Display omitted
•Magnetic field affects the electroconvection threshold in magnetic nanofluid.•Magnetic field significantly changes the geometry of the electroconvective pattern.•The effect of the ...magnetic field is evident in the low strength range < 10 kA/m.•Critical voltage increases with the fluid layer thickness and the voltage frequency.•Electroconvective instability development time decreases with voltage increasing.
It is shown that the external magnetic field (of the strength < 10 kA/m) parallel to the electric field (DC and AC) reduces the electroconvection development threshold voltage and the time of electroconvection development (up to 50 %), and creates a more branched pattern of electroconvective flows in a layer of magnetic nanofluid. The magnetic field perpendicular to the electric field increases the electroconvection development threshold (up to 15 %) and leads to electroconvective pattern degeneracy into a system of strips parallel to the magnetic field. It is demonstrated that the critical voltage increases with increasing magnetic nanofluid layer thickness and voltage frequency.
Leek (Allium porrum) has become one of the major leafy vegetable crops in Egypt and all over the world. Iris yellow spot virus (IYSV) was observed on leek plants in eight different governorates in ...Egypt, in fields near to onion fields. The symptoms in infected leek plants included yellowish or tan diamond-shaped or irregularly shaped lesions on leaves and flower stalks. Necrotic areas developed on leaves, and some plants had elongated brown lesions or brown flecks resembling thrips injury. Moreover, thrips larvae and adults feed with a punch-and-suck behavior that removes leaf chlorophyll, causing white to silver patches and streaks, which were observed on all infected plants. The plant samples were collected and subjected to ELISA test using IYSV polyantiserum. The results revealed that about 90% of the collected samples with symptoms were positive. For further confirmation, the ELISA positive samples were subjected to PCR amplification using nuclear coat protein specific primers. The PCR results were in agreement with the results obtained by ELISA. Thrip tabaci adults were reared on the infected plant and biological transfer was performed onto new healthy plants. After 15 days to 4 weeks post inoculation, symptoms were observed on the plant. Biologically infected plant samples were collected at different times after thrips-inoculation and the extracted RNA was subjected to Real Time PCR using the coat protein gene primers. The results showed that the expression of the coat protein fluctuated but reached its peak on day five (264%). Differential display technique was performed on the newly infected plant tissues to identify changes in gene expression in leek elicited by IYSV that causes a symptomatic phenotype. Both up- and down- regulated genes were observed in infected plants conjugated with the healthy ones. Sequence analysis of the up-regulated genes was performed and the encoding sequence analysis showed that the obtained genes include: MFS family protein, Pathogenesis- related protein, Mitogen-activated protein kinase, N-acetylserotonin O-methyltransferase-like protein, Serine/threonine-protein kinase, and Putative Retrosat2 Ty3-Gypsy retroelement. On the other hand, only one down-regulated gene was identified, alpha- tubulin suppressor-like protein. Most of the identified genes are suppress defensin genes (innate/adaptive). It can be concluded that viral infection is capable of inducing a huge number of genes which are important in the plant immune system.
The present work describes and evaluates the reservoir quality of the sandstone of the Nubia Formation at the Gebel Abu Hasswa outcrop in southwest Sinai, Egypt. Hydraulic flow unit (HFU) and ...electrical flow unit (EFU) concepts are implied to achieve this purpose. The Paleozoic section made up of four formations has been studied. The oldest is Araba Formation followed by Naqus formations (Nubia C and D) overlay by Abu Durba, Ahemir and Qiseib formations (Nubia B), where the Lower Cretaceous (Nubia A) is represented by the Malha Formation. The studied samples have been collected from Araba, Abu Durba, Ahemir and the Malha formations. The hydraulic flow unit (HFU) discrimination was carried out based on permeability and porosity relationship, whereas the electrical flow unit (EFU) differentiation was carried out based on the relationship between formation resistivity factor and porosity. Petrographic investigation of the studied thin sections illustrates that the studied samples are mainly quartz arenite. Important roles to enhance or reduce the pore size and/or pore throats controlling the reservoir petrophysical behavior are due to the diagenetic processes. The present study used the reservoir quality index (RQI) and Winland R
35
as additional parameters applied to discriminate the HFUs. The study samples have five hydraulic flow units of different rock types, where the detected electrical flow units are only three. The differences between them are may be due to the cementation process with iron oxides that might act as pore filling, lining and pore bridging, sometimes bridges helping to decrease permeability without serious reduction in porosity. The reduction between the number of EFUs and HFUs comes from the effect of diagenesis processes which is responsible for a precipitation of different cement types such as different clay minerals and iron oxides.
Background
Squash leaf curl virus (SLCV) is efficiently transmitted and spread by the whitefly,
Bemisia tabaci
(Gennadius), which is the only vector that transmits
begomoviruses
naturally causing ...huge crop losses through feeding damage. The widespread use of chemical insecticides to control the whitefly
B. tabaci
has become extremely hazardous to the environment. Alternative methods such as biological control have been advocated. Entomopathogenic fungi (EPF) have been found as promising whitefly bio-pesticides.
Results
Naturally infected squash plants that showed symptoms of squash leaf curl disease were collected from Giza Governorate, Egypt. SLCV was detected using a PCR assay using coat protein-specific primers and generated an amplicon of 419 bp. Multiple sequence alignment showed that the SLCV-Giza isolate has a significant identity of 99.2% with the SLCV-Mx:BCS: La Paz isolate from Mexico and 99% with the SLQV.Q2521 isolate from Egypt. Phylogenetic analysis showed that SLCV-Giza is closely related to the SLCV-Mx:BCS: La Paz isolate from Mexico. The whitefly transmission test revealed that the virus transmitted to an extent of 13.3% and reached 100% of transmission using 15–20 viruliferous whiteflies; while the efficiency of syringe injection was (60%).
B. tabaci
newly emerge adults were able to acquire and transmit SLCV after an Acquisition Access Period (AAP) of 15 and 30 min by low rates of 13.3 and 22.2%, respectively. The transmission rate was increased gradually to reach the maximum of 100% after 24, 48, and 72 h (AAP).
B. tabaci
was able to inoculate SLCV after an Inoculation Access Period (IAP) of 15 and 30 min with rates of 46.7 and 62.2%. The whitefly was allowed to acquire SLCV from a squash plant (virus source) treated previously with EPF (
Beauveria bassiana
) and allowed to transmit the virus to the test plants. The transmission effectiveness of viruliferous whitefly was lower (33.4%) than that of non-treated whitefly (100%). The transmission efficiency was decreased on the second day by 6.8% and by the third day by 2.2% of treatment with the EPF. The results were validated by PCR assay for SLCV from tested squash plants and the PCR did not reveal specific amplification.
Conclusions
The use of EPF (
B. bassiana
) for
B. tabaci
control had a direct impact on SLCV accumulation and transmission.
This study used data from an investigation into the mapping of manganese-iron (Mn-Fe) mineralization, located within the Um Bogma formation. The ore takes the form of patchy isolated bodies or lenses ...in the three members of the Um Bogma formation located in East Sinai, Egypt. Magnetic, resistivity, and induced polarization (IP) surveys were applied at the Wadi Al Sahu area to delineate the mineralized ore bodies in terms of depth and extension. The quantitative interpretation of magnetic data was carried out using the 2D analytical signal. The results of the magnetic interpretation indicated that the depths of such ore deposits range from − 2 to − 20 m, and the shape of the magnetized units (assumed to be manganese-iron ore) is lenticular and of small size ranging from 20 to 100 m in width. Three dipole-dipole geo-electrical traverses were carried out along the anomalous sites, the traverse locations selected from the constructed magnetic maps of the study area, and the resistivity and IP measurements along with them. The results of the resistivity and IP inversion indicate that there are conductive and chargeable bodies at a depth that indicate the shape of small Mn-Fe lenses being present and conform to the shape of the Mn-Fe ore mineralization. Integration between the magnetic and geo-electrical data is made to lessen the non-uniqueness problem in geophysical prospecting. In this case, we used electrical resistivity and induced polarization models to delineate the boundaries between different geo-electric units, and these boundaries were used as interfaces between layers with different magnetic susceptibility for magnetic modeling to perform magnetic data inversions.
PDF
