Stabilised cocosoy beverage: physicochemical and sensory properties

Beverages formulated from extracts of blanched coconut meat and germinated soybean were compared for their proximate composition to achieve the recommendations for vegetable milks. The stability of cocosoy beverage treated with varying levels (0.2–1.0%, v/v) of a 20% gum acacia solution was determined visually and objectively after 5 days of quiescent refrigerated storage. Cocosoy beverage (50:50, v/v coconut milk to soy milk) had 3.51% protein, 3.53% fat and 5.17% carbohydrate. Similarly, it contained 13.0, 5.2, 14.7, 18.7, 0.5 and 0.3 g kg⁻¹ K, Na, Ca, Mg, Fe and P, respectively. Compared with whole coconut milk and reconstituted whole milk powder, cocosoy beverage had significantly higher total solid contents and viscosity but lower pH and buffer index. A total solids top to bottom (T/B) ratio and protein (T/B ratio) of 0.97 and 1.0, respectively, corresponding to a separation index of 1.0, was obtained in cocosoy beverage stabilised with 1.0% gum acacia. Cocosoy beverage stabilised with 1.0% (v/v) gum acacia was rated significantly higher for all the tested sensory attributes. Cocosoy beverage, similar to whole coconut milk, had high contents of glucose and sucrose, a moderate content of fructose, low content of raffinose and no trace of stachyose. Copyright © 2006 Society of Chemical Industry     

Synthesis of glass-ceramics in the Na2O/K2O-CaO-MgO-SiO2-P2O5-CaF2 system as candidate materials for dental applications

This study reports on the sintering behavior, crystallization process, and mechanical properties of novel glass-ceramics (CGs) produced by the glass powder compact consolidation method. Substitution of K₂O for Na₂O and MgO for CaO was attempted in the parent glasses belonging to Na₂O-CaO-MgO-SiO₂-P₂O₅-CaF₂ system. Glass powder compacts were heat treated at various temperatures between 700°C and 900°C, taking under consideration the glass transition (T_g) and the crystallization peak (T_p) temperatures, which were experimentally determined for each investigated glass by thermal analysis (dilatometry and differential scanning calorimetry). The experimental results showed that sintering always preceded crystallization, regardless of the type of substitution. In the case of MgO substitution for CaO, crystallization was advanced in the range of 800°C-850°C, resulting in the formation of an assembly of crystalline phases, such as diopside, fluorapatite, and wollastonite. The substitution of K₂O for Na₂O increased the activation energy for crystallization, shifting crystallization process to a high temperature region, with the formation of alpha-potassium magnesium silicate, instead of wollastonite. The GCs produced had values of 22-31 GPa regarding the modulus of elasticity, 5.0-6.1 GPa concerning the microhardness, and 1.4-1.9 MPa⋅m^0.5 as regard the fracture toughness, which are similar to those of the human jawbone.     

Three-stage autoignition of gasoline in an HCCI engine: An experimental and chemical kinetic modeling investigation

The alternative HCCI combustion mode presents a possible means for decreasing the pollution with respect to conventional gasoline or diesel engines, while maintaining the efficiency of a diesel engine or even increasing it. This paper investigates the possibility of using gasoline in an HCCI engine and analyzes the autoignition of gasoline in such an engine. The compression ratio that has been used is 13.5, keeping the inlet temperature at 70 °C, varying the equivalence ratio from 0.3 to 0.54, and the EGR (represented by N₂) ratio from 0 to 37 vol%. For comparison, a PRF95 and a surrogate containing 11 vol% n-heptane, 59 vol% iso-octane, and 30 vol% toluene are used. A previously validated kinetic surrogate mechanism is used to analyze the experiments and to yield possible explanations to kinetic phenomena. From this work, it seems quite possible to use the high octane-rated gasoline for autoignition purposes, even under lean inlet conditions. Furthermore, it appeared that gasoline and its surrogate, unlike PRF95, show a three-stage autoignition. Since the PRF95 does not contain toluene, it is suggested by the kinetic mechanism that the benzyl radical, issued from toluene, causes this so-defined “obstructed preignition” and delaying thereby the final ignition for gasoline and its surrogate. The results of the kinetic mechanism supporting this explanation are shown in this paper.     

Highly porous electrospun polyvinylidene fluoride (PVDF)-based carbon fiber

Porous poly(vinylidene fluoride) fibers were prepared by electrospinning from solutions in dimethylformamide, poly(ethylene oxide) (PEO) and water. The PVDF fiber mats were then converted into electrospun carbon fiber paper using a low temperature chemical stabilization treatment (“dehydrofluorination”) followed by carbonization at 1000 °C. The resulting self-supporting carbon fiber paper exhibits unusually high surface area, in excess of 380 m²/g as measured by the nitrogen adsorption method, and a hierarchical pore structure. The largest pores are formed by the interstices between fibers; intermediate-sized pores arise from liquid–liquid phase separation during electrospinning to form polymer-rich and solvent-rich domains within the fibers; the smallest pores form upon decomposition of the PEO during carbonization. The electrospun carbon paper performs well as an electrode for driving the redox chemistry of ferrocene/ferrocenium. This is attributed to the high surface area of the electrode and the ease of diffusion of the redox-active species within the porous structure. The ratio of the dehydrofluorination agent (1,8-diazabicyclo[5.4.0]undec-7-ene) to vinylidene fluoride during dehydrofluorination was found to be the key to retaining the as-spun pore morphology during carbonization. The structure and morphology were further characterized by Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, X-ray diffraction, and Raman spectroscopy.     

Application of asymmetric Si3N4 hollow fiber membrane for cross-flow microfiltration of oily waste water

The asymmetric morphology of silicon nitride (Si₃N₄) ceramic hollow fiber membrane with a selective spongiform outer layer was optimized by the air gap distance and the internal rate of coagulate for oil/water emulsion microfiltration. The effect of trans-membrane pressure (TMP), feed flow rate (FFR), and pH of the feeding emulsion on the separation performance were determined experimentally. Membrane fouling has increased by dissociation of oil droplets during filtration at high TMP and FFR values. Fouling phenomena were studied based on standard pore blocking model. The pH by affecting the surface charge of the Si₃N₄ hollow fibers and zeta potential of the feed emulsion has also been introduced as a prominent influential factor on separation efficiency. The highest values of permeate flux (390 Lm^?2h^-1) and oil rejection (95%) were recorded in alkaline pH. The fabricated Si₃N₄ ceramic membranes were completely recovered (≤99%) by simple thermal treatment at 400 °C.     

β-SiAlON ceramic membranes modified with SiO2 nanoparticles with high rejection rate in oil-water emulsion separation

Porous ceramic membranes with high mechanical strength are suitable for oil-water emulsion separation. Nonetheless, it is difficult to prepare ceramic membranes with a small pore size and a good antifouling ability. In this work, SiO₂ nanoparticles were used to modify β-SiAlON ceramic membranes, which were successfully utilized to remove small oil droplets from oil-water emulsion. The modified membranes displayed a narrow pore size (the average pore size decreased from 1.05?µm, in the unmodified membrane, to 0.65?µm), and gas and water fluxes which are suitable for oil-water separation. Oil rejection rate was always higher than 90% under various pressures (1.0–2.0?bar) and flow velocities (1.0?3.0?L?min^?1) tested, which is considerably higher (60%) than the rejection rate of the unmodified membrane (which was 39.8%). Moreover, the modified membranes exhibited a good antifouling ability, since flux declined by only 7.0% after three recoveries via a simple ultrasonic treatment, over a total running period of 10?h. Accordingly, the produced membranes can be qualified for further consideration in oily wastewater treatment.     

Microbial quality of “doubles” sold in Trinidad

A cross-sectional study was conducted to determine the prevalence and characteristics of Escherichia coli, Staphylococcus aureus, Bacillus spp. and Salmonella spp. in “bara”, “channa”, condiments/spices and ready-to-eat “doubles” sold by vendors in the St. George and Caroni counties of Trinidad. Of 196 samples of each of “bara”, “channa”, condiments/spices and ready-to-eat “doubles” examined, E. coli was detected in 0 (0.0%), 14 (7.1%), 96 (49.0%) and 67 (34.2%), respectively; Staphylococci were isolated from 104 (53.1%), 71 (36.2%), 129 (65.8%) and 123 (62.8%) samples, respectively; and Bacillus spp. were recovered from 22 (11.2%), 85 (43.4%), 100 (51.0%) and 88 (44.9%) samples, respectively. Salmonella spp. were not isolated from any sample. Of the 177 isolates of E. coli recovered from all sources, 9 (5.1%), 7 (4.0%) and 47 (26.6%) were mucoid, haemolytic and non-sorbitol fermenters (NSF), respectively, but none agglutinated with O157 antiserum. Of 427 staphylococcal isolates, 130 (30.4%) were confirmed as S. aureus of which 20 (15.4%) were haemolytic and 84 (64.6%) pigmented, while 17 (20.7%) of 82 strains of S. aureus tested produced enterotoxins. Ready-to-eat “doubles”, a popular food in Trinidad, therefore pose a potential health risk to consumers due to the high level of contamination with bacteria.     

Composites of bovine hydroxyapatite (BHA) and ZnO

Composites of calcinated bovine bone-derived hydroxyapatite (BHA), doped with 2.5, 5, and 10 wt.% ZnO were produced by sintering. Scanning electron microscopy (SEM) and X-ray diffraction analysis together with measurements of density, compressive strength, and Vickers microhardness were carried out in the sintered samples. The experimental results showed that the best mechanical properties were achieved in the samples with 5% addition of ZnO. The highest value of compression strength was achieved after sintering at 1200 °C (72 MPa) and of microhardness at 1300 °C (548 HV). Prolong heat treatment at 1300 °C results in vulnerable BHA–ZnO composites to over-firing effect.     

Effect of Schottky barrier alteration on the low-frequency noise ofInP-based HEMTs

For the first time the effect of increasing the Schottky barrier's Al content of InP-based InAlAs-InGaAs HEMTs from 48 to 60% on the low-frequency (LF) drain and gate current noise is investigated. It is shown that the LF gate current noise S_IG(f) for the 60% case decreases by almost three decades, while the LF drain current noise S _IDS(f) stays at the same level. From small coherence values, it can be concluded that drain and gate noise sources can be treated separately which facilitates the LF noise modeling of these HEMTs