Compatibility and Bone Bonding Efficiency of Gamma Irradiated Hench’s Bioglass

Silicon - This research focuses on investigating and characterizing the effects of gamma irradiation through successive doses on the bioactivity or bone bonding efficiency of samples from patented...     

Effect of sample’s length on flow properties of open-cell metal foam and pressure-drop correlations

Many applications require fluid flow through the open pores of metal foam. The foam is usually treated as a porous medium for which the Darcy law and the Hazen-Dupuit-Darcy (or Forchheimer) equation are used to describe the pressure drop, and for obtaining the two important flow properties, i.e., the permeability and the form drag coefficient. Little or no attention is paid to the length (or thickness) of the porous medium in the flow direction. This paper establishes a minimum length necessary for the foam to have length-independent (or bulk) permeability and form drag coefficient. This minimum length is obtained experimentally for various types of open-cell aluminum foam subjected to airflow in the Forchheimer regime. Below this thickness values of the two key flow properties are not constant, and they include entrance/exit effects, which may explain some of the discrepancies in the reported values in the literature. The Forchheimer equation was recast in two different manners, which resulted in new non-dimensional numbers- one representing the form drag and the other the viscous drag. These numbers correlated very well with the thickness of the porous medium. The obtained correlations allow for determining the pressure drop given only the velocity and the thickness of an aluminum foam sample.     

Effect of Zr–Al Co-Doping on Structure and Photocatalytic Performance of ZnO Photocatalyst

利用水热处理结合焙烧的方法分别制备了Zr、Al掺杂及Zr–Al共掺的ZnO光催化剂。研究了制备的光催化剂样品的相结构和光谱性能;以紫外光（λ=254nm）为光源,酸性橙Ⅱ为降解对象,进行光催化活性测试;考察了Zr、Al掺杂对ZnO光催化剂反应活性的影响。研究表明,制备的产物均为六方晶系纤锌矿结构的ZnO;Zr、Al掺杂及Zr–Al共掺的ZnO样品的光催化活性相对于纯ZnO均有较大程度的提高,而且Zr–Al共掺的ZnO的光催化性能明显优于单一掺杂的。Zr–Al共掺可以明显改善ZnO表面状态,使ZnO具有更丰富的表面羟基,同时可以抑制光生电子–空穴对的复合,从而有利于光催化活性和稳定性的提高。     

Effect of different TEAOH/DEA combinations on SAPO-34’s synthesis and catalytic performance

SAPO-34 molecular sieves were synthesized hydrothermally using different combinations of amine agents [i.e., tetraethyl ammonium hydroxide (TEAOH) and diethylamine (DEA)]. XRD indicated the good crystallinity directed by single or mixed template for CHA structure. The morphology of crystals from SEM photograph was shown to be cubic shape of typical SAPO-34, but distinct in crystal size, increasing from 0.3–0.8 to 3.1–9.1 μm with the amount of DEA in the gel. NH₃-TPD showed similar acid properties for SAPO-34 with TEAOH content from 1.0 to 0.1, but strong acidity synthesized with DEA only. ²⁹Si MAS NMR demonstrated that Si species in framework with single DEA existed in large size of silicon islands, whereas dispersed finely in siliceous islands of smaller size with remarkable Si (nAl, 4-nSi, 0 < n < 4) environments in the samples using mixed template. In the methanol conversion to olefins over different SAPO-34 catalysts, the sample prepared with the mixtures of 50%TEAOH and 50%DEA showed the longest lifetime and high selectivity to C₂⁼~C₃⁼.     

Young’s Modulus of Dry-pressed Ceramics: The Effect of the Binder

Measurements of Young’s modulus of green compacts prepared from spray-dried alumina powders containing two binders: polyvinyl alcohol or polyethylene glycol are reported. The variations of Young’s modulus with forming pressure are compared to those of mechanical strength and discussed in terms of glass transition temperature (T_g). When the T_g of the polymer is lower than the pressing temperature (case of PEG and moisture-plasticized PVA), the variation of the Young’s modulus is related to the evolution of the binder film covering the surface of primary particles inside the granules. Microcracking of the brittle external polymer-rich layer of granules seems to be responsible for a different evolution of Young’s modulus of green compact in the case of a binder with a T_g higher than the forming temperature (dry PVA).     

Inward and Outward Diffusion of Modifying Ions and its Impact on the Properties of Glasses and Glass–Ceramics

In this paper, we review our recent findings about both the cationic inward and outward diffusion processes in glasses and glass–ceramics caused by redox reactions. We provide new insights into these findings by mapping the diffusion depth, the thermal reduction temperature, and time in a three dimensional diagram and by looking into the correlation among the glass composition, structure, topology, and the diffusion process in the polyvalent elements containing glasses. We illustrate the link between glassy dynamics (via the liquid fragility index m) and activation energy of diffusion. Furthermore, the inward diffusion approach is used to study percolation phenomena in glass–ceramics. Finally, we show that the diffusion approaches are potential tools for tailoring the surface performances of bulk glasses and glass fibers.     

Influence of the blast furnace’s operating conditions and coke quality on the life of air tuyeres

The influence of the coke characteristics and blast-furnace conditions on the durability of air tuyeres is considered.     

Effect of Fluorine Ion on the Electrical Properties of Glasses in the Na2O–P2O5 System

The temperature–concentration dependence of the electrical conductivity of glasses in the NaPO₃–NaF system has been investigated. The regularities revealed are interpreted from the standpoint of the structural microinhomogeneity of glasses, which is due to the formation of polar structural units of the Na⁺[O^–POO_2/2], Na₂ ⁺[O^– ₂POO_1/2], Na⁺[F^–POO_2/2], and Na⁺F^– types. It is shown that the concentration dependence of the electrical conductivity is governed by the ratio between the concentrations of these structural units.     

Effect of the Additive Fire Retardants on the Properties of Rigid Polyurethane Foams,Obtained Using Hydroxyethyl Derivatives of Oxamide and Polymeric 4,4′-diphenylmethane Diisocyanate

The present work investigates the effect of polyol structure and physical addition of boric acid and N,N′-bis(2-hydroxyethyl)oxamide on the properties of rigid polyurethane foams. The product of hydroxyalkylation of oxamide by ethylene carbonate has been used as a polyol component. The new polyol has been foamed using polymeric 4,4′-diphenylmethane diisocyanate, water, and triethylamine. To decrease the flammability of the foams, boric acid, and N,N′-bis(2-hydroxyethyl)oxamide were used as the additive flame retardants. It has been found, that chemical modification of the foam structure by means of oxamide groups decreases their flammability only to a small extent, whereas physical addition of N,N′-bis(2-hydroxyethyl)oxamide does not influence the flammability. However, the addition of boric acid to the foam composition resulted in a distinct decrease of foam flammability, according to the amount of boric acid added. All the foams, modified and nonmodified by boron, have been categorized into flammability class HF-1, according to the applicable standard. The introduction of flame retardants had its impact on the properties of polyurethane foams obtained, as described in this work.     

Effect of boron trioxide on coke’s inner carbon solution loss reaction

Boron Trioxide (B₂O₃) was adsorbed on coke through boric acid (H₃BO₃) solution, of which the concentration was 0.1%, 0.5%, 1.0%, 2.0% respectively. The existence form and distribution of boron (B) adsorbed on coke were characterized by X-Ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Inductive coupled plasma (ICP), effect of B₂O₃ adsorbed on coke was investigated by carbon solution loss reaction (CSLR) under the condition of the same weight loss. Results show that: H₃BO₃ changes into B₂O₃ after adsorption treatment, and is adsorbed on coke success-fully; B₂O₃ exhibits negative effect on coke CSLR; with the solution concentration increases, the negative effect is strengthened, and coke’s inner reactivity becomes severer, which is not beneficial for coke strength.     

Effect of annealing process on the growth and surface properties of Au–ZnO nanowire films grown by chemical routes

Au–ZnO nanowire films have been synthesized by chemical routes, electrochemical deposition (ECD) and chemical bath deposition (CBD) techniques, on zinc foil followed by annealing in air at 400 °C. X-ray diffraction patterns reveal formation of the ZnO wurtzite structure along with binary phases Au₃Zn and AuZn₃. Scanning electron microscopy shows the presence of ZnO nanowires having several micrometers in length and less than 120 nm in diameter synthesized by ECD and in the range of 70–400 nm using the CBD technique. During the annealing process, different surface morphologies originating from different catalytic effects of Au atoms/layers were observed. In addition, the effect of synthesis routes on crystalline quality and optical properties were studied by Raman and photoluminescence spectrometers indicating varying concentration of defects on the films. The Raman results indicate that Au–ZnO nanowire film prepared by chemical bath deposition route had better crystalline quality.     

Synergistic Effect of Distillers’ Grains and Petroleum Coke as Reducing Agent on the Carbothermic Reduction of Silica

Silicon - Petroleum coke (PC) has a low reactivity and is easy to graphitize at high temperatures, especially for petroleum coke as carbon reductive agent applied in the carbothermic reduction of...     

Glass Formation and Properties of Glasses in the PbO–ZnO–B2O3System

Glasses in the PbO–ZnO–B₂O₃system with a lead oxide content of less than 65 mol % are studied. The glass formation region for these glasses is determined. Their crystallization ability, density, and moisture resistance and the thermal, optical, and electrical properties are investigated. The composition–property curves are constructed. It is found that these dependences exhibit anomalies for glasses along the composition joins with constant boron oxide contents of 40 and 50 mol %. These anomalies can be associated with the change in the role of lead ions in the glass structure.     

Studies of Bone-Bonding Ability and Antibacterial Properties of Ag<Superscript>+</Superscript>, Cu<Superscript>2+</Superscript> or Zn<Superscript>2+</Superscript> ions Doping within Hench’s Bioglass and Glass-Ceramic Derivatives

Derived Hench’s bioglasses with specific ionic dopants Ag⁺, Cu²⁺, or Zn²⁺ have been prepared. The bone-boding ability or bioactivity behavior for the prepared glasses and their glass-ceramic derivatives has been investigated after immersion in phosphate solution for two weeks. Collective Fourier transform infrared absorption spectra (FTIR) and scanning electron microscopic (SEM) studies were conducted in order to study the in-vitro bioactivity behavior. X-ray diffraction (XRD) analysis was carried out to identify the crystallized phases upon thermal heat treatment through a two-step regime. The glasses and their glass-ceramic derivatives were tested to study their antibacterial or antifungal efficiency responding to the doped metal ions. FTIR spectra revealed the generation of two split peaks at about 560 and 605 cm^?1, after immersion in (0.2 M) sodium phosphate solution (Na₃PO₄), signifying the formation of a crystalline calcium phosphate phase, leading to hydroxyapatite formation. SEM examinations show characteristic rounded or nodular microcrystals for hydroxyapatite which support the FTIR data. X-ray diffraction analysis indicated crystallization of the main soda-lime silicate phase (1Na₂O.2CaO.3SiO₂) besides a secondary silicon phosphate phase (SiO₂.P₂O₅) in the studied glass ceramics. The route of crystallization is discussed on the basis of the presence of 6% P₂O_5; which facilitates the formation of phase separation and voluminous bulk crystallization of the main soda-lime silicate phase. The introduction of dopants is identified to cause no changes in the precipitated phases, with only minor changes in the percent of the crystalline phases. Experimental data indicate that the glass-ceramic samples are effective in bioactivity and antimicrobial efficiency.     

Effect of Structural Promoters on Fe-Based Fischer–Tropsch Synthesis of Biomass Derived Syngas

Biomass gasification and subsequent conversion of this syngas to liquid hydrocarbons using Fischer–Tropsch (F–T) synthesis is a promising source of hydrocarbon fuels. However, biomass-derived syngas is different from syngas obtained from other sources such as steam reforming of methane. Specifically the H₂/CO ratio is less than 1/1 and the CO₂ concentrations are somewhat higher. Here, we report the use of Fe-based F–T catalysts for the conversion of syngas produced by the air-blown, atmospheric pressure gasification of southern pine wood chips. The syngas from the gasification step is compressed and cleaned in a series of sorbents to produce the following feed to the F–T step: 2.78 % CH₄, 11 % CO₂, 15.4 % H₂, 21.3 % CO, and balance N₂. The relatively high level of CO₂ suggests the need to use catalysts that are active for CO₂ hydrogenation as well is resistant to oxidation in presence of high levels of CO₂. The work reported here focuses on the effect of these different structural promoters on iron-based F–T catalysts with the general formulas 100Fe/5Cu/4K/15Si, 100Fe/5Cu/4K/15Al and 100Fe/5Cu/4K/15Zn. Although the effect of Si, Al or Zn on iron-based F–T catalysts has been examined previously for CO+CO₂ hydrogenation, we have found no direct comparison of these three structural promoters, nor any studies of these promoters for a syngas produced from biomass. Results show that catalysts promoted with Zn and Al have a higher extent of reduction and carburization in CO and higher amount of carbides and CO adsorption as compared to Fe/Cu/K/Si. This resulted in higher activity and selectivity to C₅+ hydrocarbons than the catalyst promoted with silica.     

Effect of the Nature of the Binder on the Formation Temperature of Glass-Ceramic Coatings Based on Si–B–ZrB<Subscript>2</Subscript> for Graphite Protection

This work is devoted to fabricating and studying the properties of coatings based on the Si–B–ZrB₂ systems used in graphite protection. The kinetics of the oxidation of graphite with coatings at different temperatures in air are investigated. The optimal conditions for the thermal treatment of the material with the coating are suggested.     

Effect of γ-radiation on the structure and thermal properties of polyacrylonitrile fibres

-Radiation significantly affects both the initial structure and the thermal properties of PAN fibres. The following are probably the most important results of radiation exposure: the temperature of the beginning of cyclization decreases; the exothermic nature of cyclization decreases so that the weight losses in the region of the m.p. decrease, indicating destructive processes in the polymer chain; when irradiated samples are heated, intermolecular cross-links form with the participation of oxygen; the duration of oxidation of the fibres before a given density level is attained is reduced significantly.St. Petersburg University of Design and Technology. Translated from Khimicheskie Volokna, No. 3, pp. 18–21, May–June, 1995.     

Effect of γ-radiation on the structure and mechanical properties of polycaproamide fibres

Not only the tensile characteristics but also the character of the P(ε) and ε(T)curves change in γ-irradiation of PCA fibres. Irradiation in a forevacuum causes fewer changes in the structure and mechanical properties of PCA fibres than irradiation in air. In irradiation of PCA fibres in air, a shrinkage stage is detected, replaced by a stage of spontaneous lengthening as the absorbed dose increases. In the case of irradiation in a forevacuum (in the dose range studied), only the shrinkage stage is observed. The shrinkage stage is characterized by slight disordering of the structure of the polymer and an increase in the angle of disorientation of crystallites. Recrystallization processes activated by the radiation and to a great degree due to an increase in the molecular mobility because of fragmentation of transfer chains take place in the spontaneous lengthening stage. Translated from Khimicheskie Volokna, No. 2, pp. 47–50, March–April, 1998.