Microporous Glass Research Articles

A solution-processed radiative cooling glass.

Passive daytime radiative cooling materials could reduce the energy needed for building cooling up to 60% by reflecting sunlight and emitting long-wave infrared (LWIR) radiation into the cold Universe (~3 kelvin). However, developing passive cooling structures that are both practical to manufacture and apply while also displaying long-term environmental stability is challenging. We developed a randomized photonic composite consisting of a microporous glass framework that features selective LWIR emission along with relatively high solar reflectance and aluminum oxide particles that strongly scatter sunlight and prevent densification of the porous structure during manufacturing. This microporous glass coating enables a temperature drop of ~3.5° and 4°C even under high-humidity conditions (up to 80%) during midday and nighttime, respectively. This radiative "cooling glass" coating maintains high solar reflectance even when exposed to harsh conditions, including water, ultraviolet radiation, soiling, and high temperatures.

Microstructural Properties and in vitro Dissolution of Microporous Bioactive 13-93B3 Glass Powders Synthesized via Solution Combustion Synthesis

This study investigates the bioactivity and microstructural properties of borate-based bioactive 13-93B3 glass produced by the solution combustion synthesis (SCS) method using urea and sucrose fuels at different reaction temperatures. The results show these glasses exhibit unique properties compared to conventionally-synthesized borate-based bioactive glasses. The glass particles produced have porous surfaces, with particle sizes below 100 nm. BET measurements reveal that the mesoporous structure of these glasses is characterized by high-specific surface areas, promoting a high ion release and hydroxyapatite layer formation in simulated body fluid (SBF). The crystallization of the amorphous calcium phosphate was investigated by 1H, 31P MAS, and 2D 31P{1H} heteronuclear correlation (HETCOR) spectroscopy, showing that it progresses linearly up to three days. The produced glasses were tested for their effects on the viability of 3T3 cells and were found to have no toxic effects. Therefore, the produced glasses are promising candidates for tissue engineering applications.

Photosynthetic microporous bioactive glass ceramic beads for treating avascular osteonecrosis

Bioactive glass (BG) ceramics have attracted considerable attention as ideal bone grafts for treating avascular osteonecrosis owing to similarities in biological function with that of native bone. Metal ion-doped BGs exhibit outstanding biocompatibility, controllable biodegradability, excellent osteoinductivity, and angiogenic ability. Moreover, effective oxygen generation can support the healing of osteonecrotic defects. In this study, we developed simple sol–gel, gel-casting, and surface modification methods to fabricate photosynthetic microporous BG ceramic beads with improved therapeutic efficacy for avascular osteonecrosis by combining the oxygen generation ability, osteoconductivity, osteoinductivity, and angiogenic ability. The BG ceramic beads exhibited interconnected microporous structures with uniform micropores and unequiaxed grains, and this microstructure was not affected by Sr- and Cu-co-doping. Conversely, Sr- and Cu-co-doping, epigallocatechin gallate immobilization, and thylakoid coating affected the in vitro biological activity of the BG ceramic beads. Biological activity assays revealed that the thylakoid-coated photosynthetic microporous BG (BG12ET) ceramic beads promoted osteoblastic cell proliferation and endothelial cell tube formation more effectively than other ceramic beads. Therefore, BG12ET ceramic beads incorporated with osteoinductive and angiogenic factors can potentially provide a new generation of bone grafts for synergistic osteonecrosis therapy.

Effect of Heat Treatment of Microporous Glass on Its Structural and Electrosurface Characteristics

Effect of Heat Treatment of Microporous Glass on Its Structural and Electrosurface Characteristics

Preparation of microporous glass fiber cloth without cracking

A glass fiber cloth (GFC) with microporosity was prepared upon the suppression of crack generations. After the prepared GFC was heat-treated, it was slowly cooled to room temperature and then subsequently treated with hydrochloric acid. The experimental data through complementary techniques including scanning electron microscopy, nitrogen adsorption/desorption isotherm, solid-state 29Si nuclear magnetic resonance spectroscopy, and elemental analysis revealed the conversion of the slowly-cooled GFC into a microporous solid with no cracks in each glass fiber upon the alkaline leaching by hydrochloric acid. These results clearly indicated the formation of microporous GFC without cracking.

Finite Element Simulation of Micro-Thermoelectric Generators Based on Microporous Glass Template

COMSOL Multiphysics software-based three-dimensional finite element analysis is widely used in the performance simulation of thermoelectric devices. In this study, this software is used to simulate the heat transfer processes and power generation performance of micro-thermoelectric generators based on a microporous glass template. The temperature and electrical potential fields are coupled to each other through the thermoelectric effects during the calculations. The power generation performances of micro-thermoelectric generators with different template heights (d) for various temperature differences between their hot and cold ends (∆Th-c) are calculated. For the micro-thermoelectric generator that included four pairs of TE couples, the temperature difference between the two sides of the TE columns (∆TTE) and the open circuit voltage (Uoc) both increased with increasing d, but the growth rate gradually decreased. When d is greater than 0.2 mm, the increment basically becomes negligible. The maximum output power (Pmax) first increases and then decreases with increasing d, reaching a maximum value when d is 0.2 mm. Therefore, we can optimize the size of device according to the simulation results to ensure that the device produces the optimal output performance during the experiments. A model with the same parameters used in the experiment (i.e., d=0.2 mm) was then established and it generated a Uoc of 35.2 mV and a Pmax of 228.8 μW when ∆Th-c was 107.5 K (∆TTE = 97.55 K). The errors between the simulation and the experimental results are small and thus also verify the accuracy of the power generation performance test results.

Adsorption of Iron(III) Ions on Porous Glass with Different Pore Space Structures

The article studies the adsorption of iron ions from solutions of iron(III) chloride with a concentration of 10–4–10–3 M at pH 3 on micro- and macroporous glass, as well as on microporous glass heat-treated at 750°C, obtained from two-phase sodium borosilicate glass. It is found that the adsorption values at a constant concentration of the iron chloride solution are a function of the structural parameters of the porous glass (PG). It is shown that the Freindlich and Langmuir adsorption isotherms can be used to analyze the experimental data and the constants of these isotherms are found. In the systems studied, adsorption mainly occurs via the monolayer mechanism.

Electrodeposition of Bi-Te Thin Films on Silicon Wafer and Micro-Column Arrays on Microporous Glass Template.

Electrodeposition is an important method for preparing bismuth telluride (Bi2Te3)-based thermoelectric (TE) thin films and micro-column arrays. When the concentrations of Bi:Te in electrolytes were 3 mM:4 mM, the TE films satisfied the Bi2Te3 stoichiometry and had no dependence on deposition potential. With increasing over-potential, crystal grains changed from lamellar structures with uniform growth directions to large clusters with staggered dendrites, causing a decrease in the deposition density. Meanwhile, the preferred (110) orientation was diminished. The TE film deposited at −35 mV had an optimum conductivity of 2003.6 S/cm and a power factor of 2015.64 μW/mK2 at room temperature due to the (110)-preferred orientation. The electrodeposition of TE micro-columns in the template was recently used to fabricate high-power micro-thermoelectric generators (micro-TEG). Here, microporous glass templates were excellent templates for micro-TEG fabrication because of their low thermal conductivity, high insulation, and easy processing. A three-step pulsed-voltage deposition method was used for the fabrication of micro-columns with large aspect ratios, high filling rates, and high density. The resistance of a single TE micro-column with a 60 μm diameter and a 200 μm height was 6.22 Ω. This work laid the foundation for micro-TEG fabrication and improved performance.

Use of a Glass Membrane Pumping Emulsification Device Improves Systemic and Tumor Pharmacokinetics in Rabbit VX2 Liver Tumor in Transarterial Chemoembolization.

To evaluate the phamacokinetics of epirubicin in conventional transarterial chemoembolization using a developed pumping emulsification device with a microporous glass membrane in VX2 rabbits. Epirubicin solution (10 mg/mL) was mixed with ethiodized oil (1:2 ratio) using the device or 3-way stopcock. Forty-eight rabbits with VX2 liver tumor implanted 2 weeks prior to transarterial chemoembolization were divided into 2 groups: a device group (n= 24) and a 3-way-stopcock group (n= 24). Next, 0.5 mL of emulsion was injected into the hepatic artery, followed by embolization using 100-300-μm microspheres. The serum epirubicin concentrations (immediately after, 5 minutes after, and 10 minutes after) and the tumor epirubicin concentrations (20 minutes after and 48 hours after) were measured after transarterial chemoembolization. Histopathologic evaluation was performed with a fluorescence microscope. The area under the curve and maximum concentrations of epirubicin in plasma were 0.45 ± 0.18 μg min/mL and 0.13 ± 0.06 μg/mL, respectively, in the device group and 0.71 ± 0.45 μg min/mL and 0.22 ± 0.17 μg/mL, respectively, in the 3-way-stopcock group (P= .013 and P= .021, respectively). The mean epirubicin concentrations in VX2 tumors at 48 hours in the device group and the 3-way-stopcock group were 13.7 ± 6.71 and 7.72 ± 3.26 μg/g tissue, respectively (P= .013). The tumor necrosis ratios at 48 hours were 62 ± 11% in the device group and 51 ± 13% in the 3-way-stopcock group (P= .039). Conventional transarterial chemoembolization using the pumping emulsification device significantly improved the pharmacokinetics of epirubicin compared to the current standard technique using a 3-way stopcock.

A two-region transport model for interpreting T1-T2 measurements in complex systems.

A 1D two region coupled pore model with discrete pore coupling is developed to elucidate the eigenmode interactions in regions with different surface relaxivity. Numerical solution of the model and simulation of the correlation experiment for varying surface relaxivity, pore connectivity and pore size ratio indicate the role of negative eigenmodes and overlap of T1 and T2 eigenmodes in generating a time domain signal increase with inversion recovery time, t1. The eigenmodes and eigenfunctions are considered in detail providing connection between the mathematical model and the diffusion dynamics and spin physics of the system. Physical systems, i.e. a microporous glass bead pack, a cyclopentane/water hydrate former, and beeswax, showing experimentally measured T1-T2 time domain signal rise are considered within the limitations of the model.

Porous purple glass – a cobalt imidazolate glass with accessible porosity from a meltable cobalt imidazolate framework

We report the first microporous cobalt imidazolate glass obtained from a meltable cobalt-based zeolitic imidazolate framework, ZIF-62(Co).

Efficient Prediction of Multidomain Flow and Transport in Hierarchically Structured Porous Media

AbstractStructural hierarchy is a fundamental characteristic of natural porous media. Yet it provokes one of the grand challenges for the modeling of fluid flow and transport since pore‐scale structures and continuum‐scale domains often coincide independent of the observation scale. Common approaches to represent structural hierarchy build, for example, on a multidomain continuum for transport or on the coupling of the Stokes equations with Darcy's law for fluid flow. These approaches, however, are computationally expensive or introduce empirical parameters that are difficult to derive with independent observations. We present an efficient model for fluid flow based on Darcy's law and the law of Hagen‐Poiseuille that is parameterized based on the explicit pore space morphology obtained, for example, by X‐ray μ‐CT and inherently permits the coupling of pore‐scale and continuum‐scale domain. We used the resulting flow field to predict the transport of solutes via particle tracking across the different domains. Compared to experimental breakthrough data from laboratory‐scale columns with hierarchically structured porosity built from solid glass beads and microporous glass pellets, an excellent agreement was achieved without any calibration. Furthermore, we present different test scenarios to compare the flow fields resulting from the Stokes‐Brinkman equations and our approach to comprehensively illustrate its advantages and limitations. In this way, we could show a striking efficiency and accuracy of our approach that qualifies as general alternative for the modeling of fluid flow and transport in hierarchical porous media, for example, fractured rock or karstic aquifers.

A Review of the Most Commonly Used Methods for Sample Collection in Environmental Surveillance of Poliovirus.

We performed a review of the environmental surveillance methods commonly used to collect and concentrate poliovirus (PV) from water samples. We compared the sampling approaches (trap vs grab), the process methods (precipitation vs filtration), and the various tools and chemical reagents used to separate PV from other viruses and pathogens in water samples (microporous glass, pads, polyethylene glycol [PEG]/dextran, PEG/sodium chloride, NanoCeram/ViroCap, and ester membranes). The advantages and disadvantages of each method are considered, and the geographical areas where they are currently used are discussed. Several methods have demonstrated the ability to concentrate and recover PVs from environmental samples. The details of the particular sampling conditions and locations should be considered carefully in method selection.

Internal structure of magnetic porous glasses and the related ferroelectric nanocomposites

The internal structure of empty porous micro- and macroporous magnetic glasses and the related nanocomposites containing NaNO2 and KNO3 embedded in pores of the glasses has been investigated using small-angle neutron scattering. The characteristic sizes of magnetite particles in matrices and the sizes of nanoparticles embedded in ferroelectric materials have been estimated. It has been shown that, for microporous glasses in the momentum transfer range 0.35 nm–1 < Q < 1.7 nm–1, the dependence of the small-angle neutron scattering intensity on the momentum transfer has two characteristic regions: the first region corresponds well to the Porod’s law Q–4 (smooth surface), and the second region is consistent with the mass fractal reflecting the internal structure of channels in the microporous glass. For macroporous glasses over the entire momentum transfer range 0.35 nm–1 < Q < 1.7 nm–1, the scattering intensity is described by the dependence I(Q) ~ Q–n with α = 3.96 ± 0.02; i.e., in these glasses, there is a system of channels with sufficiently smooth surfaces.

Laboratory evaluation of nanoparticle penetration efficiency in a cylindrical counter flow denuder for non-specific removal of trace gases

ABSTRACTThis article presents a cylindrical counter-current flow diffusion denuder with high efficiency penetration of nanoparticles, for non-specific removal of trace gases from an air flow. The denuder was designed to exchange gases in the sample flow by diffusion to the purge flow across a cylindrical microporous glass tube. Laboratory test results indicated that removal efficiencies of gases increased with a lower sample flow rate and a higher sample to purge flow rate ratio. Additionally, the pore size of the microporous glass did not affect gas removal efficiency and particle penetration following optimization of sample and purge flow rate conditions. Significantly high particle penetration was obtained for the counter flow denuder technique (94% penetration for 20 nm of polystyrene latex particle [PSL]) that agreed with theoretical estimation attributed to diffusion loss.Copyright © 2017 American Association for Aerosol Research

Electrokinetic properties of iron-containing microporous glasses

The electrokinetic properties of the particles of microporous borosilicate glass powder containing the magnetite phase in its composition on the background of an indifferent electrolyte (NaCl) have been studied. It is found that the modification of two-phase sodium borosilicate glass with iron oxide leads to a shift in the position of the isoelectric point from pH 0.5 for alkali borosilicate (ABS) porous glass (PG) to pH 4.1 ± 0.1 for iron-containing ABS PG. The observed changes in the behavior of modified PG open up new prospects for their practical application.

Experimental identification of diffusive coupling using 2D NMR.

Spin relaxation based nuclear magnetic resonance (NMR) methods have been used extensively to determine pore size distributions in a variety of materials. This approach is based on the assumption that each pore is in the fast diffusion limit but that diffusion between pores can be neglected. However, in complex materials these assumptions may be violated and the relaxation time distribution is not easily interpreted. We present a 2D NMR technique and an associated data analysis that allow us to work directly with the time dependent experimental data without Laplace inversion to identify the signature of diffusive coupling between different pores. Measurements on microporous glass beads and numerical simulations are used to illustrate the technique.

Microporous glass ceramics from combination of silicate, borate and phosphate wastes

Borate mineral wastes and phosphate ash resulting from the incineration of meat and bone meal represent two particularly abundant inorganic wastes. This paper is dedicated to the combination of such wastes, together with kaolin clay, focused on the development of highly porous ceramic bodies. Borate waste has a multiple effect, providing liquid phase at the sintering temperature (1050°C), gas release (from the decomposition of its calcite fraction) and a CaO source, which reacts with residues from clay and promotes the formation of anorthite crystals as a newly formed phase. Control of the heating rate, i.e. adoption of fast heating (20°C min−1) and, above all, introduction of recycled soda–lime–silica glass as secondary additive, allowed obtaining lightweight microporous bodies (density below 0·45 g cm−3) with uniform pore structure that could be useful for thermal and acoustic insulations.

Structure of magnetic nanoclusters in ferriferous alkali borosilicate glasses

The crystal structure of two-phase and porous alkali borosilicate glasses with embedded magnetic atoms has been investigated using X-ray powder diffraction. It has been shown that, during the preparation of two-phase (nonporous) glasses, the α-Fe2O3 phase undergoes a transition to magnetite (Fe3O4) with the formation (at particular concentrations of α-Fe2O3 in the initial mixture) and stabilization of the β-Fe2O3 phase. The characteristic sizes of nanoparticles of iron oxides (Fe3O4 and β-Fe2O3) in these glasses have been determined. For two types of porous glasses (namely, the macroporous glass Fe20-MAP and the microporous glass Fe20-MIP), the occupancies of the octahedral (Fe2+) and tetrahedral (Fe2+/Fe3+) iron positions in magnetite have been found.

Core–shell glass fibers with high bioactivity and good flexibility

In this investigation, electrospun silica fibers were utilized as template for growth of microporous bioactive glass to form composite submicron fibers. The as-synthesized fibers are core–shell structured with a condensed silica core and a microporous bioactive glass shell. Specific surface area, total pore volume and average pore size of the fibers are measured to be 449.7m2/g, 0.232cm3/g and 1.7nm, respectively. Benefiting from the microporous bioactive glass shell and the condensed silica core, the compound glass fiber here shows both high bioactivity and good flexibility, which promises great potential for many biomedical applications, including tooth repairing, hard-tissue engineering and cell culturing, etc.