Search results for "Onium"
showing 10 items of 2091 documents
Eradication of enterococci biofilms by lactic acid alone and combined with chlorhexidine and cetrimide
2012
Objective: The antimicrobial activity of lactic acid (LA) alone or in combination with chlorhexidine (CHX) and cetrimide (CTR) against three Enterococcus faecalis strains, E. faecalis ATCC 29212, E. faecalis EF-D1 and E. faecalis U-1765, one Enterococcus durans strain and one dual-species biofilm was investigated. Study Design: The irrigating solutions tested were 20%, 15%, 10%, 5% and 2.5% LA, alone and in combination with 2% CHX and with 0.2% CTR. The biofilms were grown in the MBECTM high-throughput device for 24 hours and exposed to the solutions for 30 seconds and 1 minute. “Eradication” was defined as 100% bacterial kill. Results: Twenty percent LA eradicated all enterococci biofilms …
Speciation of chitosan with low and high molecular weight carboxylates in aqueous solution
2009
Quantitative data on the speciation of chitosan (310 kDa) with low and high molecular weight carboxylates in aqueous solution are reported. The following carboxylic ligands were considered: monocarboxylate (butyrate); dicarboxylates (malonate, succinate, azelate); tricarboxylate (1,2,3-propa- netricarboxylate); tetracarboxylate (1,2,3,4-butanetetracarboxylate); polyacrylates (2.0 and 20 kDa); polymethacrylate (5.4 kDa). The investigation was performed by potentiometry at t 1/4 25 C, at low ionic strength (without addition of supporting electrolyte) and at I 1/4 0:15 mol L 1 (NaCl). For all the systems the formation of (chitosan)LHi species was found (L 1/4 carboxylic ligand; i 1/4 1 to 4 de…
Role of hydrophobic forces in bilayer adhesion and fusion.
1992
With the aim of gaining more insight into the forces and molecular mechanisms associated with bilayer adhesion and fusion, the surface forces apparatus (SFA) was used for measuring the forces and deformations of interacting supported lipid bilayers. Concerning adhesion, we find that the adhesion between two bilayers can be progressively increased by up to two orders of magnitude if they are stressed to expose more hydrophobic groups. Concerning fusion, we find that the most important force leading to direct fusion is the hydrophobic attraction acting between the (exposed) hydrophobic interiors of bilayers; however, the occurrence of fusion is not simply related to the strength of the attrac…
Decay properties of neutron-rich niobium isotopes
1976
The decay of neutron-rich niobium isotopes in the mass region $A\ensuremath{\simeq}100$ has been investigated by $\ensuremath{\gamma}$-ray singles and $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidence measurements. The isotopes were produced by thermal-neutron induced fission of $^{235}\mathrm{U}$, $^{239}\mathrm{Pu}$, and $^{249}\mathrm{Cf}$, and niobium was separated from fission-product mixtures with an automated chemical procedure. Isomerism was found in the even-mass niobium isotopes with the following half-lives: 1.5 and 3.1 sec for $^{100}\mathrm{Nb}$, 1.3 and 4.3 sec for $^{102}\mathrm{Nb}$, and 0.8 and 4.8 sec for $^{104}\mathrm{Nb}$. Half-lives and $\ensuremath{\gamma}$ rays…
Mechanical, Kinetic and Morphological Correlations during the Scale Growth of Niobium and Zirconium Oxides
2001
Oxidation of niobium at 700°C and zirconium at 850°C, in air or oxygen pressures from 20 to I 000 hPa, lead to the formation in one case of a stratified Nb 2 O 5 oxide scale and in the other case a more compact ZrO 2 oxide scale. Analyses of the evolutions of phases, crystalline textures and mechanical stresses during oxidation are determined by X-ray diffraction techniques. Interactions between chemical processes, crystalline building and mechanical processes constitute together the driving force of the reaction and can explain the differences in morphologies of oxide scales.
Caries arresting effect of silver diamine fluoride on dentine carious lesion with S. mutans and L. acidophilus dual-species cariogenic biofilm
2013
OBJECTIVES: This in vitro study investigated the effects of silver diamine fluoride (SDF) on dentine carious lesion with cariogenic biofilm. STUDY DESIGN: Thirty human dentine blocks were inoculated with Streptococcus mutans and Lactobacillus acidophilus dual-species biofilm to create carious lesion. They were equally divided into test and control group to receive topical application of SDF and water. After incubation anaerobically using micro-well plate at 37oC for 7 days, the biofilms were evaluated for kinetics, morphology and viability by colony forming units (CFU), scanning electron microscopy (SEM), and confocal microscopy (CLSM), respectively. The carious lesion underwent crystal cha…
Impact of uncharged and charged stabilizers on in vitro drug performances of clarithromycin nanocrystals
2018
The purpose of this study was to evaluate the effect of charge on the in vitro drug performances of clarithromycin nanocrystals. To prepare different charges of nanocrystals, media milling was employed with the use of different stabilizing systems. The uncharged nanocrystals were prepared from poloxamer 407. The negatively and positively charged nanocrystals were stabilized using a combination of poloxamer 407 with sodium lauryl sulfate (SLS) and cetyltrimethylammonium bromide (CTAB), respectively. After production, the particle size of the negatively and positively charged nanocrystals was smaller than that of the uncharged one. The similar particle size of variously charged clarithromycin…
The role of molybdenum in Mo-doped V–Mg–O catalysts during the oxidative dehydrogenation of n-butane
1999
Abstract A detailed study on the influence of the addition of molybdenum ions on the catalytic behaviour of a selective vanadium–magnesium mixed oxide catalyst in the oxidation of n-butane has been performed. The catalysts have been prepared by impregnation of a calcined V–Mg–O mixed oxides (23.8 wt% of V2O5) with an aqueous solution of ammonium heptamolybdate, and then calcined, and further characterised by several physico-chemical techniques, i.e. SBET, XRD, FTIR, FT-Raman, XPS, H2-TPR. MgMoO4, in addition to Mg3V2O8 and MgO, have been detected in all the Mo-doped samples. The incorporation of molybdenum modifies not only the number of V5+-species on the catalyst surface and the reducibil…
Unique direct synthesis of cyanide-bridged Fe2Cu2 molecular squares by destruction of sodium nitroprusside
2009
Abstract The one-pot reaction of copper powder, sodium nitroprusside, ammonium thiocyanate and 2,2′-bipyridine (bpy) in acetonitrile solution at ambient conditions of air and water yields the novel heterometallic [Fe2Cu2(bpy)6(μ-CN)4(NCS)2]2[Fe(CN)5(NO)](NCS)2·5H2O complex 1, which has been structurally and magnetically characterized. The most prominent feature of this complex is the unique tetranuclear Fe 2 II Cu 2 II squares comprised [Cu(bpy)NCS]+ and [Fe(bpy)2]2+ corners with CN edges. The Cu⋯Cu and Fe⋯Fe separations are ∼6.72 and ∼7.73 A, respectively. The variable-temperature magnetic susceptibility study revealed that a very weak antiferromagnetic coupling is active between Cu(II) ce…
Separation of chelating agents as copper complexes by capillary zone electrophoresis using quaternary ammonium bromides as additives in N-methylforma…
2006
This study presents the use of quaternary ammonium bromides as additives in N-methylformamide (NMF) for the separation and quantification of chelating agents as copper complexes by capillary zone electrophoresis (CZE). The new quaternary ammonium bromides were synthesized in our laboratory and used for the first time for CZE applications performed in NMF media. The methods were developed and optimized for determination of six chelating agents (trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), nitrilotriacetic acid (NTA) and trieth…