Porous Glass Beads Research Articles

Facile synthesis and photocatalytic properties of TiO2 nanoparticles supported on porous glass beads

This paper presents a novel immobilization method for the preparation of highly dispersed TiO2 nanoparticles supported on porous glass beads. The method involves an in situ ion exchange process and a calcination process. Mono-dispersed TiO2 nanoparticles exhibiting the anatase phase with different mean diameter and different loading amount have been successfully prepared through the controllable and green way. With the increase of loading amount of Ti from 0.08wt.% to 4.55wt.%, the mean diameter of the TiO2 nanoparticles varied from 3.8 to 5.3nm. And the band gaps of the TiO2 nanoparticles with the highest and lowest loading amount are 3.25 and 3.00eV, respectively. The prepared TiO2 nanoparticles supported on porous glass beads showed excellent photocatalytic performance for the degradation of methyl orange (MO). For the catalyst with a Ti content of 0.08wt.%, when the dosage was 1.93e−5g/mL, 65% of the total MO decomposed after 30min; for the catalyst with a Ti content of 2.56wt.%, when the dosage reached 0.81e−3g/mL, complete degradation was observed.

Triplet–Triplet Annihilation‐Based Anti‐Stokes Oxygen Sensing Materials with a Very Broad Dynamic Range

AbstractA novel concept for designing optical oxygen sensing materials is reported. Oxygen‐sensitive anti‐Stokes emission is generated via triplet–triplet annihilation‐based upconversion and serves as an analytical parameter. Porous glass beads are used to incorporate the “sensing chemistry” including a sensitizer and an annihilator dissolved in a high boiling solvent. The beads are dispersed in silicone rubber or Teflon AF to produce solid state optodes. Inexpensive low power light sources (LEDs) are used for the excitation. The upconverted emission shows unmatched sensitivity both for the luminescence decay time and for the luminescence intensity. The latter features unusual quadratic Stern‐Volmer plots. Much lower sensitivity of the residual NIR luminescence of the sensitizer allows determination of pO2 in the broad dynamic range from trace oxygen quantities to ≈40 kPa. Interrogation of the sensors in frequency domain is demonstrated. Influence of the excitation light power on the calibration, temperature effects, dynamic response to altering pO2, and photostability of the sensing materials are also investigated.

Size Control and Catalytic Activity of Highly Dispersed Pd Nanoparticles Supported on Porous Glass Beads

This paper presents a novel in situ method to prepare monodispersed palladium nanoparticles supported on porous glass beads with an egg-shell structure at room temperature. This method integrates two processes of ion exchange and reduction in one step just by changing the solvent from water to alcohol. The monodispersed Pd nanoparticles around 3.75 nm in diameter with a face-centered cubic structure have been successfully prepared. The adsorption capacity for palladium reached 55.00 ± 0.55 mg/g in ethanol, which was 26 times larger than that in water. These Pd nanoparticles supported on porous glass beads showed an excellent catalytic performance through the hydrogenation of cyclohexene. In addition, this in situ method was also successfully applied to prepare monodispersed silver and gold nanoparticles supported on porous glass beads. Overall, this facile method provided an alternative for preparing a supported nanoparticle catalyst in a green way.

Porous glass beads as a new adsorbent to remove sulfur-containing compounds

This paper explores porous glass beads as a pollutant-free-prepared, low-cost, and recyclable adsorbent for desulfurization. Porous glass beads with a specific surface area, pore volume, and mean pore diameter of 162.6 m2 g−1, 0.26 cm3 g−1, and 6.34 nm, respectively, were obtained by subcritical water treatment. The effects of the surface chemistry of the adsorbent and the structure of the organosulfur molecules on adsorption capacity were studied; the software, Materials Studio, was used to calculate the interactions between the surface of the glass beads and the sulfur-containing compounds. Compared with these porous glass beads, two other kinds of porous glass beads modified by hexamethyldisilazane and hydrochloric acid, respectively, showed much lower adsorptive capacity for dibenzothiophene, indicating the metal ions contained in the glass played an important role during the adsorption; the capacities of the porous glass beads for benzothiophene, dibenzothiophene, and 4,6-dimethyldibenzothiophene were 6.47 ± 0.09, 8.58 ± 0.09, and 11.20 ± 0.08 mg(S) gadsorbent−1, respectively, corresponding to the simulation results. The adsorptive capacity for dibenzothiophene decreased with the increase of temperature but increased with the increase of initial concentration, the highest capacity of 10.29 ± 0.11 mg(S) gadsorbent−1 was obtained at 303 K with the initial concentration of 565 ppmw(S). Spent adsorbent can be regenerated by heating at high temperature, and the adsorptive capacity only decreased about 3.38% after five cycles. Experimental results and the computer simulations indicate that polar interactions between the surface and sulfur-containing compounds dominated the adsorption.

Effect of Pore Size on Performance of Hydrogen Fermentation with Porous Glass Beads

Effect of Pore Size on Performance of Hydrogen Fermentation with Porous Glass Beads

Mitotic Spindle Assembly around RCC1-Coated Beads in Xenopus Egg Extracts

Author SummaryThe mitotic spindle is a bipolar structure that is responsible for separating the two sets of duplicated chromosomes in a dividing cell, thereby delivering one set to each of the two daughter cells. It is built from dynamic filaments called microtubules, as well as hundreds of other components that contribute to the organization and dynamics of the microtubules and to chromosome movement. To understand which proteins are essential for spindle formation and function, we would like to be able to build it from purified components. As a step towards this goal, we coupled individual proteins to inert glass beads (as a substitute for chromosomes), to determine what combination of proteins can induce spindle assembly in a complex cytoplasm derived from frog eggs. We found that a single enzyme called RCC1 is sufficient to activate a pathway that stabilizes and organizes microtubules into a bipolar structure around the bead, but that this bead then oscillated back and forth between the poles of the spindle. By coupling a microtubule-based motor protein together with RCC1 on the bead, we were able to balance the bead in the center of the spindle. Thus, two proteins immobilized on a bead can substitute for a chromosome and induce stable spindle formation.

Fine particle deposition to porous beds

We summarize the results of flume experiments examining the transport behavior of dilute suspensions of silt‐sized particles carried in an open channel flow over three separate bed types including porous open mesh, glass beads, and small cobbles. In these experiments the time‐varying concentration of particles in suspension transport was measured as a function of suspended‐particle size and bed shear stress, and analyzed using a 1‐D model incorporating simultaneous deposition and entrainment. Rates of fine‐particle deposition to the bed are found to approach Stoke's settling velocity in slow flows, but diminish systematically with increasing bed shear stress and mean flow speed. No discernible re‐entrainment from the porous beds was observed, indicating that such beds act as an effective sink for fine particles. When our new results are compared to those of related, previously reported experiments examining fine‐particle transport over smooth impermeable beds, silt‐sized particles display similar behavior with regard to systematic reduction in deposition velocity independent of suspended‐silt‐particle size or bed porosity. This behavior is tentatively interpreted to reflect the effects of lift in a linear shear flow in excess of submerged weight of individual particles. Our findings compare favorably with values of effective settling velocity of fine particulate organic matter in natural channel flows reported elsewhere.

Isotope‐coded dimethyl tagging for differential quantification of posttranslational protein carbonylation by 4‐hydroxy‐2‐nonenal, an end‐product of lipid peroxidation

Peroxidation of cellular membrane lipids, rich in polyunsaturated fatty acids, generates electrophilic, α, β-unsaturated aldehydes such as 4-hydroxy-2-nonenal (HNE). HNE is a highly reactive and cytotoxic molecule that can react with the nucleophilic sites in proteins causing posttranslational modification. The identification of protein targets is an important first step; however, quantitative profiling of site-specific modifications is necessary to understand the biological impact of HNE-induced carbonylation. We report a method that uses light (H(12)CHO) and heavy (D(13)CDO) isotopic variant of formaldehyde to differentially label primary amines (N-termini and ε-amino group of lysines) in peptides through reductive methylation and, combined with selective enrichment of modified peptides, permits comparison of the extent of carbonylation in two samples after mixing for simultaneous liquid chromatography-mass spectrometry. Specifically, dimethyl-labeled peptide carbonyls were fractionated from unmodified peptides using solid-phase hydrazide chemistry to immobilize them to porous glass beads and, after removing the unmodified peptides by thoroughly washing the beads, subsequently recover them by acid-catalyzed hydrolysis. The method was developed using HNE-modified synthetic peptides and also showing enrichment from a complex matrix of digested human plasma proteins. Applicability was confirmed using apomyoglobin as an analyte, implicating thereby its potential value to proteome-wide identification and relative quantification of posttranslational protein carbonylation with residue-specific information. Because HNE attachment may not necessarily cause change in protein abundance, this modification-focused quantification should facilitate the characterization of accompanied changes in protein function and, also, provide important insights into molecular signaling mechanisms and a better understanding of cellular processes associated with oxidative stress.

Comparison of Covalent and Noncovalent Immobilization of Malatya Apricot Pectinesterase (Prunus armeniacaL.)

Pectinesterase isolated from Malatya apricot pulp was noncovalently and covalently immobilized onto bentonite and glutaraldehyde-containing amino group functionalized porous glass beads surface at pH 8.0 and pH 9.0, respectively. The effect of various parameters such as pH, temperature, activation energy, heat and storage stability on immobilized enzyme were investigated. The optimum temperature of covalently and noncovalently immobilized PE was 50°C. This value was 60°C for free PE. Although optimum pH of covalently-immobilized PE was 8.0, this parameter was 9.0 for free and covalently-immobilized PE. The noncovalently immobilized enzyme exhibited better thermostability than the free and covalently immobilized PE.

Immobilization of Cellulase and Hemicellulases on Porous Glass Beads

Abstract Experiments on immobilization of cellulase complex (cellulase, Novozymes) and enzyme complex (cellulases and hemicellulases, Novozymes) were performed on porous Siran™ beads using covalent and non-covalent bonding methods. Free enzyme complex was used for hydrolyzing various pretreated biomass such as corn stover, distillers dried grain with solubles, switch grass and blue stem grass. Maximum activity of enzyme complex was found with corn stover and was used as a substrate for measuring cellulase and hemicellulases activities. Protein loading for immobilized cellulase complex and enzyme complex on Siran™ carriers was found in the range of 10.776–18.000 % and 19.932–23.082 %, respectively. Activity loading for immobilized cellulase complex with avicel was in the range of 16.610–22.026 %. For enzyme complex, activity loading was found in the range of 43.558–61.222 %, 8.274–19.124 %, and 7.180–14.114 % with avicel, xylan, and corn stover as substrates, respectively. Recycling experiments for immobilized cellulase complex and enzyme complex were carried out using various substrates, and the residual enzyme activity was measured after the third cycle. Carbodiimide bonded cellulase complex retained more residual enzyme activity with avicel (49.460 %), which indicates a good cross linker for cellulase immobilization. The enzyme complex bonded to carbodiimide, and glutaraldehyde retained residual activity of 44.160 % with xylan and 73.230 % with corn stover, respectively. Recycling studies showed greater retention in residual enzyme activity with covalent bonded enzymes than non-covalent bonded enzymes. Glutaraldehyde and carbodiimide were found to be effective cross linkers for immobilizing both cellulase and hemicellulases in covalent bonding method.

Microbial calcite, a bio-based smart nanomaterial in concrete remediation

The concept of developing a biosealant in concrete remediation is based on unique microbial metabolic processes. A common soil microorganism, Sporosarcina pasteurii, can induce CaCO3 precipitation in the surroundings in response to environmental cues such as high pH and available nutrients and minerals. A new biomolecule, microbial calcite is introduced as a smart nanomaterial for self-healing concrete – its effects on concrete performance were evaluated with regard to surface crack remediation and durability enhancement. For crack remediation, S. pasteurii cells immobilized on porous glass beads, SiranTM, were applied to cracks and tested for stiffness and compressive strengths. For durability tests, cement mortar beams prepared with bacteria were subjected to freeze–thaw cycles and examined for mean expansions and weight changes. Overall performance of the concrete was significantly enhanced by treatment with microbial calcite in simulated concrete cracks and cement mortar beams.

PFG NMR study of liquid n-hexane self-diffusion in the bed of porous glass beads

PFG NMR study of liquid n-hexane self-diffusion in the bed of porous glass beads

Expermintal And Theoretical Study Of Natural Convection Heat Transfer Between Two Concentric Cylinders Filled With Porous Medium.

Porous media have considerable importance in improvement of heat transfer and storage. This research includes an experimental and theoretical study of natural convection heat transfer between two concentric cylinders filled with a porous medium, under condition of applying uniform heat flux on the inner cylinder and constant outer surface temperature for the outer cylinder. Two types of filling material were used as porous medium , iron and glass beads , the study shows that the heat dissipated ability in the inner cylinder is function of Rayligh number , and the Nusselt number increase is directly proportional with the increase in Rayligh number . Fluent program was used to show the heat dissipation and the flow lines inside the gap between the two cylinders , the experimental results show that the nature of the heat distribution depends greatly on Rayligh number , and the use of highly heat conductive materials as porous medium will completely cancel the convection as a mean of heat transfer. Key wards: Heat transfer, Natural convection, Porous medium, and two concentric cylinders.

Dye decolorization and detoxification by laccase immobilized on porous glass beads

The decolorization and detoxification of textile dyes by fungal laccase immobilized on porous glass beads were evaluated. Anthraquinone (Reactive blue 19 and Dispersed blue 3) and indigoid (Acid blue 74) dyes were degraded more rapidly than the azo dyes (Acid red 27 and Reactive black 5). There was no dye sorption to the enzyme bed when decolorization rates were high (>12 μM dye/U-h) but at moderate rates (8 to >0.06 μM/U-h), there was a transient color which disappeared upon prolonged exposure. With Reactive black 5, permanent adsorption occurred most likely because laccase had been totally inactivated. Although laccase treatment was more efficient at decolorizing the anthraquinone dyes, their toxicity (as determined by the Microtox assay) increased while the less efficiently decolorized solutions of azo and indigoid dyes became less toxic. These results demonstrate the potential and limitations of using immobilized laccase to enzymatically decolorize a range of different dye classes and reduce dye toxicity in a single step.

Inverse gas chromatography for determining the dispersive surface energy of porous silica

Inverse gas chromatography (IGC) is a modern technique for the characterization of porous materials, which provides thermodynamic parameters of the solids. Porous glass beads, silica gels and ordered mesoporous materials were used as model systems to study correlations between the dispersive part of the surface energy and the surface chemistry of porous materials. The surface chemistry of silica was controlled via thermal treatment and reaction with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) or 3-amino-propyltriethoxysilane (3-APTS). The dependency of the surface energy on the various modifications was investigated in this study. Furthermore, the impact of microstructure on the dispersive surface energy was determined by a comparative study of the ordered mesoporous materials MCM-41, SBA-15 and SBA-16.

LTCC microreactor for urea determination in biological fluids

This article presents design, fabrication and testing of an enzymatic microreactor with integrated heater and a temperature sensor. The microsystem was fabricated using low temperature co-fired ceramics (LTCCs) technology, which has a few advantages over silicon-based fabrication processes. Computational fluid dynamics (CFD) and finite element method (FEM) analysis was used to arrive at an optimum microreactor and heater design. The heater performance was evaluated using thermographic measurements, and the temperature resistance characteristics of the temperature sensor revealed good electrical properties and stability at higher temperatures (up to 140°C). As an enzyme carrier, the glass beads coated with polyacrylonitrile layer and porous glass beads were used. The microreactor was used to measure urea concentration with high output signal (ca. 2.5 pH units) and large scale. The maximal output signal enabled to apply presented microreactor for determination of urea in biological or environmental fluids. The properties of the LTCC-based enzymatic microreactor were comparable with the features of a similar one made in silicon.

Heavy Metal Ion Sorption Properties of Porous Glass Beads with a Core‐Shell Structure

Porous glass beads with a core‐shell structure have been successfully prepared through subcritical water treatment. The product has high capacity and fast mass transfer property due to its structure, and may serve as an inorganic adsorbent. Accordingly, the kinetics, the equilibrium isotherm, and the column breakthrough curve of this material were measured using Cu(II) as a model target ion. The results indicate that the material has an advantage over some other adsorbents, such as kaolinite and clinoptilolite, in both adsorption capacity and kinetics. The adsorption capacity for Cu(II) is almost twice as much as that of the Na‐mordenite. The pseudo‐second order kinetic and the Langmuir isotherm fit the experimental data. An adsorption mechanism was hypothesized in which the non‐bridging oxygen ions in the glass network were hypothesized to be the functional site.

Novel immobilization routes for the covalent binding of an alcohol dehydrogenase from Rhodococcus ruber DSM 44541

Immobilization of the alcohol dehydrogenase ADH-‘A’ from Rhodococcus ruber DSM 44541 has been performed with different amino-functionalized carrier materials. The procedure included the activation of the carrier with glutaraldehyde and subsequent covalent binding to the enzyme. The porous glass beads TRISOPERL ® and TRISOPOR ®, magnetic particles, and detonation nanodiamonds were used as carriers in these experiments. In all cases, the immobilization was successful with almost quantitative immobilization yields; subsequently the activity for the reduction of acetophenone was lower compared to the activity of the free biocatalyst. Activity yields of 40% and 60% were obtained. The immobilized biocatalysts showed high stabilities in repetitive batches.

Immobilization of apricot pectinesterase ( Prunusarmeniaca L.) on porous glass beads and its characterization

Pectinesterase isolated from Malatya apricot pulp was covalently immobilized onto glutaraldehyde-containing amino group functionalized porous glass beads surface by chemical immobilization at pH 8.0. The amount of covalently bound apricot PE was found 1.721 mg/g glass support. The properties of immobilized enzyme were investigated and compared to those of free enzyme. The effect of various parameters such as pH, temperature, activation energy, heat and storage stability on immobilized enzyme were investigated. Optimum pH and temperature were determined to be 8.0 and 50 °C, respectively. The immobilized PE exhibited better thermostability than the free one. Kinetic parameters of the immobilized enzyme ( K m and V max values) were also evaluated. The K m was 0.71 mM and the V max was 0.64 μmol min −1 mg −1. No drastic change was observed in the K m and V max values. The patterns of heat stability indicated that the immobilization process tends to stabilize the enzyme. Thermal and storage stability experiments were also carried out. It was observed that the immobilized enzyme had longer storage stability and retained 50% of its initial activity during 30 days.

Enhancement of biogenic sulfide production in a packed‐bed bioreactor via critical inoculum design and carrier material selection

Sulfate reducing bacteria (SRB) are commonly used in environmental bioprocesses for the treatment of acid mine drainage and sulfate wastewaters. Biogenic H(2)S is also a potential source of H(2) fuel with the recent development of H(2)S splitting technologies. In this study, a sulfate reducing packed bed bioreactor (PBR) capable of rapidly achieving high volumetric productivities was developed using a novel method of rational inoculum design and the selection of improved biomass carrier materials. An inoculum with initial composition of approximately 95% Desulfovibrio desulfuricans (ATCC 7757) and 5% SRB consortium was designed based on the pure strain's superior immobilization potential and the SRB consortium's superior kinetics. Diatomaceous earth (DE) pellets, porous glass beads, polyurethane foam and bone char were evaluated as potential biomass carrier materials. The DE pellets immobilized the most biomass and were employed in two packed bed bioreactor fermentations. Using the designed inoculum and DE pellets, a packed bed bioreactor achieved a volumetric productivity of 493 mol H(2)S m(-3) day(-1) (based on a 308 mL working volume) with a dissolved sulfide concentration of 9.9 mM. This occurred after 8.3 days of operation and represents a tenfold reduction in the start-up period compared to other sulfate reducing PBRs described in the literature.