Characterisation of the Microstructure of Plain Carbon Steel Formed during Isothermal and Continuous Cooling Following Austenitisation

The present study has been undertaken to compare the microstructure of the plain carbon steel, containing 0.65 carbon, which was formed during varying isothermal and continuous cooling conditions following austenitisation at the same temperature and soaking time. After austenitisation, one set of samples was subjected to isothermal treatment which was carried out at a temperature varying in the range of 650–400 °C, and the other one was continuously cooled to ambient temperature using different cooling rates ranging from 500 to 1.4 °Cs–1. The metallographic examination of the samples was fulfilled using light and TEM microscopy. Additionally, Vickers hardness measurements were performed.

Systematic Structural and Optical Characterization of TiO2 Nanofibres Synthesised by Electrospinning

TiO2 nanofibres were synthesised by means of the electrospinning technique, which were annealed at high temperatures to achieve the crystalline phase transformation. The chemical stoichiometry of electrospun TiO2 nanofibres was estimated by EDS, finding that at low annealing temperatures excess of oxygen was detected and at high temperatures excess of titanium that originates oxygen vacancies. TEM images show clearly the formation of TiO2 nanofibres that exhibit a homogeneous and continuous aspect without the presence of crystalline defects, whose surface morphology depends strongly on the annealing temperature. The crystalline phase transformation was studied by Raman spectroscopy, which revealed that annealed TiO2 nanofibres showed a crystalline phase transformation from pure anatase to, first a mix of anatase-rutile, then pure rutile as the annealing temperature increased, which was corroborated by X-ray diffraction and high-resolution TEM microscopy. The average grain size, inside the nanofibres, increased with the crystalline phase transformation from 10 to 24 nm for anatase-TiO2 and from 30 to 47 nm for rutile-TiO2, estimated by using the Scherrer-Debye equation. The band gap energy (Eg), obtained from optical absorption spectra, decreases monotonically, where a local minimum is observed at 700 °C, which is ranged in 3.75  Eg  2.42 eV, caused by the anatase → rutile crystalline phase transformation. The photoluminescence shows that radiative bands present a gradual red-shift as the annealing temperature increases due to the continuous change of Eg.

Influence of Terbium Ions and Their Concentration on the Photoluminescence Properties of Hydroxyapatite for Biomedical Applications

A new generation of biomaterials with terbium-doped hydroxyapatite was obtained using a coprecipitation method. The synthesis of new materials with luminescent properties represents a challenging but important contribution due to their potential applications in biomedical science. The main objective of this study was to revel the influence of terbium ions on the design and structure of hydroxyapatite. Different concentrations of terbium, described by the chemical formula Ca10−xTbx(PO4)6(OH)2, where x is in the range of 0 to 1, were considered. The consequence of ion concentration on hydroxyapatite morphology was also investigated. The morphology and structure, as well as the optical properties, of the obtained nanomaterials were characterized using X-ray powder diffraction analysis (XRD), Fourier Transform Infrared spectrometry (FTIR), SEM and TEM microscopy, UV-Vis and photoluminescence spectroscopies. The measurements revealed that terbium ions were integrated into the structure of hydroxyapatite within certain compositional limits. The biocompatibility and cytotoxicity of the obtained powders evaluated using MTT assay, oxidative stress assessment and fluorescent microscopy revealed the ability of the synthesized nanomaterials to be used for biological system imaging.

Star-Shaped Poly(furfuryl glycidyl ether)-Block-Poly(glyceryl glycerol ether) as an Efficient Agent for the Enhancement of Nifuratel Solubility and for the Formation of Injectable and Self-Healable Hydrogel Platforms for the Gynaecological Therapies

In this paper, we present novel well-defined unimolecular micelles constructed a on poly(furfuryl glycidyl ether) core and highly hydrophilic poly(glyceryl glycerol ether) shell, PFGE-b-PGGE. The copolymer was synthesized via anionic ring-opening polymerization of furfuryl glycidyl ether and (1,2-isopropylidene glyceryl) glycidyl ether, respectively. MTT assay revealed that the copolymer is non-cytotoxic against human cervical cancer endothelial (HeLa) cells. The copolymer thanks to furan moieties in its core is capable of encapsulation of nifuratel, a hydrophobic nitrofuran derivative, which is a drug applied in the gynaecology therapies that shows a broad antimicroorganism spectrum. The study shows high loading capacity of the copolymer, i.e., 146 mg of nifuratel per 1 g of copolymer. The load unimolecular micelles were characterized using DLS and TEM microscopy and compared with the reference glyceryl glycerol ether homopolymer sample. The presence of numerous 1,2-diol moieties in the shell of PFGE-b-PGG macromolecules enabled the formation of reversible cross-links with 2-acrylamidephenylboronic acid-based polyacrylamide. The obtained hydrogels were both injectable and self-healable, which was confirmed with a rheological study.

Cell Membrane-Coated Oil in Water Nano-Emulsions as Biomimetic Nanocarriers for Lipophilic Compounds Conveyance

Recently, we developed ultra-stable oil in water nano-emulsions (O/W NEs), able to carry both internal and external cargos (Somes), such as lipophilic compounds and hydrophilic coatings, respectively, that we call here NEsoSomes. O/W NEs are an excellent bioengineering tool for drug and molecules delivery, due to their ability to dissolve a large number of hydrophobic compounds and protect them from hydrolysis and degradation under biological conditions. At present, no report is available on the combination of cell membrane coatings with such nanocarriers, probably due to their typical instability feature. Since then, we have reported, for the first time, a new cell membrane (CM)-coated nanomaterial composed of membranes extracted from glioblastoma cancer cells (U87-MG) deposited on NEsoSomes, through a liquid–liquid interface method, to produce highly controllable membrane caked nano-capsules, namely CM-NEsoSomes. CM-NEsoSomes were physically characterized by dynamic light scattering (DLS) over time and their correct morphology was analyzed by confocal and transmission electron microscopy (TEM) microscopy. Moreover, CM-NEsoSomes biocompatibility was tested on the healthy model cell line, performing cell cytotoxicity and uptake assay, showing nanocarriers uptake by cells with no induced cytotoxicity.

Colpodella sp. (ATCC 50594) Life Cycle: Myzocytosis and Possible Links to the Origin of Intracellular Parasitism

Colpodella species are free living bi-flagellated protists that prey on algae and bodonids in a process known as myzocytosis. Colpodella species are phylogenetically related to Apicomplexa. We investigated the life cycle of Colpodella sp. (ATCC 50594) to understand the timing, duration and the transition stages of Colpodella sp. (ATCC 50594). Sam-Yellowe’s trichrome stains for light microscopy, confocal and differential interference contrast (DIC) microscopy was performed to identify cell morphology and determine cross reactivity of Plasmodium species and Toxoplasma gondii specific antibodies against Colpodella sp. (ATCC 50594) proteins. The ultrastructure of Colpodella sp. (ATCC 50594) was investigated by transmission electron microscopy (TEM). The duration of Colpodella sp. (ATCC 50594) life cycle is thirty-six hours. Colpodella sp. (ATCC 50594) were most active between 20–28 h. Myzocytosis is initiated by attachment of the Colpodella sp. (ATCC 50594) pseudo-conoid to the cell surface of Parabodo caudatus, followed by an expansion of microtubules at the attachment site and aspiration of the prey’s cytoplasmic contents. A pre-cyst formed at the conclusion of feeding differentiates into a transient or resting cyst. Both DIC and TEM microscopy identified asynchronous and asymmetric mitosis in Colpodella sp. (ATCC 50594) cysts. Knowledge of the life cycle and stages of Colpodella sp. (ATCC 50594) will provide insights into the development of intracellular parasitism among the apicomplexa.

Apoptosis and Oxidative Stress Triggered by Carbon Black Nanoparticle in the LA-9 Fibroblast

BACKGROUND/AIMS: A new type of nanoparticle, called NP CB-EDA (Black Carbon modified with ethylenediamine), is commonly used in the oil industry. In the literature, few studies are found in biological models, making NP-EDA potential cytotoxicity in organisms unclear. As its large surface area is capable of interacting with the biological system, that interaction could lead to factors harmful to health. The objective of this study was to investigate the cytotoxic effect of NP CB-EDA on fibroblasts LA-9 at 24 and 48 hours, at different concentrations of the nanoparticle (1, 50, 250, 500 and 1000 µg/ml). METHODS: NP CB-EDA was characterized by TEM microscopy and its effect on cell viability (MTT method), cell morphology (optical microscopy), cell membrane (lactate dehydrogenase release - LDH), oxidative stress pathways (species levels reactive oxygen, ROS and nitrogen, NOS) and apoptosis/necrosis (flow cytometry) were evaluated. RESULTS: The results show that NP CB-EDA at concentrations of 500 and 1000 µg/ml form clusters. The nanoparticle can be absorbed by cells decreasing cell viability. There was damage to the cell membrane of fibroblasts LA 9, an increase in the production of ROS, NOS and pro-inflammatory interleukins TNF-α and IL-6; it was also observed an increase in % of cells in the state of apoptosis in the two periods analyzed, being this response more significant in 24 hours, and concentrations of 250, 500 and 1000 µg/ml presenting higher cytotoxicity. CONCLUSION: The data suggest that NP CB-EDA in fibroblasts LA9 presents cytotoxic potential, which is associated with oxidative stress and apoptosis.

Transcriptional coupling and repair of 8-OxoG activate a RecA-dependent checkpoint that controls the onset of sporulation in Bacillus subtilis

During sporulation Bacillus subtilis Mfd couples transcription to nucleotide excision repair (NER) to eliminate DNA distorting lesions. Here, we report a significant decline in sporulation following Mfd disruption, which was manifested in the absence of external DNA-damage suggesting that spontaneous lesions activate the function of Mfd for an efficient sporogenesis. Accordingly, a dramatic decline in sporulation efficiency took place in a B. subtilis strain lacking Mfd and the repair/prevention guanine oxidized (GO) system (hereafter, the ∆GO system), composed by YtkD, MutM and MutY. Furthermore, the simultaneous absence of Mfd and the GO system, (i) sensitized sporulating cells to H2O2, and (ii) elicited spontaneous and oxygen radical-induced rifampin-resistance (Rifr) mutagenesis. Epifluorescence (EF), confocal and transmission electron (TEM) microscopy analyses, showed a decreased ability of ∆GO ∆mfd strain to sporulate and to develop the typical morphologies of sporulating cells. Remarkably, disruption of sda, sirA and disA partially, restored the sporulation efficiency of the strain deficient for Mfd and the ∆GO system; complete restoration occurred in the RecA− background. Overall, our results unveil a novel Mfd mechanism of transcription-coupled-repair (TCR) elicited by 8-OxoG which converges in the activation of a RecA-dependent checkpoint event that control the onset of sporulation in B. subtilis.