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931.
932.
Marzena Pawul-Gruba Tomasz Kiljanek Anna Madejska Jacek Osek 《Molecules (Basel, Switzerland)》2022,27(23)
Biogenic amines (BAs) are organic, basic nitrogenous compounds formed during the decarboxylation of amino acids. A method for the determination of eight biogenic amines (tryptamine, 2-phenyletylamine, putrescine, cadaverine, histamine, tyramine, spermidine, spermine) in ripened cheeses was developed and validated. Cheese samples with the addition of internal standards were extracted with 0.2 M perchloric acid and pre-column derivatized with dansyl chloride at 60 °C for 15 min, purified with toluene and dried under a stream of nitrogen. The samples were analyzed using high performance liquid chromatography with diode array detector (HPLC-DAD). The method was validated with the BAs at three concentration levels: 50, 100, and 200 mg/kg, respectively. The obtained values of correlation coefficient (R2) ranged at 0.9997–0.9998 for all of compounds. The limits of detection (LOD) and quantification (LOQ) were in ranges 1.53–1.88 and 5.13–6.28 mg/kg, respectively. The recovery for all of biogenic amines ranged from 70 to 120% and the precision (RSDr) value were <20%. The validated method was applied to analysis of 35 real ripened cheese samples purchased in Poland. 相似文献
933.
Mohammed A. Amin Gaber A. M. Mersal Morad M. El-Hendawy Abdallah A. Shaltout Ali Badawi Johan Boman Adil A. Gobouri Murat Saracoglu Fatma Kandemirli Rabah Boukherroub Jacek Ryl Mohamed E. Khalifa 《Molecules (Basel, Switzerland)》2022,27(17)
Novel cyano-benzylidene xanthene derivatives were synthesized using one-pot and condensation reactions. A diprotic Brønsted acid (i.e., oxalic acid) was used as an effective catalyst for the promotion of the synthesis process of the new starting xanthene–aldehyde compound. Different xanthene concentrations (ca. 0.1–2.0 mM) were applied as corrosion inhibitors to control the alkaline uniform corrosion of aluminum. Measurements were conducted in 1.0 M NaOH solution using Tafel extrapolation and linear polarization resistance (LPR) methods. The investigated xanthenes acted as mixed-type inhibitors that primarily affect the anodic process. Their inhibition efficiency values were enhanced with inhibitor concentration, and varied according to their chemical structures. At a concentration of 2.0 mM, the best-performing studied xanthene derivative recorded maximum inhibition efficiency values of 98.9% (calculated via the Tafel extrapolation method) and 98.4% (estimated via the LPR method). Scanning electron microscopy (SEM) was used to examine the morphology of the corroded and inhibited aluminum surfaces, revealing strong inhibitory action of each studied compound. High-resolution X-ray photoelectron spectroscopy (XPS) profiles validated the inhibitor compounds’ adsorption on the Al surface. Density functional theory (DFT) and Monte Carlo simulations were applied to investigate the distinction of the anticorrosive behavior among the studied xanthenes toward the Al (111) surface. The non-planarity of xanthenes and the presence of the nitrile group were the key players in the adsorption process. A match between the experimental and theoretical findings was evidenced. 相似文献
934.
Magdalena Wyszyska Monika Nitsze-Wierzba Aleksandra Czelakowska Jacek Kasperski Joanna ywiec Magorzata Skucha-Nowak 《Molecules (Basel, Switzerland)》2022,27(13)
The measurement of nitric oxide (NO) in exhaled air is used in diagnostics and monitoring the pathologies not only in the respiratory system but also in the oral cavity. It has shown a huge increase in its level in asthma and diseases of the oral cavity. It seems reasonable to undertake research on the impact of inflammation on the level of NO in exhaled air. The aim of the study is to make an evidence-based review of the application of NO levels in exhaled air in the diagnosis of inflammation and treatment monitoring on the basis of selected measuring devices. Methods and Results: This paper presents an example of the application of NO measurement in exhaled air in individual human systems. Selected measuring devices, their non-invasiveness, and their advantages are described. Discussion: The usefulness of this diagnostic method in pathologies of the oral cavity was noted. Conclusions: Measuring the level of NO in exhaled air seems to be a useful diagnostic method. 相似文献
935.
Ewa Dumiszewska Pawe Ciepielewski Piotr A. Caban Iwona J
wik Jaroslaw Gaca Jacek M. Baranowski 《Molecules (Basel, Switzerland)》2022,27(11)
The problem of graphene protection of Ge surfaces against oxidation is investigated. Raman, X-Ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements of graphene epitaxially grown on Ge(001)/Si(001) substrates are presented. It is shown that the penetration of water vapor through graphene defects on Gr/Ge(001)/Si(001) samples leads to the oxidation of germanium, forming GeO2. The presence of trigonal GeO2 under graphene was identified by Raman and XRD measurements. The oxidation of Ge leads to the formation of blisters under the graphene layer. It is suggested that oxidation of Ge is connected with the dissociation of water molecules and penetration of OH molecules or O to the Ge surface. It has also been found that the formation of blisters of GeO2 leads to a dramatic increase in the intensity of the graphene Raman spectrum. The increase in the Raman signal intensity is most likely due to the screening of graphene by GeO2 from the Ge(001) surface. 相似文献
936.
Dr. Arkadiusz Listkowski Dr. Natalia Masiera Michał Kijak Dr. Roman Luboradzki Dr. Barbara Leśniewska Prof. Jacek Waluk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(20):6324-6333
Porphycene, a porphyrin isomer, is an efficient fluorophore. However, four-fold meso substitution with alkyl groups decreases the fluorescence quantum yield by orders of magnitude. For aryl substituents, this effect is small. To explain this difference, we have synthesized and studied a mixed aryl-alkyl-substituted compound, 9,20-diphenyl-10,19-dimethylporphycene, as well as the 9,20-diphenyl and 9,20-dimethyl derivatives. Analysis of the structural, spectroscopic, and photophysical data of the six porphycenes, combined with quantum chemical calculations, shows a clear correlation between the strength of the intramolecular NH⋅⋅⋅N hydrogen bonds and the efficiency of the radiationless depopulation of the lowest-excited singlet state. This result led us to propose a model in which the delocalization of the inner protons in the cavity of the macrocycle is responsible for the nonradiative deactivation channel. The applicability of the model is confirmed by the literature data for other alkyl- or aryl-substituted porphycenes. The finding of a correlation between structural and emissive characteristics enables a rational design of porphycenes with desired photophysical properties. 相似文献
937.
Macewicz Ł. Skowierzak G. Niedziałkowski P. Ryl Jacek Ossowski T. Bogdanowicz R. 《Russian Journal of Electrochemistry》2021,57(3):245-254
Russian Journal of Electrochemistry - In this paper, 9,10-anthraquinone (AQ) derivative-modified glassy carbon (GC) electrodes were studied towards the electrochemical reduction of oxygen in... 相似文献
938.
Somenath Chowdhury Jianmin Mao Jacek Martynow He Zhao Erin Duffy Yusheng Wu Vinay Thakur Gopal Sirasani Yuanqing Tang Florine Collin Sandra Sinishtaj Ashoke Bhattacharjee 《Tetrahedron letters》2019,60(4):371-374
Highly efficient substrate and reagent controlled stereoselective synthesis of 2,6-trans-piperidine derivative (1) using an aza-Michael reaction is reported. This method was utilized to synthesize a variety of trans-piperidines on hundred-gram scales. 相似文献
939.
Butowska Kamila Kozak Witold Zdrowowicz Magdalena Makurat Samanta Rychłowski Michał Hać Aleksandra Herman-Antosiewicz Anna Piosik Jacek Rak Janusz 《Structural chemistry》2019,30(6):2327-2338
Structural Chemistry - Conjugating an anticancer drug of high biological efficacy but large cytotoxicity with a “transporting” molecule of low toxicity constitutes a valuable approach... 相似文献
940.
Dr. Jakub Ostapko Dr. Aleksander Gorski Dr. Joanna Buczyńska Dr. Barbara Golec Dr. Krzysztof Nawara Dr. Anastasiia Kharchenko Dr. Arkadiusz Listkowski Dr. Magdalena Ceborska Dr. Mariusz Pietrzak Prof. Jacek Waluk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16666-16675
Free base and zinc porphyrins functionalized with cyclooctatetraene (COT), a molecule known as a good triplet-state quencher, have been obtained and characterized in detail by structural, spectral, and photophysical techniques. Substitution with COT leads to a dramatic decrease of the intrinsic lifetime of the porphyrin triplet. As a result, photostability in oxygen-free solution increases by two to three orders of magnitude. In non-degassed solutions, improvement of photostability is about tenfold for zinc porphyrins, but the free bases become less photostable. Similar quantum yields of photodegradation in free base and zinc porphyrins containing the COT moiety indicate a common mechanism of photochemical decomposition. The new porphyrins are expected to be much less phototoxic, since the quantum yield of singlet oxygen formation strongly decreases because of the shorter triplet lifetime. The reduction of triplet lifetime should also enhance the brightness and reduce blinking in porphyrin chromophores emitting in single-molecule regime, since the duration of dark OFF states will be shorter. 相似文献