Bose-Fermi mixtures of ultracold gases of dysprosium

Laser cooling and trapping of the most magnetic fermionic atom, dysprosium (Dy), may provide a framework to explore quantum liquid crystal (QLC) theory (Chapter 1). This thesis presents details of the Dy laser cooling and trapping apparatus including the laser systems at 421, 741, and 1064 nm, the ultra-high vacuum (UHV) chamber, and the computer control that has produced a magneto-optically (MOT) and magneto-statically (MT) trapped Dy gas (Chapters 3, 4, 5). Despite the fact that Dy has a complex energy level structure with nearly 140 metastable states (Chapter 2), Dy MOT at 421-nm transition with 32-MHz linewidth was realized without any rempumper, exploiting its large magnetic moment, which brought a strong magnetic confinement of metastable states of Dy. This unique MOT/MT dynamics is discussed and its quantitative measurements are shown in Chapter 6. When the Dy atoms dropped from the MOT were adsorptively imaged, it was observed that Dy MOT had a bimodal temperature distribution in contrast to the usual MOT described by a single temperature (Chapter 7). Such novel anisotropic sub-Doppler laser cooling of Dy, which breaks the symmetry in cooling, is due to Dy's large magnetic spin aligned along a strong axis of the quadrupole field of the MOT, and we further support this plausible conjecture with the velocity selective resonance (VSR) theory. The MOT at ~ 1 mK was cooled to ~ 10 uK by narrow-line cooling at 741 nm with a linewidth of 2 kHz, and we were able to load the optical dipole trap (ODT) at 1064 nm. By loading two isotopes of 164Dy and 163Dy in sequence to the MOT and narrow-line cooling them simultaneously, ultracold Bose-Fermi mixtures of Dy in the ODT were realized (Chapter 8). This thesis is concluded with a discussion of prospect on the Bose-Fermi mixtures of Dy

Anisotropic sub-Doppler laser cooling in dysprosium magneto-optical traps

Magneto-optical traps (MOTs) of Er and Dy have recently been shown to exhibit population-wide sub-Doppler cooling due to their near degeneracy of excited and ground state Lande g factors. We discuss here an additional, unusual intra-MOT sub-Doppler cooling mechanism that appears when the total Dy MOT cooling laser intensity and magnetic quadrupole gradient increase beyond critical values. Specifically, anisotropically sub-Doppler-cooled cores appear, and their orientation with respect to the quadrupole axis flips at a critical ratio of the MOT laser intensity along the quadrupole axis versus that in the plane of symmetry. This phenomenon can be traced to a loss of the velocity-selective resonance at zero velocity in the cooling force along directions in which the atomic polarization is oriented by the quadrupole field. We present data characterizing this anisotropic laser cooling phenomenon and discuss a qualitative model for its origin based on the extraordinarily large Dy magnetic moment and Dy's near degenerate g factors.Comment: 4 pages, 5 figure

Anisotropic sub-Doppler laser cooling in dysprosium magneto-optical traps

Magneto-optical traps (MOTs) of Er and Dy have recently been shown to exhibit populationwide sub-Doppler cooling due to their near degeneracy of excited-and ground-state Landé g factors. We discuss here an additional, unusual intra-MOT sub-Doppler cooling mechanism that appears when the total Dy MOT cooling laser intensity and magnetic quadrupole gradient increase beyond critical values. Specifically, anisotropically sub-Dopplercooled cores appear, and their orientation with respect to the quadrupole axis flips at a critical ratio of the MOT laser intensity along the quadrupole axis versus that in the plane of symmetry. This phenomenon can be traced to a loss of the velocity-selective resonance at zero velocity in the cooling force along directions in which the atomic polarization is oriented by the quadrupole field. We present data characterizing this anisotropic laser cooling phenomenon and discuss a qualitative model for its origin based on the extraordinarily large Dy magnetic moment and Dy's near degenerate g factors

Spectroscopy of a narrow-line laser cooling transition in atomic dysprosium

The laser cooling and trapping of ultracold neutral dysprosium has been recently demonstrated using the broad, open 421-nm cycling transition. Narrow-line magneto-optical trapping of Dy on longer wavelength transitions would enable the preparation of ultracold Dy samples suitable for loading optical dipole traps and subsequent evaporative cooling. We have identified the closed 741-nm cycling transition as a candidate for the narrow-line cooling of Dy. We present experimental data on the isotope shifts, the hyperfine constants A and B, and the decay rate of the 741-nm transition. In addition, we report a measurement of the 421-nm transition's linewidth, which agrees with previous measurements. We summarize the laser cooling characteristics of these transitions as well as other narrow cycling transitions that may prove useful for cooling Dy.Comment: 6+ pages, 5 figures, 5 table

Characteristics of thyroid nodules in infant with congenital hypothyroidism

PurposeThis study aimed to assess the characteristics of thyroid nodules among infants diagnosed with congenital hypothyroidism.MethodsA retrospective study of 660 infants (374 males, 286 females) diagnosed with congenital hypothyroidism was carried out at the Pediatric Endocrine Clinic in Soonchunhyang University Hospital, Korea, between May 2003 and February 2013. The average age at diagnosis was 1.16±1.68 months.ResultsOf the 28 patients (4.2%) with thyroid nodules, 17 (2.6%) had cystic thyroid nodules and 11 (1.6%) had solid thyroid nodules. There were no significant differences in gender or age between congenital hypothyroidism patients who hadthyroid nodules and those who did not. All nodules were asymptomatic. The average age at diagnosis of congenital hypothyroidism with nodules was 1.42±1.39 months. All detected nodules measured less than 1 cm in diameter. Twenty-two of the 28 infants (78.6%) had only one nodule, while multiple nodules were found in 6 infants (21.4%). Of the 28 infants diagnosed with nodules, 16 underwent thyroid ultrasonography during follow-up and 8 of them (50%) showed no signs of nodules at thyroid ultrasonography.ConclusionThe prevalence of thyroid nodules in infants with congenital hypothyroidism was 4.2%. Most thyroid nodules were small in size and benign, disappearing during follow-up observation. We therefore conclude that thyroid nodules in infants with congenital hypothyroidism can simply be observed and do not require direct treatment

Berberine derivative WJCPR11 enhances osteoblast differentiation

Berberine is a phytocompound from plants viz. Phellodendri cortex and Coptis rhizome, used to treat a variety of diseases. It is effective in preventing osteoporosis, but it is less effective than drugs currently used in clinical practice. In this study, we used a novel berberine derivative, WJCPR11, to promote osteoblast differentiation and to investigate its use in the prevention and treatment of osteoporosis. WJCPR11 at a safe concentration without toxicity increased alkaline phosphatase (ALP) activity induced by bone morphogenetic protein 2 (BMP2) dose-dependently. The mRNA expression of ALP, osteocalcin (OC), runt-related transcription factor 2 (Runx2), and osterix was increased, with the ALP level increasing the most. In addition, the protein abundance of bone sialoprotein (BSP), collagen, type I, alpha 1, Runx2, and osterix were also increased. Moreover, the transcriptional activity of ALP, BSP, and OC was increased by WJCPR11, with OC showing the most significant increase. The results indicate that osteoblast differentiation is promoted by WJCPR11, and it could play a role in the prevention of osteoporosis