Islamic Azad University North Tehran Branch

About: Islamic Azad University North Tehran Branch is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Adsorption & Catalysis. The organization has 868 authors who have published 968 publications receiving 9987 citations.

The Primacy of Teacher Imperative Commentaries in the Improvement of Iranian English Majors’ Writing Ability

Abstract: In this study, the researchers investigated a critical aspect of EFL/ESL writing pedagogy-the impact of teacher written commentary on student writer’s earlier drafts. Compositions of 80 Iranian undergraduate English majors were commented on using a trio of imperatives, statements, and questions on both content and form. Overall, the results indicated that the comments in the imperative form helped students improve their EFL/ESL writing ability more than the other two types. However, the difference between statements and questions was found not to be significant. The findings of this study, once again, emphasized the need for EFL/ESL writing instructors to communicate to learners with appropriate types of written comments. Moreover, employing imperative sentences can orient student writers towards a more accurate (i.e. form-focused) and appropriate (i.e. content-focused) composition writing.

Phase II monitoring of simple linear profiles under decreasing step shifts

Abstract: Recently, Profile monitoring in which the quality of a process or product can be characterized by a relationship between two or more variables has been considered by a lot of researchers. In different applications, the profiles can be linear or nonlinear in nature. Several methods have been proposed for monitoring simple linear profiles in Phase II. Some of these methods either have been developed to detect increasing step shifts or their performance is just evaluated under this type of shift. However, sometimes, a decreasing step shift can be occurred leading to poor performance of the process. In this paper, we modify the methods including T2, EWMA-3, and CUSUM-3 to improve their performance in detecting decreasing step shifts in Phase II. The performance of the modified methods as well as other existing methods including EWMA/R, MEWMA and LRT has been evaluated under decreasing step shifts by using simulation studies via Average Run length criterion.

Preparation of nano silver powder from acid leaching tail in gold room

Abstract: According to the unique properties and many applications of nano silver powder, it was prepared from acid leaching tail solution. The low value residual gold and silver ions were occurred with fellow heavy metals as pollutants (Fe 2+ , Cu 2+ and Zn 2+ ) in acid leaching tail solution in Mouteh gold mine in Iran. Preparation of nano silver particles was achieved in two steps: first, by addition of ammonia as a separation step and second by using different reagents as precipitation and extraction steps. Different controlled parameters were including pH, residence time and temperature, mixing time, and reducing reagents to metals molar ratio. Acid leaching process was carried out with sulphuric and nitric acid via suitable reductants. In order to remove copper, zinc, and silver ions from solution, all of the conditions were controlled. The optimum conditions for preparation of nano silver powder with less than 90 nm were pH 10.5, hydrazine/methanol to silver molar ratio of 3 to 4, and reduction time of 5 min in 45oC. The results were evaluated via SEM, A.A and UV- Vis spectroscopy analytical methods.

Chemical Composition of the Essential Oils from Leaves, Flowers and Pollen Grains of Chrysanthemum maximum Ramond. of Different Flowering Stages

Abstract: The oil obtained from the leaves, flowers and pollen grains of Chrysanthemum maximum during early and late flowering stage have been analyzed by combination of GC and GC-MS and towenty nine compounds were identified. The major monoterpenes and sesquiterpenes constituents were camphene, limonene, geosmin, β-elemene, (Z)-caryophyllene, (E)-caryophyllene, α-humullene, germacrene D and caryophyllene oxide. The relative amounts thereof differed substantially in the leaves, flowers and pollen grains of the herb. Also, different oil components were found in the early and late flowering stages of the different plant parts.

Dibromido(2,2'-dimethyl-4,4'-bi-1,3-thia-zole-κN,N')mercury(II).

Abstract: The asymmetric unit of the title compound, [HgBr2(C8H8N2S2)], contains two crystallographically independent mol­ecules. The HgII atoms are four-coordinated in a distorted tetra­hedral geometry by two N atoms from a 2,2′-dimethyl-4,4′-bi-1,3-thia­zole ligand and two Br atoms. In the crystal structure, inter­molecular C—H⋯Br hydrogen bonds and π–π contacts between the thia­zole rings [centroid–centroid distances = 3.670 (3) and 3.614 (2) A] stabilize the structure.