306 research outputs found
ROLE OF HETERONUCLEAR COMPLEXES IN SOLUTIONS FOR METALLIZATION OF PLASTICS.
Metallization of plastics by chemical deposition of metals is an important technological process in production of circuit boards. The usual reducing agents are formaldehyde, borohydrides, hydrazine and its derivatives, and hypophosphites in alkaline media. Since most metal ions undergo hydrolysis in such media, they are converted into complex compounds. Salts of tartaric (H//4Tart) or citric (H//4Citr) acids, whose anions act as multidentate ligands, are used in solutions for chemical coppering and coating with nickel-cobalt and nickel-copper alloys. Heteronuclear complexes (HNC) may be formed in solutions containing two or more transition-metal salts. The authors studied the systems Cu(II)-Ni(II)-H//4Citr, Cu(II)-Co(II)-H//4Citr under the concentration conditions of copper baths. Using the NMR method, whereby formation of heteronuclear species can be recorded directly, the authors detected formation of a heteronuclear complex
Composition, properties, and structure of palladium(II) chlorides in aqueous solution
The composition, stability, and structure of palladium(II) chloride complexes in hydrochloric acid media have been determined using nuclear-magnetic relaxation, magnetochemical methods, and Rayleigh light scattering. The predominant form in solution for palladium(II) concentrations greater than 0.005 moles/liter is the octahedral Pd6Cl12 or Pd6Cl14 2-, which has antiferromagnetic properties in contrast with the paramagnetic properties of the mononuclear aquachloride. The polarizability anisotropy of Pd-Cl bonds with terminal and bridging chlorine atoms has been determined. © 1991 Plenum Publishing Corporation
Hygienic assessment of educational and extracurricular activities of students in grades 9 and 11
The purpose of the study is a hygienic assessment of the educational and extracurricular activities of students in grades 9 and 11.Цель исследования – гигиеническая оценка учебной и вне учебной деятельности учеников 9 и 11 классов
Assessment of ion kinetic effects in shock-driven inertial confinement fusion implosions using fusion burn imaging
The significance and nature of ion kinetic effects in D3He-filled, shock-driven inertial confinement
fusion implosions are assessed through measurements of fusion burn profiles. Over this series of
experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number,
NK) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma
conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match
measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured
the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially
resolved measurements of the fusion burn are used to examine kinetic ion transport effects in
greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional
integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison
of measured and simulated burn profiles shows that models including ion transport effects
are able to better match the experimental results. In implosions characterized by large Knudsen
numbers (NK3), the fusion burn profiles predicted by hydrodynamics simulations that exclude
ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally
observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that
includes a model of ion diffusion is able to qualitatively match the measured profile shapes.
Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the
observed trends, though further refinement of the models is needed for a more complete and
quantitative understanding of ion kinetic effects
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The Optical Lightpipe as a High-Bandwidth Fusion Diagnostic
A recent series of experiments at the University of Rochester Laboratory for Laser Energetics OMEGA facility studied the feasibility of using radiation-to-light converters and high bandwidth optical signal transmission to remote recording devices as an alternate nuclear diagnostic method. A prototype system included a radiation-to-light converter, a multiple-section light pipe consisting of stainless steel tubes with polished interiors and turning mirrors, and a streak camera or photomultiplier/digitizer combination for signal recording. Several different radiation-to-light converters (scintillators, glasses, plastics, and pressurized CO{sub 2}) performed well and produced predictable optical emissions. The lightpipe transmitted high-bandwidth optical signals to the recording stations. Data were recorded with the streak camera, the photomultiplier/digitizer, and with both recorders simultaneously
Two-Stage Rotational Disordering of a Molecular Crystal Surface: C60
We propose a two-stage mechanism for the rotational surface disordering phase
transition of a molecular crystal, as realized in C fullerite. Our
study, based on Monte Carlo simulations, uncovers the existence of a new
intermediate regime, between a low temperature ordered state,
and a high temperature disordered phase. In the intermediate
regime there is partial disorder, strongest for a subset of particularly
frustrated surface molecules. These concepts and calculations provide a
coherent understanding of experimental observations, with possible extension to
other molecular crystal surfaces.Comment: 4 pages, 2 figure
Chemical genetic screen identifies lithocholic acid as an anti-aging compound that extends yeast chronological life span in a TOR-independent manner, by modulating housekeeping longevity assurance processes
In
chronologically aging yeast, longevity can be extended by administering a
caloric restriction (CR) diet or some small molecules. These life-extending
interventions target the adaptable target of rapamycin (TOR) and
cAMP/protein kinase A (cAMP/PKA) signaling pathways that are under the
stringent control of calorie availability. We designed a chemical genetic
screen for small molecules that increase the chronological life span of
yeast under CR by targeting lipid metabolism and modulating housekeeping
longevity pathways that regulate longevity irrespective of the number of
available calories. Our screen identifies lithocholic acid (LCA) as one of
such molecules. We reveal two mechanisms underlying
the life-extending effect of LCA in chronologically aging yeast. One
mechanism operates in a calorie availability-independent fashion and
involves the LCA-governed modulation of housekeeping longevity assurance
pathways that do not overlap with the adaptable TOR and cAMP/PKA pathways.
The other mechanism extends yeast longevity under non-CR conditions and
consists in LCA-driven unmasking of the previously unknown anti-aging
potential of PKA. We provide evidence that LCA modulates housekeeping
longevity assurance pathways by suppressing lipid-induced necrosis,
attenuating mitochondrial fragmentation, altering oxidation-reduction
processes in mitochondria, enhancing resistance to oxidative and thermal
stresses, suppressing mitochondria-controlled apoptosis, and enhancing
stability of nuclear and mitochondrial DNA
Hypergraph extensions of the Erdős-Gallai Theorem
Abstract We extend the Erdős-Gallai Theorem for Berge paths in
r -uniform hypergraphs. We also find the extremal hypergraphs
avoiding t -tight paths of a given length and consider this
extremal problem for other definitions of paths in hypergraphs
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