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- Amalgam Dental Fillings as the Source of Mercury Exposure and Alternative
Solutions
Authors: Yousef ALASHHAB; Asmaa A. ABDEEWİ, İdris KABALCI
Abstract: The amalgam filling plays a major role in restorative dentistry when applied and has additional strength due to its contents, such as mercury and other alloys that could be Cooper, Silver, Tin, or Zinc. A concern has been raised that amalgam causes mercury toxicity and two primary organs are the kidney and the central nervous system that are affected by Hg poisoning.The objective of the present study is to examine new dental amalgam fillings and old amalgam fillings removed from patııent's teeth in term of a potential cause of mercury exposure, in addition to the alternative dental fillings. The technique of this study is a metallographic evaluation by using the rapid analytical technique of X-ray diffraction (XRD). Moreover, the specimens used have been obtained from a different set of amalgam fillings, to measure the mercury present in an unmixed sample, a mixed sample according to the manufacturer's recommendations, and dental amalgam fillings that had been in the patient's theeth after filling them for 15 and 20 years to analyze exposure to mercury by comparison. Mercury unmixed sample contains on silver Tin 64% and Copper Zinc 36% While mixed samples contain of Silver Mercury 63% and Copper Tin 37%, the sample after 15 years’ dental amalgam filling induced when the Silver mercury contain is increased to 84% and low Copper Tin 16%, While the sample after 20 years’ dental amalgam filling containing approximately Silver Mercury contain is 80% and Copper Tin 20%.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- EFFECTS OF SUPERHEATING AND SUBCOOLING IN A VAPOR COMPRESSION
REFRIGERATION SYSTEM WITH R507A REFRIGERANT
Authors: Bayram KILIÇ; Emre ARABACI
Abstract: Vapor compression cooling systems are the most used and most efficient cooling method in industrial and commercial applications. The reason of these systems are preferred is that they reduce environmental impacts, provide energy efficiency and have economic advantages. In this article, the effects of superheating and subcooling on the system performance in the vapor compression refrigeration cycle (VCRS) using R507A were theoretically examined. The thermodynamic data used the calculation were taken from the Coolpack program. The performance analysis of the VCRS were made for different operating conditions. In the analyses, the evaporator temperature was changed between -5 and -25 oC, the condenser temperature was changed between 25 and 45 oC, and the superheat and subcooling temperatures were changed as 0, 3, 5 and 7 oC. In the analysis made depending on the change in evaporator temperature, superheat and subcooling temperatures, the highest COP value of the cycle is 3.71. In the analysis made depending on the change in condenser temperature, superheat and subcooling temperatures, the highest COP value of the cycle was found to be 4.367.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- EXPERIMENTAL INVESTIGATION OF THE EFFECT OF THE CHARGE AMOUNT ON THE POWER
CONSUMPTION AND COOLING PERFORMANCE OF A REFRIGERATION SYSTEM
Authors: Faraz AFSHARİ; Azim Doğuş TUNCER, Afşin GÜNGÖR
Abstract: Refrigeration systems are mechanical devices that transfer heat from a low-temperature region to a high-temperature region, effectively cooling a space or substance. They operate based on the principles of thermodynamics, utilizing refrigerants to extract heat from the area being cooled and then expelling it elsewhere. These systems play a crucial role in maintaining suitable temperatures for various applications across industries. The choice of refrigerant and system design significantly impacts efficiency, environmental impact, and overall performance. This study investigates the impact of refrigerant gas charge amounts on the performance of these systems. Two different charge amounts including 340 g and 425 g have been utilized in a refrigeration system that use R134a as refrigerant gas. The experimental process has been performed in a controlled environment. Analyzing the relationship between the quantity of refrigerant gas and system efficiency, this research aims to provide insights into optimizing charge levels to enhance the overall performance and energy efficiency of refrigeration systems. Experimental results showed that increasing the refrigerant charge amount from 340 g to 425 g reduced the hourly energy consumption from 0.322 kWh to 0.306 kWh. Moreover, the average coefficient of performance (COP) values were attained as 3.94 and 4.04, respectively for the charge amounts of 340 g and 425 g. The findings contribute to a deeper understanding of the intricate dynamics between refrigerant gas charge amounts and system functionality, offering potential strategies for improved system design and operation.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- EVALUATION OF DENİZLİ SKI CENTRE IN TERMS OF AVALANCHE
SUSCEPTIBILITY
Authors: Kerem HEPDENİZ
Abstract: Avalanches, which occur in areas far from settlements and where the human population is relatively less, have started to occur more frequently and cause more loss of life and property due to the increasing human population, the gradual expansion of settlements and road networks, and the increasing interest in ski resorts, nature sports and winter tourism. Avalanches, which can reach speeds of up to 400 kilometres per hour, occur very suddenly and most people cannot escape. Today, it is not possible to change the nature of avalanches and prevent avalanches. In order to prevent damages caused by avalanches, it is necessary to prepare potential avalanche susceptibility maps. In this way, dangerous areas can be identified and it will be possible to predict, prevent and reduce the impact of avalanches. In this study, it was aimed to evaluate Denizli Ski Centre and its immediate surroundings in terms of avalanche susceptibility. For this purpose, Geographical Information Systems programme was used and land use, elevation, slope slope, aspect and slope shape parameters were used for avalanche susceptibility analysis and potential source areas for avalanche development were determined. After this stage, areas with high, medium and low avalanche susceptibility were determined by using Conefall software. Thus, it is aimed to make healthier planning for decision makers and local administrations by making use of susceptibility maps for Denizli Ski Resort and to reveal areas with high, medium and low avalanche safety in terms of runways, roads and ski facilities.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- NUMERICAL AND EXPERIMENTAL INVESTIGATION OF AIR PERMEABILITY OF AN
EVAPORATOR
Authors: İsmet Faruk YAKA; Afşin GÜNGÖR
Abstract: In this study, the air distribution in the evaporator of an industrial type monoblock refrigerator is investigated numerically and experimentally. Using the ANSYS program, 12 different points on the evaporator were determined and the velocity of these points were numerically determined, and the evaporator was divided into 5 different regions and the air flow rate change in these regions was examined. The simulated parts were also measured experimentally in a monoblock refrigerator. As a result, it is observed that there is an unbalanced air distribution on the evaporator, which has a negative effect on cooling performance and energy consumption. Thanks to the fins used to distribute the air flow more evenly, the difference in distribution between the left and right zones of the evaporator is reduced by 10.8 m3/h. As a result, a more balanced flow distribution was achieved with an improvement of approximately 10%.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- Complementary Soft Binary Piecewise Symmetric Difference Operation: A
Novel Soft Set Operation
Authors: Aslıhan SEZGİN; Kubilay DAGTOROS
Abstract: Since Molodtsov first introduced soft set theory, a useful mathematical tool for solving problems related to uncertainties, many soft set operations have been described and used in decision making problems. In this study, a new soft set operation called complementary soft binary piecewise symmetric difference operation is defined, and its properties are examined in comparison with the basic algebraic properties of the symmetric difference operation. Moreover, it has been shown that the collection of soft sets with a fixed set of parameter together with complementary soft binary symmetric difference and restricted intersection, is a commutative hemiring with identity and also a Boolean ring.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- Design and Implementation of a 2.45 GHz Band-Stop Filter Using
Single/Three Open Stubs
Authors: Büşra ÖZTÜRK; Özlem COŞKUN
Abstract: The importance of filter structures in RF/microwave applications is quite high. These filters are frequently used in microwave systems, especially in satellite and mobile communication systems. Generally, in devices such as oscillators and mixers; to block unwanted signals, band-stop filters are added to the structures. One of the WLAN applications, IEEE 802.11b has a maximum raw speed of 11Mbit/s and is used to connect the same devices in the original standard. Devices operating in the IEEE 802.11b standard experience interference from other devices (microwave ovens, bluetooth devices, cordless phones) operating at 2.45 GHz. As the main goal of this study; in order to prevent this interference, band-stop filter circuit design with single/three open stubs were carried out at the frequency of 2.45 GHz. Thanks to the realized band-stop filter designs; unwanted signals are filtered and the desired signals are transmitted successfully.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- WIND SPEED PREDICTION USING DATA MINING APPROACHES: A CASE STUDY OF
GÖKÇEADA, TURKEY
Authors: Fatma Kadriye DÜDEN
Abstract: In this study, the meteorology data set covering the wind speed, humidity, pressure and temperature data between the years 2014-2021 obtained from the Turkish State Meteorological Service is utilized. With this data set, an estimation is made for the Gokceada district in Canakkale-Turkey, with the WEKA software as pressure and temperature inputs and wind speed output. Gaussian Processes, Linear Regression, Multilayer Perceptron, Simple Linear Regression, SMOreg, Kstar, Decision Table, M5P algorithms in WEKA software are used for estimation. It is made for 7 different groups as temperature-pressure-humidity, temperature-pressure, temperature-humidity, humidity-pressure, temperature, pressure and humidity. According to the results, the best estimation for the temperature-pressure-humidity group is found to be 0.999 for the CC (correlation coefficient) value and 0.2994 for the RMSE (root-mean-square error) with the Kstar algorithm. For the temperature-humidity group, the CC value is 0.9607 and the RMSE value is 0.2777. Estimates from the temperature-pressure and humidity-pressure groups is not give accurate results in comparison to the other groups. The CC and RMSE results are obtained from the humidity and pressure groups are found to be 0.9998 and 0.9985, 0.2679 and 0.0464, respectively.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- Nanotechnology in Endodontics: Advancing and Efficacy in Root Canal
Therapy
Authors: Feyza OZDEMIR KISACIK
Abstract: Nanotechnology is a rapidly developing field with a wide range of applications in various industries, including medicine, electronics, and materials science. Nanomaterials produced with nanotechnology have also started to be used in dentistry applications. The use of nanotechnology in dentistry has revolutionized various aspects of oral healthcare, from diagnostics to treatments.This article reviews the current status of nanotechnology in the field of endodontics with its possible applications
PubDate: Sun, 31 Dec 2023 00:00:00 +030
- Determination of Rockfall Potential Source areas of Yeşilbaşköy Village
Burdur Türkiye
Authors: Kerem HEPDENİZ
Abstract: The management of rockfall risk and mitigation of its effects are gaining importance as an effective strategy in the fight against disasters. Geographic Information Systems are used as a powerful tool in rockfall risk mapping and susceptibility analysis. The aim of this study is to determine the rockfall source areas of Yeşilbaşköy village in Burdur province by using Geographical Information Systems and Conefall software and to classify these areas as low-medium and high-risk areas. In the first step, a digital elevation map was produced by digitizing the 1/25000 scale topographic maps of the study area. Potential rockfall source areas were determined by using digital elevation model and slope map was created. Considering the critical slope angles, low-medium and high-risk rockfall areas were mapped in the Yeşilbaşköy region. Low-risk areas represent areas where slopes are lower and less problematic in terms of stability. On the other hand, high-risk areas indicate steep slopes, loose soils and susceptibility areas in terms of geological structure. The results of this study provide an important basis for understanding the distribution of rockfall risk in Yeşilbaşköy village and for developing disaster management strategies. Thanks to the analytical and visualization capabilities provided by Geographic Information Systems, it becomes easier to create disaster risk maps and to use them in decision-making processes. This helps local governments and decision makers to allocate resources effectively and plan risk reduction measures.
PubDate: Sun, 31 Dec 2023 00:00:00 +030
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