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N Yu

Publications and source records attributed to N Yu.

83 records · Page 5Linked to original sources
PubMed1989

The 6S(0)-6P(0) transition in thallium isotope ion Tl: A superior atomic clock.

Experimental and theoretical studies of the forbidden J = 0 --> J' = 0 optical transition 6(1)S(0)-6(3)P(0) in the odd Hg isotopes are in the literature. From this work natural width and quadratic Zeeman effect have been estimated for the same line in the isoelectronic, even thallium ion (204)Tl(+), which has a very small nuclear magnetic moment. For the m(F) = 0 --> 0 component a linewidth of <0.01 Hz and a quadratic Zeeman shift <10(-18) at 0.1 Gauss are found, compared to 1 Hz and approximately 10(-8) for the hydrogen maser. Electronic quadrupole moments vanish for both J and J' states and with them shifts due to electric field gradients. All shifts are orders of magnitude smaller than for Hg(+) and Ba(+), which have been studied as atomic clock elements.

Journal Article↗
PubMed1989

Trapped individual ion at absolute zero temperature.

Laser cooling and ion trapping have progressed to such an extent that one can now speak of realizing a confined atom at absolute zero temperature. In this short publication, we analyze an experiment toward such realization using a single Ba(+) ion in a miniature rf trap. The Ba(+) ion is first laser-cooled to the limit where the ion spends most of its time in the zero-point energy state. Then a test sequence allows one to verify whether or not the ion is actually in its zero-point state. The test sequence may also serve as a device for state selection of an atom at absolute zero temperature.

Journal Article↗
PubMed1989

Miniature Paul-Straubel ion trap with well-defined deep potential well.

In some recently proposed experiments using ion traps, a Paul trap of conventional size and design is insufficient. We have constructed a miniature Paul-Straubel trap. It has a small elliptic ring ( approximately 0.2 mm) and three pairs of planar electrodes ( approximately 2 cm part) arranged so that they form a cube. The two conventional end-cap electrodes are replaced by the six planar electrodes. The ring is heatable to a high temperature for improving the uniformity of the dc potential on the ring surface. With this trap, we hope to do such fundamental studies as the true zero-point confinement of a single ion.

Journal Article↗
PubMed1984

The microbial production of amylase inhibitor and its application. I. Isolation and cultivation of Streptomyces nigrifaciens NTU-3314.

In the course of screening amylase inhibitor producing, microorganisms, a strain identified as Streptomyces nigrifaciens NTU-3314 was found to have the highest inhibitor-producing ability among the other isolated strains. This strain was aerobically cultured at 30 degrees C in a 5l jar fermentor with a working volume of 2l. The optimum cultural medium consisted of defatted soybean flake 3.0%, potato starch 4.0%, casein 0.6%, sucrose 0.6%, serine 0.02% and NaCl 0.8% (pH 7.0). With an aeration rate of 1.5 vvm, an agitation speed of 300 rpm and an inoculum of 15% seed (previously grown in seed medium 3), the highest amount of inhibitor was obtained after 24 hours of cultivation. The amylase inhibitor produced had inhibitory effects on both alpha-amylase and glucoamylase, but not on beta-amylase, alpha-glucosidase, beta-glucosidase or dextranase. It was quite stable in 0.1M phosphate buffer (pH 7.0) and nearly 100% of its activity was retained even after boiling at 100 degrees C for 20 min.

Amylases↗
PubMedDate not supplied

Pertussis toxin reduces the day-night rhythm of nociception and mu and kappa opioid peptide-mediated antinociception in the snail, Cepaea nemoralis.

There is accumulating evidence that pertussis toxin-sensitive G proteins are associated with the transduction of opioid-mediated antinociception in mammals. The present study examined the effects of hemocel injections of pertussis toxin (0.10 microgram) on the day-night rhythm of nociception and mu and kappa opioid-mediated antinociception in a mollusc, the land snail, Cepaea nemoralis. Five days after treatment, pertussis toxin significantly reduced the naloxone-sensitive, opioid-mediated nocturnal peak in the day-night rhythm of nociception [as measured by the latency of response to a thermal (40 degrees C) stimulus] in Cepaea, without affecting the daytime response latency. Pertussis toxin also significantly decreased the antinociceptive effects of the mu agonist, DAMGO, and blocked those of the kappa opioid agonist, U-69,593. These results suggest that G protein substrates of pertussis toxin are associated with the transduction of opioid-mediated nociception and antinociception in the snail, Cepaea.

Animals↗
PubMedDate not supplied

Determination of triamcinolone acetonide in equine serum and urine by liquid chromatography-atmospheric pressure ionization mass spectrometry.

Urine and serum samples collected from four standard-bred mares after 30-mg intraarticular administrations of triamcinolone acetonide were analyzed using combined high-performance liquid chromatography-atmospheric pressure ionization mass spectrometry. Maximum triamcinolone acetonide concentrations of 32.3, 14.8, 24.3, and 29.4 ng/mL in the urine and 2.7, 1.9, 2.3, and 2.5 ng/mL in the serum samples were observed. The peak concentrations of the drug were detected approximately 22 h (urine) and 12 h (serum) after administration. The drug elimination profiles for both urine and serum are presented and discussed.

Animals↗
PubMedDate not supplied

IL-1-alpha and TNF-alpha differentially regulate CD4 and Mac-1 expression in mouse microglia.

The regulatory effects of the proinflammatory cytokines, interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) were investigated on CD4 and Mac-1 expression in mouse microglial cultures. The identity of the microglia in cultures was confirmed by multiple indices including morphology, uptake of acetylated low-density lipoprotein and lectin RCA 120 staining. Microglia growing on a monolayer of astrocytes (astrocyte-supported microglia) were both CD4- and Mac-1 positive (out of 94.5 % Mac-1-positive cells, 85.3% were also CD4 positive). When astrocyte-supported microglia were replated directly onto culture dishes (plate-supported microglia), the percentage of CD4- and Mac-1-positive cells decreased to 12-29 and 20-25% respectively. The addition of IL-1alpha or TNF-alpha to plate-supported microglia led to an upregulation of Mac-1 expression in a time- and dose-dependent manner with different EC50s (0.5 ng/ml for IL-1alpha and 2 ng/ml for TNF-alpha) but exhibited similar time-to-peak responses (over 12 h). The addition of IL-1alpha, but not TNF-alpha, also led to an increase in CD4 expression on plate-supported microglia with a similar dose response and time course. IL-1alpha treatment gave rise to an increase in the level of CD4 mRNA as assessed by RT-PCR. The possibility that cell proliferation was responsible for the observed effects on microglia was excluded by an analysis of 3H-thymidine incorporation. Our results suggest that cultured mouse microglia express CD4 molecules which can be upregulated by IL-1alpha while Mac-1 can be upregulated by both IL-1alpha and TNF-alpha.

Animals↗