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Improvement in antibacterialproperties of Ti byelectrodeposition of biomimetic Ca-P apatite coat on anodized titania

Research Abstract
Titanium metal (Ti) with antibacterial function was successfully developed in the present study by electrodeposition of biomimetic Ca-P coat in simple supersaturated calcium and phosphate solution (SCPS).The electrochemical behavior and corrosion resistance of Ca-P deposited on anodized titanium (AT) has been investigated in SCPS by using electrochemical impedance spectroscopy (EIS). The plate-counting method was used to evaluate the antibacterial performance against Staphylococcus aureus (ATCC6538). In vitro antibacterial activity study indicated a significantly reduced number of bacteria S- aureus on Ca-P/AT plate surface when compared with that on Ti or AT surfaces and the corresponding antibacterial mechanism is discussed. The morphology and chemical structure of different titanium samples were systematically investigated by scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX). The study confirmed that the antibacterialproperties of the samples were related to chemical composition of sample surface.
Research Authors
Sanaa M.F. Gad El-Rab , Sahar A. Fadl-allaha , A.A. Montser
Research Journal
Applied Surface Science
Research Website
http://www.sciencedirect.com/science/article/pii/S0169433212009981
Research Year
2012

DIAGENETIC BEHAVIOR OF BIOGENIC SULFIDES AROUND THE K/T BOUNDARY IN DAKHLA SHALE AT GABAL GIFATA, DAKHLA OASIS, EGYPT

Research Abstract
The study aims to present new information and illustrations about sulfidic sedimentary rocks in order to provide a better understanding of how the sulfide minerals might have been formed. It also presents detailed information on the major and trace element contents of various sulfide phases hosted within the sediments. The K/T sediments at Gabal Gifata (Weina and Birbaya sections), hold different morphologic patterns of sulfides including tubular burrow fills, flat sulfidic thin bands and films, fossil replacement and fills, as well as disseminated grains and framboids. The sulfide minerals are composed of pyrite, sphalerite and galena with minor greenockite set in a groundmass composed of gypsum and clays with celestite. These sulfide minerals are believed to have originated in reduced bottom-water conditions via sulfate reducing bacteria after rapid burial of organic matter. The sulfide minerals seam to develop through successive stages by segregation, filling and replacement processes in early and intermediate diagenesis. The framboidal pyrite and its associations of fine pyrite crystals were formed in early diagenesis by rapid growth. The sulfide minerals are arranged within the burrow fills in concentric shells. The outer shells are composed of pyrite while the cores are composed mostly of large sphalerite and in some cases with galena. The grain size and crystallinity of the mineral crystals increase inwards through the shells suggesting progressive formation of the sulfides from the margins to the centers. The minerals were crystallized in a sequence: pyrite, sphalerite-galena in early (pyrite) and intermediate (sphalerite-galena) diagenetic stages. The sulfidic thin bands are composed mostly of pyrite with subordinate sphalerite. The preservation of biogenic cells by pyrite within these bands and the survival of pyrite within sphalerite suggest earlier formation of pyrite by replacement of organic matter (in early diagenesis) followed by sphalerite through cavity filling (in intermediate diagenesis). The microprobe analyses of sulfides showed that the pyrite, which occurs close to the sphalerite, displays much higher concentrations of the trace elements Zn and Ni than the pyrite in the outer shells. Distinct chemical differences exist among the different colors of sphalerite. Several observations suggest that benthic conditions during the deposition of black shales were sufficiently O2-depleted as to exclude benthic organisms (anoxic/euxinic), and that a possibly sharp rise in dissolved O2 levels coincided with the onset of the overlying sediments deposition, crossing a critical threshold to dysoxic levels that allowed benthic rise.
Research Authors
Mamdouh F. Soliman
Research Department
Research Journal
THE FIFTH INTERNATIONAL CONFERENCE ON THE GEOLOGY OF AFRICA
Research Member
Research Vol
1
Research Year
2007

UPPER DAKHLA FORMATION ( BEIDA SHALE MEMBER) AT G. DUWI, RED SEA, EGYPT: MINERALOGICAL AND GEOCHEMICAL ASPECTS

Research Abstract
This study deals wi th the mineralogy and geochemistry of the mineralogical phases found in the Beida Shale Member belonging to the Dakhla Formation and exposed at G. Duwi section, Red Sea, Egypt. The sediments of the upper Dakhla Formation (85 m thick) are composed mainly of grey, dark greyto black shales as well as grey marly shales and pink marl. These sediments are intercalated by many thin layers (30-50 cm thick) of brown and reddish brown marl. The marl and marly shale are slightly to moderately dolomitic. The stereoscopic microscopy and the SEM survey of the insoluble residues of these sediments have revealed the presence of Mn-oxides (mainly manganite), dolomite, goethite pseudomorphs (after pyrite and pyrite framboids), goethite, few Fe-Ti oxides and organic carbon particles. The mineralogical and geochemical investigations indicate that the manganese oxides, dolomite, goethite and goethite pseudomorphs are of diagenetic origin. However, the Fe-Ti oxides are of detrital origin. These mineralogical contents suggest that the Beida Shale Member is a normal marine sediment deposited in oxygen- containing bottom waters, except for the middle part which is composed of dark grey shale and contains pyrite and pyrite framboids. This part reflects an euxinic marine environment and deposition in anoxic, H2S- containing bottom water. X-ray diffraction analysis of the clay fraction revealed that the sediments under investigation are composed of detrital kaolinite, smectite and illite. The fluctuation in frequencies of these minerals within the sediments indicates a warm / humid climate with high rain falls at the K/T boundary and during the Danian periods as indicated by the abundance of kaolinite. This is followed by a temperate or cool and dry climatic conditions during the Selandian-lowermost Thanetian and a sea level rise in the early Thanetian as indicated by the low kaolinite content and the relative abundance of smectite.
Research Authors
Mamdouh F. Soliman and Mahmoud A. Essa
Research Department
Research Journal
THE THIRD INTERNATIONAL CONFERENCE ON THE GEOLOGY OF AFRICA
Research Member
Research Pages
283-305
Research Vol
2
Research Year
2003

Framboidal and idiomorphic pyrite in the upper Maastrichtian sedimentary rocks at Gabal Oweina, Nile Valley, Egypt: Formation processes, oxidation products and genetic implications to the origin of framboidal pyrite

Research Abstract
The upper Maastrichtian organic-rich sediments studied at Gabal Oweina, Egypt, are moderately enriched in syngenetic and diagenetic pyrite. Pyrite occurs mostly as layers or bands, group of lamina, lenses, diagenetic intercalated pockets, burrow fills and disseminated individual pyrite framboids and crystals within the host sediments. The pyritic thin bands and lamina consist mostly of unconsolidated to compact-oriented pyrite (oriented along the bedding planes) in gypsiferous–clayey matrix and less common as poorly oriented pyrite crystallites. In several cases, pyrite crystals of the latter type depict zoning, fracturing and micro-concretions. Pyritic burrow fills are composed mainly of pyrite, phosphatic ooids, microfossils, glauconitic grains, poorly graphitized carbon and native sulfur. Pyrite replaces minerals other than gypsum, sulfur or carbon. It also replaces microfossils thus turning some of the phosphatic ooids and microfossils to pyritized pseudomorphs. None of the studied phosphate ooids or framboids contains any mackinawite, pyrrhotite or greigite. Based on the microscopic and SEM observations of the micro-textures of disseminated pyrite found at Gabal Oweina section, four morphological forms of primary pyrite could be identified: (1) Grouped multiple-framboids; (2) Individual framboids; (3) Pyrite idiomorphic crystal overgrowths on framboids and (4) Single and aggregates of euhedral pyrite crystals. The multiple-framboid formation may have emerged from three successive processes: nucleation and growth of individual aggregates of the microcrystals to form combined micro-framboids (the growth of framboids); and followed by grouping of the several pyrite framboids. Direct pyrite nucleation (shell formation), crystallization, and aggregation processes might complete a single framboid. The disseminated single and aggregated euhedral pyrite crystals bear evidence indicating that their formation was via nucleation and growth of pyrite crystallites and their aggregation (to individual framboids), infilling (in the interstices by additional pyritic material), compaction and homogenization (of all these materials). Furthermore, we encounter for the first time in nature idiomorphic pyrite crystals that integrated numerous framboids, using them as their nucleation and growth sites without erasing or modifying their pristine morphology. Elemental sulfur contains minor concentration of Sb, Ni, Cd and Cu strongly suggesting their presence as submicron sulfide crystallite inclusions. SEM and microprobe investigations revealed that goethite is present as a weathering product in all morphological types of pyrite however; only an iron-sulfate (presumably melanterite) was encountered as oxidation product of the multi-framboids and the euhedral aggregate crystals. The upper Maastrichtian sediments not only contain a menagerie of pyrite morphologies but probably a complete record of the formation process and the geochemical conditions of the growth of framboids, single pyrite crystals, pyrite burrows, pyritized Mn–Fe-oxide framboids and finally their weathered products. The various pyrite forms strongly suggest a multistage process that led to their formation without any evidence for mackinawite, pyrrhotite or greigite, precursors. There is also no evidence in the Oweina sediments for post pyrite formation of mackinawite, pyrrhotite or greigite. The presence of elemental sulfur containing minor
Research Authors
Mamdouh F. Soliman , Ahmed El Goresy
Research Department
Research Journal
Geochimica et Cosmochimica Acta
Research Member
Research Pages
195-220
Research Vol
90
Research Year
2012

16S rRNA gene sequences analysis of Ficus elastica rubber latex degrading thermophilic Bacillus strain ASU7 isolated from Egypt.

Research Abstract
A thermophilic Bacillus strain ASU7 was isolated from soil sample collected from Assiut governorate in Upper Egypt on latex rubber-containing medium at 45 °C. Genetically, the 16S bacterial ribosomal RNA gene of the strain ASU7 was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the GenBank database. Based on phylogenetic analyses, strain ASU7 was identified as Bacillus amyloliquefaciens. The strain was able to utilize Ficus elastica rubber latex as a sole source for carbon and energy. The ability for degradation was determined by measuring the increase in protein content of bacterium (mg/g dry wt), reduction in molecular weight (g/mol), and inherent viscosity (dl/g) of the latex. Moreover, the degradation was also confirmed by observing the growth of bacterium and formation of aldehyde or keto group using scanning electron microscopy (SEM) and shiff's reagent, respectively.
Research Authors
Hesham AE, Mohamed NH, Ismail MA, Shoreit AA.
Research Journal
Biodegradation
Research Website
http://www.ncbi.nlm.nih.gov/pubmed/22453659
Research Year
2012

16S rRNA gene sequences analysis of Ficus elastica rubber latex degrading thermophilic Bacillus strain ASU7 isolated from Egypt.

Research Abstract
A thermophilic Bacillus strain ASU7 was isolated from soil sample collected from Assiut governorate in Upper Egypt on latex rubber-containing medium at 45 °C. Genetically, the 16S bacterial ribosomal RNA gene of the strain ASU7 was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the GenBank database. Based on phylogenetic analyses, strain ASU7 was identified as Bacillus amyloliquefaciens. The strain was able to utilize Ficus elastica rubber latex as a sole source for carbon and energy. The ability for degradation was determined by measuring the increase in protein content of bacterium (mg/g dry wt), reduction in molecular weight (g/mol), and inherent viscosity (dl/g) of the latex. Moreover, the degradation was also confirmed by observing the growth of bacterium and formation of aldehyde or keto group using scanning electron microscopy (SEM) and shiff's reagent, respectively.
Research Authors
Hesham AE, Mohamed NH, Ismail MA, Shoreit AA.
Research Journal
Biodegradation
Research Website
http://www.ncbi.nlm.nih.gov/pubmed/22453659
Research Year
2012

16S rRNA gene sequences analysis of Ficus elastica rubber latex degrading thermophilic Bacillus strain ASU7 isolated from Egypt.

Research Abstract
A thermophilic Bacillus strain ASU7 was isolated from soil sample collected from Assiut governorate in Upper Egypt on latex rubber-containing medium at 45 °C. Genetically, the 16S bacterial ribosomal RNA gene of the strain ASU7 was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the GenBank database. Based on phylogenetic analyses, strain ASU7 was identified as Bacillus amyloliquefaciens. The strain was able to utilize Ficus elastica rubber latex as a sole source for carbon and energy. The ability for degradation was determined by measuring the increase in protein content of bacterium (mg/g dry wt), reduction in molecular weight (g/mol), and inherent viscosity (dl/g) of the latex. Moreover, the degradation was also confirmed by observing the growth of bacterium and formation of aldehyde or keto group using scanning electron microscopy (SEM) and shiff's reagent, respectively.
Research Authors
Hesham AE, Mohamed NH, Ismail MA, Shoreit AA.
Research Journal
Biodegradation
Research Website
http://www.ncbi.nlm.nih.gov/pubmed/22453659
Research Year
2012

2-Benzoyloxycinnamaldehyde-Mediated DJ-1 Upregulation Protects MCF-7 Cells from Mitochondrial Damage

Research Abstract
2-Benzoyloxycinnamaldehyde (BCA) is a promising antitumor agent which induces cancer cells apoptosis via reactive oxygen species (ROS) generation. BCA shows more effective antiproliferation in MDAMB- 435 than in MCF-7 breast cancer cells. DJ-1 has been known to protect cells against oxidative stress as an antioxidant because of its cysteine residues sensitive to oxidative stress. In the present study, we evaluated the mechanism of DJ-1 for cell protection from oxidative stress after BCA treatment in MCF-7 cell. BCA upregulates the expression of DJ-1 in MCF-7 cells. However, DJ-1 expression decreased continuously for 24 h after BCA treatment in MDA-MB-435 cells. DJ-1 knockdown sensitized MCF-7 cells to BCA, on the contrary, DJ-1 overexpression induced MDA-MB-435 cells less sensitive to BCA. Confocal microscopic observation showed that only in MCF-7 cells BCA increased the overlapped signal between mitochondria and DJ-1 protein. Mitochondrial membrane potential (MMP) was decreased in MDA-MB-435 cells by BCA, and DJ-1 overexpression inhibited BCA-induced MMP decrease in these cells. On the contrary, DJ-1 knockdown in MCF-7 induced MMP perturbation by BCA. These findings suggest that DJ-1 upregulation protects MCF-7 cells from BCA via inhibiting mitochondrial damage.
Research Authors
Ismail Ahmed Ismail, Hye Suk Kang, Heon-Jin Lee,a Byoung-Mog Kwon,b and Su-Hyung Hong
Research Department
Research Journal
Biol. Pharm. Bull
Research Pages
PP.895–902
Research Vol
Vol.35, No.6
Research Year
2012
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