Effect of the Processing Parameters on the Porosity and Mechanical Behavior of Titanium Samples with Bimodal Microstructure Produced via Hot Pressing

Commercially pure (c.p.) titanium grade IV with a bimodal microstructure is a promising material for biomedical implants. The influence of the processing parameters on the physical, microstructural, and mechanical properties was investigated. The bimodal microstructure was achieved from the blends of powder particles with different sizes, while the porous structure was obtained using the space-holder technique (50 vol.% of ammonium bicarbonate). Mechanically milled powders (10 and 20 h) were mixed in 50 wt.% or 75 wt.% with c.p. titanium. Four different mixtures of powders were precompacted via uniaxial cold pressing at 400 MPa. Then, the specimens were sintered at 750 °C via hot pressing in an argon gas atmosphere. The presence of a bimodal microstructure, comprised of small-grain regions separated by coarse-grain ones, was confirmed by optical and scanning electron microscopies. The samples with a bimodal microstructure exhibited an increase in the porosity compared with the commercially available pure Ti. In addition, the hardness was increased while the Young’s modulus was decreased in the specimens with 75 wt.% of the milled powders (20 h).

A review on bovine hydroxyapatite; extraction and characterization

High rate of bone grafting surgeries emphasizes the need for optimal bone substitutes. Biomaterials mimicking the interconnected porous structure of the original bone with osteoconductive and osteoinductive capabilities have long been considered. Hydroxyapatite (HA), as the main inorganic part of natural bone, has exhibited excellent regenerative properties in bone tissue engineering. This manuscript reviews the HA extraction methods from bovine bone, as one of the principal biosources. Essential points in the extraction process have also been highlighted. Characterization of the produced HA through gold standard methods such as XRD, FTIR, electron microscopies (SEM and TEM), mechanical/thermodynamic tests, and bioactivity analysis has been explained in detail. Finally, future perspectives for development of HA constructs are mentioned.

Formation of NiMoO4 Anisotropic Nanostructures under Hydrothermal Conditions

Abstract—The synthesis of NiMoO4 hierarchical nanostructures using the hydrothermal method has been studied. The decomposition of NiMoO4·xH2O crystalline hydrate formed during the synthesis has been studied using synchronous thermal analysis upon heating in a stream of air and argon. According to X-ray diffraction as well as scanning and transmission electron microscopies, the proposed conditions allow one to synthesize single-phase nanosized (average CSR size of about 25 ± 2 nm) nickel(II) molybdate, which has a spinel-type monoclinic structure (space group C2/m) without impurity inclusions.

Compartmentalized Polymeric Nanoparticles Deliver Vancomycin in a pH-Responsive Manner

Vancomycin (VCM) is a last resort antibiotic in the treatment of severe Gram-positive infections. However, its administration is limited by several drawbacks such as: strong pH-dependent charge, tendency to aggregate, low bioavailability, and poor cellular uptake. These drawbacks were circumvented by engineering pH-responsive nanoparticles (NPs) capable to incorporate high VCM payload and deliver it specifically at slightly acidic pH corresponding to infection sites. Taking advantage of peculiar physicochemical properties of VCM, here we show how to incorporate VCM efficiently in biodegradable NPs made of poly(lactic-co-glycolic acid) and polylactic acid (co)polymers. The NPs were prepared by a simple and reproducible method, establishing strong electrostatic interactions between VCM and the (co)polymers’ end groups. VCM payloads reached up to 25 wt%. The drug loading mechanism was investigated by solid state nuclear magnetic resonance spectroscopy. The engineered NPs were characterized by a set of advanced physicochemical methods, which allowed examining their morphology, internal structures, and chemical composition on an individual NP basis. The compartmentalized structure of NPs was evidenced by cryogenic transmission electronic microscopy, whereas the chemical composition of the NPs’ top layers and core was obtained by electron microscopies associated with energy-dispersive X-ray spectroscopy. Noteworthy, atomic force microscopy coupled to infrared spectroscopy allowed mapping the drug location and gave semiquantitative information about the loadings of individual NPs. In addition, the NPs were stable upon storage and did not release the incorporated drug at neutral pH. Interestingly, a slight acidification of the medium induced a rapid VCM release. The compartmentalized NPs could find potential applications for controlled VCM release at an infected site with local acidic pH.

Studying the electrical conductivity and mechanical properties of irradiated natural rubber latex/magnetite nanocomposite

Nanocomposites have received voluminous interest due to the combination of unique properties of organic and inorganic component in one material. In this class, magnetic polymer nanocomposites are of particular interest because of the combination of excellent magnetic properties, stability, and good biocompatibility. This paper reports the preparation and characterization of nanocomposites films based on natural rubber in latex state (NRL) loaded with different concentrations of semiconducting magnetite nanoparticles (Fe3O4) (MNPs) (5, 10, 15, 20, and 30%). NRL (100%) and NRL/Fe3O4 nanocomposites were prepared by solution casting technique then, exposed to various irradiation doses (50, 70, 100 kGy).The nanocomposite’s morphological, and physical properties were investigated through various spectroscopic techniques such as Fourier-transformed infrared, X-ray diffraction, scanning electron, and transmission electron microscopies. The mechanical properties, including the tensile strength and elongation at break percentage (E b %) of the nanocomposites were also studied and compared with the 100% NRL films. Based on the results obtained from the mechanical study, it is found that the NRL/20% Fe3O4 nanocomposite film exhibited the highest tensile strength at 100 kGy. On the other hand, based on the conductivity study, it is found that, NRL/Fe3O4 nanocomposite with 10% magnetite exhibit the highest conductivity as the content of magnetite plays an important and effective role based on the high and homogeneous dispersity.

Electron microscopic and pathological changes of lung cancer after intratumoral injection of sodium bicarbonate

Background: Lung cancer can be treated with surgery, chemotherapy, radiation therapy, targeted therapy and palliative care. Palliative therapy is applied for inoperable lung cancer as it induces tumour necrosis. PH of tumour tissue is acidic; application of sodium bicarbonate (SB) into lung cancer locally via bronchoscopy can change its core pH, which may lead to tumour destruction. We aimed to study the ultrastructural characteristics of lung cancer and to assess the destructive effects of sodium bicarbonate 8.4% local injection on tumour tissue integrity by light and electron microscopies. Methods: This study was conducted on 21 patients with central bronchial carcinoma diagnosed according to WHO classification 2015. Three bronchoscopic biopsies were taken; two biopsies before and one after injection of sodium bicarbonate 8.4% solution of 20 ml via transbronchial needle. All biopsies were examined by both light and electron microscopes. The first biopsy was examined to diagnose the tumour morphologically with and without immunostaining. Second and third biopsies were taken before and after SB 8.4% injection to compare pathological changes in tumour tissue integrity as well as cellular ultra-structures. Different lung cancer pathological types were included in the study. Results: Tumour tissue integrity and pathological changes were examined in biopsies before and after injection of sodium bicarbonate 8.4%. Extensive necrosis in all cell types of lung cancer was seen after injection of SB; this important finding was delineated by both light and electron microscopies. Conclusion: Preliminary ultrastructural study of small biopsy of lung tumor has a complementary role to both morphological and immunohistochemical studies. Local injection of sodium bicarbonate into lung cancer induces extensive necrosis that may reflect its important therapeutic role in lung cancer.

Coherent and Compact Zinc Electrodeposition Enabled by Compressing the Electric Double Layer of the Deposits

The porous hexagonal-platelet Zinc (Zn) deposits exacerbate the chemical corrosion and deteriorate the reversibility of the Zn electrodes in aqueous electrolytes. Based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, to turn the messy Zn deposits into agglomerate ones, the challenge is to weaken the electric double layer repulsive force, which is the main reason preventing the dense Zn deposits, between the electrodeposited Zn particles. Here, we proposed a strategy to compress the electric double layer and regulate the forces between the electrodeposited Zn particles by introducing inert charges to the surface of the Zn deposits. The results of the electron microscopies revealed dense and coherent electrodeposition of Zn, indicating that the van der Waals attraction between the deposits becomes governing during electrodeposition. Such results could be attributed to the adsorbed inert charges on Zn deposits decrease the net charges and weaken the electric double layer repulsive force. This design enables the Zn||Zn cells a long-term plating/stripping stability for > 1200 h, a high average Coulombic Efficiency of 99.9% for > 2100 h, and steady charge/discharge responses even under a draconian deep-discharge condition of 80% depth of discharge of Zn (DODZn). In addition, the Zn||VS2 full cells demonstrate significantly improved electrochemical reversibility and capacity retention.

Cartap wastewater treatment by a microwave-induced catalytic oxidation procedure over Ce/Co/γ-Al2O3

Microwave-assisted catalytic technology is potentially promising in the application of water treatment due to its merits of high reaction rates, simple equipment and operations. In case of the cartap wastewater rarely studied, the easy transformation of cartap into metabolites could induce higher toxicity. This study aimed to develop a novel catalyst Ce/Co/γ-Al2O3 to dispose cartap effectively. The catalyst was prepared by loading Ce and Co on the surface of the support Al2O3, followed by characterization with X-ray diffraction, scanning and transmission electron microscopies. Based on the treatment results, the microwave-induced catalytic oxidation procedure over Ce/Co/γ-Al2O3 could decompose the contaminants efficiently and fast in the case of a low oxidant dosage and a wide pH range. Under the conditions of pH of 5, microwave power of 450 W, catalyst dosage of 0.7 g and hydrogen peroxide dosage of 0.2 mL, the activity of Ce/Co/γ-Al2O3 catalyst could reach up to 86.08%. Importantly, the Ce/Co/γ-Al2O3 catalyst displayed excellent stability after using for 6 times in the degradation process. This work paved a new way for the effective catalyst design for efficient microwave-induced oxidative degradation.