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Achieving Efficient Red-Emitting Sr(2)Ca(1-delta)Ln(delta)WO(6):Mn4+ (Ln = La, Gd, Y, Lu, delta = 0.10) Phosphors with Extraordinary Luminescence Thermal Stability for Potential UV-LEDs Application via Facile Ion Substitution in Luminescence-Ignorable Sr2
No full textIn this work, we adopt a facile rare earth ions Ln(3+) (Ln = La, Gd, Y, Lu) substitution strategy to achieve the efficient red luminescence Sr(2)Ca(1-delta)Ln(delta)WO(6):Mn4+ (delta = 0.10), which extremely improves the luminescence properties of luminescence-ignorable Sr2CaWO6:Mn4+. It is demonstrated that the substitution of Ln(3+) for Ca2+ can stabilize the Mn in tetravalent state, which would like to occupy W6+ site and generate the luminescence. It is also found that the emission profile of original Sr2CaWO6:Mn4+ changes manifestly after different Ln(3+) ions substitution, which is mainly attributed to the synergistic effect of lattice distortion, Mn4+ transition E-2(g) -> (4)A(2g) and lattice vibration. Most fascinatingly, the Sr(2)Ca(0.9)Ln(0.1)WO(6):0.005Mn(4+) (SC(0.9)Ln(0.1)WO:0.005Mn(4+), Ln = La, Gd) show extraordinary luminescence thermal stability, whose integrated emission intensity still maintains about 95% (Gd, 96.8%; La, 94.8%) at 478 K of its original value at room temperature (298 K), much better than those in most reported M4+-activated oxide phosphors so far. It is confirmed that the traps may play an important role for this phenomenon. Best of all, this work gives us a facile strategy to achieve efficient Mn4+-activated red-emitting materials with extraordinary luminescence thermal stabilities derived from luminescence-ignorable ones
Thermal properties of 3-hydroxy fatty acids and their binary mixtures as phase change energy storage materials
No full textIn the present work, we describe the chemical synthesis of 3-HFAs as prominent derivatives of fatty acids and assess if they could be applied as phase change materials (PCM). In addition, 3-HFAs were obtained by depolymerization of a bacterial biopolymeric material, polyhydroxyalkanoate. Thermal properties of 3-hydoxyoctanoic, decanoic, and dodecanoic acids are reported for the first time. These materials showed the potential to be applied as PCM in temperature range from 33 degrees C to 66 degrees C. In order to expand the temperature range for application of 3-HFAs as PCM, eutectic mass ratios of three kinds of binary mixtures of 3-HFAs were calculated, and their properties were predicted using the Schroder-van Laar equation. Thermal properties of these mixtures were validated by differential scanning calorimetry (DSC) analysis. These results showed that eutectics considerably expanded the scope of applications of 3-HFAs as PCMs. 3-HFAs originating from biotechnologically obtained polyhydroxyalkanoates also showed potential to be applied in development of PCMs
Synthesis and Structural Characterization of Lanthanide-Containing Polytungsto-antimonate [{Sb-3(mu(3)-O)(2)Ln(H2O)Ln(H2O)(2)}(2)(SbW10O37)(2)(SbW8O31)(2)](22)(-)Molecules Deriving from the Decomposition of the [Sb8W36O132](24)(-)Macroanion
No full textReaction of the tungsto-antimonate [Sb8W36O132](24-)polyoxometalate with late trivalent lanthanide cations (from Gd to Lu) gives rise to the formation of eight isostructural molecular compounds [{Sb-3(mu(3)-O)(2)Ln(H2O)Ln(H2O)(2)(SbW10O37)(SbW8O31)}(2)](22-)(Ln = Gd-III(1), Tb-III(2), Dy-III(3), Ho-III(4), Er-III(5), Tm-III(6), Yb-III(7), Lu-III(8)). All compounds were characterized by routine solid-state techniques (IR spectroscopy, TGA, single-crystal X-ray diffraction) and, by SAXS measurements in aqueous solutions to assess their stabilities. Luminescent properties of compounds5and7were also studied
Thermo-responsive hydrogels based on poly(N-isopropyl- acrylamide) and hyaluronic acid cross-linked with nanoclays
No full textSemi-interpenetrating polymer networks (SIPN) based on thermo-responsive poly(N-isopropylacrylamide) (PNIPA) and water-soluble sodium salts of linear hyaluronic acid (Na-HA) were physically cross-linked with synthetic nanoclay (laponite XLG). PNIPA hydrogels with different cross-linking densities and Na-HA concentrations were synthesized by in situ free-radical redox polymerization. The structure and heterogeneity of the semi-IPN hydrogels were examined by SEM and XRD. The content of clay incorporated in the gel was determined by TGA. DSC measurements showed that volume phase transition temperature and its enthalpy varied with the clay and hyaluronic acid content. SIPN hydrogels containing negatively charged polyelectrolyte, Na-HA, exhibited higher Q(e) and faster deswelling rates than the corresponding PNIPA NC hydrogels. The presence of the anionic Na-HA polymer reduced the storage modulus, indicating a weakening of the hydrogel network structure, especially at lower clay contents. The nanocomposite hydrogels exhibited high tan delta values, which increased with increasing Na-HA content
Wheat protein fraction to grain quality characteristics of soft albanian wheat
No full textThe classical Osborne wheat protein fraction (albumins, globulins, gliadins, glutenins), modified according Maes and chemical - technological characteristics, were determined in ten lines of soft wheat, collected during the summer season of 2014. The solvent, used during the process of extracting proteins from wheat flour, consisted of distilled water, 40% isopropyl alcohol, 3.85% lactic acid and 0.5% potassium hydroxide. Wheat lines investigated in the experiment was carried out as a randomized block design in 3 m(2) plots with three replicates. The flour obtained from those lines of wheat has the following quality: protein: 15.05%. Zeleny Sedimentation: 47 ml and gluten index (GI): 53.95%. The protein extraction with this procedure was efficient and provided 90-99% protein recovery
Sustainable development of pressure equipment using 3d digital image correlation method
No full textAs pressure equipment is most commonly used in various industrial fields, making manufacturing processes eco-friendlier (e.g., mass reduction of the final product, material and energy savings, etc.) and transitioning to sustain-able production by developing eco-innovative products will have a positive effect on the environment. The aim of this paper is to analyze globe valve housing exposed to internal pressure using full-field experimental 3D digital image correlation (3D-DIC) method and numerical strain and stress data in order to propose improvements for more sustainable development, with respect to practical engineering application of EN standards. The highest von Mises strain values around 0.03% were measured on the point of highest geometrical discontinuity, sphere/cylinder intersection. Stresses of the examined globe valve using numerical and theoretical approach are significantly below material yield limit and allowable stress for internal pressure values of 30 bar, that is significantly higher than nominal operating pressure of 6 bar, proving that structure is over-dimensioned and can be optimized. New experimental procedure development and application in full-field strain analysis contributes to increased valve housing reliability, mass reduction and material and energy savings during manufacturing which directly affects its eco- friendliness, lowers manufacturing price and increases market competitiveness
Boosting the Er3+ 1.5 mu m Luminescence in CsPbCl3 Perovskite Nanocrystals for Photonic Devices Operating at Telecommunication Wavelengths
No full textCsPb(Cl1-xBrx)(3) perovskite nanocrystals (NCs) doped with Yb3+ ions have recently attracted large attention for their applications in photovoltaics in view of the high quantum yield, exceeding 100% of Yb3+ emission at similar to 1 mu m. In contrast, the particularly relevant Er3+ emission at 1.5 mu m in the third telecommunication window, of high interest in silicon integrated photonics, has been so far largely neglected in view of the weak emission performance displayed by Er3+-doped NCs. Comprehensive steady-state and time-resolved spectroscopic measurements provide insights into the underlying mechanisms of Yb3+ and Er3+ sensitization to rationalize the anomalous different behavior of these two emitters in singly doped NCs. We propose that single-photon excitation of two Yb3+ ions possibly occurs through a transient internal redox mechanism in the perovskite host, while this pathway is unviable for Er3+. In turn, Yb3+-bridged Er3+ sensitization, boosts the Er3+ luminescence at similar to 1.5 mu m by 10(4)-fold compared to Er(3+ )singly doped NCs, and a relative high quantum yield of similar to 6% and extremely long lifetime (similar to 3 ms) are obtained. The resulting high Er3+ excited state densities, combined with the large absorption cross-sections of the semiconducting CsPbCl3 matrix make Er3+-doped perovskite promising innovative materials to realize photonic devices operating at telecommunication wavelengths
The effect of osmotic dehydration and starch coating on the microbiological stability of apples
No full textU ovom radu ispitan je uticaj osmotske dehidratacije u melasi šećerne repe i skrobnog premaza na mikrobiološku stabilnost jabuka. Polovina osmotski tretiranih/netretiranih uzoraka dodatno je zaštićena skrobnim premazom. Uzorci su upakovani u polipropilenske kesice u atmosferskim uslovima i skladišteni 10 dana na sobnoj temperaturi. Uzorcima je određena aw vrednost i mikrobiološki profil. Rezultati su pokazali da E. coli, Salmonella spp. i L. monocytogenes nisu detektovane ni u jednoj grupi uzoraka. Enterobacteria nisu kvantifikovane u uzorcima OD i OD+P tokom celog perioda skladištenja, dok su prisutne u uzorcima K i P u prva četiri dana sa opadajućim trendom, a kasnije se nisu mogle detektovati. Ukupan broj bakterija je ujednačen u okviru svake grupe uzoraka, a vrednosti su značajno veće kod K i P uzoraka. Kvasci i plesni su prisutni u K i P uzorcima tokom celog perioda skladištenja sa maksimalnom vrednošću 170.000 cfu/g za K uzorak u desetom danu skladištenja. Kod OD i OD+P uzorka kvasci i plesni su detektovani tek nakon četvrtog dana i dostigli su veću vrednost kod OD+P uzorka (120.000 cfu/g) nego kod OD uzorka (26.000 cfu/g). Uočena pojava kvasaca i plesni je posledica pogodne aw vrednosti za njihov razvoj. Kod uzorka OD+P veći broj kvasaca i plesni je posledica prisutva skrobnog premaza polisaharidne prirode koji predstavlja pogodan supstrat za razvoj inicijalno prisutnih kvasaca i plesni. Rezultati su pokazali da je OD pogodna metoda za očuvanje mikrobiološke stabilnosti, dok skrobni premaz nije opravdao svoju namenu.This paper examines the effect of starch coating and the osmotic dehydration in sugar beet molasses on the microbiological stability of apples. One-half of the osmotically treated/untreated apples were protected by starch coating, resulting in four sample groups (namely the K, P, OD and OD+P sample groups). E. coli, Salmonella spp. and Listeria monocytogenes were not detected in any of the samples. Enterobacteria were present in the K and P samples in the first four days (indicating a downward trend), but were not subsequently detectable. The total number of microorganisms (TVC) was found to be uniform in each sample group. However, the TVC values were significantly higher in the K and P sample groups than those of the OD and OD + P samples. Yeasts and molds were detected in the K and P samples, whereas the presence of yeasts and molds in the OD and OD+P samples was confirmed only after four days of storage. The results obtained indicate that osmotic dehydration is a suitable method for maintaining microbial stability, whereas starch coating did not justify its purpose
QSRR Model for predicting retention indices of Satureja kitaibelii Wierzb. ex Heuff. essential oil composition
No full textA prediction model of retention indices of compounds from the aboveground parts of Satureja kitaibelii essential oil, obtained by hydrodistillation and analysed by Gas Chromatography coupled with Mass Spectrometry (GC-MS), was the aim of this study. The quantitative structure-retention relationship was employed to predict the retention time using five molecular descriptors selected by a genetic algorithm. The selected descriptors were used as inputs of an artificial neural network. Total of 53 experimentally obtained retention indices (log RI) were used to build a prediction model. The selected descriptors were used as inputs of an artificial neural network model, to build a prediction time predictive quantitative structure-retention relationship model. The coefficient of determination for the training cycle was 0.962, indicating that this model could be used for prediction of retention indices for S. kitaibelii essential oil compounds
Application of lyophilized plum pomace as a functional ingredient in a plum spread: Optimizing texture, colour and phenol antioxidants by ANN modelling
No full textIn order to produce a high quality plum spread, plum pomace lyophilisate (PPL: 2-10%), sugar (sucrose: 10-15%) and amidated low-metoxyl pectin (LMA: 0-0.2%) were investigated as independent variables in optimization of product formulations. Plum spread was characterized in respect to chemical (total phenolic content, total flavonoid content, total monomeric anthocyanins, antioxidant activity), textural (maximal force, work of penetration, work of adhesion, intersection time and intersection force) and colour (L*, a*, b*, chroma and hue angle) parameters. An empirical model was developed that gave a good fit to experimental data and was able to predict all responses of investigated plum spreads successfully. The artificial neural network model showed a reasonably good predictive capability (r(2) was 0.888). The developed mathematical model provided adequate precision for practical use in the food industry. Optimal quality parameters surveyed in this experiment were reached with 10% of PPL, 15% of sucrose and 0% of LMA