11,175 research outputs found
Stone Beads and their Imitations
Simulations of precious-stone beads began to be made as soon as feasible materials became available. From antiquity onward, we have replicas of stone beads made of glazed stone, faience, and other ceramics, and glass. In contemporary times, glass and plastic have become the predominant substitutes for stone beads, although materials of organic origin, such as bone and tusk, have also been used. Information is presented on the background, materials, and techniques for detecting such simulations, using primarily visual clues provided by macro color photographs
Z-Selectivity in Olefin Metathesis with Chelated Ru Catalysts: Computational Studies of Mechanism and Selectivity
The mechanism and origins of Z-selectivity in olefin metathesis with chelated Ru catalysts were explored using density functional theory. The olefin approaches from the āsideā position of the chelated Ru catalysts, in contrast to reactions with previous unchelated Ru catalysts that favor the bottom-bound pathway. Steric repulsions between the substituents on the olefin and the N-substituent on the N-heterocyclic carbene ligand lead to highly selective formation of the Z product
The interaction of core-collapse supernova ejecta with a companion star
The progenitors of many CCSNe are expected to be in binary systems. After the
SN explosion, the companion may suffer from mass stripping and be shock heated
as a result of the impact of the SN ejecta. If the binary system is disrupted,
the companion is ejected as a runaway and hypervelocity star. By performing a
series of 3D hydrodynamical simulations of the collision of SN ejecta with the
companion star, we investigate how CCSN explosions affect their companions. We
use the BEC code to construct the detailed companion structure at the time of
SN explosion. The impact of the SN blast wave on the companion is followed by
means of 3D SPH simulations using the Stellar GADGET code. For main-sequence
(MS) companions, we find that the amount of removed mass, impact velocity, and
chemical contamination of the companion that results from the impact of the SN
ejecta, strongly increases with decreasing binary separation and increasing
explosion energy. Their relationship can be approximately fitted by power laws,
which is consistent with the results obtained from impact simulations of
SNe~Ia. However, we find that the impact velocity is sensitive to the momentum
profile of the outer SN ejecta and, in fact, may decrease with increasing
ejecta mass, depending on the modeling of the ejecta. Because most companions
to Ib/c CCSNe are in their MS phase at the moment of the explosion, combined
with the strongly decaying impact effects with increasing binary separation, we
argue that the majority of these SNe lead to inefficient mass stripping and
shock heating of the companion star following the impact of the ejecta. Our
simulations show that the impact effects of Ib/c SN ejecta on the structure of
MS companions, and thus their long-term post-explosion evolution, is in general
not dramatic. We find that at most 10% of their mass is lost, and their
resulting impact velocities are less than 100 km/s.Comment: Accepted for publication in Astronomy and Astrophysics, some minor
typographical errors are fixed, the affiliation of second author is correcte
An in situ probeāspacingācorrecting thermoāTDR sensor to measure soil water content accurately
To reduce the possibility of probe deflections, conventional thermo-time domain reflectometry (T-TDR) sensors have relatively short probe lengths (ā¤4 cm). However, short probes lead to large errors in TDR-estimated soil water content (Īøv). In this study, two new 6-cm-long probe-spacing-correcting T-TDR (CT-TDR) sensors were investigated. Compared to conventional 4-cm-long T-TDR sensors, the 6-cm-long CT-TDR sensors reduced errors in TDR-estimated Īøv. Errors in heat pulse (HP) estimated Īøv because of probe deflections were reduced when linear or nonlinear probe spacing correcting algorithms were implemented. The 6-cm-long CT-TDR sensors provided more accurate Īøv estimations than do the conventional 4-cm-long TTDR sensors
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Mechanisms of nuclear content loading to exosomes.
Exosome cargoes are highly varied and include proteins, small RNAs, and genomic DNA (gDNA). The presence of gDNA suggests that different intracellular compartments contribute to exosome loading, resulting in distinct exosome subpopulations. However, the loading of gDNA and other nuclear contents into exosomes (nExo) remains poorly understood. Here, we identify the relationship between cancer cell micronuclei (MN), which are markers of genomic instability, and nExo formation. Imaging flow cytometry analyses reveal that 10% of exosomes derived from cancer cells and <1% of exosomes derived from blood and ascites from patients with ovarian cancer carry nuclear contents. Treatment with genotoxic drugs resulted in increased MN and nExos both in vitro and in vivo. We observed that multivesicular body precursors and exosomal markers, such as the tetraspanins, directly interact with MN. Collectively, this work provides new insights related to nExos, which have implications for cancer biomarker development
BindingDB: a web-accessible database of experimentally determined proteināligand binding affinities
BindingDB () is a publicly accessible database currently containing ā¼20ā000 experimentally determined binding affinities of proteināligand complexes, for 110 protein targets including isoforms and mutational variants, and ā¼11ā000 small molecule ligands. The data are extracted from the scientific literature, data collection focusing on proteins that are drug-targets or candidate drug-targets and for which structural data are present in the Protein Data Bank. The BindingDB website supports a range of query types, including searches by chemical structure, substructure and similarity; protein sequence; ligand and protein names; affinity ranges and molecular weight. Data sets generated by BindingDB queries can be downloaded in the form of annotated SDfiles for further analysis, or used as the basis for virtual screening of a compound database uploaded by the user. The data in BindingDB are linked both to structural data in the PDB via PDB IDs and chemical and sequence searches, and to the literature in PubMed via PubMed IDs
Lesinurad, a novel, oral compound for gout, acts to decrease serum uric acid through inhibition of urate transporters in the kidney.
BackgroundExcess body burden of uric acid promotes gout. Diminished renal clearance of uric acid causes hyperuricemia in most patients with gout, and the renal urate transporter (URAT)1 is important for regulation of serum uric acid (sUA) levels. The URAT1 inhibitors probenecid and benzbromarone are used as gout therapies; however, their use is limited by drug-drug interactions and off-target toxicity, respectively. Here, we define the mechanism of action of lesinurad (ZurampicĀ®; RDEA594), a novel URAT1 inhibitor, recently approved in the USA and Europe for treatment of chronic gout.MethodssUA levels, fractional excretion of uric acid (FEUA), lesinurad plasma levels, and urinary excretion of lesinurad were measured in healthy volunteers treated with lesinurad. In addition, lesinurad, probenecid, and benzbromarone were compared in vitro for effects on urate transporters and the organic anion transporters (OAT)1 and OAT3, changes in mitochondrial membrane potential, and human peroxisome proliferator-activated receptor gamma (PPARĪ³) activity.ResultsAfter 6Ā hours, a single 200-mg dose of lesinurad elevated FEUA 3.6-fold (pā<ā0.001) and reduced sUA levels by 33Ā % (pā<ā0.001). At concentrations achieved in the clinic, lesinurad inhibited activity of URAT1 and OAT4 in vitro, did not inhibit GLUT9, and had no effect on ABCG2. Lesinurad also showed a low risk for mitochondrial toxicity and PPARĪ³ induction compared to benzbromarone. Unlike probenecid, lesinurad did not inhibit OAT1 or OAT3 in the clinical setting.ConclusionThe pharmacodynamic effects and in vitro activity of lesinurad are consistent with inhibition of URAT1 and OAT4, major apical transporters for uric acid. Lesinurad also has a favorable selectivity and safety profile, consistent with an important role in sUA-lowering therapy for patients with gout
Fluctuations of the Condensate in Ideal and Interacting Bose Gases
We investigate the fluctuations of the condensate in the ideal and weakly
interacting Bose gases confined in a box of volume V within canonical ensemble.
Canonical ensemble is developed to describe the behavior of the fluctuations
when different methods of approximation to the weakly interacting Bose gases
are used. Research shows that the fluctuations of the condensate exhibit
anomalous behavior for the interacting Bose gas confined in a box.Comment: RevTex, 4 Figs,E-mail:[email protected], corrected typo
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