Search results for " mine"
showing 10 items of 747 documents
The Bi sulfates from the Alfenza Mine, Crodo, Italy: An automatic electron diffraction tomography (ADT) study
2014
We report about three bismuth sulfates from mineralized quartz dikes from Alfenza (Crodo, Italy), two new phases and a rare mineral, cannonite, all growing on bismuthinite. The first new phase occurs as white, "hortensia-like" aggregates of pseudo-hexagonal platelets, with perfect basal cleavage, similar to 20 mu m wide and few micrometers thick. The approximate composition is Bi2O2(SO4), and cell parameters and symmetry, as determined by automatic diffraction tomography, are a = 22.0(4), b = 16.7(3), c = 15.9(3) angstrom, beta = 102.9(5)degrees, space group Pc or P2/c. A major stacking disorder is detected by HR-SEM images and electron diffraction data.The second new phase was detected onl…
Caracterización mineralógica de materias primas cerámicas por métodos cuantitativos de difracción de rayos x
2002
[ES] El objetivo de este trabajo es la caracterización de fases minerales presentes en materias primas utilizadas en la industria cerámica. Para ello se utilizan dos métodos cuantitativos basados en la difracción de rayos X, el método de Rietveld y un método sin estándar. Los resultados obtenidos por difracción rayos X de estos materiales policristalinos se comparan con los correspondientes análisis químicos y la composición normativa calculada. La precisión y reproducibilidad de los resultados obtenidos, en concordancia con los del análisis químico, son una de las más importantes ventajas de la difractometría cuantitativa que facilitan su utilización en la industria cerámica en el control …
Retention of Vanadium(V), Molybdenum(VI) and Tungsten(VI) by Kaolin
1993
Abstract The ability of kaolin (approximately H2Al2Si2O8 · H2O), a well known clay mineral constituent, to retain V(V) andMo(VI) species from 10−5 and 10−4 M solutions, and W(VI) species from 10−4 M solutions was investigated in the pH range 2–7.5 using a solid/liquid ratio 1:100 (w:v). The equilibration time in the adsorption studies was 72 h, and the shaking time in the desorption studies was 17 h. 0.02 M KCl was used as ionic medium and desorbing liquid. V(V), Mo(VI) and W(VI) were all retained by kaolin to some extent, and the amounts of the elements which could be washed away from kaolin with 0.02 M KCl were very small. The pH dependence of the adsorption was considerable: when added a…
Abdominal fat quantity and distribution in women with polycystic ovary syndrome and extent of its relation to insulin resistance.
2007
Composizione corporea in relazione alla sindrome dell'ovaio policistico. Increased abdominal fat has been linked to insulin resistance and increased cardiovascular risk. Because many patients with polycystic ovary syndrome (PCOS) present abdominal obesity, it may be the cause of insulin resistance in this disorder.Setting: Fat quantity and distribution were evaluated by dual x-ray absorptiometry at the Departments of Clinical Medicine at the University of Palermo and the University of Naples, Italy.Patients: A total of 110 patients with PCOS and 112 weight-matched controls were studied. Anthropometric data, blood glucose, serum insulin, and testosterone were evaluated. Total, trunk, and cen…
In vivo vibrational wave propagation in human tibiae at different ages
1989
Vibrational wave propagation was tested in vivo on the tibial bone of both legs of 56 female volunteers. The impact was produced by a hammer with a force strain gauge and the response was monitored by two accelerometers. The peak amplitude of the accelerations, the velocity of the acceleration wave propagation and damping were analysed for comparison among the different age groups. The results showed significant negative correlations between age and the peak amplitude of acceleration, and the velocity of acceleration wave propagation (p less than 0.01). The damping time of the acceleration wave also had a negative correlation with age. These findings suggested that age differences were rela…
The effects of calorie restriction, intermittent fasting and vegetarian diets on bone health.
2019
Uncountable health care organizations, clinicians, and individuals are striving to prevent obesity and the many chronic medical conditions linked to it by advocating a healthy lifestyle that includes measures such as reducing dietary calorie intake (i.e., calorie restriction = CR and intermittent fasting = IF) or limiting/abolishing animal source foods (i.e., practices termed vegetarianism and veganism). Although these regimens are traditionally considered healthy, their real impact on bone health has yet to be established, and some studies have reported that they have negative effects on bone outcomes. The current work provides an overview of the studies carried out to examine the effect/s…
25-hydroxy vitamin D levels in healthy premenopausal women: Association with bone turnover markers and bone mineral density
2008
Abstract Background Vitamin D deficiency is very common in elderly people while there are very few reports on its incidence, determinants and metabolic consequences in young subjects. Results In 608 young healthy premenopausal women participating in the BONTURNO study, levels of 25-hydroxyvitamin D [25(OH)D] below 20 ng/ml were found in almost a third of the women. Its levels were inversely ( P 2 ) and directly with sunlight exposure during the summer time, and latitude: i.e. the higher the latitude over Italy, the higher the 25(OH)D level. In women on contraceptive pill the mean 25(OH)D level was significantly increased even when the data were adjusted for age, BMI and sun exposure. 25(OH)…
In-vivo investigation of material quality of bone tissue by measuring apparent phalangeal ultrasound transmission velocity
1995
The square of ultrasound transmission velocity in a material is related to the modulus of elasticity, which is known to be an indicator of stability in bone. The aim of our study was to use ultrasound transmission velocity to obtain information about the material properties of bone tissue, keeping other factors possibly influencing ultrasound transmission as constant as possible. Apparent phalangeal ultrasound transmission velocity (APU) measured in 54 isolated, fresh pig phalanges was shown to be independent of bone mineral density (BMD) measured by SPA. Fastest sound transmission led exclusively through cortical bone so that intertrabecular connectivity in spongious bone could not influen…
Validation of a mechanical method for measuring skin thickness: relation to age, body mass index, skin thickness determined by ultrasound, and bone m…
2009
In a number of endocrine disorders, typical changes in skin thickness can be observed which make measurement of skin thickness interesting in this field. A newly developed mechanical method for measuring skin thickness is presented. Using a digital measuring screw on the dorsum of the hand with a defined measuring force of 10 newton and a resulting tissue compression of 1500 mm Hg, highly reproducible results were obtained (mean coefficient of variation 2.56%). In 129 women, 37 to 78 years old, body mass index < 30 kg/m2, there was no significant relation between body mass index and skin fold thickness. A negative correlation between skin fold thickness and age (r = 0.37, p < 0.001) was det…
The mandibular angle in osteoporotic men
2010
Objectives: Osteoporosis induces the reduction of bone mass and screening for low bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA) has been the current gold standard test to determine osteoporosis. Panoramic radiography is widely used in dentistry for routine examination of jaws. The objective of this study was to determine the relationship between the mandibular angle (MA) values and the vertebral bone mineral density (v-BMD) in 20 osteoporotic men. Study design: In panoramic radiograms of osteoporotic men, the means were calculated for the mandibular angle values measured in the right and left mandible. v-BMD values were also calculated by manual analysis of DXA scans.…