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171.
The dehydration of MgSeO4. 6 H2O has been studied using an X-ray powder diffraction method at elevated temperatures. Five different solid phases have been identified in the temperature interval of 20–450 °C: MgSeO4. 6 H2O; MgSeO4. 5 H2O (with a small amount of MgSeO4. 4 H2O), MgSeO4. 2 H2O, amorphous MgSeO4 and crystalline MgSeO4. MgSeO4. 5 H2O crystallizes in the triclinic system with the lattice parameters: a = 6.403(2) Å, b = 10.576(5) Å, c = 6.196(3) Å, α = 98.63(2)°, β = 110.36(2)°, γ = 75.25(3)°, SG P1 . MgSeO4. 2 H2O forms orthorhombic crystals with lattice parameters: a = 10.304(1) Å, b = 10.351(9) Å, c = 9.138(9) Å. The crystalline anhydrous magnesium selenate crystallizes in the orthorhombic system with the lattice parameters: a = 4.925(2) Å, b = 9.026(5) Å, c = 6.816(6) Å. Additionally MgSeO4. 4 H2O has been prepared and studied roentgenographically: monoclinic system with the lattice constants: a = 6.064(4) Å, b = 13.773(7) Å, c = 8.062(6) Å, β = 91.82(7)°, SG P21/n. According to expectation the magnesium selenate hydrates are isomorphous with the corresponding magnesium sulphate hydrates. 相似文献
172.
Violeta Jevtovi Haneen Hamoud Salma Al-Zahrani Khalaf Alenezi Salman Latif Tahani Alanazi Fahad Abdulaziz Duan Dimi 《Molecules (Basel, Switzerland)》2022,27(15)
New complex Co(III) with ligand Pyridoxal-S-methyl-isothiosemicarbazone, (PLITSC) was synthesized. X-ray analysis showed the bis-ligand octahedral structure of the cobalt complex [Co(PLITSC-H)2]BrNO3·CH3OH (compound 1). The intermolecular interactions governing the crystal structure were described by the Hirsfeld surface analysis. The structure of compound 1 and the corresponding Zn complex (([Zn(PLTSC)(H2O)2]SO4·H2O)) were optimized at the B3LYP/6–31 + G (d,p)/LanL2DZ level of theory, and the applicability was assessed by comparison with the crystallographic structure. The natural bond orbital analysis was used for the discussion on the stability of formed compounds. The antibacterial activity of obtained complexes towards S. aureus and E. coli was determined, along with the effect of compound 1 on the formation of free radical species. Activity of compound 1 towards the removal of methylene blue was also investigated. The voltammograms of these compounds showed the reduction of metal ions, as well as the catalyzed reduction of CO2 in acidic media. 相似文献
173.
Tinca Buruiana Violeta Melinte George Costin Emil C. Buruiana 《Journal of polymer science. Part A, Polymer chemistry》2011,49(12):2615-2626
Three novel liquid crystalline methacrylates have been synthesized and characterized to be tested as comonomers in light‐curing dental resin‐based composites. The selected formulations consist of an alkylammonium or cholesteryl urethane methacrylate and 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxypropyl)phenyl]propane (BisGMA) or a BisGMA derivate modified with urethane methacrylate groups, further diluted with triethyleneglycol dimethacrylate (TEGDMA) and reinforced with 70% filler (zirconium silicate nanopowder, silanized filler). This study addresses the relationships between the LC monomer structure, photopolymerization rates (by differential scanning photo calorimetry), and specific properties of the dental resin composites (volumetric shrinkage, water sorption, water solubility, and hydrophobicity). The investigation of LC properties by differential scanning calorimetry and polarizing microscopy indicated that the LC mesophase is stable to room temperature (cationic monomers) or at 40 °C (cholesteryl methacrylate). It was found that the polymerization rate for LC urethane methacrylates used in combination with BisGMA/TEGDMA (0.122–0.136 s?1) is higher than that of the mesogenic monomers alone (0.085–0.107 s?1). The structures of the urethane monomers and, consequently, the viscosity of the comonomer mixture influence both the rate and the degree of conversion (44.8–67.5 %) of the photopolymerization process. Polymerization shrinkage measured by pycnometry showed lower values for LC monomers (3.25–3.43 vol %) comparatively with the monomer mixture (5.19–6.65 vol %). Preliminarily, the effect of ammonium groups from two resin composites incorporating alkylammonium structures (4.5 wt %) was tested on Streptococcus mutans, and distinct zone of inhibition was observed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
174.
Violeta Kourbeli Eleni Chontzopoulou Kalliopi Moschovou Dimitrios Pavlos Thomas Mavromoustakos Ioannis P. Papanastasiou 《Molecules (Basel, Switzerland)》2021,26(15)
The protozoan diseases Human African Trypanosomiasis (HAT), Chagas disease (CD), and leishmaniases span worldwide and therefore their impact is a universal concern. The present regimen against kinetoplastid protozoan infections is poor and insufficient. Target-based design expands the horizon of drug design and development and offers novel chemical entities and potential drug candidates to the therapeutic arsenal against the aforementioned neglected diseases. In this review, we report the most promising targets of the main kinetoplastid parasites, as well as their corresponding inhibitors. This overview is part of the Special Issue, entitled “Advances of Medicinal Chemistry against Kinetoplastid Protozoa (Trypanosoma brucei, Trypanosoma cruzi and Leishmania spp.) Infections: Drug Design, Synthesis and Pharmacology”. 相似文献
175.
Eleftherios Lavdas Panayiotis Mavroidis Spiros Kostopoulos Dimitrios Glotsos Violeta Roka Theofilos Topalzikis Athanasios Bakas Georgia Oikonomou Nikos Papanikolaou Georgios Batsikas Ioannis Kaffes Dimitrios Kechagias 《Magnetic resonance imaging》2013
The purpose of this study is to compare two types of sequences in brain magnetic resonance (MR) examinations of uncooperative and cooperative patients. For each group of patients, the pairs of sequences that were compared were two T2-weighted (T2-W) fluid attenuated inversion recovery sequences with different k-space trajectories (conventional Cartesian and BLADE) and two T2-TSE weighted with different k-space trajectories (conventional Cartesian and BLADE). Twenty-three consecutive uncooperative patients and 44 cooperative patients, who routinely underwent brain MR imaging examination, participated in the study. Both qualitative and quantitative analyses were performed based on the signal-to-noise ratio, contrast-to-noise ratio (CNR), and relative contrast (ReCon) measures of normal anatomic structures. The qualitative analysis was performed by experienced radiologists. Also, the presence of motion, other (e.g., Gibbs, susceptibility artifacts, phase encoding from vessels) artifacts and pulsatile flow artifacts was evaluated. 相似文献
176.
177.
A new 5′-O-AZT prodrug was synthesized by conjugating 3′-azido-2′,3′-dideoxythymidine (AZT) with poly(oxyethylene H-phosphonate) at room temperature under Atherton-Todd reaction conditions. The acute toxicity of poly(5′-O-AZT-oxyethylene phosphate) was reduced significantly in comparison with non-immobilized AZT. 相似文献
178.
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180.
In the present work, we have synthesized and characterized magnetic nanoparticles of maghemite γ-Fe2O3 to study their structural and magnetic properties. For the preparation, magnetite precursor, were oxidized by adjusting the pH = 3.5 at about 80 °C in an acid medium, The mean size of the maghemite particles calculated from the X-ray diffractogram was around 5.7 nm. Mössbauer spectroscopy measurements at room temperature show their superparamagnetic behavior. Furhermore, Mössbauer measurements were carried out at 77 K and 4.2 K in order to find the typical hyperfine fields of the maghemite. Magnetite phase was not found. FC and ZFC magnetization curves measured at 500 Oe indicate a blocking temperature of 105.3 K. The magnetization measurements also show almost zero coercivity at RT. TEM images show nanoparticles with diameter smaller than 10 nm, which are in good agreement with the X-ray pattern and the fitting of the magnetization data. 相似文献