result of Duston (arXiv:0911.4068) was a surprise. A closer look into the semi-classical approach uncovered the implicit assumption of a close connection between geometry and smoothness structure. But both structures, geometry and smoothness, are independent of each other. In this paper we calculate the "smoothness structure" part of the path integral in quantum gravity assuming that the "sum over geometries" is already given. For that purpose we use the knot surgery of Fintushel and Stern applied to the class E(n) of elliptic surfaces. We mainly focus our attention to the K3 surfaces E(2). Then we assume that every exotic smoothness structure of the K3 surface can be generated by knot or link surgery a la Fintushel and Stern. The results are applied to the calculation of expectation values. Here we discuss the two observables, volume and Wilson loop, for the construction of an exotic 4-manifold using the knot $5_{2}$ and the Whitehead link $Wh$. By using Mostow rigidity, we obtain a topological contribution to the expectation value of the volume. Furthermore we obtain a justification of area quantization.Comment: 16 pages, 1 Figure, 1 Table subm. Class. Quant. Grav

Studies of the magnetic axis switching in magnetite

The influence of the external magnetic field on magnetic and crystallographic structure of magnetite was studied. We have confirmed, by means of vibrating sample magnetometer measurements, that external magnetic field can switch the easy magnetic axis to the new crystallographic direction. We have also proved by the direct observation of the crystalline structure that this phenomenon is strictly related to the crystallographic structure relaxation

Synthesis and characterisation of coating polyurethane cationomers containing fluorine built-in hard urethane segments

Polyurethane cationomers were synthesised in the reaction of 4,4’-methylenebis(phenyl isocyanate) with polyoxyethylene glycol (M = 2,000) or poly(tetrafluoroethyleneoxide-co-difluoromethylene oxide) α,ω-diisocyanate and N-methyl diethanolamine. Amine segments were built-in to the urethane-isocyanate prepolymer in the reaction with 1-bromobutane or formic acid, and then they were converted to alkylammonium cations. The obtained isocyanate prepolymers were then extended in the aqueous medium that yielded stable aqueous dispersions which were applied on the surfaces of test poly(tetrafluoroethylene) plates. After evaporation of water, the dispersions formed thin polymer coatings. 1H, 13C NMR and IR spectral methods were employed to confirm chemical structures of synthesised cationomers. Based on 1H NMR and IR spectra, the factors κ and α were calculated, which represented the polarity level of the obtained cationomers. The DSC, wide angle X-ray scattering and atom force microscopy methods were employed for the microstructural assessment of the obtained materials. Changes were discussed in the surface free energy and its components, as calculated independently according to the method suggested by van Oss–Good, in relation to chemical and physical structures of cationomers as well as morphology of coating surfaces obtained from those cationomers. Fluorine incorporated into cationomers (about 30%) contributed to lower surface free energy values, down to about 15 mJ/m2. That was caused by gradual weakening of long-range interactions within which the highest share is taken by dispersion interactions

Pogorszenie czynności nerek, czyli co należy wiedzieć w wypadku stwierdzenia obniżonego przesączania kłębuszkowego

Wyniki badań epidemiologicznych wskazują na ciągły wzrost liczby osób z przewlekłą chorobą nerek (PChN), w tym także pacjentów z upośledzoną czynnością wydalniczą nerek. Fakt ten po pierwsze stwarza konieczność zwiększonej czujności lekarzy w podejrzewaniu PChN. Po drugie wymaga dokonywania oceny wydalniczej funkcji nerek u chorych należących do grup zwiększonego ryzyka występowania PChN oraz wówczas, gdy pacjent jest narażony na działanie czynników usposabiających bądź mogących inicjować rozwój PChN. Najprostszym, a zarazem w większości sytuacji klinicznych wystarczająco dokładnym sposobem ocenienia czynności wydalniczej nerek jest oszacowanie przesączania kłębuszkowego ze stężenia kreatyniny w surowicy na podstawie jednego z wielu dostępnych wzorów. Oceny funkcji nerek należy dokonywać także u osób w podeszłym wieku, mimo obniżania się jej związanego z samym procesem starzenia, gdyż udowodniono, że obniżona wielkość przesączania kłębuszkowego jest niezależnym czynnikiem ryzyka zgonu. Wśród najczęstszych przyczyn PChN w najbardziej zaawansowanym stadium, oprócz cukrzycy, kłębuszkowych zapaleń nerek, nadciśnienia tętniczego i śródmiąższowych zapaleń nerek, są - ciągle na wysokiej pozycji - przyczyny nieznane. Wskazuje to na niedoskonałości wczesnego rozpoznawania PChN oraz kryje w sobie potencjalnie znaczne efekty możliwych do wprowadzenia działań nefroprotekcyjnych. Interdyscyplinarna opieka nad pacjentem z PChN, w której uczestniczą lekarze różnych specjalności, oraz szeroko zakrojone działania nefroprotekcyjne na wielu płaszczyznach jednocześnie, z edukacją chorych włącznie, stanowią szansę na zahamowanie lub co najmniej spowolnienie progresji PChN

Spin polarization of exciton-polariton condensate in a photonic synthetic effective magnetic field

We investigate the spin polarization of localized exciton-polariton condensates. We demonstrate the presence of an effective magnetic field leading to the formation of elliptically polarized condensates. We show that this synthetic field has an entirely photonic origin, which we believe is unique for the CdTe-based microcavities. Moreover, the degree of spin polarization of localized polariton condensates in samples with magnetic ions depends on the excitation power or polarization of the non-resonant excitation laser. In an external magnetic field, the semimagnetic condensate spontaneously builds up strong spin polarization. Based on the magnetic field behavior of the condensate in the presence of magnetic ions, we apply a model that allows us to estimate the polariton-polariton interaction strength in a CdTe-system to approx. 0.8 $\mu \text{eV}\!\cdot\!\mu \text{m}^2$

Methionine restriction restores a younger metabolic phenotype in adult mice with alterations in fibroblast growth factor 21.

Methionine restriction (MR) decreases body weight and adiposity and improves glucose homeostasis in rodents. Similar to caloric restriction, MR extends lifespan, but is accompanied by increased food intake and energy expenditure. Most studies have examined MR in young animals; therefore, the aim of this study was to investigate the ability of MR to reverse age-induced obesity and insulin resistance in adult animals. Male C57BL/6J mice aged 2 and 12 months old were fed MR (0.172% methionine) or control diet (0.86% methionine) for 8 weeks or 48 h. Food intake and whole-body physiology were assessed and serum/tissues analyzed biochemically. Methionine restriction in 12-month-old mice completely reversed age-induced alterations in body weight, adiposity, physical activity, and glucose tolerance to the levels measured in healthy 2-month-old control-fed mice. This was despite a significant increase in food intake in 12-month-old MR-fed mice. Methionine restriction decreased hepatic lipogenic gene expression and caused a remodeling of lipid metabolism in white adipose tissue, alongside increased insulin-induced phosphorylation of the insulin receptor (IR) and Akt in peripheral tissues. Mice restricted of methionine exhibited increased circulating and hepatic gene expression levels of FGF21, phosphorylation of eIF2a, and expression of ATF4, with a concomitant decrease in IRE1α phosphorylation. Short-term 48-h MR treatment increased hepatic FGF21 expression/secretion and insulin signaling and improved whole-body glucose homeostasis without affecting body weight. Our findings suggest that MR feeding can reverse the negative effects of aging on body mass, adiposity, and insulin resistance through an FGF21 mechanism. These findings implicate MR dietary intervention as a viable therapy for age-induced metabolic syndrome in adult humans

Density of Gr1-positive myeloid precursor cells, p-STAT3 expression and gene expression pattern in canine mammary cancer metastasis

The very recent studies on human and mice models have indicated an important role of myeloid precursor cells (progenitors or not fully differentiated cells that express the Gr1 antigen also called Gr1-positive myeloid suppressor cells) in the tumor progression and metastasis. They are thought to suppress the immune system and promote angiogenesis via Signal transducer and activator of transcription 3 (STAT3) activation. As of now there is no data available on the correlation of Gr1-positive cell number, phosphorylated STAT3 (p-STAT3) expression and cancer ability to metastasis. Thus, we counted the myeloid precursor cell number and analyzed p-STAT3 expression in 50 canine mammary tumors that gave local/distant metastases and did not metastasize. We showed that the number of Gr1-positive cells and p-STAT3 expression are significantly higher (p < 0.001) in the metastatic tumors than in the non-metastatic ones. We also observed higher expression of p-STAT3 in the canine mammary cancer cell lines with metastatic potential than in other cell lines (p < 0.001). Moreover, the number of myeloid precursors and p-STAT3 expression in metastatic tumors correlate strongly. The tumor infiltrating myeloid precursor cells may invigorate the STAT3 activity (probably via vascular endothelial growth factor – VEGF) that contributes to the tumor angiogenesis and furthermore tumor`s ability to metastasize. The analysis of gene expression in canine mammary cancer cell lines with metastatic potential indicated that semaphorin 3B (SEMA3B) and neuropilin receptors (NRP) may also be important elements in this process. Thus, we discuss the possible interactions within the tumor that may be required for cancer metastatis