11,347 research outputs found
THE PALEORADIOLOGY IMPORTANCE IN THE STUDY OF RELICS: THE UNIQUE DENSITOMETRIC ANALYSIS OF A BONE RELIC OF SAINT NICHOLAS
No full textDXA have greatly contributed to the development of paleoradiology, a branch of diagnostic imaging that allows to obtain information about human remains in contexts of archaeological and/or forensic interest. In this manuscript we report the unique experience of DXA performed on the relic of a Saint; in particular we analyzed a skeletal fragment of St. Nicholas, kept in the Basilica of Bari (Italy) since 1087. MATERIALS AND METHODS: The bone to be examined consisted of the posterior arch of the ninth left rib that was 12cm long, 1.2cm maximum width and 1.7cm thick at the body. The data acquired from the densitometric study were performed using the anthropometric measures reported in historical records of St. Nicholas' life: sex (male), age (75 years), weight (70kg), height (167cm), and ethnicity (Caucasian). In addition to the examination of the relic, a comparison assessment was made with the rib of a healthy 60 years old man (height of 170cm, without known skeletal pathologies). This sample had a length of 19cm, maximum width at the head 1cm, and 0.7cm thick at the body. The analysis of bone fragments is different from the analysis of bones in the context of the human body (where soft tissues are placed around the skeleton); for this reason, one of the most critical issues was to create a support that would allow the analysis of bone fragments. We simulated conditions similar to those occurring in patients: a density scale was established, using a specific plexiglass phantom on which the bone fragments to be examined were placed. From the analysis it was calculated the parameter bone mineral density (BMD), express in g/cm2, that indicates the relation between mass of bone mineral content and area of examined bone segment. BMD data was compared to a range normalized by age, sex and ethnicity (BMD-N). RESULTS: The results of the scannnig of St. Nicholas' rib showed a BMD of 0.97g/cm2 with a BMD-N between 0.77 and 1.08g/cm2. Simultaneous measurements of the relic compared with a reference rib showed highlighted BMD of 0.84g/cm2 for the relic and 0.50g/cm2 for the reference rib. The St. Nicholas data are 168% higher than reference bone. All our measurements of the relic indicated a high bone mineral density, most likely due to the presence of a high concentration of calcium salts. A relatively higher mineral density of the relic was seen compared to the healthy subject's rib. From the history of St Nicholas' life, we know of the long imprisonment at the age of 51 in damp and unhealthy environment. The results of this study suggest that a good bone mineral density was maintained by the Saint even in old age. An additional element that can influence bone mineral density is diet, certainly different during the time of St. Nicholas. The good bone densitometry indicates that the Saint maintained a proper diet, with a generally fair state of health. CONCLUSION: For this first DXA analysis of the rib relic of Saint Nicholas was necessary a long and complex experimental work to modify standard technique procedure to particular and unusual sample and Create specific supports and complementary instruments. Perform DXA analysis on relics permit to obtain additional information to living conditions, economical situation, behaviours, diet, diseaes, conservations conditions of remains, change of life style in different age. Our experimental work, the first of its kind, creates the way to analyze precious relics that often include only few bone fragments and data obtained by our work can be useful for a better management and movement of fragile relics. We ourselves are working on a new challenge for the analysis of bone finds from shipwrecks found at the bottom of the sea
Prevalence and clinical significance of incidental extra-skeletal findings detected on the unenhanced CT portion of PET/CT performed in Multiple Myeloma patients
No full textUse of amyloid PET/CT with 18 F-Florbetaben in the management of patients with Alzheimer's disease
No full textIntroduction and aim: Amyloid PET/CT is an "in vivo" imaging that may radically change management of Alzheimer's disease (AD) thanks to its ability to identify AD at the earliest stage. A diagnosis of dementia is currently made in terms of probability and is based on clinical evaluation (neuropsycological tests) as well as on the results of morphological imaging investigations (MRI) that can be supported by biohumoral (CSF analysis), and functional imaging only in the case of uncertain diagnosis of disease. The present study aimed to evaluate the role of amyloid PET/CT in the management of patients with suspicion of AD, through comparison with instrumental and clinical evaluation.
Methods: 38 consecutive patients with suspicion of AD (23 female, 15 male; median age 63 years old, range 46-72), who performed 18F-florbetaben PET/CT, were retrospectively reviewed. All of them performed a previous instrumental evaluation. A subgroup of patients (24/38) were evaluated with Mini Mental State Examination (MMSE). Cohen's K test was used as a measure of agreement between previous instrumental examinations/clinical evaluation and beta-amyloid PET results.
Results: Twenty-five/38 (65.8%) amyloid PET/CT scans resulted positive for amyloid deposition. Among the four target regions, precuneus was the most frequently involved. Previous instrumental evaluation was: MRI in 26/38 patients (24/26 positive for atrophy), CT in 9/38 (8/9 positive for atrophy), perfusion SPECT in 12/38 (8/12 areas of hypo-perfusion), 18F-FDG PET/CT in 2/38 (1/2 hypometabolism in frontal cortex). The agreement between previous instrumental examinations and beta-amyloid PET results was low (K= 0.084). In the subgroup of 24/38 patients, MMSE was scored positive (MMSE<24) in 14/24 (58.4%) and negative (MMSE>24) in 10/24 (41.6%). The agreement between clinical evaluation (MMSE) and beta-amyloid PET results was fair (K= 0.217).
Conclusion: The low agreement between amyloid PET/CT and previous clinical and instrumental assessments that we found in our study suggests that the amyloid PET/CT provides additional and early information. To perform an early and differential diagnosis of AD could have a great impact on the patient's management and cost of care in order to perform the correct therapeutic interventions and to allow family members to manage adequately the patient's demanding care
Polarization dependence of the light coupling to surface plasmons in an Ag nanoparticle & Ag nanowire system
No full textPolarization dependence of the coupling of excitation light to surface plasmon polaritons (SPPs) was investigated in a Ag nanoparticle-nanowire waveguide system (a Ag nanoparticle attached to a Ag nanowire). It was found that under the illumination of excitation light on the nanoparticle-nanowire junction, the coupling efficiency of light to SPPs depends on the polarization of the excitation light. Theoretical simulations revealed that it is the local near-field coupling between the nanoparticle and the nanowire that enhances the incident light to excite the nanowire SPPs. Because the shapes of the Ag nanoparticles differ, the local field intensity, and thus the excitement of the nanowire SPPs, vary with the polarization of the excitation light.Physics, MultidisciplinarySCI(E)EI中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)[email protected]
Effects of shell thickness on the thermal stability of Cu-Ag core-shell nanoparticles: A molecular dynamics study
No full textCu-Ag core-shell (CS) nanoparticle (NP) is considered as a cost-effective alternative material to nano silver sintering material in die attachment application. To further reduce the cost, the thickness of the Ag shell can be adjusted. Whereas the shell thickness will also affect the thermal stability of the Cu-Ag CSNPs. In this study, molecular dynamics simulation was applied to study the thickness effect on the thermal behavior of Cu-Ag CSNPs. The melting points of CSNPs and Pure NPs can be determined by the evolutions of Potential Energy (PE), and the Lindemann index (LI) of the system. The results indicated that the melting points of CS NPs were lower than monometallic NP and the melting point of CS NP is influenced by the size of the Cu core and the number of lattice mismatches. Moreover, the distribution of atoms’ LI showed that the premelting point is independent of shell thickness. However, the fraction of atoms that occurred premelting is increased with the decrease of the shell thickness. Otherwise, we also simulated the sintering process of double CS NPs with equal size.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
Search for direct CP-violation in K+- --->pi+ pi0 pi0 decays.
No full textA search for direct CP-violation in K± → π± π0 π0 decay based on 47.14 million events has been performed by the NA48/2 experiment at the CERN SPS. The asymmetry in the Dalitz plot linear slopes Ag = (g+ - g-) / (g+ + g-) is measured to be Ag = (1.8 ± 2.6) × 10-4. The design of the experiment and the method of analysis provide good control of instrumental charge asymmetries in this measurement. The precision of the result is limited by statistics and is almost one order of magnitude better than that of previous measurements by other experiment
Voltammetric Detection of Urea on an Ag-Modified Zeolite- Expanded Graphite-Epoxy Composite Electrode
No full textIn this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy) was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting electrolyte. This modified electrode exhibited moderate electrocatalytic effect towards urea oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus urea concentration was reached using square-wave voltammetry in the concentrations range of urea between 0.2 to 1.4 mM, with a relatively low limit of detection of 0.05 mM. A moderate enhancement of electroanalytical sensitivity for the determination of urea at EG-Ag-Z-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric/amperometric quantification.ChemE/Chemical EngineeringApplied Science
Ore mineralogy and trace element (re)distribution at the metamorphosed Lappberget Zn-Pb-Ag-(Cu-Au) deposit, Garpenberg, Sweden
No full textQualitative and quantitative mineralogical and textural investigations were undertaken for the different sulfide minerals in the 1.89 Ga Lappberget deposit, with a focus on sphalerite and pyrite. Three sphalerite types were identified and associated with: (1) main massive sulfide mineralization, (2) Fe-Mn skarn ore, and (3) Ag-rich fissure veins. Sphalerite-1 contained a relatively higher amount of trace elements (Fe, Co, Ge, Cu, Sn, and Au) but is lower in Mn/Fe, Ga, and Hg compared to sphalerite-2. Evidence of tectono-metamorphic modification of sulfides is observed throughout the deposit, such as the formation of growth twins and deformation twins in sulfides, the development of high-angled triple-point junctions in recrystallized pyrite and sphalerite, and the formation of â??ball oreâ?? or â??durchbewegungâ?? textures within mineralized shear zones. The recrystallization of pyrite and galena may have led to the re-distribution of fluid-mobile elements (As, Cu, Zn, Pb, Ag, and Au), some of which were deposited in discordant Ag-rich fissure veins peripheral to the main massive sulfide lenses. Trace element signatures of sulfides in Lappberget are compatible with the other metamorphosed and deformed, subseafloor volcanogenic carbonate replacement (SVALS)-type deposits in the Bergslagen mining district. © 2021 The Author(s)</p
Ore mineralogy and trace element (re)distribution at the metamorphosed Lappberget Zn-Pb-Ag-(Cu-Au) deposit, Garpenberg, Sweden
No full textQualitative and quantitative mineralogical and textural investigations were undertaken for the different sulfide minerals in the 1.89 Ga Lappberget deposit, with a focus on sphalerite and pyrite. Three sphalerite types were identified and associated with: (1) main massive sulfide mineralization, (2) Fe-Mn skarn ore, and (3) Ag-rich fissure veins. Sphalerite-1 contained a relatively higher amount of trace elements (Fe, Co, Ge, Cu, Sn, and Au) but is lower in Mn/Fe, Ga, and Hg compared to sphalerite-2. Evidence of tectono-metamorphic modification of sulfides is observed throughout the deposit, such as the formation of growth twins and deformation twins in sulfides, the development of high-angled triple-point junctions in recrystallized pyrite and sphalerite, and the formation of â??ball oreâ?? or â??durchbewegungâ?? textures within mineralized shear zones. The recrystallization of pyrite and galena may have led to the re-distribution of fluid-mobile elements (As, Cu, Zn, Pb, Ag, and Au), some of which were deposited in discordant Ag-rich fissure veins peripheral to the main massive sulfide lenses. Trace element signatures of sulfides in Lappberget are compatible with the other metamorphosed and deformed, subseafloor volcanogenic carbonate replacement (SVALS)-type deposits in the Bergslagen mining district. © 2021 The Author(s)</p
A comparative study in CCl4 reaction on Ag/Si(111) surfaces: PEEM and PES investigations
No full textA comparative study in CCl4 reaction on Ag/Si(111) surfaces: PEEM and PES investigations
Yunxi Yao, Qiang Fu, Xinhe Bao
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P.R. China
We report a comparative study in the reactivity of bulk Ag(111), monolayer Ag film on Si(111), and Si(111)-77 surfaces via X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), photoemission electron microscopy (PEEM), and scanning tunneling microscopy (STM). The monolayer Ag film grown on Si(111), which is known as √3×√3-Ag-Si surface structure, was obtained by depositing one monolayer Ag on the Si(111)-77 surface at 550 K. The most simple halogen methane, CCl4, was chosen as the probe molecule to study the surface reactivity of the bulk Ag(111) surface, the monolayer Ag film, and the Si(111) surface. XPS and UPS data indicate that the monolayer Ag film presents unique reactivity to CCl4 in comparison to the other two surfaces. For the PEEM study, a dedicated sample consisting of bulk Ag particles supported on the monolayer Ag film was prepared as shown in the schematics in Fig. 1. In situ PEEM imaging of the surface reaction in presence of CCl4 shows a gradual change in the grey intensity from bright to totally dark on the Ag particles but little change on the √3×√3-Ag-Si surface. The grey intensity decrease is due to local work function increase from the dissociated Cl atoms. The experiments suggest that monolayer Ag is inert toward dissociation of CCl4 compared to the Ag(111) and Si(111) surface. It has proposed that the confinement of 5sp electron of Ag atoms in the √3×√3-Ag-Si surface, which is delocalized in the bulk Ag(111) surface, is decisive to the different reactivity.
Figure 1: (a) Schematic representation of the √3×√3-Ag-Si surface supported Ag islands; (b) PEEM image of the Ag islands/√3×√3-Ag-Si sample before CCl4 exposure. Field of view (FoV) is 27 μm; (c) PEEM image shows the same area in (b) but after 24 L (5.2×10-9 mbar × 6000 s) CCl4 exposure; (d) the work function change (ΔΦ) of the Ag(111) and √3×√3-Ag-Si surfaces when exposed to different amount of CCl4 at RT, measured from PES results.
References:
[1] Y.X. Yao, X. Liu, Q. Fu, W.X. Li, D.L. Tan, X.H. Bao, ChemPhysChem 2008, 9: 975-979.
*Corresponding author: Fax: +86-411-84694447, E-mail: [email protected], [email protected]
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