Effect of hydrolysis time, pH and surfactant type on stability of hydrochloric acid hydrolyzed nanocellulose.

Nanocelluloses are the subject of much interest on the account of their mechanical properties, high surface area, porosity, etc. Typically, sulfuric acid is used to produce cellulose nanocrystals with high aspect ratio and dispersibility in water suspensions. However, hydrolysis in sulfuric acid leads to cellulose esterification, which has some drawbacks such as lower thermal stability of nanocellulose. Hydrochloric acid does not cause functionalization of the nanocellulose surface, yet yields in poor colloidal stability in aqueous solutions due to the lack of ionic interactions between CNC/CNF and water molecules. Therefore, it should be possible to tune the colloidal stability of nanocellulose aqueous suspensions by modifying the properties of the solution (such as pH and/or the presence of surfactants). In this work, we attempted to obtain stable aqueous CNF suspensions via hydrochloric acid hydrolysis. Hydrolysis was performed at three time intervals, at 60 °C temperature and 6 mol/dm3 of hydrochloric acid. To find the optimum stabilizing conditions, the effect of different pH values and various surfactants on CNF stability was explored. The best stabilizing effect was observed at pH range 5-9 and in nonionic surfactant. The obtained products were characterized by using spectroscopic (FTIR), microscopic (AFM), thermogravimetric and X-ray diffraction techniques.

The morphology and application of stem cells in digestive system surgery.

BACKGROUND: Stem cells constitute a group of cells which possess the ability to self-renew as well as the capacity to differentiate into a vast number of different cells within the human organism. Moreover, stem cells are able to undergo a potentially unlimited number of divisions and this characteristic is clinically essential. Specific fields of its application include treatment of diseases mainly in the field of haematology, orthopaedics, surgery, dentistry, and neurology. MATERIALS AND METHODS: In the following work, the current knowledge concerning mechanisms of stem cell treatment in different parts of the digestive system with its diseases as well as adjacent therapy for surgery has been revised. RESULTS: Stem cells therapy may be used in the treatment of various diseases of different parts of the digestive system. This also applies to the end part of the digestive tract (proctological diseases) because stem cells can be used to treat fistulas. Liposuction allows more recovery of mesenchymal stem cells, compared to previous bone marrow harvesting methods. Despite the application of stem cells in the treatment of different diseases used for many years so far, the therapeutic use for the regeneration of the gastrointestinal tract is still rare and unfamiliar. CONCLUSIONS: Regenerative medicine seems to be a promising tool in medical research, especially when insulated cells and designed biomaterials are taken into consideration. Major points of discussion include types of stem cells, their origin or differentiation for the treatment of many diseases.

Spectroscopic studies of MFI and USY zeolite layers over stainless steel 316L wire gauze meshes.

The objective of our study was to develop and optimize the in situ synthesis of zeolitic thin coatings with USY (ultrastabilised form of faujasite) and MFI (Model Five) type structure on metallic structured catalysts supports using the hydrothermal method. Thus, obtained zeolitic materials were studied in terms of their prospective activity in selective catalytic reduction of nitrogen oxides (SCR of NOx) with ammonia. Optimization of the preparation method consisted of several steps including: the pretreatment of steel carrier to obtain an adhesive surface, hydrothermal synthesis of zeolites at different conditions and adjustment of the zeolite structure type (MFI vs. USY). As a result, uniform zeolitic layers were deposited on steel supports. Prepared structured supports were ion-exchanged with copper or cobalt precursors to obtain active catalysts and then characterised by various physicochemical methods with a particular reference to the in situ Fourier-Transform Infrared Spectroscopy (FTIR), Ultraviolet-Visible Diffusion Reflectance Spectroscopy (DRS-UV/VIS) and Raman spectroscopy. For CuUSY sample, slightly better catalytic properties are related to higher copper content. In the case of Co-samples, worse catalytic properties in comparison with Cu counterparts might imply from higher concentration of Brønsted acid sites, lower cobalt loading (thus concentration of Lewis acid sites) and the presence of cobalt cation significantly in oxide form (evidenced by Raman, DRS-UV/VIS spectroscopy and by in situ FT-IR sorption studies).

Investigation of the aluminum oxide content on structural and optical properties of germanium glasses doped with RE ions.

In this paper structural and optical properties of Rare Earth doped (RE) gallo-germanate glasses modified with various amount of Al2O3 have been investigated. Glasses doped with Yb3+, Tm3+, and Ho3+ ions were synthesized to study Al2O3 additive influence on their structural and emission properties in the visible spectral region. MIR spectra indicated that the structure of prepared glasses tends to order and its polymerization along with the aluminum content increase. Glass samples consisting of the low molar content of Al2O3 are characterized by a significant contribution of Tm3+ ions in light emission while Ho3+ ions luminescence dominates in samples consisting of the higher molar content of Al2O3. Additionally, investigation of light emission in visible range showed that samples consisting of the low molar content of Al2O3 are characterized by greenish blue light emission whereas light emitted by samples consisting of 15-20 mol% is much closer to the white colour.

Influence of Ar-ion implantation on the structural and mechanical properties of zirconia as studied by Raman spectroscopy and nanoindentation techniques.

In this study, structural and nanomechanical properties of zirconia polymorphs induced by ion irradiation were investigated by means of Raman spectroscopy and nanoindentation techniques. The zirconia layer have been produced by high temperature oxidation of pure zirconium at 600 °C for 5 h at normal atmospheric pressure. In order to distinguish between the internal and external parts of zirconia, the spherical metallographic sections have been prepared. The samples were irradiated at room temperature with 150 keV Ar+ ions at fluences ranging from 1 × 1015 to 1 × 1017 ions/cm2. The main objective of this study was to distinguish and confirm different structural and mechanical properties between the interface layer and fully developed scale in the internal/external part of the oxide. Conducted studies suggest that increasing ion fluence impacts Raman bands positions (especially characteristic for tetragonal phase) and increases the nanohardness and Young's modulus of individual phases. This phenomenon has been examined from the point of view of stress-induced hardening effect and classical monoclinic → tetragonal (m → t) martensitic phase transformation.

Recognizing ancient papyri by a combination of spectroscopic, diffractional and chromatographic analytical tools.

Ancient papyri are a written heritage of culture that flourished more than 3000 years ago in Egypt. One of the most significant collections in the world is housed in the Egyptian Museum and Papyrus Collection in Berlin, from where the samples for our investigation come. The papyrologists, curators and conservators of such collections search intensely for the analytical detail that would allow ancient papyri to be distinguished from modern fabrications, in order to detect possible forgeries, assess papyrus deterioration state, and improve the design of storage conditions and conservation methods. This has become the aim of our investigation. The samples were studied by a number of methods, including spectroscopic (FTIR, fluorescent-FS, Raman) diffractional (XRD) and chromatographic (size exclusion chromatography-SEC), selected in order to determine degradation parameters: overall oxidation of lignocellulosic material, degree of polymerization and crystallinity of cellulose. The results were correlated with those obtained from carefully selected model samples including modern papyri and paper of different composition aged at elevated temperature in humid air. The methods were classified in the order SEC > FS > FTIR > XRD, based on their effectiveness in discriminating the state of papyri degradation. However, the most trustworthy evaluation of the age of papyri samples should rely on several methods.

Analysis of upconversion luminescence in germanate glass and optical fiber codoped with Yb3+/Tb3+.

In this paper, upconversion (UC) luminescence processes in a GeO2-Ga2O3-BaO glass system codoped with 0.7Yb2O3/(0.07-0.7)Tb2O3 (mol.%) and double-clad optical fiber codoped with 0.7Yb2O3/0.7Tb2O3 (mol.%) were investigated. The highest emission intensity (energy transfer efficiency equals 12.92%) was obtained for 0.7Yb2O3/0.7Tb2O3 codoped glass. Comparative analysis showed significant differences in the shape of luminescence of fabricated germanate glass and optical fiber. Due to dominant transition from D45 sublevel the main green UC peak (Tb3+: D45→F57) of fabricated double-clad optical fiber is shifted by 4 nm toward longer wavelengths.

Structural and optical study on antimony-silicate glasses doped with thulium ions.

Structural, spectroscopic and thermal properties of SiO2-Al2O3-Sb2O3-Na2O glass system doped with 0.2 mol% Tm2O3 have been presented. Synthesis of antimony-silicate glasses with relatively low phonon energy (600 cm(-1), which implicates a small non-radiative decay rate) was performed by conventional high-temperature melt-quenching methods. The effect of SiO2/Sb2O3 ratio in fabricated Tm(3+) doped glass on thermal, structural and luminescence properties was investigated. On the basis of structural investigations decomposition of absorption bands in the infrared FTIR region was performed, thus determining that antimony ions are the only glass-forming ions, setting up the lattice of fabricated glasses. Luminescence band at the wavelength of 1.8 µm corresponding to (3)F4→(3)H6 transition in thulium ions was obtained under 795 nm laser pumping. It was observed that combination of relatively low phonon energy and greater separation of optically active centers in the fabricated glasses influenced in decreasing the luminescence intensity at 1800 nm.

Raman spectroscopy of TiO2 thin films formed by hybrid treatment for biomedical applications.

The paper presents the results of the investigations of the surface layer obtained after application of the combined hybrid method of oxidation in a fluidized bed (FB) and deposition of the oxide coating by PVD technique. The material used in the study was Ti Grade 2. The process of diffusive saturation was carried out in a fluidized-bed reactor at the temperature of 640°C for 8h in air while the top oxide layer was obtained through PVD method - magnetron sputtering using TiO2 target and argon atmosphere with the pressure of 3×10(-2)mbar and the distance between the substrate to the target of 60mm. In order to determine changes in the properties that occur as a result of modification of the Ti surface, the following examinations were carried out by SEM-EDX, X-ray diffraction methods, Raman spectroscopy, Glow Discharge Optical Spectroscopy (GDOS) and Secondary Ion Mass Spectrometry (SIMS). The coatings obtained were characterized by zonal structure comprising the solution zone of Tiα(O) and oxide zone of TiO2 with modifications of rutile and anatase, depending on the oxidation method. It was found that formation of oxide layers using the hybrid method (FB+PVD) leads to limitation of defects in the oxide layer after fluidized-bed thermal treatment and obtaining a uniform, tight coating with improved corrosion properties which are important from the biomedical standpoint.

Spectroscopic studies of electrophoretically deposited hybrid HAp/CNT coatings on titanium.

Carbon nanotubes deposited on the surface of the metal can be used in a wide variety of applications for modern medicine including: sensors and sensor array devices, electrodes for neural system stimulation, scaffolds for improved healing process for bone defects. Additionally it is debated if deposited on the surface of e.g. endoprosthesis, CNT coating can significantly increase the strength of the tissue/bone joint and stimulate a fast integration of the implant and the tissue. The aim of this paper is the analysis of the electrophoretically deposited nanocomposite coating made of hydroxyapatite nanoparticles and carbon nanotubes on the surface of titanium. The paper concentrates on the analysis of the layer's structure and its bioactivity properties. The nanocomposite films were investigated using Raman Spectroscopy as well as AFM and SEM microscopy. The measurements were conducted at every stage of layer preparation and after bioactivity test. Bioactivity was evaluated by in vitro test in Simulated Body Fluid (SBF, 37°C, for 30days). It was shown that hybrid HAp/CNT layers are very attractive materials for modification of the surface of metallic orthopedic implants.

Fabrication and characterization of oxygen - diffused titanium using spectroscopy method.

A thin native oxide film that forms on the titanium surface makes contact with the bone tissue has been considered to be of great importance to successful osseointegration. The study investigated oxygen-diffused grade 2 titanium obtained by introducing oxygen into the titanium crystal lattice using thermal treatment in fluidized bed performed at 610°C and 640°C in 6, 8, 12h. The thermal treatment at different temperatures and different times led to the formation of a TiO2 rutile film on the titanium surface and a concentration gradient of oxygen into titanium (XRD/GID analyses and GDOS results). Moreover Raman spectroscopy results showed that the TiO2 film on the surface titanium was composed of two oxides (TiO2), i.e. anatase and rutile, for the analyzed variants of heat treatment. The aim of the present study was to establish the optimum conditions for obtaining oxygen-diffused TiO2 film. The results obtained in the study demonstrated that the use of a fluidized bed for titanium oxidation processes allows for obtaining uniform oxide layers with good adhesion to the substrate, thus improving the titanium surface to suit biomedical applications.

Preparation and structural studies of black glasses based on ladder-like silsesquioxanes.

Black glasses are very interesting and promising materials from the point of their thermal and mechanical resistance. They can be used as protective layers on different kind of substrates, like steel, titanium, glasses. Controlling amount of carbon introduced to its structure is crucial for the properties of the material. Samples were prepared by sol-gel method using ladder-like silsesquioxanes as precursor and were heat-treated at 800°C in inert atmosphere. Middle infrared, EDX and MAS NMR studies were carried out on heated samples to determine their structure. All methods confirmed presence of Si-C bonds in the resulting material. Theoretical MIR spectrum, of the constructed black glass model, allowed to make a precise assignment of bands in the experimental spectrum.

Spectroscopic characterization of Co3O4 catalyst doped with CeO2 and PdO for methane catalytic combustion.

The study deals with the XPS, Raman and EDX characterization of a series of structured catalysts composed of cobalt oxides promoted by palladium and cerium oxides. The aim of the work was to relate the information gathered from spectroscopic analyses with the ones from kinetic tests of methane combustion to establish the basic structure-activity relationships for the catalysts studied. The most active catalyst was the cobalt oxide doped with little amount of palladium and wins a confrontation with pure palladium oxide catalyst which is commercially used in converters for methane. The analyses Raman and XPS analyses showed that this catalyst is composed of a cobalt spinel and palladium oxide. The quantitative approach to the composition of the catalysts by XPS and EDX methods revealed that the surface of palladium doped cobalt catalyst is enriched with palladium oxide which provides a great number of active centres for methane combustion indicated by kinetic parameters.

Analysis of thermal and structural properties of germanate glasses co-doped with Yb(3+)/Tb(3+) ions.

In the work the new glass compositions in the GeO2-GaO-BaO system have been prepared and thermal, structural properties of in germanate glasses co-doped with Yb(3+)/Tb(3+)ions were studied. Glasses were obtained by conventional high-temperature melt-quenching technique. The study of the crystallization kinetics processes of glasses co-doped with 0.7Yb2O3:0.7Tb2O3 was performed with DSC measurements. The activation energies have been calculated using Freedman analysis and verified with the Flynn-Wall-Ozawa method. In this order, the DSC curves have been registered with different heating rates, between 5 and 15 degrees/min. The structure of fabricated glasses has been studied by infrared and Raman spectroscopes. The effect of heat treatment on the structural properties was determined. In all glass samples the dominated infrared absorbance band at 800cm(-1) corresponds to asymmetric stretching motions of GeO4 tetrahedra containing bridging (Ge-O(Ge)) and non-bridging (Ge-O(-)) oxygens. Additionally, the influence of heat treatment on the luminescent properties was evaluated. Strong luminescence at 489, 543, 586 and 621nm corresponding to (5)D4→(7)FJ (J=6, 5, 4, 3) transitions was measured. The highest upconversion emission intensity was obtained in the germanate glass co-doped with 0.7Yb2O3/0.7Tb2O3.

Studying functional properties of hydrogel and silicone-hydrogel contact lenses with PALS, MIR and Raman spectroscopy.

Determination of free volume holes of the hydrogel and silicone-hydrogel polymer contact lenses were investigated. Two types of polymer contact lenses were used as materials: the first is a hydrogel contact lenses Proclear family (Omafilcon A), while the second is a silicone-hydrogel contact lens of the family Biofinity (Comfilcon A). Positron annihilation lifetime spectroscopy PALS was used to characterize geometrical sizes and fraction of the free volume holes in the investigated samples. There is a clear difference in the free volume sizes and their fractions between silicone-hydrogel and polymer hydrogel contact lenses which in turn are connected with oxygen permeability in these lenses. Apart from that, spectroscopic (middle infrared) MIR and Raman examinations were carried out in order to demonstrate the differences of the water content in the test contact lenses.

Stress analysis of zirconia studied by Raman spectroscopy at low temperatures.

The paper presents effect of low temperature upon location of selected Raman bands. The structural properties of pure zirconium pre-oxidized at 773K and 873K have been studied during cooling in the range of temperatures 273K and 93K by Raman spectroscopy. Analysis of the Raman band positions for the monoclinic phase of zirconia oxide was performed. Raman spectroscopy has shown that monoclinic phase of zirconia oxide undergoes a continuous band displacement, individual for each studied Raman mode. Registered shift is aimed towards the high frequency direction. Recorded Raman band displacement was employed to study stress state in zirconia oxide films grown on pure zirconium developed during control cooling. Presented results showed a good correlation between different thicknesses of the oxide scale.

Voids in mixed-cation silicate glasses: Studies by positron annihilation lifetime and Fourier transform infrared spectroscopies.

PALS in comparison with FTIR studies have been applied to investigate the structure of different oxide glasses. Three components of the positron lifetime τ (τ1 para- and τ3 ortho-positronium and τ2 intermediate lifetime component) and their intensities were obtained. The results of the calculation of mean values of positron lifetimes for the investigated glasses showed the existence of a long-living component on the positron annihilation lifetime spectra. From the Tao-Eldrup formula we can estimate the size of free volume. On the basis of the measurements we can conclude that the size and fraction of free volume reaches the biggest value for the fused silica glass. The degree of network polymerisation increases void size.

Spectroscopic and structural investigation of 2,5-dicarboxy-1-methylpyridinium inner salt.

The structure of 2,5-dicarboxy-1-methylpyridinium inner salt (1), has been studied by X-ray diffraction, B3LYP/6-311G(d,p) calculations, FTIR, Raman and NMR spectroscopy. The molecules are linked by short intermolecular and asymmetric O-H⋯O hydrogen bonds of 2.486(2)Å between carboxyl and carboxylate groups of neighboring molecules into infinite chains. The hydrogen bonds in the molecules optimized by the B3LYP/6-311G(d,p) approach in trimer (2) and dimer (3) are slightly longer than in the crystal. The FTIR spectrum of the investigated inner salt is dominated by a broad and intense absorption in the 1500-800 cm(-1) region attributed to the ν(as)(OHO) and γ(OHO) vibrations of the strong hydrogen bond. In the Raman spectrum the broad absorption is absent. Linear correlations, δ(exp)=a+b σ(calc) between the experimental (1)H and (13)C NMR chemical shifts (δ(exp)) of the investigated inner salt in D2O and the calculated magnetic isotropic shielding constants (σ(calc)) for the optimized monomer (4a) solvated in water are reported. The pKa value for 1 of 2.31±0.02 was determined by the potentiometric titration.

Moganite in selected Polish chert samples: the evidence from MIR, Raman and X-ray studies.

The authors discuss the results of structural investigations (XRD, MIR, Raman) of Polish cherts from different geological formations. The X-ray diffraction analyses explicitly confirmed the presence of moganite, which was identified on the basis of satellite XRD peaks positioned/occurring close to the quartz reflections and the additional reflections with the dhkl values 4.456 and 3.101 Ǻ, and established its amounts as varying between about 1 and above 17 wt%. The mid-infrared and Raman spectroscopy also proved the presence of moganite, indicated by the 695 and 560-555 cm(-)(1) bands, respectively. These analytical finds allow to identify moganite in samples containing various SiO2 polymorphs.

Structure and conformation of 2,3-diethoxycarbonyl-1-methylpyridinium iodide studied by NMR, FTIR, Raman, X-ray diffraction and DFT methods.

Computational and spectroscopic properties of 2,3-diethoxycarbonyl-1-methylpyridinium iodide, 1, were studied. The crystal structure of 1 was analyzed by X-ray diffraction. Molecular geometry of title compound has been calculated using the density functional theory (DFT) at B3LYP/6-311G(d,p) level of theory and was compared with the experimental data. Iodide anion interacts electrostatically with the positively charged pyridinium nitrogen atom and via weak CH⋯I(-) hydrogen bonds. In crystals the N-methyl and ethoxycarbonyl groups are disordered in two orientations. The structures of 2 (in vacuum), 3 (in CHCl3) and 4 (in DMSO) optimized by the B3LYP/6-311G(d,p) approach are different than that in crystal 1. The experimental (13)C and (1)H chemical shifts (δexp) of the investigated ester in CDCl3 and DMSO-d6 correlate linearly with GIAO/B3LYP/6-311G(d,p) magnetic isotropic shielding constants calculated according to the screening solvation model (COSMO), δexp=a+b σcalc. The FTIR and Raman spectra of the solid compound are consisted with the X-ray structure.