bluuebunny/crossref_metadata_2025 huggingface dataset:
A mathematical model to predict the inelastic response of a steel frame: Establishment of parameters from shaking table experiments
Authors: Matzen Vernon C. , McNtven Hugh D.
Published: March 2007

The purpose of this research is to use data from experiments to formulate a mathematical model that will predict the non‐linear response of a single‐storey steel frame to an earthquake input. The process used in this formulation is system identification.

In experiments performed on a shaking table, the frame was subjected to two earthquake motions at several intensities. In each case the frame underwent severe inelastic deformation. A computer program which incorporates the concepts of system identification makes use of the recorded data to establish four parameters in a non‐linear mathematical model. When different amounts of data are used in the program, parameter sets are established which give the best model response for that amount of test data. The resulting sets of parameters reflect the way in which the properties of the structure change during the excitation. However, when the full durations of the different excitations are used, the sets of parameters are almost identical. For each of these sets of parameters, the correlation of the computed accelerations with the measured is excellent, and the shape of the computed displacement response compares very well with the measured response, although the permanent offset of the displacements is not computed exactly.

Suggestions are given on how to overcome this deficiency in the mathematical model.
Quality of life in dementia: care recipient and caregiver perceptions of quality of life in dementia: the LASER‐AD study
Authors: Hoe Juanita , Katona Cornelius , Orrell Martin , Livingston Gill
Published: March 2007

Background

Quality of Life (QoL) is a key outcome in dementia.

Aim

To compare care recipients' (CR) and caregivers' (CG) views on CRs' QoL and identify determinants.

Methods

CRs and CGs completed the Quality of Life ‐ Alzheimer's Disease (QOL‐AD) scale.

Results

One hundred and ninety‐one CR/CG dyads were interviewed. There were differences between determinants of the CRs and CGs views about QoL. Family‐CGs rated CRs' QoL higher when CRs had fewer depressive symptoms, less irritability, less apathy, less daily living impairment and lived at home. Fewer depressive symptoms, living at home and taking acetylcholinesterase‐inhibitors (AChEI) predicted higher CR rated QoL.

Conclusion

Proxy ratings in dementia do not replicate CRs' views of QoL. This is the first study to employ a validated QoL measure for people with dementia taking AChEIs. Randomised controlled trials are needed before drawing conclusions about their effect on QoL. Interpretation of correlations between QoL and symptoms should be cautious as QoL is designed to reflect the impact of psychological and physical symptoms. Copyright © 2007 John Wiley & Sons, Ltd.
Solitary necrotic nodule of the liver: Contrast‐enhanced sonography
Authors: Wang Yang , Yu Xiaoling , Tang Jie , Li Hua , Liu Liping , Gao Yongyan
Published: March 2007

Purpose.

To report contrast‐enhanced sonography (CEUS) for solitary necrotic nodule (SNN) of the liver and to assess its clinical value.

Methods.

CEUS was performed in 17 patients with pathologically proven SNN. Contrast pulse sequencing and the contrast agent SonoVue were used to depict lesion vascularity at a low mechanical index. The enhancement patterns were evaluated in real time.

Results.

Lesions were depicted as perfusion defects throughout all phases on CEUS.

Conclusions:

CEUS can be a convenient imaging modality for the differential diagnosis of SNN and may obviate the need for further imaging studies. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
Multiparametric high‐resolution imaging of barley embryos by multiphoton microscopy and magnetic resonance micro‐imaging
Authors: Stark Martin , Manz Bertram , Ehlers Alexander , Küppers Markus , Riemann Iris , Volke Frank , Siebert Uta , Weschke Winfriede , König Karsten
Published: March 2007

Nonlinear optical microscopy and magnetic resonance imaging (MRI) address different properties of the sample and operate on different geometrical scales. MRI maps density and mobility of molecules tracking specific molecular signatures. Multiphoton imaging profits from the nonlinear absorption of light in the focus of a femtosecond laser source stimulating the autofluorescence of biomolecules. As this effect relies on a high light intensity, the accessible field of view is limited, but the resolution is very high (a few hundred nanometers). Here, we aim to link the different accessible scales and properties addressed in the different techniques to obtain a synoptic view. As model specimen we studied embryos of barley. Multiphoton stimulated autofluorescence images and images of second harmonic generation are achieved even down to low magnification (10×), low numerical aperture (N.A. 0.25) conditions. The overview images allowed morphological assignments and fluorescence lifetime imaging provides further information to identify accumulation of endogenous fluorophores. The second, complementary contribution from high‐resolution MR images provides a 3D model and shows the embedding of the embryo in the grain. Images of the proton density were acquired using a standard 3D spin‐echo imaging pulse sequence. Details directly comparable to the low magnification optical data are visible. Eventually, passing from the MR images of the whole grain via low magnification to high resolution autofluorescence data bridges the scale barrier, and might provide the possibility to trace transport and accumulation of, e.g., nutrients from large structure of the plant to the (sub‐) cellular level. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
MR flow quantification using race: Clinical application to the carotid arteries
Authors: Möller Harald E. , Klocke Hans‐Kristian , Bongartz Georg M. , Peters Peter E.
Published: March 2007

Real time MR flow quantification was performed with real time acquisition and evaluation of motion (RACE) in a rigid phantom under steady flow conditions and in the common carotid arteries of 43 subjects aged 24–78 years. Hemodynamic information included the intraluminal velocity distribution during the complete cardiac cycle, the distensibility of the arterial wall, and age‐dependent changes of the flow curves. Systolic peak velocities of 51 ± 33 cm/s and time‐averaged volume flow rates of 4.3 ± 2.0 ml/s were measured in healthy subjects. Flow rates below 3.0 ml/s and the observation of abnormal flow patterns indicated stenoses greater than 70% in the region of the bifurcation (sensitivity: 83.3%; specificity: 93.7%; accuracy: 71.4%). Improvements may be achieved from a combination with MR angiography, providing both functional and morphologic vascular information noninvasively within one observer‐independent examination. MR imaging, therefore, has a strong potential for the diagnosis of critical stenoses in symptomatic patients.
Physiologic motion phantom for MRI applications
Authors: Drangova Maria , Bowman Brett , Pelc Norbert J.
Published: March 2007

To address the need for a complex physiologic motion phantom for use in MR applications, such as the verification of techniques for measuring myocardial motion dynamics and motion insensitive pulse sequences, a computer‐controlled motion phantom has been designed. The phantom, which consists of a deformable silicone gel annulus mounted on a translation stage, can undergo a range of bulk motions and deformations. Available motions include bulk rotation and translation, rotational shear, axial shear, and combinations of some or all of these motions. In this paper, the capability of the phantom to produce accurate constant and time‐varying waveforms is demonstrated. In the current implementation, peak linear translation and rotation rates are 175 mm s−1 and 10 rad s−1, respectively. Cycle‐to‐cycle reproducibility is excellent, with variations of less than .003 radians over the period of hours while under‐going rotational shear. The phantom has been designed in a flexible fashion so that various test objects can be scanned while undergoing bulk translation and can be adapted to produce different deformations.
Small bowel neoplastic disease: Demonstration by MRI
Authors: Semelka Richard C. , John Gesine , Kelekis Nikolaos L. , Burdeny Derek A. , Ascher Susan M.
Published: March 2007

This study demonstrates the appearance of small bowel tumors on MR images. Sixteen patients with tumors involving small bowel were studied by MRI. All tumors were proven with histopathology. Eleven patients had primary tumors of the small bowel, which included the following: four carcinoid tumors, three adenocarcinomas, two lymphomas, one leiomyosarcoma, and one leiomyoma. Five patients had recurrent or metastatic disease to small bowel: two patients had colon cancer, one patient had pancreatic cancer, one patient had uterine leiomyosarcoma, and one patient had chloroma (leukemia). MR examination included breath‐hold T1‐weighted spoiled gradient echo (all patients), immediate postgadolinium‐spoiled gradient echo (10 patients), and 2 to 4 minutes postgadolinium T1‐weighted, fat‐suppressed images (all patients). Tumor size, local extent, signal intensity, and enhancement features of tumor and adjacent tissue were determined. Tumor ranged in diameter from 1 to 9 cm (mean, 4.0 cm). Tumors had similar signal intensity to normal small bowel on precontrast images. Fourteen malignant tumors showed heterogeneous enhancement greater than adjacent bowel on gadolinium‐enhanced images. Tumor local extent was best shown on precontrast‐spoiled gradient‐echo images and postgadolinium T1‐weighted fat‐suppressed images. Image quality was most consistent on breath‐hold images. The results of this study show that small bowel tumors are demonstrable on MR images. Precontrast breath‐hold T1‐weighted spoiled gradient‐echo images and gadolinium‐enhanced fat suppressed images demonstrate tumor extent most reliably.
Assessing tumor angiogenesis using macromolecular MR imaging contrast media
Authors: Brasch Robert , Pham Christine , Shames David , Roberts Timothy , Van Dijke Kees , Van Bruggen Nick , Mann Jeffry , Ostrowitzki Susanne , Melnyk Ostap
Published: March 2007

MRI enhanced with a macromolecular contrast medium (MMCM) has previously been shown to estimate tumor microvascular characteristics that correlate closely with histologic microvascular density, an established surrogate of tumor angiogenesis. A similar MMCM‐enhanced MRI technique has now been used to investigate the acute tumor microvascular effects of antibody‐mediated inhibition of vascular endothelial growth factor (VEGF), a well‐studied and potent angiogenesis stimulator. Athymic rats xenografted with a human breast carcinoma (MDA‐MB‐435) were imaged after administration of albumin‐gadolinium diethylenetri‐amine pentaacetic acid (Gd‐DTPA30) using a heavily TI‐weighted three dimensional‐spoiled gradient‐refocused acquisition in a steady‐state pulse sequence before and 24 hours after treatment with anti‐VEGF antibody (single dose of 1 mg). Changes in longitudinal relaxivity (ΔR1) were analyzed using a bidirectional two‐compartment kinetic model to estimate tumor fractional blood volume (fBV) and permeability surface area product (PS). Data showed a significant decrease (P < .05) of tumor PS with respect to macromolecular contrast medium at 24 hours after treatment with anti‐VEGF antibody. No significant change was observed in fBV. Suppression of tumor microvascular permeability induced by anti‐VEGF antibody can be detected and quantified by MMCM‐enhanced MRI. MRI grading of tumor angiogenesis and monitoring of anti‐angiogenesis interventions could find wide clinical application.
Water diffusion and exchange as they influence contrast enhancement
Authors: Donahue Kathleen M. , Weisskoff Robert M. , Burstein Deborah
Published: March 2007

The contrast‐enhanced magnetic resonance imaging (MRI) signal is rarely a direct measure of contrast concentration; rather it depends on the effect that the contrast agent has on the tissue water magnetization. To correctly interpret such studies, an understanding of the effects of water movement on the magnetic resonance (MR) signal is critical. In this review, we discuss how water diffusion within biological compartments and water exchange between these compartments affect MR signal enhancement and therefore our ability to extract physiologic information. The two primary ways by which contrast agents affect water magnetization are discussed: (1) direct relaxivity and (2) indirect susceptibility effects. For relaxivity agents, for which T1 effects usually dominate, the theory of relaxation enhancement is presented, along with a review of the relevant physiologic time constants for water movement affecting this relaxation enhancement. Experimental issues that impact accurate measurement of the relaxation enhancement are discussed. Finally, the impact of these effects on extracting physiologic information is presented. Susceptibility effects depend on the size and shape of the contrast agent, the size and shape of the compartment in which it resides, as well as the characteristics of the water movement through the resulting magnetic field inhomogeneity. Therefore, modeling of this effect is complex and is the subject of active study. However, since susceptibility effects can be much stronger than relaxivity effects in certain situations, they may be useful even without full quantitation.
MR assessment of iodinated contrast‐medium‐induced nephropathy in rats using ultrasmall particles of iron oxide
Authors: Laissy Jean Pierre , Benderbous Soraya , Idée Jean Marc , Chillon Sylvie , Beaufils Hélène , Schouman‐Claeys Elisabeth
Published: March 2007

The purpose of this study was to determine the diagnostic value of ultrasmall particles of iron oxide (USPIO)‐enhanced MR imaging at different concentrations to evaluate experimental nephropathy. This study was conducted in 23 uninephrectomized rats using a model of iodinated contrast media‐induced renal failure. Eleven rats received selective intra‐arterial renal administration of diatrizoate (370 mg I/m1) and were compared to two control groups, including five animals injected with isotonic saline and seven noninjected animals. MR imaging was performed 28 hours after the procedure, including T1‐ and T2‐weighted images before and after intravenous administration of successively 5 μmol Fe/kg and 60 μmol/kg of USPIO. Results were interpreted qualitatively and quantitatively with respect to pathologic data, and differences were studied statistically. The maximal signal intensity decrease was noted in normal kidneys in cortex (−65 ± 4%) and medulla (−84 ± 5%) on T2‐weighted images after injection of 60 μmol/kg of USPIO. At this dose, diseased kidneys displayed less signal intensity decrease than normal kidneys on T2‐weighted images (p = .05). Moreover, qualitative analysis showed that the highest sensitivity and specificity to diagnose kidney involvement were obtained with T2‐weighted MR images (75% and 91%, respectively) when 60 μmol/kg of USPIO were used (p < .01). USPIO should be useful for in vivo evaluation of the severity of experimentally induced iodinated contrast media renal impairment in animals.
Evaluation of portal MR angiography using superparamagnetic iron oxide
Authors: Knollmann F. D. , Böck J. C. , Teltenkötter S. , Wlodarczyk W. , Mühler A. , Vogl Th. J. , Felix R.
Published: March 2007

The purpose of our research was to determine the effects of superparamagnetic iron oxide on MR imaging of the portal venous system. Eight piglets were examined in deep anaesthesia and respiratory arrest using a time‐of‐flight magnetic resonance fast low angle shot, two‐dimensional angiography sequence at 1.5T. MR angiograms were acquired precontrast and after intravenous administration of a cumulative dose of 10, 20 and 40 μmol/kg SHU 555A, a superparamagnetic iron oxide contrast agent for MR imaging with a particle size of 60 nm. For each dose, two subsequent sets of scans were obtained and reconstructed by a maximum‐intensity‐projection algorithm. Hepatic parenchymal and portal venous signal intensities were measured, and portal vein contrast calculated for each set of scans. All examinations were visually rated as to portal vein contrast and homogeneity by two blinded observers. Receiver operating characteristics of both observers were analyzed. The contrast agent reduced hepatic parenchymal signal in a dose‐dependent way. After a cumulative dose of 10 μmol iron oxide, hepatic parenchymal signal intensity decreased to 63 ± 6% (average of measurements at 4 and 14 minutes, mean ± standard error of the mean), after 20 μmol to 24 ± 3%, and after 40 μmol to 12 ± 1% of control. Intra‐vascular signal in the left main portal vein branch increased to 117 ± 6%, 127 ± 10%, and 133 ± 9% of control, respectively. The contrast‐to‐noise ratio of the portal vein improved (521 ± 90%, 891 ± 178%, and 995 ± 201% of control in the left portal vein main branch). Intravascular signal intensities increased slightly. The combined effect improved contrast of the portal vein stem and its branches. Receiver operating characteristics analysis documented dose‐dependency of contrast medium effects on portal venous contrast and intravascular homogeneity. Visual rating also indicated a positive effect on portal venous contrast. The superparamagnetic iron oxide agent improved portal venous contrast with surrounding hepatic parenchyma in this normal animal model, and could potentially result in more accurate diagnosis of portal venous pathology.
MR‐Guided percutaneous ethanol ablation of liver tissue in a .2‐T open MR system: Preliminary study in porcine model
Authors: Lu David S. K. , Sinha Shantanu , Lucas John , Farahani Keyvan , Lufkin Robert , Lewin Klaus
Published: March 2007

The purpose of this study was to test the feasibility of MR‐guided percutaneous ethanol ablation of liver tissue on a .2‐T open MR scanner. Needles were placed by MR guidance first into an ex vivo sheep liver and then into livers of three anesthetized pigs, and injection of 10 ml of 96% alcohol was performed. T1 fast low‐angle shot (FLASH), T2 turbo spin echo (TSE), and T1 spin echo (SE) images were obtained after incremental volumes of injection. In one pig, simultaneous injection of saline into normal liver was also performed with subsequent pathological correlation. Ethanol‐infiltrated liver was hypointense to liver on all sequences, whereas saline caused no tissue signal changes on T1 SE and either isointense or hyperintense changes on T2 TSE images. Pathological examination confirmed ethanol‐induced acute liver changes as compared with the control. MR guidance of needle placement and monitoring of ethanol effects on liver tissue is feasible. This may have implications for potential MR‐guided hepatic tumor ablation.
Magnetic Resonance Urography by Breath‐Hold Contrast‐Enhanced Three‐Dimensional FISP
Authors: Li Wei , Chavez David , Edelman Robert R. , Prasad Pottumarthi V.
Published: March 2007

The purpose of this study was to present our initial experience with contrast‐enhanced MR urography with a breath‐hold three‐dimensional imaging technique. We performed MR urographic studies in two pigs (four studies) and five human subjects using gadopentetate dimeglumine. The FISP sequence we used was the same as the one used for contrast‐enhanced three‐dimensional breath‐hold angiography. MR three‐dimensional urograms were obtained 7–24 minutes after the contrast injection with a dose as low as .03 mmol/kg. The calyces, renal pelves, and ureters were very well visualized. Three‐dimensional MR urography can be acquired within a single breath‐hold after administration of gadolinium chelates. This technique could become part of a protocol that could potentially lead to a single comprehensive diagnostic workup for suspected ureteral obstruction and gross hematuria.
Combined analysis of spatial and velocity displacement artifacts in phase contrast measurements of complex flows
Authors: Steinman David A. , Ethier C. Ross , Rutt Brian K.
Published: March 2007

MR phase contrast (PC) velocity imaging is a promising tool for quantifying blood flow velocity in vivo. PC velocity imaging is, however, susceptible to artifacts that result from the displacement of spins during the finite duration pulse sequences. Such displacement artifacts can lead to errors in velocity measurements, especially in the presence of oblique and accelerating flows, which are common throughout the cardiovascular system. By tracking particles (representing spins) through a computed velocity field, and assuming that spatial and velocity encodings occur at discrete times during the pulse sequence, we simulate the separate and combined effects of oblique and acceleration artifacts on PC velocity images. We demonstrate, both by simulation and MR measurement, the errors associated with such artifacts in PC velocity measurements in a representative flow geometry. Using example particle trajectories, we provide a fluid dynamic basis for characteristic phase‐velocity image distortions that can arise when imaging complex, physiologically relevant flows.
Intracranial contour extraction with active contour models
Authors: Matsumoto Sumiaki , Asato Reinin , Okada Tomohisa , Konishi Junji
Published: March 2007

A novel image processing scheme for extracting the intracranial contours in axial magnetic resonance data sets is proposed. The scheme incorporates the method of active contour models, a recently introduced paradigm for contour extraction. Its performance is nearly ideal for T2‐weighted images. Although the performances for proton‐density‐weighted images and T1‐weighted images drop slightly, qualitatively satisfactory extraction still can be obtained for T1‐weighted images. Due to high degree of automation, the scheme should help speed up some image processing applications that require the presegmentation of the intracranial cavity.
A reproducible repositioning method for serial magnetic resonance imaging studies of the brain in treatment trials for multiple sclerosis
Authors: Gallagher H. L. , Macmanus D. G. , Webb S. L. , Miller D. H.
Published: March 2007

Serial MRI is an important measure of disease progression in evaluating the treatment of multiple sclerosis (MS). Accurate comparisons of scans for lesion activity and lesion volume require precise repositioning of patients. A simple, reproducible repositioning method is described. In a multicenter treatment trial of MS using β‐interferon‐1b, this method has been successful, with only 1.1% of scans being rejected because of poor repositioning.
Vessel enhancement filtering in three‐dimensional MR angiograms using long‐range signal correlation
Authors: Du Yiping P. , Parker Dennis L.
Published: March 2007

Small vessels in three‐dimensional MR angiograms have low visibility in maximum‐intensity projection images because of their low contrast. In a previous study, we had two nonlinear filters that appeared to give significant improvement in small vessel detail. In this paper, we report on a generalization of this filter that allows a more general modeling of the vessels and a more complete suppression of background. One implementation of the general filter gave a vessel mean contrast‐to‐noise ratio that is 2.52 and 3.51 times higher than the vessel mean contrast‐to‐noise ratio obtained using our previously reported maximum‐minimum (max‐min) filter and cross‐ section filter, respectively.
Peroneal tendons: Use of kinematic MR imaging of the ankle to determine subluxation
Authors: Shellock Frank G. , Feske William , Frey Carol , Terk Michael
Published: March 2007

The purpose of this study was to develop a technique for kinematic MRI of the ankle to evaluate subluxation of the peroneal tendons. A special device was used to perform incremental, passive positioning of the ankle from dorsiflexed to plantarflexed positions for the kinematic MRI examination. A fast spoiled gradient‐recalled acquisition in the steady state pulse sequence was used to obtain axial images to assess the peroneal tendons during different positions of the ankle. Seven asymptomatic volunteers and five patients with suspected peroneal tendon subluxation were studied. There was no transverse displacement of the peroneal tendons observed in the asymptomatic subjects nor in two of the patients. Two patients had peroneal tendon subluxation observed on the kinematic MRI studies, and one patient had the peroneal tendons maintained in a displaced position in all ankle positions. The preliminary results suggest that kinematic MRI of the ankle is a potentially useful technique to facilitate evaluation of patients with suspected subluxation of the peroneal tendons, particularly in instances in which subluxation is position‐dependent, and spontaneous reduction of the tendons may occur.
Contrast enhancement pattern and frequency of previously unoperated lumbar discs on MRI
Authors: Hwang Geum‐Ju , Suh Jin‐Suck , Na Jae‐Bum , Lee Hwan‐Mo. , Kim Nam‐Hyun
Published: March 2007

Enhancement frequency and patterns (linear intradiscal, nodular intradiscal, and peridiscal) of the 210 previously unoperated lumbar discs were evaluated using contrast‐enhanced lumbar MRI. They also were compared with morphologic abnormalities (normal, bulging, protruded, and extruded) and signal alteration (high signal on T2‐weighted images) of the disc. Image interpretation was decided by the consensus of two musculoskeletal radiologists. Enhancement was observed in 69 (32.6%) discs. The enhancement patterns were either intradiscal, linear of (79.7%) or nodular (10.2%), peridiscal (7.2%), or combined (2.9%). Thirty‐five (77.8%) of the 45 herniated discs, 35 (77.8%) were enhanced, whereas 34 (20.6%) of 165 normal‐appearing discs were enhanced. Enhancement was observed more frequently in discs with high signal intensity zones (P < 0.05). In the six patients with enhanced discs, surgery revealed granulation tissue in three extruded discs, two protruded discs, and one bulging disc. The authors believe that contrast enhancements are frequent in herniated discs and are not infrequent in normal‐appearing discs. The understanding of various enhancement patterns may help in the interpretation of lumbar spine MRI.
Relaxivity of Gd‐EOB‐DTPA in the normal and biliary obstructed guinea pig
Authors: Shuter B. , Wang S.‐C. , Roche J. , Briggs G. , Pope J. M.
Published: March 2007

After injection of Gd‐EOB‐DTPA, T1 and T2 were determined on a clinical MR scanner (1.5 T) in the liver and kidneys of sacrificed but intact guinea pigs with normal and obstructed biliary systems and in bile, urine, and blood collected postmortem. Tissue [Gd] was determined by radioassay of 153Gd and relaxivities (R1 and R2; units of s−1·mmol−1·kg) of Gd‐EOB‐DTPA calculated. Compared with R1 in 2% agarose gel (4.49 ± 0.03), in normal animals R1 was increased in liver (9.3 ± 0.5), similar in kidney cortex (4.1 ± 0.5), but reduced in kidney medulla (2.5 ± 0.4) and papilla (2.7 ± 0.4). Chronic biliary obstruction did not change R1 in liver (9.7 ± 4.3) but reduced R1 further in kidney tissues (1.0–0.4). In normal animals, R2 values of all tissues (9.5–18.4) were greater than R2 in gel (5.72 ± 0.12). Biliary obstruction possibly elevated R2 in liver (40.1 ± 63.5), severely depressed R2 in kidney cortex (−4.2 ± 6.2) and medulla (−2.3 ± 5.4), and reduced R2 in papilla (5.4 ± 4.6). Obstruction had little effect on R1 and R2 in bile and urine. Water content, macromolecular binding, microviscosity, compartmentalization, and susceptibility effects can readily account for the R1 and R2 observed in liver and kidney. Negative R2 could be a result of several factors, including reduced endogenous magnetic field gradients due to “susceptibility matching” as [Gd] increased, changes in tissue T2 with period of ligation, or a physiological effect of EOB‐DTPA. These results show that disease can alter both R1 and R2 from their values in normal tissues.
Tropospheric biennial oscillation of the Indian summer monsoon with and without the El Nino‐Southern Oscillation
Authors: Pillai Prasanth A. , Mohankumar K.
Published: March 2007

Tropospheric biennial oscillation (TBO) is the tendency for a relatively strong monsoon to be followed by a weaker one, and vice versa, for the Asian–Australian monsoon system. According to this definition, TBO years include most of the El nino‐Southern Oscillation (ENSO)‐onset years and some other years also. It is believed that the TBO years, with and without ENSO‐onset years, have differences only in the magnitude of the signal. In the present paper, the process of coupled TBO involving the Indian monsoon and the Indian Ocean are studied through composites of relatively strong minus weak monsoon years, with and without the ENSO‐onset years, using National Centers for Environmental Prediction/National Centers for Atmospheric Research (NCEP/NCAR) data sets for the 1950–2004 time period. Different seasonal evolutions of anomalies for convection, Sea Surface Temperature (SST) and wind in a biennial cycle have been identified with and without the ENSO‐onset years. In both these cases, a perfect biennial cycle for convection has been noted. In the non‐ENSO biennial cycle, a perfect biennial cycle is obtained in the areas close to the Indian subcontinent for SST and wind. But for the ENSO‐only years, the seasonal evolutions are different. The Indian Ocean dipole, which is considered an inherent factor for TBO, is absent in the non‐ENSO years. The development and propagation of anomalies are also different in these two cases. It seems that factors other than ENSO are contributing to the biennial cycle in the non‐ENSO years. Copyright © 2007 Royal Meteorological Society
Benzoyl‐Peroxide‐Initiated Inverse Emulsion Copolymerization of Aniline and o‐Toluidine: Effect of Dodecylbenzenesulfonic Acid on the Physicochemical Properties of the Copolymers
Authors: Shreepathi Subrahmanya , Holze Rudolf
Published: March 2007

Homo‐ and copolymers of aniline and o‐toluidine have been synthesized using an inverse emulsion pathway; the copolymerization was initiated by benzoyl peroxide. The resulting homo‐ and copolymers are soluble in common organic solvents such as chloroform. Fairly higher doping percentages and polymerization yields for POT suggests that DBSA (a bulky molecule) can efficiently dope the polymer backbone by overcoming the steric hindrances created by the methyl substituent. However, in contrast to the PATs reported so far, solubility of POT as well as copolymers is lower than that of PANI. The homo‐ and copolymers have been characterized with UV‐Vis and FT‐IR spectroscopy, CV, in situ conductivity measurements and SEM. When dissolved in a 2:1 mixture of toluene and 2‐propanol, POT, unlike PANI and the copolymers, does not undergo any conformational rearrangement. A copolymer containing equimolar feed fractions of the comonomers has been obtained in higher yield and its morphology is similar to that of polyaniline.

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Propagation Kinetics of Binary Acrylate–Methacrylate Free‐Radical Bulk Copolymerizations
Authors: Buback Michael , Müller Elena
Published: March 2007

Rate coefficients of propagation, kp,copo, for MA–MMA, MA–DMA, DA–MMA, and DA–DMA bulk copolymerizations have been determined via PLP–SEC. The kp,copo values are analyzed in terms of the terminal and penultimate unit effect models. Alkyl acrylate and alkyl methacrylate reactivity ratios, as obtained from copolymer composition, are not significantly dependent on the size of the alkyl ester moiety, whereas kp,copo clearly depends on the size of the alkyl group. For MA–DMA, an almost perfect simultaneous fit of copolymer composition and kp,copo is obtained via the terminal model. For DA–MMA, even the penultimate unit effect model affords no adequate simultaneous fit. The observed effects are assigned to hindrance of internal rotational motion in the transition state due to intermolecular and intramolecular mobility terms.

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On the asymptotic stability of steady solutions of the Navier–Stokes equations in unbounded domains
Authors: Crispo Francesca , Tartaglione Alfonsina
Published: March 2007

We consider the problem of the asymptotic behaviour in the L2‐norm of solutions of the Navier–Stokes equations. We consider perturbations to the rest state and to stationary motions. In both cases we study the initial‐boundary value problem in unbounded domains with non‐compact boundary. In particular, we deal with domains with varying and possibly divergent exits to infinity and aperture domains. Copyright © 2007 John Wiley & Sons, Ltd.
The analysis and interpretation of cognitive interviews for instrument development
Authors: Knafl Kathleen , Deatrick Janet , Gallo Agatha , Holcombe Gwynne , Bakitas Marie , Dixon Jane , Grey Margaret
Published: March 2007

Cognitive interviews assess respondents' understanding of questionnaire items and are increasingly used to improve instrument design. Although investigators have described the contributions of cognitive interviews for instrument development, few guidelines are available for analyzing data from cognitive interviews when they are used for that purpose. In this article we address the development and application of analytic strategies for summarizing, interpreting, and using data from cognitive interviews that were conducted during the process of creating a measure of parental management of childhood chronic conditions. We discuss the contribution of cognitive interviews to establishing content validity and address the importance of developing standardized guidelines for analyzing and interpreting cognitive interviews in order to maximize their usefulness for instrument development. © 2007 Wiley Periodicals, Inc. Res Nurs Health 30: 224–234, 2007
Study of polystyrene/titanium dioxide nanocomposites via melt compounding for optical applications
Authors: Chandra Alexander , Turng Lih‐Sheng , Gong Shaoqin , Hall David C. , Caulfield Daniel F. , Yang Hsinjin
Published: March 2007

This article presents the study of melt compounding of polystyrene (PS) with various types of titanium dioxide (TiO2) nanoparticles and surfactants, using a corotating twin screw extruder with multiple screw element configurations. It was found that a properly designed high shear screw configuration and the copolymer of silicone, ethylene oxide, and propylene oxide‐based surfactant produced the greatest degree of nanoparticle dispersion in PS/TiO2 nanocomposites, whereas a silane‐based surfactant and silicon dioxide (SiO2) or aluminum oxide (Al2O3) coated TiO2 nanoparticles yielded nanocomposites with the least photocatalytic degradation effects and the best retention of tensile and impact properties. POLYM. COMPOS., 28:241–250, 2007. © 2007 Society of Plastic Engineers
Studies of oligomers by gel permeation chromatography
Authors: Barson C. A. , Robb J. C.
Published: March 2007

The photoinitiated reactions of bromotrichloromethane and of carbon tetrabromide on styrene, and of bromotrichloromethane on methyl methacrylate have been studied. The products have been analysed by gel permeation chromatography and the transfer constants for the first few steps in the polymerisations have been determined; some Arrhenius parameters have also been found. The processes may provide a synthetic route to a number of oligomers which are difficult to form by other methods.
Action of light on dyes in polymer materials
Authors: Egerton G. S.
Published: March 2007

Some of the general features of the way in which the nature of the polymer substrate influences the fading of dyes by light are briefly surveyed. The effects of oxygen, water vapour and atmospheric contaminants are considered in particular. It is suggested that singlet oxygen and hydrogen peroxide vapour play an important role in the fading of many dyes.
Polythiocarbamate polymers II.—Optimum conditions for synthesis
Authors: Hastings G. W. , Johnston D.
Published: March 2007

Polythiocarbamate polymers have been prepared from a prepolymer containing terminal isocyanate groups, obtained from reaction of a low molecular weight thiol‐terminated polymer with a diisocyanate. The prepolymer was chain extended and crosslinked with diols. and triols. Optimum conditions for prepolymer formation were established. Void formation in prepolymer is avoided by use of antioxidants but is difficult to prevent in the crosslinked material. Isocyanate appeared to be consumed in a reaction other than directly with thiol, and a water‐forming oxidation may be involved. A crosslinking reaction involving the thiocarbamate hydrogen and isocyanate appears to be favoured, contrary to results with carbamates. The nature of an isocyanate and catalyst complex is discussed.
Operation of a 27‐m3 biopile for the treatment of petroleum‐contaminated soil
Authors: Iturbe Rosario , Flores Carlos , Torres Luis G.
Published: March 2007

Soil and groundwater contamination due to petroleum hydrocarbon spills is a frequent problem worldwide. In Mexico, even when programs oriented to the diminution of these undesirable events exist, in 2000, a total of 1,518 petroleum spills were reported. Exploration zones, refineries, and oil distribution and storage stations frequently are contaminated with total petroleum hydrocarbons (TPH); diesel fraction; gasoline fraction; benzene, toluene, ethyl benzene, and xylenes (BTEX); and polycyclic aromatic hydrocarbons (PAHs). Among the many methodologies available for the treatment of this kind of contaminated soil, bioremediation is the most favorable, because it is an efficient/low‐cost option that is environmentally friendly. This article discusses the capability of using a biopile to treat soils contaminated with about 40,000 mg/kg of TPH. Design and operation of a 27‐m3 biopile is described in this work, including microbiological and respirometric aspects. Parameters such as TPH, diesel fraction, BTEX, and PAHs considered by the U.S. Environmental Protection Agency were measured in biopile samples at 0, 2, 4, 6, 8, 10, and 22 weeks. A final average TPH concentration of 7,300 mg/kg was achieved in 22 weeks, a removal efficiency of 80 percent. © 2007 Wiley Periodicals, Inc.
Cover Picture: Optimal Atomistic Modifications of Material Surfaces: Design of Selective Nesting Sites for Biomolecules (Small 4/2007)
Authors: Wang Boyang , Král Petr
Published: March 2007

The cover picture illustrates the electrostatic potential of the Ala‐Tyr‐Met peptide that is Coulombically docked in a highly selective nest formed on a B‐ and N‐doped graphene layer. The optimally designed nesting site has an electrostatic potential distribution that is largely complementary to that of the peptide. This methodology can selectively bind solvated proteins on material surfaces modified by covalently attached charged ligands, and it has numerous potential applications in the formation of hybrid biofunctional systems at the nanoscale. For more information, please read the Communication “Optimal Atomistic Modifications of Material Surfaces: Design of Selective Nesting Sites for Biomolecules” by Boyang Wang and Petr Král beginning on page 580.
Activation of transcription factor IL‐6 (NF‐IL‐6) and nuclear factor‐κB (NF‐κB) by lipid ozonation products is crucial to interleukin‐8 gene expression in human airway epithelial cells
Authors: Kafoury Ramzi M. , Hernandez Jazmir M. , Lasky Joseph A. , Toscano William A. , Friedman Mitchell
Published: March 2007

Ozone (O3) is a major component of smog and an inhaled toxicant to the lung. O3 rapidly reacts with the airway epithelial cell membrane phospholipids to generate lipid ozonation products (LOP). 1‐Hydroxy‐1‐hydroperoxynonane (HHP‐C9) is an important LOP, produced from the ozonation of 1‐palmitoyl‐2‐oleoyl‐sn‐glycerol‐3‐phosphatidylcholine. This LOP, at a biologically relevant concentration (100 μM), increases the activity of phospholipase C, nuclear factors‐κB (NF‐κB), and interleukin‐6 (NF‐IL‐6) and the expression of the inflammatory gene, interleukin‐8 (IL‐8) in a cultured human bronchial epithelial cell line (BEAS‐2B). The signaling pathways of ozone and its biologically‐active products are as yet undefined. In the present study, we report that the HHP LOP, HHP‐C9 (100 μM × 4 h), activated the expression of IL‐8 (218 ± 26% increase over control, n = 4, P < 0.01) through an apparent interaction between the two transcription factors, NF‐κB and NF‐IL‐6. Transfection studies using luciferase reporter assays demonstrated that HHP‐C9 induced a significant increase in NF‐κB‐DNA binding activity (37 ± 7% increase over control, n = 6, P < 0.05). Inhibition of NF‐κB showed a statistically significant but modest decrease in IL‐8 release, which suggested a role for another transcription factor, NF‐IL‐6. Exposure of BEAS‐2B cells to HHP‐C9 induced a significant increase in the DNA binding activity of NF‐IL‐6 (45 ± 11% increase over control, n = 6, P < 0.05). The results of the present study indicate that NF‐IL‐6 interacts with NF‐κB in regulating the expression of IL‐8 in cultured human airway epithelial cells exposed to LOP, the biological products of ozone in the lung. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 159–168, 2007.
Dynamic crystallization of cocoa butter. I. characterization of simple lipids in rapid‐ and slow‐nucleating cocoa butters and their seed crystals
Authors: Chaiseri Siree , Dimick Paul S.
Published: March 2007

Six cocoa butters with different crystallization induction times and their seed crystals were analyzed for simple lipid composition. The rapid‐nucleating cocoa butter samples had higher concentrations of 1‐palmitoyl‐2‐oleoyl‐3‐stearoylglycerol and 1,3‐stearoyl‐2‐oleoylglycerol (SOS), and lower concentrations of the diunsaturated triacylglycerols, 1‐palmitoyl‐2,3‐oleoylglycerol and 1‐stearoyl‐2,3‐oleoylglycerol, as well as higher stearic acid concentrations within their diacylglycerol fractions when compared to the slow‐nucleating samples. At the early stages of crystallization, under agitation conditions at 26.5°C, cocoa butters solidified into two fractions, high‐melting and low‐melting. The low‐melting fractions were composed of polymorphs IV and V of cocoa butter, as indicated by the onset melting temperatures of the endotherms from differential scanning calorimetry. The high‐melting fractions, which had wide melting ranges, had peak maxima of 38.5–52.2°C. Seed crystals isolated at the early stage of crystallization were characterized by high concentrations of complex lipids, saturated triacylglycerols, saturated fatty acid‐rich diacylglycerols, and monoacylglycerols. The rapid‐nucleating seed crystals had higher concentrations of SOS when compared to their respective cocoa butters. The slow‐nucleating seed crystals did not exhibit this characteristic.
High‐performance size‐exclusion chromatographic studies on a high‐oleic acid sunflower oil during potato frying
Authors: Romero A. , Sánchez‐Muniz F. J. , Tulasne C. , Cuesta C.
Published: March 2007

The behavior of a high‐oleic acid sunflower oil used for 75 repeated deep‐fat fryings of potatoes, with a fast turnover of fresh oil during frying, was evaluated by measuring the total polar content isolated by column chromatography. The total polar content increased in the oil from 3.6 ± 0.1 (mean ± SD) mg/100 mg unused oil to 7.6 ± 0.4 mg/100 mg oil after being used in 20 repeated fryings, followed by a tendency to reach a near‐steady state throughout the successive fryings. Further, the polar fraction was examined by high‐performance size‐exclusion chromatography. Triacylglyceride dimers increased continuously from 0.18 ± 0.01 mg/100 mg unused oil to 2.42 ± 0.12 mg/100 mg oil at the 40th frying with no further significant changes. The amount of triacylglyceride polymers increased from 0.03 ± 0.00 mg/100 mg unused oil to 0.70 ± 0.01 mg/100 mg oil at the 60th frying, but did not increase further with continued frying. Oxidized triacylglycerides also significantly increased from 1.13 ± 0.06 mg/100 mg oil to 3.58 ± 0.09 mg/100 mg oil at the 50th frying to reach a near‐steady state in successive fryings. Diacylglycerides and free fatty acids levels, related to hydrolytic alteration, did not change from the starting oil after continued fryings. Data from this study indicated that repeated fryings of potatoes in high‐oleic sunflower oil with a frequent turnover of fresh oil throughout the frying slightly increased the level of polar material in the fryer oil during the first fryings, followed by minor changes and a tendency to reach a near‐steady state in successive fryings.
Utilization of acid oils in making valuable fatty products by microbial lipase technology
Authors: Ghosh S. , Bhattacharyya D. K.
Published: March 2007

Microbial lipase‐catalyzed hydrolysis, esterification, and alcoholysis reactions were carried out on acid oils of commerce such as coconut, soybean, mustard, sunflower, and rice bran for the purpose of making fatty acids and various monohydric alcohol esters of fatty acids of the acid oils. Neutral glycerides of the acid oils were hydrolyzed byCanadida cylindracea lipase almost completely within 48 h. Acid oils were converted into fatty acid esters of short‐ and long‐chain alcohols like C4, C8, C10, C12, C16, and C18 in high yields by simultaneous esterification and alcoholysis reactions withMucor miehei lipase as catalyst. Acid oils of commerce can be utilized as raw materials in making fatty acids and fatty acid esters using lipase‐catalyzed methodologies.
Antioxidant synergism between butylated hydroxyanisole and butylated hydroxytoluene
Authors: Omura Kanji
Published: March 2007

Decay of the 2,6‐di‐tert‐butyl‐4‐methylphenoxy radical [butylated hydroxytoluene (BHT)‐radical] in the presence of butylated hydroxyanisole (BHA) was investigated in 1,2‐dimethoxyethane with or without triethylamine. BHT‐radical was conveniently generated by dissociation of its unstable dimer in solution. The products were BHT, 3,3′‐di‐tert‐butyl‐5,5′‐dimethoxy‐2,2′‐dihydroxybiphenyl (BHA‐dimer), 2,6‐di‐tert‐butyl‐p‐quinone methide (QM), 1,2‐bis(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)ethane, and 3,3′,5,5′‐tetra‐tert‐butyl‐4,4′‐stilbenequinone. The reaction without added triethylamine gave larger quantities of the last two products and BHA (recovery), whereas the reaction with it provided larger quantities of the first two products. The marked difference in the product distribution can be accounted for by a series of reactions including reversible dehydrogenation of BHA with BHT‐radical, which generates 2‐tert‐butyl‐4‐methoxyphenoxy radical (BHA‐radical) and BHT, reversible dimerization of BHA‐radical, which affords an intermediarybis(cyclohexadienone), and spontaneous and base‐catalyzed prototropic rearrangement of the intermediate into BHA‐dimer. Products of coupling between BHT‐radical and BHA‐radical were not obtained. BHA was found to undergo facile acid‐catalyzed addition to QM, providing two isomericbis(hydroxyphenyl)methanes. The results help to elucidate the mechanism of antioxidant synergism between BHA and BHT and may suggest that the synergism can be affected by base or acid.