Production,blood compatibility and cytotoxicity evaluation of a single stage non-woven multicomponent electrospun scaffold mixed with sesame oil,honey and propolis for skin tissue engineering

Scaffolds used in skin tissue engineering must mimic the native function of the extracellular matrix (ECM) and facilitate the fibroblast cell response for new tissue growth. In this study, a novel dressing scaffold based on polyurethane (PU) with sesame oil, honey, and propolis was fabricated by electrospinning. Scanning electron microscopy (SEM) images showed that the diameter of the electrospun scaffolds decreased by blending sesame oil (784?±?125.46?nm) and sesame oil/honey/propolis (576?±?133.72?nm) into the PU matrix (890?±?116.911?nm). Fourier infrared (FT-IR) and thermogravimetric (TGA) analysis demonstrated the formation of hydrogen bonds and interaction between PU and sesame oil, honey, and propolis. Contact-angle measurement indicated reduced wettability of PU/sesame oil scaffold (114?±?1.732) and improved wettability (54.33?±?1.528) in the PU/sesame oil/honey/propolis scaffold. Further, tensile tests and atomic force microscopy (AFM) analysis indicated that the fabricated composite membrane exhibited enhanced mechanical strength and reduced surface roughness compared to the pristine PU. The developed composite displayed less toxicity to the red blood cells (RBC’s) compared to the pristine PU. Cytotoxicity assay showed enhanced cell viability of HDF in electrospun scaffolds than pristine PU after 72?h culture. These enhanced properties of the developed scaffolds suggest the potential of utilizing them in skin tissue engineering.     

Study of interfacial charge transfer in nanosemiconductor–molecule composites

Interaction of sol–gel synthesized Ce–Ag‐codoped ZnO (CSZO) nanocrystals with (E)‐1‐(naphthalen‐1‐yl)‐2‐styryl‐1H‐phenanthro[9,10‐d]imidazole has been analysed. The synthesized nanocrystals and their composites with naphthyl styryl phenanthrimidazole have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X‐ray spectroscopy, X‐ray diffractometry, X‐ray photoelectron spectroscopy (XPS) lifetime and Fourier transform infrared spectroscopy and cyclic voltammetry. XPS shows doped silver and cerium in Ag⁰ and Ce⁴⁺ states, respectively_. SEM and TEM images of CSZO nanoparticles show that they appear to be 3D trapezoid and cocoon‐like shape. The selected area electron diffraction pattern supports the nanocrystalline character of the synthesized material. The percentages of doping of cerium and silver in CSZO are 0.54 (at.) and 0.34 (at.), respectively. From the energy levels of the materials used in the imidazole–CSZO composite, the dominant CT direction has been analysed. Theoretical investigation shows that the binding energy and energy gap of the imidazole composites are highly dependent on the nature of the silver oxide cluster and that charge transfer in the imidazole–Ag₄O₄ composite is faster than the same in other composites. Molecular docking technique has also been carried out to understand the imidazole–DNA interactions. Copyright © 2016 John Wiley & Sons, Ltd.     

Crisis in engineering education

Experimental Techniques -     

Extraction of U(VI), Th(IV), and La(III) from acidic streams and geological samples using AXAD-16–POPDE polymer

A new chromatographic extraction method has been developed using Amberlite XAD-16 (AXAD-16) resin chemically modified with (3-hydroxyphosphinoyl-2-oxo-propyl)phosphonic acid dibenzyl ester (POPDE). The chemically modified polymer was characterized by ¹³C CPMAS and ³¹P solid-state NMR, Fourier Transform–NIR–FIR–Raman spectroscopy, CHNPS elemental analysis, and thermogravimetric analysis. Extraction studies performed for U(VI), Th(IV), and La(III) showed good distribution ratio (D) values of approximately 10³, even under high acidities (1–4 M). Various physiochemical parameters that influence the quantitative metal ion extraction were optimized by static and dynamic methods. Data obtained from kinetic studies revealed that a time duration of 10 min was sufficient to achieve complete metal ion extraction. Maximum metal sorption capacity values under optimum pH conditions were found to be 1.38, 1.33, and 0.75 mmol g^–1 for U(VI), Th(IV), and La(III), respectively. Interference studies performed in the presence of concentrated diverse ions and electrolyte species showed quantitative analyte recovery with lower limits of analyte detection being 10 and 20 ng cm^–3 for U(VI) and both Th(IV) and La(III), respectively. Sample breakthrough studies performed on the extraction column showed an enrichment factor value of 330 for U(VI) and 270 for Th(IV) and La(III), respectively. Analyte desorption was effective using 15 cm³ of 1 M (NH₄)₂CO₃ with >99.8% analyte recovery. The analytical applicability of the developed resin was tested with synthetic mixtures mimicking nuclear spent fuels, seawater compositions and real water and geological samples. The rsd values of the data obtained were within 5.2%, thereby reflecting the reliability of the developed method.     

Duality techniques for certain integral transforms to be starlike

For β<1, let denote the class of all normalized analytic functions f such that

     

Ferromagnetic in-plane spin fluctuations in NaxCoO2 observed by neutron inelastic scattering

We present neutron scattering spectra taken from a single crystal of Na0.75CoO2, the precursor to a novel cobalt-oxide superconductor. The data contain a prominent inelastic signal at low energies ( approximately 10 meV), which is localized in wave vector about the origin of two-dimensional reciprocal space. The signal is highly dispersive, and decreases in intensity with increasing temperature. We interpret these observations as direct evidence for the existence of ferromagnetic spin fluctuations within the cobalt-oxygen layers.     

Spin correlations among the charge carriers in an ordered stripe phase

We have observed a diffuse component to the low-energy magnetic excitation spectrum of stripe-ordered La(5/3)Sr(1/3)NiO4 probed by neutron inelastic scattering. The diffuse scattering forms a square pattern with sides parallel and perpendicular to the stripe directions. The signal is dispersive, with a maximum energy of approximately 10 meV. Probed at 2 meV, the scattering decreases in strength with increasing temperature, and is barely visible at 100 K. We argue that the signal originates from dynamic, quasi-one-dimensional, antiferromagnetic correlations among the stripe electrons.     

Soft X-ray resonant magnetic diffraction

We have conducted the first soft x-ray diffraction experiments from a bulk single crystal, studying the bilayer manganite La2-2xSr1+2xMn2O7 with x=0.475 in which we were able to access the (002) Bragg reflection using soft x rays. The Bragg reflection displays a strong resonant enhancement at the L(III) and L(II) manganese absorption edges. We demonstrate that the resonant enhancement of the magnetic diffraction of the (001) is extremely large, indeed so large that it exceeds that of the nonresonant Bragg diffraction. Resonant soft x-ray scattering of 3d transition metal oxides is the only technique for the atomic selective measurement of spin, charge, and orbital correlations in materials, such as high temperature superconductors, colossal magnetoresistance manganites, and charge stripe nickelates.     

Hole-Size Effects in Pultruded Composites

The stress-gradient effects on the fracture strength of materials have been recognized for a long time. In metals, Neuber's elementary block theory has been used to explain why the actual strength reduction due to notches is less than that indicated by the stress-concentration factor. In fiber-reinforced composites, the same concept was renamed as the hole-size effect, giving rise to a point-stress characteristic dimension and an average-stress characteristic dimension.     

Surface chemistry of Fe2O3 nanoparticles on ultrathin oxide layers on Si and Ge

In this paper, we report on a comparative study of the effect of Fe₂O₃ nanoparticles (NP), introduced onto a thin oxide layer formed on silicon and germanium surfaces, on the thermal decomposition pathway of the individual oxide layers. On both the surfaces, NP of Fe₂O₃ undergo a reduction reaction through a bonding partner change reaction, where the oxygen atoms change from Fe to Si or Ge. On both the surfaces, annealing results in the conversion of the suboxide-like species to dioxide-like species (SiO_x to SiO₂ and GeO_x to GeO₂ respectively for Si and Ge surfaces), until the oxide layer decomposes following the desorption of the respective monoxide species (SiO and GeO). Both the Si and Ge corelevels show a larger chemical shift (4.1 and 3.51 eV in Si 2p and Ge 3d corelevels, respectively) for the as-prepared oxide samples with the NP, at room temperature compared to that without the NP (3.7 and 3.4 eV), indicating a catalytic enhancement of the dioxide formation. Selective formation of silicon oxides leads to encapsulation of the nanoparticles and acts like a protective layer, preventing the oxidation of Fe.