bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbenes in polycyclic systems: generation and fate of potential adamantane‐1,3‐dicarbenes
Authors: Klaić Lada , Alešković Marija , Veljković Jelena , Mlinarić‐Majerski Kata 
Published: February 2008

AbstractPotential formation and reactions of adamantane‐1,3‐dicarbenes 1–3 generated under different conditions and from different precursors, such as sodium salt of adamantane‐1,3‐dicarbaldehyde ditosylhydrazone (4a), sodium salt of 1,3‐diacetyladamantane ditosylhydrazone (5a), sodium salt of 1,3‐dibenzoyladamantane ditosylhydrazone (6a), and 1,3‐bis(diazobenzyl)adamantane (7) are reported. Carbene species generated thermally from 4a yielded bishomoadamantane (15), as a final product, via intramolecular insertion into adjacent CC bond and formation of putative anti‐Bredt olefin species, followed by hydrogen abstraction. Pyrolysis of the same sodium salt 4a in the presence of hydrogen donor n‐Bu3SnH afforded 1,3‐dimethyladamantane (17). Thermal decomposition of sodium salt 5a afforded 1,3‐divinyladamantane (14). However, thermal decomposition of sodium salt 6a and diazo‐precursor 7 gave benzonitrile as a sole identified product. On the contrary, photolysis of 7 afforded dimeric azine 21. Finally, the synthetic pathways of novel tosylhydrazone derivatives 4, 5, 6 and their corresponding sodium salts, as well as bis‐diazocompound 7 are described. Copyright © 2008 John Wiley & Sons, Ltd.
Initiator selectivity during free radical copolymerizations of styrene and methyl methacrylate initiated by anaerobic copper(II) oxidation of carbon‐13 labeled acetophenone
Authors: Harwood H. James , McNamara Kristin , Johnson James J. , Wyzgoski Faith J. 
Published: February 2008

AbstractNuclear magnetic resonance (NMR) analysis of the 13C‐labeled chain ends of polystyrene, polyMMA, and styrene‐MMA copolymers prepared by polymerizations initiated using 13C‐labeled‐phenacyl radicals were investigated. The phenacyl radicals were generated by anaerobic oxidation of acetophenone‐methyl‐13C using a Cu(II) octanoate‐pyridine complex in the presence of triethylamine and triphenylphosphine. NMR analysis of the 13C‐labeled chain ends of these polymers afforded insight into the initiation mechanism. In copolymerization experiments using 13C‐labeled acetophenone initiator, the NMR spectra provided evidence that the phenacyl radical reacts 2.7 times faster with styrene than with MMA. The resonances of the labeled phenacyl carbons also showed that the sequence and stereosequence distributions of monomer units at the chain ends are nearly the same as those that prevail along the polymer chains. Styrene–styrene, styrene–MMA, and MMA–styrene enchainments at the chain ends are equally likely to have meso (erythro) or racemic(threo) configurations but the ratio of meso to racemic MMA‐MMA enchainments is ∼ 3/7. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2347–2356, 2008
Bipolar poly(p‐phenylene vinylene)s bearing electron‐donating triphenylamine or carbazole and electron‐accepting quinoxaline moieties
Authors: Karastatiris Panayiotis , Mikroyannidis John A. , Spiliopoulos Ioakim K. 
Published: February 2008

AbstractTwo new poly(phenylene vinylene)s (PPVs) carrying electron‐donating triphenylamine or carbazole and electron‐deficient quinoxaline units were synthesized and characterized. Their properties were compared with those of PPV containing only quinoxaline unit. The two polymers showed PL maximum at 501–510 in solution and 533–540 in thin film. Because of the presence of electron donor and acceptor units they displayed strong intramolecular charge transfer (ICT) effects; hence, low‐photoluminescence quantum yields. The polymers showed reversible electrochemical reduction with electron affinity of 2.75 eV and irreversible oxidation with ionization potential of 5.10–5.24 eV. Single‐layer LED of configuration ITO/PEDOT/polymer/Al showed low turn‐on voltage at 5 V, but limited brightness of 50–60 cdm−2. The electroluminescence maximum was voltage‐tunable varying from 500 to 542 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2367–2378, 2008
Pressure‐induced molecular assembly of hydrogen‐bonded polymers
Authors: Mutsuo Shingo , Yamamoto Kazuya , Furuzono Tsutomu , Kimura Tsuyoshi , Ono Tsutomu , Kishida Akio 
Published: February 2008

AbstractControlling the noncovalent bondings such as electrostatic interaction, van der Waals force and hydrogen bond, is the key factor to generate molecular assembly. We show that pressure is one of the most intensive variables for controlling these intermolecular forces and producing assembled structure. Macrogel and nanoparticles of hydrogen‐bonded polymers were simply obtained through an ultrahigh‐pressure process. The morphology of the obtained assembly depends on concentration and various conditions of the pressurization. These results indicate that the ultrahigh‐pressure induces inter/intra‐hydrogen bond, which is strong enough to maintain microassemblies such as gels and particles. This methodology leads to the molecular design of pressure‐induced molecular assembly, and nonharmful processes for molecular separation and drug development. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 743–750, 2008
PVDF/PMMA brushes membrane for lithium‐ion rechargeable batteries prepared via preirradiation grafting technique
Authors: Li Zhiming , Wei Jiangong , Shan Feng , Yang Jun , Wang Xinling 
Published: February 2008

AbstractPoly(methyl methacrylate) (PMMA) was anchored to multiporous poly(vinylidine fluoride) (PVDF) surface via electron beam preirradiation grafting technique to prepare PVDF/PMMA brushes. The conformation of the PVDF/PMMA brushes was verified through Attenuated total reflection‐Fourier transform infra red spectroscopy (ATR‐FTIR), energy dispersive X‐ray spectroscopy (EDX), and scanning electron microscopy (SEM). Thermal stability of PVDF/PMMA brushes was characterized by thermo gravimetric analysis (TGA). The degradation of PVDF/PMMA brushes showed a two‐step pattern. PVDF/PMMA brushes membrane could be used as polymer electrolyte in lithium‐ion rechargeable batteries after it was activated by uptaking 1 M LiPF6/EC‐DMC (ethylene carbonate/dimethyl carbonate; EC:DMC = 1:1 by volume) electrolyte solution. The activated membrane showed high ionic conductivity, 6.1 × 10−3 S cm−1 at room temperature, and a good electrochemical stability up to 5.0 V. The excellent performances of multiporous PVDF‐g‐PMMA membranes suggest that they are suitable for application in high‐performance lithium‐ion batteries. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 751–758, 2008
Thermal regime of openwork block fields on the mountains Elgåhogna and Sølen, central‐eastern Norway
Authors: Juliussen Håvard , Humlum Ole 
Published: February 2008

AbstractGround temperatures in openwork blocky debris are frequently lower than in bedrock or regolith with a matrix of fine sediment, creating a negative temperature anomaly. Two years of temperature measurements in seven 1‐m‐deep profiles located in central‐eastern Norway showed that mean annual ground temperatures were 1.3–2.0°C lower in block fields (felsenmeer) compared with till and bedrock. These data suggest that mountain permafrost can be present in block fields several hundred metres lower than in bedrock and till, providing other conditions remain the same. Better thermal coupling of the ground and the air in winter was responsible for the observed anomaly, probably caused by enhanced conduction through blocks protruding into and through the snow and thereby acting as efficient heat bridges. Convection in the blocky debris, which has been used previously as an explanation of the negative thermal anomaly, was less important than initially presumed. Copyright © 2008 John Wiley & Sons, Ltd.
Airway inflammation and lung function decline in childhood post‐infectious bronchiolitis obliterans
Authors: Cazzato Salvatore , Poletti Venerino , Bernardi Filippo , Loroni Leonardo , Bertelli Luca , Colonna Stefano , Zappulla Franco , Timoncini Giuseppe , Cicognani Alessandro 
Published: February 2008

AbstractPost‐infectious bronchiolitis obliterans (PBO) is a rare form of chronic obstructive lung disease in children with few data on the pulmonary function outcome and underlying inflammatory process. The aim of this study was to determine the change in lung function over time and to investigate by bronchoalveolar lavage (BAL) the inflammatory characteristics of pulmonary involvement.Eleven Caucasian children with PBO were evaluated to estimate the average rate of change in lung function indices using a mixed model. The differential cytology and lymphocyte subsets of BAL fluid were analyzed.The median follow‐up was 10.2 (IQR 3.2–12) years. The estimated forced expiratory volume in 1 sec (FEV1) had a baseline intercept of 57% predicted (62% predicted after bronchodilator) at 10 years of age which fell at a rate of 1.01% per year whereas the estimated forced expiratory flow 25–75 (FEF25–75) had a baseline intercept of 36% predicted (42% predicted after bronchodilator) at 10 years of age which fell at a rate of 1.04% per year. The estimated FEV1/FVC ratio had a baseline intercept of 70% (74% after bronchodilator) at 10 years of age which declined with an average slope of 1.02% per year (−1.10% per year after bronchodilator). Although the baseline and post‐bronchodilator level of estimated FVC was abnormal (68% and 69% predicted, respectively) it did not change significantly with time.The median disease duration at BAL evaluation was 3.7 (IQR 0.7–8) years. The percentage differential cell counts were characterized by a significant increase in neutrophils (median 50%, IQR 1–66%), and a slight increase of lymphocytes (median 14%, IQR 7.5–15%).In conclusion, pulmonary function in childhood PBO is characterized by significant airway obstruction which deteriorates over time. The presence of an ongoing inflammatory process could explain the decline in lung function over time. Pediatr Pulmonol. 2008; 43:381–390. © 2008 Wiley‐Liss, Inc.
Neonatal pulmonary sequestration: Clinical experience with transumbilical arterial embolization
Authors: Lee Byong Sop , Kim Jin Taek , Kim Ellen Ai‐Rhan , Kim Ki‐Soo , Pi Soo‐Young , Sung Kyu‐Bo , Yoon Chong Hyun , Goo Hyun Woo 
Published: February 2008

AbstractPulmonary sequestration (PS) is a rare congenital malformation of the lower respiratory tract. The exact natural course of PS is not well understood and there are no well‐established treatment guidelines for antenatally diagnosed PS. The aim of this study was to describe clinical outcomes in neonates with PS and to evaluate the efficacy of transumbilical arterial embolization (TUE). From 1998 to 2006, total 30 neonatal cases were included. Serial antenatal ultrasound in 26 cases found 6 (23%) regressed lesions, all of which were demonstrated on postnatal chest CT. Six (20%) cases were classified as mixed‐type (combined cystic) lesions. Surgery was performed early (during initial hospitalization) in two cases and lately (after the neonatal period) in four cases. TUE was performed for 17 (57%) cases of intrapulmonary PS. Follow‐up images obtained a median of 19 months (range, 4–51) after TUE demonstrated complete (9, 53%), partial (5, 29%), and no (3, 18%) regression. The regression rate was significantly higher in solid‐type lesions (13/13, 100%) than in mixed‐type (1/4, 25%) (P = 0.006). Complications included transient hypertension (two cases, 12%), post‐embolization fever (two cases, 12%) and migration of a microcoil (one case, 6%), without long‐term morbidities. Natural courses could be observed in 10 cases of extralobar PS and regression was observed in 2 cases (20%) during a median follow‐up of 12 months (range, 6–45). A well‐designed comparative study is warranted to evaluate the long‐term efficacy and safety of TUE. Pediatr Pulmonol. 2008; 43:404–413. © 2008 Wiley‐Liss, Inc.
Longitudinal analysis of androgen deprivation of prostate cancer cells identifies pathways to androgen independence
Authors: D'Antonio Jason M. , Ma Changqing , Monzon Federico A. , Pflug Beth R. 
Published: February 2008

AbstractBACKGROUNDFollowing androgen ablation therapy, the majority of prostate cancer patients develop treatment resistance with a median time of 18–24 months to disease progression.METHODSTo identify molecular targets that promote prostate cancer cell survival and contribute to androgen independence, we evaluated changes in LNCaP cell gene expression during 12 months of androgen deprivation. At time points reflecting critical growth and phenotypic changes, we performed Affymetrix expression array analysis to examine the effects of androgen deprivation during the acute response, during the period of apparent quiescence, and following the emergence of a highly proliferative, androgen‐independent prostate cancer cell phenotype (LNCaP‐AI).RESULTSWe discovered alterations in gene expression for molecules associated with promoting prostate cancer cell growth and survival, and regulating cell cycle progression and apoptosis. Additionally, expression of AR co‐regulators, adrenal androgen metabolizing enzymes, and markers of neuroendocrine disease were significantly altered.CONCLUSIONSThese findings contribute greatly to our understanding of androgen‐independent prostate cancer. The value of this longitudinal approach lies in the ability to examine gene expression changes throughout the adaptive response to androgen deprivation; it provides a more dynamic illustration of genes which contribute to disease progression in addition to specific genes which constitute an androgen‐independent phenotype. Prostate 68: 698–714, 2008. © 2008 Wiley‐Liss, Inc.
Histopathological evidence for an association of inflammation with ductal pin‐like lesions but not with ductal adenocarcinoma in the prostate of the noble rat
Authors: Bernoulli Jenni , Yatkin Emrah , Laakso Arto , Anttinen Mikael , Bosland Maarten , Vega Katherine , Kallajoki Markku , Santti Risto , Pylkkänen Liisa 
Published: February 2008

AbstractBACKGROUNDChronic inflammation may contribute to the development of prostate cancer. The goal of this study was to determine the possible association of prostatic inflammation, prostatic intraepithelial neoplasia (PIN)‐like lesion, and prostate cancer, and to assess the androgen and estrogen dependency of the early steps of carcinogenesis.METHODSNoble rats were treated with testosterone and estradiol implants for 13, 18, or 26 weeks. Hormone dependency of the lesions was studied in a subset of animals by removing hormone implants for 3 weeks after 15 weeks treatment time.RESULTSAfter treatment for 13 weeks, acute and chronic inflammation was found in the dorsolateral prostate lobes and both inflammation and PIN‐like lesions were present in the periurethal area of the prostate in all animals (n = 8). Following hormone exposure for 18 and 26 weeks, inflammation in the prostate remained, and adenocarcinomas in the periurethal prostate area with no adjacent inflammation were observed in all 18 animals studied. When both hormone implants were removed after 15 weeks, PIN‐like lesions progressed further to adenocarcinoma only in two of seven animals. When only the estradiol implants were removed, three of five animals developed adenocarcinomas.CONCLUSIONSEven though adenocarcinomas were not morphologically associated with inflammation, PIN‐like lesions preceding adenocarcinoma were found in close association with inflammation, pointing towards a possible initiator role of inflammation in the early steps of prostatic carcinogenesis. Further, these results indicate that both androgens and estrogens together play a significant role in the induction of inflammation and prostatic cancer in this model. Prostate 68: 728–739, 2008. © 2008 Wiley‐Liss, Inc.
Increased spermine oxidase expression in human prostate cancer and prostatic intraepithelial neoplasia tissues
Authors: Goodwin Andrew C. , Jadallah Sana , Toubaji Antoun , Lecksell Kristen , Hicks Jessica L. , Kowalski Jeanne , Bova G. Steven , De Marzo Angelo M. , Netto George J. , Casero Robert A. 
Published: February 2008

AbstractBACKGROUNDInflammation has been strongly implicated in prostate carcinogenesis, but the precise molecular mechanisms linking inflammation and carcinogenic DNA damage are not known. Induction of the polyamine catabolic enzyme, spermine oxidase (SMO) has been linked to increased reactive oxygen species (ROS) and DNA damage in human gastric and lung epithelial cells and suggest direct mechanistic links between inflammation, SMO activity, ROS production, and epithelial carcinogenesis that are likely relevant in prostate cancer.METHODSTissue microarrays consisting of matched normal and diseased specimens from patients diagnosed with prostate cancer, prostatic intraepithelial neoplasia (PIN), or proliferative inflammatory atrophy (PIA), as well as unaffected individuals, were stained for SMO expression and analyzed using image analysis techniques and TMAJ software tools.RESULTSAverage SMO staining was significantly higher in prostate cancer and PIN tissues compared to patient‐matched benign tissues. Benign tissues from prostate cancer, PIN, and PIA patients also exhibited significantly higher mean SMO expression versus tissues from prostate disease‐free patients.CONCLUSIONSTissues from patients diagnosed with prostate cancer and PIN exhibit, on average, locally increased SMO expression in regions of prostatic disease and higher overall SMO expression in prostatic epithelial cells compared to healthy individuals. Further studies are warranted to directly examine the role of SMO‐produced ROS in prostate carcinogenesis. Prostate 68: 766–772, 2008. © 2008 Wiley‐Liss, Inc.
Quantum Monte Carlo and genetic algorithm study of the potential energy surface of the H molecule
Authors: e Silva Geraldo M. , Gargano Ricardo , da Silva Washington B. , Roncaratti Luiz F. , Acioli Paulo H. 
Published: February 2008

AbstractIn this article we present a characterization of the vibrational spectrum of the H molecule using the correlation function quantum Monte Carlo (CFQMC) method and a genetic algorithm study of the topology of the potential energy surface (PES) used. The vibrational modes associated with the H‐H2 torsion and stretching possess very flat minima. As a consequence the fundamental frequencies corresponding to these modes are poorly described in the harmonic approximation. In our genetic algorithm study of the PES using Cartesian coordinates we have found some unexpected minima. A careful analysis shows that, in the curvilinear coordinates in which the potential is described, some of these minima have identical coordinates. Nevertheless, they represent nonequivalent molecular geometries. The vibrational frequencies obtained in this work are not in good agreement with available experimental data as well as other computational methods. It shows that our method of detailed analysis of PESs could reveal shortcomings introduced by the use of curvilinear coordinates. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Quantum reactive study of a potential energy surface obtained via genetic algorithm
Authors: Salviano Lucas R. , Silva Geraldo M. E , Martins João B. L. , Gargano Ricardo 
Published: February 2008

AbstractIn this work, we performed a quantum reactive study using a new potential energy surface (PES) fitted to the Na + HF→NaF + H reaction. The new PES was obtained using the genetic algorithm optimization technique (GAOT). We calculated the reactive probabilities (RP) of the Na + HF system using the new PES. The GAOT RP are compared with the obtained RP using two other PES found to the Na + HF system: Bond Order 5 (BO5) and the generalized simulated annealing (GSA) PES. We found that the GAOT RP are in excellent agreement with the GSA and BO5 RP. It should be point out that the BO5 RP are considered the benchmark of literature. Therefore, the GAOT is shown to be an appropriate method to fit PES of reactive systems. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Tautomeric preferences and electron delocalization in biurets, thiobiurets, and dithiobiurets: Anab initiostudy
Authors: Adane Legesse , Bharatam Prasad V. 
Published: February 2008

AbstractIn several literature reports biuret and its sulfur analogs are reported to exist in their diketo form with general formula H2NCXNHCYNH2(X = O, Y = O, biuret; X = Y = S, dithiobiuret; and X = O, Y = S, thiobiuret). On the other hand, recently reported results on the electronic structure of biguanide analogs (X = Y = NH)demonstrated that a form equivalent to diketo is not the preferred structure. Thus, a systematicab initiostudy on the tautomeric preferences of biuret and its sulfur analogs (dithiobiuret and thiobiuret) has been carried out. The results indicate that an interplay of conjugative stabilization and intramolecular hydrogen bonding to play a role in tautomeric preferences. Energy and geometric parameters, natural bond orbital analyses have been employed to understand the chemistry of the title compounds. The results indicate that unlike biguanides, these compounds prefer diketo forms containing hydrogen on the bridging nitrogen (N4) and in atrans‐arrangement (1a–4a). However, tautomerization of these keto forms to the corresponding enol isomers was also found to be highly probable. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Characterization of perfluoroalkyl acrylic oligomers by electrospray ionization time‐of‐flight mass spectrometry
Authors: Romack Timothy J. , Danell Allison S. , Cottone Tara M. , Dutta Subodh K. 
Published: February 2008

AbstractElectrospray ionization time‐of‐flight mass spectrometry (ESI‐ToF‐MS) has been successfully employed for the characterization of molecular weight, molecular weight distribution and end groups for bromine‐terminated perfluoroalkyl acrylate oligomers prepared using atom transfer radical polymerization. Intact oligomers and smaller quantities of common side products were observed from m/z 1000 to 4000 cationized with a sodium ion, a difluorobenzyl cation or a proton with a minimum of multiply charged species. Number average molecular weight and weight average molecular weight for both the samples that were characterized were in reasonable agreement with independent measurements conducted using GPC‐MALS and 1H NMR spectroscopy. Copyright © 2008 John Wiley & Sons, Ltd.
Advanced Cantilevers for Magnetic Force Microscopy and High Frequency Magnetic Force Microscopy
Authors: Koblischka M. R. , Wei J. D. , Richter C. , Sulzbach T. H. , Hartmann U. 
Published: February 2008

AbstractIn order to improve the spatial resolution achieved by magnetic force microscopy (MFM) technique and its derivatives, we employ here advanced MFM tips fabricated by means of focused ion beam (FIB) milling. The magnetic coating applied on these tips is a CoCr film of 10 nm thickness. The MFM measurements on hard disk test samples reveal the achieved high resolution, and the measurement on a garnet film demonstrates the low invasiveness. High‐frequency MFM (HF‐MFM) is a development of the MFM technique to observe the HF stray fields emerging from magnetic recording writer poles at their operating conditions. By means of HF‐MFM, magnetic recording writer poles are characterized in the frequency range 100–1,000 MHz. Up to now, all HF‐MFM experiments conducted were using standard MFM cantilevers. From the HF‐MFM images obtained using the advanced MFM cantilevers, it is clearly seen that the spatial resolution is considerably improved over the images obtained using standard MFM tips. However, the 10 nm thick magnetic coating of the cantilevers is found to work properly only at frequencies of up to about 500 MHz. SCANNING 30: 27–34, 2008. © 2008 Wiley Periodicals, Inc.