Vibration Control of Mechanical Systems - introduction to the problem

Príèiny vibrácií strojov sú rôznorodé a je ich ako analyzova. Ich analýza je ve¾mi dôleitá, nako¾ko vibrácie majú negatívne úèinky nielen na ivotnos, prevádzkyschopnos strojov, ale i na obsluhu strojov a ivotné prostredie. V èlánku sú charakterizované základné postuláty pasívnych a aktívnych metód pre analýzu, syntézu a návrhu útlmu vibrácií s vyuitím princípu riadených vibrácií. Vyuitie matematického modelovania mechanického systému a riadenia je predmetom súèasného simulaèného výskumu vo svete. Uvedená teória je úspene aplikovaná pre útlm, redukciu vibrácií strojov, rotorov zariadení, budov, komunikaèných prostriedkov

Catalytic Performance of One-Pot Synthesized Fe-MWW Layered Zeolites (MCM-22, MCM-36, and ITQ-2) in Selective Catalytic Reduction of Nitrogen Oxides with Ammonia

[EN] The application of layered zeolites of MWW topology in environmental catalysis has attracted growing attention in recent years; however, only a few studies have explored their performance in selective catalytic reduction with ammonia (NH3-SCR). Thus, our work describes, for the first time, the one-pot synthesis of Fe-modified NH3-SCR catalysts supported on MCM-22, MCM-36, and ITQ-2. The calculated chemical composition of the materials was Si/Al of 30 and 5 wt.% of Fe. The reported results indicated a correlation between the arrangement of MWW layers and the form of iron in the zeolitic structure. We have observed that one-pot synthesis resulted in high dispersion of Fe3+ sites, which significantly enhanced low-temperature activity and prevented N2O generation during the reaction. All of the investigated samples exhibited almost 100% NO conversion at 250 degrees C. The most satisfactory activity was exhibited by Fe-modified MCM-36, since 50% of NO reduction was obtained at 150 degrees C for this catalyst. This effect can be explained by the abundance of isolated Fe3+ species, which are active in low-temperature NH3-SCR. Additionally, SiO2 pillars present in MCM-36 provided an additional surface for the deposition of the active phase.Agnieszka Szymaszek-Wawryca gratefully acknowledges the financial support of the research from the National Science Centre Grant, Preludium 19 (no. 2020/37/N/ST5/00186). Monika Motak would like to kindly acknowledge AGH Grant "Excellence Initiative-Research University" (no. 501.696.7996) for the financial support. Bogdan Samojeden is thankful to AGH Grant (no. 16.16.210.476) for the foundation of the publication. Urbano Diaz acknowledges the support from the Government of Spain through the project PID2020-112590GB-C21/AEI/10.13039/501100011033.Szymaszek-Wawryca, A.; Díaz Morales, UM.; Samojeden, B.; Motak, M. (2022). Catalytic Performance of One-Pot Synthesized Fe-MWW Layered Zeolites (MCM-22, MCM-36, and ITQ-2) in Selective Catalytic Reduction of Nitrogen Oxides with Ammonia. Molecules. 27(9):1-24. https://doi.org/10.3390/molecules2709298312427

RECENZJE

Aleksandra Kajdańska, Edward Kajdański, Jedwab. Szlakami dżonek i karawan, Książka i Wiedza, Warszawa 2007, ss. 528 (Monika Miazek-Męczyńska)Edward Kajdański, Wspomnienia z mojej Atlantydy, Wydawnictwo Literackie, Kraków 2013, ss. 530 (Bogdan Góralczyk

MCM-22, MCM-36, and ITQ-2 Zeolites with Different Si/Al Molar Ratios as Effective Catalysts of Methanol and Ethanol Dehydration

[EN] MCM-22, MCM-36, and ITQ-2 zeolites with the intended Si/Al molar ratios of 15, 25, and 50 were synthetized and tested as catalysts for dehydration of methanol to dimethyl ether and dehydration of ethanol to diethyl ether and ethylene. The surface concentration of acid sites was regulated by the synthesis of zeolite precursors with different aluminum content in the zeolite framework, while the influence of porous structure on the overall efficiency of alcohol conversion was analyzed by application of zeolitic materials with different types of porosity-microporous MCM-22 as well as microporous-mesoporous MCM-36 and ITQ-2. The zeolitic samples were characterized with respect to their: chemical composition (ICP-OES), structure (XRD, FT-IR), texture (N-2 sorption), and surface acidity (NH3-TPD). Comparison of the catalytic activity of the studied zeolitic catalysts with other reported catalytic systems, including zeolites with the similar Si/Al ratio as well as gamma-Al2O3 (one of the commercial catalysts for methanol dehydration), shows a great potential of MCM-22, MCM-36, and ITQ-2 in the reactions of alcohols dehydration.This research was funded by National Science Centre-Poland grant number 2016/21/B/ST5/00242. U.D. acknowledges to the Spanish Government grant number MAT2017-82288-C2-1-P. The research was partially done using the equipment purchased from the funds of European Regional Development Fund, Polish Innovation Economy Operational Program, grant numberPOIG.02.01.00-12-023/08.Marosz, M.; Samojeden, B.; Kowalczyk, A.; Rutkowska, M.; Motak, M.; Díaz Morales, UM.; Palomares Gimeno, AE.... (2020). MCM-22, MCM-36, and ITQ-2 Zeolites with Different Si/Al Molar Ratios as Effective Catalysts of Methanol and Ethanol Dehydration. 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Ocena funkcji serca oraz naczyń u pacjentów z klasyczną postacią wrodzonego przerostu nadnerczy

Introduction: Patients with classical congenital adrenal hyperplasia (CAH) have increased cardiovascular risk, but the vascular and cardiac function during longitudinal corticoids replacement therapy is not known thoroughly. Material and methods: Cross-sectional study of 19 Caucasian adults with CAH (age 23.7 ± 3.8 years; twelve males) compared to 20 healthy volunteers matched for origin, sex, age, and body mass index (BMI). All of the participants were assessed for flow mediated dilatation of the brachial artery (FMD), intima-media thickness of the common carotid artery (cIMT) and common femoral artery (fIMT), standard echocardiography, and global longitudinal left ventricular function using two-dimensional speckle-tracking echocardiography (LSTE). Results: The patients with CAH, compared with controls, had decreased FMD (9.4 ± 3.9 vs. 19.8 ± 5.2; p < 0.01), and the difference was still significant after correction for potential confounders. cIMT and fIMT were higher in the CAH group at baseline (for cIMT 0.47 ± 0.4 mm vs. 0.40 ± 0.03 mm; p < 0.01, for fIMT 0.47 ± 0.05 mm vs. 0.41 ± 0.04 mm; p < 0.01) but not after correction for potential confounders. The CAH subjects, compared with controls, had normal or similar left ventricular (LV) ejection fraction and LV mass index. The mean absolute value of LSTE differed in the CAH patients compared with controls (–20.5% ± 1.2 vs. –22.5% ± 1.7; p < 0.01), but it was still within the normal range. Conclusions: Young adults with CAH and glucocorticoid long-lasting treatment had impaired FMD, an insignificant increase of IMT, and subclinical changes in LV diastolic function in echocardiography.Wstęp: Pacjenci z klasyczną postacią wrodzonego przerostu nadnerczy (congenital adrenal hyperplasia, CAH) charakteryzują się zwiększonym ryzykiem sercowo-naczyniowym, jednak funkcja naczyń oraz serca podczas długotrwałej substytucyjnej terapii glikokortykoidami nie została jednoznacznie określona. Pacjenci i metody: W badaniu obserwacyjnym, 19 dorosłych rasy białej z CAH (wiek 23,7 ± 3,8 roku; 12 mężczyzn) porównywano z 20 zdrowymi ochotnikami dobranymi pod względem pochodzenia, płci, wieku i współczynnika masy ciała. U wszystkich uczestników badania oceniono wazodylatację tętnicy ramiennej indukowaną przepływem (flow mediated dilatation, FMD), grubość kompleksu intima–media tętnicy szyjnej wspólnej (intima-media thickness of the common carotid artery, cIMT) oraz tętnicy udowej (common femoral artery, fIMT) wspólnej oraz oceniono odkształcenie lewej komory przy zastosowaniu techniki śledzenia markerów akustycznych (longitudinal speckle-tracking echocardiography, LSTE). Wyniki: U pacjentów z CAH w porównaniu z grupą kontrolną zaobserwowano mniejszą wartość FMD (9,4 ± 3,9 vs. 19,8 ± 5,2; p < 0,01) i różnica ta była nadal istotna po uwzględnieniu wpływu średnicy tętnicy ramiennej. Wyjściowo cIMT i fIMT były większe u pacjentów z CAH (cIMT 0,47 ± 0,4 mm vs. 0.40 ± 0,03 mm, p < 0,01; fIMT 0,47 ± 0,05 mm vs. 0,41 ± 0,04 mm, p < 0,01), ale nie po uwzględnieniu klasycznych czynników ryzyka sercowo-naczyniowego. Frakcja wyrzutowa oraz masa lewej komory w obu grupach były podobne. Średnia wartość LSTE była różna u pacjentów z CAH z porównaniu z grupą kontrolną (–20,5 ± 1,2% vs. –22,5 ± 1,7%, p < 0,01), ale nadal pozostawała w granicach normy. Wnioski: U młodych dorosłych z CAH długotrwale leczonych glikokortykosteroidami FMD jest upośledzona, występuje nieistotne pogrubienie cIMT i fIMT oraz podkliniczne zmiany w funkcji rozkurczowej serca w echokardiografii

Effect of Magnesium Substitution on Dielectric Constant of Zn2-xMgxInV3O11 (x = 0.0, 0.4, 1.6) Solid Solutions

The results of magnetic and dielectric measurements of Zn2xMgxInV3O11 phases with x = 0:0, 0.4, and 1.6 showed diamagnetic behavior above room temperature and a strong increase in the relative electrical permittivity, "r, with an increase in the magnesium content as well as the high loss tangent, tan , above 150 K, irrespective of the magnesium content in the sample. With the increase in the frequency of the electric field both "r and tan strongly decreased. At low temperatures a residual paramagnetism coming from the paramagnetic ions of vanadium was observed. These effects were interpreted within a framework of the vacancy trapping centers acting as the accumulation of electric charges on the one hand and a mixed valence of vanadium ions on the other

Dielectric and magnetic characteristics of Ca1−xMnxMoO4 (0 ≤ x ≤ 0.15) nanomaterials

Scheelite-type Ca1−xMnxMoO4 (x = 0.0,0.01, 0.05, 0.10 and 0.15) nanomaterials were successfully synthesized via a combustion route. Dielectric studies showed a weak n-type electrical conductivity characteristic for insulators and low relative permittivity (εr < 15) decreasing with increasing Mn2+ content. CaMoO4 and Mn2+-doped nanomaterials are chemically compatible with Al and Ag electrodes and promising for lowtemperature co-fired ceramic applications. Magnetic studies showed, at room-temperature diamagnetism for pure CaMoO4, the balance between diamagnetism and paramagnetism for Ca1−xMnxMoO4 (x = 0.01) and paramagnetic behaviour when 0.05 ≤ x ≤ 0.15 as well as the short-range antiferromagnetic interactions growing in strength as Mn2+ content increases. The Landé factor fitting procedure showed a spin-only contribution to the magnetic moment. CaMoO4 matrix unexpectedly revealed the residual paramagnetism at low temperatures derived probably from the molybdenum ions having unpaired 4d electrons as well as a paramagneticdiamagnetic transition at 70 K

Glucagon-like peptide-1 receptor agonist stimulates mitochondrial bioenergetics in human adipocytes

Glucagon-like peptide 1 receptor agonists (GLP-1RAs) are relatively new pharmacological agents used to normalize glucose level in type 2 diabetes. Recently, GLP-1RAs have been approved for the treatment of obesity to reduce body weight in non-diabetic patients. The extra-pancre-atic effects of GLP-1RAs, as well as their molecular mechanism of action, are still poorly understood. Thus this study was aimed to verify the hypothesis that the mechanism of action of the GLP-1RAs involves mitochondria and that GLP-1RAs administration can improve mitochondrial functions. For this purpose, preadipocytes CHUBS7 were differentiated to mature adipocytes and then stimulated with GLP-1RA, exendin-4 at 100 nM for 24 h. Oxygen consumption rates, mitochondrial membrane potential, intracellular ATP (adenosine triphosphate) level, SIRT1 and SIRT3 gene expression and the histone deacetylases' activity were measured. Exendin-4 was found to uncouple mitochondrial electron transport from ATP synthesis, slightly decreasing mitochondrial membrane potential in mature adipocytes. Routine respiration and uncoupled oxy- gen consumption rates were higher in exendin-4 treated adipocytes than in the non-treated cells. The ATP level remained unchanged. Exendin-4 enhanced SIRT1 and SIRT3 genes expression. Histone deacetylases' activity in the nuclear fraction was not affected by exendin-4, although the activity of class III histone deacetylases was increased. All of the effects on mitochondrial bioenergetics induced by exendin-4 were abolished by addition of glucagon-like peptide 1 receptor antagonist. In conclusion, exendin-4 activates the sirtuin pathway and increases energy expenditure in human adipocytes. Our results suggest another mechanism that may be responsible for body weight reduction observed in patients using GLP-1RAs