Comparative Analyses of Heavy Metals in Portland Cement, Proroot Mta, Angelus MTA using Atomic Absorption Spectrophotometry

The purpose of this study was to evaluate the acid soluble Arsenic, Lead and Chromium content of Portland cement, Proroot MTA and Angelus MTA and also to find the metal ion leach in water and simulated body fluid at 24hrs and 7 days. The total metal was determined by the ISO 9917-1 (2007) method. Two grams of the Port land cements and MTAs were mixed with water or the liquid provided, placed in separate plastic bags, and flattened out to produce a very thin disc. The mixture was then allowed to cure in an oven at 37_C and 100% humidity for 24 hours. The disc was crushed to a very fine powder in an agate mortar and pestle. Two grams of the powdered material were placed in a 150-mL conical flask and 50 ml of 2.4 mol/L of hydrochloric acid were added. The slurry was swirled well, lightly stoppered, and allowed to stand for 16 hours. The solution was then centrifuged in a tube for 10 minutes. The supernatant was transferred to a stoppered acid washed plastic tube. The arsenic, lead, and chromium content were measured using a graphite furnace atomic absorption spectrophotometer 600mg of Port land cement and both the MTAs are mixed with the water and liquid provided by the manufacturer Cured at 37 C for 24 hrs six cement disc are made for each cement type. Three are placed in water and other three in simulated body fluid. The solutions were changed at 24hs and 7 days. The amount of Arsenic, lead and chromium leached was observed using graphite furnace atomic absorption spectrophotometer. The data's were obtained in Parts per Million (PPM). Analysis of variance with p = 0.05 and the One way Anova test were used to perform multiple comparison tests. The results were tabulated. CONCLUSION: Under the limitations of this present study it can be concluded that: 1. The Heavy Metal (Arsenic,) content in Portland cement, Proroot MTA, Angelus MTA were higher than the recommended level (ISO 9917-1). 2. Lead content was found to be the least in all the cement types tested. 3. Chromium was found to be more in Portland Cement, Proroot MTA and Angelus MTA than arsenic and lead. 4. Higher amount of leaching of Heavy metals (As, Pb, Cr) were found in Port land cement. 5. Proroot MTA Showed the leas t release of Heavy metal ions followed by Angelus MTA. Further systemic long term studies can be undertaken to investigate the potential toxicity of Heavy metals present in Mineral Trioxide Aggregate

Partially isolated four port converter with combined PWM and secondary phase shift control

A partially isolated four-port converter is proposed in this paper for interfacing two renewable sources and a storage device with an isolated load. This converter is capable of achieving high power density because of the effective sharing of devices among the input ports. Combined PWM and secondary phase shift control is employed to have a decoupled power flow management of input and output side ports. PWM control is used at the input side for maximum power tracking of renewable sources and battery power management. At the output side, secondary Phase shift control is used for controlling the output voltage. The adopted secondary phase shift control allows the primary switching legs to be operated with 1800 phase shift which results in reduced current ripple at input ports. The working principle of the converter, its output characteristics and control strategy are discussed. Working of the converter and its control strategy is verified through simulation for different input and output conditions. Further, to validate the simulation results, the experimental results of a 500W prototype are also provided

Non-isolated high gain DC-DC converter by quadratic boost converter and voltage multiplier cell

AbstractA novel non-isolated DC-DC converter is proposed by combining quadratic boost converter with voltage multiplier cell. The proposed converter has low semiconductor device voltage stress and switch utilization factor is high. The superiority of the converter is voltage stress of the semiconductor devices depends on voltage multiplier (VM) cell. By increasing the VM cell the stresses across the devices reduce drastically. The proposed converter has same number of components compared to certain voltage lift converters taken for comparison. A detailed comparative study is made on the proposed converter with few voltage lift converters in the literature, conventional boost with VM cell and quadratic boost converter. A 40W prototype is constructed with 12V input voltage and 96V output voltage to verify the performance and validate the theoretical analysis of the proposed converter

Editorial: Integrated water management for enhanced water quality and reuse to create a sustainable future

Safe drinking water and sanitation are very important for the survival of human life. With the rapid proliferation of industries, growth in population and different forms of pollution, i.e. in water, air, soil and sediments, the living environment and the ecosystem is constantly polluted. In this context, integrating different water resources for enhanced water quality and reuse is important to solve the persisting problems and challenges in developing and the developed nations. Integrated water management offers environmental, economic and social benefits because it aims at maximizing the existing resources and prevents further depletion of the ecosystem

Performance comparison of hybrid active power filter for p-q theory and SVPWM technique

Harmonic Distortion in many of the industrial applications are occur primarily owing to the enormous utilization of loads with high non-linearity like power converters, speed varying drives and arc furnaces. The power semiconductor is used to achieve the variation in speed and conversion from one source to another. Mostly active filters and tuned filters are utilized to remove the harmonic included in the source current. The tuned passive filters and inductance inserted in the line reduces the harmonics but at the same time induces the resonances in most of the industrial applications. Due to this, harmonic distortion increases in the source current and voltage. This can be reduced by adding hybrid filter in the system with decreased rating of active filter in high power applications. This article deals with the various topology of hybrid filters. The working of the proposed filter design in variable inductance mode based on the pollution created in the source voltage and current is studied. In the proposed hybrid filter passive filter is tuned with seventh harmonic frequency and connected in series with active filters to reduce the harmonic distortion. DC link voltage and the active filter VA rating could be minimized. The control signal to the filter is derived from p-q theory and space vector pulse width modulation (SVPWM). The performance of the system under study is simulated and noted for the THD percentage before and after the filter is added to the system and the same model is experimented with reduced voltage level

Evaluation of critical congenital heart defects screening using pulse oximetry in the neonatal intensive care unit.

ObjectiveTo evaluate the implementation of early screening for critical congenital heart defects (CCHDs) in the neonatal intensive care unit (NICU) and potential exclusion of sub-populations from universal screening.Study designProspective evaluation of CCHD screening at multiple time intervals was conducted in 21 NICUs across five states (n=4556 infants).ResultsOf the 4120 infants with complete screens, 92% did not have prenatal CHD diagnosis or echocardiography before screening, 72% were not receiving oxygen at 24 to 48 h and 56% were born ⩾2500 g. Thirty-seven infants failed screening (0.9%); none with an unsuspected CCHD. False positive rates were low for infants not receiving oxygen (0.5%) and those screened after weaning (0.6%), yet higher among infants born at <28 weeks (3.8%). Unnecessary echocardiograms were minimal (0.2%).ConclusionGiven the majority of NICU infants were ⩾2500 g, not on oxygen and not preidentified for CCHD, systematic screening at 24 to 48 h may be of benefit for early detection of CCHD with minimal burden

The projection and measurement of cyberpower

Cyberspace and cyberpower are terms that are increasingly used in common parlance, but are notoriously difficult to define and measure. This article builds on previous work defining the properties of cyberspace in terms of vertical layers, which when combined with a representation of distance presents a three-dimensional model. The unique attributes of cyberspace can be harnessed for power projection, the aim of which is ultimately to alter the behaviour of individuals. Although cyberspace has yet to be used as a medium to demonstrate conventional hard power of coercion and threats supported by physical force, it does present a suitable medium for the projection of soft power of attraction and imitation. These are defined within the context of the online environment and by drawing on the techniques used to optimise Web-based commerce, potential methods of implementing and measuring the success of a campaign of cyberpower projection are proposed

Effects of Dietary Protein and Fat Content on Intrahepatocellular and Intramyocellular Lipids during a 6-Day Hypercaloric, High Sucrose Diet: A Randomized Controlled Trial in Normal Weight Healthy Subjects.

Sucrose overfeeding increases intrahepatocellular (IHCL) and intramyocellular (IMCL) lipid concentrations in healthy subjects. We hypothesized that these effects would be modulated by diet protein/fat content. Twelve healthy men and women were studied on two occasions in a randomized, cross-over trial. On each occasion, they received a 3-day 12% protein weight maintenance diet (WM) followed by a 6-day hypercaloric high sucrose diet (150% energy requirements). On one occasion the hypercaloric diet contained 5% protein and 25% fat (low protein-high fat, LP-HF), on the other occasion it contained 20% protein and 10% fat (high protein-low fat, HP-LF). IHCL and IMCL concentrations (magnetic resonance spectroscopy) and energy expenditure (indirect calorimetry) were measured after WM, and again after HP-LF/LP-HF. IHCL increased from 25.0 ± 3.6 after WM to 147.1 ± 26.9 mmol/kg wet weight (ww) after LP-HF and from 30.3 ± 7.7 to 57.8 ± 14.8 after HP-LF (two-way ANOVA with interaction: p < 0.001 overfeeding x protein/fat content). IMCL increased from 7.1 ± 0.6 to 8.8 ± 0.7 mmol/kg ww after LP-HF and from 6.2 ± 0.6 to 6.9 ± 0.6 after HP-LF, (p < 0.002). These results indicate that liver and muscle fat deposition is enhanced when sucrose overfeeding is associated with a low protein, high fat diet compared to a high protein, low fat diet

Performance of reverse osmosis (RO) for water recovery from permeates of membrane bio-reactor (MBR)

In this study, permeate from a hollow fiber polyethylene (PE) membrane bio-reactor (MBR) system treating synthetic agricultural wastewater was fed into a cellulose acetate brackish water reverse osmosis (BWRO30 2540) membrane system; three different trans-membranes pressures (TMPs) of 1000, 2500, and 4000 kPa were selected to evaluate the system performance in terms of general operating parameters as well as the removal of chosen important potential fouling water quality parameters. The results showed that highest corrected permeate flux rate was at a TMP of 2500 kPa, whereas lowest recorded at a TMP of 4000 kPa. Similar situation prevailed in water recovery rate. But temperature corrected specific fluxes decreased as the applied TMPs increased. In all selected TMPs, more than 96% of salinity was removed. Permeate from MBR as feed to reverse osmosis required frequent chemical cleaning than the microfiltration/ultrafiltration (MF/UF) permeates and granular media filter (GMF) filtered in order to maintain the required rate of product water. One of the reasons for this frequent chemical cleaning is due to higher total organic carbon as well as total nitrogen (TN) in the MBR permeate. This result needs to be further evaluated through field trials. <br /