bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Theoretical Investigation on N7(H)→N9(H) Tautomerization of Isolated and Monohydrated 2,6‐Dithiopurine Combined with IPCM Solvent Model
Authors: Ren Hongjiang , Wang Wenliang , Wang Weina , Wei Ni 
Published: July 2010

AbstractThe tautomerization reaction mechanism has been reported between N7(H) and N9(H) of isolated and monohydrated 2,6‐dithiopurine using B3LYP/6‐311+G(d,p). The isodensity polarized continuum model (IPCM) in the self‐consistent reaction field (SCRF) method is employed to account for the solvent effect of water on the tautomerization reaction activation energies. The results show that the two pathways P(1) (via the carbene intermediate I1) and P(2) (via the sp3‐hybrid intermediate I2) are found in intramolecular proton transfer, and each pathway is composed by two primary steps. The calculated activation energy barriers of the rate‐determining steps in isolated 2,6‐dithiopurine N7(H)→N9(H) tautomerism are 308.2 and 220.0 kJ·mol−1in the two pathways, respectively. Interestingly, in one‐water molecule catalyst, it dramatically lowers the N7(H)→N9(H) energy barriers by the concerted double proton transfer mechanism in P(1), favoring the formation of 2,6‐dithiopurine N9(H). However, the single proton transfer mechanism assisted with out‐of‐plane water in the first step of P(2) increases the activation energy barrier from 220.0 to 232.3 kJ·mol−1, while the second step is the out‐of‐plane concerted double proton transfer mechanism, indicating that they will be less preferable for proton transfer. Additionally, the results also show that all the pathways are put into the aqueous solution, and the activation energy barriers have no significant changes. Therefore, the long‐range electrostatic effect of bulk solvent has no significant impact on proton transfer reactions and the interaction with explicit water molecules will significantly influence proton transfer reactions.
Isomerizations of CH3SO2: Quantum Chemistry and Topological Study
Authors: Li Xiaoyan , Meng Lingpeng , Zeng Yanli , Zheng Shijun 
Published: July 2010

AbstractThe structures, stabilities and the isomerization reactions of CH3SO2 isomers in a doublet electronic state have been studied at B3LYP/6‐311+ +G (d,p), MP2/6‐311++G (d,p) and CCSD(T)/6‐311++G (d,p) levels. The three different levels of calculation give the similar results: thirteen minimum isomers were located and they were connected by eleven transition states. Among the thirteen isomers, cis‐CH3OSO, trans‐CH3OSO and CH3SO2 are the most stable species, and they should be detected easily in experiment. This is well consistent with the experimental result. These isomers could isomerize to each other by chemical bond vibration, chemical bond rotation and atom migration. The non‐planar ring structure transition state (STS), which was found in this paper, extended the concept of ring STS to the non‐planar systems.
Synthesis, Crystal Structure and Thermal Decomposition Character of an Environmentally‐Friendly Energetic Coordination Compound of [Co(NH3)4(NO3)](NO3)·0.5H2O
Authors: Wang Kun , Zhang Jianguo , Chen Taoping , Zhang Tonglai , Yang Li 
Published: July 2010

AbstractA new coordination compound of [Co(NH3)4(NO3)]NO3·0.5H2O was synthesized by reacting Co(NO3)2 with NH3·H2O aqueous solution. It has been characterized by using elemental analysis, FT‐IR technology, and X‐ray single crystal diffraction analysis. It belongs to the monoclinic crystal system and P(2)/n space group with the unit cell: a=0.74618(1) nm, b=2.26114(4) nm, c=1.04282(2) nm, β=92.038(1) °. The central ion Co(II) displays a stable octahedral configuration, which was constructed with the central ion Co(II), four nitrogen atoms from NH3 molecules and two oxygen atoms from NO−3. The outer sphere was NO−3 and a common crystalline water molecule, which connected the inner sphere by electrostatic force and the intermolecular force. The intermolecular and intramolecular hydrogen bonds constructed a three‐dimensional network structure, which increased the stability of the whole crystal structure. In addition, thermal decomposition character of the title complex was investigated by using TG‐DTG, DSC and FT‐IR technologies. There are two endothermic peaks and one exothermic one in the process of thermal decomposition, and the decomposition residue at 300°C is the mixture of CoO and Co2O3.
A Novel Self‐assembled Dodecameric Water Cluster Stabilized by a Citrate‐Bridged Copper(II) Compound
Authors: Fu Feng , Wu Yapan , Gao Ziwei , Li Dongsheng , Tang Long 
Published: July 2010

AbstractThe crystal structure of [Cu2(cit)(phen)2]·6H2O (1) (citcitrate anion, phen1,10‐phenanthroline) reveals an unusual hydrogen‐bonded water dodecamer. The centrosymmetric dodecamer contains a decameric core with two pensile monomers, which is described as a chair with two handles. The structure, being predicted to be relative stable to other dodecameric structures, is stabilized by hydrogen bonding with the carboxylate groups of citrate ligands. The variable‐temperature magnetic study of 1 shows weak antiferromagnetic interaction.
Microwave Assisted, Solvent Free One Pot Synthesis of Nitriles from Aryl Aldehydes on Melamin Formaldehyde as Solid Support
Authors: Rezaei Ramin , Mohammadi Mohammad Kazem , Rastin Neda 
Published: July 2010

AbstractVarious aryl aldehydes underwent prompt one pot conversion into the corresponding nitriles in high yields by reacting with hydroxylamine hydrochloride supported on melamine formaldehyde under microwave irradiation in the presence of ammonium acetate as catalyst.
Assessment on the Removal of Malachite Green Using Tamarind Fruit Shell as Biosorbent
Authors: Saha Papita , Chowdhury Shamik , Gupta Suyash , Kumar Indresh , Kumar Raj 
Published: July 2010

AbstractTamarind fruit shell was used as a low cost biosorbent for the removal of malachite green from aqueous solution. The various factors affecting adsorption such as agitation, pH, initial dye concentration, contact time, and temperature were investigated. It was observed that the dye adsorption capacity was strongly dependent on solution pH as well as temperature. The equilibrium data were described by the Langmuir, Freundlich, and Temkin isotherm models. The Langmuir isotherm model showed good fit to the equilibrium adsorption data and the maximum adsorption capacity obtained was 1.951 mg/g at 303 K. The kinetics of adsorption followed the pseudo‐second‐order model and the rate constant decreased with increase in temperature indicating exothermic nature of adsorption. The Arrhenius equation was used to obtain the activation energy (Ea) for the adsorption system. The activation energy was estimated to be 63.56 kJ/mol. Thermodynamic parameters such as Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0) were also investigated. Results suggested that adsorption of malachite green onto tamarind fruit shell was a spontaneous and exothermic process. Present investigation suggests that tamarind fruit shell may be utilized as a low cost adsorbent for removal of malachite green from aqueous solution.
Sorption Behavior of Phthalic Acid Esters on Reference Soils Evaluated by Soil Column Chromatography
Authors: Li Binghua , Qian Yuan , Bi Erping , Chen Honghan , Schmidt Torsten C. 
Published: July 2010

AbstractSoils are commonly exposed to phthalic acid esters (PAEs) due to their wide usage in a large variety of fields. Several PAEs have been categorized as priority pollutants due to their environmental impact. Therefore, characterizing the sorption behavior of PAEs on soils is very important. Soil column chromatography was utilized to study sorption of dimethyl phthalate (DMP) and diethyl phthalate (DEP) on European and Chinese reference soils. The influence of different environmental conditions such as ionic strength, temperature and pH on the sorption process was investigated. Results show the organic carbon (OC) content in soil plays a main role in the sorption of DMP and DEP. Ionic strength and cation type influenced sorption of DMP and DEP on the two soils, however, in a different manner suggesting that OC in these two soils might be differently affected by the presence of ions. The sorption of DMP and DEP was also found to depend on the investigated pH range of mobile phase with significant relative changes of sorption coefficients in both soils. The influence of temperature on sorption to both soils was small and derived sorption enthalpies indicated that van der Waal's forces dominate the sorption of DMP and DEP, which leads us to propose that additional specific interactions such as hydrogen bonding only play a negligible role.
Central Composite Design Applied to Optimization of Dispersive Liquid–Liquid Microextraction of Cu(II) and Zn(II) in Water Followed by High Performance Liquid Chromatography Determination
Authors: Farajzadeh Mir Ali , Bahram Morteza , Vardast Mohammed Reza 
Published: July 2010

AbstractIn this study a new method for the simultaneous determination of Cu(II) and Zn(II) ions in water samples was developed by dispersive liquid–liquid microextraction preconcentration followed by HPLC with UV detection. An experimental design, central composite design, coupled with response‐surface methodology was used for the optimization of the involved experimental parameters. In the proposed approach, 8‐hydroxy quinoline (HOX) was used as a chelating agent and chloroform and methanol were chosen as the best extraction and dispersive solvents, respectively. Some factors influencing the extraction efficiency of copper and zinc ions and their subsequent determinations, including extraction and dispersive solvents kinds and volumes, pH of sample solution, concentration of the chelating agent, salting out effect and reaction time were studied and optimized. Under the optimum conditions, the calibration graphs were linear in the range of 10–4000 µg/L with the detection limits of 3 µg/L and the quantification limits of 10 µg/L for both analytes. The RSD for six replicate measurements of 500 µg/L of Cu2+ and Zn2+ were 2.9% and 5.7%, respectively.
Treatment of Acid Blue 113 Dye Solution Using Iron Electrocoagulation
Authors: Saravanan Mohan , Sambhamurthy Nurani Pabmanavhan , Sivarajan Meenatchisundaram 
Published: July 2010

AbstractThe electrocoagulation (EC) treatment of Acid Blue 113 (AB 113) was performed on the basis of chemical oxygen demand (COD) removal efficiency using an iron anode. The process variables, including current density (1–5 A/dm2), pH (5.5–7.5), and supporting electrolyte concentration (1–3 g/L) were investigated. Under the optimum operating conditions, more than 91% COD removal efficiency was found. The optimum conditions were obtained with 3 A/dm2 of current density, pH 6.5, and 2 g/L of supporting electrolyte concentration. COD removal rates obtained during the EC process can be described using a pseudo‐kinetic model. The experimental kinetic data fit well with pseudo first‐order kinetic model, with no significant change on the rate constant after 3 A/dm2 of current density. The absorption spectra and Fourier transform infra red analysis were also performed to characterize the mechanism and nature of dye cleavage.
Studies on the Removal of Arsenate by Electrochemical Coagulation Using Aluminum Alloy Anode
Authors: Vasudevan Subramanyan , Lakshmi Jothinathan , Sozhan Ganapathy 
Published: July 2010

AbstractThe removal of arsenate from aqueous solution was carried out by electrochemical coagulation using aluminum alloy as anode and stainless steel as cathode. Various operating parameters on the removal efficiency of arsenate were investigated, such as initial arsenate ion concentration, initial pH, current density, and temperature. Effect of coexisting anions such as silicate, fluoride, phosphate, and carbonate were studied on the removal efficiency of arsenate. The optimum removal efficiency of 98.4% was achieved at a current density of 0.2 A/dm2 at a pH of 7.0. The experimental data were tested against different adsorption isotherm models for describing the electrochemical coagulation process. The adsorption of arsenate preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. First and second order rate equations were applied to study adsorption kinetics. The adsorption process follows second order kinetics model with good correlation. Temperature studies showed that adsorption was endothermic and spontaneous in nature.
Levels of Chlorinated Paraffins in Water
Authors: Coelhan Mehmet 
Published: July 2010

AbstractWastewater treatment plant influents, effluents, and river water samples were analyzed for chlorinated paraffins (CPs). CPs were not detected in river water samples, in effluents, and in filtered influents by using gas chromatography electron capture negative ion mass spectrometry (GC‐ECNI‐MS) (LOQ = 100 ng/L). However, middle chain chlorinated paraffins (MCCPs) were frequently present in suspended solid matter from influents while short chain chlorinated paraffins (SCCPs) were detected only in 2 of 15 samples. Concentrations of SCCPs and MCCPs measured by GC‐ECNI‐MS varied between n.d. and 4600 ng/L adsorbed on suspended solid matter.
Viable and Rapid Determination of Organochlorine Pesticides in Water
Authors: Ozcan Senar 
Published: July 2010

AbstractVortex‐assisted liquid–liquid microextraction (VALLME) procedure was developed for the determination of different organochlorine pesticides (OCPs) in water samples by GC‐MS. After the determination of the most suitable extraction solvent and rotational speed of the vortex, parameters such as vortex extraction time, solvent volume, ionic strength of the sample were optimized by using a 23 factorial experimental design. The optimized extraction conditions for 5 mL water sample were as follows: extraction solvent, bromoform; solvent volume, 50 µL; vortex extraction time, 2 min at 3000 rpm with no ionic strength adjustment, centrifugation 5 min at 4000 rpm. Limits of detection (LODs) and quantification (LOQs) were in the range of 0.011–0.052 and 0.037–0.173 µg/L, respectively. Mean recoveries of OCPs from fortified water samples are 96% for three different fortification levels between 0.1 and 5 µg/L and relative standard deviations of the recoveries are below 6%. The performance of the developed method was compared with traditional liquid–liquid extraction on real water samples including tap water, well water, surface (lake and stream) water, municipal wastewater, and treated municipal wastewater and comparable extraction efficiencies were obtained. The proposed VALLME procedure requires small volumes of solvent and water sample. It is viable, rapid, and easy to use for the determination of OCPs in water samples by using GC‐MS.
Insulin‐like growth factor‐1 receptor and phosphorylated AKT‐serine 473 expression in 132 resected thymomas and thymic carcinomas
Authors: Zucali Paolo A. , Petrini Iacopo , Lorenzi Elena , Merino Maria , Cao Liang , Di Tommaso Luca , Lee Hye Seung , Incarbone Matteo , Walter Beatriz A. , Simonelli Matteo , Roncalli Massimo , Santoro Armando , Giaccone Giuseppe 
Published: July 2010

AbstractBACKGROUND:Thymic malignancies are rare tumors. The insulin‐like growth factor‐1 (IGF‐1)/IGF‐1 receptor (IGF‐1R) system is involved in the development of the thymus. IGF‐1R expression in thymic epithelial malignancies is unknown.METHODS:The authors investigated the expression of IGF‐1R and phosphorylated AKT serine 473 (p‐AKT) by using immunohistochemistry and examined the clinicopathologic correlations in a retrospective, single‐institution surgical series of 132 patients with thymic epithelial malignancies.RESULTS:Earlier disease stage, less aggressive histologic types, and complete resection were significant positive prognostic factors for disease‐related survival and progression‐free survival, and being a woman was a better prognostic factor for disease‐related survival. IGF‐1R and p‐AKT protein levels were expressed in 20% and 36% of thymic tumors, respectively. Both markers were expressed more commonly in recurrent disease than in primary tumors, in more aggressive subtypes, and in more advanced disease stages. There was a trend toward better survival and progression‐free survival in patients who were negative for IGF‐1R or p‐AKT expression in the whole series. When only the 91 primary tumors, IGF1R expression was associated with worse progression‐free survival (P < .001).CONCLUSIONS:The current retrospective analysis demonstrated that disease stage, tumor histology, sex, and resection type were major prognostic factors in the survival of patients with thymic malignancies. The expression levels of IGF‐1R and p‐AKT in thymic tumors suggested that IGF‐1R is a potential target for treatment. Cancer 2010. Published 2010 by the American Cancer Society.
Lung cancer histology, stage, treatment, and survival in American Indians and Alaska Natives and whites
Authors: Fesinmeyer Megan Dann , Goulart Bernardo , Blough David K. , Buchwald Dedra , Ramsey Scott D. 
Published: July 2010

AbstractBACKGROUND:Studies of lung cancer disparities between American Indians and Alaska Natives (AIANs) and whites have yielded mixed results. To the authors' knowledge, no studies to date have investigated whether race‐based differences in histology could explain survival disparities.METHODS:Data were obtained on AIANs and whites with lung cancer from the 17 population‐based cancer registries participating in the Surveillance, Epidemiology, and End Results (SEER) program from 1973 to 2006. Logistic regression was used to determine whether race and other covariates were associated with histology, stage at diagnosis, and receipt of surgery. Cox regression was used to determine the risk of death associated with race, after adjusting for histology, stage, and other covariates.RESULTS:Histology, but not race, was found to be associated with stage at diagnosis, and both race and stage were found to be associated with histology. AIANs were less likely to receive surgery than whites, after adjusting for patient and tumor characteristics. Survival improved for both AIANs and whites after 2000, compared with the 1973 through 1999 period, but survival was consistently shorter for AIANs. The association between AIAN race and decreased survival was strongest in the later time period.CONCLUSIONS:Lung cancer histology appears to be associated with tumor characteristics, treatment, and survival. AIAN race is associated with tumor histology, receipt of surgery, and survival. In the future, studies with access to smoking data, patient comorbidity information, and health systems‐level data will be able to identify factors responsible for the disparities observed in these analyses. Cancer 2010. © 2010 American Cancer Society.
Development of curcumin as an epigenetic agent
Authors: Fu Siqing , Kurzrock Razelle 
Published: July 2010

AbstractThe clinical benefits of curcumin as a single agent were demonstrated in patients with advanced pancreatic cancer in a phase 2 study despite pharmacokinetic analysis showing a much lower plasma concentration of curcumin in humans than in vitro. The diverse and broad biological activities of curcumin are mediated through direct interaction of curcumin with target proteins as well as epigenetic modulation of target genes, supported by evidence that curcumin modulates gene expression in a time‐ and concentration‐dependent manner in human cancer cells. This review delineates the novel mechanisms of curcumin as an epigenetic agent through its interaction with histone deacetylases, histone acetyltransferases, DNA methyltransferase I, and microRNAs. Accumulating data support curcumin's functionality in modulating multiple biological processes at low concentrations through its activity as an epigenetic agent. The development of curcumin as an epigenetic agent warrants further preclinical and clinical studies to explore its diversity and efficacy in cancer treatment and in combination with other anticancer agents. Cancer 2010. © 2010 American Cancer Society.
Trends in incidence and survival of pediatric and adolescent patients with germ cell tumors in the United States, 1975 to 2006
Authors: Poynter Jenny N. , Amatruda James F. , Ross Julie A. 
Published: July 2010

AbstractBACKGROUND:Pediatric germ cell tumors (GCTs) are rare and heterogeneous tumors with uncertain etiology. In the current study, data from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Program were used to evaluate trends in incidence and survival of GCTs in boys and girls ages ≤19 years. To the authors' knowledge, few studies to date have evaluated trends in pediatric GCTs. Results from these analyses may provide clues to the etiology of GCTs.METHODS:Frequencies, incidence rates, and 5‐year relative survival rates stratified by sex were evaluated overall and by demographic subgroups based on age (birth to 9 years and 10‐19 years), race (white, black, and other), and ethnicity (non‐Hispanic and Hispanic) as sample size permitted.RESULTS:In whites, the incidence of GCTs was lower for females than males in the 10‐year to 19‐year age group (rate ratio [RR], 0.47; 95% confidence interval [95% CI], 0.42‐0.53), whereas the rates were similar in the age group for birth to 9 years. In contrast, incidence rates were higher in black females than in black males in both age groups (RR, 2.01 [95%CI, 1.08‐3.84] in those ages birth to 9 years; RR, 3.30 [95% CI, 2.13‐5.28] in those ages 10‐19 years). The incidence of ovarian GCT was significantly higher in Hispanic compared with non‐Hispanic girls in the groups aged 10 to 19 years. Incidence rates increased during the study period in boys ages 10 to 19 years (annual percentage change [APC], 1.2; 95% CI, 0.4‐2.1) and girls ages birth to 9 years (APC, 1.9; 95% CI, 0.3‐2.5).CONCLUSIONS:The incidence of pediatric GCTs in the United States appears to be increasing only in certain subgroups, suggesting that the etiology is not completely overlapping in all age groups. Differences in incidence patterns by race and ethnicity merit further investigation. Cancer 2010. © 2010 American Cancer Society.
Healthcare use after screening for lung cancer
Authors: Byrne Margaret M. , Koru‐Sengul Tulay , Zhao Wei , Weissfeld Joel L. , Roberts Mark S. 
Published: July 2010

AbstractBACKGROUND:To evaluate the benefits of lung cancer screening, all effects of screening need to be considered. The aim of this study was to determine whether screening had an effect on healthcare use, specifically whether use increased for those with a false‐positive or indeterminate screening result.METHODS:Recruited were 400 individuals participating in a lung cancer screening study at the University of Pittsburgh. Self‐reported outpatient healthcare use information was collected for the 6 months before, 0 to 6 months after, and 6 to 12 months after screening. The screening outcomes were negative, indeterminate, and suspicious. Repeated‐measures Poisson regression models were used to examine changes in use over time and how changes over time varied among the screening outcome groups.RESULTS:Approximately 58% of participants had a negative screening result, 36% had an indeterminate result, and approximately 6% had a suspicious result. The percentage of individuals who had any incidence of each type of outpatient use increased after screening, with the greatest increase noted for those with a suspicious screening result. Adjusted mean use significantly increased for nearly all types of use and for all 3 screening results categories in the 6 months after screening, but mostly declined to prescreening levels in the next 6 months.CONCLUSIONS:Outpatient healthcare use was found to increase after screening for all individuals who were screened for lung cancer, regardless of the screening finding. The cost of the lung‐related visits alone was substantial. Therefore, if lung cancer screening prevalence is increased, attendant follow‐up healthcare costs are also likely to increase. Cancer 2010. © 2010 American Cancer Society.