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Mairs, Steve,Johnstone, Doug,Kirk, Helen,Lane, James,Bell, Graham S.,Graves, Sarah,Herczeg, Gregory J.,Scicluna, Peter,Bower, Geoffrey C.,Chen, Huei-Ru Vivien,Hatchell, Jennifer,Aikawa, Yuri,Chen, Wen American Astronomical Society 2017 The Astrophysical journal Vol.849 No.2
<P>Investigating variability at the earliest stages of low-mass star formation is fundamental in understanding how a protostar assembles mass. While many simulations of protostellar disks predict non-steady accretion onto protostars, deeper investigation requires robust observational constraints on the frequency and amplitude of variability events characterized across the observable SED. In this study, we develop methods to robustly analyze repeated observations of an area of the sky for submillimeter variability in order to determine constraints on the magnitude and frequency of deeply embedded protostars. We compare 850 mu m JCMT Transient Survey data with archival JCMT Gould Belt Survey data to investigate variability over 2-4 year timescales. Out of 175 bright, independent emission sources identified in the overlapping fields, we find seven variable candidates, five of which we classify as Strong, and the remaining two we classify as Extended to indicate that the latter are associated with larger-scale structure. For the Strong variable candidates, we find an average fractional peak brightness change per. year of |4.0|% yr(-1), with a standard deviation of 2.7% yr(-1). In total, 7% of the protostars associated with 850 mu m emission in our sample show signs of variability. Four of the five Strong sources are associated with a known protostar. The remaining source is a good follow-up target for an object that is anticipated to contain an enshrouded, deeply embedded protostar. In addition, we estimate the 850 mu m periodicity of the submillimeter variable source, EC 53, to be 567 +/- 32 days, based on the archival Gould Belt Survey data.</P>
Single-base Discrimination Mediated by Proofreading Inert Allele Specific Primers
( Lin Ling Chen ),( Zhang Jia ),( Steve S. Sommer ),( Li Kai ) 생화학분자생물학회 2005 BMB Reports Vol.38 No.1
The role of 3` exonuclease excision in DNA polymerization was evaluated for primer extension using inert allele specific primers with exonuclease-digestible ddNMP at their 3` termini. Efficient primer extension was observed in amplicons where the inert allele specific primers and their corresponding templates were mismatched. However, no primer-extended products were yielded by matched amplicons with inert primers. As a control, polymerase without proofreading activity failed to yield primer-extended products from inert primers regardless of whether the primers and templates were matched or mismatched. These data indicated that activation was undertaken for the inert allele specific primers through mismatch proofreading. Complementary to our previously developed SNP-operated on/off switch, in which DNA polymerization only occurs in matched amplicon, this new mutation detection assay mediated by exo+ DNA polymerases has immediate applications in SNP analysis independently or in combination of the two assays.
Wang, Li,Chen, Ken Chung,Gao, Yaozong,Shi, Feng,Liao, Shu,Li, Gang,Shen, Steve G. F.,Yan, Jin,Lee, Philip K. M.,Chow, Ben,Liu, Nancy X.,Xia, James J.,Shen, Dinggang Published for the American Association of Physicis 2014 Medical physics Vol.41 No.4
<P>Cone-beam computed tomography (CBCT) is an increasingly utilized imaging modality for the diagnosis and treatment planning of the patients with craniomaxillofacial (CMF) deformities. Accurate segmentation of CBCT image is an essential step to generate three-dimensional (3D) models for the diagnosis and treatment planning of the patients with CMF deformities. However, due to the poor image quality, including very low signal-to-noise ratio and the widespread image artifacts such as noise, beam hardening, and inhomogeneity, it is challenging to segment the CBCT images. In this paper, the authors present a new automatic segmentation method to address these problems.</P>
Single-base Discrimination Mediated by Proofreading Inert Allele Specific Primers
Lin-Ling, Chen,Zhang, Jia,Sommer, Steve S.,Li, Kai Korean Society for Biochemistry and Molecular Biol 2005 Journal of biochemistry and molecular biology Vol.38 No.1
The role of 3' exonuclease excision in DNA polymerization was evaluated for primer extension using inert allele specific primers with exonuclease-digestible ddNMP at their 3' termini. Efficient primer extension was observed in amplicons where the inert allele specific primers and their corresponding templates were mismatched. However, no primer-extended products were yielded by matched amplicons with inert primers. As a control, polymerase without proofreading activity failed to yield primer extended products from inert primers regardless of whether the primers and templates were matched or mismatched. These data indicated that activation was undertaken for the inert allele specific primers through mismatch proofreading. Complementary to our previously developed SNP-operated on/off switch, in which DNA polymerization only occurs in matched amplicon, this new mutation detection assay mediated by $exo^+$ DNA polymerases has immediate applications in SNP analysis independently or in combination of the two assays.
Flexible piezoelectric liquid volume sensor
Ryu, Jeongjae,Jeong, Hanbert,Chen, Yugang,Oh, Chungik,Kim, Jaegyu,Kim, Hongjun,Cho, Seongwoo,No, Kwangsoo,Park, Yong-Hwa,Park, Steve,Hong, Seungbum Elsevier 2018 Sensors and actuators. A, Physical Vol.276 No.-
<P><B>Abstract</B></P> <P>We report a non-contact type polyvinylidene fluoride (PVDF)-based liquid volume sensor. When a liquid container vibrates due to an applied impact, our sensor that is attached to the wall of the container detects the resonance frequency of vibration, which shifts as a result of change in liquid volume. The sensitivity of our sensor was enhanced by stacking multiple sensors in series. A PVDF bimorph actuator was also fabricated to demonstrate an integrated actuator-sensor system. We believe that the results presented in this work will pave the way for novel applications in volume sensing.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed a contact-free liquid volume sensor based on a flexible PVDF film. </LI> <LI> Resonance frequency of vibration is detected using our sensor when a liquid container vibrates. </LI> <LI> A simulation describes the relationship between resonance frequecy and liquid volume. </LI> <LI> Sensitivity increases with stacked multiple sensors in series. </LI> <LI> An integrated actuator-sensor system is demonstrated. </LI> </UL> </P>
Enhanced Diffusion and Oligomeric Enzyme Dissociation
Jee, Ah-Young,Chen, Kuo,Tlusty, Tsvi,Zhao, Jiang,Granick, Steve American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.51
<P>The concept that catalytic enzymes can act as molecular machines transducing chemical activity into motion has conceptual and experimental support, but experimental support has involved oligomeric enzymes, often studied under conditions where the substrate concentration is higher than biologically relevant and accordingly exceeds <I>k</I><SUB>M</SUB>, the Michaelis constant. Urease, a hexamer of subunits, has been considered to be the gold standard demonstrating enhanced diffusion. Here we show that urease and certain other oligomeric enzymes dissociate above <I>k</I><SUB>M</SUB> into their subunits that diffuse more rapidly, thus providing a simple physical mechanism that contributes to enhanced diffusion in this regime of concentrations. Mindful that this conclusion may be controversial, our findings are supported by four independent analytical techniques: static light scattering, dynamic light scattering (DLS), size-exclusion chromatography (SEC), and fluorescence correlation spectroscopy (FCS). Data for urease are emphasized and the conclusion is validated for hexokinase, acetylcholinesterase, and aldolase. For hexokinase and aldolase no enhanced diffusion is observed except under conditions when these oligomeric enzymes dissociate. At substrate concentration regimes below <I>k</I><SUB>M</SUB> at which acetylcholinesterase and urease do not dissociate, our finding showing up to 10% enhancement of the diffusion coefficient is consistent with various theoretical scenarios in the literature.</P> [FIG OMISSION]</BR>
Syn, Wing‐,Kin,Choi, Steve S.,Liaskou, Evaggelia,Karaca, Gamze F.,Agboola, Kolade M.,Oo, Ye Htun,Mi, Zhiyong,Pereira, Thiago A.,Zdanowicz, Marzena,Malladi, Padmini,Chen, Yuping,Moylan, Cynthia,J Wiley Subscription Services, Inc., A Wiley Company 2011 Hepatology Vol.53 No.1
<P><B>Abstract</B></P><P>Nonalcoholic steatohepatitis (NASH) is a leading cause of cirrhosis. Recently, we showed that NASH‐related cirrhosis is associated with Hedgehog (Hh) pathway activation. The gene encoding osteopontin (OPN), a profibrogenic extracellular matrix protein and cytokine, is a direct transcriptional target of the Hh pathway. Thus, we hypothesize that Hh signaling induces OPN to promote liver fibrosis in NASH. Hepatic OPN expression and liver fibrosis were analyzed in wild‐type (WT) mice, Patched‐deficient (Ptc<SUP>+/−</SUP>) (overly active Hh signaling) mice, and OPN‐deficient mice before and after feeding methionine and choline–deficient (MCD) diets to induce NASH‐related fibrosis. Hepatic OPN was also quantified in human NASH and nondiseased livers. Hh signaling was manipulated in cultured liver cells to assess direct effects on OPN expression, and hepatic stellate cells (HSCs) were cultured in medium with different OPN activities to determine effects on HSC phenotype. When fed MCD diets, Ptc<SUP>+/−</SUP> mice expressed more OPN and developed worse liver fibrosis (<I>P</I> < 0.05) than WT mice, whereas OPN‐deficient mice exhibited reduced fibrosis (<I>P</I> < 0.05). In NASH patients, OPN was significantly up‐regulated and correlated with Hh pathway activity and fibrosis stage. During NASH, ductular cells strongly expressed OPN. In cultured HSCs, SAG (an Hh agonist) up‐regulated, whereas cyclopamine (an Hh antagonist) repressed OPN expression (<I>P</I> < 0.005). Cholangiocyte‐derived OPN and recombinant OPN promoted fibrogenic responses in HSCs (<I>P</I> < 0.05); neutralizing OPN with RNA aptamers attenuated this (<I>P</I> < 0.05). <I>Conclusion:</I> OPN is Hh‐regulated and directly promotes profibrogenic responses. OPN induction correlates with Hh pathway activity and fibrosis stage. Therefore, OPN inhibition may be beneficial in NASH (H<SMALL>EPATOLOGY</SMALL> 2011)</P>
Junqiao Wang,Shaoping Nie,Lijiao Kan,Haihong Chen,Steve W. Cui,Aled O. Phillips,Glyn O. Phillips,Mingyong Xie 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.1
Four polysaccharides (named as P1, P2, and P3 from three natural Cordyceps sinensis and P4 from cultured C. sinensis) were obtained by hot-water extraction and ethanol precipitation and their structural characteristics as well as antioxidant potentials were compared. Results revealed that the backbone of P1, P2, and P3 comprised α-1,4-glucose, with a branching point mainly at position 6 and terminating at glucose. On the other hand, the structure of P4 was highly complex, mainly comprising glucose, galactose, and mannose, with 1,4-glucose and 1,4-galactose as the main chain. For in vitro antioxidant assays, all the four polysaccharides showed similar scavenging capacity against DPPH and hydroxyl radicals, whereas P1 had a relatively low ferric reducing ability, possibly related to a combination of factors such as the phenolic compounds and amino acids that conjugated in polysaccharides.