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The results of obtaining hollow glass microspheres and their effect on the properties of water-dispersion facade coatings when the titanium oxide and calcium carbonate in the formula are replaced by an equivalent volumetric number of spheres are presented.

A technology was developed for producing in a plasma reactor glass microspheres using the ferruginous quartzite tailings of the Kursk Magnetic Anomaly [KMA]. The predictable effects of the plasma-forming argon-gas flow rate and the plasma reactor power on the fractional composition were determined. It is shown that on increasing the plasma-forming gas flow rate from 1.5 to 2.5 m3/h and the current strength from 400 to 500 A the fraction amount over 630 μm increases due to coagulation processes. It is shown that the glass microspheres are enriched in aluminum and calcium oxides and depleted of silicon, magnesium, sodium, potassium, and iron oxides. It is shown that at high plasma temperatures, of the order of 9000 – 12,000 K, the particles melt completely and spherical glass microspheres ranging in size from 80 to 1250 μm are formed. Operational metrics, such as microhardness, acid resistance, and alkali resistance, of the glass microspheres based on the ferruginous quartzite tailings of KMA were investigated.

Natural fibre reinforced polymer (NFRP) composites are emerging as a viable alternative to metal parts for lightweight components in the automotive and aerospace industry. They are economical and eco-friendly, but their use is confined due to their performance properties. Currently, fillers are often incorporated in NFRP composites to modify their properties. This study explores the reinforcing effects of hollow glass microspheres (HGM) as fillers in continuous NFRP composites. Continuous NFRP laminates were fabricated using woven fabrics (jute, hemp, flax, polypropylene) and HGM with compression moulding. Tensile, flexural and impact tests were conducted to investigate the influence of HGM on the mechanical properties of these laminates. The results indicate that the loading of 1.5 % HGM improves the tensile and flexural properties, but further addition of HGM (3 %) leads to a decline in these properties; furthermore, the impact strength was significantly improved (17 %, 8 %, 24 %) in jute, hemp and flax laminates, respectively by the addition of 3 % HGM.

Transarterial radioembolization (TARE) is, by all standards, a radiation therapy. As such, according to Euratom Directive 2013/59, it should be optimized by a thorough treatment plan based on the distinct evaluation of absorbed dose to the lesions and to the non-tumoural liver (two-compartment dosimetry). Since the dosimetric prediction with 99mTc albumin macro-aggregates (MAA) of non-tumoural liver is much more accurate than the same prediction on lesions, treatment planning should focus on non-tumoural liver rather than on lesion dosimetry. The aim of this study was to determine a safety limit through the analysis of pre-treatment dosimetry with 99mTc-MAA single photon emission computed tomography (SPECT/CT), in order to deliver the maximum tolerable absorbed dose to non-tumoural liver. Data from intermediate/advanced hepato-cellular carcinoma (HCC) patients treated with 90Y glass microspheres were collected in this single-arm retrospective study. Injection was always lobar, even in case of bilobar disease, to avoid treating the whole liver in a single session. A three-level definition of liver decompensation (LD) was introduced, considering toxicity only in cases of liver decompensation requiring medical action (LD type C, LDC). We report LDC rates, receiver operating characteristic (ROC) analysis between LDC and NO LDC absorbed dose distributions, normal tissue complication probability (NTCP) curves and uni- and multivariate analysis of risk factors associated with toxicity. A 6-month timeline was defined as necessary to capture all treatment-related toxicity events. Previous transarterial chemoembolization (TACE), presence or extension of portal vein tumoural thrombosis (PVTT) and tumour pattern (nodular versus infiltrative) were not associated with tolerance to TARE. On the contrary, at the multivariate analysis, the absorbed dose averaged over the whole non-tumoural liver (including the non-injected lobe) was a prognostic indicator correlated with liver decompensation (odds ratio = 4.24). Basal bilirubin > 1.1 mg/dL was a second even more significant risk factor (odds ratio = 6.35). NTCP analysis stratified with this bilirubin cut-off determined a 15% liver decompensation risk at 50 Gy/90 Gy for bilirubin >/

Polyurea was modified by glass microspheres. Compositions of polyurea coatings based on glass microspheres were obtained. The properties of the coatings were evaluated. The results of studies of polyurea-based coating compositions containing hollow glass microspheres are reported. Similar coatings are proposed for waterproofing pre-insulated heat pipes. The composition of a polyurea-based coating containing hollow glass or aluminum-silicate microspheres with diameter 200 – 300 μm and a range of functional additives including ammonium polyphosphate, wollastonite, and microcalcite in a 1 : 1 ratio of glass to aluminum-silicate microspheres was investigated.

Light-weight and high-strength polymer composites have attracted the special attention of automotive and aerospace sectors since they offer advantages such as less fuel consumption and higher fuel efficiency. In the present study, an effort has been made to prepare such polymer composites using natural fiber and very low-density hollow inorganic particles. The use of hollow glass microspheres (HGM) as a potential filler particle for making light-weight hybrid polymer composites was investigated. Polypropylene (PP) and maleic anhydride-grafted-polypropylene (in 9:1 ratio) constituted the base matrix (BM). For strength reinforcement, alkali-treated short bamboo fibers (SBF) were employed, while for making the composite material light in weight, HGM were incorporated. Silane treatment of HGM by (3-aminopropyl)triethoxysilane was performed to enhance interfacial adhesion with BM. Adequate wetting of HGM and SBF was evident from the SEM images of cryo-fractured samples. A 14% increase in tensile strength was observed in comparison to virgin PP for the composite with 5 wt.% HGM, and a desirable decrease in density was observed for all the composite samples with increasing HGM content. Improvement in hardness but a marginal decrease in impact strength due to HGM fillers was observed. Rheological analysis of the composite melt samples showed an apparent increase in the complex modulus with increasing HGM content. Thermal analysis of the composites revealed a significant impact of hybrid fillers on the crystallinity, with SBF showing a minimal effect while HGM reducing it significantly. Wide-angle x-ray diffraction spectra showed changes in the crystal structure of the composite with noticeable β-form peaks.

Use of biodegradable polyester-based polymers in various applications has been extensively carried out in the past decades. Blending recycled poly(ethylene terephthalate) (r-PET) would be an alternative way to improve mechanical rigidity, reduce cost of the blends, and integrate recycle route with renewable resource. In this research, we attempted to prepare poly(butylene succinate) (PBS)/recycled PET (PBS/r-PET) blends via melt blending in various blend ratio (90:10, 80:20, and 70:30 wt%) and then melt compounded with hollow glass microspheres (HGM) (3, 5 and 10 wt%) to obtain thermoplastic composites that would be used in electrical or electronic applications. Mechanical properties of blends and their composites were evaluated by means of tensile and notched Izod impact tests. Compatibility and thermal behavior were characterized using DSC and TGA. Morphology of fractured specimens was studied using SEM. It was found that PBS/r-PET blends exhibited higher tensile modulus with respect to r-PET content; however, toughness of the blends was deteriorated from poor interfacial attraction and molecular weight reduction of PBS matrix. Tg of PBS phase was shifted to higher temperature because of transesterification. The composites had higher specific tensile modulus with respect to HGM loading. With the presence of r-PET, HGM surface was wetted implying r-PET acted as compatibilizer between hydrophobic PBS matrix and hydrophilic HGM, and thus, tensile modulus of composites was 10–40% increased depending on HGM loading.

In this article, a new type of flame-retardant HGM@[EOOEMIm][PF6] was prepared by modifying fly ash hollow glass microspheres (HGM) with ionic liquids 1-((ethoxycarbonyl)methyl)-3-methylimidazolium hexafluorophosphate([EOOEMIm][PF6]). The physical and chemical characteristic of HGM@[EOOEMIm][PF6] was tested by scanning electron microscope–energy-dispersive spectrometer and X-ray photoelectron spectroscopy, respectively. The flame-retardant characteristics including heat and smoke production of TPU composites were investigated using cone calorimeter test (CCT) and limiting oxygen index, etc. The CCT results revealed that the heat release rate (HRR), total smoke release, and smoke factor and so on decreased greatly with the addition of HGM@[EOOEMIm][PF6]. For example, when the loading of HGM@[EOOEMIm][PF6] was 0.125 mass%, the peak HRR value of the sample was decreased to 779.3 kW m−2 (TPU2), reduced by 23.7% compared with TPU1 (1021.1 kW m−2) containing the same loading of HGM. The thermal degradation behaviors of TPU composites have also been indicated by thermogravimetric analysis/infrared spectrometry (TG–IR). The TG–IR results showed that HGM@[EOOEMIm][PF6] could not only improve the thermal stability of TPU composites at high temperature, but also reduce the aromatic compounds as the smoke precursors. In all, HGM@[EOOEMIm][PF6] will make a great influence in improving the flame retardancy of TPU.

The structural changes occurred in bioactive glass microspheres belonging to the system SiO2–Na2O–P2O5–CaO–K2O–MgO incorporating yttrium were investigated before and after soaking in simulated body fluid (SBF) by X-ray diffraction (XRD) and 31P and 29Si magic angle sample spinning nuclear magnetic resonance (MAS-NMR). The addition of yttrium to the bioactive glass composition induces changes in the behavior of the glass microspheres in SBF. The XRD analysis proves that after the immersion in SBF a crystalline hydroxyapatite-like phase is developed on the microspheres surface. The 29Si and 31P MAS-NMR results show that silicate species with two and three bridging oxygens per SiO4 tetrahedra and PO4 monomeric units are present in the glass structure. After immersion in SBF, new silicate species with four bridging oxygens appear as result of silica-gel layer formed on microspheres surface. The formation of crystalline hydroxyapatite-type layer is reflected by the occurrence of narrow components in 31P MAS-NMR spectra. The NMR results support the Hench model for bioactive glasses behavior in biological environments.

A combination of sol–gel Pechini method and flame synthesis was used to prepare yttrium aluminate glass microspheres with the garnet composition (YAG, 62.5 mol% aluminium oxide, 37.5 mol% yttrium oxide). Prepared glass microbeads were studied by optical microscopy, SEM, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and high-temperature (HT) XRD analysis. Formation of YAG as the only crystalline phase was observed during HT XRD experiment in the temperature interval (750–1200 °C), with the onset of YAG phase crystallization in the temperature interval 860–870 °C and most prominent increase in the YAG phase content between 905 and 910 °C. The experimental data obtained by DSC analysis and the Johnson–Mehl–Avrami–Kolmogorov model were used for determination of crystallization behaviour of the studied system. The frequency factor A = 5.2 × 1048 ± 9.6 × 1048 min−1, apparent activation energy E app = 1100 ± 10 kJ mol−1 and the Avrami coefficient m = 4 were determined. The linear temperature dependence of nucleation rate, reaction-controlled crystal growth interface and a 3-D crystal growth were confirmed in the studied system.

This work describes the synthesis of three-dimensional hollow hierarchical mesoporous bioactive glass (HMBG) microspheres based on Herba leonuri pollen grains via a hydrothermal method. The HMBG microspheres perfectly copied the hierarchical porous structure and inner hollow structure constituting the double-layer surface of the natural Herba leonuri pollen grains. This structural mimicry of the pollen grains resulted in a higher degree of adsorption of acetylcholinesterase (AChE) on HMBG microspheres in comparison with mesoporous bioactive glass. Subsequently, an amperometric biosensor for the detection of Malathion was fabricated by immobilizing AChE onto an HMBG microspheres-modified carbon paste electrode. The biosensor response exhibited two good linear ranges during an incubation time of 10 min in the malathion concentration ranges of 0.02–50 ppb and 50–600 ppb, with a detection limit of 0.0135 ppb (S/N = 3). Overall, the prepared enzymatic biosensor showed high sensitivity in the rapid detection of Malathion and could be applied to detect pesticide residues in vegetable matter. An amperometric acetylcholinesterase (AChE) sensor was successfully prepared using HMBG microspheres as the carrier for adsorption of enzyme. The HMBG microspheres perfectly copied the hierarchical porous structure and inner hollow structure with a double-layer surface of the natural Herba leonuri pollen grains. The hybrid structures resulted in more AChE adsorption and protected the catalytic activity of AChE effectively, which made the sensor sensitive and stable.

In this paper, the hollow glass microspheres coated with Fe2O3 (HGM-Fe2O3) were synthesized and characterized by scanning electron microscopy (SEM–EDS) and X-ray photoemission spectroscopy, respectively. Then, the flame retardant and smoke suppression properties of HGM-Fe2O3 in thermoplastic polyurethane (TPU) composites have been investigated intensively using several methods, including cone calorimeter test (CCT), smoke density test (SDT), scanning electron microscopy, and thermogravimetric analysis/infrared spectrometry. The CCT results showed that HGM-Fe2O3 can greatly enhance the flame retardance of polymer matrix materials compared with TPU. For example, HGM-Fe2O3 can reduce heat release rate, total heat release, and smoke release of TPU composites in the combustion process. The SDT results showed that HGM-Fe2O3 can effectively decrease the amount of smoke production in the test. Furthermore, the TG results indicate that HGM-Fe2O3 can decrease the initial decomposition temperature, and change the structure of char residue layer.

A new PPy/CoFe2O4/HGMs microwave absorbing composite particle with three-layer sandwich structure, comprising cobalt ferrite (CoFe2O4) and polypyrrole (PPy) coating on the surface of hollow glass microspheres (HGMs), was synthesized by the method of co-precipitation and in situ polymerization. The surface morphology, phase structure and chemical component of the composite had been characterized by scanning electron microscope and X-ray diffractometer. The results indicated HGMs were coated by CoFe2O4 completely and the obtained CoFe2O4/HGMs composites were warped by PPy. The conductivity and the saturation magnetization Ms of the resulting PPy/CoFe2O4/HGMs composites are 0.09 S/cm and 46 emu/g, respectively. The vector network analyzer showed the composite performed better microwave absorption ability than that of PPy and PPy/HGMs. The reflection loss of the composite with 2.58 mm thickness is more than−10 dB which means over 90 % microwave is absorbed in X-band (8.38–12.4 GHz). The ternary composite that has light weight, wide absorbing bandwidth, strong absorbing capacity and conductivity can be an attractive candidate in the field of microwave absorption.

Cu nanoparticles (CuNPs) were loaded on the surface of hollow glass microspheres (HGMs) by electroless plating technique. The surface morphology and composition of the plated HGMs were characterized by XRD, XPS and SEM. The results show that the size and distribution of the CuNPs varied with the different copper sulfate concentrations and played an important part in photocatalytic hydrogen production. When the concentration was 2 g/L, the hydrogen production reached 3845 μmol/g h with lactic acid as a sacrificial agent and exhibited great stability for at least 20 h, which is better than the freshly synthesized alone CuNPs (1500 μmol/g h). What’s more, the photocatalytic degradation rate of methyl orange reached up to 95.75 % after 2 h under light irradiation and the photocatalysts can be recycled for further use.

This paper describes a novel approach for preparation of scandium glass microspheres by combining both melt-quenching technique and an indigenously developed microwave approach. The microspheres were characterized for morphology, elemental composition, crystallinity and change in physical/chemical properties with temperature. The size of the prepared microspheres was found to be ranging from 500 to 1500 μm. The obtained glass microspheres were irradiated with thermal neutrons in a nuclear reactor to produce 46Sc radioisotope.

The effect of hollow glass microspheres with a density of 125 kg/m3 on the properties of low-density (54-90 kg/m3) rigid polyurethane foams is investigated. The thermal expansion coefficient of the foams and their properties in tension and compression in relation to the content of the microspheres (0.5-5 wt.%) are determined. An increase in the characteristics of the material in compression in the foam rise direction with increasing content of filler is revealed. The limiting content of the microspheres above which the mechanical characteristics of the filled foams begin to decrease is found. The distribution of the microspheres in elements of the cellular structure of the polyurethane foams is examined.

Sol–gel bioactive glasses have been developed for bone tissue regeneration and drug delivery systems as they have the unique mesoporous structure and high bioactivity in vitro. To develop more reliable drug delivery and bone tissue repair systems, it is necessary to control the morphology and microstructure of bioactive glasses. For this purpose, bioactive glass microspheres (BGMs) were prepared by a sol–gel co-template technology using acids as catalysts. We studied the effects of different acids (citric acid, lactic acid and acetic acid) on the microstructure and apatite-forming bioactivity of BGM. The apatite-forming bioactivity was carried out in simulated body fluid (SBF). The microstructure and apatite-forming bioactivity of BGMs were characterized by various methods. Results showed that acetic acid had little effect on the structure and bioactivity of BGMs. Differently, the morphology and microstructure of BGMs could be controlled by changing citric acid and lactic acid concentrations. In vitro bioactivity test indicated that citric acid and lactic acid derived BGMs possessed the better apatite-forming capacity than that derived by acetic acid.

A facile method to fabricate molecularly imprinted polymers (MIPs) on glass microspheres in a column was developed. The column was prepacked with glass microspheres, and then the prepolymerization mixture was injected into the interstitial volume of the column. The polymerization took place in situ and the column could be directly used for high-performance liquid chromatography after the template had been removed. The template consumption was reduced greatly because the prepolymerization mixture just filled the interstitial volume between the glass microspheres in the column. The MIPs obtained exhibited better kinetic properties, higher efficiency, and low back pressure of the column. Emodin imprinted polymers were prepared by this method and were used for solid-phase extraction.

The study aims at the manufacture and investigation of biodegradable glass microspheres incorporated with yttrium potentially useful for radionuclide therapy of cancer. The glass microspheres in the SiO2-Na2O-P2O5-CaO-K2O-MgO system containing yttrium were prepared by conventional melting and flame spheroidization. The behaviour of the yttrium silicate glass microspheres was investigated under in vitro conditions using simulated body fluid (SBF) and Tris buffer solution (TBS), for different periods of time, according to half-life time of the Y-90. The local structure of the glasses and the effect of yttrium on the biodegradability process were evaluated by Fourier Transform Infrared (FT-IR) spectroscopy and Back Scattered Electron Imaging of Scanning Electron Microscopy (BEI-SEM) equipped with Energy Dispersive X-ray (EDX) analysis. UV-VIS spectrometry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used for analyzing the release behaviour of silica and yttrium in the two used solutions. The results indicate that the addition of yttrium to a bioactive glass increases its structural stability which therefore, induced a different behaviour of the glasses in simulated body environments.

This article reports the chemical deposition of silver shells on the surface of hollow glass microspheres. This was accomplished by using titanium dioxide, derived from titanium (IV) tetra-n-butoxide, as the surface modifier. Two routes of formation of thin titanium dioxide layers on the substrate were compared in terms of composition and properties: photochemical approach and atmospheric hydrolysis. The structure and composition of the samples were characterized by atomic force microscopy, scanning electron microscopy, IR spectroscopy, electron paramagnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The resulting thickness of uniform silver shells on the surface of microspheres averaged out at 1.0–1.25 μm.

Epoxy resin composites are generally applied in moulds manufactured with rapid tooling technologies. These technologies are used for wax and polymer materials injection. Well-designed and well built mould is key to achieving excellent and consistent moulded products. For production, mould with excellent temperature control and cooling efficiency are necessary to produce economical and quality product. Various compositions for tooling materials based on epoxy and silicone (Amine-containing poly dimethyl siloxane — ACS) modified epoxies were prepared. They were cured using aliphatic amines. Aluminium and glass spheres (Spheriglass) were used as fillers in these compositions. The mechanical and thermal behaviour of these particulate composites were determined. Flexural, tensile and compressive tests were done on these materials. Thermal fatigue tests were also done. The dispersion of aluminium and glass spheres in silicone modified and unmodified epoxy matrix was studied by using scanning electron microscopy.

Bone morphogenetic proteins (BMPs) and 45S5 Bioglass® microspheres (bioactive GM) can increase the differentiation of osteoblasts. Recombinant human BMP-2 (rhBMP-2) is presently the BMP most frequently used in delivery systems and it has already been used in clinical bone healing studies. We have developed a delivery system that combines a collagen Type I gel, BMP and bioactive GM. Since BMP-9 seems to be more osteogenic than BMP-2, we compared the differentiation of MC3T3-E1 preosteoblasts induced by our delivery system containing either a peptide derived from BMP-9 (pBMP-9), or rhBMP-2, both at 100 ng/mL. After 5 days, alkaline phosphatase staining showed that pBMP-9 induced more differentiation than rhBMP-2 in all experimental conditions. Also, bioactive GM increased this BMP effect. Since preosteoblasts secreted matrix metalloproteinases (MMPs) that can degrade collagen, we then studied the influence of the delivery system on MMPs production. We observed that MMP-2 was the major MMP involved in all experimental conditions. In addition, pBMP-9 with bioactive GM generated less MMP-2 than did rhBMP-2 on days 3 and 5. Thus, a delivery system using collagen Type I gel with pBMP-9 and bioactive GM seems to be a promising system for bone regeneration.

A method for production of porous composites from pyrogenic silicas, whose surface is preliminarily modified with methyl and trimethyl siloxane groups, was developed. In order to diminish shrinkage, glass microspheres and organosilicon compounds were used as modifiers. The total porosity of the composites obtained was 0.28 – 0.55.

It was found that modification of the surface of nickel-plated hollow glass microspheres with N-oxide-Cl-alkyldimethylamine causes overcharging of their surface and as a result improves wetting of particles of the solid phase with acrylic latex water-emulsion paint. The conductive paint coatings are characterized by high electrical conductivity. The paint developed can be used to protect people and equipment from electromagnetic radiation.

The use of hollow glass microspheres in syntact foam plastics with organosilicon binders is described. The physicomechanical and thermophysical properties of the heat-insulating materials obtained are investigated.

The preparation of nylon-6/hollow glass microspheres composites by the RIM procedure, leading to a new material with reduced density and increased stiffness, is described. The shear moduli of these composites show a linear dependency on the filler concentration. By means of a modified Kerner equation the shear moduli of the various glass spheres were calculated. A linear dependency between the shear modulus of a glass sphere and its wall thickness is demonstrated. A direct method for the determination of the shear moduli of those glass spheres having a density lower than the matrix material is presented.

Hollow glass microspheres (HGS) for laser fusion targets were fabricated in the system Na2O-B2O3-SiO2 from NaOCH3, B(OCH3)3 and Si(OC2H5)4. Gel powders prepared from metal alkoxides and urea liberate H2O, CO2 and NH3 gases, evolution of which takes place completely at about 500° C. The precursor of HGS is formed by the encapsulation of these gas components in the glass layer formed at the surface of the powder. HGS are produced from the gel powders having both a melting temperature lower than about 1000° C and a viscosity at that temperature lower than 105 P. In the Na2O-B2O3-SiO2 system, the compositions from which HGS are produced are those containing 55–75 wt% SiO2 and 0–20 wt% B2O3. HGS ranging from 100–500μm diameter and 0.5–7.0μm wall thickness are obtained by change of urea content.

Synaptic vesicles from rat brain were immobilized on glass microspheres covalently coated with poly-L-lysine. Using a potassium tartrate perfusion medium, the vesicular accumulation and methamphetamine-induced release of (L)-3H-norephinephrine could be conveniently monitored in a flow experiment.

A buoyant solid-phase extraction adsorbent was prepared by sodium alginate-coated hollow glass microspheres (HGMs) modified with 3-aminopropyltrimethoxysilane (3-APTS) for the separation and enrichment of anionic dye amaranth. After adsorbing amaranth, these low-density adsorbents can float on the surface of the solution, so the separation between adsorbents and substrates can be carried out by flotation. Quantitative determination of amaranth after separation and enrichment can be achieved by combining spectrophotometry. Under the optimum conditions, the linear range and detection limit for amaranth detection were 0.02 mg L−1–2.0 mg L−1 and 0.0021 mg L−1, respectively. The proposed method was applied to the determination of amaranth in different beverages, and the results were in good agreement with those by high-performance liquid chromatography (HPLC). The recoveries of amaranth in different beverages were between 97.93 and 105.91%. The floating adsorbent can be used as a conventional sample preparation method for the detection of low concentration analytes in complex samples.

The high prevalence of lactose intolerance was observed in Asian population. Lactose-free milk is a beneficial product to ameliorate this disorder. A lactase immobilized catalytic system for lactose-free milk preparation was established in the present study. The results show that lactase was covalently immobilized on the glass microspheres exhibited a highly efficient catalytic manner (the immobilization yield is about 83.2%) over other three solid carriers (PAN beads, cellulose beads, and nylon pellets). Optimal conditions were determined to be at room temperature and pH 6.0 using O-nitrophenyl-D-galactopyranoside as an indicator. Scanning electron microscopy and electron spectroscopy for chemical analysis provided direct evidence that lactase was successfully immobilized on the glass microspheres. Operational reusability was confirmed for more than 10 batch reactions and the stability was capable of sustaining catalytic activity for 62 days (the relative activity is still around 60%). Flow rate of 60 mL/h in the packed lactase immobilized on glass microspheres reactor is the optimal condition for lactose-free milk preparation. Lactose within milk can be completely hydrolyzed in 33.3 min. These results provided a good indication for the procedure for lactose-free milk preparation in dairy industry.

The effect of filler type and mass percentage on the properties of low-density rigid polyurethane foams at a temperature of 77K was investigated. The mechanical properties of foams of density 55-90 kg/m3 filled with milled carbon fibers of average length of 100 and 60 μm and hollow glass microspheres of average diameter of 65 μm were compared. A considerable increase in the compressive elastic modulus in the foam rise direction with increasing filler content was observed. The compression strength of the foams in the parallel and perpendicular directions at the cryogenic temperature decreased upon introducing the milled carbon fibers of either type. The compression strength of the foams of density 90 kg/m3 somewhat increased only upon introducing the glass microspheres.

Hollow HAP microspheres in sub-millimeter size were prepared and investigated as a drug delivery vehicle. The LCB (lithium-calcium borate) glass microspheres, which were made through flame spray process, were chosen as precursor for hollow HAP microspheres. The LCB glass microspheres reacted with phosphate buffer (K2HPO4) solution for 5 days at 37 °C. During the reaction the Ca-P-OH compound precipitated on the surface of LCB glass microspheres and formed porous shells. Then the microspheres turned to be hollow ones with the same diameter as the glass microspheres after LCB glass run out in the chemical reaction. After heat-treated at 600 ° for 4 h, the Ca-P-OH compound became HAP, thus the hollow HAP microspheres were produced. The mechanism of forming hollow HAP microspheres through the chemical reaction between phosphate buffer and LCB glass was confirmed by the XRD analysis. The microstructure characteristics of the hollow, porous microspheres were observed by SEM.

A chemically durable glass microsphere containing a large amount of phosphorus is useful for in situ irradiation of cancers, since they can be activated to be a β-emitter with a half-life of 14.3 d by neutron bombardment. When the activated microspheres are injected to the tumors, they can irradiate the tumors directly with β-rays without irradiating neighboring normal tissues. In the present study, P+ ion was implanted into silica glass microspheres of 25 μm in average diameter at 50 keV with nominal doses of 2.5×1016 and 3.35×1016 cm−2. The glass microspheres were put into a stainless container and the container was continuously shaken during the ion implantation so that P+ ion was implanted into them uniformly. The implanted phosphorus was localized in deep regions of the glass microsphere with the maximum concentration at about 50 nm depth without distributing up to the surface even for a nominal dose of 3.35×1016 cm−2. Both samples released phosphorus and silicon into water at 95 °C for 7 d. On the basis of the previous study on P+-implanted silica glass plates, the silica glass microspheres containing more phosphorus which is desired for actual treatment could be obtained, without losing high chemical durability, if P+ ion would be implanted at higher energy than 50 keV to be localized in deeper region.

Para-aramid fiber reinforced composite are the premier choice for protective applications due to their superior mechanical properties. Use of thermoplastic matrices in such composites is gaining the interest of researchers due to their better energy absorption. Polyvinyl butyral (PVB), a thermoplastic matrix, has very good mechanical and impact properties. Many studies have reported in the literature on the characterization of mechanical performance of thermoset composites for impact applications, however, there is a need to study para-aramid (PA) thermoplastic composite produced with PVB as well as further improvement of their properties using particulate reinforcements. In the present work, prepreg were developed by impregnating PA woven fabrics with a slurry of PVB, with and without silica micro particles (SMP) and glass microspheres (GMS) ranging from 1–4 %. Composites were fabricated using compression molding. 3-point bending (flexural), Pendulum (Charpy) impact and drop weight impact testing of the composites were performed. The results showed that by the addition of SMP and GMS the impact properties were increases and GMS gives better results as compared to SMP. One-way ANOVA (Tukey) statistical analysis supports the experimental findings.

Yttrium aluminate glasses (76.8 mol% of Al2O3, 23.2 mol% of Y2O3) doped with Er3+ and Nd3+ ions at different concentration levels (0.25 mol%, 0.5 mol% and 0.75 mol% Er2O3/Nd2O3) were prepared by flame synthesis in the form of glass microspheres. The prepared samples were XRD amorphous, without presence of any crystalline phases in measured patterns. The two exothermic effects (~ 940, ~ 1010 °C), which can be assigned to the two steps of YAG crystallization, were observed in the DSC records of all prepared samples. The high temperature XRD measurements showed YAG (900–1200 °C) and α-Al2O3 (1300–1450 °C) phase crystallization. The emission spectra were measured in the VIS and NIR regions for Er-doped samples and in the NIR region for Nd-doped samples. All measured emission spectra contain of characteristic bands due to the typical 4f–4f transitions within the Er3+ and Nd3+ ions. Comparison of the measured intensities of Er-doped samples made it evident that the highest intensities were obtained for the 0.5 mol% Er2O3-doped sample (in both the NIR and VIS spectral regions). The maximum intensity for Nd-doped samples was found when the sample was doped with 0.75 mol% of Nd2O3. The slowly increasing of emission intensities in samples after 20 min annealing at 1000 °C and Stark splitting of emission bands in samples after 40 and 60 min annealing at 1000 °C and after 20, 40 and 60 min annealing at 1500 °C was observed.

Bimodal poly(methyl methacrylate) (PMMA) foams are produced with a new method combining syntactic foam production and supercritical CO2 (scCO2) foaming. Bimodal pore structure offers several potential advantages to foam properties, such as reduced mass density and excellent thermal and sound insulation properties. To produce the foams, first PMMA composites are produced with hollow glass microspheres (HGMs) and octatrimethylsiloxy polyhedral oligomeric silsesquioxane (POSS) nanoparticles using a twin screw extruder. The composite syntactic foams are then processed with scCO2 to form bimodal pore structured PMMA-HGM-POSS composite foams. In the foam matrix, large pores form due to the CO2 diffusion in the matrix towards the voids between the matrix and HGM surfaces, and small pores are formed at the nucleation cites. Highly CO2-philic POSS nanoparticles contribute to scCO2 foaming as cell nucleators enhancing the foaming performance of the syntactic composites. The effects of process pressure, time, and concentrations of HGMs and POSS nanoparticles on the foam morphology are studied. The highest decrease achieved in the foam density compared to that of the bulk polymer is 69% with only 12% decrease in the hardness.

The conditions for chemical precipitation of nickel on glass microspheres are determined. It is demonstrated that nickel-plated glass microspheres can be used as conducting fillers in paint-and-lacquer materials to produce coatings for effective protection from EMR in a frequency range of 0.15 – 1000 MHz.

In this study, rigid 4,4′-diglycidyl(3,3′,5,5′-tetramethylbiphenyl) epoxy(TMBP)-based composites were developed by the incorporation of varying percentages of commercial hollow glass microspheres(HGMs, QH-450) into the TMBP resin used for electronic packaging. The thermal and mechanical properties as well as the morphology of all the composites were characterized, and dielectric properties were characterized by advanced analytical techniques. The results reveal that a series of TMBP/QH-450 composites exhibits higher initial degradation tempera-tures(Td,5%>300 °C), and the residual char and glass transition temperature were clearly improved with QH-450 loading. In addition, all epoxy composites exhibited a lower dielectric constant ranging from 3.74 to 3.06 at 1.2 MHz because the lower dielectric properties of the inert gas used as the core of the QH-450 decreased molecule polarity. Hence, this developed TMBP/QH450 system demonstrates potential applications in electronic packaging.

Hollow glass microspheres (HGMs) offer advantages such as high chemical stability, light weight, and low cost and were firstly introduced to prepare functional polymer composites of multi-walled carbon nanotubes (MWCNTs) and poly(vinylidene fluoride). When preparing porous composites via hot compaction and selective etching, embedding of HGMs into the polymer matrix promotes the continuity of the conducting pathways in the material system and thus enhances electrical conductivity. Furthermore, HGMs play an important role in multiple scattering and reflecting the incident waves and the synergistic effect between HGMs and the MWCNTs conductive network greatly enhances the electromagnetic interference (EMI) shielding properties of the composites. In this paper, we show that with 10 wt% MWCNT loading, polymer composite samples containing only 2 wt% HGMs exhibit an average EMI shielding effectiveness (SE) of 43.03 dB over the frequency of 8.2–12.4 GHz. This SE value is higher than in samples with no HGMs (25.27 dB). Analysis of the measured scattering parameters reveals that microwave absorption is the primary reason for enhanced EMI SE. The introduction of HGMs also decreases the thermal conductivity of the composites by reducing the active surface area that promotes efficient heat transfer. With the addition of 2 wt% HGMs, the thermal conductivity of the composites reduces by 46.9%, from 0.305 to 0.162 W(mK)−1. This work provides a promising technique to prepare good-quality EMI shielding materials with lower thermal conductivity to meet the requirements of different applications.

Yttrium aluminate glasses with eutectic AY-E and near-eutectic composition AY-NE were prepared in the form of glass microspheres. Their basic characterization was carried out by XRD, optical microscopy and SEM. In DSC records of both samples, two exothermic peaks in temperature interval 940–1027 °C were observed. In both samples, YAG phase crystallized in two steps, as determined by HT XRD. DSC experiments conducted in the temperature interval 35–1200 °C at heating rates 2, 4, 6, 8 and 10 °C min−1 were performed, and the kinetic parameters of crystallization were determined with the use of the JMAK model. Crystallization in both samples was controlled by diffusion flow with linear nucleation rate time dependence. One-dimensional growth and formation of needle-like (dendritic) YAG crystals was observed in AY-E glass crystallized at 932 °C corresponding to the first exothermic maximum at the DSC curve. Two-dimensional growth and the presence of plate-like YAG crystals were observed in AY-NE glass crystallized at 996 °C. For the second exothermic effect, plate-like crystals crystallized at higher temperatures (996 and 1020 °C) in both compositions. The results of SEM analysis are in agreement with the results of kinetic calculations in the prepared systems.

The chemical activity with respect to alkali in cement (ASR resistance) for granulated aggregates (Penosital®, classic foam glass, microspheres of fly ash) in aqueous extract from concrete was investigated. The basic conditions for reaching ASR resistance of aggregates such as foam sital and microspheres of fly ash were determined.

The main objective of this study was to improve borehole wall stability in deep drilling into the Lonmenshan fault zone by developing a drilling fluid with ultra-fine inert materials. The mineral composition and microstructure of rock samples from deeper zones of the fault were analyzed by X-ray diffraction and scanning electron microscopy. It was found that the rock has a loose fabric and is microporous and highly permeable. The main clay minerals in the rock are illite and chlorite, which are prone to hydration and swelling. Under high pressures, their hydration and swelling capacity increase, which may cause instability of boreholes. Based on the obtained mineral composition and surface microstructure data and analysis of the mechanism of additive action, the following was found to be the optimum composition of the drilling fluid that helped rapid drilling into the fault zone: water + 5% sodium bentonite + 0.3% Na2CO3 + 5% sodium bentonite in the form of hollow glass microspheres (HGM) + 2% polysaccharide polymer + 3% carboxymethyl cellulose.

Hollow glass microspheres/barium ferrite (HGM/BaFe12O19) was first prepared via co-precipitation reaction, which was then performed to fabricate the HGM/BaFe12O19/Ag composites by chemical plating method. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM) were utilized to characterize the structures, morphologies and properties of the resultant composites. Results showed that a homogeneous and complete BaFe12O19 shell was coated on the surface of the HGM, and HGM/BaFe12O19 composites were also fully covered with Ag particles. The conductivity of the HGM/BaFe12O19/Ag composites was 1.24 × 102 S/cm, whereas the saturation magnetizations of the composites was reduced to 12.76 emu/g. The microwave absorption properties of the HGMs/BaFe12O19/Ag composites were significantly improved compared with those of HGMs/BaFe12O19 composites and BaFe12O19 particles. The reflection loss (R) showed that the bandwidth of reflection loss of HGM/BaFe12O19/Ag less than −10 dB (90% absorption) was 2.1 GHz (from 10.3 to 12.4 GHz), herein, the minimum loss value was −19.7 dB at 12.4 GHz.

Future space exploration missions beyond Earth's orbit, such as sample returns from Mars, will use ablative materials for the thermal protection system in order to shield the spacecraft from the severe heating during reentry. In this paper, we present the results of an elaborate test campaign on a lightweight carbon composite ablator with the aim of defining a procedure for material response characterization in a 1.2-MW inductively heated Plasmatron facility, suitable to reproduce the hypersonic flight boundary layer environment. Three different test gases were used, including air, nitrogen, and argon, at surface temperatures exceeding 3300 K. A comprehensive experimental setup was developed including a nonintrusive technique to measure surface recession by means of a high-speed camera. Surface degradation was strongly test gas dependent, while mass loss was mainly driven by in-depth decomposition of phenolic resin. Emission spectroscopy helped us identify C2 as a product of dissociating hydrocarbons, as well as cyanogen, suggesting surface nitridation. Melt flow at the surface and silicon emission indicated degradation of the glass microspheres used as additional filler. In air plasma, oxidation was inferred to be the main mechanism for ablation.

Two novel concepts for the design and manufacture of polymer supports for solid phase synthesis of peptides are described. The first concept involves the encapsulation of polymers within the hole of short pieces of capillary tubing often referred to as seed beads. This provides a rigid exo-skeleton for the support of soft polymer gel and other mechanically fragile polymer based matrices. The rigidity of the support provides a polymeric media that is particularly suited to continuous flow based peptide synthesis. The second concept complements this by providing an inexpensive approach to the preparation of spherical polymer particles by coating commercially available impervious hollow glass microspheres with polymer. The added advantage of this approach lies in the buoyancy of the resultant polymer particles, which facilitates handling on a large scale.

The preparation of hollow hydroxyapatite (HA) microspheres as potential drug-delivery vehicles was investigated. A lithium-calcium-borate (10Li(2)O-15CaO-75B(2)O(3)) (mol%) glass, made by fusing the components at 1100 degrees C for 1 h, was ground to a powder and passed through a flame at approximately 1400 degrees Celsius to spheroidize the particles. The resulting glass microspheres (106-125 microm in diameter) were reacted in 0.25 M K(2)HPO(4) solution for 5 days at 37 degrees Celsius and pH 10-12, resulting in the formation of porous, hollow microspheres of a calcium phosphate (Ca-P) material with external diameters similar to those of the original glass particles. Heat treatment at 600 degrees Celsius for 4 h partially converted the Ca-P material to HA, as confirmed by X-ray diffraction, and also increased the strength of the hollow microspheres.

The molecular composition of plasma-chemical silicon dioxide deposited onto the surface of glass microspheres, which are used in laser fusion experiments on an Iskra-5 facility, was studied by IR spectroscopy. It was found that stoichiometric silica containing organic impurities was deposited on substrates regardless of the glow-discharge working gas composition. The microphotographs of the surface of films deposited in various gas discharge atmospheres were obtained using a JCMA-733 instrument. All films were amorphous, as found by X-ray diffraction analysis.

An experimental study of static and dynamic fracture properties of a spheroplastic that has a matrix of polyester resin containing a filler of glass microspheres was conducted. Crack propagation was investigated under loading conditions generated by a pulse magnetic field. Microstructure features of dynamic fracture were analyzed.

Laser fusion research demands microsized hollow shells with a large diameter and a thick wall. Because these geometric parameters are difficult to provide by fabrication, the wall thickness was increased by deposition of a silicon dioxide film on the outer surface of glass microspheres. The film was obtained by decomposition of tetraethoxysilane vapor in a low-frequency discharge plasma in mixtures with argon and oxygen. The thickness of coating was shown to be a linear function of the deposition time and the consumption of the precursor organoelement compound. The composition of plasma-deposited layers was studied and their density and refractive index were determined. Elemental analysis data showed that the coating comprised silicon dioxide with carbon and hydrogen impurities.

In Argentina, at the Ezeiza Atomic Center,131I is produced by wet distillation of natural tellurium dioxide irradiated with thermal neutrons in a pool-type reactor. In order to recover the131I present in the production process of fission99Mo obtained by irradiation of UALx/Al targets (with 90% enriched uranium) a separation method was developed. Iodine isotopes can be separated from a sodium hydroxide solution containing fission products using a column filled with alternate beds of glass microspheres and porous metal silver. Tests with tracers were performed in radiochemical laboratory. Following this results, a series of tests with higher activities (3 TBq of99Mo and 0.7 TBq of131I) were carried out in hot cells. Molybdenum passes through the silver column, while131I retention was 92–97% in tracer test and 90% in optimised hot cell tests. This result depends on several facts that are discussed. An initial separation of iodine isotopes diminishes radiation damage on ion-exchange resin used in the subsequent molybdenum purification, improving its retention and elution yield.