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61.
Milan Melník Peter Mikuš Ivan Malík 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):1015-1019
AbstractIn this review structural parameters of forty complexes with an inner coordination sphere of Pt(η2-P2L)(η2-S2L) are analyzed and classified These complexes crystallize in three crystal systems: orthorhombic (four examples), triclinic (six examples) and monoclinic (thirty examples). The organodiphosphines create four- (PCP), five- (PC2P), six- (PC3P) and seven- (PC4P) membered metallocyclic rings with mean P-Pt-P bite angle values of 72.5° (PCP) < 85.3° (PC2P) < 93.0° (PC3P) < 97.4° (PC4P). The dithiolates create four- (SCS), five- (SC2S), six- (SC3S; SCSCS; SPNPS; SPCPS) and seven- (SC4S) membered metallocyclic rings with mean S-Pt-S bite angle values of 74.5° (SCS) < 85.8° (SCSCS) < 87.0° (SPNPS) < 89.0° (SC2S) < 92.3° (SC4S) < 93.5° (SC3S) < 97.5° (SPCPS). The mean Pt-P and Pt-S bond distances are 2.257 and 2.328?Å, respectively. The data are compared with those found in complexes with inner coordination spheres of Pt(PL)2(SL)2, Pt(PL)2(η2-S2L) and Pt(η2-P2L)(SL)2. 相似文献
62.
Violeta Marković Svetlana Marković Ana Janićijević Marko V. Rodić Vukadin M. Leovac Nina Todorović Snežana Trifunović Milan D. Joksović 《Structural chemistry》2013,24(6):2127-2136
A study on the synthesis and mechanistical aspects of formation of 3-methyl-5-oxo-3-pyrazolin-1-carboxamide (MOPC) starting from S-methylisothiosemicarbazide hydrogen iodide and methyl acetoacetate was performed. In the alkaline aqueous solution, the intermediate methyl acetoacetate S-methylisothiosemicarbazone undergoes substitution of CH3S? anion by hydroxide anion, cyclization, carbanion formation, and elimination of methanol, thus yielding corresponding Na-enolate salt of pyrazol-5-one derivative. The structure of the compound obtained after protonation of the formed enolate salt was determined by means of spectroscopic techniques and single-crystal X-ray diffraction analysis. The mechanism of conversion of methyl acetoacetate S-methylisothiosemicarbazone into MOPC was investigated by means of the B3LYP functional, and it was found that the reaction is thermodynamically controlled. 相似文献
63.
64.
Tomas Bertok Pavol Gemeiner Milan Mikula Peter Gemeiner Jan Tkac 《Mikrochimica acta》2013,180(1-2):151-159
We report on an ultrasensitive label-free lectin-based impedimetric biosensor for the determination of the sialylated glycoproteins fetuin and asialofetuin. A sialic acid binding agglutinin from Sambucus nigra I was covalently immobilised on a mixed self-assembled monolayer (SAM) consisting of 11-mercaptoundecanoic acid and 6-mercaptohexanol. Poly(vinyl alcohol) was used as a blocking agent. The sensor layer was characterised by atomic force microscopy, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The biosensor exhibits a linear range that spans 7 orders of magnitude for both glycoproteins, with a detection limit as low as 0.33 fM for fetuin and 0.54 fM for asialofetuin. We also show, by making control experiments with oxidised asialofetuin, that the biosensor is capable of quantitatively detecting changes in the fraction of sialic acid on glycoproteins. We conclude that this work lays a solid foundation for future applications of such a biosensor in terms of the diagnosis of diseases such as chronic inflammatory rheumatoid arthritis, genetic disorders and cancer, all of which are associated with aberrant glycosylation of protein biomarkers. Figure
Key aspects of the biosensor: 1) mixed SAM formation, 2) immobilisation of lectin & blocking and 3) a glycoprotein recognition. 相似文献
65.
Marcel Špulák Zdeněk Novák Karel Palát Jiří Kuneš Jana Pourová Milan Pour 《Tetrahedron》2013,69(6):1705-1711
Contrary to a number of reports, alkylations of the privileged 3,4-dihydroquinazoline scaffold provide N3-alkylated products, and not 4-alkoxyquinazolines. To correctly assign the structure, 13C NMR shifts of the –Z–CHn– (Z=O, N) fragment are necessary; resonances in the 45–55 ppm range are indicative of N3-alkylation. Treatment of 3,4-dihydroquinazoline-4-one with p-TsCl afforded the N3-tosylated compound, whose reaction with an amine yielded the corresponding N3-alkyl derivative. A mechanism corroborated by 15N-labeling involving pyrimidine ring opening and recyclisation is proposed. Finally, the unambiguous preparation of 4-alkoxyquinazolines is described via treatment of 3,4-dihydroquinazoline-4-ones with PCl5 followed by an alkoxide. 相似文献
66.
Oxidative stress plays a key role in the pathophysiology of many diseases. Hydroxyl radical is the oxidative species most commonly causing damage to cells. The aim of this work was to optimize the method for antioxidant activity determination on a model lipophilic geranylated flavanone, diplacone. This method uses protection of plasmid DNA from oxidation by a hydroxyl radical generated by the Fenton reaction involving oxidation of metal ions using H2O2 and ascorbate. The method was optimized for lipophilic compounds using several solvents and co-solvents. It was found that (2-hydroxypropyl)-β-cyclodextrin (0.1 mass % aq. sol.) is the best co-solvent for our model lipophilic compound to measure the antioxidant activity by the method presented. Other solvents, namely dimethyl sulfoxide, Cremophor EL® (0.1 mass % aq. sol.), ethanol, and methanol, were not suitable for the determination of the antioxidant activity by the method described. Tween 80 (0.1 mass % aq. sol.) and a mixture of 10 vol. % ethanol and 9 mass % bovine serum albumin (aq. sol.) significantly decreased the antioxidant activity of the model lipophilic compound and thus were not suitable for this method. 相似文献
67.
Dr. Mark Feyand Milan Köppen Prof. Dr. Gernot Friedrichs Prof. Dr. Norbert Stock 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(37):12537-12546
A systematic investigation of the systems Bi3+/carboxylic acid/HNO3 for the tri‐ and tetracarboxylic acids pyromellitic acid (H4Pyr), trimellitic acid (H3Tri) and trimesic acid (H3BTC) acid led to the discovery of five new bismuth carboxylates. Structural characterisation allowed the influence of the linker geometry and the Bi3+:linker molar ratio in the starting solution on the crystal structure to be determined. The crystallisation of three selected compounds was investigated by in situ energy‐dispersive X‐ray diffraction. Three new crystalline intermediates were observed within minutes, and two of them could be isolated by quenching of the reaction mixture. Their crystal structures were determined from laboratory and synchrotron X‐ray powder diffraction data and allowed a possible reaction pathway to be established. In depth characterisation of the luminescence properties of the three bismuth pyromellate compounds was carried out. Fluorescence and phosphorescence could be assigned to (mainly) ligand‐ and metal‐based transitions. The polymorphs of Bi(HPyr) exhibit different luminescence properties, although their structures are very similar. Surprisingly, doping of the three host structures with Eu3+ and Tb3+ ions was only successful for one of the polymorphs. 相似文献
68.
Mahrous Awad M. A. El-Desoky A. Ghallab Jan Kubes S. E. Abdel-Mawly Subhan Danish Disna Ratnasekera Mohammad Sohidul Islam Milan Skalicky Marian Brestic Alaa Baazeem Saqer S. Alotaibi Talha Javed Rubab Shabbir Shah Fahad Muhammad Habib ur Rahman Ayman EL Sabagh 《Molecules (Basel, Switzerland)》2021,26(11)
Accumulation of heavy metals (HMs) by ornamental plants (OPs) from contaminated agriculture soils is a unique technique that can efficiently reduce the metal load in the food chain. Amaranthus tricolor L. has attractive characteristics acquiring a higher growth rate and large biomass when grown at heavy metal contaminated soils. Site-specific detailed information is not available on the use of A. tricolor plant in metal phytoremediation from the polluted sites. The study aimed to enhance the uptake of HMs (Pb, Zn, and Cu) via amending poultry litter extract (PLE), vinasse sugarcane (VSC), and humic acid (HA) as natural mobilized organic materials compared to ethylene diamine tetraacetic acid (EDTA), as a common mobilized chemical agent by A. tricolor plant. The studied soils collected from Helwan, El-Gabal El-Asfar (Cairo Governorate), Arab El-Madabeg (Assiut Governorate), Egypt, and study have been conducted under pot condition. Our results revealed all organic materials in all studied soils, except EDTA in EL-Gabal El-Asfar soil, significantly increased the dry weight of the A. tricolor plant compared to the control treatment. The uptake of Pb and Zn significantly (p > 0.05) increased due to applying all organic materials to the studied soils. HA application caused the highest uptake as shown in Pb concentration by more than 5 times in Helwan soil and EDTA by 65% in El-Gabal El-Asfar soil while VSC increased it by 110% in El-Madabeg soil. Also, an increase in Zn concentration due to EDTA application was 58, 42, and 56% for Helwan, El-Gabal El-Asfar, and El-Madabeg soil, respectively. In all studied soils, the application of organic materials increased the remediation factor (RF) than the control. El-Madabeg soil treated with vinasse sugarcane gave the highest RF values; 6.40, 3.26, and 4.02% for Pb, Zn, and Cu, respectively, than the control. Thus, we identified A. tricolor as a successful ornamental candidate that, along with organic mobilization amendments, most efficiently develop soil health, reduce metal toxicity, and recommend remediation of heavy metal-contaminated soils. Additionally, long-term application of organic mobilization amendments and continued growth of A. tricolor under field conditions could be recommended for future directions to confirm the results. 相似文献
69.
Zahoor Ahmad Shazia Anjum Milan Skalicky Ejaz Ahmad Waraich Rana Muhammad Sabir Tariq Muhammad Ashar Ayub Akbar Hossain Mohamed M. Hassan Marian Brestic Mohammad Sohidul Islam Muhammad Habib-Ur-Rahman Allah Wasaya Muhammad Aamir Iqbal Ayman EL Sabagh 《Molecules (Basel, Switzerland)》2021,26(6)
Drought poses a serious threat to oilseed crops by lowering yield and crop failures under prolonged spells. A multi-year field investigation was conducted to enhance the drought tolerance in four genotypes of Camelina and canola by selenium (Se) application. The principal aim of the research was to optimize the crop yield by eliciting the physio-biochemical attributes by alleviating the adverse effects of drought stress. Both crops were cultivated under control (normal irrigation) and drought stress (skipping irrigation at stages i.e., vegetative and reproductive) conditions. Four different treatments of Se viz., seed priming with Se (75 μM), foliar application of Se (7.06 μM), foliar application of Se + Seed priming with Se (7.06 μM and 75 μM, respectively) and control (without Se), were implemented at the vegetative and reproductive stages of both crops. Sodium selenite (Na2SeO3), an inorganic compound was used as Se sources for both seed priming and foliar application. Data regarding physiochemical, antioxidants, and yield components were recorded as response variables at crop maturity. Results indicated that WP, OP, TP, proline, TSS, TFAA, TPr, TS, total chlorophyll contents, osmoprotectant (GB, anthocyanin, TPC, and flavonoids), antioxidants (APX, SOD, POD, and CAT), and yield components (number of branches per plant, thousand seed weight, seed, and biological yields were significantly improved by foliar Se + priming Se in both crops under drought stress. Moreover, this treatment was also helpful in boosting yield attributes under irrigated (non-stress) conditions. Camelina genotypes responded better to Se application as seed priming and foliar spray than canola for both years. It has concluded that Se application (either foliar or priming) can potentially alleviate adverse effects of drought stress in camelina and canola by eliciting various physio-biochemicals attributes under drought stress. Furthermore, Se application was also helpful for crop health under irrigated condition. 相似文献
70.
As a first step towards computing instanton-generated superpotentials in heterotic standard model vacua, we determine the Gromov–Witten invariants for a Calabi–Yau threefold with fundamental group π1(X)=Z3×Z3. We find that the curves fall into homology classes in H2(X,Z)=Z3⊕(Z3⊕Z3). The unexpected appearance of the finite torsion subgroup in the homology group complicates our analysis. However, we succeed in computing the complete genus-0 prepotential. Expanding it as a power series, the number of instantons in any integral homology class can be read off. This is the first explicit calculation of the Gromov–Witten invariants of homology classes with torsion. We find that some curve classes contain only a single instanton. This ensures that the contribution to the superpotential from each such instanton cannot cancel. 相似文献