Ionic Crystals
Mostrando 1-12 de 40 artigos, teses e dissertações.
-
1. An Alternative Description for the Electronegativity Difference in Binary Ionic Solids
We are introducing an alternative analytical expression to the electronegativity difference (∆χ) as a function of the charge ge, g is the charge factor, the fraction of the electronic charge devoted to the bond and e the elementary charge, the packing factor (p) and the effective atomic number (Zeff) of binary ionic solids, by using the very basic Coulomb
J. Braz. Chem. Soc.. Publicado em: 2021-02
-
2. Solid-state Morphology Evolution of Sodium Neutralized Poly(ethylene-ran-methacrylic acid) Ionomer Under Dry and Wet Thermal Annealing
The DSC low temperature endothermic peak shown by sodium neutralized poly(ethylene-random-methacrylic acid) (E/MAA-Na+) ionomers in the range of 50-70 ºC is attributed to the endothermic reordering of polyethylene chain segments belonging to two populations of quasi-crystals set from melt, initially showing no birefringence. Dry or wet thermal annealing imp
Mat. Res.. Publicado em: 08/08/2019
-
3. Identification of Heavy Metals in Crystals of Sand and Silt Fractions of Soils by Scanning Electron Microscopy (SEM EDS/WD-EPMA)
ABSTRACT Studies of heavy metals are concentrate on clay fractions, but coarser fractions of the soil can constitute significant sources of structural forms of heavy metals. The aim of this study was to evaluate the occurrence of heavy metals in the structure of minerals of the sand and silt fractions of soils from three different parent materials (metamorph
Rev. Bras. Ciênc. Solo. Publicado em: 08/03/2018
-
4. Cellulose Oxidation and the Use of Carboxyl Cellulose Metal Complexes in Heterogeneous Catalytic Systems to Promote Suzuki-Miyaura Coupling and C-O Bond Formation Reaction
This work shows the modification of microcrystalline cellulose by the selective oxidation of primary hydroxyl groups to carboxylate groups by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated system and its application as a heterogeneous ligand by ionic exchange with catalytic metals ions such as palladium, nickel and copper. Afterwards is desc
J. Braz. Chem. Soc.. Publicado em: 2017-11
-
5. Electrical Conductivity in the KDP, ADP, and K1-x(NH4)xH2PO4 Crystals
Impedance Spectroscopy was performed to examine the electrical conductivity on KH2PO4 KDP, (NH4)H2PO4 ADP and K1-x(NH4)xH2PO4 (x = 0.076, 0.118, 0.357, 0.857, 0.942) crystals with increasing temperature. They were grown by solvent evaporation method. Zview simulation software was used to theoretically fit electrical conductivity results as a function of freq
Mat. Res.. Publicado em: 23/02/2017
-
6. New Zr-based glass-forming alloys containing Gd and Sm
The effect of minor additions of Gd and Sm on the glass-forming ability (GFA) of Cu-Zr-Al alloys is investigated here. The rationale for these additions is the fact that the atomic size distribution can increase GFA by changing the topology of the alloy as a function of cluster stability, which is tied to the electronegativity and ionic and covalent nature o
Mat. Res.. Publicado em: 09/08/2012
-
7. Efeito crioprotetor de lactose e glicose em cÃlulas fÃngicas imobilizadas em alginato de sÃdio como mÃtodo de preservaÃÃo de culturas. / Cryoprotectant effect of lactose and glucose yeast cells immobilized in calcium alginate as a method for preservation of cultures
Cryopreservation is the method of choice in many banks of microorganisms because it leads to a situation of metabolic dormancy and consequently cultures are stable for long periods. By reducing the temperature may however be formed of ice crystals which tend to cause cell damage to cell damage in turn can be avoided by vitrification process which takes place
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 26/08/2011
-
8. Electrospinning and characterization of polyamide 66 nanofibers with different molecular weights
Polyamide 66 (PA66) nanofibers of different molecular weights were obtained by electrospinning of formic acid solutions. An ionic salt, NaCl, was also added to the solutions to increase the conductivity. PA66 concentrations between 15-17 wt.(%)/v and electrical fields between 2.0 and 2.5 kV/cm were the best conditions to produce the smallest nanofibers; howe
Materials Research. Publicado em: 2009-06
-
9. Preparação e caracterização estrutural e elétrica de cristais mistos de K1-x(NH4)xH2PO4
The preparation and structural and electrical characterization of KH2PO4 (KDP), (NH4)H2PO4 (ADP) and K1-x(NH4)xH2PO4 (KADPx) mixed crystals grown by the method of solvent evaporation at 40 C and with x = 0, 0.076, 0.118, 0.357, 0.857, 0.942, 1.0 was carried out. Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) was performed in order to deter
Publicado em: 2009
-
10. Propiedades de adsorción en zeolitas con anillos de 8 miembros: I. microporosidad y superficie externa
In this work synthesis of LTA zeolite and its ionic exchange with inorganic chemical salts were studied. Likewise experimental results are reported about LTA zeolite external surface area by using the t-plot method. Physicochemical characterization of this zeolite was carried out by XRD, SEM, IR and nitrogen adsorption (76 K) techniques. LTA zeolite was synt
Matéria (Rio de Janeiro). Publicado em: 2009
-
11. Phase transitions in Na2ThF6 single crystals using Diferential Scanning Calorimetry (DSC) / TRANSIÇÕES DE FASE EM MONOCRISTAIS DE Na2ThF6
In this work we have studied possible phase transitions in Na2ThF6 single crystals using Dierential Scanning Calorimetry (DSC), Raman and Impedance spectroscopies and static simulations. The polarized Raman spectroscopy measurements were performed in the temperature range from 10 K up to 770 K and DSC measurements from 298 K up to 823 K. The results indicate
Publicado em: 2008
-
12. Development and evaluation of the stability of O/W emulsion with liquid crystals added of xantine to treatment of the gynoid hydrolipodystrophy (cellulite). / Desenvolvimento e avaliação da estabilidade de emulsões O/A com cristais líquidos acrescidas de xantina para tratamento da hidrolipodistrofia ginóide (celulite)
Atualmente, decorrente da cultura estética onde há o culto aos corpos esbeltos com aparência saudável e pele lisa, macia e viçosa, a hidrolipodistrofia ginóide, conhecida como celulite, tem sido um dos desafios para os dermatologistas e cirurgiões plásticos. Assim, temse testado diferentes formas de tratamentos entre as quais estão aplicações de c
Publicado em: 2006