High-power laser-induced optical aberrations on beam director mirrors

We present a full-scale numerical study of thermally induced optical aberrations on the primary mirror of a beam director telescope. In particular, we investigate high-power laser-induced deformations, resulting monochromatic aberrations, and their effects on imaging and laser focusing performance of primary telescope mirrors in shared aperture beam director systems. As a practical example, we consider a system based on 6 × 4 kW single-mode high-power laser sources and a primary mirror having a 500 mm circular clear aperture. A detailed comparison of the monochromatic aberrations and their implications on the optical performance is provided for borosilicate and Zerodur® substrates having identical reflective coatings for potential laser beam director applications. Our analyses show that high-power lasers can be efficiently directed with negligible imaging degradation using athermal substrates (i.e., Zerodur®) with high reflective coatings (>99.9 %) for primary mirrors. On the other hand, substrates with a relatively higher coefficient of thermal expansion (i.e., borosilicate) can only be used effectively under a strictly controlled ambient temperature

Thermal and mechanical behavior of graphene loaded synthetic graphite/polyphenylene sulfide (PPS) composites

Thermoplastics when they become thermally conductive, have a great potential to be used in thermal management applications due to their low cost, lightweight, and flexibility. Here, synthetic graphite and graphene are used as thermally conductive fillers to fabricate Polyphenylene Sulfide-(PPS) based composite materials with high thermal conductivity. Graphene and graphite added PPS composites were manufactured by using a twin-screw extruder and injection molding machine. Physical, thermal, mechanical, and morphological properties of the composites were investigated by several characterization methods including thermogravimetric analysis, differential scanning calorimetry. thermomechanical analysis, scanning electron microscopy. thermal diffusivity measurement, and tensile and flexural tests, The in-plane and through-plane thermal conductivity coefficient of graphene (5 wt. %) loaded synthetic graphite (40 wt. %)/PPS composites are greatly improved to 26.45 and 5.02 W/mK, respectively compared to that of neat PPS. The outstanding in-plane thermal conductivity of graphene loaded graphite/PPS composites is attributed to the formation of an effective thermal conductive pathway due to the alignment of the layered structure of graphene and graphite fillers in the flow direction.scientific and technological research council of Turkey [117M088]The authors are grateful for the funding from the scientific and technological research council of Turkey (Project no: 117M088)

The prevalence of mixed genotype infections in Turkish patients with hepatitis c: a multicentered assessment

AKTAS, OSMAN/0000-0002-7762-4108; Karsligil, Tekin/0000-0001-7672-3625; cekin, yesim/0000-0003-4393-5618; Sayiner, Ayca/0000-0001-6750-2353; Altindis, Mustafa/0000-0003-0411-9669WOS: 000463988900008PubMed: 30969089Background: HCV virus infections are one of the major health problems in the world that can cause cirrhosis and liver cancer at a higher rate than other hepatitis data. The aim of this study was to determine the prevalence of mixed infections with different HCV genotypes in Turkey and also to evaluate the current HCV genot pe and subtype distributions by a multicentered assessment. Methods: The HCV genotype data of 17,578 hepatitis C patients collected from 23 centers from different geographic regions covering all Turkey were collected. The data included information about the HCV genotypes in the last 10 years (bail een 2007 and 2016), demographic properties of the patients and the methods/systems used to determine the genotypes. Results: Two hundred twenty-eight of the patients (1.3%) had mixed genotype. The most common mixed genotype combination was 1b + 4 (0.83%) followed by 1a + 1b (0.26%). Genotype distribution varies according to geographical regions. However, genotype 1 (82.92%) was the most common genotype in all regions and all years. This was followed by genotype 3 (7.07%) and genotype 4 (5.43%). A variety of methods were used by the centers including sequencing, pyrosequencing, real-time PCR, in-house RFLP, reverse hybridization (LIPA), and hybridization. Conclusions: Infection with mixed HCV genotypes in Turkey is uncommon. Genotype distribution varies according to geographic regions; the most common genotype 1 is encountered all oN er the country, while genotypes 3 and 4 are only in some of the centers. Since there is limited information about mixed HCV infection, further investigations are needed to determine the clinical importance of mixed HCV infection