Synthesis,structural model and vibrational spectroscopy of lutetium tricalcium phosphate Ca9Lu(PO4)7

Lutetium β-tricalcium phosphate Ca_9Lu(PO_4)_7 was synthesized by solid-state reaction at 1200 ℃,and investigated by means of a combination of scanning electron microscopy(SEM) equipped with energy dispersive X-ray spectroscopy(EDS), X-ray diffraction(XRD), Fourier transform infrared(FTIR) and Raman spectroscopies. SEM morphological analysis reveals the presence of sub spherical and prismatic micro crystalline aggregates, while EDS semi-quantitative analysis confirms the nominal Lu/Ca composition. The unit cell and the space group were determined by X-ray powder diffraction data showing that the compound crystallizes in the rhombohedral R3c whitlockite-type structure, with unit cell constants a = b = 1.04164(1) nm, c = 3.7302(1) nm and cell volume V = 3.5051(1) nm~3. The investigation was completed with the structural refinement by the Rietveld method, and discussion of the distribution of Lu within cationic sites according to the results of the Rietveld refinement. The FTIR and Raman spectra,correlated to isostructural rare earth phosphates from literature, show slight band shifts of the phosphate modes correlated to the evolving size of the rare earth elements.     

Effect of Nano-Sized ZnO on the Physical Properties of (Cu0.5Tl0.25Pb0.25)Ba2Ca2Cu3O10?δ

High-temperature superconductor phase of (Cu_0.5Tl_0.25Pb_0.25)-1223 was synthesized by solid-state reaction technique and characterized using X-ray powder diffraction (XRD). XRD analysis revealed that the prepared sample was nearly monophase and exhibited tetragonal structure with space group P4/mmm. Nano-zinc-oxide, prepared by Co-precipitation method, was added to the sample. ZnO-concentrations y varied from 0.0 to 2.0 wt.% of the sample’s mass. The prepared samples were investigated through XRD, scanning electron microscope (SEM), energy dispersive X-ray (EDX), particle size analyzer (PSA), differential scanning calorimeter (DSC), electrical resistivity and transport critical current density measurement. X-ray data analysis showed that the nano-Zn addition does not affect the tetragonal structure of (Cu_0.5Tl_0.25Pb_0.25)-1223 phase, whereas the lattice parameters showed an insignificant variation. The results of the superconducting transition temperature, the transport critical current density and melting point of the prepared samples were found to depend on nano-ZnO concentrations.     

Laboratory study of the effect of RAP conditioning on the mechanical properties of hot mix asphalt containing RAP

This paper evaluates the effect of reclaimed asphalt pavement (RAP) laboratory conditioning on the rheological properties of recycled hot-mix asphalt. Four different conditioning processes were used on a single RAP source before mixing: unheated RAP, RAP heated at 110 °C in a microwave, RAP heated in a covered pan at 110 °C in a draft oven, and RAP heated in a non-covered pan at 110 °C in a draft oven. Dense graded 20 mm HMA was designed using a PG 64-28 binder and mixed with 25 % of the four different conditioned RAPs. Thermal stress restrained specimen test (TSRST) and complex modulus test were used to characterize RAP conditioning effect. Test results showed that the complex modulus of the four mixes has no different rheological behaviour, and did not affect TSRST results as much.     

High Resolution Study of Micrometer Particle Detachment on Different Surfaces

In an effort to identify particle initial motion prior liftoff interactions of micrometer glass beads (10–100 μm) on glass, ceramic, and hardwood substrates were investigated experimentally. Particles were deposited on the lower surface of a 10 cm² wind tunnel by gravitational settling. Air flows were imposed from an open entrance at average velocities up to 16 m/s. Individual particle trajectories obtained by high-speed imaging reveal three different types of motion: rolling/bouncing (saltation caused by the movement of hard particles over an uneven surface in a turbulent flow of air), immediate liftoff (particles completely leave the surface with no or minimal initial rolling/bouncing) and complex motion (particles travel with rolling/bouncing motion on the surface for a certain distance before final liftoff). Surface roughness significantly affects the particle initial motion prior to liftoff. The majority of particle trajectories from the glass substrate were parallel to the surface with complex motion. Hardwood substrates took the longest time for initial particle movement (t >1 s) causing a more rapid liftoff. The ceramic substrate showed the most rolling/bouncing motion, for 80% of the particles. The detachment percentage initially follows an exponentially increasing trend for a period of ～1 s, followed by a plateau phase for a period of 5 s. Changing the velocity, substrate, and particle size significantly affects particle detachment. Incorporating the different types of particle motion prior to liftoff into detachment mode models, and understanding how their relative contributions change with different particle and substrate materials, can potentially yield improved predictive capabilities.

Copyright 2013 American Association for Aerosol Research     

Facile polyacrylamide graft based on poly (2-chloroaniline) silver nano-composites as antimicrobial

Series of polymers based on the grafting of polyacrylamide with both poly(2-methoxyaniline) P2-MeOANI and poly(2-chloroaniline) P2-ClANI were synthesized by the oxidative chemical grafting copolymerization of individually 2-methoxyaniline (2-MeOANI) and 2-chloroaniline (2-ClANI) onto polyacrylamide (PACM). The grafting was performed in aqueous hydrochloric acid solution (HCl) using ammonium persulfate (APS) as oxidant. The optimum conditions of the grafting based on the yield was achieved. The obtained polymer samples at optimum conditions were assembling on colloidal silver nanoparticles (AgNPs). The obtained polymer samples and their AgNPs were characterized by UV- visible & IR spectroscopy, EM, TEM & TGA to confirm the suggested structure of obtained polymers. The efficiency of the prepared polymeric samples to using as anti-microbial including as sulfate reducing bacteria (SRB) was investigated.     

First-principle calculations of electronic and ferromagnetic properties of $$\hbox {Al}_{1-x}\hbox {V}_{x}\hbox {Sb}$$

We have used the first-principle calculations of density functional theory within full-potential linearized augmented plane-wave method to investigate the electronic and ferromagnetic properties of \(\hbox {Al}_{1-x}\hbox {V}_{x}\hbox {Sb}\) alloys. The electronic structures of \(\hbox {Al}_{0.25}\hbox {V}_{0.75}\hbox {Sb}, \hbox {Al}_{0.5}\hbox {V}_{0.5}\hbox {Sb}\) and \(\hbox {Al}_{0.75}\hbox {V}_{0.25}\hbox {Sb}\) exhibit a half-metallic ferromagnetic character with spin polarization of 100 %. The total magnetic moment per V atom for each compound is integral Bohr magneton of 2 \(\mu _{\mathrm{B}}\), confirming the half-metallic feature of \(\hbox {Al}_{1-x}\hbox {V}_{x}\hbox {Sb}\). Therefore, these materials are half-metallic ferromagnets useful for possible spintronics applications.     

Recommendation using a clustering algorithm based on a hybrid features selection method

The cold start problem is a potentiel problem in Recommender Systems (RSs). It concerns the inability of the system to infer recommendaation for new users or new items about wich it has not enough iformation. Specifically, when an item is new, the system may fail to perform well due to the insufficiency of available information for this item. The most common solution addressed in the literature consists in combining the content and collaborative information under a single RS. However these hybrid solutions inherit the classical problems of natural language ambiguity and don’t exploit semantic knowledge in their items representations. In this paper, we propose a hybrid RS composed of three modules to surpass those weaknesses. The first one is rested on a powerful content clustering algorithm; which uses a Hybrid Features Selection Method (HFSM). It combines statistical and semantic relevant features to get the maximum profit from the content of items. The second module is the Collaborative Filtering (CF) one, which depends only on users’ ratings. The third one combines the previous modules to solve the problem of missing values in CF approach and to handle new-item issue. The proposed hybrid Recommender is evaluated against traditional item-based CF in different settings: no cold-start situation and a simulation of a new-item scenario (an item with few/ no ratings). The conducted experiments show the ability of the proposed hybrid recommender to deliver more accurate predictions for any item and its outperformance on the classical CF approach, which fails in cold-start situations.     

A novel etched-substrate mechanism for characteristics improvement of X-band broadband printed monopole antenna

A unique tiny wideband antenna with improvements in fundamental features is offered. The antenna consists of a crown-shaped patch and an incomplete ground plane. The proposed patch shape is constructed by introducing multiple truncated circular-shaped arcs, which help to enhance the performance of the designed antenna. A unique strategy of etching the substrate structure, is integrated which aims to provide a useful solution for the excitation of the surface waves within the microstrip antenna. The essential attributes including impedance bandwidth and radiation efficiency of the recommended antenna are strengthened after the removal of these portions. The recommended antenna can be used for X-band applications with a compact size of 30 × 30 mm². The usable impedance bandwidth (S₁₁  ≤ 10 dB) covered by the proposed antenna is 6.2 GHz and ranges from 5.8 to 12 GHz. The antenna is experimentally tested to confirm the outcomes of the simulation thus, a satisfactory agreement is reached between simulated and measured results that prove the antenna’s validity for wideband operations.