Displaying publications 101 - 120 of 392 in total

Abstract:
Sort:
  1. Usman AR, Khandaker MU, Haba H, Otuka N, Murakami M, Komori Y
    Appl Radiat Isot, 2016 08;114:104-13.
    PMID: 27227905 DOI: 10.1016/j.apradiso.2016.04.027
    The excitation functions were measured for the (nat)Cu(α,x)(66,67)Ga,(65)Zn,(57,58,60)Co reactions in the energy range of 16.5 -50MeV. A conventional stacked-foil activation technique combined with HPGe γ-ray spectrometry was employed to determine cross-sections. The measured cross-sections were critically compared with relevant previous experimental data and also with the evaluated data in the TENDL-2014 library. Present results confirmed some of the previous experimental data, whereas only a partial agreement was found with the evaluated data. The measured data are useful for reducing the existing discrepancies in the literature, to improve the nuclear reaction model codes, and to enrich the experimental database towards various applications.
  2. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 Aug;58(Pt 8):o477-9.
    PMID: 12154304
    In the title compounds, C(24)H(17)NO(3), (I), and C(43)H(27)NO(5), (II), the dioxine ring is not planar and tends toward a boat conformation. The oxazoline ring adopts a twisted conformation in molecule (I) but is essentially planar in molecule (II). The configuration of the dioxine-oxazoline system is determined by the sp(3) state of the two shared atoms. The phenanthrene moiety is nearly coplanar with the dioxine ring, while the phenyl ring is perpendicular to the attached oxazole ring. The triclinic unit cell of (II) contains two crystallographically independent molecules related by a pseudo-inversion centre.
  3. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 Feb;58(Pt 2):o59-62.
    PMID: 11828108
    In the syn- and anticlinal isomers of the title compound, C(22)H(18)N(2)O(6), the indole moiety is not completely planar, with the pyrrolidine ring being distorted very slightly towards a conformation intermediate between half-chair and envelope. The molecular and packing structures in the crystals of these isomers are stabilized by C-H...O interactions.
  4. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhao BG, Xu JH
    Acta Crystallogr C, 2002 Feb;58(Pt 2):o57-8.
    PMID: 11828107
    In the title compound, C(26)H(22)O(4), the pyranone ring adopts a twisted boat conformation, while the cyclohexane ring is close to an envelope conformation. The dihedral angle between the mean planes of the coumarin and naphthalene systems is 78.8(1) degree. The attached phenyl ring is in an equatorial position with respect to the cyclohexane ring.
  5. Razak IA, Usman A, Fun HK, Yamin BM, Keat GW
    Acta Crystallogr C, 2002 Feb;58(Pt 2):m122-3.
    PMID: 11828100
    In the title compound, [SbCl(2)(C(4)H(8)N(2)S)(2)]Cl, the coordination around the Sb atom can be described as distorted pseudo-octahedral. Both rings of the trimethylenethiourea ligands [alternatively 3,4,5,6-tetrahydropyrimidine-2(1H)-thione] adopt an envelope conformation. The molecules are connected into dimers in the ab plane by two intermolecular hydrogen bonds. The dimers are arranged into infinite one-dimensional chains along the a axis as a result of the Cl(-) ions forming intermolecular hydrogen bonds with three NH groups.
  6. Abdul-Razak I, Usman A, Fun HK, Yamin BM, Kasim NA
    Acta Crystallogr C, 2002 Mar;58(Pt 3):m162-4.
    PMID: 11870289
    In the title compound, [Fe(C(17)H(14)P)(2)](2)[Sb(4)Cl(16)] x C(2)H(6)O, the Fe atoms lie on inversion centres and the pairs of cyclopentadienyl rings are consequently in a fully staggered conformation. The centrosymmetric anionic clusters formed by [Sb(4)Cl(16)](4-) are surrounded by the cations and are held together by weak C-H...Cl interactions. These formations stack along the a axis to form columns, and the columns are interconnected by another weak C-H...Cl interaction along the b axis.
  7. Usman A, Nayar CR, Unnikrishnan PA, Sreeja PB, Prathapachandra Kurup MR, Fun HK
    Acta Crystallogr C, 2002 Dec;58(Pt 12):o724-6.
    PMID: 12466626
    The title molecule, C(13)H(13)N(3)O(3).H(2)O, is in the form of a monohydrated zwitterion. The tetrahydropyridinium ring adopts an envelope conformation and is nearly coplanar with the plane of the imidazoline ring. The water solvate molecule plays an important role as a bridge between zwitterions, forming molecular chains running along the c direction, which are interconnected by N-H.O hydrogen bonds into molecular ribbons. The crystal packing is further stabilized by another N-H.O and one O-H.N hydrogen bond, which interconnect the molecular ribbons.
  8. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 Sep;58(Pt 9):o543-4.
    PMID: 12205382
    In the title compound, C(24)H(17)NO(2)S, the dioxine and thiazoline rings are distorted from planarity towards a half-chair and an envelope conformation, respectively. The configurations of the dioxine ring, the thiazoline ring and the attached phenyl ring are conditioned by the sp(3) state of the two bridgehead C atoms. The phenanthrene system is nearly coplanar with the dioxine ring, while the attached phenyl ring is orthogonal to the thiazoline ring.
  9. Usman A, Razak IA, Chantrapromma S, Fun HK, Sreekanth A, Sivakumar S, et al.
    Acta Crystallogr C, 2002 Sep;58(Pt 9):m461-3.
    PMID: 12205370
    One half of the molecule of the title complex, [Mn(C(14)H(13)N(4)S)(2)], is related to the other half by a twofold axis passing through the Mn atom. This high-spin Mn atom is six-coordinated, in an octahedral geometry, by the azomethine N, the pyridyl N and the thiolate S atom of two planar 1-(pyridin-2-yl)ethanone N(4)-phenylthiosemicarbazone ligands. In the crystal, the molecules are interconnected by N-H.S and C-H.N interactions, forming a three-dimensional network.
  10. Usman A, Razak IA, Chantrapromma S, Fun HK, Philip V, Sreekanth A, et al.
    Acta Crystallogr C, 2002 Nov;58(Pt 11):o652-4.
    PMID: 12415171
    The title compound, C(16)H(17)N(5)S, is in the thione form and crystallizes with two independent molecules in the asymmetric unit. In both molecules, the pentamethyleneimine five-membered ring adopts an envelope conformation, and in one of the molecules this ring shows positional disorder. The thione S and hydrazine N atoms are in the Z configuration with respect to the C-N bond.
  11. Razak IA, Usman A, Fun HK, Yamin BM, Kasim NA
    Acta Crystallogr C, 2002 Apr;58(Pt 4):M225-7.
    PMID: 11932524
    In the title compound, [Fe(C(34)H(29)O(2)P(2))](2)[Sb(2)Cl(8)], the discrete centrosymmetric [Sb(2)Cl(8)]2- anions are formed from two edge-shared square pyramids of Cl atoms about each Sb atom. Within the cation, the two diphenylphosphinate groups share one H atom and the ferrocene cyclopentadienyl rings are in a staggered conformation, with the average value of the twist angle being 46 degrees. In the crystal, each [Sb(2)Cl(8)]2- anion is involved in eight C-H* * *Cl interactions with four surrounding cations and these interactions interconnect the ions to form molecular columns along the a direction.
  12. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 Apr;58(Pt 4):O239-41.
    PMID: 11932554
    The crystal of the title compound, C(20)H(17)NO(4), which was used for collecting intensity data was twinned. Each of the two crystallographically independent molecules in the asymmetric unit has a planar indole moiety perpendicular to a planar oxopropyl moiety. The distribution of the bonds at the central C atom joining the oxopropyl, phenyl and indole substituents is also planar. The packing is stabilized by intermolecular C-H* * *O interactions, as well as by dipole-dipole and van der Waals interactions.
  13. Usman A, Fun HK, Chantrapromma S, Zhu HL, Wang XJ
    Acta Crystallogr C, 2003 Mar;59(Pt 3):m97-9.
    PMID: 12711770
    In the ternary title compound, catena-poly[[silver(I)-mu-ethylenediamine-kappa(2)N:N'] 3-nitrobenzoate monohydrate], [[Ag(C(2)H(8)N(2))](C(7)H(4)NO(4)) x H(2)O](n), the Ag atom is bicoordinated in a linear configuration by two different N atoms from two symmetry-related ethylenediamine ligands, thus giving linear polymeric chains with an [-Ag-N-C-C-N-](n) backbone running parallel to the a axis. In the crystal packing, these linear chains are interconnected by N-H...O and O-H...O hydrogen bonds to form layers parallel to the ab plane.
  14. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhao BG, Xu JH
    Acta Crystallogr C, 2002 Jan;58(Pt 1):o24-5.
    PMID: 11781485
    In the title compound, C20H16N2O5, both of the 1-acetylisatin (1-acetyl-1H-indole-2,3-dione) moieties are planar and form a dihedral angle of 74.1 (1) degrees. Weak intermolecular hydrogen bonds and C-H...pi interactions stabilize the packing in the crystal.
  15. Razak IA, Usman A, Fun HK, Yamin BM, Keat GW
    Acta Crystallogr C, 2002 Jan;58(Pt 1):m31-3.
    PMID: 11781464
    In the title compound, [Zn(CH3COO)2(C4H8N2S)2]*H2O, the Zn atom is tetrahedrally coordinated in the ZnO2S2 form. N-H...O and O-H...O intramolecular and intermolecular hydrogen bonds are formed by the four N atoms and the water molecule. N-H...O intermolecular hydrogen bonds and C-H...S and C-H...O intermolecular interactions interconnect columns formed by the molecules into layers. Adjacent layers are then linked by other N-H...O and O-H...O intermolecular hydrogen bonds to form a three-dimensional framework throughout the structure. The orientations of the acetate planes are such that the Zn atom lies within them.
  16. Ng CH, Lim CW, Teoh SG, Fun HK, Usman A, Ng SW
    Inorg Chem, 2002 Jan 14;41(1):2-3.
    PMID: 11782136
    Treatment of vanadium(V) oxide with an ethanol-concentrated sulfuric acid mixture, followed by the addition of an equimolar amount of beta-alanine and sodium hydroxide, and finally raising the pH to 3.9 with sodium carbonate solution, under continuous heating in a water bath and in the presence of air, leads to the polyionic sodium cyclo-[mu(6)-(sulfato-O,O',O'')tris[mu-(beta-alanine-O,O')-mu-oxo]tris(mu-hydroxo-mu-oxo)hexa[oxovanadium(V)]] sulfate tridecahydrate which crystallizes in the monoclinic P2(1)/n space group [a = 9.5192(4), b = 20.1185(9), c = 22.6174(9) A, beta = 97.011(1) degrees; Z = 4]. The crown-shaped polyoxovanadium(V) cluster cation, with carboxylate-bridging amino acid ligands, has an Anderson structure with two unique capping sulfato ligands. Its structural analysis, together with IR, UV-vis, and preliminary data on its solution properties, is presented.
  17. Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2002 May;58(Pt 5):o287-8.
    PMID: 11983994
    In the title compound, C(18)H(13)BrClNO(3), the heterocyclic ring of the indole is distorted from planarity towards an envelope conformation. The orientations of the indole, oxetane, chloro and bromophenyl substituents are conditioned by the sp(3) states of the spiro-junction and the Cl-attached C atoms.
  18. Usman A, Makmor Bakry M, Mustafa N, Rehman IU, Bukhsh A, Lee SWH, et al.
    Diabetes Metab Syndr Obes, 2019;12:1323-1338.
    PMID: 31496770 DOI: 10.2147/DMSO.S208492
    Background: During the progress and resolution of a diabetic ketoacidosis (DKA) episode, potassium levels are significantly affected by the extent of acidosis. However, none of the current guidelines take into account acidosis during resuscitation of potassium level in DKA management, which may increase the risk of cardiovascular adverse events.

    Objective: To assess literature regarding the adjustment of potassium level using pH to calculate pH-adjusted corrected potassium level, and to observe the relationship of cardiovascular outcomes with reported potassium level and pH-adjusted corrected potassium in DKA.

    Methodology: Seven databases were searched from inception to January 2018 for studies which had reported people with diabetes developing diabetic ketoacidosis, in relation to prevalence or incidence, fluid resuscitation or potassium supplementation treatment, treatment or cardiovascular outcomes, and experimentation with DKA management or insulin. Quality of studies was evaluated using Cochrane Risk of Bias and Newcastle Ottawa Scale.

    Results: Forty-seven studies were included in qualitative synthesis out of a total of 10,292 retrieved studies. Forty-one studies discussed the potassium level and blood pH at the time of admission, ten studies discussed cardiovascular outcomes, and only four studies concurrently discussed potassium level, pH, and cardiovascular outcomes. Only two studies were graded as good on the Newcastle Ottawa Scale. The reported potassium level was well within normal range (5.8 mmol/L), whereas pH rendered patients to be moderately acidotic (7.13). Surprisingly, none of the included studies mentioned pH-adjusted corrected potassium level and, hence, this was calculated later. Although mean corrected potassium was within the normal range (3.56 mmol/L), 13 studies had corrected potassium below 3.5 mmol/L and five had it below 3.0 mmol/L. Nevertheless, with the exception of one study, none discussed cardiovascular outcomes in the context of potassium or pH-adjusted potassium level.

    Conclusion: The evidence surrounding cardiovascular outcomes during DKA episodes in light of a pH-adjusted corrected potassium level is scarce. A prospective observational, or preferably, an experimental study in this regard will ensure we can modify and enhance safety of existing DKA treatment protocols.
  19. Defo Deeh PB, Watcho P, Wankeu-Nya M, Ngadjui E, Usman UZ
    Andrologia, 2019 Apr;51(3):e13216.
    PMID: 30536879 DOI: 10.1111/and.13216
    This study evaluated the effects of the methanolic extract of Guibourtia tessmannii (GT) and selenium (Se) on cell viability, intracellular calcium concentration ([Ca2+ ]i ), apoptosis and oxidative stress through transient receptor potential vanilloid 1 (TRPV1) channel activity in CCL-97 (R2C) tumour Leydig cells. The cells were divided into nine groups and treated as follows: (a)-Control, (b)-Capsazepine (CPZ, 0.1 mM, a TRPV1 channel blocker), (c)-Capsaicin (CAP, 0.01 mM, a TRPV1 channel activator), (d)-GT (500 μg/ml), (e)-GT+CPZ, (f)-GT+CAP, (g)-Se (200 nM), (h)-Se+CPZ and (i)-Se+CAP. After treatments, cell viability, [Ca2+ ]i , apoptosis, caspase 3/9, reactive oxygen species (ROS) and mitochondrial membrane depolarisation (MMD) were evaluated. The [Ca2+ ]i , apoptosis, caspase 3/9, MMD and ROS levels were significantly (p 
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links