فهرست مطالب محسن حاتمی

Recently, array waveguides have been considered for the design of ultra-fast optical processors, especially in the field of artificial intelligence. In this article, we first obtained the propagation constant of each waveguide separately with Lumerical software and calculated the supermodes of a waveguide array consisting of 6 waveguides using MATLAB software. By using coupled mode theory, we designed a waveguide array with 6 waveguides which consisting of chalcogenide core on the insulator then we obtained the corresponding supermodes. We have shown that the use of chalcogenide materials can be used cause to reduce length of integrate optical circuits, in addition, it can be used for designing of non-linear optical devices due to the high non-linear coefficient of chalcogenide materials.

Manipulating of training variables with the aim to augment muscle metabolic stress could result in muscle hypertrophy.The purpose of the current study was to present a lacto-resistance training method and to compare its effect on rectus femoris muscle hypertrophy with traditional resistance training.

Twenty- four male professional bodybuilders were randomly divided into three groups based on muscle cross-section area: lacto-resistance (n=8), traditional-resistance (n=8) and control (n=8). The comparison of metabolic stress between two types of exercise was done using monitoring blood lactate and urea following squat exercise. Muscle cross-section area and strength were measured by sonography and one repetition maximum (1RM), respectively, before and after 4 weeks of resistance training.  Analysis of covariance was used to evaluate inter – and intra groups differences.

Compared to the baseline values, blood lactate levels significantly increased following squat exercise in both lacto-resistance (10.76±1.35) and traditional–resistance (7.70±1.16) groups, and the changes in blood lactate was significant between two groups (P˂0.05). After 4 weeks of resistance training, the changes in rectus femoris muscle cross-section had a significant difference only in lacto-resistance group in comparison to its own baseline values (P˂0.05) and the control group (P˂0.05). Compared to the baseline values, 1RM measured in squat exercise significantly increased in both experimental groups (P˂0.01), the difference between groups was significant, and lacto-resistance group had higher values than those from the traditional-resistance group (P˂0.05).

Compared to the traditional resistance training, Lacto-resistance training induces a higher metabolic stress and its effects on muscle hypertrophy and strength are more impressive.

In this paper, design and simulation of a side pumped Er:Yb:glass laser is reported. We designed an air cooled system for using Close Coupling method and reduction of the volume and the weight of the system. In this case, symmetrizing and uniformity of pumping is done by using of three laser diodes to pump at a Y shape structure. To optimize system designed, energy and shape of the output laser is studied by change of the main components of the resonator parameters that we could increase the output energy, reduce the pulse width and achieve desired divergence without using of the optical elements. By this condition, we derived a pulse with output energy of 17.8 mJ, pulse width of 13.2 ns and beam with divergence of 4 mrad at repetition rate of 10 Hz in the eye safe band.

Tomato is a climacteric fruit and its ripening can be completed after harvest. Provided that appropriate storage condition for a given harvesting stage is implemented، fruits are endowed with proper quality for the market. In order to study the effects of maturity stage on fruit storage life، tomato fruits were harvested at three ripening stages. They were stored at three storage conditions i. e. 5 ˚C، 13 ˚C، and a simulated condition (SC) of the interval between harvest and consumption by the consumer. Fruit color، lycopene، firmness، pH، titratable acidity (TA)، total soluble solids (TSS)، ascorbic acid، weight loss، and chilling injury (CI) were measured and evaluated during the experiment. Results showed that at the end of the storage at 13 ˚C، mature green fruits had relatively similar values of color، lycopene content، TA، TSS، and firmness compared to the red ones، with the exception of their ascorbic acid. While storage of different maturity stages of tomatoes at 13 ˚C developed normal ripening، storage at 5 ˚C and SC disturbed the normal ripening process.

Sensitivity of tomato fruit to low temperature and chilling injury limits the storage, handling and marketability of the fruit. As a recommended postharvest treatment, effects of hot water treatment (HWT) on reducing chilling injury and quality traits, variation of tomato fruits during storage life were investigated. Tomato fruits were harvested at mature green stage. They were treated by hot water at 45 ˚C for 15 min, then placed at three storage temperature conditions including 5 ˚C, 13 ˚C, and at a Simulated Condition (SC) of the interval between harvest and consumption by the consumer. Storage period was 43 days. Fruit color, lycopene, weight loss, firmness, enzyme activity of polygalacturonase (PG), ascorbic acid and Chilling Injury (CI) were assessed and evaluated during the experiment. While storage of mature green tomatoes at 13 ˚C developed normal ripening, storage at 5 ˚C and during SC disturbed the normal ripening process. HWT caused delay in surface color development to some extent, resulting in reduction in weight loss and enzyme activity as well as in enhancing ascorbic acid and lycopene contents. It also had a significant effect on reduction of CI in mature green tomatoes. Based on the results, it can be concluded that in tomato as a climacteric fruit, HWT and temperature condition of storage exert significant effects on its storage and shelf life. This study confirmed that 13 ˚C is the optimum temperature for maintenance while HWT is a proper postharvest treatment as regards tomato fruit.