Rotational line overlap in CO2 laser transitions

Patel, B. S.; Swarup, Prem

doi:10.1088/0022-3727/6/14/303

Cited by 11 publications

(7 citation statements)

References 3 publications

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“…In these measurements only the integrated intensity was recorded as the specimen was rotated through its reflecting position. The silicon specimen studied here was similar to those reported in an earlier study with anomalous Xray transmission (Patel, 1973). The X-ray specimen was cut from the center of a 2" diameter Czochralskigrown dislocation-free silicon crystal with an oxygen atomic concentration of 7 x 10 x7 cm -3 as determined by infrared absorption measurements at 9 pm.…”

Section: Lil Experimentalmentioning

confidence: 99%

“…Evidence of diffuse scattering from clusters of oxygen in Silicon is reported herein. In previous publications (Patel & Batterman, 1963;Patel, 1973) the problem of oxygen precipitation in silicon has been outlined. To recapitulate very briefly; when silicon crystals are grown from quartz crucibles they can contain up to 10 TM atom cm -3 of dissolved oxygen, which can be detected by a band in the infrared at 9 /~m.…”

Section: Introductionmentioning

confidence: 99%

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X-ray diffuse scattering from silicon containing oxygen clusters

Patel¹

1975

J Appl Cryst

106

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X-ray diffuse scattering has been observed in silicon crystals containing oxygen clusters. The crystals were initially dislocation free and the clustering was produced by a heat treatment at 950°C for 5 h. Since defect sizes are relatively large, measurements were made in a double-crystal spectrometer close to Bragg reflections of about 2" halfwidth. From the angular dependence of the diffuse scattering we estimate the average defect size to be about 2000 A,. In addition a very noticeable asymmetry in the diffuse scattering was observed with much higher intensities at the high-angle tail of the Bragg reflection. Very marked changes in the intensity of the anomalous transmission of X-rays in silicon have previously been observed following similar treatment. The defects responsible for the observed anomalous transmission and diffuse scattering effects have been characterized by X-ray topography and electron microscopy. The asymmetry of the diffuse scattering observed is consistent with the direct determination of the interstitial nature of the defects produced after clustering.

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Section: Lil Experimentalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

X-ray diffuse scattering from silicon containing oxygen clusters

Patel¹

1975

J Appl Cryst

106

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“…The method of Chou and Fasman [33] is simple and based on empirical rules from a statistical analysis of 15 proteins of known conformation. This predictive model was claimed to be capable of determining protein secondary structures with 80% accuracy, and it has been used by others to predict protein conformations [34]. To obtain an idea of the lipoprotein conformation and to compare the outcome with the results of the circular dichroism measurements, we determined the lipoprotein conformation according to the Chou-Fasman rules.…”

Section: Prediction Of Lipoprotein Conformationmentioning

confidence: 99%

Conformational Studies on Murein‐Lipoprotein from the Outer Membrane of Escherichia coli

Braun

Rotering

Ohms

et al. 1976

European Journal of Biochemistry

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Conformational studies on an isolated integral membrane protein are reported. Lipoprotein of the Escherichia coli outer membrane was released from murein by treatment with either lysozyme or trypsin. The isolated lysozyme-released lipoprotein (lipoprotein I) contained 2 or 3 muropeptides covalently linked at the C-terminal end, while the trypsin-released lipoprotein (lipoprotein IT) was free of muropeptides and lacked the C-terminal peptide Tyr-Arg-Lys. Circular dichroism spectra of the two preparations were essentially identical, and they show an a-helix content of about 80%. According to calculations based on the Chou-Fasman rules for proteins of known sequence, lipoprotein is 64 % a-helix and 15 % p-structure. Infrared spectroscopy qualitatively supports these values. The conformation was stable in the pH range of 5-12. Denaturation of lipoprotein by heat, 8 M urea, or sodium dodecylsulphate was a fully reversible, cooperative process. The thermal denaturation of lipoprotein occurs in two steps with transition points at 79.4 "C for lipoprotein I and at 85.1 "C for lipoprotein 11. Lipoprotein markedly changes conformation at dodecylsulphate concentrations where micelle formation sets in. The unusual behaviour of the lipoprotein conformation in sodium dodecylsulphate is discussed in relation to the lipoprotein conformation and aggregation within the membrane.The conformation of membrane proteins has played an important role in discussions on the molecular organization of biological membranes [I -41. The outer membrane of Escherichia coli is basically constructed like other biological membranes in that glycolipids are at the surface, and phospholipids and proteins are the major constituents. A peculiarity of the bacterial cell's outer layer is the murein net composed of polysaccharide chains cross-linked by short peptide side-chains [5]. Lipoprotein molecules of a single type are covalently fixed at the murein net and extend into the outer membrane [6,7]. Together with the free form of lipoprotein not covalently bound to the murein [8], they constitute the most abundant protein in E. coli. It can be assumed that certain properties of the outer membrane, such as its function as a permeability barrier against certain substrates and antibiotics, are determined substantially by this lipoprotein. Knowledge of the lipoprotein's conformation would aid in the construction of a tentative model of outer membrane structure.Immunological studies with the aim of localizing the lipoprotein within the outer membrane showed that lipoprotein acts as an antigen in mutant cells with defects in cell surface structures and that in wild-type cells it is buried in the membrane (9 -111. Since the amino acid sequence of the lipoprotein is known [12,13], we could study the regions of the polypeptide chain against which antibodies were directed. From the two lipoprotein samples used for the conformational studies in this paper, one was released from the murein by degradation of murein with lysozyme and the other by cleaving the polypeptid...

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“…Although a number of authors have discussed the effects of line broadening [9] and calculations of the high-pressure gain spectrum have been published [lo] , there has been little effort to compare the predicted behavior with experimental data. Recently, gain measurements for a 15-atm electron-beamcontrolled device were reported by Harris et aE.…”

Section: Introductionmentioning

confidence: 99%