An experimental investigation on the laser cure of thermosetting powder: An empirical model for the local coating

We report an in-depth experimental study to evaluate a process for achieving a local coating of thermosetting powder on metallic substrate. Laser cure is a fast and smart process for achieving local, bound, and fixed coating.     

Impact of the hypocaloric diet using food substitutes on the body weight and biochemical profile

Recent studies using balanced hypocaloric diets with food substitutes in some meals, have presented positive results. There are no studies with the Brazilian population on the efficacy of using food substitute, together with a hypocaloric diet. Main objective of this study was to verify the effects of a hypocaloric diet using food substitutes as meal replacement on the body weight, lipid profile, and glucose and insulin plasma levels. Seventy eight subjects of both genders were selected, 20-50 years old, and a body weight index between 25 kg/m2 and 35 kg/m2. The study lasted for six months and it was divided in 2 phases of three months each- mass reduction for 3 months and 3 months for maintenance. The sample was randomly divided in two groups: Group A (control- 3 months of general nutritional and physical orientation followed by 3 months with 1 meal replacement) and Group B (intervention- 2 meals replacement a day plus nutritional and physical orientation for 3 months followed by 3 months with 1 meal replacement). Anthropometric measurements, percent body fat (%BF), biochemical profile and intake survey were performed at moments 0, 3 and 6 months. Both groups showed a significant decrease in %BF, weight, and consequently in their BMI, in the third and sixth month of follow up. However, weight loss in group B was higher than in group A. At the end of the treatment, 0 and 25.0% of the patients of the group A and B, respectively, presented a weight loss higher than 10% of the initial weight. Comparing the triglycerides, LDL-cholesterol and glucose levels, between the beginning and after the three and six months of treatment, there was a significant reduction in the individuals only in group B. In conclusion, the use of food substitutes as meal replacement, together with a balanced, hypocaloric diet, proved to be efficient in weight loss for Brazilian overweighed individuals.     

Walnut consumption in a weight reduction intervention: effects on body weight,biological measures,blood pressure and satiety

Background

Dietary strategies that help patients adhere to a weight reduction diet may increase the likelihood of weight loss maintenance and improved long-term health outcomes. Regular nut consumption has been associated with better weight management and less adiposity. The objective of this study was to compare the effects of a walnut-enriched reduced-energy diet to a standard reduced-energy-density diet on weight, cardiovascular disease risk factors, and satiety.

Methods

Overweight and obese men and women (n =?100) were randomly assigned to a standard reduced-energy-density diet or a walnut-enriched (15% of energy) reduced-energy diet in the context of a behavioral weight loss intervention. Measurements were obtained at baseline and 3- and 6-month clinic visits. Participants rated hunger, fullness and anticipated prospective consumption at 3 time points during the intervention. Body measurements, blood pressure, physical activity, lipids, tocopherols and fatty acids were analyzed using repeated measures mixed models.

Results

Both study groups reduced body weight, body mass index and waist circumference (time effect p <?0.001 for each). Change in weight was ?9.4 (0.9)% vs. -8.9 (0.7)% (mean [SE]), for the standard vs. walnut-enriched diet groups, respectively. Systolic blood pressure decreased in both groups at 3 months, but only the walnut-enriched diet group maintained a lower systolic blood pressure at 6 months. The walnut-enriched diet group, but not the standard reduced-energy-density diet group, reduced total cholesterol and low-density lipoprotein cholesterol (LDL-C) at 6 months, from 203 to 194 mg/dL and 121 to 112 mg/dL, respectively (p <?0.05). Self-reported satiety was similar in the groups.

Conclusions

These findings provide further evidence that a walnut-enriched reduced-energy diet can promote weight loss that is comparable to a standard reduced-energy-density diet in the context of a behavioral weight loss intervention. Although weight loss in response to both dietary strategies was associated with improvements in cardiovascular disease risk factors, the walnut-enriched diet promoted more favorable effects on LDL-C and systolic blood pressure.

Trial registration

The trial is registered at (NCT02501889).

     

An investigation of the effects of the molecular weight distribution on the sensitivity of positive electron resists

The molecular weight distribution of two grades of poly(methyl methacrylate) was determined, and the solubility of that polymer in methyl ethyl ketone–2-propanol mixtures was studied. The effects of the molecular weight distribution of the polymer and the strength of the developing solvent on electron resist sensitivity were studied experimentally and compared with a computer model of the electron exposure process. The molecular weight and the molecular weight distribution were found to have a significant effect on the sensitivity of poly(methyl methacrylate) as an electron resist. Increased sensitivity is predicted for higher molecular weight and narrower molecular weight distribution.     

An investigation into the impact of daylight on perceived color of façade: Understanding the role of chromaticness

Color selection has always been a classic problem in exterior color design for the simple reason that façade color is commonly chosen at the architect's office, regardless of different external conditions affecting color perception. This issue often leads to an apparent discrepancy between the selected color and the perceived color of façade. So far, extensive research has been carried out to identify, classify, and study the influence of these conditions on perceived color. However, little attention has been paid to the importance of color attributes. Hence, this article attempts to grasp better the significance of chromaticness, as briefly discussed in earlier studies, in the variation pattern of perceived color while daylight condition differs. In order to determine perceived color, each test subject was asked to compare the color seen on the façade to the standard color samples of natural color system index and choose the matching one, using a designed color‐measuring device. The results obtained from 93 participants demonstrate 3 things: First, they further support the belief that perceived color is influenced in both hue and nuance under varied daylight circumstances. Second, they confirm previous findings that indicated chromaticness would affect the extent of color shifts. And above all, a comparison of the results reveals that façade colors of higher chromaticness values have had less shifts in hue, yet greater shifts in whiteness. Finally, the findings suggest that chromaticness together with the external conditions, under which the color is to be seen, should be carefully considered when selecting the façade color.     

High-velocity impact study of an advanced ceramic using finite element model coupling with a machine learning approach

A numerical approach combining finite element modeling and machine learning is used to inform the material performance of an alumina ceramic tile undergoing high-velocity impact. In this study, the alumina ceramic tile is simulated by incorporating a user-defined Johnson–Holmquist–Beissel (JHB) material model within the framework of smoothed particle hydrodynamics (SPH) in LS-DYNA finite element software. The implementation of the JHB model is verified by comparing equivalent stress–pressure responses through a single element simulation test. After implementation, the computational framework is simulated across our chosen range of conditions by matching the results from both plate impact experiments and ballistic testing from the literature. The computational model is then used to generate training data sets for an artificial neural network (ANN) to predict the residual velocity and projectile erosion for an alumina ceramic tile undergoing high-velocity impact in the SPH framework. The ANN is then used to perform a sensitivity analysis involving exploring the effect of mechanical properties (e.g., strength and shear modulus) and impact simulation geometries (e.g., thickness of ceramic tile) on material performance (i.e., residual projectile velocity and erosion). Overall, this study shows the capability of the FEM-ANN approach in studying the high-velocity impact on ceramic tiles and is applicable to guide the structural-scale design of ceramic-based protection systems.     

一种基于自适应回归核函数的污水处理能耗模型

针对污水处理过程能耗模型难以建立的问题,提出了一种基于自适应回归核函数的建模方法。通过分析污水处理过程的运行特点,构建能耗与运行过程变量之间的关系,得到一种基于过程变量的能耗模型表达;同时利用梯度下降算法对能耗模型参数进行自适应调整,提高模型精度。最后,将设计的能耗模型应用于污水处理过程基准仿真平台BSM1和实际污水处理厂,实验结果表明该模型能够根据污水处理过程变量实时获得污水处理过程的能耗,具有较好的自适应特性和较高的精度。     

An empirical model relating the molecular weight distribution of high-density polyethylene to the shear dependence of the steady shear melt viscosity

An empirical model has been developed to relate molecular weight distribution to the shear dependence of the steady shear viscosity in high-density polyethylene melts. It uses a molecular weight, M_c, which partitions molecular weights into two classes; those below M_c contribute to the viscosity as they do at zero shear, and those above M_c contribute to the viscosity as though they were of molecular weight M_c at zero shear. Each individual molecular weight species contributes on the basis of its weight fraction. M_c is proposed to be a unique function of the shear rate. Using this method of treating the molecular weight distribution, and the zero shear relation for relating η0 to molecular weight, the calculated steady shear viscosities at various shear rates for polyethylene samples of widely varying polydispersities agree well with experimental results. The model makes no judgment on the existence or importance of entanglements in non-Newtonian behavior since it has no specific parameters involving an entanglement concept. Use of the model suggests that for the samples studied, only the upper portion of the molecular weight distribution contributes toward the experimentally observed decrease of steady shear viscosity with shear rate for shear rates of up to 10,000 sec^?1. The lower molecular weight species are assumed to behave in a Newtonian manner.     

Estimating the population impact of an intervention: a decision-analytic approach

The aim of this paper is to highlight the role for decision analysis in assessing outcomes of medical interventions at a population level. The basic steps of decision analysis are introduced and an illustrative hypothetical preventive intervention is examined. Specific modelling challenges that arise when estimating the population impact of an intervention are described and each is accompanied by an example. Decision analysis can provide useful information for health policy decision makers by identifying the intervention(s) with the largest beneficial impact on health over a wide range of assumptions. In addition, by focusing attention on the parameters with the greatest influence on projected outcomes, decision analysis can aid in identifying critical areas for future research.     

An investigation on the applicability of Parachor model for the prediction of MMP using five equations of state

Miscible gas injection is generally used as one of the most efficient methods in the enhanced oil recovery. Minimum miscibility pressure (MMP) is an important parameter in the miscible gas injection projects, since local displacement efficiency in the reservoir media is highly dependent on the MMP. Therefore, an appropriate estimation of MMP would bring significant economic benefits. This paper presents a comparative study on five representative equations of state (EoSs) for predicting MMP using Parachor model together with the criterion of zero interfacial tension (IFT) at the miscibility conditions. The predicted MMP values are compared with the experimental data obtained from the most reliable measurement technique, so called slim tube method. Such a prediction would enables us to judge the accuracy of the results obtained from different equations of state as well as the capability of Parachor model to calculate the MMP. The results of predictions obtained for five oil-gas systems in this study reveal reliable MMP values within 5% of accuracy.     

Can future colour trends be predicted on the basis of past colour trends?: An empirical investigation

A question that has received remarkably little empirical attention is whether colour trends reflect the prevailing sociocultural lifestyle conditions of a society. This is exemplified by such assertions as “the austerity of the War years was accompanied by sombre colours.” The presumed existence of order to colour consumption and a causal association between it and sociocultural lifestyle conditions provides the theoretical underpinnings to the work of colour forecasting agencies. The present study investigated this question by examining changes in Australian residential interior colours over the twentieth century. Colour palettes were assembled decade by decade and an analysis was undertaken using the NCS system. The results indicate that the main variation during the century was in the hue dimension. However, variation in each of the NCS colour dimensions was greater in the second half of the century. No evidence was found to support the notion of colour cycles or any tangible order to colour consumption. Although some colour palettes could be partially accounted for by developments in colour/materials technology, such influences were short‐lived. The picture that emerges does not support the notion that future colour trends can be predicted on the basis of past colour trends. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 235–242, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col. 20110     

Assessment of the ecological effects of forest fertilization using an experimental watershed approach

In the research project ARINUS, the effects of restabilization measures (fertilization with readily soluble MgSO₄) on the element cycling of Norway spruce ecosystems in the Black Forest (SW Germany) are studied. The objective is to quantify the natural and anthropogenic components of element cycling. Interrelations between the terrestrial and aquatic subsystem are assessed using an integrated approach which combines flux measurements in representative plots with input/output balances of small experimental watersheds. The paper discusses the initial effects of a whole-watershed treatment with Kieserite (750 kg ha^–1 MgSO₄ · H₂O) based on the Mg and S cycling in the control watershed. With the fertilizer, 130 kg ha^–1 Mg and 170 kg ha^–1 S were introduced into the system. Fertilization resulted in increased levels of Mg and S in the needles. Despite high inorganic Al concentrations and extremely low Ca/Al ratios in soil solution, there was no evidence for Al toxicity. Since fertilizer losses from the system 1 1/2 years (2 growing seasons) after the treatment have been modest, surface water was hardly been affected. More than 75% of the applied Mg has remained in the ecosystem, primarily in the intensively rooted upper soil layer. Also S has been retained to a considerable extent. The mobility of fertilizer sulfate in acidic forest soils is substantially lower than has been hitherto assumed from laboratory experiments. Therefore, fertilization with readily soluble sulfate-based Mg fertilizers is recommended as an efficient and — in comparison to liming — less risky restabilization measure on sites with a high potential for nitrification.     

Flow near the permeable boundary of an aligned fiber preform: An experimental investigation using laser doppler anemometry

The flow of fluid at the interface of an aligned fiber bed and an open flow is the governing phenomenon in a number of processes of industrial importance. Traditionally, this has been modeled by applying Brinkman's modification of Darcy's law to obtain the velocity profile in planar geometries in terms of an additional parameter called “apparent viscosity.” to test this ad hoc approach, a detailed experimental investigation of the flow was conducted using Laser Doppler Anemometry (LDA) in the close vicinity of the permeable boundary of aligned fiber preforms. The performs used in the experiments consisted of cylindrical fibers aligned in one direction. Two cases were investigated. In the first case, the axis of alignment was in the direction of flow and in the second case the axis of alignment was perpendicular to the flow direction. A Hele-Shaw cell is partially filled with a fibrous preform such that an open channel flow is coupled to the Darcy flow inside the fiber bed through the permeable interface of the bed. The unfilled portion of the Hele-Shaw cell acts as an ideal porous medium of known in-plane permeability, which is much higher than the permeability of the fibrous/porous bed. Modeling this flow situation using a Hele-Shaw cell is appropriate because most composite parts are long and wide in comparison with their thickness. When a viscous fluid is injected at a constant flow rate through the above arrangement, a steady state coupled flow is created. This coupling of the open flow and the Darcy flow through the fibrous bed occurs through the boundary layer zone inside the fibrous bed. Using LDA, steady state velocity profiles are accurately measured in the boundary layer zone by traversing the fibrous bed at a suitable location. For aligned fiber beds, the depth of the boundary layer zone inside the bed was found to be of the order of the mold depth, which is much larger as compared to the Brinkman's prediction. This finding indicates the presence of a length scale that is much larger than the known length scale $ \sqrt K $, where K is the permeability of the bed made up of aligned cylindrical fibers. Based on this finding, the depth of the boundary layer thickness is incorporated in the Brinkman's solution through a boundary condition. This results in a model that compares well with the experimental data for the planar geometry and the fibrous beds considered here.     

An integrated methodology for assessing the impact of food matrix and gastrointestinal effects on the biokinetics and cellular toxicity of ingested engineered nanomaterials

Background

Engineered nanomaterials (ENMs) are increasingly added to foods to improve their quality, sensory appeal, safety and shelf-life. Human exposure to these ingested ENMs (iENMS) is inevitable, yet little is known of their hazards. To assess potential hazards, efficient in vitro methodologies are needed to evaluate particle biokinetics and toxicity. These methodologies must account for interactions and transformations of iENMs in foods (food matrix effect) and in the gastrointestinal tract (GIT) that are likely to determine nano-biointeractions. Here we report the development and application of an integrated methodology consisting of three interconnected stages: 1) assessment of iENM-food interactions (food matrix effect) using model foods; 2) assessment of gastrointestinal transformations of the nano-enabled model foods using a three-stage GIT simulator; 3) assessment of iENMs biokinetics and cellular toxicity after exposure to simulated GIT conditions using a triculture cell model. As a case study, a model food (corn oil-in-water emulsion) was infused with Fe₂O₃ (Iron(III) oxide or ferric oxide) ENMs and processed using this three-stage integrated platform to study the impact of food matrix and GIT effects on nanoparticle biokinetics and cytotoxicity .

Methods

A corn oil in phosphate buffer emulsion was prepared using a high speed blender and high pressure homogenizer. Iron oxide ENM was dispersed in water by sonication and combined with the food model. The resulting nano-enabled food was passed through a three stage (mouth, stomach and small intestine) GIT simulator. Size distributions of nano-enabled food model and digestae at each stage were analyzed by DLS and laser diffraction. TEM and confocal imaging were used to assess morphology of digestae at each phase. Dissolution of Fe2O3 ENM along the GIT was assessed by ICP-MS analysis of supernatants and pellets following centrifugation of digestae. An in vitro transwell triculture epithelial model was used to assess biokinetics and toxicity of ingested Fe₂O₃ ENM. Translocation of Fe₂O₃ ENM was determined by ICP-MS analysis of cell lysates and basolateral compartment fluid over time.

Results

It was demonstrated that the interactions of iENMs with food and GIT components influenced nanoparticle fate and transport, biokinetics and toxicological profile. Large differences in particle size, charge, and morphology were observed in the model food with and without Fe₂O₃ and among digestae from different stages of the simulated GIT (mouth, stomach, and small intestine). Immunoflorescence and TEM imaging of the cell culture model revealed markers and morphology of small intestinal epithelium including enterocytes, goblet cells and M cells. Fe₂O₃ was not toxic at concentrations tested in the digesta. In biokinetics studies, translocation of Fe₂O₃ after 4 h was <1% and ~2% for digesta with and without serum, respectively, suggesting that use of serum proteins alters iENMs biokinetics and raises concerns about commonly-used approaches that neglect iENM – food-GIT interactions or dilute digestae in serum-containing media.

Conclusions

We present a simple integrated methodology for studying the biokinetics and toxicology of iENMs, which takes into consideration nanoparticle-food-GIT interactions. The importance of food matrix and GIT effects on biointeractions was demonstrated, as well as the incorporation of these critical factors into a cellular toxicity screening model. Standardized food models still need to be developed and used to assess the effect of the food matrix effects on the fate and bioactivity of iENMs since commercial foods vary considerably in their compositions and structures.

     

An investigation of the effects of polymer binder compositional variables on the corrosion control of aluminum alloys using magnesium-rich primers

It has recently been shown that magnesium (Mg) particles possessing a thin oxide surface layer can be used to produce primers that provide corrosion protection to aluminum (Al) alloys through a galvanic coupling mechanism. In addition to the Mg particles, polymer binder properties also affect corrosion protection. As a result, the effects of compositional variables associated with a two-component epoxy binder system on the ability of Mg-rich primers to protect an aerospace Al alloy were determined. The variables investigated were epoxy resin molecular mass, curing agent functionality, epoxy/NH ratio, and Mg content. All of the variables investigated had a significant effect on coating system performance and an optimized coating composition was identified that showed very good corrosion protection for at least 3,000 h of ASTM B117 salt spray exposure.     

Effect of high molecular weight fraction in HDPE on its impact properties: An HTSEC study

Three commercial injection-molding-grade HDPE samples were evaluated for their properties. It was found that their impact property determined in the laboratory does not bear a simple correlation with the actual performance. The HTSEC study, undertaken to evaluate these samples, revealed that they differ significantly in z-average and z + 1-average molecular weights. This difference is attributed to the presence of a small amount of a very high molecular weight fraction and is responsible for the variation in the performance. © 1996 John Wiley & Sons, Inc.     

Dairy biofilm: an investigation of the impact on the surface chemistry of two materials: silicone and stainless steel

Biofilms are the most common mode of bacterial growth in nature and the formation will occur on organic or inorganic solid surfaces in contact with a liquid. The aims of this study were, by combining numeration and sessile drop technique, (i) to characterize the structural dynamics of dairy biofilm growth and the physico chemical properties on silicone and stainless steel and (ii) to evaluate the impact of bio-adhesion on chemistry of surfaces at different times of contact (2, 7, 9 and 24?h). Significantly, greater biofilm volumes were observed after 48?h on two materials. Gram-positive bacteria and fungal population exhibited a significantly higher biofilm organization than gram-negative (43–64%). Elsewhere, after 48?h, results showed a slight difference on gram-negative adhered cells on stainless steel than silicone (2.6?×?10⁷?cfu/cm² and 4.7?×?10⁵?cfu/cm², respectively). Moreover, the physico chemical properties of the surfaces showed that the silicone and stainless steel have a hydrophobic character (Giwi?=??68.28?mJ/m² and ?57.6?mJ/m², respectively). Also, both the surfaces present a weak electron donor character (γ ^??=?2.2?mJ/m² and 4.1?mJ/m², respectively). The real-time investigation of the impact of dairy biofilm on the physico chemical properties of the materials has shown a decrease of hydrophobicity degree of the silicone surface that becomes hydrophilic (ΔGiwi?=?11.47?mJ/m²) after 7?h and the increase of electron donor character (γ ^??=?75.8?mJ/m²). Elsewhere, bio-adhesion on stainless steel was accompanied with a decrease of hydrophobicity degree of the surface, which becomes hydrophilic after 7?h of contact (ΔGiwi?=?6.62?mJ/m²) and the increase of the electron donor character (γ ^??=?44.8?mJ/m²). While, after 24?h of contact, results showed a decrease of the hydrophilicity degree and surface energy components of silicone and stainless steel that become hydrophobic (ΔGiwi?=??21.2?mJ/m² and ΔGiwi?=??56.51?mJ/m², respectively) and weak electron donor (γ ^??=?14.0 and 2.3?mJ/m², respectively).     

An investigation into the influence of microwave treatment on mineral ore comminution

The influence of microwave pre-treatment on mineral ore breakage has been investigated. Samples of lead-zinc ore were microwave pre-treated prior to strength testing and change in strength with microwave exposure time determined. Comparisons of change in strength were made between microwave-treated and -untreated material. Using a multimode microwave cavity, it was found that strength could be significantly reduced in 0.5 s when using 15 kW of microwave power. Lower powers in this type of cavity were found to be less effective. Drop weight tests were used to quantify the change in strength in terms of reduction in required comminution energy. Reductions of up to 40% were achieved for particles of mean size 14.53 mm. Preliminary tests in a single-mode microwave cavity gave strength reductions of 50% at 10 kW of microwave power with a residence time of only 0.1 s, indicating that high electric field strength is important in the failure of ore. A preliminary energy balance indicating the benefits of single-mode heating is presented.