Microstructural, Biomechanical, and In Vitro Studies of Ti-Nb-Zr Alloys Fabricated by Powder Metallurgy

Data Availability Statement: The data underpinning this publication can be accessed from Brunel University London’s data repository, Brunelfigshare here under a CCBY licence: https://doi.org/10.17633/rd.brunel.5446813.v1. Non-digital data supporting this study are stored by the corresponding author at Brunel University. Details of how to request access to these data are provided here: https://doi.org/10.17633/rd.brunel.5446813.v1.Supplementary Materials: The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/ma16124240/s1, Figure S1: Plasmid–DNA interaction assay for Ti-Nb-Zr based alloys. The migration pattern of plasmid DNA incubated with Ti-Nb-Zr-based alloys and TiRG4 reference materials is shown in the figure. The bands are labeled as NC: Nicked circular and SC: Supercoiled; ddH2O served as a negative control.Copyright © 2023 by the authors. This study investigated the microstructures, mechanical performances, corrosion resistances, and in vitro studies of porous Ti-xNb-10Zr (x: 10 and 20; at. %) alloys. The alloys were fabricated by powder metallurgy with two categories of porosities, i.e., 21–25% and 50–56%, respectively. The space holder technique was employed to generate the high porosities. Microstructural analysis was performed by using various methods including scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and x-ray diffraction. Corrosion resistance was assessed via electrochemical polarisation tests, while mechanical behavior was determined by uniaxial compressive tests. In vitro studies, such as cell viability and proliferation, adhesion potential, and genotoxicity, were examined by performing an MTT assay, fibronectin adsorption, and plasmid-DNA interaction assay. Experimental results showed that the alloys had a dual-phase microstructure composed of finely dispersed acicular hcp α-Ti needles in the bcc β-Ti matrix. The ultimate compressive strength ranged from 1019 MPa to 767 MPa for alloys with 21–25% porosities and from 173 MPa to 78 MPa for alloys with 50–56% porosities. Noted that adding a space holder agent played a more critical role in the mechanical behaviors of the alloys compared to adding niobium. The pores were largely open and exhibited irregular shapes, with uniform size distribution, allowing for cell ingrowth. Histological analysis showed that the alloys studied met the biocompatibility criteria required for orthopaedic biomaterial use.EPSRC Future LiME Hub (EP/N007638/1); PhD studentship, the Republic of Turkey Ministry of National Education

Resistance fluctuations and Aharonov-Bohm-type oscillations in antidot arrays in the quantum Hall regime

Resistance fluctuation phenomenon in antidot lattices in the quantum Hall regime are studied. Magnetoresistance of finite antidot array systems in the quantum Hall plateau transition regime exhibits two types of oscillatory effect. One is the aperiodic resistance fluctuations (RFs) and the other is the Aharonov-Bohm (AB)-type oscillations. Their dependences on the magnetic field and the gate voltage are quite distinct. While the aperiodic RFs are attributed to the complex evolution of the conducting network of compressible channels, the AB-type oscillations are interpreted in terms of edge states formed around individual antidots. The self-consistent screening effect is important for the both phenomenon, whereas, the single electron charging effect plays a minor role in the present case.Comment: 5 pages, 4 figure

Potential Role of Stabilized Criegee Radicals in Sulfuric Acid Production in a High Biogenic VOC Environment

We present field observations made in June 2011 downwind of Dallas-Fort Worth, TX, and evaluate the role of stabilized Criegee radicals (sCIs) in gaseous sulfuric acid (H2SO4) production. Zero-dimensional model calculations show that sCI from biogenic volatile organic compounds composed the majority of the sCIs. The main uncertainty associated with an evaluation of H2SO4 production from the sCI reaction channel is the lack of experimentally determined reaction rates for sCIs formed from isoprene ozonolysis with SO2 along with systematic discrepancies in experimentally derived reaction rates between other sCIs and SO2 and water vapor. In general, the maximum of H2SO4 production from the sCI channel is found in the late afternoon as ozone increases toward the late afternoon. The sCI channel, however, contributes minor H2SO4 production compared with the conventional OH channel in the mid-day. Finally, the production and the loss rates of H2SO4 are compared. The application of the recommended mass accommodation coefficient causes significant overestimation of H2SO4 loss rates compared with H2SO4 production rates. However, the application of a lower experimental value for the mass accommodation coefficient provides good agreement between the loss and production rates of H2SO4. The results suggest that the recommended coefficient for the H2O surface may not be suitable for this relatively dry environment

Gizli Dinlemeye Karşı Önlemlerin Kablosuz Algılayıcı Ağ Yaşam Süresine Etkisi

26th IEEE Signal Processing and Communications Applications Conference (2018 : Izmir, Turkey)Wireless sensor networks (WSNs) consist of tiny sensor nodes distributed over a specific geographical area. Eavesdropping can be considered as an attack against WSNs when an adversary node overhears the transmissions among the sensor nodes. Hence a WSN needs to minimize the risk of overhearing in order to operate safely. One of the most important performance metrics of WSNs is network lifetime. Decreasing the transmission power levels of the nodes in order to reduce the overhearing can negatively affect the network lifetime due to the suboptimal routing paths that are used. In this study, two optimization models are developed to jointly reduce eavesdropping and increase the network lifetime. The analysis of the relationship between eavesdropping and network lifetime is investigated by using the proposed optimization models. As a result of this study, it was observed that the minimum reduction of eavesdropping causes a significant decrement in network lifetime and when the overhearing limit is extended to a certain level, the network lifetime converges to the maximum.Kablosuz algılayıcı ağlar (KAA) belirli bir coğrafi alana dağılmış küçük algılayıcı düğümlerden oluşmaktadır. Hedeflenen düğüm çiftleri dışında diğer düğümlerin haberleşme menziline girmesi gizli dinleme (kulak misafirligi) olarak bilinmektedir. Gizli dinleme KAA’lara karşı bir saldırı olarak nitelendirilmekte olup KAA’nın güvenli biçimde çalışması için gizli dinlenme riskinin en aza indirgenmesi gerekmektedir. KAA’ların en önemli performans metriklerinden birisi ag yaşam süresidir. Gizli dinlemeyi azaltmak adına dügümlerin iletim güç seviyelerinin düşürülmesi en iyi olmayan yönlendirme kararlarının kullanılmasına bu da agın yaşam süresinin olumsuz etkilenmesine yol açar. Bu çalışmada, gizli dinlemeyi en aza indirmeye ve ağ yaşam süresini belirli bir gizli dinleme kısıtı altında en büyüklemeye yönelik iki eniyileme modeli tasarlanmıştır. Gizli dinleme ve ağ yaşam süresi arasında ilişkinin analizi tasarlanan eniyileme modelleri yardımı ile incelenmiştir. Bu çalışma sonucunda, gizli dinlemeyi minimuma indirgemenin ağ yaşam süresinde azımsanmayacak ölçüde düşüşe neden oldugu gözlenmiş olup gizli dinleme sınırı belli miktarda genişletildiginde ağ yaşam süresinin maksimum seviyeye çıktıgı görülmüştür