Type Of Wall Material Research Articles

Effect of nanotextured array of conical features on explosive boiling over a flat substrate: A nonequilibrium molecular dynamics study

Nonequilibrium molecular dynamics simulations were performed to investigate the effects of size of nanocone array and types of wall material, i.e., aluminum and silver, on the explosive boiling of ultra-thin liquid argon film on nanostructure. An Embedded Atom Method (EAM) potential is used in describing the interatomic interaction between metal atoms. The results showed that the cone-like nanostructures drastically enhance heat transfer from solid to liquid and they have significant effects on temperature and pressure histories, net evaporation number, as well as the density distribution in the system. In all cases studied, the liquid molecules above the solid surface go into explosive boiling and a cluster of liquid is observed to move upward. It was also observed that the separation temperature associated with separation of liquid film from solid surface strongly depends on size of nanostructure while it is not sensitive to the type of materials. Furthermore, in all cases in a specific time after beginning of boiling, the evaporation on the hot wall stopped and a non-evaporating layer will form on the surface.

Study on Building Engineering with Simulation and Analysis of Outdoor Thermal Environment for a Residential Subdistrict in Hot Summer/Cold Winter Region

Thermal environmental problems in urban high-rise buildings are prevalent. To analyze the phenomenon, the thermal environment of a typical urban residential subdistrict is simulated by using CFD techniques considering the affects of different type of wall material. The simulation data are carefully analyzed. Some useful results are thus obtained. The direction of the buildings affects air circulation greatly with the north-south orientation having the best effects. Temperature in the subdistrict is about 3~5°C higher than its surroundings because of heat island effects which could be weakened if greening rate of the sbudistrict is increased. Finally, simulation results show that wall materials affect the environment considerably.

Analysis on Life Cycle CO<sub>2</sub> Emission of Aerated Concrete Production in China

Aerated concrete is a new type of wall material with beneficial features like light weight, heat insulation, fire prevention and low energy consumption. As a key milestone in wall materials innovation and energy-saving of building system, it has been proven to be an ideal wall material which can replace traditional clay brick through years of application and practice. This study calculated the CO2 emissions in all the stages of life cycle of aerated concrete production. Compared with clay brick, the life cycle CO2 intensity of aerated concrete block will be decreased by 67.4% with the same insulation effect. Study on the environmental loads of aerated concrete industry will provide theoretical base for the carry out of energy-saving and emission reduction, the formulation of clean production and the development of recycling economy.

Effects of altering the liquid phase boundary conditions of methanol pool fires

Fuel burning rate, flame height and temperature distributions within the liquid phase of a methanol pool fire were measured to investigate the impacts of altering the pool’s liquid-side boundary conditions. The conditions changed were the temperature at the bottom of the pool and the material used for the pool walls (either quartz or aluminum). These materials were chosen for their different thermal conductivities, which affect one of the pathways for heat transfer from the flame to the pool. The experiments were conducted under steady state and quiescent ambient conditions. It was observed that the burning rate increased linearly with increasing the bottom boundary temperature, and that the aluminum pool was significantly more sensitive to this parameter than the quartz pool. Due to the coupling between burning rate and flame area, the flame height showed similar behavior to boundary temperature and pool wall material variations. For either type of wall materials, the temperature distribution showed a vertical structure of two distinct layers with one layer being nearly uniform and the other having a relatively steep gradient. The arrangement of these layers was unexpectedly opposite for the different wall materials. For the aluminum vessel the pattern was thermally well-mixed in the lower part of the pool and the steep temperature gradient near the surface, while for the quartz pool the thermally well-mixed region was at the top. These observations lead to proposing the existence of non-1-D fluid motion in regions of high convective heat transfer from the walls. Irrespective of the underlying mechanism, these differing temperature distributions suggested that the liquid phase is not as simple as what has been typically modeled in the literature.

Microencapsulation of Flaxseed Oil by Spray Drying: Effect of Oil Load and Type of Wall Material

The objective of this work was to evaluate the effect of the type of wall material and the oil load on the microencapsulation of flaxseed oil by spray drying. Gum arabic, whey protein concentrate, and a modified starch were used to produce the microcapsules, each with four oil concentrations (10, 20, 30, and 40% oil, w/w, with respect to total solids), for a total of 12 tests. Initially, the feed emulsions were characterized for stability, viscosity, and droplet size. Then they were dried in a laboratory-scale spray dryer and the resulting particles were analyzed for encapsulation efficiency, lipid oxidation, moisture content, and bulk density. The increase in oil concentration led to the production of emulsions with larger droplets and lower viscosity, which directly affected powder properties, resulting in lower encapsulation efficiency and higher lipid oxidation. Among the three wall materials evaluated, the modified starch showed the best performance, with the highest encapsulation efficiency and lowest peroxide values.

Stabilization of canthaxanthin produced by Dietzia natronolimnaea HS-1 with spray drying microencapsulation.

The strain bacterium Dietzia natronolimnaea has propounded as a source for biological production of canthaxanthin. Because of sensitivity of this pigment, examine on its stability is important. In this study, stability of encapsulated canthaxanthin from D. natronolimnaea HS-1 using soluble soybean polysaccharide (SSPS), gum acacia (GA), and maltodextrin (MD) as wall materials was investigated at 4, 25, and 45°C in light and dark conditions during 4months of storage. It was shown that the type of walls influenced the size of emulsion droplets; spray dried particles, microencapsulation efficiency (ME), and retention of canthaxanthin in microcapsules. SSPS and MD produced the smallest and the biggest emulsion droplets and spray dried particles, respectively. Microcapsules made with SSPS resulted in better ME and higher stability for canthaxanthin. Samples were degraded in all conditions, especially in light and 45°C. Degradation of microencapsulated canthaxanthin with SSPS and GA proceeded more slowly than did with MD. Regardless of the type of wall materials, total canthaxanthin contents of the microencapsulated products decreased by an increase in time or temperature. Also, samples exposed to light indicated less stability at 4 and 25°C when compared to the storage at dark conditions. According to the results of this study, SSPS can be considered as potential wall material for the encapsulation of carotenoids.

Aerated Concrete Block in Engineering Application

The autoclaved aerated concrete is a new type of wall material of energy reserve and enviroment protection, it has good economy profit and social profit during basic construction. Basic on application of aerated concrete in Hunan, this paper discussed its application from material, construction, plastering and existing problem. It is reference for relevant design and construction people.

Development of a soup powder enriched with microencapsulated linseed oil as a source of omega‐3 fatty acids

AbstractThe main objective of this study was to develop an optimized formulation of soup powder enriched with omega‐3 fatty acids. For this purpose, the process conditions for optimizing the microencapsulation efficiency (ME) of linseed oil by spray drying were determined using the Taguchi methodology with an orthogonal array L4(23). The effect of the variables on the ME, such as wall material concentration (25 and 30%), linseed oil concentration (14 and 20%), and wall material type (gum arabic GA; and a mixture maltodextrin/GA), was evaluated. The oxidative stability of the microcapsules obtained were determined by the Rancimat method, and a morphological and size characterization of microcapsules was performed by scanning electronic microscopy, confocal microscopy, and laser diffraction. The optimization of the soup formulation was reached by means of RSM, using the central composite design, two control factors (salty taste and consistency), and 11 design points. The hedonic test was applied to measure the acceptability of the optimized formulation. Chemical characterization of optimized soup and its oxidative stability were also evaluated. This study resulted in a healthy soup enriched with omega‐3 which was highly acceptable to consumers.Practical applications: Linseed oil is a healthy and nutritive oil, very rich in unsaturated fatty acids such as omega‐3. In addition to protecting the oil against oxidative damage, the microencapsulation of oils in a polymeric matrix (mainly polysaccharides and proteins) also offers the possibility of controlled release of the lipophilic functional ingredient and can be useful for the supplementation of foods with PUFA. The soup powder enriched with microencapsulated linseed oil as a source of omega‐3 formulated in this study will contribute to the development of foods according to the functionality requirements of current consumers and markets.

Beta-efficiency of a typical gas-flow ionization chamber using GEANT4 Monte Carlo simulations

GEANT4 based Monte Carlo simulations have been carried out for the determination of efficiency and conversion factors of a gas-flow ionization chamber for beta particles emitted by 86 different radioisotopes covering the average-b energy range of 5.69 keV-2.061 MeV. Good agreements were found between the GEANT4 predicted values and corresponding experimental data, as well as with EGS4 based calculations. For the reported set of b-emitters, the values of the conversion factor have been established in the range of 0.5?1013-2.5?1013 Bqcm-3/A. The computed xenon-to-air conversion factor ratios have attained the minimum value of 0.2 in the range of 0.1-1 MeV. As the radius and/or volume of the ion chamber increases, conversion factors approach a flat energy response. These simulations show a small, but significant dependence of ionization efficiency on the type of wall material.

Effect of Drying Process and Wall Material on the Properties of Encapsulated Cardamom Oil

The retention and shelf stability of cardamom oil entrapped in freeze- and spray-dried microcapsules coated with skim milk powder and modified starch was investigated. It was found that the retention of flavor in freeze-dried matrices was low and independent from the composition of wall material, whereas for the spray-dried microcapsules, it was much higher and markedly dependent on the type and percentage of coating material. It was also shown that the particle size of spray-dried powder greatly contributed to the flavor retention and surface oil content of microcapsules. Additionally, microscopic observation of powder particles revealed that the type of wall material and drying method distinctly influenced the morphological characteristics of powders which presumably caused a difference in their capability of cardamom oil retention.

Microencapsulation Efficacy of d-Limonene by Spray Drying Using Various Combinations of Wall Materials and Emulsifiers

The impact of emulsifiers on the microencapsulation of d-limonene was investigated for the wall materials gum arabic (GA) or maltodextrin (MD) and their blend. The emulsifiers used were sucrose ester (SE), polyglycerol ester (PGE), and sugar beet pectin (SBP). SBP presented good emulsification ability and higher retention of d-limonene with various types of wall materials. On the other hand, SE was not recommended because of its unstable emulsion, resulted in very low flavor retention. For PGE, the flavor retention was strongly dependent on the type of wall material. Regarding to the physicochemical properties of spray-dried powder, the combination of GA and PGE produced a stable emulsion and had high flavor retention with low surface oil, while the MD and SE combination was not recommended because of unstable emulsion and almost no flavor retention.

Microbiological evaluation of poultry house wall materials and industrial cleaning agents

SUMMARY Proper cleaning of commercial poultry production units, particularly after the removal of litter, is essential for a successful biosecurity program. The effectiveness of a cleaning regimen depends on numerous variables, such as organic load, building design, and wall and floor materials. The objective of this project was to compare the efficacy of industrial cleaning agents used in food-processing establishments with one commonly used on farm, and to determine if the type of wall material influenced the effectiveness of these products. Iodine, a disinfectant traditionally used in broiler housing, was compared with 2 cleaning agents commonly used in food-processing areas. Each cleaner was applied to 3 types of building material (plywood, metal, and plastic), which had been placed in commercial broiler pens to achieve an organic load. Plywood maintained a higher bacterial load after cleaning than other building material types. Additionally, iodine was not as effective as either the foam or gel cleaner commonly used in food-processing establishments. This information will be useful in developing good sanitization protocols for commercial poultry production.

Optimization of the Microencapsulation of Lemon Myrtle Oil Using Response Surface Methodology

Response surface methodology (RSM) was applied to study the effects of types of wall materials (modified starch + maltodextrin and whey protein concentrate + maltodextrin), feed concentration, oil concentration, and outlet air temperature on oil retention and surface oil content of the encapsulated powder. The results revealed that the oil retention was significantly (P < 0.05) affected by the constant term of types of wall materials and the linear term of feed concentration but seemed to be almost independent (P > 0.05) of experimental range of oil concentration and outlet air temperature. The types of wall materials, oil load, and outlet air temperature showed a significant (P < 0.05) influence on surface oil content. The types of wall materials (Hi-Cap and WPC) also influenced significantly the oil retention and surface oil content. Based on the limited range of experimental conditions used in this work, it was not possible to choose the wall materials that can give both high oil retention and low surface oil content. Disregarding the effect of wall material, an optimum response was obtained at 40% of feed concentration (w/w), 18% of oil concentration, and 65°C of outlet air temperature.

Decomposition and discoloration of L-ascorbic acid freeze-dried with saccharides

Abstract L -Ascorbic acid (vitamin C) was freeze-dried along with the following six types of wall materials: soluble soybean polysaccharide (SSPS), gum arabic (GA), maltodextrin (MD), α-cyclodextrin (α-CD), trehalose (Tre) and lactose (Lac). α-CD, Tre and Lac were used in mixtures with MD (weight ratio of 1:1). The decomposition kinetics of L -ascorbic acid in these powders stored at 80 °C and relative humidities of 11, 51 and 79% were expressed by the Weibull equation. The discoloration of the powders was also monitored by measuring the absorbance at 500 nm for solutions which were obtained by dissolving the systems in water. The L -ascorbic acid powders prepared with GA and SSPS were significantly discolored and the processes could be expressed by a modified Weibull equation. The discoloration of the L -ascorbic acid powders prepared with other saccharides was very slow. The discoloration rate constants were significantly greater at temperatures higher than the glass transition temperatures of the saccharides under the stated storage conditions, while the decomposition rate constant was only slightly affected by the system glass transition temperature. Industrial relevance Decomposition and discoloration are examples of food deterioration. Food usually represents a multi-component system in which components interact with each other. Both their state and interaction would affect the deterioration. L -Ascorbic acid is one of the food components which are subject to decomposition and discoloration during storage. The decomposition and discoloration of L -ascorbic acid powders freeze-dried with saccharides were measured under various conditions and kinetically analyzed to understand an aspect of food deterioration.

Characteristics of microencapsulated β-carotene formed by spray drying with modified tapioca starch, native tapioca starch and maltodextrin

Acid-modified tapioca starch, native tapioca starch, and maltodextrin were tested for their ability to serve as wall materials for encapsulating β-carotene. The modified tapioca starch had wider particle size distribution, toward the smaller diameters, as compared to its native starch and maltodextrin. Moisture content and water activity of microcapsules were found to be dependent on type of wall materials. There were differences in total β-carotene and surface β-carotene contents among samples. The total β-carotene was highest for modified tapioca starch while it was lowest for maltodextrin. The surface β-carotene was lowest for modified tapioca starch while it was highest for native tapioca starch. The modified tapioca starch was more effective than its native starch in β-carotene retention. Results obtained suggest that the modified tapioca starch can be considered as potential wall material for encapsulation of β-carotene.

Stability of Lactobacillus reuteri in Different Types of Microcapsules

ABSTRACT:This study was designed to find the most suitable method and wall material for microencapsulation of the probiotic bacterium Lactobacillus reuteri to maintain cell viability during gastric challenge. Five L. reuteri strains were individually encapsulated using alginate, alginate plus starch, K‐carrageenan with locust bean gum, or xanthan with gellan by extrusion or phase separation (emulsion). The morphology of the microcapsules was studied using phase contrast and cryo‐scanning electron microscopy (cryo‐SEM). The resistance of these microcapsules and the viability of contained L. reuteri to simulated gastric juice were studied. The shape and size of the microcapsules produced varied with the preparation method and type of wall material. Extruded microcapsules were larger and more uniformly shaped. Survival of microencapsulated L. reuteri was significantly better than that of planktonic cells and varied with the strain, method of microencapsulation, and wall material used. In general, microencapsulation using alginate and alginate with starch by both extrusion and phase separation were found to provide bacteria significantly greater protection (P &lt; 0.05) against simulated gastric juice.

Micromegas neutron beam monitor neutronics

The Micromegas is a type of ionising radiation detector that consists of a gas chamber sandwiched between two parallel plate electrodes, with the gas chamber divided by a Frisch grid into drift and amplification gaps. Investigators have applied it to a number of different applications, such as charged particle, X-ray and neutron detection. A Micromegas device has been tested as a neutron beam monitor at CERN and is expected to be used for that purpose at the Spallation Neutron Source (SNS) under construction in Oak Ridge, TN. For the Micromegas to function effectively as neutron beam monitor, it should cause minimal disruption to the neutron beam in question. Specifically, it should scatter as few neutrons as possible and avoid neutron absorption when it does not contribute to generating useful information concerning the neutron beam. Here, we present the results of Monte Carlo calculations of the effect of different types of wall materials and detector gases on neutron beams and suggest methods for minimising disruption to the beam.

Investigation of Ozone Loss Rate Influenced by the Surface Material of a Discharge Chamber

ABSTRACT Decay characteristics of ozone concentration in oxygen in a chamber with three types of wall material (stainless steel, copper, and aluminum) are measured using the 254 nm photoabsorption method. Effective lifetimes of ozone are estimated from decay curves of ozone concentration. These values depend on the wall material: They are largest for stainless steel and smallest for aluminum. The relationship between effective lifetime and gas pressure is investigated precisely to determine three values. The equivalent diffusion coefficient of ozone in oxygen and the reflection coefficient of ozone at the wall correspond to the loss rate of ozone at the wall. The collisional loss (quenching) rate coefficient of ozone in oxygen is also determined.

THERMAL BEHAVIOR IN RECTANGULAR CHANNELS BY USING TRANSIENT LIQUID CRYSTAL METHOD

A series of experimental investigations by using the transient liquid crystal method on the studies related to the convective heat transfer in rectangular channels with different wall material types have been successfully performed. The results show that the local and average Nusselt numbers on the test channel surface for wall material type (II) are higher than those for wall material type (I). The effect of the steady-state air preheating temperature on average Nusselt numbers is not significant, while the average Nusselt numbers increase with increasing Reynolds number in a power of 0.627. Furthermore, two empirical Nu correlations for channels with wall material type (I) and type (II) are respectively proposed in this study.

Influence of tube wall material type and tube temperature on the recombination processes of nitrogen ions and atoms in afterglow

The recombination of positive ions and atoms during an afterglow period, created during previous electrical breakdown and gas discharge, at the molybdenum glass and copper is investigated using the time delay method. It has been shown that the recombination of the positive ions at the copper wall, while the atoms at the molybdenum wall, at room temperature, is more intensive. The temperature influence on the recombination of these particles at copper has also been monitored by the same method, showing that the positive ion recombination rate increases and atom recombination rate decreases with temperature.