Properties of cellulose/Thespesia Lampas short fibers bio-composite films

Abstract: Cellulose was dissolved in pre cooled environment friendly solvent (aq.7% sodium hydroxide+12% urea) and regenerated with 5%H2SO4 as coagulation bath. Using cellulose as matrix and alkali treated short natural fibers extracted from the newly identified Thespesia Lampas plant as reinforcement, the green composite films were prepared. The effect of fiber loading on the tensile properties and thermal stability was studied. The fractographs indicated better interfacial bonding between the fibers and cellulose. The crystallinity of the composite films was found to be lower than the matrix and decreased with increasing fiber content. In spite of better interfacial bonding, the tensile properties of the composites were found to be lower than those of the matrix and decreased with increasing fiber content and this behavior was attributed to the random orientation of the fibers in the composites. The thermal stability of the composite films was higher than the matrix and increased with fiber content

Tensile and thermal properties of poly(lactic acid)/eggshell powder composite films

Biodegradable composite films of poly(lactic acid) (PLA)=eggshell powder (ESP) were prepared by the composite film casting method using chloroform as the solvent. ESP was loaded in PLA in 1 to 5 wt.%. The films were subjected to tensile, FT-IR spectral, thermogravimetric, X-ray, and microscopic analyses. The tensile strength and modulus of the composite films were found to be higher than those of PLA and increased with ESP content up to 4 wt.% and then decreased. A reverse trend was observed in the case of percentage elongation at break. The X-ray diffractograms of the composite films indicated an increase in crystallinity with ESP content. The optical micrographs indicated uniform distribution of ESP particles in the composite films. However, the fractographs indicated agglomeration of ESP particles at 5 wt.% loading. The FT-IR spectra revealed no specific interactions between PLA and ESP. The thermal stability of the composite films increased with ESP content

Extraction and characterization of novel lignocellulosic fibers from Thespesia lampas plant

In this work, the lignocellulosic fibers from the plant Thespesia lampas were extracted and investigated in detail. The prime objective of this work was to study the effect of alkali treatment on the chemical composition, tensile properties, morphological and structural changes, and thermal degradation of Thespesia lampas fibers. Chemical analysis, FT-IR, and 13C CP-MAS NMR spectroscopic studies indicated lowering of amorphous hemicellulose content on alkali treatment. Wide-angle X-ray diffraction studies indicated increase in crystallinity of the fibers on alkali treatment. The tensile strength and modulus of the fibers and thermal stability increased on alkali treatment. Scanning electron micrographs revealed roughening of the surface of the fibers due to the removal of the hemicellulose layer on alkali treatment. Tensile properties of Thespesia fibers were compared to those of other important natural fibers, and it was indicated as an alternative suitable source for composite construction

Nanocomposite cotton fabrics with in situ formed copper nanoparticles using citrus lemon leaf extract as reducing agent

Nanocomposite cotton fabrics (NCCFs) with in situ formed copper nanoparticles (CuNPs) using aqueous extraction of citrus lemon leaves as reducing agent have been made. The NCCFs have been analyzed by SEM, FTIR, XRD and TGA techniques and antibacterial test. The CuNPS have been roughly spherical in shape with a mean size in the range of 82-114 nm. The OH and C-OH groups of leaf extract has played an important role in the generation of the CuNPs in the NCCFs as established by the FTIR spectral analysis. The XRD analysis has indicated that the formation of CuNPs in NCCFs lowered the crystallinity of NCCFs. The thermal stability of NCCFs has been lowered by the CuNPs. However, the NCCFs with in situ generated CuNPs exhibited higher antibacterial activity against both gram-negative and gram-positive bacteria and hence can be effectively used as antibacterial wound dressing and hospital bed materials

Master equations for effective Hamiltonians

We reelaborate on a general method for obtaining effective Hamiltonians that describe different nonlinear optical processes. The method exploits the existence of a nonlinear deformation of the su(2) algebra that arises as the dynamical symmetry of the original model. When some physical parameter (usually related to the dispersive limit) becomes small, we immediately get a diagonal effective Hamiltonian that represents correctly the dynamics for arbitrary states and long times. We apply the same technique to obtain how the noise terms in the original model transform under this scheme, providing a systematic way of including damping effects in processes described in terms of effective Hamiltonians.Comment: 10 pages, no figure

Observation of squeezed light from one atom excited with two photons

Single quantum emitters like atoms are well-known as non-classical light sources which can produce photons one by one at given times, with reduced intensity noise. However, the light field emitted by a single atom can exhibit much richer dynamics. A prominent example is the predicted ability for a single atom to produce quadrature-squeezed light, with sub-shot-noise amplitude or phase fluctuations. It has long been foreseen, though, that such squeezing would be "at least an order of magnitude more difficult" to observe than the emission of single photons. Squeezed beams have been generated using macroscopic and mesoscopic media down to a few tens of atoms, but despite experimental efforts, single-atom squeezing has so far escaped observation. Here we generate squeezed light with a single atom in a high-finesse optical resonator. The strong coupling of the atom to the cavity field induces a genuine quantum mechanical nonlinearity, several orders of magnitude larger than for usual macroscopic media. This produces observable quadrature squeezing with an excitation beam containing on average only two photons per system lifetime. In sharp contrast to the emission of single photons, the squeezed light stems from the quantum coherence of photon pairs emitted from the system. The ability of a single atom to induce strong coherent interactions between propagating photons opens up new perspectives for photonic quantum logic with single emittersComment: Main paper (4 pages, 3 figures) + Supplementary information (5 pages, 2 figures). Revised versio

Transition from antibunching to bunching for two dipole-interacting atoms

It is known that there is a transition from photon antibunching to bunching in the resonance fluorescence of a driven system of two two-level atoms with dipole-dipole interaction when the atomic distance decreases and the other parameters are kept fixed. We give a simple explanation for the underlying mechanism which in principle can also be applied to other systems. PACS numbers 42.50.Ar, 42.50FxComment: Submitted to Phys. Rev. A; 15 pages Latex + 4 figure