Tm,Ho:Ca(Gd,Lu)AlO4 crystals: Crystal growth, structure refinement and Judd-Ofelt analysis

“Mixed” calcium rare-earth aluminate laser host crystals Ca(Gd,Lu)AlO4 (CALGLO) with up to 10.8 at.% Lu codoped with Tm3 + and Ho3 + ions are grown by the Czochralski method along the [001] direction. The segregation of rare-earth ions is studied. The crystal structure is refined by the Rietveld method. Tm,Ho:Ca(Gd, Lu)AlO4 crystallizes in the tetragonal system (sp. gr. I4/mmm) exhibiting a K2NiF4 type structure. The lattice constants are a = 3.6585(6) Å and c = 11.9660(9) Å for a crystal with a composition of CaG-d0.8947Lu0.0551Tm0.0448Ho0.0054AlO4. The stability of Ca(Gd,Lu)AlO4 solid-solutions is discussed. The polarized Raman spectra are measured, revealing a most intense mode at 311 cm 1 and a maximum phonon frequency of ~650 cm 1. The polarized absorption spectra are measured. The transition intensities for the Ho3 + ion are analyzed using the modified Judd-Ofelt theory accounting for configuration interaction

Growth, spectroscopy and first laser operation of monoclinic Ho3+ :MgWO4 crystal

A monoclinic 0.86 at.% Ho3+:MgWO4 crystal is grown by the Top-Seeded-Solution Growth method. Its spectroscopic properties are studied with polarized light for E || a, b, c. The Ho3+ ion transition probabilities are determined within the modified Judd-Ofelt theory (mJ-O) accounting for the configuration interaction. The intensity parameters are Ω2 = 21.09, Ω4 = 4.42, Ω6 = 2.28 [10–20 cm2] and α= 0.053 [10-4cm]. The calculated radiative lifetime of the 5I7 state is 6.18 ms. The Stark splitting of the 5I7 and 5I8 multiplets is determined with low-temperature spectroscopy. The absorption, stimulated-emission (SE) and gain cross-sections for the 5I8↔5I7 transition are derived. Ho3+ :MgWO4 features a large Stark splitting of the ground-state (380 cm-1), high maximumσSE of 1.82 × 10–20 cm2 at 2.083μm, broad gain spectra and high luminescence quantum yield making it suitable for efficient continuous-wave and mode-locked lasers at∼2.1μm. First laser operation of Ho3+:MgWO4 crystal is demonstrated at 2.104μm reaching a slope efficiency of 72%

Mastering DNA Content Estimation by Flow Cytometry as an Efficient Tool for Plant Breeding and Biodiversity Research

Flow cytometry gives a unique opportunity to analyze thousands of individual cells for multiple parameters in a course of minutes. The most commonly used flow cytometry application in plant biology is estimation of nuclear DNA content. This becomes an indispensable tool in different areas of plant research, including breeding, taxonomy, plant development, evolutionary biology, populational studies and others. DNA content analysis can provide an insight into natural ploidy changes that reflect evolutionary processes, such as interspecific hybridization and polyploidization. It is also widely used for processing samples with biotechnologically induced ploidy changes, for instance, plants produced by doubled haploid technology. Absolute genome size data produced by cytometric analysis serve as useful taxon-specific markers since genome size vary between different taxa. It often allows the distinguishing of species within a genus or even different subspecies. Introducing flow cytometry method in the lab is extremely appealing, but new users face a significant challenge of learning instrument management, quality sample preparation and data processing. Not only is flow cytometry a complex method, but plant samples have unique features that make plants a demanding research subject. Without proper training, researchers risk damaging the expensive instrument or publishing poor quality data, artifacts or unreproducible results. We bring together information from our experience, key papers and online resources to provide step by step protocols and give a starting point for exploring the abundant cytometry literature

Cell Cycle-Dependent Dynamics of the Golgi-Centrosome Association in Motile Cells

Here, we characterize spatial distribution of the Golgi complex in human cells. In contrast to the prevailing view that the Golgi compactly surrounds the centrosome throughout interphase, we observe characteristic differences in the morphology of Golgi ribbons and their association with the centrosome during various periods of the cell cycle. The compact Golgi complex is typical in G1; during S-phase, Golgi ribbons lose their association with the centrosome and extend along the nuclear envelope to largely encircle the nucleus in G2. Interestingly, pre-mitotic separation of duplicated centrosomes always occurs after dissociation from the Golgi. Shortly before the nuclear envelope breakdown, scattered Golgi ribbons reassociate with the separated centrosomes restoring two compact Golgi complexes. Transitions between the compact and distributed Golgi morphologies are microtubule-dependent. However, they occur even in the absence of centrosomes, which implies that Golgi reorganization is not driven by the centrosomal microtubule asters. Cells with different Golgi morphology exhibit distinct differences in the directional persistence and velocity of migration. These data suggest that changes in the radial distribution of the Golgi around the nucleus define the extent of cell polarization and regulate cell motility in a cell cycle-dependent manner

Optimizing Different Medium Component Concentration and Temperature Stress Pretreatment for Gynogenesis Induction in Unpollinated Ovule Culture of Sugar Beet (<i>Beta vulgaris</i> L.)

The great economic importance of sugar beet determines the ongoing biotechnological studies conducted worldwide to improve the technology of obtaining doubled haploids (DHs) using the method of unpollinated ovule culture in vitro. To improve the induction of gynogenesis, we tested the effect of thidiazuron (TDZ), temperature bud pretreatment, different concentrations of sucrose, and culturing on liquid or solid medium. Three genotypes were tested in this study. The use of TDZ at a concentration of 0.4 mg/L in solid IMB (induction medium for Beta vulgaris) induction nutrient medium with 3 g/L phytagel, 50 g/L sucrose, 200 mg/L ampicillin and cultivation at 28◦C in the dark produced up to 16.7% induced ovules. The liquid nutrient medium of the same composition induced up to 8% ovules. Increasing TDZ concentration to 0.8 mg/L resulted in reduction or total inhibition of gynogenesis, depending on the genotype. Reducing the sucrose concentration to 20 g/L or increasing it to 80 g/L was not effective. In all three genotypes, the absence of temperature pretreatment of buds (5–6 °C) showed the best results. The plant regeneration with MS nutrient medium of 20 g/L sucrose, 3 g/L phytagel, 1 mg/L 6-benzylaminopurine (BAP) and 0.1 mg/L gibberellic acid (GA3) resulted in up to seven shoots from one induced ovule in the most responsive genotype. We showed by flow cytometry, chromosome counting and chloroplast number assessment that all regenerant plants were haploid (2n = x = 9)

Tm,Ho:Ca(Gd,Lu)AlO4 crystals: Crystal growth, structure refinement and Judd-Ofelt analysis

International audienceMixed” calcium rare-earth aluminate laser host crystals Ca(Gd,Lu)AlO4 (CALGLO) with up to 10.8 at.% Lu codoped with Tm3+ and Ho3+ ions are grown by the Czochralski method along the [001] direction. The segregation of rare-earth ions is studied. The crystal structure is refined by the Rietveld method. Tm,Ho:Ca(Gd,Lu)AlO4 crystallizes in the tetragonal system (sp. gr. I4/mmm) exhibiting a K2NiF4 type structure. The lattice constants are a = 3.6585(6) Å and c = 11.9660(9) Å for a crystal with a composition of CaGd0.8947Lu0.0551Tm0.0448Ho0.0054AlO4. The stability of Ca(Gd,Lu)AlO4 solid-solutions is discussed. The polarized Raman spectra are measured, revealing a most intense mode at 311 cm−1 and a maximum phonon frequency of ∼650 cm−1. The polarized absorption spectra are measured. The transition intensities for the Ho3+ ion are analyzed using the modified Judd-Ofelt theory accounting for configuration interaction

Disordered Tm3+,Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm

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