The interaction between the Moon and the solar wind

We study the interaction between the Moon and the solar wind using a three-dimensional hybrid plasma solver. The proton fluxes and electromagnetical fields are presented for typical solar wind conditions with different magnetic field directions. We find two different wake structures for an interplanetary magnetic field that is perpendicular to the solar wind flow, and for one that is parallell to the flow. The wake for intermediate magnetic field directions will be a mix of these two extreme conditions. Several features are consistent with a fluid interaction, e.g., the presence of a rarefaction cone, and an increased magnetic field in the wake. There are however several kinetic features of the interaction. We find kinks in the magnetic field at the wake boundary. There are also density and magnetic field variations in the far wake, maybe from an ion beam instability related to the wake refill. The results are compared to observations by the WIND spacecraft during a wake crossing. The model magnetic field and ion velocities are in agreement with the measurements. The density and the electron temperature in the central wake are not as well captured by the model, probably from the lack of electron physics in the hybrid model.Comment: Accepted for publication in Earth, Planets and Spac

Emergence of Bulk CsCl Structure in (CsCl)nCs+ Cluster Ions

The emergence of CsCl bulk structure in (CsCl)nCs+ cluster ions is investigated using a mixed quantum-mechanical/semiempirical theoretical approach. We find that rhombic dodecahedral fragments (with bulk CsCl symmetry) are more stable than rock-salt fragments after the completion of the fifth rhombic dodecahedral atomic shell. From this size (n=184) on, a new set of magic numbers should appear in the experimental mass spectra. We also propose another experimental test for this transition, which explicitely involves the electronic structure of the cluster. Finally, we perform more detailed calculations in the size range n=31--33, where recent experimental investigations have found indications of the presence of rhombic dodecahedral (CsCl)32Cs+ isomers in the cluster beams.Comment: LaTeX file. 6 pages and 4 pictures. Accepted for publication in Phys. Rev.

A V-grooved GaAs solar cell

V-grooved GaAs solar cells promise the benefits of improved optical coupling, higher short-circuit current, and increased tolerance to particle radiation compared to planar cells. A GaAs homojunction cell was fabricated by etching a V-groove pattern into an n epilayer (2.1 x 10 to the 17th power per cu cm) grown by metalorganic chemical vapor deposition (MOCVD) on an n+ substrate (2.8 x 10 to the 18th power per cu cm) and then depositing and MOCVD p epilayer (4.2 x 10 to the 18th power per cu cm). Reflectivity measurements on cells with and without an antireflective coating confirm the expected decrease in reluctance of the microgrooved cell compared to the planar structure. The short circuit current of the V-grooved solar cell was 13 percent higher than that of the planar control

Microstructure, texture and tensile properties of ultrafine/nano grained magnesium alloy processed by accumulative back extrusion

An AZ31 wrought magnesium alloy was processed by employing multipass accumulative back extrusion process. The obtained microstructure, texture and room temperature tensile properties were characterized and discussed. Ultrafine grained microstructure including nano grains were developed, where the obtained mean grain size was decreased from 8 to 0.5 µm by applying consecutive passes. The frequency of both low angle and high angle boundaries increased after processing. Strength of the experimental alloy was decreased after processing, which was attributed to the obtained texture involving the major component lying inclined to the deformation axis. Both the uniform and post uniform elongations of the processed materials were increased after processing, where a total elongation of 68 pct was obtained after six-pass deformation. The contribution of different twinning and slip mechanism was described by calculating corresponding Schmid factors. The operation of prismatic slip was considered as the major deformation contributor. The significant increase in post uniform deformation of the processed material was discussed relying on the occurrence of grain boundary sliding associated with the operation of prismatic slip.Postprint (author's final draft

Molecular study of the populations of Artemia partenogenetica in Iran using PCR-RFLP Method

Considering the importance of genetic studies to manifest inter population differences in species, samples of Artemia partenogenetica were collected from seven inland lakes including Shoor and Inche-Borun lakes in Golestan Province, Hoze-Soltan and Namak lakes in Qom Province, Maharloo and Bakhteghan lakes in Fars Province and Mighan pool in Markazi Province. A total of 210 samples were subjected to DNA extraction by phenol-chloroform method. Primers were designed on a ribosomal fragment (16SrRNA) of the species' mtDNA sequence and the PCR was conducted on the samples. Digestion of the PCR product with approximately 1584bp lengths by 10 restriction endonuclease (AluI, EcoRI, Eco47I, HaeIII, HindIII, HinfI, MboI, MspI, RsaI, TaqI) showed 12 different haplotypes: 4 haplotypes in Shoor and Inche-Borun, 1 in Namak and Hoze-Soltan, 3 in Mighan pool, 1 in Bakhtegan and Maharloo and 3 in Maharloo. Haplotype diversity values within collected samples varied from zero in Hoze-Soltan, Namak and Bakhteghan samples to 0.7425 in Inche-Borun and Shoor while nucleotide diversity varied from zero in Hoze-Soltan, Namak and Bakhteghan, to 0.0077 in Mighan. The minimum nucleotide diversity among samples was zero between Hoze-Soltan vs. Namak and the maximum was 0.1700 between Inche-Borun and Shoor vs. Mighan. Nucleotide divergences among samples were least in Inche-Borun vs. Shoor (%-0.02) and most in Inche-Borun and Shoor vs. Mighan (%16.18), averaging to %3.40. The evolutionary distances between 12 haplotype showed that the maximum value belonged to Mighan haplotypes vs. Inche-Borun and Shoor haplotypes. Regarding the digestive patterns produced by each enzyme in the studied region, Eco47I is introduced as the population-specific marker of A. partenogenetica in Iran. Test of population differentiation based on haplotype frequencies were statistically significant (P≤0.001) with the exception of Hoze-Soltan vs. Namak and Inche-Borun vs. Shoor. We conclude that there are enough evidences in haplotypic level for dividing A. partenogenetica in Iran into five populations: Hoze-Soltan and Namak, Mighan, Maharloo, Bakhtegan, Incheh-Borun and Shoor

Peeled film GaAs solar cells for space power

Gallium arsenide (GaAs) peeled film solar cells were fabricated, by Organo-Metallic Vapor Phase Epitaxy (OMVPE), incorporating an aluminum arsenide (AlAs) parting layer between the device structure and the GaAs substrate. This layer was selectively removed by etching in dilute hydrofloric (HF) acid to release the epitaxial film. Test devices exhibit high series resistance due to insufficient back contact area. A new design is presented which uses a coverglass superstrate for structural support and incorporates a coplanar back contact design. Devices based on this design should have a specific power approaching 700 W/Kg

Molecular evaluation of the population of Silver Pomfret (Pampus argenteus) in the Persian Gulf and Oman Sea (Iranian &Kuwaiti waters)

A total of 162 specimens of Silver Pomfret (Pampus argenteus) including 38 samples from Kuwait and 124 samples from Iran (24 from Khouzestan, 24 from Chabahar and 38 from Bushehr) were examined for their DNA structure. DNA from all specimens was extracted using the Phenol-chloroform and amplified using PCR method with a pair of primers with ND sub(2) gene sequence. The PCR products were about 1300 (bp) for all samples. For RFLP analysis 16 restriction enzymes Bcl I, Pst I, Acc II, BseN I, Tru I, Dra I, Alw26 I, Hin6 I, Tas I, Alu I, EcoR I ,Hae III, Hinc II, Hind III, Hinf I and Hpa II were used. DNA bands were visualized by Gel electrophoresis (polyacrylamid) and staining with silver nitrate. Out of 16 enzymes, four showed polymorphism that includedg Hinf I, Alu I, Acc II, and Hpa II. Of the total 162 samples, 13 showed polymorphic patterns. Six haplotypes were rare occurring only once, but others which were only four different kinds occurred more than once. The REAP test gave no significant result for the examined regions (P>0.05). Therefore, our results revealed that the Pampus argenteus stocks in the Persian Gulf and Oman Sea of Iranian and Kuwaiti waters constitute a unique population

Conventional Fast Neutron Flux Measurement in the Radial Piercing Channel D of the TRIGA Mark II Reactor, Pavia

open8openMarco Di Luzio; Giancarlo D’Agostino; Setareh Fatemi; Barbara Smilgys; Andrea Salvini; Massimo Oddone; Saverio Altieri; Michele PrataDI LUZIO, Marco; D'Agostino, Giancarlo; Fatemi, Setareh; Smilgys, Barbara; Salvini, Andrea; Oddone, Massimo; Altieri, Saverio; Prata, Michel