Nabil Saad

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Diffuse neonatal haemangiomatosis: Successful management with high dose corticosteroids

European Journal of Pediatrics, 1990

We report two cases of diffuse neonatal haemangiomatosis. The multiple cutaneous lesions were ass... more We report two cases of diffuse neonatal haemangiomatosis. The multiple cutaneous lesions were associated with massive hepatic involvement and congestive heart failure in one, while in the other laryngeal haemangiomas caused stridor and inspiratory distress. A significant regression in vascular lesions was achieved with high dose corticosteroid therapy.

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A Study of Circulation, Water Masses and Mixing Processes in the Southeastern Mediterranean off the Egyptian Coast During Autumn

Journal of King Abdulaziz University-Marine Sciences, 1999

A total of 34 stations were sampled in the Egyptian Mediterranean continental shelf during autumn... more A total of 34 stations were sampled in the Egyptian Mediterranean continental shelf during autumn 1994. A sharp thermocline of about a quarter of a celsius degree per meter in a layer of about 50 m depth was formed. Correspondingly, a sharp pycnocline layer is found and acts as a barrier to vertical mixing and greatly allows for horizontal mixing. The average current speed of this area was about 30 cm/sec and it was mainly wind driven current at the surface. The Nile Delta Convergence Zone (NDCZ) covers a great area in front of the Nile Delta. This cyclonic gyre was detected earlier during summer season.

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Seasonal Variation of Geostrophic Current and Water Transport in the Central Part of The Red Sea

Journal of King Abdulaziz University-Marine Sciences, 1999

... NABIL N. SAAD, EBTESSAM E. MOHAMED and SAMY M. EL-NADY National Institute of Oceanography and... more

Evaluation of Some Dynamical Parameters at the Central Red Sea during Early Summer

Journal of King Abdulaziz University-Marine Sciences, 2010

The horizontal circulation pattern of the Red Sea shows that the maximum turbulent mixing zone is... more The horizontal circulation pattern of the Red Sea shows that the maximum turbulent mixing zone is in the central area. The dynamical computation of the turbulent vertical mixing parameters: Richardson Number (Ri), Reynolds Stress (J m) and Diffusive Salt Flux (J s) have been carried out at the central area of the Red Sea. The Ri values show the occurrence of dynamical stability with magnitude greater than 1/4 along the three selected stations. The Reynolds stress results show an upward vertical flux at station II between surface and 40m and near surface at station III. The maximum value of upward momentum flux is-4.71 x 10-3 Pa. The distribution pattern of J s is analogous to that of K s as both distributions reveal that the magnitude of these two mixing parameters decreases relatively with depth.

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Application of a Mathematical Model for Estimating the Pattern of Pollution Dispersion at the Coast of Alexandria

Journal of King Abdulaziz University-Marine Sciences, 2007

... EE Mohamed, El-Sayed M. El-sayed*, Nabil N. Saad, and Hassan A. Abou Tahoun Marine Physics ..... more

Highly efficient monolithic silica capillary columns modified with poly(acrylic acid) for hydrophilic interaction chromatography

Journal of Chromatography A, 2007

Monolithic silica capillary columns for hydrophilic interaction liquid chromatography (HILIC) wer... more Monolithic silica capillary columns for hydrophilic interaction liquid chromatography (HILIC) were prepared by on-column polymerization of acrylic acid on monolithic silica in a fused silica capillary modified with anchor groups. The products maintained the high permeability (K = 5 × 10 −14 m 2) and provided a plate height (H) of less than 10 m at optimum linear velocity (u) and H below 20 m at u = 6 mm/s for polar solutes including nucleosides and carbohydrates. The HILIC mode monolithic silica capillary column was able to produce 10 000 theoretical plates (N) with column dead time (t 0) of 20 s at a pressure drop of 20 MPa or lower. The total performance was much higher than conventional particle-packed HILIC columns currently available. The gradient separations of peptides by a capillary LC-electrospray mass spectrometry system resulted in very different retention selectivity between reversed-phase mode separations and the HILIC mode separations with a peak capacity of ca. 100 in a 10 min gradient time in either mode. The high performance observed with the monolithic silica capillary column modified with poly(acrylic acid) suggests that the HILIC mode can be an alternative to the reversed-phase mode for a wide range of compounds, especially for those of high polarity in isocratic as well as gradient elution.

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Calculating Optimal Modulation Periods to Maximize the Peak Capacity in Two-Dimensional HPLC

Analytical Chemistry, 2007

Theoretical calculations are presented to optimize modulation period for maximum total peak capac... more Theoretical calculations are presented to optimize modulation period for maximum total peak capacity in comprehensive two-dimensional HPLC (2D-HPLC) taking into account the effect of modulation on the apparent peak capacity of the first-dimension (1 D) separation. Results indicate that modulation periods are most favorable when they are adjusted to ∼2.2-4 times the standard deviation of a 1 D peak in order to avoid excessively short run times at the second dimension (2 D). Data are presented that effective peak capacities of several thousand in 60 min can be expected for practical 2D-HPLC conditions, utilizing 1 D gradient elution followed by 2 D isocratic elution, that remain at ∼50-70% of the theoretical maximum peak capacity. This work suggests that lower modulation frequencies and longer 2 D separation times than previously proposed are favorable under realistic chromatographic conditions, alleviating some practical problems associated with 2D-HPLC. Separation of complex mixtures consisting of thousands of components remains a challenge for liquid chromatography. Recent advances in high-speed separations such as use of ultrahigh-pressure liquid chromatography 1-5 or monolithic silica columns 6,7 considerably increased peak capacities of one-dimensional HPLC separations compared to more conventional HPLC methods. Today, peak capacities of 350 or greater can be achieved when long columns and extended gradient run times are employed. 7 The next logical step is to combine peak capacities of two different HPLC separations that are based on largely distinct

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Highly efficient analysis of underivatized carbohydrates using monolithic-silica-based capillary hydrophilic interaction (HILIC) HPLC

Analytical and Bioanalytical Chemistry, 2008

A polyacrylamide (PAAm)-modified monolithic silica capillary column of increased phase ratio, 200... more A polyacrylamide (PAAm)-modified monolithic silica capillary column of increased phase ratio, 200T-PAAm, for hydrophilic interaction liquid chromatography (HILIC) was prepared. The column showed high separation efficiency, with a theoretical plate height H=7-20 μm at a linear velocity, u=1-7 mm/s. From a kinetic plot analysis, it was expected that the monolithic column could provide three times faster separation than particle-packed HILIC columns under a pressure limit at 20 MPa. HILIC coupled with electrospray ionization (ESI)-mass spectrometry (HILIC-ESI-MS) using the 200T-PAAm column was employed for the analysis of underivatized carbohydrates to achieve fast and efficient separations of mixtures containing mono-, di-, and trisaccharides within 5 min. Under single MS full scan mode, 200 pg of oligosaccharides was detected by the system. The limit of detection (LOD) of the LC-ESI-MS/MS system was determined using selected reaction monitoring (SRM) to be as low as 3.2 ng/mL (attomol level) for nonreducing saccharides. The system was successfully applied to the detection of disaccharides in extracts of plant, such as corn, soybean, and Arabidopsis thaliana.

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Nabil Saad

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