In the present study, bulk nanocrystallineCu(99.5)Zr(0.5), Cu99Nb1.0, and Cu(98.5)Zr(0.5)Nb(1.0)alloys have been synthesized by using mechanical alloying followed by hot pressing (HP) at 550 degrees C. Further, these asfabricated alloys were annealed at 800 degrees C and 900 degrees C for 1 h to investigate the structure-property correlation. Grain size and phase identification has been carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM). While mechanical properties were investigated using Vickers hardness and shear punch test (SPT). The grain size of the as-processed alloys was found to remain nanosized 41 +/- 2.2 nm in Cu99.5Zr0.5(CZ), 50 +/- 1.5 nm in Cu99Nb1.0(CN) and 26 +/- 1.2 nm in Cu98.5Zr0.5Nb1.0(CNZ) even after annealing at 900 degrees C. This is attributed to the stabilization of the nanosize grains by segregation of solute atoms (Nb and Zr) along grain boundaries and/or Zenner pinning by intermetallic precipitates like Cu5Zr in CZ and CNZ alloys. (C) 2020 Elsevier B.V. All rights reserved.

Pharmacologically active compounds having poor permeability through several physiological barriers often limits their application. New age therapeutics such as peptides or nucleic acid-based agents are promising but their targeted delivery to the brain is challenging through conventional drug delivery methods. The objective of using carbon nano onions is to develop potential nanoscale carriers for effective diagnosis and targeted therapies. Pharmacokinetic and pharmacodynamic profiles of such nanocarriers can also be controlled, enhancing the drug concentration at target sites.This review critically evaluates the current status of the carbon nano onion mediated targeted delivery of the drugs through nasal pathway bypassing the biological barriers.This intranasal drug delivery system can escape the first-pass metabolism, increases the bioavailability of the drug to the targeted area reduces the dose of chemotherapeutic reagents having serious side effects.

Nanostructured Cu98Cr2–W composite powder was synthesized by high-energy ball milling and consolidated by spark plasma sintering (SPS). For comparison, pure Cu and Cu98Cr2 composite were also prepared under similar condition. Phase and microstructural characterization was carried out by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Hardness, wear property and electrical conductivity of the composite was evaluated and compared with pure Cu and Cu98Cr2 composite. The Cu98Cr2–W composite, show ~5% and ~21% higher hardness compared to Cu98Cr2 and pure Cu respectively. It also shows significant improvement in wear property and electrical conductivity, which makes the newly developed composite a potentially better candidate for high voltage circuit breaker application over existing Cu–Cr based composites.

Nanostructured Cu98Cr2/W composite powder was synthesized at various milling time through high-energy planetary ball milling cryogenically and consolidated at various temperatures (1073 K (800 degrees C) and 573 K (300 degrees C) respectively) by spark plasma sintering (SPS). Further, the detailed characterisation is being investigated through X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM analysis shows complete solid solubility of Cr however, W does not form any solid solution at any of the processed parameters. The presence of the W stabilizes the grain at nano level in the powdered as well as sintered sample which is due to Orowan strengthening. Thereby, increasing the hardness of the as processed composite processed at 300 degrees C. (C) 2019 Elsevier B.V. All rights reserved.

Microstructure and magnetic behavior of nanocrystalline 50Cu–40Co–10Si(at%) alloy prepared by mechanical alloying and subsequent isothermal annealing in the temperature range of 450–650°C have been studied. Phase evolution during mechanical alloying and isothermal annealing is characterized by X-ray diffraction (XRD), differential thermal analyzer (DTA), high resolution transmission electron microscopy (HRTEM) and magnetic measurement. Addition of Si has been found to facilitate the metastable alloying of Co in Cu resulting into the formation of single phase solid solution having average grain size of 9nm after ball milling for 50h duration. Annealing of the ball milled alloy improves the magnetic properties significantly and best combination of magnetic properties has been obtained after annealing at 550°C for 1h duration.

In order to improve solubility and magnetic properties, the ball milling technology was used for the production of 50Cu–40Fe–10Mn (wt%) alloy. The effect of Mn content on the microstructure and magnetic properties of Cu–Fe alloy was also investigated in detail. Microstructure and magnetic properties of the alloy were analyzed by X-ray diffraction, differential scanning calorimetry, high resolution transmission electron microscopy and superconducting quantum interface device magnetometry. The results showed that a complete solid solution of the alloy was produced after 30h of milling. Quantitative phase analysis of X-ray diffraction data revealed that the milled alloy obtained after isothermal annealing at 550°C for 1h consisted of Cu (54.52wt%), α-Fe (36.49wt%) and MnO (8.99wt%). The milled alloy obtained after annealing at 450°C for 1h leads to the maximum values of magnetic properties such as coercivity=438Oe, remanent magnetization=14.3emu/g, and saturation magnetization=51emu/g.

The current state of studies presents the effect of ternary addition of transition elements such as Mn, Cr and Si (10wt%) on the mechanically driven non-equilibrium solubility of 40wt% Co containing Cu–Co alloy. X-ray powder diffraction analysis indicates that addition of Mn has been found to be the most effective in enhancing the solubility and formation of a complete solid solution between Co and Cu in a short duration (30h) of ball milling. The microstructure of the ball milled CuCoMn alloy was found to be stable after the isothermal annealing up to a temperature of 450°C for 1h. The magnetic properties such as magnetic saturation, coercivity and remanence of ball milled CuCo alloy in the presence of Mn significantly altered after annealing in the temperature range 350–650°C for 1h. The best combination of magnetic properties of CuCoMn alloy has been found after annealing at 550°C for 1h.

The Cu-Ni-Co-Fe alloys with average grain size~10nm have been prepared by mechanical alloying. The ball milled and annealed samples were characterized by XRD, HRTEM and magnetic measurement. In the case of ball milled sample, superior magnetic properties have been achieved for sample comprising dispersed magnetic phases in Cu-rich matrix. In the case of annealed sample magnetic properties are improved due to precipitation of hard magnetic phase Co(fcc) from single phase Cu-rich solid solution.

Nanocomposites of Fe–NiO are synthesized by the mechanical milling technique. The phase purity of the sample was checked by X-ray diffraction (XRD), which shows only lines of α-Fe and NiO. Transmission electron microscopy (TEM) measurements confirmed a homogeneous dispersion of α-Fe nanoparticles in NiO matrix. Magnetic hysteresis measurements showed an enhancement in coercivity at room temperature with increasing milling durations and presence of exchange bias field. With increasing milling durations, the exchange field is found to increase while blocking temperature decreased. Presence of defects in Fe–NiO nanocomposites ball-milled for prolonged durations is confirmed by positron annihilation lifetime spectroscopy (PALS) measurements. Mössbauer spectroscopic measurements reveal that Fe nanoparticles are in the blocked state though their size is less than the critical size for becoming single domain and superparamagnetic. This is attributed to strong exchange coupling between the ferromagnetic and antiferromagnetic moments.

Ultrafine nanoparticles owing to their increased surface to volume ratio, coupled with the ability to tune their surface properties through molecular modification have made them ideal for their detection and remediation of broad range of environmental contaminants. Arsenic contamination has become a worldwide epidemic and remediation of this problem needs the development of technology with improved materials and systems with high efficiency. In the present study, we have demonstrated a simple and efficient method using surface functionalized ultrafine iron oxide nanoparticles for absolute removal of arsenic from arsenic treated water with low contact time period and low adsorbent dose. The efficiency of arsenic removal has been drastically improved by considering nanoparticles of size 10 nm and subsequent surface engineering of the nanoparticles resulting more adsorption sites being exposed to arsenic. The mechanism for adsorption was identified through electron microscopic and spectroscopic studies. The adsorption equilibrium data were well fitted to Freundlich isotherm.

Arsenic toxicity has become a major concern worldwide. Remediation of this problem needs the development of technology with improved materials and systems with high efficiency. We have demonstrated a simple and efficient method for the absolute removal of As(III) from high concentration As(III) treated water with a low contact time period. The process of As(III) adsorption follows pseudo-second-order kinetic model. The mechanism for high-adsorption efficiency is attributed to fatty acid binding domain-mediated surface conjugation of ultrafine Fe2O3 nanoparticles with As(III). We have also ensured the simultaneous separation of arsenic sorbed nanoparticles by entrapping them in hydrophilic calcium alginate beads and thereby a pure arsenic free solution has been obtained.

The present study concerns correlation of microstructure and magnetic properties of nanocrystalline binary 50Cu–50Co and ternary 50Cu–25Co–25Ni (wt%) alloys prepared by ball milling and subsequent isothermal annealing of the ball milled alloys. High resolution transmission electron microscopic (HR-TEM) investigation has shown deformation-induced microstructural features. Field emission scanning electron microscopy (FE-SEM) has revealed a distinct change in morphology of as-milled CuCoNi alloys after annealing. Differential scanning calorimetric (DSC) and X-ray diffraction (XRD) analysis have revealed that annealing of the CuCoNi alloy above 350°C results into precipitation of nanocrystalline Co (fcc) in the CuNi matrix by spinodal decomposition. It is also demonstrated that isothermal annealing of the ball milled alloys in the temperature range between 350 and 650°C significantly influence the magnetic properties, e.g. coercivity (Hc), remanence (Mr) and magnetic saturation (Ms) due to annihilation of defects such as stacking and twin fault along with dissolution and/or precipitation of magnetic phases in the Cu-rich matrix.

Multiferroic nanoparticles of Bi1-xSrxFeO3 (x = 0, 0.01, 0.03, 0.05 and 0.07) were prepared by a facile sol gel route and the variation of their structural, optical, dielectric and magnetic properties on strontium concentration has been studied. XRD and TEM results confirm the phase purity of the samples having high degree of crystallinity and monodispersity. The average particle size shows an exponential decline with increase in Sr concentration. A shape transformation from a multifaceted polygon to a spherical one has been observed as Sr concentration in the sample increases to 5%. In the second derivative FTIR spectra, the intensity of vibration peak at similar to 593 cm(-1) that is characteristic of rhombohedral BiFeO3 is seen to decrease after Sr doping. All the samples showed typical M H behavior of a ferromagnet with saturation magnetization achieved within an applied magnetic field of 10 kOe. The sample with 3% Sr substitution displayed saturation and remanent magnetization values 1.37 emu/g and 0.32 emu/g respectively that are highest among all the samples studied. Presence of exchange coupling produced due to interaction between the antiferromagnetic core and ferromagnetic shell is also observed in all Bi1-xSrxFeO3 nanoparticles. (C) 2010 Elsevier Masson SAS. All rights reserved.

Arrays of ZnO nanowires (NWs) were fabricated within the well-distributed pores of anodic aluminium oxide (AAO) template by a simple chemical method. The photoluminescence (PL) and field emission (FE) properties of the AAO/ZnO NWs hybrid structure were investigated in detail. The hybrid nanostructure exhibits interesting PL characteristics. ZnO NWs exhibit UV emission at 378nm and two prominent blue-green emissions at about 462 and 508nm. Intense blue emission from the AAO template itself was observed at around 430nm. Herein, for the first time we report the FE characteristics of the ZnO/AAO hybrid structure to show the influence of the AAO template on the FE property of the hybrid structure. It is found that the turn-on electric field of the vertically grown and aligned ZnO NWs within the pores of AAO template is lower than the entangled unaligned ZnO NWs extracted from the template. Although the AAO template exhibits no FE current but it helps to achieve better FE property of the ZnO NWs through better alignment. The turn-on electric field of aligned NWs was found to be 3Vμm−1 at a current of 0.1μA. Results indicate that the AAO embedded ZnO NW hybrid structure may find useful applications in luminescent and field emission display devices.

The investigation addresses low temperature magnetization behavior in Co36Fe36Si3Al1Nb4B20 alloy ribbons in their as-spun as well as annealed state. Optimum heat treatment at 875 K led to nanocrystallization whereby bcc-(FeCo)SiAl nanoparticles were dispersed in an amorphous matrix as evidenced from transmission electron microscopy. Low temperature magnetization studies were carried out in the range 77–300 K. Using the method of mathematical fittings, magnetization extrapolated to 0 K was obtained. The dependence of the magnetization with respect to temperature of BT3/2 was used to determine the Bloch coefficient “B” and spin wave stiffness constant “D”. Magnetic softening revealed by lowering in the coercivity in the optimum nanostructured state was also the cause of a drop in the stiffness constant. The range of exchange interaction given by D/TC was higher in the nanostructured state compared to the as-spun amorphous state. The effect of nanocrystallization and the resulting ferromagnetic coupling was further evidenced by low temperature magnetization studies.

Fe 2 O 3 nano-particles are synthesized by mechanical milling at room temperature. Dry milling technique has been found to be effective method of particle size reduction of Fe 2 O 3 . The particle size and lattice strains have been determined by x-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). For studying optical properties, UV-Visible and photoluminescence (PL) spectroscopy have been done. The results reveal that different milling conditions influence the optical properties. This stud y also reveals that not only the surface layer but the inter facial regio n between the α and γ phases also plays an important role for photoluminescence emission of ultra fine nanoparticles invisible light region.

Fatigue lives at high peak stresses for peak-aged (T6) and overaged (T73) 7075 aluminum alloy were compared in the uncorroded and precorroded (pitted) states. Absolute fatigue lives of T73 samples were much higher than that of T6 in the virgin as well as precorroded condition, but the normalized life of T73 was less than that of T6, indicating an intrinsic crack initiation resistance in the former, borne out by fractography, which showed that fatigue cracks almost always initiated at pits for T73 but not for T6. The various crack initiation methodologies observed and the effect of pitting on fatigue lives in the two aging conditions are discussed.

Alumina nanowires have been synthesized by a simple electrochemical route, by tailoring the anodization process of aluminum. Two-stage anodization of pure aluminum foils were carried out in 0.3 M oxalic acid electrolyte by maintaining a constant current density of 250 A/m(2) and suitably controlling the other anodization parameters: anodization voltage, bath temperature and anodization time. The fabricated alumina nanowires were investigated by field-emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Moreover, the X-ray diffraction (XRD) study on the prepared nanowires shows that they are non-crystalline in nature. The photoluminescence (PL) spectra of alumina nanowires exhibit two stable emission bands at 438 and 581 nm. The blue luminescence behavior of the alumina nanowires are attributed to the oxygen-deficient defect centers. PL study of alumina nanowires shows that they have potential applications in light emission devices.