bluuebunny/crossref_metadata_2025_split huggingface dataset:
Can homogeneous preparation encoding (HoPE) help reduce scan time in abdominal MRI? A clinical evaluation
Authors: Paul Dominik , Frydrychowicz Alex , Walcher Jens , Fautz Hans‐Peter , Hennig Jürgen , Langer Matthias , Schäfer Oliver 
Published: July 2007

AbstractPurposeTo evaluate time efficiency, image quality, and diagnostic value of a clinical routine homogeneous preparation encoding (HoPE) imaging protocol in different malign and inflammatory abdominal conditions.Materials and MethodsA total of 14 healthy volunteers and 40 patients were examined after written informed consent and approval of the local ethics committee. A standard abdominal T1‐weighted (T1W) fat‐saturated gradient‐echo protocol was compared to the HoPE sequence protocol ensuring for comparable imaging parameters. Examinations were performed on a 1.5‐T Siemens Avanto equipped with a multichannel body‐array coil. Image analysis was performed with respect to contrast‐to‐noise ratio (CNR) and signal‐to‐noise ratio (SNR), level of fat suppression (FS), generation of artifacts, and overall image quality by two blinded radiologists.ResultsIn addition to comparable results in overall image quality and FS level, the HoPE sequence protocol provided a reduction in acquisition time of up to 40%. In addition, artifact generation was same or even reduced with respect to pulsation. Quantitative SNR analysis showed strong correlation between HoPE and the conventional method.ConclusionThe HoPE technique is a feasible and time‐saving alternative for clinical abdominal MRI. Future studies will have to be conducted on larger patient collectives to strengthen the impact of this promising technique for FS imaging and to prove its accuracy. J. Magn. Reson. Imaging 2007;26:442–447. © 2007 Wiley‐Liss, Inc.
Cardiac MRI in mice at 9.4 Tesla with a transmit‐receive surface coil and a cardiac‐tailored intensity‐correction algorithm
Authors: Sosnovik David E. , Dai Guangping , Nahrendorf Matthias , Rosen Bruce R. , Seethamraju Ravi 
Published: July 2007

AbstractPurposeTo evaluate the use of a transmit‐receive surface (TRS) coil and a cardiac‐tailored intensity‐correction algorithm for cardiac MRI in mice at 9.4 Tesla (9.4T).Materials and MethodsFast low‐angle shot (FLASH) cines, with and without delays alternating with nutations for tailored excitation (DANTE) tagging, were acquired in 13 mice. An intensity‐correction algorithm was developed to compensate for the sensitivity profile of the surface coil, and was tailored to account for the unique distribution of noise and flow artifacts in cardiac MR images.ResultsImage quality was extremely high and allowed fine structures such as trabeculations, valve cusps, and coronary arteries to be clearly visualized. The tag lines created with the surface coil were also sharp and clearly visible. Application of the intensity‐correction algorithm improved signal intensity, tissue contrast, and image quality even further. Importantly, the cardiac‐tailored properties of the correction algorithm prevented noise and flow artifacts from being significantly amplified.ConclusionThe feasibility and value of cardiac MRI in mice with a TRS coil has been demonstrated. In addition, a cardiac‐tailored intensity‐correction algorithm has been developed and shown to improve image quality even further. The use of these techniques could produce significant potential benefits over a broad range of scanners, coil configurations, and field strengths. J. Magn. Reson. Imaging 2007;26:279–287. © 2007 Wiley‐Liss, Inc.
Detection of cerebral metabolites by single‐voxel‐based PRESS and COSY techniques at 3T
Authors: Velan S. Sendhil , Lemieux Susan K. , Raylman Raymond R. , Boling Warren , Hobbs Gerald R. , Spencer Richard G. , Sridhar Rajagopalan , Kuppusamy Periannan , Thomas M. Albert 
Published: July 2007

AbstractPurposeTo compare point‐resolved spectroscopy (PRESS) and localized two‐dimensional (2D) correlated spectroscopy (L‐COSY) in the detection of cerebral metabolites in humans on a clinical scanner at 3T and to estimate their respective inter‐ and intrasubject variances.Materials and MethodsMeasurements were made on nine healthy subjects to assess intersubject variance, and daily on a single subject over a period of seven days to assess intrasubject variance. All L‐COSY measurements were performed with a voxel size of 27 mL (3 × 3 × 3 cm3) and a measurement time of ∼34 minutes in the occipitoparietal lobe of the brain. Relative metabolite concentrations were estimated with respect to N‐methyl creatine.ResultsWhile the sensitivity of PRESS is twice that of L‐COSY, the greater spectral resolution offered by L‐COSY resulted in greater consistency in estimates of the concentrations of several cerebral metabolites, as indicated by a superior intraclass correlation and a significantly lower standard deviation (SD) in a matched pair intrasubject analysis.ConclusionOur pilot results demonstrate that L‐COSY is an effective approach for resolving cerebral metabolites, and demonstrates a lower coefficient of variance (CV) than the conventional 1D localized spectroscopic approach using LC Model for quantification. J. Magn. Reson. Imaging 2007;26:405–409. © 2007 Wiley‐Liss, Inc.
Regional pulmonary perfusion using model‐free analysis of contrast‐enhanced MRI in meconium‐aspirated piglets
Authors: Ryhammer Pia , Pedersen Michael , Ringgaard Steffen , Ravn Hanne 
Published: July 2007

AbstractPurposeTo investigate if dynamic contrast‐enhanced MRI in lungs could add new information to pulmonary hypertension in a newborn piglet model.Materials and MethodsSix newborn piglets were subjected to instillation of meconium following treatment with sildenafil. Before and after both of these events, dynamic contrast‐enhanced MRI was performed to determine pulmonary blood flow (PBF) using a model‐free deconvolution of the dynamic signal‐time curve, together with invasive measurements of mean airway pressure (PAW), cardiac output (CO), and oxygenation index (OI).ResultsMeconium instillation caused a significant increase in PAW (P < 0.05) accompanied by a marked increase in OI, the average PBF in the four lung regions (apical‐anterior, apical‐posterior, distal‐anterior, and distal‐posterior) decreased significantly by 33% (P < 0.001), but it did not significantly affect CO. On the other hand, infusion of sildenafil caused a significant increase in CO (P < 0.01), and administration resulted mainly in an increased PBF in the distal parts of the lungs.ConclusionBy using dynamic contrast‐enhanced MRI, we demonstrated a marked decrease in PBF following instillation of meconium, which was not followed by an equivalent decrease in CO, suggesting that measurements of CO inadequately reflect the intrapulmonary changes in the blood circulation. J. Magn. Reson. Imaging 2007;26:296–303. © 2007 Wiley‐Liss, Inc.
Implementation and validation of localized constant‐time correlated spectroscopy (LCT‐COSY) on a clinical 3T MRI scanner for investigation of muscle metabolism
Authors: Velan S. Sendhil , Ramamurthy Senthil , Ainala Srilatha , Durst Christopher , Lemieux Susan K. , Raylman Raymond R. , Spencer Richard G. , Thomas M. Albert 
Published: July 2007

AbstractPurposeTo implement and evaluate a novel single‐volume two‐dimensional localized constant‐time‐based correlated spectroscopy (2D LCT‐COSY) sequence on a clinical 3T MR scanner. This sequence exhibits homonuclear decoupling along the F1 dimension, leading to improved spectral resolution compared to that of non‐constant‐time localized correlated spectroscopy (L–COSY).Materials and MethodsA GE 3T MR scanner equipped with a quadrature transmit and receive extremity coil was used in this study. The 2D LCT‐COSY sequence was programmed using General Electric's EPIC compiler. Simulations for a two‐spin 1/2 system were performed using GAMMA libraries to evaluate the theoretical performance of the sequences, and were also compared with corresponding phantom experiments using trans‐cinnamic acid. Finally, spectra were acquired from the soleus muscle of healthy volunteers in order to evaluate performance in vivo.ResultsSimulations and experimental results confirmed the improved spectral resolution of LCT‐COSY over L–COSY, as well as its homonuclear decoupling performance. The behavior of resonance amplitudes as a function of evolution time in the experiment also was appropriately reflected by the simulation. Corresponding results were obtained for the in vivo muscle spectra, in which separation of overlapping olefinic and allylic methylene protons from the intra‐ and extramyocellular lipids (IMCL and EMCL, respectively) was achieved.ConclusionSimulations and experimental results in vitro and in vivo demonstrate the strengths of LCT‐COSY. This technique can be implemented on systems of any field strength, and has the potential to separate overlapping metabolites in tissue when employed on high‐field clinical MRI scanners equipped for proton spectroscopy. J. Magn. Reson. Imaging 2007;26:410–417. © 2007 Wiley‐Liss, Inc.
Investigation of axonal magnetic fields in the human corpus callosum using visual stimulation based on MR signal modulation
Authors: Chow Li Sze , Cook Greg G. , Whitby Elspeth , Paley Martyn N.J. 
Published: July 2007

AbstractPurposeTo investigate the possibility of detecting visually‐evoked axonal currents in the splenium of the human corpus callosum using a 3.0T MRI system.Materials and MethodsAxonal currents produce weak and transient magnetic fields, and the components of these that lie parallel to the B0 field of the MRI system can potentially modulate the MR signal, which can be detected as an integrated effect over time. A fast gradient‐echo echo‐planar imaging (GE‐EPI) sequence with short TR and intermediate TE was employed in an attempt to detect such axonal currents using light‐emitting diode (LED) visual stimulation paradigms.ResultsThe mean magnitude signal change, expressed relative to the fully relaxed equilibrium signal calculated from the measured value using the known T1 of white matter, was 0.014 ± 0.004% at TE = 30 msec. This corresponded to a mean axonal field of 0.11 ± 0.03 nT, according to the hypothesis that the axonal currents create a Lorentzian field distribution within an imaging voxel.ConclusionMeasured frequency spectra and statistical mapping using the general linear model (GLM) showed evidence of the stimulus localized within the splenium of the corpus callosum, which was not thought to be due to motion artifacts or physiological responses. J. Magn. Reson. Imaging 2007;26:265–273. © 2007 Wiley‐Liss, Inc.
Prospective evaluation of nonenhanced MR imaging in acute pancreatitis
Authors: Viremouneix Loic , Monneuse Olivier , Gautier Guillaume , Gruner Laurent , Giorgi Roch , Allaouchiche Bernard , Pilleul Frank 
Published: July 2007

AbstractPurposeTo compare the value of nonenhanced (NE) magnetic resonance imaging (MRI) (NE‐MRI) with contrast‐enhanced (CE) computed tomography (CT) (CE‐CT) scan in assessing acute pancreatitis (AP) and in evaluating the severity index (SI) with clinical outcome.Materials and MethodsPatients with AP were prospectively investigated by CE‐CT scan and NE‐MRI on admission. MRI was performed with fat‐saturated T1‐weighted imaging, T2‐weighted imaging, and MR cholangiopancreatography (MRCP). Balthazar's grading system was used to evaluate the NE‐MRI severity index (CTSI, MRISI) and it was compared to the clinical outcome.ResultsA total of 90 patients (median age = 55 years) were included in the study. AP was of biliary etiology in 37 patients (41%). On admission, AP was assessed as grade III by CTSI in four patients (4%), whereas 19 patients were classified grade III by MRISI. The coefficient correlation between CTSI and MRISI was good, with r = 0.6 (P < 0.001). Considering CE‐CT scan as the gold standard, sensitivity (Sn), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of NE‐MRI for detecting severe AP based on imaging criteria were 100%, 82.6%, 100%, and 21%, respectively. NE‐MRI discriminates normal pancreatic parenchyma from edema and necrosis with a correlation between morbidity (P < 0.008).ConclusionNE‐MRI seems to be a reliable method of staging AP severity in comparison to CE‐CT scan. J. Magn. Reson. Imaging 2007;26:331–338. © 2007 Wiley‐Liss, Inc.
Preparative isolation and purification of sinomenine from Sinomenium acutum by centrifugal partition chromatography
Authors: Cheong Jong Hye , Kim Chul Young , Kim Jinwoong 
Published: July 2007

AbstractPreparative centrifugal partition chromatography (CPC) was successfully carried out for the separation of sinomenine from the methanolic extract of Sinomenium acutum stems and rhizomes. The optimum two‐phase solvent system of CPC was composed of n‐hexane/ethyl acetate/methanol/water at a volume ratio of 1:6:2:8 (v/v/v/v) with 0.1% triethylamine (TEA). Preparative CPC yielded 44.3 mg of sinomenine from 400 mg of MeOH extract with a purity of 96.9%.
Chip‐based nano‐LC‐MS/MS identification of proteins in complex biological samples using a novel polymer microfluidic device
Authors: Srbek Jan , Eickhoff Jan , Effelsberg Uwe , Kraiczek Karsten , van de Goor Tom , Coufal Pavel 
Published: July 2007

AbstractAlthough the proteome of each organism is unambiguously coded in its genome, the proteome shows the real biology in action in each particular organism. New powerful tools are being developed for biochemists and biologists to analyze complex biological samples for studying the complete protein supplement of the genome,i. e., the proteome. There are several methods available for proteome analysis including 2‐DE and several forms of MS. In recent years, technologies such as microfluidics and array‐based systems have appeared in the field of analysis, identification, and quantification of proteins. These novel approaches might help in solving current technical challenges in proteomics. This paper presents a practical application of the first commercially available microfluidic nano‐ESI device coupled with nano‐LC (i. e., HPLC‐chip) for the analysis of samples of some biological protein mixtures.
A rapid RP‐HPTLC densitometry method for simultaneous determination of major flavonoids in important medicinal plants
Authors: Bhandari Pamita , Kumar Neeraj , Gupta Ajai P. , Singh Bikram , Kaul Vijay K. 
Published: July 2007

AbstractA simple, sensitive, selective, precise, and robust high‐performance TLC (HPTLC) method was developed and validated for determination of flavonoids in herbal extracts Bauhinia variegata, Bacopa monnieri, Centella asiatica, Ginkgo biloba, Lonicera japonica, Rosa bourboniana, Rosa brunonii, and Rosa damascena. The HPTLC of flavonoids was performed on RP‐18 F254 TLC plates with dual run, water (5% formic acid)/methanol (70:30) and water (5% formic acid)/methanol (50:50) as mobile phases. Densitometric determination of flavonoids was performed at λ = 280 nm in reflectance/absorbance mode. The linear regression analysis data for the calibration plots showed a good linear relationship with r2 = 0.998 ± 0.0003 in the concentration range of 150–800 ng/spot for apigenin and rutin and 200–1000 ng/spot for quercetin, luteolin, and quercitrin with respect to peak area. The average recovery for apigenin, quercetin, rutin, luteolin, and quercitrin was 97–99.8% indicating the excellent reproducibility. Statistical analysis of the data showed that the method is reproducible and selective for determination of flavonoids.
High‐performance thin‐layer chromatographic method for quantitative determination of 4α‐methyl‐24β‐ethyl‐5α‐cholesta‐14,25‐dien‐3β‐ol, 24β‐ethylcholesta‐5,9(11),22E‐trien‐3β‐ol, and betulinic acid in Clerodendrum inerme
Authors: Pandey Richa , Verma Ram K. , Gupta Madan M. 
Published: July 2007

AbstractA sensitive, selective, precise, and robust high‐performance thin‐layer chromatography method was developed and validated for analysis of two new recently isolated sterols, 4α‐methyl‐24β‐ethyl‐5α‐cholesta‐14,25‐dien‐3β‐ol (1) and 24β‐ethylcholesta‐5,9(11),22E‐trien‐3β‐ol (2), and a triterpene, betulinic acid (3), in Clerodendrum inerme extract. The method employed HPTLC plates precoated with silica gel 60F254 as the stationary phase. To achieve good separation, an optimised mobile phase consisting of toluene‐acetone (94:06, v/v) was used (Rf 0.48, 0.34, and 0.22 for compounds 1, 2, and 3, respectively). Densitometric determination of the above compounds was carried out in reflection/absorption mode at 620 nm. Optimised chromatographic conditions provide well separated compact spots for the compounds 1, 2, and 3. The calibration curves were linear in the concentration range of 100–2500 ng/spot. The method was validated for precision, robustness, and recovery. The limits of detection and quantitation were 5, 6, and 10 μg/mL and 14, 18, and 29 μg/mL, respectively, for 1, 2, and 3. The method reported here is reproducible and convenient for quantitative analysis of these compounds in the aerial parts of C. inerme.
Preparation of single‐walled carbon nanotube fiber coating for solid‐phase microextraction of organochlorine pesticides in lake water and wastewater
Authors: Lü Jianxia , Liu Jingfu , Wei Yang , Jiang Kaili , Fan Shoushan , Liu Jiyan , Jiang Guibin 
Published: July 2007

AbstractThe feasibility of single‐walled carbon nanotubes (SWCNTs) as adsorbents for solid‐phase microextraction was investigated by using organochlorine pesticides (OCPs) as model compounds. SWCNTs were attached onto a stainless steel wire through organic binder. Potential factors affecting the extraction efficiency were optimized, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity. The developed method has a linear range of 2–800 ng/L for most analytes, with coefficients of correlation ranging from 0.9911 to 0.9996, LODs ranged from 0.19 to 3.77 ng/L (S/N = 3), and RSDs in the range of 3.5–13.9% (n = 5). Compared with the commercial PDMS fiber, the SWCNT fiber has better thermal stability (over 350°C) and longer life span (over 150 times). The developed method was applied to determine trace OCPs in lake water and wastewater samples with external standard calibration. Results showed that OCP contamination was very low in these samples, and HCHs were detected in almost all water samples while DDT concentrations were almost under detection limits in these samples. Recoveries obtained at 20 ng/L spiking level were in the range of 88.4–111% for OCPs in lake water. For wastewater samples, however, the recoveries were satisfactory for HCHs (63.6–97.1%) but relatively low for DDTs (44.7–116%) due to the high content of organic matter in wastewater.
Shotgun proteomic analysis of Arabidopsis thaliana leaves
Authors: Lee Joohyun , Garrett Wesley M. , Cooper Bret 
Published: July 2007

AbstractTwo shotgun tandem MS proteomics approaches, multidimensional protein identification technology (MudPIT) and 1‐D gel‐LC‐MS/MS, were used to identify Arabidopsis thaliana leaf proteins. These methods utilize different protein/peptide separation strategies. Detergents not compatible with MudPIT were used with 1‐D gel‐LC‐MS/MS to help enrich for the detection of membrane‐spanning and hydrophobic proteins. By combining the data from all MudPIT and 1‐D gel‐LC‐MS/MS experiments, 2342 nonredundant proteins spanning a broad range of molecular weights and pI values were detected. With the exception of unknown proteins, the distribution of gene ontology (GO) classifications for the detected proteins was similar to that encoded by the genome, which shows that these extraction and separation procedures are useful for a broad proteomic survey of plant cells. Unknown proteins will likely have to be targeted by using additional methods, some of which should be compatible with separation strategies taken here.
Synthesis of Novel Linear PEO‐b‐PS‐b‐PCL Triblock Copolymers by the Combination of ATRP, ROP, and a Click Reaction
Authors: He Xiaohua , Liang Liyuan , Xie Meiran , Zhang Yiqun , Lin Shaoliang , Yan Deyue 
Published: July 2007

AbstractA new strategy to synthesize a series of well‐defined amphiphilic PEO‐b‐PS‐b‐PCL block copolymers is presented. First, bromine‐terminated diblock copolymers PEO‐b‐PS‐Br are prepared by ATRP of styrene, and converted into azido‐terminated PEO‐b‐PS‐N3 diblock copolymers. Then propargyl‐terminated PCL is prepared by ROP of ε‐caprolactone. The PEO‐b‐PS‐b‐PCL triblock copolymers with $\overline M _{\rm n}$ from 1.62 × 104 to 1.96 × 104 and a narrow PDI from 1.09 to 1.19 are finally synthesized from these precursors. The structures of these triblock copolymers and their precursors have been characterized by NMR, IR, and GPC analysis.magnified image
A Water‐Soluble π‐Conjugated Polymer with up to 100 mg · mL−1 Solubility
Authors: Wang Huiping , Lu Ping , Wang Baoling , Qiu Song , Liu Meirong , Hanif Muddasir , Cheng Gang , Liu Shiyong , Ma Yuguang 
Published: July 2007

AbstractA cationic water‐soluble polyfluorene (P2) containing a high density of tetraalkylammonium side chains in polymer backbone was synthesized and characterized. The polymer shows excellent water solubility up to 100 mg · mL−1 as well as high photoluminescence (PL) quantum yield of 44% in water. The relatively high cationic density and appropriate side chain length of the polymer are the key factors to achieve such high water solubility. The reduction potential of P2 is decreased as compared with its neutral polymer, reflecting the enhanced electron injection abilities. The standard NPB/Alq3 device using such a polymer as the electron injection layer shows nearly three‐fold enhancement in the electroluminescence (EL) efficiency.magnified image
Broadband planer array with switchable polarizations
Authors: Bombale Uttam L. , Gupta Sanjeev 
Published: July 2007

AbstractIn this article microstrip planar array of eight elements is designed and simulated. It operates in the frequency range from 3.7 to 4.2 GHz. It gives gain of 17 dB. It can produce many types of polarizations such as Eθ, EΦ, right, and left circular. In all these polarizations the cross‐polar level is around 20 dB lower than the copolar level (except for Eθ, for Eθ it is around 10 dB). The novel microstrip antenna element used in this article is constructed using parasitic patch and shorting pins. It gives wide bandwidth and various polarizations due to parasitic patch and shorting pins, respectively. The array is simulated using Agilent's ADS 2003A momentum software. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2415–2419, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22731
Left‐handed characteristic analysis of a split‐ring resonator defected ground structure transmisson line
Authors: Wu Bian , Li Gang , Lai Xin , Liang Chang‐hong 
Published: July 2007

AbstractThe left‐handed properties of a split‐ring resonator defected ground structure transmission line (TL) is investigated in this article. Then the transmission zero location, dispersion relation, impedance characteristic as well as refraction index are derived in detail. The numerical and measurement results validate that, this type of TL unit has the left‐handed properties with transmission zero. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2599–2602, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22752
Does a representative volume element exist for fatigue life prediction? The case of aggregate composites
Authors: Lachihab Adel , Sab Karam 
Published: July 2007

AbstractIn a previous work, discrete modeling and a statistical approach were used to quantify the minimal representative volume element (RVE) size for aggregate composites, such as bituminous materials in the linear elastic regime (Comput. Mater. Sci. 2005; 33:467–490). In this paper, the discrete model is extended to strain‐softening behavior under cyclic loading. The existence of a RVE for fatigue life prediction is numerically proved and its minimal size is determined. It is found that it is much larger than the minimal RVE size in the elastic regime. Copyright © 2007 John Wiley & Sons, Ltd.