Behaviour of CoNaA zeolites in interaction with water

1980 ◽  
Vol 45 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Blanka Wichterlová ◽  
Ludmila Kubelková ◽  
Pavel Jírů
Keyword(s):  
Catalytic Activity ◽  
Infrared Spectroscopy ◽  
Adsorbed Water ◽  
The State ◽  
Molecular Water ◽  
Oh Groups ◽  
Adsorption Of Water ◽  
Stretching Vibrations

The influence of dehydration and adsorption of water on the coordination of cations, the state of adsorbed water, and stretching vibrations of CoNaA and NaA zeolites was investigated by means of electronic and infrared spectroscopy. Complexes of Co2+ change their symmetry from octahedral through tetrahedral to planar trigonal. The role of ligands play both skeletal oxygens and molecular water. The formation of OH groups either on skeleton or on Co2+ ions was not found; the existence of these groups was assumed in the literature to explain the catalytic activity of CoNaA zeolites in the isomerization of butenes.

scholarly journals Moisture Induced Degradation of Porous Low-k Materials

2006 ◽  
Vol 914 ◽  
Author(s):  
Mikhail Baklanov ◽  
David O'Dwyer ◽  
Adam M Urbanowicz ◽  
Quoc Toan Le ◽  
Steven Demuynck ◽  
...  
Keyword(s):  
Water Film ◽  
Internal Surface ◽  
Hydrophobic Surface ◽  
Adsorbed Water ◽  
Bulk Water ◽  
Oh Groups ◽  
Film Bulk ◽  
Low K

AbstractInteraction of moisture with porous low-k films is evaluated by using in situ ellipsometry setup. The adsorbed water amount is calculated from change of refractive index measured during the adsorption. Pristine low-k films reversibly adsorb 2 - 5% of water that reflects presence of constitutive hydrophilic centrums. Plasma and thermal treatments increase the number of hydrophilic centrums. Once the amount of these centrums has reached a certain critical value sufficient to form a continuous water film, bulk water condensation is observed. Change of properties during the water adsorption in the damaged films is not fully reversible. Each additional adsorption cycle increases the dielectric function of the film because of decreasing porosity, increasing skeleton density and shrinkage. The pressure corresponding to the bulk condensation allows us to calculate internal contact angle (internal surface energy) of low-k materials. The water molecules adsorbed on separate OH groups play the role of a catalyst that hydrolyses the siloxane bridges initially present on hydrophobic surface.

Comparison of Water Adsorption Properties of Cellulose and Cellulose Nanocrystals Studied by Near-Infrared Spectroscopy and Gravimetry

2017 ◽  
Vol 735 ◽  
pp. 235-239 ◽  
Author(s):  
Thamonwan Angkuratipakorn ◽  
Jirada Singkhonrat ◽  
Alfred A. Christy
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Cellulose Nanocrystals ◽  
Water Adsorption ◽  
Near Infrared ◽  
Adsorption Properties ◽  
Water Molecules ◽  
Oh Groups ◽  
Adsorption Processes ◽  
Adsorption Of Water

The adsorption properties of water molecules on cellulose and cellulose nanocrystals (CNCs), isolated from defatted rice bran (DRB) by 55% sulfuric acid hydrolysis under sonication were investigated. The powdered samples of cellulose and CNCs were analysed by using near infrared spectroscopy (NIR) and gravimetry at 38% and 55% humidities. Small amounts of samples were dried under vacuum at 120°C and the NIR spectra of the dry samples and their spectra during the adsorption water molecules were measured by using an NIR spectrometer equipped with a transflectance accessory and a DTGS detector. The quantitative adsorption of water molecules by the samples was determined by gravimetry. Second and fourth derivative profiles of the NIR spectra were used in understanding the chemistry of adsorption of water molecules and the adsorption processes by the samples. The results show that the adsorption of water molecules by the cellulose samples gives rise to three prominent peaks that can be related to the water molecules engaged in hydrogen bonding with C2, C3 and C6-OH groups on the glucose units of the cellulose polymers. Furthermore, the cellulose nanocrystals adsorb twice as much of water as the cellulose polymer. It is also clear from the results that C2 and C3-OH groups in the glucose units adsorb water molecules at a faster rate than the C6-OH group and responsible for nearly 50% of the water adsorption.

scholarly journals Water Structure in Proteins in Solid State Studied by Near Infrared Spectroscopy

2017 ◽  
Vol 735 ◽  
pp. 168-172
Author(s):  
Siraporn Soonthonhut ◽  
Alfred A. Christy
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Water Adsorption ◽  
Near Infrared ◽  
Free Water ◽  
Adsorbed Water ◽  
Water Molecules ◽  
Combination Frequency ◽  
Adsorption Of Water ◽  
Combination Frequencies

Water adsorption in proteins is the crucial process of protein folding and structure stabilizing. Adsorption of water on proteins can be evaluated by near-infrared spectroscopy, a useful technique for observing combination frequency of a water molecule. In this work, albumin, lysozyme, and silk, were used as models for α-helix and β-pleated sheet proteins. Their NIR spectra during water adsorption process were measured by using an NIR spectrometer equipped with a transflectance accessory. Moreover, the quantitative adsorption of water was determined by gravimetric technique. The results indicate that, there are five different NIR absorptions arise from the OH combination frequencies of water adsorbed by albumin in the 5300-5100 cm-1 region. But there are only four absorptions for lysozyme and silk. The OH combination frequencies arising from water molecules in albumin indicate that it acquires free water molecules (5280 cm-1) and adsorbed water molecules through carbonyl-water interactions (5248 and 5160 cm-1) and amino-water interactions (5200 and 5120 cm-1). Interestingly, there is no indication for the presence of free water molecules in lysozyme and silk. Furthermore, the gravimetric results indicate that the rate of water adsorbed follows the order RW.Alb<RW.Lys<RW.Sil and total mass of water adsorbed per gram solid follows the order WAlb<WLys=WSil.

scholarly journals Comparison of Water Adsorption Characteristics of Oligo and Polysaccharides of α-Glucose Studied by Near Infrared Spectroscopy

2014 ◽  
Vol 1035 ◽  
pp. 476-482 ◽  
Author(s):  
Alfred A. Christy
Keyword(s):  
Near Infrared ◽  
Adsorbed Water ◽  
Water Molecules ◽  
Hydrogen Bond Formation ◽  
Oh Groups ◽  
Adsorption Characteristics ◽  
Near Infrared Spectra ◽  
Adsorption Of Water ◽  
Ethereal Oxygen ◽  
Combination Frequencies

The adsorption properties of water molecules on oligo and polysaccharides are attributed to the OH groups of the glucose rings in the molecules. The water molecules are adsorbed onto OH groups by hydrogen bond formation. Near infrared spectroscopic and gravimetric techniques were used in analysing the adsorption characteristics of malto-oligosaccharides and some polysaccharides. Near infrared spectra of the dry oligo and polysaccharides were acquired during the adsorption of water molecules at a relative humidity of 50-55%. The amounts of water adsorbed by the samples were also recorded by an analytical balance. Second derivative techniques were used in decomposing the OH combination frequencies of the adsorbed water molecules in the region 5300-5000 cm -1.The results indicate that the water molecules are adsorbed on to C2 and C3-OH groups at a higher rate compared to the adsorption onto C1-OH groups in the molecules. Adsorption also takes place onto the ethereal oxygen atoms in the glucose rings in malto-oligosaccarides. The gravimetric results show that the adsorption of water molecules increases with the number of glucose units in the malto-oligosaccharides except maltotriose which has the highest adsorption over a period of 75 minutes. Furthermore, the adsorption characteristics of amylose and amylopectin are similar.

IR study of water and 2-propanol adsorption on alumina

1988 ◽  
Vol 53 (4) ◽  
pp. 743-748 ◽  
Author(s):  
L. V. Malysheva ◽  
Vladimír Morávek ◽  
E. A. Paukshtis ◽  
E. N. Yurchenko
Keyword(s):  
Low Temperature ◽  
Ir Spectroscopy ◽  
Acid Sites ◽  
Molecular Water ◽  
Lewis Acid Sites ◽  
Irreversible Adsorption ◽  
Oh Groups ◽  
Adsorption Of Water ◽  
Adsorption Of Co ◽  
Ir Study

The adsorption of water and 2-propanol on alumina has been studied by means of IR spectroscopy. Low temperature adsorption of CO has revealed that evolution of Lewis acid sites begins at 80 °C in vacuo when still about 40% of molecular water is present on the surface. The thermodesorption of water proceeds by recombination of neighbouring OH groups. The adsorption of 2-propanol increases the concentration of the nonisolated OH groups and decreases the concentration of isolated ones. The irreversible adsorption influences mostly the C-O and Cβ-H bonds in 2-propanol.

Infrared spectroscopy of ferrihydrite: evidence for the presence of structural hydroxyl groups

Clay Minerals ◽  
1979 ◽  
Vol 14 (2) ◽  
pp. 109-114 ◽  
Author(s):  
J. D. Russell
Keyword(s):  
Infrared Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Adsorbed Water ◽  
Deformation Vibration ◽  
Hydroxyl Groups ◽  
Absorption Bands ◽  
Oh Groups ◽  
Structural Hydroxyl

AbstractIR spectroscopy has shown that adsorbed water is almost completely removed from ferrihydrite by evacuation at room temperature. Absorption bands at 3615 and 3430 cm−1 appearing thereafter are interpreted as arising from OH groups located respectively at the surface and deeper in the structure. These groups are readily converted to OD on treatment with D2O vapour and this has allowed the OH deformation vibration to be identified at 800 cm−1. It is proposed that OH groups in ferrihydrite are about half as numerous as those in akaganéite (β-FeOOH) and that they may occur in environments similar to those in this mineral. The formula for ferrihydrite proposed by earlier workers, 5 Fe2O3.9H2O, should thus be amended to Fe2O3. 2 FeOOH.2·6H2O in order to indicate the presence of structural OH groups. A re-appraisal of the ferrihydrite structure appears desirable.

A Re-Appraisal of the Role of Blood Coagulation and Platelets in the Generalized Shwartzman Phenomenon

1966 ◽  
Vol 15 (03/04) ◽  
pp. 519-538 ◽  
Author(s):  
J Levin ◽  
E Beck
Keyword(s):  
Blood Coagulation ◽  
The State ◽  
Coagulation System ◽  
Renal Lesions ◽  
Intravascular Coagulation ◽  
Renal Glomeruli ◽  
Coagulation Mechanism ◽  
Shwartzman Phenomenon ◽  
Do So

SummaryThe role of intravascular coagulation in the production of the generalized Shwartzman phenomenon has been evaluated. The administration of endotoxin to animals prepared with Thorotrast results in activation of the coagulation mechanism with the resultant deposition of fibrinoid material in the renal glomeruli. Anticoagulation prevents alterations in the state of the coagulation system and inhibits development of the renal lesions. Platelets are not primarily involved. Platelet antiserum produces similar lesions in animals prepared with Thorotrast, but appears to do so in a manner which does not significantly involve intravascular coagulation.The production of adrenal cortical hemorrhage, comparable to that seen in the Waterhouse-Friderichsen syndrome, following the administration of endotoxin to animals that had previously received ACTH does not require intravascular coagulation and may not be a manifestation of the generalized Shwartzman phenomenon.

Economic and Legal Support for Commercialization of Intellectual Property in Russia

2003 ◽  
pp. 66-76
Author(s):  
I. Dezhina ◽  
I. Leonov
Keyword(s):  
Intellectual Property ◽  
The State ◽  
Commercial Application ◽  
The West ◽  
Role Of The State ◽  
Legal Context

The article is devoted to the analysis of the changes in economic and legal context for commercial application of intellectual property created under federal budgetary financing. Special attention is given to the role of the state and to comparison of key elements of mechanisms for commercial application of intellectual property that are currently under implementation in Russia and in the West. A number of practical suggestions are presented aimed at improving government stimuli to commercialization of intellectual property created at budgetary expense.

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