The penetration of igneous basement in the Nazca Plate during DSDP Legs 16 and 34 provided samples of both fine-grained pillow-basalt and coarse-grained massive flow units. The magnetic mineral in these basalt samples is initially a titanomagnetite (Fe,Ti,O4) with a narrow range of composition of x = 0.62 f 0.05. Subsequent to formation, the titanomagnetite grains are generally subjected to low temperature oxidation to titanomaghemite with a corresponding rise in Curie temperature from the initial values of 120-150°C up to a maximum of 400°C. Both grain size and low-temperature oxidation state play important, and interrelated, roles in controlling the intensity and stability of magnetic remanence and other magnetic properties. Overall grain size can, in some cases, be related to oxidation state since some sections of the relatively impermeable massive flows can remain unoxidized for as long as 40 Myr while pillow basalts are extensively oxidized within 34 Myr. Low-temperature alteration in turn effects magnetic grain size since oxidation and subsequent Fe cation migration results in grain subdivision by the formation of shrinkage cracks. A five-stage sequence of the microscopic changes that are associated with progressive low-temperature oxidation is proposed and illustrated with photomicrographs from these basalt samples.A hierarchy in the intensity of magnetic remanence may exist with unoxidized pillow basalts having a much higher intensity and oxidized pillow basalts having a much lower intensity than the massive flow units. While pillow basalts are relatively immune to the addition of secondary components of magnetization, the coarse-grained massive flows readily acquire components of viscous remanence. Although they oxidize much more slowly than pillows, when oxidation does take place, components of chemical remanence can be acquired by the multi-domained grains in the massive flow units. 319319A 320 321

No abstract

The detailed study of 455 basement samples from DSDP Leg 37 reveals magnetic properties, particularly inclinations and intensities, different from those commonly considered representative of Layer 2. Non-dipole inclinations are the most common. The deepest hole (582 m) has a vector average intensity of 24.3 × 10−4 emu cm−3 (24.3 × 10−1 A/m) and an inclination of only −14.5°. Induced magnetization never dominates and is usually much less than remanent magnetization, with Q ratio averaging 35 for basalts and 2.6 for plutonic rocks. Viscous magnetization acquisition constant, S, ranges widely from 0.001 to 1 × 10−4 emu cm−3 (0.001 to 1 × 10−1A/m), but is very rarely sufficient to cause VRM to dominate NRM.The major carrier of NRM is cation-deficient titanomagnetite produced by low-temperature oxidation of stoichiometric titantomagnetite. There is no trend of alteration with depth. All the magnetic properties are controlled by conditions within the individual basalt pillows or more massive units. A high degree of cation deficiency is associated with reduced NRM intensity, initial susceptibility, saturation magnetization, and VRM acquisition and increased MDF, Q ratio, and Curie point. Zones of low cation deficiency are presently found only in parts of massive units. With the exception of rare individual samples pillow sequences are highly oxidized throughout.A discussion is given of the kinds of ocean crust drilling and laboratory experiments required to solve the problems of the magnetic structure of Layer 2 as seen at the Leg 37 sites.

Aerated n-dodecane as a liquid under 800-psig pressure has been passed over heated tubes at temperatures between 375 and 1000 °F (190-538 °C). The initial product, hydroperoxide, is stable to 550 °F (282 °C), but its decomposition at higher temperatures leads to alcohols, ketones, hydrogen, carbon monoxide, n-alkanes, and 1alkenes. Product yields increase only slightly between 725 and 900 °F (385-482 °C) since peroxide has completely disappeared at the lower temperature. Hydrocarbon pyrolysis reactions occur above 900 °F (482 °C) with greater yields for aerated n-dodecane than for oxygen-free liquid. Heater tubes fabricated from aluminum and two types of stainless steel, 304 and 316, yielded the same products and exhibited similar "temperature/ product concentration'' patterns.

An attempt has been made to identify the processes that give rise to a number of depth trends in the magnetization of a 3.1 km vertical section of Icelandic-type oceanic crust and to assess the possibility that similar processes act, and depth trends occur, in typical oceanic crust. The depth trends in the Icelandic section consist of a general increase in saturation and induced magnetization to 2 km crustal depth, below which flow magnetization decreases while dike magnetization remains constant, and of large changes in flow magnetization that occur on a scale of a few hundred metres below 3 km crustal depth.Increase in saturation and induced magnetization with depth in the upper 2 km is thought to be the result of two processes: a decrease in low-temperature oxidation from the original lava surface to 700–800 m crustal depth, thence an increase in hydrothermal alteration with depth. This interpretation is based on oxide petrography and Curie temperatures, which show a weakly defined minimum in the 700–800 m interval, then an increase to ubiquitous "magnetite" values at just below 2 km crustal depth. Although the relationship between magnetic properties and oxide alteration is reasonably well known for the low-temperature oxidation process from laboratory studies and ophiolite and typical ocean-crust analogs, the change in magnetic properties during hydrothermal alteration is not generally known, nor are ophiolite or typical ocean-crust analogs presently available.Decrease in flow saturation and induced magnetization below 2 km is likely to be the result of alteration of magnetite (sensu lato) to nonmagnetic phases, either on a fine scale to hematite (s.l.) between 2 km and 3 km, or by leaching of iron, leaving anatase pseudomorphs after magnetite (s.l.) below 3 km. The relatively low porosity of the dikes is likely to have protected dike magnetite below 2 km from such oxidation and leaching processes.The study confirms that secondary magnetite in several forms is an important magnetic constituent of the flows in the lower part of the section, particularly where decomposition of primary magnetite is widespread. Secondary magnetite occurs as vermiform or bladelike masses, as rims associated with former silicates, or as fresh continuous magnetite occurring either as subhedral grains or as "reconstructed" primary grains in which relics of sphene-replaced ilmenite lamellae grids are seen.In conclusion, the possibility that the near-surface magnetization of typical ocean crust is commonly the minimum value for a layer extending downwards to the onset of an epidote-bearing facies deserves serious consideration, as does the possibility that strong, stable magnetization of secondary origin occurs in flows where dike density becomes significant.

Extragnathic xanthomas are seen in the bones or as soft tissue masses. They are often associated with hyperlipidemia and are considered as reactive or metabolic lesions. Only 19 cases of xanthomas of the jaws have been reported so far in the English literature. A total of ten cases of central xanthoma of the jaw bones were identified from the Oral and Maxillofacial Pathology biopsy services of the University of Washington and the Tufts University School of Dental Medicine, between the years 2000-2016. The demographic and clinical information on these cases was tabulated logically on the basis of age, gender, location and presence or absence of symptoms, extragnathic lesions and serum hyperlipidemia. Radiographic and histopathological features were also examined. The findings in these cases were correlated with those available from the previously reported cases. Majority of cases are seen in the second and third decades of life. There is no gender predilection. Jaw lesions presented as solitary radiolucencies with a predilection for the posterior mandible. Unlike maxillary lesions, pain and expansion are inconsistent findings in mandibular lesions. Jaw lesions are not associated with extragnathic bone or soft tissue involvement or a hyperlipidemia. The central xanthoma of the jaws is a unique benign tumor. Histopathologically, many other jaw lesions contain variable numbers of foamy histiocytes. Therefore, a diagnosis of a central xanthoma of the jaws must be made after excluding all other such histiocyte containing lesions. This requires correlation of histopathological findings with clinical and radiographic features.

What we believe to be the first demonstration of isotope-specific detection of a low-Z and low density object shielded by a high-Z and high-density material using monoenergetic gamma rays is reported. The isotope-specific detection of LiH shielded by Pb and Al is accomplished using the nuclear resonance fluorescence line of L7i at 478 keV. Resonant photons are produced via laser-based Compton scattering. The detection techniques are general, and the confidence level obtained is shown to be superior to that yielded by conventional x-ray and gamma-ray techniques in these situations.

Excess nitrite (NO2 -) concentrations in water supplies is considered detrimental to the environment and human health, and is associated with incidence of stomach cancer. In this work, the authors describe a nitrite detection system based on the synthesis of gold nanoparticles (AuNPs) on reduced graphene oxide (rGO) using an aqueous solution of chitosan and succinic acid. The AuNPs-rGO nanocomposite was confirmed by different physicochemical characterization methods including transmission electron microscopy, elemental analysis, X-ray diffraction, UV-visible (UV-vis) and Fourier transform infrared spectroscopy. The AuNPs-rGO nanocomposite was applicable to the sensitive and selective detection of NO2 − with increasing concentrations quantifiable by UV–vis spectroscopy and obvious to the naked eye. The color of the AuNPs-rGO nanocomposite changes from wine red to purple with the addition of different concertation of NO2 −. Therefore, nitrite ion concentrations can be quantitatively detected using AuNPs-rGO sensor with UV-vis spectroscopy and estimated with the naked eye. The sensor is able to detect NO2 − in a linear response ranging from 1 to 20 μM with a detection limit of 0.1 μM by spectrophotometric method. The as-prepared AuNPs-rGO nanocomposite shows appropriate selectivity towards NO2 − in the presence of potentially interfering metal anions.