613 research outputs found
THE OPTICAL PROPERTIES OF Pr3+ EMBEDDED IN THE RARE EARTH BOROGERMANATE MATRICES: REBGeO5
The luminescent properties of the trivalent praseodymium ion in the trigonal borogermanate matrice PrBGeO5 have been analysed. The energy level schemes are deduced from the absorption and emission spectra and reproduced with 14 crystal field parameters (cfps) according to the local point symmetry occupied by the rare earth element in the matrix.The luminescent properties of the trivalent praseodymium ion in the trigonal borogermanate matrice PrBGeO5 have been analysed. The energy level schemes are deduced from the absorption and emission spectra and reproduced with 14 crystal field parameters (cfps) according to the local point symmetry occupied by the rare earth element in the matrix
Intuitive Understanding of sigma Delocalization in Loose and sigma Localization in Tight Helical Conformations of a Saturated Chain Oligosilanes
Conformational effects on the amp; 963; electron delocalization in oligosilanes are addressed by Hartree Fock and time dependent density functional theory calculations B3LYP, 6 311G at MP2 optimized geometries of permethylated uniformly helical linear oligosilanes all amp; 969; SinR2n 2 up to n 16 and for backbone dihedral angles amp; 969; 55 180 . The extent of amp; 963; delocalization is judged by the partition ratio of the highest occupied molecular orbital and is reflected in the dependence of its shape and energy and of UV absorption spectra on n. The results agree with known spectra of all transoid loose helix conformers all [ 165] SinMe2n 2 and reveal a transition at amp; 969; amp; 8776;90 from the amp; 963; delocalized limit at amp; 969; 180 toward and close to the physically non realizable amp; 963; localized tight helix limit amp; 969; 0 with entirely different properties. The distinction is also obtained in the Hückel Ladder H and C models of amp; 963; delocalization. An easy intuitive way to understand the origin of the two contrasting limits is to first view the linear chain as two subchains with alternating primary and vicinal interactions amp; 963; hyperconjugation , one consisting of the odd and the other of the even amp; 963; SiSi bonds, and then allow the two subchains to interact by geminal interactions amp; 963; conjugatio
High resolution infrared absorption spectra, crystal field, and relaxation processes in CsCdBr_3:Pr^3+
High resolution low-temperature absorption spectra of 0.2% Pr^3+ doped
CsCdBr_3 were measured in the spectral region 2000--7000 cm-1. Positions and
widths of the crystal field levels within the 3H5, 3H4, 3F2, and 3F3 multiplets
of the Pr^3+ main center have been determined. Hyperfine structure of several
spectral lines has been found. Crystal field calculations were carried out in
the framework of the semiphenomenological exchange charge model (ECM).
Parameters of the ECM were determined by fitting to the measured total
splittings of the 3H4 and 3H6 multiplets and to the observed in this work
hyperfine splittings of the crystal field levels. One- and two-phonon
relaxation rates were calculated using the phonon Green's functions of the
perfect (CsCdBr_3) and locally perturbed (impurity dimer centers in
CsCdBr_3:Pr^3+) crystal lattice. Comparison with the measured linewidths
confirmed an essential redistribution of the phonon density of states in
CsCdBr_3 crystals doped with rare-earth ions.Comment: 16 pages, 5 tables, 3 figure
High-efficiency dual transistor base drive circuit based on the Cuk converter topology
A role for suppressed thermogenesis favoring catch-up fat in the pathophysiology of catch-up growth
Catch-up growth is a risk factor for later obesity, type 2
diabetes, and cardiovascular diseases. We show here
that after growth arrest by semistarvation, rats refed
the same amount of a low-fat diet as controls show 1)
lower energy expenditure due to diminished thermogenesis
that favors accelerated fat deposition or catch-up
fat and 2) normal glucose tolerance but higher plasma
insulin after a glucose load at a time point when their
body fat and plasma free fatty acids (FFAs) have not
exceeded those of controls. Isocaloric refeeding on a
high-fat diet resulted in even lower energy expenditure
and thermogenesis and increased fat deposition and
led to even higher plasma insulin and elevated plasma
glucose after a glucose load. Stepwise regression analysis
showed that plasma insulin and insulin-to-glucose
ratio after the glucose load are predicted by variations
in efficiency of energy use (i.e., in thermogenesis)
rather than by the absolute amount of body fat or
plasma FFAs. These studies suggest that suppression of
thermogenesis per se may have a primary role in the
development of hyperinsulinemia and insulin resistance
during catch-up growth and underscore a role for suppressed
thermogenesis directed specifically at catch-up
fat in the link between catch-up growth and chronic
metabolic diseases
Assessment of levels of microbial contamination and presence of Salmonella spp. in wild boars in Serbia
Initiation of simple and complex spikes in cerebellar Purkinje cells
Cerebellar Purkinje cells produce two distinct forms of action potential output: simple and complex spikes. Simple spikes occur spontaneously or are driven by parallel fibre input, while complex spikes are activated by climbing fibre input. Previous studies indicate that both simple and complex spikes originate in the axon of Purkinje cells, but the precise location where they are initiated is unclear. Here we address where in the axon of cerebellar Purkinje cells simple and complex spikes are generated. Using extracellular recording and voltage-sensitive dye imaging in rat and mouse Purkinje cells, we show that both simple and complex spikes are generated in the proximal axon, ∼15–20 μm from the soma. Once initiated, simple and complex spikes propagate both down the axon and back into the soma. The speed of backpropagation into the soma was significantly faster for complex compared to simple spikes, presumably due to charging of the somatodendritic membrane capacitance during the climbing fibre synaptic conductance. In conclusion, we show using two independent methods that the final integration site of simple and complex spikes is in the proximal axon of cerebellar Purkinje cells, at a location corresponding to the distal end of the axon initial segment
Low T-cell Receptor Diversity, High Somatic Mutation Burden, and High Neoantigen Load as Predictors of Clinical Outcome in Muscle-invasive Bladder Cancer
AbstractBackgroundThe success of cancer immunotherapies has highlighted the potent ability of local adaptive immune responses to eradicate cancer cells by targeting neoantigens generated by somatic alterations. However, how these factors interact to drive the natural history of muscle-invasive bladder cancer (MIBC) is not well understood.ObjectiveTo investigate the role of immune regulation in MIBC disease progression, we performed massively parallel T-cell receptor (TCR) sequencing of tumor-infiltrating T cells (TILs), in silico neoantigen prediction from exome sequences, and expression analysis of immune-related genes.Design, setting, and participantsWe analyzed 38 MIBC tissues from patients who underwent definitive surgery with a minimum clinical follow-up of 2 yr.Outcome measurements and statistical analysisRecurrence-free survival (RFS) was determined. TCR diversity was quantified using Simpson's diversity index. The main analyses involved the Mann-Whitney U test, Kaplan-Meier survival analysis, and Cox proportional hazards models.Results and limitationsLow TCRβ chain diversity, correlating with oligoclonal TIL expansion, was significantly correlated with longer RFS, even after adjustment for pathologic tumor stage, node status, and receipt of adjuvant chemotherapy (hazard ratio 2.67, 95% confidence interval 1.08–6.60; p=0.03). Patients with both a high number of neoantigens and low TCRβ diversity had longer RFS compared to those with fewer neoantigens and high TCR diversity (median RFS 275 vs 30 wk; p=0.03). Higher expression of immune cytolytic genes was associated with nonrecurrence among patients with low TCR diversity or fewer neoantigens. Limitations include the sample size and the inability to distinguish CD8+ and CD4+ T cells using TCR sequencing.ConclusionsThese findings are the first to show that detailed tumor immune-genome analysis at definitive surgery can identify molecular patterns of antitumor immune response contributing to better clinical outcomes in MIBC.Patient summaryWe discovered that clonal expansion of certain T cells in tumor tissue, possibly targeting cancer-specific antigens, contributes to prevention of bladder cancer recurrence
A Chemogenetic Approach for the Optical Monitoring of Voltage in Neurons
Optical monitoring of neuronal voltage using fluorescent indicators is a powerful approach for the interrogation of the cellular and molecular logic of the nervous system. Herein, a semisynthetic tethered voltage indicator (STeVI1) based upon nile red is described that displays voltage sensitivity when genetically targeted to neuronal membranes. This environmentally sensitive probe allows for wash-free imaging and faithfully detects supra- and sub-threshold activity in neurons
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