Reflections on restructuring of IEJME

As an international journal, one of the goals of International Electronic Journal of Mathematics Education (IEJME) is to stimulate discussions in our field through publishing significant and innovative research studies. To pursue this goal better, IEJME has gone through a restructuring process recently. The journal is now stronger with its two new associate editors, an editorial assistant, and a renewed international editorial board. We now have a shorter and improved review process. There are certain measures and challenges we needed to take into consideration in revising and improving the structure of the journal. The purpose in this article is to share the changes made to the journal and their impact in its progress

Age and growth of four-spotted megrim (Lepidorhombus boscii Risso, 1810) from Saros Bay (Northern Aegean Sea, Turkey)

In this study, the growth parameters of the four-spotted megrim, (Lepidorhombus boscii Risso, 1810), were studied in Saros Bay, which had been closed to bottom trawl fishery since 2000. The sex ratio of females to males was 1:0.42. Length-weight relationships were W=0.0032L3.31 and W=0.0069L3.04 for females and males, respectively. Growth parameters of the populations were L∞=49.8 cm, k=0.09 year-1, t0=-2.15 year for females; L∞=39.1 cm, k=0.11 year-1, t0=-2.59 year for males. The growth performance index (Φ’) was found to be 2.35 and 2.23 for females and males, respectively

Designing microcapsules to save energy in buildings

Buildings consume the major portıon of the world’s energy. Improvements in building elements have been proven to significantly reduce this consumption. Integrating phase change materials (PCM) into a building’s parts is an effective solution to reduce energy consumption. PCMs help to maintain thermal comfort, reduce heating, cooling loads as well as improve passive storage of solar energy in buildings. Previous studies have concentrated on impregnating PCMs into materials like concrete mixes, gypsum wall boards, plasters, textured finishes, as well as PCM trombe walls, PCM shutters, PCM building blocks, air-based heating systems, floor heating systems, suspended ceiling boards, etc.[1]. The current challenge is to find a suitable PCM that can be safe, thermally effective and at the same time not adversely effect the durability of a building. PCMs may be in microcapsulated form to meet these challenges. The most common PCM studied previously is paraffin, be it in bulk or microencapsulated. Leakage of paraffin from porous structures, the breaking of microcapsules and the low thermal capacities of microencapsulated PCMs are the main problems that have been observed [2]. The current challenge is to find a suitable PCM that can be safe, thermally effective and at the same time not adversely effect the durability of a building. PCMs may be in microcapsulated form to meet these challenges. The most common PCM studied previously is paraffin, be it in bulk or microencapsulated. Leakage of paraffin from porous structures, the breaking of microcapsules and the low thermal capacities of microencapsulated PCMs are the main problems that have been observed [2. Paraffin is a fossil fuel derivative; thus, it is unsustainable. This study focuses on bio-based fatty acid mixtures as PCMs. We developed microcapsules of fatty acid mixtures that were tried in concrete mixes. Our design approach involved the following steps: determining and characterizing PCMs with suitable thermal properties; developing a method to synthesize microencapsulated PCMs; and finally incorporate these materials in buildings for improving thermal comfort and energy conservation. Please click Additional Files below to see the full abstract

Design of high power S-band GaN MMIC power amplifiers for WiMAX applications

This paper reports two different S band GaN MMIC PA designs for WiMAX applications. First PA has a 42.6 dBm output power with a 55%PAE @ 3.5 GHz and 16 dB small signal gain in the 3.2-3.8 GHz frequency range. When two of these MMICs were combined by using off-chip Lange Couplers, 45.3 dBm output power with a 45%PAE @3.5Ghz and 16 dB small signal gain were obtained with less than 0.2 dB gain ripple in the 3.3-3.8 GHz frequency range. © 2011 IEEE

The effect of initial pH and retention time on boron removal by continuous electrocoagulation process

In this study, factors influencing boron removal via the continuous electrocoagulation process were investigated at lab-scale. Different influent pH values (4, 5, 6, 7.45 and 9) and contact times (10, 25, 50 and 100 min) were examined as variable parameters. Plate-type aluminium electrodes with 5 mm distance between them were used. All the experiments were conducted in continuous mode and the current density was kept constant at 5 A throughout the whole experimental period. The initial boron concentration was selected to be 1000 mg L-1. The first set of experiments concerning the influence of the influent pH showed that the highest boron removal (67%) was obtained at pH=6 since it was the optimal pH for boron precipitation through aluminium borate formation. Under the constant current density of the study and with the initial pH adjusted to 6, increasing the duration of the electrocoagulation process from 10 to 100 min resulted in raising the boron removal from 45 to 79% during the second set of experiments. The greater duration of the electrocagulation process enabled higher aluminium dissolution, thus allowing the existence of a higher number of coagulants within the reactor. Moreover, it enhanced boron precipitation because of the longer contact time between the boron ions and the coagulants. After optimizing significant parameters such as the influent pH and the electrocagulation duration, the continuous electrocoagulation process was found to constitute an effective alternative for boron removal

Low-frequency time-domain characterization for fast and reliable evaluation of microwave transistor performance

In this paper, we introduce the use of the low-frequency characterization of electron devices as an accurate and economical way to fast gather consistent data about the electron device performance at microwaves in the evaluation phase of new components, technologies and processes. © 2016 European Microwave Association

Inhibition of focal adhesion kinase with her-2 targeted antibody pertuzumab (Omnitarg®, 2C4) in breast cancer cells

Pertuzumab (Omnitarg®, 2C4) is a recombinant humanized monoclonal antibody targeted to extracellular region of HER-2. Previous results proved the inhibitory effect of Pertuzumab on the survival of breast cancer cells via MAPK and Akt pathway. Focal adhesion kinase (FAK) regulates multiple cellular processes including growth, differentiation, adhesion, motility and apoptosis. Here, we aimed to investigate the effects of Pertuzumab on ligand activated total FAK expression and phosphorylation in the HER-2 overexpressing BT-474 breast cancer cell line. Heregulin was used for ligand activation. We have found that FAK expression and phosphorylation were inhibited in with Pertuzumab in breast cancer cells