Co-Doped ZnO Nanoparticles:Structural,Morphological,Optical,Magnetic and Antibacterial Studies

Un-doped and Co-doped ZnO nanoparticles （NPs） with different weight ratios （0.5, 1.0, 1.5, and 2.0 wt% of Co） were synthesized by a facile and rapid microwave-assisted combustion method using urea as a fuel. The prepared NPs were characterized by X-ray diffraction （XRD）, high resolution scanning electron microscopy （HR-SEM）, energy dispersive X-ray analysis （EDX）, diffuse reflectance spectroscopy （DRS）, photoluminescence （PL） spectroscopy and vibrating sample magnetometry （VSM）. XRD patterns refined by the Rietveld method indicated that Co-doped ZnO had a single pure phase with wurtzite structure suggesting that Co^2＋ ions would occupy Zn^2＋ ionic sites within the ZnO crystal lattice. Interestingly, the morphology was found to convert substantially from grains to nanoparticles with close-packed periodic array of hexagonal-like shape and then into randomly distributed spherical NPs with the variation of Co-content. The optical band gap estimated using DRS was found to be red-shifted from 3.22 eV for the un-doped ZnO NPs then decrease up to 2.88 eV with increasing Co-content. PL spectra showed a strong green emission band thus confirming the formation of pure single ZnO phase. Magnetic studies showed that Co-doped ZnO NPs exhibited room temperature ferromagnetism （RTFM） and that the saturation magnetization attained a maximum value of 2.203 × 10^-3 emu/g for the highest Co-content. The antibacterial studies performed against a set of bacterial strains showed that the 2.0 wt% Co-doped ZnO NPs possessed a greater antibacterial effect.     

Kitchen Chemistry 101: Multigram Production of High Quality Biographene in a Blender with Edible Proteins

A high yielding aqueous phase exfoliation of graphite to high quality graphene using edible proteins and kitchen chemistry is reported here. Bovine serum albumin (BSA), β‐lactoglobulin, ovalbumin, lysozyme, and hemoglobin are used to exfoliate graphite and the exfoliation efficiency depended on the sign and magnitude of the protein charge. BSA showed maximum exfoliation rate, facilitated graphite exfoliation in water, at room temperature, by turbulence/shear force generated in a kitchen blender at exfoliation efficiencies exceeding 4 mg mL^?1 h^?1. Raman spectroscopy and transmission electron microscopy indicated 3–5 layer, defect‐free graphene of 0.5 μm size. Graphene dispersions loaded on a cellulose paper (650 μg cm^?2) showed the film conductivity of 32 000 S m^?1, which is much higher than graphene/polymer composites. Our method yielded ≈7 mg mL^?1, BSA‐coated graphene with controllable surface charge, which is stable under wide ranges of pH (3.0–11) and temperature (5.0–50 °C), and in fetal bovine serum, for more than two months.These findings may lead to the large scale production of graphene for biological applications.     

Effect of fluid thermal properties on the heat transfer characteristics in a double-pipe helical heat exchanger

Heat transfer characteristics of a double-pipe helical heat exchanger were numerically studied to determine the effect of fluid thermal properties on the heat transfer. Two studies were performed; the first with three different Prandtl numbers (7.0, 12.8, and 70.3) and the second with thermally dependent thermal conductivities. Thermal conductivities of the fluid were based on a linear relationship with the fluid temperature. Six different fluid dependencies were modeled. Both parallel flow and counterflow configurations were used for the second study.Results from the first study showed that the inner Nusselt number was dependent on the Prandtl number, with a greater dependency at lower Dean numbers; this was attributed to changing hydrodynamic and thermal entry lengths. Nusselt number correlations based on the Prandtl number and a modified Dean number are presented for the heat transfer in the annulus. Results from the second part of the study showed that the Nusselt number correlated better using a modified Dean number. The counterflow configuration had higher heat transfer rates than the parallel flow, but the ratio of these differences was not different when comparing thermally dependent properties and thermally independent properties.     

Optical properties of Dy<Superscript>3+</Superscript>-doped sodium–aluminum–phosphate glasses

Trivalent dysprosium (Dy³⁺)-doped sodium–aluminum–phosphate (NAP) glasses were prepared and characterized by their optical absorption, excitation, emission spectra, and decay time measurements. Judd–Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative lifetime and stimulated emission cross section of the ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_15/2 transitions. The luminescence intensity ratio of ⁴F_9/2 → ⁶H_13/2 to ⁴F_9/2 → ⁶H_15/2 transitions of Dy³⁺ in NAP glasses gives the feasibility of extracting white light. The lifetime and quantum efficiency of ⁴F_9/2 level is found to be higher than other reported glasses. With increase in Dy³⁺ ion concentration, the decay from ⁴F_9/2 level is found to be faster with decrease in lifetime due to cross relaxation between Dy³⁺ ions.     

Hispolon Cyclodextrin Complexes and Their Inclusion in Liposomes for Enhanced Delivery in Melanoma Cell Lines

Hispolon, a phenolic pigment isolated from the mushroom species Phellinus linteus, has been investigated for anti-inflammatory, antioxidant, and anticancer properties; however, low solubility and poor bioavailability have limited its potential clinical translation. In this study, the inclusion complex of hispolon with Sulfobutylether-β-cyclodextrin (SBEβCD) was characterized, and the Hispolon-SBEβCD Complex (HSC) was included within the sterically stabilized liposomes (SL) to further investigate its anticancer activity against melanoma cell lines. The HSC-trapped-Liposome (HSC-SL) formulation was investigated for its sustained drug delivery and enhanced cytotoxicity. The inclusion complex in the solid=state was confirmed by a Job’s plot analysis, molecular modeling, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance (NMR) spectroscopy, and scanning electron microscopy (SEM). The HSC-SL showed no appreciable deviation in size (<150 nm) and polydispersity index (<0.2) and improved drug encapsulation efficiency (>90%) as compared to control hispolon liposomes. Individually incorporated hispolon and SBEβCD in the liposomes (H-CD-SL) was not significant in loading the drug in the liposomes, compared to HSC-SL, as a substantial amount of free drug was separated during dialysis. The HSC-SL formulation showed a sustained release compared to hispolon liposomes (H-SLs) and Hispolon-SBEβCD liposomes (H-CD-SLs). The anticancer activity on melanoma cell lines (B16BL6) of HSC and HSC-SL was higher than in H-CD-SL and hispolon solution. These findings suggest that HSC inclusion in the HSC-SL liposomes stands out as a potential formulation approach for enhancing drug loading, encapsulation, and chemotherapeutic efficiency of hispolon and similar water insoluble drug molecules.     

Empirical examination of critical failure factors of continuous improvement deployments: stage-wise results and a contingency theory perspective

Organisations implement various Continuous Improvement (CI) practices such as Total Quality Management, Lean, Six Sigma and Lean Six Sigma (LSS) for improving their processes. Drawing from the success and failure stories of these structured CI practices, scholars enumerated Critical Success Factors and Critical Failure Factors (CFFs). This study empirically examines the occurrence of various CFFs across different stages of CI deployment. Further, from a contingency theoretic perspective, this study investigates their associations with contextual variables by collecting survey data from 213 business units from the USA, the UK, China, and India. Principal Component Analysis is used to group CFFs across five CI deployment stages leading to an empirically refined framework for CI. Crosstab analysis using the chi-square likelihood ratio presented associations of CFFs with contextual variables. Findings reveal significant differences in the occurrence of CFFs across countries. There is evidence that LSS is less prone to failures when compared with TQM, Lean and Six Sigma. The occurrence of CFFs has been relatively lower in smaller and medium-sized enterprises operating in the service sector. Findings also reveal that lessons learned from each CI deployment cycle, contribute to organisational learning, and thence, leading to success at the strategic CI level of maturity.     

Catalyst Design by NH4OH Treatment of USY Zeolite

Hierarchical zeolites are a class of superior catalysts which couples the intrinsic zeolitic properties to enhanced accessibility and intracrystalline mass transport to and from the active sites. The design of hierarchical USY (Ultra‐Stable Y) catalysts is achieved using a sustainable postsynthetic room temperature treatment with mildly alkaline NH₄OH (0.02 m ) solutions. Starting from a commercial dealuminated USY zeolite (Si/Al = 47), a hierarchical material is obtained by selective and tuneable creation of interconnected and accessible small mesopores (2–6 nm). In addition, the treatment immediately yields the NH₄⁺ form without the need for additional ion exchange. After NH₄OH modification, the crystal morphology is retained, whereas the microporosity and relative crystallinity are decreased. The gradual formation of dense amorphous phases throughout the crystal without significant framework atom leaching rationalizes the very high material yields (>90%). The superior catalytic performance of the developed hierarchical zeolites is demonstrated in the acid‐catalyzed isomerization of α‐pinene and the metal‐catalyzed conjugation of safflower oil. Significant improvements in activity and selectivity are attained, as well as a lowered susceptibility to deactivation. The catalytic performance is intimately related to the introduced mesopores, hence enhanced mass transport capacity, and the retained intrinsic zeolitic properties.     

Thick lead-free ferroelectric films with high Curie temperatures through nanocomposite-induced strain

Ferroelectric materials are used in applications ranging from energy harvesting to high-power electronic transducers. However, industry-standard ferroelectric materials contain lead, which is toxic and environmentally unfriendly. The preferred alternative, BaTiO(3), is non-toxic and has excellent ferroelectric properties, but its Curie temperature of ～130 °C is too low to be practical. Strain has been used to enhance the Curie temperature of BaTiO(3) (ref. 4) and SrTiO(3) (ref. 5) films, but only for thicknesses of tens of nanometres, which is not thick enough for many device applications. Here, we increase the Curie temperature of micrometre-thick films of BaTiO(3) to at least 330 °C, and the tetragonal-to-cubic structural transition temperature to beyond 800 °C, by interspersing stiff, self-assembled vertical columns of Sm(2)O(3) throughout the film thickness. The columns, which are 10 nm in diameter, strain the BaTiO(3) matrix by 2.35%, forcing it to maintain its tetragonal structure and resulting in the highest BaTiO(3) transition temperatures so far.     

Investigation on effect of fibre hybridization and orientation on mechanical behaviour of natural fibre epoxy composite

Nowadays bio fibre composites play a vital role by replacing conventional materials used in automotive and aerospace industries owing to their high strength to weight ratio, biodegradability and ease of production. This paper aims to find the effect of fibre hybridization and orientation on mechanical behaviour of composite fabricated with neem, abaca fibres and epoxy resin. Here, three varieties of composites are fabricated namely, composite 1 which consists of abaca fibre and glass fibre, composite 2, which consists of neem fibre and glass fibre, whereas composite 3 consists of abaca, neem fibres and glass fibres. In all the above three varieties, fibres are arranged in three types of orientations namely, horizontal (type I), vertical (type II) and 45\(^{\circ }\) inclination (type III). The result shows that composites made up of abaca and neem fibres with inclined orientation (45\(^{\circ }\)) have better mechanical properties when compared with other types of composites. In addition, morphological analysis is carried out using scanning electron microscope to know the fibre distribution, fibre pull out, fibre breakage and crack propagation on tested composites.     

Laminar flow of a suspension in a curved pipe with varying curvature

The laminar flow of a fairly concentrated suspension (in which the volume fraction Z of the solid particles $\text{< 0.4}$) in a spatially varying periodically curved pipe has been examined numerically. Unlike the case of interacting suspension flows, the particles are found to flow in a well-mixed fashion, altering both the axial and circumferential velocities and consequently the fluid flux in the tube, depending on their diffusivity and inertia. The magnitude of shear stress at the wall is enhanced, suggesting that, if applied to vascular system, the vascular wall could be prone to ulceration during pathological situations like polycythemia. The delay in adaptation of the deviation in Poiseuille flow velocity to the curvature changes is also discussed in detail.