13949 research outputs found
Sort by
Action of Salinity on Seed Germination and growth of (Solanum melongena L.)
No full textEffect of seven salinity levels on seed germination, length, fresh and dry weights, carbohydrates contents and - amylase activity seedlings of Solanum melongena (egg plant) was studied. Salinity progressively decreased the percentage of germination. The length and the fresh and dry weights of root and shoot increased level increased with increasing level of salinity up to 8.5 m. mhoss/cm EC, indicating that the egg plant tolerate quite high level of salinity at seedling stage. The soluble and insoluble carbohydrates contents and -amylase activity were also affected by salinit
Experiments to produce cysts in cultures of Histomonas meleagridis—the agent of histomonosis in poultry.
No full textExperiments were done with cultured trophozoite stages of different clonal strains (Histomonas meleagridis/ Turkey/Austria/2922-C6/04 and H. meleagridis/Chicken/ Hungary/5009-C2/05) of H. meleagridis in order to induce
a cyst formation as it is known in other intestinal parasites. It was shown that the best multiplication of H. meleagridis occurred at 40°C in a full medium 199, when fetal calf serum and rice starch had been added. Under these conditions, numerous amoebic stages (8–12 μm in diameter) without and a few with flagellum were seen showing regular reproduction rates. When the conditions of culture
were experimentally changed—and thus became worse— by decreasing the temperature, by deprivation of the medium from fetal calf serum and/or rice starch, and by changing the osmolarity, the pH, or the MgCl2 concentration, many of the amoebic stages (containing starch granules) were destroyed, and several had obtained a spherical shape. If the culture conditions became even worse, smaller spherical stages occurred, which had only diameters of 4–7 μm and which appeared more condensed. Both spherical stages did not contain starch granules. All the previously seen stages disappeared constantly. Since a similar decrease of the optimal living conditions also occurs when intestinal or cloacal feces are deposited outside from the bird’s body, the results obtained here may underline the interpretation that some of the formerly amoebic stages are able to become large spherical stages and later small
spherical stages. The large spherical stage would be some
type of precysts while the smaller ones would represent true
cysts
Arabidopsis V-ATPase activity at the tonoplast is required for efficient nutrient storage but not for sodium accumulation..
No full textThe productivity of higher plants as a major source of food and
energy is linked to their ability to buffer changes in the concentrations of essential and toxic ions. Transport across the tonoplast is energized by two proton pumps, the vacuolar H+-ATPase (VATPase) and the vacuolar H+-pyrophosphatase (V-PPase); however, their functional relation and relative contributions to ion storage and detoxification are unclear. We have identified an Arabidopsis mutant in which energization of vacuolar transport solely relies on the activity of the V-PPase. The vha-a2 vha-a3 double mutant, which lacks the two tonoplast-localized isoforms of the membrane-integral V-ATPase subunit VHA-a, is viable but shows day-length-dependent growth retardation. Nitrate content is
reduced whereas nitrate assimilation is increased in the vha-a2
vha-a3 mutant, indicating that vacuolar nitrate storage represents
a major growth-limiting factor. Zinc is an essential micronutrient
that is toxic at excess concentrations and is detoxified via a vacuolar
Zn2+/H+-antiport system. Accordingly, the double mutant
shows reduced zinc tolerance. In the same way the vacuolar
Na+/H+-antiport system is assumed to be an important component
of the system that removes sodium from the cytosol. Unexpectedly,
salt tolerance and accumulation are not affected in the vhaa2
vha-a3 double mutant. In contrast, reduction of V-ATPase activity
in the trans-Golgi network/early endosome (TGN/EE) leads to
increased salt sensitivity. Taken together, our results show that
during gametophyte and embryo development V-PPase activity
at the tonoplast is sufficient whereas tonoplast V-ATPase activity
is limiting for nutrient storage but not for sodium tolerance during
vegetative and reproductive growt
Effect of the Antioxidant Butylatedhydroxytoluene on the Genotoxicity and Cytotoxicity Induced by Arsenic Trioxide in Male Mice.
No full textThe present study aims to evaluate the effect of antioxidant and on the genotoxicity and apoptosis induced in mice by arsenic trioxide (As2O3) in normal adult male SWR/J mouse. Animals were treated intraperitoneally (ip) with single doses (2.65, 5.35 or 10.70 mg kg-1 b.wt. of As2O3 and decapitated 24 h later. Another group of animals were treated firstly with 60 mg kg-1 b.wt. of the antioxidant agent butylated hydroxytoluene (BHT) 1 h prior to As2O3 doses administration. The three treated single doses of As2O3 significantly (P<0.05) increased the rate of sister chromatid exchanges (SCEs), micronucleus (MNs) formation, DNA ladder and apoptosis as compared with the negative control. The three treated doses with BHT were significantly (P<0.05) increased the rate of MNs as compared with the effect of the individual single doses. With agarose gel electrophoresis, DNA ladder were clearly detected in all the treated mice. The data recorded revealed that, administration of As2O3 had a negative effects as represented in SCEs, MNs and DNA ladder test. Thus, we have demonstrated that arsenic trioxide play direct or indirect role in the induction of genotoxicity and apoptosis in mice cells
Modified DFIG control strategy for wind energy applications
No full textA detailed computer simulation for interconnecting wind energy system to an electric utility is presented. The proposed system consists of four high rating wind turbines each one uses double fed induction generator (DFIG). Two back to back bidirectional PWM inverters are used in the rotor circuit of each DFIG to be interfaced with the electrical utility. The simulation incorporates a flexible independent control for the active and reactive powers by using field oriented control technique. Also it introduces an effective technique to track the maximum power point of the wind energy by controlling the pitch angle and rotational speed. Active power is controlled through the direct axis current of the rotor side converter in outer control layer. Reactive power is controlled by the quadrature axis current of the rotor side converter. The system shows a stable operation under different operating conditions. © 2010 IEEE.IEEE 2010 International Conferenc
Investigation of new ground structure for reducing human exposure to electromagnetic fields from mobile phones
No full textThe presence of human body can significantly alter the antenna performance. The radiation efficiency and gain reduction are the examples of antenna performance reduction in the presence of human body. The bandwidth can also be increased in the vicinity of human body, especially in the case of antennas with relatively high SAR values. To protect the users from hazardous RF exposure, safety guidelines or limits called Specific Absorption Rate (SAR) have been made by Federal Communication Commission (FCC). According to IEEE, SAR is the time derivative of the incremental energy absorbed by (dissipated in) an incremental mass contained in a volume element of given density [1]. Planar Inverted F-Antenna (PIFA) is considered as one of the most suitable antenna structure for mobile handset application due to low profile, simple structures, and reasonable antenna performance [2-3]. There are many methods proposed to PIFA structure to reduce SAR levels. The simplest method is increasing the distance between human head and mobile handset antenna [4], [5]. This can be achieved by the application of back mounted antenna for mobile handset. Ferrite material has been proposed in order to reduce handset SAR values [6], [7]. The ferrite sheet is used to suppress the current flowing in the handset box. It is found that the ferrite attachment can reduce the SAR up to 57.75% due to current suppression flowing on the front side of the mobile handset. In 2006, Chan, et al have studied the effect of sidewall attachment of internal patch antenna ground plane on SAR values [8]. It is found that the sidewall attachment reduces the SAR values and reduces the radiation efficiency. © 2010 IEEE.IEE
Digital implementation of harmonics reduction of three-phase boost rectifier
No full textThe line currents of three-phase diode bridge rectifier suffer from high THD. This THD is higher than IEEE standards. Injection of six harmonic components to the control signal of the boost converter connected to the three-phase diode bridge rectifier reduces the THD of the utility line current. In this paper a digital implementation of injecting six harmonic to the control signal of three-phase boost rectifier is shown. The digital implementation is carried out by using FPGA. In this study a sin-wave and a triangle-wave with six times the fundamental frequency and variable amplitude are digitally generated in the FPGA. Each signal is added to the dc control signal component of boost converter to be compared with digitally generated saw-tooth. The simulation and experimental results show that the THD of the utility line currents depends on the amplitude and phase-shift of the six-order component injected to the control signal of the boost converter and the angle of input three-phase voltage. ©2010 IEEE.14th International Conference on Harmonics and Quality of Powe
Polynomial lower bounds for the two-machine flowshop problem with sequence-independent setup times
No full textIn this paper, we address the problem of two-machine flowshop scheduling problem with sequence independent setup times to minimize the total completion time. We propose five new polynomial lower bounds. Computational results based on randomly generated data show that our proposed lower bounds consistently outperform those of the literature.King Saud University, Riyadh, Saudi Arabi
Training Needs for the Heads of Departments
No full textParticular and clear ethics of professionals should be available to any profession and professionalization, should be available. It is important for the education career to have clear and declared ethics that bind the teachers' behavior in relation towards their students and society.
The present paper tries to achieve certain goals such as the following:
a- To know the nature of ethical and educational values.
b- To know the nature of ethical and educational framework of education and to apply the same on Saudi education system.
c- To know the ethical sources of education career in the Saudi education system.
d- To know the ways of enhancing the ethics of education career in teachers under the Saudi education system.
To achieve these goals, the present paper tries to answer the following questions:
a- What are the ethical and educational values found in education literature?
b- What is the ethical and educational framework of education career that is applied on the Saudi education system?
c- What are the ethical sources of education career on in Saudi education system?
d- What are the suggested means that enhance ethics of education career in teachers under the Saudi education system?
In the conclusion, the paper highly recommends the following:
a- Tackling or handling daily double standard behavior of teachers.
b- The necessity to avail a clear educational approach among teachers.
c- The need for the authorization of practicing the education career.
d- Issuing a document the includes ethics of education career.
e- Providing sustained educational opportunities for teachers.
f- Giving opportunity to teachers to voice their opinions.
Potentiality in using measures as to focus on internal control and auto-contro
FORMATION OF HYDRAULIC JUMPS ON CORRUGATED BEDS
No full textA study of the effect of different shapes of corrugated beds on the characteristics of hydraulic jumps was conducted. Experiments were performed for a range of the Froude number from 3 to 7.5. Five shapes of corrugations (sinusoidal, triangular, trapezoidal with two side slopes and rectangular) of the same amplitude and wavelength were tested. Two values of relative roughness t/y1 of 0.36 and 0.72 were studied. It was found that, for all shapes of corrugated beds, the tailwater depth required to form a jump was appreciably smaller than that for the corresponding jumps on smooth beds. Further, the length of the jump on the different corrugated beds was less than half of that on smooth beds. The integrated bed shear stress on the corrugated beds was more than 15 times that on smooth beds. For the same amplitude and wavelength, it was found that the effect of the shape of corrugations is relatively small. The results of this study confirm the effectiveness of corrugated beds for energy dissipation below hydraulic structures.Research Center, Faculty of Engineering, King Saud Universit