Breakdown of Evaporating Falling Films as a Function of Surface Tension Gradient

This study has found that liquid film breakdown in isopropanol, ethylene glycol, and water mixtures occurred only in systems with negative surface tension gradients. These systems were characterized by a decrease in local surface tension with a decrease in film thickness. Thus, the direction of surface tension gradient with respect to film thickness can be used as a criterion for predicting falling film breakdown in certain mixture systems.

Visual observations of an evaporating falling film gave insight into the mechanism of film breakdown. It appeared that a lateral surface shear force created by the surface tension gradient caused lateral expansion of valleys of the wavy film liquid film as it flowed over the heating surface. This valley expansion caused localized gradual thinning of the wavy film, so that the film thinned to an unstable thickness and broke down.     

Role of Ion Beam Irradiation and Annealing Effect on the Deposition of AlON Nanolayers by Using Plasma Focus Device

AlON nanolayers are synthesized on Al substrate by the irradiation of energetic nitrogen ions using plasma focusing. Samples are exposed to multiple （5, 10, 15, 20 and 25） focus shots. Ion energy and ion number density range from 80 keV to 1.4 MeV and 5.6×10^19 m^- 3 to 1.3×10^19 m ^-3, respectively. Moreover, the effect of continuous annealing （473 K and 523 K） on an AlN surface layer synthesized with 25 focus shots is also examined. The main features of the X-ray diffraction （XRD） patterns with increasing focus shots are： （i） variation in the crystallinity of AlN along （111）, （200） and （311） planes, （ii） increasing average crystallite size of AlN （111） plane, and （iii） stress relaxation observed in AlN （111） and （200） planes. The crystallinity of AlN surface layer is comparatively better at 473 K annealing temperature. A broadened diffraction peak related to an aluminium oxide phase showing weak crystallinity is observed for 15 focus shots while non-bounded oxides are present in all other deposited layers. Raman and Fourier transform infrared spectroscopy （FTIR） analysis confirm the presence of AlN and Al203 for the surface layer annealed at 473 K temperature. Raman analysis shows that the overlapping of AlN and Al2Oa results in the development of residual stresses. Scanning electron microscope （SEM） results demonstrate that the formation of rounded grains （range from 20 nm to 200 nm） and variations in their microstructures features depend on the increasing number of focus shots. Decomposition of larger clusters into smaller ones is observed.     

VAPOR OPERATED SOLAR PUMP

The choice of a water pumping system in remote areas depends on the type of energy available for power generation. In most of these areas where electricity and other sources of energy are not available or expensive to obtain, solar energy offers a cheap source of energy which can be utilized for operating water pumping systems. This paper describes a simple low technology vapor operated solar pump having minimum number of moving parts. The system is easy to manufacture and requires low maintenance. The performance of the system is experimentally investigated and the results obtained are presented and discussed.     

Thermal characteristics and corrosion behaviour of Mg–xZn alloys for biomedical applications

The thermal parameters of Mg–xZn cast alloys with 0·5–9 wt% Zn were evaluated by using computer aided cooling curve thermal analysis (CA–CCTA), whereas the corrosion behaviour was investigated by potentiodynamic polarization and immersion tests. Thermal analysis results revealed that the dendrite coherency temperature (T _DCP ) decreased from 642·2 to 600 °C with the addition of Zn from 0·5 to 9 wt%. The liquid fraction at coherency point ( ${f}_{ L}^{ DCP}$ ) increased by 72% when Zn was increased up to 9 wt%. MgZn intermetallic phase was observed in samples with <3 wt% Zn. At higher percentages of Zn, the Mg ₅₁Zn ₂₀ intermetallic phase was also detected in addition to α-Mg and MgZn by first derivative cooling curves under non-equilibrium solidification. All these phases were observed along the grain boundary when Zn was rejected from the solid/liquid interface and enriched in the triple conjunction of grain boundary. The grain size decreased from 185·2 to 71·5 μm when Zn content was increased. The addition of Zn content had a significant effect on the corrosion rate and the corresponding mechanisms. The corrosion rate decreased from 2·1 to 1·81 mmpy as Zn content increased from 0·5 to 3 wt%; afterwards, however, this value increased with further increase of Zn. Mg–3Zn also had the lowest degradation rate and highest corrosion resistance which can be fully utilized for biodegradable orthopedic applications.     

E-SPART Analysis of Poly (D,L-lactide-co-glycolide) Microspheres Formulated for Dry Powder Aerosols

ABSTRACT

Electrical-single particle aerodynamic relaxation time (E-SPART) analysis was studied as a tool in formulation screening of diy powders for use in aerosol delivery to the lung. The respirable fraction (RF) of drugs delivered by dry powder inhalers (DPIs) can be improved more effectively by using hydrophobic microspheres as carriers. Poly (D,L-lacttde-co-grycolide) microspheres (PLGA) prepared in die respirable size range (3-7 mm) were treated with poryamino acids and isopropanol in order to obtain particles of surface charge suitable for use in DPIs.

The powder formulations were evaluated for their degree of aggregation by cascade impaction following delivery by the Pfeifler® DPI. The IPA treated PLGA microspheres had a significantly higher RF (12.9%) as compared to the PL and PGA treated microspheres (3.3 and 2.4%, respectively), and untreated microspheres (3.8%). Results of electrostatic charge determined by E-SPART analysis suggested that die higher RF for the IPA formulation may be due to hs highly unipolar nature (+ 56.3 mC/g).     

The use of carbon dioxide in the processing and packaging of milk and dairy products: A review

The upswing in consumer demand for fresh and high quality preservative‐free foods has led to the development of modified atmosphere packaging (MAP). Increasingly, MAP is being used with high carbon dioxide (CO₂) concentration as well as CO₂/N₂ gas mixes. Modified atmosphere packaging or ‘gas flushing’ as it is also known is an increasingly popular technique used to extend the shelf life (both quality and safety) of a number of dairy products. Carbon dioxide is an active constituent of MAP, naturally present in freshly drawn raw milk. Addition of CO₂ to raw milk or flushing the package headspace has proved to be a simple and cost‐effective method, depending upon the initial microbiological quality of the food product. Carbon dioxide addition through MAP or direct injection as an economically affordable shelf life extension strategy is used commercially worldwide for some dairy products. The development of food packaging machines with integrated gas flushing capabilities and the supply of ‘food grade’ gases allow dairy foods manufacturers to enhance the quality of their products. This review presents a broad spectrum of current research and the current trends with respect to CO₂ as a natural microbial hurdle with special focus on its precise mechanism and its role in quality improvement of dairy products.     

EFFECTS OF ADDED WEIGHTING AGENT AND XANTHAN GUM ON STABILITY AND RHEOLOGICAL PROPERTIES OF BEVERAGE CLOUD EMULSIONS FORMULATED USING MODIFIED STARCH

Stability of beverage emulsion is measured by the rate at which the emulsion creams, flocculates or coalesces, and is generally dependent on rheology of water phase, difference in specific gravities of the two phases and droplet size/distribution of the emulsion. The effects of weighting agents (sucrose acetate isobutyrate and brominated vegetable oil) and xanthan gum on modified starch‐based emulsions were evaluated in this study. Emulsion was formed by addition of 9% coconut oil, in the presence or absence of weighting agents, into the water phase containing modified starch at 10, 12 or 14% without or with the addition of 0.3% xanthan gum. Stabilities of emulsions were evaluated both in the concentrated form used for storage and dilute form used in beverages. The addition of xanthan gum into the water phase decreased the flow behavior index (n) from 0.88 down to 0.31 and increased elastic modulus (G′) over 20 times at elevated frequency (ω = 50 rad/s) and elevated the stability of the emulsion. The xanthan gum‐added emulsion had smaller particle size and demonstrated 14 and 5 times slower phase separation compared to the emulsions without or with the addition of weighting agents, respectively. When the elastic modulus was larger than the viscous modulus (G′ > G″), the emulsions demonstrated greater stability. In dilute beverage solutions, creaming was observed in the absence of xanthan gum.     

Quality Assessment of Ground Beef Patties After Infrared Heat Processing in a Conveyorized Tube Broiler for Foodservice Use

Ground beef patties were prepared, by infrared broiling in a conveyorized broiler and compared with those cooked on a conventional gas broiler. Results showed that with the high temperatures and short cooking times possible with the infrared broiler, more servings per hour could be produced by this new method of preparation than with the standard gas broiler. Also, no significant difference in the percent shrinkage of the patties was found when the two methods of broiling were compared. Both of these conclusions were supported regardless of the degree of doneness. Finally, the only significant difference in sensory evaluation of the five attributes was found in appearance, where gas broiled patties were rated higher than the infrared broiled samples (p > 0.05).     

Association of Zinc with Soy Proteins as Affected by Heat and pH

The effect of heat on the chemical association of ⁶⁵Zn with proteins and of pH on the solubility of proteins, phytic acid, zinc, and their complex formation were studied in soybeans grown hydroponically and intrinsically labeled with ⁶⁵Zn. ⁶⁵Zn association with soy proteins was not affected by autoclaving. Zinc was not covalently associated with the major soy proteins, 11S and 7S. Protein, phytic acid and zinc content of the raw soyflour was determined at pH range 3.5–12 before and after dialysis. pH had only a slight effect on zinc solubility. Protein-zinc-phytate complex formation was maximum in the pH range 7.5–10.5.