Effects Of Such Additives Research Articles

Influence of low concentration MgCo 2(VO 4) 2 addition on microwave dielectric properties of Ba 0.6Sr 0.4TiO 3 ceramics

Ba 0.6Sr 0.4TiO 3− x MgCo 2(VO 4) 2 ceramics with x = 0, 0.5, 1.0, 2.0, and 5.0 wt% was fabricated via conventional solid-state reaction process. The effects of such additives on the structure, dielectric and tunability properties were systemically investigated. A small number of secondary phase identified as Ba 3(VO 4) 2 appeared in Ba 0.6Sr 0.4TiO 3− x MgCo 2(VO 4) 2 ceramics when x is more than 5.0 wt%. With increasing of MgCo 2(VO 4) 2 content, the peak values of permittivity gradually decreased and shifted to low temperature. The Ba 0.60Sr 0.40TiO 3 added with 0.5 wt% MgCo 2(VO 4) 2 possesses a dielectric constant of 2763, Q value of 267 at ∼1 GHz and tunability of 35.9% under dc electric field of 30 kV/cm at 10 kHz.

Study of Experimental Methods for Interface Problems Based on Virtual Testing

AbstractThe effective properties of fiber reinforced materials depend strongly on the properties of the interface between the phases. In the particular case of glass fiber reinforced thermoplastics, this bonding is inherently weak and needs to be improved, e.g., by addition of compatibilyzers. Reliable experimental setups are needed in order to investigate the effects of such additives on the interface properties. In this contribution, the sensitivity of push out experiments with respect to the microstructure and test setup are examined in order to find such an experimental configuration. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The Effects of Different Concentrations of Glycine and Cysteine on the Freezability of Moghani Ram Spermatozoa

Two experiments were designed to evaluate the effects of the amino acids glycine and cysteine on cryopreservation of ram spermatozoa. After primary evaluation of collected ejaculates, the semen samples were pooled and diluted 1:4 before cooling (experiment 1) and freezing (experiment 2) with Tris-Citrate-Fructose-Yolk (TCFY) extender supplemented with different concentrations of glycine and cysteine (5, 10, 15 and 20 mM). As the control, semen was diluted and frozen in the extender without amino acids. Motility, viability and membrane integrity were assessed as the parameters for semen quality in the first experiment. In the second experiment, motility, progressive motility, viability, membranes and acrosome integrity were evaluated after the freezing-thawing process. The results of the first experiment indicated that the addition of 10 and 15 mM cysteine compared to the control (basic) extender significantly increased (p0.05) between 5 mM glycine compared to 5 mM cysteine and between 20 mM glycine and 20 mM cysteine. The results of experiment 2 showed that the amino acids significantly improved post-thaw motility, progressive motility, viability, membranes and acrosome integrity of ram spermatozoa. These positive effects were observed at concentrations between 5 to 15 mM of glycine and cysteine, with the best results at 15 mM. Further increasing of amino acid concentrations significantly decreased the post-thaw characteristics of spermatozoa, but the results showed that cysteine was better than glycine and control extenders. The data indicated that addition of glycine or cysteine to the freezing extender can be recommended for cryopreservation of ram spermatozoa. However, further studies are still needed to determine the effect of such addition on fertility in farm animals.

Effect of In Addition on Wetting Properties of Sn-Zn-In/Cu Soldering

In this study, trace amounts (0.5–2 mass%) of indium (In) are added to the binary Sn-9Zn alloy to examine the effect of such addition on wetting properties of Sn-9Zn-In soldering. Results show that addition of In to Sn-9Zn alloy leads to decrease in eutectic temperature; and the greater the amount of In added, the larger the decrease is. On the other hand, the maximum wetting force, an indicator of wettability and solderability, increases with increasing mass% of In added. In addition, the higher the eutectic temperature, the better the wettability of solder is. Increasing In content in the solder also enhances the dissolution of Cu. Moreover, the higher the In content, the faster the dissolution rate is. At wetting temperatures of 220 � C and 240 � C, the wetting time achieved is shorter than 3 s, which can meet practical needs for industrial applications. In sum, the addition of 0.5 mass% of In is optimal in that it can achieve good wettability while maintaining low dissolution rate, which would also enhance solderability. [doi:10.2320/matertrans.MJ201004]

Nucleation, structure and lamellar morphology of isotactic polypropylene filled with polypropylene-grafted multiwalled carbon nanotubes

Polypropylene-based nanocomposites filled with polypropylene-grafted multiwalled carbon nanotubes (PP-g-MWNT) were compared to PP samples filled with pristine MWNT. The effect of such additives on the structure and morphology of the polymer matrix was studied by small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD), polarized light optical microscopy (PLOM) and differential scanning calorimetry (DSC). PP-g-MWNT allowed a more efficient and unhindered crystallization at a lamellar level, while MWNT disrupted the order of lamellar stacks, probably because of their tendency to aggregate. A common trend of tensile properties and lamellar morphology as a function of filler content was noted in the series filled with functionalized carbon nanotubes.

Effect of Food Additives on Hyperphosphatemia Among Patients With End-stage Renal Disease

High dietary phosphorus intake has deleterious consequences for renal patients and is possibly harmful for the general public as well. To prevent hyperphosphatemia, patients with end-stage renal disease limit their intake of foods that are naturally high in phosphorus. However, phosphorus-containing additives are increasingly being added to processed and fast foods. The effect of such additives on serum phosphorus levels is unclear. To determine the effect of limiting the intake of phosphorus-containing food additives on serum phosphorus levels among patients with end-stage renal disease. Cluster randomized controlled trial at 14 long-term hemodialysis facilities in northeast Ohio. Two hundred seventy-nine patients with elevated baseline serum phosphorus levels (>5.5 mg/dL) were recruited between May and October 2007. Two shifts at each of 12 large facilities and 1 shift at each of 2 small facilities were randomly assigned to an intervention or control group. Intervention participants (n=145) received education on avoiding foods with phosphorus additives when purchasing groceries or visiting fast food restaurants. Control participants (n=134) continued to receive usual care. Change in serum phosphorus level after 3 months. At baseline, there was no significant difference in serum phosphorus levels between the 2 groups. After 3 months, the decline in serum phosphorus levels was 0.6 mg/dL larger among intervention vs control participants (95% confidence interval, -1.0 to -0.1 mg/dL). Intervention participants also had statistically significant increases in reading ingredient lists (P<.001) and nutrition facts labels (P = .04) but no significant increase in food knowledge scores (P = .13). Educating end-stage renal disease patients to avoid phosphorus-containing food additives resulted in modest improvements in hyperphosphatemia. clinicaltrials.gov Identifier: NCT00583570.

Low sintering temperature of (Zn 0.65Mg 0.35)TiO 3– xCaTiO 3-based dielectric with controlled temperature coefficient

(Zn 0.65Mg 0.35)TiO 3– xCaTiO 3-based dielectric ceramics sintered at low temperature thanks to ZnO–B 2O 3 glass phase addition are investigated. The effects of such additions on the dilatometric curves, the microstructure, the phase composition and the dielectric properties have been carefully examined. It is shown that the sintering temperature is significantly lowered to 930 °C by the addition of 2 wt.% of ZnO–B 2O 3 glass phase. The temperature coefficient of permittivity ( τ ɛ) could be controlled by varying the CaTiO 3 content and lead to near zero τ ɛ value. As an optimal composition, (Zn 0.65Mg 0.35)TiO 3 + 7%CaTiO 3, co-sinterable with silver electrodes at 930 °C, exhibits at 1 MHz, a relative permittivity of ɛ r = 21, a temperature coefficient of the permittivity τ ɛ of −4 ppm/°C and low dielectric losses (tan( δ) < 10 −3). These interesting properties make this system promising to manufacture Ag-based electrodes multilayer dielectric devices.

Improvement of UO2 Pellet Properties by Controlling the Powder Morphology of Recycled U3O8 Powder

Powder morphology evolution of recycled U3O8 according to the thermal treatments has been studied. The defective UO2 pellets are oxidized to U3O8 powders at a conventional temperature of 350 or 450°C in air. Those powders are pressed into green pellets and then sintered at 1,500 and 1,730°C in H2 gas flow. Final reoxidized U3O8 powers are obtained by reoxidizing those sintered pellets at 450°C in air. This paper shows that the reoxidized U3O8 powder morphology and the BET surface areas are greatly dependent on the density of sintered UO2 pellets before reoxidation. Reoxidized U3O8 powders are added to virgin UO2 powders to fabricate UO2 pellets and the effect of such addition on the UO2 pellet properties is investigated. The reoxidized U3O8 powders having a certain range of BET surface area significantly promote the grain growth of UO2 pellets.

Effects of additives on hydrogen absorption and desorption characteristics of Nd(Fe,Mo) 12 alloys

Effects of such additives as Co, Zr, Nb or Ga on hydrogen absorption and desorption characteristics of Nd(Fe,Mo) 12 alloys are investigated. It is found that Zr or Nb addition increases the disproportionation temperature of Nd(Fe,Mo) 12 alloys, and Co or Ga addition decreases the recombined temperature of its disproportionated products. This shows that Zr or Nb addition retards the disproportionation, while Co or Ga addition is effective for improving the recombination, which is similar to the effects of the additives on the hydrogen absorption and desorption characteristics of Nd 2Fe 14B alloys. However, according to X-ray diffraction (XRD) investigations for the magnetic-oriented samples, the final hydrogenation disproportiontation desorption recombination (HDDR) NdFe 10.5− X M X Mo 1.5 (M=Co, Zr, Nb or Ga) products are isotropic. The effects of additives on hydrogen absorption and desorption characteristics of Nd 2Fe 14B and Nd(Fe,Mo) 12 alloys are very similar, but the magnetic anisotropy of the final two HDDR products are different. In order to investigate this, similarities and differences of the two alloy systems and their corresponding HDDR phenomena are further studied. The results show that the formation of anisotropic powders may be related to the disproportionated products and crystal growth direction of the Nd 2Fe 14B and Nd(Fe,Mo) 12 system.

Effect of alumina additions on the anode|electrolyte interface in solid oxide fuel cells

The longevity of a solid oxide fuel cell (SOFC) stack is curtailed by the fragility of its ceramic components. At Ceramic Fuel Cells Limited (CFCL), 15wt.% alumina is added to the commonly used 10mol% Y2O3–ZrO2 (YSZ) electrolyte to improve both the fracture toughness and grain-boundary conductivity of the electrolyte. This study investigates the effect of such addition of alumina on the anode|electrolyte interface; more specifically, which reactions occur with the Al2O3 at the interface and how these reactions influence fuel cell performance. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize the formation of NiAl2O4 in the alumina regions in the electrolyte. The NiAl2O4 is observed to grow into the adjacent grain boundaries to form an interconnected NiAl2O4 network up to 4μm deep into the electrolyte. Impedance spectroscopy shows that the formation of NiAl2O4 does not affect the grain bulk ionic conductivity. The grain-boundary conductivity is markedly reduced at low temperatures. However, at the high SOFC operating temperature at CFCL (850°C) the contribution of the grain-boundary conductivity to the total conductivity is diminished, and the NiAl2O4 is found not to have an effect on the total electrolyte conductivity and is deemed not to be a detrimental reaction.

Improvement of UO2 Pellet Properties by Controlling the Powder Morphology of Recycled U3O8 Powder

Powder morphology evolution of recycled U3O8 according to the thermal treatments has been studied. The defective UO2 pellets are oxidized to U3O8 powders at a conventional temperature of 350 or 450°C in air. Those powders are pressed into green pellets and then sintered at 1,500 and 1,730°C in H2 gas flow. Final reoxidized U3O8 powers are obtained by reoxidizing those sintered pellets at 450°C in air. This paper shows that the reoxidized U3O8 powder morphology and the BET surface areas are greatly dependent on the density of sintered UO2 pellets before reoxidation. Reoxidized U3O8 powders are added to virgin UO2 powders to fabricate UO2 pellets and the effect of such addition on the UO2 pellet properties is investigated. The reoxidized U3O8 powders having a certain range of BET surface area significantly promote the grain growth of UO2 pellets.

ZnTiO 3 ceramic sintered at low temperature with glass phase addition for LTCC applications

The compound ZnTiO 3 is an attractive dielectric ceramic owing to its good dielectric properties at high frequency range ( ɛ r = 21, tan( δ) < 10 −4, τ f ≅ −55 ppm/°C) and its relatively low sintering temperature (below 1200 °C). Nevertheless, it is well established that the synthesis of pure ZnTiO 3 phase is very difficult since ZnTiO 3 partially decomposes at high temperature into TiO 2 and Zn 2TiO 4. Consequently, sintered specimens usually contain these secondary phases. Another point which needs to be underlined is the lowering of the sintering temperature in order to be compatible with silver co-sintering. For that, the addition of glass phases from the system ZnO–SiO 2–B 2O 3 has been investigated. The effect of such additions on the dilatometric curves, the microstructure, the phase composition and the dielectric properties has been carefully examined. It was shown that the addition of 5 wt.% of (ZnO–B 2O 3) or (ZnO–SiO 2–B 2O 3) allows sintering ZnTiO 3 at 900 and 930 °C, respectively. In addition to the sintering temperature decreasing, it is clearly evidenced that some glass phases addition allows to suppress the secondary phases after the sintering stage. For example, starting from a powder containing ZnTiO 3 as majority phase and TiO 2 + Zn 3Ti 2O 8 as secondary phases, the addition of some glass phases allows getting a pure and dense ZnTiO 3 ceramic after a sintering performed at 900 °C. Typical samples sintered in such conditions exhibit a density higher than 94% of the theoretical value, a relative permittivity ɛ r = 21, a loss factor tan( δ) < 10 −3 and a temperature dependence of permittivity low with a value close to 30 ppm/°C. These properties make these compositions suitable for low temperature co-fired ceramics applications (LTCC).

Effects of some additives on wheat gluten solubility: A structural approach

The effects of KCl, NaCl and cysteine on the solubility in water of partially hydrolyzed gluten were studied at different pH values. As expected, solubility was shown to depend on solution pH. It decreased to reach a minimal value at the isoelectric pH (pH 6) and then it increased. In the presence of additives, the same behaviour was observed with an increase in solubilities values. In fact, an improvement of solubility of 28–30% was observed in the case of KCl and cysteine, while NaCl was much less efficient. The solubilisation effect of such additives was found to decrease with the initial concentration of wheat gluten. The structural investigation, by analysis of the amide I region of the infrared spectra of gluten samples, solubilised in the presence of additives, showed an increase in the proportion of β-turns and extended structures, accompanied by a decrease in the α-helix proportion. Such results confirm and explain the improvement of wheat gluten solubility by enhancing water–protein bonding and reducing protein–protein interactions. Structural changes result in a better accessibility of more water molecules to the protein and in greater hydration and solubilisation effects.

Synergistic effect of fly ash and blast furnace slag on the mechanical strength of traditional porcelain tiles

Fly ash and blast furnace slag, the by-products of Indian thermal power plant and steel plant, were gradually added to a traditional kaolin—quartz—feldspar based porcelain tile compositions singly and in combination by replacing a part of quartz and feldspar, respectively. The effects of such additions were studied by measuring the linear shrinkage, bulk density, water absorption and flexural strength of the samples heated in the temperature range of 1150–1200 °C. The results reveal that additions of both the by-products have beneficial effects towards mechanical strength. The strength improvement was mainly due to the presence of microcrystalline components such as mullite and quartz in fly ash and alkaline earth oxides in blast furnace slag. Slag containing compositions with or without fly ash vitrified at an early temperature (1175 °C) and achieved highest strength at this temperature compared to 1200 °C for normal and fly ash bearing compositions. Specific combinations of fly ash and slag in the ratio of 1:1 and 1:2 have shown the development of highest flexural strength (>70 MPa) at 1175 °C due to their lowest R 2O:R′O (R = K, Na and R′ = CaO, MgO) and moderately higher SiO 2:Al 2O 3 ratio. Beyond this temperature, the strength drastically reduced due to the formation of glassy phases at higher temperatures. XRD studies were also carried out to find out the differences in phase evolution due to addition of fly ash and blast furnace slag to traditional porcelain composition.

Effect of grain refining and Sr modification on Prefil measurement sensitivity in 356 alloys using electron probe microanalysis technique

To obtain the best possible Ai–Si alloy casting, the quality of the molten alloy must be optimised, i.e. the molten metal must be free of inclusions, impurities and dissolved gases during the casting process. The cleanliness of the molten metal can be monitored by means of various filtration techniques such as the Prefil (pressure filtration) technique used in the present study. Two melt treatment processes also generally applied to Al–Si alloys to improve the cast microstructure and alloy properties are grain refining and modification. However, the addition of grain refiners (in the form of Al–Ti–B master alloys) or modifiers (in the form of Al–Sr master alloys) to the melt can affect the behaviour of the inclusion measurement system. The present work was carried out on A356 alloys to study the effect of such additions when using the Prefil technique (additions of Ti, B or Sr can skew the Prefil filtration curve and make it less effective). The Prefil experiments were carried out using two types of ceramic filters: standard permeability (SP) filters with an average filter pore size of ~90 μm, and high permeability (HP) filters with an average filter pore size of ~130 μm. The results show that the Prefil curves obtained from the high permeability filters are more sensitive to the presence of oxides (film or particles) than the standard filters. The filtration rate is greatly affected by the amount of grain refiner added. Best results are obtained for the alloy without grain refiner addition. The filtration rate progressively decreases with increasing amount of grain refiner. When the total amount of boron added to the melt (through the Al–5Ti–1B grain refiner used) reaches 60 ppm, the filtration rate is approximately nil. In the case of strontium modification, a reasonably good correlation between the amount of Sr in the molten metal and the Prefil curve (or 'footprint') has been established. However, more experiments are still needed for a better understanding of the effect. Oxidation of Sr is possible, even for concentrations as low as 30 ppm. The SrO oxide particles (white, round shaped) are always seen to be associated with Al2O3 oxide particles (observed in the form of dark short rods). The curvature of the Prefil footprint is found to be sensitive to the amount of oxides present.

Scientific data and heightened public safety concerns to drive growth in flame retardants

The use of flame-retardant additives is expected to experience strong growth in the next five years. The anticipated growth is being attributed to two factors. Firstly, there will be a more scientific-based approach to evaluating the effects of such additives on the environment and secondly an increased global emphasis on public safety. Plastics Additives & Compounding reports on an assessment made by leading additive manufacturer Great Lakes Chemical Corporation.

Mechanical and thermal behaviour of cordierite–zirconia composites

Cordierite (Mg 2Al 4Si 5O 18) ceramics are susceptible of mechanical failure due to their low fracture toughness, which may hinder their application. Dispersion of ZrO 2 in cordierite to improve the mechanical properties has been extensively studied. However, little is known about the effect of such additions on both the sinterability and the mechanical properties of cordierite bodies fabricated from talc, kaolin and alumina mixes with additions of monoclinic ZrO 2, as most studies are concerned with additions of tetragonal ZrO 2 to cordierite powders. The present paper describes the in situ fabrication, the thermal and mechanical properties of sintered cordierite-based ceramic matrix composites containing dispersed particles of ZrO 2 obtained by mixing clay–talc–alumina mixtures with additions of monoclinic ZrO 2 up to 40 wt.%. The results obtained clearly demonstrate that the thermal expansion coefficient (CTE), elastic moduli ( E) and flexural strength ( σ r) were critically dependent on the mixing/milling conditions, the ZrO 2 content and the retained porosity.

Thermoelectric semiconductor iron disilicides produced by sintering elemental powders

Development of a sintering process to fabricate iron disilicides with a fine grain structure is pursued using elemental powders as starting materials with additions of Al. The Al additions are expected to involve liquid Al-rich phase during sintering to accelerate the reaction kinetics. At the same time, additions are made of Co and Cu, the former being an n-type dopant while the latter might promote metal-to-semiconductor transition upon annealing after sintering. The effects of such additions on the sintering kinetics, constituent phases in the products, and their thermoelectric properties are examined. It is shown that fabrication of sintered iron disilicides using elemental powders, heretofore believed to be difficult, becomes possible with Al additions. Then a mechanism of sintering in the Fe–Si–Al ternary system is proposed, and finally a series of demonstrations is given for the changes in thermoelectric properties depending upon the doping element used. It becomes evident that the thermoelectric figure of merit of the present materials is equivalent to that of the conventionally fabricated iron disilicides.

Improvement of potentiometric selectivity of ion-exchanger based membranes doped with co-exchanger: Origin of the effect

A novel equation is derived to describe the electric potential and selectivity of membranes which contain ion-exchanger and some co-exchanger. Numeric simulation of the potentials and that of concentrations of species in the membranes allows elucidation of the origin of the co-exchanger effect on potentiometric selectivity. It is shown that the elimination of the diffusion potential due to addition of co-exchanger is the main source of the beneficial effect of such additives. Another important feature of these membranes is the stabilization of the concentration of free ion-exchanging sites and their excess relative to ions. As a result, the potentiometric selectivity of membranes doped with co-exchanger becomes proportional to the association selectivity of ion-exchanging sites.

Effects of Enzymes and Oxidizing Agents on Shear Stress Relaxation of Wheat Flour Dough: Additions of Protease, Glucose Oxidase, Ascorbic Acid, and Potassium Bromate

ABSTRACTMeasuring shear stress relaxation with an established research rheometer after slowly applying large strain proved useful for characterizing the effects of different chemical and enzymatic additives. Baking tests done with and without added ascorbic acid indicated that the method can be used for predicting effects of such additives on breadbaking quality. The relaxation process for dough is discussed in terms of two flow processes, one occurring at short time periods and the other at longer time periods. The slowly applied large strain shear stress relaxation method provides information about stress relaxation behavior during the second flow process. The effects of two enzymes (protease and glucose oxidase) and two chemical additives (ascorbic acid and potassium bromate) were studied. The results are presented as the stress relaxation curve with the corresponding rate plot and the initial value of the stress. Addition of the oxidizing agents increased the second flow process times and decreased the relaxation rate during the second process. Protease shortened the second flow process times and increased the relaxation rate during the second process. Glucose oxidase separated the two flow processes by increasing the relaxation time of the second process and decreasing the relaxation time of the first process.