Clay-organic interactions

Lagaly, G.

doi:10.1098/rsta.1984.0031

Cited by 205 publications

(22 citation statements)

References 49 publications

(43 reference statements)

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“…If a geomaterial has the ability to assist desorption and ionization of biomolecules, the actual mechanism may or may not be similar to MALDI or SALDI because biomolecules may be associated with the geomaterial in a variety of ways. Biomolecules can associate with minerals by attaching to mineral surfaces, being incorporated within the aggregate structure of soil or sediment particles (Arnarson and Keil 2001), or being entrained inside of mineral crystal structures (Lagaly 1984). Because of the uncertainty related to the mechanism(s), the general term geomatrix-assisted laser desorption/ionization (GALDI) is applied if a geological material allows a biomolecule to be desorbed and ionized for mass spectrometric analysis.…”

Section: Introductionmentioning

confidence: 99%

Detection of Biosignatures by Geomatrix-Assisted Laser Desorption/Ionization (GALDI) Mass Spectrometry

Yan

Stoner

Kotler

et al. 2007

Geomicrobiology Journal

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Identification of mineral-associated biosignatures is of significance for retrieving biochemical information from geological records here on Earth and for detecting signs of life on other planets, such as Mars. An investigation using laser desorption Fourier transform mass spectrometry was conducted to determine whether geomatrix-assisted laser desorption/ionization (GALDI) can be used to detect amino acids (e.g., histidine, threonine, and cysteine) and small proteins (e.g., gramicidin S) associated with mineral phases and whether the geomatrix impacts detection. Iron oxide (Fe 2 O 3 ) and sodium chloride (NaCl) were investigated as clean chemical analogues of hematite and halite, respectively, which have both been detected on the surface of Mars. Samples were prepared by 2 methods: (1) application of analyte solution to the geomatrix surface with subsequent drying; and (2) physical mixing of analyte and geomatrix. Amino acids incorporated within NaCl by physical mixing yielded a better signal-to-noise ratio than those that were applied to the surface of a NaCl pellet. The composition of the geomatrix had an influence on the detection of biomolecules. Peaks corresponding to the cation-attached biomolecular ions were observed for the NaCl prepared samples. However, no biomolecular ion species were observed in samples using Fe 2 O 3 as geomatrix. Instead, only minor peaks that may correspond to ions derived from fragments of the biomolecules were obtained.

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Section: Introductionmentioning

confidence: 99%

Detection of Biosignatures by Geomatrix-Assisted Laser Desorption/Ionization (GALDI) Mass Spectrometry

Yan

Stoner

Kotler

et al. 2007

Geomicrobiology Journal

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“…The intercalation of low molecular weight organic molecules into the nanogalleries is well known and has been reported in various studies. Lagaly et al 34 also found that the interlayer gaps of dodecylammonium modified montmorillonite increased with the increase in chain length of different alcohols. However, the increase of the gallery gap was not observed when the chain length was less than six carbon atoms.…”

Section: Atr Spectroscopymentioning

confidence: 95%

Preintercalation of an organic accelerator into nanogalleries and preparation of ethylene propylene diene terpolymer rubber–clay nanocomposites

Rooj

Das

Heinrich

2011

Polym J

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A multifunctional additive, bis(diisopropyl) thiophosphoryl diisopropyl disulfide (DIPDIS), was melted in the presence of quaternary ammonium-modified montmorillonite clay and incorporated into an ethylene propylene diene terpolymer (EPDM) rubber matrix as a nanofiller to prepare EPDM rubber nanocomposites. The finer dispersion of the organoclay (OC) in the rubber matrix was observed when the OC was preintercalated by DIPDIS using the propping-open procedure. X-ray diffraction (XRD) results showed that the silicate layers of the OC were successfully preintercalated by the DIPDIS; that is, the basal spacing of clay galleries was expanded from 2.98 to 3.76 nm. Because of the larger interlayer distance, as evidenced by XRD studies, the delamination process was facilitated through the easy intercalation of macromolecular rubber chains, which was reflected in various properties, such as the stress-strain behavior, thermal stability, dynamic mechanical properties and swelling properties. XRD studies and transmission electron microscopy directly supported the effective filler dispersion in the non-polar EPDM rubber matrix. INTRODUCTIONPolymer nanocomposites based on nanoclay have recently generated a great deal of interest as a successful approach to overcome the inadequacy of conventional composites. 1-4 Very recently, advances in rubber-clay nanocomposites have attracted the attention of scientists working in the field of polymer-clay nanocomposites. In addition to higher gas barrier properties and certain improved fireresistance properties, most of the developed rubber-clay nanocomposites exhibit much higher tensile strength than that of the corresponding matrix. Generally, the corresponding ratio is at least two to three times greater. 5,6 However, because of the inorganic nature of the clay minerals, the dispersion by the delamination process of the clay layers is the main problem for the desirable reinforcement of the silicate clay layers. The most established and common ways to overcome this problem are the use of quaternary ammonium salt, 7 surfactants, 8,9 ionic liquids, 10,11 silane coupling agents 12,13 and different fatty acid salts, 14 which are common approaches to obtain a higher degree of delamination. Very recently, it was reported that 15 the preintercalation of stearic acid into the gallery of layered silicate, which was already modified by quaternary ammonium compounds (QUATs), could be one common approach to make the delamination process more effective. The effectiveness of this process was verified in different rubber systems where crosslinking was caused by a sulfur

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“…Infiltration in granular soils mainly involve capillarity whereas other physico-chemical effects also take place in fine grained soils in the clay fraction, in the organic fraction and along the oxides components (see for instance Lagaly 1984). As in unsaturated soils, techniques of controlling the ''matrix'' air-oil suction account for both capillary and physico-chemical soilfluid interactions.…”

Section: Napl Retention and Transfer Propertiesmentioning

confidence: 98%