Dynamics of broken symmetry nodal and anti-nodal excitations in Bi_{2} Sr_{2} CaCu_{2} O_{8+\delta} probed by polarized femtosecond spectroscopy

The dynamics of excitations with different symmetry is investigated in the superconducting (SC) and normal state of the high-temperature superconductor Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ (Bi2212) using optical pump-probe (Pp) experiments with different light polarizations at different doping levels. The observation of distinct selection rules for SC excitations, present in A$_{{\rm 1g}}$ and B$_{{\rm 1g}}$ symmetries, and for the PG excitations, present in A$_{{\rm 1g}}$ and B$_{{\rm 2g}}$ symmetries, by the probe and absence of any dependence on the pump beam polarization leads to the unequivocal conclusion of the existence of a spontaneous spatial symmetry breaking in the pseudogap (PG) state

Compression and strength behaviour of viscose/polypropylene nonwoven fabrics

Compression and strength properties of viscose/polypropylene nonwoven fabrics has been studied. Compressionbehavior of the nonwoven samples (sample compressibility, sample thickness loss & sample compressive resilience) havebeen analyzed considering the magnitude of applied pressure, fabric weight, fabric thickness, and the porosity of thesamples. Based on the calculated porosity of the samples, pore compression behavior (pore compressibility, porosity loss &pore compressive resilience) are determined. Equations for the determination of pore compressibility, porosity loss, and porecompressive resilience, are established. Tensile strength and elongation as well as bursting strength and ball traverseelongation are also determined. The results show that the sample compression behavior as well as pore compressionbehavior depend on the magnitude of applied pressure. At the high level of applied pressure, a sample with highercompressibility has the lower sample compressive resilience. Differences in pore compressibility and porosity loss betweeninvestigated samples have also been registered, except in pore compressive resilience. Sample with the higher fabric weight,higher thickness, and lower porosity shows the lower sample compressibility, pore compressibility, sample thickness loss,porosity loss, and tensile elongation, but the higher tensile strength, bursting strength, and ball traverse elongation

Laser-driven quantum magnonics and THz dynamics of the order parameter in antiferromagnets

The impulsive generation of two-magnon modes in antiferromagnets by femtosecond optical pulses, so-called femto-nanomagnons, leads to coherent longitudinal oscillations of the antiferromagnetic order parameter that cannot be described by a thermodynamic Landau-Lifshitz approach. We argue that this dynamics is triggered as a result of a laser-induced modification of the exchange interaction. In order to describe the oscillations we have formulated a quantum mechanical description in terms of magnon pair operators and coherent states. Such an approach allowed us to} derive an effective macroscopic equation of motion for the temporal evolution of the antiferromagnetic order parameter. An implication of the latter is that the photo-induced spin dynamics represents a macroscopic entanglement of pairs of magnons with femtosecond period and nanometer wavelength. By performing magneto-optical pump-probe experiments with 10 femtosecond resolution in the cubic KNiF$_3$ and the uniaxial K$_2$NiF$_4$ collinear Heisenberg antiferromagnets, we observed coherent oscillations at the frequency of 22 THz and 16 THz, respectively. The detected frequencies as a function of the temperature ideally fit the two-magnon excitation up to the N\'eel point. The experimental signals are described as dynamics of magnetic linear dichroism due to longitudinal oscillations of the antiferromagnetic vector.Comment: 25 pages, 10 figure

Quality of clothing fabrics in terms of their comfort properties

Quality of various clothing woven fabrics with respect to their comfort properties, such as electro-physical properties, air permeability, and compression properties has been studied. Fabrics are produced from cotton and cotton/polyester fibre blends in plain, twill, satin and basket weave. Results show that cotton fabrics have lower values of the volume resistivity, air permeability and compressive resilience but higher values of effective relative dielectric permeability and compressibility as compared to fabrics that have been produced from cotton/PES fibre blends. Regression analysis shows a strong linear correlative relationship between the air permeability and the porosity of the woven fabrics with very high coefficient of linear correlation (0.9807). It is also observed that comfort properties are determined by the structure of woven fabrics (raw material composition, type of weave) as well as by the fabrics surface condition. Findings of the studies have been used for estimating the quality of woven fabrics in terms of their comfort properties by the application of ranking method. It is concluded that the group of cotton fabrics exhibits better quality of comfort as compared to the group of cotton/PES blend fabrics.

Quasiparticle relaxation dynamics in heavy fermion compounds

We present the first femtosecond studies of electron-phonon (e-ph) thermalization in heavy fermion compounds. The e-ph thermalization time tau_{ep} increases below the Kondo temperature by more than two orders of magnitude as T = 0 K is approached. Analysis using the two-temperature model and numerical simulations based on Boltzmann's equations suggest that this anomalous slowing down of the e-ph thermalization derives from the large electronic specific heat and the suppresion of scattering between heavy electrons and phonons.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. Let

Finite-wavevector Jahn-Teller-pairing and superconductivity in the cuprat es

A model interaction is proposed in which pairing is caused by a non-local Jahn-Teller (JT) -like instability due to the coupling between planar O states and knot equal to 0 phonons. Apart from pairing, the interaction is found to naturally allow metallic stripe formation. The consequences of the model for superconductivity in the cuprates are discussed. The model is shown to be consistent with numerous sets of experimental data in quite some detail.Comment: 20 pages, 6 ps figure

Antioksidativna aktivnost metanolskog ekstrakta lista biljke Saxifraga Rotundifolia L.

The aim of this study was to investigate the potential antioxidant activity of the methanol leaf extract of Saxifraga rotundifolia L., depending on the total quantity of phenols, flavonoids and flavonol. The tested extracts showed high phenolic content (324.39 mg GA/g) and small amounts of flavonoids (36.81 mg RU/g) and flavonols (11.52 mg RU/g). The antioxidant activity was determined by a series of in vitro methods. The tested extracts showed high level of total antioxidant activity (509.78 mg AA/g), and high degree of ABTS+ and DPPH "scavenger" activity with IC50 value of 48.76 μg/mL for ABTS+ method and 30.39 μg/mL for DPPH method. The results indicate that the tested extract has significant antioxidant activity and can be a source of natural antioxidants.Cilj rada je bio da se ispita potencijalna antioksidativna aktivnost metanolskog ekstrakta lista biljke Saxifraga rotundifolia L. u zavisnosti od ukupne količine fenola, flavonoida i flavonola. Ispitivani ekstrakt pokazao je visok sadržaj fenola (324,39 mg GA/g) i manje količine flavonoida (36,81 mg RU/g) i flavonola (11,52 mg RU/g). Antioksidativna aktivnost određena je serijom in vitro metoda. Ispitivani ekstrakt pokazuje visok nivo ukupne antioksidativne aktivnosti (509,78 mg AA/g), kao i visok stepen АBTS+. i DPPH ,,skevindžer“ aktivnosti sa IC50 vrednošću od 48,76 μg/mL za ABTS+. i 30,39 μg/mL za DPPH metodu. Dobijeni rezultati ukazuju da ispitivani ekstrakt poseduje značajnu antioksidativnu aktivnost i može biti izvor prirodnih antioksidanata