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  • 1. Abdullah, Omed Gh.
    et al.
    Tahir, Dana A.
    Kadir, K.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Kurdistan Institution for Strategic Studies and Scientific Research, Iraq.
    Optical and structural investigation of synthesized PVA/PbS nanocomposites2015Ingår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 26, nr 9, s. 6939-6944Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polymer nanocomposite based on polyvinyl alcohol (PVA) and lead sulfide (PbS) in the average radius of (1.88-2.23) nm, have been synthesized using the chemical reduction rote and solution casting technique for different concentrations of PbS. The characterization of the polymer nanocomposite films were carried out using UV-visible spectroscopy, SEM, and XRD. The effect of various concentration of PbS NP on the optical properties of the composite has been studied to understand the optimum conditions for the synthesis process. The nanocomposite film shows high UV and visible light absorptions in the wavelength range of (200-500) nm, which correspond to the characteristics of the PbS NPs. The significant decreasing trend of the direct allowed band gap of the nanocomposite was observed upon increasing the Pb source concentration, from (6.27 eV) for pure PVA to (2.34 eV) for 0.04 M PbS concentration, which is much higher than the energy gap of bulk PbS value (0.41 eV). The calculated values of the static refractive index of Cauchy dispersion model were in the range of (1.09-1.20). X-ray diffraction analysis confirmed the cubic nanocrystalline PbS phase formation.

  • 2.
    Fahlquist, Henrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Kadir, Abdulkarim
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Noréus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Structural characterization of Sr4Mg4H4[CoH5]3 shows the importance of support from polarizingcounter ions to 3d transition metal hydrido complexesIngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure of the title compound was refined from neutronpowder diffraction data in the cubic space group P-43m (215). The unitcell contains one formula unit with 3 structurally equivalent [Co(I)H5]4-complexes as well as 4 interstitial hydride (H-) ions. The presence ofthe larger and less polarizing Sr2+ ions weakens the bond in thecomplexes and probably also the stability of the structure. Attempts tosynthesize the corresponding Ba analogue failed in contrast to usingsmaller and more polarizing Ca2+ and Yb2+ counterions.

  • 3.
    Fahlquist, Henrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Kadir, Karim
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Noréus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Structural characterization of Sr4Mg4H4[CoH5](3) shows the importance of support from polarizing counter ions to 3d transition metal hydrido complexes2013Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 579, s. 31-33Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure of the title compound was refined from neutron powder diffraction data in the cubic space group P-43m (215). The unit cell contains one formula unit with 3 structurally equivalent [Co(I)H-5](4)-complexes as well as 4 interstitial hydride (H-) ions. The presence of the larger and less polarizing Sr2+ ions weakens the bond in the complexes and probably also the stability of the structure. Attempts to synthesize the corresponding Ba analogue failed in contrast to using smaller and more polarizing Ca2+ and Yb2+ counterions.

  • 4.
    Kadir, Abdulkarim
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Moser, D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Munzel, M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Noreus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Investigation of Counterion Influence on an Octahedral IrH(6)-Complex in the Solid State Hydrides AAeIrH(6) (A = Na, K and Ae = Ca, Sr, Ba, and Eu) with a New Structure Type2011Ingår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, nr 23, s. 11890-11895Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A number of new quaternary iridium based hydrides and deuterides AAeIrH/D(6) (where A = Na and K; Ae = Ca, Ba, Sr, and Eu) have been synthesized by direct combination of the alkali, alkaline earth or europium binary hydrides/deuterides and iridium powder. The crystal structures were determined by Guinier-Hagg X-ray and neutron powder diffraction and a new cubic structure type was found. The structure is described in space group F (4) over bar 3m, but related to the K(2)PtCl(6) type structure. The new structure can be described as consisting of cubes of A(+) and Ae(2+) ions, where the A(+) and Ae(2+) ions alternates so that they occupy opposite corners in the cube. Every second cube contains a regular octahedral [Ir(III)H(6)](-3)-complex and the adjacent is empty. Solid-state IR spectroscopy was used to determine the Ir-allowed stretching and bending frequencies for the [Ir(III)H(6)](-3) complex with different counterions. These were also compared with the corresponding stretching frequencies for Fe(II)H(6), Ru(II)H(6), Os(II)H(6), and Ir(II)H(5) complexes in similar solid state hydrides, which increased when going from Fe through Ru, Os to Ir. The frequencies scaled almost linearly with the inverse of size of the cube surrounding the complexes but showed no significant dependence of the formal oxidation state or the experimentally obtained Ir-D distances. However, this was mainly because of difficulties in obtaining enough accurate atomic positions. The ab initio DFT calculations could reproduce the stretching frequencies within a few 10 cm(-1), indicating that experimental vibrational frequencies offer a sensitive test of DFT results.

  • 5.
    Kadir, Abdulkarim
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Noreus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Structural determination of NaAl2Ga2 intermetallic compound having the ThCr2Si2 type structure.2009Ingår i: Journal of Alloys and Compounds, Vol. 477, nr 1-2, s. 149-151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    NaAl2Ga2 intermetallic compound has been synthesized by direct combination of the elements in the atomic ratio Na:Ga:Al = 1:2:2. Guinier–Hägg X-ray and neutron powder diffraction determined a ThCr2Si2 type structure for the new compound with tetragonal unit cell axis a = 4.1817(5) and c = 11.388(2) Å.

  • 6. Lelis, Martynas
    et al.
    Milcius, Darius
    Wirth, Emmanuel
    Halenius, Ulf
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Jansson, Kjell
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Kadir, Karim
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Ruan, Juanfang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Sato, Toyoto
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Yokosawa, Tadahiro
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Noréus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    A mechanically switchable metal-insulator transition in Mg2NiH4 discovers a strain sensitive, nanoscale modulated resistivity connected to a stacking fault2010Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 496, nr 02-jan, s. 81-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The band gap in semiconducting Mg2NiH4 was found to be dependent on subtle structural differences. This was discovered when investigating if thin film samples of Mg2NiH4 could be used in a switchable mirror or window device by utilizing a high to low temperature transition at about 510K. In powder samples; this transition between an FCC high temperature phase, with dynamically disordered NiH4-complexes, and a monoclinic distorted low temperature phase, with ordered Mg2NiH4-complexes, has been demonstrated in a mechanical reversible conductor-insulator transition (Blomqvist and Noreus (2002) [7]). Black monoclinic Mg2NiH4 powders were found to have a band gap of 1.1 eV. Pressed tablets of black monoclinic Mg2NiH4 powders are conductive, probably from doping by impurities or non-stoichiometry. Thin film Mg2NiH4 samples were produced by reacting hydrogen with magnetron sputtered Mg2Ni films on quartz glass or CaF2 substrates. The Mg2NiH4 films on the other hand were orange, transparent with a band gap of 2.2 eV and a cubic unit cell parameter almost identical to the disorder HT phase but with lower symmetry. If black Mg2NiH4 powder is heated above the phase transition at 510K and subsequently cooled down, the conductivity is lost and the powder turns brown. After this heat treatment TEM pictures revealed a multiple stacking fault having a local pseudo-cubic arrangement separating regions of monoclinic symmetry. The loss of conductivity and colour change is attributed to a higher band gap in the strained areas. The structure on each side of the stacking fault is related by a mirror plane as a consequence of the possibility for the NiH4-complexes to order with different orientations. This leads to a mismatch in the long range ordering and strain is probably creating the stacking faults. Strain is important for forming the cubic modification. A severely strained film was revealed with optical microscopy in reflected light, indicating that strain prevents it from relaxing back into the monoclinic structure. This was supported by multiple twinned red translucent Mg2NiH4 crystals grown with cubic symmetry at elevated temperatures in a LiH flux. When cooled to ambient conditions, the ""crystals"" had the same cubic symmetry as the films, probably held together by their neighbours. When they were ground to a fine powder to prepare TEM samples, they relaxed and reverted back to the conventional monoclinic unit cell. This interesting nanoscale modulated resistance could possibly be developed into novel memory devices if properly controllable.

  • 7. Rahman, Inayat U.
    et al.
    Idrees, Muhammad
    Waqas, Mohammad
    Karim, Abdul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för genetik, mikrobiologi och toxikologi.
    A study of the interaction between H-pylori mice passage strains and gastric epithelial cells2018Ingår i: Pakistan Journal of Pharmaceutical Sciences, ISSN 1011-601X, Vol. 31, nr 3, s. 769-775Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Helicobacter pylon (H. pylori) infections are very serious health problem that are further worsened by increasing/developing resistance to the current antibiotics. Therefore, new therapeutic agents are needed for H. pylori eradication. Use of a CD46 derived peptide (P3) as bactericidal agent against H. pylon has shown high activity rate in vivo and this study examines the changes in H. pylori features in response to effect of P3 treatment. AGS cells were infected with H. pylon wild type strain 67:21 and its mice passage strains (P3 treated and untreated strains) and further examined using immunoblotting assay, FACS and Urease activity analysis. Comparatively we found increased level of Urease alpha subunit A (UreA) and alkyl hydroperoxide reductase C (AhpC) proteins for P3 treated strain of H. pylori than its wild type or untreated strain after infection of AGS cells. Conclusion These results suggest that there might be a high rate of adherence to host cells for the P3 treated passage strain than untreated or wild type strain. Our findings also indicate that either adhesins are being changed or H pylon interaction to the host cells is affected after P3 treatment.

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