9,971 research outputs found
The effect of sulfanilamide on the electrocrystallization of copper on a single crystal copper (110) plane
The presence of small quantities of sulfanilamide in a highly purified acidic CuSO4 electroplating bath alters the growth habit of Cu on a single-crystal Cu(110) plane. At a given c.d. a transition from a ridge type of growth to broken ridgesand then to polycryst. growth was obsd. with increasing sulfanilamide concn. andthis mechanism was discussed using η vs. log i curves. These effects were attributed to complex formation, decomplexation and the adsorption of sulfanilamide
The structure of dark matter halos in hierarchical clustering theories
During hierarchical clustering, smaller masses generally collapse earlier
than larger masses and so are denser on the average. The core of a small mass
halo could be dense enough to resist disruption and survive undigested, when it
is incorporated into a bigger object. We explore the possibility that a nested
sequence of undigested cores in the center of the halo, which have survived the
hierarchical, inhomogeneous collapse to form larger and larger objects,
determines the halo structure in the inner regions. For a flat universe with
, scaling arguments then suggest that the core density
profile is, with . But
whether such behaviour obtains depends on detailed dynamics. We first examine
the dynamics using a fluid approach to the self-similar collapse solutions for
the dark matter phase space density, including the effect of velocity
dispersions. We highlight the importance of tangential velocity dispersions to
obtain density profiles shallower than in the core regions. If
tangential velocity dispersions in the core are constrained to be less than the
radial dispersion, a cuspy core density profile shallower than 1/r cannot
obtain, in self-similar collapse. We then briefly look at the profiles of the
outer halos in low density cosmological models where the total halo mass is
convergent. Finally, we analyze a suite of dark halo density and velocity
dispersion profiles obtained in cosmological N-body simulations of models with
n= 0, -1 and -2. We find that the core-density profiles of dark halos, show
considerable scatter in their properties, but nevertheless do appear to reflect
a memory of the initial power spectrum, with steeper initial spectra producing
flatter core profiles. (Abridged)Comment: 31 pages, 7 figures, submitted to Ap
The effect of sulfanilamide on the electrodeposition of copper onto a single crystal copper (100) plane and a polycrystalline copper substrate
Studies were made of the electrodeposition of Cu onto a single-crystal Cu(100) plane and onto a polycryst. Cu surface both in pure acidic CuSO4 soln. and in solns. contg. various concns. of sulfanilamide at various c. ds. the transition is from pyramids to truncated blocks to ridges and then to a polycryst. deposit. On a polycryst. substrate there is a change from large grains to very fine grains in the presence of sulfanilamide. These changes are explained with the help of complexation and adsorption theory
Electrodeposition of copper on a copper single-crystal (100) face and on a copper polycrystalline surface in the presence of sulphaguanidine
In the presence of sulphaguanidine a triangular pyramid growth form changes successively to a layer type of growth which transforms to ridges and then to a polycrystalline deposit on a (100) single-crystal copper substrate. On a polycrystalline copper surface the grain size of the deposit is affected markedly by sulphaguanidine. The change in the growth form and overpotential are explained with the help of IR and X-ray techniques. © 1979
Surface modified nano-zeolite used as carrier for slow release of sulphur
Surface modified nano-zeolite (SMNZ) was used as carrier to develop nano-zeolite based nano-sulphur fertilizer. A laboratory study on sulphur nano-fertilizer and conventional sulphur fertilizer were studied with percolation reactor system to evaluate the slow release of sulphur from both fertilizers in ambient temperature. SMNZ and sulphur nano-fertilizer were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Zeta Analyzer, Raman Spectroscopy, XRD and Scanning Electron Microscope (SEM). Raman spectroscopy confirmed the sulphur attachment at 480 cm-1 in the SMNZ. The FTIR spectra at 1030 cm-1 confirmed the sulphate attachments in the SMNZ spectrum. Zeta analyzer showed the surface charge of sulphur nano-fertilizer had (-) 52.6 mV. SEM imaged the sulphur loaded SMNZ in irregular flake like structure. A comparative study of the release of sulphate (SO4 2-) from fertilizer-loaded SMNZ and (NH4)2 SO4 fertilizers were performed using the percolation reactor. The results showed that the SO42- supply from fertilizer-loaded SMNZ was available even after 912 h of continuous percolation, whereas SO42- from (NH4)2 SO4 was exhausted within 384 h. These properties suggest that SMNZ has a great potential as the fertilizer carrier for slow release of SO42-
How are Forbush decreases related to interplanetary magnetic field enhancements ?
Aims. Forbush decrease (FD) is a transient decrease followed by a gradual
recovery in the observed galactic cosmic ray intensity. We seek to understand
the relationship between the FDs and near-Earth interplanetary magnetic field
(IMF) enhancements associated with solar coronal mass ejections (CMEs).
Methods. We use muon data at cutoff rigidities ranging from 14 to 24 GV from
the GRAPES-3 tracking muon telescope to identify FD events. We select those FD
events that have a reasonably clean profile, and magnitude > 0.25%. We use IMF
data from ACE/WIND spacecrafts. We look for correlations between the FD profile
and that of the one hour averaged IMF. We ask if the diffusion of high energy
protons into the large scale magnetic field is the cause of the lag observed
between the FD and the IMF. Results. The enhancement of the IMF associated with
FDs occurs mainly in the shock-sheath region, and the turbulence level in the
magnetic field is also enhanced in this region. The observed FD profiles look
remarkably similar to the IMF enhancement profiles. The FDs typically lag the
IMF enhancement by a few hours. The lag corresponds to the time taken by high
energy protons to diffuse into the magnetic field enhancement via cross-field
diffusion. Conclusions. Our findings show that high rigidity FDs associated
with CMEs are caused primarily by the cumulative diffusion of protons across
the magnetic field enhancement in the turbulent sheath region between the shock
and the CME.Comment: accepted in A&
A Unified treatment of small and large- scale dynamos in helical turbulence
Helical turbulence is thought to provide the key to the generation of
large-scale magnetic fields. Turbulence also generically leads to rapidly
growing small-scale magnetic fields correlated on the turbulence scales. These
two processes are usually studied separately. We give here a unified treatment
of both processes, in the case of random fields, incorporating also a simple
model non-linear drift. In the process we uncover an interesting plausible
saturated state of the small-scale dynamo and a novel analogy between quantum
mechanical (QM) tunneling and the generation of large scale fields. The steady
state problem of the combined small/large scale dynamo, is mapped to a
zero-energy, QM potential problem; but a potential which, for non-zero mean
helicity, allows tunneling of bound states. A field generated by the
small-scale dynamo, can 'tunnel' to produce large-scale correlations, which in
steady state, correspond to a force-free 'mean' field.Comment: 4 pages, 1 figure, Physical Review Letters, in pres
Green processes in process metallurgy
Environmental pollution ultimately governs the economic or industrial growth rate of the world. Ideal green processes, both conceptual and feasible are discussed and the advantages and limitations are brought out. Typical
examples of novel techniques developed to combat pollution are presented. An integrated approach coupling energy saving with pollution control measures appears to be the best strategy
Process Engineering for Pollution Control and Waste Minimisation in Non -Ferrous Metallurgical Industries
The importance of industrial ecology in the materials cycle has been stressed.The different approaches to process design have been outlined and typical applications to non-ferrous metallurgy have been highlighted. The
challenges and opportunities for pollution control and waste minimisation in the non-ferrous metallurgical industries with reference to gaseous emissions, liquid effluents and solid wastes have been examined
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