bluuebunny/crossref_metadata_2025_split huggingface dataset:
Membrane extraction of a new antibiotic (Shengjimycin): equilibrium and mass transfer analysis
Authors: Hossain Md M , Rothman Kam , Jiang Wei , Sun Chenghang 
Published: August 2011

AbstractBACKGROUND: During the last two decades, separations based on liquid membrane technology have been demonstrated to be a potentially attractive process for a large number of industrial separations. The advantages of this technology over the current separation processes allowed its commercialization in the area of chemical/environmental applications (for the removal of toxic metals). Efforts are being devoted to biotechnological processes where membrane extraction has an added advantage of improving the productivity by removing inhibitory product during its production cycle. In this article the applicability of a membrane extraction technique based on hollow‐fibre membrane modules is investigated to extract a new antibiotic, Shengjimycin (SJM). SJM is produced in a multicomponent fermentation broth, from which the main components required to be separated selectively.RESULTS: From equilibrium experiments, sunflower oil, a cheap and less toxic solvent, was found to be good for the extraction of SJM at its natural pH of 7.2–7.8. Addition of a small amount (1.5%) of Amberlite LA‐2 (a carrier) in the solvent could intensify the process to achieve a high distribution coefficient. The process using this organic phase (Amberlite LA‐2 in sunflower oil) gave good extraction (ca 70%) within 3–4 h in a pilot‐scale hollow‐fibre membrane module. This new system is preferred over the toxic solvents being used or tried because of its cost, less toxicity, low environmental impact and operator‐friendliness.CONCLUSIONS: Because of the above‐mentioned favourable characteristics this membrane extraction method has the potential to be sustainable and effective as it has shown selective separation of the desired component from a multicomponent mixture. Copyright © 2011 Society of Chemical Industry
Design of carbon nanotube fiber microelectrode for glucose biosensing
Authors: Zhu Zhigang , Garcia‐Gancedo Luis , Flewitt Andrew J. , Moussy Francis , Li Yali , Milne William I. 
Published: August 2011

AbstractBACKGROUND: Carbon nanotube (CNT) fiber directly spun from an aerogel has a unique, well‐aligned nanostructure (nano‐pore and nano‐brush), and thus provides high electro‐catalytic activity and strong interaction with glucose oxidase enzyme. It shows great potential as a microelectrode for electrochemical biosensors.RESULTS: Cyclic voltammogram results indicate that post‐synthesis treatments have great influence on the electrocatalytic activity of CNT fibers. Raman spectroscopy and electrical conductivity tests suggest that fibers annealed at 250 °C remove most of the impurities without damaging the graphite‐like structure. This leads to a nano‐porous morphology on the surface and the highest conductivity value (1.1 × 105 S m−1). Two CNT fiber microelectrode designs were applied to enhance their electron transfer behaviour, and it was found that a design using a 30 nm gold coating is able to linearly cover human physiological glucose level between 2 and 30 mmol L−1. The design also leads to a low detection limit of 25 µmol L−1.CONCLUSIONS: The high performance of CNT fibers not only offers exceptional mechanical and electrical properties, but also provides a large surface area and electron transfer pathway. They consequently make excellent bioactive microelectrodes for glucose biosensing, especially for potential use in implantable devices. Copyright © 2011 Society of Chemical Industry
Development of a hybrid neural network model to predict feeding method in fed‐batch cultivation for enhanced recombinant streptokinase productivity in Escherichia coli
Authors: Geethalakshmi Sundaresan , Narendran Sekar , Pappa Natarajan , Ramalingam Subramanian 
Published: August 2011

AbstractBACKGROUND: A simple and efficient model for enhancing production of recombinant proteins is essential for cost effective development of processes at industrial scale. A hybrid neural network (HNN) model is proposed combining an unstructured model and neural network to predict the feeding method for the post‐induction phase of fed‐batch cultivation for increased recombinant streptokinase activity in Escherichia coli.RESULTS: The parameters of the unstructured model were estimated from experiments conducted with various feeding methods. The simulated model described the dynamics of the process satisfactorily, however, its predictive capability of the process for different feeding methods is limited due to wide disparity in process parameters. In contrast, a neural network model trained to map the variations in process parameters to state variables complements the ‘first principle’ model in predicting the state variables effectively.CONCLUSIONS: The HNN model is able to predict the product profile for different substrate feed rates. Further, the average volumetric streptokinase activity predicted by the HNN model matches closely the experimental values for fed‐batches having high as well as low streptokinase activity. The HNN model developed in this study could facilitate development of a process for recombinant protein production with minimum number of experiments. Copyright © 2011 Society of Chemical Industry
First evidence of a cDNA encoding for a melatonin receptor (mel 1b) in brain, retina, and testis of Pelophylax esculentus
Authors: Serino Ismene , Izzo Gaia , Ferrara Diana , Minucci Sergio , d'Istria Michela 
Published: August 2011

AbstractMelatonin, nocturnally secreted by the pineal gland, regulates a variety of physiological functions, including reproduction. Here, we investigated the evidence of melatonin binding sites in frog tissue (brain, retina, and testis) through saturation and competition binding experiments. In the frog, Pelophylax esculentus, our results confirm the presence of a single class of melatonin‐specific binding sites in the brain and retina, but not in the testis. Further experiments have been done using biomolecular approaches (PCR analysis). Here, we report the isolation of a cDNA encoding for a melatonin receptor type (mel1b) from brain, retina, and testis of the P. esculentus. PCR analysis revealed that melatonin expression is higher in the brain and retina, whereas it is lower in the testis. The presence of a melatonin receptor transcript in the frog testis corroborates our previous results obtained in in vitro experiments that suggest that melatonin might act directly in male vertebrate gonads, and indicates that the frog testis may be a suitable model to verify the role of indolamine in testicular activity. J. Exp. Zool. 315:520–526, 2011. © 2011 Wiley Periodicals, Inc.
LESSONS FROM THE UNFINISHED AGENDA OF A SMALL DEVELOPING ECONOMY UNDER TRADE AND STRUCTURAL REFORMS
Authors: Mahadevan Renuka , Asafu‐Adjaye John 
Published: August 2011

AbstractThis article examines the issue of trade reforms confronting many African Caribbean and Pacific countries such as Fiji, which are set to lose their European Union sugar price subsidy at the end of 2007. It was found that attempts to offset the adverse impacts of the subsidy removal by targeting to improve the performance of any particular sector are counterproductive. Although the optimal policy for Fiji is a broad‐based diversification of exports, it is further argued that small developing economies need to address supply‐side constraints so that structural reforms can effectively sustain the economy's competitiveness in an increasingly globalised world economy. Copyright © 2011 John Wiley & Sons, Ltd.
A Simple Scheme for Grafting an Ion‐Imprinted Layer onto the Surface of Poly(propylene) Fibers
Authors: Li Tongyi , Wu Lei , Chen Shuixia , Li Haichao , Xu Xiuzhu 
Published: August 2011

AbstractA simple method for surface ion‐imprinting is described in which poly(glycidyl methacrylate) is grafted onto PP fibers to act as a binder to a Cu2+ ion‐imprinted polymer layer. Mechanical and thermal analysis shows excellent tensile and thermal properties of the ion‐imprinted fibers. Competitive adsorption of Cu2+ and other ions such as Zn2+, Ni2+, Cd2+, Mn2+, and Mg2+ on the fibes is examined and a highly selective adsorption of Cu2+ is observed. The selectivity coefficient for Cu2+ with respect to Cd2+ can be as high as 20.2. Dynamic adsorption results indicate that the fibers are able to thoroughly remove Cu2+ from a solution. Regeneration performance tests show that the fibers maintain almost the same adsorption capacity for copper ions after 10 adsorption/desorption cycles.magnified image
Thermally Curable Polyoxanorbornene by Ring Opening Metathesis Polymerization
Authors: Tasdelen Mehmet Atilla , Durmaz Hakan 
Published: August 2011

AbstractA novel norbornene monomer bearing a thermally curable benzoxazine group is synthesized and polymerized by ROMP using the Grubbs first‐generation ruthenium catalyst. The $\overline {M} _{{\rm w}} $ of the side‐chain benzoxazine functionalized polyoxanorbornene can be up to 87 000 Da with unimodal molecular‐weight distribution and narrow polydispersity between 1.18 and 1.65. Thermally activated ring‐opening polymerization of benzoxazine moieties leads to the formation of highly cross‐linked structures. The effects of molecular weight on the thermal ROP of polybenzoxazine precursors are examined.magnified image
Measurement Protocols for Reporting PEDOT Thin Film Conductivity and Optical Transmission: A Critical Survey
Authors: Fabretto Manrico , Zuber Kamil , Jariego‐Moncunill Carlos , Murphy Peter 
Published: August 2011

AbstractPEDOT is one of the most frequently studied conducting polymers in literature but values for optical transmission and electrical conductivity vary greatly. Therefore measurement protocols are examined and insights are suggested into why the protocols themselves may lead to differences. Reported PEDOT conductivity is the result of contact and non‐contact film thickness and four‐point probe measurements. The soft nature of PEDOT implies that any contact method must be executed with extreme care as values of conductivity ranging from 780 to 2 775 S · cm−1 can be obtained. Similarly, variations in the optical minimum, maximum, and transmission range are found based on different switching voltage protocols. The results present here highlight the need for explicitly stating the measurement protocol used.magnified image
Lp‐Liouville property for non‐local operators
Authors: Masamune Jun , Uemura Toshihiro 
Published: August 2011

AbstractThe Lp‐Liouville property of a non‐local operator \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathcal {A}$\end{document} is investigated via the associated Dirichlet form \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$({\mathcal E},{\mathcal F})$\end{document}. We will show that any non‐negative continuous \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}${\mathcal E}$\end{document}‐subharmonic function \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$f \in {\mathcal F}_{\rm loc} \cap L^p$\end{document} are constant under a quite mild assumption on the kernel of \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}${\mathcal E}$\end{document} if p ≥ 2. On the contrary, if 1 < p < 2, we need an additional assumption: either, the kernel has compact support; or f is Hölder continuous.
Thiol‐alkyne Chemistry for the Preparation of Micelles with Glycopolymer Corona: Dendritic Surfaces versus Linear Glycopolymer in Their Ability to Bind to Lectins
Authors: Kumar Jatin , Bousquet Antoine , Stenzel Martina H. 
Published: August 2011

AbstractA poly(tert‐butyl acrylate) (P(tBA)) with a glycodendric endfunctionality with eight glucose moieties was synthesised in four steps via a combination of esterification, thiol‐alkyne conjugation and hetero‐Diels–Alder (HDA) cycloaddition. A linear glycopolymer of similar size and composition was also synthesised in order to compare the protein binding characteristics of the polymer with glycodendritic endfunctionality to the linear glycol blockcopolymer. The two amphiphilic polymers were self‐assembled in water into micelles. These particles were then tested for their ability to bind to Concanavalin A (Con A). In a turbidity assay, the polymer glycodendron exhibited a significantly faster clustering rate to the lectin as compared to the linear glycopolymer. In a precipitation assay, it is found that significantly less glucose residue is required for binding per Con A for the polymer with the glycodendritic endfunctionality. magnified image
One‐step Electro‐spinning/netting Technique for Controllably Preparing Polyurethane Nano‐fiber/net
Authors: Hu Juanping , Wang Xianfeng , Ding Bin , Lin Jinyou , Yu Jianyong , Sun Gang 
Published: August 2011

AbstractElectro‐spinning/netting (ESN) as a cutting‐edge technique evokes much interest because of its ability in the one‐step preparation of versatile nano‐fiber/net (NFN) membranes. Here, a controllable fabrication of polyurethane (PU) NFN membranes with attractive structures, consisting of common electrospun nanofibers and two‐dimensional (2D) soap bubble‐like structured nano‐nets via an ESN process is reported. The unique nanoscaled NFN architecture can be finely controlled by regulating the solution properties and several ESN process parameters. The versatile PU nano‐nets comprising interlinked nanowires with ultrathin diameters (5–40 nm) mean that the NFN structured membranes possess several excellent characteristics, such as an extremely large specific surface area, high porosity and large stacking density, which would be particularly useful for applications in ultrafiltration, special protective clothing, ultrasensitive sensors, catalyst support and so on.magnified image
New Thiol‐Responsive Mono‐Cleavable Block Copolymer Micelles Labeled with Single Disulfides
Authors: Khorsand Sourkohi Behnoush , Schmidt Rolf , Oh Jung Kwon 
Published: August 2011

AbstractThiol‐responsive symmetric triblock copolymers having single disulfide linkages in the middle blocks (called mono‐cleavable block copolymers, ss‐ABP2) were synthesized by atom transfer radical polymerization in the presence of a disulfide‐labeled difunctional Br‐initiator. These brush‐like triblock copolymers consist of a hydrophobic polyacrylate block having pendent oligo(propylene oxide) and a hydrophilic polymethacrylate block having pendent oligo(ethylene oxide). Gel permeation chromatography and 1H NMR results confirmed the synthesis of well‐defined mono‐cleavable block copolymers and revealed that polymerizations were well controlled. Because of amphiphilic nature, these copolymers self‐assembled to form colloidally stable micelles above critical micellar concentration of 0.032 mg · mL−1. In response to reductive reactions, disulfides in thiol‐responsive micelles were cleaved. Atomic force microscopy and dynamic light scattering analysis suggested that the cleavage of disulfides caused dissociation of micelles to smaller‐sized assembled structures in water. Moreover, in a biomedical perspective, the mono‐cleavable block copolymer micelles are not cytotoxic and thus biocompatible. magnified image
Phase Behavior of Polymer‐Containing Systems: Recent Advances Through Computer Simulation
Authors: Binder Kurt , Müller M. , Vink R. L. C. 
Published: August 2011

AbstractComputer simulations dealing with the phase transitions and phase diagrams of polymer solutions, polymer mixtures, and polymers in heterogeneous environments are still a methodological challenge, since nontrivial structure occurs from the Angstrom‐scale of covalent chemical bonds to the micrometer scale in the resulting multiphase materials. A brief review of strategies that were developed to deal with these problems will be given, and a few highlights of recent results from the research groups of the authors will be described.magnified image
Accuracy of the cylinder approximation for susceptometric measurement of intravascular oxygen saturation
Authors: Li Cheng , Langham Michael C. , Epstein Charles L. , Magland Jeremy F. , Wu Jue , Gee James , Wehrli Felix W. 
Published: August 2011

AbstractSusceptometry‐based MR oximetry has previously been shown suitable for quantifying hemoglobin oxygen saturation in large vessels for studying vascular reactivity and quantification of global cerebral metabolic rate of oxygen utilization. A key assumption underlying this method is that large vessels can be modeled as long paramagnetic cylinders. However, bifurcations, tapering, noncircular cross‐section, and curvature of these vessels produce substantial deviations from cylindrical geometry, which may lead to errors in hemoglobin oxygen saturation quantification. Here, the accuracy of the “long cylinder” approximation is evaluated via numerical computation of the induced magnetic field from 3D segmented renditions of three veins of interest (superior sagittal sinus, femoral and jugular vein). At a typical venous oxygen saturation of 65%, the absolute error in hemoglobin oxygen saturation estimated via a closed‐form cylinder approximation was 2.6% hemoglobin oxygen saturation averaged over three locations in the three veins studied and did not exceed 5% for vessel tilt angles <30° at any one location. In conclusion, the simulation results provide a significant level of confidence for the validity of the cylinder approximation underlying MR susceptometry‐based oximetry of large vessels. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Three‐dimensional MRI with independent slab excitation and encoding
Authors: Eissa Amir , Wilman Alan H. 
Published: August 2011

AbstractThree‐dimensional MRI is typically performed with the same orientation for radiofrequency slab excitation and slab select phase encoding. We introduce independent slab excitation and encoding to create a new degree of freedom in three‐dimensional MRI, which is the angular relationship between the prescribed excitation volume and the voxel encoding grid. By separating the directions of slab excitation and slab phase encoding, the independent slab excitation and encoding method allows choice of optimal voxel orientation, while maintaining volume excitation based on anatomic landmarks. The method requires simple pulse sequence modifications and uses standard image reconstruction followed by removal of aliasing and image reformatting. The independent slab excitation and encoding method enables arbitrary oblique angle imaging using fixed voxel encoding gradients to maintain similar eddy current, concomitant field, or magnetic dipole effects independent of the oblique angle of excitation. We apply independent slab excitation and encoding to phase and susceptibility‐weighted imaging using fixed voxel encoding aligned with the main magnetic field to demonstrate its value in both standardizing and improving image contrast, when using arbitrary oblique imaging volumes. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Parallel traveling‐wave MRI: A feasibility study
Authors: Pang Yong , Vigneron Daniel B. , Zhang Xiaoliang 
Published: August 2011

AbstractTraveling‐wave magnetic resonance imaging utilizes far fields of a single‐piece patch antenna in the magnet bore to generate radio frequency fields for imaging large‐size samples, such as the human body. In this work, the feasibility of applying the “traveling‐wave” technique to parallel imaging is studied using microstrip patch antenna arrays with both the numerical analysis and experimental tests. A specific patch array model is built and each array element is a microstrip patch antenna. Bench tests show that decoupling between two adjacent elements is better than ‐26‐dB while matching of each element reaches ‐36‐dB, demonstrating excellent isolation performance and impedance match capability. The sensitivity patterns are simulated and g‐factors are calculated for both unloaded and loaded cases. The results on B sensitivity patterns and g‐factors demonstrate the feasibility of the traveling‐wave parallel imaging. Simulations also suggest that different array configuration such as patch shape, position and orientation leads to different sensitivity patterns and g‐factor maps, which provides a way to manipulate B1 fields and improve the parallel imaging performance. The proposed method is also validated by using 7T MR imaging experiments. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Virtual dye angiography: Flow visualization for MRI‐guided interventions
Authors: George Ashvin K. , Faranesh Anthony Z. , Ratnayaka Kanishka , Derbyshire J. Andrew , Lederman Robert J. , Hansen Michael S. 
Published: August 2011

AbstractIn magnetic resonance imaging‐guided cardiovascular interventional procedures, it is valuable to be able to visualize blood flow immediately and interactively in selected regions. In particular, it is useful to assess normal or pathological communications between specific heart chambers and vessels. Phase‐contrast velocity mapping is not suitable for this purpose as it requires too much data and is not capable of determining directly if blood originating in one location travels to a nearby location. This article presents a novel flow visualization method called virtual dye angiography that enables visualization of blood flow analogous to selective catheter angiography. The method uses two‐dimensional radio frequency pulses to achieve interactive, intermittent, targeted saturation of a localized region of the blood pool. The flow of the saturated spins is observed directly on real‐time images or, in an enhanced manner, using ECG synchronized background subtraction. The modular nature of the technique allows for easy and seamless integration into a real‐time, interactive imaging system with minimal overhead. We present initial results in animals and in a healthy human volunteer. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Blipped‐controlled aliasing in parallel imaging for simultaneous multislice echo planar imaging with reduced g‐factor penalty
Authors: Setsompop Kawin , Gagoski Borjan A. , Polimeni Jonathan R. , Witzel Thomas , Wedeen Van J. , Wald Lawrence L. 
Published: August 2011

AbstractSimultaneous multislice Echo Planar Imaging (EPI) acquisition using parallel imaging can decrease the acquisition time for diffusion imaging and allow full‐brain, high‐resolution functional MRI (fMRI) acquisitions at a reduced repetition time (TR). However, the unaliasing of simultaneously acquired, closely spaced slices can be difficult, leading to a high g‐factor penalty. We introduce a method to create interslice image shifts in the phase encoding direction to increase the distance between aliasing pixels. The shift between the slices is induced using sign‐ and amplitude‐modulated slice‐select gradient blips simultaneous with the EPI phase encoding blips. This achieves the desired shifts but avoids an undesired “tilted voxel” blurring artifact associated with previous methods. We validate the method in 3× slice‐accelerated spin‐echo and gradient‐echo EPI at 3 T and 7 T using 32‐channel radio frequency (RF) coil brain arrays. The Monte‐Carlo simulated average g‐factor penalty of the 3‐fold slice‐accelerated acquisition with interslice shifts is <1% at 3 T (compared with 32% without slice shift). Combining 3× slice acceleration with 2× inplane acceleration, the g‐factor penalty becomes 19% at 3 T and 10% at 7 T (compared with 41% and 23% without slice shift). We demonstrate the potential of the method for accelerating diffusion imaging by comparing the fiber orientation uncertainty, where the 3‐fold faster acquisition showed no noticeable degradation. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.