1,002 research outputs found
Expression, crystallization and preliminary X-ray diffraction studies of N-carbamyl-D-amino-acid amidohydrolase from Agrobacterium radiobacter
The Agrobacterium radiobacter CCRC 14924 N-carbamyl-D-amino-acid amidohydrolase, the enzyme used for production of D-amino acids, was overexpressed in Escherichia coli JM109. The expressed protein was crystallized by vapour diffusion using lithium sulfate as precipitant. It crystallizes in space group P2(1) with unit-cell parameters cr = 69.8, b = 67.9 and c = 137.8 Angstrom and beta = 96.4 degrees. There are four molecules per asymmetric unit. Crystals diffract to 2.8 Angstrom resolution using a rotating-anode source at cryogenic (113 K) temperatures
Highly Facet-reflection Immune 53GBaud EML for 800G Artificial Intelligence Optical Transceivers
We developed a facet-reflection immune 53GBaud electro-absorption modulated laser (EML) for 800G artificial intelligence (AI) optical network. An ultra-low anti-reflection (AR) coating reflectivity of 2x10-5 has been demonstrated for straight waveguide. Based on Hakki-Paoli method, we characterized the ultra-low AR using the ripple test technique. Such ultra-low AR is critical in achieving excellent eye pattern and optical transmission for 800G AI supercomputing
Structure optimization in an off-lattice protein model
We study an off-lattice protein toy model with two species of monomers
interacting through modified Lennard-Jones interactions. Low energy
configurations are optimized using the pruned-enriched-Rosenbluth method
(PERM), hitherto employed to native state searches only for off lattice models.
For 2 dimensions we found states with lower energy than previously proposed
putative ground states, for all chain lengths . This indicates that
PERM has the potential to produce native states also for more realistic protein
models. For , where no published ground states exist, we present some
putative lowest energy states for future comparison with other methods.Comment: 4 pages, 2 figure
Sequential drain amylase to guide drain removal following pancreatectomy
BACKGROUND:
Although used as criterion for early drain removal, postoperative day (POD) 1 drain fluid amylase (DFA) ≤ 5000 U/L has low negative predictive value for clinically relevant postoperative pancreatic fistula (CR-POPF). It was hypothesized that POD3 DFA ≤ 350 could provide further information to guide early drain removal.
METHODS:
Data from a pancreas surgery consortium database for pancreatoduodenectomy and distal pancreatectomy patients were analyzed retrospectively. Those patients without drains or POD 1 and 3 DFA data were excluded. Patients with POD1 DFA ≤ 5000 were divided into groups based on POD3 DFA: Group A (≤350) and Group B (>350). Operative characteristics and 60-day outcomes were compared using chi-square test.
RESULTS:
Among 687 patients in the database, all data were available for 380. Fifty-five (14.5%) had a POD1 DFA > 5000. Among 325 with POD1 DFA ≤ 5000, 254 (78.2%) were in Group A and 71 (21.8%) in Group B. Complications (35 (49.3%) vs 87 (34.4%); p = 0.021) and CR-POPF (13 (18.3%) vs 10 (3.9%); p < 0.001) were more frequent in Group B.
CONCLUSIONS:
In patients with POD1 DFA ≤ 5000, POD3 DFA ≤ 350 may be a practical test to guide safe early drain removal. Further prospective testing may be useful
Optical properties of pyrochlore oxide
We present optical conductivity spectra for
single crystal at different temperatures. Among reported pyrochlore ruthenates,
this compound exhibits metallic behavior in a wide temperature range and has
the least resistivity. At low frequencies, the optical spectra show typical
Drude responses, but with a knee feature around 1000 \cm. Above 20000 \cm, a
broad absorption feature is observed. Our analysis suggests that the low
frequency responses can be understood from two Drude components arising from
the partially filled Ru bands with different plasma frequencies and
scattering rates. The high frequency broad absorption may be contributed by two
interband transitions: from occupied Ru states to empty bands
and from the fully filled O 2p bands to unoccupied Ru states.Comment: 4 pages, 6 figure
Ligation of lymphocyte function-associated antigen-1 on monocytes decreases very late antigen-4-mediated adhesion through a reactive oxygen species-dependent pathway
Monocyte-endothelial adhesion plays an important role in monocyte trafficking and hence is important for immune responses and pathogenesis of inflammatory diseases including atherosclerosis. The cross-talk between different integrins on monocytes may be crucial for a coordinated regulation of the cellular adhesion during the complex process of transendothelial migration. By using monoclonal antibodies and recombinant intercellular adhesion molecule 1 (ICAM-1) to engage lymphocyte function-associated antigen 1 (LFA-1) on monocytic cells, we found that the cellular adhesion to vascular cell adhesion molecule 1 (VCAM-1) mediated by very late antigen 4 (VLA-4) was suppressed after this treatment and the suppression depended on the presence of reactive oxygen species (ROSs). Inhibition of production of RoSs through the use of inhibitor of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, but not inhibitors of mitochondrial electron transport chain or xanthine oxidase, revealed that this suppression on VLA-4-mediated cellular binding was mediated by Ross produced by phagocyte NADPH oxidase. Activation of phosphoinositol-3 kinase and Akt appears to mediate this NADPH oxidase activation through p47 phox phosphorylation and Rac-1 activation. Our results provide a novel pathway in which Ross play a critical role in integrin cross-talk in monocytes. This signaling pathway may be important for cellular transition from firm arrest to diapedesis during monocyte trafficking. (C) 2004 by The American Society of Hematology
Stepwise formation of heteronuclear coordination networks based on quadruple-bonded dimolybdenum units containing formamidinate ligands
Reactions of [Mo2(4-pyf)4] (4-Hpyf = 4-pyridylformamidine) with
HgX2 (X = Cl, Br and I) afforded the first 2D and 3D heteronuclear
coordination networks based on quadruple-bonded dimolybdenum
units
Ground-state properties of tubelike flexible polymers
In this work we investigate structural properties of native states of a
simple model for short flexible homopolymers, where the steric influence of
monomeric side chains is effectively introduced by a thickness constraint. This
geometric constraint is implemented through the concept of the global radius of
curvature and affects the conformational topology of ground-state structures. A
systematic analysis allows for a thickness-dependent classification of the
dominant ground-state topologies. It turns out that helical structures,
strands, rings, and coils are natural, intrinsic geometries of such tubelike
objects
Thermostatistics of deformed bosons and fermions
Based on the q-deformed oscillator algebra, we study the behavior of the mean
occupation number and its analogies with intermediate statistics and we obtain
an expression in terms of an infinite continued fraction, thus clarifying
successive approximations. In this framework, we study the thermostatistics of
q-deformed bosons and fermions and show that thermodynamics can be built on the
formalism of q-calculus. The entire structure of thermodynamics is preserved if
ordinary derivatives are replaced by the use of an appropriate Jackson
derivative and q-integral. Moreover, we derive the most important thermodynamic
functions and we study the q-boson and q-fermion ideal gas in the thermodynamic
limit.Comment: 14 pages, 2 figure
- …