bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoelectrochromic Dithienylperfluorocyclopentene Derivatives
Authors: Zhou Xin-Hong , Zhang Fu-Shi , Yuan Peng , Sun Fan , Pu Shou-Zhi , Zhao Fu-Qun , Tung Chen-Ho 
Published: July 2004

Abstract
Dithienylperfluorocyclopentene derivatives that bear alkyl substituents connected onto the two carbon atoms of the thiophene heterocycles where, in their ring-closed form, the new C–C single bond is formed (the 2-positions of the thiophene), can exhibit photochromic ring-closing, and both photochromic and electrochromic ring-opening.
Isolation and Characterization of a New Isomer of Ca@C72
Authors: Ichikawa Takafumi , Kodama Takeshi , Suzuki Shinzo , Fujii Ryosuke , Nishikawa Hiroyuki , Ikemoto Isao , Kikuchi Koichi , Achiba Yohji 
Published: July 2004

Abstract
We isolated a new (second) isomer of Ca@C72. As a result of this discovery, it was confirmed that at least one of the two Ca@C72 isomers has a C72 cage that does not satisfy the so-called isolated pentagon rule (IPR), because C72 has only one IPR cage structure.
“One-pot” Fabrication of Ag/PMMA “shell/core” Nanocomposites by Chemical Reduction Method
Authors: Wang Limei , Chen Dajun 
Published: July 2004

Abstract
The Ag/PMMA shell/core nanocomposites were fabricated by one-pot emulsification method. AgNO3 are both silver source and initiator for polymerization of MMA. The polymerization took place when the Ag+ was reduced to Ag. The microstructures of the nanocomposites were characterized by TEM, XRD, FTIR, and AFM.
Noncovalent Combination of Oligoamine and Oligonucleotide as Totally Organic Site-selective RNA Cutter
Authors: Shi Yun , Niikura Fumiya , Kuzuya Akinori , Komiyama Makoto 
Published: July 2004

Abstract
When a one-base gap was formed in substrate RNA by using two oligonucleotides, the phosphodiester linkage at the gap-site was activated and selectively hydrolyzed by ethylenediamine. This site-selective hydrolysis was further promoted by connecting two gap-forming oligonucleotides with 1,3-propanediol linker.
Lithium Acetate-catalyzed Michael Reaction between Trimethylsilyl Enolate and α,β-Unsaturated Carbonyl Compound
Authors: Nakagawa Takashi , Fujisawa Hidehiko , Nagata Yuzo , Mukaiyama Teruaki 
Published: July 2004

Abstract
Lithium acetate-catalyzed Michael reaction between trimethylsilyl enolates and α,β-unsaturated carbonyl compounds in DMF proceeded smoothly to afford the corresponding Michael-adducts in good to high yields. Hindered α,β-unsaturated ketones also behaved as an excellent Michael-acceptor in the above reaction at room temperature.
Bicyclo[10.10.10]dotriacontanes: the Largest Bicyclo[n.n.n]alkane Ever Known
Authors: Kurata Hiroyuki , Rikitake Nobuo , Okumura Akio , Oda Masaji 
Published: July 2004

Abstract
Bicyclo[10.10.10]dotriacontanes, the largest bicyclo[n.n.n]alkanes ever known, have been first synthesized by Raney nickel reduction of trithienylmethanophanes consisiting of two tris(2-thienyl)methanes and three etheno bridges. X-ray crystallographic analysis of a crystalline derivative confirmed the structure, though disorder of included hexane molecules lowered the accuracy.
Improved Rapid Preparation of Polyelectrolyte-protected Gold Nanoparticles through a Microwave-based Thermal Process
Authors: Liao Fang 
Published: July 2004

Abstract
This work demonstrates the improved, size-controlled preparation of polyelectrolyte-protected gold nanoparticles, carried out by microwave radiation of an aqueous solution containing chloroauric acid and amine-containing polyelectrolyte.
Novel Ionic Liquids Composed of Only Azole Ions
Authors: Ogihara Wataru , Yoshizawa Masahiro , Ohno Hiroyuki 
Published: July 2004

Abstract
Novel ionic liquids (ILs) composed of azole type cation and anion were prepared. Triazole and tetrazole were coupled with 1-ethyl-3-methylimidazolium hydroxide. Obtained tetrazole salt was liquid at room temperature showing only glass transition temperature at −89 °C. The ionic conductivity reached to 8.9 × 10−3 S cm−1 at room temperature reflecting low viscosity of 42.5 cP at 25 °C. This is the first report on the ILs based on only azole type ions.
Phosphoprotein-Selective Recognition and Staining in SDS-PAGE by Bis-Zn(II)-dipycolylamine-Appended Anthracene
Authors: Ojida Akio , Kohira Takahiro , Hamachi Itaru 
Published: July 2004

Abstract
A novel fluorescence detection system using a chemosensor for phosphoprotein in gel electrophoresis analysis has been developed. The system employed bis-Zn(II)-dipycolylamine (Dpa)-appended anthracene as a fluorescent staining dye to carry out convenient and selective detection of phosphoproteins in SDS-PAGE.
Efficient Synthesis of 3-Substituted Indazoles Using Pd-Catalyzed Intramolecular Amination Reaction of N-Tosylhydrazones
Authors: Inamoto Kiyofumi , Katsuno Mika , Yoshino Takashi , Suzuki Ikue , Hiroya Kou , Sakamoto Takao 
Published: July 2004

Abstract
The efficient method for the preparation of 3-substituted indazoles was developed using the palladium catalyzed intramolecular amination reaction of 2-bromophenyl hydrazone derivatives. Good functional group compatibility was observed under mild reaction conditions and various 3-substituted indazoles were obtained in moderate to excellent yield.
Improved Cathodic Expansions of Electrochemomechanical Behavior in Polypyrrole Films Electrodeposited from Aerosol OT Emulsion
Authors: Takashima Wataru , Pandey Shyam S , Kaneto Keiichi 
Published: July 2004

Abstract
Electrodeposited polypyrrole films in Aerosol OT emulsion media (PPyAOT) have been investigated in terms of their electrochemomechanical characteristics for various tetraalkyl ammonium (TAA) chloride salts. PPyAOT film exhibited a cathodic expansive behavior during potential cycling, indicating the reversible exchange of TAA in PPyAOT. The oxidation peaks changed with the alkyl chain length while the reduction peaks were stationary. The large cathodic expansion of 4.5% was obtained in 0.2 M tetraethyl ammonium chloride solution. The unique porous morphology on PPyAOT film seems to assist the large mobility of bulky cations.
Improved Durability of Norbornadiene Derivatives Using Antioxidized Reagent
Authors: Nagai Takabumi , Nishikubo Tadatomi 
Published: July 2004

Abstract
It was found that improvement in durability of NBDs against degradation during repeated cycles of photoisomerization of NBDs to QCs and thermal reversion of QCs to NBDs could be achieved by an antioxidized reagent. Hindered amine derivative was the most effective.
Retrospectives: How Joan Robinson and B. L. Hallward Named Monopsony
Authors: Thornton Robert J 
Published: July 2004

The term “monopsony” was introduced by Joan Robinson in her 1932 classic The Economics of Imperfect Competition, although she gives credit to classics scholar B.L. Hallward of Cambridge for the actual coining of the term. Even though the term has become widely accepted by economists, its literal meaning is more idiosyncratic than simply “one buyer” of a commodity or service. In this paper I discuss the etymology of the term monopsony and suggest several other words that would seem to be more appropriate for describing this market phenomenon. This feature addresses the history of economic words and ideas. The hope is to deepen the workaday dialogue of economists, while perhaps also casting new light on ongoing questions. If you have suggestions for future topics or authors, please write to Joseph Persky, c/o Journal of Economic Perspectives, Department of Economics (M/C 144), University of Illinois at Chicago, 601 South Morgan Street, Room 2103, Chicago, Illinois 60607-7121.
Sensitive Nonradiometric Method for Determining Thymidine Kinase 1 Activity
Authors: Öhrvik Anders , Lindh Maria , Einarsson Roland , Grassi Jacques , Eriksson Staffan 
Published: July 2004

AbstractBackground: Thymidine kinase 1 (TK1) is a cytoplasmic enzyme, produced only in the S-phase of proliferating cells, that has potential as a tumor marker. Specific determination of TK1 in serum is difficult, in part because of differences in the physical properties of serum TK1 compared with cytoplasmic TK1.Methods: The first step in the new assay was phosphorylation of 3′-azido-2′,3′-deoxythymidine (AZT) to AZT 5′-monophosphate (AZTMP) by TK1 present in patient material. The AZTMP formed was measured in a competitive immunoassay with specific anti-AZTMP antibodies and AZTMP-labeled peroxidase. Results were compared with those of a TK radioenzyme assay (REA) for 78 samples from patients suffering from hematologic diseases.Results: The detection limit was 78 μIU/L, and within-run CVs &lt;20% were seen for samples with TK1 down to 130 μIU/L. Cross-determination of the mitochondrial isoenzyme TK2 activity was &lt;0.1%. Between-assay imprecision (CV) was 3.5–7.4%, and the within-assay imprecision was 4.1–9.1%. In studies of recovery and linearity on dilution, measured values ranged from 84% to 115% of expected at concentrations of 0.26–10.4 mIU/L. Results of the new assay (mIU/L) = 0.109 × TK REA (U/L) + 0.092. Heterophilic antibodies did not interfere in the assay. The upper 95th percentile, in 100 healthy individuals, was 0.94 mIU/L, and the median value was 0.43 mIU/L.Conclusion: The TK1 enzyme-labeled immunoassay uses a stable substrate, is precise, appears to be accurate, and is resistant to interferences. It may provide a practical tool in the management of hematologic malignancies.
Daily Cyclic Changes in the Urinary Excretion of 5-Hydroxyindoleacetic Acid in Patients with Carcinoid Tumors
Authors: Zuetenhorst Johanna M , Korse Catharina M , Bonfrer Johannes M G , Peter Ellen , Lamers Cornelis B H W , Taal Babs G 
Published: July 2004

AbstractBackground: Vasoactive peptides produced by neuroendocrine tumors can induce characteristic symptoms of the carcinoid syndrome (flushing, diarrhea, and wheezing). To what extent external factors provoke these symptoms and how excretion of 5-hydroxyindoleacetic acid (5-HIAA), the degradation product of serotonin, varies throughout the day remain unknown. In this study, we investigated whether symptoms and daily activity are related to 5-HIAA excretion and whether 24-h urine collection is needed.Methods: In 26 patients with metastatic carcinoid (14 men and 12 women; median age, 60 years) urine was collected in portions of 4 or 8 h during 2 days. Patients were asked to keep a diary in which they noted symptoms of flushes, consistency of stools, activities, and food intake.Results: Excretion of 5-HIAA in 24-h urine was increased in 88% of the patients (median, 515 μmol/24 h). Overnight-collected urine appeared the most representative for 24-h collection concentrations (correlation coefficient = 0.81). We found no clear correlation between symptoms of the carcinoid syndrome and degree of activity. Watery diarrhea was reported only by patients with strong variations in 5-HIAA excretion. One-half of the patients (n = 16) exhibited a high variability in urinary 5-HIAA excretion throughout the day, with increased concentrations most prominent in morning collections (P = 0.0074) and lower concentrations in the evening (P = 0.0034). In the other patients these curves were flat.Conclusions: Cyclic changes in patients relate to high variability in 5-HIAA excretion. Overnight-collected urine can replace the 24-h urine collection, and marked variations in 5-HIAA excretion seem to be associated with severity of diarrhea.
Rapid Screening Test for Primary Hyperaldosteronism: Ratio of Plasma Aldosterone to Renin Concentration Determined by Fully Automated Chemiluminescence Immunoassays
Authors: Perschel Frank Holger , Schemer Rudolf , Seiler Lysann , Reincke Martin , Deinum Jaap , Maser-Gluth Christiane , Mechelhoff David , Tauber Rudolf , Diederich Sven 
Published: July 2004

Abstract
Background: The ratio of plasma aldosterone concentration to plasma renin activity (PAC/PRA) is the most common screening test for primary hyperaldosteronism (PHA), but it is not standardized among laboratories. We evaluated new automated assays for the simultaneous measurement of PAC and plasma renin concentration (PRC).
Methods: We studied 76 healthy normotensive volunteers and 28 patients with confirmed PHA. PAC and PRC were measured immunochemically in EDTA plasma on the Nichols Advantage® chemiluminescence analyzer, and PRA was determined by an activity assay.
Results: In volunteers, PAC varied from 33.3 to 1930 pmol/L, PRA from 1.13 to 19.7 ng · mL−1 · h−1 (0.215 ng · mL−1 · h−1 = 1 pmol · L−1 · s−1), and PRC from 5.70 to 116 mU/L. PAC/PRA ratios ranged from 4.35 to 494 (pmol/L)/(ng · mL−1 · h−1) and PAC/PRC ratios from 0.69 to 71.0 pmol/mU. In PHA patients, PAC ranged from 158 to 5012 pmol/L, PRA from 0.40 to 1.70 ng · mL−1 · h−1, and PRC from 0.80 to 11.7 mU/L. PAC/PRA ratios were between 298 and 6756 (pmol/L)/(ng · mL−1 · h−1) and PAC/PRC ratios between 105 and 2328 pmol/mU. Whereas PAC or PRC showed broad overlap between PHA patients and volunteers, the PAC/PRC ratio indicated distinct discrimination of these two groups at a cutoff of 71 pmol/mU.
Conclusion: The PAC/PRC ratio offers several practical advantages compared with the PAC/PRA screening method. The present study offers preliminary evidence that it may be a useful screening test for PHA. Further studies are required to validate these results, especially in hypertensive cohorts.
New evidence on the factors affecting bridging and semibridging character of carbonyl ligands. The structures of Mn2(CO)7(μ‐SCH2CH2S) and its phosphine derivatives Mn2(CO)7‐X(PMe2Ph)X(μ‐SCH2CH2S), × = 1,2
Authors: Adams Richard D. , Kwon O‐Sung , Smith Mark D. 
Published: July 2004

AbstractThe new ethanedithiolate—dimanganese carbonyl complex, Mn2(μ‐SCH2CH2S)(CO)7, 1, was prepared in 28% yield from the reaction of 1,2,5,6‐tetrathiacyclooctane with Mn2(CO)9(NCMe). Complex 1 was characterized crystal‐lographically. It contains two Mn(CO)3 groups joined by a Mn–Mn bond of 2.6470(6) Å in length, a dihapto‐bridging ethanedithiolate ligand, and one strong semibridging CO ligand. The reaction of 1 with PMe2Ph yielded two derivatives: Mn2(μ‐SCH2CH2S)(CO)6(PMe2Ph), 2, and gem‐Mn2(μ‐SCH2CH2S)(CO)5(PMe2Ph)2, 3a, in 48% and 6% yields, respectively. When heated at 40 °C, compound 3a was transformed into three isomers, iso‐gem‐Mn2(μ‐SCH2CH2S)(CO)5(PMe2Ph)2, 3b, 1,2‐Mn2(μ‐SCH2CH2S)(CO)5(PMe2Ph)2, 3c, and cis‐Mn2(μ‐SCH2CH2S)‐(CO)5(PMe2Ph)2, 3d. Compounds 3b and 3c were characterized by single‐crystal X‐ray diffraction analyses. The introduction of phosphine ligand into the complexes strongly affects the semibridging character of the carbonyl ligand.
Revisiting N‐continuous density‐functional theory: Chemical reactivity and “Atoms” in “Molecules”
Authors: Cohen Morrel H. , Wasserman Adam 
Published: July 2004

AbstractWe construct an internally‐consistent density‐functional theory valid for noninteger electron numbers N by precise definition of a density functional that is continuous in N. In this theory, charge transfer between the atoms of a heteronuclear diatomic molecule, which have been separated adiabatically to infinity, is avoided because the hardness for fractional occupation of a single HOMO spin‐orbital is negative. This N‐continuous density functional makes possible a variational theory of “atoms” in “molecules” that exactly decomposes the molecular electron density into a sum of contributions from its parts. The parts are treated as though isolated. That theory, in turn, gives a deep foundation to the chemical reactivity theory provided that the hardness of entities with vanishing spin density is positive, as argued to be the case here. This transition from negative to positive hardness closely parallels the transition from the Heitler‐London to the Hund‐Mulliken picture of molecular bonding.
Electronic coupling between molybdenum and tungsten quadruple bonds in molecular squares and extended chains linked by oxalate, acetylenedicarboxylate, and perfluoroterephthalate bridges
Authors: Bursten Bruce E. , Chisholm Malcolm H. , Hadad Christopher M. , Li Jun , Wilson Paul J. 
Published: July 2004

AbstractThe electronic structures of dicarboxylate‐bridged complexes containing dimolybdenum and ditungsten quadruple bonds have been investigated using density function theory (gradient corrected and time‐dependent), which reveals the consequences of strong mixing of M2 δ and oxalate π orbitals within extended chains and cyclic structures. Where the bridge is oxalate, acetylene dicarboxylate, and perfluoroterephthalate (PFT), the M2 centers are in all cases strongly coupled through M2 δ to bridge π‐conjugation. In the case of the chain compounds, this is strongly mediated by torsion angles along the chain. For the squares, only when the bridge is PFT is there a dependence on the orientation of the phenyl ring.
Chiral lewis acid‐catalyzed enantioselective michael reactions in water
Authors: Kobayashi Shū , Kakumoto Kentaro , Mori Yuichiro , Manabe Kei 
Published: July 2004

AbstractAsymmetric Michael reactions of ß‐ketoesters with enones were effectively catalyzed by complexes of silver salts and BINAP derivatives in water. The reactions have proved to give Michael adducts in high yields with high enantioselectivities. These reactions are the first example of Lewis acid‐catalyzed asymmetric Michael reactions in water.
Hydrogen/deuterium exchange kinetics of cytochrome C: An electrospray ionization fast flow experiment
Authors: Geller Orit , Lifshitz Chava 
Published: July 2004

AbstractNew experiments are described in which the gas phase hydrogen/deuterium (H/D) exchange kinetics is studied for multiply‐protonated cytochrome c ions with +10 to +17 charges. The experimental technique involves electrospray ionization (ESI) combined with a fast‐flow method. Experimental results are presented including (1) average rate constants for H/D exchange, (2) overall decay kinetics of the reactant ion, and (3) sets of profiles for consecutive deuterium exchanges as a function of the flow rate of ND3 as the deuterating agent. The maximum number of exchanged hydrogen atoms and the exchange rate are observed to increase with increasing charge. The +13 state demonstrates special reactivity with a reactant ion decay constant of 2.5 × 10−9 cc/molecule's. Further insight into the H/D exchange mechanism is anticipated upon analysis of the data with a newly developed algorithm for extracting site‐specific rate constants from profiles for H/D exchange in gas phase protonated amino acids, their clusters, and peptides. The algorithm minimizes the mutual entropy or the Kullback‐Leibler information divergence between the observed concentrations and a chosen model.
An STM investigation of the adsorption of mixtures of fatty acids and substituted acids at the solution‐graphite interface
Authors: Yablon Dalia G. , Ertas Deniz , Fang Hongbin , Flynn George W. 
Published: July 2004

AbstractScanning tunneling microscopy (STM) is used to investigate the adsorption on graphite of two‐solute mixtures from phenyloctane solvent at room temperature. The first mixture is composed of the co‐solutes hexadecanoic acid (HA) and 2‐Br‐hexadecanoic acid (2BrHA), while the second mixture is composed of co‐solutes tetracosanoic acid (TA) and octadecanoic acid (OA). While the HA/2BrHA solution exhibits a miscible co‐adsorbed surface structure, the TA/OA solution reveals a quasi‐segregated surface structure where there is a sharp transition from full surface coverage by one solute to full coverage by the second as the composition of the solution mixture is varied. A one‐dimensional Ising model is used to model the adsorption behavior of both systems, and it is shown that both the HA/2BrHA and OA/TA mixtures correspond to two different limits of this model. The HA/2BrHA mixture exhibits similar, weak interactions between adsorbed molecules, corresponding to one limit of the Ising model, which also corresponds to competitive Langmuir adsorption. Another limit of the Ising model is reached when there are significantly different interactions between the different co‐adsorbates on the surface, a situation present in the OA/TA mixture resulting in a significantly different co‐adsorption behavior.
Synthesis of polycyclic polyfunctionalized carbocycles by a cobalt(I)‐initiated tandem diels–alder reaction sequence
Authors: Hilt Gerhard , Lüers Steffen , Polborn Kurt 
Published: July 2004

AbstractThe cobalt(I)‐catalyzed neutral Diels–Alder reaction of acyclic 1,3‐dienes with conjugated enynes can be used to generate secondary dihydroaromatic 1,4,8‐trienes containing a 1,3‐diene substructure, in good yields under mild reaction conditions. These 1,3‐dienes can be converted, with reactive dienophiles in a tandem normal Diels–Alder reaction, into polycyclic compounds. In a similar tandem Diels–Alder sequence, the cobalt‐catalyzed neutral homo Diels–Alder reaction of 2,5‐norbornadiene can be used to generate polycyclic cycloaddition adducts. A sequential triple Diels–Alder reaction sequence can be realized when norbornadiene is reacted with the excess of the conjugated enynes under cobalt(I) catalysis. In a homo Diels–Alder, neutral Diels–Alder, normal Diels–Alder reaction sequence, the intermediately formed adducts are reacted with activated dienophiles to yield polycyclic compounds in a short sequence. The structures of several products were established by X‐ray analysis. This showed that predominantly endo‐products are formed in the tandem reaction sequences, while the exo‐product becomes predominant in the triple Diels–Alder reaction sequence.
Quantum reaction dynamics and hyperspherical harmonics
Authors: Kuppermann Aron 
Published: July 2004

AbstractThis paper describes how large numbers of hyperspherical harmonics for triatomic and tetratomic systems, generated analytically by a computer algebra program, can be efficiently used to solve the time‐independent reactive scattering Schrödinger equation for triatomic and tetratomic systems in the strong interaction region of configuration space.
Theoretical studies of diiron(II) complexes that model features of the dioxygen‐activating centers in non‐heme diiron enzymes
Authors: Baik Mu‐Hyun , Lee Dongwhan , Friesner Richard A. , Lippard Stephen J. 
Published: July 2004

AbstractWe have applied high‐level Density Functional Theory to investigate the properties of recently characterized carboxylate‐bridged diiron(II) complexes supported by 2,6‐di(p‐tolyl)benzoate (ArTolCO2‐) ligands. These compounds, prepared as synthetic models for the reduced non‐heme diiron centers in the enzymes MMO, RNR‐R2, and Δ9D, reproduce the composition of the first coordination sphere ligands as well as the core geometry. The experimentally observed flexibility of the diiron cores in the model compounds, a main design target, was confirmed computationally. Details of a possible interconversion mechanism that transforms quadruply and doubly carboxylate‐bridged isomers of [Fe2(ArTolCO2)4L2], L = pyridine or related ligand, were examined. The orientation of the pyridine ligands plays a major role and promotes an initial carboxylate shift of the bridging carboxylate ligand that is orthogonal to the pyridine ring plane. Alternative mechanisms were explored and evaluated. Structural features of the strongly coupled diiron centers could only be reproduced reliably by using the experimentally determined antiferromagnetic spin‐coupling properties of the high‐spin d6 iron(II) centers. Use of the ferromagnetic‐coupling scheme gave rise to a poor correlation of the computed structure with the experiment. The broken‐symmetry orbitals required to describe the antiferromagnetic coupling are compared to the MOs as classical symmetry‐adapted linear combinations of atomic orbitals that form the basis for the magnetic coupling scheme. The molecular orbitals responsible for the dependence of the structural results on spin coupling were identified and used to evolve an intuitive explanation for the structural differences observed.