1999
10
2
2
0
A SEGMENTED REGRESSION MODEL FOR
DESCRIPTION OF MICROBIAL GROWTH

2
2
A segmented regression model for the description of microbial growth has been
suggested. The model is able to predict the exponential growth, logistic growth,
logistic growth with a phase of decline, diauxic growth, microbial growth in
synchronous cultures and the oscillatory growth
1

0
0
CLONING AND EXPRESSION OF A HUMAN
INTERFERON a2 GENE IN E. COLI

2
2
The plasmid pALCA1SIFN containing cDNA that encodes the human interferon
a2b was obtained from the ATCC(no. 531667). In this system the expression of the
gene is under the control of an alcA promoter. alcA p is a specific promoter for
expression of different genes in Aspergillusfilamentous. In this plasmid the coding
region of IFN?2b is preceded by the coding region of a synthetic signal peptide. For
direct expression of the IFNa2b gene under the control of a T7/lac promotor of
pET24d(+) expression vector, three subcloning steps were carried out which resulted
in the construction of 3 new plamids. pHA1, pHA2 and pHA4 in which the IFNa2
gene is under the control of lacp, lacuv5p and T7 promoter, respectively. Another
plasrnid, pHA3, was also constiucted and is a modified version of pET24d(+).
Provided there is a synthetic signal peptide preceding the coding region of IFNa2
gene, the protein can be seen in either system, as shown by western blotting, albeit
with a different level of expression. The best product can be seen in the pHA4plasmid
with a T7 pas judged by dot and western blotting
1

0
0
FLOW INJECTIOW DETERMINATION OF
FLUORIDE BY MURTNALUMINUM REAGEM
WITH SPECTROEUORIMIETRIC DETECTION

2
2
A flow injection system is reported for the determination of fluoride based on its
effects on the fluorescence intensity of Almorin complex at pH 3.0 in ethanolwarn mixture. The effect of important parameters such as excitation and emission
wavelengths, pH, reagents concenkations, flow rate of the carrier stream, sample
injection volume, time of measurepent and interferences are reported. Cation and
anion exchange resins were used to remove interferences and to preconcenttate
fluoride ions prior to measurement. Calibration curve was linear over the range of 5 20000 ng ml of fluoride. The deteetion limit was 3 ng ml and the relative standard deviation for the determination of 100 ng ml of fluoride was ±38.7'he proposed method was used to determine ffuofide in natural water samples. R&overy was 97.5 105% for the fluoride added to the water samples. The relative standard deviation for the andysis of these samples was less than 5%.
1

0
0
THE ROLE OF AMINES AS TEMPLATES IN
DIRECTING THE STRUCTURE OF ZEOLITES

2
2
In this article, we have investigated the role of dimethylamine (DMA), tributylamine
(TBA), Triethanoleamine (TEA), Trishydroxymethylamine (TRIZMA), and
Hexamethyleneterraamine (HMTA), in the formation of zeolitic compounds. The
experiments were carried out in acidic and basic media using Si/Al< 10 and Si/A1>10.
The structure of the resulting synthetic zeolites were similar to Natro Davyne,
ammonium sodalite, analcime, and mordenite. We also recognized that HMTA in
basic media resulted in a new crystalline Compound
1

0
0
TRIPHENYLPHOSPHINE CATALYZED
AROMATIC ELECTROPHILIC SUBSTITUTION
OF 2HYDROXYACETOPHENONE MEDIATED
BY VINYLTRIPHENYLPHOSPHONIUM CATION

2
2
Protonation of the highly reactive 1:l intermediate produced in the reaction
between triphenylphosphine and dimethyl acetylenedicarboxylate by 2
hydroxyacetophenone leads to vinyltriphenylphosphonium salt, which undergoes
aromatic electrophilic substitution reaction with the conjugate base to produce
compounds 4,5, and 6 in 1 : 1.2:0.5 ratios
1

0
0
THE ALMOST SURE CONVERGENCE OF
WEIGHTED SUMS OF NEGATIVELY
DEPENDENT RANDOM VARIABLES

2
2
In this paper we study the almost universal convergence of weighted sums
for sequence {x ,n } of negatively dependent (ND) uniformly bounded random variables, where a, k21 is an may of nonnegative real numbers such that 0(k ) for every ?> 0 and Ex  F  =0 , F = ?(X ,…, X ) for every n>l.
1

0
0
PERIODIC SOLUTIONS OF CERTAIN THREE
DIMENSIONAL AUTONOMOUS SYSTEMS

2
2
There has been extensive work on the existence of periodic solutions for nonlinear
second order autonomous differantial equations, but little work regarding the third
order problems. The popular PoincareBendixon theorem applies well to the former
but not the latter (see [2] and [3]). We give a necessary condition for the existence of
periodic solutions for the third order autonomous systems, This may become useful
in further investigations. Our claims are proved and supported by certain examples.
1

0
0
THE STEFAN PROBLEM WITH KINETIC
FUNCTIONS AT THE FREE BOUNDARY

2
2
This paper considers a class of onedimensional solidification problem in which
kinetic undercooling is incorporated into the temperature condition at the interface.
A model problem with nonlinear kinetic law is considered. The main result is an
existence theorem. The mathematical effects of the kinetic term are discussed
1

0
0
A NUMERICAL RENORMALIZATION GROUP
APPROACH FOR AN ELECTRONPHONON
INTERACTION

2
2
A finite chain calculation in terms of Hubbard Xoperators is explored by setting
up a vibronic Harniltonian. The model conveniently transformed into a form so that
in the case of strong coupling a numerical renormalization group approach is
applicable. To test the technique, a one particle Green function is calculated for the
model Harniltonian
1

0
0
OPTICAL PROPERTIES OF COEVAPORATED
THIN FILMS OF BINARY Bi 0Te 0 AND
Bi 0 V 0 SYSTEMS

2
2
Thin films of binary Bi 0 TeO and Bi 0 V 0 systems were prepared by the
thermal coevaporation technique in a vacuum at room temperature. The optical
absorption edge of these systems are studied in the wavelength of 200800 nm using
a PERKINELMER uv/Vis spectrophotometer. It is found that the value of n=3/2 in
the DavisMott equation is best fitted for the fundamental absorption edge for these
materials. It is also found that the optical energy gap (E ) for the Bi o  v o system
lies between 0.65 and 3.5 eV. and for the Bi 0 TeO system between 0.95 and
3.25 eV. depending on the film composition. The exponential behaviour of the
absorption coefficient with photon energy for the systems under invesgiation are
verified as suggested by Urbach
1

0
0