Relationships between serum adiponectin and soluble TNF-α receptors and glucose and lipid oxidation in lean and obese subjects

Insulin resistance might be associated with an impaired ability of insulin to stimulate glucose oxidation and inhibit lipid oxidation. Insulin action is also inversely associated with TNF-α system and positively related to adiponectin. The aim of the present study was to analyze the associations between serum adiponectin, soluble TNF-α receptors concentrations and the whole-body insulin sensitivity, lipid and glucose oxidation, non-oxidative glucose metabolism (NOGM) and metabolic flexibility in lean and obese subjects. We examined 53 subjects: 25 lean (BMI < 25 kg × m−2) and 28 with overweight or obesity (BMI > 25 kg × m−2) with normal glucose tolerance. Hyperinsulinemic euglycemic clamp and indirect calorimetry were performed. An increase in respiratory exchange ratio in response to insulin was used as a measure of metabolic flexibility. Obese subjects had lower insulin sensitivity, adiponectin and higher sTNFR1 (all P < 0.001) and sTNFR2 (P = 0.001). Insulin sensitivity was positively related to adiponectin (r = 0.49, P < 0.001) and negatively related to sTNFR1 (r = −0.40, P = 0.004) and sTNFR2 (r = −0.52, P < 0.001). Adiponectin was related to the rate of glucose (r = 0.47, P < 0.001) and lipid (r = −0.40, P = 0.003) oxidation during the clamp, NOGM (r = 0.41, P = 0.002) and metabolic flexibility (r = 0.36, P = 0.007). Serum sTNFR1 and sTNFR2 were associated with the rate of glucose (r = −0.45, P = 0.001; r = −0.51, P < 0.001, respectively) and lipid (r = 0.52, P < 0.001; r = 0.46, P = 0.001, respectively) oxidation during hyperinsulinemia, NOGM (r = −0.31, P = 0.02; r = −0.43, P = 0.002, respectively) and metabolic flexibility (r = −0.47 and r = −0.51, respectively, both P < 0.001) in an opposite manner than adiponectin. Our data suggest that soluble TNF-α receptors and adiponectin have multiple effects on glucose and lipid metabolism in obesity

A hydrodynamic interaction between bubbles and gas supply system during gas bubble departures in liquids: an experimental study

Abstract In the present paper, the hydrodynamic interactions between bubbles and the gas supply system to a needle were experimentally investigated. In experimental investigations in one of the needles, the air volume flow rate was constant, and in the neighbouring needle, it was changed. In the paper, the methods of data analysis: wavelet decomposition, and FFT were used. It was shown that the hydrodynamic interaction becomes stronger with the increase in air volume flow rate supply to the needle. The occurrence of hydrodynamic interaction modifies bubble growth time slightly, but it significantly modifies the bubble waiting time. In the case when the liquid penetration into the needle is repeatable, then the percentage disturbances in bubble growth time and bubble waiting time are close to each other. Moreover, it can be concluded that synchronized or alternative bubble departures from twin neighbouring needles (occurring due to hydrodynamic interaction) are possible by modifying the bubble waiting time. The modification of hydrodynamic interaction between bubbles, the bubbles themselves, and gas supply systems can be used to control the bubble departure process

An attempt to preliminary evaluation of modified polypropylene in aspect of its application in plain bearings of agricultural machines

Przeprowadzono wstępne badania laboratoryjne polipropylenowych, nasyconych olejami naturalnymi panewek samosmarownych łożysk ślizgowych. Wyznaczono moment siły tarcia i temperaturę pracy układu panewka - czop. Zaobserwowano wysoki stopień nasycenia polipropylenu olejami EMKOL-paliwowy i EM-KOL-smarny (17,43% i 17,33%) w porównaniu ze stopniem nasycenia stosowanym w łożyskach ślizgowych Tarnamidu T-27M (2,34% i 2,26%). Przy obrotach n = 200/min., odpowiadających prędkości liniowej v = 0,1 m/s, zaobserwowano po około 250 s zacieranie się próbek poliamidowych (Tarnamid T-27 M) i wzrost momentu siły tarcia od Mp = 100 Ncm do Mk = 225-255 Ncm. Nie zaobserwowano zatarcia próbek polipropylenowych nawet po 900 s, a moment siły tarcia utrzymywał się na stałym poziomie Mp = Mk = 100 Ncm. Na tej podstawie wstępnie oceniono pozytywnie próbę zastosowania kompozytu polipropylenowo-olejowego w samosmarownych łożyskach ślizgowych. Wskazano konieczność wykonania zwiększonego zakresu prób w celu pełnej oceny trybologicznej badanego materiału.Self-lubricating, polypropylene plain bearings, impregnated with natural vegetable oils, were tested under laboratory conditions. The moment of friction force and working temperature were determined for investigated pin-plane bearing system. High degrees of polypropylene impregnation with the use of EMKOL-fuel and EMKOL-lubricating oils were observed (17.43 and 17.33%, respectively), in comparison to the impregnation of plain bearings with Tarnamid T-27M (2.34 and 2.26%, respectively). At the rotations of n = 200 r.p.m., equivalent to linear velocity v = 0.1 m/s, the seizing of polyamide (Tarnamid T-27M) samples and increas-ing friction force moment from Mp = 100 Ncm up to Mk = 225 -255 Ncm, were observed just after about 250 sec. In case of polypropylene samples no seizing was noted even after 900 sec. and the friction force moment was kept at constant level Mp = Mk = 100 Ncm. On such a basis an attempt to using the polypropylene-oil composite in self-lubricating plain bearings was estimated positively. It was also indicated the necessity of further extended investigations to obtain the results which would enable full tribological evaluation of the materials tested