s.h. kaboli

Chemical fertilizers have a devastating impact on soil and the environment when used in seedling production and planting. Conversely, biofertilizers can enhance soil structure and fertility while mitigating the harmful effects of chemical fertilizers on the environment. This study aimed to identify an appropriate biofertilizer for Zygophyllum eurypterum, a species that is particularly amenable to arid area restoration. To this end, we conducted an experiments using six different biofertilizer treatments (Azotobacter chroococcum, Azospirillum lipoferum, Flavobacterium F-40, Bacillus megaterium, Pseudomonas fluorescens, and Rhizophagus irregularis) and fertilizer-free control in a completely randomized design by cultivation of the plants in the seedling bags with 15 replications. This was done in the spring of 2018, in the research farm of Semnan University. Vegetative growth parameters such as root length, fresh and dry weight of roots and shoots, number of leaves, shoot diameter, and total chlorophyll were measured three months after planting. The percentage of root colonization with mycorrhizal fungi was measured at three and six months of age of seedlings. In this context, the maximum length of root (33.40 cm) and shoot (18.20 cm), height (51.30 cm), weight of root (99.94 g) and shoot (473.90 g), number of leaves (58.00), shoot diameter (3.32 mm) and total chlorophyll (74.96) were observed in the treatment by Pseudomonas fluorescens. Symbiotic mycorrhizal fungi was confirmed and it increased root length and plant height. The percentage of root colonization increased over time. Root to shoot ratio was increased by application of Azospirillum lipoferum fertilizer. The results showed that the use of biofertilizers Pseudomonas fluorescens, Azospirillum lipoferum, and Rhizophagus irregularis can be recommended in the production of Zygophyllum eurypterum seedlings.

The importance of Nitraria scoberi in many arid and semi-arid biodiversity projects is undeniable. Improving the vegetative properties of this plant is critical to the success of these designs. The present study was designed to achieve the best chemical, biological and mechanical priming treatments to improve the vegetative traits. Experiments were conducted in a completely randomized design in both cultivating tray and seedling bags. Chemical treatments included salicylicacid and gibberellicacid. Biological treatments included Azotobacter, Azospirillum, Bacillus, Flavobacterium and Pseudomonu. The 24 kHz wavelength ultrasonic device was used. In cultivating tray, all traits except for germination percent and shoot length were significantly different. In seedling bag environment, seed Vigor Index, root length, Seedling growth, root fresh weight, Shoot fresh weight, shoot dry weight, leaf fresh weight , leaf dry weight, shoot diameter and number of leaves and root to shoot ratio showed significant difference; There were no significant difference between germination percent, shoot length and root dry weight. Maximum seed vigor index, root length and leaf dry weight in both of environment, and fresh weight of root and shoot, root dry weight, fresh weight and number of leaves in cultivating tray and in seedling bag root to shoot ratio, shoot diameter and seedling growth in salicylic acid treatment 2000 ppm was seen. Azospirillum increased root, shoot and leaf fresh weight, leaf number and shoot dry weight in seedling bag.

The ceramic fracture in output RF1 window is one of the most important failure factors in high power vacuum tubes. Fast protection systems are used to protect the tube. These protection systems are activated with some measured variables such as the level of backward RF power. On the other hand, a fast protection system can be activated with noise. Therefore, a tradeoff must be done between the response time of the protection system and its sensitivity to the noise. There are many methods to determine the response time of the protection system. The level of allowable power loss in the tube failure process is one of the conventional figures of merit for protection response time determination. However, these methods are conservative and the resulted response time is usually less than the critical time which is necessary for protecting the tube. In this paper, an experimental investigation is presented about the relation between the response time of the tube protection system and the crack growth in the ceramic of RF window. It is shown that the twin growth in ceramic can be a reliable figure of merit for the response time calculation of the tube protection system.

Blumlein bipolar pulse former is a widely used bipolar pulse generator with good performance. This structure produces a bipolar pulse from a unipolar pulse using the reflection theorem of the waves in transmission lines. Practical considerations in the design process of Blumlein bipolar pulse former is an important issue from the view point of output voltage waveform quality and construction cost. In this paper, a Blumlein bipolar pulse former has been simulated and analyzed to investigate the effect of different physical parameters on the output voltage waveform. The results of simulations can be used to design a bipolar pulse generator with acceptable output voltage waveform.

In this paper, a high power tetrode tube (TH781-200kW, cw) modulator is designed and implemented. This modulator is used for a part of RF system of the first Iranian high power electron accelerator project with similar structure to Rhodotron accelerator. Regarding to the level of sensitive and importance of TH781 tube the modulator system designed with high accuracy. So beside of power supplies design the control circuits for protection of the tube have been considered. The results of test and operation of this system that have been constructed in Iran for fist time is very satisfactory.