bluuebunny/crossref_metadata_2025 huggingface dataset:
Mean number of real zeros of a random trigonometric polynomial. III
Authors: Wilkins J. Ernest , Souter Shantay A.
Published: March 2007

If a1, a2, …, an are independent, normally distributed random variables with
mean 0 and variance 1, and if vn is the mean number of zeros on the interval
(0, 2π) of the trigonometric polynomial a1cosx + 2½a2cos2x + …+n½ancosnx,
then vn = 2−½{(2n + 1) + D1 + (2n+1)−1D2 + (2n+1)−2D3} + O{(2n+1)−3}, in which D1 = −0.378124, , D3 = 0.5523. After tabulation of
5D values of vn when n = 1(1)40, we find that the approximate formula for vn,
obtained from the above result when the error term is neglected, produces 5D
values that are in error by at most 10−5 when n ≥ 8, and by only about 0.1%
when n = 2.
Invariant probabilities for Feller‐Markov chains
Authors: Hernández-Lerma Onésimo , Lasserre Jean B.
Published: March 2007

We give necessary and sufficient conditions for the existence of invariant
probability measures for Markov chains that satisfy the Feller property.
Oscillation criteria for nonlinear inhomogeneous hyperbolicequations with distributed deviating arguments
Authors: Liu Xinzhi , Fu Xilin
Published: March 2007

This paper investigates the oscillatory properties of solutions of nonlinear
inhomogeneous hyperbolic equations with distributed deviating arguments subject
to two different boundary conditions. Several oscillation criteria are establishing
employing Green′s Theorem and certain differential inequalities. An example is
also given.
Sufficient conditions for oscillations of all solutions of aclass of impulsive differential equations with deviating argument
Authors: Bainov D. D. , Dimitrova M. B.
Published: March 2007

Sufficient conditions are found for oscillation of all solutions of impulsive
differential equation with deviating argument.
On certain classes of variational inequalities and relatediterative algorithms
Authors: Noor Muhammad Aslam
Published: March 2007

In this paper, we introduce and study some new classes of variational inequalities and Wiener‐Hopf equations. Essentially using the projection technique, we
establish the equivalence between the multivalued general quasi‐variational inequalities and the multivalued implicit Wiener‐Hopf equations. This equivalence
enables us to suggest and analyze a number of iterative algorithms for solving
multivalued general quasi‐variational inequalities. We also consider the auxiliary
principle technique to prove the existence of a unique solution of the variational‐like inequalities. This technique is used to suggest a general and unified iterative
algorithm for computing the approximate solution. Several special cases which
can be obtained from our main results are also discussed. The results proved in
this paper represent a significant refinement and improvement of the previously
known results.
Generalized practical stability results by perturbing Lyapunov functions
Authors: Stutson Donna , Vatsala A. S.
Published: March 2007

It is known that practical stability is neither stronger nor weaker than
Lyapunov stability. In this paper we combine perturbing Lyapunov technique
with stability in terms of two measures to obtain nonuniform practical stability
results under weaker assumptions. We also use comparison methods to obtain
these results.
A non‐regenerative model of a redundant repairable system: bounds for the unavailability and asymptotical insensitivity to the lifetime distribution
Authors: Kovalenko Igor N.
Published: March 2007

In this paper we investigate steady state reliability parameters of an F : r‐out‐of‐N redundant repairable system with m(1 ≤ m ≤ r − 1) repair channels in light
traffic conditions. Such a system can also be treated as a closed queueing network of a simple kind. It includes two nodes, with infinite number of channels
and m channels, respectively. Each of the N customers pass cyclically from one
node to the other; the service time distributions are of a general form for both the
nodes.

It is an N‐component system with a general distribution A(t) of free‐of‐failure periods of the components is considered. Failed components are repaired by
an m‐channel queueing system with a general distribution B(t) of repair times.
The system is assumed to be failed if and only if the number of failed
components is at least r. (Only the rather difficult case r ≥ m + 1 is considered.)

Let μ be the intensity of the stationary point process of the occurrences of
(partial) busy periods within which systems failures happen at least once, and let
Q be the steady‐state unavailability of the system.

Two‐sided bounds are established for Q and μ based on the behavior of the renewal rate of an auxiliary renewal process. The bounds are used for deriving
some asymptotical insensitivity properties in light traffic conditions.
GIX/MY/1 systems with resident server and generally distributed arrival and service groups
Authors: Dukhovny Alexander
Published: March 2007

Considered are bulk systems of GI/M/1 type in which the server stands by
when it is idle, waits for the first group to arrive if the queue is empty, takes customers up to its capacity and is not available when busy. Distributions of arrival
group size and server′s capacity are not restricted. The queueing process is analyzed via an augmented imbedded Markov chain. In the general case, the generating function of the steady‐state probabilities of the chain is found as a solution of
a Riemann boundary value problem. This function is proven to be rational when
the generating function of the arrival group size is rational, in which case the solution is given in terms of roots of a characteristic equation. A necessary and sufficient condition of ergodicity is proven in the general case. Several special cases
are studied in detail: single arrivals, geometric arrivals, bounded arrivals, and an
arrival group with a geometric tail.
Nonparametric density estimators based on nonstationaryabsolutely regular random sequences
Authors: Harel Michel , Puri Madan L.
Published: March 2007

In this paper, the central limit theorems for the density estimator and for the
integrated square error are proved for the case when the underlying sequence of
random variables is nonstationary. Applications to Markov processes and ARMA
processes are provided.
A probabilistic approach to the trace at the boundary forsolutions of a semilinear parabolic partial differential equation
Authors: Gall Jean-François Le
Published: March 2007

We use the path‐valued process called the “Brownian snake” to investigate
the trace at the boundary of nonnegative solutions of a semilinear parabolic partial differential equation. In particular, we characterize possible traces and in
dimension one we prove that nonnegative solutions are in one‐to‐one correspondence with their traces at the origin. We also provide probabilistic representations for various classes of solutions.

This article is dedicated to the memory of Roland L. Dobrushin.
Itô′s formula with respect to fractional Brownian motion and its application
Authors: Dai W. , Heyde C. C.
Published: March 2007

Fractional Brownian motion (FBM) with Hurst index 1/2 < H < 1 is not a
semimartingale. Consequently, the standard Itô calculus is not available for
stochastic integrals with respect to FBM as an integrator if 1/2 < H < 1. In this
paper we derive a version of Itô′s formula for fractional Brownian motion. Then,
as an application, we propose and study a fractional Brownian Scholes stochastic
model which includes the standard Black‐Scholes model as a special case and is
able to account for long range dependence in modeling the price of a risky asset.
This article is dedicated to the memory of Roland L. Dobrushin.
Limiting behavior of the perturbed empirical distribution functions evaluated at U‐statistics for strongly mixing sequences of random variables
Authors: Sun Shan , Chiang Ching-Yuan
Published: March 2007

We prove the almost sure representation, a law of the iterated logarithm
and an invariance principle for the statistic for a class of strongly
mixing sequences of random variables {Xi, i ≥ 1}. Stationarity is not
assumed. Here is the perturbed empirical distribution function and Un
is a U‐statistic based on X1, …, Xn.
Mark Alexandrovich Krasnosel′skii, (April 27, 1920 ‐ February 13, 1997)
Authors: Asarin E. A. , Bakhtin I. A. , Bobylev N. A. , Bondarenko V. A. , Burd V. Sh. , Chernorutskii V. V. , Gorin E. A. , Kozyakin V. S. , Krasnosel′skii A. M. , Kurzhanskii A. B. , Kuznetsov N. A. , Levin A. Yu. , Mukhamadiev E. M. , Perov A. I. , Pokorny Yu. V. , Pokrovskii A. V. , Rachinskii D. I. , Sadovsky B. I. , Strygin V. V. , Tsypkin Ya. Z. , Yemel′yanov S. V. , Zabreiko P. P.
Published: March 2007

On February 13, 1997, the world famous mathematician, Mark Alexandrovich Krasnosel′skii, died unexpectedly. This article gives a brief overview
of his life and research.
Quadratically converging iterative schemes for nonlinear Volterra integral equations and an application
Authors: Pandit Sudhakar G.
Published: March 2007

A generalized quasilinear technique is employed to derive iterative schemes
for nonlinear Volterra integral equations under various monotonicity and
convexity (concavity) conditions on the kernels. The iterates in the
schemes are linear, and converge monotonically, uniformly and quadratically to the unique solution. An application to a boundary‐layer theory problem and examples illustrating the results are presented.
Analysis of the asymmetrical shortest two‐server queueing model
Authors: Cohen J. W.
Published: March 2007

This study presents the analytic solution for an asymmetrical two‐server
queueing model for arriving customers joining the shorter queue for the
case of Poisson arrivals and negative exponentially distributed service
times. The bivariate generating function of the stationary joint distribution of the queue lengths is explicitly determined.

The determination of this bivariate generating function requires a construction of four generating functions. It is shown that each of these functions is the sum of a polynomial and a meromorphic function. The poles
and residues at the poles of the meromorphic functions can be simply calculated recursively; the coefficients of the polynomials are easily found, in
particular, if the asymmetry in the model parameters is not excessively
large. The starting point for the asymptotic analysis for the queue lengths
is obtained. The approach developed in the present study is applicable to
a larger class of random walks modeling asymmetrical two‐dimensional
queueing processes.
The stationary G/G/s queue with non‐identical servers
Authors: Gall Pierre Le
Published: March 2007

We extend a recently developed factorization method to the case of the
G/G/s queue with non‐identical servers, by presenting three simple properties which lead to a simple numerical calculation method. We compare
our results with those determined by classical Markovian (phase) methods
in the case of the symmetrical M/G/s queue, and for the mean queueing
delay we compare with results given by traffic simulation.
Oscillation criteria for high order delay partial differentialequations
Authors: Liu Xinzhi , Fu Xilin
Published: March 2007

This paper studies a class of high order delay partial differential equations.
Employing high order delay differential inequalities, several oscillation criteria are established for such equations subject to two different boundary
conditions. Two examples are also given.
Sample correlations of infinite variance time series models: an empirical and theoretical study
Authors: Cohen Jason , Resnick Sidney , Samorodnitsky Gennady
Published: March 2007

When the elements of a stationary ergodic time series have finite variance
the sample correlation function converges (with probability 1) to the theoretical correlation function. What happens in the case where the variance
is infinite? In certain cases, the sample correlation function converges in
probability to a constant, but not always. If within a class of heavy tailed
time series the sample correlation functions do not converge to a constant,
then more care must be taken in making inferences and in model selection
on the basis of sample autocorrelations. We experimented with simulating
various heavy tailed stationary sequences in an attempt to understand
what causes the sample correlation function to converge or not to converge
to a constant. In two new cases, namely the sum of two independent moving averages and a random permutation scheme, we are able to provide
theoretical explanations for a random limit of the sample autocorrelation
function as the sample grows.
Volterra and Urysohn integral equations in Banach spaces
Authors: O′Regan Donal
Published: March 2007

We use topological methods to present existence principles and theory for
integral equations in Banach spaces.
A G‐KKM type theorem and its applications to minimax inequalities on G‐convex spaces
Authors: Chowdhury Mohammad S. R.
Published: March 2007

A G‐KKM type theorem is obtained on G‐convex spaces. As application,
a generalization of Ky Fan′s minimax inequality to non‐compact sets on
G‐convex spaces is first obtained. As special cases of this minimax
inequality, some new minimax inequalites are obtained. Four fixed point
theorems and four equivalent formulations of the second minimax
inequality are also obtained.
Averaging and stability of quasilinear functional differential equations with Markov parameters
Authors: Katafygiotis Lambros , Tsarkov Yevgeny
Published: March 2007

An asymptotic method for stability analysis of quasilinear functional differential equations, with small perturbations dependent on phase coordinates
and an ergodic Markov process, is presented. The proposed method is
based on an averaging procedure with respect to: 1) time along critical
solutions of the linear equation; and 2) the invariant measure of the
Markov process. For asymptotic analysis of the initial random equation
with delay, it is proved that one can approximate its solutions (which are
stochastic processes) by corresponding solutions of a specially constructed
averaged, deterministic ordinary differential equation. Moreover, it is
proved that exponential stability of the resulting deterministic equation is
sufficient for exponential p‐stability of the initial random system for all
positive numbers p, and for sufficiently small perturbation terms.
Continuity of fuzzy multifunctions
Authors: Beg Ismat
Published: March 2007

We define the upper and lower inverse of a fuzzy multifunction and prove
basic identities. Then by using these ideas we introduce the concept of
hemicontinuity and obtain many interesting properties of lower and upper
hemicontinuous fuzzy multifunctions. Using the notion of hemicontinuity,
we also characterize closed and open fuzzy mappings.
Generic stability of the spectra for bounded linear operators on Banach spaces
Authors: Qun Luo
Published: March 2007

In this paper, we study the stability of the spectra of bounded linear
operators B(X) in a Banach space X, and obtain that their spectra are
stable on a dense residual subset of B(X).
An MX/GI/1/N queue with close‐down and vacation times
Authors: Frey Andreas , Takahashi Yoshitaka
Published: March 2007

An MX/GI/1/N finite capacity queue with close‐down time, vacation time
and exhaustive service discipline is considered under the partial batch
acceptance strategy as well as under the whole batch acceptance strategy.
Applying the supplementary variable technique the queue length distribution at an arbitrary instant and at a departure epoch is obtained under
both strategies, where no assumption on the batch size distribution is
made. The loss probabilities and the Laplace‐Stieltjes transforms of the
waiting time distribution of the first customer and of an arbitrary customer of a batch are also given. Numerical examples give some insight into
the behavior of the system.
Existence and uniqueness of a classical solution to a functional‐differential abstract nonlocal Cauchy problem
Authors: Byszewski Ludwik
Published: March 2007

The aim of this paper is to investigate the existence and uniqueness of a
classical solution to a functional‐differential abstract nonlocal Cauchy problem in a general Banach space. For this purpose, a special kind of a mild
solution is introduced and the Banach contraction theorem and a modified
Picard method are applied.
Periodic in distribution solution for a telegraph equation
Authors: Dorogovtsev A. Ya.
Published: March 2007

In this paper we study an abstract stochastic equation of second order and
stochastic boundary problem for the telegraph equation in a strip. We
prove the existence of solutions, which are d‐periodic (periodic in distribution) random processes.
A note on multivalued differential equations on proximate retracts
Authors: O′Regan Donal
Published: March 2007

This paper discusses viable solutions for differential inclusions in Banach
spaces. Existence will be established in two steps. In step 1, a nonlinear
alternative of Leray‐Schauder type [8] for maps with closed graphs will be
used to establish a variety of existence principles for the Cauchy differential inclusion. Step 2 involves using the results in step 1 together with
some tricks involving the Bouligand cone (and sometimes the Urysohn
function) so that new existence criteria can be established for multivalued
differential equations on proximate retracts.
On the H‐function
Authors: Kilbas Anatoly A. , Saigo Megumi
Published: March 2007

This paper is devoted to the study of the H‐function as defined by the
Mellin‐Barnes integral
,
where the function is a certain ratio of products of the Gamma‐functions with the argument s and the contour ℒ specially chosen. The
conditions for the existence of are discussed and explicit power
and power‐logarithmic series expansions of near zero and infinity
are given. The obtained results define more precisely the known results.
Random mappings with a single absorbing center and combinatorics of discretizations of the logistic mapping
Authors: Klemm A. , Pokrovskii A.
Published: March 2007

Distributions of basic characteristics of random mappings with a single absorbing center are calculated. Results explain some phenomena occurring
in computer simulations of the logistic mapping.
Nonconvex evolution inclusions generated by time‐dependent subdifferential operators
Authors: Arseni-Benou Kate , Halidias Nikolaos , Papageorgiou Nikolaos S.
Published: March 2007

We consider nonlinear nonconvex evolution inclusions driven by time‐varying subdifferentials ∂ϕ(t, x) without assuming that ϕ(t.) is of compact
type. We show the existence of extremal solutions and then we prove a
strong relaxation theorem. Moreover, we show that under a Lipschitz condition on the orientor field, the solution set of the nonconvex problem is
path‐connected in C(T, H). These results are applied to nonlinear feedback control systems to derive nonlinear infinite dimensional versions of
the “bang‐bang principle.” The abstract results are illustrated by two
examples of nonlinear parabolic problems and an example of a differential
variational inequality.
The solution of an open problem given by H. Haruki and T. M. Rassias
Authors: Kim Bara
Published: March 2007

Haruki and Rassias [1] generalized the Poisson kernel in two dimensions
and discussed integral formulas for each case. They presented an open problem for an integral formula. In this paper, we give a solution to that problem.
On nonlocal problems for ordinary differential equations and on a nonlocal parabolic transmission problem
Authors: Denche M.
Published: March 2007

In the present paper we study nonlocal problems for ordinary differential
equations with a discontinuous coefficient for the high order derivative.
We establish sufficient conditions, known as regularity conditions, which
guarantee the coerciveness for both the space variable and the spectral
parameter, as well as guarantee the completeness of the system of root
functions. The results obtained are then applied to the study of a nonlocal
parabolic transmission problem.
A simplified proof of a conjecture of D. G. Kendall concerning shapes of random polygons
Authors: Kovalenko Igor N.
Published: March 2007

Following investigations by Miles, the author has given a few proofs of a
conjecture of D.G. Kendall concerning random polygons determined by the
tessellation of a Euclidean plane by an homogeneous Poisson line process.
This proof seems to be rather elementary. Consider a Poisson line process
of intensity λ on the plane ℛ2 determining the tessellation of the plane
into convex random polygons. Denote by Kω a random polygon containing the origin (so‐called Crofton cell). If the area of Kω is known to equal
1, then the probability of the event {the contour of Kω lies between two
concentric circles with the ratio 1 + ϵ of their ratio} tends to 1 as λ → ∞.
Two service units with interference in the access to servers
Authors: Lillo Rosa E. , Neuts Marcel F.
Published: March 2007

We examine the service mechanism of two queueing models with two units
in tandem. In the first model, customers who complete service in Unit 1
must wait in an intermediate buffer until the ongoing service in Unit II
ends. In the second model, jobs can be pre‐positioned in an intermediate
buffer to await service in Unit II. Under the assumption of phase‐type service times, the steady‐state regime of the service system is studied in detail.

The models are inspired by the gas pump model of A.B. Clarke and
by phenomena observed in cafeteria lines and certain manufacturing systems. However, their primary interest may lie in the methodology of their
exceptionally tractable analysis. We derive formulas for the throughput
and other quantities by using the familiar PH‐formalism. These formulas
turn out to be unusually transparent and have probabilistic interpretations
that do not depend on the PH assumptions. These interpretations therefore also hold for general service time distributions. The methodology is
general and can be applied to other systems with interactions between
servers. The models also present interesting algorithmic problems of didactic interest.
Effects of chromophore interaction in photophysics and photochemistry of cyanine dyes
Authors: Tatikolov A. S. , Krasnaya Zh. A. , Shvedova L. A. , Kuzmin V. A.
Published: March 2007

Spectral and fluorescent properties of ketocyanine dyes (polyenic bis‐ω, ω′‐aminoketones) and
cation‐anionic polymethine dyes of various structures were studied. The symmetric ketocyanines were shown
to have a long‐wavelength absorption band bathochromically shifted in comparison with that of the asymmetric
ketocyanines with the same total length of the polyenic chain. The nonlinear ketocyanines exhibit
the additional short‐wavelength band in their absorption spectra, which can be more intense than the longwavelength
band. The absorption spectra of ion pairs of cation‐anionic dyes with overlapping cation and
anion bands contain a new intense short‐wavelength band inactive in fluorescence excitation. These spectral
peculiarities are explained on the basis of chromophore interaction model. It has also been shown that the
T1 levels of ketocyanine chromophores do not essentially interact with each other in a ketocyanine molecule
in nonpolar solvents; in polar solvents this interaction becomes appreciable due to lowering the potential
barrier for conjugation.
The structure and characteristics of photochromic dithienylethenes
Authors: Krayushkin M. M. , Vorontsova L. G. , Uzhinov B. M.
Published: March 2007

The data on X‐ray diffraction analysis for dihetarylethenes with perfluorocyclopentene (F), maleic
anhydride (M) and cyclobutenedione (S) bridges between thienyl fragments were summarized and their photochromic
properties were discussed. It was established that benzoxazole and benzothiazole substituents
in position 5 of thienyl rings are coplanar to the plane of thiophene cycles. Thienyl fragments in A form of
all dithienylethenes are considerably turned relative to the plane of bridging cycle. It means that there is no
conjugation between π‐electrons of aromatic heterocycles and double bond of the bridge.

Flattening of molecule frameworkand the envelope conformation of thienyl cycles because of aromaticity
loss are characteristic features of the form B structure with F‐bridge. In all cases (excluding the compounds
with alkylthio substituents in position 2 of thiophene cycle) the photochromic transition A → B is observed
independently of different nature and structure of functional groups.
A fulleropyrrolidine with two oligophenylenevinylene substituents: synthesis, electrochemistry and photophysical properties
Authors: Armaroli Nicola , Barigelletti Francesco , Ceroni Paola , Eckert Jean-François , Nierengarten Jean-François
Published: March 2007

A fullerene derivative in which two oligophenylenevinylene (OPV) groupsare attached to C60 through a pyrrolidine ring has been prepared and photophysical studies in CH2CL2 solution show that photoinduced
energy transfer from the OPV moieties to C60 occurs, and not electron transfer. On passing to a
more polar solvent such as benzonitrile, again no evidence of electron transfer is found.
The surprising photochemistry of sultams related to saccharin
Authors: Döpp Dietrich
Published: March 2007

The known light induced reactions of sulfonamides and sultams are in most (but not all) cases
initiated by S–N homolysis. Sulfur dioxide release may be a consequence of this primary process. In the
author′s laboratory three hitherto unexplored photoreactions of saccharin‐derived sultams have been investigated:
(i) a novel formal oxygen shift from sulfur to nitrogen generating upto now unknown cyclic
N‐hydroxysulfinamides; (ii) a condensative dimerization of 2,3‐dihydro‐1,2‐ benzoisothiazole 1,1‐dioxide
generating a new cleft molecule, and (iii) a facile allylic skeletal rearrangement of a pyrrolo‐anellated dihydro‐
1,2‐benzoisothiazole. At least in the latter two cases an initial S–N‐homolysis seems to be vital for the processes
observed, whereas in the first case some ambiguity remains with respect to the first step. Scope and
limitations are discussed and rationales for the conversions observed are presented, with special emphasis
on structure proof by X‐ray crystal structure determinations. All reactions discussed have to be treated
within the wider context of current sulfonamide and sultam photochemistry.
Ion‐induced luminescence control in pyrene‐tethered bipyridine ligand systems
Authors: Leroy S. , Soujanya T. , Sohna J.-E. Sohna , Fages F.
Published: March 2007

A series of tunable fluorophores combining the pyrene nucleus and the 2, 2′‐bipyridine ligand
unit are presented. They were designed to display luminescence tuning upon metal ion complexation. The
effects are strongly affected by the nature of the covalent bridge linking the two subunits. The intensity, the
color, but also the lifetime of the luminescence emission are features that can be finely modulated depending
on the molecular structure, the nature of the solvent and the metal cation. This approach provides accesss
to a new class of photosensitive receptors for applications in chemosensing, optoelectronic, or solar energy
storage and conversion.
Oxidation of PAHs in water solution by ozone combined with ultraviolet radiation
Authors: Ledakowicz Stanisław , Miller Jacek S. , Olejnik Dorota
Published: March 2007

The oxidation of three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BAP), chrysene
(CHR) and fluorene (FLU) in aqueous solution using ozone assisted by UV radiation was investigated. The
influence of pH of the reaction mixture, ozone concentration and the presence of a radical scavenger on the
reaction rate was determined. The highest rate of PAHs disappearance was achieved in acidic solutions. The
radical scavenger‐tert‐butanol, effectively inhibited the rate of BAP and CHR destruction but had a slight
influencein thecaseof FLU. Therateconstants of direct reaction of PAHs with ozonewe recalculate d using
our earlier investigations and they were equal to 6.8 × 104; 6.9 × 103 and 62M-1s-1 for BAP, CHR and FLU,
respectively. The contributions of direct ozonolysis, photolysis and radical reaction to PAHs oxidation in O3/UV system were evaluated.
Photophysical and photochemical applications of femtosecond time‐resolved transient absorption spectroscopy
Authors: Foggi Paolo , Bussotti Laura , Neuwahl Frederik V. R.
Published: March 2007

The aim of this paper is to provide the main pieces of information concerning the application of
transient absorption (TA) spectroscopy with sub‐picosecond laser pulses. A description of the experimental
apparatus and of some detection schemes are included together with the most common mathematical formulas
utilized to analyze the signals. The results, recently obtained in our laboratory and presented here,
concern the investigation of the excited state dynamics of simple molecular systems. Examples of the measurements
of the relaxation processes occurring in the lowest excited states of some aromatic molecules will
be discussed in order to show the potentiality of the technique.
Photobehaviour of Z‐1,2‐di‐(3′‐methoxynaphth‐2′‐yl)ethene as model compound of biphotochromic supermolecules with Z‐ethenic bridge
Authors: Ortica F. , Levi D. , Brun P. , Guglielmetti R. , Favaro G. , Mazzucato U.
Published: March 2007

This work is part of a research project aimed at investigating the behaviour of biphotochromic
supermolecules where two photochromic units of the spirooxazine or chromene series are linked through
a conjugated or unconjugated spacer. Preliminary investigations showed that the compounds with ethane,
acetylene or ester bridges behave as classical photochromes while those with an ethene bridge showed good
coloration accompanied by unusual thermal irreversibility at room temperature. The temperature effect
on the spectral behaviour allowed such irreversibility to be explained by the occurrence of a cyclization
process at the central ethene bond, typical of Z‐diarylethenes. To better understand this photobehaviour, a
deep investigation of a model molecule, Z‐1,2‐di‐(3′‐methoxynaphth‐2′‐yl)ethene, was carried out. This paper
reports the results obtained on the model molecule and two biphotochromic systems containing benzochromene
and spirooxazine units.
Photocatalytic degradation of aqueous organic solvents in the presence of hydroxyl radical scavengers
Authors: Mehrvar Mehrab , Anderson William A. , Moo-Young Murray
Published: March 2007

Tetrahydrofuran (THF) and 1,4‐dioxane (DIOX) are two common solvents that are found in
contaminated groundwater. Photocatalytic degradation of these two organic solvents in water was studied
in the presence of carbonate and bicarbonate, which are hydroxyl radical scavengers. The reactions were
performed in an annular slurry photoreactor. It was found that bicarbonate and carbonate ions acted as
hydroxyl radical scavengers and slowed down the DIOX degradation rate but did not significantly affect
the THF degradation rate. The slight enhancement in the THF degradation rate in the presence of sodium
bicarbonate may be due to the increase in pH. In addition, it appears that bicarbonate and carbonate ions
were reduced to other organic species during the photocatalytic reaction.
Kinetics and mechanisms of EDTA photocatalytic degradation with TiO2 under different experimental conditions
Authors: Babay Paola A. , Emilio Carina A. , Ferreyra Rosana E. , Gautier Eduardo A. , Gettar Raquel T. , Litter Marta I.
Published: March 2007

The photocatalytic degradationof EDTA over TiO2 has been analyzed to establish the influence
of oxidants on the reaction rate, the nature of the intermediates and the kinetic regime. Degussa P‐25 suspensions
containing EDTA at initial pH 3 in different concentrations were irradiated under near UV light.
A Langmuirian behavior was observed. O2 at saturation concentrations was found to be crucial for EDTA
degradation. The rapid depletion of EDTA was not accompanied by a corresponding TOC decrease, indicating
formation of refractory intermediates. An enhancement in TOC reduction could be achieved by keeping pH
constant or by hydrogen peroxide addition. Addition of Fe(III) caused a remarkable increase on the initial
rate of EDTA consumption and also on TOC decrease. Changes in both parameters clearly increased under
the simultaneous addition of Fe(III) and H2O2, until limiting values.

Some of the possible intermediates of EDTA degradation were evaluated in the filtered solution. So far,
glycine, ethylenediamine, ammonium, formaldehyde, and formic, iminodiacetic, oxalic, oxamic, glycolic and
glyoxylic acids have been identified in different proportions, depending on the experimental conditions.
Different degradationpathways are proposed. Inthe presence of Fe(III), photo‐Fenton reactions would contribute
also to the degradation process.
The phthalocyanines applications in photodynamic therapy investigated by time‐resolved and steady‐state photothermal methods
Authors: Frackowiak Danuta , Wiktorowicz Krzysztof , Planner Alfons , Waszkowiak Aneta , Ion Rodica-Mariana
Published: March 2007

The time‐resolved photothermal methods are used in order to establish the yield of intersystem
(singlet‐triplet) crossing of dyes that are candidates for the application in photodynamic therapy. It is known
that molecules with long living triplet state cause efficient photosensitization by direct interaction with the
cells or by singlet oxygen generation.

The steady state photoacoustic spectra enables one to establish the dye incorporation into cells.

Both methods were applied to several phthalocyanines and the results gathered by photothermal measurements
were compared with the results obtained by means of other methods.The six investigated dyes were
compared.
Comparison of the photoactivities of two commercial titanium dioxide powders in the degradation of 1,4‐dioxane
Authors: Mehrvar M. , Anderson W. A. , Moo-Young M.
Published: March 2007

Two different commercial photocatalysts, Degussa P25 and Hombikat UV 100, were used to degrade
1,4‐dioxane photocatalytically in an annular slurry photoreactor. The optimum photocatalyst loading
for Degussa P25 was found to be 1.5 g L-1 while for Hombikat UV 100 was between 3.0 − 4.0 g L-1. The photoactivity
of Degussa P25 is higher than that of Hombikat at lower photocatalyst loadings whereas it is lower
at higher photocatalyst loadings. This was found both experimentally and also by mathematical modeling of
the radiation within the photoreactor zone. The photoactivity of UV 100 titanium dioxide was found to be
twice that of Degussa P25 at optimum loadings.
Photocatalytic degradation of metoxuron in aqueous suspensions of TiO2. Analytical and kinetic studies
Authors: Khodja Amina Amine , Lavedrine Bernadette , Richard Claire , Sehili Tahar
Published: March 2007

The photocatalytic degradation of metoxuron [3‐(3‐chloro‐4‐methoxyphenyl)‐1,1‐dimethylurea]
in aqueous suspensions of TiO2 was investigated. Several intermediate photoproducts were identified using
NMR and MS techniques. Oxidation or removal of the methyl of terminal nitrogen and ring hydroxylation were
found to occur. 2‐Propanol was shown to decrease the rate of photocatalytic degradation, inhibiting partly
ring hydroxylation and completely reactions on terminal nitrogen. In contrast, basification of the suspensions
accelerated the degradation significantly. Degussa P25 TiO2 was found to exhibit a higher photocatalytic
activity than Millennium TiO2 in spite of a generally smaller specific surface area. Within the Millennium
TiO2 series, the photocatalytic efficiency increased with the specific surface area.
Discharge photoelectrocatalytic system for the degradation of aromatics
Authors: Kim Hak-Soo , Lee Eun-Ah , Lee Ju-Hyeon , Han Chul-Hee , Ha Jin-Wook , Shul Yong-Gun
Published: March 2007

We have introduced the discharge photoelectrocatalytic system, in which TiO2 thin film coating on aluminum plate is subjected simultaneously to both UV irradiation and high voltages in excess of
3000 volts. Due to high voltages O3 is generated; however, efficient removal of O3 is observed in this photoelectrocatalytic
system. In terms of the removal of volatile organic compounds (VOCs), the discharge photoelectrocatalytic
system has been applied to the removal of aromatic compounds such as benzene and
toluene. Based on the experimental data, the rates of the removal of these compounds in this system are
higher compared to either the discharge—only system (without the photocatalyst) or the photocatalyst—only system (without high voltage discharge), and the higher rates of degradation of these compounds in the
photoelectrocatalytic system are attributed to the reduced rate of electron‐hole recombination in TiO2.
Pressure dependence of electron‐ and hole‐consuming reactions in photocatalytic water splitting on Pt/TiO2 studied by time‐resolved IR absorption spectroscopy
Authors: Yamakata Akira , Ishibashi Taka-aki , Onishi Hiroshi
Published: March 2007

The decay kinetics of photogenerated electrons in the water splitting reaction on a Pt/TiO2 photocatalyst was studied by time‐resolved IR absorption spectroscopy. The decay of the photogenerated
electrons within 2 μs was decelerated when the catalyst was exposed to water vapor. The holes were consumed
by the reaction with water instead of by the recombination with the electrons. On the other hand,
the decay at 10–900 μs was accelerated by the exposure. The electrons were consumed by the reaction with
water. The rate of the hole‐consuming reaction was independent of the pressure of water vapor, whereas
that of the electron‐consuming reaction increased with the pressure from 1 to 10 Torr. The different pressure
dependences indicate different reactants involved in the oxidative and reductive reactants.
In‐situ investigations of the photoluminescence properties of SiO2/TiO2 binary and Boron‐SiO2/TiO2 ternary oxides prepared by the sol‐gel method and their photocatalytic reactivity for the oxidative decomposition of trichloroethylene
Authors: Jung Kyeong Youl , Park Seung Bin , Matsuoka Masaya , Anpo Masakazu
Published: March 2007

Photoluminescence behavior of TiO2, SiO2/TiO2 binary and Boron‐SiO2/TiO2 ternary oxides prepared by the sol‐gel method was investigated. The differences in their photocatalytic reactivities of TiO2‐based photocatalysts were interpreted in terms of the relationship of the difference in their photoluminescence
characteristics. The addition of SiO2 into TiO2 matrix induced new photoluminescence sites, which were due to anchored titanium oxide species (i.e., the formation of Ti–O–Si bonds) located on the surface. The photoluminescence was found to be very sensitive to the presence of oxygen. These new photoluminescence
completely disappeared by the addition of boron into SiO2/TiO2 binary oxide, since the emitting sites having a Ti–O–Si bond were destroyed and the new sites having B–O–Ti or Si–O–B bonds were
constructed on the surface, being in agreement with the results obtained by FT‐IR measurements. For all
TiO2‐based photocatalysts, a significant quenching of photoluminescence was observed by the addition of
oxygen. It was found that the photocatalytic reactivity of TiO2‐based photocatalysts for the decomposition of trichloroethylene was clearly associated with their relative quenching efficiencies of photoluminescence; photocatalyst showing high quenching efficiency exhibited a high photocatalytic reactivity.
Iron(III) photoinduced degradation: Catalytic method for 4 ,4′‐diaminostilbene‐2 ,2′‐disulfonic acid removal from water
Authors: Wong-Wah-Chung Pascal , Mailhot Gilles , Bolte Michèle
Published: March 2007

The Fe(III)‐photoinduced degradation of 4 ,4′‐diaminostilbene‐2 ,2′‐disulfonic acid (DSD), used as a model compound of fluorescent whitening agents, was investigated in aqueous solution. The mixing
of DSD and iron(III) solutions immediately led to DSD degradation into two oxidation products 5‐amino‐2‐
formyl‐benzene sulfonic acid (1) and DSD epoxide (2) together with the formation of Fe(II). The behaviour
of the latter solution was investigated under monochromatic excitation at 365 nm. The irradiation of the
solution resulted in a photoredox process that yielded Fe(II) and HO• radicals; being the most photoactive species. The disappearances of the oxidation products were shown to only involve the
attack of HO• radicals; the quantum yields of disappearances are wavelength dependent as the formation
of the hydroxyl radicals is. For prolonged irradiation, the total mineralisation of the oxidation products
was achieved with the formation of sulphate and ammonium ions. The half‐lives of products 1 and 2 when
submitted to such a process under solar irradiation were estimated to be respectively 12 and 11 min in the
mixture with 100% of monomeric species . Under these conditions, the total mineralisation is reached within 2 days of exposure.
Photocatalytic degradation of reactive yellow 17 dye in aqueous solution in the presence of TiO2 with cement binder
Authors: Neppolian B. , Kanel S. R. , Choi H. C. , Shankar M. V. , Arabindoo Banunathi , Murugesan V.
Published: March 2007

This study examined the photocatalytic degradation of common textile dye, reactive yellow 17 by
photocatalysis over TiO2 (Degussa P25) photocatalyst coated on the glass plates (reactor) using cement as a
binder. Sunlight was used as an energy source. The degradation efficiency was found to be the high at around
neutral pH values. The influence of additives such as H2O2, K2S2O8, Na2CO3 or NaCl, on the degradation
efficiency of the dye in the presence of cement binder was systematically studied. Both Na2CO3 and NaCl
were hindering the rate of photocatalytic degradation. Whereas, increase the initial concentrations of both
H2O2 and K2S2O8, increased the rate of degradation of the dye. UV‐vis spectrophotometer and chemical
oxidation demand were used to study decolourisation and degradation of dye, respectively. From this study,
degradation of textile dye reactive yellow 17 with TiO2 photocatalyst coated on the glass plate using cement
as a binder employing solar energy may emerge as a cost‐effective method for textile dye wastewater of low
concentration.
Photocatalytic mineralization of humic acids with TiO2: Effect of pH, sulfate and chloride anions
Authors: Wiszniowski Jarek , Robert Didier , Surmacz-Gorska Joanna , Miksch Korneliusz , Weber Jean-Victor
Published: March 2007

Aims of the present work are to investigate the photomineralization of commercial humic acid
in water solution.The effect of initial pH of solution and different anions (chloride, sulfate and mixture)
on the photocatalytic degradation of HA with titanium dioxide in aqueous solution has been examined.
The photocatalytic mineralization rate in alkaline solution is lower than in neutral and acidic solution. In our
conditions no effect of chloride ions on the degradation rate is observed. The influence of the sulfate depends
on its concentration in the solution. For a large concentration, we note a decrease of the mineralization
rate.
Kinetics of atrazine degradation by photocatalytic process in aqueous solution
Authors: Zahraa O. , Sauvanaud L. , Hamard G. , Bouchy M.
Published: March 2007

The photocatalytic degradation of the herbicide atrazine has been studied using suspended titanium
dioxide as catalyst. The Langmuir‐Hinshelwood model is satisfactorily obeyed at initial time and in the
course of the reaction. The rate of degradation is found to be enhanced by the addition of persulphate ions.
Competitive degradation between atrazine and other pollutants is satisfactorily interpreted as monitored by
a competitive adsorption of the reactants. As a consequence, efficient reactants such as salicylic acid and
phenol delay atrazine degradation until these compounds are degraded.
Testing and performance of immobilized Fenton photoreactions via membranes, mats and modified copolymers
Authors: Fernandez J. , Nadtochenko V. , Enea O. , Bozzi A. , Yuranova T. , Kiwi J.
Published: March 2007

During the last 6 years our laboratory has developed Fenton immobilized catalysts for the partial
or total destruction of toxic organic compounds and their mixtures. This paper reports on Fe‐supported noncorrosive
supported membranes and fabrics like: Nafion, Nafion‐glass mats and polyethylene block copolymers.
These novel supported catalysts have shown acceptable kinetic rates, resistance to the leaching of Fe3+ into the solution and no corrosion to the highly oxidative radicals generated in the solution during Fenton
immobilized photo‐assisted catalysis. Nafion‐Fe membranes degrade Orange II under visible light only up to
pH 4.8. In the case of nafion glass mats supported Fe3+‐ions, the initial pH could be raised up to 8 or above.
The pH decreased to about 4 during the photodegradation of Orange II due to the formation of intermediate
carboxylic acids but the costly initial acidification process necessary in the case of homogeneous Fenton processes
is avoided. Carboxylates and carboxylic acids were observed by IR spectroscopy on the surface of the
supported catalysts towards the end of the photodegradation process as well as carboxylic acids detected
by HPLC. The IR bands are found at 1523 and 1557 cm-1 in the case of the copolymer‐Fe3+ corresponding to two types of iron‐carboxylate species. The formation of carboxylates explains the drop of pH during the
photodegradation to values between 3 and 4 corresponding to the pKa of the carboxylic functional group.
ETS‐10 as a photocatalyst
Authors: Krisnandi Yuni K. , Southon Peter D. , Adesina Asoji A. , Howe Russell F.
Published: March 2007

ETS‐10 is a microporous titanosilicate zeolite with a framework containing linear Ti‐ O ‐Ti‐ O‐ chains. This paper describes an investigation of the photoreactivity of ETS‐10 with the particular objective of
evaluating the potential of this novel material as a zeolitic photocatalyst. The photoreactivity and photocatalytic
activity of ETS‐10 are strongly influenced by defects in the structure. A relatively defect free material
catalyses photo‐polymerisation of ethene, and in the presence of oxygen catalyses the partial oxidation of
ethene to acetic acid and acetaldehyde, which remain strongly adsorbed in the pores. A more defective
material is photoreduced when irradiated in the presence of adsorbed ethene, and catalyses the complete
oxidation of ethene to carbon dioxide and water in the presence of oxygen. These differences are attributed
to differences in the concentrations of exposed titanium sites associated with defects in the ETS‐10 structure.
Photocatalytic activity of spectro‐pure titanium dioxide: Effects of crystalline structure, specific surface area and sorption properties
Authors: Kapinus Evgeny I. , Khalyavka Tatyana A. , Shimanovskaya Valentina V. , Viktorova Tatyana I. , Strelko Vladimir V.
Published: March 2007

Dispersed optically pure anatase, rutile and two‐phase samples of titanium dioxide were prepared
using a sol‐gel technique. In particle of two‐phase samples, the anatase nuclei are surrounded by a
rutile envelope. Content of anatase in the two‐phase particles varied between 20 and 80%. Particles of all
the TiO2 samples had a globular shape of diameter between 10 and 30 μm. When compared to the corresponding
technical‐grade samples, the optically pure anatase and rutile demonstrated higher photocatalytic
activity in the destruction of tetradecylpyridinium chloride, Methylene Blue and tetrachlorofluorescein as
well as in reduction of Cr2O7 2−, MnO4 −, and . The photocatalytic reactions bring about the reduction of the inorganic anions to yield water insoluble substances and mineralization of the
organic compounds. Rate constant of the all above processes do not depend on specific surface area of TiO2
and adsorption of the substrates on the TiO2 samples. The rutile calcined at 1027K exhibits the highest
specific rate constants. Exposure to γ‐radiation increases photocatalytic activity of the dispersed TiO2. The influence of TiO2 and substrate on the photocatalytic reactions is caused by the influence of these factors
on the formation of reactive electron hole pair and on the efficiency of the interfacial electron transfer.