bluuebunny/crossref_metadata_2025 huggingface dataset:
An efficient algorithm based on the differential quadrature method for solving Navier–Stokes equations
Authors: Hamed Meraji S. , Ghaheri Abbas , Malekzadeh Parviz
Published: March 2012

In this paper, an approach to improve the application of the differential quadrature method for the solution of Navier–Stokes equations is presented. In using the conventional differential quadrature method for solving Navier–Stokes equations, difficulties such as boundary conditions' implementation, generation of an ill conditioned set of linear equations, large memory storage requirement to store data, and matrix coefficients, are usually encountered. Also, the solution of the generated set of equations takes a long running time and needs high computational efforts. An approach based on the point pressure–velocity iteration method, which is a variant of the Newton–Raphson relaxation technique, is presented to overcome these problems without losing accuracy. To verify its performance, four cases of two‐dimensional flows in single and staggered double lid‐driven cavity and flows past backward facing step and square cylinder, which have been often solved by researchers as benchmark solution, are simulated for different Reynolds numbers. The results are compared with existing solutions in the open literature. Very good agreement with low computational efforts of the approach is shown. It has been concluded that the method can be applied easily and is very time efficient. Copyright © 2012 John Wiley & Sons, Ltd.
BMP‐2 immobilized on nanocrystalline diamond–coated titanium screws; demonstration of osteoinductive properties in irradiated bone
Authors: Kloss Frank R. , Singh Sarvpreet , Hächl Oliver , Rentenberger Julia , Auberger Thomas , Kraft Anna , Klima Guenther , Mitterlechner Thomas , Steinmüller‐Nethl Doris , Lethaus Bernd , Rasse Michael , Lepperdinger Guenter , Gassner Robert
Published: March 2012

Background

Irradiation results in impaired bone healing. Thus, osteosynthesis procedures are afflicted with increased failure rates. To improve osseointegration bone morphogenetic protein‐2 (BMP‐2) immobilized on nanocrystalline diamond (NCD)–coated implant surfaces might be 1 solution.

Methods

By 4 weeks after irradiation of pig's mandible with a dose of 60 Gy a fracture was accomplished. Osteosynthesis was performed either with titanium osteosynthesis screws or NCD‐coated screws with immobilized BMP‐2. Nonirradiated animals served as control. After 1, 2, 4, and 8 weeks screws were evaluated histologically. Bone biopsies were gained to extract mesenchymal stem or precursor cells (MSCs).

Results

MSCs after irradiation demonstrated a behavior comparable to that of unirradiated cells. Consequently, immobilized BMP‐2 resulted in an initial increased bone contact ratio (p = .014) but demonstrated no sustainable effect compared with osseointegration in nonirradiated bone (p = .08).

Conclusion

Immobilized BMP‐2 demonstrates an osteoinductive effect in irradiated bone. MSCs as effector cells possess protective mechanisms to overcome the destructive effect of irradiation. © 2012 Wiley Periodicals, Inc. Head Neck, 2013
Phenotypic fidelity (or not?) of epithelial cells in the liver
Authors: Malato Y , Naqvi S , Schurmann N , Ng R , Wang B , Zape J
Published: March 2012

Recent evidence has contradicted the prevailing view that homeostasis and regeneration of the adult liver are mediated by self duplication of lineage-restricted hepatocytes and biliary epithelial cells. These new data suggest that liver progenitor cells do not function solely as a backup system in chronic liver injury; rather, they also produce hepatocytes after acute injury and are in fact the main source of new hepatocytes during normal hepatocyte turnover. In addition, other evidence suggests that hepatocytes are capable of lineage conversion, acting as precursors of biliary epithelial cells during biliary injury. To test these concepts, we generated a hepatocyte fate-tracing model based on timed and specific Cre recombinase expression and marker gene activation in all hepatocytes of adult Rosa26 reporter mice with an adenoassociated viral (AAV) vector. We found that newly formed hepatocytes derived from preexisting hepatocytes in the normal liver and that liver progenitor cells contributed minimally to acute hepatocyte regeneration. Further, we found no evidence that biliary injury induced conversion of hepatocytes into biliary epithelial cells. These results therefore restore the previously prevailing paradigms of liver homeostasis and regeneration. In addition, our new vector system will be a valuable tool for timed, efficient, and specific loop out of floxed sequences in hepatocytes.
TIMP-1 deficiency leads to lethal partial hepatic ischemia and reperfusion injury
Authors: Duarte Sergio , Hamada Takashi , Kuriyama Naohisa , Busuttil Ronald W. , Coito Ana J.
Published: March 2012

Hepatic ischemia and reperfusion injury (IRI) remains an important challenge in clinical orthotopic liver transplantation (OLT). Tissue inhibitor of metalloproteinase-1 (TIMP-1) is the major endogenous regulator of matrix metalloproteinase-9 (MMP-9). In this study we investigated the functional significance of TIMP-1 expression in a well-established mouse model of partial liver IRI. Compared to wildtype mice, TIMP-1−/− mice showed further impaired liver function and histological preservation after IRI. Notably, TIMP-1 deficiency led to lethal liver IRI, as over 60% of the TIMP-1−/− mice died postreperfusion, whereas all TIMP-1+/+ mice recovered and survived surgery. Lack of TIMP-1 expression was accompanied by markedly high levels of MMP-9 activity, which facilitates leukocyte transmigration across vascular barriers in hepatic IRI. Indeed, TIMP-1−/− livers were characterized by massive leukocyte infiltration and by up-regulation of proinflammatory mediators, including tumor necrosis factor alpha, interferon-gamma, and inducible nitric oxide synthase post-IRI. The inability of TIMP-1−/− mice to express TIMP-1 increased the levels of active caspase-3 and depressed the expression of Bcl-2 and the phosphorylation of Akt, emphasizing an important role for TIMP-1 expression on hepatocyte survival. Using independent parameters of regeneration, 5-bromodeoxyuridine incorporation, proliferating cell nuclear antigen expression, and histone H3 phosphorylation, we provide evidence that hepatocyte progression into S phase and mitosis was impaired in TIMP-1-deficient livers after IRI. Inhibition of the cell cycle progression by TIMP-1 deficiency was linked to depressed levels of cyclins-D1 and -E and to a disrupted c-Met signaling pathway, as evidenced by reduced phosphorylated c-Met expression and elevated c-Met ectodomain shedding postliver IRI.

Conclusion
: These results support a critical protective function for TIMP-1 expression on promoting survival and proliferation of liver cells and on regulating leukocyte recruitment and activation in liver IRI.
Hepatic activation of IKK/NFκB signaling induces liver fibrosis via macrophage-mediated chronic inflammation
Authors: Sunami Yoshiaki , Leithäuser Frank , Gul Sarah , Fiedler Katja , Güldiken Nurdan , Espenlaub Sigrid , Holzmann Karl-Heinz , Hipp Nora , Sindrilaru Anca , Luedde Tom , Baumann Bernd , Wissel Sebastian , Kreppel Florian , Schneider Marion , Scharffetter-Kochanek Karin , Kochanek Stefan , Strnad Pavel , Wirth Thomas
Published: March 2012

Liver damage in humans is induced by various insults including alcohol abuse, hepatitis B/C virus infection, autoimmune or metabolic disorders and, when persistent, leads to development of liver fibrosis. Because the nuclear factor-κB (NF-κB) system is activated in response to several of these stresses, we hypothesized that NF-κB activation in hepatocytes may contribute to fibrosis development. To activate the NF-κB signaling pathway in a time- and cell-type-specific manner in the liver, we crossed transgenic mice carrying the tetracycline-responsive transactivator under the control of the liver activator protein promotor with transgenic mice carrying a constitutively active form of the

Ikbkb

gene (IKK2 protein [CAIKK2]). Double-transgenic mice displayed doxycycline-regulated CAIKK2 expression in hepatocytes. Removal of doxycycline at birth led to activation of NF-κB signaling, moderate liver damage, recruitment of inflammatory cells, hepatocyte proliferation, and ultimately to spontaneous liver fibrosis development. Microarray analysis revealed prominent up-regulation of chemokines and chemokine receptors and this induction was rapidly reversed after switching off the CAIKK2 expression. Turning off the transgene expression for 3 weeks reversed stellate cell activation but did not diminish liver fibrosis. The elimination of macrophages by clodronate-liposomes attenuated NF-κB-induced liver fibrosis in a liver-injury-independent manner.

Conclusion
: Our results revealed that hepatic activation of IKK/NF-κB is sufficient to induce liver fibrosis by way of macrophage-mediated chronic inflammation. Therefore, agents controlling the hepatic NF-κB system represent attractive therapeutic tools to prevent fibrosis development in multiple chronic liver diseases.
Development and validation of a simple assay for the determination of cholinesterase activity in whole blood of laboratory animals
Authors: Naik Ramachandra S. , Liu Weiyi , Saxena Ashima
Published: March 2012

Current methods for measuring acetylcholinesterase (AChE) activities in whole blood use butyrylcholinesterase (BChE)‐selective inhibitors. However, the poor selectivity of these inhibitors results in the inhibition of AChE activity to some degree, leading to errors in reported values. The goal of this study was to develop and validate a simple assay for measuring AChE and BChE activities in whole blood from humans as well as experimental animals. Blood was fractionated into plasma and erythrocytes, and cholinesterase activities were titrated against ethopropazine and (−)‐huperzine A to determine the lowest concentration of ethopropazine that inhibited BChE completely without affecting AChE activity and the lowest concentration of (−)‐huperzine A that inhibited AChE completely without interfering with BChE activity. Results indicate that 20 µm ethopropazine can be successfully used for the accurate measurement of AChE activity in blood from humans as well as animals. Use of (−)‐huperzine A is not required for measuring BChE activity in normal or ‘exposed’ blood samples. The method was validated for blood from several animal species, including mice, rats, guinea pigs, dogs, minipigs, and African green, cynomolgus and rhesus monkeys. This method is superior to all reported methods, does not require the separation of erythrocyte and plasma fractions, and is suitable for measuring cholinesterase activities in fresh or frozen blood from animals that were exposed to nerve agents or those that were administered high doses of BChE. The method is simple, direct, reproducible, and reliable and can easily be adapted for high‐throughput screening of blood samples. Published 2012. This article is a US Government work and is in the public domain in the USA.
Efficient gene therapy based targeting system for the treatment of inoperable tumors
Authors: Wirth Thomas , Pikkarainen Jere Tuomas , Samaranayake Haritha Dhammika , Lehtolainen‐Dalkilic Pauliina , Lesch Hanna Pirita , Airenne Kari Juhani , Marjomäki Varpu , Ylä‐Herttuala Seppo Pasi Antero
Published: March 2012

Background

A considerable percentage of tumors are not amenable to surgery. We have designed a simple and powerful targeting system that offers an alternative option for the multi‐component pre‐targeting strategies used clinically. This targeting system can be used for any type of solid tumors independent of the tumor type, thereby omitting the need to engineer unique antibodies for each specific application or tumour type. In the present study, we show the expression of a chimeric fusion protein, which contains the low‐density lipoprotein receptor transmembrane domains and avidin, after local gene transfer and its ability to bind biotinylated compounds in vivo.

Methods

Semliki Forest virus and lentivirus vectors were used to express the fusion protein with a high affinity binding site for biotinylated compounds in the tumor. Three different animal models and imaging modalities were used for the demonstration of the functionality and efficacy of the targeting system in vitro and in vivo.

Results

We demonstrate targeting of biotinylated compounds after local gene transfer in vivo using two different gene transfer vectors. The findings were confirmed by immunohistochemistry, single‐photon emission computed tomography and magnetic resonance imaging. The therapeutic efficacy was tested in a syngeneic rat glioma model by injecting biotinylated‐90Yttrium into the tail vein of glioma bearing rats. The study demonstrates that animals, which were treated by using the gene therapy based targeting system, lived significantly longer than control animals.

Conclusions

Our gene therapy based targeting system is a promising tool for the treatment of inoperable tumors and other disease conditions, as well as diagnostic imaging. Copyright © 2012 John Wiley & Sons, Ltd.
Use of continuously MR tagged imaging for automated motion assessment in the abdomen: A feasibility study
Authors: Sprengers Andre M.J. , van der Paardt Marije P. , Zijta Frank M. , Caan Matthan W.A. , Lamerichs Rolf M. , Nederveen Aart J. , Stoker Jaap
Published: March 2012

Purpose:

To investigate the feasibility of measuring motion in the abdomen using a continuously tagged magnetic resonance imaging sequence.

Materials and Methods:

To assess (nonperiodic) motion in the abdomen, a nontriggered, continuously tagged transient field echo (TFE) sequence was implemented that acquires one complete 3D dataset per prepulse after a fixed delay. In postprocessing, a frequency analysis approach was developed for compact reviewing of the data and noise suppression. For proof of principle, a simulation was made and one free‐breathing dynamic in vivo scan was acquired in a healthy volunteer. During the dynamic scan the volunteer received glucagon intravenously.

Results:

The simulation showed that this frequency analysis enables the extraction of motion at low signal‐to‐noise ratio levels. Motion information was successfully gathered from the in vivo scan. The decline in bowel motion caused by the administration of glucagon could be quantitatively measured using the continuously tagged sequence.

Conclusion:

Continuously tagged imaging in the abdomen for the purpose of automated gathering of motion information is feasible and could aid the study of bowel motion. J. Magn. Reson. Imaging 2012;36:492–497. © 2012 Wiley Periodicals, Inc.
Nucleation and growth kinetics of silver nanoparticles prepared by glutamic acid in micellar media
Authors: Zaheer Zoya , Rafiuddin
Published: March 2012

The title reaction in the presence of cetyltrimethylammonium bromide (CTAB) has been followed spectrophotometrically at 325 nm. In the process of reduction, characteristic surface resonance plasmon absorption peaks appear for the silver nanoparticles (NP) and the intensities increase with reaction time. UV–visible spectra suggest that [CTAB] and glutamic acid influence the morphology of the silver NP and act as shape‐directing agents, whereas [Ag+] has no effect. The effects of the total [glutamic acid], [CTAB], and [Ag+] on the apparent rate constants of silver NP formation are determined. The sigmoidal curve of absorbance versus reaction time indicates an autocatalytic path involved in the growth process. The α‐amino and COOH groups undergo chemical transformation (oxidative deamination and decarboxylation). The particles are spherical in shape with average diameters ranging between 12 and 25 nm, and their size distribution is wide. A plausible mechanism has been proposed with the following rate law: (d[silver sol])/dt = k[Ag+][Glutamic acid]T. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 680–691, 2012
Impact of topical nasal steroid therapy on symptoms of nasal polyposis
Authors: Rudmik Luke , Schlosser Rodney J. , Smith Timothy L. , Soler Zachary M.
Published: March 2012

Objectives/Hypothesis:

Topical steroid therapy is an important strategy in the management of chronic rhinosinusitis (CRS) with nasal polyposis. The objective of this study was to determine the impact of topical steroid therapy on nasal symptoms in patients with nasal polyposis.

Study Design:

Systematic review with meta‐analysis using standardized methodology.

Methods:

Study inclusion criteria included: randomized, placebo controlled trials, nasal polyposis, and topical steroid therapy. Exclusion criteria included: failure to report at least one symptom‐based outcome measure, concurrent use of systemic steroids, or mixed CRS cohorts (polyp and nonpolyp patients). Quantitative analysis was performed using a random effect model. The PRISMA guidelines for meta‐analysis reporting were followed.

Results:

A total of 19 studies fulfilled eligibility. Seven studies were excluded from the meta‐analysis due to significant heterogeneity in outcome reporting. A total of 12 studies were combined for quantitative analysis and demonstrated a pooled risk ratio of 1.72 (95% confidence interval, 1.41–2.09), indicating a significant improvement in nasal symptoms. All three topical steroid preparations (fluticasone, mometasone, and budesonide) resulted in symptom improvement. All seven studies excluded from the meta‐analysis qualitatively confirmed the overall findings.

Conclusions:

Topical nasal steroid therapy improves nasal symptoms in CRS patients with nasal polyposis. Future studies will need to evaluate the impact on quality of life, preferably using validated disease‐specific instruments.
Address Practices and Social Relationships in European Languages
Authors: Norrby Catrin , Warren Jane
Published: March 2012

Address practices – the way people use second‐person pronouns, first names, last names and titles, and other terms to address one another – are fundamental to expressing social relationships. They reflect cultural values and can tell us a great deal about social structures and change. This article gives an overview of recent research on address practices, focusing on three European languages – French, German and Swedish. It follows theoretical developments in the study of address from the 1960s onwards, and examines how address practices have evolved in French, German and Swedish since the socio‐political upheavals of that decade. It is argued that the notions of social distance and common ground are central to an understanding of address choice in these languages.
Materials and Corrosion 3/2012
Authors: Schönberger A. , Virtanen S. , Giese V. , Schröttner H. , Spießberger C.
Published: March 2012

Cover: Grinding surface pattern of steel, coated with thick‐film E‐coat (40 μm) after a stone chipping defect exposed in an accelerated corrosion test (BMW AA‐0224) showing blistering and a corrosion progress. The small image represents a cross section of the sample which was carried out on the FEI Nanolab Nova200 dual‐beam focused ion beam (DB‐FIB – FEI company, Eindhoven, The Netherlands). For the single wide cut (1350 μm by 30 μm) a beam current of 20nA at an acceleration voltage of 20kV was used. Afterwards the part in front of the cross section was removed manually with a scalpel blade. Additional ion beam cross section cleaning with 7nA at 20kV was performed and images were taken with the electron beam using the Everhart‐Thornley detector at 52° tilt angle and an acceleration voltage of 5kV.

Grinding surface pattern and analyzes were investigated at the Austrian Centre for Electron Microscopy and Nanoanalysis (ZFE‐Graz), Graz‐Austria, by Dr. J. Wagner.

More detailed information can be found in: A. Schönberger, S. Virtanen, V. Giese, H. Schröttner, C. Spießberger, Non‐destructive detection of corrosion applied to steel and galvanized steel coated with organic paints by the pulsed phase thermography, Materials and Corrosion 2012, 63, 195.
Entorhinal cortex atrophy differentiates Parkinson's disease patients with and without dementia
Authors: Goldman Jennifer G. , Stebbins Glenn T. , Bernard Bryan , Stoub Travis R. , Goetz Christopher G. , deToledo‐Morrell Leyla
Published: March 2012

Volumetric measures of mesial temporal lobe structures on MRI scans recently have been explored as potential biomarkers of dementia in patients with PD, with investigations primarily focused on hippocampal volume. Both in vivo MRI and postmortem tissue studies in Alzheimer's disease, however, demonstrate that the entorhinal cortex (ERC) is involved earlier in disease‐related pathology than the hippocampus. The ERC, a region integral in declarative memory function, projects multimodal sensory information to the hippocampus through the perforant path. In PD, ERC atrophy, as measured on MRI, however, has received less attention, compared to hippocampal atrophy. We compared ERC and hippocampal atrophy in 12 subjects with PD dementia including memory impairment, 14 PD subjects with normal cognition, and 14 healthy controls with normal cognition using manual segmentation methods on MRI scans. Though hippocampal volumes were similar in the two PD cognitive groups, ERC volumes were substantially smaller in the demented PD subjects, compared to cognitively normal PD subjects (P < 0.05). In addition, normalized ERC and hippocampal volumes for right and left hemispheres were significantly lower in the demented PD group, compared to healthy controls. Our findings suggest that ERC atrophy differentiates demented and cognitively normal PD subjects, in contrast to hippocampal atrophy. Thus, ERC atrophy on MRI may be a potential biomarker for dementia in PD, particularly in the setting of memory impairment. © 2012 Movement Disorder Society
Acquired neurosyphilis presenting as movement disorders
Authors: Shah Binit B. , Lang Anthony E.
Published: March 2012

After a significant decline in the second half of the 20th century, rates of infection with syphilis are again on the rise. Long known as the “great mimicker,” syphilitic infection can be difficult to recognize clinically and this particularly holds true for neurologic manifestations of the disease. Gait dysfunction and sensory ataxia have been historically well described in neurosyphilis literature; however, other movement disorders have been reported to a lesser extent. Here we review reports of movement disorders in acquired neurosyphilis. Given its increasing incidence, it is important to be cognizant of its diverse presentation and retain a high index of suspicion for syphilis, particularly as it is completely curable in the early stages. © 2012 Movement Disorder Society
Reconstruction of divergence‐free velocity fields from cine 3D phase‐contrast flow measurements
Authors: Busch Julia , Giese Daniel , Wissmann Lukas , Kozerke Sebastian
Published: March 2012

Three‐dimensional phase‐contrast velocity vector field mapping shows great potential for clinical applications; however measurement inaccuracies may limit the utility and robustness of the technique. While parts of the error in the measured velocity fields can be minimized by background phase estimation in static tissue and magnetic field monitoring, considerable inaccuracies remain. The present work introduces divergence‐reduction processing of 3D phase‐contrast flow data based on a synergistic combination of normalized convolution and divergence‐free radial basis functions. It is demonstrated that this approach effectively addresses erroneous flow for image reconstructions from both fully sampled and undersampled data. Using computer simulations and in vivo data acquired in the aorta of healthy subjects and a stenotic valve patient it is shown that divergence arising from measurement imperfections can be reduced by up to 87% resulting in improved vector field representations. Based on the results obtained it is concluded that integration of the divergence‐free condition into postprocessing of vector fields presents an efficient approach to addressing flow field inaccuracies. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Single‐shot echo‐planar imaging with Nyquist ghost compensation: Interleaved dual echo with acceleration (IDEA) echo‐planar imaging (EPI)
Authors: Poser Benedikt A. , Barth Markus , Goa Pål‐Erik , Deng Weiran , Stenger V. Andrew
Published: March 2012

Echo planar imaging (EPI) is most commonly used for blood oxygen level‐dependent fMRI, owing to its sensitivity and acquisition speed. A major problem with EPI is Nyquist (N/2) ghosting, most notably at high field. EPI data are acquired under an oscillating readout gradient and hence vulnerable to gradient imperfections such as eddy current delays and off‐resonance effects, as these cause inconsistencies between odd and even k‐space lines after time reversal. We propose a straightforward and pragmatic method herein termed “interleaved dual echo with acceleration (IDEA) EPI”: two k‐spaces (echoes) are acquired under the positive and negative readout lobes, respectively, by performing phase encoding blips only before alternate readout gradients. From these two k‐spaces, two almost entirely ghost free images per shot can be constructed, without need for phase correction. The doubled echo train length can be compensated by parallel imaging and/or partial Fourier acquisition. The two k‐spaces can either be complex averaged during reconstruction, which results in near‐perfect cancellation of residual phase errors, or reconstructed into separate images. We demonstrate the efficacy of IDEA EPI and show phantom and in vivo images at both 3 T and 7 T. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Super‐resolution for multislice diffusion tensor imaging
Authors: Poot Dirk H. J. , Jeurissen Ben , Bastiaensen Yannick , Veraart Jelle , Van Hecke Wim , Parizel Paul M. , Sijbers Jan
Published: March 2012

Diffusion weighted magnetic resonance images are often acquired with single shot multislice imaging sequences, because of their short scanning times and robustness to motion. To minimize noise and acquisition time, images are generally acquired with either anisotropic or isotropic low resolution voxels, which impedes subsequent posterior image processing and visualization. In this article, we propose a super‐resolution method for diffusion weighted imaging that combines anisotropic multislice images to enhance the spatial resolution of diffusion tensor data. Each diffusion weighted image is reconstructed from a set of arbitrarily oriented images with a low through‐plane resolution. The quality of the reconstructed diffusion weighted images was evaluated by diffusion tensor metrics and tractography. Experiments with simulated data, a hardware DTI phantom, as well as in vivo human brain data were conducted. Our results show a significant increase in spatial resolution of the diffusion tensor data while preserving high signal to noise ratio. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
A least squares temporal difference actor–critic algorithm with applications to warehouse management
Authors: Estanjini Reza Moazzez , Li Keyong , Paschalidis Ioannis Ch.
Published: March 2012

This article develops a new approximate dynamic programming (DP) algorithm for Markov decision problems and applies it to a vehicle dispatching problem arising in warehouse management. The algorithm is of the actor‐critic type and uses a least squares temporal difference learning method. It operates on a sample‐path of the system and optimizes the policy within a prespecified class parameterized by a parsimonious set of parameters. The method is applicable to a partially observable Markov decision process setting where the measurements of state variables are potentially corrupted, and the cost is only observed through the imperfect state observations. We show that under reasonable assumptions, the algorithm converges to a locally optimal parameter set. We also show that the imperfect cost observations do not affect the policy and the algorithm minimizes the true expected cost. In the warehouse application, the problem is to dispatch sensor‐equipped forklifts in order to minimize operating costs involving product movement delays and forklift maintenance. We consider instances where standard DP is computationally intractable. Simulation results confirm the theoretical claims of the article and show that our algorithm converges more smoothly than earlier actor–critic algorithms while substantially outperforming heuristics used in practice. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012
Phase‐adjusted echo time (PATE)‐averaging 1H MRS: application for improved glutamine quantification at 2.89 T
Authors: Prescot Andrew P. , Richards Todd , Dager Stephen R. , Choi Changho , Renshaw Perry F.
Published: March 2012

1H MRS investigations have reported altered glutamatergic neurotransmission in a variety of psychiatric disorders. The unraveling of glutamate from glutamine resonances is crucial for the interpretation of these observations, although this remains a challenge at clinical static magnetic field strengths. Glutamate resolution can be improved through an approach known as echo time (TE) averaging, which involves the acquisition and subsequent averaging of multiple TE steps. The process of TE averaging retains the central component of the glutamate methylene multiplet at 2.35 ppm, with the simultaneous attenuation of overlapping phase‐modulated coupled resonances of glutamine and N‐acetylaspartate. We have developed a novel post‐processing approach, termed phase‐adjusted echo time (PATE) averaging, for the retrieval of glutamine signals from a TE‐averaged 1H MRS dataset. The method works by the application of an optimal TE‐specific phase term, which is derived from spectral simulation, prior to averaging over TE space. The simulation procedures and preliminary in vivo spectra acquired from the human frontal lobe at 2.89 T are presented. Three metabolite normalization schemes were developed to evaluate the frontal lobe test–retest reliability for glutamine measurement in six subjects, and the resulting values were comparable with previous reports for within‐subject (9–14%) and inter‐subject (14–20%) measures. Using the acquisition parameters and TE range described, glutamine quantification is possible in approximately 10 min. The post‐processing methods described can also be applied retrospectively to extract glutamine and glutamate levels from previously acquired TE‐averaged 1H MRS datasets. Copyright © 2012 John Wiley & Sons, Ltd.
A wideband fast multipole accelerated boundary integral equation method for time‐harmonic elastodynamics in two dimensions
Authors: Takahashi Toru
Published: March 2012

This article presents a wideband fast multipole method (FMM) to accelerate the boundary integral equation method for two‐dimensional elastodynamics in frequency domain. The present wideband FMM is established by coupling the low‐frequency FMM and the high‐frequency FMM that are formulated on the ingenious decomposition of the elastodynamic fundamental solution developed by Nishimura's group. For each of the two FMMs, we estimated the approximation parameters, that is, the expansion order for the low‐frequency FMM and the quadrature order for the high‐frequency FMM according to the requested accuracy, considering the coexistence of the derivatives of the Helmholtz kernels for the longitudinal and transcendental waves in the Burton–Muller type boundary integral equation of interest. In the numerical tests, the error resulting from the fast multipole approximation was monotonically decreased as the requested accuracy level was raised. Also, the computational complexity of the present fast boundary integral equation method agreed with the theory, that is, Nlog N, where N is the number of boundary elements in a series of scattering problems. The present fast boundary integral equation method is promising for simulations of the elastic systems with subwavelength structures. As an example, the wave propagation along a waveguide fabricated in a finite‐size phononic crystal was demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.
High‐k nanocomposites with modified double layer in carbon black‐epoxy system
Authors: Yang Yooseong , Jee Sang Soo , Lee Eun Sung , Lee Sangmock , Kim Seyun , Lee Jae‐Chan , Son Bui Thanh , Bae Jin‐Young
Published: March 2012

High dielectric constant (K), low dielectric loss (tan δ) polymer nanocomposite is achieved by introducing a modified electrical double layer in the carbon black (CB)‐epoxy system, rather than by exploiting the percolation of CB in the epoxy system, in which both the dielectric constant and loss are increased simultaneously. The modified electrical double layer is introduced in CB‐epoxy system when nanosized nickel oxides embedded in CB absorbs anionic surfactants. In addition to the ionic charges on the CB, high‐k and low dielectric loss can be obtained because of CB passivation with the polymeric surfactant. The CB‐epoxy nanocomposite containing 3.1 vol% of modified CB exhibited a high dielectric constant of K 5200 and a low dielectric loss of tan δ 45% at 1 MHz. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Polypropylene/natural rubber composites filled with recycled newspaper: Effect of chemical treatment using maleic anhydride‐grafted polypropylene and 3‐aminopropyltriethoxysilane
Authors: Osman H. , Ismail H. , Mariatti M.
Published: March 2012

A study on effect of chemical treatment using maleic anhydride‐grafted polypropylene (MAPP) and 3‐aminopropyltiethoxysilane (3‐APE) was investigated. The performance of the MAPP and 3‐APE were investigated by means of torque development, mechanical properties, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy morphology, and water absorption. The results revealed that the use of MAPP or 3‐APE in the composites has increased the stabilization torque, tensile strength, Young's modulus, water absorption, and thermal stability of the PP/NR composites. The incorporation of MAPP in the composites shows higher stabilization torque, tensile strength, EB, Young's modulus, and lower water uptake when compared with the use of 3‐APE in the PP/NR composites. TGA and DSC results indicated that primary and secondary peak of DTG curve, initial degradation temperature (T0), degradation temperature (Tdeg), melting temperature (Tm), heat of fusion of composites (ΔHf(com)), crystallinity of composites (XPP), and PP (XPP) increased, while total weight loss and thermal degradation rate decreased for both treated composites. The MAPP‐treated RNP‐filled PP/NR composites were found to be more thermal resistance and more crystalline than 3‐APE‐treated filled PP/NR RNP composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Polycarbonate/molybdenum disulfide/carbon black composites: Physicomechanical, thermal, wear, and morphological properties
Authors: Basavaraj E. , Ramaraj B. , Siddaramaiah
Published: March 2012

To investigate the influence of molybdenum disulfide (MoS2) as solid lubricant and filler on the polycarbonate (PC) and carbon black (CB) composites, PC containing one weight percentage of CB powder was compounded and extruded with 0.5, 1.0, 2.0, and 3.0 weight percentage of MoS2 powder in a co‐rotating twin screw extruder. Thus, the fabricated PC/CB/MoS2 composites were characterized for physicomechanical properties such as density, void content, surface hardness, tensile behaviors, and impact strength. The thermal characteristics of the composites have been studied by differential scanning calorimetry and dynamic mechanical analysis (DMA). The effect of MoS2 content, loads and sliding distances on wear characteristics of the composites were evaluated using pin‐on‐disc equipment. It was found that wear, friction, and laser etching resistance of PC/CB/MoS2 composites increased with increase in MoS2 content along with improvement in tensile and impact strengths. DMA analysis indicates the storage modulus of PC/CB/MoS2 composites increased with increase in MoS2 content below the glass transition temperature (Tg) of PC. Worn surfaces and laser etched surfaces were examined with scanning electron microscopy and optical microcopy respectively to have better insight of the wear and laser etching mechanism. It was observed that the MoS2 as solid lubricant played major role in improving resistance to wear, friction, and laser etching. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Multifunctional high‐density polyethylene nanocomposites produced by incorporation of exfoliated graphene nanoplatelets 2: Crystallization, thermal and electrical properties
Authors: Jiang Xian , Drzal Lawrence T.
Published: March 2012

This research investigates the effect of exfoliated graphene nanoplatelets (GNP) on the crystallization behavior, thermal conductivity, and electrical conductivity of high‐density polyethylene (HDPE)/GNP nanocomposites. HDPE/GNP nanocomposites were fabricated by melt blending followed with injection molding. Results indicate that GNP is a good nucleating agent at low loading levels and as a result can significantly increase crystallization temperature and crystallinity of HDPE. At high GNP loadings, however, the close proximity of GNP particles retards the crystallization process. The thermal stability and thermal conductivity of HDPE/GNP nanocomposites were found to be significantly enhanced as a function of GNP concentration owing to the excellent thermal properties of GNP. Finally, the high percolation threshold of HDPE/GNP nanocomposites (∼10–15 vol%), prepared by melt blending and injection molding was successfully reduced to around 5 vol% of GNP loading by employing a novel compounding method, solid‐state ball milling. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Role of radicals in UV‐initiated postplasma grafting of poly‐ε‐caprolactone: An electron paramagnetic resonance study
Authors: De Cooman Hendrik , Desmet Tim , Callens Freddy , Dubruel Peter
Published: March 2012

Electron paramagnetic resonance (EPR) measurements were performed on poly‐ε‐caprolactone (PCL) films at different stages of the postplasma‐grafting process. PCL films prepared by solvent casting (SC) or electrospinning (ESP) yield very similar EPR spectra after Ar‐plasma treatment and subsequent exposure to air, but the EPR signal is much stronger in the PCL‐ESP films. The free radicals appear to be mainly, and possibly exclusively, oxygen centered. The radicals generated by UV irradiation in PCL‐ESP films were studied in situ with EPR, using a UV‐LED (λ = (285 ± 5) nm). Their EPR spectrum is distinctly different from the plasma‐induced signal, indicative of carbon‐centered radicals, and appears to be independent of the plasma pretreatment. UV‐induced homolytic splitting of (hydro)peroxide bonds was not observed. Both the plasma‐ and UV‐induced radicals decay at room temperature (RT), even in an inert atmosphere. This study demonstrates the potential of electrospun films and UV‐LEDs for the study of plasma‐ and UV‐generated free radicals with EPR in polyesters, and raises questions with respect to the validity of some generally accepted molecular mechanisms underpinning the postplasma grafting technique for polyesters. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
A multifunctional poly(aryl ether) with oligoaniline and fluorene pendants: Synthesis, electrochromic performance, and tunable fluorescent properties
Authors: Chao Danming , Yang Rui , Jia Xiaoteng , Liu Hongtao , Wang Shutao , Wang Ce , Berda Erik B.
Published: March 2012

A novel multifunctional poly(aryl ether) with both pendant oligoaniline and fluorene groups (PAE‐p‐OF) was synthesized by nucleophilic polycondensation and characterized by 1H NMR, Fourier‐transform infrared spectra, and gel permeation chromatography. The polymer showed excellent solubility in common organic solvents and good thermal stability. Electrochemical and photophysical properties were also investigated using cyclic voltammetry, UV–vis, and fluorescence spectroscopies. The obtained PAE‐p‐OF exhibits satisfactory electrochromic properties with high contrast value, acceptable coloration efficiency, and moderate switching times. Moreover, the fluorescence intensity of PAE‐p‐OF was modulated by controlling oxidation degree of oligoaniline moiety, due to the energy migration occurring between oligoaniline and fluorene groups. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Thermal frontal polymerization with a thermally released redox catalyst
Authors: Parrinello Claudio Attardo , Bounds Christopher O. , Liveri Maria Liria Turco , Pojman John A.
Published: March 2012

We studied thermal frontal polymerization using a redox system in an attempt to lower the temperature of the frontally polymerizable system while increasing the front velocity so as to obtain a self‐sustaining front in a thinner layer than without the redox components. A cobalt‐containing polymer with a melting point of 63 °C (Intelimer 6050X11) and cumene hydroperoxide were used with a triacrylate. The use of the Intelimer decreased the front velocity but allowed fronts to propagate in thinner layers and with more filler while still having a pot life of days. Nonplanar modes of propagation occurred. Fronts propagated faster when 6‐O‐palmitoyl‐L‐ascorbic acid was used as a reductant. Interestingly, fronts were also faster with the reductant even without the Intelimer if kaolin clay was the filler; however, the pot life was significantly reduced. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Modern and Late Holocene Retrogressive Thaw Slump Activity on the Yukon Coastal Plain and Herschel Island, Yukon Territory, Canada
Authors: Lantuit H. , Pollard W. H. , Couture N. , Fritz M. , Schirrmeister L. , Meyer H. , Hubberten H.‐W.
Published: March 2012

Four retrogressive thaw slumps (RTS) located on Herschel Island and the Yukon coast (King Point) in the western Canadian Arctic were investigated to compare the environmental, sedimentological and geochemical setting and characteristics of zones in active and stabilised slumps and at undisturbed sites. In general, the slope, sedimentology and biogeochemistry of stabilised and undisturbed zones differ, independent of their age or location. Organic carbon contents were lower in slumps than in the surrounding tundra, and the density and compaction of slump sediments were much greater. Radiocarbon dating showed that RTS were likely to have been active around 300 a BP and are undergoing a similar period of increased activity now. This cycle is thought to be controlled more by local geometry, cryostratigraphy and the rate of coastal erosion than by variation in summer temperatures. Copyright © 2012 John Wiley & Sons, Ltd.
Protein–protein interaction network‐based detection of functionally similar proteins within species
Authors: Song Baoxing , Wang Fen , Guo Yang , Sang Qing , Liu Min , Li Dengyun , Fang Wei , Zhang Deli
Published: March 2012

Although functionally similar proteins across species have been widely studied, functionally similar proteins within species showing low sequence similarity have not been examined in detail. Identification of these proteins is of significant importance for understanding biological functions, evolution of protein families, progression of co‐evolution, and convergent evolution and others which cannot be obtained by detection of functionally similar proteins across species. Here, we explored a method of detecting functionally similar proteins within species based on graph theory. After denoting protein–protein interaction networks using graphs, we split the graphs into subgraphs using the 1‐hop method. Proteins with functional similarities in a species were detected using a method of modified shortest path to compare these subgraphs and to find the eligible optimal results. Using seven protein–protein interaction networks and this method, some functionally similar proteins with low sequence similarity that cannot detected by sequence alignment were identified. By analyzing the results, we found that, sometimes, it is difficult to separate homologous from convergent evolution. Evaluation of the performance of our method by gene ontology term overlap showed that the precision of our method was excellent. Proteins 2012; © 2012 Wiley Periodicals, Inc.
Comparative modeling and protein‐like features of hydrophobic–polar models on a two‐dimensional lattice
Authors: Moreno‐Hernández Sergio , Levitt Michael
Published: March 2012

Lattice models of proteins have been extensively used to study protein thermodynamics, folding dynamics, and evolution. Our study considers two different hydrophobic–polar (HP) models on the 2D square lattice: the purely HP model and a model where a compactness‐favoring term is added. We exhaustively enumerate all the possible structures in our models and perform the study of their corresponding folds, HP arrangements in space and shapes. The two models considered differ greatly in their numbers of structures, folds, arrangements, and shapes. Despite their differences, both lattice models have distinctive protein‐like features: (1) Shapes are compact in both models, especially when a compactness‐favoring energy term is added. (2) The residue composition is independent of the chain length and is very close to 50% hydrophobic in both models, as we observe in real proteins. (3) Comparative modeling works well in both models, particularly in the more compact one. The fact that our models show protein‐like features suggests that lattice models incorporate the fundamental physical principles of proteins. Our study supports the use of lattice models to study questions about proteins that require exactness and extensive calculations, such as protein design and evolution, which are often too complex and computationally demanding to be addressed with more detailed models. Proteins 2012; © 2012 Wiley Periodicals, Inc.
Modeling small releases from tanks
Authors: (Rick) Knack Fredrick H. , Brown Michelle L. , (Rick) Knack Fredrick W.
Published: March 2012

The methodologies in the chapter on “Dispersion Modeling” in the CCPS book Guidelines for Consequence Analysis of Chemical Releases provide means for modeling outdoor releases at relatively long distances from a large source. At times it is necessary to model releases at relatively short distances from a small source. Making the assumption that the model as developed is valid at the near range, it was used to estimate the levels of ethanol that are emitted from indoor mixing tanks and the potential operator exposure to carbon dioxide released from a lithium bromide manufacturing operation. This article presents the development, implementation, and results of using the model for small releases from tanks. © 2012 American Institute of Chemical Engineers Process Saf Prog, 2012
Structural properties of solid solutions of the non‐dimerized, 3/4‐filled conductors (o‐DMTTF)2X (X = Cl, Br, I)
Authors: Reinheimer Eric W. , Assaf Ali , Jeannin Olivier , Benallouche Abla , Nguyen Phuong‐Tien , Coulon Claude , Fourmigué Marc
Published: March 2012

Halide salts of the unsymmetrically substituted o‐DMTTF, formulated as (o‐DMTTF)2X, X = Cl, Br, I, are organized into uniform chains in a tetragonal structure with space group I‐42d, providing a rare example of non‐dimerized 3/4 filled system. Solid solutions formulated as (o‐DMTTF)(Br)x(Cl)1−x and (o‐DMTTF)2(Br)x(I)1−x have been prepared and structurally characterized. A systematic preferential bromide insertion is observed together with a lateral expansion of the structure with increasing anion size.

magnified image

Tetragonal (space group I–42d) structure of the halide salts of o‐DMTTF, in solid solutions (o‐DMTTF)2(X)x(Y)1−x.