Characterization of the Torsional Piezoelectric-like Response of Tantalum Trisulfide Associated with Charge-Density-Wave Depinning

We have studied the frequency and voltage dependence of voltage-induced torsional strains in orthorhombic TaS3 [V. Ya. Pokrovskii, et al, Phys. Rev. Lett. 98, 206404 (2007)] by measuring the modulation of the resonant frequency of an RF cavity containing the sample. The strain has an onset voltage below the charge-density-wave (CDW) threshold voltages associated with changes in shear compliance and resistance, suggesting that the strain is associated with polarization of the CDW rather than CDW current. Measurements with square-wave voltages show that the strain is very sluggish, not even reaching its dc value at a frequency of 0.1 Hz, but the dynamics appear to be very sample dependent. By applying oscillating torque while biasing the sample with a dc current, we have also looked for strain induced voltage in the sample; none is observed at the low biases where the voltage-induced strains first occur, but an induced voltage is observed at higher biases, probably associated with strain-dependent CDW conductance.Comment: 11 pages, including 3 figures, to be published in Phys. Rev. B (Rapid Comm.

Site-selective quantum correlations revealed by magnetic anisotropy in the tetramer system SeCuO3

We present the investigation of a monoclinic compound SeCuO3 using x-ray powder diffraction, magnetization, torque and electron-spin-resonance (ESR). Structurally based analysis suggests that SeCuO3 can be considered as a 3D network of tetramers. The values of intra-tetramer exchange interactions are extracted from the temperature dependence of the susceptibility and amount to ~200 K. The inter-tetramer coupling leads to the development of long-range antiferromagnetic order at TN = 8 K. An unusual temperature dependence of the effective g-tensors is observed, accompanied with a rotation of macroscopic magnetic axes. We explain this unique observation as due to site-selective quantum correlations

Dynamics of the Electro-Optic response of Blue Bronze

We have studied the charge density wave (CDW) repolarization dynamics in blue bronze by applying square-wave voltages of different frequencies to the sample and measuring the changes in infrared transmittance, proportional to CDW strain. The frequency dependence of the electro-transmittance was fit to a modified harmonic oscillator response and the evolution of the parameters as functions of voltage, position, and temperature are discussed. Resonant frequencies decrease with distance from the current contacts, indicating that the resulting delays are intrinsic to the CDW with the strain effectively flowing from the contact. For a fixed position, the average relaxation time has a voltage dependence given by tau_0~V^-p, with 1<p<2. The temperature dependence of the fitting parameters shows that the dynamics are governed by both the force on the CDW and the CDW current: for a given force and position, both the relaxation and delay times are inversely proportional to the CDW current as temperature is varied. The long relaxation and delay times (~ 1 ms) suggest that the strain response involves the motion of macroscopic objects, presumably CDW phase dislocation lines.Comment: 36 pages, including 12 figures, submitted to Phys. Rev.

LiFePO4 nanocrystals synthesis by hydrothermal reduction method

The nanocrystals of LiFePO4 a cathode material for Li-ion batteries were synthesized by simple one – pot combined colloidal hydrothermal reduction approach. The influences of surfactant ratios on nanocrystal formation are investigated. Also extent of surface modification and agglomeration is assessed. The electrochemical performance of material is investigated on as prepared samples and on samples with carbonized surface layer. The XRD, TEM, SEM, FTIR, laser diffraction PSA, magnetic measurements and galvanostatic cycling are performed characterization techniques

Direct observation of active material concentration gradients and crystallinity breakdown in LiFePO4 electrodes during charge/discharge cycling of lithium batteries

The phase changes that occur during discharge of an electrode comprised of LiFePO4, carbon, and PTFE binder have been studied in lithium half cells by using X-ray diffraction measurements in reflection geometry. Differences in the state of charge between the front and the back of LiFePO4 electrodes have been visualized. By modifying the X-ray incident angle the depth of penetration of the X-ray beam into the electrode was altered, allowing for the examination of any concentration gradients that were present within the electrode. At high rates of discharge the electrode side facing the current collector underwent limited lithium insertion while the electrode as a whole underwent greater than 50% of discharge. This behavior is consistent with depletion at high rate of the lithium content of the electrolyte contained in the electrode pores. Increases in the diffraction peak widths indicated a breakdown of crystallinity within the active material during cycling even during the relatively short duration of these experiments, which can also be linked to cycling at high rate

Optical properties of exfoliated MoS2 coaxial nanotubes - analogues of graphene

We report on the first exfoliation of MoS2 coaxial nanotubes. The single-layer flakes, as the result of exfoliation, represent the transition metal dichalcogenides' analogue of graphene. They show a very low degree of restacking in comparison with exfoliation of MoS2 plate-like crystals. MoS2 monolayers were investigated by means of electron and atomic force microscopies, showing their structure, and ultraviolet-visible spectrometry, revealing quantum confinement as the consequence of the nanoscale size in the z-direction

Repurposing agricultural waste as low-cost cultured meat scaffolds

Growing meat in vitro using tissue engineering and bioproduction techniques (cellular agriculture) has become an increasingly promising solution to the global food security challenge. Our lab has established methods to cultivate bovine muscle tissue on decellularized plants, representing a viable low-cost, sustainable method to grow meat on edible scaffolds. Most work in this area has focused on the use of edible plant materials (i.e., spinach leaves, apple, broccoli) with inherent economic value. Harvest waste such as corn husk or jackfruit represent abundant sources of cellulose for scaffold production and may be a viable alternative. The present study aims to investigate production of cultured meat through tissue engineering and bioproduction on decellularized, edible samples of corn husk and jackfruit rind. Corn husks and jackfruit rinds were exposed to immersion decellularization. DNA quantification and histological analysis demonstrated sufficient decellularization (0.17 ± 0.06 and 0.07 ± 0.00 ug DNA/g tissue for corn husk and jackfruit rinds, respectively). Following decellularization, corn husk scaffold stiffnesses decreased from 56.67±16.71 MPa to 12.95±2.43 MPa in fiber-aligned direction, while jackfruit decreased from 7.54 ±2.42 MPa to 2.47±1.47 MPa. Seeded scaffolds with bovine satellite cells (BSCs) (11.45±2.24 ug/ul lysate/Gram) and avian (QM7s) (12.90±1.99 ug/ul lysate/Gram) demonstrated increased protein yields on jackfruit scaffolds. QM7 cultured on corn husk scaffolds yielded increased protein but PBSCs seeded on corn husks did not yield protein content higher than controls (QM7 on corn husk: 16.28±3.55, PBSCs on corn husks: 9.57±1.56 ug/ul lysate/Gram, control: 6.35±1.43 ug/ul lysate/Gram). Additionally, cell transfer from scaffold to scaffold (bead-to-bead transfer) was observed on corn husk scaffolds in a dynamic environment. These results suggest that decellularized harvest waste scaffolds may aid in realization of cultured meat products that will contribute to a more robust and environmentally sustainable food supply