An exploratory study of co-authorships among Iranian scientists in experimental sciences

This paper investigates the factors that made international co-authorship between scientists in Iran and elsewhere possible. A questionnaire was sent out to Iranian scientists in fields of physics, chemistry, and biology who had co-authored an internationally published journal article during 2003. The main foreign co-author in each of the articles was identified and questions regarding this co-author and the collaborative event were asked. The results show that not all co-authored articles were the results of collaborative projects. Also, the main collaborative motives behind the co-authorships were identified and described. Among these, we could mention sharing laboratory devices, accessing knowledge, and increase the efficiency of the study at hand. It is clear that emigrated Iranian scientists play an important role as collaborators and probably also as links to the international scientific community as a whole. Cultural factors mix with scientific and work related one

Determination of Genetic Relatedness among Selected Rice Cultivars Using Microsatellite Markers for Cultivars Improvement through Marker Assisted Breeding

Rice is grown in diverse environmental conditions. In this study, genetic variation among thirteen Iranian and thirteen Malaysian rice cultivars was determined using Microsatellite markers. Microsatellites are polymerase chain reaction (PCR) based and dbla ceelcuoobeoy xoed (DNA) markers which are abundant, co-dominant and widely used in various organisms. This study consisted of two parts, the first part was DNA extraction, which consisted of comparing between four different DNA extraction methods, namely the Dellaporta and CTAB as conventional methods also, Promega and Axyprep as commercial protocols kits. Comparison was also made on the effect of different leaf age as well as leaf position on different quality and yield of DNA obtained. The results of the study showed significant difference (P<0.05) between different extraction methods in relation to optical density OD 260/280 nm and DNA yield from each method. The Dellaporta method (OD260/280=2±0.07nm and DNA yield 2073±196 ng) gave the best results. The positions of different leafs (from top to bottom leaf number 4 to 1) and the ages of leafs (2, 4, 6 and 8 weeks) were also monitored for optimum DNA extraction. The results of the Duncan test showed that there was no significant difference (P>0.05) between leaf positions for 2 to 4 weeks old leaf. However, the age of leaves in young and fresh stages of tissue showed significant difference (P<0.05) in ratio of OD260/280 2±0.03 and DNA yield (1373±70 ng). The results (based on method of extraction, leaf age and position) were used for subsequent DNA extraction of the 26 rice cultivars. The second part consisted of molecular work using twenty one microsatellite primer pairs which were selected from the Gene Bank. The estimation of genetic diversity among two rice groups (Iranian and Malaysian cultivars) were done with the assistance of two softwares UVIdoc (ver.98) and POPGENE (ver.1.31). A total of 21 loci (75 alleles) were observed, of which 20 loci (95.24 %) were polymorphic, except RM338. Microsatellite loci RM1 and RM271 showed the highest polymorphism (between 94 to 136 bp in size). The Polymorphism Information Content (PIC) value was (0.578±0.170). The dendogram constructed based on genetic distance values (UPGMA) grouped the cultivars into five clusters. All of the Iranian rice cultivars were placed in cluster I and III while Malaysian rice cultivars were in clusters IV and V. However cluster II consisted of both Iranian and Malaysian rice cultivars. The results of genetic diversity among selected cultivars in this study can be used for screening of the high grain quality rice accession for backcrossing and breeding programs

Preparation and characterization of new hybrid organic/inorganic systems derived from calcium (aminoalkyl)-phosphonates and -phosphonocarboxylates

We have studied the phenomenon of calcium complexation by lab synthesized amphiphilic (α-aminoalkyl)-phosphonocarboxylic or -phosphonic acids. The electrical conductivity of aqueous solutions of sodium salts of all these acids was measured versus the volume of a calcium salt solution added. It appeared that calcium complexes are formed in a Ca/P atomic ratio close to 1. Calcium phosphonocarboxylates and calcium phosphonates were also precipitated by mixing aqueous solutions of disodium salts of phosphorus amphiphiles and calcium nitrate solutions. Before chemical analysis, these complexes were calcined to remove the organic part. In the mineralized products, calcium and phosphate were assayed: the Ca/P atomic ratio was equal to 1. X-ray diffraction and IR spectroscopy showed that they are made entirely of β pyrophosphate (Ca2P2O7), a result in agreement with previous chemical analysis. The chemical formula of the starting calcium complexes could be written as CaL·2H2O (L= ligand). The SEM micrographs of these complexes show plate-like structures. XRD patterns are characteristic of layered structures. These facts suggest that calcium complexes are composed of alternating bimolecular layers of calcium alkylphosphonocarboxylates or calcium alkylphosphonates, the chains being tilted and partially interdigitated

Predicting scour depth around non-uniformly spaced pile groups

Pile scour may cause instability to the structures they support. Ensuring a safe and economically sound design is essential for the wider community. Although much laboratory research has been carried out on scour at pile groups, there are still significant gaps in prediction formulae. This study has been conducted to develop a formula for scour at pile arrangements of non-uniform spacing. The study was based on a laboratory experiment found in the literature. Previous empirical formulae for uniformly spaced pile groups were first used to gauge an idea of their performance. The formula that predicted the scour depth more accurately was then modified. The approach of Ghaemi et al. (2013) outperformed the other trialled empirical formulas. Using this formula, a correction factor was suggested to increase the prediction accuracy. The gap to diameter ratio was also corrected to include the non-uniformity of spacing in two directions

Forced boiling of nanofluids, effects of contact angle and surface wettability

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Nanofluids are the suspension of ultra fine particles in a conventional base fluid which tremendously changes the heat transfer characteristics of the original fluid. In this paper the boiling characteristics of different nanofluids was studied numerically using a CFD approach. Dispersions of Al2O3, SiO2, and ZrO2 nanoparticles in water at different concentrations (0.1, 0.01 and 0.001% by volume) have been used. Effects of some noticeable parameters such as nanoparticle concentration and temperature profile on the critical heat flux (CHF) have been investigated. The results of CFD simulation based on two-phase models were compared with experimental data. Boiling curves and critical heat flux were measured for the base fluid and the nanofluids. Based on the simulation results, it was concluded that the using of the Zirconium oxide (0.001%) led to modest (up to 31%) increase in the CHF. The minimum enhancement belongs to the aluminum oxide (0.1%) which increases the critical heat flux up to 11%. According to the experimental results, despite of expectation, addition of the nanoparticles causes decreasing the boiling heat transfer coefficient. This reduction is related to the changing of the surface characteristic causing by depositing the nanoparticles. In the Al2O3/water and SiO2/water nanofluids, the surface contact angle increases with increase in the nanoparticle volume fraction, so the CHF decreases

Coherent Umklapp Scattering of Light from Disordered Photonic Crystals

A theoretical study of the coherent light scattering from disordered photonic crystal is presented. In addition to the conventional enhancement of the reflected light intensity into the backscattering direction, the so called coherent backscattering (CBS), the periodic modulation of the dielectric function in photonic crystals gives rise to a qualitatively new effect: enhancement of the reflected light intensity in directions different from the backscattering direction. These additional coherent scattering processes, dubbed here {\em umklapp scattering} (CUS), result in peaks, which are most pronounced when the incident light beam enters the sample at an angle close to the the Bragg angle. Assuming that the dielectric function modulation is weak, we study the shape of the CUS peaks for different relative lengths of the modulation-induced Bragg attenuation compared to disorder-induced mean free path. We show that when the Bragg length increases, then the CBS peak assumes its conventional shape, whereas the CUS peak rapidly diminishes in amplitude. We also study the suppression of the CUS peak upon the departure of the incident beam from Bragg resonance: we found that the diminishing of the CUS intensity is accompanied by substantial broadening. In addition, the peak becomes asymmetric.Comment: LaTeX, 8 two-column pages, 6 figures include