scholarly journals Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides

2015 ◽  
Vol 68 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Gisele Tavares Marques ◽  
Marcondes Lima da Costa ◽  
Érico Rodrigues Gomes
Keyword(s):  
Chemical Composition ◽  
Aqueous Solutions ◽  
High Stability ◽  
Hydrothermal Fluids ◽  
Northeastern Brazil ◽  
Quartz Crystals ◽  
Hydrothermal Processes ◽  
Hydrothermal Environment

Orange opals from Buriti dos Montes (Piauí, northeastern Brazil) have gemological properties that favor their use as jewelry; these characteristics include their colors, transparency, relatively high stability and hardness. The exotic content of solid inclusions provides greater beauty to the opals of this region. These opals originated from hydrothermal processes and are found mainly as veinlets and veins in the sandstones of the Serra Grande Group, sectioned by diabase dikes and sills of the Sardinha Formation. Solid inclusions, such as bubbles, botryoidal aggregates, dendrites, and nodules, among others, consist mainly of kaolinite, hematite/goethite and quartz and influence the chemical composition of opals. Intense zoning of quartz crystals and high values of Ba and Fe suggest that opal deposits were formed in a hydrothermal environment. Diabase dykes could have been responsible for heating the hydrothermal fluids. Sandstones, rich in aqueous solutions, also contributed to the available silica for the saturation of these solutions, and fractures enabled the migration and entrapment of hydrothermal fluids, resulting in the mineralized veins.

First approach on transfection ability of novel amphiphilic water soluble degradable poly(ε-caprolactone)-g-poly(Llysine) copolymers

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Benjamin Nottelet ◽  
Julie Vendrell ◽  
Jean Coudane ◽  
Michel Vert
Keyword(s):  
Chemical Composition ◽  
Aqueous Solutions ◽  
Graft Copolymers ◽  
Water Soluble ◽  
Dna Transfection ◽  
Mcf 7

AbstractThe potential of novel amphiphilic water soluble and degradable poly(ε- caprolactone)-g-poly(L-lysine) as carriers for DNA transfection has been investigated. Two graft copolymers having the same proportion of lysine units but different structures have been synthesized following two grafting techniques. The chemical composition of these copolymers, their expected architectures and their behaviour in aqueous solutions have been studied. The benefits resulting from the use of these degradable polycationic structures as well as their ability to form polyplexes are discussed. Finally, preliminary transfection assays of MCF-7 cells by pRL-TK plasmid using poly(ε-caprolactone)-g-poly(L-lysine) copolymers as carriers are reported.

scholarly journals Recovery of gangliosides from aqueous solutions on styrene-divinylbenzene copolymer columns

2002 ◽  
Vol 43 (8) ◽  
pp. 1335-1340 ◽  
Author(s):  
Iuliana Popa ◽  
Cristina Vlad ◽  
Jacques Bodennec ◽  
Jacques Portoukalian
Keyword(s):  
Aqueous Solutions ◽  
Silica Gel ◽  
Salt Concentration ◽  
High Stability ◽  
Solid Phase ◽  
General Procedure ◽  
Optimal Conditions ◽  
Alkaline Conditions ◽  
Styrene Divinylbenzene ◽  
Multiple Cycles

An investigation was made using a styrene-divinylbenzene copolymer as a solid phase sorbent to recover gangliosides from aqueous solutions. A comparison with octadecyl-bonded (C18) silica gel showed that the general procedure used to purify gangliosides on C18 silica gel could be used with the copolymer. The yield of gangliosides depended on various parameters such as the composition of the conditioning solution, the salt concentration of the loading solution, and the amount of applied gangliosides per gram of copolymer. In optimal conditions, the recovery of gangliosides and other lipids present in the upper phases of partition was higher than 95%. Using radiolabeled gangliosides, it was found that gangliosides present in serum-containing medium could also be quantitatively recovered on copolymer, provided the medium was diluted with an equal volume of methanol prior to its application onto the column.The major advantage of the copolymer is its high stability in acidic or alkaline conditions that allows multiple cycles of cleaning and reconditioning of the sorbent without alteration of its chromatographic properties.

scholarly journals Electrochemically-derived graphene oxide membranes with high stability and superior ionic sieving

2019 ◽  
Vol 55 (28) ◽  
pp. 4075-4078 ◽  
Author(s):  
Pei Yu ◽  
Zhiyuan Xiong ◽  
Hualin Zhan ◽  
Ke Xie ◽  
Yu Lin Zhong ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Aqueous Solutions ◽  
High Stability ◽  
Oxide Membranes ◽  
Graphene Oxide Membranes

Crosslinker-free electrochemically-derived graphene oxide membranes are found to be extraordinarily stable in aqueous solutions and exhibit superior ionic sieving performance.

Governing metal–organic frameworks towards high stability

2016 ◽  
Vol 52 (55) ◽  
pp. 8501-8513 ◽  
Author(s):  
Na Li ◽  
Jian Xu ◽  
Rui Feng ◽  
Tong-Liang Hu ◽  
Xian-He Bu
Keyword(s):  
Chemical Composition ◽  
High Stability ◽  
Metal Organic Frameworks ◽  
Crucial Issue ◽  
Practical Applications ◽  
Metal Organic ◽  
The Stability

Stability of MOFs is a crucial issue for their practical applications, which might be improved by varying their chemical composition and/or structurally tuning them. Several strategies for enhancing the stability of MOFs were provided.

scholarly journals Chemical Composition and Ruminal Degradability of Spineless Cactus Grown in Northeastern Brazil

2009 ◽  
Vol 62 (3) ◽  
pp. 297-301 ◽  
Author(s):  
Ângela M.V. Batista ◽  
Agenor C. Ribeironeto ◽  
Rodrigo B. Lucena ◽  
Djalma C. Santos ◽  
JosèB. Dubeux ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Northeastern Brazil ◽  
Ruminal Degradability

Biosorption of heavy metal ions from aqueous solutions by short hemp fibers: Effect of chemical composition

2009 ◽  
Vol 164 (1) ◽  
pp. 146-153 ◽  
Author(s):  
Biljana Pejic ◽  
Marija Vukcevic ◽  
Mirjana Kostic ◽  
Petar Skundric
Keyword(s):  
Heavy Metal ◽  
Chemical Composition ◽  
Aqueous Solutions ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Hemp Fibers

scholarly journals Chemical composition, botanical evaluation and screening of radical scavenging activity of collected pollen by the stingless bees Melipona rufiventris (Uruçu-amarela)

2009 ◽  
Vol 81 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Tania M.S. Silva ◽  
Celso A. Camara ◽  
Antonio C.S. Lins ◽  
Maria de Fátima Agra ◽  
Eva M.S. Silva ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Stingless Bees ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Northeastern Brazil ◽  
Scavenging Activity ◽  
Dominant Type ◽  
Etoac Extract ◽  
Pollen Loads ◽  
Pollen Types

Stingless bees in Brazil are indigenous and found all over the country. Bee pollen is used for its nutritional value in the human diet. It is made up of natural flower pollen mixed with nectar and bee secretions. In order to evaluate the chemical composition, free radical scavenging activity, and botanical origin, sample of pollen loads from stingless bee, Melipona rufiventris (Uruçu amarela) was studied. The EtOAc extract of pollen of Melipona rufiventris yielded the following compounds: p-hydroxycinnamic acid, dihydroquercetin, isorhamnetin, isorhamnetin3-O-(6"-O-E-p-coumaroyl)-β-D-glucopyranoside, luteolin, and quercetin. This is the first report of the isolation of isorhamnetin3-O-(6"O-E-p-coumaroyl)β-D-glucopyranoside from pollen. The free radicalscavenging activities of different solvent extracts of pollen were determined using DPPH assay. This activity decreases in the order: EtOAc>EtOH>Hexane extract. It appears that the EtOAc extract of the pollen is a good scavenger of active oxygen species. The botanical evaluation of pollen loads showed the composition by two pollen types, with the dominant type (97.3%) being Scopariadulcis (L.) (Scrophulariaceae) and the minor one Senna obtusifolia (L.) Irwin & Barneby (Fabaceae). This suggests a specific foraging behavior in Melipona rufiventris bees, even in an environment with such a rich botanical diversity as the Northeastern Brazil.

Effect of Borohydride Addition Rate on Chemically Prepared Amorphous Fe–B Particles

1990 ◽  
Vol 206 ◽  
Author(s):  
C. Bender Koch ◽  
S. Mørup ◽  
S. Linderoth
Keyword(s):  
Chemical Composition ◽  
Aqueous Solutions ◽  
Hyperfine Field ◽  
Isomer Shift ◽  
Amorphous Alloys ◽  
Chemical Reduction ◽  
Magnetic Hyperfine Field ◽  
Hyperfine Parameters ◽  
Addition Rate ◽  
Identical Composition

ABSTRACTAmorphous Fe-B alloys can be prepared by reacting aqueous solutions of Fe salts and NaBH4. In this work the effect of the addition rate of the NaBH4 solution to the FeSO4 solution on the precipitate is investigated. The chemical composition of the amorphous alloys formed varies between Fe79B21 and Fe68B32. The hyperfine parameters of the alloys, derived from Mössbauer spectra, show a decrease from 29 to 25 T of the magnetic hyperfine field and an increase from 0.19 to 0.28 mms−1 of the isomer shift with increasing NaBH4 addition rate. The results suggest that alloys with different structures but identical composition may be produced by chemical reduction.

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