Effect of The Nickel And Temperature Dependent Electrical Properties C-SiO2 -Ni Composites

The sol-gel method was chosen to synthesize C-SiO2/Ni nanocomposites, silica nanofillers were incorporated into a carbon based on resorcinol-formaldehyde (RF), doped with 5% nickel. During preparation process, they were subjected to a heat treatment of different pyrolysis temperatures and under an inert atmosphere for 2 h. The X- ray diffractogram presented by XRD of the samples treated at low temperatures, indicates the presence of characteristic lines of metallic nickel. FTIR analysis shows the presence of a main band located at about 1050 cm-1, which corresponds to the vibrations of Si-O-Si. From electrical characterizations, the C-SiO2-Ni5%-650 sample has a negative differential resistance‎ behavior (NDR) at low measurement temperatures. According to the I-V characterization, the C-SiO2-Ni5%-625 °C nanocomposite reveals the NDR behavior at room temperature. The conduction mechanism was fitted by two models: the hopping conduction model for the nanocomposite, treated at 650 °C, and the small polaron model for the composite treated at 675 °C.

Value aggregation of pine (Araucaria angustifolia) nuts agro-industrial waste by cellulose extraction

Araucaria (Araucaria angustifolia) is a tree species found in the Southeast and South of Brazil. It is also known as Brazilian pine, presenting fruits of high acceptance. However, its processing generates by-products that are little used. Thus, this work aimed to extract and characterize the cellulose obtained from the pinion husk, as well as to evaluate the contents of ash, lignin, cellulose and α-cellulose in its composition. The raw material and the extracted cellulose were characterized by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). As for the contents of chemical composition detected, the husks showed 1.6% ash, 7% extractives, 34% lignin and 55% cellulose, being 46% α-cellulose and 9% hemicellulose. It was observed by XRD that the removal of amorphous materials resulted in a gain of crystallinity (from 19 to 33%). Proving the efficiency of the extraction, the characterization of the cellulose obtained was shown to be of high purity, since the main band of the lignin (FTIR) and the amorphous materials of the cellulosic sample (TGA) disappeared. Finally, this work shows that the pinion bark is a rich source of cellulose, making it possible to obtain nanocrystals.

A PSO-CVX Algorithm of Sum and Difference Beam Patterns for Time-Modulated Antenna Array

An integrated optimization of sum and difference beam for time-modulated linear antenna array is studied in this paper. The goal of sum and difference beam synthesis is to generate sum beam in the main band and difference beams in the first-order sideband with low side-lobe level through timing switches. The turn-on times of antenna array are achieved by solving a quadratic constraint linear programming; meanwhile, the opening times are optimized by particle swarm optimization algorithm. The results of linear array show that the sum and difference beam can be scanned within ± 40 degrees, with lower peak side-lobe level.

Two muscular variations in the elbow associated with the anterior interosseous nerve

The coexistence of different muscular-neurovascular variations is of significant clinical importance. A male cadaver, 76 years old at death, was subjected to routine anatomical dissection; the procedure was performed for research and teaching purposes at the Department of Anatomical Dissection and Donation, Medical University of Lodz. The right forearm and hand were dissected using standard techniques according to a strictly specified protocol. The presence accessory head of the flexor pollicis longus may potentially compress the anterior interosseous nerve. The present case report describes a rare variant of the ulnar head of the pronator teres, characterized by two independent bands (i.e., two proximal attachments). The main band originates from the coronoid process and the second originates from the tendon of the biceps brachii. This type of attachment could potentially affect the compression of the ulnar artery running between the two bands. Additionally, the accessory head of the flexor pollicis longus was observed, which started on the medial epicondyle; its coexistence with a high division median nerve creates a potential pressure site on the anterior interesosseous nerve.

Highly sensitive detection of Cr(VI), Pb(II) and Cd(II) ions by a new fluorescent sensor based on 4-amino-3-hydroxynaphthalene sulfonic acid-doped polypyrrole

A new electrosynthesized, fluorescent 4-amino-3-hydroxynaphthalene-1-sulfonic acid-doped polypyrrole (AHNSA-PPy) was used for the detection of Cr(VI), Pb(II) and Cd(II) heavy metallic ions. The optical properties of AHNSA-PPy were studied by UV-VIS absorption and fluorescence spectrometry in diluted DMSO solutions. UV-VIS spectrum showed a main band at 260 nm, a moderate band at 240 nm, and shoulders at 285, 295, 320 and 360 nm, whereas the fluorescence spectrum presented an excitation peak at 330 nm and a main emission peak at 390 nm with a shoulder at 295 nm. The effects of heavy metallic ions, including Cr(VI), Pb(II), and Cd(II), on the AHNSA-PPy UV-VIS absorption and fluorescence spectra were investigated. AHNSA-PPy fluorescence spectra were strongly quenched upon increasing the Cr(VI), Pb(II) and Cd(II) concentrations. Linear Stern-Volmer relationships were established, and polynomial equations for Pb(II) and Cd(II) were obeyed, indicating the existence of a AHNSA-PPy dynamic fluorescence quenching mechanism for Cr(VI) and a combination of dynamic and static fluorescence quenching for Pb(II) and Cd(II). The AHNSA-PPy sensor showed high sensitivity for fluorescence detection of the three heavy metallic ions, with very low limits of detection (3σ) of 1.4 nM for Cr(VI), 2.7 nM for Cd(II) and 2.6 nM for Pb(II). Therefore, this very sensitive quenching fluorimetric sensor is proposed for the detection of trace, toxic heavy metallic ions in the environment.

A Novel and Potentially Multifaceted Dehydroascorbate Reductase Increasing the Antioxidant Systems is Induced by Beauvericin in Tomato

Dehydroascorbate reductases (DHARs) are important enzymes that reconvert the dehydroascorbic acid (DHA) into ascorbic acid (ASC). They are involved in the plant response to oxidative stress, such as that induced by the mycotoxin beauvericin (BEA). Tomato plants were treated with 50 µM of BEA; the main antioxidant compounds and enzymes were evaluated. DHARs were analyzed in the presence of different electron donors by native and denaturing electrophoresis as well as by western blot and mass spectrometry to identify a novel induced protein with DHAR activity. Kinetic parameters for dehydroascorbate (DHA) and glutathione (GSH) were also determined. The novel DHAR was induced after BEA treatment. It was GSH-dependent and possessed lower affinity to DHA and GSH than the classical DHARs. Interestingly, the mass spectrometry analysis of the main band appearing on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed a chloroplast sedoheptulose 1,7-bisphosphatase, a key enzyme of the Calvin cycle, and a chloroplast mRNA-binding protein, suggesting that the DHA reducing capacity could be a side activity or the novel DHAR could be part of a protein complex. These results shed new light on the ascorbate-glutathione regulation network under oxidative stress and may represent a new way to increase the plant antioxidant defense system, plant nutraceutical value, and the health benefits of plant consumption.

Micro-Raman Spectroscopy of Zircon (ZrSiO4) Mineral at Annealing Conditions Usually Applied in Zircon Fission-Track Annealing Dataset

Raman analyzes were performed on zircon from a syenite located in the Poços de Caldas Complex, Brazil, with a fission-track (FT) zircon age of 81.4±6.8 Ma. Three isochronous heating (1, 10 and 100 hours) of zircon grains were subjected to temperatures between 300 and 750 °C. These temperature and times are usually applied to obtain zircon Fission-Track annealing dataset. For each time-temperature conditions, Raman spectra analyses were accomplished. The results show variations in the intensity and FWHM (full width at half maximum) in the main band (1007 cm-1– Si–O stretching mode), and a singular change in the peaks from 356 to 439 cm-1 (Si–O bending mode); and from 202 to 224 cm-1 (external modes). These changes were interpreted as spectral polarization-dependence related to common crystallinity increases due to the annealing radiation damages and that the thermal treatments do not interfere on the stability of zircon lattice.

TRYPTOFAN TRANSFORMATION DURING THE REACTION WITH TETRACHLOROAURIC ACID

Gold nanoparticles (Au NPs) are effective agents for early diagnostic and treatment of a variety of diseases, including cancer. However, initial components in the synthesis like surfactants, which are commonly used to stabilize nanoparticles, can produce toxic effects on living organisms. Thus, finding ways to reduce the toxicity of nanoscale preparations is an actual problem. In this regard the essential aminoacid tryptophan (Trp) is a promising reagent for the synthesis of Au NPs that can serve as a reducer of Au(ІІІ) ions and particle stabilizer. In this work, in order to increase the biocompatibility of the nanoscale system, the synthesis of gold nanoparticles was performed in the presence of Trp. The reaction between HAuCl4 and Trp proceeded in aqueous medium with neutral pH at different temperatures. Spectral characteristics of products formed in Au/Trp systems and were studied. In the absorption spectra the main band of Trp at 280 nm was shifted to 250 nm during the reaction; for all studied systems upon excitation of fluorescence with the wavelength of λex = 340 nm the maximum of the emission bands were observed at λem = 450 nm, while for initial tryptophan (λex = 280 nm) it was located at λex = 375nm. Mass spectra of Trp solution in positive mode contained the signal at 131 Da, that was characteristic for ionized indole moiety of amino acid. For supernatants of studied Au/Trp systems in positive mode signals of ionized fragments with masses of 118, 146 and 174 Da were observed. Based on the data it was revealed that amino acid oxidation proceeded through the formation of kynurenine or through the "kynurenine pathway", that corresponds to the metabolic conversion of amino acid in human organism and proves the biocompatibility of formed products.

Collective multipole oscillations direct the plasmonic coupling at the nanojunction interfaces

We present a systematic study of the effect of higher-multipolar order plasmon modes on the spectral response and plasmonic coupling of silver nanoparticle dimers at nanojunction separation and introduce a coupling mechanism. The most prominent plasmonic band within the extinction spectra of coupled resonators is the dipolar coupling band. A detailed calculation of the plasmonic coupling between equivalent particles suggests that the coupling is not limited to the overlap between the main bands of individual particles but can also be affected by the contribution of the higher-order modes in the multipolar region. This requires an appropriate description of the mechanism that goes beyond the general coupling phenomenon introduced as the plasmonic ruler equation in 2007. In the present work, we found that the plasmonic coupling of nearby Ag nanocubes does not only depend on the plasmonic properties of the main band. The results suggest the decay length of the higher-order plasmon mode is more sensitive to changes in the magnitude of the interparticle axis and is a function of the gap size. For cubic particles, the contribution of the higher-order modes becomes significant due to the high density of oscillating dipoles localized on the corners. This gives rise to changes in the decay length of the plasmonic ruler equation. For spherical particles, as the size of the particle increases (i.e., ≥80 nm), the number of dipoles increases, which results in higher dipole–multipole interactions. This exhibits a strong impact on the plasmonic coupling, even at long separation distances (20 nm).