59 research outputs found
The false vacuum bubble nucleation due to a nonminimally coupled scalar field
We study the possibility of forming the false vacuum bubble nucleated within
the true vacuum background via the true-to-false vacuum phase transition in
curved spacetime. We consider a semiclassical Euclidean bubble in the Einstein
theory of gravity with a nonminimally coupled scalar field. In this paper we
present the numerical computations as well as the approximate analytical
computations. We mention the evolution of the false vacuum bubble after
nucleation.Comment: 23 pages, 12 figures, References added, minor correctio
The vacuum bubbles in de Sitter background and black hole pair creation
We study the possible types of the nucleation of vacuum bubbles. We classify
vacuum bubbles in de Sitter background and present some numerical solutions.
The thin-wall approximation is employed to obtain the nucleation rate and the
radius of vacuum bubbles. With careful analysis we confirm that Parke's formula
is also applicable to the large true vacuum bubbles. The nucleation of the
false vacuum bubble in de Sitter background is also evaluated. The tunneling
process in the potential with degenerate vacua is analyzed as the limiting
cases of the large true vacuum bubble and false vacuum bubble. Next, we
consider the pair creation of black holes in the background of bubble
solutions. We obtain static bubble wall solutions of junction equation with
black hole pair. The masses of created black holes are uniquely determined by
the cosmological constant and surface tension on the wall. Finally, we obtain
the rate of pair creation of black holes.Comment: 3 figures, minor including errors and typos corrected, and refs.
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Bubble collision with gravitation
In this paper, we study vacuum bubble collisions with various potentials
including gravitation, assuming spherical, planar, and hyperbolic symmetry. We
use numerical calculations from double-null formalism. Spherical symmetry can
mimic the formation of a black hole via multiple bubble collisions. Planar and
especially hyperbolic symmetry describes two bubble collisions. We study both
cases, when two true vacuum regions have the same field value or different
field values, by varying tensions. For the latter case, we also test symmetric
and asymmetric bubble collisions, and see details of causal structures. If the
colliding energy is sufficient, then the vacuum can be destabilized, and it is
also demonstrated. This double-null formalism can be a complementary approach
in the context of bubble collisions.Comment: 31 pages, 19 figure
Phosphorescent Sensor for Robust Quantification of Copper(II) Ion
A phosphorescent sensor based on a multichromophoric iridium(III) complex was synthesized and characterized. The construct exhibits concomitant changes in its phosphorescence intensity ratio and phosphorescence lifetime in response to copper(II) ion. The sensor, which is reversible and selective, is able to quantify copper(II) ions in aqueous media, and it detects intracellular copper ratiometrically.National Institute of General Medical Sciences (U.S.) ((Grant GM065519)Ewha Woman's University (Korea) (RP-Grant 2009
Tunable emission properties of CdSe/CdS quantum dots by Ce doping
A facile one-step hydrothermal synthesis to prepare cerium (Ce3+) ion doped CdSe/CdS core/shell quantum dots (QDs) is introduced. The effect of Ce3+ ion doping on structural and optical properties of the CdSe/CdS core/shell QDs is comprehensively investigated. With increasing Ce doping concentration, a linear increase in the lattice parameter is observed, suggesting the successful coupling of Ce3+ ions to the CdSe/CdS QDs. X-ray photoelectron spectroscopy reveals strong peaks of the Ce3+ state, indicating that Ce is initially present mainly in the Ce3+ ion state. In addition, red-shift over the range 538–569 nm is observed in the photoluminescence (PL) spectra of Ce3+ ion doped CdSe/CdS QDs. Results clearly indicates that the PL peak positions of the CdSe/CdS QDs could be controlled by the Ce content. This study highlights a new approach to tune the emission of the QDs
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Acitretin-induced periungual pyogenic granulomas and review
Periungual pyogenic granulomas are benign vascular tumors that present as painful, round, spontaneously bleeding lesions composed of rapidly proliferating capillaries and excess tissue. The vast majority of pyogenic granulomas are caused by physical trauma or infectious agents and they may resolve spontaneously. Herein, we highlight a very rare case of periungual pyogenic granulomas induced by the regularly prescribed oral retinoid acitretin during treatment for congenital palmoplantar keratoderma. This unique case showed that it is feasible to continue acitretin therapy in the presence of pyogenic granuloma development if proper dose reduction and topical therapies are utilized. The patient's lesions resolved within two weeks of this protocol's initiation and the pyogenic granulomas did not recur over the course of a six-month follow-up observation period. In addition, we performed a systematic review of the literature using PubMed databases for the clinical features and treatments in other reported acitretin-induced pyogenic granuloma cases; we compiled a comprehensive list of other prescription drugs known to cause pyogenic granulomas up-to-date
Nutrients and bioactive potentials of edible green and red seaweed in Korea
Abstract Background Traditionally, East-Asians (Korea, Japan, and China) utilize seaweeds as a food source and ingredient in traditional medicine. Korea is one of the biggest seaweed producer and consumer in the global trade. Especially, side dishes made from seaweeds are very popular in the traditional Korean cuisines. Seaweeds are popular as fresh vegetable salads and soup or eaten as snacks. Main body Seaweeds are rich in essential nutrients, minerals, and vitamins as well as a promising source of novel bioactive compounds. The compounds (polysaccharides, polyphenols, and sterols) present in the edible Korean seaweeds possess important bioactive properties such as antioxidant, anti-inflammation, anticancer, anti-diabetic, and anticoagulant properties. Thus, the long-term consumption of seaweed has a potential to reduce the risk of cancer, diabetes, obesity, and inflammation-related complications. However, seaweed consumption is limited to the small population around the globe. Thus, it is important to increase the awareness of the health benefits of seaweeds consumption among the general population. Short conclusion In the present study, we discussed some popular green and red edible Korean seaweeds and their health-promoting properties. This study might be useful to increase the public awareness of the consumption of seaweed as a food source. Graphical Abstrac
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