On the Jovanovic model of adsorption

Summary The effect of the hydrostatic pressure exerted by bulk phases on adsorbed phases depends on the mobility of adsorbed phase and on the topographical distribution of adsorption energy. It is shown in this paper that the Langmuir's equation applies also to adsorption of fully mobile hard discs, on heterogeneous surfaces having fully random topographical distribution of adsorption energy. The effects of the hydrostatic pressure are discussed also in the case of heterogeneous surfaces exhibiting patchwise topographical distribution of adsorption energy.

Symbols

Roman Letters a parameter in the Jovanovic isotherm - A fraction of total surface covered - A ₁ fraction covered of sites having a given adsorption energy - A _j fraction of surface covered as evaluated from the Jovanovic adsorption isotherm - b,b _t parameters in various versions of the Langmuir isotherm - B number of adsorption sites on an adsorbent surface - H enthalpy of adsorption - F free energy of adsorption - k Boltzmann's constant - K, K _j ,K _L parameters in various versions of adsorption isotherms - m mass of the adsorbate molecule - N number of adsorbed molecules - N ₀ monolayer capacity in mobile adsorption - N ₁ local adsorption isotherm - N _t overall adsorption isotherm - p pressure of gas phase adsorbate - q canonical molecular partition function for mobile admolecules - q _st isosteric heat of adsorption - R gas constant - S surface area of adsorbent - S ₁ surface area of sites having a given adsorption energy - S ^* minimum change in the external variable S - T absolute tempetature - T _t frozen temperature Greek Letters Greek Letters parameter of the adsorption isotherm - isothermal-isobaric partition function - adsorption energy - area occupied by one adsorbate molecule - area of box of uniform adsorption energy - chemical potential - v frequency of vibrations of admolecules - range of variation of - () distribution of adsorption energy With 2 figures and 1 table     

Preparation of micron-sized composite polymer particles containing hydrophilic 2-hydroxyethyl methacrylate and their biomedical applications

Micron-sized polystyrene or PS particles were first prepared by dispersion polymerization. Then a series of polystyrene/poly(styrene-2-hydroxyethyl methacrylate) or PS/P(S-HEMA) composite polymer particles was prepared by seeded copolymerization using different amounts of 2-hydroxyethyl methacrylate (HEMA) at the constant core/shell ratio of 1/0.5. The produced PS seed and composite polymer particles were characterized by transmission electron microscopy. Adsorption behaviors of some biologically active macromolecules were studied under similar conditions. In each case the magnitude of adsorption on composite polymer particles decreased with the increase in HEMA content in the recipe, which means that the hydrophobic interaction between the surface of the particles and biomolecules decreased. The specific activities of trypsin aqueous solution and adsorbed trypsin on PS seed and composite polymer particles prepared with different HEMA contents were also measured and compared. The activity of adsorbed trypsin on composite polymer particles improved significantly with the incorporation of hydrophilic HEMA.     

Minor phospholipids of the seeds of the cotton plant of variety “Tashkent-2” structure of the N-acyllysophosphatidylethanolamine

Summary The minor phospholipids from the seeds of the cotton plant of variety Tashkent-2 have been isolated and studied. It has been established that the FA's attached to the N atom are more saturated than the corresponding O-acyls. For the N-acyllsyo-PE the structure of a 2-acylglycerophosphoryl-N-acylethanolamine has been proposed. As in the main fractions, in the minor components of the phospholipids of the seeds of the cotton plant of variety Tashkent-2 the saturated fatty acids mainly occupy position 2.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedininii, No. 1, pp. 41–44, January–February, 1978.     

A comparative study of uncatalyzed and catalyzed oscillatory behavior of different mono-and dihydroxybenzoic acids in acidic bromate

Optimum and boundary conditions for uncatalyzed and catalyzed temporal oscillations in the redox potentials in the oxidation of mono- and dihydroxybenzoic acids in acidic bromate (H₂SO₄) have been established and compared. The number and relative positions of the functional groups, in the aromatic ring have been found to influence the oscillatory behavior. Ferroin has been found to enhance the oscillatory behavior considerably as compared to Ce(IV) and Mn(II). A probable explanation of the oscillatory behaviour of these system is suggested.

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- - (H₂SO₄). . , Ce(IV) Mn(II), . .

     

The influence of basic calcium chloride nuclei on the hydration of calcium chloridesilicate

The influence of CaCl₂ · Ca(OH)₂ · H₂O nuclei on the hydration of Ca₃SiO₄Cl₂ was studied by means of calorimetry, X-ray diffraction, simultaneous DTA-TG and chemical analysis of the liquid phase.

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Zusammenfassung Der Einfluss von CaCl₂ · Ca(OH)₂ · H₂O-Zusätzen auf die Hydratation von Calciumchlorid-silicat Ca₃SiO₄Cl₂ wurde durch Kalorimetrie, Röntgenbeugung, simultane TG-DTA und chemische Analyse der flüssigen Phase untersucht.

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l₃ · ()₂ Ca₃SiO₄Cl₂ , .

     

Solvate shell rearrangements and solvation corrections to the Br?nsted equation

Solvate corrections f^solv for the Brönsted equation have been estimated under the assumption of the minimum work of shell rearrangement (MWSR).

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f^solv ().

     

Adsorption Peculiarities of Carbon Monoxide on Iridium Electrodeposits

The transients of current and open-circuit potential observed at CO adsorption on Ir/Pt electrodes in solutions of sulfuric and hydrochloric acids are shown to adequately agree with those theoretically expected. From voltammetric curves of electrooxidation of chemisorbed CO, the values of its adsorption are estimated by making a proper double-layer correction. It is concluded that CO is preferentially adsorbed in the bridge form. During CO adsorption from sulfuric acid solutions on an electrode with a preliminarily accumulated monolayer of copper adatoms (Cu_ad), small negative current are observed and Cu_ad are displaced by 50%. To explain these results, it is assumed that CO is reduced by copper adatoms.     

Kinetic equations for the redistribution of isotopic molecules due to reversible dissociation. Homoexchange of methane

Isotope kinetic equations for the equilibrium dissociation have been derived. General set of kineti equations of methane homoexchange for all dissociation variants under isotopic steady state of products have been obtained.

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Effect of Phase Transitions on Adsorption Properties of Thin Ferroelectric Poly(vinylidene fluoride-co-trifluoroethylene) Films

The adsorption isotherms of water, oxygen, and hexane molecules at the surface of poly(vinylidene fluoride-co-trifluoroethylene) films 30 and 5 monolayers thick obtained by the Langmuir–Schaefer technique were measured at various temperatures using quartz crystal microbalance. An effect of a ferroelectric phase transition occurring at a temperatures from 363 to 388 K on the adsorption activity of the films of the both thicknesses was disclosed. The highest adsorption was observed at a temperature T 380 K. In the case of the superthin copolymer film 5 monolayers thick, one more maximum of the adsorbability was detected at T 300 K that corresponded to a low-temperature phase transition, which is typical of only the copolymer films thinner than 30 monolayers. The effects observed were explained by the facilitation of an adsorbate diffusion into the copolymer film upon its structural rearrangement caused by the phase transition. The results of this study allowed us to propose a new method for the determination of structural phase transitions based on studying isotherms of molecular adsorption from the gaseous phase.     

Adsorption behaviors of emulsifiers and biomolecules on temperaturesensitive polymer particles

Adsorption and desorption behaviours of emulsifiers and biomolecules on the two kinds of temperature-sensitive composite polymer particles were compared. One (I) was produced by seeded emulsion copolymerization of dimethylaminoethyl methacrylate and ethylene glycol dimethacrylate with 0.17 m-sized polystyrene seed particles. The other (II) was produced by seeded emulsion copolymerization of N-isopropylacrylamide (NIPAM) and N,N-methylenebisacrylamide with 0.36 m-sized styrene-NIPAM copolymer particles. The amount of adsorption at temperatures above each lower critical solution temperature (LCST) was found to be much higher for I than II. In both cases, at temperatures below the LCST, almost all lactalbumin hydrolysate molecules adsorbed above the LCST were desorbed but the desorptions of adsorbed egg albumin and lysozyme molecules were not so high. The adsorption and desorption were reversible for both particles and the efficiency was better for I than II. From these results, it is concluded that the adsorption/desorption of protein onto the temperature-sensitive polymer particles is controllable by changing the temperature below and above the LCST of the shell layer and the sensitivity is based on the surface property of the composite polymer particles.Part CXLIX of the series Studies on Suspensions and Emulsions     

The influence of the water content on the adsorption properties of γ-Al2O3

Summary One of the most important parameters which decide the peaks resolution in HPLC with the nonmodified adsorbents, is the amount of water which is present on the adsorbent surface. This article tries to show that the change in the adsorption properties of -Al₂O₃ is dependent on the amount of adsorbed water. These changes are shown with the help of adsorption isotherms, isosteric heats of adsorption and adsorption energy distributions. The data is analysed on the bases of Jovanovic equations. It was also found that a relationship exists between the Brockman activity scale and the adsorption isotherm of water on -Al₂O₃.     

Zur Analytik histochemisch gebr?uchlicher Tetrazoliumsalze

Zusammenfassung Als Beitrag zur Klärung der bei Verwendung von Di-Tetrazoliumsalzen in der Fermenthistochemie auftretenden Rotstufen wird das analytische Verhalten einer Reihe von Tetrazoliumsalzen charakterisiert. Für die papier-chromatographische Trennung von Diformazanen, Mono formazanen und Halbreduktionsstufen von Di-Tetrazoliumsalzen werden geeignete Lösungsmittelsysteme angegeben. Für die Formazane und Halbreduktionsstufen wird die Lage der Maxima in reinem und in alkalisiertem Tetrahydrofuran ermittelt. Daneben sind die Extinktions koeffizienten einiger Formazane bestimmt worden. Es wird über Versuche zur Herstellung von Mono-Tetrazoliumsalz-freien Di-Tetrazolium-salzen berichtet.

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Summary For explaining the red stages which occur in enzymatic histochemistry when using ditetrazolium salts, the analytical properties of several tetrazolium salts are characterized. Suitable solvent mixtures for separating formazans, diformazans and semi-reduction stages of ditetrazolium salts by paper-chromatography are described. The position of the maxima of formazans and semi-reduction stages in pure and alkalized tetrahydrofurane are estimated. The extinction coefficients of some formazans are listed. The preparation of ditetrazolium salts free of monotetrazolium salt is described.

     

Features of nuclear magnetic relaxation of water and benzene molecules during absorption on activated carbons and estimation of pore size distribution in adsorbents

Nuclear magnetic relaxation in activated carbon—water and activated carbon—benzene adsorption systems was studied by pulse NMR methods. Activated carbons characterized by different porous structures and chemical state of the surface were used. The application of the three-pulse Goldman—Shen sequence to the adsorption system generates a dipole echo caused by the dipole-dipole coupling of structural protons, which is not averaged due to their mobility during experiment. The non-exponential character of relaxation attenuations of the transverse and longitudinal nuclear magnetizations of physically adsorbed molecules in activated carbon pores is a result of differencies in pore sizes. The pore sizes in activated carbon and the size distribution were determined from the data of nuclear magnetic relaxation with allowance for the contribution from the structural protons.     

Thermoanalytical characterization of precipitated acids obtained by alkaline permanganate degradation of the kerogen from Aleksinac (Yugoslavia) oil shale

The precipitated acids, obtained by partial stepwise oxidation of Aleksinac (Yugoslavia) shale kerogen, were studied by thermal analysis. Significant differences were observed in the weight loss and the shape of TG curves of precipitated acids from various degradation steps, indicating their structural differences and heterogeneity of the kerogen. The thermal curves of precipitated acids were found to consist of two distinct parts. From IR data it was found that the low-temperature part corresponded to thermal changes of aromatic, and the high-temperature part of aliphatic type structures. These results were in good agreement with chemical analysis (elemental analysis, atomic H/C ratio, total acidity) of the same acids.

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Zusammenfassung Durch partielle schrittweise Oxydierung von Schieferkerogen (Aleksinac. Jugoslavien) erhaltene präzipitierte Säuren werden thermoanalytisch untersucht. Signifikante Unterschiede wurden im Gewichtsverlust und der TG-Kurvengestalt von nach den einzelnen Abbauschritten erhaltenen präzipitierten Säuren beobachtet, was auf deren strukturelle Verschiedenheit und auf die Heterogenität des Kerogens hinweist. Die thermische Kurven der präzipitierten Säuren weisen zwei sich unterscheidende Abschnitte auf. Aus IR-Daten ergab sich, daß im Tieftemperaturabschnitt thermische Veränderungen von aromatischen, im Hochtemperaturabschnitt dagegen von aliphatischen Strukturen verlaufen. Diese Ergebnisse stimmen mit chemischen Analysendaten (Elementaranalyse, H/C-Atomverhältnis, Gesamtsäure) gut überein.

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, ( ). , , , . , . , , — . ( , -, ) .

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Paper presented at the World Conference on Thermal Analysis, Madeira (Portugal). 1986.     

Effect of surface charge on adsorption of bovine serum albumin as studied by ellipsometry 1. Adsorption on cationic monolayer

The adsorption of bovine serum albumin (BSA) onto a cationic monolayer (N,N-dimethyl-N,N-dialkylammonium chloride) spread at the air/water interface was studied by ellipsometry. Both thicknesses and refractive indices of the BSA layer adsorbed at the monolayer/solution interface are estimated from the observed change in phase difference and the ratio of reflection coefficients. The amount of adsorption of BSA resembles a Langmuir type isotherm. The adsorption changes with pH asymmetrically with respect to the pH of maximum adsorption, which was calculated to be 5.06 ± 0.47 mg/m². The amount of maximum adsorption implies that the BSA molecule adsorbs to the surface in a mode intermediate between side-on and end-on.     

ET-AAS in the Analysis of high-purity mercury

ET-AAS is investigated for the analysis of high purity mercury. Two possibilities are proposed: ET-AAS determination of trace analytes in the presence of high mercury concentrations or after matrix separation by reduction. The ET-AAS analysis of high-purity mercury under optimal instrumental parameters permits fast and reproducible determination of 0.03 gg^–1 Al, Cd and Mn; 0.05 gg^–1 Cu, Co, Cr, Fe, Ni and Pb and 0.2 gg^–1 V. Preliminary mercury matrix reductive separation with ascorbic acid allows determination of 0.005 gg^–1 Cd, 0.02 gg^–1 Cu, Cr and Mn, 0.03 g g^–1 Co, Ni and Pb, 0.05 g g^–1 Al and Fe and 0.1 gg^–1 V, but the reproducibility is lower. The main advantage of the second procedure is that it avoids laboratory and instrument pollution with toxic mercury.     

Structure of the sesquiterpene lactone artapshinin

On the basis of spectral characteristics (IR,¹H and¹³C NMR spectroscopies) and chemical transformations it has been shown that the new sesquiterpene lactone artapshinin has the structure of 1,3-dihydroxy-6H,7H,11H-germacra-4(5),10(15)-dien-6,12-olide.Institute of Botany, Academy of Sciences of the Azerbaidzhan Republic, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 837–840, November–December, 1997.     

Pathomechanisms of the adult respiratory distress syndrome (ARDS): elastase contents of polymorphonuclear leukocytes and elastase release during passage across the blood/air barrier

Conclusions In comparison to normals blood derived PMNL of ARDS patients were found to be partially depleted of elastase that in turn caused a 5-fold elevation of the plasma elastase concentration. During their capillary-interstitial-alveolar passage stimulated PMNL released elastase as could be demonstrated by the further decreased elastase contents of BAL derived PMNL and by a 68-fold increase in total elastase concentration in BAL fluid as compared to normals. Urea served as an internal reference substance in plasma and BAL fluid as well as the albumin/urea ratios indicated the extent of permeability increase. By this it was possible to judge whether the high total elastase concentration in BAL fluid predominantly resulted from a₁PI-elastase complex permeation or from elastase release during PMNL migration followed by consecutive complexation with ubiquitously occurring a₁PI. The total elastase/urea ratios of the patients were elevated 79-fold above normals in BAL fluid whereas the patients' albumin/urea ratios were only 4.4-fold higher than those of normals. These data gave evidence that the high BAL fluid elastase concentration was mainly the result of free elastase release from migrating and phagocytosing PMNL. Hereby, the inflammatory cascades can be started and/ or enhanced, thus contributing to lung injury in ARDS, especially, if non-complexed enzymatically active elastase is present in BAL fluid.

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Zum Pathomechanismus des posttraumatischen progressiven Lungenversagens (ARDS): Elastase-Gehalt und -Freisetzung aus polymorphkernigen Leukocyten während der capillär/alveolären Passage

Abbreviations PTS polytrauma scale injury severity score (ISS) - NP 40 Nonidet P-40 nonionic detergent - ₁ PI ₁-protein-ase inhibitor (₁-antitrypsin) Supported by the Deutsche Forschungsgemeinschaft, project II B 6     

Can TMS and DSS be used as NMR references for cyclodextrin species in aqueous solution?

Tetramethylsilane (TMS) can be included by -cyclodextrin (-CD), and sodium 2,2-dimethylsilapentane-5-sulphonate (DSS) can form inclusion complexes with - and -CD. The NMR chemical shifts are changed considerably as a result of the strong interaction between CD and the guest compound in the inclusion complexes. A downfield shift of as much as 0.63 ppm shift downfield has been observed for the protons of external TMS in CD aqueous solution. In view of this, the question arises of whether TMS and DSS can be used as internal references. DSS in D₂O is suggested as an external reference for aqueous cyclodextrin solution in NMR measurements.     

Über die Verwendung von Adsorptionszonen in der Ringofenmethode

Zusammenfassung Um auch thermolabile Substanzen mit der Ringofenmethode untersuchen zu können, wird an Stelle der sonst üblichen Temperaturbarriere eine Adsorptionsbarriere vorgeschlagen. Mit Hilfe des Ringofens wird eine scharf ausgebildete ringförmige Zone eines Adsorptionsmittels auf Filterpapier hergestellt. Die zu konzentrierenden Substanzen werden mit einem Lösungsmittel — ohne Verwendung des Ringofens selbst — in diese Zone gewaschen.

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On the application of adsorption zones in the ring-oven method

Summary To permit also the investigation of thermo-labile substances by the ring-furnace method, it has been suggested that the usual temperature barrier be substituted by an adsorption barrier. A sharply developed ring-shaped zone of an adsorption agent is produced on filter paper with the aid of the ring furnace. The substances to be concentrated are washed into this zone by means of a solvent without employing the ring furnace itself.