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2.
J Med Life ; 14(1): 81-85, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33767790

RESUMEN

This study aims to determine whether the design of resin posts reinforced with glass fiber (FRC) and Reporfost (Angelus, Londrina, PR, Brazil) significantly improves the fracture resistance of endodontically treated teeth restored through this method.A batch of 30 maxillary monoradicular teeth (15 central incisors, 15 canines) were treated endodontically by step-back technique (apical enlargement 40-K file) sealed with Sealapex (Kerr Corporation, Orange, US) and gutta-percha by lateral condensation, cold. They were divided into two equal groups, prepared for cementing the FRC posts. The Exacto posts (Angelus, Londrina, PR, Brazil) in group 1 and the Reforpost posts (Angelus; Londrina; PR, Brazil) were cemented with dual cure resin cement Breeze Self-Adhesive Resin Cement (Pentron Clinical, Orange, US). Fracture resistance testing was performed on the crown-apical axial direction, using the Hounsfield / Tinius Olsen H1-KS, PA, USA mechanical testing apparatus. The behavior of each tooth-post assembly was recorded as a graph. The statistical analysis was done using one way ANOVA (α=0.05). The differences between the Exacto post group and the Reforpost post group are not statistically significant (p = 0.466). The maximum force recorded was 970 N and the minimum 186N. The mean force at which the fracture occurred was approximately 500N for both groups. The strain test showed that modifying the Reforpost post design did not improve the fracture resistance parameters of the tooth-post assembly through increasing the surface friction or maintaining adhesion to the walls of the root dentin.


Asunto(s)
Resinas Compuestas/uso terapéutico , Vidrio/química , Técnica de Perno Muñón , Fracturas de los Dientes/terapia , Diente no Vital/terapia , Humanos , Ensayo de Materiales , Estrés Mecánico
3.
Waste Manag ; 124: 8-16, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33592321

RESUMEN

An efficient, microwave-assisted chemical recovery approach for epoxy resin and glass fiber from non-metallic components (NMC) in waste printed circuit boards (WPCBs) for resource reutilization was developed in this research. HNO3 was selected as the chemical reagent because epoxy resin has low corrosion resistance to HNO3. The influence of reaction parameters such as reaction time, temperature, concentration of HNO3, liquid-solid ratio, and power of the microwave synthesizer on the separation efficiency of NMC (epoxy resin and glass fiber) and the reaction mechanism were investigated. The physical and chemical properties of NMC, reaction solvent, and decomposed products were analyzed using energy dispersive X-ray Spectroscopy (SEM-EDX) and Fourier transform infrared spectroscopy (FT-IR). The results showed that up to 88.42% of epoxy resin and glass fiber ((5 g) 10 mL/g) could be separated under the action of 300 W microwave power at 95 ℃ for 12 h and a HNO3 concentration of 7 mol/L. During the reaction, C-N bonds formed by the crosslinking agent and the three-dimensional network structure of the thermosetting epoxy resin were destroyed. The carbon chain structure and chemical properties of epoxy resin did not change significantly and the functional groups of ethyl acetate maintained the chemical structure before and after the reaction. This uncomplicated and efficient inorganic acid chemical microwave-assisted process holds promise for use as a feasible recovery technology for epoxy resin and glass fibers in NMC. The proposed process is particularly appealing because of its high selectivity, considerable economic advantages, and environmental benefits.


Asunto(s)
Residuos Electrónicos , Resinas Epoxi , Vidrio , Microondas , Reciclaje , Espectroscopía Infrarroja por Transformada de Fourier
4.
J Environ Manage ; 285: 112094, 2021 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-33588168

RESUMEN

Nowadays, the disposal of industrial wastes is an ablaze issue worldwide, especially those containing hazardous materials. Lead silicate glass waste (LSG) produced during lead crystal glass manufacturing, which contains about 30% of toxic lead compounds, belongs to this category. This work aims to adopt an innovative clean method to convert this waste into novel advanced ceramic materials via an environmental friendly method. Chromia Cr2O3 and hematite Fe2O3 ceramics with different content (0, 5, 10, 15%) are added separately to the solid wastes of LSG recovered from national crystal glass industry to obtain various ceramics/LSG composites by pressureless sintering methods. Different properties of the produced composites are evaluated in terms of phase's identification and microstructural features. Optical properties in terms of absorbance, reflectance, band gap (Eg), refractive index (n) and photoluminescence (PL) are investigated. Magnetic and electrical properties are inclusively studied. Results indicated that, an addition of chromia and hematite as well as increasing their content to 15% has enhanced the microstructural features, optical, electrical and magnetic properties of the obtained composites. Cr2O3/LSG composites are considered as promising optical and electrical materials. However, Fe2O3/LSG composites showed the highest optical and magnetic properties. They are strongly recommended in optoelectronic and magneto-optical applications.


Asunto(s)
Plomo , Reciclaje , Cerámica , Vidrio , Fenómenos Magnéticos , Ensayo de Materiales , Silicatos
5.
Waste Manag ; 122: 89-99, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33494003

RESUMEN

The increase in the annual flux of the end-of-life photovoltaic panels (EoL-PVPs) imposed the development of effective recycling strategies to reach EU regulation targets (i.e. 80% recycling; 85% recovery, starting from August 2018). The recycling targets in a PVP are generally glass, photovoltaic cell and metals, while no scientific paper or patent addressed polymeric fractions recycling and recovery, i.e. encapsulant polymer (EVA) and backsheet (Tedlar), starting from preliminarily milled EoL-PVPs. In the present study an optimization following the solvent treatment operation of the basic Photolife process (demonstrated at pilot scale), was proposed (lab scale) and validated (micropilot scale), focusing on polymers separation and metals recovery. The optimization was performed by testing 4 different processes. Specifically, the selectivity of the filtration operation (subsequent the solvent treatment) on polymers separation grade was evaluated, demonstrating that Tedlar can be effectively separated from EVA residues. Moreover, in comparison to the basic Photolife, a further operation was introduced treating thermally the EVA residues (containing the PV cell). The metal extraction yields highlighted the effectiveness of that strategy in comparison with direct extraction from the uncombusted EVA residues. Processing 100 Kg of crushed material, 0.03 Kg of Ag, 45.5 Kg of high value glass, 10 Kg of Al scraps and 1.2 Kg of metallic filaments can be recovered. Thanks to the optimization the recycling rate of the implemented process grew up to 82% (75% during demonstration of the basic Photolife process), while the recovery was estimated at 94%. Remarkably, these rates get over with EU Directive.


Asunto(s)
Reciclaje , Silicio , Vidrio , Metales , Polímeros
6.
Environ Sci Pollut Res Int ; 28(9): 10488-10502, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33426587

RESUMEN

The environmental impact of waste glass (WG) is one of the major challenges crippling sustainable waste management and mitigation. Reclamation of recycled materials from waste glass remains a tedious task amidst complex technological approaches. The challenge as seen in the global containment measures increase the proportion of waste glass and minimize the existing capacity of landfill space. In many works, findings have shown how best to minimize the impact of waste glass as evidenced in their inclusion as building materials such as cement, mortars, concretes and blocks. The concept of this paper is to appraise previous studies carried out on the use of waste glass as key contributing factor in structural building. The scope of this paper will be broaden to include various successes recorded in the evolution of concrete mixtures containing different proportion of recycle glass. Part of the setbacks noted in the inclusion of these recycled materials as matrix, filler or fibre are also reported in this paper. Also discussed is the durability of glass materials in varying conglomerate involving cement in reinforcement of building and structures. Thermal insulating properties of recycled glass are also considered in this work where considerable energy is saved due to their low thermal conductivity. Based on the analysis of various studies and other factors considered in this paper, it is established that recycled glass materials can be accommodated in structural buildings, while continuous research is necessary to adapt waste glass to high pH value of Portland cement.


Asunto(s)
Reciclaje , Administración de Residuos , Materiales de Construcción , Ambiente , Vidrio
7.
Arch Oral Biol ; 122: 105032, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33418435

RESUMEN

OBJECTIVES: This study aims to investigate the effects of tea extracts on biofilm formation by oral streptococci and the potential mechanisms behind the effects. DESIGN: We examined the effects of five types of tea extracts (green, oolong, black, pu-erh and chrysanthemum tea) on cell surface hydrophobicity and auto-aggregation of three different streptococcal species (Streptococcus mutans, Streptococcus salivarius and Streptococcus mitis) and evaluated their biofilm formation on four disparate hard surfaces (glass, stainless steel, hydroxyapatite and titanium). The correlation between biofilm formation and the cellular properties were investigated in order to study the mechanisms by which the tea extracts affect biofilm formation. RESULTS: Results show that the tea extracts reduced cell surface hydrophobicity (by up to 57.9 %) and, in some cases, altered cellular auto-aggregation (by up to 12 %) and biofilm formation (by up to 2.61 log CFU cm-2). Specifically, oolong tea extract was found to enhance biofilm formation by increasing cellular auto-aggregation and pu-erh tea extract retarded biofilm formation by increasing auto-aggregation. Biofilm formation correlated well to cell surface hydrophobicity and auto-aggregation in combination, but not to either one alone as determined by multiple linear regression analysis. CONCLUSIONS: Tea extracts have the ability to modulate streptococcal biofilm formation by altering cell surface hydrophobicity and cellular aggregation.


Asunto(s)
Biopelículas/efectos de los fármacos , Extractos Vegetales/farmacología , Streptococcus mutans/efectos de los fármacos , Té/química , Durapatita , Vidrio , Interacciones Hidrofóbicas e Hidrofílicas , Acero Inoxidable , Titanio
8.
J Prosthet Dent ; 125(4): 674.e1-674.e7, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33431176

RESUMEN

STATEMENT OF PROBLEM: Light transmitted deep into the root canal is an important parameter to increase bonding of the cement to the post and dentin. Glass fiber posts seem to be an option to increase transmitted light, but literature on the light transmittance profile and power transmission to deep canal regions is lacking. PURPOSE: The purpose of this in vitro study was to evaluate light delivered by 2 types of fiberglass posts submitted to different surface treatments and to evaluate the bond strength. MATERIAL AND METHODS: Whiteposts and Superposts were allocated to 4 groups: no surface treatment, surface treatment with 24% hydrogen peroxide, surface treatment with silane, and surface treatment with 24% hydrogen peroxide plus silane. The total light transmitted by the posts was measured by using an integrating sphere to collect the diffuse light. The light profile that was laterally delivered to the post was measured with a power detector equipped with an optical fiber probe. The bond strength was measured with the push-out test. Scanning electron microscopy was used to evaluate the surface treatments. The light transmission data were analyzed by using a generalized linear model and the Bonferroni test and the bond strength values were evaluated by using ANOVA and the Tukey test (α=.05). RESULTS: The cervical third presented the highest transmission (74.1% for Whiteposts and 74.6% for Superposts), followed by the middle (20.9% for Whiteposts and 20.4% for Superposts) and apical (5.0% for both Whiteposts and Superposts) thirds. Superposts led to higher bond strength than Whiteposts (9.73 ±5.89 and 8.48 ±4.99 MPa, respectively). Surface treatment with silane and hydrogen peroxide plus silane afforded similar bond strength (11.4 ±6.4 and 10.7 ±5.6 MPa, respectively), which was higher as compared with the bond strength obtained after surface treatment with hydrogen peroxide. For both post types, the bond strength decreased from the cervical (12.2 ±6.0 MPa) to the middle (9.7 ±5.0 MPa) and apical (6.5 ±3.6 MPa) thirds. CONCLUSIONS: Light transmission and bond strength decreased from the cervical to the apical third. Surface treatment impacted bond strength; light transmission through Whiteposts was slightly higher than light transmission through Superposts.


Asunto(s)
Recubrimiento Dental Adhesivo , Técnica de Perno Muñón , Dentina , Vidrio , Ensayo de Materiales , Cementos de Resina
9.
Int J Mol Sci ; 22(3)2021 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-33498202

RESUMEN

In this work, we performed a systematic analysis of the impact of selected chemical reagents used in sol-gel synthesis (i.e., N,N-dimethylformamide) and different catalyst agents (i.e., CH3COOH, HNO3) on the formation and luminescence of Eu3+-doped SiO2-LaF3 nano-glass-ceramics. Due to the characteristic nature of intra-configurational electronic transitions of Eu3+ ions within the 4f6 manifold (5D0 → 7FJ, J = 0-4), they are frequently used as a spectral probe. Thus, the changes in the photoluminescence profile of Eu3+ ions could identify the general tendency of rare earth materials to segregate inside low-phonon energy fluoride nanocrystals, which allows us to assess their application potential in optoelectronics. Fabricated sol-gel materials, from sols to gels and xerogels to nano-glass-ceramics, were examined using several experimental techniques: X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), and luminescence measurements. It was found that the distribution of Eu3+ ions between the amorphous silicate sol-gel host and LaF3 nanocrystals is strictly dependent on the initial composition of the obtained sols, and the lack of N,N-dimethylformamide significantly promotes the segregation of Eu3+ ions inside LaF3 nanocrystals. As a result, we detected long-lived luminescence from the 5D0 excited state equal to 6.21 ms, which predisposes the obtained glass-ceramic material for use as an optical element in reddish-orange emitting devices.


Asunto(s)
Cerámica/química , Europio/química , Fluoruros/química , Vidrio/química , Lantano/química , Nanopartículas/química , Catálisis , Geles/química , Dióxido de Silicio/química
10.
AAPS PharmSciTech ; 22(2): 57, 2021 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-33502633

RESUMEN

Recent advances in molded vial manufacturing enabled manufacturers to use a new manufacturing technique to achieve superior homogeneity of the vial wall thickness. This study evaluated the influence of the different manufacturing techniques of molded vials and glass compositions on vial heat transfer in freeze-drying. Additionally, the influence of using empty vials as thermal shielding on thermal characteristics of edge and center vials was investigated. The vial heat transfer coefficient Kv was determined gravimetrically for multiple vial systems. The results showed superior heat transfer characteristics of the novel manufacturing technique as well as differences in heat transfer for the different glass compositions. Empty vials on the outside of the array did not influence center vial Kv values compared to a full array. The direct contact area and vial bottom curvature and their correlation to heat transfer parameters were analyzed across multiple vial systems. A new approach based on light microscopy to describe the vial bottom curvature more accurately was described. The presented results for the contact area allowed for an approximation of the pressure-independent heat transfer parameter KC. The results for the vial bottom curvature showed a great correlation to the pressure-dependent heat transfer parameter KD. Overall, the results highlighted how a thorough geometrical characterization of vials with known heat transfer characteristics could be used to predict thermal characteristics of new vial systems as an alternative to a time-consuming gravimetric Kv determination. Primary drying times were simulated to show the influence of Kv on drying performance.


Asunto(s)
Embalaje de Medicamentos/métodos , Liofilización/métodos , Tecnología Farmacéutica/métodos , Vidrio/química , Calor
11.
ACS Appl Mater Interfaces ; 13(4): 4835-4843, 2021 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-33474941

RESUMEN

A wide range of biomedical devices are being used to treat cardiovascular diseases, and thus they routinely come into contact with blood. Insufficient hemocompatibility has been found to impair the functionality and safety of these devices through the activation of blood coagulation and the immune system. Numerous attempts have been made to develop surface modification approaches of the cardiovascular devices to improve their hemocompatibility. However, there are still no ideal "blood-friendly" coating materials, which possess the desired hemocompatibility, tissue compatibility, and mechanical properties. As a novel multifunctional material, graphene has been proposed for a wide range of biomedical applications. The chemical inertness, atomic smoothness, and high durability make graphene an ideal candidate as a surface coating material for implantable devices. Here, we evaluated the hemocompatibility of a graphene film prepared on quartz glasses (Gra-glasses) from a direct chemical vapor deposition process. We found that the graphene coating, which is free of transfer-mediating polymer contamination, significantly suppressed platelet adhesion and activation, prolonged coagulation time, and reduced ex vivo thrombosis formation. We attribute the excellent antithrombogenic properties of the Gra-glasses to the low surface roughness, low surface energy (especially the low polar component of the surface energy), and the negative surface charge of the graphene film. Given these excellent hemocompatible properties, along with its chemical inertness, high durability, and molecular impermeability, a graphene film holds great promise as an antithrombogenic coating for next-generation cardiovascular devices.


Asunto(s)
Coagulación Sanguínea , Materiales Biocompatibles Revestidos/química , Grafito/química , Adhesividad Plaquetaria , Animales , Coagulación Sanguínea/efectos de los fármacos , Materiales Biocompatibles Revestidos/efectos adversos , Activación de Complemento , Vidrio/química , Grafito/efectos adversos , Hemólisis/efectos de los fármacos , Masculino , Ensayo de Materiales , Adhesividad Plaquetaria/efectos de los fármacos , Conejos , Propiedades de Superficie , Volatilización
12.
Environ Sci Pollut Res Int ; 28(13): 16843-16854, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33394426

RESUMEN

In this study, the possibilities of disposal of environmental waste, silica fume, and waste glass powder as substitutes in the mortar samples in Portland cement were investigated. For this purpose, Portland cement (CEM I), silica fume (SF), waste glass powder (WGP), CEN standard sand, and water were used in mortar production. Additive cements were obtained by using the SF, WGP, and SFWGP substitution methods in Portland cement at the rates of 10, 20, 30, and 40%. The flexural strength, compressive strength, radiation permeability (determination of linear absorption coefficient), high temperature, and alkali-silica reaction (ASR) effect on SF, WGP, and SFWGP were examined and compared with the control PC 42.5R samples. Mortar samples of 40 × 40 × 160 mm size were obtained with the grouts/mortars produced, and the samples were exposed to five temperature effects, namely, 20, 150, 300, 700, and 1000 ° C. Samples kept at 20 ° C are accepted as baseline. A total of 429 samples were studied, including the cooling process in the air (spontaneously in the laboratory, 20 ° C ± 2). After the samples achieved room temperature, flexural and compressive strength tests were carried out at 28 and 90 days. Test results demonstrate that SF, WGP, and SFWGP, which are environmental wastes, can be disposed both as a pozzolanic additive material both alone and together in cement mortars, can be utilized in buildings with high fire hazard, and the sample with the highest linear absorption coefficient is the sample obtained with SFWGP, and also, the expansion values ​​that occur in SF and WGP are less than the control sample.


Asunto(s)
Materiales de Construcción , Dióxido de Silicio , Fuerza Compresiva , Vidrio , Polvos
13.
Arch Oral Biol ; 123: 105041, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33454420

RESUMEN

OBJECTIVE: The aim of this study was to develop a composite scaffold with the optimal poly(lactic-co-glycolic acid) (PLGA) and bioactive glass proportions to provide an environment for bone tissue regeneration and repair. DESIGN: PLGA-bioactive glass composite scaffolds were prepared using a salt-leaching technique with different percentages of bioactive glass (0%, 10 %, and 15 % [w/w]) with PLGA. The resulting scaffolds were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), and water contact angle, dynamic mechanical, and pH analysis. The scaffold biocompatibility was investigated using stem cells from human exfoliated deciduous teeth (SHED) and rat experiments. RESULTS: SEM-EDS confirmed the successful fabrication of three-dimensional PLGA-bioactive glass scaffolds. The results showed that 10 % bioactive glass with PLGA exhibited favorable properties including increased pore size, hydrophilicity, and mechanical properties. The growth medium pH was increased for scaffolds containing bioactive glass. All scaffolds were biocompatible, and 10 % bioactive glass composite scaffolding showed better attachment, growth, and proliferation of SHED compared to the other scaffolds. Moreover, it enhanced osteogenic differentiation of SHED in vitro and in vivo. CONCLUSIONS: Salt-leaching-derived PLGA-bioactive glass composite scaffolds were successfully established. PLGA with 10 % bioactive glass had adequate physical properties and bioactivity, and it could be considered as a composite for bone tissue engineering applications.


Asunto(s)
Vidrio/química , Osteogénesis , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/química , Células Madre/citología , Ingeniería de Tejidos , Andamios del Tejido , Animales , Humanos , Porosidad , Ratas , Diente Primario/citología
14.
Methods Mol Biol ; 2237: 191-198, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33237418

RESUMEN

Glass serves as the solid support for a variety of array types; however, the chemical nature of glass makes it unsuitable for high-affinity binding to most biomolecules. In this chapter, we describe the activation and surface coating of glass with silane, a wide-ranging group of molecules that can covalently attach to the surface of glass and modify it with a variety of functional groups.


Asunto(s)
Vidrio/química , Análisis por Micromatrices/métodos , Silanos/química , Peróxido de Hidrógeno/química , Ácidos Sulfúricos/química
15.
Methods Mol Biol ; 2180: 203-220, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-32797413

RESUMEN

Dry preservation has become an attractive approach for the long-term storage of biologics. By removing water from the matrix to solidify the sample, refrigeration needs are reduced, and thus storage costs are minimized and shipping logistics greatly simplified. This chapter describes two energy deposition technologies, namely, microwave and laser systems, that have recently been used to enhance the rate and nature of solution densification for the purpose of anhydrous preservation of feline oocytes, sperm, and egg white lysozyme in trehalose glass. Several physical screening methodologies used to determine the suitability of an amorphous matrix for biopreservation are also introduced in this chapter.


Asunto(s)
Productos Biológicos/química , Criopreservación/veterinaria , Crioprotectores/metabolismo , Liofilización/métodos , Rayos Láser , Microondas , Preservación Biológica/métodos , Animales , Gatos , Pollos , Criopreservación/métodos , Desecación , Femenino , Vidrio/química , Masculino , Muramidasa/química , Oocitos/citología , Espermatozoides/citología
16.
Dent Mater J ; 40(2): 464-471, 2021 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-33361660

RESUMEN

The human antimicrobial peptide beta-defensin-2 (hBD2) shows broad antibacterial activity and infrequent bacterial resistance. Here mesoporous bioactive glass (MBG) was loaded with hBD2, forming hBD2-loaded MBG (BD-MBG). The antibacterial and osteogenic effects of BD-MBG were investigated in comparison with MBG and the blank control (BC). The result showed that BD-MBG yielded sustained hBD2 release for more than 7 weeks in vitro, and resulted in significantly lower amounts of viable bacteria and colony forming units, and significantly higher levels of bacterial protein release compared with those in the BC and MBG groups (all p<0.05). Compared with that in the BC group, significantly higher bone marrow stromal cell (BMSC) proliferation rates, alkaline phosphatase (ALP) activity, calcium nodule formation, and expression levels of early and late osteogenic makers were observed after MBG and BD-MBG treatments (p<0.05). Thus, BD-MBG inhibited bacterial growth, damaged their membrane, and promoted early and late osteogenic BMSC differentiation.


Asunto(s)
Andamios del Tejido , beta-Defensinas , Antibacterianos/farmacología , Cerámica , Vidrio , Humanos , Osteogénesis , Porosidad , beta-Defensinas/farmacología
17.
ACS Appl Mater Interfaces ; 12(52): 58360-58368, 2020 Dec 30.
Artículo en Inglés | MEDLINE | ID: mdl-33337873

RESUMEN

The SARS-CoV-2 virus that causes the COVID-19 epidemic can be transmitted via respiratory droplet-contaminated surfaces or fomites, which urgently requires a fundamental understanding of intermolecular interactions of the coronavirus with various surfaces. The corona-like component of the outer surface of the SARS-CoV-2 virion, named spike protein, is a key target for the adsorption and persistence of SARS-CoV-2 on various surfaces. However, a lack of knowledge in intermolecular interactions between spike protein and different substrate surfaces has resulted in ineffective preventive measures and inaccurate information. Herein, we quantified the surface interaction and adhesion energy of SARS-CoV-2 spike protein with a series of inanimate surfaces via atomic force microscopy under a simulated respiratory droplet environment. Among four target surfaces, polystyrene was found to exhibit the strongest adhesion, followed by stainless steel (SS), gold, and glass. The environmental factors (e.g., pH and temperature) played a role in mediating the spike protein binding. According to systematic quantification on a series of inanimate surfaces, the adhesion energy of spike protein was found to be (i) 0-1 mJ/m2 for hydrophilic inorganics (e.g., silica and glass) due to the lack of hydrogen bonding, (ii) 2-9 mJ/m2 for metals (e.g., alumina, SS, and copper) due to the variation of their binding capacity, and (iii) 6-11 mJ/m2 for hydrophobic polymers (e.g., medical masks, safety glass, and nitrile gloves) due to stronger hydrophobic interactions. The quantitative analysis of the nanomechanics of spike proteins will enable a protein-surface model database for SARS-CoV-2 to help generate effective preventive strategies to tackle the epidemic.


Asunto(s)
Vidrio/química , Oro/química , Poliestirenos/química , Glicoproteína de la Espiga del Coronavirus/química , Acero Inoxidable/química , Adsorción , Fómites/virología , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Microscopía de Fuerza Atómica , Propiedades de Superficie , Temperatura
18.
PLoS One ; 15(12): e0244621, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33378374

RESUMEN

Alkali-activated materials (AAMs), sometimes called geopolymers, are eco-friendly cementitious materials with reduced carbon emissions when compared to ordinary Portland cement. However, the availability of most precursors used for AAM production may decline in the future because of changes in industrial sectors. Thus, new precursors must be developed. Recently there has been increased interest in synthetic glass precursors. One major concern with using synthetic glasses is ensuring that they react sufficiently under alkaline conditions. Reactivity is a necessary, although not sufficient, requirement for a suitable precursor for AAMs. This work involves the synthesis, characterization, and estimation of alkaline reactivity of Na-Mg aluminosilicate glasses. Structural characterization showed that replacing Na with Mg led to more depolymerization. Alkaline reactivity studies indicated that, as Mg replaced Na, reactivity of glasses increased at first, reached an optimal value, and then declined. This trend in reactivity could not be explained by the conventional parameters used for estimating glass reactivity: the non-bridging oxygen fraction (which predicts similar reactivity for all glasses) and optical basicity (which predicts a decrease in reactivity with an increase in Mg replacement). The reactivity of the studied glasses was found to depend on two main factors: depolymerization (as indicated by structural characterization) and optical basicity. Depolymerization dominated initially, which led to an increase in reactivity, while the effect of optical basicity dominated later, leading to a decrease in reactivity. Hence, while designing reactive synthetic glasses for alkali activation, structural study of glasses should be given due consideration in addition to the conventional factors.


Asunto(s)
Silicatos de Aluminio/química , Vidrio/química , Magnesio/química , Sodio/química , Álcalis/química , Materiales Biocompatibles/química , Modelos Moleculares , Conformación Molecular , Difracción de Rayos X
19.
Molecules ; 26(1)2020 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-33379358

RESUMEN

A star polymer with a polyhedral oligomeric silsesquioxanne (POSS) core and poly(ethylene glycol) (PEG) vertex groups is incorporated in a polyurethane with flexible hard segments in-situ during the polymerization process. The blends are studied in terms of morphology, molecular dynamics, and charge mobility. The methods utilized for this purpose are scanning electron and atomic force microscopies (SEM, AFM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and to a larger extent dielectric relaxation spectroscopy (DRS). It is found that POSS reduces the degree of crystallinity of the hard segments. Contrary to what was observed in a similar system with POSS pendent along the main chain, soft phase calorimetric glass transition temperature drops as a result of plasticization, and homogenization of the soft phase by the star molecules. The dynamic glass transition though, remains practically unaffected, and a hypothesis is formed to resolve the discrepancy, based on the assumption of different thermal and dielectric responses of slow and fast modes of the system. A relaxation α', slower than the bulky segmental α and common in polyurethanes, appears here too. A detailed analysis of dielectric spectra provides some evidence that this relaxation has cooperative character. An additional relaxation g, which is not commonly observed, accompanies the Maxwell Wagner Sillars interfacial polarization process, and has dynamics similar to it. POSS is found to introduce conductivity and possibly alter its mechanism. The study points out that different architectures of incorporation of POSS in polyurethane affect its physical properties by different mechanisms.


Asunto(s)
Compuestos de Organosilicio/química , Polietilenglicoles/química , Poliuretanos/química , Materiales Biocompatibles/química , Rastreo Diferencial de Calorimetría/métodos , Conductividad Eléctrica , Vidrio/química , Dureza , Polímeros/química , Temperatura , Difracción de Rayos X/métodos
20.
Shanghai Kou Qiang Yi Xue ; 29(3): 325-328, 2020 Jun.
Artículo en Chino | MEDLINE | ID: mdl-33043354

RESUMEN

PURPOSE: To analyze the effect and long-term success rate of using glass fiber post or metal post in restoration of anterior tooth defect. METHODS: One hundred and fifty cases with anterior tooth defects were chosen after root canal therapy in our hospital. According to different material being chosen, the patients were divided into fiber post group and metal post group with 75 cases in each group. Local gingival sulcus fluid (GCF) levels and alkaline phosphatase (ALP) level in gingival sulcus liquid were measured and compared 4 weeks, 6 months, 1 year, 2 years and 3 years after restoration. Restoration integrity, edge fitness and color matching of two groups were compared after follow-up for 3 years. The data were analyzed with SPSS 19.0 software package. RESULTS: Four weeks, 6 months, and 1 year after restoration, local GCF, ALP levels significantly elevated in both groups. The fiber post group showed more significant elevated levels of GCF and ALP than the metal post group (P<0.05). After 2 and 3 years, the difference between the two groups was not significant. The gingival color matching degrees were significantly better in the glass fiber post group after 1 year compared with that in the metal post group(P<0.05). The success rate of metal post group was significantly higher than that of fiber post group 3 years after restoration(P<0.05). CONCLUSIONS: Fiber post and metal post both have satisfactory restoration result for tooth defect in anterior teeth area. However, the use of precious metal alloy post may reduce the possibility of microleakage between tooth-prosthesis surfaces.


Asunto(s)
Técnica de Perno Muñón , Vidrio , Humanos , Metales , Tratamiento del Conducto Radicular
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