University of Malaya

About: University of Malaya is a education organization based out in Kuala Lumpur, Malaysia. It is known for research contribution in the topics: Population & Fiber laser. The organization has 25087 authors who have published 51491 publications receiving 1036791 citations. The organization is also known as: UM & Universiti Malaya.

On non-negative forms in real variables some or all of which are non-negative

Abstract: In a recent paper (3) Mordell proposed for solutionPROBLEM 1. To find the constants a1, …, an so thatwhere xn+i = xi ≥ 0 for all i.

Helical Silver(I)−2,4‘-Bipyridine Chains Organized into 2-D Networks by Metal−Counterion or Metal−Metal Bonding. Structures of [Ag(2,4‘-bipyridine)]X (X- = NO3- or ClO4-)

Abstract: Two compounds, [Ag(2,4‘-bpy)]NO3 (1) and [Ag(2,4‘-bpy)]ClO4 (2), were obtained from self-assembly of AgX (X = NO3-, ClO4-) with 2,4‘-bipyridine (2,4‘-bpy). 1 crystallizes in the orthorhombic space group Pbca, with a = 11.2884(7) A, b = 11.3981(10) A, c = 16.5299(13) A, and Z = 8, while 2 crystallizes in the monoclinic space group P21/c, with a = 10.6361(4) A, b = 9.9896(4) A, c = 11.2661(6) A, β = 98.527(4)°, and Z = 4. Both complexes consist of helical [Ag(2,4‘-bpy)]∞ chains that are surrounded by nitrate or perchlorate counterions. Adjacent helical chains are racemic. The AgI atom is linked to two nitrogen atoms of the 2-pyridyl and 4‘-pyridyl groups from two different 2,4‘-bpy ligands as well as to the oxygen atom of the counterion. In 1, another oxygen atom of the counterion is weakly coordinated to the AgI atom of an adjacent chain, thus bridging the helical chains into a wavy 2-D network structure, whereas in 2, adjacent helical chains are linked by the weak ligand-unsupported metal−metal interactio...

Characterization of chitosan/PVA blended electrolyte doped with NH4I

Abstract: The (chitosan–PVA)–NH 4 I electrolytes have been prepared by the solution casting method. The prepared electrolytes are analyzed using Fourier transform infrared (FTIR) spectroscopy in order to determine the interaction between salt and the polymer blend hosts which can be deduced from the band shifting. From infrared spectra, shifts are observed at the amine, carboxamide, carbonyl and hydroxyl bands of chitosan and PVA. These shifts indicate that complexation has occurred. The crystallinity/amorphousness of the blended electrolytes has been examined by X-ray diffraction (XRD). XRD pattern shows that the crystallinity of chitosan–NH 4 I electrolyte increases with PVA concentration. Impedance of the electrolytes has been measured using electrochemical impedance spectroscopy (EIS) over the frequency range from 50 Hz to 1 MHz. The highest conducting sample 55 wt.% (chitosan–PVA)–45 wt.% NH 4 I has conductivity of 1.77 × 10 − 6 S cm − 1 . The chitosan:PVA ratio is 1:1. This is higher than the conductivity for the unblended electrolyte 55 wt.% chitosan–45 wt.% NH 4 I which is 3.73 × 10 − 7 S cm − 1 . From ln τ versus 10 3 / T plot, the activation energy for relaxation process is 0.87 eV. This is different from activation energy for dc conductivity which is 0.38 eV. Ion conduction is by hopping.