Search results for "Alate"
showing 10 items of 695 documents
Synthesis and spectral studies ofN-2-pyridinylcarbonyl-2-pyridinecarxoximidate copper(II) complexes
1987
Dimeric and polymeric copper(II) complexes containing BPCA (N-2-pyridinylcarbonyl-2-pyridinecarboximidate), having general formulae Cu(BPCA)X·nH2O (X=Cl, Br, NCS, NCO, N3, or CN) and Cu2(BPCA)2-X·nH2O [X=oxalate anion (OX), chloranilate anion (CA) or the dianion of 2,5-dihydroxy-1,4-benzoquinone (DHBQ)] have been synthesized by the copper(II)-assisted hydrolysis of 2, 4, 6-tris(2-pyridyl)-1, 3, 5-triazine. Spectroscopic results indicate five-coordinate, approximately square-pyramidal, geometry around the copper(II) ion. Half-field absorption in the ΔMs=±2 region of the X-band e.p.r. powder spectra has been observed for the dimeric species.
Contribution to the knowledge of North-American species Hyperomyzus subgenus Neonasonovia (Aphididae, Aphidinae, Macrosiphini)
2017
American specimens of the Hyperomyzus subgenus Neonasonovia conserved in the collections of the Museum national d’Histoire naturelle (Paris, France) and the Natural History Museum (London, United Kingdom), have been studied. Data to complement previous descriptions of apterous and alate viviparous females of H. nabali and of apterous viviparae of H. nigricornis, H. inflatus, H. niger and H. pullatus , are presented. Apterous and alate virginogeniae females of H. nigricornis, alate viviparous females of H. inflatus, H. niger and H. pullatus, plus oviparous females of H. nabali , are described for the first time. The morphological and biological variability of H. pullatus is discussed. An ide…
Intercalation of [M(ox)3]3− (M=Cr, Rh) complexes into NiIIFeIII-LDH
2010
Abstract Layered Double Hydroxides (LDH) containing paramagnetic NiII and FeIII ions in the hydroxide layers and chromium or rhodium oxalate complexes at the interlayer space were prepared by ion exchange from a NiFe-LDH precursor with sebacate anions between the hydroxide layers. The precursor was synthesized by coprecipitation at controlled pH in order to avoid the formation of solid phases different from LDH. Magnetic studies demonstrated that both LDHs, NiFe–Cr(ox)3 and NiFe–Rh(ox)3, exhibited a behaviour similar to the precursor. Nevertheless, the substitution of intercalated sebacate anions with oxalate complexes compresses the LDH basal spacing, increasing the intensity of dipolar in…
Comparative study of upper lip frenectomy with the CO2 laser versus the Er, Cr:YSGG laser
2012
Objectives: To compare upper lip frenulum reinsertion, bleeding, surgical time and surgical wound healing in frenectomies performed with the CO2 laser versus the Er, Cr:YSGG laser. Study design: A prospective study was carried out on 50 randomized pediatric patients who underwent rhomboidal resection of the upper lip frenulum with either the CO2 laser or the Er,Cr:YSGG laser. Twenty-five patients were assigned to each laser system. All patients were examined at 7, 14, 21 days and 4 months after the operation in order to assess the surgical wound healing. Results: Insertion of the frenulum, which was preoperatively located between the upper central incisors, migrated to the mucogingival junc…
Malic Enzyme and Malolactic Enzyme Pathways Are Functionally Linked but Independently Regulated in Lactobacillus casei BL23
2013
ABSTRACT Lactobacillus casei is the only lactic acid bacterium in which two pathways for l -malate degradation have been described: the malolactic enzyme (MLE) and the malic enzyme (ME) pathways. Whereas the ME pathway enables L. casei to grow on l -malate, MLE does not support growth. The mle gene cluster consists of three genes encoding MLE ( mleS ), the putative l -malate transporter MleT, and the putative regulator MleR. The mae gene cluster consists of four genes encoding ME ( maeE ), the putative transporter MaeP, and the two-component system MaeKR. Since both pathways compete for the same substrate, we sought to determine whether they are coordinately regulated and their role in l -m…
Polyoxometalates in Langmuir–Blodgett films: toward new magnetic materials
1998
Abstract Polyoxometalates having various structures and properties can be organized by the Langmuir–Blodgett (LB) technique. The adsorption of such polyanions along a positively charged monolayer of DODA (dimethyldioctadecylammonium) induces large changes in the compression isotherm and enables the transfer of the Langmuir film onto solid substrate. X-ray diffraction and infrared dichroism experiments demonstrate that the polyoxometalates are organized in monolayers within the LB films. Furthermore, these magnetic multilayers were characterized by their paramagnetic susceptibility measured by a SQUID magnetometer.
Polyoxometalate Monolayers in Langmuir-Blodgett Films
2005
Langmuir and Langmuir-Blodgett (LB) films of a variety of polyoxometalates of different shapes, sizes, and charges were prepared by taking advantage of the adsorption properties of these polyanions on a positively charged monolayer of an organic surfactant spread on water. Three different aspects were investigated. 1) The electrochemical and electrochromic properties of LB films containing the easily reducible polyoxoanion [P2Mo18O62]6-. Absorbance changes of these LB films deposited onto an ITO substrate have been induced by repeated switching of the applied potential. These changes are due to the formation of the colored reduced forms of the polyanion. Coloration and bleaching of the LB f…
Incorporation of CrIII into a Keggin Polyoxometalate as a Chemical Strategy to Stabilize a Labile {CrIIIO4} Tetrahedral Conformation and Promote Unat…
2020
Polyoxometalates (POMs) provide rigid and highly symmetric coordination sites and can be used as a strategy for the stabilization of magnetic ions. Herein, we report a new member of the Keggin archetype, the Cr-centered Keggin anion [α-CrW12O40]5– (CrW12), with the unusual tetrahedral coordination of CrIII reported for the first time in POMs conferring unattended magnetic properties. POM chemistry has recently presented excellent examples of single-molecule and single-ion magnets (SMMs and SIMs) as well as molecular spin qubits; however, the majority of POM-based SIMs reported to date contain lanthanoid ions. CrW12, as the first example of a chromium(III) SIM, exhibits slow relaxation of ma…
Mononuclear lanthanide single molecule magnets based on the polyoxometalates [Ln(W5O18)2]9- and [Ln(beta2-SiW11O39)2]13- (Ln(III) = Tb, Dy, Ho, Er, T…
2009
The first two families of polyoxometalate-based single-molecule magnets (SMMs) are reported here. Compounds of the general formula [Ln(W(5)O(18))(2)](9-) (Ln(III) = Tb, Dy, Ho, and Er) and [Ln(SiW(11)O(39))(2)](13-) (Ln(III) = Tb, Dy, Ho, Er, Tm, and Yb) have been magnetically characterized with static and dynamic measurements. Slow relaxation of the magnetization, typically associated with SMM-like behavior, was observed for [Ln(W(5)O(18))(2)](9-) (Ln(III) = Ho and Er) and [Ln(SiW(11)O(39))(2)](13-) (Ln(III) = Dy, Ho, Er, and Yb). Among them, only the [Er(W(5)O(18))(2)](9-) derivative exhibited such a behavior above 2 K with an energy barrier for the reversal of the magnetization of 55 K. …
Co-crystallization of Keggin type polyoxometalates [HL]3[PW12O40] and [Ln(DMF)8][PW12O40] (Ln=La, Dy, Yb) (L=N-(2-hydroxyphenyl)-3-methoxy-salicylide…
2016
Abstract Four new Keggin type polyoxometalate clusters [HL]3[PW12O40]·5MeOH (1) and [Ln(DMF)8][PW12O40] {Ln = La (2), Dy (3), Yb (4)} (L = N-(2-hydroxyphenyl)-3-methoxy-salicylideneamine) have been synthesized. Co-crystallization of complex 1 with each of the three complexes 2–4 takes place when the Schiff base ligand is treated with hydrated phosphotungstic acid, H3[PW12O40]·xH2O, hydrated lanthanide nitrate, Ln(NO3)3·6H2O in the presence of Ni(NO3)2·6H2O. The Schiff base ligand is protonated in complex 1 and thus it is neutralizing the charge of the polyoxotungstate anion, [PW12O40]3−. A dimethylformamide (DMF) coordinated trivalent lanthanide ion balances the negative charge of the polyo…