Durability of the refractive index change induced by a single femtosecond laser pulse in glass

Ultrafast-laser inscribed optical memories have been considered as a high-density low-energy-consumption alternative to the magnetization-based memories. The optical memories are based on laser-induced material modifications resulting in the refractive index change. The long-term stability of such modifications has been indicated by subjecting them to the accelerated aging by annealing at elevated temperatures. Here, the first direct evidence is provided of the durability of the type II refractive index change in BK7 glass. The investigation was performed for over 27 months at room temperature. The results show the existence of the laser pulse intensity threshold above which the magnitude of the index change does not deteriorate with time and, hence, is suitable for optical memory, photonic crystal and fibre-grating writing. © 201

Multiple period resonances of long period gratings in photonic crystal fibre

A comprehensive eigenmode analysis is performed of the guided modes supported by typical photonic crystal fiber. These modes exhibit unusual phase matching conditions requiring multiple grating periods for resonant coupling. All the signature features of the experimentally observed transmission spectra are explained by multiple-period resonances

Monitoring of respiratory volumes by an long period grating sensor of bending

Here, we present a method of respiratory volumes monitoring using a single fiber-grating sensor of bending. Measurements are conducted using simple monochromatic interrogation scheme that relies on a photodiode measurement of the power transmitted through a long period grating (LPG) sensor at fixed wavelength. Good sensor accuracy in measurements of tidal and minute respiratory volumes for different types of breathing is achieved.Conference on Light in Nanoscience and Nanotechnology (LNN), Oct 20-22, 2015, Hissar, Bulgari

The Effect of Soy Flour on Cookie Quality

Cookies are a popular confectionery product with a unique texture and taste, long shelf life and a relatively cheap price; therefore, it is a widespread snack among people of all generations. Nevertheless, cookies are usually made of wheat flour and most formulations are highly caloric and have a low fiber content. Soy flour is an excellent source of proteins, fibers, vitamins and minerals and it is being considered as a great supplement to wheat flour because it increases nutritive characteristics of the final product. By their digestibility and amino acid content, soy proteins are very similar to proteins derived from animals. They also contain many essential amino acids, which are deficient in most of the cereals. The purpose of this work was to determine the effect of soy flour on quality of cookies. Wheat flour was supplemented with 35% of soy flour (full-fat toasted, low-fat toasted, defatted lightly toasted, toasted and soy protein concentrate). The supplementation of wheat flour with soy flour had affected nutritive value and sensory characteristics of cookies

A multi-state interferometer on an atom chip

Matter-wave interferometry is a powerful tool for high-precision measurements of the quantum properties of atoms, many-body phenomena and gravity. The most precise matter-wave interferometers exploit the excellent localization in momentum space and coherence of the degenerate gases. Further enhancement of the sensitivity and reduction of complexity are crucial conditions for the success and widening of their applications. Here we introduce a multi-state interferometric scheme that offers advances in both these aspects. The coherent coupling between Bose-Einstein condensates in different Zeeman states is used to generate high-harmonic output signals with an enhanced resolution and the maximum possible interferometric visibility. We demonstrate the realization of such an interferometer as a compact, easy to use, atomchip device. This provides an alternative method for the measurement of the light-atom and surface-atom interactions and enables the application of multi-parameter sensing schemes in cold-atom interferometry

Study on chemical, bioactive and food preserving properties of Laetiporus sulphureus (Bull.: Fr.) Murr.

Laetiporus sulphureus (Bull.: Fr.) Murr. was studied regarding the nutritional value, bioactive compounds, in vitro antioxidant, antimicrobial and antitumor activities. The studied mushroom is a rich source of carbohydrates and proteins. Mannitol and trehalose were the main free sugars, and polyunsaturated fatty acids. α-, γ- and δ-Tocopherols were found. Oxalic and citric acids were the most abundant organic acids; cinnamic and p-hydroxybenzoic acids were quantified in the methanolic extract and could be related to the antioxidant properties. It was the polysaccharidic extract that exhibited, higher antioxidant and antimicrobial activities, indicating that compounds present in this extract possess stronger bioactivity. Only polysaccharidic extract revealed antiproliferative activity of human tumor cell lines. A suitable model system with chicken pate was also developed to test antimicrobial preserving properties of L. sulphureus. The methanolic extract was used to examine in situ preserving properties against Aspergillus flavus and demonstrated excellent preserving potential.The authors are grateful to Foundation for Science and Technology (FCT, Portugal) and COMPETE/QREN/EU for financial support to this work (research project PTDC/AGR-ALI/110062/2009 and L. Barros researcher contract under “Programa Compromisso com Ciência-2008”) and to CIMO (strategic project PEst-OE/AGR/UI0690/2011). The authors also thank the Serbian Ministry of Education and Science for financial support (grant number 173032) and Mr Dragoljub Ratkovic for providing us with fresh material of the mushroom Laetiporus sulphureus

Light pulse analysis with a multi-state atom interferometer

We present a controllable multi-state cold-atom interferometer that is easy-to-use and fully merged on an atom chip. We demonstrate its applications as a sensor of the fields whose interactions with atoms are state-dependent.11th International Conference on Quantum Communication, Measurement and Computing (QCMC), Jul 30-Aug 03, 2012, Vienna Univ Technol, Vienna, Austri

Long-period grating fiber-optic sensors of bending for applications in pulmonology

U ovom radu predstavili smo fiber-optički senzor krivine na bazi rešetke sa dugim periodom i njegovu primenu u praćenju disanja pri mehaničkoj ventilaciji pacijenata. Predložena šema merenja koristi monohromatski izvor svetlosti i fotodiodu kao detektor što je čini ekonomičnom i jednostavnom za upotrebu. Ovde smo demonstrirali primenu senzora u merenju disajnih zapremina koja se zasniva na korelaciji izmenu promene zapremine pluća i promene lokalne krivine torza. Poređenjem rezultata studije na skupu od 15 zdravih dobrovoljaca sa konkurentnim metodima zaključujemo da je predloženi neinvazivni metod pogodan za kliničku praksu.Here we present a fibre-optic sensor of bending and demonstrate its application in monitoring of assisted breathing. The sensor is based on a long-period fibre grating and uses a simple monochromatic interrogation scheme. Here, we first explain the working principle of the sensor and then present a method for the measurement of respiratory volumes. The measurement is based on the correlation between a change in lung volume and the corresponding change in a local torso curvature. We validate the method by applying a calibration-test measurement procedure on a set of 15 healthy volunteers. Results show good sensor accuracy in measurements of the tidal and minute respiratory volumes for clinically relevant types of breathing. Finally, we compare the proposed method with the current clinical standards and competing techniques