Showing 4 results for Nahvi
I. Nahvi, M. Vaez, G. Emtiazi,
Volume 4, Issue 3 (fall 2000)
Abstract
Carotenoids are one of the most important and widely distributed pigments in nature and have essential biological functions in organisms. They also impart distinctive and attractive coloration to the breeding animals. Over the past two decades, application of microbial carotenoids has attracted the attention of researchers due to their natural and economic advantages. However, carotenoid producing yeasts with lactose assimilating capacity have rarely been studied and there are few references on the use of lactose as a carbon substrate, such as whey, for the biosynthesis of yeast carotenoids. In this study, a red carotenoid-producing yeast, Rhodotorula acheniorum, was isolated from the sap of birch trees at Masseh Chal in the Taleghan village. The yeast thus isolated was identified through microscopic, macroscopic and biochemical tests.
The yeast has both the abilities of lactose assimilation and carotenoid production. The optimal conditions of culture were determined and maximum biomass and carotenoid production were 9.9 g/lit, 290 µg/g, respectively. Chemical analyses of extracted carotenoids have shown that the major portion of the yeast consists of β-carotene, torulene and torularhodin. With regard to the fact that whey is one of the by-products of cheese industries and that its proper disposal has long been a major problem, the most desirable way of handling this waste is to utilize it as a substrate in the production of useful products such as carotenoids.
S. Farrahi-Ashtiani, M. Mahdiyeh, I. Nahvi,
Volume 6, Issue 2 (summer 2002)
Abstract
In order to increase ketocarotenoid astaxanthin production by Haematococcus pluvialis, the effects of salinity, phosphate deprivation and eosin on growth and astaxanhin production were examined. The experiments were carried out in the growth chamber at 20oC under sterile conditions. The results showed that under salinity, phosphate deprivation and eosin supply, encystment was induced, and at the same time, astaxanthin formation and dry weight increased. Furthermore, by adding histidine to culture medium as a quencher of singlet oxygen, astaxanthin production significantly reduced. Therefore, it can be claimed that accumulation of astaxanthin may be related to antioxidative responses, which increased survival of algal cells under environmental stress conditions.
R. Arefi, H. Nahvi, A. Hemat,
Volume 10, Issue 3 (fall 2006)
Abstract
The objective of this research was to design and develope a Pick and Position system to displace spherical-shaped fruits, with minimum damage to flesh, from one specific place to another. A mechanical gripper (end-effector) suitable for grasping spherical-shaped fruits with 5-9 cm in diameter was designed and developed. The primary goal of the gripper design was to take and release the fruit without bruising it in a specified time sequence. A slider-crank mechanism was used to drive the gripper. To achieve suitable timing in gripping and releasing of the fruit, the slider was driven by a cam. The kinematic and dynamic analysis of the gripping unit was done and its motion was simulated using Working Modwl software. In the next step, a four-bar mechanism (arm) was designed and developed to displace gripper between two specified locations. After kinematic analysis, equation of motion of the arm mechanism was derived and its dynamic analysis was performed. The gripper was assembled on the arm mechanism and the performance of the gripper and arm mechanism was investigated. It was observed that the system had the ability to pick and release the oblong fruits, such as apple, between two specified locations. The performance of the system for larger size fruits could be improved by some modifications on the gripper fingers.
M. Modaraye Mashhoud, M. Esfahany, M. Nahvi,
Volume 11, Issue 42 (winter 2008)
Abstract
In order to reduce the rainfall damages on rice yield at harvest stage, a field experiment was conducted at Rice Research Institute of Iran, Rasht, in 2004 by using Sodium Chlorate as a chemical desiccant. Five seed moisture contents of Dorfak rice cultivar were considered as experimantal treatments [24 - 28% (M1), 22 - 24% (M2), 20 -22% (M3). 18 - 20% (M4) and control (M5= conventional harvesting)]. The experiment was carried out in a randomized complete block design with three replications and the effects of treatments on grain yield, head rice yield,seed germination rate and percentage, kernel breakage, kernel cracking, amylose content, gelatinization temperature and gel consistency were evaluated. Results showed that the whole plant and grain moisture contents were significantly reduced in all experimental treatments compared with control. M2 and M3 both cosiderably reduced the plant moisture content in which harvesting occurred 12 and 8 days respectively sooner than the control. In M1, due to high grain moisture and non - simultaneous grain filling in different tillers, many of panicles desiccated prior to maturity lost their quality. In M4, the crop harvested was only 2 days earlier than the control. Analysis of variance showed that there were no significant effects of treatments on evaluated traits. It seems that rice plant could be reliably desiccated by Sodium Chlorat and harvested earlier without any adverse effects on its quality and quantity.
