Possible Room Temperature Ferromagnetism in Hydrogenated Carbon Nanotubes

We find that ferromagnetism can be induced in carbon nanotubes (CNTs) by introducing hydrogen. Multiwalled CNTs grown inside porous alumina templates contain a large density of defects resulting in significant hydrogen uptake when annealed at high temperatures. This hydrogen incorporation produces H-complex and adatom magnetism which generates a sizeable ferromagnetic moment and a Curie temperature near Tc=1000 K. We studied the conditions for the incorporation of hydrogen, the temperature-dependent magnetic behavior, and the dependence of the ferromagnetism on the size of the nanotubes.Comment: 15 pages with 3 figures included; Accepted by Phys. Rev.

Compact High-Voltage Generator of Primary Power Based on Shock Wave Depolarization of Lead Zirconate Titanate Piezoelectric Ceramics

The design and performance of a compact explosive-driven high-voltage primary power generator is presented. The generator utilizes a fundamental physical effect—depolarization of ferroelectric materials under longitudinal shock wave impact, when the shock wave is initiated along the polarization vector P. These primary power sources, containing energy-carrying elements made of lead zirconate titanate poled piezoelectric ceramics, with the volume from 0.35 to 3.3 cm3, are capable of producing pulses of high voltage with amplitudes up to 21.4 kV. The amplitude and full width at half-maximum of the high-voltage pulses are directly proportional to the thickness of the energy-carrying element, with coefficients of proportionality of 3.42±0.12 kV/mm (amplitude) and 0.125±0.01 µs/mm (width). The specific energy density of these ferroelectric energy-carrying elements reaches 76 mJ/cm3

Studies on the effects of Adansonia Digitata Lin's fruits on diabetes

The point of this study is to look into how Adansonia digitata Linn plants can help people with diabetes. The bioactive extract was chosen by using the Haemoglobin Glycosylation Inhibition Assay and α-Amylase Inhibition Assay in a lab setting.So, the ethanolic solution was the most effective at fighting diabetes. In vivo study was done on it because of this. The extract was determined to be safe up to a level of 5000 mg/kg in a trial on acute poisoning. Anti-diabetic action was tested using a model of diabetes mellitus caused by streptozotocin. The factors that were looked at were changes in body weight and blood sugar levels. It was determined that following significant necrotic alterations, a damaged β-cell population, and smaller cells, the cells in the diabetes control group developed atrophy and fibrosis. The group that got the test amount, on the other hand, had normal pancreatic cells, more and bigger islets, and no necrosis or fibrotic changes. These were about the same amounts as those found in people who took Glibenclamide, which is the common drug. The analysis of phytochemicals showed that flavonoids exist. These chemicals may be what give Adansonia digitata Linn's fruits their ability to help people with diabetes. The current study says that ethanolic extract greatly lowers the chance of getting diabetes in both lab-based and real-life setting

Antiferromagnetic ordering in the doped Kondo insulator CeRhSb

CeRhSb, the so-called ``Kondo insulator," is a mixed-valent compound showing a gap formation in the electronic density of states. On the other hand, CePdSb is ferromagnetically ordered with a Curie temperature of ~17 K. We have carried out magnetic susceptibility and electrical resistivity measurements on CeRh1-xPdxSb (0≤x≤1.0), to study the ground-state properties of this system. For small Pd doping in CeRhSb, up to 20%, the gap continually diminishes and no magnetic ordering is observed down to 2 K. In the region 0.3≤x≤0.4, as soon as the gap is suppressed, an antiferromagnetic ground state is observed. In the region 0.5≤x<0.7, the compounds are not single phase. At the CePdSb end, in the region 0.7≤x≤1, the ground state is ferromagnetic. The observation of an antiferromagnetic phase in the phase diagram of CeRh1-xPdxSb, where neither end is antiferromagnetic, is interesting and is discussed in the light of some recent theoretical models

Magnetic and transport measurements on RAuAl (R=La, Ce, and Nd) compounds: Kondo-lattice behavior of CeAuAl

Magnetic susceptibility, electrical resistivity, and magnetoresistance measurements have been made on RAuAl (R=La, Ce, and Nd) compounds. These reveal that CeAuAl is an antiferromagnetic compound with a Neel temperature of ~3.8 K. Its resistivity shows a shallow minimum at ~20 K and a ln(T) behavior below this temperature. These features suggest a Kondo-lattice behavior in CeAuAl. The compound LaAuAl is metallic down to 2 K while NdAuAl is a ferromagnet with a Curie temperature of ~10 K. The susceptibility of CeAuAl deviates from Curie-Weiss behavior below 70 K and this has been analyzed in terms of crystal-field effects

Ferromagnetic Kondo lattice behavior in CeNiSb

We report magnetic susceptibility, electrical resistivity, and magnetoresistance measurements on hexagonal CeNiSb. These measurements suggest that CeNiSb is ferromagnetically ordered with a transition temperature of about 4 K. Its electrical resistivity shows a weak shallow minimum (at about 15K), characteristic of Kondo lattice systems. Further, in contrast to the other closely related compounds, the orthorhombic CeRhSb and CeNiSn, this compound does not show a rapid rise in its electrical resistivity and hence no Kondo coherence gap formation in the electronic density of states at low temperatures

Growth and Magnetic Properties of Polycrystalline Self-Assembled Bifurcated Co Nanowires

We use anodization of aluminum foil with variable applied anodization voltage to create an alumina template with bifurcated porous structures. The template is then used to electrodeposit Co, fabricating unique bifurcated Co nanowires. In order to better understand the crystal structure of our new material, we then report magnetic properties of these self-assembled bifurcated Co nanowires. Magnetic measurements of the bifurcated wires are studied as functions of branch/stem ratios, wire length, and temperature. The results are compared with those of straight Co nanowires of similar dimensions and thin film Co samples to find that a different crystal lattice structure prevails in the stems than in the branches of the wires

Investigation of electrical transport in hydrogenated multiwalled carbon nanotubes

Highly disordered multiwalled carbon nanotubes of large outer diameter (~60 nm) fabricated by means of chemical vapor deposition process inside porous alumina templates exhibit ferromagnetism when annealed in a H2/Ar atmosphere. In the presence of an applied magnetic field, there is a transition from positive to negative magnetoresistance. The transition may be explained in terms of the Bright model for ordered and disordered carbon structures. Additionally, temperature dependent electrical transport experiments exhibit a zero-bias anomaly at low temperature