Green Synthesis of Nickel Oxide Nanoparticles from Berberis balochistanica Stem for Investigating Bioactivities

Green synthesis of nanomaterials is advancing due to its ease of synthesis, inexpensiveness, nontoxicity and renewability. In the present study, an eco-friendly biogenic method was developed for the green synthesis of nickel oxide nanoparticles (NiONPs) using phytochemically rich Berberis balochistanica stem (BBS) extract. The BBS extract was rich in phenolics, flavonoids and berberine. These phytochemicals successfully reduced and stabilised the NiNO₃ (green) into NiONPs (greenish-gray). BBS-NiONPs were confirmed by using UV-visible spectroscopy (peak at 305 nm), X-ray diffraction (size of 31.44 nm), Fourier transform infrared spectroscopy (identified -OH group and Ni-O formation), energy dispersive spectroscopy (showed specified elemental nature) and scanning electron microscopy (showed rhombohedral agglomerated shape). BBS-NiONPs were exposed to multiple in vitro bioactivities to ascertain their beneficial biological applications. They exhibited strong antioxidant activities: total antioxidant capacity (64.77%) and 2, 2-diphenyl-1-picrylhydrazyl (71.48%); and cytotoxic potential: Brine shrimp cytotoxicity assay with IC₅₀ (10.40 µg/mL). BBS-NiONPs restricted the bacterial and fungal pathogenic growths at 1000, 500 and 100 µg/mL. Additionally, BBS-NiONPs showed stimulatory efficacy by enhancing seed germination rate and seedling growth at 31.25 and 62.5 µg/mL. In aggregate, BBS extract has a potent antioxidant activity which makes the green biosynthesis of NiONPs easy, economical and safe. The biochemical potential of BBS-NiONPs can be useful in various biomedical and agricultural fields.     

Floating ZnO QDs-Modified TiO2/LLDPE Hybrid Polymer Film for the Effective Photodegradation of Tetracycline under Fluorescent Light Irradiation: Synthesis and Characterisation

In this work, mesoporous TiO₂-modified ZnO quantum dots (QDs) were immobilised on a linear low-density polyethylene (LLDPE) polymer using a solution casting method for the photodegradation of tetracycline (TC) antibiotics under fluorescent light irradiation. Various spectroscopic and microscopic techniques were used to investigate the physicochemical properties of the floating hybrid polymer film catalyst (8%-ZT@LLDPE). The highest removal (89.5%) of TC (40 mg/L) was achieved within 90 min at pH 9 due to enhanced water uptake by the LDDPE film and the surface roughness of the hybrid film. The formation of heterojunctions increased the separation of photogenerated electron-hole pairs. The QDs size-dependent quantum confinement effect leads to the displacement of the conduction band potential of ZnO QDs to more negative energy values than TiO₂. The displacement generates more reactive species with higher oxidation ability. The highly stable film photocatalyst can be separated easily and can be repeatedly used up to 8 cycles without significant loss in the photocatalytic ability. The scavenging test indicates that the main species responsible for the photodegradation was O₂^●−. The proposed photodegradation mechanism of TC was demonstrated in further detail based on the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS).     

Quantum Phase for an Electric Multipole Moment in Noncommutative Quantum Mechanics

We study the noncommutative nonrelativistic quantum dynamics of a neutral particle, which possesses an electric multipole moment, in the presence of an external magnetic field. First, by introducing a shift for the magnetic field we give the Schrödinger equations in the presence of an external magnetic field both on a noncommutative space and a noncommutative phase space, respectively. Then by solving the Schrödinger equations, we obtain quantum phases of the electric multipole moment both on a noncommutative space and a noncommutative phase space. We demonstrate that these phase are geometric and dispersive.     

On the flow of an electrically conducting fluid and heat transfer along a plane wall with periodic suction

The purpose of this paper is to consider the behaviour of a three-dimensional laminar boundary layer flow of an incompressible, electrically conducting Newtonian fluid past a plane wall in the presence of a transverse suction velocity distribution applied at the wall. The components of the wall shear stress and heat transfer, using the method of perturbation, are obtained. The variations of these quantities with the Prandtl number and a magnetic parameter are also investigated.

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Sommario Scopo di questo lavoro é di studiare il comportamento di un flusso di stato-limite laminare tridimensionale e di un flusso newtoniano incompressibile elettroconduttore lungo una parete piana in presenza di una distribuzione di velocità trasversale di aspirazione applicata alla parete. Si determinano le componenti di tensione tangenziale sulla parete e la trasmissione di calore usando un metodo perturbativo. Si studiano anche le variazioni di queste quntità con il numero di Prandtl e con il parametro magnetico.

     

Residual stresses in turned AISI 4340 steel

The residual-stress distribution in the surface region of workpieces of annealed AISI 4340 steel that is turned under unlubricated conditions is determined using a deflection etching technique. The absolute value of the residual stresses at the machined surface are low and increase with an increase in depth beneath the machined surface to a maximum. They then decrease with a further increase in depth eventually becoming vanishingly small. Peak residual stresses are tensile at cutting speeds of 0.5 and 1.0 ms⁻¹ and are compressive at a cutting speed of 1.5 ms⁻¹ for all feed rates and depths of cut. Peak residual stresses and depth of the stressed region increase with an increase in feed rate and depth of cut, but decrease with an increase in cutting speed. The results of this investigation can be interpreted in terms of the variation of tool forces with cutting conditions.     

On log-convexity for differences of mixed symmetric means

Recently S. Simi? has proved log-convexity for differences of power means. We prove a generalization of his result. Namely, log-convexity for differences of mixed symmetric means is proved.     

Novel and facile methods for the synthesis of DTPA-mono-amide: a new completely revised strategy in radiopharmaceutical chemistry

DTPA is a very strong metal chelator widely utilized in radiopharmaceutical chemistry for conjugation of chemicals which do not have enough potency for direct metalo-labeling and also to manage toxic radioactive materials such as plutonium, americium, and curium. It is difficult to conjugate DTPA to an amine group in a singular direction and such reactions usually also coincidently produce a mixture of DTPA-bis-amides and DTPA-mono-amide resulting in considerable insufficiencies/difficulties in synthesis and especially yield/separation procedures. In this paper, novel methods for the exclusive synthesis of DTPA-mono-amide have been established which extensively reduce the difficulties otherwise encountered and increase the reaction’s yield considering the green chemistry approaches. This is expected to be of interest to radiopharmaceutical researchers interested in the DTPA (Radio)-metallic-conjugate. Overall, this paper provides a framework to achieve a higher degree of propriety from DTPA as a chelator to conjugate to the chemical compounds.     

Design of a portable luminescence bio-tool for on-site analysis of heavy metals in water samples

ABSTRACT

In this work, we report an innovative tool for heavy metal screening in water samples. This new chemiluminescent set-up screens the light generated from luminol oxidation by horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H₂O₂). The pollutant concentrations in real water samples were calculated by studying the effect of metal ions on chemiluminescence signal. Owing to its simplicity, portability and low cost, this approach presents a real alternative to classical optical methods. It is constructed with simple materials: a black box containing a cuvette and a micro-camera. When the enzymatic reaction takes place, the luminescence is captured by the camera placed in upright position. The image can be saved automatically in a computer for further analysis using a MATLAB interface. The RGB diagram is then established to determine the analyte concentrations in the tested samples. This method was successfully applied for the determination of mercury (Hg), lead (Pb) and cadmium (Cd) in lake and field water samples. In these experiments, three concentrations of each analytes were tested (5, 25 and 50 µg/L). We noted a good proportionality between the analyte concentration and the chemiluminescent detection intensity. Detection of binary and tertiary combinations of heavy metals has been also investigated. The developed biosensor showed low detection limits for the tested heavy metals: 1, 0.7 and 0.02 for Hg²⁺, Pb²⁺ and Cd²⁺, respectively. Finally, excellent recoveries ranging from 98% to 104% were obtained for the HRP-inhibition assay.     

The variation of heat transfer in a two‐sided lid‐driven differentially heated square cavity with nanofluids containing carbon nanotubes for physical properties of fluid dependent on temperature

The behavior of nanofluids containing cylindrical nanoparticles are investigated numerically inside a two‐sided lid‐driven differentially heated square cavity to gain insight into the convective recirculation and flow processes induced by a nanofluid. The physical properties of the base fluid such as viscosity, thermal conductivity and thermal expansion coefficient are, respectively, assumed to be temperature independent (taking the mean temperature of the left and right walls) and temperature dependent. A model is developed to analyze the behavior of nanofluids taking into account the nanoparticle volume fraction whereas the transport equations are solved numerically with finite volume approach using SIMPLEC algorithm. The left and right moving walls are maintained at different constant temperatures while the upper and bottom walls are thermally insulated. The directions of the moving walls were considered in a way that the force and natural convections aid each other. The governing parameter Richardson number was 0.1<Ri<50.0 but due to space constraints only the results for 0.1<Ri<10.0 from fluid flow are presented. It was found that the temperature dependency of physical properties at different Richardson numbers and nanoparticle volume fractions affects the fluid flow and heat transfer in the cavities. Finally, comparisons between the behaviors of the average Nusselt number at the left wall for two cases are presented. Copyright © 2011 John Wiley & Sons, Ltd.