High Performance Molybdenum Disulfide Amorphous Silicon Heterojunction Photodetector

One important use of layered semiconductors such as molybdenum disulfide (MoS2) could be in making novel heterojunction devices leading to functionalities unachievable using conventional semiconductors. Here we demonstrate an ultrafast metal-semiconductor-metal heterojunction photodetector, made of MoS2 and amorphous silicon (a-Si), with rise and fall times of about 0.3 ms. This is more than an order of magnitude improvement over response times of conventional a-Si (~5 ms) and best reported MoS2 devices (~50 ms). The van-der-waals heterojunction presented here yields a high photoresponsivity of 210 mA/W at green light-the wavelength used in commercial imaging systems. This responsivity is 4X larger than that of the best MoS2 devices, and 2X larger than that of commercial a-Si devices. The 10X improvement in speed with high photoresponsivity provides a potential solution to a decades-long problem for thin film imagers and could find applications in large area electronics such as biomedical imaging and x-ray fluoroscopy

Head circumference in Iranian infants

Background: Head circumference (HC) measurement is an important parameter in the diagnosis of neurological and developmental disorders as well as dysmorphic syndromes. Recognition of different disorders requires an understanding of the normal variation of the HC size, especially during infancy which is a period of rapid brain growth. Regarding the differences in the international and interracial standard charts of anthropometric indices, local and generational diversities, changes in the ethnic mix of the population and socioeconomic factors, periodic re-evaluations need to be done on the size of HC. This study aimed to represent a local HC standard for an Iranian infant population in comparison with the charts of the American National Center of Health Statistics (NCHS) approved by the World Health Organization (WHO). Methods: About 1003 neonates were randomly enrolled in this cross-sectional study. They were ageing from 3 days to 24 months and were apparently in normal condition. The HC size of these infants was measured and recorded. Tables and graphs were diagramed by Excel Microsoft Office 2007 software and two-tailed Student's t-test was used for statistical analysis of data. Results: According to the findings of this study, the mean of the HC size in male infants was larger than the female ones. Based on a visual comparison, the curves followed a pattern similar to that of the NCHS's. Overall, our subjects in both genders were found to have a smaller HC size at birth compared to the NCHS charts. However, infants of other ages had a larger HC size compared to that of the NCHS's. Conclusion: With respect to the international and interracial differences in the HC size, it is recommended that local anthropometric indices be constructed and used clinically across the world. In addition, extensive and longitudinally designed studies are required in this regard

Inclusion of an Introduction to Infrastructure Course in a Civil and Environmental Engineering Curriculum

Civil infrastructure refers to the built environment (sometimes referred to as public works) and consists of roads, bridges, buildings, dams, levees, drinking water treatment facilities, wastewater treatment facilities, power generation and transmission facilities, communications, solid waste facilities, hazardous waste facilities, and other sectors. Although there is a need to train engineers who have a holistic view of infrastructure, there is evidence that civil and environmental engineering (CEE) programs have not fully addressed this increasingly recognized need. One effective approach to address this educational gap is to incorporate a course related to infrastructure into the curriculum for first-year or second-year civil and environmental engineering students. Therefore, this study assesses the current status of teaching such courses in the United States and identifies the incentives for, and the barriers against, incorporating an introduction to infrastructure course into schools’ current CEE curricula. Two distinct activities enabled these objectives. First, a questionnaire was distributed to CEE programs across the United States, to which 33 responses were received. The results indicated that although the majority of participants believe that offering such a course will benefit students by increasing the breadth of the curriculum and by providing a holistic view of CEE, barriers such as the maximum allowable credits for graduation, the lack of motivation within a department—either because such a course did not have a champion or because the department had no plans to revise their curriculum—and a lack of expertise among faculty members inhibited inclusion of the course in curricula. Second, three case studies demonstrating successful inclusion of an introduction to infrastructure course into the CEE curriculum were evaluated. Cases were collected from Marquette University, University of Wisconsin-Platteville, and West Point CEE programs, and it was found that the key to success in including such a course is a motivated team of faculty members who are committed to educating students about different aspects of infrastructure. The results of the study can be used as a road map to help universities successfully incorporate an introduction to infrastructure course in their CEE programs

Life history traits and gonad histology of an endemic cyprinid fish, Mond spotted barb, Capoeta mandica from Southern Iran

The life history traits and gonad development of an endemic cyprinid fish, the spotted barb, Capoeta mandica (Bianco & Banarescu 1982), from southern Iran was investigated by regular monthly collections from February 2006 through January 2007 and on the basis of microscopic and macroscopic analyses. No information on the spawning characteristics of the fish are available to date. A total of 335 specimens were captured using electrofishing including 253 males and 102 females, resulting in 2.5:1 (male: female) sex ratio, which is significantly different from the expected ratio. The commonly known five standard maturation stages were determined based on the size, shape and weight of the gonads, degree of occupation of the body cavity, presence or absence of ripe oocytes, or milt, diameter of the oocytes in the ovary, and histological observations. These stages were correlated to the reproductive indices. The ovum diameters ranged from 0.04 to 1.31 mm, with the highest mean value in May. The condition factor of male and female specimens was the highest in April. The female GSI increased from March to May, peaking in the middle of spring and decreased significantly in June. Based on the gonad maturation stages, gonadosomatic index (GSI), modified GSI, mean egg diameter, condition factor (K) and Dobriyal index (DI), it was concluded that the spotted barb spawns during May and June. The provided data, contribute baseline data towards management ecology and conservation of this endemic fish species

Hemiculter leucisculus (Basilewsky, 1855) and Alburnus caeruleus Heckel, 1843: New data on their distributions in Iran

This paper provides information on the geographic distributions of two cyprinid species: Hemiculter leucisculus (Basilewsky, 1855) and Alburnus caeruleus Heckel, 1843, in the world and the entire drainage systems in Iran. The new distribution records were taken from Maroon River (Jarrahi River system) and Chardaval River (Karkheh river system), both in Tigris River basin showing wide and narrow distribution ranges of these two cyprinid fishes, respectively. The main introduction sites and distribution range of H. leucisculus is the southern parts of the Caspian Sea basin in Iran from where it has probably been translocated to other Iranian basins along with exotic Chinese carps. Although A. caeruleus is native to Tigris River basin, it had been already recorded only from Gamasiab and Doab rivers in 2009 in Karkheh River system (Tigris) and thus the present study extends its distribution range. In case of alien species, human-mediated fish introductions may increase faunal similarity among primary drainages due to a strong tendency for taxonomic homogenization caused primarily by the widespread introduction of cyprinid fishes. Fish faunal homogenization might be highest in drainages (e.g. Caspian Sea and Tigris basins) subjected to the greatest degree of disturbance associated with human settlement, infrastructure and change in land use. The provided data might be used in conservation program of freshwater fishes of Iran

Simultaneous determination of irinotecan hydrochloride and its related compounds by high performance liquid chromatography using ultraviolet detection

A new simple, precise and accurate high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of irinotecan (CPT-11) and two related compounds viz., 7-ethyl-10 hydroxycamptothecin (SN-38) and camptothecin (CPT) in pharmaceutical dosage forms. Chromatography was accomplished using a reversed-phase C18 column and ultraviolet (UV)detection and an isocratic mobile phase consisting of 3 % v/v triethylammonium acetate buffer (pH 3) and acetonitrile (70:30 v/v). The linear range of quantitation for all the compounds was 0.1-10 μg/mL. The limit of quantitation for all the compounds ranged between 0.01-0.05 μg/mL. The method has the requisite accuracy, selectivity, sensitivity and precision to assay of CPT-11 and related compounds in pharmaceutical dosage forms and bulk API

Family medicine in Iran: facing the health system challenges

OBJECTIVE: This study aimed to understand the perspectives of policy makers and decision makers of Iran's health system about the implementation of family medicine in Iran urban areas. MATERIALS/PATIENTS & METHODS: This study is a qualitative study with framework analysis. Purposive semi-structured interviews were conducted with Policy and decision makers in the five main organizations of Iran health care system. The codes were extracted using inductive and deductive methods. RESULTS: According to 27 semi-structured interviews were conducted with Policy and decision makers, three main themes and 8 subthemes extracted, including: The development of referral system, better access to health care and the management of chronic diseases. CONCLUSION: Family medicine is a viable means for a series of crucial reforms in the face of the current challenges of health system. Implementation of family medicine can strengthen the PHC model in Iran urban areas. Attempting to create a general consensus among various stakeholders is essential for effective implementation of the project. BACKGROUND: In response to the current fragmented context of health systems, it is essential to support the revitalization of primary health care in order to provide a stronger sense of direction and integrity. Around the world, family medicine recognized as a core discipline for strengthening primary health care setting

A case of May-Thurner syndrome

May-Thurner syndrome is a condition that results from narrowing of the left common iliac vein lumen due to pressure from the right common iliac artery as it crosses anterior to it. We describe a very rare case in which a previously asymptomatic patient presented with May-Thurner syndrome

The fluctuations of physicochemical factors and phytoplankton populations of Urmia Lake, Iran

Urmia Lake is one of the two large hypersaline lakes in the world which have Artemia. It is located in northwest of Iran. Due to a decrease in water inflow and volume, the salinity of Urmia Lake has reached to more than 300 g.l-1 since 2001. The increased salinity has greatly influenced biological aspects of the lake, and caused the lake undergoes at critical conduction. The aim of the present study was to investigate the distribution fluctuations of phytoplanktons and selected physicochemical factors in relation to Artemia distribution in Urmia Lake during 8 months. Statistical analysis of mean values of ion concentrations and phytoplankton abundance indicated significant differences among sampling months. The minimum and maximum values for the selected factors were, as Cl- 176.2-201.3 g.l-1 , CO2 95-175mg.l-1 , dissolved oxygen (DO) 0.1-2.8 mg.l-1 , HCO3 - 144-496 mg.l-1 , PO42+ 104-875 mg.l-1, NO3- 330-4104 mg.l-1, NO2- 4-21.5 mg.l-1, SO42- 10490-29840 mg.l-1, Ca2+ 561-1606 mg.l-1, Mg2+ 3649-14587 mg.l-1 while water hardness was 21000- 62000 mg.l-1. Fourteen phytoplankton genera included Bacillariophyceae (10 genera),Chlorophyceae (2 genera) and Cyanophyceae (2 genera) were identified during sampling period. The smallest average density of phytoplankton 97249 L-1 was observed in December 2005 and the greatest average density 481983 L-1 in August 2005. Dunaliella sp. composed 92.1% of the lake's phytoplankton. Statistical analysis of phytoplanktons fluctuations showed a significant difference among different months (p< 0.05)