Equatorial Arcs Research Articles

Sources of magnetic fields in recurrent interplanetary streams

We examined the sources of magnetic fields in recurrent streams observed by the Imp 8 and Heos spacecraft at 1 AU and by Mariner 10 en route to Mercury between October 31, 1973, and February 9, 1974, during Carrington rotations 1607–1610. Most fields and plasmas at 1 AU were related to coronal holes, and the magnetic field lines were open in those holes. However, some of the magnetic fields and plasmas at 1 AU were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines may be more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes, estimated by projecting the measured interplanetary magnetic fields back to the sun by using the principle of flux conservation, ranged from 2 to 18 G with an average of 9 G. Average measured photospheric magnetic fields along the footprints of the corresponding unipolar fields on circular equatorial arcs at 2.5 RS had a similar range and average, but in two cases the intensities were approximately 3 times higher than the projected intensities. The coronal footprints of the sector boundaries on the source surface at 2.5 RS, determined by a potential field extrapolation of the measured photospheric fields, meandered between −45° and +45° latitude, and their inclination with respect to the solar equator ranged from near 0° at some longitudes to near 90° at others. It is possible that sector boundaries are related to convergence surfaces of the flow near the sun. The high densities observed near sector boundaries between streams might be due in part to the convergence of flows from adjacent coronal holes.

Structure of Twisted Nylon 6 and Poly(ethylene terephthalate) Fibers

Nylon 6 and poly(ethylene terephthalate) monofilaments were subjected to various levels of twist inserted under constant load. X-ray diffraction patterns of the twisted filaments were obtained and the axial dispersion of the crystalline regions was estimated from the azimuthal spreading of the equatorial diffraction arcs. The experimentally obtained values were compared with those calculated by assuming that the fiber under goes a uniform deformation. The data show that the crystalline orientation does not follow the macroscopic twist imparted to the filament. The discrepancy is largest at small twist angles, indicating that at this stage the twist is taken up primarily by regions that do not give rise to coherent x-ray scattering. At higher twist angles, there is indi cation that a tilting of crystallographic planes accompanies the reorientation of the crystallites. The effect of crystallite disorientation on the properties of the fibers is discussed.

Crystallite orientation in regenerated cellulose filaments. III. Crystallite orientation in viscose monofilaments

AbstractThree sets of regenerated cellulose monofilaments have been prepared from viscose. Two were stretched while still in the xanthate form and the third was stretched after regeneration to cellulose. X‐ray orientation measurements were taken around the 101 equatorial arc of x‐ray orientation measurements were taken around the 101 equatorial arc of x‐ray diagrams of filaments with different degrees of stretch. By plotting the orientation parameter, defined as the reciprocal of the angle at half the maximum intensity, against stretch, it was found that those filaments in which strong intermolecular bonding forces existed during the application of stretch reacted differently from those in which these forces were small. The presence of a well‐developed system of intermolecular bonds during stretch is found to prevent the attainment of the maximum theoretical orientation with high stretching forces. The Kratky rodlet theory is found to fit the results, and good fits are obtained for the theoretical intensity‐distribution curves predicted from it and those found experimentally. The Hermans x‐ray orientation factor fx was calculated from theoretical distribution curves, and the results plotted against stretch confirm those obtained from the orientation parameter.

The Crystallite Orientation in Different Varieties of Jute Fibers of Known Strength

The orientation of micelles in jute fiber of different varieties, both Tossa and White having different values of intrinsic strength and quality ratio, has been studied. The Hermans' orientation factor, average angle of orientation, and angle at 40% intensity of ten different samples of jute fibers have been determineed from the intensity distribution curves of the equatorial arcs, in the X -ray diffraction photograph. It has been ob served that the orientation factor and angle at 40% intensity have no correlation with the intrinsic strength, but there is a slight correlation if the two varieties of jute White and Tossa are taken separately. For the same value of strength these two varieties have different values of orientation factor. The quality ratio of the yarn has no correla tion with the orientation factor and the angle at 40% intensity. It has been further observed that the average angle of orientation varies from 8° to 9° approximately in the case of jute fibers, and Hermans' orientation factor varies from 0.96 to 0.97, whereas those of ramie are 7°36' and 0.973, respectively.

Evidence for α-Protein Structure in Polypeptides

CONTINUING our work on the structure of synthetic polypeptides1,2 we have recently spun fibres of a number of these products. The following is a preliminary review of the results of an X-ray examination of two—a copolymer of L-glutamic γ methyl ester with DL-β-phenylalanine (A), and poly DL-β-phenyl-alanine (B). fig. 1 and 2 are X-ray photographs of the former in disoriented and oriented states respectively ; Fig. 3 is a photograph of oriented fibre B. These diagrams show that both polymers have very similar structures. In A, the repeat along the fibre axis is 5·26 A., and it is possible that the intense equatorial reflexion can be resolved into two spacings of 11·7 A. and 11·2 A. ; the angular dispersion of the former arc is much greater in this particular specimen. The 11·7 A. and 11·2 A. spacings, therefore, appear to orient to different extents on stretching. In the powder diagram of the fibre, Fig. 1, the spacings are not resolved, and give a mean of 11·4 A. In B, the repeat along the fibre axis is 5·28 A., and the equatorial arc may perhaps again be resolved into a doublet of spacings—12·8 A. and 11·7 A. These two overlapping arcs again show differences in angular dispersion, that at 12·8 A. being the greater, but this is not so marked as in the former case.

A Journey on the Rio Zamora, Ecuador

The Andes of Ecuador part into two main parallel ranges, known as the Cordillera Occidental and Cordillera Oriental, united at intervals by transverse ridges of inferior height, designated by the Spanish topographical term of nudos, literally knots.l The southernmost of these is the Nudo de Cajanuma, which forms the divide between Pacific and AmazonAtlantic drainage; some twenty-five miles to the north is the Nudo de Acayana y Guagra-uma; and enclosed between the two and the lateral mountain chains is the Basin of Loja (Hoya de Loja). The opposite inner faces of the two Cordilleras are here physiographically similar, but the outer, or Pacific and Amazon versants, respectively, are in distinct contrast. The former, through the withering action of the hot, dry air currents borne up the Catamayo valley from the desert littoral of Peru, is bare of vegetation, while the latter, under the benign influence of perennial rains, is clothed with dense tropical forest. In the intermontane depression between the two ranges, at an elevation of 2,150 meters (7,053 feet) above sea level,2 stands the town of Loja. Due west of it the isolated and sharply outlined peak of Villonaco (3,220 meters, or 10,560 feet) rises from the relatively low profile of the Cordillera Occidental, forming a dominant feature of the local topography and a widely visible landmark. It is interesting to note that certain neighboring eminences, Fierro-urcu (3,788 meters, or 12,430 feet) and Colambo (3,094 meters, or 10,150 feet), were occupied as trigonometrical stations in the great triangulation carried from Tulcan, on the Colombian frontier, all through Ecuador down to Payta, in Peru, by the French geodetic commission in 1899-1906, in their revision and extension of the work of the academicians Bouguer, La Condamine, and Godin in the eighteenth century for the measurement of an equatorial arc of a meridian.3 The lower slopes of the Cordillera Oriental about the Hoya de Loja are