scholarly journals Synthetic calcium carbonate improves the effectiveness of treatments with nanolime to contrast decay in highly porous limestone

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Radek Ševčík ◽  
Alberto Viani ◽  
Dita Machová ◽  
Gabriele Lanzafame ◽  
Lucia Mancini ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Stone Decay ◽  
Micro Computed Tomography ◽  
Non Invasive ◽  
Matrix Microstructure ◽  
Particle Size And Shape ◽  
Positive Effect ◽  
Highly Porous ◽  
Negligible Contribution

Abstract Three synthetized polymorphs of calcium carbonate have been tested in combination with the suspension of nanolime particles as potential consolidating agents for contrasting stone decay and overcome some of the limitations of nanolime agents when applied to substrates with large porosity. The modifications induced in the pore network of the Maastricht limestone were analyzed with microscopy and in a non-invasive fashion with small angle neutron scattering and synchrotron radiation micro-computed tomography. A reduction in porosity and pore accessibility at the micrometric scale was detected with the latter technique, and ascribed to the improved pore-filling capacity of the consolidation agent containing CaCO3 particles. These were found to be effectively bound to the carbonated nanolime, strengthening the pore-matrix microstructure. Penetration depth and positive effect on porosity were found to depend on the particle size and shape. Absence of significant changes in the fractal nature of the pore surface at the nanoscale, was interpreted as indication of the negligible contribution of nanolime-based materials in the consolidation of stones with large porosity. However, the results indicate that in such cases, their effectiveness may be enhanced when used in combination with CaCO3 particles, owing to the synergic effect of chemical/structural compatibility and particle size distribution.

Dextran-induced modifications of calcium carbonate particles precipitated during carbonatation

2019 ◽  
pp. 382-391
Author(s):  
Karin Abraham ◽  
Liza Splett ◽  
Eckhard Flöter
Keyword(s):  
Particle Size ◽  
Image Analysis ◽  
Calcium Carbonate ◽  
Filter Cake ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Shape Parameters ◽  
Size And Shape ◽  
Static Image ◽  
Particle Size And Shape

The effects of high and low molecular mass dextran (T2000 and T40) on the size and shape of particles precipitated during carbonatation and their correlation with filtration performances were key to this study. Varying contents of T2000 and T40 dextran in sugar solutions corresponding to DS contents of thin juice were investigated. For particle size and shape analysis, static image analysis and laser particle size analysis were used. Both methods, static image analysis and laser diffraction, revealed that the presence of T2000 and T40 dextran leads to a higher amount of large-sized particles at the expense of small-sized particles, indicating pronounced agglomeration. The additional evaluation of shape parameters (circularity, roundness, solidity) obtained from static image analysis indicates that the agglomeration is oriented in the absence and in the presence of lower T40 dextran levels. Besides, non-oriented agglomeration, resulting in more round agglomerates with smoother surfaces, was found for samples loaded with T2000 dextran and high T40 dextran levels. Only the latter samples have shown to negatively affect the filtration performance. Thus, in the presence of T2000 dextran and high T40 dextran levels, the filtration was hampered. This appears to be mainly caused by a tighter packing of more round calcium carbonate agglomerates in the porous structure of the filter cake.

Antiwear Properties of Commercial Grease as a Function of Particle Morphology and Uniformity of the As-Synthesized Calcium Carbonate Additive

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Khalida Akhtar ◽  
Saniya Yousafzai
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Tribological Properties ◽  
Particle Morphology ◽  
Optimum Amount ◽  
Lithium Grease ◽  
Antifriction Additive ◽  
Key Factor ◽  
Antiwear Properties ◽  
Particle Size And Shape

Abstract Calcium carbonate powder comprising uniform nanoparticles of novel morphology was synthesized under extensively optimized trial parameters. The as-prepared ultrafine rod shape CaCO3 particles after characterizations were used as an antiwear/antifriction additive in commercial lithium grease (CLG) of different specifications. The effect of the added particles on the antifriction and antiwear properties of the blended commercial greases was explored by using a ball-on-disk tribometer. The observed data were compared with the additized grease having commercially available CaCO3 powder. Results exposed that uniformity in particle size and shape is a key factor for the improvement of tribological properties and reproducibility of the experimental results. Therefore, the as-prepared monodispersed rod shapes CaCO3 particles as additives considerably improved the tribological properties of the CLG as compared with the irregular particles of the commercial calcium carbonate. These blends showed the best results at the optimum amount of 3 wt% of the added CaCO3 particles. Among the three selected greases, the additized Momin grease exhibited best antiwear/antifriction performance as compared with the additized Awami and Sinopec greases.

Effect of CO2 Flow Rate on the Synthesis Nanosized Precipitated Calcium Carbonate, PCC

2013 ◽  
Vol 481 ◽  
pp. 72-75
Author(s):  
O. Nooririnah ◽  
Azwar Azhari Muhamad ◽  
Y. Yusliza ◽  
Abreeza Manap ◽  
M.J. Md Ashadi
Keyword(s):  
Particle Size ◽  
Wastewater Treatment ◽  
Calcium Carbonate ◽  
Ionic Strength ◽  
Calcium Hydroxide ◽  
Flow Rate ◽  
High Purity ◽  
Precipitated Calcium Carbonate ◽  
Particle Size And Shape ◽  
Spraying Method

The precipitated of calcium carbonate has attractedmuch attention because of its numerous applications in various areas of plastics, textiles, rubbers, adhesives, paints and wastewater treatment. Nanosized of precipitated calcium carbonate,(PCC) will enhance the properties and give better performance. Its high purity and close controlled particle size and shape are making it the white filler of choice. Nanosized precipitated calcium carbonate particles were prepared using spraying method. The particles were prepared using three (3) different concentrations of Calcium Hydroxide,Ca (OH)2, three (3) CO2flow rate and three (3) different calcinations temperature. The three (3) concentration of Calcium Hydroxide that been used are 25g/200ml, 25g/ 400ml and 25g/800ml and each of these initial solution sprayed at three (3) different CO2flow rate, 5l/per-minute, 7l/per-minute and 10l/per-minute. Calcium Carbonate, CaCO3powders were then calcined at three (3) different temperature, 1100°C,1200°C and 1300°C. Images from SEM showed morphology of the particles changed to spindle-like or prismatic when the ionic strength of the Calcium Hydroxide, Ca (OH)2was increased.

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

2020 ◽  
Vol 27 (22) ◽  
pp. 3623-3656 ◽  
Author(s):  
Bruno Fonseca-Santos ◽  
Patrícia Bento Silva ◽  
Roberta Balansin Rigon ◽  
Mariana Rillo Sato ◽  
Marlus Chorilli
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Drug Release ◽  
Drug Loading ◽  
Average Particle Size ◽  
Delivery Systems ◽  
Average Particle ◽  
Minor Importance ◽  
Routes Of Administration ◽  
Non Invasive

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

scholarly journals Impact of Coseismic Frictional Melting on Particle Size, Shape Distribution and Chemistry of Experimentally-Generated Pseudotachylite

2020 ◽  
Vol 8 ◽  
Author(s):  
Leny Montheil ◽  
Virginia G. Toy ◽  
James M. Scott ◽  
Thomas M. Mitchell ◽  
David P. Dobson
Keyword(s):  
Particle Size ◽  
Host Rock ◽  
Fractal Dimensions ◽  
Rock Composition ◽  
Slip Rates ◽  
Shape Distribution ◽  
Frictional Behavior ◽  
Particle Size And Shape ◽  
Frictional Melting ◽  
Glass Compositions

In natural friction melts, or pseudotachylites, clast textures and glass compositions can influence the frictional behavior of faults hosting pseudotachylites, and are, in turn, sensitive to the processes involved in pseudotachylite formation. Quantification of these parameters in situations where the host rock composition and formation conditions are well-constrained, such as analogue experiments, may yield calibrations that can be employed in analysis of natural pseudotachylites. In this paper, we experimentally-generated pseudotachylites in granitoid rocks (tonalite and Westerly granite) at Pconf = 40 MPa and slip rates of ∼0.1 m s−1, comparable to the conditions under which natural pseudotachylite is known to form in Earth’s upper crust. We find variations in both clast textures and glass compositions that reflect formation processes, and probably influence the frictional behavior of similar natural faults hosting pseudotachylite. Quantification of particle size and shape distribution with a semi-automatic image analysis method, combined with analysis of glass and host-rock composition of these experimentally generated pseudotachylites, reveals that the textures of pseudotachylite material evolved by combinations of 1) comminution, 2) heterogeneous frictional flash melting, and 3) homogeneous (diffusive) clast melting and/or marginal decrepitation. Fractal dimensions of pseudotachylite-hosted clasts (D ∼ 3) that are greater than those of marginal fragmented host rock particles (gouge, D ∼ 2.4), reflect an increase of the intensity of comminution by slip localisation during a pre-melting phase. Chemical analyses demonstrate that these pseudotachylite glasses were generated by frictional flash melting, where host rock phases melt individually. Biotite is the least resistant to melting, feldspar intermediate, and quartz is the most resistant. The peudotachylite glass generated in these experiments has an alkaline composition, is depleted in SiO2 compared to the bulk host-rock, and shows heterogeneous compositions in a single sample related to proximity to host-rock minerals. The percentage contributions of host rock phases to the melt, calculated by a mixing model, shows that glass compositions are dominated by plagioclase and biotite. Within the melt, margins of clasts were dissolved uniformly by diffusion and/or affected by marginal decrepitation, resulting in convex and round shapes with convexities averaging ∼0.8 and circularities averaging ∼0.65.

scholarly journals Holistic description of new deep sea megafauna (Cephalopoda: Cirrata) using a minimally invasive approach

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Alexander Ziegler ◽  
Christina Sagorny
Keyword(s):  
Minimally Invasive ◽  
Dna Barcoding ◽  
Deep Sea ◽  
Imaging Techniques ◽  
Structural Complexity ◽  
Micro Computed Tomography ◽  
Invasive Approach ◽  
Non Invasive ◽  
Additional Support ◽  
Holistic Description

Abstract Background In zoology, species descriptions conventionally rely on invasive morphological techniques, frequently leading to damage of the specimens and thus only a partial understanding of their structural complexity. More recently, non-destructive imaging techniques have successfully been used to describe smaller fauna, but this approach has so far not been applied to identify or describe larger animal species. Here, we present a combination of entirely non-invasive as well as minimally invasive methods that permit taxonomic descriptions of large zoological specimens in a more comprehensive manner. Results Using the single available representative of an allegedly novel species of deep-sea cephalopod (Mollusca: Cephalopoda), digital photography, standardized external measurements, high-field magnetic resonance imaging, micro-computed tomography, and DNA barcoding were combined to gather all morphological and molecular characters relevant for a full species description. The results show that this specimen belongs to the cirrate octopod (Octopoda: Cirrata) genus Grimpoteuthis Robson, 1932. Based on the number of suckers, position of web nodules, cirrus length, presence of a radula, and various shell characters, the specimen is designated as the holotype of a new species of dumbo octopus, G. imperator sp. nov. The digital nature of the acquired data permits a seamless online deposition of raw as well as derived morphological and molecular datasets in publicly accessible repositories. Conclusions Using high-resolution, non-invasive imaging systems intended for the analysis of larger biological objects, all external as well as internal morphological character states relevant for the identification of a new megafaunal species were obtained. Potentially harmful effects on this unique deep-sea cephalopod specimen were avoided by scanning the fixed animal without admixture of a contrast agent. Additional support for the taxonomic placement of the new dumbo octopus species was obtained through DNA barcoding, further underlining the importance of combining morphological and molecular datasets for a holistic description of zoological specimens.

scholarly journals Effects of pre-extraction intermittent PTH administration on extraction socket healing in bisphosphonate administered ovariectomized rats

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jae-Young Kim ◽  
Hyo-Won Jang ◽  
Jung-In Kim ◽  
In-Ho Cha
Keyword(s):  
Tooth Extraction ◽  
Bisphosphonate Therapy ◽  
Ovariectomized Rats ◽  
Control Group ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Extraction Socket ◽  
Before And After ◽  
Socket Healing ◽  
Positive Effect

AbstractThe purpose of this study was to investigate the effect of administering intermittent parathyroid hormone (iPTH) before tooth extraction versus after tooth extraction on the risk of developing MRONJ in experimental animal model. Twenty-five ovariectomized rats received 6 weeks of bisphosphonate therapy. They were classified into 3 groups, based on the timing of the medication, as Control, Pre-PTH and Post-PTH groups. For Control group, normal saline was administered before and after tooth extraction. iPTH was administered during 4 weeks before tooth extraction for Pre-PTH group and after tooth extraction for Post-PTH group. The animals were euthanized 8 weeks after tooth extraction. Macroscopic, histological, micro-computed tomography (micro-CT), and histomorphometric examinations were conducted. The incidences of impaired healing were 11.11% both in Pre-PTH and Post-PTH groups, which was lower than the Control group (42.86%). Bone healing in the extraction socket, based on micro-CT and histomorphometry evaluations, was best in Post-PTH and worst in Control group. The Pre-PTH group showed moderate healing pattern. Despite of limitations in this study, the authors identified Pre-PTH group seems to have positive effect on extraction socket healing. With regard to timing, administering iPTH after tooth extraction was superior to applying it before tooth extraction.

Particle Size, Structure and Powdering Process of Calcium Carbonate Nanoparticles Filled Powdered Styrene-Butadiene Rubber

2011 ◽  
Vol 415-417 ◽  
pp. 237-242
Author(s):  
Zhou Da Zhang ◽  
Xue Mei Chen ◽  
Guo Liang Qu
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Size Structure ◽  
Average Diameter ◽  
Rubber Matrix ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Particle Structure ◽  
Styrene Butadiene ◽  
New Particles

Calcium carbonate nanoparticles (nano-CaCO3) filled powdered styrene-butadiene rubber (P(SBR/CaCO3) was prepared by adding nano-CaCO3 particles, encapsulant and coagulant to styrene-butadiene rubber (SBR) latex by coacervation, and the particle size distribution, structure were studied. Scanning electron microscopy (SEM) was used to investigate the (P(SBR/CaCO3) particle structure, and a powdering model was proposed to describe the powdering process. The process includes: (i) the latex particles associated with the dispersed nano-CaCO3 particles (adsorption process) to form “new particles” and (ii) the formation of P(SBR/CaCO3) by coagulating “new particles”. The SEM results also shown that the nano-CaCO3 and rubber matrix have formed a macroscopic homogenization in the (P(SBR/CaCO3) particles and nano-CaCO3 dispersed uniformly in the rubber matrix with an average diameter of approximately 50 nm.

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