bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Electronic Coupling in Linear Porphyrin Arrays Probed by Single‐Molecule Fluorescence Spectroscopy
Authors: Yang Jaesung , Lee Ji‐Eun , Lee Chang Yeon , Aratani Naoki , Osuka Atsuhiro , Hupp Joseph T. , Kim Dongho 
Published: July 2011

AbstractSingle‐molecule photophysical properties of two families of linear porphyrin arrays have been investigated by single‐molecule fluorescence detection techniques. Butadiyne‐linked arrays (ZNB) with extensive π‐conjugation perform as photostable one‐quantum systems. This demonstration has been suggested by the long‐lasting initial emissive state and subsequent discrete one‐step photobleaching in the fluorescence intensity trajectories (FITs). As in the behavior of a one‐quantum system, ZNB shows anti‐bunching data in the coincidence measurements. On the other hand, in directly‐linked arrays (ZN) with strong dipole coupling, each porphyrin moiety keeps individual character in photobleaching dynamics. The stepwise photobleachings in the FITs account for this explanation. Most of the FITs of ZN do not carry momentary cessation of fluorescence emission, which has been explained by the strongly bound electron‐hole pair of Frenkel exciton that suppresses charge transfer between the molecule and surrounding polymers. These results give insight into the influences of interchromophorinc interactions between porphyrin moieties in the multiporphyrin arrays on their fluorescence dynamics at the single‐molecule level.
Intramolecular Weak Interactions in the Thermodynamic Stereoselectivity of Copper(II) Complexes with Carnosine–Trehalose Conjugates
Authors: Grasso Giuseppa I. , Arena Giuseppe , Bellia Francesco , Maccarrone Giuseppe , Parrinello Michele , Pietropaolo Adriana , Vecchio Graziella , Rizzarelli Enrico 
Published: July 2011

AbstractThe interactions of metal ions with chiral molecules are of particular interest for relevant biochemical processes, as many of them are made possible only with a selected chirality of the stereocenters. In this work we report a study of the stereoselectivity of copper(II) complexes with D‐trehalose–L‐carnosine and D‐trehalose–D‐carnosine as a prototypical case of natural chirality selection. The interest in L‐carnosine dipeptide is compounded by its antioxidant and antitumor properties, which are further enhanced when combined with D‐trehalose. Potentiometric, calorimetric, and UV/circular dichroism (CD) spectroscopic measurements show that the copper(II) dimer of D‐trehalose–L‐carnosine is more stable than the D‐trehalose–D‐carnosine diastereoisomeric copper(II) dimer (log ${\beta {{{l}\hfill \atop 22- 2\hfill}}}$−log ${\beta {{{d}\hfill \atop 22- 2\hfill}}}$=3.6). Free‐energy calculations highlight that the cause of this different behavior lies with different intramolecular weak interactions between the diastereoisomers. The different pattern of hydrogen bonds and the different CH–π interactions between the π‐electron‐rich imidazole and the α‐glucose rings are more favorable by 5 kcal mol−1 in the L dimer.
On the Reactions of Methyl Radicals with TiO2 Nanoparticles and Granular Powders Immersed in Aqueous Solutions
Authors: Golberg‐Oster Olga , Bar‐Ziv Ronen , Yardeni Guy , Zilbermann Israel , Meyerstein Dan 
Published: July 2011

AbstractMethyl radicals react with TiO2 nanoparticles (NPs) immersed in aqueous solutions to form transients in which the methyls are covalently bound to the particles. The rate constant for this reaction approaches the diffusion‐controlled limit and increases somewhat with the number of methyls bound to the particle. The transients decompose to yield ethane. Thus, formally the particles “catalyse” the dimerization of the radicals, a reaction that is diffusion‐controlled. Rutile powders behave similarly to the TiO2 NPs whereas the mechanism for the decomposition of the transients formed in the analogous reaction of the radicals with anatase powders differs. These results are of importance as alkyl radicals are formed near the surface of TiO2 in a variety of important photocatalytic processes. The results imply that the reactions of alkyl radicals with TiO2 have to be considered in these processes.
Inelastic Neutron Scattering on an Mn10 Supertetrahedron: Assessment of Exchange Coupling Constants, Ferromagnetic Spin Waves and an Analogy to the Hückel Method
Authors: Stuiber Stefan , Wu Gang , Nehrkorn Joscha , Dreiser Jan , Lan Yanhua , Novitchi Ghenadie , Anson Christopher E. , Unruh Tobias , Powell Annie K. , Waldmann Oliver 
Published: July 2011

AbstractThe synthesis, crystal structure and magnetic characterisation by magnetisation and inelastic neutron scattering (INS) of a mixed‐valent Mn10 supertetrahedral aggregate [MnIII6MnII4(μ4‐O)4(μ3‐N3)3(μ3‐Br)(Hmpt)6(Br)]Br0.7(N3)0.3⋅2 MeOH⋅3 MeCN (1) (H3mpt=3‐methylpentan‐1,3,5‐triol) is reported. The magnetic core of the molecule can be described as an octahedron of six S=2 MnIII ions with four faces, each capped by a S=5/2 MnII ion such as to form the supertetrahedron. Unlike most related complexes, the molecular symmetry is slightly reduced from approximately Td to C3. The magnetic data reveal a total spin of S=22 in the ground state due to ferromagnetic exchange couplings within the molecule. The combined INS and magnetic data permits the accurate determination of the exchange coupling constants. Two types are found. The couplings between the MnIII ions in the inner octahedron are characterised by Ja=18.4(3) K, whereas the couplings between the apical MnII ions to the neighbouring MnIII ions are given by Jb=7.3(2) K. The significantly larger coupling strength Ja as compared to Jb, and the near‐Td symmetry have profound consequences on the energy spectrum, which are discussed and carefully analysed. In particular, the observed INS spectra can consistently be reproduced by a simplified model in which the inner octahedron is replaced by one large spin of length S0=12. This model provides intuitive insight into the structure of the magnetic spectrum. Additionally, the magnetic excitations at low temperature are analysed within the frame of ferromagnetic linear spin‐wave theory, which permits an analytical calculation of the energy levels. For ferromagnetic clusters, a close analogy to the Hückel method of electronic structure calculation can be drawn, which allows one to grasp the results of the spin‐wave theory or the magnetic excitation spectrum, respectively, in a chemical language.
Generating Hydrogen Gas from Methane with Carbon Captured as Pure Spheroidal Nanomaterials
Authors: Cornejo Andrew , Zhang Weike , Gao Lizhen , Varsani Rahi R. , Saunders Martin , Iyer K. Swaminathan , Raston Colin L. , Chua Hui Tong 
Published: July 2011

AbstractEnergy production by using hydrogen gas as a feedstock is considered to be one of the keys to creating clean energy, with the proviso that the gas is generated in a sustainable way with no emissions. A simple, self‐sustaining process generating hydrogen gas from methane using inexpensive stainless steel wire‐mesh catalysts at elevated temperatures (800 °C) is reported. A theoretical analysis of the production of electricity by this process revealed peak chain energy efficiencies up to 21 % (emission free) when using a percentage of the produced hydrogen (approximately 40 % of purified yield) as the heat source. In addition, a practical method has been developed to purify the carbon byproduct, affording essentially pure highly graphitic spheroidal carbon for advanced materials applications.
Chemical Surface Modification of Self‐Assembled Monolayers by Radical Nitroxide Exchange Reactions
Authors: Wagner Hendrik , Brinks Marion K. , Hirtz Michael , Schäfer Andreas , Chi Lifeng , Studer Armido 
Published: July 2011

AbstractThis article describes the application of nitroxide exchange reactions of surface‐bound alkoxyamines as a tool for reversible chemical modification of self‐assembled monolayers (SAMs). This approach is based on radical chemistry, which allows for introduction of various functional groups and can be used to reversibly introduce functionalities at surfaces. To investigate the scope of this surface chemistry, alkoxyamines with different functionalities were synthesized and were then applied to the immobilization of, for example, dyes, sugars, or biotin. Surface analysis was carried out by contact angle, X‐ray photoelectron spectroscopy, and fluorescence microscopy measurements. The results show that this reaction is highly efficient, reversible, and mild and allows for immobilization of various sensitive functional groups. In addition, Langmuir–Blodgett lithography was used to generate structured SAMs. Site‐selective immobilization of a fluorescent dye could be achieved by nitroxide exchange reactions.
Novel Multidentate Sulfur–Nitrogen Ligands with Enhanced Complexation Properties
Authors: Meinholz Margret M. , Klemmer Maika , Kriemen Ella , Stalke Dietmar 
Published: July 2011

AbstractDi(tert‐butyl)sulfur diimide and bis(trimethylsilyl)sulfur diimide were reacted with different metalated amines to form versatile novel multidentate ligand systems with side‐arm donation. Their complexation properties in terms of ligand design, denticity and the cation size are discussed. We report herein the synthesis and structure elucidation of [(tBuN)2S{LiMe2N(C6H4)S(NtBu)2}2] (1), [(Li{Me2N(C6H4)S(NSiMe3)2})2] (2), [(Li(thf){Me2N(C6H4)S(NSiMe3)2})2] (3), [(Li{2‐PicS(NSiMe3)2})2] (4), [(Li{Me2N(CH2)2N(Me)S(NSiMe3)2})2] (5), [(Na{Me2N(CH2)2N(Me)S(NSiMe3)2})2] (6) and [(K{Me2N(C6H4)S(NSiMe3)2})2] (7).
An Axially Chiral, Electron‐Deficient Borane: Synthesis, Coordination Chemistry, Lewis Acidity, and Reactivity
Authors: Mewald Marius , Fröhlich Roland , Oestreich Martin 
Published: July 2011

AbstractAn axially chiral dihydroborepine with a binaphthyl backbone and a C6F5 substituent at the boron atom was prepared by transmetalation from the corresponding tin precursor. This novel motif was structurally characterized by X‐ray diffraction analysis as its THF and its PhCN Lewis acid/base complex. 1H NMR measurements at variable temperatures of the former adduct revealed a remarkable dynamic behavior in solution. Several more Lewis pairs with oxygen, nitrogen, carbon, and phosphorus σ‐donors were synthesized and analyzed by multinuclear NMR spectroscopy. The determination of the borane’s Lewis acidity with the Gutmann–Beckett method attests its substantial Lewis acidity [85 % with Et3PO as well as 74 % with Ph3PO relative to the parent B(C6F5)3]. Representative examples of SiH bond activation (carbonyl reduction and dehydrogenative SiO coupling) are included, demonstrating the chemical stability and the synthetic potential of the new chiral boron‐based Lewis acid.
Synthetic Utilization of 2‐Chloro‐1,1,1,2‐tetrafluoroethane
Authors: Notsu Keiji , Zushi Yasuyuki , Ota Shin , Kawasaki‐Takasuka Tomoko , Yamazaki Takashi 
Published: July 2011

Abstractβ‐Substituted α‐fluoro‐α,β‐unsaturated carboxylic acids have been successfully synthesized, usually in a (Z)‐stereospecific manner by way of a stepwise or a one‐pot three‐step procedure starting from 2‐chloro‐1,1,1,2‐tetrafluoroethane (HCFC‐124), one of the major byproducts of the industrial process for tetrafluoroethene formation from chlorofluoromethane (HCFC‐22).
Ruthenium‐Catalysed Synthesis of Fluorinated Bicyclic Amino Esters through Tandem Carbene Addition/Cyclopropanation of Enynes
Authors: Eckert Matthieu , Moulin Solenne , Monnier Florian , Titanyuk Igor D. , Osipov Sergey N. , Roisnel Thierry , Dérien Sylvie , Dixneuf Pierre H. 
Published: July 2011

AbstractThe reaction of fluorinated 1,6‐ and 1,7‐enynes, containing the moiety N(PG)C(CF3)(CO2R), with diazo compounds in the presence of [RuCl(cod)(Cp*)] (cod=cycloocta‐1,5‐diene, Cp*=C5Me5, PG=protecting group) as the catalyst precursor leads to the formation of fluorinated 3‐azabicyclo[3.1.0]hexane‐2‐carboxylates and 4‐azabicyclo‐[4.1.0]heptane‐3‐carboxylates. This catalytic transformation was applied to various protecting groups and has proved to be a selective and a general synthetic tool to form constrained proline or homoproline derivatives in good yields. Z stereoselectivity of the created alkenyl group is obtained with N2CHSiMe3, whereas N2CHCO2Et favours selectively the E configuration for the same double bond. The diastereoselectivity exo/endo depends on the size of the created ring. The X‐ray structures of two products have been determined, showing the stereochemistry of the compounds. The reaction can be understood by initial [2+2] addition of the RuCHY bond, generated from diazoalkane, with the CCH bond of the enyne leading to a key bicyclic ruthenacyclobutane, which promotes the cyclopropanation, rather than metathesis. This selective formation of bicyclic [n.1.0] compounds results from the ruthenium‐catalysed creation of three carbon–carbon bonds in a single step under mild conditions.
The Organocatalytic Vinylogous Aldol Reaction: Recent Advances
Authors: Pansare Sunil V. , Paul Eldho K. 
Published: July 2011

AbstractOver the past decade, organocatalysis has emerged as a powerful tool for stereoselective carbon–carbon bond formation under exceptionally mild conditions. The organocatalytic versions of a large number of traditional synthetic transformations are now well established and the quest for new applications of the basic concepts of organocatalysis continues. This review addresses the emergent interest in the organocatalytic vinylogous aldol reaction. While noteworthy progress has been made in this area, significant challenges lie ahead.
Identification of a Glycogen Synthase Kinase‐3β Inhibitor that Attenuates Hyperactivity in CLOCK Mutant Mice
Authors: Kozikowski Alan P. , Gunosewoyo Hendra , Guo Songpo , Gaisina Irina N. , Walter Richard L. , Ketcherside Ariel , McClung Colleen A. , Mesecar Andrew D. , Caldarone Barbara 
Published: July 2011

AbstractBipolar disorder is characterized by a cycle of mania and depression, which affects approximately 5 million people in the United States. Current treatment regimes include the so‐called “mood‐stabilizing drugs”, such as lithium and valproate that are relatively dated drugs with various known side effects. Glycogen synthase kinase‐3β (GSK‐3β) plays a central role in regulating circadian rhythms, and lithium is known to be a direct inhibitor of GSK‐3β. We designed a series of second generation benzofuran‐3‐yl‐(indol‐3‐yl)maleimides containing a piperidine ring that possess IC50 values in the range of 4 to 680 nM against human GSK‐3β. One of these compounds exhibits reasonable kinase selectivity and promising preliminary absorption, distribution, metabolism, and excretion (ADME) data. The administration of this compound at doses of 10 to 25 mg kg−1 resulted in the attenuation of hyperactivity in amphetamine/chlordiazepoxide‐induced manic‐like mice together with enhancement of prepulse inhibition, similar to the effects found for valproate (400 mg kg−1) and the antipsychotic haloperidol (1 mg kg−1). We also tested this compound in mice carrying a mutation in the central transcriptional activator of molecular rhythms, the CLOCK gene, and found that the same compound attenuates locomotor hyperactivity in response to novelty. This study further demonstrates the use of inhibitors of GSK‐3β in the treatment of manic episodes of bipolar/mood disorders, thus further validating GSK‐3β as a relevant therapeutic target in the identification of new therapies for bipolar patients.
Synthesis of Aryl‐Substituted Naphthalene‐Linked Pyrrolobenzodiazepine Conjugates as Potential Anticancer Agents with Apoptosis‐Inducing Ability
Authors: Kamal Ahmed , Reddy M. Kashi , Ramaiah M. Janaki , Srikanth Y. V. V. , Rajender  , Reddy V. Santosh , Kumar G. Bharath , Pushpavalli S. N. C. V. L. , Bag Indira , Juvekar Aarti , Sen Subrata , Zingde Surekha M. , Pal‐Bhadra Manika 
Published: July 2011

AbstractA library of new aryl‐substituted naphthalene C8‐linked pyrrolo[2,1‐c][1,4]benzodiazepine (PBD) conjugates with various linker architectures were designed, synthesized, and evaluated for their anticancer activity against a panel of 11 human cancer cell lines. All 32 conjugates show anticancer potential, with some of them exhibiting particularly high activity (0.01–0.19 μM). Thermal denaturation studies showed effective DNA binding capacity relative to DC‐81. In assays for biological activity relating to cell‐cycle distribution, these PBD conjugates induce G0/G1‐phase arrest and also cause an increase in the levels of p53 and caspase‐9 proteins, followed by apoptotic cell death. One conjugate in particular is the most promising candidate of the series, with the potential to be selected for further studies, either alone or in combination with existing anticancer therapies.
Use of human papillomavirus vaccines among young adult women in the United States: An analysis of the 2008 National Health Interview Survey
Authors: Anhang Price Rebecca , Tiro Jasmin A. , Saraiya Mona , Meissner Helen , Breen Nancy 
Published: July 2011

AbstractBACKGROUND:The Centers for Disease Control and Prevention recommends catch‐up administration of human papillomavirus (HPV) vaccines to girls and women ages 13 to 26 who have not been vaccinated previously. In response to debate regarding catch‐up vaccination of young adult women, this study examined whether 18‐ to 26‐year‐old women most likely to benefit from catch‐up vaccination were aware of the HPV vaccine, and initiated the vaccine series by the end of 2008.METHODS:We used data from the 2008 National Health Interview Survey to assess HPV vaccine awareness and use, and reasons for not vaccinating, among women aged 18‐26 years (n = 1583). Sociodemographic, health care access, and health history factors associated with vaccine initiation were assessed using multivariate logistic regression.RESULTS:Overall, 11.7% of women aged 18‐26 years reported receiving at least 1 dose of the HPV vaccine by the end of 2008. In multivariate analyses, younger age, history of previous HPV infection, unmarried status, health insurance, flu shot in the past year, and receipt of 1 or more recommended lifetime vaccines were significantly associated with HPV vaccine initiation. Two‐fifths (39.6%) of unvaccinated women were interested in receiving the HPV vaccine (n = 1327). Primary reasons for lack of interest in the vaccine were belief that it was not needed, not knowing enough about it, concerns about safety, and not being sexually active.CONCLUSION:HPV vaccine coverage among young adult women was low, and lower among the uninsured than the insured. Public financing and care provision programs have the potential to expand vaccine coverage among uninsured women, who are at increased risk of cervical cancer. Cancer 2011;. © 2011 American Cancer Society.
Clinically significant Gleason sum upgrade
Authors: Iremashvili Viacheslav , Manoharan Murugesan , Pelaez Liset , Rosenberg Daniel L. , Soloway Mark S. 
Published: July 2011

AbstractBACKGROUND:Several nomograms have been developed for the purpose of predicting the likelihood of an increase in Gleason sum (GS) from biopsy information compared with the GS determined after examination of the “entire prostate” in patients with prostate cancer. In this study, the authors evaluated and compared the ability of 4 nomograms (published by Capitanio et al, Chun et al, Kulkarni et al, and Moussa et al) to predict GS upgrades for patients with biopsy GS ≤6 prostate cancer who underwent radical prostatectomy (RP) at their center.METHODS:The entire study cohort included 942 patients with a biopsy GS ≤6. Predictive performances of the nomograms were compared using area under the receiver operating characteristic curve (AUC‐ROC) analysis, calibration plots, and decision curve analysis (DCA) in the entire cohort, in patients with low‐risk prostate cancer (LRPC), and a subgroup of those patients who underwent extended biopsy with ≥10 cores.RESULTS:Patients with a GS ≥7 at prostatectomy included 319 of 942 patients (33.9%) in the entire study cohort, 263 of 814 patients (32.2%) with LRPC, and 84 of 301 patients (27.9%) with LRPC who underwent extended biopsy. With an AUC‐ROC of 0.637 to 0.647 in the different subgroups of patients with low‐risk cancer, the Kulkarni et al nomogram demonstrated significantly higher discriminative ability compared with the other nomograms. The same nomogram provided a small clinical benefit at DCA. All nomograms were poorly calibrated.CONCLUSIONS:The available prognostic tools had limited ability to predict clinically significant upgrading in patients with biopsy GS ≤6 and, thus, the authors concluded that these tools are not ready for clinical application. Cancer 2011;. © 2011 American Cancer Society.
Use of the monoclonal antibody MOC‐31 as an immunomarker for detecting metastatic adenocarcinoma in effusion cytology
Authors: Kundu Uma R. , Krishnamurthy Savitri 
Published: July 2011

AbstractBACKGROUND:MOC‐31 is an established immunologic marker with which to detect adenocarcinomas. The objective of the current study was to evaluate the use of MOC‐31 in the diagnosis of metastatic adenocarcinoma in effusion specimens.METHODS:The authors evaluated cytologic specimens of effusions/washings in which MOC‐31 immunostaining was performed on unstained cell block sections or Papanicolaou‐stained cytospin preparations. Membranous staining with or without cytoplasmic staining was considered to be positive. The immunostaining results were correlated with the cytologic diagnoses and clinical follow‐up data.RESULTS:A total of 215 effusions and washings were identified (cell blocks in 162 cases, cytospin preparations in 53 cases, and both in 2 cases in which MOC‐31 immunostaining was performed). A total of 94 (44%) of the 215 cases were found to be positive for malignancy, including 87 metastatic adenocarcinomas. Specimens were positive for MOC‐31 in 76 (87%; 55 cell blocks and 21 cytospin preparations) of 87 cases of metastatic adenocarcinoma. Eleven cases of metastatic adenocarcinoma were found to be negative for MOC‐31 (4 cases from lung tumors, 2 from stomach tumors, 2 from colon tumors, 2 from breast tumors, and 1 from a renal tumor). Minimal and/or focal cytoplasmic staining for MOC‐31 was noted in 13% of cases of reactive mesothelial cells/mesothelioma. The sensitivity of MOC‐31 for metastatic adenocarcinoma was 89%, the specificity was 100%, the negative predictive value was 92%, and the positive predictive value was 100%.CONCLUSIONS:MOC‐31 alone was found to be highly sensitive for distinguishing reactive mesothelial cells/mesothelioma from metastatic adenocarcinoma in effusion specimens. Interpreting membranous MOC‐31 staining as positive can help prevent confusion between reactive mesothelial cells/mesothelioma and metastatic adenocarcinoma. Cancer (Cancer Cytopathol) 2011;. © 2011 American Cancer Society