Effects of Fe2O3 Nanoparticles on Water Permeability and Strength Assessments of High Strength Self-Compacting Concrete

In this work,compressive,flexural and split tensile strength together with coefficient of water absorption of high performance self-compacting concrete containing different amount of Fe2O3 nanoparticles have been investigated.The strength and the water permeability of the specimens have been improved by adding Fe2O3 nanoparticles in the cement paste up to 4.0 wt%.Fe2O3 nanoparticle as a foreign nucleation site could accelerate C-S-H gel formation as a result of increased crystalline Ca(OH)2 amount especially at the early age of hydration and hence increase the strength of the specimens.In addition,Fe2O3 nanoparticles are able to act as nanofillers and recover the pore structure of the specimens by decreasing harmful pores to improve the water permeability.Several empirical relations have been presented to predict the flexural and the split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing.Accelerated peak appearance in conduction calorimetry tests,more weight loss in thermogravimetric analysis and more rapid appearance of peaks related to hydrated products in X-ray diffraction results indicate that Fe2O3 nanoparticles up to 4 wt% could improve the mechanical and the physical properties of the specimens.     

Synthesis,radiolabelling, and biological assessment of folic acid‐conjugated G‐3 99m Tc‐dendrimer as the breast cancer molecular imaging agent

Hence, in this study, the authors aimed to develop a dendrimer‐based imaging agent comprised of poly(ethylene glycol) (PEG)‐citrate, technetium‐99 m (^99m Tc), and folic acid. The dendrimer‐G3 was synthesised and conjugated with folic acid, which confirmed by Fourier transform infrared, proton nuclear magnetic resonance, dynamic light scattering, and transition electron microscopy. 2,3‐bis‐(2‐methoxy‐4‐nitro‐5‐sulfophenyl)‐2H‐Tetrazolium‐5‐Carboxanilide cytotoxicity assay kit was used to measure the cellular toxicity of dendrimer. Imaging and biodistribution studies were conducted on the mice bearing tumour. The results showed that the fabricated dendrimer‐G3 has a size of 90 ± 3 nm, which was increased to 100 ± 4 nm following the conjugation with folic acid. The radiostablity investigation showed that the fabricated dendrimers were stable in the human serum at various times. Toxicity assessment confirmed no cellular toxicity against HEK‐293 cells at 0.25, 0.5, 1, 2, 4, and 8 mg/μl concentrations. The in vivo studies demonstrated that the synthesised dendrimers were able to provide a bright SPECT image applicable for tumour detection. In conclusion, the authors’ study documented the positive aspects of PEG‐citrate dendrimer conjugated with folic acid as the SPECT contrast agent for breast cancer detection.Inspec keywords: toxicology, single photon emission computed tomography, technetium, cancer, bone, polymers, biochemistry, tumours, electrospinning, biomedical materials, light scattering, cellular biophysics, Fourier transform infrared spectra, proton magnetic resonance, transmission electron microscopy, biological organsOther keywords: biodistribution, toxicity assessment, cellular toxicity, bright SPECT image, PEG‐citrate dendrimer, breast cancer molecular imaging agent, proton nuclear magnetic resonance, dendrimer‐based imaging agent, folic acid‐conjugated G‐^399m Tc‐dendrimer, dendrimer‐G3, poly(ethylene glycol)‐citrate, Fourier transform infrared spectra, dynamic light scattering, transition electron microscopy, 2,3‐bis‐(2‐methoxy‐4‐nitro‐5‐sulfophenyl)‐2H‐tetrazolium‐5‐carboxanilide cytotoxicity assay, human serum, tumour detection     

Analysis of nonuniform transmission lines using Fourier series expansion

A new method is introduced for frequency domain analysis of arbitrary lossy and dispersive nonuniform transmission lines (NTLs). In this method, all distributed primary parameters of the line are expanded in Fourier series and also a periodic NTL is made from cascading infinite number of desired NTL. The ABCD parameters of desired NTL are obtained after finding the propagation constant and the characteristic impedances of its periodic model. The validity of the method is verified using analysis of some special types of lines. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

Wideband RCS reduction using polarization cancelation method

Polarization cancelation method to reduce the monostatic radar cross section (RCS) is investigated thoroughly. The inherent bandwidth of rotatable unit cells is determined. Also, 0‐dB RCS reduction bandwidth of any arbitrary method including polarization cancelation method is investigated. A special unit cell is proposed to reduce RCS over 100% fractional bandwidth. Finally, a structure is fabricated and measured so that results in verifying the performance of the proposed unit cell.     

Analysis of coupled or single nonuniform transmission lines using the method of moments

A method is proposed for the analysis of arbitrarily loaded lossy and dispersive single or coupled nonuniform transmission lines (NTLs). In this method, the integral equations of the NTLs, converted from their differential equations, are solved using the method of moments. It is assumed that per‐unit‐length matrices are known at all or even some points along the length of the coupled NTLs. The validity of the method is verified using a comprehensive example. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Nonuniform reflect‐array antennas

A center‐fed reflect‐array antenna with nonuniform substrate as a reflecting surface is proposed. To design and analyze this kind of antennas, a simple method based on an equivalent circuit model is introduced. Using this method a low cross‐polarization of about ?21 dB below the main beam peak and wide 3‐dB gain bandwidth of 19.5% are obtained at X‐band frequency. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

Using linear sections instead of uniform ones to analyze the coupled nonuniform transmission lines

In this article, a new method is introduced to frequency domain analyze arbitrary coupled nonuniform transmission lines (CNTLs). The CNTLs are subdivided into several short linear sections instead of uniform sections. The chain parameter matrix of linear sections is obtained by expressing the voltages and currents by power series expansion. This method is applicable to all arbitrary CNTLs. The accuracy of the proposed method is verified using a comprehensive example. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Synthesis of linear and planar arrays with sidelobes of individually arbitrary levels

A procedure is presented to synthesize linear and planar antenna arrays to have individually arbitrary sidelobe levels. This procedure is based on perturbation of the zeros of radiation pattern and is applicable for both sum‐ and difference‐type radiation patterns. Planar antenna arrays are synthesized by transforming synthesized linear arrays to planar arrays. The synthesized planar arrays would have ring type sidelobes. Some examples are brought to verify the effectiveness of the proposed procedure for both linear and planar arrays with sum or difference radiation patterns.     

Synthesis of circular arrays with sidelobes of individually arbitrary levels

Synthesis of circular antenna arrays to have individually arbitrary sidelobe levels, is investigated. Circular arrays are synthesized by applying a transformation to previously designed linear arrays. The antennas of the circular arrays are considered either isotropic or directive. The synthesized patterns are steerable without any distortion. Some examples are brought to verify the effectiveness of the proposed procedure for both isotropic and directive antennas.     

Modeling hardness of Nb-microalloyed steels using fuzzy logic

The paper presents some results of the research connected with the development of new approach based on the fuzzy logic of predicting the Vickers microhardness of the phase constituents occurring in five steels after continuous cooling. The independent variables in the model are chemical compositions, initial austenite grain size, and cooling rate over the temperature range of the occurrence of phase transformations. For purpose of constructing these models, 114 different experimental data were gathered from the literature. The data used in the fuzzy logic model are arranged in a format of twelve input parameters that cover the chemical compositions, initial austenite grain size, and cooling rate, and output parameter which is Vickers microhardness. In this model, the training and testing results in the fuzzy logic systems have shown strong potential for prediction of effects of chemical compositions and heat treatments on hardness of microalloyed steels.