• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.670-679
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• 1997

The pH changes in 4 small cavities prepared at the facial inner dentin and lingual outer dentin of the cervical and apical portion of root filled with calcium hydroxide pastes were investigated. Forty extracted permanent teeth with single canal were instrumented with step-back method, and then 4 small cavities were prepared. Two inner dentin cavities were cut a distance of about 1.0mm from the canal wall and two outer dentin cavities were cut to a depth of about 0.5mm from the root surface. Root canals and prepared cavities were flushed with 17% EDTA, and then irrigated with 5% NaOCl to remove smear layer. Teeth were randomly divided into four groups. Control group was not filled and the remaining other groups were filled with mixture of calcium hydroxide and distilled water, Vitapex$^{(R)}$ paste and Pulpdent$^{(R)}$ paste respectively. The pH change of the dentin in each cavity was measured at 0, 1, 3, 7, 14, 21, 28, 60, 90 days with pH microelectrode(WPI Co., USA). The results were as follows : 1. The groups obturated with Pulpdent$^{(R)}$ paste and Aqueous calcium hydroxide produced the increased pH level at 1 day and maintained plateau over next 3weeks and decreased after 3weeks. 2. The group obturated with Vitapex$^{(R)}$ paste observed no significant pH change until 2weeks and slight increased pH at 3weeks and sequential increasing after 3weeks. But, the pH in the group obturated with Vitapex$^{(R)}$ paste remained significantly below the pH measured in the other two experimental groups(P<0.05). 3. All experimental groups showed pH level similar to control group after 28 days. 4. The pH of outer dentin is slightly higher than that of inner dentin. There is no significant difference in pH level between apical and cervical dentin throughout the duration of the experiment, though apical dentin showed slightly higher pH than cervical dentin at 1 day(P<0.05).

• Interdisciplinary Bio Central
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• v.1 no.2
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• pp.7.1-7.7
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• 2009

"To be, or not to be?" This question is not only Hamlet's agony but also the dilemma of mitochondria in a cancer cell. Cancer cells have a high glycolysis rate even in the presence of oxygen. This feature of cancer cells is known as the Warburg effect, named for the first scientist to observe it, Otto Warburg, who assumed that because of mitochondrial malfunction, cancer cells had to depend on anaerobic glycolysis to generate ATP. It was demonstrated, however, that cancer cells with intact mitochondria also showed evidence of the Warburg effect. Thus, an alternative explanation was proposed: the Warburg effect helps cancer cells harness additional ATP to meet the high energy demand required for their extraordinary growth while providing a basic building block of metabolites for their proliferation. A third view suggests that the Warburg effect is a defense mechanism, protecting cancer cells from the higher than usual oxidative environment in which they survive. Interestingly, the latter view does not conflict with the high-energy production view, as increased glucose metabolism enables cancer cells to produce larger amounts of both antioxidants to fight oxidative stress and ATP and metabolites for growth. The combination of these two different hypotheses may explain the Warburg effect, but critical questions at the mechanistic level remain to be explored. Cancer shows complex and multi-faceted behaviors. Previously, there has been no overall plan or systematic approach to integrate and interpret the complex signaling in cancer cells. A new paradigm of collaboration and a well-designed systemic approach will supply answers to fill the gaps in current cancer knowledge and will accelerate the discovery of the connections behind the Warburg mystery. An integrated understanding of cancer complexity and tumorigenesis is necessary to expand the frontiers of cancer cell biology.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.625-628
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• 2015

POLARBEAR is a ground-based experiment located in the Atacama desert of northern Chile. The experiment is designed to measure the Cosmic Microwave Background B-mode polarization at several arcminute resolution. The CMB B-mode polarization on degree angular scales is a unique signature of primordial gravitational waves from cosmic inflation and B-mode signal on sub-degree scales is induced by the gravitational lensing from large-scale structure. Science observations began in early 2012 with an array of 1.274 polarization sensitive antenna-couple Transition Edge Sensor (TES) bolometers at 150 GHz. We published the first CMB-only measurement of the B-mode polarization on sub-degree scales induced by gravitational lensing in December 2013 followed by the first measurement of the B-mode power spectrum on those scales in March 2014. In this proceedings, we review the physics of CMB B-modes and then describe the Polarbear experiment, observations, and recent results.