Alert-QSAR. Implications for Electrophilic Theory of Chemical Carcinogenesis

Given the modeling and predictive abilities of quantitative structure activity relationships (QSARs) for genotoxic carcinogens or mutagens that directly affect DNA, the present research investigates structural alert (SA) intermediate-predicted correlations A(SA) of electrophilic molecular structures with observed carcinogenic potencies in rats (observed activity, A = Log[1/TD(50)], i.e., [Formula: see text]). The present method includes calculation of the recently developed residual correlation of the structural alert models, i.e., [Formula: see text]. We propose a specific electrophilic ligand-receptor mechanism that combines electronegativity with chemical hardness-associated frontier principles, equality of ligand-reagent electronegativities and ligand maximum chemical hardness for highly diverse toxic molecules against specific receptors in rats. The observed carcinogenic activity is influenced by the induced SA-mutagenic intermediate effect, alongside Hansch indices such as hydrophobicity (LogP), polarizability (POL) and total energy (Etot), which account for molecular membrane diffusion, ionic deformation, and stericity, respectively. A possible QSAR mechanistic interpretation of mutagenicity as the first step in genotoxic carcinogenesis development is discussed using the structural alert chemoinformation and in full accordance with the Organization for Economic Co-operation and Development QSAR guidance principles.     

The Synthesis and Characterization of Star Shaped Metal Complexes of Triazine Cored Schiff Bases: Their Thermal Decompositions and Magnetic Moment Values

Tripodal ligand III, 2,4,6-tris(4-hydroxybenzimino)-1,3,5-triazine, was synthesized by reacting melamine with 4-hydroxybenzaldehyde. (E)-4-Bromo-2-((2-bromoethylimino)-methyl)phenol VI was obtained by reaction of 5-bromo-2-hydroxybenzaldehyde and 2-bromoethanamine hydrochloride. Melamine cored tripodal Schiff base VII (H₃L) was synthesized by reacting III with VI. Tripodal metal complexes were obtained by reacting H₃L and transition metal salts. The complexes were characterized by elemental analyses, FT-IR, ¹H NMR and LC–MS spectroscopy, thermal analyses and magnetic measurements. Finally, metal ratios of the complexes were determined by atomic absorption spectroscopy. The complexes are square-planar low-spin (S = 1/2) Co(II), diamagnetic square-planar Ni(II), square-planar (S = 1/2) Cu(II) and diamagnetic tetrahedral Zn(II).     

LaScO3 as a higher-κ dielectric for p-MOSFETs

The electrical properties of MOS capacitors with LaScO₃ thin films grown by molecular beam deposition (MBD) have been studied with and without post deposition annealing (PDA) in O₂ environment followed by forming gas. An EOT of 0.65 nm could be achieved for samples without PDA. However, the films suffer from large hysteresis and interface trap density. Applying PDA reduces the hysteresis, the D_it (down to the mid of 10¹¹ (eV cm²)⁻¹) and the leakage current by two orders of magnitude (down to the range of 10⁻⁴A/cm²) for an EOT of 1.1 nm. Furthermore we have successfully integrated LaScO₃ into FD MOSFETs on SOI substrates. The p-FETs with LaScO₃ show excellent characteristics with a steep subthreshold slope down to 65 mV/dec and hole mobilities comparable to HfO₂ and HfSiON.     

Dependence of Electrical Resistivity on Temperature and Sn Content in Pb-Sn Solders

Pb_(100−x)-Sn _x solders (x = 5 wt.%, 10 wt.%, 20 wt.%, 35 wt.%, 50 wt.%, 60 wt.%, 61.9 wt.%, and 95 wt.%) were directionally solidified upward with a constant growth rate (V = 37.4 μm/s) in a temperature gradient (G = 4.8 K/mm) in a Bridgman-type growth apparatus. The variations of electrical resistivity (ρ) with temperature in the range of 323 K to 423 K for the directionally solidified Pb-Sn solders were measured. The present measurements indicate that the electrical resistivity of the directionally solidified Pb-Sn solders increases with increasing temperature, whereas the resistivity of the Pb-Sn solders decreases with increasing Sn content. The dependency of the Lorenz number (L) on temperature and Sn content for the Pb-Sn solders was also investigated based on the Wiedemann–Franz law by using the measured values of the thermal (K) and electrical (σ) conductivity for the same alloys.     

Thermal stresses in orthotropic Cosserat elastic cylinders

Abstract

This paper is concerned with the equilibrium theory of orthotropic Cosserat continua. We study the thermoelastic deformation of a beam which is subjected to a prescribed thermal field. The work is motivated by the recent interest in the using of the orthotropic Cosserat elastic solid as a model for bones and various engineering materials with microstructure. The temperature variation is a assumed to be independent of the axial coordinate. First, we investigate the case of a homogeneous solid. Then we study the deformation of a beam which is composed by two materials welded together along the surface of separation. The solution could be used to investigate the behavior of bone implants. We present some results concerning the plane strain problem of orthotropic beams and reduce the three-dimensional problem to the study of some plane problems. The results are used to investigate the deformation of a circular beam subjected to a uniform thermal field.     

Distributed Coalition Formation Games for Secure Wireless Transmission

Cooperation among wireless nodes has been recently proposed for improving the physical layer (PHY) security of wireless transmission in the presence of multiple eavesdroppers. While existing PHY security literature answered the question “what are the link-level secrecy rate gains from cooperation?”, this paper attempts to answer the question of “how to achieve those gains in a practical decentralized wireless network and in the presence of a cost for information exchange?”. For this purpose, we model the PHY security cooperation problem as a coalitional game with non-transferable utility and propose a distributed algorithm for coalition formation. Using the proposed algorithm, the wireless users can cooperate and self-organize into disjoint independent coalitions, while maximizing their secrecy rate taking into account the costs during information exchange. We analyze the resulting coalitional structures for both decode-and-forward and amplify-and-forward cooperation and study how the users can adapt the network topology to environmental changes such as mobility. Through simulations, we assess the performance of the proposed algorithm and show that, by coalition formation using decode-and-forward, the average secrecy rate per user is increased of up to 25.3 and 24.4% (for a network with 45 users) relative to the non-cooperative and amplify-and-forward cases, respectively.     

Application of a continuously stirred tank bioreactor (CSTR) for bioremediation of hydrocarbon-rich industrial wastewater effluents

A continuously stirred tank bioreactor (CSTR) was used to optimize feasible and reliable bioprocess system in order to treat hydrocarbon-rich industrial wastewaters. A successful bioremediation was developed by an efficient acclimatized microbial consortium. After an experimental period of 225 days, the process was shown to be highly efficient in decontaminating the wastewater. The performance of the bioaugmented reactor was demonstrated by the reduction of COD rates up to 95%. The residual total petroleum hydrocarbon (TPH) decreased from 320 mg TPH l(-1) to 8 mg TPH l(-1). Analysis using gas chromatography-mass spectrometry (GC-MS) identified 26 hydrocarbons. The use of the mixed cultures demonstrated high degradation performance for hydrocarbons range n-alkanes (C10-C35). Six microbial isolates from the CSTR were characterized and species identification was confirmed by sequencing the 16S rRNA genes. The partial 16S rRNA gene sequences demonstrated that 5 strains were closely related to Aeromonas punctata (Aeromonas caviae), Bacillus cereus, Ochrobactrum intermedium, Stenotrophomonas maltophilia and Rhodococcus sp. The 6th isolate was affiliated to genera Achromobacter. Besides, the treated wastewater could be considered as non toxic according to the phytotoxicity test since the germination index of Lepidium sativum ranged between 57 and 95%. The treatment provided satisfactory results and presents a feasible technology for the treatment of hydrocarbon-rich wastewater from petrochemical industries and petroleum refineries.     

Influence of copper morphology in forming nucleation seeds for graphene growth

We report that highly crystalline graphene can be obtained from well-controlled surface morphology of the copper substrate. Flat copper surface was prepared by using a chemical mechanical polishing method. At early growth stage, the density of graphene nucleation seeds from polished Cu film was much lower and the domain sizes of graphene flakes were larger than those from unpolished Cu film. At later growth stage, these domains were stitched together to form monolayer graphene, where the orientation of each domain crystal was unexpectedly not much different from each other. We also found that grain boundaries and intentionally formed scratched area play an important role for nucleation seeds. Although the best monolayer graphene was grown from polished Cu with a low sheet resistance of 260 Ω/sq, a small portion of multilayers were also formed near the impurity particles or locally protruded parts.     

The effect of arginine on gold nanoparticles in colloidal solutions and in thin films

Gold nanoparticles were prepared in aqueous colloidal solutions and their interaction with L-arginine solutions at different concentrations was investigated by UV-vis spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM). The shift towards red of the absorption maximum of gold nanoparticles with increasing L-arginine concentration and in time, and the apparition of a new large band at higher wavelength evidence the formation of assemblies of gold nanoparticles, mediated by the amino acid. TEM images present the progress in the building process of supermolecular structures. Further, the AFM images show the self assemblies of gold nanoparticles capped with L-arginine well ordered in large domains on silanized glass. As a model for the process, we suggest that the positively charged guanidinium group of L-arginine is anchored on the negative citrate capped gold nanoparticles, while the other two functionalities of L-arginine are involved in the bonding between gold nanoparticles. The ability of arginine to specifically bind gold nanoparticles could lead to an increased ability of proteins, containing arginine, to specifically bind to nanogold. Then, they bind other target proteins or different ligands underlying numerous biological and medical applications that range from nanoscale biosensors, cell-cell communications to targeted delivery of drugs to cancer cells.     

Greenway Planning Context in Istanbul-Haliç: A Compulsory Intervention into the Historical Green Corridors of Golden Horn

In the last two decades, planners and landscape architects have been concerned with the open space planning concept called ‘greenway planning’. This approach aims at nature protection that balances both conservation and growth, creating livable environments and maintaining open spaces. In Istanbul, the functional and spatial connectivity of greenways can protect the local landscape against urbanization and population growth problems. This study aimed to emphasize the natural and cultural heritage in an ecologically based planning approach. After taking into consideration the current greenway planning process in Europe and America, a planning strategy was determined for Haliç reflecting all characteristics of Istanbul and possibly representing the first greenway example in the city. Haliç was degraded by industrialization, urbanization, migration and inappropriate land use plans through the ages and existing greenway corridors had disappeared. As a result, current greenway planning strategies were foreseen as a solution to prevent threats to heritage and re-emphasize the lost identity of Haliç. It was emphasized as the starting point of a greenway plan that could be applied for Istanbul in general.