bluuebunny/crossref_metadata_2025_split huggingface dataset:
On bifurcation points of a complex polynomial
Authors: Jelonek Zbigniew 
Published: January 2003

Let

f
:

C

n

→

C

f: \mathbb {C}^n \to \mathbb {C}

be a polynomial of degree

d
d

. Assume that the set

K
~

∞

(
f
)
=
{
y
∈

C

:

\tilde {K}_\infty (f)=\{ y \in \mathbb {C} :

there is a sequence

x
l

→
∞

x_l\rightarrow \infty

s.t.

f
(

x
l

)
→
y

f(x_l)\rightarrow y

and

‖
d
f
(

x
l

)
‖
→
0
}

\Vert d f(x_l)\Vert \rightarrow 0\}

is finite. We prove that the set

K
~

(
f
)
=

K
0

(
f
)
∪

K
~

∞

(
f
)

\tilde {K} (f)= K_0(f)\cup \tilde {K}_\infty (f)

of generalized critical values of

f
f

(hence in particular the set of bifurcation points of

f
f

) has at most

(
d
−
1

)
n

(d-1)^n

points. Moreover,

#

K
~

∞

(
f
)
≤
(
d
−
1

)

n
−
1

.

\#\tilde {K}_\infty (f)\le (d-1)^{n-1}.

We also compute the set

K
~

(
f
)

\tilde {K} (f)

effectively.
On quasi-affine transforms of Read’s operator
Authors: Schlumprecht Thomas , Troitsky Vladimir 
Published: January 2003

We show that C. J. Read’s example of an operator

T
T

on

ℓ
1

\ell _1

which does not have any non-trivial invariant subspaces is not the adjoint of an operator on a predual of

ℓ
1

\ell _1

. Furthermore, we present a bounded diagonal operator

D
D

such that even though

D

−
1

D^{-1}

is unbounded, the operator

D

−
1

T
D

D^{-1}TD

is a bounded operator on

ℓ
1

\ell _1

with invariant subspaces, and is adjoint to an operator on

c
0

c_0

.
On the equation 𝑑𝑖𝑣𝑌=𝑓 and application to control of phases
Authors: Bourgain Jean , Brezis Haïm 
Published: January 2003

The main result is the following. Let

Ω
\Omega

be a bounded Lipschitz domain in

R

d

\mathbb {R}^{d}

,

d
≥
2

d\geq 2

. Then for every

f
∈

L

d

(
Ω
)

f\in L^{d}(\Omega )

with

∫
f
=
0

\int f =0

, there exists a solution

u
∈

C

0

(

Ω
¯

)
∩

W

1
,
d

(
Ω
)

u\in C^{0}(\bar \Omega )\cap W^{1, d}(\Omega )

of the equation div

u
=
f

u=f

in

Ω
\Omega

, satisfying in addition

u
=
0

u=0

on

∂
Ω

\partial \Omega

and the estimate

‖
u

‖

L

∞

+
‖
u

‖

W

1
,
d

≤
C
‖
f

‖

L

d

\begin{equation*}\Vert u\Vert _{L^{\infty }}+\Vert u\Vert _{W^{1, d}}\leq C\Vert f\Vert _{L^{d}} \end{equation*}

where

C
C

depends only on

Ω
\Omega

. However one cannot choose

u
u

depending linearly on

f
f

. Our proof is constructive, but nonlinear—which is quite surprising for such an elementary linear PDE. When

d
=
2

d=2

there is a simpler proof by duality—hence nonconstructive.
Asymmetric Synthesis of gem-Dimethylcyclopropane-fused Compounds through Chemo-, Regio-, and Stereoselective Cyclopropanation and Stereospecific Rearrangement
Authors: Sugimura Takashi , Tei Takahiro , Okuyama Tadashi 
Published: January 2003

Abstract
Optically active gem-dimethylcyclopropane-fused compound was synthesized by a tandem reaction consisting of chemo-, regio-, and stereoselective cyclopropanation of a 4-substituted 7,7-dimethylcycloheptatriene with an internal diazo ester and following stereospecific rearrangement.
Fabrication of Thin Films Using a Soluble Metal Phthalocyanine Salt and Their Photoconductive Properties
Authors: Matsuda Masaki , Ikeda Shingo , Hanasaki Noriaki , Yoshita Masahiro , Tajima Hiroyuki 
Published: January 2003

Abstract
We fabricated thin films from an acetone solution containing [(n-C7H15)4N]2[FeII(Pc)(CN)2] (Pc = phthalocyanine). The quality of films was improved by the pretreatment of the substrate with 3-trimethoxysilylpropyl chloride. The fabricated films exhibit the photoswitching phenomenon for ultraviolet (UV) irradiation.
Synthesis of Mesoporous Carbon-Containing Ferrocene Derivative and Its Electrochemical Property
Authors: Furukawa Hiroyasu , Hibino Mitsuhiro , Zhou Hao-Shen , Honma Itaru 
Published: January 2003

Abstract
Ordered mesoporous carbon-containing ferrocene derivative (Fc-MC) with a hexagonal framework structure has been prepared using a SBA-15 silica template. The electric double-layer capacitance of Fc-MC increases in comparison with that of pure mesoporous carbon.
Catalytic Transfer Hydrogenation of Nitro and Carbonyl Compounds over Novel Fe(III) Substituted Hexagonal Mesoporous Aluminophosphates
Authors: Sonavane Sachin U , Mohapatra Susanta K , Jayaram Radha V , Selvam Parasuraman 
Published: January 2003

Abstract
Catalytic transfer hydrogenation (CTH) of aromatic nitro and carbonyl compounds over novel Fe(III) substituted hexagonal mesoporous aluminophosphate (FeHMA) molecular sieve catalyst showed excellent regioselectivity/chemoselectivity as well as superior recycling capability. Furthermore, the reduction occurs without affecting other functional groups such as –CN, –CHO, –Cl, –CH3, –OCH3 and –NH2.
Generation of Photoinduced Steady Current by Purple Membrane Langmuir-Blodgett Films at Electrode-Electrolyte Interface
Authors: Miyasaka Tsutomu , Atake Tatsuya , Watanabe Tadashi 
Published: January 2003

Abstract
The Langmuir-Blodgett films of purple membrane (PM) immobilized on a gold electrode produced steady cathodic photocurrents under cathodic polarization of the electrode in aqueous electrolyte. The photocurrent is attributable to proton-reducing current that responds to proton release from light-excited bacteriorhodopsin. Effect of DC electric field at the water-air interface on the orientation of PM monolayer film was investigated.
C–H Activation by Cu(III)2O2 Intermediate with Secondary Amino Ligand
Authors: Arii Hidekazu , Saito Yamato , Nagatomo Shigenori , Kitagawa Teizo , Funahashi Yasuhiro , Jitsukawa Koichiro , Masuda Hideki 
Published: January 2003

Abstract
Reaction of Cu(I) complex having a newly designed tridentate ligand i-Bu3CY with dioxygen has given an active bis(μ-oxo)dicopper(III) complex, which has exhibited a unique intramolecular hydroxylation of the β-methine carbon of isobutyl group of the ligand.
Platinum-catalyzed Amidocarbonylation
Authors: Sagae Takahiro , Sugiura Masaharu , Hagio Hiroyuki , Kobayashi Shu 
Published: January 2003

Abstract
The first example of platinum-catalyzed amidocarbonylation of aldehydes with amides and carbon monoxide is described. In contrast to precedent palladium catalysis, a remarkable ligand acceleration by phosphines was observed. Furthermore, an optically active N-acetyl amino acid was partially epimerized under the platinum-catalyzed conditions, while faster racemization was observed under the palladium catalysis.
Pronounced Effect of the Methods of Preparation of Organic Thin Films on Hole Injection from the Indium-tin-oxide Electrode–Vacuum Deposition vs Spin Coating
Authors: Ishihara Mari , Okumoto Kenji , Shirota Yasuhiko 
Published: January 2003

Abstract
The methods of preparation of organic thin films of hole-transporting materials, vacuum deposition and spin coating, were found to exert a pronounced influence on charge injection from electrodes into organic layers in organic electroluminescent devices, depending upon the kind of hole transporters.
Electrooxidative Copolymerization of Aniline with o-Aminobenzonitrile in Centrifugal Fields
Authors: Atobe Mahito , Sekido Michiko , Fuchigami Toshio , Nonaka Tsutomu 
Published: January 2003

Abstract
It was demonstrated for the first time that centrifugal effects controlled not only the electrooxidative copolymerization ratio of aniline and o-aminobenzonitrile but also the morphology of the copolymer films.
The Role of Dissolved Organic Carbon in a Shallow Lowland Reservoir Ecosystem — A Long‐term Study
Authors: Górniak Andrzej , Zieliński Piotr , Jekatierynczuk‐Rudczyk Elżbieta , Grabowska Magdalena , Suchowolec Tomasz 
Published: January 2003

AbstractLong‐term studies were conducted on the polymictic Siemianówka reservoir (SR), situated in a seminatural forest‐peat catchment in NE Poland. The studies were started on the second year of the reservoir's existence. The records showed dissolved organic carbon (DOC) concentrations gradually increasing up to 25…30 mg/L. The largest DOC pool in the reservoir comes from the spring load input, supplemented by the excessive development of phytoplankton with cyanobacteria dominance. The DOC limited the range of the photic zone, eliminated the occurrence of aquatic plants, and was a significant carrier of nutrients, which were gradually released to water, bringing about the “humoeutrophication” of the reservoir.
Using web‐based technology in laboratory instruction to reduce costs
Authors: Powell Rita M. , Anderson Helen , Van der Spiegel Jan , Pope David P. 
Published: January 2003

AbstractThe authors report the results of a project to reemphasize high quality, hands‐on laboratory courses in the engineering curriculum while reducing their costs through the application of web‐based teaching tools. The project resulted in substantial gains in productivity of faculty and staff, increased utilization of laboratory space, cost reductions in equipment, and improved quality of learning for our students. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 204–214, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10029
WWW‐based virtual laboratories for reinforced concrete education
Authors: Jiang Hua , Kurama Yahya C. , Fanella David A. 
Published: January 2003

AbstractThis paper introduces three interactive virtual laboratory modules for undergraduate and graduate level education on the behavior and design of reinforced concrete structures using the World Wide Web (WWW). Users can select and configure module parameters (such as reinforcement) to investigate the design and behavior of a reinforced concrete member or section. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 167–181, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10030
Cover Picture: Chem. Eur. J. 2/2003
Authors: Tseng Hsian‐Rong , Vignon Scott A. , Celestre Paul C. , Stoddart J. Fraser , White Andrew J. P. , Williams David J. 
Published: January 2003

AbstractThe cover picture conveys the concise message that a fixed element of axial chirality residing in one ring of a catenane can induce chirality of a helical nature within a dynamic setting in the other (interlocked) ring. The overwhelming preference for one enantiomeric pair within a bipartite set of diastereoisomers relating to the particular [2]catenane, presented as its X‐ray crystal structure in the circular inset, becomes more and more pronounced as its 1,4‐dioxybenzene units are replaced, one at a time, by 1,5‐dioxynaphthalene ones, with their concomitant planar chiralities. The very high levels of induction of dynamic helical and planar chiralities by a fixed source of axial chirality in a simple catenane conjures up a number of scenarios where this approximately cubic nanometer of programmable information might be put to good use. For more details concerning these tiny stereochemical wonders with no stereogenic center in sight, see the article on p. 543 ff by J. F. Stoddart and D. J. Williams and the wizards that work their magic for them.
Structural Studies of N,N′‐Di(ortho‐fluorophenyl)formamidine Group 1 Metallation
Authors: Cole Marcus L. , Evans David J. , Junk Peter C. , Smith Matthew K. 
Published: January 2003

AbstractThe treatment of N,N′‐di(ortho‐fluorophenyl)formamidine (HFPhF) in tetrahydrofuran with equimolar amounts of n‐butyllithium, sodium bis(trimethylsilyl)amide or potassium bis(trimethylsilyl)amide affords the colourless crystalline formamidinate complexes [Li(FPhF)(thf)] (1), [Na(FPhF)(thf)] (2) and [K(FPhF)] (5). Low‐temperature preparation of 2 in diethyl ether yields the Et2O adduct [Na(FPhF)(Et2O)] (3). At ambient temperature the sodium fluoride inclusion complex [Na3(FPhF)3(Et2O)(NaF)] (4) is also formed. Spectroscopic (1H, 13C and 19F{1H} NMR) data for 1–5, microanalytical analyses for compounds 1, 2 and 5 and X‐ray structure determinations for 1, 3–5 confirm the formulae of these species. In the solid‐state, 1 and 3 possess a dimeric nature in which the formamidinate ligands coordinate through μ2:η2:η1 (1) and μ2:η2:η2 (3) binding modes. These are enabled by partial ortho‐fluoro donation. Compound 4, which is also dimeric, contains two trisodium tris(formamidinate) units that comprise μ2:η2:η2‐FPhF ligands, a bridging diethyl ether moiety and an unprecedented μ3:η2:η2:η2‐formamidinate donor. Together, these trinuclear units encapsulate two sodium fluoride units by η2‐N,N‐formamidinate chelation of the sodium cations (thereby creating further μ3:η2:η2:η2‐bound formamidinates) and fluoride–sodium interactions. Compound 5 extends the coordinative versatility of FPhF to μ2:η4:η3 coordination by the generation of K2(μ2:η4:η3‐FPhF)2 units that exhibit η2‐arene interactions. Macromolecularly, the overlaying of these units affords a polymeric solvent‐free structure that incites coordination of the FPhF ligands to metal atoms above and below the K2(FPhF)2 plane. Overall, this generates a remarkable μ4:η4:η3:η2:η1‐amidinate binding mode that incorporates both bridging and terminal fluorine donors. Compounds 1–5 are the first non‐chromium complexes of N,N′‐di(ortho‐fluorophenyl)formamidinate.
Lanthanum(III)‐Catalyzed Disproportionation of Hydrogen Peroxide: A Heterogeneous Generator of Singlet Molecular Oxygen—1O2 (1Δg)—in Near‐Neutral Aqueous and Organic Media for Peroxidation of Electron‐Rich Substrates
Authors: Nardello Véronique , Barbillat Jacques , Marko Jean , Witte Peter T. , Alsters Paul L. , Aubry Jean‐Marie 
Published: January 2003

AbstractThe decomposition of hydrogen peroxide into singlet molecular oxygen—1O2 (1Δg)—in the presence of lanthanum(iii) salts was studied by monitoring its characteristic IR luminescence at 1270 nm. The process was found to be heterogeneously catalyzed by LaIII, provided that the heterogeneous catalyst is generated in situ. The yield of 1O2 generation was assessed as 45±5 % both in water and in methanol. The pH‐dependence on the rate of 1O2 generation corresponds to a bell‐shaped curve from pH 4.5 to 13 with a maximum around pH 8. The study of the influence of H2O2 showed that the formation of 1O2 begins as soon as one equivalent of H2O2 is introduced. It then increases drastically up to two equivalents and more smoothly above. Unlike all other metal salt catalyst systems known to date for H2O2 disproportionation, this chemical source of 1O2 is able to generate 1O2 not only in basic media, but also under neutral and slightly acidic conditions. In addition, this La‐based catalyst system has a very low tendency to induce unwanted oxygenating side reactions, such as epoxidation of alkenes. These two characteristics of the heterogeneous lanthanum catalyst system allow non‐photochemical (i.e., “dark”) singlet oxygenation of substrate classes that cannot be peroxidized successfully with conventional molybdate catalysts, such as allylic alcohols and alkenyl amines.
A Three‐Component Reaction for Diversity‐Oriented Synthesis of Polysubstituted Piperidines: Solution and Solid‐Phase Optimization of the First Tandem Aza[4+2]/Allylboration
Authors: Touré Barry B. , Hoveyda Hamid R. , Tailor Jyoti , Ulaczyk‐Lesanko Agnieszka , Hall Dennis G. 
Published: January 2003

AbstractThis article describes the design and optimization of a simple three‐component aza[4+2]/allylboration reaction to access polysubstituted α‐hydroxyalkyl piperidines in a highly diastereocontrolled fashion from maleimides, 4‐boronohydrazonodienes, and aldehydes. The aldehyde component does not interfere with the first aza[4+2] step, and it was found that this tandem reaction provides better yields of piperidine products 5 when carried out in one‐pot. The required 4‐borono‐hydrazonodienes 1 are synthesized efficiently from the condensation of 3‐boronoacrolein pinacol ester (4) with hydrazines. Overall, the three‐component process using N‐substituted maleimides as dienophiles produces four stereogenic centers and is quite general. It tolerates the use of a wide variety of aldehydes and hydrazine precursors with different electronic and steric characteristics. By allowing such a wide substrate scope and up to four elements of diversity, this reaction process is particularly well adapted towards applications in diversity‐oriented synthesis of polysubstituted piperidine derivatives. The suitability of the aza[4+2]/allylboration reaction for use in solid‐phase chemistry was also demonstrated using a N‐arylmaleidobenzoic acid functionalized resin. This novel multicomponent reaction thus offers a high level of stereocontrol and versatility in the preparation of densely functionalized nitrogen heterocycles.
A Comprehensive Theoretical Study on the Reactions of Sc+ with CnH2n+2 (n=1–3): Structure, Mechanism, and Potential‐Energy Surface
Authors: Zhang Dongju , Liu Chengbu , Bi Siwei , Yuan Shiling 
Published: January 2003

AbstractThe reactions of Sc+(3D) with methane, ethane, and propane in the gas phase were studied theoretically by density functional theory. The potential energy surfaces corresponding to [Sc, Cn, H2n+2]+ (n=1–3) were examined in detail at the B3LYP/6‐311++G(3df, 3pd)//B3LYP/6‐311+G(d,p) level of theory. The performance of this theoretical method was calibrated with respect to the available thermochemical data. Calculations indicated that the reactions of Sc+ with alkanes are multichannel processes which involve two general mechanisms: an addition–elimination mechanism, which is in good agreement with the general mechanism proposed from earlier experiments, and a concerted mechanism, which is presented for the first time in this work. The addition–elimination reactions are favorable at low energy, and the concerted reactions could be alternative pathways at high energy. In most cases, the energetic bottleneck in the addition–elimination mechanism is the initial CC or CH activation. The loss of CH4 and/or C2H6 from Sc++CnH2n+2 (n=2, 3) can proceed along both the initial CC activation branch and the CH activation branch. The loss of H2 from Sc++CnH2n+2 (n=2, 3) can proceed not only by 1,2‐H2 and/or 1,3‐H2 elimination, but also by 1,1‐H2 elimination. The reactivity of Sc+ with alkanes is compared with those reported earlier for the reactions of the late first‐row transition‐metal ions with alkanes.
The Stabilisation of Monomeric Parent Compounds of Phosphanyl‐ and Arsanylboranes
Authors: Vogel Ulf , Hoemensch Petra , Schwan Karl‐Christian , Timoshkin Alexey Y. , Scheer Manfred 
Published: January 2003

AbstractThe structures of the parent compounds of phosphanyl‐ and arsanylboranes, H2BPH2 and H2BAsH2, were calculated by DFT‐B3LYP methods. Such compounds have not previously been obtained preparatively. By applying the concept of Lewis acid/base stabilisation, [(CO)5W(H2EBH2⋅NMe3)] (E=P (3), As (4)) derivatives have been synthesised by the metathesis reactions between Li[(CO)5WEH2] and ClH2BNMe3 (E=P, As). Comprehensive thermodynamic studies on these systems verify the high stability of the Lewis acid/base stabilised complexes. Unexpected based on the thermodynamic calculations, UV radiation of the phosphanylborane 3 leads to the dinuclear phosphanido‐bridged complex [(CO)8W2(μ‐PHBH2⋅NMe3)2] (5) by H2 and CO elimination.
Synthesis of an Amino‐Functionalized Model of the Fe‐Only Hydrogenase Active Site
Authors: Salyi Szabolcs , Kritikos Mikael , Åkermark Björn , Sun Licheng 
Published: January 2003

AbstractA dinuclear 2Fe2S mimic 6 of the active site of the Fe‐only hydrogenases has been synthesized. Complex 6 contains a free amino group which enables linkage to a protein backbone or to a redox active species for the study of electron transfer processes in proteins or in supramolecular systems. The structures of the complex 6 and its Boc‐protected precursor 5 could be verified by X‐ray crystallography.
On the Cavitation Energy of Water
Authors: Höfinger Siegfried , Zerbetto Francesco 
Published: January 2003

AbstractFree‐energy‐perturbation theory from molecular dynamics calculations has been used to obtain the ΔG of adjoining cavities' formation in water. The ΔGs for systems with three, five and seven cavities are compared with that of a single cavity of the same volume, and found to be in good agreement. The conditions under which the analytical formulation of the energy of cavity formation proposed by Pierotti holds are discussed. The data for a single cavity have been tabulated and can lend themselves to a simple numerical implementation in standard quantum chemical packages, which can be used when high accuracy for ΔGcav is required.
Sequestered Alkyllithiums: Why Phenyllithium Alone is Suitable for Betaine‐Ylide Generation
Authors: Wang Qian , Deredas Dariusz , Huynh Cyril , Schlosser Manfred 
Published: January 2003

AbstractThe key step in the trans‐selective modification of the Wittig reaction is the α‐lithiation of the lithium bromide coordinated ylide–aldehyde adduct (the so‐called “P‐betaine”). Only phenyllithium effects this deprotonation rapidly and cleanly. Alkyllithiums (in particular, butyl‐, sec‐butyl‐, and tert‐butyllithium) react only sluggishly and incompletely, being tied up in very stable mixed aggregates with the lithium alkoxide part of the betaines.
Vibronic Coupling in Molecules and in Solids
Authors: Grochala Wojciech , Hoffmann Roald , Edwards Peter P. 
Published: January 2003

AbstractWe utilize the experience gained in our previous studies on the “chemistry of vibronic coupling” in simple homonuclear and heteronuclear molecules to begin assembling theoretical guidelines for the construction of potentially superconducting solids exhibiting large electron‐phonon coupling. For this purpose we analyze similarities between vibronic coupling in isolated molecules and in extended solids. In particular, we study vibronic coupling along the antisymmetric stretch coordinate (Qas) in linear symmetric AAA molecules, and along the optical phonon “pairing” mode coordinate (Qopt) in corresponding one‐dimensional [A]∞ chains built of equidistant A atoms. This is done for a broad range of chemical elements (A). The following similarities between vibronic coupling in molecules and phonon coupling in solids emerge from our calculations: 1) The HOMO/LUMO electronic energy gap in an AAA molecule increases along Qas, and the highest occupied crystal orbital/lowest unoccupied crystal orbital gap in [A]∞ chain increases along Qopt. 2) The maximum vibronic instability is invariably obtained for a half‐filled, singly occupied molecular orbital in AAA molecules, and for a corresponding half‐filled band in [A]∞ chains. 3) The vibronic stability of an AAA molecule increases with a decrease of the AA bond length, as does the vibronic stability of [A]∞ chains (external pressure may lead to a reversal of a Peierls distortion). 4) The high degree of s–p mixing and ionic/covalent forbidden curve crossing dramatically enhance the vibronic instability of both AAA molecules and [A]∞ chains. We also introduce one quantitative relationship: The parameter log(R) (where R is molar refractivity, a parameter used by Herzfeld to prescribe the conditions for the metallization of the elements) correlates with a parameter fAA (defined as twice the electronegativity of A, divided by the equilibrium AA bond length), used by two of us previously to describe vibronic coupling in AAA molecules for a broad range of elements (A=halogen, H, or an alkali metal). We hope to illustrate that key chemical aspects of vibronic coupling in simple molecules may thus be profitably transferred to corresponding materials in the solid state.