Effect of Microalloying Additions on the Microstructure and Mechanical Properties of Low Carbon Steel

Low carbon steels are characterized by good weldability,formability and fracture toughness properties.However,the low strength levels of these steel grades limit their wide applications.On the other hand,increasing the strength by increasing the carbon content and alloying elements deteriorates the other properties.In this study,the microalloying technique was used to examine the possibility of attaining low carbon steels with good combination of strength,ductility and impact properties.A low carbon steel microalloyed with single addition of vanadium and another one microalloyed with combined addition of vanadium and titanium were used in this investigation and their properties were compared with non-microalloyed low carbon steel having the same base composition.Furthermore,other two nonmicroalloyed and V-microalloyed steels with higher carbon,silicon and manganese contents were also investigated to reveal the effect of base composition.Tensile,hardness,room and zero temperature Charpy V-notch impact tests were conducted to evaluate the variations in the mechanical properties of low carbon hot forged steel containing vanadium and combinations of vanadium and titanium.In addition,the microstructures of the different investigated steels were observed using both optical microscope and scanning electron microscope.Furthermore,the hardness of the ferrite phase was also determined using micro-hardness technique.The results showed improvement of the mechanical properties of the investigated steels by both single V-and combined V + Ti-microadditions.Tensile,hardness and impact tests results indicated that good combinations of strength,ductility and impact properties can be achieved by V-microalloying addition.Steel with combination of V and Ti microaddition has much higher hardness,yield strength,ultimate tensile strength and impact energy at both room and zero temperatures compared with non-microalloyed and single Vmicroalloyed steels.Higher C,Si and Mn contents result in increasing the strength accompanied with decrea     

Thermal comfort analysis of earth-sheltered buildings: The case of meymand village,Iran

Vernacular buildings are known for their localized passive settings to provide comfortable indoor environment without air conditioning systems. One alternative is the consistent ground temperature over the year that earth-sheltered envelopes take the benefit; however, ensuring annual indoor comfort might be challenging. Thus, this research monitors the indoor thermal indicators of 22 earth-sheltered buildings in Meymand, Iran with a warm-dry climate. Furthermore, the observations are used to validate the simulation results through two outdoor and indoor environmental parameters, air temperature and relative humidity during the hottest period of the year. Findings indicated that the main thermal comfort differences among case studies were mainly due to their architectural layouts where the associated variables including length, width, height, orientation, window-to-wall ratio, and shading depth were optimized through a linkage between Ladybug-tools and Genetic Algorithm (GA) concerning adaptive thermal comfort model definition and could enhance the annual thermal comfort by 31%.     

A Comparative Study Of Ann For Predicting Nitrate Concentration In Groundwater Wells In The Southern Area Of Gaza Strip

ABSTRACT

The main source of water in the Gaza Strip is the shallow aquifer which is part of the coastal aquifer. The quality of the groundwater is extremely deteriorated in terms of nitrates and salinity. The Gaza Strip is mostly in catastrophic conditions that desire imperative and great efforts to improve the water situation on conditions of both quality and quantity. In this study, performance of two artificial networks was evaluated to determine which one would have more efficiency in predicting nitrate concentrations of groundwater wells used for desalination purpose in the southern area of Gaza Strip. Multiple layer perceptron (MLP) and radial basis function (RBF) neural networks are trained and developed with reference to seven important variables including pH, EC, TDS, hardness, calcium, magnesium, and abstraction rate. These variables are considered as inputs of the network. The data sets used in this study consist of six months and collected from 15 groundwater wells in Khan Younis and Rafah area. The network performance has been tested with different data sets and the results showed satisfactory performance. The prediction results of the MLP neural network were found to be better than RBF. Prediction results prove that neural network approach has good and wide applicability for modeling nitrate in the groundwater wells of Gaza Strip coastal aquifer. We hope that the established model will help in assisting the local authorities in developing plans and policies to improve the water quality in the Gaza Strip to acceptable levels.     

Synthesis and characterization of CNTs/POM nanocomposite acetabular hip cup

Polyoxymethylene (POM) considered as the most appropriate alternative for ultra-high molecular weight polyethylene (UHMWPE) in the hip joint replacement application due to their biocompatibility, high mechanical properties, and cheapness. The wear is the main cause of the failure in the hip joint and the wear resistance of UHMWPE is still better than the wear resistance of POM. This research aims to improve the wear behavior of POM by blending it with 0.02?wt% of functionalized carbon nanotubes (CNTs) and using paraffin oil dispersion technique to obtain a uniform dispersion. The injection molding and machining process were used to produce the new (CNTs/POM) nanocomposite acetabular hip cup which has a high wear performance. The wear rate of the CNTs/POM cups was evaluated using a total leg joint’s simulator at 1,000?N for 3 million cycles under serum-based lubricated conditions. Moreover, the wear mechanism of cups was examined by scanning electron microscopy as well as the dispersion of CNTs inside the cup matrix. The results show that the wear resistance of POM cup has been improved by adding functionalized CNTs ～402% and ～221%, when compared with a virgin POM and UHMWPE, respectively, because of increasing the melting temperature and crystallinity degree.     

Recent Advances for Improving Functionality,Biocompatibility, and Longevity of Implantable Medical Devices and Deliverable Drug Delivery Systems

The great majority of medical devices elicit foreign body response (FBR) postimplantation. FBR is a major hurdle to develop a successful device for impaired organs, leading to failure of devices/treatments. In recent times, several advantageous technologies have been developed based on either surface modifications or localized drug delivery systems (DDSs) in order to overcome the FBR limitation, which enhanced the success of implantable medical devices. The recent advances for improving the functionality, biocompatibility, and longevity of implantable medical devices and deliverable DDSs are discussed here. It is believed that these advances will further guarantee the improvement of existing implants and deliverable entities while enabling the development of new therapy technologies. Such technologies are anticipated to be long-term patient-friendly and thus lead to a higher quality of life.     

Workshop 7a (synthesis): sustainable groundwater management.

Groundwater, the hidden part of the hydrological cycle, is often overlooked in the freshwater discourse, partly because the damage and changes that human activities cause are not immediately visible. Increasingly across the world, groundwater resources are strained with serious consequences.     

Achieving informed decision-making for net zero energy buildings design using building performance simulation tools

Building performance simulation (BPS) is the basis for informed decision-making of Net Zero Energy Buildings (NZEBs) design. This paper aims to investigate the use of building performance simulation tools as a method of informing the design decision of NZEBs. The aim of this study is to evaluate the effect of a simulation-based decision aid, ZEBO, on informed decision-making using sensitivity analysis. The objective is to assess the effect of ZEBO and other building performance simulation tools on three specific outcomes: (i) knowledge and satisfaction when using simulation for NZEB design; (ii) users’ decision-making attitudes and patterns, and (iii) performance robustness based on an energy analysis. The paper utilizes three design case studies comprising a framework to test the use of BPS tools. The paper provides results that shed light on the effectiveness of sensitivity analysis as an approach for informing the design decisions of NZEBs.     

Screening of strains of Lactococci isolated from Egyptian dairy products for their proteolytic activity

A collection of cocci isolates (293) obtained from traditional Egyptian dairy products collected from four Egyptian regions yielded 151 lactic acid bacteria (LAB) cocci isolates. Among them, 24 isolates were characterised as highly proteolytic. SDS–PAGE showed that 6 isolates were the most proteolytically active, which were classified into Enterococcus faecalis HH22 (4 isolates) and Enterococcus faecium DO623 (2 isolates). The proteolytic activity of E. faecalis was higher than that of E. faecium (particularly on β-casein). The maximal degradation of milk proteins was achieved at pH 6.5–7.2 (E. faecalis) or pH 6.5 (E. faecium) and at 42 °C for both strains. The proteolytic activities of the two strains were inhibited mostly by the presence of EDTA, showing that their proteases belong mainly to metalloproteases. A slight inhibition of proteolysis by PMSF in the case of E. faecalis HH22 suggests a limited inclusion of serine proteases in its protease system.     

Synthesis and characterization of zirconyl molybdopyrophosphate and its application for preparing 137Cs/137m Ba radioisotope generator

Semicrystalline zirconyl molybdopyrophosphate (ZMPP) ion exchanger was synthesized and characterized by thermal analysis, IR spectroscopy, and X-ray diffraction and was used for preparing ¹³⁷Cs/^137m Ba radioisotope generator. The interaction of ¹³⁴Cs radionuclides in HCl solutions was studied by batch equilibration method. The corresponding distribution coefficients were determined in relation to the acid concentration. Cesium-137 was loaded onto 1 g of zirconyl molybdopyrophosphate packed in 0.6 cm i.d. column. Elution of the generated ^137m Ba was examined in relation to the chemical composition and flow rate of the eluent. Barium-137m was obtained with high and reproducible elution yield and high chemical and radionuclidic purity.