Technology assessment for power quality mitigation devices - Micro-DVR case study

This work presents a case study on technology assessment for power quality improvement devices. A system compatibility test protocol for power quality mitigation devices was developed in order to evaluate the functionality of three-phase voltage restoration devices. In order to validate this test protocol, the micro-DVR, a reduced power development platform for DVR (dynamic voltage restorer) devices, was tested and the results are discussed based on voltage disturbances standards. (C) 2011 Elsevier B.V. All rights reserved.

DEVELOPMENT OF A MICRO-HEAT EXCHANGER WITH STACKED PLATES USING LTCC TECHNOLOGY

A green ceramic tape micro-heat exchanger was developed using Low Temperature Co-fired Ceramics technology (LTCC). The device was designed by using Computational Aided Design software and simulations were made using a Computational Fluid Dynamics package (COMSOL Multiphysics) to evaluate the homogeneity of fluid distribution in the microchannels. Four geometries were proposed and simulated in two and three dimensions to show that geometric details directly affect the distribution of velocity in the micro-heat exchanger channels. The simulation results were quite useful for the design of the microfluidic device. The micro-heat exchanger was then constructed using the LTCC technology and is composed of five thermal exchange plates in cross-flow arrangement and two connecting plates, with all plates stacked to form a device with external dimensions of 26 x 26 x 6 mm(3).

Trace elements removal from water using modified activated carbon

This paper present the possible alternative options for the remove of trace elements from drinking water supplies in the trace. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causing various adverse effects on living bodies. The performance of three filter bed methods was evaluated in the laboratory. Experiments were conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe / Fe3C (iron / iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon, powder carbon steel and ceramic spheres in the ion-sorption columns as a cleaning process. The modified powdered block carbon is a satisfactory and economical sorbent for trace elements (arsenite and chromate) dissolved in water due to its low unit cost of about $23 and compatibility with the traditional household filtration system.

Influence of substrate surface topography in the deposition of nanostructured diamond-like carbon films by high density plasma chemical vapor deposition

In this work, we have studied the influence of the substrate surface condition on the roughness and the structure of the nanostructured DLC films deposited by High Density Plasma Chemical Vapor Deposition. Four methods were used to modify the silicon wafers surface before starting the deposition processes of the nanostructured DLC films: micro-diamond powder dispersion, micro-graphite powder dispersion, and roughness generation by wet chemical etching and roughness generation by plasma etching. The reference wafer was only submitted to a chemical cleaning. It was possible to see that the final roughness and the sp(3) hybridization degree strongly depend on the substrate surface conditions. The surface roughness was observed by AFM and SEM and the hybridization degree of the DLC films was analyzed by Raman Spectroscopy. In these samples, the final roughness and the sp(3) hybridization quantity depend strongly on the substrate surface condition. Thus, the effects of the substrate surface on the DLC film structure were confirmed. These phenomena can be explained by the fact that the locally higher surface energy and the sharp edges may induce local defects promoting the nanostructured characteristics in the DLC films. (C) 2008 Elsevier B.V. All rights reserved.

Mechanical properties, drying and autogenous shrinkage of blast furnace slag activated with hydrated lime and gypsum

This article reports the characteristics of blast furnace slag (BFS) pastes activated with hydrated lime (5%) and hydrated lime (2%) plus gypsum (6%) in relation to compressive strength, shrinkage (autogenous and drying) and microstructure (porosity, hydrated products). The paste mixtures were characterized using powder X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and thermogravimetric analysis (TG/DTG). BSF activated with lime and gypsum (LG) results in larger amounts of ettringite when compared with BFS activated with lime (L). Although the porosities of the L and LG mixtures were about the same, there was a greater pore refinement for the BFS activated with lime, with an increase in mesopores volume with age. The presence of ettringite and the higher volumes of macropores cause the compressive strength of BSF activated with hydrated lime plus gypsum to be smaller than that of BFS activated with lime. For both chemical activators, compressive strength developed slowly at early ages. Autogenous and drying shrinkage were greater for the BFS activated with lime, believed to result from the more refined porous structure in comparison with the mixture activated with gypsum plus lime. (c) 2010 Elsevier Ltd. All rights reserved.

Chemical interaction between EVA and Portland cement hydration at early-age

Ethylene/vinyl acetate (EVA) copolymer. as latex or redispersable powder, is added to mortars and concrete to improve the fracture toughness, impermeability and bond strength to various substrates. The physical and chemical interactions were already proved after one day of hydration but during the first hour just the physical interaction was identified and some evidences of a chemical interaction. The aim of this paper was to evaluate the chemical interaction between EVA and Portland cement during the first hours of hydration in the thermogravimetric analysis. The results confirmed that the EVA hydrolyses in pH alkaline and consumes calcium ions from the solution, forming an organic salt (calcium acetate). reducing the calcium hydroxide content. And, its interaction occurred in the first 15 min of hydration. (C) 2009 Elsevier Ltd. All rights reserved.

Microencapsulation of propolis extract by complex coacervation

The propolis has potential to be a natural food additive However its application is limited because It is alcohol-soluble and has strong flavour Microencapsulation may be an alternative for reducing these problems The aim of this study was to encapsulate propolis extract by complex coacervation using isolated soy protein and pectin as encapsulant agents The coacervation was studied as a function of pH (5 0 4 5 4 0 and 3 5) and the concentration of encapsulants and core (2 5 and 5 0 g/100 mL) Samples obtained at pH 4 0 in both concentrations were lyophilized and analyzed for hygroscopicity encapsulation efficiency particle size morphology thermal behavior stability of phenolic and flavonoids during storage as well as antioxidant and antimicrobial activities It was possible to encapsulate propolis extract by complex coacervation and to obtain it in the form of powder alcohol-free stable with antioxidant property antimicrobial activity against Staphylococcus aureus and with the possibility of controlled release in foods (C) 2010 Elsevier Ltd All rights reserved

Occurrence of AFM(1) in urine samples of a Brazilian population and association with food consumption

This survey evaluated the presence of AFM(1) in human urine samples from a specific Brazilian population, as well as corn, peanut, and milk consumption measured by two types of food inquiry. Urine samples from donors who live in the city of Piracicaba, State of Sao Paulo, Brazil were analyzed to detect the presence of aflatoxin M(1) (AFM(1)). an aflatoxin B(1) metabolite, which may be used as aflatoxin B(1) exposure biomarker. The AFM(1) analysis was performed using immunoaffinity clean-up and detection by high-performance-liquid chromatography with fluorescence detector. A total of 69 samples were analyzed and 45 of them (65%) presented contaminations >= 1.8 pg ml(-1), which was the limit of quantification (LOQ). Seventy eight percent (n = 54) of the samples presented detectable concentrations of AFM(1) (>0.6 pg ml(-1)). The AFM(1) concentration among samples above LOQ ranged from 1.8 to 39.9 pg ml(-1). There were differences in food consumption profile among donors, although no association was found between food consumption and AFM(1) concentration in urine. The high frequency of positive samples suggests exposure of the populations studied to aflatoxins. (C) 2009 Elsevier Ltd. All rights reserved.

An estimate of biometric parameters in eucalyptus clone plantations in Southern Bahia: an application of the airborne laser scanning (ALS) technology

The application of airborne laser scanning (ALS) technologies in forest inventories has shown great potential to improve the efficiency of forest planning activities. Precise estimates, fast assessment and relatively low complexity can explain the good results in terms of efficiency. The evolution of GPS and inertial measurement technologies, as well as the observed lower assessment costs when these technologies are applied to large scale studies, can explain the increasing dissemination of ALS technologies. The observed good quality of results can be expressed by estimates of volumes and basal area with estimated error below the level of 8.4%, depending on the size of sampled area, the quantity of laser pulses per square meter and the number of control plots. This paper analyzes the potential of an ALS assessment to produce certain forest inventory statistics in plantations of cloned Eucalyptus spp with precision equal of superior to conventional methods. The statistics of interest in this case were: volume, basal area, mean height and dominant trees mean height. The ALS flight for data assessment covered two strips of approximately 2 by 20 Km, in which clouds of points were sampled in circular plots with a radius of 13 m. Plots were sampled in different parts of the strips to cover different stand ages. The clouds of points generated by the ALS assessment: overall height mean, standard error, five percentiles (height under which we can find 10%, 30%, 50%,70% and 90% of the ALS points above ground level in the cloud), and density of points above ground level in each percentile were calculated. The ALS statistics were used in regression models to estimate mean diameter, mean height, mean height of dominant trees, basal area and volume. Conventional forest inventory sample plots provided real data. For volume, an exploratory assessment involving different combinations of ALS statistics allowed for the definition of the most promising relationships and fitting tests based on well known forest biometric models. The models based on ALS statistics that produced the best results involved: the 30% percentile to estimate mean diameter (R(2)=0,88 and MQE%=0,0004); the 10% and 90% percentiles to estimate mean height (R(2)=0,94 and MQE%=0,0003); the 90% percentile to estimate dominant height (R(2)=0,96 and MQE%=0,0003); the 10% percentile and mean height of ALS points to estimate basal area (R(2)=0,92 and MQE%=0,0016); and, to estimate volume, age and the 30% and 90% percentiles (R(2)=0,95 MQE%=0,002). Among the tested forest biometric models, the best fits were provided by the modified Schumacher using age and the 90% percentile, modified Clutter using age, mean height of ALS points and the 70% percentile, and modified Buckman using age, mean height of ALS points and the 10% percentile.

Microbiological Assay for Apramycin Soluble Powder

The aim of this study was to validate an agar diffusion method through the parameters linearity, precision and accuracy, to quantify apramycin in soluble powder. The calibration curve of apramycin was constructed by plotting log of concentrations (mu g ml(-1)) versus zone diameter (mm) and shows good linearity in the range of 1.0-4.0 mu g.ml(-1). The precision of the assay was determined by assaying samples at the same day (repeatability - R.S.D. = 2.00%) and on different days (intermediate precision - R.S.D. = 5.06%) and indicate good precision. The accuracy expresses the agreement between the accepted value and the value found. The mean recovery was found to be 100.49 % for apramycin soluble powder. The results indicated that the microbiological assay proposed in this work hold linearity, precision and accuracy being an acceptable alternative method for routine quality control of apramycin in the pharmaceutical dosage form studied.

Retention of the Enzymatic Activity and Product Properties During Spray Drying of Pineapple Stem Extract in Presence of Maltodextrin

The aim of this work was to investigate the effects of drying parameters on the retention of the enzymatic activity and on the physical properties of spray-dried pineapple stem extract. A Box and Behnken experimental design was used to investigate the effects of the processing parameters on the product properties. The parameters studied were the inlet temperature of drying gas (Tgi), the feed flow rate of the pineapple extract relative to evaporative capacity of the system (Ws /Wmax), and the concentration of maltodextrin added to the extract (MD). Significant effects of the processing parameters on the retention of the proteolytic activity of the powdered extract were observed. High processing temperatures lead to a product with a smaller moisture content, particle size, and lower agglomerating tendency. A product with insignificant losses of the proteolytic activity ( 10%) and low moisture content (less than 6.5%) is obtained at selected conditions.

The effect of a novel crystallised bioactive glass-ceramic powder on dentine hypersensitivity: a long-term clinical study

P>The aim of this comparative clinical study was to evaluate a novel bioactive glass-ceramic (Biosilicate (R) 1-20 mu m particles) to treat dentine hypersensitivity (DH). Volunteers (n = 120 patients/ 230 teeth) received the following treatments: G1-Sensodyne (R), G2-SensiKill (R), G3-Biosilicate (R) incorporated in a 1% water-free-gel and G4-Biosilicate (R) mixed with distilled water at 1:10 ratio. G1 and G3 were applied at home, daily for 30 days; G2 and G4 were applied once a week by a dentist (four applications). A visual analogue scale (VAS) was employed to evaluate pain for each quadrant in one sensitive tooth at baseline, weekly during treatment and during a 6-month follow-up period. Dentine hypersensitivity values (G1/n = 52), (G2/n = 62), (G3/n = 59) and (G4/n = 59) were analysed with Kruskal-Wallis/Dunn tests. All the products were efficient in reducing DH after 4 weeks. Among the four materials tested, G4 demonstrated the best clinical performance and provided the fastest treatment to reduce DH pain. Distilled water proved to be an adequate vehicle to disperse Biosilicate (R). Low DH scores were maintained during the 6-month follow-up period. The hypothesis that the novel bioactive glass-ceramic may be an efficient treatment for DH was confirmed.

Paste Residence Time in a Spouted Bed Dryer. IV: Effect of the Inert Particle Size Distribution

The residence time distribution and mean residence time of a 10% sodium bicarbonate solution that is dried in a conventional spouted bed with inert bodies were measured with the stimulus-response method. Methylene blue was used as a chemical tracer, and the effects of the paste feed mode, size distribution of the inert bodies, and mean particle size on the residence times and dried powder properties were investigated. The results showed that the residence time distributions could be best reproduced with the perfect mixing cell model or N = 1 for the continuous stirred tank reactor in a series model. The mean residence times ranged from 6.04 to 12.90 min and were significantly affected by the factors studied. Analysis of variance on the experimental data showed that mean residence times were affected by the mean diameter of the inert bodies at a significance level of 1% and by the size distribution at a level of 5%. Moreover, altering the paste feed from dripping to pneumatic atomization affected mean residence time at a 5% significance level. The dried powder characteristics proved to be adequate for further industrial manipulation, as demonstrated by the low moisture content, narrow range of particle size, and good flow properties. The results of this research are significant in the study of the drying of heat-sensitive materials because it shows that by simultaneously changing the size distribution and average size of the inert bodies, the mean residence times of a paste can be reduced by half, thus decreasing losses due to degradation.

Spray Drying of Extracts from Red Yeast Fermentation Broth

Red yeast rice is a pigmented material that is traditionally used in Asia as a food colorant. In addition to food applications, red yeast rice is known in traditional Chinese medicine for its therapeutic actions. The aim of this work was to study the quality interactions during spray drying of extracts from the Monascus ruber van Tiegham fermentation broth. The quality indicators used for the dry powder properties were the levels of monacolin K, ratio of red to yellow pigments, as well as their antioxidant activity. The experiments followed a Box-Behnken design to study the effects of the adjuvant/drug ratio, adjuvant incorporation time, and oulet drying temperature on the pharmacotechnical, chemical, and biological properties of the dry extract. The influences of these factors on the characteristics of the dry powder were evaluated by the bulk density, tapped density, Carr index, Hausner factor, residual moisture content, water activity, antioxidant activity, monacolin K, yellow-to-red pigment ratio, and antioxidant activity. The analysis of variance (ANOVA) on experimental data revealed that an increase in drying temperature significantly increased the dry powder yield and caused an improvement in powder flow properties, which may be related to lower moisture contents. The drying temperature did not affect the monacolin K content in dry powder but showed a complex influence on its antioxidant activity. The increase in drying adjuvant-to-drug ratio affected the yield and also indicated a protective effect on the monacolin K content. The duration of drying adjuvant incorporation had little or negligible effect on powder properties. The dry extracts of red yeast rice showed adequate properties and the process proposed herein can be used to prepare nutraceutical products.

A new approach to the granulation of beta-cyclodextrin inclusion complexes

Cyclodextrins (CDs) are annular oligosaccharides containing 6-12 glucose unities joined together by alpha-1,4 bonds. They have a conical-truncated shape with a lipophilic cavity in which different molecules can be included resulting in a stable inclusion complex. The cyclodextrins have been widely applied in pharmaceutical technology with the objective of increasing the solubility, stability and bioavailability of drugs in different pharmaceutical dosage forms, such as tablets. In order to obtain beta-CD tablets, liquid dispersions of drug/beta-CD are usually submitted to different drying processes, like spray-drying, freeze-drying or slow evaporation, being this dry material added to a number of excipients. However, such drying processes can generate particulate materials showing problems of flow and compressibility, needing their conversion into granulates by means of wetting with granulation liquid followed by additional drying. In this work, the main objective was to evaluate the preparation of tablets without the need of this additional drying step. For this purpose an aqueous dispersion containing acetaminophen/beta-CD complex and cornstarch was dried using a spouted bed and the obtained granules were compressed in tablets. Acetaminophen was used as model drug due to its low water solubility and the inexpensive and widely available cornstarch was chosen as excipient. Acetaminophen powder was added into a beta-cyclodextrin solution prepared in distilled water at 70 degrees C. Stirring was kept until this dispersion cooled to room temperature. Then cornstarch was added and the resulting dispersion was dried in spouted bed equipment. This material was compressed into tablets using an Erweka Korsh EKO tablet machine. This innovative approach allowed the tablets preparation process to be carried out with fewer steps and represents a technological reliable strategy to produce beta-cyclodextrin inclusion complexes tablets. (C) 2010 Elsevier By. All rights reserved.