Investigation on the Crystallization Process of Eu3+\text{}^{3+}:CaSiO3\text{}_{3} Gel Using Optical and Thermal Methods

Alkoxy sol-gel technique is an important preparation method for production of rare-earth based phosphors. Crystallization of gel provides a way to prepare phosphors on lower working temperatures than those required for the solid state reactions. CaSiO$\text{}_{3}$ gel samples were obtained through hydrolysis-condensation reactions of tetraethylorthosilicate as silica source. In this work we studied the process of crystallization of Eu$\text{}^{3+}$-activated CaSiO$\text{}_{3}$ gel and decomposition of organic precursors by means of thermal analysis and infrared spectroscopy. Results of scanning electron microscopy and energy-dispersion spectrometry are used to check chemical composition and morphology of synthesized material. Emission spectra and emission lifetime measurements are performed to investigate luminescence properties of Eu$\text{}^{3+}$ doped CaSiO$\text{}_{3}$ powder

Polycrystalline (Y0.7Gd0.3)(2)O-3:Eu3+ ceramics fabricated by Spark Plasma Sintering: Densification and microstructure development

Using Spark Plasma Sintering it is possible to produce polycrystalline ceramics of very fine microstructure and good mechanical properties. This work presents the fabrication of such ceramics using Eu3+-doped (Y0.7Gd0.3)(2)O-3 nanopowder as a starting material. We monitored the changes in the morphology of ceramic samples and their consolidation with additional thermal treatments at 650 degrees C and 1100 degrees C. The ceramics grain size remained in the sub-micron domain, even when elevated temperatures were used for annealing. The best results were obtained for the sample sintered at 1100 degrees C for 20 min, which had the smallest grain size, theoretical density, and the most intensive photoluminescence, along with the maximum hardness and appropriate fracture toughness. The Judd-Ofelt intensity parameters and branching ratios were calculated, taking into account the difference in the effective refractive index for the nanopowder and ceramic samples

The relationship between the loess stratigraphy in the Vojvodina region of northern Serbia and the Saalian and Rissian Stage glaciations – a review

Publication status: PublishedThe regional loess stratigraphy in the Vojvodina region, in the southeastern Carpathian Basin, has often been successfully correlated to the global palaeoclimate. This is a quasi‐continuous sedimentary record that provides detailed environmental reconstruction during the last four glacial/interglacial cycles. In this study, we present a standardized loess stratigraphy and illustrate how it correlates with the marine oxygen isotope and Chinese loess stratigraphical records. We argue that the loess stratigraphy in Vojvodina region is an important link in the integration of European terrestrial stratigraphical schemes and the deep‐sea stratigraphical model. We highlight how the loess record can better illustrate terrestrial environmental change through multiple glacial cycles than other records, such as glacial records. The investigated loess record enables direct links to be made between the loess sediments and their glacial sources. This reveals evidence of glaciations during every glacial cycle of the Saalian Stage complex, equivalent to Marine Isotope Stage (MIS) 10, 8 and 6. Therefore, Serbian loess has the potential to provide a direct link between terrestrial glaciations and wider records of global climate change, which is an enigma for many other continental records. These loess records display a strong relationship with the intensity of European glaciations during different glacial cycles. Loess sedimentation rates are highest in the most intensive European glaciation of the Saalian complex (MIS 6) and much lower during the weaker ‘missing’ glaciations equivalent to MIS 8 and 10. A key observation from the Vojvodina loess is the gradual increase in interglacial aridity through the late Middle Pleistocene. The explanation for the progressively increasing aridity in the investigated region at this time is still unclear. However, this trend is consistent with the idea of the Saalian complex as representing a 400 ka mega glacial cycle modulated by shorter classic 100 ka glacial cycles.</jats:p

Field Dodder Life Cycle and Interaction with Host Plants

Cuscuta as a generalist type of holoparasitic plant interacts with various hostplants in different manners, and all Cuscuta species depend (absolutely) on hostplants to complete their life cycle. Field dodder is a parasitic plant that attaches tostems and leaves of broadleaf plants, including weeds, field crops, vegetables, andornamentals, across most agricultural regions of the world. Most hosts of Cuscutaplants are passive, only a few hosts are known to show clear resistance (e.g.,Ipomoea sp.). Unlike other weeds occurring in anthropogenic habitats that havebeen well-studied in their taxonomic, biological, and ecological aspects, as wellas their anatomical and physiological properties to some extent, the parasiticflowering species of the genus Cuscuta have been examined very scarcely despitethe great damage that they are able to cause. More extensive research is required in order to develop new means for parasitic weed control. A basic research shouldidentify new targets for control within the life cycle of the parasites and amongtheir metabolic activities