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A. M. Abdelghany - One of the best experts on this subject based on the ideXlab platform.

  • Spectroscopic Inquiry of the Fe_2O_3-role in Binary Sodium Borate, Sodium Silicate and Sodium Phosphate Glasses and Effects of Gamma Irradiation
    Silicon, 2016
    Co-Authors: A. M. Fayad, A. M. Abdelghany
    Abstract:

    Optical absorption spectral investigations have been carried out on Fe^3+ ions doped Sodium Borate, Sodium silicate and Sodium phosphate glasses before and after gamma irradiation. The UV-visible absorption spectrum exhibits bands characteristic of Fe^3+ ions coordination in each system. Interesting aspects of FT-IR spectra were found, and this gives information about the structure changes in the constituent units of these glass systems as a function of Fe_2O_3 concentration. All glasses reveal characteristic absorption bands due to the addition of different ratios of iron which explain the state of iron in each system in terms of its valence and coordination number. Results indicate that iron favors a higher oxidation state (tetrahedral coordination) in the case of Sodium silicate glasses. The doping with progressive Fe_2O_3 additions (0.5−7.5 % ) has some effect on the number and position of the characteristic bands due to formation of FeO_4 groups. The IR absorption spectra after irradiation reveal limited changes in the intensity which can be correlated with minor changes in bond angles and /or bond lengths within the structural units by irradiation.

  • Spectroscopic Inquiry of the Fe2O3-role in Binary Sodium Borate, Sodium Silicate and Sodium Phosphate Glasses and Effects of Gamma Irradiation
    Silicon, 2015
    Co-Authors: A. M. Fayad, A. M. Abdelghany
    Abstract:

    Optical absorption spectral investigations have been carried out on Fe3+ ions doped Sodium Borate, Sodium silicate and Sodium phosphate glasses before and after gamma irradiation. The UV-visible absorption spectrum exhibits bands characteristic of Fe3+ ions coordination in each system. Interesting aspects of FT-IR spectra were found, and this gives information about the structure changes in the constituent units of these glass systems as a function of Fe2O3 concentration. All glasses reveal characteristic absorption bands due to the addition of different ratios of iron which explain the state of iron in each system in terms of its valence and coordination number. Results indicate that iron favors a higher oxidation state (tetrahedral coordination) in the case of Sodium silicate glasses. The doping with progressive Fe2O3 additions (0.5−7.5 %) has some effect on the number and position of the characteristic bands due to formation of FeO4 groups. The IR absorption spectra after irradiation reveal limited changes in the intensity which can be correlated with minor changes in bond angles and /or bond lengths within the structural units by irradiation.

  • Optical and FTIR structural studies of CoO-doped Sodium Borate, Sodium silicate and Sodium phosphate glasses and effects of gamma irradiation-a comparative study
    Journal of Molecular Structure, 2014
    Co-Authors: A. M. Abdelghany, Fatma H. Elbatal, Hatem A. Elbatal, F.m. Ezzeldin
    Abstract:

    Abstract Undoped and CoO-doped three binary glass systems, namely Sodium Borate, Sodium silicate and Sodium phosphate glasses were prepared by the melt annealing technique. Combined optical and FTIR spectral studies were carried out for the prepared samples before and after being subjected to a gamma dose of 8 Mrad (8 × 10 4  Gy). Optical spectra of the undoped samples before irradiation reveal strong UV absorption varying in depth with the type of glass and such strong UV spectra are related to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of these three basic glasses. CoO-doped (0.25%) glasses show additional visible absorption spectra which are related to the existence of cobalt in the divalent state (Co) 2+ ions which are present in two coordination states, namely the octahedral and tetrahedral forms. The broad visible band of Co 2+ ions shows in some instances obvious splitting to three component peaks. Gamma irradiation on undoped glasses causes obvious induced UV–visible bands and their extension depends on the type of glass system. Irradiation of CoO-doped glasses causes an obvious increase of absorption within the visible region. Infrared absorption spectra of the undoped three basic glasses reveal IR vibrational bands which are characteristics to the three specific characteristic structural building units within the Borate, silicate and phosphate glasses. The introduction of CoO with the doping level causes minor variations of the IR spectra because of the low doping content together with the presence of cobalt ions in structural modifying sites. Gamma irradiation is observed to cause limited changes within the intensities of some bands in the IR spectra which are attributed to changes in bond lengths and/or bond angles of the structural building units by the irradiation process.

Reinhard Niessner - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of atrazine, terbutylazine and their N-dealkylated chloro and hydroxy metabolites by solid-phase extraction and gas chromatography-mass spectrometry and capillary electrophoresis-ultraviolet detection.
    Journal of Chromatography A, 1999
    Co-Authors: Robert Loos, Reinhard Niessner
    Abstract:

    Abstract Solid-phase extraction (SPE) with the styrene–divinylbenzene adsorbent LiChrolut EN was investigated for the extraction of the s-triazine herbicides atrazine and terbutylazine, their polar N-dealkylated degradation products deethylatrazine (DEA), deisopropylatrazine (DIA) and deethylterbutylazine (DET) and for the hydrophilic hydroxytriazine degradation products (HTDPs) hydroxyatrazine (HA), hydroxyterbutylazine (HT), deethylhydroxyatrazine (DEHA), deisopropylhydroxyatrazine (DIHA) and deethyldeisopropylhydroxyatrazine (ameline). The optimum pH value for the extraction of the HTDPs from fortified tap water at 2 μg/l is 3.0. Recovery values with 200 mg LiChrolut EN are >80% for HA, HT, DEHA and 30% for DIHA from 200 ml spiked tap and river water. Atrazine, terbutylazine, DEA, DIA and DET are quantitatively extracted by LiChrolut EN. The chlorotriazines are analyzed by GC–MS and the HTDPs by capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC) with an acetate buffer at pH 4.6 or a Sodium Borate–Sodium dodecyl sulfate buffer at pH 9.3. The combined method of SPE enrichment and CE analysis allows the determination of HTDPs in the low μg/l range.

M.s. Lowery - One of the best experts on this subject based on the ideXlab platform.

  • Conduction calorimetric investigation of the effect of retarders on the hydration of Portland cement
    Thermochimica Acta, 1992
    Co-Authors: V.s. Ramachandran, M.s. Lowery
    Abstract:

    Abstract Eleven potential retarders, calcium gluconate, glucose, glycolic acid, molasses, Sodium Borate, Sodium citrate, Sodium heptonate, Sodium hexametaphosphate, Sodium pyrophosphate, sugar-free calcium lignosulfonate and sucrose, were added to Portland cement in dosages ranging from 0.025% to 1.2%, at a constant water: cement ratio of 0.5 and their conduction calorimetric behavior was investigated for periods up to 72 h. All retarders increased the induction period, from about 4 h to 55 h. Less than 0.15% of the most efficient retarders were needed to extend effectively the induction period to 40 h. They included Ca-gluconate, Na-heptonate and sucrose. The least effective retarders such as Ca-lignosulfonate (sugar-free), Na-pyrophosphate, Na-hexametaphosphate, Na-Borate and glycolic acid had to be added at levels above 0.5% to attain an induction period of 40 h. Others such as glucose, molasses and Na-citrate were designated as moderately retarding admixtures. In most instances the degree of extension of the induction period was approximately linear with respect to the dosage of retarders, but the slopes were different.

A. M. Fayad - One of the best experts on this subject based on the ideXlab platform.

  • Spectroscopic Inquiry of the Fe_2O_3-role in Binary Sodium Borate, Sodium Silicate and Sodium Phosphate Glasses and Effects of Gamma Irradiation
    Silicon, 2016
    Co-Authors: A. M. Fayad, A. M. Abdelghany
    Abstract:

    Optical absorption spectral investigations have been carried out on Fe^3+ ions doped Sodium Borate, Sodium silicate and Sodium phosphate glasses before and after gamma irradiation. The UV-visible absorption spectrum exhibits bands characteristic of Fe^3+ ions coordination in each system. Interesting aspects of FT-IR spectra were found, and this gives information about the structure changes in the constituent units of these glass systems as a function of Fe_2O_3 concentration. All glasses reveal characteristic absorption bands due to the addition of different ratios of iron which explain the state of iron in each system in terms of its valence and coordination number. Results indicate that iron favors a higher oxidation state (tetrahedral coordination) in the case of Sodium silicate glasses. The doping with progressive Fe_2O_3 additions (0.5−7.5 % ) has some effect on the number and position of the characteristic bands due to formation of FeO_4 groups. The IR absorption spectra after irradiation reveal limited changes in the intensity which can be correlated with minor changes in bond angles and /or bond lengths within the structural units by irradiation.

  • Spectroscopic Inquiry of the Fe2O3-role in Binary Sodium Borate, Sodium Silicate and Sodium Phosphate Glasses and Effects of Gamma Irradiation
    Silicon, 2015
    Co-Authors: A. M. Fayad, A. M. Abdelghany
    Abstract:

    Optical absorption spectral investigations have been carried out on Fe3+ ions doped Sodium Borate, Sodium silicate and Sodium phosphate glasses before and after gamma irradiation. The UV-visible absorption spectrum exhibits bands characteristic of Fe3+ ions coordination in each system. Interesting aspects of FT-IR spectra were found, and this gives information about the structure changes in the constituent units of these glass systems as a function of Fe2O3 concentration. All glasses reveal characteristic absorption bands due to the addition of different ratios of iron which explain the state of iron in each system in terms of its valence and coordination number. Results indicate that iron favors a higher oxidation state (tetrahedral coordination) in the case of Sodium silicate glasses. The doping with progressive Fe2O3 additions (0.5−7.5 %) has some effect on the number and position of the characteristic bands due to formation of FeO4 groups. The IR absorption spectra after irradiation reveal limited changes in the intensity which can be correlated with minor changes in bond angles and /or bond lengths within the structural units by irradiation.

Zheng Sun - One of the best experts on this subject based on the ideXlab platform.

  • Syntheses and Structures of Oxovanadium (IV) Complexes, HB(pz)3VO(ph‐acac) · 2H2O (pz, Pyrazole) and HB(3,5‐Me2pz)3VO(ph‐acac) · 2H2O and V2O4[HB(pz)3]2 · 2CH3CN
    Synthesis and Reactivity in Inorganic Metal-Organic and Nano-Metal Chemistry, 2007
    Co-Authors: Yong Heng Xing, Feng Ying Bai, Katsuyuki Aoki, Zheng Sun
    Abstract:

    The reaction of VO(ph‐acac)2 (ph‐acac=phenyacetylacetonato) with NaHB(pz)3 (pz=pyrazole) or NaHB(3,5‐Me2pz)3 in the solution of MeOH gave oxovanadium (IV) complexes HB(pz)3VO(ph‐acac) · 2H2O (1) and HB(3,5‐Me2pz)3VO(ph‐acac) · 2H2O (2), respectively. An oxovanadium complex, V2O4[HB(pz)3]2 · 2CH3CN (3), was obtained by the reaction of VOSO4 · 3H2O with tri(pyrazolyl)Borate Sodium in MeOH. The complexes 1, 2 and 3 were characterized by elemental analysis, IR, UV‐Vis, NMR. In particular, the crystals of complex 1 and 3 were determined by X‐ray diffraction. They crystallize in space group P2 1/c, a=16.497(5) A, b=7.6601(19) A, c=17.199(4) A, β=107.498(19)°, V=2072.8(9) A3, Z=4, R=0.0371 (I>2σ(I)) for 1; in the monoclinic, space group Pbca, with cell dimensions of a=15.531(2) A; b=18.007(2) A; c=10.725(2) A; V=2999.4(8) A3, Z=4, R= 0.0401(I>2σ(I)) for 3. Structure analyses have shown that complex 1 is a monomeric oxovanadium complexe containing polypyrazolylBorate and two lattice water. Complex 3 consists of a...