Band 115, Heft 3

A controlled and sustained release of drugs is much more desirable and beneficial when dealing with cancer, as such drugs also harm normal cells. Available anticancer drugs used in chemotherapy are associated with severe side effects due to high dosage requirements. Electrospun nanofibers have an extensive surface area, controllable pore size, and tunable drug release profiles, which make these nanofibers promising candidates in the medical field. Electrospun fibrous matrices are increasingly used in cancer research as patches for drug delivery in living organisms and as scaffolds for cancer modeling in the lab. Towards these applications, nanofibers synthesized by electrospinning have exhibited great clinical potential as a biomimetic tumor microenvironment model for drug screening, a controllable platform for localized, prolonged drug release for cancer therapy, and a human cancer diagnostic tool for capture and isolation of circulating tumor cells in the bloodstream and detection of cancer-associated biomarkers. This review briefly describes most of the materials used in electrospinning. Then, we discuss two ways that electrospinning is used to fight cancer: first, as patches with anticancer agents for therapeutic cargo delivery, and second, as three-dimensional fiber for filtering and detecting cancers.

Utilisation of templates facilitates the synthesis of titania samples with improved physico-chemical properties. When biomaterials are utilised as templates in the creation of inorganic materials, they can lead to constructed mesostructures via cost-effective and environmentally friendly synthetic pathways. Based on this context, the goal of this study was to assess the impact of palm oil on the surface properties and crystallite characteristics of titania nanoparticles. In this work, the various physico-chemical parameters such as thermal, surface area, porosity, crystallinity, chemical composition, textural and morphological characteristics of the palm oil (PO) templated titania were studied using various analysis techniques. Palm oil templated titania samples were synthesised using various amounts of palm oil as templates. The sample generated with a molar ratio of PO over titania precursor of 0.07 possessed large surface area (74.5 m 2  g −1 ), small particle size (13.4 nm), uniformly dispersed spherical particles with good morphology and porosity among the various templated titania produced in this work. In addition, it was found to possess maximum photocatalytic efficiency in degrading the target 4-chlorophenol under UV irradiation.

Hydroxyapatite is an important biomaterial for orthopaedic applications due to its high structural similarity to human bone. However, weak mechanical and antibacterial properties limit the use of hydroxyapatite compared to metallic implants such as Ti and 316L alloys for direct use in the human skeleton. To overcome these shortcomings, we have prepared hydroxyapatite matrix silver and carbon nanotube reinforced biocomposites. Silver particles have beneficial effects on biomaterials due to their effective antibacterial activity. In addition, CNT particles are known for their high strength and their ability to improve the mechanical properties of composite materials. To prepare the hydroxyapatite-based composites, the powder blends with different reinforcement types (Ag, CNT) and ratios were ground using a planetary ball mill. The biocomposite powders were then cold pressed under 500 MPa pressure to obtain green samples. The sintering process was carried out at 1200 °C for 4 h. The microstructural and structural investigations were carried out by scanning electron microscopy and X-ray diffraction, respectively. In order to better evaluate the mechanical properties of the samples, hardness measurements, compression and fracture tests were carried out. Antibacterial tests were also carried out against various micro-organisms. Both types of reinforcement were found to be effective in improving the mechanical properties. In addition, it was observed that CNT reinforcement slightly increased the antibacterial resistance, but silver-reinforced samples provided excellent antibacterial resistance.

Bone disorders and conditions have been increasing at an alarming rate all over the world, especially in niches where increased obesity and poor physical activity have been prevailing. Synthetic nanohydroxyapatite (HAp) is one of the remedies to reconstruct bone formation. Its rate of dissolution and compatibility is in the moderately acceptable range. The doping of HAp with bone-forming ions can make them highly biologically compatible materials. In the present work, we formulated HAp doped with essential micronutrients of strontium and copper. Nanoglobular Sr and Cu doped HAp (SC-HAp) with an average size of 30 nm was prepared. The SC-HAp was partially crystalline and amorphous, which could influence the dissolution rate of the material. The biomineralization ability of the SC-HAp seemed to be effective in apatite formation. The calcium, collagen and alkaline phosphatase secretion levels after the addition of SC-HAp on MG63 cells indicate the bone-forming capacity of the material. Further, the cell proliferation rate was enhanced compared to the control with SC-HAp.

In this study, poly(2-ethyl aniline)/graphene composites were prepared by a mechanochemical method, through in-situ polymerization of 2-ethyl aniline in the presence of graphene at different concentrations. Vickers microhardness, elastic modulus and electrical conductivity measurements were carried out as a function of the graphene concentration in the composite. Increasing the graphene content of the composite resulted in an increase in the conjugation length and carrier mobility of the polymer, and thus in the electrical conductivity of the composites. However, thermogravimetric analysis showed that the thermal stability of poly(2-ethyl aniline) increased with increasing graphene concentration. This study suggests the potential of graphene concentration to efficiently modify the morphological, electrical, mechanical, and thermal properties of poly(2-ethyl aniline).

Sn 1− x Fe x O 2 ( x = 0, 1, 2, 3, and 4 %) of the diamagnetic/ferromagnetic phase were synthesized by the conventional hydrothermal method. X-ray diffraction spectra confirm that all the samples have a tetragonal structure. Electronic distribution over the unit cell of Sn 1− x Fe x O 2 showed the dependence of electronic density on the x . The crystallite size of the obtained samples was in the range of 42–72 nm. Impedance spectroscopy was employed to investigate the variation of the electrical impedance and some related parameters as frequency functions in the range of 75 k Hz–10 MHz at room temperature. The dielectric behavior was explained using the Maxwell–Wagner model of interfacial polarization. The ac conductivity results were used to evaluate the maximum barrier height, the minimum hopping distance, and the density of the localized states at the Fermi level. The effect of adding the iron ion into the tin dioxide compound was apparent, as the electrical and magnetic properties as well as the morphology were affected, although the crystal structure phase still has the same tetragonal crystal system for the different iron concentration (Fe from x = 0 up to x = 0.04) with slight variation in the lattice constants. The magnetic measurements illustrated that the Fe-doped SnO 2 nanoparticles exhibit ferromagnetic ordering at room temperature. Variation of the Fe content affects the ferromagnetic characteristics of the samples.

The enthalpies of mixing in liquid alloys of the ternary Ag–Eu–Sn system were determined over a wide range of concentrations by means of isoperibolic calorimetry in the temperature range from 1313 to 1373 K. The partial enthalpies of each component of the ternary system were measured along the following sections: Δ H ̄ Ag ${\Delta}{\bar{H}}_{\text{Ag}}$ along the section with x Eu /x Sn = 0.28/0.72 up to silver content of about x Ag = 0.2 at 1373 K; Δ H ̄ Sn ${\Delta}{\bar{H}}_{\text{Sn}}$ along three sections ( x Ag / x Eu = 0.31/0.69, 0.50/0.50 and 0.70/0.30) up to x Sn = 0.35 at 1373 K; Δ H ̄ Eu ${\Delta}{\bar{H}}_{\text{Eu}}$ along the section x Ag / x Sn = 0.50/0.50 up to x Eu = 0.25 at 1313 K. The enthalpies of mixing in the liquid Ag–Eu–Sn alloys show exothermic effects, being more pronounced in the vicinity of the Eu–Sn binary constituent. The minimum value of the integral enthalpy of about −60 kJ mol −1 is observed in the composition region of the congruently melting Eu 2 Sn phase.

The evolution characteristics of the second phases in the weld seams of 2.25Cr-Mo-0.25 V steel in three states – welded, post-weld heat-treated and creep states – during manufacturing and service were evaluated by calculations and observations using optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction spectrometry. The results showed that the second phase was M 3 C in the as-welded state. The types and quantities of the precipitated phases increased greatly after post-weld heat treatment (PWHT), and M 3 C, M 2 C, M 7 C 3 , M 23 C 6 and MX were the main precipitated phases. During PWHT, the amount of M 7 C 3 decreased, the amounts of M 23 C 6 and MX increased, and the sizes of the second phases increased. The precipitates coarsened after long-term creep, and M 7 C 3 , M 6 C, M 23 C 6 , M 2 C, and MX were the main precipitate phases in this state. The size of the MX phase remained relatively stable during long-term creep, which contributed greatly to the creep resistance.