Numerical investigation of nanostructured silica PCFs for sensing applications.

Photonic crystal fibers (PCFs) developed using nanostructured composite materials provide special optical properties. PCF light propagation and modal characteristics can be tailored by modifying their structural and material parameters. Structuring and infusion of liquid crystal materials enhances the capabilities of all silica PCFs, facilitating their operation in different spectral regimes. The wavelength tunability feature of nanostructured PCFs can be utilized for many advanced sensing applications. This paper discusses a new approach to modify the optical properties of PCFs by periodic nanostructuring and composite material (liquid crystal-silica) infiltration. PCF characteristics like confinement wavelength, confinement loss, mode field diameter (MFD) and bandwidth are investigated by varying the structural parameters and material infiltrations. Theoretical study revealed that composite material infusion resulted in a spectral band shift accompanied by an improvement in PCF bandwidth. Moreover, nanostructured PCFs also achieved reduced confinement losses and improved MFD which is very important in long-distance remote sensing applications

Intensity modulation effect on second harmonic profile of methane detection using wavelength modulation spectroscopy

The effect of intensity modulation (IM) of a tunable diode laser (TDL) on the wavelength modulation spectroscopy (WMS) and second harmonic (2f) lineshape profile of methane near 1666nm is experimentally investigated. The results are quantified and shown as a function of modulation dep

Methane concentration measurement using tunable diode laser in near infrared spectrum

The main element for a successful laser-based gas sensing system significantly relies on the availability and performance of tunable laser sources in the measurement spectra. In addition, an appropriate detection scheme should be adopted to obtain a sensitive measurement. Wavelength modulation spectroscopy (WMS) is considered as a sensitive measuring technique in a gas monitoring applications. The paper investigates the experimental results of laser-based methane detection system using WMS technique. Methane absorption lines in near infrared spectrum are targeted using tunable distributed feedback laser (DFB) by modulating the laser current over the absorption lines. Methane concentrations in the range from 0.1% to %5 volume concentration in mixtures with nitrogen as a background gas have been successfully measured

Systematics, Bioecology, and Medical Importance of Widow Spiders (Lathrodectus spp.) in Khorasan Province, Iran

Following the hospitalization of 195 individuals due to the spider bite in 1995 and three cases of recorded death in the year of 1993 which were referred to Emam Reza Hospital in Mashad, the present study was undertaken on bionomics and medical importance of Lathrodectus spp in Khorasan Province, during 1995-2005. A total cases of 195 bites were studied composing of 70.8 % males and 29.2% females. The most prevalence cases were observed in mid age (20-55 years old) and par¬ticularly among farmers (36.4%). A total number of 216 adult widow spiders and 258 egg sacs were collected from their habitats in different localities of 15 counties in the province. The following species have been recognized: Lathrodectus tredecimgottatus (62%), L. dahli (32%), L. geometricus (5%) and L. pallidus (1%). Here is the first report on the occurrence of males of L. pallidus as well as both sexes of L. trdecimgottatus and L. geometricus in the country. The sex ratio among collected specimens was 88% and 12% female and male, respectively. Summer provides the most suitable and favorable climatic condition for the activities of these spiders. However 65% of spiders were collected in this season. Among different cit¬ies, Mashad had (60%) the most reported cases in the study area. Foot was more injured than other parts. 96.5% of pa¬tients exhib¬ited localized pain from which only 2% had no pain in the bitten part and 87% had a generalized pain in whole body

The Occurrence of Red-Back Spider Latrodectus hasselti (Araneae: Theridiidae) in Bandar Abbas, Southern Port of Iran

Background:  Due to importance and fatal affect of Red-back spiders, Latrodectus hasselti, a faunistic survey for presence of this spider in Bandar Abbas has been conducted. This animal is considerably the most medically importance spiders all over the world. Methods: Live adult spider specimens were collected from Bandar Abbas town using hand catch conventional method and transferred to the laboratory throughout the summer of 2008. They  were identified based on mor­phological characteristics and taxonomic keys and confirmed by some external experts. Results: Results showed the occurrence of the red-back spider, L. hasselti from Bandar Abbas, southern port of Iran. Two female specimens were found. The spider had specific morphological characters  including black color with an obvious orange to red longitudinal strip on its upper parts of  abdomen. Conclusion: Although the specimens were collected from south of the country, however since the region is an important harbor and port and goods come form different parts of world we assume the possibility of arrival  from its origin and native breeding sites of the world. Therefore further investigation is needed to clarify the presence of this species in different parts of Iran.

Faunistic Study and Biodiversity of Scorpions in Qeshm Island (Persian Gulf)

 Background: Scorpions are known as the most widespread poisonous creatures that cause casualties and death to human. They are distributed in tropical and subtropical areas. Among the sixteen Iranian Island in the Persian Gulf, Qeshm Island is the biggest and is located in the focus of the important internal and international commercial marinelines. Furthermore, thousands of tourists also visit the Island every year for its natural beauties and the siteseeings. The present research study was carried out during 1998-99 throughout Qeshm Island in order to know the species of scorpions, their abundance, the distribution and control strategy in order to reduce the scorpion stings and to safeguard the visitors as well as the local population. Methods: Collections were made randomly during the night. Samples were searched by black light and then collected by forceps. A total of 102 scorpions were captured. Results: The scorpions were identified as Buthotus jayakari numbered 42 specimens (41.17%) and B. leptochelys numbering only 7 specimens (6.86%) belonging to the family Buthidae. Androctonus crassicauda was collected in the most parts of the Island and considered as the dominant species. The sex ratio was 1:1.53 in favor of females. B. lep­tochelys was rare species and by far restricted in its distribution. Conclusion: Considering the high population of A. crassicauda and its wide distribution, it is regarded to be re­sponsible for the majority of scorpion stings in Qeshm Island

Laboratory colonization of Lucilia sericata Meigen (Diptera: Caliphoridae) strain from Hashtgerd, Iran

Background & objectives: The treatment of wounds with live green bottle fly larvae is receiving considerableattention in many countries. Laboratory rearing of Lucilia sericata is crucially important for the treatment ofwounds.Study design: The study was carried out for mass rearing of green bottle flies from April to November 2010.Hand catch and net trap baited with beef and cattle liver were used to collect adult flies from the field. Thecollected samples were placed in appropriately labeled tubes and sent to the laboratory. Adult stage flies rearedin the insectary were used for species identification using specific keys.Results: A total of 89 flies (55 females and 34 males) were collected from Hashtgerd area. In the first generation,299 flies were produced in the laboratory including 105 (35.12%) males, and 194 (64.88%) females. The female/male sex ratio was 1.61 for parents, whereas it was 1.84, 1.30 for F1 and F2 generations respectively. In total,432 flies were reared in F3 generation including 173 (40.04%) males, and 259 (59.96%) females, and the sexratio was 1.49.Conclusion: Setting up the mass rearing of sheep blowfly at the School of Public Health, Tehran University ofMedical Sciences is an important step in producing candidate flies for the treatment of myiasis by maggottherapy in future