1,091 research outputs found
Hydrocarbon chain conformation in an intercalated surfactant monolayer and bilayer
Cetyl trimethyl ammonium (CTA) ions have been confined within galleries of layered CdPS3 at two different grafting densities. Low grafting densities are obtained on direct intercalation of CTA ions into CdPS3 to give Cd0.93PS3(CTA)0.14. Intercalation occurs with a lattice expansion of 4.8 Ã… with the interlamellar surfactant ion lying flat forming a monolayer. Intercalation at higher grafting densities was effected by a two-step ion-exchange process to give Cd0.83PS3(CTA)0.34, with a lattice expansion of 26.5 Ã…. At higher grafting densities the interlamellar surfactant ions adopt a tilted bilayer structure. 13C NMR and orientation-dependent IR vibrational spectroscopy on single crystals have been used to probe the conformation and orientation of the methylene 'tail' of the intercalated surfactant in the two phases. In the monolayer phase, the confined methylene chain adopts an essentially all-trans conformation with most of the trans chain aligned parallel to the gallery walls. On lowering the temperature, molecular plane aligns parallel, so that the methylene chain lies flat, rigid and aligned to the confining surface. In the bilayer phase, most bonds in the methylene chain are in trans conformation. It is possible to identify specific conformational sequences containing a gauche bond, in the interior and termini of the intercalated methylene. These high energy conformers disappear on cooling leaving all fifteen methylene units of the intercalated cetyl trimethyl ammonium ion in trans conformational registry at 40 K
Functionalization of the internal surfaces of layered cadmium thiophosphate with cationic surfactants: adsolubilization of uncharged organic molecules
Ion-exchange intercalation of the cationic surfactant cetyl trimethylammonium in layered CdPS3 leads to the formation of an intercalated bilayer within the galleries, thereby converting the internal surface of the layers from hydrophilic to hydrophobic. Several uncharged organic 'guest' molecules were found to be solubilized in the intercalated bilayer 'host'
Near-IR studies of recurrent nova V745 Scorpii during its 2014 outburst
The recurrent nova (RN) V745 Scorpii underwent its third known outburst on
2014 February 6. Infrared monitoring of the eruption on an almost daily basis,
starting from 1.3d after discovery, shows the emergence of a powerful blast
wave generated by the high velocity nova ejecta exceeding 4000 kms
plowing into its surrounding environment. The temperature of the shocked gas is
raised to a high value exceeding 10K immediately after outburst
commencement. The energetics of the outburst clearly surpass those of similar
symbiotic systems like RS Oph and V407 Cyg which have giant secondaries. The
shock does not show a free-expansion stage but rather shows a decelerative
Sedov-Taylor phase from the beginning. Such strong shockfronts are known to be
sites for ray generation. V745 Sco is the latest nova, apart from five
other known novae, to show ray emission. It may be an important
testbed to resolve the crucial question whether all novae are generically
ray emitters by virtue of having a circumbinary reservoir of material
that is shocked by the ejecta rather than ray generation being
restricted to only symbiotic systems with a shocked red giant (RG) wind. The
lack of a free-expansion stage favors V745 Sco to have a density enhancement
around the white dwarf (WD), above that contributed by a RG wind. Our analysis
also suggests that the WD in V745 Sco is very massive and a potential
progenitor for a future SN Ia explosion.Comment: To appear in ApJ (Letters
Evaluation of bacteriological diagnosis of smear positive pulmonary tubreculosis under programme conditions in three districts in the context of DOTS implementation in India
Objective: To study the smear and culture positivity rates in pulmonary tuberculosis patients declared as smear positive in
the districts of North Arcot (Tamil Nadu), Raichur (Karnataka) and Wardha (Maharashtra) in India in order to evaluate the
diagnosis of pulmonary tuberculosis at the field level under programme conditions.
Methods: Two specimens of sputum from each of 320 patients in North Arcot, 314 patients in Raichur and 302 patients
from Wardha district, all of whom had been reported as smear-positive at the field level, were examined by smear and culture.
Findings: The proportion of specimens found to be smear-negative was 4.7% in North Arcot and 5.7% in Raichur as against
38.7% in Wardha. The proportions of culture negative specimens were 5.7% and 6.3% respectively in North Arcot and
Raichur, while it was 35.6% at Wardha. The difference in the smear and culture negativity between Wardha and the other two
districts was highly significant.
Conclusions: The study revealed an unacceptably high level of false positives in sputum smear microscopy in the Wardha
district. This could be attributed to the absence of systematic and intensive training in smear examination consequent to the
non-implementation of the DOTS strategy in this district and a high standard of training offered in the RNTCP implemented
districts
Survelliance of drug resistance in tuberculosis in the state of Tamil Nadu
Summary: Surveillance of drug resistance was carried out at State level to obtain data which are standardised
and comparable using guidelines prescribed by the WHO/IUATLD Working Group on Anti-tuberculosis Drug
Resistance Surveillance.
Objective: To determine the proportion of initial and acquired drug resistance in cases of pulmonary tuberculosis
in Tamilnadu, in order to use the level of drug resistance as a performance indicator of the National Tuberculosis
Programme.
Methods: Two specimens of sputum from each of a total of 713 patients attending 145 participating centres all over
the state were tested by smear and culture examination and drug susceptibility tests of Isoniazid, Rifampicin,
Ethambutol and Streptomycin.
Results: Out of 400 patients for whom drug susceptibility results were available, 384 (96%) had no history of
previous anti-tuberculosis treatment. Of these, 312 (81%) were susceptible to all the drugs tested. Resistance to
isoniazid was seen in 15.4% of patients and to Rifampicin in 4.4% including resistance to Isoniazid and Rifampicin
in 3.4%.
Conclusion: There has been a gradual increase in initial drug resistance over the years in this part of the
country
The peculiar extinction law of SN2014J measured with The Hubble Space Telescope
The wavelength-dependence of the extinction of Type Ia SN2014J in the nearby
galaxy M82 has been measured using UV to near-IR photometry obtained with the
Hubble Space Telescope, the Nordic Optical Telescope, and the Mount Abu
Infrared Telescope. This is the first time that the reddening of a SN Ia is
characterized over the full wavelength range of - microns. A
total-to-selective extinction, , is ruled out with high
significance. The best fit at maximum using a Galactic type extinction law
yields . The observed reddening of SN2014J is also compatible
with a power-law extinction, as expected from multiple scattering of light, with
. After correction for differences in reddening, SN2014J appears
to be very similar to SN2011fe over the 14 broad-band filter light curves used
in our study.Comment: Accepted for publication in ApJ
Isolation of tubercle bacilli from sputum samples of patients in the field studies by the cetylpyridinium chloride-sodium chloride & sodium hydroxide methods
A total of 125 sputum specimens, collected in the field, were homogenised, aliquoted in sterile
universal containers and randomly allocated to the cetylpyridinium chloride - sodium chloride (CPCNaCl)
method and sodium hydroxide ( NaOH) method for culture of tubercle bacilli. After storage
for 8 days at ambient temperature in the field laboratory at Thiruvallur, the aliquots were transported
to the main laboratory at Madras where they were processed for culture by the respective
methods. The yield of positive cultures in the CPC-NaCl (31/125) method was only marginally better
than that in the NaOH method (27/125) (95% Cl being-3.4 to 9.8%), while the contamination of
cultures was significantly less in the CPC-NaCl method ( 3/125) than in the NaOH method (12/125)
(95% Cl being 2.2 to 12.2%). As the CPC-NaCl method has advantages over the NaOH method in
reducing contamination, in augmenting the yield of positive cultures and also in its simplicity, it can
be applied in field studies
Optimization and Analysis of Wireless Networks Lifetime using Soft Computing for Industrial Applications
Recently, wireless networks are applied in various engineering and industrial applications. One of the critical problems in wireless network system optimization in intelligent applications is obtaining an adequate energy fairness level. This issue can be resolved by applying effective cluster-based routing optimization with multi-hop routing. Hence a new network structure is developed that is derived from energy consumption architecture by applying soft computing strategies such as evolutionary operators in determining the exact clusters for optimizing energy consumption. The new effective evolutionary operators are tested in the optimization of a lifetime. The proposed method is simulated for different values of the routing factor, α, for different types of networks. The energy levels range from 0.4 to 0.8, achieving good results for nearly 2500 rounds. The proposed strategy optimizes the clusters, and its head is selected reliably. The optimization of cluster head choice has been done based on the base station distance, the energy of the node, and the node's energy efficiency. The reliability of the long-distance nodes is increased during the data transmission by modifying the size of the area of the candidate set of nodes in contrast the near-distance node's energy consumption is reduced. For the energy levels that range from 0.4 to 0.8, the higher network throughput is obtained at the same time network lifetime is optimized compared to other well-known approaches. The proposed model is expected for different industrial wireless network applications to optimize the systems during the long-run simulation and to achieve high reliability and sustainability
The deexcitation of the S<SUB>1</SUB> state of aminoanthraquinones: a steadystate and timeresolved study
The non-radiative processes of deactivation from the lowest singlet excited state of aminoanthraquinones have been studied using steady-state and time-resolved methods. The fluorescence decay rate constant, kf correlates well with the solvent polarity parameter, ET(30), in nonhydrogen bonding solvents. Large deuterium isotope effects in fluorescence lifetimes (τf) and quantum yields (Φf) are observed in the case of 1-amino (AAQ) and 1-methylaminoanthraquinones (MAQ), where the S1 state is mainly deactivated through internal conversion to the ground state. The temperature-dependence of the fluorescence quantum yields of various aminoanthraquinones was also investigated. The Φf and τf exhibited strong temperature-dependence in the case of 1-acetylaminoanthraquinone (ACAQ). In the case of ACAQ, the intersystem crossing to the triplet state is a major deactivation channel from the S1 and in this derivative a close-lying T2 state seems to be responsible for the high kisc rate. The fluorescence properties of 1,5-diaminoanthraquinone (DAQ) are affected by intermolecular hydrogen bonding with alcohols. Increasingn-alkyl chain length in the case of l-(n-alkyl)aminoanthraquinones from methyl to butyl does not produce any change in the fluorescence properties, whereas a hydroxypropyl substitution results in a small decrease of Φf and τf in these compounds, indicating an interaction of the hydroxyl group with the carbonyl group of the aminoanthraquinones
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