Experimental study of an in-fiber acousto-optic tunable bandpass filter for single- and dual-wavelength operation in a thulium-doped fiber laser

A tunable single- and dual-wavelength thulium-doped all-fiber laser is demonstrated based on the implementation of an in-fiber acousto-optic tunable bandpass filter (AOTBF). The AOTBF is fabricated to be operated in the 1.9 µm region, and takes advantage of the intermodal coupling effect produced by traveling flexural acoustic waves in an optical fiber. It exhibits a 3-dB bandwidth of 2.04 nm with an insertion loss of 4.75 dB. The tuning properties of the AO device allows a continuous-wave operation with characteristics of wide tuning range (211.5 nm), narrow linewidth (50 pm) and high signal-to-noise ratio (60 dB). In the dual-wavelength regime, the laser is capable of independent tuning of each of the laser lines, achieving a tunable dual-wavelength emission that extends from 1802.67 to 1932.75 nm. A controllable wavelength spacing with minimum and maximum separations of 1.04 and 130.08 nm is obtained

Antagonistic Interaction of Staphylococcus aureus Toward Candida glabrata During in vitro Biofilm Formation Is Caused by an Apoptotic Mechanism

Background: Infections caused by Candida species and Staphylococcus aureus are associated with biofilm formation. C. albicans–S. aureus interactions are synergistic due to the significant increase in mixed biofilms and improved resistance to vancomycin of S. aureus. C. glabrata and S. aureus both are nosocomial pathogens that cause opportunistic infections in similar host niches. However, there is scarce information concerning the interaction between these last microorganisms.Results: The relationship between C. glabrata and S. aureus was evaluated by estimating the viability of both microorganisms in co-culture of planktonic cells and in single and mixed biofilms. An antagonistic behavior of S. aureus and their cell-free bacterial supernatant (CFBS) toward C. glabrata, both in planktonic form and in biofilms, was demonstrated. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal laser scanning microscopy (CLSM) images showed yeast cells surrounded by bacteria, alterations in intracytoplasmic membranes, and non-viable blastoconidia with intact cell walls. Concomitantly, S. aureus cells remained viable and unaltered. The antagonistic activity of S. aureus toward C. glabrata was not due to cell-to-cell contact but the presence of CFBS, which causes a significant decrement in yeast viability and the formation of numerous lipid droplets (LDs), reactive oxygen species (ROS) accumulation, as well as nuclear alterations, and DNA fragmentation indicating the induction of an apoptotic mechanism.Conclusion: Our results demonstrate that the S. aureus CFBS causes cell death in C. glabrata by an apoptotic mechanism

Broadband tuning of a long-cavity all-fiber mode locked Thulium-doped fiber laser using an acousto-optic bandpass filter

A long-cavity passively mode-locked thulium-doped all-fiber laser is reported incorporating a tapered acousto-optic tunable bandpass filter (AOTBF). The operation of the AOTBF relies on the intermodal coupling between core and cladding modes when a flexural acoustic wave propagates along an 80-microm tapered fiber. The filter works in transmission and exhibits a 3-dB bandwidth of 9.02 nm with an insertion loss of 3.4 dB. The laser supports ultrashort pulse generation at a low repetition rate of 784.93 kHz. Optical pulses with 2.43 nm of optical bandwidth and 2.1 ps pulse duration were obtained in a broad tuning range from 1824.77 to 1905.16 nm

Q switching and mode locking pulse generation from an all-fiber ring laser by intermodal acousto-optic bandpass modulation

Q-switched and mode-locked (QML) pulse generation from an all-fiber ring laser based on intermodal acousto-optic bandpass modulation is reported. The modulator relies on full-acousto-optic mode re-coupling cycle induced by a standing flexural acoustic wave, with a transmission response that is controlled by amplitude modulation of the acoustic wave signal. The Q factor of the cavity is controlled by a rectangular pulse wave with variable frequency and duty cycle, whereas mode locking is achieved by amplitude modulation derived from a standing flexural acoustic wave. The best QML pulses were obtained at 0.5 kHz repetition rate, with a pump power of 549.2 mW, at the optical wavelength of 1568.2 nm. A maximum overall energy of 2.14 µJ at an average output power of 1.07 mW was achieved, corresponding to a burst of mode-locked sub-pulses of 100 ps pulse duration within a QML envelope of 3.5 µs

Chitosan–Starch–Keratin composites: Improving thermo-mechanical and degradation properties through chemical modification

The lysozyme test shows an improved in the degradability rate, the weight loss of the films at 21 days is reduced from 73 % for chitosan-starch matrix up to 16 % for the composites with 5wt% of quill; but all films show a biodegradable character depending on keratin type and chemical modification. The outstanding properties related to the addition of treated keratin materials show that these natural composites are a remarkable alternative to potentiat-ing chitosan–starch films with sustainable featuresChitosan–starch polymers are reinforced with different keratin materials obtained from chicken feather. Keratin materials are treated with sodium hydroxide; the modified surfaces are rougher in comparison with untreated surfaces, observed by Scanning Electron Microscopy. The results obtained by Differential Scanning Calorimetry show an increase in the endothermic peak related to water evaporation of the films from 92 °C (matrix) up to 102–114 °C (reinforced composites). Glass transition temperature increases from 126 °C in the polymer matrix up to 170–200 °C for the composites. Additionally, the storage modulus in the composites is enhanced up to 1614 % for the composites with modified ground quill, 2522 % for composites with modified long fiber and 3206 % for the composites with modified short fiber. The lysozyme test shows an improved in the degradability rate, the weight loss of the films at 21 days is reduced from 73 % for chitosan-starch matrix up to 16 % for the composites with 5wt% of quill; but all films show a biodegradable character depending on keratin type and chemical modification. The outstanding properties related to the addition of treated keratin materials show that these natural composites are a remarkable alternative to potentiat-ing chitosan–starch films with sustainable featuresUniversidad Autónoma del Estado de México Tecnológico Nacional de México, Instituto Tecnológico de Querétaro Universidad Nacional Autónoma de México Tecnológico Nacional de México, Instituto Tecnológico de Celaya Universidad Autónoma de Cd. Juáre

Synthesis, crystal structure, and preliminary study of luminescent properties of InTbGe2O7

A new indium terbium germanate InTbGe2O7, which is a member of the thortveitite family, was prepared as a polycrystalline powder material by high-temperature solid-state reaction. This new compound crystallizes in the monoclinic system, space group C2/c (No. 15), with unit cell parameters a = 6.8818(2)Angstrom, b = 8.8774(3)Angstrom, c = 9.7892(4)Angstrom, beta = 101.401 (1)degrees V = 586.25(4)Angstrom(3) and Z = 4. Its structure was characterized by Rietveld refinement of powder laboratory X-ray diffraction data. It consists of octahedral sheets that are held together by sheets of isolated Ge2O7 diorthogroups composed of two tetrahedra sharing a common vertex. It contains only one octahedral site occupied by In3+ and Tb+3 cations. The characteristic mirror plane in the thortveitite (SC2Si2O7) space group (C2/m, No. 12) is not present in this new compound. Besides, in InTbGe2O7, the Ge-O-Ge angle bridging two diorthogroups is 156.8(2)degrees as compared to the one in thortveitite, which is 180degrees. On the other hand, luminescent properties were observed when it is excited with 376.5 nm wavelength. The luminescence spectrum shows typical transitions from the D-5(4) multiplet belonging to the trivalent terbium ion. (C) 2003 Elsevier Science (USA). All rights reserved

DETECTION OF CR3+ SITES IN LINBO3MGO,CR3+ AND LINBO3CR3+

In this work, experimental results describing Cr3+ sites in LiNbO3:Cr and LiNbO3:MgO,Cr previously determined with electron-paramagnetic-resonance (EPR), electron-nuclear-double-resonance, and optical techniques, are correlated in terms of the formation of three chromium sites:Cr3+ ions in Li+ and Nb5+ positions, and a Cr3+ (Nb5+)-Mg2+ center that only appears in the double-doped system. It is concluded that the majority of the unperturbed centers, Cr3+ (Li+) and Cr3+ (Nb5+), are forming close pairs and only a small fraction of Cr3+ (Li+) ions are diluted into the crystal host, giving rise to an EPR signal

A simple blind test of hypoglycemic effect of phyllanthus niruri (huevito escondido) and its combination with azadirachta indica (nim) in wistar rats.

Objetivo: valorar el efecto ipoglucemiante de un extracto acuoso de la planta entera Phyllantus niruri, hojas de Azadirachta indica y su combinación. Métodos: Se diseñó un ensayo cruzado a ciego simple, preparándose extractos acuosos de hojas de A. indica y planta entera de P. niruri, colocando 70 g en 200 mL de agua a 55-60 °C, conformando tres tratamientos: uno para cada extracto y el tercero la combinación. Como control positivo o de referencia se utilizó el extracto de A. Indica. Se emplearon 18 ratas Wistar a las que se administró el tratamiento vía oral una sola vez, a razón de 5mL/300 g de peso. La glucemia se midió con un glucómetro One Touch Ultra antes y 2h después del tratamiento. Se aplicó la prueba ANOVA a los datos. Resultados: Hubo disminución de la glucemia con los tres tratamientos. No se encontró diferencia entre los tratamientos probados. Conclusiones: el extracto acuoso de la planta entera de Phyllanthus niruri tiene un efecto hipoglucemiante similar al extracto acuoso de hojas de Azadirachta indica. No hubo evidencia de efecto siné[email protected]: to evaluate the hypoglycemic effect of aqueous extract of Phyllanthus niruri whole plant and its combination with one of Azadirachta indica leaves. Methods: A single-blind crossover trial was design. One for each extract and the third corresponding to the combination: aqueous extracts of leaves of Azadirachta indica and whole plant Phyllanthus niruri, placing 70g of the plant material in 200 mL of water at 55-60 ° C, three treatments were prepared. The comparison was performed using the extract of Azadirachta indica as control. Eighteen Wistar rats were used. Treatment was given orally at a dose of 5 mL/300 g. Glucose measurement was made with a glucometer One Touch Ultra before and 2h after administration of the treatment. ANOVA was applied to the data. Results: There was a decrease in blood glucose levels with the three treatments. No difference was found between the tested treatments regarding the hypoglycemic effect. Conclusions: The aqueous extract of the whole plant of Phyllanthus niruri has a similar hypoglycemic effect to aqueous extract of Azadirachta indica leaves. There was no evidence of synergistic effect

Transmission of Anaplasma marginale by unfed Rhipicephalus microplus tick larvae under experimental conditions

The current description of biological transmission of Anaplasma marginale by Rhipicephalus microplus ticks, includes both intrastadial and transstadial transmission. Both transovarial transmission of Anaplasma from engorged ticks to their progeny and, transmission from infected unfed larvae to the mammalian host are is controversial. In order to demonstrate vertical transmission of A. marginale by R. microplus ticks under experimental conditions, feed-acquisition infected engorged females were incubated at 18° C or 28° C for oviposition. Larvae hatched from these ticks were used to infest two steers for each incubation temperature. None of the four steers infested with either lot of larvae developed clinical disease, yet subclinical infection was observed in the steers infested with larvae from engorged ticks incubated at 28°. DNA from larvae used for the infection of the carrier tick donor, Only DNA from larvae oviposited  at 28 ºC, DNA from blood of positive steers were positive for amplification of msp5 and msp1α variable region by PCR. All other DNA samples from the original stabilate, blood from the donor steer, larvae from ticks incubated at 28° C and steers infested with these same larvae were positive both to msp5 and msp1α PCR. msp1α sequences of all PCR products were the same and coincided with previously reported Tlapacoyan-2 sequence. The present evidence indicates that R. microplus is capable of transmitting A. marginale to its progeny and that these infected larvae can transmit the infection to susceptible hosts.