Compositionally controlled rhombohedral to cubic phase transition in CsTe2−xWxO6 related to pyrochlore structure

CsTe₂O₆ adopts a rhombohedrally distorted pyrochlore related structure due to the 1:3 ordering of Te⁴⁺ and Te⁶⁺ in the octahedral sites respectively. Phases of the type CsTe_2−xW_xO₆ were found to have the cubic pyrochlore structure from x = 0.2 to 0.5. These phases all contain Te⁴⁺ and Te⁶⁺ (mixed with W⁶⁺) and are disordered in octahedral sites of the pyrochlore structure. This mixed valence situation results in strong optical absorption in the visible region of the spectrum but does not produce a measurable electrical conductivity.     

Tensile and moisture barrier properties of whey protein–beeswax layered composite films

BACKGROUND: There is a lack of research on producing layered protein–lipid composite films with improved tensile and barrier properties compared to films from individual components. Several film‐forming parameters were hypothesized to influence the extent to which lipids were either dispersed within or layered upon whey protein films. Film‐forming parameters investigated were ratio of whey protein isolate (WPI) to beeswax (BW), homogenization method, sodium chloride (NaCl) concentration, and BW particle size. RESULTS: Film percent elongation (E) increased, while tensile strength (TS) and elastic modulus (EM) decreased when BW was incorporated into WPI films, demonstrating a lubricant effect of the BW. Mean water vapor permeability values for WPI film decreased by 57% when the film composition was modified by the addition of 40% BW. BW phase separation was observed in all of the tested films. Particle size of BW in the film‐forming emulsions was larger in the presence of NaCl (100 mmol L^?1), indicating a neutralization of particle charge. However, the addition of NaCl did not improve the moisture barrier of WPI‐BW film over the range of film‐forming conditions used in the study. CONCLUSION: The results from this study are useful in determining formulations and conditions for the production of composite films from WPI and BW with improved tensile and moisture barrier properties. Copyright © 2008 Society of Chemical Industry     

Properties of konjac glucomannan–whey protein isolate blend films

Edible composite packaging has been developed by blending biocomponents for specific applications, aiming to take advantage of complementary functional properties or to overcome their respective flaws. The aim of this work was to study the effect of incorporation of whey protein isolate (WPI) on the properties of konjac glucomannan (KGM) based films. Five aqueous solutions of KGM and/or WPI were prepared by casting and solvent evaporation of 1:0, 0.8:3.4, 0.6:3.6, 0.4:3.8 and 0:4.2 g KGM:g WPI/100 g solution. Glycerol (Gly) was used as a plasticizer at 1.5 and 1.8 g/100 g solution. The result showed that incorporated WPI proportionally increased transparency of KGM-based films. An increase in proportion of WPI resulted in decreased tensile strength and elastic modulus as well as improved flexibility. The incorporation of WPI into the KGM matrix led to an increase in water insolubility which enhanced product integrity and water resistance. Nevertheless, WPI did not improve water vapor barrier of KGM–WPI films. WPI and blend film with the highest concentration of WPI could be heat sealed at 175 °C. Overall, the range of Gly in this study did not apparently affect properties of the films.     

Synthesis, magnetic and thermoelectric properties of Rh2MO6 (M = Mo, Te, and W) with rutile-related structure

The Rh₂MO₆ compounds with M = Mo, W and Te were synthesized by solid state reaction. The compounds all crystallize in a rutile-type structure. These compounds would be expected to be diamagnetic insulators if the oxidation states were Rh³⁺ and M⁶⁺. In fact, all show relatively high electronic conductivities with Rh₂TeO₆ showing the highest electronic conductivity of ∼500 S/cm at room temperature. Measurable magnetic moments also indicate valence degeneracy between Rh and the M cation. The measured Seebeck coefficients are relatively low and positive indicating hole-type conduction.     

Synthesis,characterization, and dielectric properties of Y2NiMnO6 ceramics prepared by a simple thermal decomposition route

In attempt to search for an improved material preparation technique, Y₂NiMnO₆ dielectric material is prepared by a one-step thermal decomposition route where a solution of stoichiometric mixtures of metal acetates is directly heated. Structural characterization by X-ray diffraction and electron diffraction shows that the samples were successfully prepared at relatively low temperature comparing to a standard solid state synthesis. Results from several techniques including thermal analysis, electron microscopy, and X-ray absorption are used to investigate compound formation. It is revealed that metal acetates decompose at 300–350 °C resulting in mixture of several metal oxide intermediates which continue to react to form the desired product. Y₂NiMnO₆ nanoparticles are first obtained at 800 °C. Later, these nanoparticles agglomerate and grow at higher temperature and/or longer heating time to give larger particle size and more crystallinity. Although the starting reagent contains Mn in 2+ oxidation state, X-ray absorption near edge structure analysis indicates that the obtained Y₂NiMnO₆ contain Mn and Ni in 4+/3+ and 2+ oxidation states, respectively. Ceramic sample shows large dielectric constant of about 6,000–7,000 at 30–120 °C at 1 kHz. Dielectric constant and dielectric response of the sample are consistent with those reported in other works where different synthetic techniques were used. The activation energy of dielectric relaxation is similar to the energy required to transfer electrons between Ni²⁺ and Mn⁴⁺, thus the observed large dielectric constant is intrinsically related to electronic ferroelectricity due to charge ordering of Ni²⁺ and Mn⁴⁺.     

Barrier and tensile properties of whey protein–candelilla wax film/sheet

Barrier and tensile properties were compared for whey protein isolate- (WPI-) based solution-cast films, extruded sheets and extruded sheets subsequently thinned into films by compression. Solution-cast films were made from mixtures of WPI and glycerol (GLY) in water. Sheets were made by feeding WPI, GLY, and water to a twin-screw co-rotating extruder. In each case, candelilla wax (CAN) was added at 0, 5 or 7.5 g CAN/100 g dry mix to determine the effect on the barrier and tensile properties. Compressed extruded films were made by thinning extruded sheets using a Carver Press equipped with heated platens. Water vapor permeability (WVP), oxygen permeability (OP) and tensile properties were measured. Scanning electron microscopy (SEM) images were also taken.     

Active and intelligent packaging: The indication of quality and safety

The food industry has been under growing pressure to feed an exponentially increasing world population and challenged to meet rigorous food safety law and regulation. The plethora of media consumption has provoked consumer demand for safe, sustainable, organic, and wholesome products with “clean” labels. The application of active and intelligent packaging has been commercially adopted by food and pharmaceutical industries as a solution for the future for extending shelf life and simplifying production processes; facilitating complex distribution logistics; reducing, if not eliminating the need for preservatives in food formulations; enabling restricted food packaging applications; providing convenience, improving quality, variety and marketing features; as well as providing essential information to ensure consumer safety. This chapter reviews innovations of active and intelligent packaging which advance packaging technology through both scavenging and releasing systems for shelf life extension, and through diagnostic and identification systems for communicating quality, tracking and brand protection.     

Whey protein-okra polysaccharide fraction blend edible films: tensile properties, water vapor permeability and oxygen permeability

BACKGROUND: A hot‐buffer‐soluble‐solid fraction (HBSS) and an alkaline‐soluble‐solid fraction (ASS) of okra polysaccharides (OKP) were obtained using sequential extraction. These fractions were combined with whey protein isolate (WPI) and glycerol (Gly) plasticizer to form blend edible films. Effects of OKP fraction and content on tensile properties, water vapor permeability (WVP) and oxygen permeability (OP) were determined. RESULTS: HBSS film had significantly higher percent elongation (%E) and lower elastic modulus (EM), WVP and OP than ASS film. Increasing HBSS or ASS content in blend films with WPI significantly reduced film tensile strength and EM and increased film %E and WVP. OP values for WPI–HBSS blend films were significantly lower than OP for WPI or HBSS film. WPI–HBSS and WPI–ASS blend films had lower WVP and OP than WPI films with equivalent tensile properties. CONCLUSIONS: WPI–HBSS blend films have higher WVP and lower OP than WPI film or HBSS film, indicating unique interactions between WPI and HBSS. Compared to WPI film, WPI–HBSS blend films have improved flexibility, stretchability and oxygen barrier. Different HBSS and ASS compositions and structures are responsible for property differences between HBSS and ASS films and between WPI–HBSS and WPI–ASS blend films. Copyright © 2010 Society of Chemical Industry     

Single crystal growth and structure refinements of CsMxTe2−xO6 (M = Al, Ga, Ge, In) pyrochlores

Single crystals of CsM_xTe_2−xO₆ pyrochlores with M = Al, Ga, Ge, and In have been grown from a TeO₂ flux. Structure refinements from single crystal X-ray diffraction data are reported. These results are used to discuss deviations from ideal stoichiometry that result in electronic conductivity presumably related to mixed valency of tellurium.