UNTRADITIONAL METHODS OF P-APPLICATION FOR RAISING ITS EFFICIENCY ON SANDY SOIL

Soils of Egypt characterize with raising pH values, CaCO3 content, clay and Fe & Al oxides. These factors contribute, to a large extent, in P-fixation in soil and its transformation into unavailable forms. This reflect, in turn, on plant growth and the resultant crop. So, the main target of this investigation is raising the use efficiency of P-fertilization, decreasing P-fixation, increasing its availability in soil and promoting its uptake by plant through testing new methods for P-application compared with the traditional one (P-application before sowing). Therefore, two field experiments were designed in sandy soils during the two winter seasons 2002/2003 and 2003/2004 at South Tahrir Res. Station, Ali Moubark village, El-Bustan region, Behira gover-norate under drip irrigation system. For the two experiments, P was applied as soil or seed coating. Soil application treatments were added at a rate of 30 kg P2O5/fed., once before sowing, twice: before sowing and during the vegetative growth stages or in three portions, before sowing and during the vegetative and flowering growth stages. In seed coating method, seed were coated before sowing with P at rates of 0.1, 0.2 and 0.3 kg P2O5/kg seed. Data obtained revealed that the treatments of P-soil application generally surpassed the P-seed coating ones. In this respect, P-soil appli-cation in three portions (at sowing and during the vegetative and flowering growth stages) gave the highest increments in seed, straw and seed protein yields as well as macro- and micronutrients contents in both seed and straw compared with the tradi-tional method of soil P-application. Moreover, seed coated with 0.2 kg P2O5/kg seeds attained the highest increases in all abovementioned yield components and nu-tritive contents among the treatments of seed coating method, whereas, coating of seeds with 0.3 kg P2O5/kg seeds caused the least ones. Therefore, it can be conclud-ed that the addition of P to sandy soil at a rate of 30 kg P2O5/fed., in three portions, i.e. at sowing and during the vegetative and flowering growth stages reduce P-fixation by soil factors, increase its availability, promote its uptake by plant, achieve the highest productivity of faba bean seed, straw and seed protein yields and im-prove the nutritive contents of both seeds and straw

The Attenuation Capability ofSelected Steel Alloys for Nuclear Reactor Applications

Neutronsand gamma ray attenuation of different steel grades (SS304, SS304L, SS316L, SS430, a modified high manganese-nitrogen austenitic stainless steel, and developed cobalt-free Maraging steel) was measured to study their capability to be used as nuclear reactor materials. The hardness and microstructure of the studied steel alloys were carried out using Vickers hardness and optical microscope respectively.Neutron and gamma rays measurements were carried out using a narrow beam transmissions geometry method. Measurements and calculations of gamma ray attenuation coefficients were carried out at energies 238.63, 338.28, 583.19, 911.2, 968.97, 1173.23, 1332.49, and 2614.51 keV. The transmitted gamma rays were detected by the Hyper Pure Germanium detector (HPGe), while, the neutron flux emitted from 241Am-Be neutron source was used to measure the neutron removal cross section for both slow and total neutrons. The transmitted beam of neutrons was measured under a good geometric conditions using 3He counter.A good agreement between experimental data of mass attenuation coefficients and theoretical results calculated by the WinXcom computer program (version 3.1) was obtained

Mathematical formulae for neutron self-shielding properties of media in an isotropic neutron field

The complexity of the neutron transport phenomenon throws its shadows on every physical system wherever neutron is produced or used. In the current study, an ab initio derivation of the neutron self-shielding factor to solve the problem of the decrease of the neutron flux as it penetrates into a material placed in an isotropic neutron field. We have employed the theory of steady-state neutron transport, starting from Stuart's formula. Simple formulae were derived based on the integral cross-section parameters that could be adopted by the user according to various variables, such as the neutron flux distribution and geometry of the simulation at hand. The concluded formulae of the self-shielding factors comprise an inverted sigmoid function normalized with a weight representing the ratio between the macroscopic total and scattering cross-sections of the medium. The general convex volume geometries are reduced to a set of chord lengths, while the neutron interactions probabilities within the volume are parameterized to the epithermal and thermal neutron energies. The arguments of the inverted-sigmoid function were derived from a simplified version of neutron transport formulation. Accordingly, the obtained general formulae were successful in giving the values of the experimental neutron self-shielding factor for different elements and different geometries.Comment: 14 pages, 5 figures, 1 graphical abstract, 73 references, and 2 tables, include improvement of illustration and story-telling writing styl

Stimulated perturbation on the neutron flux distribution in the mutually-dependent source-to-absorber geometry

The complexity of the neutron transport phenomenon throws its shadows on every physical system wherever neutron is produced or absorbed. The Monte Carlo N-Particle Transport Code (MCNP) was used to investigate the flux perturbations in the neutron field caused by an absorber. The geometry of the present experiment was designed to reach a simulation of an isotopic neutron field. The neutron source was a ${}^{241}$AmBe with the production physics of neutrons is dependent only on alpha-beryllium interaction and is independent of what happened to the neutron after it was generated. The geometries have been designed to get a volume of uniform neutron densities within a spherical volume of radius 15 cm in every neutron energy group up to 10 MeV. Absorbers of different dimensions were placed within the volume to investigate the field perturbation. Different neutron absorbers were used to correlate the phenomenon to the integral cross-section of the absorber. Flux density inside and outside the absorber samples was determined, while the spatial neutron flux distribution produced by the AmBe source without an absorber was taken as a reference. This study displayed that absorbers of various dimensions perturb the neutron field in a way that is dependent on the absorption and scattering cross-sections, particularly in the neutron resonance region. Unlike the simple picture of reducing the number density of neutrons, the perturbation was found to influence the moderation of neutrons in the medium, significantly above 1 MeV.Comment: 10 pages, 13 figures, 26 reference

Anti-Saccharomyces cerevisiae antibodies and its relationship with radiological damage in ankylosing spondylitis

Aim The presence of anti-Saccharomyces cerevisiae antibodies (ASCA) is controversial in ankylosing spondylitis (AS). In this study, we aimed to investigate the prevalence of ASCA in AS and its relationship with disease activity and radiological damage in patients attending Sharkia governorate hospitals. Patients and methods Thirty AS patients and 30 apparently healthy volunteers were included in the present study. All patients were questioned for Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis metrology Index and Bath Ankylosing Functional Index (BASFI). Total Bath Ankylosing Spondylitis Radiology Index (BASRI-T) and ASCA levels were measured. Results ASCA IgA level was significantly higher in AS patients than in healthy controls (P < 0.001). The ASCA-positive group, although not significant, tended to have higher BASFI scores. ASCA IgA-positive patients had higher BASRI-T levels (P = 0.037). In AS patients, significant positive correlation was found between ASCA IgA level and BASRI-T and BASFI (r = 0.19 and 0.31, respectively, P < 0.05). Bath Ankylosing Spondylitis Disease Activity Index scores, BASFI and ASCA IgA positivity were significantly associated with increased BASRI-T (P= 0.01, 0.03 and 0.04, respectively). The most significant risk factor for increased BASRI-T is ASCA IgA positivity (P < 0.001). Conclusion ASCA IgA was detected more frequently in AS patients than in healthy controls. ASCA IgA could be considered a marker of severe radiological damage. Further studies are recommended to investigate ASCA level versus radiological damage and intestinal involvement in AS patients