bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of the Birch reduction
Authors: Greenfield A. , Schindewolf U. 
Published: July 2012

AbstractBecause of contradictions in the literature, we reinvestigated the kinetics of the Birch reduction, i.e. the hydrogenation of benzene and its derivatives in metal ammonia solutions (MAS: containing solvated electrons e− and metal cations M+) with alcohols to yield the corresponding cyclohexa‐1,4‐dien compounds (e.g. 2 Li+2CH3OH+C6H6⟹2CH3OLi+C6H8). The kinetics of this reaction are obscured since the hydrogen reaction proceeds parallel to it (2Li+2CH3OH⟹2CH3OLi+H2). The two reactions differ in their activation energies (6.5 and 22.5 kJ/Mol resp.); and in the series of the alkali metals Li, Na and K the rate of the Birch reduction decreases, whereas that of the hydrogen reaction increases. However, in the metal concentration range around 0.01 M. both reactions have within the experimental error the same reaction order with respect to the metal (≈︁0.8). Both are accelerated by addition of alkali cations common to the dissolved alkali metal, and both are decelerated by addition of alkali cation complexing cryptands. Thus we conclude that the cations are involved in the kinetics of both reactions, probably by forming intermediate ion pairs or shifting pre‐equilibria in which solvated electrons are involved. The experimental data of both reactions can be described very well with the rate laws v(B) = kBf2[e−][Li+)[CH3OH][C6H6]and v(H)=kHf2[e−][Li+](CH3OH]resp. (f activity coefficients after Debye‐Hückel) inserting the concentrations of e− and Li+ as calculated from the known thermodynamics of LiAS. The experimental rate constants kB and kH are the products of the rate constants of the rate determining steps and the equilibrium constants of the pre‐equilibria.
Large molecules, radicals, ions, and small soot particles in fuel‐rich hydrocarbon flames: Part III: REMPI mass spectrometry of large flame PAHs and fullerenes and their quantitative calibration through sublimation
Authors: Ahrens J. , Keller A. , Kovacs R. , Homann K.‐H. 
Published: July 2012

AbstractLarge polycyclic aromatic hydrocarbons (PAHs) and fullerenes have been studied using nozzle/molecular beam sampling from flames and from a sublimator with subsequent resonance enhanced multi‐photon ionization (REMPI) mass spectrometry. The mass spectrometer was of the time‐of‐flight type with an ion reflector. The sublimator for large molecules generated a definite gas phase concentration of the respective PAHs or fullerene which was controlled by determining the mass loss of the substance in a stream of heated nitrogen. The purpose of these calibrations is the quantitative analysis of these large molecules when sampling fuel‐rich flames. Twenty‐three PAHs with masses up to 596 u (dicoronylene), some oxygen‐containing PAHs, C60, C70, and C84 were used. Sublimation energies of low‐volatility PAHs and of fullerenes were determined.Multi‐photon ionization of PAHs and fullerenes was investigated as function of the effective laser power density in the ion source and the wavelength. Furthermore, ion fragmentation of large PAHs and fullerenes was studied for different power densities and wavelengths. For PAHs with up to about 20 C atoms a wavelength of 265 nm with laser power densities of 0.5 to 1 MW/cm2 are suitable. For larger PAHs, C60. and C70 a wavelength of 208 nm is more favorable. At the shorter wavelength PAHs have considerably higher ionization efficiencies and the fullerenes do not show delayed ionization and fragmentation. Quantitative relationships between the ion signal and the absolute number density for a large number of PAHs and fullerenes in the source were determined for standardized inflow and ionization conditions.
CF3CFHO• radical: Decomposition vs. reaction with O2
Authors: Schneider W. F. , Wallington T. J. , Barker J.R. , Stahlberg E. A. 
Published: July 2012

AbstractTwo puzzles are associated with reactions of the CF3CFHO alkoxy radical: first, the ratio of A‐factors for the reaction with O2 and that for decomposition is about 500 times greater than expected; second, decomposition is more favored when the alkoxy radicals are produced by the reaction of peroxy radicals (RO2) with NO, compared to when they are produced by RO2 radical disproportionation. Recent experimental evidence suggests that a major fraction of the exothermicity of the reaction RO2+NO is deposited into vibrational excitation of the alkoxy radical product. A combined electronic structure and kinetic modeling study has been conducted to examine these issues. The results reported here implicate the reaction with O2 as responsible for the surprisingly large A‐factor ratio. They also support the notion that significant numbers of vibrationally excited CF3CFHO alkoxy radicals are produced in the reaction of peroxy radicals with NO and that the radicals subsequently decompose promptly on a nanosecond time scale.
γ‐Ray polymerization of cationic surfactant methacrylates in lyotropic mesophases
Authors: Pawlowski Dirk , Haibel Astrid , Ticke Bernd 
Published: July 2012

AbstractThe γ‐ray polymerization of (2‐methacryloylethyl)dodecyldimethylammonium bromide 1 and (11‐methacryloylundecyl)trimethylammonium bromide 2 in lyotropic mesophase is described. 1 forms hexagonal (Hα), cubic (Qα) and lamellar phases as indicated by polarizing microscopy and small angle X‐ray scattering (SAXS). Dose versus conversion curves indicate a complete polymerization of 1 in organized aqueous phases, the reaction rate being highest in the Hα phase. 2 is less reactive and polymerization in the Hα phase ceases at about 60% conversion to polymer. Both surfactants polymerize under retention of the macroscopic order of the mesophase. Nanostructured gel‐like materials with hydrophilic and hydrophobic compartments are obtained, which after removal of water can be swollen in polar and nonpolar solvents.
Differential thermal analysis under high pressure on liquid‐crystalline compounds with lateral aromatic branches
Authors: Ernst C. R. , Schneider G. M. , Würflinger A. , Weißflog W. 
Published: July 2012

AbstractThe high pressure phase behaviour of four liquid crystals, belonging to the class of laterally aryl‐substituted mesogens has been studied with differential thermal analysis. The pressure dependence of the phase transitions has been determined up to 300 MPa. Transition enthalpies have been determined with the aid of differential scanning calorimetry. Volume changes accompanying the phase transitions have been calculated using the Clausius‐Clapeyron equation. Several metastable phase transitions have been discovered.
Influences of nuclear mass, size, shape and spin on chemical isotope effect of titanium
Authors: Fujii Toshiyuki , Inagawa Jun , Nishizawa Kazushige 
Published: July 2012

AbstractTitanium isotopes of Ti (III) or Ti (IV) were fractionated by liquid‐liquid extraction system using dicyclohexano‐18‐crown‐6. The nuclear size and shape effect and the nuclear spin effect resulted in the breakdowns of the linear dependency of the enrichment factors to the mass difference. The nuclear mass effect, the nuclear size and shape effect and the nuclear spin effect were calculated by the isotope pair evaluation method. The nuclear mass effects were 0.000634 for 48Ti‐46Ti (III) and 0.000559 for 48Ti‐46Ti (IV), where the total enrichment factor were 0.000989 and −0.000166, respectively. The nuclear size and shape effects were 0.000356 for 48Ti‐46Ti (III) and −0.000725 for 48Ti‐46Ti (IV). The nuclear spin effects were 0.000180 for 47Ti (III), 0.000369 for 49Ti (III), −0.000303 for 47Ti (IV) and −0.000526 for 49Ti (IV). The ratio of chemical effect given by the field shift of 3d‐orbital to that of 4s‐orbital was −1.54, which had same direction and quantity with the field shift ratio of 3d‐orbital to 4s‐orbital in Ti I in atomic spectra. This showed that the nuclear size and shape effect on the chemical isotope effect directly reflected the field shifts of Ti I. The nuclear spin effect was the function of the number of the hyperfine splitting vibrational energy levels and the coordination number. This effect was found when the coordination numbers differ nonstoichiometrically between the aqueous phase and the organic phase.
Comparison of two methods for designing calorimeters using stirred tank reactors
Authors: Regestein Lars , Giese Heiner , Zavrel Michael , Büchs Jochen 
Published: July 2012

AbstractCalorimetry is a robust method for online monitoring and controlling bioprocesses in stirred tank reactors. Up to now, reactor calorimeters have not been optimally constructed for pilot scale applications. Thus, the objective of this paper is to compare two different ways for designing reactor calorimeters and validate them. The “heat capacity” method based on the mass flow of the cooling liquid in the jacket was compared with the “heat transfer” method based on the heat transfer coefficient continuously measured in the cultivation of Escherichia coli VH33 in a 50 L stirred tank reactor. It was found that the values of the “heat transfer” method agreed very well with the calculated values from the oxygen consumption. By contrast, the curve of the “heat capacity” method deviated from that of the oxygen consumption calculated with the oxycaloric equivalent. In conclusion, the “heat transfer” method has been proven to have a higher degree of validity than the “heat capacity” method. Thus, it is a better and more robust means to measure heat generation of fermentations in stirred tank bioreactors on a pilot scale. Biotechnol. Bioeng. 2013; 110: 180–190. © 2012 Wiley Periodicals, Inc.
Reactivity Control of CH Bond Activation over Vanadium–Silver Bimetallic Oxide Cluster Cations
Authors: Li Xiao‐Na , Wu Xiao‐Nan , Ding Xun‐Lei , Xu Bo , He Sheng‐Gui 
Published: July 2012

AbstractVanadium–silver bimetallic oxide cluster ions (VxAgyOz+; x=1–4, y=1–4, z=3–11) are produced by laser ablation and reacted with ethane in a fast‐flow reactor. A reflectron time of flight (Re‐TOF) mass spectrometer is used to detect the cluster distribution before and after the reactions. Hydrogen atom abstraction (HAA) reactions are identified over VAgO3+, V2Ag2O6+, V2Ag4O7+, V3AgO8+, V3Ag3O9+, and V4Ag2O11+ ions, in which the oxygen‐centered radicals terminally bonded on V atoms are active sites for the facile HAA reactions. DFT calculations are performed to study the structures, bonding, and reactivity. The reaction mechanisms of V2Ag2O6++C2H6 are also given. The doped Ag atoms with a valence state of +1 are highly dispersed at the periphery of the VxAgyOz+ cluster ions. The reactivity can be well‐tuned gradually by controlling the number of Ag atoms. The steric protection due to the peripherally bonded Ag atoms greatly enhances the selectivity of the V–Ag bimetallic oxide clusters with respect to the corresponding pure vanadium oxide systems.
Regulation of motility, invasion, and metastatic potential of squamous cell carcinoma by 1α,25‐dihydroxycholecalciferol
Authors: Ma Yingyu , Yu Wei‐Dong , Su Bing , Seshadri Mukund , Luo Wei , Trump Donald L. , Johnson Candace S. 
Published: July 2012

AbstractBACKGROUND:The active metabolite of vitamin D 1α,25‐dihydroxycholecalciferol (1,25D3) has exhibited broad‐spectrum antitumor activity in xenograft animal models. However, its activity against metastatic disease has not been extensively investigated.METHODS:Squamous cell carcinoma (SCC) or 1,25D3‐resistant variant SCC‐DR cells were treated with 1,25D3. Actin organization was examined by immunofluorescence assay. Cell migration was assessed by “wound” healing and chemotactic migration assays. Cell invasion was assessed by a Matrigel‐based invasion assay and in situ zymography. Matrix metalloproteinase 2 (MMP‐2) and MMP‐9 expression and secretion were examined by immunoblot analysis and an enzyme‐linked immunosorbent assay, respectively. E‐cadherin expression was assessed by flow cytometry, immunoblot analysis, and immunohistochemistry. Knockdown of E‐cadherin was achieved by small interfering RNA. An experimental metastasis mouse model was created by intravenous injection of tumor cells; and lung tumor development in the mice was assessed by magnetic resonance imaging, gross observation, and histology.RESULTS:SCC cellular morphology and actin organization were altered by 10 nM 1,25D3. 1,25D3 inhibited SCC cell motility and invasion, which were associated with reduced expression and secretion of MMP‐2 and MMP‐9, and 1,25D3 promoted the expression of E‐cadherin. These findings were not observed in SCC‐DR cells. Knock down of E‐cadherin rescued 1,25D3‐inhibited cell migration. Intravenous injection of SCC or SCC‐DR cells resulted in the establishment of extensive pulmonary lesions in saline‐treated C3H mice. Treatment with 1,25D3 resulted in a marked reduction in the formation of lung tumor colonies in mice that were injected with SCC cells, but not in mice that were injected with SCC‐DR cells.CONCLUSIONS:1,25D3 suppressed SCC cell motility, invasion, and metastasis, partially through the promotion of E‐cadherin‐mediated cell‐cell adhesion. Cancer 2013. © 2012 American Cancer Society.
Genome‐wide identification of Epstein‐Barr virus–driven promoter methylation profiles of human genes in gastric cancer cells
Authors: Zhao Junhong , Liang Qiaoyi , Cheung Kin‐Fai , Kang Wei , Lung Raymond W. M. , Tong Joanna H. M. , To Ka Fai , Sung Joseph J. Y. , Yu Jun 
Published: July 2012

AbstractBACKGROUND:Aberrant methylation of tumor‐related genes has been reported in Epstein‐Barr virus (EBV)‐associated gastric cancers. This study sought to profile EBV‐driven hypermethylation in EBV‐infected cells.METHODS:The EBV‐positive AGS gastric cancer cell line (AGS‐EBV) and EBV‐negative AGS cells were used in this study. DNA methyltransferase‐3b (DNMT3b) activity was assessed by EpiQuick activity assay, and genome‐wide DNA methylation profiles were assessed by methyl‐DNA immunoprecipitation microarray assay.RESULTS:EBV infection was confirmed in AGS‐EBV cells by EBV‐encoded RNA in situ hybridization. Expression and activity of DNA methyltransferase‐3b (DNMT3b) was significantly increased in AGS‐EBV compared to AGS. Ectopic expression of LMP2A (latent membrane protein 2A) in AGS increased activity of DNMT3b. A total of 1065 genes were differentially methylated by EBV infection (fold‐changes ≥ 2, P < .05) in AGS‐EBV compared to AGS cells. The majority of the differentially methylated genes (83.2%, 886 of 1065 genes) had cytosine‐guanine dinucleotide (CpG) hypermethylation in AGS‐EBV (fold‐changes 2.43∼65.2) versus that found in AGS cells. Gene ontology analysis revealed that hypermethylated genes were enriched in the important cancer pathways (≥ 10 genes each, P ≤ .05) including mitogen‐activated protein kinase signaling, cell adhesion molecules, wnt signaling pathway, and so forth. Six novel hypermethylated candidates (IL15RA, REC8, SSTR1, EPHB6, MDGA2, and SCARF2) were further validated. Higher levels of DNA methylation were confirmed for all these genes in AGS‐EBV cells by bisulfite genomic sequencing. Furthermore, these candidates were silenced or down‐regulated in AGS‐EBV cells, but can be restored by demethylation treatment.CONCLUSIONS:EBV infection in AGS cells induced aberrant CpG hypermethylation of 886 genes involving in important cancer‐related pathways. Induction of promoter methylation by EBV is regulated by up‐regulation of DNMT3b through LMP2A. Cancer 2013. © 2012 American Cancer Society.
Phase 2 trial of combined cisplatin, etoposide, gemcitabine, and methylprednisolone (PEGS) in peripheral T‐cell non‐Hodgkin lymphoma
Authors: Mahadevan Daruka , Unger Joseph M. , Spier Catherine M. , Persky Daniel O. , Young Fay , LeBlanc Michael , Fisher Richard I. , Miller Thomas P. 
Published: July 2012

AbstractBACKGROUND:Patients with peripheral T‐cell lymphomas (PTCLs) have inferior progression‐free survival (PFS) and overall survival (OS) compared with patients who have aggressive B‐cell non‐Hodgkin lymphoma. Because PTCLs over express multidrug resistance gene 1/P‐glycoprotein (MDR‐1/P‐gp), we devised platinum, etoposide, gemcitabine, and methylprednisolone (PEGS) with agents that are not substrates of the efflux pump. Gemcitabine was included because of its excellent single‐agent activity in PTCL.METHODS:Patients who had PTCL with stage II bulky disease, stage III or IV disease with extra‐nodal, nodal, and transformed cutaneous presentations were eligible. Patients received intravenous cisplatin 25 mg/m2 on days 1 through 4, etoposide 40 mg/m2 on days 1 through 4, gemcitabine 1000 mg/m2 on day 1, and methylprednisolone 250 mg on days 1 through 4 of a 21‐day cycle for 6 cycles.RESULTS:In total, 34 patients were enrolled, 33 were eligible, and 79% were newly diagnosed. Histologic types were PTCL not otherwise specified (n = 15), anaplastic lymphoma kinase (ALK)‐negative anaplastic large cell lymphoma (n = 4), angioimmunoblastic T‐cell lymphoma (n = 6), or other T‐cell non‐Hodgkin lymphomas (n = 8). Adverse events included 1 grade 5 infection with grade 3 or 4 neutropenia and 9 grade 4 hematologic toxicities. The overall response rate was 39% (47% in PTCL not otherwise specified, 33% in angioimmunoblastic T‐cell lymphoma, 25% in ALK‐negative and 38% in other T‐cell non‐Hodgkin lymphomas). The PFS rate at 2 years was 12% (95% confidence interval, 0.1%‐31%), and the median PFS was 7 months. The OS rate at 2 years was 30% (95% confidence interval, 8%‐54%), and the median OS was 17 months. Immunohistochemical analysis of P‐gp expression revealed strong positivity in a subset of lymphoma cells (n = 6) and tumor endothelium (n = 25).CONCLUSIONS:Overall, PEGS was well tolerated, but OS was not considered promising given the design‐specified targets. These results may serve as a benchmark for future comparisons for non‐CHOP regimens. Cancer 2013. © 2012 American Cancer Society.
Phase 2 trial of linifanib (ABT‐869) in patients with unresectable or metastatic hepatocellular carcinoma
Authors: Toh Han Chong , Chen Pei‐Jer , Carr Brian I. , Knox Jennifer J. , Gill Sharlene , Ansell Peter , McKeegan Evelyn M. , Dowell Barry , Pedersen Michelle , Qin Qin , Qian Jiang , Scappaticci Frank A. , Ricker Justin L. , Carlson Dawn M. , Yong Wei Peng 
Published: July 2012

AbstractBACKGROUND:The efficacy and safety of linifanib (ABT‐869), a selective inhibitor of vascular endothelial growth factor and platelet‐derived growth factor receptor tyrosine kinases, were assessed in this phase 2, single‐arm, open‐label, multicenter trial.METHODS:Eligible patients had unresectable or metastatic hepatocellular carcinoma and had received ≤ 1 prior systemic therapy. Patients received oral linifanib at a fasting dose of 0.25 mg/kg,. The primary endpoint was the progression‐free rate at 16 weeks. Tumor response was assessed every 8 weeks. Secondary endpoints included the time to disease progression, overall survival, and objective response rate. Safety was also assessed.RESULTS:Of the 44 patients enrolled, the majority were Asian (89%), had received no prior systemic therapy (82%), had Child‐Pugh class A hepatic function (86%), and had hepatitis B virus infection (61%). The estimated progression‐free rate at 16 weeks was 31.8% (34.2% for patients with Child‐Pugh class A hepatic function), the estimated objective response rate was 9.1% (10.5% for patients with Child‐Pugh class A hepatic function), the median time to disease progression was 3.7 months (3.7 months for patients with Child‐Pugh class A hepatic function), and the median overall survival was 9.7 months (10.4 months for patients with Child‐Pugh class A hepatic function). The most common linifanib‐related adverse events were diarrhea (55%) and fatigue (52%). The most common linifanib‐related grade 3/4 adverse events were hypertension (25%) and fatigue (14%). Serum levels of biomarkers cancer antigen (CA) 125, cytokeratin fragment (CYFRA)21.1, and protein induced by vitamin K absence or antagonist II (PIVKA) demonstrated potential as prognostic indicators of patient response or outcome.CONCLUSIONS:Single‐agent linifanib was found to be clinically active in patients with advanced hepatocellular carcinoma, with an acceptable safety profile. Cancer 2013. © 2012 American Cancer Society.
Cost analysis of a patient navigation system to increase screening colonoscopy adherence among urban minorities
Authors: Jandorf Lina , Stossel Lauren M. , Cooperman Julia L. , Graff Zivin Joshua , Ladabaum Uri , Hall Diana , Thélémaque Linda D. , Redd William , Itzkowitz Steven H. 
Published: July 2012

AbstractBACKGROUND:Patient navigation (PN) is being used increasingly to help patients complete screening colonoscopy (SC) to prevent colorectal cancer. At their large, urban academic medical center with an open‐access endoscopy system, the authors previously demonstrated that PN programs produced a colonoscopy completion rate of 78.5% in a cohort of 503 patients (predominantly African Americans and Latinos with public health insurance). Very little is known about the direct costs of implementing PN programs. The objective of the current study was to perform a detailed cost analysis of PN programs at the authors' institution from an institutional perspective.METHODS:In 2 randomized controlled trials, average‐risk patients who were referred for SC by primary care providers were recruited for PN between May 2008 and May 2010. Patients were randomized to 1 of 4 PN groups. The cost of PN and net income to the institution were determined in a cost analysis.RESULTS:Among 395 patients who completed colonoscopy, 53.4% underwent SC alone, 30.1% underwent colonoscopy with biopsy, and 16.5% underwent snare polypectomy. Accounting for the average contribution margins of each procedure type, the total revenue was $95,266.00. The total cost of PN was $14,027.30. Net income was $81,238.70. In a model sample of 1000 patients, net incomes for the institutional completion rate (approximately 80%), the historic PN program (approximately 65%), and the national average (approximately 50%) were compared. The current PN program generated additional net incomes of $35,035.50 and $44,956.00, respectively.CONCLUSIONS:PN among minority patients with mostly public health insurance generated additional income to the institution, mainly because of increased colonoscopy completion rates. Cancer 2013. © 2012 American Cancer Society.