Evaluation of antibacterial effects of contemporary orthodontic bonding materials

Aim: The aim of this study was to evaluate the antibacterial effects of five orthodontic bonding materials commonly used in orthodontics. Materials and Methods: The antibacterial effects of five orthodontic bonding materials were evaluated against Streptococcus mutans and Streptococcus salivarius by direct contact test (DCT). Using the DCT technique, quintet specimens of Transbond XT, Blugloo, Grengloo, Light Bond, and Opal Bond were applied to the bottom and the walls of the five wells of a 96-microtiter plate with a height of 2 mm. Samples were prepared in two sets: 1-day samples and 7-day samples. Ten microliters of bacterial suspension were added to each well for direct contact with each material for 1h at 37 °C. Bacterial growth was then measured in a microplate spectrophotometer hourly at 600 nm for 24 h. Five uncoated wells with identical inoculum sizes served as positive controls. The data obtained at the end of 24 h was statistically analyzed with one-way ANOVA, and post hoc comparisons were done using Tamhane’s T2 test. Results: Blugloo generally showed better antibacterial activity than the other materials. Transbond XT did not show any antibacterial activity. There was a statistically significant difference between Transbond XT and Light Bond in the 1-day sample against S. mutans (p < 0.05). No statistically significant differences were found among the other groups (p > 0.05). Conclusion: Blugloo had the most potent antibacterial activity against S. salivarious.     

A W-Band MMIC Radar System for Remote Detection of Vital Signs

In medical and personal health systems for vital sign monitoring, contact-free remote detection is favourable compared to wired solutions. For example, they help to avoid severe pain, which is involved when a patient with burned skin has to be examined. Continuous wave (CW) radar systems have proven to be good candidates for this purpose. In this paper a monolithic millimetre-wave integrated circuit (MMIC) based CW radar system operating in the W-band (75–110?GHz) at 96?GHz is presented. The MMIC components are custom-built and make use of 100?nm metamorphic high electron mobility transistors (mHEMTs). The radar system is employing a frequency multiplier-by-twelve MMIC and a receiver MMIC both packaged in split-block modules. They allow for the determination of respiration and heartbeat frequency of a human target sitting in 1?m distance. The analysis of the measured data is carried out in time and frequency domain and each approach is shown to have its advantages and drawbacks.     

The decolorization of C.I. Reactive Black 5 in aqueous solution by electrocoagulation using sacrificial iron electrodes

The removal of color from synthetic wastewater containing Reactive Black 5 was experimentally investigated using direct current electrocoagulation at iron electrodes. The effects of operational parameters such as current density, initial pH, electrolysis time, initial dye concentration and solution conductivity on color removal efficiency were investigated in this study. The optimum operating range for each of these operating variables was experimentally determined. The experimental results show that the color of Reactive Black 5 in the aqueous phase was removed effectively. Under the conditions of an initial dye concentration of 100 mg L(-1), initial pH of 5, current density of 4.575 mAcm(-2), salt concentration of 3000 mg L(-1), temperature of 20 degrees C, and interelectrode distance of 2.5 cm, the color removal efficiency reached 98.8%. Electrical energy consumption in the above conditions for the decolorization of the dye solution containing Reactive Black 5 was 4.96 kWh/kg dye. Results show that the first-order rate equation provides the best correlation for the decolorization rate of Reactive Black 5.     

Biorefineries: Current activities and future developments

This paper reviews the current refuel valorization facilities as well as the future importance of biorefineries. A biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power, and chemicals from biomass. Biorefineries combine the necessary technologies of the biorenewable raw materials with those of chemical intermediates and final products. Char production by pyrolysis, bio-oil production by pyrolysis, gaseous fuels from biomass, Fischer–Tropsch liquids from biomass, hydrothermal liquefaction of biomass, supercritical liquefaction, and biochemical processes of biomass are studied and concluded in this review. Upgraded bio-oil from biomass pyrolysis can be used in vehicle engines as fuel.     

Performance investigation of salt gradient cylindrical solar pond integrated and nonintegrated with evacuated tube solar collectors

In this study, the energetic and exergetic efficiencies of a salt gradient cylindrical solar pond (SGCSP) that integrated and nonintegrated evacuated tube solar collectors (ETSCs) are investigated to improve daily heat preservation performance of the heat storage zone (HSZ). The integrated system is consisted of an SGCSP and four ETSCs. The SGCSP has a surface area of 2 m², a depth of 1.65 m, salty water layers at different densities, and HSZ in which the cylindrical serpentine type heat exchanger (CSHE) is located. Thus, the daily effects of the heat storage performance of both the ETSCs and the SGCSP in the winter season was determined experimentally. The analysis of the data regarding the efficiencies of the system is investigated separately by means of experimental studies where the SGCSP is integrated and nonintegrated with the ETSCs. The number of ETSCs integrated with SGCSP is increased to 1, 2, 3, and 4, respectively, and each of the five different experimental systems is performed separately. The temperature distributions of the integrated system are measured by a data acquisition system on 11 different points per hour. The efficiencies are calculated using the data obtained from these studies. Consequently, the energetic and exergetic efficiencies of the SGCSP are obtained without collectors as 10.4% and 4.3% and with one collector as 12.83% and 6.15%, with two collectors 14.88% and 8.25%, with three collectors 16% and 9.35%, and finally with four collectors 16.94% and 10.3%, respectively. Furthermore, the theoretical efficiencies are found to be consistent with the experimental results obtained by increasing the collector numbers.     

Improving the flame retardancy and mechanical properties of epoxy composites using flame retardants with red mud waste

In this study, a novel flame retardant ammonium tetrafluoroborate (ATFB) was successfully synthesized using boric acid (H₃BO₃) and ammonium hydrogen difluoride (NH₄HF₂) as the reactants. In addition to ATFB, aluminum hydroxide (Al(OH)₃) was used as a flame retardant and red mud (RM) waste was used as a filler to prepare epoxy composite materials with enhanced flammability properties. The appropriate ratio of RM:ATFB:Al(OH)₃ both in terms of combustion and mechanical properties was found to be 15:10:5 wt%. The tensile strength of the composite in this ratio was obtained as 112 MPa, while the neat ER was 46 MPa. The burnout of the composite with the appropriate RM:ATFB:Al(OH)₃ ratio decreased in the first 10 seconds, and extinguished in 32 seconds. Moreover, the burned area of this composite was the smallest among all the others. The experimental and estimated LOI values for this composite was found as 26 and 29, respectively.     

Trick the body trick the mind: avatar representation affects the perception of available action possibilities in virtual reality

Virtual Reality - In immersive Virtual Reality (VR), your brain can trick you into believing that your virtual hands are your real hands. Manipulating the representation of the body, namely the...     

Parasitic effects of the metallic towers on the characteristics of the broadcast antennas

In this article, we use a tool NEC (Numerical Electromagnetic Code) to model antenna on top of a tower structure. Simulation results for the parasitic effect of the tower on characteristics of broadcast DVB‐T (Digital Video Broadcasting Terrestrial) antenna such as input impedance, return loss, gain, front‐to‐back ratio and radiation patterns are reported. In addition, the effect of a nearby tower on antenna characteristics is studied. A 3D tower and broadband antenna in the UHF (470‐862) MHz band are constructed. The antenna works for both digital and analog TV with return loss (RL) ≥ 10 dB, fractional bandwidth of 87% and gain of 12.3 dBi at center frequency. The effective radiated power is calculated by mounting the antenna at each face of the tower to give a satisfactory coverage to a region around the antenna.     

A new approach for dyeability of cotton fabrics by different plasma polymerisation methods

The increased dyeability of cotton fabrics in low temperature media using two different plasma polymerisation methods was investigated in this study. In the first method, fabrics were directly treated in amine plasma (ethylenediamine or triethylenetetramine). In the second method, they were first treated in argon plasma and then immersed in an aqueous amine bath. The treated fabrics were then dyed with a reactive dye (Remazol Black B) and the colour yields and fastness properties of the resulting fabrics measured. The K/S values obtained were significantly improved when compared to the untreated fabric.