bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of lignans by liquid chromatography‐electrospray ionization ion‐trap mass spectrometry
Authors: Eklund Patrik C. , Backman M. Josefin , Kronberg Leif Å. , Smeds Annika I. , Sjöholm Rainer E. 
Published: August 2007

AbstractThe fragmentation pattern of 30 compounds belonging to different classes of the lignan family was studied by liquid chromatography‐electrospray ionization ion‐trap mass spectrometry. On the basis of the observed fragmentation patterns, identification of different types of lignans was achieved. For example, dibenzylbutyrolactone lignans showed a characteristic fragmentation pathway by the loss of 44 Da (CO2) from the lactone moiety, whereas dibenzylbutanediols showed a loss of 48 Da by a combined loss of formaldehyde and water from the 1,4‐butanediol moiety. Lignan glycosides readily lost the sugar residue to give the parent lignan as their primary product ion. In addition, several compound‐specific fragmentations were observed and used for identification of individual compounds.A versatile method for analyses of lignans was developed using LC separation on a C8 column followed by fragmentation and detection of ions produced in the ion trap. Copyright © 2007 John Wiley & Sons, Ltd.
Non‐Newtonian and thermal effects in constant flow valve compensated symmetric hole‐entry hybrid journal bearing
Authors: Garg H. C. , Kumar Vijay , Sharda H. B. 
Published: August 2007

AbstractEvery high speed machine, demanding high level of perfection, can operate successfully through a precise design of bearings. Such a design can be formulated after carefully studying both static and dynamic characteristics of the journal bearing. The present paper described the study of static and dynamic performance of a hole‐entry hybrid journal bearing system compensated with constant flow valve restrictor by considering the combined influence of thermal effects and non‐Newtonian behaviour of the lubricant. The variation of the viscosity due to the non‐Newtonian behaviour of the lubricant and temperature rise has been considered in the study. The numerical solution of the generalized Reynolds equation governing the flow of the lubricant, having variable viscosity along with the energy and heat conduction equations, was obtained using finite element method. The non‐Newtonian lubricant has been assumed to follow the cubic shear stress law. The study included the performance of a double row symmetric hole‐entry hybrid journal bearing configuration containing 12 holes per row. The results presented in this paper indicate that change in viscosity of lubricant affects the performance of the hole‐entry hybrid journal bearing system quite significantly. Copyright © 2007 John Wiley & Sons, Ltd.
Tailoring protective coatings for all‐oxide ceramic matrix composites in high temperature‐/high heat flux environments and corrosive media
Authors: Braue W. , Mechnich P. 
Published: August 2007

AbstractThe application range of porous all‐oxide ceramic matrix composites (CMCs) can be significantly extended through deposition of protective coating systems. Typical applications include protection against erosion, wear and foreign object damage as well as a reduced permeability. Environmental barrier coatings (EBC) are mandatory in order to guarantee sufficient lifetime of the CMC components under high temperature‐, high heat flux conditions and corrosive attack (combustor liners, thermal protection systems for atmospheric reentry). Limited thermal stability of today’s oxide fibers requires additional thermal barrier functionality for EBCs in order to keep the effective CMC bulk temperatures below 1200 °C. Depending on the specific application DLR’s coating concept for all‐oxide CMCs is based on either a single reaction‐bonded aluminium oxide (RBAO) coating or a hybrid coating system consisting of a RBAO bond coat followed by an EB‐PVD YSZ/FSZ top coat and is highlighted for three case studies. Deposition techniques (magnetron sputtering, MOCVD) alternative to EB‐PVD as well as the suitability of fibrous and cellular materials for thick EBC/TBC layers are explored.
Strain rate sensitivity of titanium matrix composites under tensile loading
Authors: Hausmann J. M. 
Published: August 2007

AbstractTitanium matrix composites continuously reinforced by silicon carbide fibres are considered as key technology for a new generation of aero engines. High specific strength and stiffness promise significant weight savings and performance improvements. Impact loading may be one critical aspect in the design of rotating compressor components with titanium matrix composites. On the other hand the strength increases at high strain rates. Considering this additional loading capability enables a design closer to the edge. Therefore, the strength to strain rate relation needs to be examined. This paper presents results of high strain rate tests at the fly wheel device. Loadings resulting in strain rates from quasistatic loading to 740 1/s were applied. The results are discussed and the mechanism of energy consumption was investigated by determination of the plastic deformed length by scanning electron microscopy.
Biaxiale Ermüdung reibrührgeschweißter Strukturelemente
Authors: Biallas G. , Sick C. , Schneider J. , Trautmann K.‐H. 
Published: August 2007

AbstractIm Rahmen des EU‐Projekts WelAir wurden Kreuzproben auf der biaxialen Prüfanlage des DLR zyklisch belastet. Die Proben wurden aus reibrührgeschweißten Überlappstößen hergestellt und enthielten versteifende Elemente. Um die reale Belastungssituation von innendruckbeaufschlagten Strukturen im Flugzeugrumpf nachzubilden, wurden proportionale, gleichphasige Belastungen aufgebracht, wobei das mit λ bezeichnete Verhältnis der Lasten in den beiden Beanspruchungsrichtungen variierte.Die natürliche Rissinitiierung und das nachfolgende Risswachstum wurden vom Steifigkeitssprung am Nahtanfang und ‐ende bestimmt, die Risse bildeten sich dort jeweils senkrecht zur Naht aus. Die kleinste Lebensdauer wurde bei einachsiger Beanspruchung in Schweißrichtung (λ = 0) beobachtet. Zusätzliche Lastkomponenten senkrecht zur Schweißnaht (λ > 0) wirkten lebensdauerverlängernd. Ähnlich wie bei Stringerproben verlängerte eine größere Last senkrecht zum Stringer auch die Lebensdauer von reibrührgeschweißten Clip‐Stringer‐Strukturelementen, aber zusätzlich änderte sich die Lage des versagensrelevanten Risses.
Click chemistry reactions in medicinal chemistry: Applications of the 1,3‐dipolar cycloaddition between azides and alkynes
Authors: Tron Gian Cesare , Pirali Tracey , Billington Richard A. , Canonico Pier Luigi , Sorba Giovanni , Genazzani Armando A. 
Published: August 2007

AbstractIn recent years, there has been an ever‐increasing need for rapid reactions that meet the three main criteria of an ideal synthesis: efficiency, versatility, and selectivity. Such reactions would allow medicinal chemistry to keep pace with the multitude of information derived from modern biological screening techniques. The present review describes one of these reactions, the 1,3‐dipolar cycloaddition (“click‐reaction”) between azides and alkynes catalyzed by copper (I) salts. The simplicity of this reaction and the ease of purification of the resulting products have opened new opportunities in generating vast arrays of compounds with biological potential. The present review will outline the accomplishments of this strategy achieved so far and outline some of medicinal chemistry applications in which click‐chemistry might be relevant in the future. © 2007 Wiley Periodicals, Inc. Med Res Rev, 28, No. 2, 278–308, 2008
Laplacian decomposition of vector fields on fractal surfaces
Authors: Abreu‐Blaya R. , Bory‐Reyes J. , Moreno‐García T. , Peña‐Peña D. 
Published: August 2007

AbstractIn the present paper we consider domains in ℝ3 with fractal boundaries. Our main purpose is to study the boundary values of Laplacian vector fields, paying special attention to the problem of decomposing a Hölder continuous vector field on the boundary of a domain as a sum of two Hölder continuous vector fields which are Laplacian in the domain and in the complement of its closure, respectively. Our proofs are based on the intimate relationships between the theory of Laplacian vector fields and quaternionic analysis. Copyright © 2007 John Wiley & Sons, Ltd.
NMR and IR characterization of the aluminium complexes of norfloxacin and ciprofloxacin fluoroquinolones
Authors: Chattah Ana K. , Garro Linck Yamila , Monti Gustavo A. , Levstein Patricia R. , Breda Susana A. , Manzo Rubén H. , Olivera María E. 
Published: August 2007

AbstractA set of new aluminium complexes of norfloxacin (NOR) and ciprofloxacin (CIP) that show an improvement in their pharmaceutical properties were studied using solution and solid‐state nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The complexes synthesized with two different methods were compared. One of these methods will allow formulation of the compounds at production scale. High‐resolution 13C spectra were obtained with the cross‐polarization and magic angle spinning (CP‐MAS) experiment. These spectra were assigned by comparing them with the solution data of the pure drug and by using a quaternary carbon edition technique. The carbon relaxation times in the rotating frame, T1ρC, were measured for all the complexes. A two‐exponential decay evidences that the complexes are nonhomogeneous. The short T1ρC values are in the range 320–1100 µs and the long values in the range 1.8–7 ms. 27Al MAS NMR spectra revealed an octahedral coordination between the aluminium ion and oxygens of the pure drug, supporting a 3:1 ligand:metal stoichiometry in both CIP and NOR complexes. The stretching and deformation modes of carboxylic acid and carboxylate and keto groups were analyzed by IR. This technique shows that the same modes are present in the aluminium complexes obtained by the two methods and that the coordination of the fluoroquinolone to aluminium occurs through the 4‐keto and 3‐carboxylic groups. Copyright © 2007 John Wiley & Sons, Ltd.
Comparison of airway diameter measurements from an anthropomorphic airway tree phantom using hyperpolarized 3He MRI and high‐resolution computed tomography
Authors: Tzeng Yang‐Sheng , Hoffman Eric , Cook‐Granroth Janice , Maurer Rie , Shah Niral , Mansour Joey , Tschirren Juerg , Albert Mitchell 
Published: August 2007

AbstractAn anthropomorphic airway tree phantom was imaged with both hyperpolarized (HP) 3He MRI using a dynamic projection scan and computed tomography (CT). Airway diameter measurements from the HP 3He MR images obtained using a newly developed model‐based algorithm were compared against their corresponding CT values quantified with a well‐established method. Of the 45 airway segments that could be evaluated with CT, only 14 airway segments (31%) could be evaluated using HP 3He MRI. No airway segments smaller than ∼4 mm in diameter and distal to the fourth generation were adequate for analysis in MRI. For the 14 airway segments measured, only two airway segments yielded a non‐equivalent comparison between the two imaging modalities, while eight more had inconclusive comparison results, leaving only four airway segments (29%) that satisfied the designed equivalence criteria. Some of the potential problems in airway diameter quantification described in the formulation of the model‐based algorithm were observed in this study. These results suggest that dynamic projection HP 3He MRI may have limited utility for measuring airway segment diameters, particularly those of the central airways. Magn Reson Med 58:636–642, 2007. © 2007 Wiley‐Liss, Inc.
Magnetically‐labeled sensitized splenocytes to identify glioma by MRI: A preliminary study
Authors: Arbab Ali S. , Rad Ali M. , Iskander A.S.M. , Jafari‐Khouzani Kourosh , Brown Stephen L. , Churchman Jamie L. , Ding Guangliang , Jiang Quan , Frank Joseph A. , Soltanian‐Zadeh Hamid , Peck Donald J. 
Published: August 2007

AbstractThis study investigated the feasibility of imaging the migration and incorporation of magnetically‐labeled sensitized splenocytes in an experimental 9L glioma brain tumor model. Splenocytes collected from tumor‐bearing (sensitized splenocytes) or control (nonsensitized splenocytes) host rats were analyzed to determine the population of different cells, labeled with ferumoxides‐protamine sulfate (FePro) and injected intravenously to recipient rats (N = 4, for each group) bearing intracranial 9L tumors. Day 3 postinjection of splenocytes multiecho T‐weighted and three‐dimensional (3D) gradient echo MRI were obtained using a 7 Tesla MR system. R (1/T) maps were created from the T‐weighted images. Signal intensities (SIs) and R values in the tumors and contralateral brain were determined by hand drawn regions of interest (ROIs). Brain sections were stained for the evidence of administered cells. Both 3D and T‐weighted MRI showed low signal intensity areas in and around the tumors in rats that received labeled sensitized splenocytes. Prussian blue (PB), CD45‐ and CD8‐positive cells were present in areas at the corresponding sites of low signal intensities seen on MRI. Rats that received labeled nonsensitized splenocytes did not show low signal intensity areas or PB positive cells in or around the implanted tumors. In conclusion, the immunogenic reaction can be exploited to delineate recurrent glioma using MRI following systemically delivered magnetically labeled sensitized splenocytes or T‐cells. Magn Reson Med 58:519–526, 2007. © 2007 Wiley‐Liss, Inc.
Contrast agent concentration measurements affecting quantification of bolus‐tracking perfusion MRI
Authors: Calamante Fernando , Vonken Evert‐jan P.A. , van Osch Matthias J.P. 
Published: August 2007

AbstractMeasurement of the concentration of the contrast agent using dynamic susceptibility contrast MRI relies on field inhomogeneities caused by the presence of the paramagnetic agent. The usual method for calculation of the concentration from dynamic T‐weighted images is based on two key assumptions: 1) a linear relation between the change in R and the contrast agent concentration, and 2) a negligible effect on the MR signal due to concurrent T1 changes. In this study the effect of inaccuracies in these two assumptions on perfusion measurements was investigated using simulations and in vivo data. The results of the simulations provide a quantitative characterization of the magnitude of these effects for various experimental conditions (e.g., when a 1‐sec TR is used with TE = 20 ms, the T1 effects can introduce up to 40% cerebral blood flow underestimation depending on the flip angle). These findings can be used as a guide to estimate the errors in specific practical implementaions, as well as to optimize the sequence parameters to minimize their effect. In summary, this study shows that the arterial input function measurement should be corrected for nonlinear R effects and that care should be taken in the study design to avoid introducing significant T1 effects in perfusion quantification. Magn Reson Med 58:544–553, 2007. © 2007 Wiley‐Liss, Inc.
Three‐dimensional cine imaging using variable‐density spiral trajectories and SSFP with application to coronary artery angiography
Authors: Kressler Bryan , Spincemaille Pascal , Nguyen Thanh D. , Cheng Liuquan , Xi Hai Zhao , Prince Martin R. , Wang Yi 
Published: August 2007

AbstractA single breath‐hold 3D cardiac phase resolved steady‐state free precession (SSFP) sequence was developed, allowing 3D visualization of the moving coronary arteries. A 3D stack of spirals was acquired continuously throughout the cardiac cycle, and a sliding window reconstruction was used to achieve high temporal resolution. A coil specific field of view reconstruction technique was combined with Parallel Imaging with Localized Sensitivities (PILS) to allow acquisition of a reduced field of view. A view ordering incorporating fat suppression was employed to allow use of sliding window reconstruction. The technique was evaluated on healthy volunteers (n = 8), yielding images with 102 ms temporal resolution and 1.35 mm in‐plane resolution, and reasonable visualization of the left and right coronary arteries was achieved. Magn Reson Med 58:535–543, 2007. © 2007 Wiley‐Liss, Inc.
Fast, accurate, and precise mapping of the RF field in vivo using the 180° signal null
Authors: Dowell Nicholas G. , Tofts Paul S. 
Published: August 2007

AbstractRF field B1 nonuniformity is the largest cause of error in the quantitative measurement of many clinically relevant parameters in MR images and spectra. Knowledge of the absolute flip angles at every region will improve the accuracy and precision of such parameters. This method uses the 180° signal null to construct a flip angle map of the entire brain in less than 4 min, independent of T1, T2, and proton density. Three spoiled gradient echo volume acquisitions of the whole brain were made with three different flip angles. The optimum choice of flip angles was determined to be 145°, 180°, and 215°. Linear regression analysis was used to determine the nominal (system calibrated) flip angle required for a signal null at every pixel and thence determine the absolute flip angle at that location. The experiment utilizes an existing MR sequence supplied by the scanner manufacturer. The technique is validated experimentally and a theoretical investigation into the optimum experimental parameters is presented. Magn Reson Med 58:622–630, 2007. © 2007 Wiley‐Liss, Inc.
Structure–function relations of the giant elastic protein titin in striated and smooth muscle cells
Authors: Granzier Henk , Labeit Siegfried 
Published: August 2007

AbstractThe striated muscle sarcomere contains, in addition to thin and thick filaments, a third myofilament comprised of titin. The extensible region of titin spans the I‐band region of the sarcomere and develops passive force in stretched sarcomeres. This force positions the A‐bands in the middle of the sarcomere, maintains sarcomere length homogeneity and, importantly, is responsible for myocardial passive tension that determines diastolic filling. Recent work suggests that smooth muscle expresses a truncated titin isoform with a short extensible region that is predicted to develop high passive force levels. Several mechanisms for tuning the titin‐based passive tension have been discovered that involve alternative splicing as well as posttranslational modification, mechanisms that are at play both during normal muscle function as well as during disease. Muscle Nerve, 2007
Phrenic nerve conduction studies: Technical aspects and normative data
Authors: Resman‐Gǎspěrsč Anita , Podnar Simon 
Published: August 2007

AbstractIn our clinical work we have occasionally encountered difficulties (e.g., no response, concomitant brachial plexus stimulation) in performing phrenic nerve conduction studies. The aim of this study was to overcome these difficulties and obtain our own set of normative data. In 29 healthy volunteers (15 men), aged 21–65 years, phrenic nerve conduction studies were performed using bipolar surface stimulation electrodes and a standard recording montage. Stimulation just above the clavicle, between the sternal and clavicular heads of the sternocleidomastoid muscles, elicited responses at the lowest stimulation strength, without concomitant brachial plexus stimulation. M‐wave amplitude and duration changed with respiration, whereas latency and area did not. The normative limit for M‐wave latency was 8.0 ms (upper), for amplitude it was 0.46/0.33 mV (lower: inspiration/expiration), and for area it was 4.4 mVms (lower). We suggest a slight modification of the generally used position for phrenic nerve stimulation, and the use of M‐wave latency and area (unaffected by the respiratory cycle) in future phrenic nerve conduction studies. Muscle Nerve, 2007
Effects of nandrolone on denervation atrophy depend upon time after nerve transection
Authors: Zhao Jingbo , Zhang Yuangfei , Zhao Weidong , Wu Yong , Pan Jiangping , Bauman William A. , Cardozo Christopher 
Published: August 2007

AbstractAnabolic steroids prevent disuse atrophy and reverse atrophy caused by glucocorticoids. To determine whether these beneficial effects extend to denervation atrophy, we tested whether nandrolone blocked denervation atrophy acutely or reversed subacute denervation atrophy. We also tested the association of such anabolic effects with expression of MAFbx, MuRF1 (both of which accelerate denervation atrophy), and IGF‐1 (which prevents such atrophy). When begun at the time of denervation, nandrolone did not alter atrophy or expression of MAFbx, MuRF1, or IGF‐1 measured 3, 7, or 14 days thereafter. When nandrolone administration was begun 28 days after denervation, atrophy was significantly reduced 7 and 28 days later (16% and 30%, respectively), and this was associated with significant reductions in expression of MAFbx and MuRF1, without alterations in the expression of IGF‐1. The findings indicate that the actions of nandrolone depend on time after nerve transection and that the timing of anabolic steroid administration is an important determinant of responses of atrophying muscle to these agents. Muscle Nerve, 2007
Expression of transforming growth factor β1 gene, basic fibroblast growth factor gene and hydroxyproline in diabetes‐induced bladder dysfunction in a rat model
Authors: Yongzhi Li , Benkang Shi , Jianping Zhang , Lingxia Ran , Wei Bian , Yaofeng Zhu , Keqin Zhang , Laudon Vincent 
Published: August 2007

AbstractAimsTo investigate the content of hydroxyproline (Hyp) and the expression of transforming growth factor beta1 (TGFβ1) and basic fibroblast growth factor (bFGF) in the bladder 8 weeks after diabetes induction.MethodsThirty wistar rats were divided into three groups: control (n = 10), streptozotocin‐induced diabetic group (n = 10), TAD group (n = 10; diabetic rats were fed with Tadenan100 mg kg−1 day−1). Eight weeks later, the bladders were dissected. RT‐PCR, immunohistochemistry, and ELISA were used to detect the expression of TGFβ1 and bFGF in the bladder. Also hydroxyproline (Hyp) was measured using a method based on alkaline hydrolysis.ResultsThe content of hydroxyproline in the diabetic group was greater than that of control group (P < 0.05); we found significantly increased expression of TGFβ1 mRNA and bFGF mRNA in the bladder from the diabetic group compared with the control group; immunohistochemical and ELISA studies showed a statistically significant increased expression of TGFβ1 protein and bFGF protein in the bladder from the diabetic group compared with the control group (P < 0.05). The content of hydroxyproline in TAD group was less than that of diabetic group (P < 0.05); mRNA expression of TGFβ1 and bFGF greatly decreased in TAD group compared with that of the diabetic group; immunohistochemical and ELISA studies showed decreased levels of TGFβ1 protein and bFGF protein in the bladder from TAD group compared with the diabetic group (P < 0.05).ConclusionsRats with streptozoticin‐induced diabetes mellitus showed significant increase in hydroxyproline, TGFβ1 and bFGF levels in their bladders, which may be an important mechanism inducing diabetic cystopathy. Tadenan could effectively reduce hydroxyproline, TGFβ1, and bFGF levels. Neurourol. Urodynam. 27:254–259, 2008. © 2007 Wiley‐Liss, Inc.