Characterisation of fibrous ferrierite in the rhyolitic tuffs at Lovelock, Nevada, USA

2019 ◽  
Vol 83 (4) ◽  
pp. 577-586 ◽  
Author(s):  
Alessandro Zoboli ◽  
Dario Di Giuseppe ◽  
Cecilia Baraldi ◽  
Maria Cristina Gamberini ◽  
Daniele Malferrari ◽  
...  
Keyword(s):  
Thermal Analyses ◽  
Local Population ◽  
Crystal Habit ◽  
X Ray Diffraction ◽  
Mining Operations ◽  
Precautionary Approach ◽  
Mineral Fibre ◽  
Fibrous Morphology

AbstractFerrierite is the name for a series of zeolite-group of minerals which includes three species with the same ferrierite framework (FER) crystal structure but different extra-framework cations. Recent studies have shown that ferrierite can exhibit a fibrous-asbestiform crystal habit and may possess the same properties as carcinogenic fibrous erionite. Characterisation of the ferrierite in and around a mine location will be helpful in assessing the potential for toxic outcomes of exposure in the mine and any local population.The zeolite-rich tuff deposit of Lovelock, Nevada, USA is the largest occurrence of diagenetic ferrierite-Mg. A previous survey reported that ferrierite hosted in these rocks displays a fibrous morphology. However, these observations concerned a limited number of samples and until now there has been little evidence of widespread occurrence of fibrous ferrierite in the Lovelock deposit.The main goal of this study was to perform a mineralogical and morphometric characterisation of the tuff deposit at Lovelock and evaluate the distribution of fibrous ferrierite in the outcrop. For this purpose, a multi-analytical approach including powder X-ray diffraction, scanning and transmission microscopies, micro-Raman spectroscopy, thermal analyses, and surface-area determination was applied.The results prove fibrous ferrierite is widespread and intermixed with mordenite and orthoclase, although there are variations in the spatial distribution in the bedrock. The crystal habit of the ferrierite ranges from prismatic to asbestiform (elongated, thin and slightly flexible) and fibres are aggregated in bundles. According to the WHO counting criteria, most of the ferrierite fibres can be classified as breathable. While waiting for confirmatory in vitro and in vivo tests to assess the actual toxicity/pathogenicity potential of this mineral fibre, it is recommended to adopt a precautionary approach for mining operations in this area to reduce the risk of exposure.

Fibrous ferrierite from Lovelock, Nevada, USA

2020 ◽  
Author(s):  
Alessandro Gualtieri ◽  
Alessandro Zoboli ◽  
Dario Di Giuseppe ◽  
Cecilia Baraldi ◽  
Maria Cristina Gamberini ◽  
...  
Keyword(s):  
Thermal Analyses ◽  
Crystal Habit ◽  
International Agency ◽  
Mining Operations ◽  
Transmission Electron ◽  
Mineral Fibre ◽  
Microscopy Techniques ◽  
Different Content

<p>Ferrierite is the name of a family of zeolite minerals that includes three species with the same topological framework (FER) but with different content of extra-framework cations. In Nevada (USA), the zeolite-rich tuff deposit of Lovelock is the largest occurrence of diagenetic ferrierite-Mg, one of the member of the family. Recent studies have shown that Lovelock ferrierite can exhibit fibrous-asbestiform crystal habit and may possess the same physical-chemical and crystallographic properties of carcinogenic fibrous erionite, Nevertheless, it has not yet been classified by the International Agency for Research on Cancer (IARC). Nowadays, outcrops hosting fibrous ferrierite are being mined in Nevada for commercial purposes. Dust generated by these excavation activities may expose workforces and general public to this potential natural hazard. The main goal of this study was to perform a mineralogical and morphometric characterisation of the tuff deposit at Lovelock and evaluate the distribution of fibrous ferrierite in the outcrop. For this purpose, a multi-analytical approach including X-ray powder diffraction, scanning and transmission electron microscopy techniques, micro-Raman spectroscopy, thermal analyses, and surface-area determination was applied. The results indicate that fibrous ferrierite is widespread in the deposit and intermixed with mordenite and feldspar, although there are variations in the spatial distribution in the bedrock. The crystal habit of the ferrierite ranges from prismatic to asbestiform (elongated, thin and slightly flexible) and fibres are aggregated in bundles. According to the WHO counting criteria, most of the ferrierite fibres can be classified as breathable. While waiting for confirmatory in vitro and in vivo tests to assess the actual toxicity/pathogenicity potential of this mineral fibre, it is recommended to adopt a precautionary approach for mining operations in this area to reduce the risk of exposure.</p>

Effects of dietary alteration of bicarbonate and magnesium on rat bone

1986 ◽  
Vol 250 (2) ◽  
pp. F302-F307 ◽  
Author(s):  
J. M. Burnell ◽  
C. Liu ◽  
A. G. Miller ◽  
E. Teubner
Keyword(s):  
Crystal Structure ◽  
Bone Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Growing Rats ◽  
Final Composition ◽  
Rat Bone

To study the effects of bicarbonate and magnesium on bone, mild acidosis and/or hypermagnesemia were produced in growing rats by feeding ammonium chloride and/or magnesium sulfate. Bone composition, quantitative histomorphometry, and mineral x-ray diffraction (XRD) characteristics were measured after 6 wk of treatment. The results demonstrated that both acidosis (decreased HCO3) and hypermagnesemia inhibited periosteal bone formation, and, when combined, results were summative; and the previously observed in vitro role of HCO3- and Mg2+ as inhibitors of crystal growth were confirmed in vivo. XRD measurements demonstrated that decreased plasma HCO3 resulted in larger crystals and increased Mg resulted in smaller crystals. However, the combined XRD effects of acidosis and hypermagnesemia resembled acidosis alone. It is postulated that the final composition and crystal structure of bone are strongly influenced by HCO3- and Mg2+, and the effects are mediated by the combined influence on both osteoblastic bone formation and the growth of hydroxyapatite.

scholarly journals Purification, crystallization and preliminary crystallographic analysis of histone lysine demethylase NO66 fromHomo sapiens

2012 ◽  
Vol 68 (7) ◽  
pp. 764-766 ◽  
Author(s):  
Xing Zhou ◽  
Yue Tao ◽  
Minhao Wu ◽  
Dandan Zhang ◽  
Jianye Zang
Keyword(s):  
Crystallographic Analysis ◽  
Diffusion Method ◽  
Amino Acid Residues ◽  
X Ray Diffraction ◽  
Cell Parameters ◽  
Histone Lysine Demethylase ◽  
Jmjc Domain ◽  
Lysine Demethylase

NO66 is a JmjC domain-containing histone demethylase with specificity towards histone H3 methylated on both Lys4 and Lys36in vitroandin vivo. A fragment of NO66 lacking the N-terminal 167 amino-acid residues was overexpressed inEscherichia coli, purified and crystallized using the sitting-drop vapour-diffusion method. X-ray diffraction data were collected to a resolution of 2.29 Å. NO66 crystallized in space groupP31orP32, with unit-cell parametersa= 89.35,b = 89.35,c= 304.86 Å, α = β = 90, γ = 120°, and the crystal is likely to contain four molecules in the asymmetric unit.

scholarly journals Direct visualization of the microtubule lattice seam both in vitro and in vivo.

1994 ◽  
Vol 127 (6) ◽  
pp. 1965-1971 ◽  
Author(s):  
M Kikkawa ◽  
T Ishikawa ◽  
T Nakata ◽  
T Wakabayashi ◽  
N Hirokawa
Keyword(s):  
Electron Microscopy ◽  
Lattice Structure ◽  
X Ray Diffraction ◽  
Beta Tubulin ◽  
Structural Investigations ◽  
Cytoplasmic Microtubules ◽  
Type Lattice ◽  
Closed Lattice

Microtubules are constructed from alpha- and beta-tubulin heterodimers that are arranged into protofilaments. Most commonly there are 13 or 14 protofilaments. A series of structural investigations using both electron microscopy and x-ray diffraction have indicated that there are two potential lattices (A and B) in which the tubulin subunits can be arranged. Electron microscopy has shown that kinesin heads, which bind only to beta-tubulin, follow a helical path with a 12-nm pitch in which subunits repeat every 8-nm axially, implying a primarily B-type lattice. However, these helical symmetry parameters are not consistent with a closed lattice and imply that there must be a discontinuity or "seam" along the microtubule. We have used quick-freeze deep-etch electron microscopy to obtain the first direct evidence for the presence of this seam in microtubules formed either in vivo or in vitro. In addition to a conventional single seam, we have also rarely found microtubules in which there is more than one seam. Overall our data indicates that microtubules have a predominantly B lattice, but that A lattice bonds between tubulin subunits are found at the seam. The cytoplasmic microtubules in mouse nerve cells also have predominantly B lattice structure and A lattice bonds at the seam. These observations have important implications for the interaction of microtubules with MAPs and with motor proteins, and for example, suggest that kinesin motors may follow a single protofilament track.

Preparation of N, O-Carboxymethyl Chitosan with Different Substitutional Degree and its Application for Hemostasis

2013 ◽  
Vol 798-799 ◽  
pp. 1061-1066 ◽  
Author(s):  
Yan Wei Zhao ◽  
Lu Liu ◽  
Xiang Han ◽  
Jing Guan
Keyword(s):  
Carboxymethyl Chitosan ◽  
X Ray Diffraction ◽  
Clotting Time ◽  
X Ray ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Ft Ir ◽  
Ubbelohde Viscometer

We prepared N, O-carboxymethyl chitosans (CMCSs) with different substitutional degrees (SDs) to evaluate their effects of hemostasis, and provided experimental basis on biomedical materials. Chloroethanoic acid was used to synthesize CMCSs. The structure were characterized by Fourier transform infrared (FT-IR) and wide-angle X-ray diffraction (WXRD). Potentiometric titration and Ubbelohde viscometer were adopted to determine the SD and intrinsic viscosity of CMCSs. Contact angle measurements were investigated to determine surface wettability. Method of dynamic clotting time and coagulation test in vivo were used to evaluate their effects of hemostasis. SDs of CMCSs were from 50% to 110%. As the SD increased, molecular weight decreased. CMCS powder with SD 63% possessed excellent hemostasis both in vitro and in vivo. CMCS powder owned hemostatic capability prior to CS. CMCS powder with SD 63% (neither too high, nor too low) possessed excellent hemostasis both in vitro and in vivo.

scholarly journals Hydrophilic Sugars for Enhancing Dissolution Rate of Cilostazol: Effect of Wet Co-Processing

2020 ◽  
Vol 27 (1) ◽  
pp. 111-120
Author(s):  
Alaa Yosf Bazeed ◽  
Ahmed Nouh ◽  
Ebtessam Ahmed Essa ◽  
Gamal El Maghraby
Keyword(s):  
Aqueous Solubility ◽  
Submicron Particles ◽  
Drug Dissolution ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Swallowing Difficulties ◽  
Fast Disintegrating Tablets

Background: Cilostazol is an anti-platelets drug with considerable antithrombotic effects in vivo. Therefore, it is widely used by elderly patients. However, it suffers from poor bioavailability due to its low aqueous solubility. The objective of this work was to enhance the dissolution of cilostazol with the aim of formulating fast dissolving tablets for geriatrics and those of swallowing difficulties. Methods: Ethanol-assisted co-grinding of cilostazol with sugar-based excipients was adopted. Sucralose and mannitol were used for this purpose as hydrophilic excipient as well as taste improving agents. The obtained products were investigated regarding differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and in vitro drug dissolution. Fast disintegrating tablets were prepared and evaluated. Results: Thermal behavior of the developed products reflected reduced crystallinity, it also suggested possible existence of new crystalline species with sucralose. Eutexia was also suggested for mannitol mixtures, that was supported by X-ray diffraction data. SEM indicated size reduction with the deposition of the drug as submicron particles over the excipient surface. Co-processing markedly improved cilostazol dissolution compared to unprocessed drug. The optimized formulations were successively formulated into fast disintegrating tablets. Conclusion: This investigation introduced the wet grinding strategy with sugar excipients as a platform for the formulation of easy to use tablets with optimum drug release.

scholarly journals Chemical, Microstructural and Morphological Characterisation of Dentine Caries Simulation by pH-Cycling

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 5
Author(s):  
Juan Sebastián Zuluaga-Morales ◽  
María Victoria Bolaños-Carmona ◽  
Carolina Cecilia Cifuentes-Jiménez ◽  
Pedro Álvarez-Lloret
Keyword(s):  
Microstructural Properties ◽  
Third Molars ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Vitro Simulation ◽  
Ph Cycling ◽  
Residual Caries ◽  
Microscopy Techniques

In vitro simulation of natural caries is of great importance in dental research for the development of more effective clinical treatments. The pH-cycling (pHc) procedure consists of a dynamic caries process with alternating de-remineralisation periods. The current research aims to evaluate the effects of the pHc procedure on mineral dentine properties in comparison with sound dentine and natural residual caries. For this purpose, dentine slices from human third molars were submitted to cycling periods of 14 and 28 days. The chemical composition, morphological and microstructural properties of the dentine samples were examined by infrared and Raman spectroscopies, X-ray diffraction, and scanning electron microscopy techniques. In addition, the depth of the demineralisation front was evaluated by Masson’s trichrome (MT) staining. The results showed that the pHc procedure led to notable changes in the mineral composition and the crystalline characteristics with respect to sound dentine and some extent to natural caries. The MT results revealed that pHc 28 yields a deeper lesion than pHc 14, simulating potential progression of natural caries. The results of this study provide a better understanding of the mechanisms of demineralisation that could occur in an in vivo environment and provide a standardised substrate similar to natural residual caries.

Comparisons of the Biological Effects of Mineral Fibre Samples Using in Vitro and in Vivo Assay Systems

1985 ◽  
pp. 405-411 ◽  
Author(s):  
J. M. G. Davis ◽  
R. E. Bolton ◽  
H. Cowie ◽  
K. Donaldson ◽  
I. P. Gormley ◽  
...  
Keyword(s):  
Biological Effects ◽  
In Vivo Assay ◽  
Mineral Fibre

Amelogenin Nanospheres Modulate Crystal Habit of Octacalcium Phosphate and Hydroxyapatite Crystals in In Vitro Model Systems

2000 ◽  
Vol 620 ◽  
Author(s):  
Moradian-Oldak J. ◽  
Wen H.B. ◽  
Fincham A.G. ◽  
Iijima M.
Keyword(s):  
Membrane System ◽  
Octacalcium Phosphate ◽  
Model Systems ◽  
Crystal Habit ◽  
Width Ratio ◽  
Growth Morphology ◽  
Oriented Growth ◽  
Apatite Crystals

ABSTRACTThis paper is a short review of recent studies, which were undertaken to investigate interactions of amelogenin with octacalcium phosphate (OCP), and apatite. OCP crystals were grown using two independent experimental systems; (a) in a 10% gelatin gel, containing 0-2% amelogenin, where the crystals were formed in a double-diffusion chamber, and (b) in a 10% pure amelogenin gel, where crystal growth took place in between a cation-selective and a dialysis membrane. Apatite crystals were grown from a supersaturated calcifying solution on a bioactive glass in the absence (SCSB) and the presence of amelogenin (SCSrM179). It was found that OCP crystals formed in 10% gelatin gel containing 1-2% amelogenin were longer (3-5 times larger in aspect ratio) than the OCP crystals formed in 10% gelatin without amelogenin. A profound effect was that found in the cation selective membrane system when 10% amelogenin inhibited the growth morphology in a specific manner. Affected crystals had a length to width ratio twice larger than that of control crystals while the width to thickness ratio was about 1/12 of that of the control crystals. Amelogenin promoted the formation of bundles of lengthwise apatite crystals, which were all oriented parallel to their c axes when grown on SCSrM179. It was found that individual apatite crystals within those bundles adopted an elongated, curved shape. The data presented here suggest that amelogenin nanospheres modulate the growth morphology of apatite and OCP crystals and indicate significant functional roles for amelogenin proteins during the in vivo oriented growth of enamel crystallites.

Assessment of the potential health hazard of fibrous glaucophane

2020 ◽  
Author(s):  
Dario Di Giuseppe ◽  
Alessandro Gualtieri ◽  
Alessandro Zoboli ◽  
Monica Filaferro ◽  
Giovanni Vitale ◽  
...  
Keyword(s):  
Health Hazard ◽  
Toxicity Tests ◽  
International Agency ◽  
Potential Toxicity ◽  
Potential Health ◽  
Franciscan Complex ◽  
Mineral Fibre ◽  
Potential Health Hazard

<p>The widespread concern on the environmental hazards and public health issues related to exposure to respirable dusts from naturally occurring asbestos (NOA) in principle should also apply to deposits of mineral fibres other than the currently regulated six asbestos minerals. Recent studies highlight that glaucophane can assume a fibrous habit resembling the regulated amphibole asbestos minerals. Glaucophane, sometimes occurring in a fibrous habit, is a major mineral component of blueschist rocks of the Franciscan Complex, USA. Recently, fibrous blueschist occurrences within the Franciscan Complex were being excavated in California for construction purposes (<em>e.g.</em>, the Calaveras Dam Replacement Project) and concern existed that the dust generated by the excavation activities might potentially expose workers and the general public to health risks. For this reason, fibrous glaucophane (Gla) was considered to represent a potential health hazard as NOA by the dam owner, the San Francisco Public Utilities Commission, though an evaluation of the potential health hazard of this mineral fibre was not mandatory per local state and federal regulations. To fill this gap, the potential toxicity/pathogenicity of Gla from the Franciscan Complex has been assessed using the fibre potential toxicity model (FPTI) model and specific <em>in vitro</em> toxicity tests. FPTI is an analytical tool to predict the toxicity/pathogenicity of minerals fibers, based on physical/chemical and morphological parameters that induce biochemical mechanisms responsible for <em>in vivo</em> adverse effects. This model delivers an FPTI index aimed at ranking the toxicity and pathogenicity of a mineral fibre. Compared to asbestos minerals, the FPTI of Gla is considerably higher than that of chrysotile, comparable to that of tremolite and lower than that of crocidolite. Biological responses of cultured human lung cells (THP-1 and Met-5A) following 24 and 48h of exposure to different doses of Gla (25, 50 and 100 µg/mL), have been determined by Alamar Blue viability, Extra-cellular lactate dehydrogenase (LDH) and Comet assays. Generation of reactive oxygen species (ROS) has been evaluated performing the luminescent ROS-Glo™ assay. Crocidolite UICC asbestos (100 µg/mL) was also tested for comparison. Results of in vitro tests showed that Gla may induce a decrease in cell viability and an increase in LDH release in tested cell cultures in a concentration dependent mode. Overall, the rank of the investigated fibres in increasing order of cytotoxicity is: Gla (25 μg/mL) < Gla (50 μg/mL) < crocidolite (50 μg/mL) < Gla (100 μg/mL). For both the cells lines, Gla was able to induce DNA damage. Moreover, it was found that Gla can induce the formation of ROS. The chemical-structural features and biological reactivity of Gla confirm that this mineral fibre is a toxic agent. Although Gla induced lower toxic effects compared to the carcinogenic crocidolite, the inhalation of its fibres may be hypothetically responsible for the development of lung diseases. For a conclusive understanding of the mechanisms of the cellular/tissues responses to fibrous glaucophane, <em>in vivo</em> animal tests should be performed and compared to our outcome to stimulate a critical evaluation and a classification by the International Agency for Research on Cancer (IARC).</p>

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