In vivo study of conductive 3D printed PCL/MWCNTs scaffolds with electrical stimulation for bone tissue engineering

Critical bone defects are considered one of the major clinical challenges in reconstructive bone surgery.The combination of 3D printed conductive scaffolds and exogenous electrical stimulation(ES)is a potential favorable approach for bone tissue repair.In this study,3D conductive scaffolds made with biocompatible and biodegradable polycaprolactone(PCL)and multi-walled carbon nanotubes(MWCNTs)were produced using the extrusion-based additive manufacturing to treat large calvary bone defects in rats.Histology results show that the use of PCL/MWCNTs scaffolds and ES contributes to thicker and increased bone tissue formation within the bone defect.Angiogenesis and mineralization are also significantly promoted using high concentration of MWCNTs(3 wt%)and ES.Moreover,scaffolds favor the tartrate-resistant acid phosphatase(TRAP)positive cell formation,while the addition of MWCNTs seems to inhibit the osteoclastogenesis but present limited effects on the osteoclast functionalities(receptor activator of nuclear factor κβ ligand(RANKL)and osteoprotegerin(OPG)expressions).The use of ES promotes the osteoclastogenesis and RANKL expressions,showing a dominant effect in the bone remodeling process.These results indicate that the combination of 3D printed conductive PCL/MWCNTs scaffold and ES is a promising strategy to treat critical bone defects and provide a cue to establish an optimal protocol to use conductive scaffolds and ES for bone tissue engineering.

Interplay between cold densification and malic acid addition (C4H6O5) for the fabrication of near-isotropic MgB2 conductors for magnet application

The effect of cold high pressure densification(CHPD)on anisotropy of the critical current density(Jc)in《in situ》single core binary and alloyed MgB2 tapes has been determined as a function of temperatures at 4.2 K,20 K and 25 K as well as at applied magnetic fields up to 19 T.The study includes binary and C4H6O5(malic acid)doped MgB2 tapes before and after CHPD.It is remarkable that the CHPD process not only improved the Jc values,in particular at the higher magnetic fields,but also decreased the anisotropy ratio,Г=JC^///JC^⊥In binary MgB2 tapes,the anisotropy factor F increases with higher aspect ratios,even after applying CHPD.In malic acid(C4H6O5)doped tapes,however,the application of CHPD leads only to small enhancements ofГ,even for higher aspect ratios.This is attributed to the higher carbon content in the MgB2 filaments,which in turn is a consequence of the reduced chemical reaction path in the densified filaments.At all applied field values,it was found that CHPD processed C4H6O5 doped tapes exhibit an almost isotropic behavior.This constitutes an advantage in view of industrial magnet applications using wires with square or slightly rectangular configuration.

Impedance spectroscopy study on Mn_(1+x)Fe_(2-2x)Ti_xO_4(0≤x≤0.5) ferrites

The complex impedance spectroscopy and surface morphology of Mn1+xFe2-2xTixO4(0≤x≤0.5) system,prepared using a conventional solid state reaction technique,were investigated.The impedance spectroscopy measurements were carried out at room temperature in the frequency range of 42-5 MHz.The electrical processes in the samples were modeled in the form of an equivalent circuit made up of a combination of two parallel RC circuits attributed to grain and grain boundaries.The DC conductivity obtained by extrapolation of AC data using impedance spectroscopy and four-probe method increases at 10% doping of Ti ions.The energy-dispersive X-ray(EDX) pattern confirmed the homogeneous mixing of the Mn,Fe,Ti and O atoms in pure and doped ferrite samples.

Mssbauer spectra of MnFe_(2-2x)Al_(2x)O_4(0≤x≤0.4) ferrites

The effect of non-magnetic Al3+ ion doping on the magnetic properties of MnFe2-2xAl2xO4(0≤x≤0.4) spinel ferrites was studied using Mssbauer spectroscopy measurements at room temperature.From the Mssbauer study,it is observed that the resolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites.The value of the isomer shift obtained from the fitting of the Mssbauer spectra indicates that Fe ions are in +3 state.A paramagnetic doublet is observed at degree of inversion x=0.4,superimposed on the hyperfine sextets,indicating that the super-exchange interaction A-B decreases due to the dilution of sublattice by Al3+ ions.The hyperfine magnetic field decreases at both interstitial sites of tetrahedral(A) and octahedral(B) with the increase in Al concentration.

A Current Review on the Synthesis and Magnetic Properties of M-Type Hexaferrites Material

After the discovery of hexagonal ferrites or hexaferrites, it has been become important materials commercially and technically to study which is still growing on. In this article, we have reviewed about the M-type hexaferrites including their structural, synthesis techniques and important magnetic properties. The role of experimental synthesizing techniques adopted for preparation of M-type hexaferrites on the various parameters studied in this review paper. The substitution of holonium in BaM ferrite reduces the value of coercivity but not saturation magnetization and ramanence and the cobalt-titanium substituted ferrites were the most important M-type ferrites in the field of application in microwave properties and magnetic field industry.

Spatially asymmetric cascade nanocatalysts for enhanced chemodynamic therapy

Chemodynamic therapy(CDT)based on cascade catalytic nanomedicine has emerged as a promising cancer treatment strategy.However,most of the reported cascade catalytic systems are designed based on symmetric-or co-assembly of multiple catalytic active sites,in which their functions are difficult to perform independently and may interfere with each other.Especially in cascade catalytic system that involves fragile natural-enzymes,the strong oxidation of free-radicals toward natural-enzymes should be carefully considered,and the spatial distribution of the multiple catalytic active sites should be carefully organized to avoid the degradation of the enzyme catalytic activity.Herein,a spatially-asymmetric cascade nanocatalyst is developed for enhanced CDT,which is composed by a Fe_(3)O_(4)head and a closely connected mesoporous silica nanorod immobilized with glucose oxidase(mSiO_(2)-GOx).The mSiO_(2)-GOx subunit could effectively deplete glucose in tumor cells,and meanwhile produce a considerable amount of H_(2)O_(2)for subsequent Fenton reaction under the catalysis of Fe_(3)O_(4)subunit in the tumor microenvironment.Taking the advantage of the spatial isolation of mSiO_(2)-GOx and Fe_(3)O_(4)subunits,the catalysis of GOx and freeradicals generation occur at different domains of the asymmetric nanocomposite,minimizing the strong oxidation of free-radicals toward the activity of GOx at the other side.In addition,direct exposure of Fe_(3)O_(4)subunit without any shelter could further enhance the strong oxidation of free-radicals toward objectives.So,compared with traditional core@shell structure,the long-term stability and efficiency of the asymmetric cascade catalytic for CDT is greatly increased by 138%,thus realizing improved cancer cell killing and tumor restrain efficiency.

Optical and electrical properties of electrochemically deposited polyaniline/CeO2 hybrid nanocomposite film

This paper reports the optical and electrical properties of electrochemically deposited polyaniline （PANI）/cerium oxide（CeO;） hybrid nano-composite film onto indium-tin-oxide（ITO） glass substrate.UV-visible spectroscopy andⅠ-Ⅴcharacteristic were performed to study the optical and electrical parameters of the electrochemically deposited film.The film exhibited a strong absorption below 400 nm（3.10 eV） with a well defined absorbance peak at around 285 nm（4.35 eV）.The estimated band gap of the CeO;sample was 3.44 eV,higher than bulk CeO;powder（E;= 3.19 eV） due to the quantum confinement effect.Optical and electrochemical characteristics indicated that the electrical properties of PANI/CeO;hybrid nanocomposite film arc dominated by PANI doping.

Influence of Y^(3+),Yb^(3+),Gd^(3+) cations on structural and electromagnetic properties of CuFe_(2)O_(4) nanoferrites prepared via one step sol-gel method

Rare earths(REs) play a key role in distorting spinel structure by creating some defects at the lattice sites and make them suitable for magnetodielectric applications.In the present study,the nanoferrites of CuRE0.02Fe1.98O4,where REs=Y^(3+),Yb^(3+),Gd^(3+),were prepared using one step sol-gel method.The prepared samples are copper ferrite(CFO),yttrium doped copper ferrite(Y-CFO),ytterbium doped copper ferrite(Yb-CFO) and gadolinium doped copper ferrite(Gd-CFO),respectively.The single-phase structure of all the REs doped nanoferrites was determined by X-ray diffraction(XRD) analysis.The porosity,agglomerations and grain size of the REs doped copper ferrite were examined using field emission scanning electron microscopy(FESEM) analysis.Fourier transform infrared spectroscopy(FTIR)elaborates the phase formation and environmental effects on the REs doped nanoparticles(NPs).The recorded room temperature M-H loops from a vibrating sample magnetometer(VSM) elucidate the magnetic properties of the REs doped spinel nanoferrites.The magnetic saturation(Ms) was calculated in the range of 23.08 to 51.78 emu/g.The calculated coercivity values(272.6 to 705.60 Oe) confirm the soft magnetic behavior of REs doped copper ferrites.Furthermore,the electromagnetic and dielectric properties were assessed using a Vector network analyzer(VNA) from 1 to 6 GHz.The permeability,permittivity,dielectric tangent loss and electric modulus of the REs doped spinel ferrites illustrate that the prepared NPs may be suitable for microwave and high frequency applications.

Enhancement of photocatalytic and photoelectrochemical properties of TiO_(2) nanotubes sensitized by SILAR-Deposited PbS nanoparticles

The aim of this work is to improve the photocatalytic and photoelectrochemical properties of TiO_(2) nanotubes(TiO_(2)-NTAs)by sensitizing them with PbS nanoparticles(NPs)prepared by the Successive Ionic Layer Adsorption and Reaction method(SILAR).The Microstructure,surface morphology,phase composition and optical properties of the prepared structure were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM and High-resolution mode HRTEM)and X-ray photoelectron spectroscopy(XPS).The TiO_(2) NTAs were loaded by PbS NPs,which contents increase by increasing the number of SILAR cycles.The PbS NPs,which have a size in the order of ~20 nm,were found to be uniformly distributed in the TiO_(2) NTAs without damaging the tubular ordered structure.The photocatalytic activity of the PbS/TiO_(2) NTAs system,toward Amido Black(AB),showed significant enhancement compared to the bare untreated TiO_(2) NTs.At 30 SILAR deposition cycles the PbS-NPs/TiO_(2) NTAs structure is able to remove 75% of BA under simulated solar light,considerably higher than the 40% removal obtained with unloaded TiO_(2) NTAs.A significant improvement of the Photoelectrochemical(PEC)efficiency has been also demonstrated for the PbS-NPs/TiO_(2) NTAs hybrid system.This improvement is mainly related to visible-light harvesting and reduced recombination of photo-generated electron-hole pairs due to the synergistic effect of the heterojunction and to the wellorganized morphology of the TiO_(2) NTAs.

A significant improvement in adsorption behavior of mesoporous TUD-1 silica through neodymium incorporation

Neodymium was incorporated into the three-dimensional mesoporous siliceous material TUD-1.In order to understand the chemical and morphological structure of the prepared material,several characterization techniques were performed.The characterization results show the formation of highly distributed isolated Nd3+ions incorporated in the silica matrix in tetrahedrally coordinated structure,moreover no aggregation of separate phase(s)was/were observed.The prepared material was investigated as an adsorbent for methyl green(MG)dye in aqueous solution as a model cationic dye.The results show higher adsorption capacity for Nd-TUD-1 by almost 24 times higher than the neat parent TUD-1 material and more than 100 times higher than bulky Nd_(2)O_(3)under neutral pH.The adsorption results were fitted perfectly with pseudo-second-order model.Moreover,the adsorption isotherms were perfectly fitted with Freundlich isotherm model which indicates the formation of a multilayer of the dye molecules onto the Nd-TUD-1 surface as a physisorption with endothermic nature.

Nanoporous characteristics of sol-gel-derived ZnO thin film

Sol-gel-derived nanoporous ZnO film has been successfully deposited on glass substrate at 200 °C and subsequently annealed at different temperatures of 300, 400 and 600 °C. Atomic force micrographs demonstrated that the film was crack-free, and that granular nanoparticles were homogenously distributed on the film surface. The average grain size of the nanoparticles and RMS roughness of the scanned surface area was 10 nm and 13.6 nm, respectively, which is due to the high porosity of the film. Photoluminescence （PL） spectra of the nanoporous ZnO film at room temperature show a diffused band, which might be due to an increased amount of oxygen va- cancies on the lattice surface. The observed results of the nanoporous ZnO film indicates a promising application in the development of electrochemical biosensors due to the porosity of film enhancing the higher loading of biomacromolecules （enzyme and proteins）.

Interdependence between electrical and magnetic properties of polycrystalline cobalt-substituted tungsten bronze multiferroic ceramics

Polycrystalline cobalt-substituted tungsten bronze ferroelectric ceramics with chemical composition Ba_(5)CaTi_(2-x)Co_(X)Nb_(8)O_(30)(x=0.00,0.02,0.04 and 0.08)were synthesized by solid state reaction technique.X-ray diffraction(XRD)technique was used to confirm the phase formation and it revealed the formation of single phase tetragonal structure with space group P4bm.The surface morphology of the samples was studied by using the scanning electron microscopy(SEM)technique.The dielectric properties such as dielectric constant and dielectric loss have been investigated as a function of temperature and frequency.The P-E and M-H studies confirmed the coexistent of ferroelectricity and magnetism at room temperature.The P-E loop study indicated an increase in the coercive field while the M-H study depicted a decrease in the magnetization with the incorporation of cobalt ions.

Impact of surface coating on morphological, optical and photoluminescence properties of YF3：Tb^3＋ nanoparticles

A simple polyol and sol–gel Stober process were employed for synthesis of YF_3：Tb~＋（core）, YF_3：Tb~＋@LaF_3（core/shell） and YF_3：Tb~＋@LaF_3@SiO_2（core/shell/SiO_2） nanoparticles（NPs）. The phase purity, crystalinity,morphology, optical and photoluminescence properties were investigated and discussed with the help of various analytical techniques including X-ray diffraction pattern,FE-transmission electron microscopy（TEM）,FTIR, UV/vis absorption, energy band gap and emission spectra. XRD andFE-TEM studies indicate the formation of core/shell nanostructure and ~10 nm thick amorphous silica surface coating surrounding the core-NPs, which is also confirmed byFTIR spectral results. The surface modifications of core-NPs significantly affect the optical features in the form of energy band gap, which were correlated with particle size of the nanomaterials. The comparative emission spectral results show that after inert layer coating the luminescent core-NPs display stronger emission intensity in respect to core and silica coated core/shell/SiO_2-NPs. The solubility character along with colloidal stability was improved after silica surface modification, whereas luminescent intensity was suppressed causing the surface functionalized with high energy silanol（Si-OH） molecules. These novel luminescent nanomaterials with enhanced emission intensity and excellent solubility in aqueous solvents would be potentially useful for fluorescence bioimaging/optical bio-probe etc.

Synthesis,Structural and Optical Properties of Mn-Doped Ceria Nanoparticles:A Promising Catalytic Material

The structure,the morphology and the thermal,optical and the surface properties of nanocrystalline CeO_2 doped with Mn have been studied by X-ray diffraction（XRD）,field-emission transmission electron microscopy（FE-TEM）,energy-dispersive X-ray analysis,thermogravimetric analysis,UV–Vis absorption spectroscopy and Fourier transform infrared spectroscopy.The XRD results confirmed the successful incorporation of Mn into the CeO_2 lattice through the formation of nanoscale face-centered cubic solid solution.The FE-TEM observations supported the nanocrystalline nature of the solid solutions.The presence of structural defects and their role on the band gap have been discussed on the basis of absorption spectral studies.The structural differences correlate with results from temperature-programmed reaction（TPR）experiments with H_2 consumption.The TPR measurements showed an enhanced bulk reduction at much lower temperatures,indicating increased oxygen mobility in the samples,which enable to enhanced oxygen diffusion at lower temperatures.