scholarly journals Effectiveness and Compatibility of a Novel Sustainable Method for Stone Consolidation Based on Di-Ammonium Phosphate and Calcium-Based Nanomaterials

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3025 ◽  
Author(s):  
Cecilia Pesce ◽  
Ligia M. Moretto ◽  
Emilio F. Orsega ◽  
Giovanni L. Pesce ◽  
Marco Corradi ◽  
...  
Keyword(s):  
Ammonium Phosphate ◽  
Pulse Velocity ◽  
X Ray ◽  
Artistic Value ◽  
Physical Chemical ◽  
Stone Consolidation ◽  
Colour Measurements ◽  
Combined Use ◽  
Water Absorption Test ◽  
Ultrasound Pulse

External surfaces of stones used in historic buildings often carry high artistic value and need to be preserved from the damages of time, especially from the detrimental effects of the weathering. This study aimed to test the effectiveness and compatibility of some new environmentally-friendly materials for stone consolidation, as the use thereof has been so far poorly investigated. The treatments were based on combinations of an aqueous solution of di-ammonium phosphate (DAP) and two calcium-based nanomaterials, namely a commercial nanosuspension of Ca(OH)2 and a novel nanosuspension of calcite. The treatments were applied to samples of two porous stones: a limestone and a sandstone. The effectiveness of the treatments was assessed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, ultrasound pulse velocity test, colour measurements, and capillary water absorption test. The results suggest that the combined use of DAP and Ca-based nanosuspensions can be advantageous over other commonly used consolidants in terms of retreatability and physical-chemical compatibility with the stone. Some limitations are also highlighted, such as the uneven distribution and low penetration of the consolidants.

scholarly journals An An Analysis of Crystalline Admixtures in Terms of Their Influence on the Resistance of Cementitious Composites to Aggressive Environments

2020 ◽  
Author(s):  
Ámos Dufka ◽  
Nikol Žižková ◽  
Jiří Brožovský
Keyword(s):  
Computed Tomography ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Mechanical Tests ◽  
Pulse Velocity ◽  
Cementitious Composites ◽  
Reference Laboratory ◽  
Chemical Analyses ◽  
X Ray ◽  
Physical Chemical

This paper describes the influence of crystalline admixtures on the chemical resistance of cement composites exposed to aggressive environments. The effect of the crystalline admixtures was determined by a series of physical-mechanical and innovative physical-chemical methods. Specifically, this concerned the measurement of flexural strength, compressive strength, determination of the dynamic modulus of elasticity by the ultrasonic pulse velocity test, and an analysis of the internal structure by mercury intrusion porosimetry and x-ray computed tomography. Physical-chemical analyses were also performed; namely an x-ray diffraction analysis to determine the mineralogical composition and electron microscopy to examine the microstructure. The use of non-destructive testing methods (ultrasonic pulse velocity test and computed tomography) made it possible to compare the properties of the same specimens for 16 months. The specimens were stored in reference laboratory conditions, a sodium sulphate solution and an ammonium chloride solution. The physical-mechanical tests and physical-chemical analyses clearly showed the benefit that crystalline admixtures have for the resistance of cementitious composites attacked by chemically aggressive solutions without affecting the fresh-mixture rheology or decreasing the strength of the composites.

Tracing young SMBHs in the dusty distant universe – a Chandra view of DOGs

2020 ◽  
Vol 15 (S359) ◽  
pp. 17-21
Author(s):  
Karín Menéndez-Delmestre ◽  
Laurie Riguccini ◽  
Ezequiel Treister
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Far Infrared ◽  
Host Galaxy ◽  
X Ray ◽  
Star Forming ◽  
Near Ir ◽  
X Ray Imaging ◽  
Combined Use ◽  
Dusty Galaxies

AbstractThe coexistence of star formation and AGN activity has geared much attention to dusty galaxies at high redshifts, in the interest of understanding the origin of the Magorrian relation observed locally, where the mass of the stellar bulk in a galaxy appears to be tied to the mass of the underlying supermassive black hole. We exploit the combined use of far-infrared (IR) Herschel data and deep Chandra ˜160 ksec depth X-ray imaging of the COSMOS field to probe for AGN signatures in a large sample of >100 Dust-Obscured Galaxies (DOGs). Only a handful (˜20%) present individual X-ray detections pointing to the presence of significant AGN activity, while X-ray stacking analysis on the X-ray undetected DOGs points to a mix between AGN activity and star formation. Together, they are typically found on the main sequence of star-forming galaxies or below it, suggesting that they are either still undergoing significant build up of the stellar bulk or have started quenching. We find only ˜30% (6) Compton-thick AGN candidates (NH > 1024 cm–2), which is the same frequency found within other soft- and hard-X-ray selected AGN populations. This suggests that the large column densities responsible for the obscuration in Compton-thick AGNs must be nuclear and have little to do with the dust obscuration of the host galaxy. We find that DOGs identified to have an AGN share similar near-IR and mid-to-far-IR colors, independently of whether they are individually detected or not in the X-ray. The main difference between the X-ray detected and the X-ray undetected populations appears to be in their redshift distributions, with the X-ray undetected ones being typically found at larger distances. This strongly underlines the critical need for multiwavelength studies in order to obtain a more complete census of the obscured AGN population out to higher redshifts. For more details, we refer the reader to Riguccini et al. (2019).

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

In vitro production of struvite by Bacillus pumilus

1991 ◽  
Vol 37 (12) ◽  
pp. 978-983 ◽  
Author(s):  
Berlin Nelson ◽  
James Struble ◽  
Gregory McCarthy
Keyword(s):  
Bacillus Pumilus ◽  
Potassium Phosphate ◽  
Ammonium Phosphate ◽  
Maximum Size ◽  
In Vitro Production ◽  
Magnesium Ammonium Phosphate ◽  
X Ray ◽  
Magnesium Ammonium ◽  
Vitro Production

A strain of Bacillus pumilus, isolated from the soilborne sclerotia of a fungus, produced crystals of the mineral struvite (magnesium ammonium phosphate hexahydrate) on Difco nutrient agar and a yeast extract agar containing magnesium sulphate and potassium phosphate. Crystals were macroscopically observed after 6–20 days of bacterial growth and reached a maximum size of 3 × 0.5 mm. Crystals were identified by X-ray powder diffractometry. These findings support the hypothesis that bacteria are involved in the biogenic formation of struvite in nature. Key words: struvite, magnesium ammonium phosphate hexahydrate, Bacillus pumilus, biomineral.

scholarly journals Ultrasonic, Molecular and Mechanical Testing Diagnostics in Natural Fibre Reinforced, Polymer-Stabilized Earth Blocks

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
C. Galán-Marín ◽  
C. Rivera-Gómez ◽  
F. Bradley
Keyword(s):  
Soil Stabilization ◽  
Ultrasonic Pulse Velocity ◽  
Mechanical Tests ◽  
Pulse Velocity ◽  
Mechanical Resistance ◽  
Chemical Compositions ◽  
Natural Polymer ◽  
Natural Polymers ◽  
X Ray ◽  
Earth Blocks

The aim of this research study was to evaluate the influence of utilising natural polymers as a form of soil stabilization, in order to assess their potential for use in building applications. Mixtures were stabilized with a natural polymer (alginate) and reinforced with wool fibres in order to improve the overall compressive and flexural strength of a series of composite materials. Ultrasonic pulse velocity (UPV) and mechanical strength testing techniques were then used to measure the porous properties of the manufactured natural polymer-soil composites, which were formed into earth blocks. Mechanical tests were carried out for three different clays which showed that the polymer increased the mechanical resistance of the samples to varying degrees, depending on the plasticity index of each soil. Variation in soil grain size distributions and Atterberg limits were assessed and chemical compositions were studied and compared. X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and energy dispersive X-ray fluorescence (EDXRF) techniques were all used in conjunction with qualitative identification of the aggregates. Ultrasonic wave propagation was found to be a useful technique for assisting in the determination of soil shrinkage characteristics and fibre-soil adherence capacity and UPV results correlated well with the measured mechanical properties.

scholarly journals Recycled Concrete Aggregate for Medium-Quality Structural Concrete

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4612
Author(s):  
Dong Viet Phuong Tran ◽  
Abbas Allawi ◽  
Amjad Albayati ◽  
Thi Nguyen Cao ◽  
Ayman El-Zohairy ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Pulse Velocity ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Predictive Equation ◽  
Recycled Concrete Aggregate ◽  
Structural Concrete ◽  
Medium Quality ◽  
Ultrasound Pulse

This paper reports an evaluation of the properties of medium-quality concrete incorporating recycled coarse aggregate (RCA). Concrete specimens were prepared with various percentages of the RCA (25%, 50%, 75%, and 100%). The workability, mechanical properties, and durability in terms of abrasion of cured concrete were examined at different ages. The results reveal insignificant differences between the recycled concrete (RC) and reference concrete in terms of the mechanical and durability-related measurements. Meanwhile, the workability of the RC reduced vastly since the replacement of the RCA reached 75% and 100%. The ultrasound pulse velocity (UPV) results greatly depend on the porosity of concrete and the RC exhibited higher porosity than that of the reference concrete, particularly at the transition zone between the RCA and the new paste. Therefore, the sound transmission in the RC required longer times than that in the reference concrete. Moreover, a predictive equation relating the compressive strength to the UPV was developed.

scholarly journals Experience of Using Hyperbaric Oxygenation in the Treatment of Radionecrosis That Developed as a Complication of Stereotactic Radiosurgical Treatment of Meningioma on the Example of a Clinical Case

2021 ◽  
Vol 9 (4) ◽  
pp. 670-676
Author(s):  
A. S. Tokarev ◽  
V. N. Stepanov ◽  
V. A. Rak ◽  
O. L. Yevdokimova ◽  
I. A. Terekhin ◽  
...  
Keyword(s):  
Clinical Picture ◽  
Hyperbaric Oxygenation ◽  
Radiation Necrosis ◽  
Late Complication ◽  
Intravenous Contrast ◽  
X Ray ◽  
Combined Use ◽  
Radiation Induced ◽  
Magnetic Resonance Imaging Mri ◽  
And Control

In contrast to conventional microsurgery, stereotactic radiosurgery has an advantage in the treatment of intracranial masses, avoiding severe complications associated with open surgery. In rare cases, the use of the method is associated with the development of radiation-induced injuries, one of which is radiation necrosis (RN). This is a late complication of radiosurgery, developing mainly 6 months after radiation exposure. The neurological manifestations of this complication depend on location, and the clinical picture is very diverse. The method of magnetic resonance imaging (MRI) with intravenous contrast enhancement is quite often the first link in neuroimaging, which helps to suggest the presence of this complication based on the X-ray picture and to clarify the location of changes.We presented the experience of radiation necrosis treatment in a 47-year-old patient who was referred to our department with a diagnosis of frontal meningioma. The patient underwent stereotactic radiosurgical treatment using the Elekta Leksell Gamma Knife Perfextion device, and 6 months later the gradual deterioration began, the patient complained of headache, nausea; central prosoparesis developed. Considering the clinical picture and control MRI data, the changes were interpreted as radionecrosis. In order to control the complication, the patient underwent standard glucocroticosteroid therapy, supplemented by hyperbaric oxygenation (HBO), which made it possible to achieve regression of the adverse clinical and radiological manifestations of the complication. Thus, on a clinical example, it was demonstrated that the combined use of glucocorticosteroids and HBOs is highly effective in the treatment of RN.

Poorly soluble, iron-aluminium phosphates in ammonium phosphate fertilizers: Their nature and availability to plants

Soil Research ◽  
1983 ◽  
Vol 21 (2) ◽  
pp. 183 ◽  
Author(s):  
RJ Gilkes ◽  
P Mangano
Keyword(s):  
Total Phosphorus ◽  
Powder Diffraction ◽  
Phosphorus Content ◽  
Ammonium Phosphate ◽  
Residual Value ◽  
Phosphate Fertilizers ◽  
Total Phosphorus Content ◽  
X Ray ◽  
Poorly Soluble ◽  
Residual Effectiveness

Both monoammonium and diammonium phosphate fertilizers contain various (Ca,Mg)(NH4)- (Fe,Al)(PO4)(F,OH)H2O compounds that are insoluble in water and comprise 4.9-9.9% of the total phosphorus content of the fertilizers. The compounds have been isolated and characterized by chemical, X-ray powder diffraction, ix., and thermogravimetric techniques. The compounds are only 35-60% as effective as monocalcium phosphate (MCP) in supplying phosphorus to wheat grown under glasshouse conditions. The residual effectiveness of the compounds for a second crop of wheat was generally lower (10-20% relative to freshly applied MCP) than the residual value of MCP (20 %).

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