bluuebunny/crossref_metadata_2025 huggingface dataset:
Ligand‐Stabilized and Atomically Precise Gold Nanocluster Catalysis: A Case Study for Correlating Fundamental Electronic Properties with Catalysis
Authors: Liu Jing , Krishna Katla Sai , Losovyj Yaroslav B. , Chattopadhyay Soma , Lozova Natalia , Miller Jeffrey T. , Spivey James J. , Kumar Challa S. S. R.
Published: June 2013

We present results from our investigations into correlating the styrene‐oxidation catalysis of atomically precise mixed‐ligand biicosahedral‐structure [Au25(PPh3)10(SC12H25)5Cl2]2+ (Au25‐bi) and thiol‐stabilized icosahedral core–shell‐structure [Au25(SCH2CH2Ph)18]− (Au25‐i) clusters with their electronic and atomic structure by using a combination of synchrotron radiation‐based X‐ray absorption fine‐structure spectroscopy (XAFS) and ultraviolet photoemission spectroscopy (UPS). Compared to bulk Au, XAFS revealed low Au–Au coordination, AuAu bond contraction and higher d‐band vacancies in both the ligand‐stabilized Au clusters. The ligands were found not only to act as colloidal stabilizers, but also as d‐band electron acceptor for Au atoms. Au25‐bi clusters have a higher first‐shell Au coordination number than Au25‐i, whereas Au25‐bi and Au25‐i clusters have the same number of Au atoms. The UPS revealed a trend of narrower d‐band width, with apparent d‐band spin–orbit splitting and higher binding energy of d‐band center position for Au25‐bi and Au25‐i. We propose that the differences in their d‐band unoccupied state population are likely to be responsible for differences in their catalytic activity and selectivity. The findings reported herein help to understand the catalysis of atomically precise ligand‐stabilized metal clusters by correlating their atomic or electronic properties with catalytic activity.
Molecular Topology Tuning of Bipolar Host Materials Composed of Fluorene‐Bridged Benzimidazole and Carbazole for Highly Efficient Electrophosphorescence
Authors: Mondal Ejabul , Hung Wen‐Yi , Chen Yang‐Huei , Cheng Ming‐Hung , Wong Ken‐Tsung
Published: June 2013

Two new molecules, CzFCBI and CzFNBI, have been tailor‐made to serve as bipolar host materials to realize high‐efficiency electrophosphorescent devices. The molecular design is configured with carbazole as the hole‐transporting block and N‐phenylbenzimidazole as the electron‐transporting block hybridized through the saturated bridge center (C9) and meta‐conjugation site (C3) of fluorene, respectively. With structural topology tuning of the connecting manner between N‐phenylbenzimidazole and the fluorene core, the resulting physical properties can be subtly modulated. Bipolar host CzFCBI with a C connectivity between phenylbenzimidazole and the fluorene bridge exhibited extended π conjugation; therefore, a low triplet energy of 2.52 eV was observed, which is insufficient to confine blue phosphorescence. However, the monochromatic devices indicate that the matched energy‐level alignment allows CzFCBI to outperform its N‐connected counterpart CzFNBI while employing other long‐wavelength‐emitting phosphorescent guests. In contrast, the high triplet energy (2.72 eV) of CzFNBI imparted by the N connectivity ensures its utilization as a universal bipolar host for blue‐to‐red phosphors. With a common device configuration, CzFNBI has been utilized to achieve highly efficient and low‐roll‐off devices with external quantum efficiency as high as 14 % blue, 17.8 % green, 16.6 % yellowish‐green, 19.5 % yellow, and 18.6 % red. In addition, by combining yellowish‐green with a sky‐blue emitter and a red emitter, a CzFNBI‐hosted single‐emitting‐layer all‐phosphor three‐color‐based white electrophosphorescent device was successfully achieved with high efficiencies (18.4 %, 36.3 cd A−1, 28.3 lm W−1) and highly stable chromaticity (CIE x=0.43–0.46 and CIE y=0.43) at an applied voltage of 8 to 12 V, and a high color‐rendering index of 91.6.
Facile Microstructure Control of Mesoporous Co1.29Ni1.71O4 and the Effect of the Microstructure on Lithium‐Storage Performance
Authors: Xiao Ying , Hu Changwen , Cao Minhua
Published: June 2013

A simple and efficient pathway has been designed and developed to synthesize mesoporous Co1.29Ni1.71O4 nanostructures without the use of any templates. By adjusting the volume ratio of water to ethanol, the Co1.29Ni1.71O4 microstructure can be facilely controlled, and different nanostructures such as microflowers, nanorods, and nanoparticles were obtained. All three as‐synthesized samples have a mesoporous structure, but with different pore‐size distributions, in which the nanorod sample exhibits the highest capacity, good rate capability, and cycle stability as an anode material in lithium‐ion batteries (LIBs). The possible reason might be that the one‐dimensional structure of the nanorods accounts for their higher conductivity relative to microflowers and nanoparticles, and their high conductivity coupled with their mesoporous structure might contribute to their excellent electrochemical performance.
Presynaptic Ultrastructural Plasticity Along CA3→CA1 Axons During Long‐Term Potentiation in Mature Hippocampus
Authors: Bourne Jennifer N. , Chirillo Michael A. , Harris Kristen M.
Published: June 2013

In area CA1 of the mature hippocampus, synaptogenesis occurs within 30 minutes after the induction of long‐term potentiation (LTP); however, by 2 hours many small dendritic spines are lost, and those remaining have larger synapses. Little is known, however, about associated changes in presynaptic vesicles and axonal boutons. Axons in CA1 stratum radiatum were evaluated with 3D reconstructions from serial section electron microscopy at 30 minutes and 2 hours after induction of LTP by theta‐burst stimulation (TBS). The frequency of axonal boutons with a single postsynaptic partner was decreased by 33% at 2 hours, corresponding perfectly to the 33% loss specifically of small dendritic spines (head diameters <0.45 μm). Docked vesicles were reduced at 30 minutes and then returned to control levels by 2 hours following induction of LTP. By 2 hours there were fewer small synaptic vesicles overall in the presynaptic vesicle pool. Clathrin‐mediated endocytosis was used as a marker of local activity, and axonal boutons containing clathrin‐coated pits showed a more pronounced decrease in presynaptic vesicles at both 30 minutes and 2 hours after induction of LTP relative to control values. Putative transport packets, identified as a cluster of less than 10 axonal vesicles occurring between synaptic boutons, were stable at 30 minutes but markedly reduced by 2 hours after the induction of LTP. APV blocked these effects, suggesting that the loss of axonal boutons and presynaptic vesicles was dependent on N‐methyl‐D‐aspartic acid (NMDA) receptor activation during LTP. These findings show that specific presynaptic ultrastructural changes complement postsynaptic ultrastructural plasticity during LTP. J. Comp. Neurol. 521:3898–3912, 2013. © 2013 Wiley Periodicals, Inc.
Polyethylene‐Glycol‐Doped Polypyrrole Increases the Rate Performance of the Cathode in Lithium–Sulfur Batteries
Authors: Wu Feng , Chen Junzheng , Li Li , Zhao Teng , Liu Zhen , Chen Renjie
Published: June 2013

Polypyrrole–polyethylene glycol (PPy/PEG)‐modified sulfur/aligned carbon nanotubes (PPy/PEG–S/A‐CNTs) were synthesized by using an in situ polymerization method. The ratio of PPy to PEG equaled 31.7:1 after polymerization, and the PEG served as a cation dopant in the polymerization and electrochemical reactions. Elemental analysis, FTIR, Raman spectroscopy, XRD, and electrochemical methods were performed to measure the physicochemical properties of the composite. Elemental analysis demonstrated that the sulfur, PPy, PEG, A‐CNT, and chloride content in the synthesized material was 64.6 %, 22.1 %, 0.7 %, 12.1 %, and 0.5 %, respectively. The thickness of the polymer shell was about 15–25 nm, and FTIR confirmed the successful PPy/PEG synthesis. The cathode exhibited a high initial specific capacity of 1355 mAh g−1, and a sulfur usage of 81.1 %. The reversible capacity of 924 mAh g−1 was obtained after 100 cycles, showing a remarkably improved cyclability compared to equivalent systems without PEG doping and without any coatings. PPy/PEG provided an effective electronically conductive network and a stable interface structure for the cathode. Rate performance of the PPy/PEG– S/A‐CNT composite was more than double that of the unmodified S/A‐CNTs. Remarkably, the battery could work at a very high current density of 8 A g−1 and reached an initial capacity of 542 mAh g−1; it also retained a capacity of 480 mAh g−1 after 100 cycles. The addition of PEG as a dopant in the PPy shell contributed to this prominent rate improvement. Lithium ions and electrons were available everywhere on the surfaces of the particles, and thus could greatly improve the electrochemical reaction; PEG is a well‐known solvent for lithium salts and a very good lithium‐ion catcher.
Positive feedback for gain enhancement in sub‐100 nm multi‐GHz CMOS amplifier design
Authors: Pude Mark , Mukund P. R. , Burleson Jeff
Published: June 2013

The use of positive feedback as a solution to intrinsic gain degradation in scaled CMOS technologies, such as 65 nm and below, is discussed in detail. Criteria for increasing gain while keeping the system stable are derived using a positive feedback amplifier model. These criteria are shown to provide significant gain enhancement in silicon. This work extends the previously reported DC gain analysis to include evaluation of additional effects of positive feedback as well an investigation of the frequency behavior using S‐parameter measurements in silicon. These S‐parameter measurements of fully differential positive feedback amplifiers designed in TSMC's 65 nm technology show gain enhancements of up to 26.7 dB at frequencies up to 8.5 GHz. Copyright © 2013 John Wiley & Sons, Ltd.
Control of Magnetic Field for Sustainment of Ion Production and Uniform Ion Flux to Substrate in Neutral Loop Discharge Plasma
Authors: Yoshida Takuhei , Sakurai Yohei , Sugawara Hirotake , Murayama Akihiro
Published: June 2013

We simulated electron and ion motions in a neutral loop discharge plasma under the control of the foot of the separatrix sweeping over the substrate and the neutral loop moving within a short distance from the RF antenna by a Monte Carlo method. We analyzed the distributions of ion production and ion flux to the substrate. We found that ion production is sensitive to the magnetic field gradient rather than to the electric field strength. Moreover, by superposing the flux distributions weighted by the residence time of the foot of the separatrix on the substrate, we obtained a uniform time‐averaged distribution of the ion flux to the substrate in a radius range of r = 4.0 to 14.0 cm with σ/m = 0.25% (m: mean, σ: standard deviation). © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(1): 9–16, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22417
Unveiling the rat urinary proteome with three complementary proteomics approaches
Authors: Sánchez‐Juanes Fernando , Muñiz María Carmen , Raposo César , Rodríguez‐Prieto Silvia , Paradela Alberto , Quiros Yaremi , López‐Hernández Francisco , González‐Buitrago José Manuel , Ferreira Laura
Published: June 2013

Urine is a suitable biological fluid to look for markers of physiological and pathological processes, including renal and nonrenal diseases. In addition, it is an optimal body sample for diagnosis, because it is easily obtained without invasive procedures and can be sampled in large quantities at almost any time. Rats are frequently used as a model to study human diseases, and rat urine has been analyzed to search for disease biomarkers. The normal human urinary proteome has been studied extensively, but the normal rat urinary proteome has not been studied in such depth. In light of this, we were prompted to analyze the normal rat urinary proteome using three complementary proteomics platforms: SDS‐PAGE separation, followed by LC‐ESI‐MS/MS; 2DE, followed by MALDI‐TOF‐TOF and 2D‐liquid chromatography‐chromatofocusing, followed by LC‐ESI‐Q‐TOF. A total of 366 unique proteins were identified, of which only 5.2% of unique proteins were identified jointly by the three proteomics platforms used. This suggests that simultaneous proteomics techniques provide complementary and nonredundant information. Our analysis affords the most extensive rat urinary protein database currently available and this may be useful in the study of renal physiology and in the search for biomarkers related to renal and nonrenal diseases.
Trust management system in wireless sensor networks: design considerations and research challenges
Authors: Ishmanov Farruh , Malik Aamir Saeed , Kim Sung Won , Begalov Bahodir
Published: June 2013

Trust is an important factor in wireless sensor networks (WSNs) in terms of security enhancement and successful collaboration. Trust management (TM) can ensure that all communicating nodes are trustworthy during authentication, authorisation, or key management, which makes traditional security services more robust and reliable. Moreover, by helping to find reliable nodes, TM improves cooperation among nodes, which is vital for improvement of system performance. Trust estimations and management are highly challenging issues because of the unique features and susceptibility of WSNs to different attacks. These factors prevent direct application of schemes suited to other networks and require careful design in a TM system. Hence, our objective is to discuss and present the concept and design factors of TM in WSNs in detail. Moreover, we explore the current state of research as well as open research issues by reviewing proposed trust computation and management schemes in WSNs. Copyright © 2013 John Wiley & Sons, Ltd.
Avoiding damage and achieving cold tolerance in rice plants
Authors: Cruz Renata Pereira da , Sperotto Raul Antonio , Cargnelutti Denise , Adamski Janete Mariza , de FreitasTerra Tatiana , Fett Janette Palma
Published: June 2013

Rice is a staple food for half of the human population. Unlike other cereals such as wheat and barley, rice plants are susceptible to cold stress, which often results in decreased productivity, especially in regions where theindicasubspecies is cultivated. Low temperatures can have negative impacts on rice plants during germination, vegetative growth, and reproductive stages. Considering the expected higher frequency of extreme temperature events in the near future, cold waves could even increase the negative impacts of low temperatures in rice production. Here, we review the efforts that have been made to achieve cold tolerance in rice through breeding, the major tools used for evaluating cold tolerance in rice plants, the discovery of quantitative trait loci (QTLs) and genes related to this tolerance, and the results obtained so far by genetic transformation of rice plants with potential cold‐tolerance genes. Although much progress has been achieved, joint efforts from breeders and plant biologists could speed up the production of cold‐tolerant rice plants, and some possible approaches are suggested.
Improvement in the traditional processing method and nutritional quality of traditional extruded cassava‐based snack (modified Ajogun)
Authors: Obadina Adewale O. , Oyewole Olusola B. , Williams Oluwasolabomi E.
Published: June 2013

This study was carried out to investigate and improve the traditional processing method and nutritional quality of the traditional cassava snack (Ajogun). Cassava root (Manihot esculenta Crantz L.) of TME 419 variety was processed into mash (40% moisture content). The cassava mash was mixed into different blends to produce fried traditional “Ajogun”, fried and baked extrudates (modified Ajogun) as snacks. These products were analyzed to determine the proximate composition including carbohydrate, fat, protein, fiber, ash, and moisture contents and functional properties such as bulk density. The results obtained for the moisture, fat, protein, and ash contents showed significant difference (P < 0.05) between the control sample and the extrudates. However, there was no significant difference (P > 0.05) in the carbohydrate and fiber contents between the three samples. There was no significant difference (P > 0.05) in the bulk density of the snacks. Also, sensory evaluation was carried out on the cassava‐based snacks using the 9‐point hedonic scale to determine the degree of acceptability. Results obtained showed significant difference (P < 0.05) between the extrudates and control sample in terms of appearance, taste, flavor, color, aroma, texture, and overall acceptability. The highest acceptability level of the product was at 8.04 for the control sample (traditional Ajogun). This study has shown that “Ajogun”, which is a lesser known cassava product, is rich in protein and fat.
Contrasting Effects of Central Pacific and Eastern Pacific El Niño on stratospheric water vapor
Authors: Garfinkel Chaim I. , Hurwitz Margaret M. , Oman Luke D. , Waugh Darryn W.
Published: June 2013

Targeted experiments with a comprehensive chemistry‐climate model are used to demonstrate that seasonality and the location of the peak warming of sea surface temperatures dictate the response of stratospheric water vapor to El Niño. In boreal spring, El Niño events in which sea surface temperature anomalies peak in the eastern Pacific lead to a warming at the tropopause above the warm pool region, and subsequently to more stratospheric water vapor (consistent with previous work). However, in fall and in early winter, and also during El Niño events in which the sea surface temperature anomaly is found mainly in the central Pacific, the response is qualitatively different: temperature changes in the warm pool region and specifically over the cold point region are nonuniform, and less water vapor enters the stratosphere. The difference in water vapor in the lower stratosphere between the two variants of El Niño approaches 0.3 ppmv, while the difference between the winter and spring responses exceeds 0.5 ppmv.
Complex networks identify spatial patterns of extreme rainfall events of the South American Monsoon System
Authors: Boers Niklas , Bookhagen Bodo , Marwan Norbert , Kurths Jürgen , Marengo José
Published: June 2013

We investigate the spatial characteristics of extreme rainfall synchronicity of the South American Monsoon System (SAMS) by means of Complex Networks (CN). By introducing a new combination of CN measures and interpreting it in a climatic context, we investigate climatic linkages and classify the spatial characteristics of extreme rainfall synchronicity. Although our approach is based on only one variable (rainfall), it reveals the most important features of the SAMS, such as the main moisture pathways, areas with frequent development of Mesoscale Convective Systems (MCS), and the major convergence zones. In addition, our results reveal substantial differences between the spatial structures of rainfall synchronicity above the 90th and above the 95th percentiles. Most notably, events above the 95th percentile contribute stronger to MCS in the La Plata Basin.
Forward mapping of solar energetic proton distributions through the geomagnetic field
Authors: Kouznetsov A. , Knudsen D. J.
Published: June 2013

During solar proton events, large ejections of energetic protons spread throughout the interplanetary medium, penetrate the geomagnetic field, and are deposited in the upper polar atmosphere where they play important roles in its physical and chemical processes. We develop a model of direct proton propagation through a static geomagnetic field based on a generalized leapfrog method and validate it through comparison with Störmer theory. We then apply the algorithm to two ideal cases representing the late and early phases of a solar particle event, for proton energies of 10, 100, and 1000 MeV. The late‐phase case is represented by an isotropic infinite bath of protons surrounding the magnetosphere; in this case, most protons reaching the polar cap originate within ±20° of the magnetic equatorial plane, with pronounced peaks near ±20°. The early‐phase case is represented by broad, monodirectional proton beams; these sources are highly focused by the geomagnetic field, with all particles mapping to small regions in the polar cap only a few hundred kilometers across, and with low‐energy particles being focused more than higher‐energy ones. Pure dipole and International Geomagnetic Reference Field‐11 magnetic field models lead to very similar fluence patterns in the polar cap, though the latter are somewhat less focused.
A thermal plume model for the Martian convective boundary layer
Authors: Colaïtis A. , Spiga A. , Hourdin F. , Rio C. , Forget F. , Millour E.
Published: June 2013

The Martian planetary boundary layer (PBL) is a crucial component of the Martian climate system. Global climate models (GCMs) and mesoscale models (MMs) lack the resolution to predict PBL mixing which is therefore parameterized. Here we propose to adapt the “thermal plume” model, recently developed for Earth climate modeling, to Martian GCMs, MMs, and single‐column models. The aim of this physically based parameterization is to represent the effect of organized turbulent structures (updrafts and downdrafts) on the daytime PBL transport, as it is resolved in large‐eddy simulations (LESs). We find that the terrestrial thermal plume model needs to be modified to satisfyingly account for deep turbulent plumes found in the Martian convective PBL. Our Martian thermal plume model qualitatively and quantitatively reproduces the thermal structure of the daytime PBL on Mars: superadiabatic near‐surface layer, mixing layer, and overshoot region at PBL top. This model is coupled to surface layer parameterizations taking into account stability and turbulent gustiness to calculate surface‐atmosphere fluxes. Those new parameterizations for the surface and mixed layers are validated against near‐surface lander measurements. Using a thermal plume model moreover enables a first‐order estimation of key turbulent quantities (e.g., PBL height and convective plume velocity) in Martian GCMs and MMs without having to run costly LESs.
Hypoxia inducible factor‐1 alpha plays a pivotal role in hepatic metastasis of pancreatic cancer: an immunohistochemical study
Authors: Matsuo Yoichiro , Ding Qiang , Desaki Ryosuke , Maemura Kosei , Mataki Yuko , Shinchi Hiroyuki , Natsugoe Shoji , Takao Sonshin
Published: June 2013

Background

Hypoxia is an important condition to promote angiogenesis that is essential to tumor progression, including pancreatic ductal adenocarcinoma (PDAC). We evaluated whether the immunohistochemistry for hypoxia inducible factor‐1α (HIF‐1α) was correlated with hepatic metastases in PDAC.

Methods

We examined the expression of HIF‐1α, vascular endothelial growth factor‐A (VEGF‐A), thymidine phosphorylase (TP) and basic fibroblast growth factor (bFGF) in a total of 100 paraffin‐embedded PDAC primary tumors using immunohistochemical staining, and assessed their clinicopathological correlations. We determined microvessel count (MVC) and apoptotic index (AI), and assessed their correlations with hepatic metastases. Student's t‐test, the Mann–Whitney U‐test, and Spearman correlation coefficients were used to validate the model, and regression analysis was used to test the model.

Results

Hypoxia inducible factor‐1α expression induced the expression of multiple angiogenic factors, leading to a higher MVC and a lower AI. HIF‐1α expression (P = 0.0087) and angiogenic factors (P = 0.0079) were significantly associated with not only the microvessel status (P = 0.022) but also the high incidence of hepatic metastasis (P = 0.02), resulting in the worse survival of PDAC patients (P < 0.05).

Conclusions

Hypoxia inducible factor‐1α plays a pivotal role in hepatic metastasis through its association with the expression of angiogenic factors in PDAC patients. These results may contribute future therapeutic strategies to prevent pancreatic cancer metastasis.
Selection of ceramic fluorapatite‐binding peptides from a phage display combinatorial peptide library: optimum affinity tags for fluorapatite chromatography
Authors: Islam Tuhidul , Bibi Noor Shad , Vennapusa Rami Reddy , Fernandez‐Lahore Marcelo
Published: June 2013

Peptide affinity tags have become efficient tools for the purification of recombinant proteins from biological mixtures. The most commonly used ligands in this type of affinity chromatography are immobilized metal ions, proteins, antibodies, and complementary peptides. However, the major bottlenecks of this technique are still related to the ligands, including their low stability, difficulties in immobilization, and leakage into the final products. A model approach is presented here to overcome these bottlenecks by utilizing macroporous ceramic fluorapatite (CFA) as the stationary phase in chromatography and the CFA‐specific short peptides as tags. The CFA chromatographic materials act as both the support matrix and the ligand. Peptides that bind with affinity to CFA were identified from a randomized phage display heptapeptide library. A total of five rounds of phage selection were performed. A common N‐terminal sequence was found in two selected peptides: F4‐2 (KPRSMLH) and F5‐4 (KPRSVSG). The peptide F5‐4, displayed by more than 40% of the phages analyzed in the fifth round of selection, was subjected to further studies. Selectivity of the peptide for the chemical composition and morphology of CFA was assured by the adsorption studies. The dissociation constant, obtained from the F5‐4/CFA adsorption isotherm, was in the micromolar range, and the maximum capacity was 39.4 nmol/mg. The chromatographic behavior of the peptides was characterized on a CFA stationary phase with different buffers. Preferential affinity and specific retention properties suggest the possible application of the phage‐derived peptides as a tag in CFA affinity chromatography for enhancing the selective recovery of proteins. Copyright © 2013 John Wiley & Sons, Ltd.
Concept to improve the resistance of bearing steels to seawater
Authors: Krasokha N. , Berns H.
Published: June 2013

Zur Entwicklung von korrosionsbeständigen härtbaren Wälzlagerstählen für die Meerwassertechnik wurden die Gehalte an Mo und Cr gegenüber X65Cr14 erhöht und der C‐Gehalt durch Nutzung des löslichen N‐Gehaltes gesenkt. Die unter Normaldruck zu erschmelzenden Stähle X51CrN(14)14 und X51CrMoN(14)15‐3 sowie der unter einem N2‐Druck von = 4,7 bar zu erschmelzende X33CrMoN(32)15‐3 versprechen eine höhere Beständigkeit gegen Lochkorrosion und eine geringere Gefahr seigerungsbedingter grober eutektischer Karbide ohne erkennbare Nachteile für die Härte und den Restaustenitgehalt. Die Studie hat allein durch thermodynamische Rechnungen und empirische Formeln ohne zeit‐ und kostenaufwendige Experimente zu einer Vorauswahl erfolgsversprechender neuer Stähle geführt.
A novel abrasive blasting process: Abrasive medium classification and CFD simulations
Authors: Özkaya E. , Bayraktar E. , Turek S. , Biermann D.
Published: June 2013

This study concerns the determination of the significant factors for an innovative deburring process: low pressure abrasive water‐jet blasting. The abrasive medium aluminum oxide (Al2O3) is classified according to the individual characteristics of different grain sizes. Then, the particle behavior in the air jet is analyzed with an optical measuring method, Particle Image Velocimetry (PIV); the velocity profile and the particle distribution of the dispersed system are obtained. Computational Fluid Dynamics (CFD) simulations were verified by comparing the experimental and numerical results, and the velocity range for the abrasive particles has been specified.
Necessary and sufficient conditions on the asymptotic behavior of second‐order neutral delay dynamic equations with positive and negative coefficients
Authors: Karpuz B.
Published: June 2013

In this paper, we establish necessary and sufficient conditions for the solutions of a second‐order nonlinear neutral delay dynamic equation with positive and negative coefficients to be oscillatory or tend to zero asymptotically. We consider three different ranges of the coefficient associated with the neutral part in one of which it is allowed to be oscillatory. Thus, our results improve and generalize the existing results in the literature to arbitrary time scales. Some examples on nontrivial time scales are also given. Copyright © 2013 John Wiley & Sons, Ltd.
Improving T2‐weighted imaging at high field through the use of kT‐points
Authors: Eggenschwiler Florent , O'Brien Kieran R. , Gruetter Rolf , Marques José P.
Published: June 2013

Purpose

At high magnetic field strengths (B0 ≥ 3 T), the shorter radiofrequency wavelength produces an inhomogeneous distribution of the transmit magnetic field. This can lead to variable contrast across the brain which is particularly pronounced in T2‐weighted imaging that requires multiple radiofrequency pulses. To obtain T2‐weighted images with uniform contrast throughout the whole brain at 7 T, short (2–3 ms) 3D tailored radiofrequency pulses (kT‐points) were integrated into a 3D variable flip angle turbo spin echo sequence.

Methods

The excitation and refocusing “hard” pulses of a variable flip angle turbo spin echo sequence were replaced with kT‐point pulses. Spatially resolved extended phase graph simulations and in vivo acquisitions at 7 T, utilizing both single channel and parallel‐transmit systems, were used to test different kT‐point configurations.

Results

Simulations indicated that an extended optimized k‐space trajectory ensured a more homogeneous signal throughout images. In vivo experiments showed that high quality T2‐weighted brain images with uniform signal and contrast were obtained at 7 T by using the proposed methodology.

Conclusion

This work demonstrates that T2‐weighted images devoid of artifacts resulting from B1+ inhomogeneity can be obtained at high field through the optimization of extended kT‐point pulses. Magn Reson Med 71:1478–1488, 2014. © 2013 Wiley Periodicals, Inc.
Fast noniterative calibration of an external motion tracking device
Authors: Zahneisen Benjamin , Lovell‐Smith Chris , Herbst Michael , Zaitsev Maxim , Speck Oliver , Armstrong Brian , Ernst Thomas
Published: June 2013

Purpose

Prospective motion correction of magnetic resonance (MR) scans commonly uses an external device, such as a camera, to track the pose of the organ of interest. However, in order for external tracking data to be translated into the MR scanner reference frame, the pose of the camera relative to the MR scanner must be known accurately. Here, we describe a fast, accurate, non‐iterative technique to determine the position of an external tracking device de novo relative to the MR reference frame.

Theory and Methods

The method relies on imaging a sparse object that allows simultaneous tracking of arbitrary rigid body transformations in the reference frame of the magnetic resonance imaging (MRI) machine and that of the external tracking device.

Results

Large motions in the MRI reference frame can be measured using a sparse phantom with an accuracy of 0.2 mm, or approximately 1/10 of the voxel size. By using a dual quaternion algorithm to solve the calibration problem, a good camera calibration can be achieved with fewer than six measurements. Further refinements can be achieved by applying the method iteratively and using motion correction feedback.

Conclusion

Independent tracking of a series of movements in two reference frames allows for an analytical solution to the hand‐eye‐calibration problem for various motion tracking setups in MRI. Magn Reson Med 71:1489–1500, 2014. © 2013 Wiley Periodicals, Inc.
Improved steering of the RF field of traveling wave MR with a multimode, coaxial waveguide
Authors: Andreychenko A. , Kroeze H. , Boer V. O. , Lagendijk J. J. W. , Luijten P. R. , van den Berg C. A. T.
Published: June 2013

Purpose

Magnetic resonance imaging of humans at high magnetic field strengths is strongly influenced by the interference of the radiofrequency (RF) electromagnetic field and the body. To minimize this effect, multiple RF sources could be used. A novel setup (called multimode, coaxial waveguide) is proposed that facilitates RF shimming based on the traveling waves.

Methods

The multimode, coaxial waveguide combines the coaxial waveguide, cylindrical waveguide, high dielectric permittivity lining, and eight radial stub antennas. Each antenna excites multiple waveguide modes. Based on modes orthogonality, a method was devised to decompose an excitation pattern of single stub antenna into waveguide modes.

Results

The number of modes present in the excitation pattern of a single stub antenna increased with the higher effective permittivity of the dielectric lining. Thus, RF shimming performance of the setup was improved. An average homogeneity of 10% was demonstrated for a single slice of each principle plane in the human head at 7 T.

Conclusion

Traveling wave RF shimming is feasible both in axial and longitudinal directions and is improved with an increased amount of orthogonal waveguide modes. Nevertheless, with the currently available RF amplifiers at 7 T, the performance of the setup is limited to low flip angles. Magn Reson Med 71:1641–1649, 2014. © 2013 Wiley Periodicals, Inc.
A randomized controlled pilot study testing three types of health coaches for obesity treatment: Professional, peer, and mentor
Authors: Leahey Tricia M. , Wing Rena R.
Published: June 2013

Despite their popularity, empirical support for health coaches is limited.

Objective:

This study examined the feasibility and preliminary efficacy of three types of coaching models for obesity treatment.

Design and Methods:

Participants (N = 44) were randomized to 6 months of reduced intensity group behavioral weight loss (rBWL) plus one of three types of health coaches: (i) Professional (rBWL interventionist), (ii) Peer (group members randomly paired and coached one another), or (iii) Mentor (successful weight loser). Groups met weekly for the first 6 weeks, biweekly for the next 6 weeks, and monthly thereafter, for a total of 12 meetings. During weeks that group did not meet, participants emailed their weight loss information to their coach and received feedback. Coaches were trained on appropriate coaching strategies and feedback delivery.

Results:

Retention was 95%. Participants emailed their progress to their coach 10.8 ± 1.9 of the 12 weeks that there were no group meetings. Coaches responded with feedback 94% of the time. Percent weight losses at 6 months were 9.6 ± 8.1, 9.1 ± 5.0, and 5.7 ± 5.6 for the Professional, Peer, and Mentor conditions, respectively. More participants in the Professional and Peer conditions lost 10% of their initial body weight (Professional: 56% Peer: 50% and Mentor: 17%), with a statistically significant difference between the Professional and Mentor conditions (P = 0.03).

Conclusion:

These preliminary data suggest that combining a rBWL program with health coaching may hold significant promise as a cost‐effective obesity treatment paradigm. Larger trials are needed to conclusively determine whether adding coaches improves weight loss outcomes in reduced intensity treatments and to examine which type of coach is most effective.
The use of routine thoracoabdominal CT scans in the polytrauma patient to estimate obesity
Authors: Ferguson David F. , Busenlehner Bryce J. , Rahm Mark D. , Mehta Sachin M. , Song Juhee , Davis Matthew L. , Sampson H. Wayne , Chaput Christopher D.
Published: June 2013

Objective:

To utilize data from routine CT scans to quantify obesity in polytrauma patients without the need to obtain a height and weight.

Design and Methods:

We utilized a comprehensive database including multidetector CT thoracoabdominal images of all polytrauma patients admitted to a Level 1 trauma center. One thousand one hundred seventy‐four patients were reviewed from 2006 to 2008 and of these, 162 had previous documentation of Body Mass Index (BMI) or height and weight measurements as an outpatient within 6 months of trauma activation and with a truncal girth smaller than the scanning area of the CT machine. Truncal Adiposity Volume (TAV) was calculated from three dimensional reconstructions (3DRs) of the CT scans of the thorax and abdomen obtained in the emergency department.

Results:

Statistical analysis yielded a fairly good correlation between TAV and BMI (correlation coefficient = 0.77; p‐value < 0.0001). The intra‐observer and inter‐observer correlations in measuring TAV were high; 0.99 and 0.98 respectively. A linear regression equation of BMI on TAV was estimated and it had a form: 3DR BMI = 20.81+0.00064×TAV. In conclusion, TAV provides a reproducible means of evaluating obesity in trauma patients from routinely obtained CT scans.

Conclusions:

The TAV eliminates the often problematic task of obtaining a height and weight in a trauma patient and it correlates fairly well with the most commonly used clinical method of quantifying patient adiposity, BMI. This method may provide a more direct measurement of adiposity than does BMI, and holds promise for improving trauma care and research in the obese patient.
Hollow mesoporous silica nanoparticles modified with coumarin‐containing copolymer for photo‐modulated loading and releasing guest molecule
Authors: Yang Jing , He Wei‐Dong , He Chen , Tao Jing , Chen Sheng‐Qi , Niu Shao‐Min , Zhu Shao‐Lin
Published: June 2013

Hollow mesoporous silica nanoparticles (HMSNs) grafted with a photo‐responsive copolymer containing coumarin groups were successfully prepared. With uniform polystyrene nanoparticles and cetyltrimethylammonium bromide correspondingly as the template of core and channel, HMSNs were made from tetraethyloxysilane in alkalic condition. Epoxy groups were introduced onto the outer surface of HMSNs with γ‐(2,3‐epoxypropoxy)propyltrimethoxysilane and converted into azido groups with sodium azide, resulting in azido‐functionalized HMSNs (azido‐HMSNs). Meanwhile, single‐electron transfer‐living radical copolymerization of methyl methacrylate (MMA) and 7‐(2‐methacryloyloxy)‐4‐methylcoumarin (CMA) with propargyl 2‐bromoisobutyrate as the initiator produced alkynyl‐capped P(MMA‐co‐CMA) [alkynyl‐P(MMA‐co‐CMA)]. Finally, photo‐responsive HMSNs grafted with P(MMA‐co‐CMA) [HMSN‐g‐P(MMA‐co‐CMA)] was achieved through the click reaction between azido‐HMSNs and alkynyl‐P(MMA‐co‐CMA). Different techniques such as transmission electron microscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis confirmed the successful preparation of the resultant hybrid nanoparticles and their intermediates. Because of its hollow core, mesoporous shell channels and light responsiveness, the coumarin‐modified HMSNs would be an interesting nano‐vehicle for guest molecules. Thus, the loading and release of pyrene with HMSN‐g‐P(MMA‐co‐CMA) was studied. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3791–3799
A New General Correlation for Predicting Impact Sensitivity of Energetic Compounds
Authors: Keshavarz Mohammad H.
Published: June 2013

This paper describes an improved simple model for prediction of impact sensitivity of different classes of energetic compounds containing nitropyridines, nitroimidazoles, nitropyrazoles, nitrofurazanes, nitrotriazoles, nitropyrimidines, polynitroarenes, benzofuroxans, polynitroarenes with α‐CH, nitramines, nitroaliphatics, nitroaliphatic containing other functional groups, and nitrate energetic compounds. The model is based on some molecular structural parameters. It is applied for 90 explosives, which have different molecular structures. The predicted results are compared with outputs of complex neural network approach as one of the best available methods. Root mean squares (rms) of deviations of different energetic compounds are 24 and 49 cm, corresponding to 5.88 and 12.01 J with 2.5 kg dropping mass, for new and neural network methods, respectively. The novel model also predicts good results for eight new synthesized and miscellaneous explosives with respect to experimental data.
Determination of exposure levels of honey bees foraging on flowers of mature citrus trees previously treated with imidacloprid
Authors: Byrne Frank J , Visscher P Kirk , Leimkuehler Bill , Fischer Dave , Grafton‐Cardwell Elizabeth E , Morse Joseph G
Published: June 2013

BACKGROUND

Field and tunnel cage studies were undertaken to determine the extent to which honey bees foraging on citrus blossoms were exposed to imidacloprid and its metabolites when citrus trees were treated with soil applications of the insecticide. Residues were measured by LC/MS/MS in nectar and pollen samples from trees treated up to 232 days prior to bloom.

RESULTS

Imidacloprid, imidacloprid olefin and 5‐hydroxy imidacloprid were detected in nectar and pollen sampled from the flowers of citrus trees treated with imidacloprid up to 232 days prior to bloom. In tunnel studies, where foraging was restricted exclusively to citrus, imidacloprid residues in nectar extracted from flowers and from bee crops were similar (<10 ng mL−1) and below the established no‐observed‐effects limit; however, the residue levels were about threefold higher in nectar sampled from comb. Concentrations of imidacloprid in nectar were higher in trees treated with higher application rates.

CONCLUSIONS

Imidacloprid and its metabolites were detected in the nectar and pollen of citrus trees treated up to 232 days prior to the onset of bloom. However, based on published bioassay data, the imidacloprid concentrations in the floral nectar did not surpass levels that would compromise foraging activity under normal use conditions for imidacloprid. Further research is needed to assess the impact of elevated levels of imidacloprid within stored nectar in the comb. © 2013 Society of Chemical Industry
Change‐point models to estimate the limit of detection
Authors: May Ryan C. , Chu Haitao , Ibrahim Joseph G. , Hudgens Michael G. , Lees Abigail C. , Margolis David M.
Published: June 2013

In many biological and environmental studies, measured data is subject to a limit of detection. The limit of detection is generally defined as the lowest concentration of analyte that can be differentiated from a blank sample with some certainty. Data falling below the limit of detection is left censored, falling below a level that is easily quantified by a measuring device. A great deal of interest lies in estimating the limit of detection for a particular measurement device. In this paper, we propose a change‐point model to estimate the limit of detection by using data from an experiment with known analyte concentrations. Estimation of the limit of detection proceeds by a two‐stage maximum likelihood method. Extensions are considered that allow for censored measurements and data from multiple experiments. A simulation study is conducted demonstrating that in some settings the change‐point model provides less biased estimates of the limit of detection than conventional methods. The proposed method is then applied to data from an HIV pilot study. Copyright © 2013 John Wiley & Sons, Ltd.
Origin of Copious Recrystallization in Cold Rolled Interstitial Free (IF) Steels
Authors: Quadir Md Zakaria , Munroe Paul Richard
Published: June 2013

Copious recrystallization occurs during the very early stages of annealing in some deformed grains in 85% cold rolled IF steel. This event happens to certain regions in γ oriented grains while the α oriented grains remain unrecrystallized. The orientations of the newly forming grains are near either {111}<123> or {554}<225>, and as a result the intensity at these orientations are high in the recrystallization texture. An investigation by scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) shows that such copious recrystallization event originates from the frequent presence of high crystallographic gradients, at the locations where two set shear bands intersect.
Hydrogen Softening in the Thin Plate of Microcrystalline 316L Stainless Steel
Authors: Kim Yunsung , Shin Dongjun , Kim Youngsuk , Kim Dae Whan , Kim Sungsoo , Nam Wonjong , Kim Yong‐Suk , Máthis Kristián , Choe Heeman
Published: June 2013

The thin‐plate specimen of 316L austenite stainless steel was charged with hydrogen using a cathodic charging technique. Despite the short diffusion distance of hydrogen predicted by the diffusion‐controlled model for a semi‐infinite sheet, the Vickers hardness measurements revealed the full effect of hydrogen in the center of the cross‐sections of thin‐plate specimens as well as in the vicinity of the outer surfaces, which appears to be due to the short‐circuit diffusion mechanism along the grain boundaries. The room‐temperature tensile properties of both undeformed and deformed (20, 40%) samples were examined and compared. Hydrogen softening was apparent in both types of samples. For example, the 40% deformed sample showed an approximately 17 and 7% lower yield and tensile strength, respectively, after H charging at a strain rate of 2 × 10−4 s−1 with a concomitant decrease in ductility compared to that without H.
Multielemental analysis of powder samples by direct measurement with TXRF
Authors: Cantaluppi C. , Natali M. , Ceccotto F. , Fasson A.
Published: June 2013

Total reflection X‐ray fluorescence analysis was used to measure various powder samples directly put on an adhesive carbon tab placed on a quartz carrier. In this paper, the ability of the method to perform quantitative multielemental analysis without sample digestion was demonstrated. To assess the optimal measurement conditions, angular scans to find the best glancing angle were carried out, different kinds of reference standard powders were measured, and matrix effects and detection limits were evaluated. The results show a good agreement of data obtained with certified values. This quick method can be applied to characterize powders without any chemical treatment, thus reducing time for analysis and minimizing the risk of sample contamination. As a consequence, a great advantage is that a large number of samples can be analyzed in a short time: This method can be very useful in environmental applications such as the analysis of many atmospheric particulate samples from a wide area and for repeated monitoring. Copyright © 2013 John Wiley & Sons, Ltd.
Molecular mapping of QTLs for resistance to Fusarium wilt (race 1) and Ascochyta blight in chickpea (Cicer arietinum L.)
Authors: Sabbavarapu Murali Mohan , Sharma Mamta , Chamarthi Siva Kumar , Swapna Nayakoti , Rathore Abhishek , Thudi Mahendar , Gaur Pooran Mal , Pande Suresh , Singh Sarvjeet , Kaur Livinder , Varshney Rajeev Kumar
Published: June 2013

Fusarium wilt (FW) and Ascochyta blight (AB) are two important diseases of chickpea which cause 100 % yield losses under favorable conditions. With an objective to validate and/or to identify novel quantitative trait loci (QTLs) for resistance to race 1 of FW caused by Fusarium oxysporum f. sp. ciceris and AB caused by Ascochyta rabiei in chickpea, two new mapping populations (F2:3) namely ‘C 214’ (FW susceptible) × ‘WR 315’ (FW resistant) and ‘C 214’ (AB susceptible) × ‘ILC 3279’ (AB resistant) were developed. After screening 371 SSR markers on parental lines and genotyping the mapping populations with polymorphic markers, two new genetic maps comprising 57 (C 214 × WR 315) and 58 (C 214 × ILC 3279) loci were developed. Analysis of genotyping data together with phenotyping data collected on mapping population for resistance to FW in field conditions identified two novel QTLs which explained 10.4–18.8 % of phenotypic variation. Similarly, analysis of phenotyping data for resistance to seedling resistance and adult plant resistance for AB under controlled and field conditions together with genotyping data identified a total of 6 QTLs explaining up to 31.9 % of phenotypic variation. One major QTL, explaining 31.9 % phenotypic variation for AB resistance was identified in both field and controlled conditions and was also reported from different resistant lines in many earlier studies. This major QTL for AB resistance and two novel QTLs identified for FW resistance are the most promising QTLs for molecular breeding separately or pyramiding for resistance to FW and AB for chickpea improvement.