Potential of Orange Peel Ash as a Cement Replacement Material

The potential of Orange peel ash (OPA) as a cement replacement material was investigated with focus on the effect of OPA content on the physicomechnical properties such as consistency, setting times, soundness, compressive and flexural strengths of OPA-cement blend for cement replacement between 2.5-10% at 2.5% interval. The optimal calcination temperature and time of orange peel (OP) was achieved by calcining the OP at various temperature between (600 °C, 700 °C, 800 °C) and time (1 hr. and 2 hrs.) respectively. The chemical compositions of the various orange peel ashes were determined using X-ray fluorescence equipment and the optimal conditions was obtained at 600 °C and 2 hours. The consistency and setting time tests were conducted with a Vicat apparatus on the binary cement pastes in accordance to ASTM standards. Results indicated an increase in the water required for consistency as the OPA content was increased from 2.5-10 % which was attributed to the unburnt carbon content present in the ash. Similarly, a gradual increase in the cement replacement with OPA resulted in a prolonged setting time which was could be attributed to the diminution of the clinker content and the higher water requirement for normal consistence. The soundness of the OPA cement blend experienced an increase in free lime content as the OPA content rose from 2.5-10 %. Both compressive and flexural strengths were found to decrease as the OPA content was gradually increased whereas an increase in the strengths were observed as the curing days progressed. It was also observed that 5% cement replacement with OPA did not adversely affect the strength in comparison to the OPC control due to the pozzolanic reaction which resulted in the enhanced strengths especially at 28 days

Phase-sensitive Manipulations of Squeezed Vacuum Field in an Optical Parametric Amplifier inside an Optical Cavity

Squeezed vacuum field can be amplified or deamplified when it is injected, as the signal beam, into a phase-sensitive optical parametric amplifier (OPA) inside an optical cavity. The spectral features of the reflected quantized signal field are controlled by the relative phase between the injected squeezed vacuum field and the pump field for the OPA. The experimental results demonstrate coherent phenomena of OPA in the quantum regime, and show phase-sensitive manipulations of quantum fluctuations for quantum information processing.Comment: 4 pages, 3 figures, appear in Phys. Rev. Let

Electromagnetically-Induced-Transparency-Like Effect in the Degenerate Triple-Resonant Optical Parametric Amplifier

We investigate experimentally the absorptive and dispersive properties of triple-resonant optical parametric amplifier OPA for the degenerate subharmonic field. In the experiment, the subharmonic field is utilized as the probe field and the harmonic wave as the pump field. We demonstrate that EIT-like effect can be simulated in the triple-resonant OPA when the cavity line-width for the harmonic wave is narrower than that for the subharmonic field. However, this phenomenon can not be observed in a double-resonant OPA. The narrow transparency window appears in the reflected field. Especially, in the measured dispersive spectra of triple-resonant OPA, a very steep variation of the dispersive profile of the subharmonic field is observed, which can result in a slow light as that observed in atomic EIT medium.Comment: 10 pages, 4 figures, appear in Opt. Let

Occupational Physical Activity and Cardiovascular Risk Factors Profile in the Adult Population of the Southern Cone of Latin America: Results From the CESCAS I Study

OBJECTIVE: We explore the association between occupational physical activity (OPA) and cardiovascular risk factors in four cities of the Southern Cone. METHODS: Robust multivariable linear regression models were used to examine the associations. RESULTS: The working population was constituted by 1868 men and 1672 women. Men performing high levels of OPA showed higher levels of high-density lipoprotein (HDL; mean adj. diff. = 2.24 mg/dL; P = 0.004), lower levels of triglycerides (-24.59 mg/dL; P = 0.006), and total cholesterol (TC)/HDL ratio values (-0.21; P = 0.015) than reference. Women in the highest category of OPA had higher levels of HDL (2.85 mg/dL; P = 0.006), lower TC/HDL (0.27; P = 0.001), and low-density lipoprotein/HDL ratios (-0.18; P = 0.003) than sedentary activities. CONCLUSION: Individuals who performed high levels of OPA did not exhibit a worse cardiovascular risk profile and an improvement on selected biomarkers was observed when compared with those performing sedentary activities.Fil: Poggio, Rosana. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Melendi, Santiago Ezequiel. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Gutierrez, Laura. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Elorriaga, Natalia. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Irazola, Vilma. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Efectividad Clínica y Sanitaria; Argentin

Enhanced entanglement of two optical modes in optomechanical systems via an optical parametric amplifier

We investigate the effect of a degenerate optical parametric amplifier (OPA) placed inside an optomechanical cavity on the steady-state entanglement of two cavity modes, which jointly interact with a mechanical resonator. Two cavity modes are respectively driven at the red and blue sideband associated with the mechanical resonator, which generates entanglement between them in the limit of resolved sideband. The OPA gives rise to single-mode squeezing of the cavity fields, which results in significant improvement of the two-mode entanglement. It is found that an optimal nonlinear gain of the OPA exists, depending on the system temperatures, which yields the maximum entanglement. The improvement is particularly remarkable for the system at cryogenic temperatures.Comment: 14 pages, 5 figures, to appear in J. Phys.

Generation of Polarization Squeezing with Periodically Poled KTP at 1064 nm

We report the experimental demonstration of directly produced polarization squeezing at 1064 nm from a type I optical parametric amplifier (OPA) based on a periodically poled KTP crystal (PPKTP). The orthogonal polarization modes of the polarization squeezed state are both defined by the OPA cavity mode, and the birefringence induced by the PPKTP crystal is compensated for by a second, but inactive, PPKTP crystal. Stokes parameter squeezing of 3.6 dB and anti squeezing of 9.4 dB is observed.Comment: 4 pages, 2 figure

Fracture Mechanics Characterization of an AnisotropicGeomaterial

Argillites are considered worldwide as potential host rock for high level radioactive waste given the low permeability and strong adsorption potential. However, the excavation of the galleries of a repository would produce a disturbed zone around the boundaries rich of new fractures which may enhance the conductivity of the rock along the gallery axis. Several mine-by experiments have been performed in underground rock labs to investi- gate the features of the disturbed zone. In Mont Terri URL (Kanton Jura, Switzerland) the EZ-B experiment was specifically conceived for the measurement of excavation induced fractures around a small chamber. The host rock of the URL is a particularly compact and resistant argillite, known as the Opalinus Clay (OPA) excavated and OPA samples were subjected to fracture mechanics tests at the rock mechanics lab of IGAG-CNR in Torino, Italy. The tests aimed at the understanding aspects of the fracturing process occurring in OPA of Mont Terri, which may be considered a transversely isotropic geomaterial, whose planes of isotropy coincide with the beddin

Persistence of two genotypes of Neisseria gonorrhoeae during transmission.

Isolates of Neisseria gonorrhoeae were tested using a highly discriminatory typing method, opa typing, to examine the genetic diversity over a 2-year study period of isolates from all consecutive patients with gonorrhea attending the Genitourinary Medicine clinic in Sheffield, United Kingdom. Two opa genotypes were detected throughout the 2-year time period and comprised 41% of all strains tested. The persistence of two opa types was investigated further to determine the apparent genetic stability, by examining the ability of isolates to undergo intragenic and intergenic recombination and mutation in vitro. Intragenic recombination or mutation involving the opa genes of N. gonorrhoeae in the selected isolates was not detected, but intergenic recombination did occur. opa genes of N. gonorrhoeae in vivo appear to diversify primarily through intergenic recombination. Intergenic recombination in vivo would require the presence of a mixed gonococcal infection, in which an individual is concurrently colonized with more than one strain of N. gonorrhoeae. We propose that the level of diversity of opa genotypes in a population is linked to the degree of sexual mixing of individuals and the incidence of mixed infections of N. gonorrhoeae