Characteristics of ⟨a⟩\langle a \rangle Screw Dislocations Basal Slip in Titanium

Plasticity in hexagonal close packed (HCP) metals and alloys such as Titanium (Ti) and Zirconium (Zr) is carried out by the motion of $\langle a \rangle$ dislocations. Above room temperature, in situ transmission electron microscopy straining experiments have shown that basal slip of $\langle a \rangle$ screw dislocations in Ti is activated and its preponderance increases with temperature. To discern the mechanism of basal slip of these dislocations in pure Ti, molecular dynamics (MD) simulations and nudged elastic band (NEB) calculations were performed for a screw dislocation gliding on the basal plane. From MD simulations, basal and pyramidal slip were shown to be intertwined. The screw dislocation glides by kink pair nucleation and propagation mechanism on one of the two equiprobable pyramidal planes adjacent to the maximum resolved shear stress basal plane, before switching to the other pyramidal plane, thus leading to an average basal slip at low stress and/or high temperature. On the other hand, NEB calculations revealed that at low stresses kinks do not nucleate in the pyramidal plane but rather directly in the basal plane fully compatible with the motion of a screw dislocation confined to the basal plane, in agreement with experimental observations in Ti and Zr. The discrepancy between these two mechanisms is shown to be related to the thermal activation of the cross-slip from the pyramidal to the prismatic core configuration of the $\langle a \rangle$ screw dislocation

Clinical significance of anti-Scl-70 antibody estimation in pediatric patients with systemic lupus erythematosus

Background: Some patients with scleroderma have overlap features with systemic lupus erythematosus (SLE). Anti-Scl-70 antibody was reported in as many as 35% of patients with scleroderma and signifies an increased risk for the development of pulmonary fibrosis and pulmonary hypertension. This antibody was detected in 25% of adult patients with SLE. Objective: We hypothesized that a particular subset of lupus patients might be at an increased risk of certain complications if anti-Scl-70 antibody was elevated in their sera. Methods: Serum anti-Scl-70 antibody levels were assayed by ELISA from 34 pediatric patients with SLE and from 24 healthy controls. Patients were also subjected to clinical evaluation for system involvement and for disease activity by systemic lupus erythematosus disease activity index (SLEDAI). The ESR, serum anti DNA antibody, serum complement 3, creatinine clearance and 24 hours urinary protein excretion were assessed and renal biopsy for histopathology was performed in selected cases. Results: Anti Scl-70 antibody was elevated (> 25 U/ml) in 6 SLE patients (18%), borderline (15-25 U/ml) in 17 patients (50%) and normal (< 15 U/ml) in 11 of them (32%). The patient group had significant elevation of serum anti-Scl-70 antibody levels (mean [SD] = 32.5 [8.8] U/ml) as compared to the controls, (mean [SD]= 9.3 [4.1] U/ml; p < 0.001). Patients with clinical lupus nephritis had significant higher levels of this autoantibody as compared to those without clinically evident renal involvement. Also, pulmonary hypertension was found significantly related to the high serum levels of anti-Scl-70 antibody. A significant positive correlation could link anti-Scl-70 levels to the ESR values and SLEDAI scores. Anti-Scl-70 levels were neither affected by the presence of neuropsychiatric involvement nor by intake of cytotoxic drugs. Conclusion: Anti-Scl-70 antibody is present in a significant subset of patients with SLE. For this subset, it offers a good correlate of disease activity and suggests an increased risk for pulmonary hypertension and renal involvement.Keywords: SLE; anti-Scl-70; pulmonary hypertension; lupus nephritis; SLEDAIEgypt J Pediatr Allergy Immunol 2006; 4(2): 53-60

A reproducible protocol for regeneration and transformation in canola (Brassica napus L.)

The objective of the present study is to develop an efficient protocol for shoot and plant regeneration using five commercial canola cultivars grown under the Egyptian agricultural conditions. The regeneration efficiency from hypocotyl explants was examined. The data indicated that embryonic calli were formed within two weeks in the presence of 1 mgl-1 2,4-D. Adventitious shoots emerged from the embryonic callus in the presence of 4.5 mgl-1 BA. The cultivars showed a varied response to shoot regeneration. Regeneration frequency was high in the cultivar Sarow-4 (68%) followed by Masrri L-16 (64%) compared with the other cultivars tested. Hypocotyl explants from the cultivars Sarow-4 and Semu-249 were inoculated and co-cultivated with Agrobacterium tumefaciens strain LBA4404 harboring a binary vector pBI-121 containing the neomycin phosphotransferase-II gene (NPT-II). The resulted putative transgenic plantlets were able to grow under knanamycin containing medium. The stable integration of the NPT-II gene into the plant genomes was tested by PCR using NPT-II -specific primers. The GUS gene expression can be detected only in the transgenic plants. The reported protocol in the present study is repeatable and can be used to regenerate transgenic canola plants expressing the genes present in A. tumifaciens binary vectors.Keywords: Agrobacterium, canola, GUS assay, regeneration, fransformation, NPT II gen

Strain rate dependency of dislocation plasticity

Dislocation slip is a general deformation mode and governs the strength of metals. Via discrete dislocation dynamics and molecular dynamics simulations, we investigate the strain rate and dislocation density dependence of the strength of bulk copper single crystals using 192 simulations spanning over 10 orders of magnitude in strain rate and 9 orders of magnitude in dislocation density. Based on these large set of simulations and theoretical analysis, a new analytical relationship between material strength, dislocation density, strain rate and dislocation mobility is proposed, which is in excellent agreement with the current simulations as well as with experimental data. The results show that the material strength is a non-monotonic function of dislocation density and displays two universal regimes (first decreasing, then increasing) as the dislocation density increases. The first regime is a result of strain rate hardening, while the second regime is dominated by the classical Taylor forest hardening. Accordingly, the strength displays universally, as a function of strain rate, a rate-independent regime at low strain rates (governed by forest hardening) followed by a rate hardening regime at high strain rates (governed by strain rate hardening). All the results can be captured by a single scaling function. Finally, the fluctuations of dislocation flow are analyzed in terms of the strain rate dependent distribution of dislocation segment velocities. It is found that the fluctuations are governed by another universal scaling function and diverge in the rate independent limit, indicating a critical behavior. The current analysis provides a comprehensive understanding on how collective dislocation motions are governed by the competition between the internal elastic interactions of dislocations, and the stress required to drive dislocation fluxes at a given externally imposed strain rate.Comment: 31 pages, 6 figures, 71 conference

Loss of miR-101-3p Promotes Transmigration of Metastatic Breast Cancer Cells through the Brain Endothelium by Inducing COX-2/MMP1 Signaling

Brain metastases represent one of the incurable end stages in breast cancer (BC). Developing effective or preventive treatments is hampered by a lack of knowledge on the molecular mechanisms driving brain metastasis. Transmigration of BC cells through the brain endothelium is a key event in the pathogenesis of brain metastasis. In this study, we identified miR-101-3p as a critical micro-RNA able to reduce transmigration of BC cells through the brain endothelium. Our results revealed that miR-101-3p expression is downregulated in brain metastatic BC cells compared to less invasive variants, and varies inversely compared to the brain metastatic propensity of BC cells. Using a loss-and-gain of function approach, we found that miR-101-3p downregulation increased transmigration of BC cells through the brain endothelium in vitro by inducing COX-2 expression in cancer cells, whereas ectopic restoration of miR-101-3p exerted a metastasis-reducing effect. In regulatory experiments, we found that miR-101-3p mediated its effect by modulating COX-2-MMP1 signaling capable of degrading the inter-endothelial junctions (claudin-5 and VE-cadherin), key components of the brain endothelium. These findings suggest that miR-101-3p plays a critical role in the transmigration of breast cancer cells through the brain endothelium by modulating the COX-2-MMP1 signaling and thus may serve as a therapeutic target that can be exploited to prevent or suppress brain metastasis in human breast cancer

SOIL EROSION BY TILLAGE IN RAINFED N-W. EGYPTION COAST

Tillage erosion is one of the main causes of land degradation. The objective of the present study is to evaluate the effect of tillage systems (up and downslope and contour tillage), soil conditions (consolidated and loosened soils), tillage depth, speed and slope on tillage erosion rate. Field experiments of variable slopes (3 - 16%) were established on sandy soil of Wadi El Ramala, west Mersa Matruh City. Soil translocation as affected by tillage systems and soil conditions were examined. In addition, soil losses by tillage erosion and water erosion were measured and evaluated. The experimental results showed that the average displacement distance is a function of gradient slopes, soil condition, tillage system, depth and speed. The validation of the soil translocation model developed by (Van Muysen et al 2000), under different gradient slopes, tillage depth, speed and soil condition were evaluated. This validation showed that variations in tracer displacement distance can be successfully predicted. Consequently, such model can be used under sandy soil. Finally, experiment results showed that tillage operations with a chisel plow under present agricultural practices are responsible for the major field redistribution of soil. Furthermore, it is clear that tillage of a loosened soil is far more erosive than tillage of a consolidated soil, where the tillage transport coefficient (K) was 105 kg.m-1 per tillage operation for consolidated soil and 179 kg.m-1 for loosened soil under contour tillage. However, 256 kg.m-1 per tillage prevailed for consolidated soil and 454 kg.m-1 for loosened soil under up and downslope tillage treatments

Učinak zamjene obroka od pšeničnih mekinja obrokom sa sjemenkama kima na nesenje, kvalitetu jaja i masnokiselinski profil u kokoši nesilica

The objective of the present study was to investigate the effect of substituting wheat bran (WB) with cumin seed meal (CSM) on laying performance, egg quality characteristics and egg-yolk fatty acids profile in laying hens. A total of 180 Bovans hens at 55 weeks of age were divided randomly into three treatments. The CSM was incorporated into a standard corn- and soybean meal-based diet by replacing 0, 50, and 100% of WB [i.e., 100% WB (control), 50% WB+50% CSM and 100% CSM] from 55 to 61 weeks of age. Body weight was measured at the beginning and end of the experiment. Feed intake, hen-day egg production and egg weight were recorded daily. At 61 weeks of age, 30 eggs were taken at random from each treatment group to determine the egg quality characteristics. Replacing 100% of WB by CSM did not affect body weight, however, hen-day egg production, egg weight and egg mass significantly increased, while feed conversion ratio significantly decreased (P<0.05). Haugh unit, shell thickness and yolk color significantly increased by CSM substitution in comparison with 100% WB. Plasma concentrations of total cholesterol, triglycerides, LDL-cholesterol and glutamic oxalacetic transaminase (GOT) significantly decreased by replacing WB with CSM, while, plasma HDL-cholesterol significantly increased. Furthermore, the liver malondialdehyde (MDA) concentration significantly decreased, while vitamin E, linoleic acid and alpha-linolenic acid significantly increased (P<0.05) due to CSM inclusion. Therefore, it could be concluded that substitution of WB with CSM could improve laying performance and egg quality characteristics, and reduce lipid peroxidation in laying hens.Cilj ovoga rada bio je istražiti učinak zamjene obroka s pšeničnim mekinjama (WB) obrokom sa sjemenkama kima (CSM) na nesenje, kvalitetu jaja te profil masnih kiselina u žumanjku jajeta kokoši nesilica. Ukupno je 180 Bovans kokoši u dobi od 55 tjedana slučajnim odabirom podijeljeno u tri pokusne skupine, u kojima su sjemenke kima dodane u standardni obrok s kukuruzom i sojom zamjenjujući 0, 50 i 100 % pšeničnih mekinja. Tako je kontrolna skupina hranjena obrocima sa 100 % pšeničnih mekinja, druga skupina s 50 % obroka s pšeničnim mekinjama i 50 % obroka sa sjemenkama kima, a treća skupina obrokom koji je sadržavao 100 % sjemenki kima. Pokusno razdoblje je trajalo od 55. do 61. tjedna starosti nesilica. Tjelesna je masa mjerena na početku i na kraju pokusa. Unos hrane, dnevna proizvodnja jaja i njihova masa bilježili su se svaki dan. U dobi od 61 tjedna iz svake je skupine slučajnim odabirom uzeto 30 jaja kako bi se odredila njihova kvaliteta. zamjenjujući 100 % obrok od pšeničnih mekinja sjemenke kima nisu utjecale na tjelesnu masu, no ipak su dnevna proizvodnja, težina i masa jaja znakovito porasle, dok se stopa konverzije hrane znakovito smanjila (P<0,05). Haugh-ova jedinica, debljina ljuske i boja žumanjka znakovito su porasle u skupinama u kojima su pšenične mekinje zamijenjene sjemenkama kima u odnosu na kontrolnu skupinu. Ukupni kolesterol, trigliceridi, LDL-kolesterol i glutaminska oksalooctena transaminaza (GOT) znakovito su sniženi u skupinama u kojima su pšenične mekinje zamijenjene sjemenkama kima, dok je HDL-kolesterol znakovito povišen. nadalje, koncentracija malondialdehida (MDA) u jetri znakovito je snižena, dok su vitamin E, linolna i alfa-linolna kiselina znakovito porasli (P<0,05) uslijed dodanih sjemenki kima. Može se zaključiti da zamjena obroka s pšeničnim mekinjama obrokom sa sjemenkama kima može poboljšati nesenje i kvalitetu jaja te smanjiti lipidnu peroksidaciju u kokoši nesilica