Impact of processing and storage on citrus fiber functionality: Insights from spectroscopic techniques

Excellent hydration properties and oil holding capacity of citrus fiber: Effects of component variation and microstructure

In this experimental study, picosecond laser treatment was performed on a nickel-based superalloy Nimonic 263, aiming to investigate the surface effects induced by irradiation in different atmospheric conditions and, concerning changes in surface composition, regarding the possibility for improvement of its functionality. Besides the varying laser parameters, such as a number of pulses and pulse energy, environmental conditions are also varied. All surface modifications were carried out in standard laboratory conditions and a nitrogen- and argon-rich atmosphere. The resulting topography effects depend on the specific laser treatment and could be categorized as increased roughness, crater formation, and formation of the laser-induced periodic surface structures (LIPSS). Changes in the chemical surface composition are distinguished as the potential formation of the protective oxides/nitrides on the sample surface. Numerous characterization techniques analyse the resulting effects on the topography and surface parameters. The multi-response parametric optimization of the picosecond laser process was performed using an advanced statistical method based on Taguchi’s robust parameter design. Finally, the optimal parameter conditions for Nimonic 263 modification are suggested.

Changes in surface composition and morphology of UF4 targets during heavy ion irradiation

Effects of adding citrus fiber with different chemical compositions and physicochemical properties on the cooking yield of spiced beef

Preferential sputtering in binary targets

The interaction between asphaltenes and clay is crucial in understanding wettability changes in petroleum reservoirs and in oilsands production. In this study, we report the changes in surface properties and composition of kaolin clay as a result of exposure to solutions of asphaltenes. Adsorption experiments were conducted at 25 °C with solutions of asphaltenes in toluene at concentrations ranging from 0.05 to 5 mg/mL. The wettability of the modified kaolinite surface was characterized by contact angle measurement. Chemical composition changes of the surface because of asphaltene adsorption were assessed using time-of-flight secondary ion mass spectroscopy (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), and elemental analysis. The contact angle data indicated that, upon asphaltene adsorption, the clay particles changed from water-wet to bi-wet. Both ToF-SIMS and XPS measurements indicated that the kaolinite surface was never completely covered by asphaltenes based on the concentration of Al and Si on asphaltene-treated kaolinite surfaces. ToF-SIMS analysis indicated that, with more asphaltenes covered on the kaolinite surface, the relative intensities of C3H5+/Al+ and C3H5+/Si+ increased and an inverse linear correlation between the contact angle and surface Si+ concentration was observed. The maximum thickness of adsorbed asphaltenes, assuming complete surface coverage, was estimated to be 11 nm based on XPS depth profile results on a model silica surface, with a mean value of 3 nm. The XPS depth profile also indicated no preferential adsorption of nitrogen- or sulfur-rich species at the interface between asphaltenes and kaolinite.

PEGylated gadolinium carbonate ((Gd2(CO3)3)@PEG) powder was successfully synthesized by a modified solvothermal method. The synthesized products were characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). A systematic change in the chemical surface composition, crystallinity and size properties of the Gd2(CO3)3@PEG particles was observed by increasing the reaction time at 5 hours, 7 hours, and 8 hours. The corresponding XRD patterns showed that the Gd2(CO3)3 particles had hexagonal symmetry (JCPDS No. 37-0559) with a crystallite size of 3.5, 2.9, and 4.6 nm. FTIR spectra showed that the Gd2(CO3)3)@PEG particles were formed with the PEG as carbonyl and hydroxyl group attached to the surface. SEM analysis showed that the Gd2(CO3)3)@PEG particles had a flake-like morphology of homogeneous sized particles and agglomerates. EDS analysis confirmed the presence of constituent Gd2(CO3)3 elements.

Silicone elastomers were surface modified by oxygen microwave plasma under different conditions and the elemental composition was followed by X‐ray photoelectron spectroscopy (XPS). The changes in elemental composition were mapped by a method based on ternary XPS diagrams that we have recently developed. Already at the shortest treatment times, 5 s, the change in surface composition is more than one‐half the maximum change obtained on prolonged exposure. After this initial change, the surface gradually oxidizes toward the final composition. Curve resolutions of C1s and Si2p XPS data showed that the initial jump in surface composition is caused by an oxidation of silicon where one of the two methyl groups are replaced by an oxygen. The second methyl group appears to be more difficult to remove, but as the treatment progresses, the number of oxygen bonded to silicon gradually increases. The dominating form of carbon acts as unoxidized methyl groups throughout the process, but the total carbon percentage decreases as the treatment progresses. This indicates either that the methyl groups are removed without prior oxidation or that the methyl groups are removed shortly after oxidation. A silica‐like surface layer was formed on prolonged plasma treatment under all the investigated conditions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4098–4104, 2004

Neutron reflectivity has been used to study the effect of temperature on the adsorption of non‐ionic surfactants and non‐ionic surfactant mixtures at the air‐water interface. For a range of polyoxyethylene non‐ionic surfactants the adsorption is invariant with temperature in the range 25 to 50 c; however some subtle changes in the structure of the adsorbed layer are observed.For the non‐ionic mixture of monododecyltriethylene glycol, C12EO3, and monododecyloctaethylene glycol, C12EO18, measurements over a wide concentration range, from below to above the cmc (10−5 to 10−2 M), provide a direct qualitative confirmation of the abrupt change in surface composition at the cmc due to the onset on mixed micelle formation predicted recently by Nikas, Puvvada, and Blankschtein, Langmuir, 8 (1992) 2680.For the same non‐ionic mixtures and at concentrations below and above the cmc (at concentrations of 1.25 × 10−5 and 5 × 10−4 M) a change in surface composition with increasing temperature is observed. The surface becomes more rich in the least surface active component, the C12EO8. In the same temperature range the total adsorption from the mixture at the interface decreases slightly.

Biogeochemical transformation (inclusive of dissolution) of iron (hydr)oxides resulting from dissimilatory reduction has a pronounced impact on the fate and transport of nutrients and contaminants in subsurface environments. Despite the reactivity noted for pristine (unreacted) minerals, iron (hydr)oxides within native environments will likely have a different reactivity owing in part to changes in surface composition. Accordingly, here we explore the impact of surface modifications induced by phosphate adsorption on ferrihydrite reduction by Shewanella putrefaciens under static and advective flow conditions. Alterations in surface reactivity induced by phosphate changes the extent, decreasing Fe(Ill) reduction nearly linearly with increasing P surface coverage, and pathway of iron biomineralization. Magnetite is the most appreciable mineralization product while minor amounts of vivianite and green rust-like phases are formed in systems having high aqueous concentrations of phosphate, ferrous iron, and bicarbonate. Goethite and lepidocrocite, characteristic biomineralization products at low ferrous-iron concentrations, are inhibited in the presence of adsorbed phosphate. Thus, deviations in iron (hydr)oxide reactivity with changes in surface composition, such as those noted here for phosphate, need to be considered within natural environments.

Influence of sputtering on the surface composition of MoNi alloys

The study of the reactions of oxygenates on well-defined oxide surfaces is important for the fundamental understanding of heterogeneous chemical pathways that are influenced by atomic geometry, electronic structure, and chemical composition. In this work, an ordered uranium oxide thin film surface terminated in the (100) orientation is prepared on a LaAlO3 substrate and studied for its reactivity with a C-2 oxygenate, ethanol (CH3CH2OH). With the use of synchrotron X-ray photoelectron spectroscopy (XPS), we have probed the adsorption and desorption processes observed in the valence band, C 1s, O 1s, and U 4f to investigate the bonding mode, surface composition, electronic structure, and probable chemical changes to the stoichiometric-UO2(100) [smooth-UO2(100)] and Ar+-sputtered UO2(100) [rough-UO2(100)] surfaces. Unlike UO2(111) single crystal and UO2 thin film, Ar-ion-sputtering of this UO2(100) did not result in noticeable reduction of U cations. Upon ethanol adsorption (saturation occurred at 0.5 ML), ...

Comprehensive investigation of the corrosion state of the heat exchanger tubes of steam generators. Part II. Chemical composition and structure of tube surfaces

XPS Study of Amorphous Fe-T-B/T-Transitions Metals or Rare-Earth/Alloys

The wide‐bandgap GaN semiconductor has been used to fabricate efficient blue–green light‐emitting diodes, laser diodes and high‐power/high‐temperature electronic devices since the many problems regarding the life‐time characteristics were resolved in recent years. Knowledge of ion‐bombardment‐induced surface composition changes is important in quantitative AES/XPS analysis. We investigated the dependence of preferential sputtering of components on ion energies and on the angle of incidence of argon ions. Thin films of GaN prepared on a smooth Si substrate and GaN single crystals were bombarded with argon ions of energy 0.5–5 keV at incidence angles of 10–72° with respect to the surface normal. The N KLL and Ga LMM AES signals were acquired after the steady‐state surface composition was reached. The results show that nitrogen is sputtered preferentially. This effect is more pronounced for higher ion energies and smaller incidence angles. The experimental results are discussed in the framework of models of preferential sputtering and compared with computer simulations. Copyright © 2002 John Wiley & Sons, Ltd.