bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrokinetic Mobilities Characterization and Rapid Detection of Microorganisms in Glass Microchannels
Authors: Garza‐García L. D. , Pérez‐González V. H. , Pérez‐Sánchez O. A. , Lapizco‐Encinas B. H.
Published: January 2011

Microscale electrokinetic techniques have great potential for the separation and sorting of microorganisms, and could solve the need for rapid and early detection of pathogens in medical diagnostics and food safety applications. Presented here is the application of micro particle image velocimetry for the characterization of electrokinetic transport of three types of microorganisms: Escherichia coli, Ankistrodesmus spiralis, and Saccharomyces cerevisiae. The electrokinetic behavior of these microorganisms was characterized employing a straight glass microchannel and direct current electric fields (50–300 V cm–1). The effects of the type and size of microorganism, electric field magnitude, and suspending medium characteristics were analyzed. Additionally, electrokinetic differentiation was achieved when a sample containing a mixture of the three types of microorganisms was analyzed by generating an electropherogram in one minute, identifying that three different species were present. These results demonstrate that fast and effective detection, and differentiation of intact microorganisms can be achieved employing microscale electrokinetic techniques.
Analysis of Seed Quality and Drying Performance of a Multistage Countercurrent Sliding‐Bed Dryer
Authors: Pfeifer A. A. , Murata V. V. , Barrozo M. A. S.
Published: January 2011

The effect exerted by the number of stages (one, two, three, and four stages) of a countercurrent sliding‐bed dryer on the quality indices and drying performance of soybean seeds is evaluated by simulation. The two‐phase model is used to describe heat and mass transfer between air and soybean seeds. The constitutive model equations are taken from specific studies. The seed quality is determined based on germination and nonfissured seed indices obtained by empirical functions reported in the literature. The simulated results show that dividing the air mass flux and air velocity can produce a lower seed outlet temperature which may yield higher quality indices and better drying performance in multistage configurations.
Liquid/Liquid Slug Flow Capillary Microreactor
Authors: Ufer A. , Mendorf M. , Ghaini A. , Agar D. W.
Published: January 2011

The liquid‐liquid slug flow capillary microreactor offers an excellent mass transfer performance for extraction and biphasic reactions. In combination with a simple phase separator based on wettability discrimination between the two liquids, it provides a powerful tool for process intensification and microscale processing. By new visualization techniques, the interfacial surface and slug vortex structures dictating inter‐ and intraphase mass transfer have been revealed to be more complex than previously assumed. Suspending fine catalyst particles in one phase of a two‐phase slug flow is an effective technique for using heterogeneous catalysts in microreactors, owing to the very good mass transfer characteristics and because catalyst recovery becomes simply a matter of separating the catalyst carrier phase from the reaction medium. To exploit the performance attributes of capillary microreactors at higher throughputs, distributor and control strategies for parallelisation were developed to provide a flow distribution uniform to within 1 % or less.
A Label‐Free, Quadruplex‐Based Functional Molecular Beacon (LFG4‐MB) for Fluorescence Turn‐On Detection of DNA and Nuclease
Authors: Hu Dan , Huang Zhenzhen , Pu Fang , Ren Jinsong , Qu Xiaogang
Published: January 2011

We demonstrate a novel concept for the construction of a label‐free, quadruplex‐based functional molecular beacon (LFG4‐MB) by using G‐quadruplex motif as a substitute for Watson–Crick base pairing in the MB stem and a specific G‐quadruplex binder, N‐methyl mesoporphyrin IX (NMM) as a reporter. It shows high sensitivity in assays for UDG activity/inhibition and detection of DNA sequence based on the unique fluorescence increase that occurs as a result of the strong interaction between NMM and the folded quadruplex upon removal of uracil by UDG or displacement of block sequence by target DNA. The LFG4‐MB is simple in design, fast in operation and could be easily transposesd to other biological relevant target analysis by simply changing the recognition portion. The LFG4‐MB does not require any chemical modification for DNA, which offers the advantages of simplicity and cost efficiency and obviates the possible interference with the affinity and specificity of the MB as well as the kinetic behavior of the catalysts caused by the bulky fluorescent groups. More importantly, the LFG4‐MB offers great extent of freedom to tune the experimental conditions for the general applicability in bioanalysis.
A Macrocyclic Ligand as Receptor and ZnII‐Complex Receptor for Anions in Water: Binding Properties and Crystal Structures
Authors: Ambrosi Gianluca , Formica Mauro , Fusi Vieri , Giorgi Luca , Macedi Eleonora , Micheloni Mauro , Paoli Paola , Pontellini Roberto , Rossi Patrizia
Published: January 2011

Binding properties of 24,29‐dimethyl‐6,7,15,16‐tetraoxotetracyclo[19.5.5.05,8.014,17]‐1,4,9,13,18,21,24,29‐octaazaenatriaconta‐Δ5,8,Δ14,17‐diene ligand L towards ZnII and anions, such as the halide series and inorganic oxoanions (phosphate (Pi), sulfate, pyrophosphate (PPi), and others), were investigated in aqueous solution; in addition, the ZnII/L system was tested as a metal‐ion‐based receptor for the halide series. Ligand L is a cryptand receptor incorporating two squaramide functions in an over‐structured chain that connects two opposite nitrogen atoms of the Me2[12]aneN4 polyaza macrocyclic base. It binds ZnII to form mononuclear species in which the metal ion, coordinated by the Me2[12]aneN4 moiety, lodges inside the three‐dimensional cavity. ZnII‐containing species are able to bind chloride and fluoride at the physiologically important pH value of 7.4; the anion is coordinated to the metal center but the squaramide units play the key role in stabilizing the anion through a hydrogen‐bonding network; two crystal structures reported here clearly show this aspect. Free L is able to bind fluoride, chloride, bromide, sulfate, Pi, and PPi in aqueous solution. The halides are bound at acidic pH, whereas the oxoanions are bound in a wide range of pH values ranging from acidic to basic. The cryptand cavity, abundant in hydrogen‐bonding sites at all pH values, allows excellent selectivity towards Pi to be achieved mainly at physiological pH 7.4. By joining amine and squaramide moieties and using this preorganized topology, it was possible, with preservation of the solubility of the receptor, to achieve a very wide pH range in which oxoanions can be bound. The good selectivity towards Pi allows its discrimination in a manner not easily obtainable with nonmetallic systems in aqueous environment.
A Multistate Switchable [3]Rotacatenane
Authors: Barin Gokhan , Coskun Ali , Friedman Douglas C. , Olson Mark A. , Colvin Michael T. , Carmielli Raanan , Dey Sanjeev K. , Bozdemir O. Altan , Wasielewski Michael R. , Stoddart J. Fraser
Published: January 2011

Rotacatenanes are exotic molecular compounds that can be visualized as a unique combination of a [2]catenane and a [2]rotaxane, thereby combining both the circumrotation of the ring component (rotary motion) and the shuttling of the dumbbell component (translational motion) in one structure. Herein, we describe a strategy for the synthesis of a new switchable [3]rotacatenane and the investigation of its switching properties, which rely on the formation of tetrathiafulvalene (TTF) radical π‐dimer interactions—namely, the mixed‐valence state (TTF2)+. and the radical‐cation dimer state (TTF+.)2—under ambient conditions. A template‐directed approach, based on donor–acceptor interactions, has been developed, resulting in an improved yield of the key precursor [2]catenane, prior to rotacatenation. The nature of the binding between the [2]catenane and selected π‐electron‐rich templates has been elucidated by using X‐ray crystallography and UV/Vis spectroscopy as well as isothermal titration microcalorimetry. The multistate switching mechanism of the [3]rotacatenane has been demonstrated by cyclic voltammetry and EPR spectroscopy. Most notably, the radical‐cation dimer state (TTF+.)2 has been shown to enter into an equilibrium by forming the co‐conformation in which the two 1,5‐dioxynaphthalene (DNP) units co‐occupy the cavity of tetracationic cyclophane, thus enforcing the separation of TTF radical‐cation dimer (TTF+.)2. The population ratio of this equilibrium state was found to be 1:1. We believe that this research demonstrates the power of constructing complex molecular machines using template‐directed protocols, enabling us to make the transition from simple molecular switches to their multistate variants for enhancing information storage in molecular electronic devices.
Experimental and Theoretical Studies on the Magnetic Properties of Manganese(II) Compounds with Mixed Isocyanate and Carboxylate Bridges
Authors: Ma Yu , Bandeira Nuno A. G. , Robert Vincent , Gao En‐Qing
Published: January 2011

Two manganese(II) isocyanate complexes with different flexible zwitterionic dicarboxylate ligands, [Mn2(bcpp)(NCO)4]n (1; bcpp=1,3‐bis(N‐carboxylatomethyl‐4‐pyridinio)propane) and [Mn2(bcp)(NCO)4]n (2; bcp=bis(N‐carboxylatomethyl)‐4,4′‐bipyridinium, have been synthesized and characterized by X‐ray crystallography and magnetic measurements. Both compounds consist of two‐dimensional coordination layers in which uniform anionic chains with mixed (NCO)2(COO) triple bridges are cross‐linked by flexible cationic 4,4′‐trimethylenedipyridinium spacers. Magnetic studies revealed antiferromagnetic interactions through the triple bridges (J=−8.0 cm−1 (1) and J=−8.6 cm−1 (2)), which are stronger than those in the isoelectronic analogue (N3)2(COO). To complement the experimental data, periodic and finite‐cluster DFT and CASPT2 calculations were performed on the dimeric units of the (NCO)2(COO) and (N3)2(COO) mixed‐bridged systems to support the Heisenberg picture and stress the relative efficiency of the magnetic couplers. It was found that the isocyanate ligand plays a greater role in the conveyance of antiferromagnetic behavior than the azide counterpart, and that both pseudohalide bridges function cooperatively with the carboxylate group.
Topochemical Synthesis of Cobalt Oxide‐Based Porous Nanostructures for High‐Performance Lithium‐Ion Batteries
Authors: Li Cheng Chao , Yin Xiao Ming , Li Qiu Hong , Chen Li Bao , Wang Tai Hong
Published: January 2011

Two kinds of topochemical conversion routes from cobalt hydroxide precursors to cobalt oxide‐based porous nanostructures are presented: pyrolysis in air and hydrothermal treatment by the Kirkendall diffusion effect. These cobalt hydroxide precursors were synthesized by a simple hydrothermal approach with sodium acetate as mineralizer at 200 °C. Detailed proof indicates that the process of cobalt hydroxide precursor growth is dominated by a nucleation, dissolution, renucleation, growth, and exfoliation mechanism. By the topochemical conversion processes several Co3O4 nanostructures, such as cobalt oxide‐coated cobalt hydroxide carbonate nanowires, cobalt oxide nanotubes, hollow cobalt oxide spheres, and porous cobalt oxide nanowires, have been synthesized. The obtained Co3O4 nanostructures have also been evaluated as the anode materials in lithium‐ion batteries. It was found that the as‐prepared Co3O4 nanostructures exhibited high reversible capacity and good cycle performance due to their porous structure and small size.
Modeling the cis‐Oxo‐Labile Binding Site Motif of Non‐Heme Iron Oxygenases: Water Exchange and Oxidation Reactivity of a Non‐Heme Iron(IV)‐Oxo Compound Bearing a Tripodal Tetradentate Ligand
Authors: Company Anna , Prat Irene , Frisch Jonathan R. , Mas‐Ballesté Dr Ruben , Güell Mireia , Juhász Gergely , Ribas Xavi , Münck Dr Eckard , Luis Josep M. , Que Lawrence , Costas Miquel
Published: January 2011

The spectroscopic and chemical characterization of a new synthetic non‐heme iron(IV)‐oxo species [FeIV(O)(Me,HPytacn)(S)]2+ (2, Me,HPytacn=1‐(2′‐pyridylmethyl)‐4,7‐dimethyl‐1,4,7‐triazacyclononane, S=CH3CN or H2O) is described. Complex 2 was prepared by reaction of [FeII(CF3SO3)2(Me,HPytacn)] (1) with peracetic acid. Complex 2 bears a tetradentate N4 ligand that leaves two cis sites available for binding an oxo group and a second external ligand but, unlike the related iron(IV)‐oxo species with tetradentate ligands, it is remarkably stable at room temperature (t1/2>2 h at 288 K). Its ability to exchange the oxygen atom of the oxo ligand with water has been analyzed in detail by means of kinetic studies, and a mechanism is proposed on the basis of DFT calculations. Hydrogen‐atom abstraction from CH bonds and oxygen‐atom transfer to sulfides by 2 have also been studied. Despite its thermal stability, 2 proves to be a very powerful oxidant that is capable of breaking the strong CH bond of cyclohexane (bond dissociation energy=99.3 kcal mol−1).
Mimicking Photosynthetic Antenna‐Reaction‐Center Complexes with a (Boron Dipyrromethene)3–Porphyrin–C60 Pentad
Authors: Liu Jian‐Yong , El‐Khouly Mohamed E. , Fukuzumi Shunichi , Ng Dennis K. P.
Published: January 2011

A highly efficient functional mimic of the photosynthetic antenna‐reaction‐center complexes has been designed and synthesized. The model contains a zinc(II) porphyrin (ZnP) core, which is connected to three boron dipyrromethene (BDP) units by click chemistry, and to a C60 moiety using the Prato procedure. The compound has been characterized using various spectroscopic methods. The intramolecular photoinduced processes of this pentad have also been studied in detail with steady‐state and time‐resolved absorption and emission spectroscopic methods, both in polar benzonitrile and nonpolar toluene. The BDP units serve as the antennae, which upon excitation undergo singlet–singlet energy transfer to the porphyrin core. This is then followed by an efficient electron transfer to the C60 moiety, resulting in the formation of the singlet charge‐separated state (BDP)3–ZnP.+–C60.−, which has a lifetime of 476 and 1000 ps in benzonitrile and toluene, respectively. Interestingly, a slow charge‐recombination process (${k{{{\rm T}\hfill \atop {\rm CR}\hfill}}}$=2.6×106 s−1) and a long‐lived triplet charge‐separated state (${\tau {{{\rm T}\hfill \atop {\rm CS}\hfill}}}$=385 ns) were detected in polar benzonitrile by nanosecond transient measurements.
Selectivity among Two Lectins: Probing the Effect of Topology, Multivalency and Flexibility of “Clicked” Multivalent Glycoclusters
Authors: Cecioni Samy , Faure Sophie , Darbost Ulrich , Bonnamour Isabelle , Parrot‐Lopez Hélène , Roy Olivier , Taillefumier Claude , Wimmerová Michaela , Praly Jean‐Pierre , Imberty Anne , Vidal Sébastien
Published: January 2011

The design of multivalent glycoconjugates has been developed over the past decades to obtain high‐affinity ligands for lectin receptors. While multivalency frequently increases the affinity of a ligand for its lectin through the so‐called “glycoside cluster effect”, the binding profiles towards different lectins have been much less investigated. We have designed a series of multivalent galactosylated glycoconjugates and studied their binding properties towards two lectins, from plant and bacterial origins, to determine their potential selectivity. The synthesis was achieved through copper(I)‐catalysed azide–alkyne cycloaddition (CuAAC) under microwave activation between propargylated multivalent scaffolds and an azido‐functionalised carbohydrate derivative. The interactions of two galactose‐binding lectins from Pseudomonas aeruginosa (PA‐IL) and Erythrina cristagalli (ECA) with the synthesized glycoclusters were studied by hemagglutination inhibition assays (HIA), surface plasmon resonance (SPR) and isothermal titration microcalorimetry (ITC). The results obtained illustrate the influence of the scaffold’s geometry on the affinity towards the lectin and also on the relative potency in comparison with a monovalent galactoside reference probe.
Vapor‐ and Mechanical‐Grinding‐Triggered Color and Luminescence Switches for Bis(σ‐fluorophenylacetylide) Platinum(II) Complexes
Authors: Ni Jun , Zhang Xu , Wu Yu‐Hui , Zhang Li‐Yi , Chen Zhong‐Ning
Published: January 2011

Square‐planar bis(σ‐fluorophenylacetylide) platinum(II) complexes [Pt(Me3SiCCbpyCC‐SiMe3)(CCC6H4F)2] (CCC6H4F‐2 for 2, CCC6H4F‐3 for 3, and CCC6H4F‐4 for 4; Me3SiCCbpyCCSiMe3=5,5′‐bis(trimethylsilylethynyl)‐2,2′‐bipyridine) were prepared and were characterized by spectroscopic and luminescence studies, and X‐ray crystallography. The color and luminescence of crystalline complex 3 is specifically sensitive to CHCl3 vapor to afford 140–180 nm of luminescence vapochromic redshift, which is useful for specific detection of CHCl3 vapor. Complex 4 displays selective luminescence vapochromic properties to CH2Cl2 and CHCl3 vapors with a luminescence vapochromic shift response of ca. 150–200 nm. Interestingly, complexes 2–4 exhibit reversible, and naked‐eye perceivable, mechanical stimuli‐responsive color and luminescence changes. When solid species 2–4 are crushed gently or ground, the crystalline state is converted to an amorphous phase. Meanwhile, bright yellow‐orange luminescence in the crystalline species is converted to dark red under UV light irradiation with 100–160 nm of mechanochromic shift response. A vapochromic or mechanochromic cycle was monitored by dynamic variations in emission spectra and X‐ray diffraction (XRD) patterns. The halohydrocarbon vapor‐ or mechanical‐grinding‐triggered color and luminescence switches are most likely correlated to a shorted intermolecular Pt–Pt distance as that revealed in vapochromic species 4⋅0.5 CH2Cl2 by X‐ray crystallography, thus leading to an increased contribution from intermolecular Pt–Pt interaction as demonstrated by DTF computational studies.
Bioactive natural products and chirality
Authors: Mori Kenji
Published: January 2011

Mori's synthetic works on bioactive natural products in general and pheromones in particular started about 40 years ago to establish their absolute configurations and also to clarify their stereochemistry–bioactivity relationships. Results indicate that bioactive natural products are not always enantiomerically pure, and the stereochemistry–bioactivity relationships are not simple but complicated. For example, neither (R)‐ nor (S)‐sulcatol, the aggregation pheromone of an ambrosia beetle, is behaviorally bioactive, whereas their mixture is active. In the case of olean, the sex pheromone of the olive fruit fly, its (R)‐isomer is active against the males and the (S)‐isomer is active against the females. Recent synthesis of two new insect pheromones is discussed to illustrate the modern methods in enantioselective synthesis. Chirality, 2011. © 2011 Wiley‐Liss, Inc.
The search for a deterministic origin for the presence of nonracemic amino‐acids in meteorites: A computational approach
Authors: Vandenbussche Sophie , Reisse Jacques , Bartik Kristin , Lievin Jacques
Published: January 2011

Amino‐acid enantiomeric excesses (ee's) have been detected in different types of carbonaceous chondrites, all in favor of the L enantiomer. In this article, we discuss possible deterministic causes to the presence of these amino‐acid ee's in meteorites and evaluate in particular enantioselective photolysis by circularly polarized light (CPL). The electronic circular dichroism spectra of a set of amino‐ and hydroxy‐acids, all detected in chondritic matter but some with ee's and others without ee's, were calculated and compared. The spectra were calculated for the most stable conformation(s) of the considered molecules using quantum mechanical methods (density functional theory). Our results suggest that CPL photolysis in the gas phase was perhaps not at the origin of the presence of ee's in meteorites and that the search for another, but still unknown, deterministic cause must be seriously undertaken. Chirality, 2011. © 2011 Wiley‐Liss, Inc.
Chiral separation of D,L‐mandelic acid through cellulose membranes
Authors: Ma Chao , Xu Xiao‐Lin , Ai Ping , Xie Sheng‐Ming , Lv Ying‐Chun , Shan Hai‐Qin , Yuan Li‐Ming
Published: January 2011

This work reports the chiral separation of D,L‐mandelic acid with cellulose membranes. Cellulose was chosen as membrane material because it possesses multichiral carbon atoms in its molecular structure unit. The flux and permselective properties of membrane using aqueous solutions of D,L‐mandelic acid as feed solution was studied. The top surface and cross‐section morphology of the resulting membrane were examined by scanning electron microscopy. When the membrane was prepared with 8.1 wt % cellulose and 8.1 wt % LiCl in the DMA casting solution, and the operating pressure and feed concentration of racemate were 0.0125 MPa and 0.5 mg/ml, respectively, over 90% of enantiomeric excess could be obtained. This is the first report that the cellulose membrane is used for isolating the optical isomers of D,L‐mandelic acid. Chirality, 2011. © 2011 Wiley‐Liss, Inc.
Nitrooxyacyl Derivatives of Salicylic Acid: Aspirin‐Like Molecules that Covalently Inactivate Cyclooxygenase‐1
Authors: Cena Clara , Tosco Paolo , Marini Elisabetta , Lazzarato Loretta , Piccinini Marco , Ramondetti Cristina , Lupino Elisa , Fruttero Roberta , Gasco Alberto
Published: January 2011

A recently described series of nitrooxyacyl derivatives of salicylic acid, displaying aspirin‐like anti‐inflammatory and platelet anti‐aggregatory properties, were evaluated for their abilities to inhibit cyclooxygenase (COX). A number of these compounds irreversibly inhibited both COX‐1 and COX‐2 isoforms when tested in isolated human platelets and monocytes. Further studies using COX‐1 expressed in human HEK293T cells showed that this inhibition mechanism is similar to that of aspirin; namely, the products are able to covalently bind to the Ser 530 residue present in the active cleft of the enzyme. Molecular modeling enabled us to rationalize this behavior. Because these products were previously found to display NO‐dependent properties in rat animal models, particularly as they decreased in vivo gastrotoxicity and induced in vitro vasodilation, they represent a new and interesting class of potential aspirin‐like antithrombotic agents worthy of further study.
24‐Hour Fasting with Diabetes: guide to physicians advising patients on medication adjustments prior to religious observances (or outpatient surgical procedures)
Authors: Grajower Martin M.
Published: January 2011

Patients with diabetes may undergo an approximately 24‐h fast for a voluntary religious observance or in preparation for a medical procedure. Commonly, patients will manage their diabetes before and during such fasting without guidelines from their doctors, often because they did not ask for advice. The physician should therefore take the lead in advising patients how to fast safely, in order to avoid the situation wherein the patient manages medication changes on his/her own. Furthermore, it sends a message to the patient that having diabetes does not preclude living a reasonably ‘normal’ life, even when it comes to religious observances. Copyright © 2011 John Wiley & Sons, Ltd.
The First Total Synthesis of Topsentolide B3
Authors: Sreedhar Eppakayala , Venkanna Arramshetti , Chandramouli Nagula , Babu K. Suresh , Rao Janaswamy Madhusudana
Published: January 2011

The first total synthesis of the cytotoxic oxylipin Topsentolide B3 has been accomplished in 15 steps with an overall yield of 24 %. Starting with readily available cis‐butene diol as a synthon, the synthesis involved Marouka allylation and Sharpless hydroxylation for the construction of three asymmetric centers. The nine‐membered lactone ring was built through a selective Grubbs ring‐closing metathesis reaction. Other key steps in the synthesis are CuI‐mediated alkynylation and Swern oxidation reactions. This provides a unique approach to the synthesis of oxylipins and offers the advantages of brevity and relatively high overall yield.
2′‐Deoxy‐2′‐α‐C‐(hydroxymethyl)adenosine as Potential anti‐HCV Agent
Authors: Chavain Natascha , Herdewijn Piet
Published: January 2011

Because of the importance of C‐branched nucleosides in the discovery of new antiviral molecules, we decided to synthesize 2′‐deoxy‐2′‐α‐C‐(hydroxymethyl)adenosine as a potential anti‐HCV agent. The synthesis of a new adenosine analogue following two different synthetic routes is described. The new C‐branched nucleoside was tested for its antiviral activity and found to be inactive.
The potential of white‐rot fungi to degrade phorbol esters of Jatropha curcas L. seed cake
Authors: de Barros Cândida R. M. , Ferreira Luis M. M. , Nunes Fernando M. , Bezerra Rui M. F. , Dias Albino A. , Guedes Cristina V. , Cone John W. , Marques Guilhermina S. M. , Rodrigues Miguel A. M.
Published: January 2011

The potential of solid‐state cultivation, with three white‐rot fungi (Bjerkandera adusta, Ganoderma resinaceum and Phlebia rufa), to decrease phorbol esters concentration of Jatropha curcas L. was evaluated in this study. Incubation was conducted in 250 mL Erlenmeyer flasks without agitation at 28°C for 30 days. Phorbol esters were analyzed by reverse‐phase HPLC after an extraction procedure using dichloromethane. All fungi studied were able to decrease the concentration of phorbol esters, mainly B. adusta and P. rufa which significantly reduced (p<0.05) phorbol esters contents to non‐toxic levels. These results suggest that white‐rot fungi could be potentially used as a possible approach for the biological treatment of the oilseed cake.
Assessment of the backflashover occurrence rate on HV transmission line towers
Authors: Sarajcev Petar , Goic Ranko
Published: January 2011

An assessment of the backflashover occurrence rate on the high voltage (HV) transmission line towers is presented in this paper. It is based on a mathematical model that accounts for the transmission line geometry, keraunic level, statistical distribution of lightning current parameters, and correlation between statistical variables defining the lightning current waveshape. Furthermore, assessment of the backflashover occurrence rate on these towers accounts for the tower footing impulse resistance, lightning impulse insulation strength of the insulator strings and surge impedance of the tower itself. Proposed theoretical analysis is backed by the most recent propositions of parameters that define statistical distributions of lightning current parameters and then applied to the typical HV transmission line example. This analysis might be useful when scrutinizing the several first transmission line towers incoming to the HV substations. Hence, here presented analysis could be subsequently applied for the design of the HV substation overvoltage protection. Finally, a sensitivity analysis is provided, in regards to the parameters of the log‐normal distributions defining lightning current amplitude and steepness, as well as in regards to the tower footing impulse resistance. Copyright © 2011 John Wiley & Sons, Ltd.
Shape‐memory anchoring system for bladder sensors
Authors: Pereira Iaci M. , Axisa Fabrice , Oréfice Rodrigo L. , Vanfleteren Jan , Neves Hercules P.
Published: January 2011

In this work, we propose the use of shape‐memory polymer as an anchoring system for a bladder sensor. The anchoring system was designed from a biomedical biodegradable water‐based poly(ester‐urethane) produced in an aqueous environment by using isophorone diisocyanate/hydrazine (hard segment) and poly(caprolactone diol)/2,2‐bis (hydroxymethyl) propionic acid (soft segment) as the main reagents. Tensile strength and elongation‐at‐break deterioration upon degradation in synthetic urine were investigated. In‐body shape recovery was simulated and measured in synthetic urine. Results indicated that shape recovery can occur at body temperature and expulsion of the sensor by the body along with urine may occur through the combined effect of urine hydrolytic attack and compression exerted by the bladder walls. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Development, validation, and results of a measure of 30‐day readmission following hospitalization for pneumonia
Authors: Lindenauer Peter K. , Normand Sharon‐Lise T. , Drye Elizabeth E. , Lin Zhenqiu , Goodrich Katherine , Desai Mayur M. , Bratzler Dale W. , O'Donnell Walter J. , Metersky Mark L. , Krumholz Harlan M.
Published: January 2011

BACKGROUND:

Readmission following hospital discharge has become an important target of quality improvement.

OBJECTIVE:

To describe the development, validation, and results of a risk‐standardized measure of hospital readmission rates among elderly patients with pneumonia employed in federal quality measurement and efficiency initiatives.

DESIGN:

A retrospective cohort study using hospital and outpatient Medicare claims from 2005 and 2006.

SETTING:

A total of 4675 hospitals in the United States.

PATIENTS:

Medicare beneficiaries aged >65 years with a principal discharge diagnosis of pneumonia.

INTERVENTION:

None.

MEASUREMENTS:

Hospital‐specific, risk‐standardized 30‐day readmission rates calculated as the ratio of predicted‐to‐expected readmissions, multiplied by the national unadjusted rate. Comparison of the areas under the receiver operating curve (ROC) and measurement of correlation coefficient in development and validation samples.

RESULTS:

The development sample consisted of 226,545 hospitalizations at 4675 hospitals, with an overall unadjusted 30‐day readmission rate of 17.4%. The median risk‐standardized hospital readmission rate was 17.3%, and the odds of readmission for a hospital one standard deviation above average was 1.4 times that of a hospital one standard deviation below average. Performance of the medical record and administrative models was similar (areas under the ROC curve 0.59 and 0.63, respectively) and the correlation coefficient of estimated state‐specific standardized readmission rates from the administrative and medical record models was 0.96.

CONCLUSIONS:

Rehospitalization within 30 days of treatment for pneumonia is common, and rates vary across hospitals. A risk‐standardized measure of hospital readmission rates derived from administrative claims has similar performance characteristics to one based on medical record review. Journal of Hospital Medicine 2010. © 2010 Society of Hospital Medicine
A Model for Flow‐enhanced Nucleation Based on Fibrillar Dormant Precursors
Authors: Roozemond Peter C. , Steenbakkers Rudi J. A. , Peters Gerrit W. M.
Published: January 2011

A model for flow‐enhanced nucleation is presented based on the concept of a polymer melt containing a fixed number of nucleation precursors with a fixed size distribution. Depending on the size, precursors can either be active (i.e. susceptible to nucleation, the characteristic time scale of which is governed by the deformation rate) and grow into a spherulite or remain dormant. The size distribution of precursors is derived by combining nucleation theory and experimentally determined quiescent spherulite number densities. Longitudinal precursor growth, causing activation of dormant precursors, is a function of molecular deformation: the stretch of high molecular weight chains. Both the eXtended Pom‐Pom and the Rolie‐Poly model are tested to calculate the molecular deformation. A quantitative agreement is found between simulations and experimental results.

magnified image
Complex behavioral and synaptic effects of dietary branched chain amino acids in a mouse model of amyotrophic lateral sclerosis
Authors: Venerosi Aldina , Martire Alberto , Rungi Angela , Pieri Massimo , Ferrante Antonella , Zona Cristina , Popoli Patrizia , Calamandrei Gemma
Published: January 2011

Scope: We hypothesized that chronic supplementation with branched chain amino acids (BCAAs) affects neurobehavioral development in vulnerable gene backgrounds.

Methods and results: A murine model of amyotrophic lateral sclerosis (ALS), G93A mice bearing the mutated human superoxide dismutase 1 (SOD1) gene, and control mice received from 4 to 16 wk of age dietary supplementation with BCAAs at doses comparable to human usage. Motor coordination, exploratory behaviors, pain threshold, synaptic activity and response to glutamatergic stimulation in primary motor cortex slices were evaluated between the 8th and 16th week. The glial glutamate transporter 1 (GLT‐1) and metabotropic glutamate 5 receptor (mGlu5R) were analyzed by immunoblotting in cortex, hippocampus and striatum. BCAAs induced hyperactivity, decreased pain threshold in wild‐type mice and exacerbated the motor deficits of G93A mice while counteracting their abnormal pain response. Electrophysiology on G93A brain slices showed impaired synaptic function, reduced toxicity of GLT‐1 blocking and increased glutamate toxicity prevented by BCAAs. Immunoblotting indicated down‐regulation of GLT‐1 and mGlu5R in G93A, both effects counteracted by BCAAs.

Conclusion: These results, though not fully confirming a role of BCAAs in ALS‐like etiology in the genetic model, clearly indicate that BCAAs' complex effects on central nervous system depend on gene background and raise alert over their spread use.
Spectral analysis of nonlocal regularization in two‐dimensional finite element models
Authors: Lu Xilin , Bardet Jean‐Pierre , Huang Maosong
Published: January 2011

Strain‐softening in geomaterials often leads to ill‐posed boundary‐valued problems (BVP), which cannot be solved with finite element methods without introducing some kind of regularization such as nonlocal plasticity. Hereafter we propose to apply spectral analysis for testing the performance of nonlocal plasticity in regularizing ill‐posed BVP and producing mesh‐independent solutions when local plasticity usually fails. The spectral analysis consists of examining the eigenvalues and eigenvectors of the global tangential stiffness matrix of the incremental equilibrium equations. Based on spectral analysis, we propose a criterion for passing or failing the test of constitutive regularization in the context of BVP. If the eigenvalues of the tangential operator are all positive then the regularization succeeds, otherwise it fails and may not prevent artificial mesh‐dependent solutions from appearing. The approach is illustrated in the particular case of a biaxial compression with strain‐softening plasticity. In this particular case, local softening plasticity is found to produce negative eigenvalues in the tangential stiffness matrix, which indicates ill‐posed BVP. In contrast, nonlocal softening plasticity always produces positive eigenvalues, which regularizes ill‐posed BVP. The dominant eigenvectors, which generate localized deformation patterns, have a bandwidth independent of mesh size, provided that the mesh is fine enough to capture localization. These mesh‐independent eigenmodes explain why nonlocal plasticity produces numerical solutions that are mesh‐independent. Copyright © 2011 John Wiley & Sons, Ltd.
BUREAUCRATS AS PURCHASERS OF HEALTH SERVICES: LIMITATIONS OF THE PUBLIC SECTOR FOR CONTRACTING
Authors: Zaidi Shehla , Mayhew Susannah H , Palmer Natasha
Published: January 2011

Contracting out of health services increasingly involves a new role for governments as purchasers of services. To date, emphasis has been on contractual outcomes and the contracting process, which may benefit from improvements in developing countries, has been understudied. This article uses evidence from wide scale NGO contracting in Pakistan and examines the performance of government purchasers in managing the contracting process; draws comparisons with NGO managed contracting; and identifies purchaser skills needed for contracting NGOs. We found that the contracting process is complex and government purchasers struggled to manage the contracting process despite the provision of well‐designed contracts and guidelines. Weaknesses were seen in three areas: (i) poor capacity for managing tendering; (ii) weak public sector governance resulting in slow processes, low interest and rent seeking pressures; and (iii) mistrust between government and the NGO sector. In comparison parallel contracting ventures managed by large NGOs generally resulted in faster implementation, closer contractual relationships, drew wider participation of NGOs and often provided technical support. Our findings do not dilute the importance of government in contracting but front the case for an independent purchasing agency, for example an experienced NGO, to manage public sector contracts for community based services with the government role instead being one of larger oversight. Copyright © 2011 John Wiley & Sons, Ltd.
Down‐regulation of oestrogen receptor‐β associates with transcriptional co‐regulator PATZ1 delocalization in human testicular seminomas
Authors: Esposito Francesco , Boscia Francesca , Franco Renato , Tornincasa Mara , Fusco Alfredo , Kitazawa Sohei , Looijenga Leendert H , Chieffi Paolo
Published: January 2011

Oestrogen exposure has been linked to a risk for the development of testicular germ cell cancers. The effects of oestrogen are now known to be mediated by oestrogen receptor‐α (ERα) and ERβ subtypes, but only ERβ has been found in human germ cells of normal testis. However, its expression was markedly diminished in seminomas, embryonal cell carcinomas and mixed germ cell tumours, but remains high in teratomas. PATZ1 is a recently discovered zinc finger protein that, due to the presence of the POZ domain, acts as a transcriptional repressor affecting the basal activity of different promoters. We have previously described that PATZ1 plays a crucial role in normal male gametogenesis and that its up‐regulation and mislocalization could be associated with the development of testicular germ cell tumours. Here we show that ERβ interacts with PATZ1 in normal germ cells, while down‐regulation of ERβ associates with transcriptional co‐regulator PATZ1 delocalization in human testicular seminomas. In addition, we show that the translocation of PATZ1 from the cytoplasm into the nucleus is regulated by cAMP, which also induces increased expression and nuclear localization of ERβ, while this effect is counteracted by using the anti‐oestrogen ICI 182‐780. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Screening for trisomies in dichorionic twins by measurement of fetal nuchal translucency thickness according to the mixture model
Authors: Wright David , Syngelaki Argyro , Staboulidou Ismini , Jesus Cruz Jader de , Nicolaides Kypros H.
Published: January 2011

Objective

To examine the distribution of fetal nuchal translucency (NT) thickness in dichorionic twins and investigate the effect of the correlation between NT measurements in each twin pair on the performance of screening for trisomies.

Methods

The distribution of fetal NT for crown–rump length (CRL) was examined in 5646 dichorionic twin pregnancies, including 103 with fetal trisomies 21, 18 or 13. The correlation in fetal NT in each euploid twin pregnancy was estimated.

Results

The distribution of NT in both euploid and trisomic fetuses was consistent with the mixture model in singleton pregnancies. In the euploid pregnancies, there was a correlation in log NT measurements in each twin pair (r = 0.42, 95% CI: 0.39–0.45) and, after removal of the effect of the operator, this correlation was reduced to 0.34. Allowing for this correlation in risk assessment for trisomies had a major impact on the estimated patient‐specific risk but had little effect on the overall performance of screening.

Conclusions

In dichorionic twin pregnancies, the mixture model of distributions of NT can be applied as in singletons. In screening for trisomies, the correlation in NT measurements between the fetuses should be taken into account in the estimation of patient‐specific risks. Copyright © 2011 John Wiley & Sons, Ltd.
Current practices in determining amnionicity and chorionicity in multiple gestations
Authors: Wan Jennifer J. , Schrimmer David , Taché Véronique , Quinn Kristen , Lacoursiere D. Yvette , James Gina , Benirschke Kurt , Pretorius Dolores H.
Published: January 2011

Objective

To evaluate the accuracy of amnionicity and chorionicity (A/C) diagnosis of referral physicians and a tertiary care center as compared to histopathologic diagnosis.

Method

A retrospective study of 289 multi‐fetal gestations was performed comparing A/C diagnoses of referring physicians, a tertiary care center, and histopathology.

Results

Two hundred and eighty‐nine multi‐fetal pregnancies were referred for evaluation; only 43.6% (126/289) carried an accurate diagnosis of A/C before tertiary care center evaluation. The tertiary care center accurately identified A/C in 94.8% (274/289) overall and 100% in first trimester twins and triplets. Referrals with an unspecified A/C diagnosis included 46.1% (113/245) twins and 64.1% (25/39) triplets.

Conclusion

Accurate diagnosis of A/C can be obtained by the early assessment of key sonographic findings. Referral providers are less accurate at determining A/C of mutifetal gestation when compared to a tertiary center, suggesting that an emphasis should be placed on enhancing these diagnostic skills in the general community or encouraging referral when diagnosis is ambiguous. Copyright © 2011 John Wiley & Sons, Ltd.
Greenhouse gas emissions associated with photovoltaic electricity from crystalline silicon modules under various energy supply options
Authors: Reich N.H. , Alsema E.A. , van Sark W.G.J.H.M. , Turkenburg W.C. , Sinke W.C.
Published: January 2011

The direct and indirect emissions associated with photovoltaic (PV) electricity generation are evaluated, focussing on greenhouse gas (GHG) emissions related to crystalline silicon (c‐Si) solar module production. Electricity supply technologies used in the entire PV production chain are found to be most influential. Emissions associated with only the electricity‐input in the production of PV vary as much as 0–200 g CO2‐eq per kWh electricity generated by PV. This wide range results because of specific supply technologies one may assume to provide the electricity‐input in PV production, i.e., whether coal‐, gas‐, wind‐, or PV‐power facilities in the “background” provide the electricity supply for powering the entire PV production chain. The heat input in the entire PV production chain, for which mainly the combustion of natural gas is assumed, adds another ∼16 CO2‐eq/kWh. The GHG emissions directly attributed to c‐Si PV technology alone constitute only ∼1–2 g CO2‐eq/kWh. The difference in scale indicates the relevance of reporting “indirect” emissions due to energy input in PV production separately from “direct” emissions particular to PV technology. In this article, we also demonstrate the utilization of “direct” and “indirect” shares of emissions for the calculation of GHG emissions in simplified world electricity‐ and PV‐market development scenarios. Results underscore very large GHG mitigation realized by solar PV toward increasingly significant PV market shares. Copyright © 2011 John Wiley & Sons, Ltd.
Development of industrial high‐efficiency back‐contact czochralski‐silicon solar cells
Authors: Gee James M. , Kumar Prabhat , Howarth James , Schroeder Todd , Franklin Jeff , Dominguez Jason , Tanner David
Published: January 2011

Back‐contact silicon solar cells feature high efficiencies, simpler module assembly, and improved aesthetics. The emitter wrap through (EWT) cell structure is particularly attractive for use with industrial processing (e.g., screen‐printed metallization) and common solar‐grade p‐type Si materials. We report development of a high‐efficiency EWT back‐contact cell using p‐type Cz silicon and only industrial processing techniques such as screen‐printed metallizations, diffusions, and PECVD. An efficiency of 19.0% has been achieved with large area (156‐mm pseudo‐square) cells. Detailed characterization and modeling have been performed to understand the optical and electrical losses, and these results were used to generate a roadmap to improve the efficiency to over 20%. Copyright © 2011 John Wiley & Sons, Ltd.
A genuine circular contact grid pattern for solar cells
Authors: Bissels G.M.M.W. , Asselbergs M.A.H. , Schermer J.J. , Haverkamp E.J. , Smeenk N.J. , Vlieg E.
Published: January 2011

A model was developed for a genuine circular contact grid, based on the same principles that led to previously reported models for other contact grid types. The circular grid differs from the regular (radial) grid often applied to round solar cells, in that it has considerably less radial lines and many more concentric rings, to the effect that the rings now take on the role of fingers, while the lines serve as busbars. For a 16 mm2 n‐on‐p GaAs cell and irradiances ranging from 1 to 1000 suns, optimised grids of this new circular design were compared to equivalent radial, square and inverted square grids. Furthermore, in order to allow for a fair comparison of the different grid types, the previously reported radial grid model was modified to obtain additional freedom in design that is comparable to that of the other grid configurations. The circular grid turned out to suffer less power loss than a comparable radial grid up to a concentration ratio of 30. At higher concentration ratios, cells with a radial grid performed better, while comparable square and inverted square grids perform better over the entire range of concentration ratios. For GaAs cells serving as the bottom cell in a mechanical tandem, the effects of secondary shadowing were calculated for a range of translational and rotational misalignments, for the four patterns optimised for the case where the GaAs cell is effectively subjected to a concentration ratio of 500. The effects of translational misalignment varied little between the grids, but the rotational misalignment effects demonstrated the strength of the circular grid, since its shadowing loss hardly increases with increasing rotational misalignment angle, while those of the other three grid types quickly approach a doubling. When these secondary shadowing effects are taken into account, the circular grid can be the preferred pattern for the constituent cells of a mechanical stack, depending on the accuracy with which those cells can be rotationally aligned. Copyright © 2011 John Wiley & Sons, Ltd.
Internet epidemiology: healthy, susceptible, infected, quarantined, and recovered
Authors: Kondakci Suleyman , Dincer Cemali
Published: January 2011

This paper presents a recurrent epidemic model (REM) to explore the dynamics of Internet epidemiology through the phases of susceptibility to recovery. From both theoretical and practical standpoint, it has two main differences compared to the bare worm propagation modeling. In the first place, it defines a unique stochastic model of a general infection spread. In the second place, it models the recovery process as a stochastic queueing system, which accurately partitions diagnose, quarantine, disinfection and recovery processes and complements it as a recurrent failure‐repair management model, which is entirely unique. There still exists an open question to model propagation patterns of infections and accompanying recovery models needed for effectively managing the infected individuals. The REM model is a unique concept in determining the parameters for estimating the recovery efficiency of disrupted systems and for developing long‐term recovery strategies under different epidemic situations. Existing infection and worm propagation models can also be used in cooperation with REM in order to analyse necessary quarantine and recovery processes. REM can also be applied for the accurate classification of the phases in epidemic dynamics and the states of affected systems in general, and also be used as a guideline for developing stochastic simulations covering various types of systems with recurrent state dynamics in order to facilitate reliability analysis of the systems. Copyright © 2011 John Wiley & Sons, Ltd.