•Low-amylose rice starch was more susceptible to acetylation.•Acetylated starches presented hydrophobic characteristics.•The crystallinity and viscosity decreased with acetylation, mainly in 90-min ...of reaction.
The high-, medium-, and low-amylose rice starches were isolated by the alkaline method and acetylated by using acetic anhydride for 10, 30, and 90min of reaction. The degree of substitution (DS), the Fourier-transformed infrared spectroscopy (FTIR), the X-ray diffractograms, the thermal, morphological, and pasting properties, and the swelling power and solubility of native and acetylated starches were evaluated. The DS of the low-amylose rice starch was higher than the DS of the medium- and the high-amylose rice starches. The introduction of acetyl groups was confirmed by FTIR spectroscopy. The acetylation treatment reduced the crystallinity, the viscosity, the swelling power, and the solubility of rice starch; however, there was an increase in the thermal stability of rice starch modified by acetylation.
A simple and low-cost method is proposed to synthesize graphene oxide incorporated with silver nanoparticles. The inter-sheet distance was controlled by introducing hexylamine into the graphene oxide ...sheets. The materials were investigated by Raman, UV-vis and Fourier transform infrared spectroscopy, X-ray diffraction and field-emission scanning electron microscopy. The increase in inter-sheet distance, due to the presence of hexylamine, favored the growth of the silver nanoparticles within the sheets. We demonstrate that silver nanoparticles increased the electrical conductivity and capacitive properties of the graphene oxide based electrode. The high concentration of well dispersed silver nanoparticles on the surface of the graphene sheets resulted in ca. 90 times higher specific capacitance than bare graphene oxide, in addition to improved electrochemical activity. The proposed method is promising for the development of hybrid materials with enhanced properties for applications mainly in electrochemical energy storage devices.
UNS N26455 is a superalloy commonly used on offshore platforms in components for injection pumps due to its appreciable resistance to various forms of corrosion. However, this superalloy sustain ...damage under aggressive operating conditions, such as in the presence of chloride ions (Cl-), harmful gases or even thermal variations. Hence, the corrosion resistance of UNS N26455 was evaluated via the anodic potentiodynamic polarization technique to understand its behavior under potentially harmful working conditions. The experiments were carried out in controlled environments containing high Cl- concentrations at different temperatures (25 and 40 °C), with and without carbon dioxide (CO2) saturation. The results confirmed that the as-cast superalloy is highly resistant to localized corrosion. On the other hand, the influence of the formation of its microstructure’s secondary phase, which occurs when it is exposed to high temperatures for a prolonged period of time, still needs to be investigated properly.
Pitted keratolysis de Almeida, Jr, Hiram Larangeira; Siqueira, Rodrigo Nunes; Meireles, Renan da Silva ...
Anais brasileiros de dermatología,
01/2016, Letnik:
91, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Pitted keratolysis is a skin disorder that affects the stratum corneum of the plantar surface and is caused by Gram-positive bacteria. A 30-year-old male presented with small punched-out lesions on ...the plantar surface. A superficial shaving was carried out for scanning electron microscopy. Hypokeratosis was noted on the plantar skin and in the acrosyringium, where the normal elimination of corneocytes was not seen. At higher magnification (x 3,500) bacteria were easily found on the surface and the described transversal bacterial septation was observed.
Partial Oxidation of Methane into hydrocarbons using photoelectrochemical routes is attractive from a sustainability point of view owing to the possibility of using renewable energy (i.e., solar ...illumination) to activate this stable molecule. However, the process demands the development of novel catalysts that can promote methane activation and oxidation in a controlled manner to increase energy conversion efficiency. Herein, we demonstrated that semiconductor heterostructures improved charge separation compared to the individual materials alone. A more effortless transfer between bands favors the separation of the electron-hole (e−/h+) pairs generated by the photoelectrocatalytic system and prevents them from recombining. This process produces reactive oxygens, essential to driving methane oxidation conversion of the C–H bond cleavage. TiO2:SnO2 semiconductor heterojunction catalysts in film shape were investigated for methane oxidation via a photoelectrocatalytic process. The methane oxidation reactions were carried out in an inflow and sealed electrochemical system for 1 h. Liquid-state nuclear magnetic resonance revealed methanol and acetic acid as the main liquid products, where the TiO2:SnO2 heterojunction exhibited better performance with values of 30 and 8 µmol.cm−2.h−1, respectively. Compared to their materials alone, the superior performance of the TiO2:SnO2 heterojunction is attributed to the formation of heterostructure type II that enables a more effortless transfer between bands, facilitating the separation of the generated e−/h+ pairs under UV-Vis irradiation. The outcomes achieved here will motivate further studies for developing semiconductor heterojunction structure catalysts in photoelectrocatalysis to partially oxidize methane into valuable chemicals.
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•We synthesized and characterized TiO2:SnO2 heterojunction as a model catalyst for controlled photoelectrochemical methane oxidation.•As-synthesized TiO2:SnO2 heterojunction catalysts and their individual materials alone (i.e., TiO2-anatase and SnO2-rutile) in film-shaped were investigated for methane oxidation via photoelectrocatalytic process under mild conditions.•TiO2:SnO2 heterostructure excited by photoelectron source exhibited superior performance for methanol and acetic acid production when compared to their individual materials alone and excited by different sources (i.e., photon and electron).•The superior production could be attributed to the heterojunction mechanism between TiO2-anatase and SnO2-rutile materials that enables a more effortless transfer between bands, facilitating the separation of the generated electron-hole (e−/h+), liable for producing reactive oxygens ; essential to driving methane oxidation conversion by the C–H bond cleavage.
Clonazepam was initially licensed as an anti-epileptic agent, but its use in a wide variety of psychiatric conditions, including panic disorder (PD) has now been well established. This overview ...evaluates the current role of clonazepam alone or in combination with antidepressants and/or behavioral therapy in the treatment of PD. We review the data establishing the use of clonazepam in the treatment of PD as well as new information, particularly confirmation of longterm efficacy and safety. We also discuss a regimen for safely tapered withdrawal of clonazepam, the characteristics of the respiratory subtype of PD, and CO2-induced panic attacks as a diagnostic measure and predictor for therapeutic success. It has been shown that panic attacks can more readily be induced by CO2 in PD patients with the respiratory subtype than those with the non-respiratory subtype. More than 25 years after the first report of efficacy in PD in 1984, clonazepam, alone or combined with selective serotonin reuptake inhibitors (SSRIs) and/or behavioral therapy, remains an important therapeutic modality for the management of PD.
The cytotoxic activity of the pimarane diterpene annonalide (1) and nine of its semisynthetic derivatives (2–10) was investigated against the human tumor cell lines HL-60 (leukemia), PC-3 (prostate ...adenocarcinoma), HepG2 (hepatocellular carcinoma), SF-295 (glioblastoma) and HCT-116 (colon cancer), and normal mouse fibroblast (L929) cells. The preparation of 2–10 involved derivatization of the side chain of 1 at C-13. Except for 2, all derivatives are being reported for the first time. Most of the tested compounds presented IC50s below 4.0 μM, being considered potential antitumor agents. The structures of all new compounds were elucidated by spectroscopic analyses including 2D NMR and HRMS. Additionally, the interaction of annonalide (1) with ctDNA was evaluated using spectroscopic techniques, and the formation of a supramolecular complex with the macromolecule was confirmed. Competition assays with fluorescent probes (Hoechst and ethidium bromide) and theoretical studies confirmed that 1 interacts preferentially via DNA intercalation with stoichiometric ratio of 1:1 (1:ctDNA). The ΔG value was calculated as −28.24 kJ mol−1, and indicated that the interaction process occurs spontaneously. Docking studies revealed that van der Walls is the most important interaction in 1-DNA and EB-DNA complexes, and that both ligands (1 and EB) interact with the same DNA residues (DA6, DA17 and DT19).
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•Nine derivatives of the pimarane diterpene annonalide were prepared by semisynthesis.•The cytotoxic activity of annonalide and its semisynthetic derivatives was investigated against five tumor cell lines.•Interaction studies suggested that annonalide interacts with ctDNA by intercalation.•The cytotoxic activity of annonalide may be associated with its interaction with DNA.
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•Membranes incorporated with particles were obtained by electrospinning.•Particles showed no cytotoxic effects and contributed to cell proliferation.•Niobium pentoxide particles ...showed biocompatibility in simulated body fluid.•Obtained membranes showed potential benefits for bone tissue applications.
Effective methods of accelerating the bone regeneration healing process are in demand for a number of bone-related diseases and trauma. This work developed scaffolds with improved properties for bone tissue engineering by electrospinning composite polycaprolactone-gelatin-hydroxyapatite-niobium pentoxide (PGHANb) membranes. Composite membranes, with average fiber diameters ranging from 123 to 156 nm, were produced by adding hydroxyapatite (HA) and varying concentrations of niobium pentoxide (Nb2O5) particles (0, 3, 7, and 10 wt%) to a polycaprolactone (PCL) and gelatin (GL) matrix prior to electrospinning. The morphology, mechanical, chemical and biological properties of resultant membranes were evaluated. Bioactivity was assessed using simulated body fluid (SBF) and it confirmed that the presence of particles induced the formation of hydroxyapatite crystals on the surface of the membranes. Samples were hydrophilic and cell metabolism results showed that the niobium-containing membranes were non-toxic while improving cell proliferation and differentiation compared to controls. This study demonstrated that electrospun membranes containing HA and Nb2O5 particles have potential to promote cell adhesion and proliferation while exhibiting bioactive properties. PGHANb membranes are promising candidates for bone tissue engineering applications.
The aim of this work was to prepare a flexible nanocomposite from ultra-fine titanium oxide (
TiO
2
) growth on carbon fibre via microwave-assisted hydrothermal synthesis (MHS) and to evaluate its ...photocatalytic properties. The
TiO
2
nanoparticles were directly grown on the carbon fibre (CF). Thus, a study comparing the conventional titania coating
vs.
the MHS were performed. The significant layer interaction as a function of the coating method on the visible and dark dye photodegradation performance was observed. Techniques such as X-ray diffraction, electron microscopy (field-emission scanning electron microscope (FESEM)), Raman spectroscopy, among others were used aiming to characterize the different route samples. This study reports a reproducible and single method to manufacture of nanocomposites through the growth of
TiO
2
nanoparticle on CF by MHS that allow controlling the thickness layer. Similar procedure of synthesized nanocomposite could be applied in different chemical compositions to advanced applications, based on the electrochemical nanostructure.
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