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Recent scientific publications have already demonstrated that co-grinding appears as an efficient, solvent-free technique for preparing cyclodextrin complexes and improving physicochemical properties of active ingredients. The improvement of solubility and dissolution rate could enhance the biopharmaceutical properties of the active ingredients in solid pharmaceutical products. Furthermore stable, amorphous, organic solvent-free inclusion complexes could be formed efficiently in the industrial environment. In this study terbinafine hydrochloride (TER), an antifungal BCS II drug was chosen as a model drug. The aim of this study was the follow-through of inclusion complex preparation by co-grinding using several analytical methods. TER and amorphous cyclodextrin derivatives (hydroxypropyl-β-cyclodextrin; heptakis(2,6-di-O-methyl)-β-cyclodextrin) were used for the preparation of products. The thermoanalytical behavior was analyzed by differential scanning calorimetry (DSC), the occurred changes in crystalline properties were investigated by X-ray powder diffractometry (XRPD) and hot-humidity stage X-ray powder diffractometry (HOT-XRPD). Chemical interactions between the components were analyzed by Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR). Dissolution studies of TER and products were also carried out. Cyclodextrin-TER complexes were prepared in the 1:1 molar ratio. DSC and XRPD studies suggested that the crystallinity of products gradually decreased by the increasing grinding time, and after 75 minutes of co-grinding the products were completely amorphous. HOT-XRPD studies revealed that the amorphous product containing hydroxypropyl-β-cyclodextrin did not change with increasing temperature. However, in the same process, the heptakis(2,6-di-O-methyl)-β-cyclodextrin containing product recrystallized in a new crystalline phase. Raman and FT-IR spectroscopy confirmed the molecular interactions between the components. Dissolution studies showed that the dissolution rate of complexes improved, and the solubility of TER increased both in simulated gastric and intestinal fluid, depending on the pH of the dissolution medium.

In the present work, the structure and thermal stability of Ca–Al mixed-metal compounds, relevant in the Bayer process as intermediates, have been investigated. X-ray diffraction (XRD) measurements revealed the amorphous morphology of the compounds, which was corroborated by SEM-EDX measurements. The results of ICP-OES and UV-Vis experiments suggested the formation of three possible ternary calcium aluminum heptagluconate (Ca-Al-Hpgl) compounds, with the formulae of CaAlHpgl(OH)40, Ca2AlHpgl2(OH)50 and Ca3Al2Hpgl3(OH)90. Additional IR and Raman experiments revealed the centrally symmetric arrangement of heptagluconate around the metal ion. The increased thermal stability was demonstrated by thermal analysis of the solids and confirmed our findings.

The conformational as well as the structure-forming properties of E -3-( x -pyridyl)propenoic acids ( x = 2, 3 or 4) have been studied with a combination of computational and spectroscopic methods. IR spectroscopy revealed that in the solid state the zwitterionic species predominate, while NMR measurements showed that dimers, kept together by strong C O⋯H O hydrogen bonds, were formed in a dipolar aprotic solvent (DMSO). In concentrated solution, extended aggregation occurred through the cooperative effect of (aromatic) C H⋯N weak hydrogen bonds. Conformational search was performed at the HF/6-31G(d,p) level of theory. Comparison with experimental values as well as benchmarking calculations at several different levels of theory to probe the performance of the methods, B3LYP/6-31G++(d,p) method was found to be able to provide reasonable geometries as well as quantitative formation energies for the dimers and the tetramers, too.

Psoriasis is a T lymphocyte-mediated inflammatory disorder that affects the skin. A number of studies have demonstrated the occurrence of lipid alterations in psoriatic skin, resulting in a highly perturbed stratum corneum (SC). Relatively little attention has been paid to the protein conformation of the SC. In this study, the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrum of the untreated psoriatic patients' unharmed SC was obtained after tape stripping. We focused on the amide-I band components in order to establish whether there are any protein alterations in the intact areas of psoriatic skin. Fourier self-deconvolution (FSD) of the amide-I band was followed by curve-fitting to generate the underlying components. Integration of band areas provided an estimate of the secondary structure. The results indicated decreases in all amide-I band components, the peak at 1660 cm − 1 revealing the most dramatic change. This peak is characteristic of the turn structure in the protein chain. The decrease is marked in the case of the β-sheet structure at 1630 cm − 1 too. This ATR-FTIR imaging is a rapid and simple noninvasive method, promotes a better understanding of the disease, and would be helpful in following the treatment.

Two different preparation methods were developed to cover successfully multi-walled carbon nanotubes (MWCNT) with tin-dioxide (SnO 2 ) nanoparticles using SnCl 2 I‡2H 2 O as precursor under different solvent conditions. The applied mass ratios of the components were 1:4, 1:8, 1:16, 1:32 and 1:64, respectively. As-prepared tin-dioxide coverages were characterized by TEM, SEM, SEM-EDX, Raman microscopy, BET and X-ray diffraction techniques. Photocatalytic efficiencies of selected composites were investigated in a self-made photoreactor, equipped with UV-A fluorescence lamps. Photocatalytic degradation of phenol solution was followed by using HPLC. Observations revealed that using hydrothermal method we can easily control the layer of SnO 2 nanoparticles on the surface of MWCNTs. Using various solvents SnO 2 nanoparticles with different morphologies formed. The nanocomposites have low photocatalytic efficiencies under conditions used generally (when I»>300 nm).

Effective bio-electrocatalysts require stable immobilization of sufficient amounts of the bioactive component. In this study, a novel and efficient method for specific binding of laccase enzyme onto magnetite nanoparticles (NPs) is presented. The interaction between the chemically modified magnetite NPs and the enzyme was evidenced by both infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). Subsequently, the enzyme-coated magnetite NPs were successfully incorporated into polypyrrole (PPy) matrix during galvanostatic electropolymerization. The encapsulation of laccase covered NPs was proved by EQCN, TEM, and FT-IR spectroscopy; whereas the electrochemical behaviour of the formed bionanocomposite was characterized by cyclic voltammetry. In oxygen saturated solution a cathodic charge surplus was observed, related to the electrochemical reduction of oxygen. This surplus was two times higher in the case of the laccase containing layer compared to its only magnetite containing counterpart. Kinetic aspects of the oxygen reduction reaction (ORR) on the laccase containing films were investigated by hydrodynamic voltammetry, and the four-electron route was found to be exclusive, which is promising from the fuel cell perspective. Such synergistic combination of inorganic NPs and enzymes may open new avenues in the application of these bio-nanocomposite materials.

The identity of the predominating tin(II)-hydroxide complex formed in hyper-alkaline aqueous solutions (0.2

The plasmonic Ag-TiO2 (with 0.5 wt% Ag) photocatalyst was prepared on P25 TiO2 surface. The presence of AgNPs on the titania was indicated by the UV–vis spectrum, which showed a plasmonic absorbance band in the visible range (λmax = 455 nm). XPS measurements suggested that Ag was in metallic (Ag) and in oxide forms on TiO2. Ag-TiO2 photocatalyst and TiO2 were embedded in [poly(ethyl acrylate-co-methyl methacrylate; p(EA-co-MMA)] copolymer to attain mechanically stable, photocatalytically active nanocomposite films. The photooxidation of ethanol was slower on the photocatalyst/polymer nanocomposites, but it could be significantly improved by irradiating them with UV light. The photoaging was applied as a post-preparation treatment to improve the photocatalytic activity of the nanocomposite films. Changed surface morphology and the partial destruction of the polymer were supported by AFM and FTIR results. Contact angle measurements were used to determine the surface free energies of the prepared and the photoaged nanocomposite films.

The investigation of free films is an essential part of the preformulation studies, because it is necessary to know, weather the given formulation is suitable to coat the corpus or not. As preformulation, the relationships between surface properties, and the structure of ethylcellulose free films containing different amount of plasticizer were studied. The structure analysis, and the incorporation of the plasticizer was performed with the use of FT-IR analysis. The results showed that the films are suitable to produce diffusion coatings.

The intercalation of biosurfactants (lysolecithin and lecithin) in layered clay mineral supports was investigated to assess the suitability of the resulting nanohybrid materials as flavor and fragrance delivery system. The protonated biosurfactant molecules (pH = 2.3) were intercalated into the Na-montmorillonite, whereas the deprotonated biosurfactants (pH ~ 12) were intercalated into Mg–Al layered double hydroxides. The amount of lysolecithin and lecithin bound to the layered adsorbents was estimated by measuring adsorption isotherms. The basal spacing obtained from X-ray diffraction measurements suggested that the molecules are arranged in parallel with the layers of montmorillonite, whereas in the case of layered double hydroxides, the adsorbed molecules are in a vertical position between the layers. The interaction of layered adsorbents and biosurfactants was further evidenced by infrared spectroscopy. The intercalated montmorillonite and LDH particles were then probed for their ability to intercalate limonene molecules. Only the lysolecithins modified samples adsorbed limonene. The theoretical sizes of molecules and their possible arrangement between the layers were modeled by HyperChem 7.0 molecular calculations to correlate the ability to bind the lecithins in the confined space of the layered materials.

The preparation and application of heterogeneous chiral catalysts are described. Heterogeneous Pd, Ir and Ru catalysts were tested in the enantioselective hydrogenations of N-heterocyclic compounds, namely 6,7-dimethoxy-3,4-dihydroisoquinoline and 1-methylene-2-ethoxycarbonyl-6,7-dimetoxy-3,4-dihydroisoquinoline in the presence of optically pure cinchonidine, (S,S)- and (R,R)-Ts-DPEN ligands. Cinchonidine-modified metal catalysts exhibited low ee, whereas catalysts stabilized by triphenylphosphane and modified by (S,S)-Ts-DPEN afforded promising ee values (70–80 %). Immobilized Ru(II)-aminophosphane complexes were found to be active in these hydrogenations producing the corresponding tetrahydroisoquinoline derivatives in high optical purities (up to 97 %). The latter catalysts were characterized by infrared spectroscopy, solid-state MAS NMR spectroscopy and elemental analysis. Recycling of these catalysts showed constant or increasing activities in racemic hydrogenation, whereas the presence of the chiral ligands led to leaching of the active species in the liquid phase.

An exact wavelength separation of the spectrum cannot be accomplished when utilizing common ultraviolet (UV) light sources, so the dependence of photodegradation on wavelength cannot be done directly. The photodegradation of wood resulted in by laser irradiation on various wavelengths can be studied by comparing the changes in the DRIFT spectra of various wood materials. The analysis of the difference spectrum is a widely used method to investigate the changes in the infrared spectrum. As this procedure cannot be used to compare the changes quantitatively, a new indicator was introduced, termed Band Damage Index (BDI). The BDI and the results obtained by its analysis are going to be discussed.

The steps of formation of an inclusion complex produced by the co-grinding of gemfibrozil and dimethyl-β-cyclodextrin were investigated by differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD) and Fourier transform infrared (FTIR) spectroscopy with curve-fitting analysis. The endothermic peak at 59.25 °C reflecting the melting of gemfibrozil progressively disappeared from the DSC curves of the products on increase of the duration of co-grinding. The crystallinity of the samples too gradually decreased, and after 35 min of co-grinding the product was totally amorphous. Up to this co-grinding time, XRPD and FTIR investigations indicated a linear correlation between the cyclodextrin complexation and the co-grinding time. After co-grinding for 30 min, the ratio of complex formation did not increase. These studies demonstrated that co-grinding is a suitable method for the complexation of gemfibrozil with dimethyl-β-cyclodextrin. XRPD analysis revealed the amorphous state of the gemfibrozil–dimethyl-β-cyclodextrin product. FTIR spectroscopy with curve-fitting analysis may be useful as a semiquantitative analytical method for discriminating the molecular and amorphous states of gemfibrozil.

The aim of this study was to develop transdermal gel formulations for ibuprofen, which ensure good skin permeation into the deeper layers, hereby achieving effective pain and inflammation relief locally. Transcutol and a new generation surfactant, a sucrose ester, were used as penetration enhancer. Ibuprofen diffusion was investigated across synthetic membrane (in vitro), and permeation was examined through excised human epidermis (ex vivo) and hairless mice (in vivo) too. Our investigations revealed that Transcutol is an effective diffusion increaser for ibuprofen, but it could not enhance its skin permeation. However, the sucrose ester promoted skin permeation of ibuprofen 2.15 fold. From our study, it seems that it is not enough to make in vitro membrane diffusion measurements by testing newly developed transdermal preparations, but it is also indispensable to complete the examinations with ex vivo skin permeation method. Our investigations show that sucrose laurate seems to be an appropriate and effective penetration and permeation enhancer for ibuprofen.

The compatibility of aceclofenac with various tableting excipients was investigated by means of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The excipients applied in the direct pressing retard tablets were Carbopol 940, hydroxypropyl-methyl-cellulose, microcrystalline cellulose, Aerosil 200 and magnesium stearate. The ingredients alone and their 1:1 (w/w) binary mixtures were investigated before and after accelerated storage. An interaction was observed only between aceclofenac and magnesium stearate. The DSC and FT-IR examinations indicated formation of the magnesium salt of aceclofenac. For the other mixtures, there was no incompatibility between the components.

Conducting polymers are getting more and more interest as both supporting matrixes and electrocatalysts in the oxygen reduction reaction (ORR). A polypyrrole−magnetite nanocomposite layer has been synthesized by using potassium tetraoxalate as the conducting electrolyte. FT-IR measurements proved that chemical modification of the iron oxide by a reaction between the nanoparticles and the salt—leading to an iron oxalate layer on their surface—endows a negative charge to the particles, which leads to their penetration into the polymeric film as a part of the charge compensation. The new hybrid material showed significant photoelectrocatalytic behavior in the ORR. The ratio observed between the stabilized stationary currents under and without illumination is 2.0 for this hybrid. Separate studies on the electrochemical decomposition of H2O2 also indicated an enhanced catalytic activity of the polypyrrole/magnetite hybrid compared with the neat polymer. The results may open new opportunities in the next genera...

Potential metal-organic-framework precursors, Zn(4)O complexes with various alicyclic or aromatic carboxylate ligands, were prepared, in many cases quantitatively, from ZnO and the relevant carboxylic acids in the presence of trace amounts of water. The complexes obtained were characterized with various classical (titration) and instrumental (IR and NMR spectroscopies) methods and molecular modeling (PM3 and PM6 semiempirical quantum chemical methods and HF/6-31G** ab initio calculations). Structural peculiarities reflected in the success or failure in the synthesis could be rationalized with the combination of IR and NMR spectroscopies and molecular modeling.

Ablation of a silicone oil, Dow Corning's DC-705 with laser pulses of sub-ps duration in high vacuum is a novel approach to fabrication of Si-doped carbon nanocomposite films. Gently focused, temporally clean 700 fs pulses @ 248 nm of a hybrid dye/excimer laser system produce power densities of the order of 10 11 –10 12 W cm −2 on the target surface. The evolution of the chemical structure of film material is followed by comparing Fourier Transformed Infrared and X-ray Photoelectron spectra of films deposited at temperatures between room temperature and 250 °C. Despite the low thermal budget technique, in the spectrum of films deposited at room temperature the fingerprint of the silicone oil can clearly be identified. With increasing substrate temperature the contribution of the features characteristic of the oil gradually diminishes, but does not completely disappear even at 250 °C. This result is intriguing since the chance of oil droplets to survive in their original liquid form on the hot surface should be minimal. The results of the X-ray Photoelectron Spectroscopy suggest that the chemical structure of the film material resembles that of the oil. Both reflection mode optical microscopy and low magnification Scanning Electron Microscopy reveal that the films are inhomogeneous: areas of lateral dimensions ranging from a few to tens of micrometers, characterized by different contrasts can be identified. On the other hand, surface mapping by Scanning Electron and Atomic Force Microscopy unambiguously proves that all films possess a solid surface consisting of nanoparticles of less than 100 nm dimension, without the presence of any drop of oil. Possible explanations of the puzzling results can be that the films are polymers consisting mainly of the molecules of the target material, or composites of solid C:Si nanoparticles and oil residues.

The aim of this study was to evaluate the interaction between the film-forming sodium alginate and lactose monohydrate. This combination is used in the co-spray-drying technique for microencapsulation, but no respect on the structure of the film formed has not been published previously. From mechanical tests, positronium lifetime measurements and FT-IR studies on free films containing different ratios of film-former and lactose, we concluded that the mechanical strength of the sodium alginate film decreased with the increasing proportion of lactose. The free volume in the polymer matrix decreased to a minimum as the lactose content was progressively increased to 40%, but subsequently increased at higher lactose contents. The explanation of this phenomenon is the filling of the holes with the sugar. As lactose became predominant component, the structure of the polymer network weakened. These conclusions were supported by the FT-IR findings. The present results permit a clear explanation of the previously reported favourable effects of this film-forming combination on the dissolution of the active agent from the microcapsules.

A tricyclic, piperidine derivative of antihistamines, loratadine, which belongs in class II of the Biopharmaceutical Classification System, was investigated. It is an ionizable drug, whose solubility depends on the gastrointestinal pH, and the bioavailability is therefore very variable. The aim of this work was to enhance the dissolution and make the solubility of loratadine independent of pH. Inclusion complexes were prepared between loratadine and dimethyl-β-cyclodextrin in two different molar ratios by three techniques (physical mixing, kneading and spray-drying). The formation and physicochemical properties of the inclusion complexes were investigated by means of dissolution tests, thermal analysis and Fourier Transform Infrared spectroscopy. The instrumental examinations proved the presence of partial or total complexes depending on the preparation method and molar ratio, which resulted in better dissolution. For some compositions and preparation methods, the application of this cyclodextrin made the solubility of loratadine independent of pH.

Polythiophene−magnetite composite layers have been prepared through the electropolymerization of 3-thiophene-acetic-acid in the presence of Fe3O4 nanoparticles in nitrobenzene. Stabilization of magnetite in this organic medium could be achieved by the reaction between surface −OH groups of the nanoparticles and the −COOH function of the monomers. Fourier transformed infrared spectroscopic (FT-IR) measurements evidenced the chemisorption of the monomer on the surface of the nanoparticles. By modifying the amount of iron-oxide in the polymerization solution, the inorganic material content of the layer could be increased up to 80 m/m%. Electrochemical results, including data obtained by electrochemical quartz crystal microbalance (EQCM), proved that the presence of Fe3O4 did not influence the redox properties of the polymeric film. In the presence of magnetite, an extraordinary microstructure can be detected, where the self-assembling magnetic component strongly determines the morphology of the composite, le...

Mid infrared, far-infrared and Raman spectroscopic studies, combined with force field analyses, were performed for the 1 hydrated platinum(II) and palladium(II) ions and cis-diammineplatinum(II) complex in acidic aqueous solutions. Simplified Density Functional Theory (DFT) calculations were made for the equatorial plane of the platinum complexes. Careful subtraction of solvent spectra allowed a number of 'internal' modes of coordinated H(2)O and NH(3) to be determined as weak residual bands. The [Pt(OH(2))(6)](2+) and [cis-Pt(NH(3))(2)(OH(2))(4)](2+) complexes were found to be six-coordinated with four ligands strongly bound in an equatorial plane. The assignments of the vibrational modes in the equatorial plane could be performed on the basis of the experimental observations and by comparison with metal-ligand vibrations of square-planar complexes, aided by normal coordinate calculations. For the weakly coordinated axial aqua ligands, the low wavenumber range and the polarizibility properties allowed the assignments of the bands at about 365 and 325 cm(-1) to the stretching modes of one short and one longer Pt - O* bound to axial aqua ligands, respectively. A similar picture with even less strongly bound axial water molecules emerges from Raman spectroscopy data for the hydrated palladium(II) ion, [Pd(OH(2))(6)](2+). The results are consistent with a description of the [Pt(OH(2))(6)](2+) and [Pd(OH(2))(6)](2+) aqua ions in C(4v) symmetry, and with the [cis-Pt(NH(3))(2)(OH(2))(4)](2+) complex in the Cs point group, and also in qualitative agreement with the structures devised from previous extended X-ray absorption fine structure (EXAFS) measurements.

The majority of active pharmaceutical ingredients are poorly soluble in water. The rate-determining step of absorption is the dissolution of these drugs. Inclusion complexation with cyclodextrin derivatives can lead to improved aqueous solubility and bioavailability of pharmacons due to the formation of co-crystals through hydrogen-bonding between the components. Inclusion complexes of loratadine were prepared by a convenient new method involving microwave irradiation and the products were compared with those of a conventional preparation method. Dissolution studies demonstrated that the solubility and rate of dissolution of loratadine increased in both of the methods used. The interactions between the components were investigated by thermal analysis and Fourier Transform Infrared studies. The microwave treatment did not cause any chemical changes in the loratadine molecule.

In order to find highly active and selective oxygen-transfer catalysts with appreciable durability, Cu(II)-histidine complexes were covalently grafted onto a chlorinated polystyrene resin as copper-containing enzyme mimics. The Cu(II)-histidine complexes and the mobile polymer were to resemble the active center and the pro- teomic skeleton of the enzymes, respectively. The resulting heterogenized complexes were expected to be nearly so active and more durable catalysts that are easier to recycle than their homogeneous counterparts. The substances were tested in a superoxide radical anion dismutation reaction. Control for the syntheses was exerted by protecting either the N-terminal or the C-terminal of the covalently grafted L-histidine molecules. During the preparative work gener- ally applied methods of synthetic organic chemistry (alkylation or esterification) were used. Various anchored complexes were prepared and characterized by classical analytical methods, different forms of spectroscopy as well as molecular modeling. The covalently grafted complexes having the protected amino acids as ligands displayed remarkably high activities in the superoxide dismutase (SOD) test reaction.

Highly concentrated alkaline gallate solutions with 0.23≤[Ga(III)]T≤2.32 mol⋅dm−3 and 1≤[NaOH]T≤15 mol⋅dm−3 have been prepared and investigated by Raman and 71Ga-NMR spectroscopy. Both the Raman and 71Ga-NMR spectra are consistent with the presence of only one Ga-bearing species in these solutions, the tetrahedral hydroxocomplex, Ga(OH)4−. Contact ion pairs were found to cause variations in the Raman and 71Ga-NMR parameters that are at the edge of detectability. Other species that have been claimed to exist in the literature, like higher hydroxo complexes (i.e., Ga(OH)63−) or the μ-oxo-bridged dimer (i.e., (OH)3Ga-O-(OH)32−), were not detected by these spectroscopic techniques. If such solution species exist at all, their concentrations are below the detection limit of Raman and 71Ga-NMR spectroscopy. The behavior of gallium appears to be very similar to that of aluminium under identical conditions, except that the dimeric species detected in aluminate solutions is undetectable in analogous gallates.

Poly(3-octylthiophene)/silver nanocomposites (P3OT/Ag) were prepared by impregnating the polymer powder in silver perchlorate salt solutions. The total silver content, up to 6 wt %, was determined by inductively coupled plasma atomic absorption spectroscopy (ICP-AAS). The electric conductivities of the composites were measured and correlated with the silver content. Conductivity increased by more than 5 orders of magnitude with silver doping. The incorporated silver was speciated by X-ray diffraction (XRD). Silver was found in the form of both Ag and AgCl, predominantly in metallic nanocrystallites. The size distribution of the nanoparticles, determined from transmission electron microscopy (TEM), was found to be bimodal with two maxima around 3 and 17 nm, correlating with the two forms of silver in the composite. Increased conductivity was interpreted by results obtained by photoacoustic Fourier transform infrared spectroscopy (PAS-FTIR). The observed large Seebeck coefficient of P3OT is promising from t...

The Zn 4 O(RCO 2 ) 6 complexes of a selection of straight- and branched-chain carboxylic acids have been prepared in CCl 4 and characterized by their 13 C NMR, 1 H NMR and mid-FT-IR spectra. Their structural stability was studied by FT-IR-spectroscopy over a 4-day long period of time in CCl 4 solution and as cast films. The observed characteristic spectroscopic features have been discussed. The cast film samples showed extremely diverse behaviour from instant decomposition to the perfect conservation of the original T d symmetry, even though water was not excluded from the system. An explanation, supported by ab initio quantum chemical calculations on the conformation of the free carboxylate ions with various alkyl-chains, has been given for the diverse behaviour of the samples. Formation of a hydrocarbon moiety, with somewhat extended anti-periplanar (all- trans ) conformation, perpendicular to the carboxylate plane was the essential factor in the preservation of the structure and the quaternary α-carbon was an additional requirement to sustain its symmetry. Two attempts at preparing the corresponding Zn 4 O(RCO 2 ) 6 complexes from water have been successful in the cases when the R-groups fulfilled the requirements in geometry stated above.

Acrylic polymers in aqueous dispersions are very often used to prepare coating suspensions which contain insoluble particles. The mixing of the pigment suspension and the polymer dispersion is a very important step in the preparation of the liquid. The stirring can cause precipitation of the polymer and foam formation. Foam formation from different Eudragit dispersions was evaluated in this study. A high-speed mixer was applied and the foam and liquid phases formed were separated. The changes in concentration of the polymer in the two phases were studied by FT-IR with a horizontal attenuated total reflection (HATR) accessory. The presence of shape-holding foam can be detected at very different rates of stirring. The most intensive foam formation was detected for Eudragit FS 30 D. The Eudragit RL 30 D dispersion was the least sensitive to high-speed mixing. The relative content of the polymer in the foam was higher than that in the liquid. This is indicated by the accumulation of surface-active agent on the surface of the bubbles formed in the foam. This phenomenon differed considerably for the various dispersions. An exact knowledge of the foam formation from aqueous acrylic dispersions is very important in order to determine the parameters of mixing and the quantity of antifoaming agent.

We demonstrated the pulsed laser deposition (PLD) of high quality films of a biodegradable polymer, the polyhydroxybutyrate (PHB). Thin films of PHB were deposited on KBr substrates and fused silica plates using an ArF (λ = 193 nm, FWHM = 30 ns) excimer laser with fluences between 0.05 and 1.5 J cm−2. FTIR spectroscopic measurements proved that at the appropriate fluence (0.05, 0.09 and 0.12 J cm−2), the films exhibited similar functional groups with no significant laser-produced modifications present. Optical microscopic images showed that the layers were contiguous with embedded micrometer-sized grains. Ellipsometric results determined the wavelength dependence (λ ∼ 245–1000 nm) of the refractive index and absorption coefficient which were new information about the material and were not published in the scientific literature. We believe that our deposited PHB thin films would have more possible applications. For example to our supposal the thin layers would be applicable in laser induced forward transfer (LIFT) of biological materials using them as absorbing thin films.

This study contributes to the sustained effort to unravel the chemical structure of graphite oxide (GO) by proposing a model based on elemental analysis, transmission electron microscopy, X-ray dif...

The surface of gloss fired porcelain with and without raw glaze coating was radiated by a CO 2 laser working at 10.6 μm, a choice resulted from spectroscopic studies of suspensions made of China. The shine of the untreated sample was defined as the distribution of micro-droplets on the surface. The surface alterations due to laser heating were classified by the diameter of the completely melted surface, the ring of the surface at the threshold of melting, and the size of microscopic cracks. The diameter of the laser treated area was in the range of 3 mm, while the incident laser power and the duration of laser heating were varied between 1 and 10 W and 1–8 min, respectively. The different stages of surface modifications were attributed primarily to the irradiating laser power and proved to be rather insensitive to the duration of the treatment. We have found a range of parameters under which the white China surface coated with raw glaze and followed by laser induced melting exhibited very similar characteristics to the untreated porcelain. This technique seems prosperous for laser assisted reparation of small surface defects of unique China samples after the firing process.

The permeable polymer film-formation behavior of a Eudragit RS dispersion was investigated in response to stirring at various rates and for various times in an Ultra Turrax instrument. No additives were used. The minimum film-forming temperature of the liquid, the thermal behavior of the film and the compositions of the dispersion and the foam arising were investigated. It was found that, at a given mixing time, shape-retaining foam formation could be detected at over 17,500 rpm. The polymer was enriched in the foam, while its quantity was decreased in the liquid. The minimum film-forming temperature of the liquid phase did not vary significantly, with the exception of the rate of 24,000 rpm, when a uniform film was not formed because of the bubbles. The glass-transition temperatures of the films formed did not exhibit any differences. Film formation was not influenced by the stirring time at a given rate. It was found that the efficiency of homogenization should not be increased by using a high stirring rate, as a uniform, smooth film did not develop, such a film being indispensable to ensure appropriate drug release. Copyright © 2006 John Wiley & Sons, Ltd.

Inclusion complexation between dimethyl-β-cyclodextrin and a very poorly water-soluble serum lipid-regulating agent, gemfibrozil, was studied. Products were prepared by several methods (physical mixing, kneading, spray-drying and ultrasonic treatment) in four different molecular ratios (2:1, 1:1, 1:2 and 1:3). The possibility of complex formation between the drug and the host molecule was studied by thermal analysis. Supplementary techniques, such as Fourier transformation-infrared spectroscopy and X-ray diffractometry, were also applied to interpret the results of thermal study of the products.

We investigate the energy dependence of the UV laser irradiation on DRIFT spectra of wood. Changes in the spectra have been studied with 248.5 nm wavelength of UV laser radiation. To monitor the energy dependence, a different number of laser impulses were directed towards the sample's surface. It can be concluded that several chemical processes contribute to the effect of the UV laser radiation. The processes depend on several factors one of which is the amount of absorbed energy. The characteristics of wood species can be observed mainly at low energy irradiation in the changes of spectra since these characteristics disappear with increased energy, the absorption's changes have become more and more uniform. Recording the spectra of treated sample, the spectra show the degree of the surface's instantaneous degradation. The differences among the observed changes in spectra may originate from both the diversity of the original spectra (the features of wood species and surface properties) and the stage of degradation's degree of sample. Changes in absorption become less pronounced with increasing energy.

The effect of different wavelength UV laser irradiation on DRIFT spectra of lignin extracted from hard wood was investigated. Changes in the spectra of lignin were studied with 308, 248.5, and 193 nm wavelength of UV laser radiation. To monitor the energy dependence, different number of laser impulses reached the sample’s surface. To investigate quantitatively how the absorption does change the band damage index (BDI) is introduced. Fourier deconvolution and fit of mixtures of Gaussians and Lorentzians were used to decompose the difference spectra into two spectra containing the bands changing their intensity to opposite directions, which made us possible to identify the products and the components destroyed. Opening up of the glucopyranose ring is essential starting point of the decomposition process and all further steps are dependent on the energy and intensity of the photons.

The interactions between the cationic polymer chitosan (Chit) and iron(III) were investigated. The solution properties were studied by pH-metry, viscometry and dynamic light scattering. Solid state iron(III)-Chit samples were also prepared and characterized by IR spectroscopy and electron microscopy. In aqueous solutions, the precipitation pH of the iron(III) oxyhydroxide (FeOOH) is significantly shifted towards the higher pH values in the presence of Chit indicating that some interaction takes place between the iron(III) and the polymer. However, the additivity of the pH-metric titration curves, the lack of variation both in the viscometric and IR spectra of Chit in the presence and absence of iron(III), indicate the lack of direct complexation between the Chit and ferric ions. Isolated FeOOH nanospheres of 5-10 nm diameter were observed on the transmission electron microscopic pictures of samples obtained from solutions containing iron(III) and Chit, while from DLS measurements hydrodynamic units with a few hundred nm in diameter were identified. Our data support that Chit acts as steric stabilizer and inhibits the macroscopic aggregation of the subcolloidal FeOOH particles. Thus the iron(III)-Chit interactions offer a simple and economic way to fabricate nanometric size FeOOH spheres, morphologically similar to the core of iron(III)-storage protein, ferritin.

Inclusion complexation between cyclodextrin derivatives (hydroxypropyl-β-cyclodextrin and methyl-β-cyclodextrin) and a very poorly water-soluble antifungal agent, ketoconazole, was studied. Solid products were prepared by physical mixing, kneading and spray-drying methods in four molecular ratios: 2:1, 1:1, 1:2 and 1:3. The possibility of complex formation between the drug and the cyclodextrins was studied by thermal analysis. Supplementary techniques, such as X-ray diffractometry and Fourier transformation-infrared spectroscopy, were also applied to interpret the results of the thermal study of the products.

The structural features of four benzylidene type Schiff bases [(E)-benzaldehyde-N-phenyl imine, (A) (E)-2-hydroxybenzaldehyde-N-phenyl imine (B) (E)-benzaldehyde-N-2-hydroxyphenyl imine (C) (E)-2-hydroxybenzaldehyde-N-2-hydroxyphenyl imine (D)] were studied by FT-IR spectroscopy in solution, photoacoustic and Raman spectroscopies in the solid state and quantum chemical calculations. It was found that molecule D dimerised in the solid state with concomitant loss of aromaticity in the benzylidene ring. Beside the intermolecular C=O...HO hydrogen bonds, intramolecular N-H...C=O hydrogen bonds could be found experimentally as well as computationally. Spectra taken in solution and ab initio quantum chemical calculation helped to identify hydrogen bonding interactions occurring for compounds B and C. Intramolecular OH...N hydrogen bond predominated in molecule B, while this interaction, although it existed, was weaker.

We have analyzed the emerging precipitate pattern of calcium-oxalate in a flow system. The circular symmetry is broken because of the hydrodynamic instability at the tip of the underlying gravity current. The presence of a concentration gradient maintained by the flow leads to the enrichment of the thermodynamically unstable calcium oxalate dihydrate form.

The adsorption of promethazine chloride [10-(2-dimethylammonium propyl) fenothiazine chloride] and buformin hydrochloride (1-butylbiguanidine chloride) on montmorillonite was studied in previous work. The present article focuses on the desorption of these molecules from their organocomplexes in a medium of artificial intestinal juice (pH 7.0 ± 0.1) at the temperature of the human body (37 ± 0.5 °C). The desorption was investigated by kinetic studies, basal spacing measurements and Fourier transform IR studies. Important quantitative differences were observed: buformin, which adsorbed in a monolayer coverage, exhibited a very high desorption rate, whereas promethazine formed a pseudotrilayer arrangement and showed a lower dissolution rate.

Twenty-two samples of zinc carboxylates were prepared from saturated, non-cyclic carboxylic acids with systematically altered hydrocarbon chain structures under well-defined conditions. Essential temperature- and solvent-induced changes concerning the coordination of the carboxylate group are shown using selected prepared samples, and general rules for systems containing zinc carboxylates in nonpolar media are presented. It is shown that there are three possible structural forms for zinc carboxylates: polymeric sheet, polymeric chain, and closed tetranuclear oxo complex molecules. These forms are closely related through their physical and chemical transitions. The results show that the spatial structure of the hydrocarbon chain is a crucial factor, besides physical and chemical conditions, limiting the possible forms of zinc carboxylates present in the system. The principles presented enable us to predict and design the behaviour of a system containing zinc carboxylate additives.

The adsorption of asphaltene on different clay minerals (kaolinite, illite, montmorillonite) and mineral oil reservoir rocks was studied. In toluene solution, specific adsorption was observed on kaolinite and a decrease in adsorption was found in the order illite-montmorillonite. In toluene/n-heptane mixtures a two-stage isotherm was recorded on the surface of the adsorbents. Surface modification by the adsorption of asphaltenes was characterized by a variety of structure-probing methods such as N2-adsorption, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS) measurements, and FTIR spectroscopy. The hydrophobizing effect of asphaltene on clays was also checked by immersion microcalorimetry. According to XRD studies, no intercalation of asphaltene occurs in toluene and toluene/n-heptane mixture on montmorillonites. SAXS scattering curves measured on kaolinite samples deviate from each other in the angle range close to primary scattering, because of the preferential adsorption of asphaltene. The aggregation of clays by asphaltene also manifests itself in a decrease of specific surface areas determined by N2-adsorption.

Polymer-supported oxidic osmium catalysts based on cross-linked poly(4-vinyl pyridine) were synthesized by various routes and characterized by a number of physical techniques (Raman, IR, XPS, 13 C and 15 N solid-state NMR spectroscopy). Model compounds of type Os 2 O 6 L 4 (L = pyridine, 4- iso -propyl pyridine, and 4- tert -butyl pyridine) were obtained under the conditions of the catalyst synthesis. The catalytic systems were successful in the dihydroxylation of alkenes.

The compositions of paraffinic deposits obtained from oil wells and pipelines were studied. It was established that, besides the well-known asphaltene, malthene, resin and paraffin, a hydrophobic paraffin derivative (solid hydrophobic fraction) of higher molar mass and melting point, containing polar end-groups (CO and COO−), can also be isolated. X-ray analyses showed this material to be an organocolloid of lamellar structure. Small angle X-ray scattering measurements demonstrated that the substance readily swells in toluene. When its solutions and its suspensions prepared by cooling are studied in aromatic aliphatic solvent mixtures, they exhibit a great variety of structural characteristics. Optical measurements indicate that its tendency to aggregate is very sensitively affected by the polarity of the hydrocarbon mixture, and by temperature. Its presence at a concentration of 1–2% stabilizes water-in-oil emulsions, which is explained by changes in the colloidal state of the paraffin derivative.