Spectral-luminescent properties of orthorhombic and monoclinic tungstate and molybdate crystals doped with europium, terbium, thulium, and ytterbium ions

Aquest treball tracta d'un estudi exhaustiu de les propietats espectral-luminiscents de nous cristalls de tungstat i molibdat ortoròmbics i monoclínics de baixa simetria dopats amb ions europi, terbi, tuli i iterbi, incloent-hi l'estudi de l'anisotropia de les propietats espectral-luminiscents, la determinació de les principals característiques espectroscòpiques, així com la determinació de la possibilitat d'utilitzar aquests cristalls com a medi làser actiu per a les regions espectrals visibles i properes a IR i obtenir làser en aquests materials, inclosa en la configuració microxiplàser. Els principals resultats de l'estudi:Els principals resultats de l'estudi: 1. Les principals característiques de luminescència espectral dels ions europi, terbi, tuli i iterbi en cristalls de tungstat dobles KY(WO4)2, KLu(WO4)2, cristalls de molibdats dobles KY(MoO4)2, CsGd(MoO4)2 i vidres de tungstat de zinc ZnWO4. 2. S'ha determinat per primera vegada la divisió Stark dels multiplets i l'amplada de la línia de fonons zero dels ions Yb3+ en els cristalls ZnWO4 i KY(MoO4)2.Este trabajo trata de un estudio exhaustivo de las propiedades luminiscentes espectrales de los nuevos cristales de molibdato y tungstato ortorrómbicos y monoclínicos de baja simetría dopados con iones de europio, terbio, tulio e iterbio, incluyendo tanto el estudio de la anisotropía de las propiedades luminiscentes espectrales, la determinación de las principales características espectroscópicas, así como determinar la posibilidad de utilizar tales cristales como medio láser activo para las regiones espectrales visible e infrarroja cercana y obtener láser en estos materiales, incluso en la configuración microchip-láser. Los principales resultados del estudio:1. Las principales características de luminiscencia espectral de los iones europio, terbio, tulio e iterbio en cristales de tungstato dobles KY(WO4)2, KLu(WO4)2, cristales de molibdatos dobles KY(MoO4)2, CsGd(MoO4)2 y cristales de tungstato de zinc ZnWO4. 2. La división de Stark de multipletes y el ancho de la línea de fonón cero de los iones Yb3+ en cristales de ZnWO4 y KY(MoO4)2 se han determinado por primera vez. Se encontró que el mecanismo heterovalente de sustitución en los cristales de ZnWO4 conduce a un notable ensanchamiento de la línea de fonón cero y a un alto valor de la división de Stark de los multipletes Yb3+.This work deals with an exhaustive study of the spectral luminescent properties of the new crystals of low symmetry monoclinic orthorhombic molybdate and tungstate doped with ions of europium, terbium, thulium and ytterbium, including both the study of the anisotropy of the spectral luminescent properties, the determination of the main spectroscopic characteristics, as well as determine the possibility of using such crystals as active laser medium for the visible and near-infrared spectral regions and obtain lasers in these materials, even in the microchip-laser configuration. The main results of the study:1. The main spectral luminescence characteristics of europium ions, terbium, thulium and ytterbium in double tungstate crystals KY(WO4)2, KLu(WO4)2, double molybdate crystals KY(MoO4)2, CsGd(MoO4)2 and ZnWO4 zinc tungstate crystals. 2. The Stark division of multiplets and the width of the zero phonon line of Yb3+ ions in ZnWO4 crystals and KY(MoO4)2 have been determined for the first time. It was found that the heterovalent mechanism of substitution in the ZnWO4 crystals leads to a remarkable broadening of the zero-phonon line and a high value of the division of Stark of the Yb3+ multiplets

Dievo įvaizdis Franzo Werfelio darbuose

F. Werfel (1890-1945) – a representative of Austrian expressionism. A Jew by birth, he was interested in theology from an early age. One of the main themes of his work was the theme of man’s faith in God. The religious quest of Franz Werfel, depending on his life circumstances (military service, marriage to a Catholic, the death of his son) and world cataclysms (World War I, the breakup of Austria-Hungary) passed through periods of faith in God, his strength, and doubts about his justice (“The Creation of Music” 1913, “The Death of Moses” 1914, “Theology” 1914, “The Creation of Joke” 1918, “The Blasphemy of Madness” 1918) and the denial of the existence of God in general (“The Black Mass” 1919, “The Man from the Mirror” 1920). God appears in the novels and dramas of Werfel then as an evil and unjust judge and executioner, then as a mad beggar, and then as the creator of beauty. In this work, we want to explore in detail the causes of Werfel’s religious offerings, the stages in the evolution of his attitude towards God, and changes in the image of God in his novels and plays.Ekspresionizmo plėtra Austrijoje pirmiausia siejama su XX a. istoriniais įvykiais. Pirmasis pasaulinis karas, Austrijos-Vengrijos likvidavimas, monarchijos nunykimas – visa tai sudarė prielaidas formuotis dvasios ir sąmonės bei tikėjimo krizei. Egzistencinė krizė privertė ekspresionistų rašytojus ieškoti savo darbuose „naujo žmogaus“, mesijaus, galinčio pakeisti pasaulį. Darbai vienu metu atskleidžia Dievo ir religijos apskritai neigimą ir gilų tikėjimą Dievo galia. Ryškus Austrijos ekspresionizmo atstovas yra žydų kilmės F. Werfelis (1890–1945). Jis domėjosi teologija nuo ankstyvo amžiaus. Viena iš pagrindinių jo darbo temų – žmogaus tikėjimas Dievu. Religinės Franzo Werfelio paieškos lemtos jo gyvenimo aplinkybių (karinės tarnybos, katalikiškos santuokos, sūnaus mirties patirtys) ir pasaulio kataklizmų (Pirmasis pasaulinis karas, Austrijos-Vengrijos žlugimas). Pirmuose savo darbuose Werfelis bando interpretuoti Dievo netobulumo idėją. Kaip įrodymus jis cituoja Biblinį žmogaus trėmimo iš Rojaus epizodą. Teigiama, kad jei žmogus yra sukurtas pagal Dievo įvaizdį, kaip jis galėjo pažeisti Dievo tvarką ir trokšti draudžiamo vaisiaus? Ar tai reiškia, kad padaryta kūrėjo klaida? Werfelio romanuose ir dramose Dievas pasirodo ir kaip blogis, ir neteisingas teisėjas, ir budelis, kartais menko įžvalgumo, kaip grožio kūrėjas. Šiame darbe ketinama nagrinėti Werfelio religinių haliucinacijų priežastis, jo santykių su Dievu evoliuciją, Dievo įvaizdžio romanuose ir pjesėse pokyčius. Werfelis kreipia skaitytoją prie išvados, kad pats žmogus gali atpirkti savo nuodėmes ir būti išgelbėtas. Nepaisant to, Werfelis savo romanuose nuolat grįžta prie Dievo įvaizdžio. Paskutinis romanas religine tema buvo jo knyga „Bernadetų dainos“, parašytas 1941 metais. Autoriaus religines nuostatas galima įžvelgti visame jo kūrybiniame kelyje. Werfelis apibūdina galingą Dievą, sprendžiantį žmonių likimus, ir silpną Dievą, atgailaujantį dėl savo trūkumų ir silpnumo. Viešpats rodo demoniškas savybes, atskleidžiančias žmogaus nuodėmes. Galiausiai, Dievo įvaizdį pakeičia „naujojo žmogaus“ įvaizdis, kuris sugeba išsigelbėti per atgailą. Werfelis sugrįžta prie tikėjimo Dievu ir žmogumi, gebančiu išsaugoti savo sielos skaistumą pilname žiaurumo ir neteisybės pasaulyje

Development of sers substrates based on nanoparticles obtained by pulsed laser ablation

SERS spectroscopy is an effective method for the determination of organic and biological compounds, which finds its place in many areas of human life: the analysis of works of art and food 24 YOUNG SCIENTISTS SESSION SESSION Y products, the identification of drugs and drugs, the study of biological structures, incl. at the cellular level. The creation of simple and effective SERS substrates is an urgent task in the development of this method. This paper presents the results of a study of SERS substrates based on gold nanoparticles (NPs). Gold NPs were obtained by pulsed laser ablation of an Au metal target in alcohol using a Nd:YAG laser (1064 nm, 7 ns, 150 mJ). The resulting colloidal solution was applied onto glass substrates by the drop method, varying the number of layers. The SERS characteristics were studied using a model dye rhodamine 6G using Renishaw inVia Basis Raman microscope. The samples were excited in the region of surface plasmon resonance of gold by laser radiation of 532 nm. The results of the study showed that with an increase in the number of deposited layers up to 5, the intensity of the Raman scattering of the dye increases linearly. With a further increase in the number of layers, the signal saturates. This data correlates with SEM data. At the beginning, an increase in the packing density of NPs in the plane of the substrate is observed. Accordingly, the number of "hot spots" increases, which contribute to the amplification of the signal. Further, the homogeneity of the NP layer deteriorates, and large bulk agglomerates appear. Thus, we have developed a simple method for obtaining SERS substrates, which made it possible to increase the signal intensity up to three orders of magnitude

New Combined Technology of Deformation “Rolling-Equal Channel Angular Pressing”, Allowing to Obtain Metals and Alloys with Sub-Ultra-fine-Grained Structure

In this chapter, results of theoretical and laboratory research of combined process “rolling-pressing” using equal-channel step matrix are described. In theoretical studies, the empirical dependences for determining forces of rolling, extrusion, and back pressure in the matrix have been obtained. A program was compiled for finding the optimal value of the angle of intersection of channels in the matrix. In the study of kinematic parameters of the process were obtained formulas for determining diameters of the rolls, the values of which would provide the best capture angle of the workpiece. During computer simulation, the parameters of stress-strain state, temperature distribution, and the influence of the tilting of the workpiece on the process parameters were studied. In the laboratory experiment, the effect of the new combined deformation process “rolling-pressing” on the evolution of microstructure of copper was studied

Investigation of the stress-strain state of balls under deformation in a closed die

The paper presents the results of the study of the production process of balls in a special closed die, which performs a full compression due to the alternate insertion of rams. The possibility of implementing the proposed method is proved experimentally, and the presence of high compressive stresses in the deformation center is shown using the method of sliding lines and mathematical computer modeling. Due to the alternate insertion of rams, the process of plastic deformation is intensified, which makes it possible to obtain high-quality balls. The maximum average stress in the deformation center obtained by the theoretical calculation method of sliding lines is – 436,94 MPa, and the values obtained by mathematical computer modeling is – 500 MPa. Metallographic analysis showed that the grain diameter of the obtained ball samples in the central part, compared to the initial samples, was crushed 3 times (up to 5 μm)

Recycling of stainless steel bar scrap by radial-shear rolling to obtain a gradient ultrafine-grained structure

The paper presents the results of the conducted experiments confirmed not only the possibility of processing bar scrap from stainless metals to produce a marketable product, but also confirmed the possibility of obtaining highquality bars with a gradient fine-grained structure and an increased level of mechanical properties. In the course of the research conducted on deformed bar scrap in the form of pins from 12X18N9T austenitic stainless steel at the radial-shear rolling mill the microstructure of two different types was obtained: on the periphery - equiaxed ultrafine- grained structure with a grain size of 0,4 – 0,6 μm; in the axial zone - oriented striped texture. This discrepancy in the structure of the peripheral and axial zones, together with the results of microhardness measuring across the cross section of samples with a total degree of deformation of 44,4 %, indicates the gradient nature of the formed microstructure