256 research outputs found
Photocatalytic Activity of Quantum Dots
In recent years, nanoscale semiconductors have attracted great interest due to their unique structural, optical and electronic properties, which arise due to their large surface-to-volume ratio and quantum confinement effect. Quantum dots (QDs) as zero-dimensional semiconductor nanomaterials, which are confined to a size of 2–8 nm in three dimensions, are defined as particles with physical dimensions smaller than the exciton Bohr radius. One of the attractive research fields in recent years is the synthesis of various sizes and shapes of semiconductor material nanoparticles as doped with different dopants. The aim of this chapter is to focus on the photocatalytic activity of QDs as new, green and efficient nanophotocatalysts
Studija o rekonfiguraciji mreže distributivnog sustava korištenjem adaptivnog modificiranog \u27firefly\u27 algoritma
This paper suggests a new method based on the probabilistic load flow and Adaptive Modified Firefly Algorithm (AMFA) in order to evaluate the optimal management of the Distribution Feeder Reconfiguration (DFR) operation problems by considering a few Wind Turbines (WTs) in system and performance satisfaction of the proposed method is examined on the IEEE 32-bus standard test system. The significant objective functions in this paper includes: 1) Minimizing the total cost of active power losses in the network, 2) voltage profile improvement, 3) decreasing the present network total costs such as power production cost by the main network and distributed generations. Furthermore, a new stochastic solution based on Point Estimate Method (PEM) is proposed to effectively deal with the uncertainty related to the important random parameters such as active and reactive loads in addition to the wind speed variations. Thus, the suggested probabilistic framework must be considered in order to solve the reconfiguration problem with regard to uncertainties which caused by the wind turbines.U radu se predlaže novi pristup za optimalno rekonfiguriranje napojnih vodova u elektroenergetskim distributivnim sustavima temeljen na adaptivnom modificiranom \u27firefly\u27 algoritmu. Primjena obuhvaća problem s par vjetroagregata u sustavu, a učinkovitost je provjerena korištenjem standardnog testa za IEEE 32 sabirnicu. Značajniji razmatrani kriteriji su: 1) smanjenje ukupne cijene gubitaka aktivne snage u mreži, 2) poboljšanje profila napona, 3) smanjenje ukupne cijene postojeće mreže kroz smanjenje cijene proizvodnje snage glavne mreže i distribuiranih izvora. Nadalje, novo stohastičko rješenje temeljeno na \u27Point estimate\u27 metodi predloženo je za učinkovito savladavanje nesigurnosti povezanom s važnim stohastičkim parametrima kao što su aktivni i reaktivni teret u dodatku s varijacijama brzine vjetra. Predloženi stohastički okvir mora biti uzet u obzir prilikom rješavanja problema rekonfiguracije s obzirom na neodređenosti koje proizlaze iz vjetroagregata
The spinal mouse validity and reliability in measurement of thoracic and lumbar vertebral curvatures
زمینه و هدف: تحقیق حاضر برای بررسی میزان اعتبار این دستگاه در اندازه گیری زوایای کایفوز سینه ای و لوردوز کمری در مقایسه با عکس رادیوگرافی و همچنین تکرارپذیری درون و بین آزمونگر آن بود. روش بررسی: برای بررسی میزان اعتبار دستگاه اسپاینال موس در اندازه گیری زوایای کایفوز سینه ای و لوردوز کمری، تعداد 20 نفر از افراد مراجعه کننده به یکی از مراکز تصویربرداری پزشکی شهر تهران که قرار بود بر اساس تجویز پزشک متخص عکس رادیوگرافی کامل ستون فقرات از نمای نیمرخ تهیه کنند انتخاب شدند. معیارهای ورود و خروج آن ها بررسی شد و اندازه گیری ها با دو روش در یک روز و بدون فاصله انجام گردید، در نهایت زاویه ها در عکس رادیوگرافی به روش کوب و در اسپاینال موس با توجه به نتایج ثبت شده بر روی نمایشگر، با روش آماری همبستگی پیرسون مقایسه شدند. همچنین برای بررسی تکرارپذیری درون آزمونگر 30 نفر از دانشجویان پسر دانشگاه تهران به صورت تصادفی وارد تحقیق شدند تا در سه نوبت در سه روز متوالی اندازه گیری ها تکرار شود، همچنین برای تکرارپذیری بین آزمونگر 15 نفر از دانشجویان پسر دانشگاه تهران در دو نوبت با فاصله زمانی یک دقیقه توسط دو آزمونگر اندازه گیری شدند. در نهایت نتایج با روش همبستگی درونی بررسی قرار گرفت. یافته ها: دستگاه اسپاینال موس از اعتبارپذیری مطلوبی در مقایسه با رادیوگرافی در اندازه گیری زاویه کایفوز سینه ای (0/001=P، 0/81=r) و لوردوز کمری (0/001=P، 0/86=r) برخوردار است. همچنین تکرارپذیری درون و بین آزمونگر دستگاه اسپاینال موس نیز در اندازه گیری زوایای کایفوز سینه ای به ترتیب (0/92=ICC، 0/79ICC=) و لوردوز کمری (0/89ICC=، 0/87ICC=) مطلوب بود. نتیجه گیری: استفاده از دستگاه اسپاینال موس به عنوان یک وسیله غیرتهاجمی ایمن و جایگزینی مناسب برای عکس رادیوگرافی در اندازه گیری زوایای کایفوز سینه ای و لوردوز کمری توصیه می شود
Study of density, distribution and yield on benthic fauna and brown trout (Salmo trutta fario) feeding in Laar reservoirs
Lar lake, with the international UTM specification of 39S 579680 3976567
& 39S 589930 3976184 is Situated in Lar national Park with an aerial distance of 55 Km of
Tehran along Haraz road.
The present research is carried out as part of a comprehensives Plan for assessment of
bioresearches of Lar lake & the rivers flowing into it. This research includes examination of
there benthic Samplings performed in Lar lake and each of the related rivers including
Delichaee, Ab-e-sefid , Alarm & Lar (Kamardasht).Tubifex and Chironomus genus were
found to have the highest frequencies of occurrence in the lake with %77.117 & %21.823
respectively followed by Chironomidae and Simulidae from the Diptera order which
accounted for %72.328 and %13.812 occurrences in four rivers examined in the Study. The
benthic biomass at various examined Sites and the average wet weight of the benthic biomass
in station No one in the lake Was 17.397g and the figure for the examined site in Alarm was
20.242 g which were the highest level among Other examination stations the index for the
abundance of species in Alarm river was greater than the rest of the examined rivers with
12.57. A sum of 354 Pieces of brown trouts was caught in the course of sampling which were
closely investigated in terms of their digestive tract Content. It was identified that Daphniidae
and Chironomus constituted the bulk of eaten items from the lake with %17.985 and %63.973
respectively. Meanwhile, Chironomidae and Simuladae were the most frequently eanten
benthos by the fish with %81.47 and %7.93 respectively.The index for the relative length of
gut was recorded at 0.49± 0.08 which is well indicative of the carnivorous diet of the fish.The
index for the feeding intensity amounted to 138 83 showing that the one year old fish were
of more feeding intensity.The coefficient of condition (K) was estimated at 1.02 0.142 for
all the caught fish. The average wet weight of the benthos was 10.348 g per square meter
which if extended to 700ha surface area of the lake, the total macrobenthic production in the
lake would amount to 72730Kg of wet weight or 6510 Kg of dry weight. Since the Secondary
Production of macrobenthos have always been double that of their biomass, it is reasonable to
assume that the Secondary Production of macrobenthos amount to 145640 Kg by their wet
weight and Since the energy transfer in the food chain of the lake from benthos to fish is 10
percent, the fish production Capacity Coming from benthic resources of the lake (Lar) would be 14.5 MT, half of which (7000-8000MT) could annually be harvested. Further more, the actual fish Production Capacity might exceed the projected level Since Daphnia, Rotifers and Ostracoda which belong to Zooplanktons, play a part in the natural diet of trout. Meanwhile, rivers Play a major role in fish nutrition and the annual fish production in Delichaee river is about 4481.8Kg while the figures for Ab-e-sefid, Alerm and Lar rivers are 2370.7 4848.7 and 2586.2 Kg respectively, that further increase fish Production in the area and every year half of these resources can be exploitable from the river & the lake.Nevertheless, due to ecological & biological importance of rivers and the probability of environmental Pollution, devastation of natural fish habitats & their nursery grounds, Sport fishing is not recommended at all
Mushroom Poisoning in the Northeast of Iran; a Retrospective 6-Year Epidemiologic Study
Introduction: Toxic mushrooms are distributed across the globe with over 5000 species. Among them, 100 species are responsible for most of the cases of mushroom poisoning. This study aimed to evaluate the epidemiologic pattern of mushroom poisoning among patients referred to the main toxicology center of Mashhad province located in North-east of Iran.Method: This cross-sectional study was conducted on patients with final diagnosis of mushroom poisoning referred to the toxicology center of Mashhad, Iran, from February 2005 to 2011. Patients’ demographic characteristics, clinical presentations, laboratory findings, outcomes, and therapeutic measures were collected using a predesigned checklist and searching patient’s profile. Results: 32 cases with the mean age of 24.6 ± 16.7 years were presented to the toxicology center following mushroom poisoning (59% female). Mushroom poisoning accounted for 0.1% of all admitted cases. The mean time elapsed from consumption to referral to poisoning department was 61.9 ± 49.4 hours. 19 (59%) cases were discharged with complete recovery, 7 (22%) expired, and 6 (19%) cases left hospital against medical advice. Mushroom poisoning mortality accounted for 1.5% of deceased cases in the studied center. There was significant relationship between mortality rate and higher values of INR (p = 0.035), PT (p = 0.011) and PTT (p = 0.003). Likewise, there was significant relationship between the need for mechanical ventilation and higher values of INR (p = 0.035), PT (p = 0.006) and PTT (p = 0.014). The relationships between the need for ICU admission, mechanical ventilation, and mortality rate with the rise of hepatic transaminases and serum bilirubin were not significant.Conclusion: Based on the findings, the prevalence of mushroom poisoning among patients referred to Mashhad toxicology center was very low (0.1%), but with a high mortality rate of 22%. Nausea and vomiting were the most common early symptoms of intoxication and higher values of coagulation profile were correlated with poor outcome
Influence of the Lamination Material and Rotor Pole Geometry on the Performance of Wound Field Synchronous Machines
This paper examines the influence of the lamination
material and rotor pole geometry on the steady-state performance
of a wound field synchronous machine operated in the generating
mode. The investigations are carried out through 2D finite element
analyses using a commercial software package. Non-Oriented
silicon-iron alloys of various grades are selected to recognize the
impact of their magnetic properties on the machine performance.
Different methods for the extrapolation of BH curves from low medium field levels to saturation are reviewed and compared.
The effect of using different materials on both the rotor and the
stator core is assessed in terms of variation of the air gap power,
the torque ripple and the core losses. The performance of a new
machine featuring a higher-grade lamination material and a
refined rotor pole geometry are compared at constant air gap
power with those of the reference machine.
The results show that, depending on the adopted strategy, it is
possible to almost halve the torque ripple and slightly decrease the
mass of the rotor core
Effects of Endurance and Resistance Training on Calcitonin Gene-Related Peptide and Acetylcholine Receptor at Slow and Fast Twitch Skeletal Muscles and Sciatic Nerve in Male Wistar Rats
The aim of this study was to investigate effects of endurance and resistance training (ET and RT) on CGRP and AChRs at slow and fast twitch muscles and sciatic nerve in rats. Twenty-five male rats were randomly assigned into three groups including sedentary (SED), endurance training (ET), and resistance training (RT). Animals of ET exercised for 12 weeks, five times/week, and 60 min/day at 30 m/min. Animals of RT were housed in metal cage with 2 m high wire-mesh tower, with water bottles set at the top. 48 h after the last session of training protocol, animals were anaesthetized. The right sciatic nerves were removed; then, Soleus (SOL) and Tibialis anterior (TA) muscles were excised and immediately snap frozen in liquid nitrogen. All frozen tissues were stored at −80°C. Results showed that, after both ET and RT, CGRP content as well as AChR content of SOL and TA muscles significantly increased. But there was no significant difference among groups at sciatic nerve' CGRP content. In conclusion, data demonstrate that ET and RT lead to changes of CGRP and AChR content of ST and FT muscles. The changes indicate to the importance of neuromuscular activity
Attitudes Towards Accreditation and Quality Improvement Activities Among Hospital Employees in Iran:A Quantitative Study
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