saleh mohamed - Academia.edu (original) (raw)

Papers by saleh mohamed

Volume 8C: Heat Transfer and Thermal Engineering, 2013

A combined thermal power and ejector refrigeration cooling cycle is proposed in this paper to har... more A combined thermal power and ejector refrigeration cooling cycle is proposed in this paper to harness low-grade solar energy. It utilizes abundant and low-cost hydrocarbon as the working fluid. Hydrocarbon has been identified as a promising alternative to existing high global-warming-potential refrigerants (i.e., HFC refrigerant R134a) in next-generation refrigeration systems. Several typical alternative refrigerants are evaluated by considering their fundamental thermophysical properties: absolute pressure level, volumetric cooling capacity, surface tension, saturated liquid/vapor density ratio and kinematic viscosity. Comparing with R1234yf, R1234ze and R744 (CO2), hydrocarbon refrigerants, such as R290 (propane) and R601 (pentane), do have inherent advantages for either cooling or power generation purposes in hot climates: lower flow resistance and better heat transfer at higher temperature. Fundamental phase stability and transition issues have been considered in designing penta...

Ironworks constitute a great part of the world cultural heritage of metallic objects. Amongst the... more Ironworks constitute a great part of the world cultural heritage of metallic objects. Amongst these only a small part are on display in controlled environments. The rest is often exposed to uncontrolled atmospheres, high humidity and fluctuating temperatures and are usually heavily corroded. The aim of this study is to evaluate the efficiency of organic coating materials and corrosion inhibitors to protect ornamental cast ironwork from corrosion in uncontrolled environment using electrochemical techniques (Potentiodynamic polarization Tafel lines and electrochemical impedance (EIS)) and one year of exposure inside the clock tower of Muhammed Ali’s mosque in Salah El-Din Citadel in Cairo (natural ageing). Grey cast iron coupons were prepared to simulate the composition and morphology of the historic cast iron staircase, and treated with different protection systems. Four organic coatings have been studied; a methyl acrylate / ethyl methacrylate copolymer resin (ParaloidTM B-72) disso...

Volume 8C: Heat Transfer and Thermal Engineering, 2013

Bioscience, Biotechnology, and Biochemistry, 2016

The influence of solid state fermentation (SSF) by Trichoderma spp. on the solubility, total phen... more The influence of solid state fermentation (SSF) by Trichoderma spp. on the solubility, total phenolic content, antioxidant, and antibacterial activities of turmeric was determined and compared with unfermented turmeric. The solubility of turmeric was monitored by increase in its phenolic content. The total phenolic content of turmeric extracted by 80% methanol and water after SSF by six species of Trichoderma spp. increased significantly from 2.5 to 11.3–23.3 and from 0.5 to 13.5–20.4 GAE/g DW, respectively. The antioxidant activities of fermented turmeric were enhanced using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS), and ferric ion-reducing antioxidant power (FRAP) assays. The antibacterial activity of fermented turmeric against human-pathogenic bacteria Escherichia coli, Streptococcus agalactiae, Staphylococcus aureus, Entreococcus faecalis, Methicillin-Resistant S. aureus, Klebsiella pneumonia, and Pseudomonas aeruginosa...

Bioscience, Biotechnology, and Biochemistry, 2016

Process Biochemistry, 2011

An extracellular lipase LII from Mucor racemosus was purified by anion exchange and gel filtratio... more An extracellular lipase LII from Mucor racemosus was purified by anion exchange and gel filtration chromatography using DEAE-Sepharose and Sephacryl S-200 columns, respectively. A molecular weight of 20 kDa was estimated for M. racemosus LII by Sephacryl S-200 column and SDS-PAGE. LII had an acidic pI at 4.8. V max and K m for LII were estimated to be 55.5 mol oleic acid/min/ml and 2% olive oil, respectively. The highest lipolytic activity was detected with linseed oil as the substrate. The optimal pH and temperature for LII was 5.0 and 40 • C, respectively. The enzyme was stable up to 70 • C. The lipase activity was strongly enhanced by Cu 2+ , Al 3+ and Fe 3+ , and slightly enhanced by Mg 2+ , Ni 2+ and Mn 2+ , whereas Ca 2+ , Co 2+ , K + and Hg 2+ showed no effect. Pb 2+ only caused a partial inhibition of the enzyme. The residual lipase activity in carbopol 934 base gel was 385% after storage at 4 • C for 420 days. The characteristic properties of M. racemsus lipase formulated in the carbopol 934 gel was utilized for topical treatment of cellulite, and the results were positive for reducing thigh circumference.

Food Chemistry, 2011

An anionic peroxidase POIII, molecular weight 56 kDa, was purified from the roots of horseradish ... more An anionic peroxidase POIII, molecular weight 56 kDa, was purified from the roots of horseradish cv. Balady. The enzyme exhibited high activity towards o-phenylenediamine and guaiacol, while o-dianisidine had moderate peroxidase activity. Pyrogallol and p-aminoantipyrine had low affinity toward POIII. POIII was found to have a temperature optimum at 40°C; the enzyme activity remained stable up to 40°C and retained 87%, 51% and 29% of its activity at 50, 60 and 70°C, respectively. The enzyme exhibited more than 50% of activity in the pH range between 4.0 and 8.0 with its pH optimum at 5.5. Several metal cations had partial inhibitory effects toward POIII. Fe 3+ enhanced the activity of the enzyme by 160% at 5 mM. All the metal chelators caused partial inhibitory effects toward POIII, except for EDTA at 1 mM, which had no effect on the enzyme.

Experimental Parasitology, 2008

Ornithine aminotransferase (OAT), proline oxidase (PO), D 1-pyrroline-5-carboxylate reductase (P5... more Ornithine aminotransferase (OAT), proline oxidase (PO), D 1-pyrroline-5-carboxylate reductase (P5CR), and D 1-pyrroline-5-carboxylate dehydrogenase (P5CD) were assessed in Fasciola gigantica. All enzymes are involved in the conversion of ornithine into glutamate and proline. High levels of P5CD suggest that the direction of the metabolic flow from ornithine is more toward glutamate than proline. F. gigantica P5CD1 and P5CD2 were separated from the majority of contaminating proteins in crude homogenate using a CM-cellulose column. A Sephacryl S-200 column was employed for P5CD2 to obtain pure enzyme with increased specific activity. The molecular mass of P5CD2 was estimated to be 50 kDa using a Sephacryl S-200 column and SDS-PAGE. It migrated as a single band on SDS-PAGE, indicating a monomeric enzyme. P5CD2 had K m values of 1.44 mM and 0.37 mM for NAD and P5C, respectively. P5CD2 oxidized a number of aliphatic and aromatic aldehydes, where the aromatic compounds had higher affinity toward the enzyme. All amino acids examined had partial inhibitory effects on the enzyme. While 3 mM AMP caused 31% activation of enzyme, 3 mM ADP and ATP inhibited activity by 18% and 23%, respectively. Apart from Cu 2+ , the divalent cations that were studied caused partial inhibitory effects on the enzyme.

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2004

Esterase and lipase activity showed significant changes during embryogenesis of camel tick Hyalom... more Esterase and lipase activity showed significant changes during embryogenesis of camel tick Hyalomma dromedarii. From the elution profile of chromatography on DEAE-cellulose, six forms of H. dromedarii esterase (El to EVI) can be distinguished. Esterase EIII was purified to homogeneity after chromatography on Sepharose 6B. The molecular mass of esterase EIII was 45 kDa for the native enzyme and represented a monomer of 45 kDa by SDS-PAGE. Esterase EIII had an acidic pI at 5.3. Lipase activity was detected in the same DEAE-cellulose peaks (LI to LVI) of H. dromedarii esterases. The highest lipase activity was exhibited by lipase LIII. Esterase EIII and lipase LIII were compared with respect to Michaelis constant, substrate specificity, temperature optimum, heat stability, pH optimum, effect of metal ions and inhibitors. This study suggests that H. dromedarii lipolytic enzymes may play a central role in the interconversion of lipovitellins during embryogenesis.

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2005

Proteolytic activity of 0-12 day old eggs, miracidium and adult worm of Fasciola gigantica was as... more Proteolytic activity of 0-12 day old eggs, miracidium and adult worm of Fasciola gigantica was assessed and proteases were partially purified by DEAE-Sepharose and CM-cellulose columns. Four forms of protease were separated, PIa, PIb, PIc and PII. Purifications were completed for PIc and PII using Sephacryl S-200 chromatography. A number of natural and synthetic proteins were tested as substrates for F. gigantica PIc and PII. The two proteases had moderate activity levels toward azoalbumin and casein compared to azocasein, while gelatin, hemoglobin, albumin and fibrin had very low affinity toward the two enzymes. Amidolytic substrates are more specific to protease activity. PIc had higher affinity toward BAPNA-HCl (N-benzoyl-arginine-p-nitroanilide-HCl) and BTPNA-HCl (N-benzoyl-tyrosine-pnitroanilide-HCl) at pH 8.0 indicating that the enzyme was a serine protease. However, PII had higher affinity toward BAPNA at pH 6.5 in the presence of sulfhydryl groups (h-mercaptoethanol) indicating that the enzyme was a cysteine protease. The effect of specific protease inhibitors on these enzymes was studied. The results confirmed that proteases PIc and PII could be serine and cysteine proteases, respectively. The molecular weights of F. gigantica PIc and PII were 60,000 and 25,000, respectively. F. gigantica PIc and PII had pH optima at 7.5 and 5.5 and K M of 2 and 5 mg azocasein/mL, respectively. For amidolytic substrates, PIc had K M of 0.3 mM BAPNA/mL and 0.5 mM BTPNA/ mL at pH 8.0 and PII had K M of 0.6 mM BAPNA/mL at pH 6.5 with reducing agent. F. gigantica PIc and PII had the same optimum temperature at 50-C and were stable up to 40-C. All examined metal cations tested had inhibitory effects toward the two enzymes. From substrate specificity and protease inhibitor studies, PIc and PII could be designated as serine PIc and cysteine PII, respectively.

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2005

The present study analyzed the existence of carbohydrases in camel pancreas compared to some othe... more The present study analyzed the existence of carbohydrases in camel pancreas compared to some other ruminants. Disaccharidases (maltase, cellobiase, lactase, trehalase and sucrase), glucoamylase and alpha-amylase were detected in pancreas of camel, sheep, cow and buffalo. Enzyme levels in sheep were lower than in the other ruminants. The highest level was detected for alpha-amylase (EC 3.2.1.2). Moderate activity levels were detected for glucoamylase (EC 3.2.1.3) and maltase (EC 3.2.1.20), while other disaccharidases showed very low activity. The results suggested that, in addition to alpha-amylase, glucoamylase and maltase may be synthesized and secreted from pancreas to the small intestine in ruminants. Camel pancreatic glucoamylase was purified and characterized. The purification procedure included glycogen precipitation and chromatography on DEAE-Sepharose and Sepharose 6B. The molecular mass was 58 kDa for native and denatured enzyme using gel filtration and SDS-PAGE, respectively. The enzyme had a pH optimum at 5.5 and a Km of 10 mg starch/mL with more affinity toward potato soluble starch than the other carbohydrates. Glucoamylase had a temperature optimum at 50 degrees C with heat stability up to 30 degrees C. The effect of different cations and inhibitors was examined. The camel pancreatic glucoamylase may possess an essential thiol.

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 1997

The activity of P5C metabolizing enzymes: OAT, P5CR, PO, and P5CD, in the camel tick Hyalomma dro... more The activity of P5C metabolizing enzymes: OAT, P5CR, PO, and P5CD, in the camel tick Hyalomma dromedarii has been followed throughout embryogenesis. The profiles of enzymatic activity showed clear differences in the four enzymes as the embryos grew older. During purification of P5CD to homogeneity the ion exchange chromatography steps lead to two separate forms (termed A and B) with

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2005

The ornithine-urea cycle has been investigated in Fasciola gigantica. Agrinase had very high acti... more The ornithine-urea cycle has been investigated in Fasciola gigantica. Agrinase had very high activity compared to the other enzymes. Carbamoyl phosphate synthetase and ornithine carbamoyltransferase had very low activity. A moderate enzymatic activity was recorded for argininosuccinate synthetase and argininosuccinate lyase. The low levels of F. gigantica urea cycle enzymes except to the arginase suggest the urea cycle is operative but its role is of a minor important. The high level of arginase activity may benefit for the hydrolysis of the exogenous arginine to ornithine and urea. Two arginases Arg I and Arg II were separated by DEAE-Sepharose column. Further purification was restricted to Arg II with highest activity. The molecular weight of Arg II, as determined by gel filtration and SDS-PAGE, was 92,000. The enzyme was capable to hydrolyze l-arginine and to less extent l-canavanine at arginase : canavanase ratio (> 10). The enzyme exhibited a maximal activity at pH 9.5 and K m of 6 mM. The optimum temperature of F. gigantica Arg II was 40-C and the enzyme was stable up to 30-C and retained 80% of its activity after incubation at 40-C for 15 min and lost all of its activity at 50-C. The order of effectiveness of amino acids as inhibitors of enzyme was found to be lysine > isoleucine > ornithine > valine > leucine > proline with 67%, 43%, 31%, 25%, 23% and 15% inhibition, respectively. The enzyme was activated with Mn 2+ , where the other metals Fe 2+ , Ca 2+ , Hg 2+ , Ni 2+ , Co 2+ and Mg 2+ had inhibitory effects.

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2007

Disaccharidases (maltase, cellobiase, lactase, and sucrase), alpha-amylase, and glucoamylase in t... more Disaccharidases (maltase, cellobiase, lactase, and sucrase), alpha-amylase, and glucoamylase in the camel small intestine were investigated to integrate the enzymatic digestion profile in camel. High activities were detected for maltase and glucoamylase, followed by moderate levels of sucrase and alpha-amylase. Very low activity levels were detected for lactase and cellobiase. Camel intestinal maltase-glucoamylase (MG) was purified by DEAE-Sepharose and Sephacryl S-200 columns. The molecular weight of camel small intestinal MG4 and MG6 were estimated to be 140,000 and 180,000 using Sephacryl S-200. These values were confirmed by SDS-PAGE, where the two enzymes migrated as single subunits. This study encompassed characterization of MGs from camel intestine. The Km values of MG4 and MG6 were estimated to be 13.3 mM and 20 mM maltose, respectively. Substrate specificity for MG4 and MG6 indicated that the two enzymes are maltase-glucoamylases because they catalysed the hydrolysis of maltose and starch with alpha-1,4 and alpha-1,6 glycosidic bonds, but not sucrose with alpha-1,2 glycosidic bond which was hydrolyzed by sucrase-isomaltase. Camel intestinal MG4 and MG6 had the same optimum pH at 7.0 and temperature optimum at 50 degrees C and 40 degrees C, respectively. The two enzymes were stable up to 50 degrees C and 40 degrees C, followed by strong decrease in activity at 60 degrees C and 50 degrees C, respectively. The effect of divalent cations on the activity of camel intestinal MG4 and MG6 was studied. All the examined divalent cations Ca(2+), Mn(2+), Mg(2+), Co(2+) and Fe(3+) had slight effects on the two enzymes except Hg(2+) which had a strong inhibitory effect. The effect of different inhibitors on MG4 and MG6 indicated that the two enzymes had a cysteine residue.

Chemical and Pharmaceutical Bulletin, 1986

Carbohydrate Research, 2003

A polygalacturonase (PGase) was purified from Trichoderma harzianum, grown on citrus peel, by ani... more A polygalacturonase (PGase) was purified from Trichoderma harzianum, grown on citrus peel, by anion exchange and size exclusion chromatographies. The enzyme had molecular mass of 29 kDa. The extent of hydrolysis by PGase was decreased with increasing of pectin esterification degree. m m a x K and V , using polygalacturonic acid as substrate, were 1.42 mg and 0.66 ìmol reducing sugar, respectively. PGase had a broad pH optimum ranged from 4.5 to 7.0 and temperature optimum at 55<C. PGase was stable up to 50°C after incubation for 30 min. All the examined metal cations showed partial inhibitory effects, except for Hg which was completely inhibited the enzyme activity. 2+ The effect of PGase and wheat á-amylase on apple juice was studied, where the mixture of the two enzymes increased the quantity (135% fold) and clarity degree of apple juice.

Bioresource Technology, 1999

Urease, in liquid and powder forms, with a purity meeting the requirements of diagnostic use, wer... more Urease, in liquid and powder forms, with a purity meeting the requirements of diagnostic use, were partially purified from water melon Citrullus vulgaris cv. &amp;#x27;Giza 1&amp;#x27; seeds through a simple reproducible method consisting of delipidation, extraction, batch adsorption on TEAE-...

Volume 8C: Heat Transfer and Thermal Engineering, 2013

Bioscience, Biotechnology, and Biochemistry, 2016

Process Biochemistry, 2011

Food Chemistry, 2011

Experimental Parasitology, 2008

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2004

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2005

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 1997

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2005

Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2007

Chemical and Pharmaceutical Bulletin, 1986

Carbohydrate Research, 2003

Bioresource Technology, 1999