bluuebunny/crossref_metadata_2025 huggingface dataset:
Dithieno‐ and thienobenzothiazines
Authors: Grol C. J.
Published: April 2009

The synthesis of some isomeric dithienothiazine systems has been described. These thiazines were made by an Ullman type cyclization reaction, starting with the appropriate dithienyl‐sulphides. During the ring closure reaction hydrogen chloride was eliminated from the β‐chloro‐propionyl side chain resulting in the formation of the acryloylthiazines5, 7and11. This reaction was studied under various conditions and some of the byproducts were identified. The general applicability of the reaction was demonstrated by the synthesis of two isomeric thienobenzothiazines14and16. Addition ofN‐methylpiperazine afforded the (N‐methylpiperazinyl)propionylthienothiazines, which were isolated as their hydrochloride salts. The latter compounds were tested for neuroleptic and antidepressive properties, but were shown to be devoid of activity. This lack of activity is discussed in terms of the hampered formation of the radicalcations, as was shown by the electrochemical oxidation of these compounds. Efforts to reduce the carbonyl function to give the propyl chain failed, due to an elimination of the side chain.
Polycyclic azetidines. I. The preparation of benzo [c]‐cis‐6‐azabicyclo[3.2.0] heptane
Authors: Murray Robert J. , Cromwell Norman H.
Published: April 2009

The title compound was prepared from compounds readily obtained from 2‐carbomethoxy‐I‐indanone oxime (5) or from the N‐chlorosulfonyl isocyanate adduct of indene (9). Apart from its ability to undergo transformation to the azetidine, compound 9 upon refluxing with excess LAII was found to undergo reductive decompostion to cis‐2‐hydroxymethyl‐1‐indanamine (2).
The chemistry of 4‐hydrazino‐7‐phenylpyrazolo[1,5‐a] ‐1,3,5‐triazines
Authors: Kobe Joze , O'Brien D. E. , Robins R. K. , Novinson Thomas
Published: April 2009

The reaction of 4‐hydrazino‐7‐phenylpyrazolo[1,5‐a]‐1,3,5‐triazine (4) with nitrous acid gave 8‐phenyltetrazolo[1,5‐e]pyrazolo[1,5‐a]‐1,3,5‐triazine (5b), which was determined by pmr and ir spectra to be in equilibrium with 4‐azido‐7‐phenylpyrazolo[1,5‐a]‐1,3,5‐triazine (5a). The equilibrium between the tetrazolo (5b) and azido (5a) forms was studied by pmr and an attempt was made to determine if substituents in the pyrazole nucleus could sufficiently stabilize the tricyclic tetrazolo form (5b) over the bicyclic azido form (5a). Thermal degradation of 5(a ⇌ b) in an aprotic solvent gave 4‐amino‐7‐phenylpyrazolo[1,5‐a]‐1,3,5‐triazine (7), indicating the probability of a nitrene mechanism involved in the decomposition. Heating 5 in aqueous base gave both 7 and the “hydroxy” analog, 7‐phenylpyrazolo[1,5‐a]‐1,3,5‐triazin‐4(3H)one (6), further substantiating the existence of a nitrene intermediate with a competing nucleophilic displacement of the azido group by a hydroxyl group. Cyclization of 4 with diethoxymethylacetate (DEMA) gave 8‐phenyl‐s‐triazolo[4,3‐e]pyrazolo[1,5‐a]‐1,3,5‐triazine (8), which underwent thermal rearrangement to 8‐phenyl‐s‐triazolo[2,3‐e]pyrazolo[1,5‐a]‐1,3,5‐triazine (9). Acid catalyzed ring opening of 9 with formic acid gave 3‐N‐formamido‐5‐phenyl‐2(2‐s‐triazolyl)pyrazole (10). The failure of 10 to recyclize to 9 with the resultant loss of water, supported the theory that the rearrangement of 8 to 9 might occur simply as a concerted, thermally induced “anhydrous” rearrangement rather than via a covalently hydrated intermediate or a Dimroth type mechanism (in the base catalyzed rearrangement).
The synthesis of novel dipyridazinothiazine ring systems
Authors: Wise Dean S. , Castle Raymond N.
Published: April 2009

The synthesis of several dipyridazinothiazines have been accomplished by: (a) cyclization in concentrated hydrochloric acid solution of the appropriate intermediates; and (b) via the Smiles rearrangement in either basic or glacial acetic acid solution of the appropriate intermediates. The following ring systems have been prepared and characterized: 10H‐dipyridazino‐[4,3‐b:4′,5′‐e]‐1,4‐thiazine, 5H‐dipyridazino[3,4‐b:4′,5′‐e]‐1,4‐thiazine, 10H‐dipyridazino[4,5‐b:‐4′,5′‐e]‐1,4‐thiazine, 5Hdipyridazino[5,4‐b:4′,3′‐e]‐1,4‐thiazine, and 10H‐dipyridazino[3,4‐b:‐3′,4′‐e]‐1,4‐thiazine.
Nitration of 2,3′‐bithienyl
Authors: Dell'Erba Carlo , Guanti Giuseppe , Garbarino Giacomo
Published: April 2009

The nitration of 2,3′‐bithienyl (1) with fuming nitric acid in acetic anhydride at 0° gives a mixture of 3‐nitro‐ (2), 2′ ‐nitro‐ (3) and 5‐nitro‐2,3′‐bithienyl (4) with relative percentages of 38.7%, 34.8% and 26.5%. When the nitration of 1 was carried out with fuming nitric acid in acetic acid at 20°, the same compounds 2, 3 and 4 were obtained, but with different relative percentages: 20.4%, 36.5% and 43.1% respectively. The results of the mononitration of 1 are compared with those obtained in other electrophilic substitutions and with the theoretical predictions. The further nitrations of 2, 3 and 4 with nitric acid in acetic anhydride at room temperature lead to the formation of five dinitro‐2,3′‐bithienyl isomers. Compound 2 gives a mixture of 2′,3‐dinitro‐ (5) and 3,5′‐dinitro‐2,3′‐bithienyl (6); compound 3 gives a mixture of 5, 2′,5‐dinitro‐ (7) and 2′,4‐dinitro‐2,3′‐bithienyl (8); compound 4 gives 7 and 5,5′‐dinitro‐2,3′‐bithienyl (9). The possible reasons of the formation of the various dinitro‐2,3′‐bithienyl isomers are discussed.
The synthesis of 4‐(o‐fluorophenyl)‐6,8‐dihydro‐3,8‐dimethyl‐pyrazolo[3,4‐e][1,4]diazepin‐7(IH)one, a metabolite of zolazepam
Authors: Dewald Horace A.
Published: April 2009

A metabolite of Zolazepam was prepared by a selective N‐demethylation of a dihydro derivative of Zolazepam using pyridine hydrochloride.
Studies on the syntheses of heterocyclic compounds. Part DLXXXI . Syntheses of 3‐carboxy‐1,2,3,4‐tetrahydroisoquinoline derivatives by phenolic cyclization
Authors: Kametani Tetsuji , Kigasawa Kazuo , Hüragi Mineharu , Ishimaru Haruhide , Haga Seiji
Published: April 2009

3‐Carboxy‐1,1‐dimethylisoquinoline and 3‐carboxy‐1‐spirocycloalkano‐and 1‐spiroheterocyclo‐alkanoisoquinoline derivatives were synthesized by phenolic cyclization reaction using m‐tyrosine and several carbonyl compounds.
Alkylation of complementary ribonucleotides by 1,2‐dodecyl‐epoxide in a micellar environment: a liquid chromatography—electrospray ionization—sequential mass spectrometry investigation
Authors: Losito I. , Angelico R. , Ceglie A. , Diomede S. , Palmisano F.
Published: April 2009

Alkylation of a pair of complementary ribonucleotides, adenosine monophosphate (AMP) and uridine monophosphate (UMP), was accomplished by 1,2‐dodecyl‐epoxide (DE) in a oil‐in‐water microemulsion based on the cationic surfactant Cetyl‐trimethyl‐ammonium‐bromide, providing a suitable catalytic interface for the reagents. Several, often isomeric, alkylation products, bearing one or two hydroxy–dodecyl moieties on their structures, were identified in the reaction mixtures by high‐performance liquid chromatography coupled to electrospray ionization ion trap mass spectrometry. In particular, mass spectrometry (MS)/MS spectra, implemented by extracted ion chromatograms obtained for peculiar MS/MS product ions, indicated alkylation to occur on uracil and on uracil/phosphate OH groups in singly and doubly alkylated UMP, respectively. Adenine NH2 group and phosphate or ribose OH groups were found to be involved as such (single alkylation) or in combination, in the case of alkylated derivatives of AMP. The reaction of both endocyclic N and CO groups (tautomerized to COH groups) of uracil and the predominance of nucleophilic attack to the more accessible carbon of the DE epoxydic bridge (the only exception being the reaction by the NH2 group of adenine) were inferred from MS3 spectra with the help of extracted ion chromatograms for specific fragment ions, after their structural characterization. Interestingly, alkylation on one of the uracil CO groups and, partially, on the adenine NH2 group, both potentially involved in AMP/UMP base pairing in the micellar environment, were found to be hindered when both ribonucleotides were present in the reaction mixtures. Copyright © 2009 John Wiley & Sons, Ltd.
Pulsating fluid flow modulates gene expression of proteins involved in Wnt signaling pathways in osteocytes
Authors: Santos Ana , Bakker Astrid D. , Zandieh‐Doulabi Behrouz , Semeins Cornelis M. , Klein‐Nulend Jenneke
Published: April 2009

Strain‐derived flow of interstitial fluid activates signal transduction pathways in osteocytes that regulate bone mechanical adaptation. Wnts are involved in this process, but whether mechanical loading modulates Wnt signaling in osteocytes is unclear. We assessed whether mechanical stimulation by pulsating fluid flow (PFF) leads to functional Wnt production, and whether nitric oxide (NO) is important for activation of the canonical Wnt signaling pathway in MLO‐Y4 osteocytes. MC3T3‐E1 osteoblasts were studied as a positive control for the MLO‐Y4 osteocyte response to mechanical loading. MLO‐Y4 osteocytes and MC3T3‐E1 osteoblasts were submitted to 1‐h PFF (0.7 ± 0.3 Pa, 5 Hz), and postincubated (PI) without PFF for 0.5–3 h. Gene expression of proteins related to the Wnt canonical and noncanonical pathways were studied using real‐time polymerase chain reaction (PCR). In MLO‐Y4 osteocytes, PFF upregulated gene expression of Wnt3a, c‐jun, connexin 43, and CD44 at 1–3‐h PI. In MC3T3‐E1 osteoblasts, PFF downregulated gene expression of Wnt5a and c‐jun at 0.5–3‐h PI. In MLO‐Y4 osteocytes, gene expression of PFF‐induced Wnt target genes was suppressed by the Wnt antagonist sFRP4, suggesting that loading activates the Wnt canonical pathway through functional Wnt production. The NO inhibitor L‐NAME suppressed the effect of PFF on gene expression of Wnt target genes, suggesting that NO might play a role in PFF‐induced Wnt production. The response to PFF differed in MC3T3‐E1 osteoblasts. Because Wnt signaling is important for bone mass regulation, osteocytes might orchestrate loading‐induced bone remodeling through, among others, Wnts. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1280–1287, 2009
The role of small‐scale fold and fault development in seismogenic zones: example of the western Huércal‐Overa Basin (eastern Betic Cordillera, Spain)
Authors: Pedrera Antonio , Galindo‐Zaldívar Jesús , Ruiz‐Bustos Antonio , Rodríguez‐Fernández José , Ruiz‐Constán Ana
Published: April 2009

The NW–SE shortening between the African and the Eurasian plates is accommodated in the eastern Betic Cordillera along a broad area that includes large N‐vergent folds and kilometric NE–SW sinistral faults with related seismicity. We have selected the best exposed small‐scale tectonic structures located in the western Huércal‐Overa Basin (Betic Cordillera) to discuss the seismotectonic implications of such structures usually developed in seismogenic zones. Subvertical ESE–WNW pure dextral faults and E–W to ENE–ESW dextral‐reverse faults and folds deform the Quaternary sediments. The La Molata structure is the most impressive example, including dextral ESE–WNW Neogene faults, active southward‐dipping reverse faults and associated ENE–WSW folds. A molar M1 assigned to Mimomys savini allows for precise dating of the folded sediments (0.95–0.83 Ma). Strain rates calculated across this structure give ∼0.006 mm a−1 horizontal shortening from the Middle Pleistocene up until now. The widespread active deformations on small‐scale structures contribute to elastic energy dissipation around the large seismogenic zones of the eastern Betics, decreasing the seismic hazard of major fault zones. Copyright © 2009 John Wiley & Sons, Ltd.
Assessing the economic value of a public birdwatching interpretative service using a contingent valuation method
Authors: Lee Choong‐Ki , Lee Jin‐Hyung , Mjelde James W. , Scott David , Kim Tae‐Kyun
Published: April 2009

Although resource interpretative services are an essential conservation management tool that can add value to ecotourism experiences, there has been little empirical investigation on the ‘true’ economic value of such services. As such, this study's objective is to estimate the economic value of public interpretative services at a publicly supported Korean birdwatching festival, using a dichotomous choice contingent valuation method. Logit estimation results indicate that bid, age, income and birdwatching experience are important factors in explaining willingness‐to‐pay for interpretative services. The mean value of the publicly supported interpretative services is estimated to be 4,961 South Korean Won (approximately US$5) per person. Copyright © 2009 John Wiley & Sons, Ltd.
Structures, energetics, and dynamics of gas phase ions studied by FTICR and HPMS
Authors: Wu Ronghu , McMahon Terry B.
Published: April 2009

Both Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS) and high‐pressure mass spectrometry (HPMS) are very powerful tools in the field of gas phase ion chemistry. Many experimental method developments based on FTICR‐MS and HPMS are summarized, including the coupling of a high‐pressure external ion source to a FTICR mass spectrometer, blackbody infrared radiative dissociation (BIRD), coupling laser desorption ionization with HPMS, infrared multiple photon dissociation (IRMPD), radiative association and bimolecular routes to gas phase cluster ion formation. An abundance of thermochemical data, such as proton affinities, gas phase acidities, methyl cation affinities and metal cation affinities, have been obtained. Some of these data are the basis of the standard data listed in the NIST thermochemical databases. Ion–molecule interactions, energetics, reactivities, and structures of molecules have been extensively investigated using the methods developed based on HPMS and FTICR mass spectrometric techniques. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:546–585, 2009
A clinic‐based screening of mutations in exons 31, 34, 35, 41, and 48 of LRRK2 in Iranian Parkinson's disease patients
Authors: Shojaee Seyedmehdi , Sina Farzad , Farboodi Niloofar , Fazlali Zeinab , Ghazavi Farzaneh , Ghorashi Seyed Ali , Parsa Khosro , Sadeghi Homa , Shahidi Gholam‐Ali , Ronaghi Mostafa , Elahi Elahe
Published: April 2009

We present results of mutation screening of exons 31, 34, 35, 41, and 48 of LRRK2 in 205 Iranian Parkinson's disease patients. Sixteen percent of the cases were familial. Although age was not a factor in patient recruitment, the Iranian cohort was relatively young (average age at onset of disease: 48.9 years). A notably high male to female ratio (2.96:1) and earlier age at onset (by 2.9 years) in men were observed. A known disease‐associated variation, c.C4321T causing R1441C, and IVS31 + 3A > G, a variation that may be associated, were observed. Therefore, disregarding IVS31 + 3A > G, disease status in at least 0.5% of our young cohort and in 3.5% of the familial cases was associated with a mutation in the five exons of LRRK2 screened. Interestingly, the variation causing p.G2019S was not observed. © 2009 Movement Disorder Society
Cognitive impairment in Parkinson's disease: Tools for diagnosis and assessment
Authors: Kulisevsky Jaime , Pagonabarraga Javier
Published: April 2009

Cognitive impairment (CI) and dementia are frequent and debilitating features associated with Parkinson's disease (PD). Formal neuropsychological examination is required to ascertain the degree and pattern of CI over the course of the disease. The use of different tools may explain heterogeneous data obtained from studies to date. Normative data for extensively used scales [Mattis Dementia Rating Scale (MDRS), Mini‐Mental State Examination (MMSE)] is incomplete in PD populations. According to sample characteristics, statistical analyses, and methodological quality, 33 studies using scales not specific to PD (MDRS, MMSE, Cambridge Cognitive Assessment, FAB) or PD‐specific scales (Mini‐Mental Parkinson, Scales for Outcomes of Parkinson's disease—Cognition, Parkinson's Disease—Cognitive Rating Scale, and Parkinson Neuropsychometric Dementia Assessment) were eligible for the critical analysis of their appropriateness to assess cognition in PD. Of the four scales specifically designed for PD, the SCOPA‐COG and the PD‐CRS have undergone extensive and rigorous validation processes. While the SCOPA‐COG mainly assesses “frontal‐subcortical” cognitive defects, the PD‐CRS also assesses “instrumental‐cortical” functions, allowing better characterization of the different patterns of CI that may be present in PD from the earliest stages. The MMP and PANDA scales were designed as brief screening tests for CI and have not yet been subjected to extensive clinimetric evaluations. Further research on PD‐specific tools seems mandatory to help establish accurate cut‐off scores for the diagnosis of mild PDD, detect cognitive profiles more prone to the future development of dementia, and allow comparisons between different descriptive or interventional studies. © 2009 Movement Disorder Society
Estimation of k‐space trajectories in spiral MRI
Authors: Tan Hao , Meyer Craig H.
Published: April 2009

For non‐Cartesian data acquisition in MRI, k‐space trajectory infidelity due to eddy current effects and other hardware imperfections will blur and distort the reconstructed images. Even with the shielded gradients and eddy current compensation techniques of current scanners, the deviation between the actual k‐space trajectory and the requested trajectory remains a major reason for image artifacts in non‐Cartesian MRI. It is often not practical to measure the k‐space trajectory for each imaging slice. It has been reported that better image quality is achieved in radial scanning by correcting anisotropic delays on different physical gradient axes. In this article the delay model is applied in spiral k‐space trajectory estimation to reduce image artifacts. Then a novel estimation method combining the anisotropic delay model and a simple convolution eddy current model further reduces the artifact level in spiral image reconstruction. The root mean square error and peak error in both phantom and in vivo images reconstructed using the estimated trajectories are reduced substantially compared to the results achieved by only tuning delays. After a one‐time calibration, it is thus possible to get an accurate estimate of the spiral trajectory and a high‐quality image reconstruction for an arbitrary scan plane. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
B interferometry for the calibration of RF transmitter arrays
Authors: Brunner David O. , Pruessmann Klaas P.
Published: April 2009

Multiple‐channel RF transmission holds great promise for MRI, especially for human applications at high fields. For calibration it requires mapping the effective RF magnetic fields, B, of the transmitter array. This is challenging to do accurately and fast due to the large dynamic range of B and tight SAR constraints. In the present work, this problem is revisited and solved by a novel mapping approach relying on an interference principle. The B fields of individual transmitter elements are measured indirectly by observing their interference with a SAR‐efficient baseline RF field. In this fashion even small RF fields can be observed in the B ‐sensitive large‐flip‐angle regime. Based on a set of such experiments B maps of the individual transmitter channels are obtained by solving a linear inverse problem. Confounding relaxation and off‐resonance effects are addressed by an extended signal model and nonlinear fitting. Using the novel approach, 2D mapping of an 8‐channel transmitter array was accomplished in less than a minute. For validation it is demonstrated that mapping results do not vary with T1 or parameters of the mapping sequence. In RF shimming experiments it is shown that the measured B maps accurately reflect the linearity of RF superposition. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Spatial normalization of the fiber orientation distribution based on high angular resolution diffusion imaging data
Authors: Hong Xin , Arlinghaus Lori R. , Anderson Adam W.
Published: April 2009

Comparison of high angular resolution diffusion imaging (HARDI) measurements between subjects or between timepoints for the same subject are facilitated by spatial normalization. In this work an algorithm was developed to transform the fiber orientation distribution (FOD) function, based on HARDI data, taking into account not only translation, but also rotation, scaling, and shearing effects of the spatial transformation. The algorithm was tested using simulated data and intrasubject and intersubject normalization of in vivo human data. All cases demonstrated reliable transformation of the FOD. This technique makes it possible to compare the intravoxel fiber distribution between subjects, between groups, or between timepoints for a single subject, which will be helpful in HARDI studies of white matter disease. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
HTGRAPPA: Real‐time B1‐weighted image domain TGRAPPA reconstruction
Authors: Saybasili Haris , Kellman Peter , Griswold Mark A. , Derbyshire J. Andrew , Guttman Michael A.
Published: April 2009

The temporal generalized autocalibrating partially parallel acquisitions (TGRAPPA) algorithm for parallel MRI was modified for real‐time low latency imaging in interventional procedures using image domain, B1‐weighted reconstruction. GRAPPA coefficients were calculated in k‐space, but applied in the image domain after appropriate transformation. Convolution‐like operations in k‐space were thus avoided, resulting in improved reconstruction speed. Image domain GRAPPA weights were combined into composite unmixing coefficients using adaptive B1‐map estimates and optimal noise weighting. Images were reconstructed by pixel‐by‐pixel multiplication in the image domain, rather than time‐consuming convolution operations in k‐space. Reconstruction and weight‐set calculation computations were parallelized and implemented on a general‐purpose multicore architecture. The weight calculation was performed asynchronously to the real‐time image reconstruction using a dedicated parallel processing thread. The weight‐set coefficients were computed in an adaptive manner with updates linked to changes in the imaging scan plane. In this implementation, reconstruction speed is not dependent on acceleration rate or GRAPPA kernel size. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Reproducibility of cerebral phenylalanine levels in patients with phenylketonuria determined by 1H‐MR spectroscopy
Authors: Kreis R. , Zwygart K. , Boesch C. , Nuoffer J‐M.
Published: April 2009

The reproducibility of metabolite content determined by MR spectroscopy (MRS) is usually at best a few percent for the prominent singlets. When studying low‐concentration metabolites, like phenylalanine (Phe), where tissue content can be <100 μmol/kg, better reproducibility is paramount—particularly in view of using MRS results for potential individual treatment advice. An optimized, targeted spectroscopy method was established at 1.5T and reproducibility was established in 21 patients with phenylketonuria (PKU) where three spectra were recorded in each of three independent sessions, two of which were in immediate succession to minimize physiologic variation. Intersession variation was found to be only 7 μmol/kg Phe for back‐to‐back repetition of sessions, in close agreement with the variation of 16 μmol/kg observed for single spectra within a session. Analysis of variance proved the individuality of the blood/brain Phe ratio—though this ratio seems to be influenced by physiologic factors that are not stable in time. The excellent reproducibility was achieved through optimization of various factors, including signal‐to‐noise ratio, repositioning, and prescan calibrations, but also by enforcing as much prior information as possible (e.g., lineshape and phase from reference scans, constant prior‐knowledge‐locked baseline). While the application of maximum general prior knowledge is a general method to reduce fluctuations, one should remember that it may introduce systematic errors. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Characterization and correction of system delays and eddy currents for MR imaging with ultrashort echo‐time and time‐varying gradients
Authors: Atkinson Ian C. , Lu Aiming , Thulborn Keith R.
Published: April 2009

Reconstruction of high‐quality MR images requires precise knowledge of the dynamic gradient magnetic fields used to perform spatial encoding. System delays and eddy currents can perturb the gradient fields in both time and space and significantly degrade the image quality for acquisitions with an ultrashort echo time or with rapidly varying readout gradient waveforms. A technique for simultaneously characterizing and correcting the system delay and linear‐ and zero‐order eddy currents of an MR system is proposed. A single set of calibration scans were used to compute a set of system constants that describe the effects of system delays and eddy currents to enable accurate reconstruction of data collected before uncorrected eddy currents have decayed. The ability of the proposed technique to reproducibly characterize small fixed delays (<50 μs) and short‐time constant (<1 ms) eddy currents is demonstrated. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Quantitative analysis of first‐pass contrast‐enhanced myocardial perfusion MRI using a patlak plot method and blood saturation correction
Authors: Ichihara Takashi , Ishida Masaki , Kitagawa Kakuya , Ichikawa Yasutaka , Natsume Takahiro , Yamaki Noriyasu , Maeda Hisato , Takeda Kan , Sakuma Hajime
Published: April 2009

The objectives of this study were to develop a method for quantifying myocardialK1and blood flow (MBF) with minimal operator interaction by using a Patlak plot method and to compare the MBF obtained by perfusion MRI with that from coronary sinus blood flow in the resting state. A method that can correct for the nonlinearity of the blood time–signal intensity curve on perfusion MR images was developed. Myocardial perfusion MR images were acquired with a saturation‐recovery balanced turbo field‐echo sequence in 10 patients. Coronary sinus blood flow was determined by phase‐contrast cine MRI, and the average MBF was calculated as coronary sinus blood flow divided by left ventricular (LV) mass obtained by cine MRI. Patlak plot analysis was performed using the saturation‐corrected blood time–signal intensity curve as an input function and the regional myocardial time–signal intensity curve as an output function. The mean MBF obtained by perfusion MRI was 86 ± 25 ml/min/100 g, showing good agreement with MBF calculated from coronary sinus blood flow (89 ± 30 ml/min/100 g,r= 0.74). The mean coefficient of variation for measuring regional MBF in 16 LV myocardial segments was 0.11. The current method using Patlak plot permits quantification of MBF with operator interaction limited to tracing the LV wall contours, registration, and time delays. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Vertical amplitude reduction of Rayleigh waves by a row of piles in a poroelastic half‐space
Authors: Cai Yuan‐Qiang , Ding Guang‐Ya , Xu Chang‐Jie , Wang Jun
Published: April 2009

A row of rigid piles is addressed as the countermeasures for isolating Rayleigh waves in a poroelastic half‐space. The complex characteristic equations for Rayleigh waves are derived via Biot's theory and their existence conditions are given. The piles are modeled as Euler–Bernoulli beams with longitudinal displacements and the diffracted field by each pile is constructed only with Rayleigh waves. Six infinite linear systems of algebraic equations are obtained in terms of the equilibrium of forces and continuity of displacements at the pile–soil interfaces. The systems are subsequently solved in the complex least‐squares sense. The influence of certain pile and soil characteristics such as the permeability of poroelastic soil, spacing between the piles and length of the piles on the isolating performance of a pile barrier is investigated. Computed results show that the permeability of poroelastic soil displays a significant effect on the vertical amplitude reduction of Rayleigh waves. Copyright © 2009 John Wiley & Sons, Ltd.
Buckling of thin‐walled cylindrical shells under axial compression
Authors: Ullah Himayat
Published: April 2009

Lightweight thin‐walled cylindrical shells subjected to external loads are prone to buckling rather than strength failure. The buckling of an axially compressed shell is studied using analytical, numerical and semi‐empirical models. An analytical model is developed using the classical shell small deflection theory. A semi‐empirical model is obtained by employing experimental correction factors based on the available test data in the theoretical model. Numerical model is built using ANSYS finite element analysis code for the same shell. The comparison reveals that the analytical and numerical linear model results match closely with each other but are higher than the empirical values. To investigate this discrepancy, non‐linear buckling analyses with large deflection effect and geometric imperfections are carried out. These analyses show that the effects of non‐linearity and geometric imperfections are responsible for the mismatch between theoretical and experimental results. The effect of shell thickness, radius and length variation on buckling load and buckling mode has also been studied. Copyright © 2009 John Wiley & Sons, Ltd.
First phase insulin release and glucose tolerance in children with Fanconi anemia after hematopoietic cell transplantation
Authors: Polgreen Lynda E. , Thomas William , MacMillan Margaret L. , Wagner John E. , Moran Antoinette , Petryk Anna
Published: April 2009

Background

Fanconi anemia (FA) is an autosomal and X‐linked recessive disease of chromosomal instability, which results in bone marrow failure. Children with FA have been shown to have an increased risk of diabetes mellitus (DM).

Procedure

A cross‐sectional study of glucose and insulin metabolism was conducted in 17 children with FA who had undergone hematopoietic cell transplantation (HCT) at the University of Minnesota. First phase insulin release (FPIR) was determined by intravenous glucose tolerance test (IVGTT). Oral glucose tolerance test (OGTT), lipid panel, blood pressure, and medical history were reviewed for additional metabolic abnormalities.

Results

Seventeen FA participants, median age 11.3 (range 5.5–17.6) years, were evaluated. IVGTT identified three separate groups: low FPIR, normal FPIR, and high FPIR. Those with low FPIR were more likely to have low BMI, but had normal glucose levels. Those with high FPIR, had high BMI, elevated lipids, and body fat. One patient with normal FPIR had impaired glucose tolerance and another with normal FPIR had impaired fasting glucose. No participant was diagnosed with DM by fasting glucose, 2 hr glucose during OGTT, or hemoglobin A1C.

Conclusions

The majority of children with FA had normal glucose tolerance and normal beta‐cell function after HCT. Two small subsets of patients had lower than expected and higher than expected FPIR. The clinical significance of these differences is not yet known given the normal glucose tolerance and fasting glucose levels in these two groups. Pediatr Blood Cancer 2009;53:191–196. © 2009 Wiley‐Liss, Inc.
Tribological properties of LDPE + Boehmite composites
Authors: Brostow Witold , Datashvili Tea , Kao David , Too Jonathan
Published: April 2009

Tribological properties of composites of low density polyethylene (LDPE) reinforced with 1, 5, 10, 20 wt% micrometric Boehmite (B) and/or preheated Boehmite (HB) powders were studied in combination with two silane coupling agents (SCAs): vinyltri(2‐methoxyethoxy)‐silane (VTMES)‐SCA 972 and 3‐(trimethoxysilyl)‐propylmethacrylate (3MPS)‐SCA 989. When coupling agents are used, the samples not subjected to preheating provide higher yields of grafting and more bonds introduced on surfaces of Boehmite particles than heated ones. We have determined sliding wear by multiple scratching along the same groove using a micro scratch tester. Instantaneous penetration depth is lowered by the filler addition to LDPE. However, there is less viscoelastic recovery and the residual (healing) depths increase with increasing Boehmite concentration. Friction was determined using a pin‐on‐disk tribometer and also a moving sled friction device. Addition of 20 wt% untreated B and/or HB particles to LDPE matrix reduces friction. However, a more significant improvement of tribological properties results from incorporation of grafted particles; this occurs because of an increase of the filler/matrix interfacial adhesion. Surface morphology seen in scanning electron microscopy confirms this explanation. Friction values for all samples decrease along with the filler concentration increase. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Synthesis and characterization of short Grewia optiva fiber‐based polymer composites
Authors: Singha Amar S. , Thakur Vijay Kumar
Published: April 2009

Natural fibers, such as Flax, Sisal, Hibiscus Sabdariffa, and Grewia optiva (GO) possess good reinforcing capability when properly compounded with polymers. These fibers are relatively inexpensive, easily available from renewable resources, and possess favorable values of specific strength and specific modulus. The mechanical performance of natural fiber‐reinforced polymers (FRPs) is often limited owing to a weak fiber‐ matrix interface. In contrast, urea–formaldehyde (UF) resins are well known to have a strong adhesion to most cellulose‐containing materials. This article deals with the synthesis of short G. optiva fiber‐reinforced UF polymer matrix‐based composites. G. optiva fiber‐reinforced UF composites processed by compression molding have been studied by evaluating their mechanical, physical, and chemical properties. This work reveals that mechanical properties such as: tensile strength, compressive strength, flexural strength, and wear resistance of the UF matrix increase up to 30% fiber loading and then decreases for higher loading when fibers are incorporated into the polymer matrix. Morphological and thermal studies of the matrix, fiber, and short FRP composites have also been carried out. The swelling, moisture absorbance, chemical resistance, and water uptake behavior of these composites have also been carried out at different intervals. The results obtained lay emphasis on the utilization of these fibers, as potential reinforcing materials in bio‐based polymer composites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Effect of both silane‐grafted and ion‐exchanged organophilic clay in structural, thermal, and mechanical properties of unsaturated polyester nanocomposites
Authors: Şen Sinan
Published: April 2009

Unsaturated polyester (UPE) resin including styrene monomer was mixed with organophilic montmorillonite (MMT) clay and its crosslinking polymerization reaction was done in the presence of free‐radical initiator. MMT clay was modified with cetyl trimethly ammonium bromide and trimethoxy vinyl silane. The nanocomposites were characterized by X‐ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), thermogravimetric and dynamic mechanical analyses (TGA and DMA). The exfoliated nanocomposite structure was obtained when the MMT clay was modified in the presence of both modifiers, whereas individual modifications all resulted in intercalated structures. The exfoliated UPE nanocomposite exhibited better thermal and dynamic mechanical properties when compared with pure UPE and other composites, even with 3 wt% clay loading. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Synthesis and mechanical properties of polybenzimidazole nanocomposites reinforced by vapor grown carbon nanofibers
Authors: Zhang Li , Ni Qing‐Qing , Shiga Akihiko , Fu Yaqin , Natsuki Toshiaki
Published: April 2009

Polybenzimidazole (PBI) nanocomposites containing 0.5–5 wt% vapor grown carbon nanofibers (VGNFs) were successfully synthesized by solvent evaporation method. Fracture morphology examination confirmed the uniform dispersion of VGNFs in the matrix. The mechanical properties of neat PBI and the nanocomposites were systematically measured by tensile test, dynamic mechanical analysis (DMA), hardness measurement, and friction test. Tensile tests revealed that Young's modulus increased by about 43.7% at 2 wt% VGNFs loading, and further modulus growth was observed at higher filler loadings. DMA studies showed that the nanocomposites have higher storage modulus than neat PBI in the temperature range of 30–350°C, holding storage modulus larger than 1.54 GPa below 300°C. Outstanding improvement of hardness was achieved for PBI upon incorporating 2 wt% of VGNFs. The results of friction test showed that coefficient of friction of PBI nanocomposites decreased with VGNFs content compared with neat PBI. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Liquid crystalline matrix polymers for aramid ballistic composites
Authors: de Ruijter C. , van der Zwaag S. , Stolze R. , Dingemans T.J.
Published: April 2009

Five semi‐flexible thermotropic liquid crystalline (LC) polyesters and poly(ester‐amide)s were synthesized and used as matrix resins for Twaron™ aramid‐based ballistic fabrics. The ballistic performance was investigated as a function of the neat resin content. For the most successful liquid crystalline polyester system, the effect of blending with styrene‐ethylene‐butylene‐styrene (SEBS) and polyvinyl butyrate (PVB) rubber was also explored. The best neat resin V50 values were obtained for 20 wt% LC polyester (LCPE)‐Twaron™ composites, that is, 418 m.s−1, whereas SEBS/LCPE and PVB/LCPE modifications resulted in maximum V50 values of 460 and 466 m.s−1, respectively. It was found that the ballistic impact resistance is strongly influenced by the elastic modulus of the resin component and to a lesser extent to the level of adhesion between the resin and fabric. The effect of resin content, resin strength, elongation‐at‐break, and resin toughness on the ballistic impact resistance was found to be small. The best ballistic protection could be obtained when the Young's modulus of the LC resin was in the range of 0.01–1 GPa. This result seems to be in agreement with existing inter‐yarn friction models. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Kaolin–epoxy‐based nanocomposites: A complementary study of the epoxy curing by FTIR and fluorescence
Authors: Castrillo P.D. , Olmos D. , Torkelson J.M. , González‐Benito J.
Published: April 2009

This work is focused on the study of the effect exerted by the presence of kaolin on the cure reaction of an epoxy‐based polymer, discussing the influence of different kaolin pretreatments. During the last few years, the interest on polymer matrix nanocomposite materials has sharply increased because generally they show improved properties when compared with those of the neat polymer (without filler). Among this sort of materials, polymer clay nanocomposites have been widely studied. However, there are not many works about kaolin‐based composites. Although several techniques have been used to monitor the cure process in epoxy‐based composites such as Fourier transform infrared spectroscopy (FTIR) or differential scanning calorimetry, only the use of the fluorescent response from a fluorophore seems to be adequate to monitor the reaction exactly at the interfaces at a molecular scale. In this work, FTIR and fluorimetry were used to monitor the cure reaction of the different composite systems at different curing temperatures. The analysis of FTIR experiments revealed that the presence of the reinforcement clay affects the extent of the cure reaction depending on the nature of its surface. On the other hand, the use of a fluorescent molecule chemically bonded to the reinforcement allows studying the curing exactly at the interface. Finally, with the collected data, a kinetic analysis was done and the results obtained were compared in terms of the technique used and the information source (interface or bulk). At the interface, the activation energy for the epoxy reaction is lower than that carried out in the bulk indicating that the reaction at the interface proceeds via a particular mechanism for which the reaction is favored. It seems that a higher amount of hydroxyl groups is capable of catalyzing the cure reaction. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Toughening of polyamide 11 via addition of crystallizable polyethylene derivatives
Authors: Zhou Chengjuan , Wang Ke , Fu Qiang
Published: April 2009

BACKGROUND: Conventional rubber‐like toughening modifiers are soft and amorphous, and when used to toughen polyamide 11 (PA11) they commonly induce a decrease in the tensile strength and modulus. In this study, crystallizable polyethylene (PE) derivatives, i.e. linear low‐density polyethylene (LLDPE) and maleic anhydride‐grafted polyethylene (PE‐g‐MA), were adopted to toughen PA11.

RESULTS: Compared to pure PA11, a highest improvement by a factor of eight in the impact toughness was achieved; also, the tensile strength and modulus could be maintained at a relatively high level. PE‐g‐MA acted as a compatibilizer for PA11 and LLDPE, bringing strong interfacial adherence, and especially a domain‐in‐domain morphology observed in PA11/PE‐g‐MA/LLDPE (70/10/20 by weight) blends. The observation that PA11 was toughened by the crystallizable PE derivatives is discussed in depth, based on the combined effect of surface crystallization of LLDPE on pre‐formed PA11 crystallites and interfacial compatiblization between PA11 and PE‐g‐MA.

CONCLUSION: The crystallizable PE derivatives LLDPE and PE‐g‐MA were shown to be effective toughening modifiers for the proportions PA11/PE‐g‐MA/LLDPE 70/10/20 (by weight), which is considered to be an optimum composition: special domain‐in‐domain morphology was observed indicating a good dispersion of PE in the PA11 matrix and strong interfacial adherence between PE phase and PA11 phase. The reason why strength and modulus were maintained at a high level in the as‐prepared blends was attributed to the existence of rigid crystalline domains in PE. Copyright © 2009 Society of Chemical Industry
Relationship vulnerabilities during breast cancer: patient and partner perspectives
Authors: Fergus Karen D. , Gray Ross E.
Published: April 2009

Objective: Close interpersonal relationships play a crucial role in a woman's adjustment to breast cancer. To date, the literature has focused primarily on characteristics or behaviors of the well spouse that influence a woman's adaptation to the illness. The present qualitative investigation extended this literature by adopting an interactional perspective based on the underlying assumption that relationship partners' coping and distress is mutually influential. The focus of the analysis was patient and partner perceptions of relationship strife or tension over the course of the illness based on the notion that such interactions may be as or more harmful to relationships than supportive exchanges are helpful.

Method: Nineteen women (at different stages of the illness) and eleven male spouses were interviewed about their experiences in relation to breast cancer. Nine of the men and nine of the women were relationship partners. Interview text was subjected to a thematic analysis and informed by grounded theory principles.

Results: Two higher‐order categories of Personal Characteristics (both patient and partner) and Relationship Dynamics that impeded couple adjustment defined the overall theme of Relationship Vulnerabilities.

Conclusions: Findings from this study are situated within a broader developmental framework wherein breast cancer is considered a catastrophic life event that challenges the assimilation and accommodation processes of both partners in the relationship. For couples that are able to overcome the relationship challenges associated with the illness, there is the potential for mutual growth, and a deepening and strengthening of the relationship. Implications for clinical practice are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Personality variables are associated with colorectal cancer patients' quality of life independent of psychological distress and disease severity
Authors: Paika Vassiliki , Almyroudi Augoustina , Tomenson Barbara , Creed Francis , Kampletsas Eleftherios O. , Siafaka Vassiliki , Gkika Styliani , Mavreas Venetsanos , Pavlidis Nicholas , Hyphantis Thomas
Published: April 2009

Objective: The aim of the present study was to test whether psychological distress and personality variables are independently associated with health‐related quality of life (HRQOL) in colorectal cancer patients, after adjusting for age, gender, education and disease severity.

Methods: In a cross‐sectional study of 162 colorectal cancer patients (response rate 65.6%), the following self‐report instruments were administered: the Symptom Distress Checklist‐90‐R, the Sense of Coherence scale, the Life Style Index and the Hostility and Direction of Hostility Questionnaire. The outcome measures were the four components of the WHO Quality of Life Instrument, Short Form. We used hierarchical regressions to determine whether psychological distress mediates the relationship of personality and disease parameters with HRQOL.

Results: The overall proportion of the variance in the four components of HRQOL explained by our regression models ranged from 28.1 to 44.4%. Psychological distress was an independent correlate of HRQOL, associated with physical (p<0005), mental (p<0.05) and social relationships HRQOL (p<0.02). Personality variables were associated with HRQOL independent of psychological distress and disease severity. Sense of coherence and denial defense were positively associated with all aspects of HRQOL independent of psychological distress and disease parameters (p‐values ranging fromp<0.05 top<0.0005). Hostility (p<0.01) and repression defense (p=0.024) were also independently but negatively associated with physical HRQOL.

Conclusions: In colorectal cancer patients, psychological distress is associated with HRQOL independent of disease parameters but personality variables are also associated with HRQOL independent of disease severity and psychological distress, and this could be relevant to psychological interventions. Copyright © 2009 John Wiley & Sons, Ltd.
Biophysical studies support a predicted superhelical structure with armadillo repeats for Ric‐8
Authors: Figueroa Maximiliano , Victoria Hinrichs María , Bunster Marta , Babbitt Patricia , Martinez‐Oyanedel José , Olate Juan
Published: April 2009

Ric‐8 is a highly conserved cytosolic protein (MW 63 KDa) initially identified in C. elegans as an essential factor in neurotransmitter release and asymmetric cell division. Two different isoforms have been described in mammals, Ric‐8A and Ric‐8B; each possess guanine nucleotide exchange activity (GEF) on heterotrimeric G‐proteins, but with different Gα subunits specificities. To gain insight on the mechanisms involved in Ric‐8 cellular functions it is essential to obtain some information about its structure. Therefore, the aim of this work was to create a structural model for Ric‐8. In this case, it was not possible to construct a model based on comparison with a template structure because Ric‐8 does not present sequence similarity with any other protein. Consequently, different bioinformatics approaches that include protein folding and structure prediction were used. The Ric‐8 structural model is composed of 10 armadillo folding motifs, organized in a right‐twisted α‐alpha super helix. In order to validate the structural model, a His‐tag fusion construct of Ric‐8 was expressed in E. coli, purified by affinity and anion exchange chromatography and subjected to circular dichroism analysis (CD) and thermostability studies. Ric‐8 is approximately 80% alpha helix, with a Tm of 43.1°C, consistent with an armadillo‐type structure such as α‐importin, a protein composed of 10 armadillo repeats. The proposed structural model for Ric‐8 is intriguing because armadillo proteins are known to interact with multiple partners and participate in diverse cellular functions. These results open the possibility of finding new protein partners for Ric‐8 with new cellular functions.