bluuebunny/crossref_metadata_2025 huggingface dataset:
Utilizing a nano‐sorbent for the selective solid‐phase extraction of vanillic acid prior to its determination by photoluminescence spectroscopy
Authors: Abdolmohammad‐Zadeh Hossein , Mahmoudi‐kordi Fatemeh , Rahmati Manoochehr
Published: April 2014

Vanillic acid (VA) is a phenolic acid, and acts as a natural antioxidant in fruits, vegetables and plants. The extraction and determination of trace levels of VA in plants is important, because stimulation of protein synthesis and activation of antioxidant enzymes occur in the presence of phenolic acids at trace levels. In this research, a photoluminescence spectroscopic method was developed for the quantification of VA in plant samples after separation and pre‐concentration. Selective extraction of VA from aqueous solution was performed using a solid‐phase extraction column packed with nickel–aluminum layered double hydroxide as a nano‐sorbent. After elution of extracted analyte from the column using 3 mL of a 3 mol/L NaOH solution, its concentration was determined spectrofluorometrically at λem = 357 nm with excitation at λex = 280 nm. The spectrofluorometry method gave a linear response for VA within the range 20.0–900.0 µg/L, with a correlation coefficient of 0.9982. The limit of detection and sorption capacity were 7.6 µg/L and 66.2 mg/g, respectively. The method was validated by comparing the obtained results with gas chromatographic data. This method was used to determine VA in Chenopodium album and Prangos asperula plants. Copyright © 2014 John Wiley & Sons, Ltd.
A web‐based method for building and simulating standard cell circuits—A classroom application
Authors: Beg Azam
Published: April 2014

The characterization of standard cells (basic digital blocks) is an iterative and arduous process. Our web‐based tool enables the students/users to quickly perform a large number of characterization experiments. The tool is useful for various courses on micro/nano‐electronics and circuit design, and eliminates the need for costly CAD‐software/hardware. © 2014 Wiley Periodicals, Inc. Comput Appl Eng Educ 23:304–313, 2015; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21600
Interactive computer modules for undergraduate chemical engineering instruction
Authors: Fogler H. Scott , Montgomery Susan M. , Zipp Robert P.
Published: April 2014

Interactive computer modules have been developed for four of the core courses in the Chemical Engineering curriculum: Introduction to Chemical Engineering, Fluids/Transport, Separations, and Kinetics. These modules generally consist of a review of the material, followed by an interactive problem‐solving session, which may include a computer simulation of the processes involved. The problem is often presented as part of a scenario, to capture the student's interest, and hints are available to guide the student. This study examines the components of these modules, as well as considerations that educators should take into account when developing interactive computer modules.
Multimedia‐based educational applications of computer simulations of chemical engineering processes
Authors: Squires R. G. , Andersen P. K. , Reklaitis G. V. , Jayakumar S. , Carmichael D. S.
Published: April 2014

A series of computer simulations of industrial chemical engineering processes designed to be used as senior chemical engineering laboratory “experiments” are being developed. Each company sponsor has also produced a 20‐minute videotape of the process so that students may “tour” the facilities. Four modules have been completed. Two additional modules are currently being developed. The distribution of all materials will be handled by CACHE. Although the modules were designed for use in the senior chemical engineering laboratory course, schools report success in applying the modules in other chemical engineering courses.
NSF/IEEE CAEME center: An exciting opportunity to align electromagnetic education with the nineties
Authors: Iskander Magdy F.
Published: April 2014

The National Science Foundation/Institute of Electrical and Electronic Engineers (NSF/IEEE) Center for Computer Applications in Electromagnetic (EM) Education (CAEME) was funded in early 1990 by the National Science Foundation to stimulate and accelerate the use of computers and software tools in EM education. The Center is managed by the Executive Office of IEEE on behalf of the Antennas and Propagation Society. This organizational structure provided avenues for broad participation by universities, professional societies, and corporations in the Center's activities. In two years of operation, CAEME has organized several workshops and special sessions in international meetings, published its first software book, prepared a lesson on “Electromagnetic Waves” using interactive video, and raised over $ 130,000 from university membership, participating societies, and corporate sponsors. This article summarizes CAEME activities, outlines its organizational structure, and briefly describes the contents of its first software book. Future developments are discussed and avenues for participation are outlined.
Visualization, simulation, and computing: New tools for learning, new paradigm for teaching
Authors: Cole Rodney , Brune Curtis
Published: April 2014

In this article we explore the role computing can play in an electromagnetics class. Our aim is not to provide answers, but to open a discussion on several topics related to the use of the computer as a learning aid. We provide some examples of what we have done in an introductory electricity and magnetism class using a program called SilverHammer that maps electric and magnetic fields for point charges. However, the point of this article is not to say that this is the only way computers should be used, but rather to point out that we really have only scratched the surface of a very versatile tool. Those who are presently working in this area are the pioneers, and will see the use of the computer go from these first applications to being an indispensable medium for learning. The computer may well let us create virtual scenarios that allow us to explore ideas and relationships with a heretofore unattained proficiency.
Computer use in a multidisciplinary control laboratory
Authors: Mastascusa Edward J. , Aburdene Maurice F.
Published: April 2014

This article describes a multidisciplinary control systems laboratory based on PCs with IEEE‐488 capability. The laboratory is used for courses in electrical engineering control systems, mechanical engineering control systems, and chemical engineering process control.
Interactive video: Innovative episodes for enhancing education
Authors: Bailey Harold J. , Thornton Nancy E.
Published: April 2014

This article provides information about the actual and potential uses of interactive video in instruction in an effort to motivate educators to consider using this technology to improve teaching. The authors (1) describe the continuing evolution of computer‐based educational tools; (2) examine instances when an interactive videodisc provides viable instructional solutions to otherwise very difficult or impossible tasks; (3) discuss several models for delivering instruction to accommodate different learning styles and teaching methods; and (4) provide a framework for designing lessons systematically based on proven methods.
A multimedia laboratory
Authors: El‐Sharkawy Mohamed
Published: April 2014

This paper describes multimedia work stations used in an undergraduate electrical engineering laboratory. The work stations are DSP96000 IBM PC‐based and are used for digital signal processing (DSP), speech processing, image processing, and graphics applications. The experiments conducted in two undergraduate courses are presented. The first is a one‐semester, three‐credit‐hour digital signal processing course and the second is a one‐semester, three‐credit‐hour senior design course.
Interactive analysis of propagation in optical fibers
Authors: Aicklen Gregory H. , Tamil Lakshman S.
Published: April 2014

We have developed a set of computer codes that compute the propagation constants and field patterns for the propagating modes of cylindrical optical fibers. From a simple set of finite difference equations, solutions of the scalar Helmholtz wave‐equation may be computed across a range of normalized frequencies to generate curves describing the dispersion characteristics of the fiber. Accurate cutoff frequencies for any mode can also be computed. We designed the computer codes around α‐index profiles since these profiles have been extensively covered in the literature, but our system also supports arbitrary profiles within the limits of the “small index gradient” and “weakly guiding” approximations. The computer codes are accurate and fast. They may be used interactively to explore dispersion in optical fibers and the effects of finite cladding width on dispersion.
Radio‐wave propagation and hypercard: A helpful link
Authors: Crampagne Raymond , Hélier Marc , Tabbara Walid
Published: April 2014

An educational software developed for an introduction to radio‐wave propagation is presented. Designed based on the model of a classical radio or microwave link, the software is based on the authoring system HyperCard and makes use of the animation capabilities provided by QuickTime. Tested in the frame of a continuing education program and attended by technicians and engineers involved in the practical aspects of propagation, it is a helpful tool for both the teacher and the student.
A new educational packet for passive and active filter design
Authors: Ruiz J. , Aramendi E. , Ubierna A.
Published: April 2014

A new software package for the design, analysis, and simulation of passive and active filters in cascade is presented. This article is mainly directed to engineering education. The software can also be used to aid in the filter design needed in industry. The main characteristic of this new software is based on several proposed alternatives in the design of passive filters.
Educational use of a microwave electromagnetic analysis of 3‐D planar structures
Authors: Rautio James C.
Published: April 2014

The use of an electromagnetic analysis of 3‐D planar structures is described with respect to the educational requirements of students from the college freshman level through the graduate level. The analysis is intended primarily for microwave use; however, there is also significant potential interest from the student of high speed digital design. The analysis is used for passive planar circuits with any number of layers. The third dimension is represented by vias. A mature graphical user interface is provided allowing rapid capture of structure geometry, color visualization, and animation of the resulting current distributions. The software is also explicitly designed to work in conjunction with popular circuit theory based microwave software and with SPICE.
Prototype expert system trouble‐shooter for the ANEX structural engineering teaching laboratory
Authors: Behr Richard A. , Benjamin Colin O. , Mirza Azam A.
Published: April 2014

This article describes the design and evaluation of a knowledge‐based expert system, called “TROUBLE‐SHOOTER,” developed for use in the newly developed “ANEX” undergraduate structural engineering teaching laboratory at the University of Missouri‐Rolla. ANEX is a portable, computer‐assisted mini‐laboratory that students use interactively to investigate correlations between computerized structural analyses and physical experiments performed on small‐scale model structures. TROUBLE‐SHOOTER was developed using LEVEL5 OBJECT® for Microsoft® Windows™ expert system shell. It is intended to act as a trouble‐shooter for various analytical and/or experimental problems that students could encounter during typical ANEX sessions.

An extensive three‐phase evaluation of the prototype expert system was performed, including an in‐house technical evaluation using 36 ANEX session test cases, a subjective evaluation by 16 civil engineering undergraduate students, and a controlled empirical evaluation to compare the prototype's speed and accuracy of advice with those provided by three experienced ANEX laboratory teaching assistants. Results of the evaluations indicated that the prototype expert system was well received by students; it was a competent trouble‐shooter and it provided advice quickly. Statistical results of the empirical evaluation revealed that the prototype expert system was significantly more accurate than were experienced teaching assistants in trouble‐shooting typical ANEX sessions. The prototype expert system was especially adept at handling ANEX test cases that were burdened with multiple analytical and/or experimental errors.
Teaching aids for electrical machines laboratory
Authors: Faiz Jawad , Ghasemzadeh S.
Published: April 2014

A personal computer software package has been recently developed in the electrical machines laboratory at Tabriz University. The package includes a set of computer programs that can be used alongside experiments, to assist students in learning the experimental aspects of electric machines.
CIG: A calorically imperfect compressible flow software element
Authors: Hodge B. K. , Koenig Keith
Published: April 2014

A compressible flow utility software element, CIG, for calorically imperfect gas flows is reviewed. CIG makes possible the routine computation of one‐dimensional isentropic flow, normal shock waves, and Prandtl‐Meyer processes for calorically imperfect gases. Details of the formulation, discussions of the numeric procedures, and examples of applications are provided. CIG is a useful software element both for introducing students in a first compressible flow course to the effects of the calorically perfect gas assumption and for providing more advanced students with useful applications software for calorically imperfect gas flows.
Solid modeling: A new approach to freshman graphics
Authors: Marlor Sheryl Sorby
Published: April 2014

A new course in computer aided drafting and design at the freshman and sophomore level is currently being offered at Michigan Technological University (MTU). The course is interdisciplinary in nature, with example problems taken from several engineering fields. This article discusses the course and the need for such a course in engineering education. Grading procedures and comments describing students' reactions to the course are also discussed.
Data acquisition tutor and programming interface
Authors: Guirguis Shawkat K.
Published: April 2014

In this article a tutoring system is presented to act as a platform for research students to study data acquisition. In addition, it could be used to program and operate an existing hardware setup. The hardware consists of a number of sensors attached to a programmable data logger, and collected data are transferred to a PC via a pair of short‐haul modems. The tutor exhibits the flexibility required to meet different needs of research students in information technology and environment‐related studies. In addition, it has the capability to act as a user‐friendly interface able to operate complex setups.
Enhancement of aerodynamics and flight dynamics instruction with interactive computer visualizations
Authors: Higuchi Hiroshi
Published: April 2014

Desktop (Macintosh) computers with multimedia capabilities have been incorporated into the aerospace engineering curriculum—in particular, in the laboratory and core courses on aerodynamics and flight dynamics. Through interactive simulation, visual presentation, and image and motion analysis techniques at different levels of complexity, the enhancement of classroom materials has been achieved to further students' understanding of the underlying principles.
TLINE: Software for sinusoidal steady‐state analysis of transmission lines
Authors: Iskander M. F. , Jensen E.
Published: April 2014

This article describes the use of the software package TLINE, which includes three programs for the sinusoidal steady‐state analysis of transmission lines. The first program provides analysis of the tandem connection of several transmission lines with the possibility of including PI, T, or L lumped‐element discontinuity junctions between the transmission lines. The other two programs are related to analysis of impedance matching using single and double stubs. All analysis procedures are graphically displayed on Smith charts. Output files that include numerical values of input impedances, values of time‐average powers, and reflection coefficients at various sections of a tandem transmission line system are included. The TLINE software package is used to train students on the use of the Smith chart and also to help in the teaching and demonstration of various transmission line and impedance‐matching concepts.
Teaching technique for internal forced convection flows through tubes cooled or heated by external natural convection. I. Horizontal orientation
Authors: Campo Antonio , Lacoa Ulises
Published: April 2014

This report is concerned with a distinct instructional technique that facilitates the teaching of laminar forced convection flow through a horizontal tube exposed to external natural convection. A simple one‐dimensional lumped‐based formulation enabled the determination of the mean bulk and wall temperature distributions of the internal fluid flow as well as the total rate of heat transfer between two axial stations in the region of thermal development. Streamwise‐mean values for the internal and circumferential‐mean values for the external Nusselt numbers have been taken from standard correlations reported in undergraduate textbooks on heat transfer, leading to the immediate calculation of a mean, equivalent Nusselt number, which serves to regulate the thermal interaction between the two fluid streams. Representative results for a complete combination of internal and external fluids, expressed in terms of their respective thermal conductivity ratios, are discussed at length. The thermal quantities were computed with a pocket‐size calculator and compared favorably with those based on a more general and rigorous two‐dimensional differential formulation. The latter was utilized as a baseline solution, and inevitably required a finite‐difference procedure on a personal computer.
Effect of atmospheric phenomena on satellite communications
Authors: Anitzine I. Fernández , Almazán R. Ibeas
Published: April 2014

In this article we describe the development of a C++ program for Windows designed to aid the setting up of a VSAT communications network. The network's purpose is to perform the relevant radio link calculations, taking into consideration aspects such as attenuation by atmospheric gases, clouds, rain, and cross polarization.
The significance of TK solver in problem solving
Authors: Ferguson R. J.
Published: April 2014

This article shows how TK Solver's unique ability to “backsolve” system of linear and nonlinear equations can contribute to condensing and clarifying problem solutions. Beyond this, TK can be used as a complete knowledge management environment in which equations, tabular data, and design rules are made easily accessible and usable.
The universal transformation matrix: Revealing the relationships among different graphical projection methods
Authors: Pas Eric I. , Vesilind P. Aarne
Published: April 2014

This article discusses the relationships among the different graphical projection techniques used by engineers and architects. These relationships are examined in the context of the transformation matrices that are employed to generate such projections on the computer. The report shows that the transformations that produce parallel (isometric and orthographic) and perspective projections can be derived as special cases of a transformation matrix that produces a three‐point perspective view. For this reason, the latter transformation matrix is referred to here as the “universal transformation matrix.” A better understanding of the different projection techniques, and the relationships among them, emerges from the recognition that all parallel and perspective transformations may be written as special cases of a single, general transformation matrix.
Classical control theory applied to potentially chaotic systems
Authors: Brogan William L.
Published: April 2014

Some nonlinear systems of order three or higher become chaotic for certain parameter values and initial conditions. Interesting examples have been discussed in recent years, using sophisticated mathematical analysis and/or simulation. This article presents a simple method of predicting if chaos is possible and under what conditions, using classical control theory tools such as Nyquist's stability theorem and describing functions. The method is demonstrated using several examples.
Development of engineering courseware for university undergraduate teaching using computer animation
Authors: Tan F.‐L. , Fok S.‐C.
Published: April 2014

Computer animation on personal computers (PC) is becoming increasingly popular as an educational teaching aid. With the increasing CPU power and high‐resolution graphics of PC, and the rapid evolution of animation softwares, engineering courses can be developed on the PC using computer animation. Many engineering systems and processes in the engineering courses can be animated to enhance learning by university undergraduates. These animation projects could be developed into engineering courseware on certain subjects or topics for effective teaching in classrooms, at home, or as computer‐aided laboratory lessons. Several types of animation software are introduced in this article.
Fortran 90 and the direct calculation of radiation view factors
Authors: Ribando Robert J. , Shi Qingping
Published: April 2014

The recent introduction of Fortran 90, along with constant increases in the speed of desktop personal computers, makes direct integration an extremely viable means of computing radiation view factors. Using the new intrinsic functions and simplified array operations which are part of the Fortran 90 standard, an algorithm based on discretization of the two surfaces can be implemented in fewer than a hundred lines of code and run in only a few seconds on a typical personal computer. The basics of such an algorithm for arbitrarily oriented flat parallelograms will be reviewed in this brief note.
Computerized nichols' chart for enhancing control design
Authors: Vibet C.
Published: April 2014

This article presents a versatile way to design Nichols' charts on small computers. First, this control problem is formulated in terms of open‐loop and closed‐loop transfer functions. Next, the plotting equations are solved by means of the Gnuplot version 3.0 program. When needed, the printing process is realized via an EMTEX postscript output provided by this program.
Computer solution of electrostatics problems using schwarz‐christoffel mapping technique
Authors: Oloomi Hossein M. , Badii Vahid
Published: April 2014

In this article we discuss the suitability of using a new MATLAB toolbox for teaching several undergraduate engineering courses. This toolbox, which is based on the Schwarz—Christoffel transformation of the complex variable theory, numerically solves the conformal mapping of many complex domains to the upper half‐plane. The toolbox allows a computer solution to many complex problems in areas such as electromagnetics and fluid mechanics. It is the purpose of this article to show the usefulness of this toolbox in introducing these advanced topics to the undergraduate students.
Introductory approach for variational methods
Authors: Gibson Andrew A. P. , Dillon Bernice M.
Published: April 2014

A variational property of lumped element electrical circuits can be conveniently used to introduce the variational solution of boundary value problems in electrical engineering. In the case of electrical circuits, the Euler equation is Kirchhoff's current or voltage law. Easily solvable, low‐order problems with graphic illustrations are generated without difficulty.
Development and application of MCAL tools for marine radar instruction
Authors: Guirguis S. , Korany E. , Abdel‐Bary A.
Published: April 2014

In this article a multimedia computer‐assisted learning (MCAL) system is presented. The major objective of this work was to investigate the potential of using such systems as tools for transferring instructional course information through various types of computer media as opposed to the classic CAL systems. The philosophy and techniques employed to design the system are investigated. Usage of the implemented system and its merits have been illustrated through its application to teach engineering students and technicians the theory and concepts of marine radar. System design, implementation, test, and revision phases are presented and discussed.
Student quizzing with computer‐projected images
Authors: Martin Peter T.
Published: April 2014

This article describes an innovative student quiz technique with projected laptop images. Students respond to the images in writing, and their answers are peer graded with a second “answer quiz.” The article provides step‐by‐step guides to quiz composition and execution, with a discussion of the method's advantages of immediacy, efficiency, and spontaneity.
N‐Terminal Modification of VEGF‐A C Terminus‐Derived Peptides Delineates Structural Features Involved in Neuropilin‐1 Binding and Functional Activity
Authors: Jia Haiyan , Aqil Rehan , Cheng Lili , Chapman Chris , Shaikh Shaheda , Jarvis Ashley , Chan A. W. Edith , Hartzoulakis Basil , Evans Ian M. , Frolov Antonina , Martin John , Frankel Paul , Djordevic Snezana , Zachary Ian C. , Selwood David L.
Published: April 2014

The interaction between VEGF‐A and its neuropilin (NRP) receptors mediates a number of important biological effects. NRP1 and the related molecule NRP2 are widely expressed on multiple tumour types and throughout the tumour vasculature, and are emerging as critical molecules required for the progression of angiogenic diseases. Given the increasing evidence supporting a role for NRP1 in tumour development, there is growing interest in developing inhibitors of NRP1 interactions with VEGF and its other ligands. In order to probe the interaction we synthesised a number of exon 7‐ and 8‐derived bicyclic peptides with N‐terminal lipophilic groups and found a simple N‐octanoyl derivative (EG00086) to be the most potent and functionally active. Detailed modelling studies indicated that new intramolecular hydrogen bonds were formed, stabilising the structure and possibly contributing to the potency. Removal of a salt bridge between D142 and R164 implicated in VEGF‐A binding to neuropilin‐1 had a minor effect on potency. Isothermal calorimetry was used to assess binding of EG00086 to NRP1 and NRP2, and the stability of the peptide in serum and in vivo was investigated. EG00086 is a potent blocker of VEGF‐promoted cellular adhesion to extracellular matrices, and phosphorylation of p130Cas contributes to this effect.
8‐Cyclopropyl‐2′‐Deoxyguanosine: A Hole Trap for DNA‐Mediated Charge Transport
Authors: Wong Jiun Ru , Shao Fangwei
Published: April 2014

DNA duplexes containing 8‐cyclopropyl‐2′‐deoxyguanosine (8CPG) were synthesized to investigate the effect of the C8‐modified deoxyguanosine as a kinetic trap for transient hole occupancy on guanines during DNA‐mediated hole transport (HT). Thermal denaturation and CD spectra show that DNA duplexes containing 8CPG are able to form stable B‐form duplexes. Photoirradiation of terminal tethered anthraquinone can induce oxidative decomposition of 8CPG through DNA HT along adenine tracts with lengths of up to 4.8 nm. Shallow and periodic distance dependence was observed in a long adenine tract with intervening guanines. The efficient charge transport indicates that 8CPG can electronically couple well with a DNA bridge and form HT‐active conformational domains to facilitate transient hole delocalization over an adenine tract.
Expanding the Binding Envelope of CYP51 Inhibitors Targeting Trypanosoma cruzi with 4‐Aminopyridyl‐Based Sulfonamide Derivatives
Authors: Vieira Debora F. , Choi Jun Yong , Roush William R. , Podust Larissa M.
Published: April 2014

Chagas disease is a chronic infection caused by the protozoan parasite Trypanosoma cruzi, manifested in progressive cardiomyopathy and/or gastrointestinal dysfunction. Therapeutic options to prevent or treat Chagas disease are limited. CYP51, the enzyme key to the biosynthesis of eukaryotic membrane sterols, is a validated drug target in both fungi and T. cruzi. Sulfonamide derivatives of 4‐aminopyridyl‐based inhibitors of T. cruzi CYP51 (TcCYP51), including the sub‐nanomolar compound 3, have molecular structures distinct from other validated CYP51 inhibitors. They augment the biologically relevant chemical space of molecules targeting TcCYP51. In a 2.08 Å X‐ray structure, TcCYP51 is in a conformation that has been influenced by compound 3 and is distinct from the previously characterized ground‐state conformation of CYP51 drug–target complexes. That the binding site was modulated in response to an incoming inhibitor for the first time characterizes TcCYP51 as a flexible target rather than a rigid template.
Evaluation of the Interaction between Phosphohistidine Analogues and Phosphotyrosine Binding Domains
Authors: McAllister Tom E. , Horner Katherine A. , Webb Michael E.
Published: April 2014

We have investigated the interaction of peptides containing phosphohistidine analogues and their homologues with the prototypical phosphotyrosine binding SH2 domain from the eukaryotic cell signalling protein Grb2 by using a combination of isothermal titration calorimetry and a fluorescence anisotropy competition assay. These investigations demonstrated that the triazole class of phosphohistidine analogues are capable of binding too, suggesting that phosphohistidine could potentially be detected by this class of proteins in vivo.
TiN@VN Nanowire Arrays on 3D Carbon for High‐Performance Supercapacitors
Authors: Pang Hongchang , Ee Shu Jing , Dong Yongqiang , Dong Xiaochen , Chen Peng
Published: April 2014

We hybridize core–shell‐structured metal‐nitride nanowires with a 3D carbon substrate. Such electrodes demonstrate a high volumetric capacitance and good cycling stability, owing to the synergistic integration of titanium nitride and vanadium nitride, as well as the vast surface area and conductive network provided by the microporous 3D carbon structure.
Highly Efficient Gold‐Catalyzed Synthesis of Dibenzocycloheptatrienes
Authors: Pflästerer Daniel , Rettenmeier Eva , Schneider Severin , de Las Heras Ruiz Edgar , Rudolph Matthias , Hashmi A. Stephen K.
Published: April 2014

Dibenzocycloheptatrienes are obtained by a gold‐catalyzed 7‐exo‐dig hydroarylation protocol in a highly efficient manner. The gold‐catalyzed reaction usually gives the products in high yields and excellent selectivity. This procedure provides an easy and efficient access to dibenzocycloheptanoids, which are an interesting and unique class of natural products. This was underlined by the first total synthesis of reticuol.
Disruptive chemical doping in a ferritin‐based iron oxide nanoparticle to decrease r2 and enhance detection with T1‐weighted MRI
Authors: Clavijo Jordan M. Veronica , Beeman Scott C. , Baldelomar Edwin J. , Bennett Kevin M.
Published: April 2014

Inorganic doping was used to create flexible, paramagnetic nanoparticle contrast agents for in vivo molecular magnetic resonance imaging (MRI) with low transverse relaxivity (r2). Most nanoparticle contrast agents formed from superparamagnetic metal oxides are developed with high r2. While sensitive, they can have limited in vivo detection due to a number of constraints with T2 or T2*‐weighted imaging. T1‐weighted imaging is often preferred for molecular MRI, but most T1‐shortening agents are small chelates with low metal payload or are nanoparticles that also shorten T2 and limit the range of concentrations detectable with T1‐weighting. Here we used tungsten and iron deposition to form doped iron oxide crystals inside the apoferritin cavity to form a WFe nanoparticle with a disordered crystal and un‐coupled atomic magnetic moments. The atomic magnetic moments were thus localized, resulting in a principally paramagnetic nanoparticle. The WFe nanoparticles had no coercivity or saturation magnetization at 5 K and sweeping up to ±20 000 Oe, while native ferritin had a coercivity of 3000 Oe and saturation at ±20 000 Oe. This tungsten–iron crystal paramagnetism resulted in an increased WFe particle longitudinal relaxivity (r1) of 4870 mm−1 s−1 and a reduced transverse relaxivity (r2) of 9076 mm−1 s−1 compared with native ferritin. The accumulation of the particles was detected with T1‐weighted MRI in concentrations from 20 to 400 nm in vivo, both injected in the rat brain and targeted to the rat kidney glomerulus. The WFe apoferritin nanoparticles were not cytotoxic up to 700 nm particle concentrations, making them potentially important for targeted molecular MRI. Copyright © 2014 John Wiley & Sons, Ltd.
Entrapment of a neutral Tm(III)‐based complex with two inner‐sphere coordinated water molecules into PEG‐stabilized vesicles: towards an alternative strategy to develop high‐performance LipoCEST contrast agents for MR imaging
Authors: Chahid Bochra , Vander Elst Luce , Flament Julien , Boumezbeur Fawzi , Medina Christelle , Port Marc , Muller Robert N. , Lesieur Sylviane
Published: April 2014

Chemical exchange saturation transfer (CEST) probes issued from the encapsulation of a water proton paramagnetic shift reagent into the inner aqueous volume of lipid vesicles provide an emerging class of frequency‐selective contrast agents with huge potential in the field of molecular magnetic resonance imaging (MRI). This work deals with the generation of such LipoCEST agents properly designed to optimize, under isotonic conditions, the chemical shift offset of the intra‐liposomal water protons as well as the number of exchangeable protons under reasonably low radiofrequency (RF) fields of saturation. The strategy lies in the loading of poly(ethylene glycol)‐stabilized nanosized liposomes with uncharged lanthanide chelates, binding more than one water molecule in the first hydration sphere, exemplified here by [Tm(III)–DO3A (H2O)2] complex. The key properties of the probes are demonstrated by complementary NMR investigations. The residence lifetime of the water molecules coordinated to the lanthanide center was outstandingly short (9.5 ± 0.2 ns from 17O NMR), and indeed relevant for effective LipoCEST responsiveness. The 1H NMR CEST spectra (7.01 T magnetic field) prove that the theoretically expected optimal sensitivity can be approximated in the nanomolar concentration range, at reasonably low RF presaturation pulses (6.7–12 μT) and saturation frequency offsets of the intra‐liposomal water protons beyond 10 ppm, making possible selective irradiation in biological environment. CEST‐MRI images (7.01 T magnetic field and 10–12 μT RF pulse) explicitly confirm the interest of these newly conceived LipoCEST agents, indeed among the most efficient ones developed so far under isosmotic conditions. Copyright © 2014 John Wiley & Sons, Ltd.
In vivo quantification of SPIO nanoparticles for cell labeling based on MR phase gradient images
Authors: Wang Luning , Potter William M. , Zhao Qun
Published: April 2014

Along with the development of modern imaging technologies, contrast agents play increasingly important roles in both clinical applications and scientific research. Super‐paramagnetic iron oxide (SPIO) nanoparticles, a negative contrast agent, have been extensively used in magnetic resonance imaging (MRI), such as in vivo labeling and tracking of cells. However, there still remain many challenges, such as in vivo quantification of SPIO nanoparticles. In this work, an MR phase gradient‐based method was proposed to quantify the SPIO nanoparticles. As a calibration, a phantom experiment using known concentrations (10, 25, 50, 100, 150 and 250 µg/ml) of SPIO was first conducted to verify the proposed quantification method. In a following in vivo experiment, C6 glioma cells labeled with SPIO nanoparticles were implanted into flanks of four mice, which were scanned 1–3 days post‐injection for in vivo quantification of SPIO concentration. The results showed that the concentration of SPIO nanoparticles could be determined in both phantom and in vivo experiments using the developed MR phase gradients approach. Copyright © 2014 John Wiley & Sons, Ltd.
Relaxivity enhancement of aquated Tris(β‐diketonate)gadolinium(III) chelates by confinement within ultrashort single‐walled carbon nanotubes
Authors: Law Justin J. , Guven Adem , Wilson Lon J.
Published: April 2014

Ultrashort single‐walled carbon nanotubes loaded with gadolinium ions (gadonanotubes) have been previously shown to exhibit extremely high T1‐weighted relaxivities (>100 mm−1 s−1). To further examine the effect of nanoconfinement on the relaxivity of gadolinium‐based contrast agents for magnetic resonance imaging, a series of ultrashort single‐walled carbon nanotube (US‐tube) materials internally loaded with gadolinium chelates have been prepared and studied. US‐tubes were loaded with Gd(acac)3 · 2H2O, Gd(hfac)3 · 2H2O, and Gd(thd)3 (acac = acetylacetone, hfac = hexafluoroacetylacetone, thd = tetramethylheptanedione). The longitudinal relaxivities of the prepared materials determined at 25°C in a 1.5 T field were 103 mm−1 s−1 for Gd(acac)3 · 2H2O@US‐tubes, 105 mm−1 s−1 for Gd(hfac)3 · 2H2O@US‐tubes and 26 mm−1 s−1 for Gd(thd)3@US‐tubes. Compared with the relaxivities obtained for the unloaded chelates (<10 mm−1 s−1) as well as accounting for the T1 reduction observed for the empty US‐tubes, the boost in relaxivity for chelate‐loaded US‐tubes is attributed to confinement within the nanotube and depends on the number of coordinated water molecules. Copyright © 2014 John Wiley & Sons, Ltd.
Computational modeling of vibration‐induced systemic hydration of vocal folds over a range of phonation conditions
Authors: Bhattacharya Pinaki , Siegmund Thomas
Published: April 2014

Predicting phonation conditions that are benign to voice health remains a biomechanically relevant problem. Our objective is to provide insight into vocal fold (VF) hydration based on continuum‐based VF models that are able to compute VF stresses during phonation and a scheme for the extraction and generalization of such computational data based on the principle of linear superposition. Because VF tissue is poroelastic, spatial gradients of VF hydrostatic stresses computed for a given phonation condition determine VF interstitial fluid flow. The present approach transforms, based on linear superposition principles, the computed interstitial fluid velocities at the particular phonation to those at an arbitrary phonation condition. Intersititial fluid flow characteristics for a range of phonation conditions are compared. For phonation conditions with no or moderate collision, no dehydration per vibration cycle is predicted throughout the VF. For more severe collision conditions, tissue dehydration is restricted to a region close to the glottal surface. Interstitial fluid displacement in the VF is found to be heterogeneous and strongly dependent on the phonation condition. A phonation condition is found to exist for which dehydration peaks. The proposed method significantly expands the scope and relevance of conducting isolated numerical simulations of VF vibration. Copyright © 2014 John Wiley & Sons, Ltd.
Occurrence and Implications of Voltage Reversal in Stacked Microbial Fuel Cells
Authors: An Junyeong , Lee Hyung‐Sool
Published: April 2014

Voltage reversal in stacked microbial fuel cells (MFCs) is a significant challenge that must be addressed, and the information on its definite cause and occurrence process is still obscure. In this work, we first demonstrated that different anodic reaction rates caused voltage reversal in a stacked MFC. Sluggish reaction rates on the anode in unit 1 of the stacked MFC resulted in a significantly increased anode overpotential of up to 0.132 V, as compared to negligible anode overpotential (0.0247 V) in unit 2. This work clearly verified the process of voltage reversal in the stacked MFC. As the current was gradually increased in the stacked MFC, the voltage in the stacked unit 1 decreased to 0 V prior to that of the stacked unit 2. Then, when the voltage in unit 1 became 0 V, it was converted from a galvanic cell to an electrochemical cell powered by unit 2. We found that the stacked unit 2 provided electrical energy for the stacked unit 1 as a power supply. Finally, the anode potential of the stacked unit 1 significantly increased over cathode potential as current increased further, which caused voltage reversal in unit 1. Voltage reversal occurs in stacked MFCs as a result of non‐spontaneous anode overpotential in a unit MFC that has sluggish anode kinetics compared to the other unit MFCs.
Validation of microsatellite multiplexes for parentage analysis and species discrimination in two hybridizing species of coral reef fish (Plectropomus spp., Serranidae)
Authors: Harrison Hugo B. , Feldheim Kevin A. , Jones Geoffrey P. , Ma Kayan , Mansour Hicham , Perumal Sadhasivam , Williamson David H. , Berumen Michael L.
Published: April 2014

Microsatellites are often considered ideal markers to investigate ecological processes in animal populations. They are regularly used as genetic barcodes to identify species, individuals, and infer familial relationships. However, such applications are highly sensitive the number and diversity of microsatellite markers, which are also prone to error. Here, we propose a novel framework to assess the suitability of microsatellite datasets for parentage analysis and species discrimination in two closely related species of coral reef fish, Plectropomus leopardus and P. maculatus (Serranidae). Coral trout are important fisheries species throughout the Indo‐Pacific region and have been shown to hybridize in parts of the Great Barrier Reef, Australia. We first describe the development of 25 microsatellite loci and their integration to three multiplex PCRs that co‐amplify in both species. Using simulations, we demonstrate that the complete suite of markers provides appropriate power to discriminate between species, detect hybrid individuals, and resolve parent–offspring relationships in natural populations, with over 99.6% accuracy in parent–offspring assignments. The markers were also tested on seven additional species within the Plectropomus genus with polymorphism in 28–96% of loci. The multiplex PCRs developed here provide a reliable and cost‐effective strategy to investigate evolutionary and ecological dynamics and will be broadly applicable in studies of wild populations and aquaculture brood stocks for these closely related fish species.
Comparing ecophysiological traits and evapotranspiration of an invasive exotic, Pinus halepensis in native woodland overlying a karst aquifer
Authors: Swaffer Brooke A. , Holland Kate L.
Published: April 2014

Invasion by exotic plant species into water‐limited environments has the potential to change the ecosystem water balance and may further exacerbate water scarcity issues. Here, we compared ecophysiological traits related to tree water use (sap flux, sapwood density, leaf and soil water potentials) and actual evapotranspiration (ETa) of the invasive Pinus halepensis to native tree and shrub species. We hypothesized that the invasive pine species would possess traits that are consistent with the potential to use more water than native species, which would be supported by higher ETa in areas invaded by pine. We found higher rates of sap flux for the invasive P. halepensis (5.5 cm h−1) per unit sapwood area compared with the native species (<3.5 cm h−1). In addition, P. halepensis sapwood was significantly less dense than the sapwood of the native species, suggesting higher sapwood conductivity facilitated the faster sap flux. Comparison of remotely sensed ETa before and after P. halepensis removal within a Eucalyptus camaldulensis stand demonstrated a reduction in ETa by an average of 50 (±11 SE) mm year−1 in the 2 years after removal, relative to the ETa from an undisturbed, intact E. camaldulensis stand. This study suggests that active management of this invasive species should reduce overall ETa losses and thereby exert a positive influence on the availability of soil moisture for groundwater recharge. Copyright © 2014 John Wiley & Sons, Ltd.
OX40 controls effector CD4+ T‐cell expansion, not follicular T helper cell generation in acute Listeria infection
Authors: Marriott Clare L. , Mackley Emma C. , Ferreira Cristina , Veldhoen Marc , Yagita Hideo , Withers David R.
Published: April 2014

To investigate the importance of OX40 signals for physiological CD4+ T‐cell responses, an endogenous antigen‐specific population of CD4+ T cells that recognise the 2W1S peptide was assessed and temporal control of OX40 signals was achieved using blocking or agonistic antibodies (Abs) in vivo. Following infection with Listeria monocytogenes expressing 2W1S peptide, OX40 was briefly expressed by the responding 2W1S‐specific CD4+ T cells, but only on a subset that co‐expressed effector cell markers. This population was specifically expanded by Ab‐ligation of OX40 during priming, which also caused skewing of the memory response towards effector memory cells. Strikingly, this greatly enhanced effector response was accompanied by the loss of T follicular helper (TFH) cells and germinal centres. Mice deficient in OX40 and CD30 showed normal generation of TFH cells but impaired numbers of 2W1S‐specific effector cells. OX40 was not expressed by 2W1S‐specific memory cells, although it was rapidly up‐regulated upon challenge whereupon Ab‐ligation of OX40 specifically affected the effector subset. In summary, these data indicate that for CD4+ T cells, OX40 signals are important for generation of effector T cells rather than TFH cells in this response to acute bacterial infection.
Uracil excision by endogenous SMUG1 glycosylase promotes efficient Ig class switching and impacts on A:T substitutions during somatic mutation
Authors: Dingler Felix A. , Kemmerich Kristin , Neuberger Michael S. , Rada Cristina
Published: April 2014

Excision of uracil introduced into the immunoglobulin loci by AID is central to antibody diversification. While predominantly carried out by the UNG uracil‐DNA glycosylase as reflected by deficiency in immunoglobulin class switching in Ung−/− mice, the deficiency is incomplete, as evidenced by the emergence of switched IgG in the serum of Ung−/− mice. Lack of switching in mice deficient in both UNG and MSH2 suggested that mismatch repair initiated a backup pathway. We now show that most of the residual class switching in Ung−/− mice depends upon the endogenous SMUG1 uracil‐DNA glycosylase, with in vitro switching to IgG1 as well as serum IgG3, IgG2b, and IgA greatly diminished in Ung−/−Smug1−/− mice, and that Smug1 partially compensates for Ung deficiency over time. Nonetheless, using a highly MSH2‐dependent mechanism, Ung−/−Smug1−/− mice can still produce detectable levels of switched isotypes, especially IgG1. While not affecting the pattern of base substitutions, SMUG1 deficiency in an Ung−/− background further reduces somatic hypermutation at A:T base pairs. Our data reveal an essential requirement for uracil excision in class switching and in facilitating noncanonical mismatch repair for the A:T phase of hypermutation presumably by creating nicks near the U:G lesion recognized by MSH2.