University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
COMPARATIVE ANALYSIS OF PIGMENTS IN
PETALS AND STIGMATA OF CROCUS
ALMENENSIS C. BRICKELL AND B. MATHEW
AND CROCUS SATWUS L
-
31463
EN
Journal Article
1970
01
01
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
MOLECULAR MODELING AND NMR STUDY OF
HISTDINIE AND ITS ANALOGUES AS
, PYRIDOXAL 5 '-PHOSPHATE DEPENDENT
HISTIDINE DECARBOXYLASE INHIBITORS
-
31464
EN
Journal Article
1970
01
01
Molecular modeling analysis of charge density and heat of fornation by PM3
method as well as C, H NMR and 2D-NMR measurements of histidine (substrate)
and some of its derivatives as histidine decarboxylase inhibitors were performed. It
was established that the atom, usually nitrogen, which forms internal aldimine with
pyridoxal5 -phosphate (PLP), (coenzyme), has negative and almost equal charge in
histidine and ather inhibittors. The preferred ccznfom&on of compounds with higher
inhibitory activity is calculated to be in such a form that the amino group and
imidazole ring have a dihedral angle of 60?. In this conformation, molecules are able
to form internal hydrogen bonds. In contrast, their derivatives with lower activity
have adifferent conformation. NMR measurements support our theoretical calculations
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
SYNTHESIS AND MAGNETIC
CHARACTERIZATION OF THE COPPER(I1)
DIMER DI-p- (S UB STITUTED PHENOXO) B IS-
[(2,2,6,6-TETRAMETHY L HEPTANE-3 ,5-
DIONATO) COPPER(II)]
-
31465
EN
Journal Article
1970
01
01
A number of complexes in the series (Cu LL'),, where L = [(CH,),C-CO-CH-COC(
CH,),]-I and L'= 3-(Me) C6H,0-, 2,6-(Di-Me)C6H30-, 4-(OH)C6H?O-, 3- (F)
C6H,0-, 4-(Br)C6H40-a, nd 3,s-(Dl-Me)C6H30h- ave been prepared and theu magnetic
and optical properties determined. In chloroform, the complexes exhibit two bands
in the visible and near UV regions. All complexes show room temperature magnetic
moment order of 1.0 B.M. per copper atom. The X-band ESR spectrum of solution
samples at room temperature shows typical hm=l transition. An electron release or
withdrawing group on bridging ligand causes a great change in spin-spin interaction
and is observable at Am =2 transition at half-field, which is the characteristic of
dimeric unit
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
BIVPLENT METAL COMPLEXES OF SODIUM ASCORBATE
-
31466
EN
Journal Article
1970
01
01
The mode of coordination of8 manganese(fI), cobaltm, nickel(H), copper(II),
zinc(H), lead(II) and cadmium(I1) to sodium ascorbate (NaHAsc) was investigated
using IR, UV-visible, AAS, elemental microanalyzer, conductivity, magnetic and 'M
and I3C NMR spectroscopic studies, NaNAsc is bidentate and coordination was
through the carbonyl group and the oxygen atom of carbon-2 enolic hydfoxyl group,
The complexes are mainly high spin octahedral complexes based on the magnetic
moment and spectral data.
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
LEWIS BASE ADDUCTS OF LEAD(I1)
COMPOUNDS VII *
SYNTHESIS AND STRUCTURAL
CHARACTERIZATION OF MONONUCLEAR
(DICHLORO) (1,4,10,13-TETRA-OXA-7, 16-
DIAZA-CY CLOOCTADECANE) LEAD(II)
-
31467
EN
Journal Article
1970
01
01
The reaction of PbCI, with 1,4,10,13-tetra-oxa-7, 16-diaza-cyclooctadecane (L=
C H N O ) yielded colourless crystals of LPbCI . The complex crystallizes in
monoclinic space group, C2/c, a = 7.90(2), b = 14.75(3) and C = 17.36(3) ?= ?
101.75(3)?, Z = 4 and R = 0.083 The coordination number around the lead atom is
Eight . [Pb-N, 2.36(1), 2.70(4)], [Pb-0,2.41(3)-2.57(3)], [Pb-CI, 2.51(4), 2.57(4)].
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
CHARACTERIZATION OF HIGH-SILICA
MORDENITE OBTAINED BY DIRECT
SYNTHESIS
-
31468
EN
Journal Article
1970
01
01
Three high-silica mordenite zeolites differing in SiO440, ratio were prepared by
direct synthesis without using any template. The products Si02/A120, ratio is
influenced by the starting gel composition. This ratio is increased upon ion-exchange
with NH,Cl and subsequent calcination to prepare protonic mordenite. The protonic
mordenites with Si02/A1203ra tios of 14.6,29.2 and 34.6 were characterized by X-ray
diffraction, energy dispersive X-ray microprobe analysis, scanning electron microscopy
and thermogravimetric analysis. Catalytic cracking of n-hexane was studied as a
measure of catalytic activity of protonic mordenites. Catalytic activities are expressed
as conversion percent of n-hexane. Catalysts with higher Si02/A1,03 were found to
be more active
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
SYNTHESIS OF NOVEL HETEROCYCLIC
SYSTEM
4H-IMIDAZO [ 2,l -b] PYRIDO [2,3-el [I, 3,4]
THIADIGZIM
-
31469
EN
Journal Article
1970
01
01
Diazotization of 3-amino-2-cMoro pyridine (3) in the presence of dithizone (5)
gave dphenyl-2-phenylazo-4H-pyrid[o3 ,2-e] [1,3,4] thiadiazine (6). Reaction of 2-
chloro-3-nitropyridine (2, G=H) with (5) dfordd 4-phenyl -2-phenylazo -4Hpyrido
[2,3-el [1,3,4] thiadiazine (7). Reduction of the latter with H gas in the
presence of Raney nickel gave the corresponding amino derivative (12). One pot
condensation and cyclization of the latter with phenacyl bromide gave a novel
heterocyclic system (13).
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
PERFORMANCE OF AB, ALLOYS FOR
HYDROGEN STORAGE AND HYDRIDE
ELECTRODES
-
31470
EN
Journal Article
1970
01
01
Two types of hydride electxodes are potential candidates to replace the Cd
elecsode in NilCd batteries, One is of the A type where A is a rare earth metal or
mixture thereof, and B is the transition metal. The other is commonly referred to as
A type. A , type alloys with partial substitution of the B element in A type
hydride material (Ovonic) with Co, Mn, Al, and Fe were studied (A components were Ti and Zr, the major B components were V, Ni, and Ck), The materials were prepared by arc melting and characterized using X-ray diffraction and SEM techniques. The hydrogen absorptionldesorption presswe-composition isothems for the alloys were determined, Partial substitution of the B element changes the initial, multiphase structure of the basic composition. Mn increases the plateau pressure, while addition of small amounts of A1 and Fe have positive influence. Generally, the addition of described elements does not improve the characteristics of the basic material (Ovonic). The electrochemical storage capacities of based system were in the range of 300-400 mAh/g.
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
THE RATIONAL CHARACTER TABLE OF
SPECIAL LINEAR GROUPS
-
31471
EN
Journal Article
1970
01
01
In this paper we will give the character table of the irreducible rational representations of G=SL (2, q) where q= , p prime, n>O, by using the character table and the Schur indices of SL(2,q).
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
AFFINE SUBGROUPS OF THE CLASSICAL
GROUPS AND THEIR CHARACTER DEGREES
-
31472
EN
Journal Article
1970
01
01
In this paper we describe how the degrees of the irreducible characters of the affine
subgroups of the classical groups under consideration can be found inductively. In [4]
Gow obtained certain character degrees for all of the affine subgroups of the classical
groups. We apply the method of Fischer to the above groups and, in addition to the
character degrees given in [4], we obtain some new character degrees for these
groups.
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
NUMERICAL SIMULATIONS OF THE PHASE
TRANSITIONS IN CLUSTERS
-
31473
EN
Journal Article
1970
01
01
We have studied the phase transitions in atomic clusters by molecular dynamics
simulation, assuming Lennard-Jones interatomic pair potential. Calculations are
performed by DAP parallel computer. The results are analyzed by simulating their
orientational distribution plots (dot-plot), and neutron diffraction patterns. It is shown
that all the main features of the bulk phase transitions are essentially exhibited by such
a small sample. It is seen that by cooling the sample below the melting temperature,
the atoms establish an icosahedral quasi-crystal structure with five fold symmetry.
The Mackay predicted magic numbers are confirmed by our simulation. Finally, we
conclude that in cooling the sample blow the melting point, nucleation initiates from
the central region and then propagates toward the surface
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
FISSION FRAGMENT ANGULAR ANISOTROPIES
AND INERTIA PARAMETERS
-
31474
EN
Journal Article
1970
01
01
An analysis of selected fission fragment angular distributions from helium-ion
induced fission is made using an exact theoretical expression. Theoretical anisotropies
obtained with the transition state model are compared with their corresponding values
deduced from the statistical scission model. The nuclear moment of inertia extracted
from the model calculations are compared with their estimated values from a
microscopic theory, which includes the nuclear pairing interaction [I]. Single particle
levels of Nilsson eta!. are utilized. It is found that the value of the statistical parameter,
Ko2(Ko2deff T/h2) is very sensitive to the energy gap parameter, A. The reduction of
energy gap results in an increase in the moment of inertia. The effect of pairing
interaction on the inertia parameters is illustrated and discussed
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
9
2
1998
06
01
POLARIZATION HYSTERESIS CURVE
MEASUREMENT FOR AN Au/PZT/YBCO DEVICE
BY DOUBLE PULSE TECHNIQUE
-
31475
EN
Journal Article
1970
01
01
Polarization for Au/Pb(Zr Ti )O /YBa Cu O ferroelectric capacitor has
been studied and measured by pulse method. A sequence of pulses with amplitudes
varying from 0 to 10 volts in 2 volt steps is applied and a conventional polarization
curve is obtained by integrating the charge flow from the polarization switching
induced by the voltage ramp. A value of 25?C/cm2 is measured for the saturated
polarization from the hysteresis curve. The polarization retention is also measured at
200°C for the device and the polarization change over 24 hours was about 5.7%.