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  1. AU="Adam, Mahmoud A"
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  1. Article: Enhancing the Durability of Calcareous Stone Monuments of Ancient Egypt Using CaCO<sub>3</sub> Nanoparticles

    Aldoasri, Mohammad A / Adam, Mahmoud A / Ahmed, Sayed M / Darwish, Sawsan S / Elmarzugi, Nagib A

    Sustainability. 2017 Aug. 10, v. 9, no. 8

    2017  

    Abstract: The unwanted changes in valuable historic calcareous stone monuments due to exposure to many physical and chemical effects may lead to its deterioration. The growing interest in the field of conservation of stone monuments encourages the development of ... ...

    Abstract The unwanted changes in valuable historic calcareous stone monuments due to exposure to many physical and chemical effects may lead to its deterioration. The growing interest in the field of conservation of stone monuments encourages the development of consolidation and water-repellent materials. The aim of this study is to evaluate the effectiveness of CaCO<inf>3</inf> nanoparticles as a consolidation and protection material for calcareous stone monuments, when those nanoparticles used are dispersed in acrylic copolymer; polyethylmethacrylate (EMA)/methylacrylate (MA) (70/30), respectively. Samples were subjected to artificial aging by relative humidity/temperature to show the optimum conditions of durability and the effectiveness of the nano-mixture in improving the physical and mechanical properties of the stone material. The synthesis process of CaCO<inf>3</inf> nanoparticles/polymer nanocomposite has been prepared by in situ emulsion polymerization system. The prepared nanocomposites with 0.15 g CaCO<inf>3</inf> nanoparticles showed obvious transparency features and represent nanocomposites coating technology with hydrophobic, consolidating and good protection properties. Some tests were performed in order to estimate the superficial consolidating and protective effect of the treatment. The obtained nanocomposites have been characterized by TEM, while the surface morphology before and after treatment and homogeneous distribution of used consolidation materials on stone surface were examined by SEM. Improvement of stone mechanical properties was evaluated by compressive strength tests. Change in water-interaction properties was evaluated by water absorption capillarity measurements, and colorimetric measurements were used to evaluate the optical appearance. Taken together, the results indicate that CaCO<inf>3</inf>/polymer nanocomposite is a completely compatible, efficient material for the consolidation of artistic and architectural limestone monuments capable of enhancing the durability of limestone toward artificial aging and improving the stone mechanical properties compared to the samples treated with pure acrylic copolymer without Calcium carbonate nanoparticles.
    Keywords calcium carbonate ; capillarity ; colorimetry ; composite polymers ; compression strength ; durability ; emulsions ; hydrophobicity ; limestone ; mechanical properties ; monuments ; nanoparticles ; polymer nanocomposites ; polymerization ; protective effect ; relative humidity ; scanning electron microscopy ; temperature ; transmission electron microscopy ; water uptake ; Egypt
    Language English
    Dates of publication 2017-0810
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2518383-7
    ISSN 2071-1050
    ISSN 2071-1050
    DOI 10.3390/su9081392
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: Protecting of Marble Stone Facades of Historic Buildings Using Multifunctional TiO<sub>2</sub> Nanocoatings

    Aldoasri, Mohammad A / Adam, Mahmoud A / Ahmed, Sayed M / Darwish, Sawsan S / Elmarzugi, Nagib A

    Sustainability. 2017 Nov. 07, v. 9, no. 11

    2017  

    Abstract: Stone surfaces and façades of historic buildings, due to their predominately outdoor location, suffer from many deterioration factors, including air pollution, soluble salts, relative humidity (RH)/temperature, and biodeterioration, which are the main ... ...

    Abstract Stone surfaces and façades of historic buildings, due to their predominately outdoor location, suffer from many deterioration factors, including air pollution, soluble salts, relative humidity (RH)/temperature, and biodeterioration, which are the main causes of decay. In particular, the façades of the buildings deteriorate with direct exposure to these factors; deformation and disfiguration of superficial decoration and formation of black crusts are often observed on the stones. The development and application of self-cleaning and protection treatments on historical and architectural stone surfaces could be a significant improvement in the conservation, protection and maintenance of Cultural Heritage. A titanium dioxide nanoparticle has become a promising photocatalytic material, owing to its ability to catalyze the complete degradation of many organic contaminants and environmental factors. In this study, TiO<inf>2</inf> nanoparticles, dispersed in an aqueous colloidal suspension, were applied directly to historic marble stone surfaces, by spray-coating, in order to obtain a nanometric film over the stone surface. The study started with an investigation of some properties of TiO<inf>2</inf> nanoparticles, to assess the feasibility of the use of TiO<inf>2</inf> on historic stone and architectural surfaces. Scanning electron microscopy (SEM) was, coupled with energy dispersive X-ray (EDX) microanalysis, (SEM-EDX), in order to obtain information on coating homogeneity and surface morphology, before and after artificial aging; the activity of the coated surface was evaluated through UV-light exposure, to evaluate photo-induced effects. The changes of molecular structure occurring in treated samples were spectroscopically studied by attenuated total reflection infrared spectroscopy (ATR-FTIR); activity of the hydrophobic property of the coated surface was evaluated by Sterio microscopy, model Zeiss 2010 from Munich, Germany, equipped with photo camera S23 under 80X magnification. The efficacy of the treatments was evaluated through capillary water absorption, and colorimetric measurements, performed to evaluate the optical appearance. Results showed that TiO<inf>2</inf> nanoparticles are good candidates for coating applications on historic stone surfaces, where self-cleaning photo-induced effects are well evident; they enhanced the durability of stone surfaces toward UV aging, improved resistance to relative humidity (RH)/temperature and abrasion affect, reduced accumulation of dirt on stone surfaces when left in open air for 6 months, and did not alter the original features.
    Keywords air ; air pollution ; biodegradation ; buildings ; cameras ; chemical structure ; colloids ; colorimetry ; deformation ; durability ; energy-dispersive X-ray analysis ; environmental factors ; Fourier transform infrared spectroscopy ; historic sites ; hydrophobicity ; models ; nanoparticles ; photocatalysis ; relative humidity ; rocks ; scanning electron microscopy ; soluble salts ; temperature ; titanium dioxide ; ultraviolet radiation ; water uptake ; Germany
    Language English
    Dates of publication 2017-1107
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2518383-7
    ISSN 2071-1050
    ISSN 2071-1050
    DOI 10.3390/su9112002
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: The restoration and erection of the world's first elevated obelisk.

    Saleh, Atef M / Mourad, Sherif A / Elanwar, Hazem H / Metwally, Omar K / Zeidan, Eissa / Adam, Mahmoud A / Ameen, Mostafa F / Helal, Khalid R / Sholqamy, Mohamed S / Allam, Hussien E / Ismael, Mohamed A / Mostafa, Khaled A / Helal, Hany M / Elbanhawy, Amr Y / Grosse, Christian U / Bakhoum, Mourad M / Farag, Mousa M / Matar, Hani B / Eltobgy, Hanan H /
    Moharram, Moustafa I / Marzouk, Mohamed M / Metawie, Mahmoud S / Ali, Mohamed R / Sayed, Ashraf N / Mohamed, Mohamed G / Elkarmoty, Mohamed M

    Scientific reports

    2023  Volume 13, Issue 1, Page(s) 2065

    Abstract: Obelisks presented an important element in the architecture of ancient Egypt. This research is concerned with the re-erection of an obelisk that belongs to the famous Pharoah Ramses II. It was found broken and was transported to the Grand Egyptian Museum ...

    Abstract Obelisks presented an important element in the architecture of ancient Egypt. This research is concerned with the re-erection of an obelisk that belongs to the famous Pharoah Ramses II. It was found broken and was transported to the Grand Egyptian Museum for restoration and display. An observation of Ramses II Cartouche at the bottom side of the obelisk base inspired the authorities to provide an innovative architectural design to display the obelisk elevated. The supporting structure was designed to allow the visitors to walk underneath the obelisk and observe Ramses II's signature. The idea of elevating the obelisk presented several challenges including evaluating the obelisk's current condition, restoration and fixation methodology, structural stability, and uncertainties of material characteristics, amongst others. To control the obelisk deformations under lateral loading, state-of-the-art base isolators were introduced. For the task to be achieved, a multidisciplinary team including historians, conservators, archaeologists, architects, and engineers with different specialties was appointed. The team performed the task successfully and currently, the obelisk stands at the entrance piazza of the Grand Egyptian Museum representing the world's first elevated obelisk.
    Language English
    Publishing date 2023-02-04
    Publishing country England
    Document type Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-023-29092-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Close approximation of two platelet factor 4 tetramers by charge neutralization forms the antigens recognized by HIT antibodies.

    Greinacher, Andreas / Gopinadhan, Manesh / Günther, Jens-Uwe / Omer-Adam, Mahmoud A / Strobel, Ulrike / Warkentin, Theodore E / Papastavrou, Georg / Weitschies, Werner / Helm, Christiane A

    Arteriosclerosis, thrombosis, and vascular biology

    2006  Volume 26, Issue 10, Page(s) 2386–2393

    Abstract: Objective: Heparin-induced thrombocytopenia (HIT) is a prothrombotic drug reaction caused by antibodies that recognize positively charged platelet factor 4 (PF4), bound to the polyanion, heparin. The resulting immune complexes activate platelets. ... ...

    Abstract Objective: Heparin-induced thrombocytopenia (HIT) is a prothrombotic drug reaction caused by antibodies that recognize positively charged platelet factor 4 (PF4), bound to the polyanion, heparin. The resulting immune complexes activate platelets. Unfractionated heparin (UFH) causes HIT more frequently than low-molecular-weight heparin (LMWH), whereas the smallest heparin-like molecule (the pentasaccharide, fondaparinux), induces anti-PF4/heparin antibodies as frequently as LMWH, but without exhibiting cross-reactivity with these antibodies. To better understand these findings, we analyzed the molecular structure of the complexes formed between PF4 and UFH, LMWH, or fondaparinux.
    Methods and results: By atomic force microscopy and photon correlation spectroscopy, we show that with any of the 3 polyanions, but in the order, UFH>LMWH>>fondaparinux--PF4 forms clusters in which PF4 tetramers become closely apposed, and to which anti-PF4/heparin antibodies bind. By immunoassay, HIT antibodies bind strongly to PF4/H/PF4 complexes, but only weakly to single PF4/heparin molecules.
    Conclusions: HIT antigens are formed when charge neutralization by polyanion allows positively charged PF4 tetramers to undergo close approximation. Whereas such a model could explain why all 3 polyanions form antibodies with similar specificities, the striking differences in the relative size and amount of complexes formed likely correspond to the observed differences in immunogenicity (UFH>LMWH approximately fondaparinux) and clinically relevant cross-reactivity (UFH>LMWH>>fondaparinux).
    MeSH term(s) Adsorption ; Antibodies/immunology ; Antibody Formation ; Enzyme-Linked Immunosorbent Assay ; Heparin/adverse effects ; Heparin/immunology ; Heparin, Low-Molecular-Weight/immunology ; Humans ; Microscopy, Atomic Force ; Photons ; Platelet Factor 4/chemistry ; Platelet Factor 4/immunology ; Polysaccharides/immunology ; Spectrum Analysis/methods ; Thrombocytopenia/chemically induced ; Thrombocytopenia/immunology
    Chemical Substances Antibodies ; Heparin, Low-Molecular-Weight ; Polysaccharides ; Platelet Factor 4 (37270-94-3) ; Heparin (9005-49-6) ; fondaparinux (J177FOW5JL)
    Language English
    Publishing date 2006-10
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1221433-4
    ISSN 1524-4636 ; 1079-5642
    ISSN (online) 1524-4636
    ISSN 1079-5642
    DOI 10.1161/01.ATV.0000238350.89477.88
    Database MEDical Literature Analysis and Retrieval System OnLINE

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