Mohamed Tarek Mohamed Zaki

Metal chelates of phosphonate-containing ligands-V Stability of some 1-hydroxyethane-1,1-diphosphonic acid metal chelates.

A detailed study of the complexes formed between 1-hydroxyethane-1,1-diphosphonic acid and twelve metal ions, including the alkaline earth and transition non-transition metal ions, is reported. The formation constants of the protonated and unprotonated complexes are measured from potentiometric data and possible structural formulae are given. The results reveal that only mononuclear (1:1) di-, mono- and unprotonated metal chelates are formed and that the general order of stability for the unprotonated complexes is Zn > Mn > Ca > Cu > Cd > Pd > Ni > Co reverse similar Sr > Mg > Ag > Ba.

Aspects of Assessment and Management of Velopharyngeal Dysfunction in Developing Countries

Proper assessment of patients with velopharyngeal valve incompetence is a mandatory prerequisite for optimal management. The protocol of assessment of Ain Shams University, Phoniatric Department, uses three levels of assessment of velopharyngeal valve incompetence according to the complexity of the armamentarium used. This allows application of those parts of the protocol that suit the needs of the different socioeconomic levels and geographical locations. Firstly, the elementary diagnostic procedures, which are rather simple, noninvasive, but essentially subjective. Despite the clinical feasibility of these procedures, documentation of the data is made utilizing the tools at the second level of assessment in that protocol (clinical diagnostic aids). This level comprises video-nasofiberscopy and high fidelity voice recording. An attempt to extract quasi-quantitative measures from the hitherto qualitative video-nasofiberscopy is made. The third level of assessment, namely additional instrumental measures, comprises CT scanning of the velopharyngeal port, aerodynamics, and acoustic analysis. The results of the three levels of the protocol are presented. Their significance and clinical efficacy are discussed. Some community-related problems that have faced the cleft palate team are outlined. Their sociocultural significance in a developing country is discussed.

Extraction-spectrophotometric determination of iron(II) by ternary complex formation with pyrocatechol violet and cetyltrimethylammonium bromide

A method for iron(II) determination based on reaction with Pyrocatechol Violet to form a 1:2 binary complex at pH 5-7 is described and has been extended to an extraction-spectrophotometric procedure for the determination of iron(II) by formation of the 1:2:2 iron(II)-Pyrocatechol Violet-cetyltrimethylammonium bromide ternary complex. The molar absorptivities of the binary and ternary complexes at 595 and 605 nm are 6.55 x 10(4) and 1.35 x 10(5)1.mole(-1).cm(-1), respectively. The method has been successfully applied to the determination of iron in felspar, Portland cement and sodium hydroxide.

Use of quercetin in an improved method for molybdenum determination in waste water, silicate rocks and diverse alloys

A simple and highly sensitive spectrophotometric method for molybdenum (VI) determination has been developed. The method is based on solubilizing the binary molybdenum-quercetin complex and sensitizing the color reaction with cetyltrimethylammonium bromide (CTAB). The optimal conditions for the quantitative determination of molybdenum are studied. In KCl-HCl buffered medium of pH 2.3, the molar absorptivity of the 1∶2∶2 (Moquercetin-CTAB) ternary complex is 2.03 × 105 1 · mol−1 · cm−1 at 420 nm. The system obeys Beers law up to 0.30 νg/ml of molybdenum and the sensitivity index is 0.47 ng · cm−2. The method is free of interference of most of the common metal ions and anions. The developed procedure has been successfully applied to molybdenum determination in waste water, silicate rocks and diverse alloys.

Potentiometric determination of silver(I), palladium(II) and gold(III) in mixtures by use of an iodide-selective electrode

Two procedures are proposed for the potentiometric determination of Ag(I), Pd(II) and Au(III) in binary mixtures, by titration with potassium iodide solution, and use of a commercial iodide electrode as sensor. In the first procedure, two aliquots of the mixture are titrated, at pH 2.0 ± 0.2 and 9.0 ± 0.2, adjusted with dilute sulphuric acid and ammonia solution. At pH 2.0, the titrant reacts with both metals, whereas at pH 9.0, Ag(I) is the only reactant. The second procedure utilizes titration of two aliquots of the mixture in the presence and absence of a selective masking agent. The methods have been applied to the determination of these metals in some jewellery alloys.

Determination of penicillins by desulphurization with lead and edta titration

A new, simple, accurate and rapid method is described for the determination of total penicillins in pharmaceutical preparations. The method is based on desulphurization with potassium plumbite whereby one mole of lead sulphide is formed per mole of penicillin. The excess of lead ions is titrated with EDTA at pH 4.5, with use of the lead ion-selective electrode. Results are reproducible within +/- 0.5% and compare favourably with those obtained by the procedures of the United States and British Pharmacopoeias.

Spectrophotometric determination of molybdenum with 7,8-dihydroxy-4-methylcoumarin and cetyltrimethylammonium bromide.

The 1:2 complexes formed between molybdenum and 7,8-dihydroxy-4-methylcoumarin in the presence and absence of cetyltrimethylammonium bromide (CTAB) have been studied. The binary complex formed at pH 5.6-6.0 in the absence of CTAB exhibits an absortion maximum at 360 nm with a molar absorptivity of 5.1 x 10(4) 1.mole(-1).cm(-1). The complex formed at pH 4.8-6.0 in the presence of CTAB has a molar absorptivity of 1.32 x 10(5) 1.mole(-1).cm (-1) at 400 nm, the wavelength of maximum absorption. Optimum conditions for complex formation were investigated and a rapid, sensitive and relatively selective method for the determination of up to approximately 70% of Mo in diverse alloys and steels is described. Small amounts of zirconium and tungsten interfere.

Secondary aortoduodenal fistula following endovascular repair of inflammatory abdominal aortic aneurysm due to Streptococcus anginosus infection: A case report and literature review☆

INTRODUCTION Aortoenteric fistula is a rare but very serious complication of both surgical and endovascular abdominal aortic reconstruction. Since the advent of endovascular abdominal aortic aneurysm repair (EVAR), 20 cases of aortoduodenal fistula associated with aortic stent grafts have been reported.1 However, only a handful has been reported following inflammatory abdominal aortic aneurysm repair. It most commonly presents with bleeding, usually from the upper gastro-intestinal tract. With recent advances in the screening, diagnosis and management of abdominal aortic aneurysms either surgically or through an endovascular approach, the diagnosis of an aortoduodenal fistula in patients with gastro-intestinal bleeding must be suspected and excluded. PRESENTATION OF CASE We describe a case of secondary aortoduodenal fistula that occurred two and a half years following endovascular stent graft repair of an inflammatory abdominal aortic aneurysm. We also outline the emergency correction plan and the attempts at repair. DISCUSSION This case defies the general concept that patients with inflammatory abdominal aortic aneurysms are relatively immune to rupture. Although the presence of a peri-aneurysm thick inflammatory membrane decreases the possibility of rupture, these patients are more susceptible to other related complications such as aorto-enteric and aorto-caval fistulas.2 This case also demonstrates the peculiar presence of Streptococcus anginosus as the pathological organism leading to graft infection and subsequent fistula, as opposed to enterococci which are often found in endograft infection. CONCLUSION Aorto-enteric fistulas are associated with a grave prognosis. Early diagnosis is crucial and extra vigilance should be taken in cases of inflammatory AAA.

Spectrophotometric determination of iron as phenylfluorone complex sensitized with Triton X-100

SummaryThe effect of some surfactants and protective colloids on the absorbance of the iron(III)-phenylfluorone complex has been investigated. The binary complex formed at pH 9.0 show a molar absorptivity of 7.5×104 l · mol−1 · cm−1 at 530 nm. In the presence of 2% Triton X-100, at the same pH, the molar absorptivity of the sensitized complex was 1.19×105 l · mo−1 · cm−1 at 555 nm. Full colour development of the sensitized complex occurred within 25 min and Beers law was followed up to 0.53 ppm of iron. The molar ratio and continuous variation methods indicated a 1∶3 metal-ligand ratio for the sensitized complex. The effect of various amounts of different ions has been studied under the experimental conditions and some masking agents were recommended. The method has been applied to the determination of iron in copper and nickel metals and some non-ferrous alloys.

Bioconversion of sugarcane bagasse into a protein-rich product by white rot fungus

Abstract The fungus Pleurotus ostreatus NRRL-2366 degraded 56.7% and 45.9% of untreated and chemically pretreated (delignified) sugarcane bagasse, respectively, during 14-day incubation in a submerged fermentation process. The biodegradation percentages of cellulose, hemicellulose and lignin were 33.0%, 72.5% and 14.5%, respectively. An increment of 22.6% of crude protein content in the residual fermented material was observed. Chemical composition of the end-product and its amino acids profile were reported.