bluuebunny/crossref_metadata_2025 huggingface dataset:
Untersuchung der Fluidströmung und deren Auswirkung auf die Partikelflugbahnen in einem Sprühtrockner
Authors: Stübing S. , Horender S. , Sommerfeld M. , Lübbers M.
Published: December 2007

Ziel der Untersuchungen war, bestehende Wandanlagerungen von Partikeln in einem Sprühtrockner zu minimieren. Dafür wurde die Bewegung der zu trocknenden Flüssigkeitstropfen in einem Sprühtrockner mittels CFD (computational fluid dynamics) numerisch berechnet. Die Fluidströmung im Einlassbereich des Trockners wurde mittels Laser‐Doppler‐Anemometrie vermessen, um Randbedingungen für die Simulationsrechnungen zu erhalten. Ein zweites, weiter vom Lufteinlass entfernt gemessenes Strömungsprofil diente als Validierung für das numerisch berechnete Profil. Es zeigte sich, dass die Abweichungen zwischen Experiment und Rechnung nur wenige Prozent betrugen. Die berechnete Fluidströmung im Sprühtrockner diente als Grundlage für die Berechnung der Flugbahnen der Produkttröpfchen aufgrund aerodynamischer Kräfte. Die daraus resultierenden Ablagerungsprofile stimmten gut mit den tatsächlich auftretenden Partikelablagerungen überein, sodass die Simulationen als Grundlage für Optimierungen des Sprühtrockners herangezogen werden konnten.
Präparation und Evaluation neuer Hybrid‐Protonenleiter – Teil II: Anorganische Nanoteilchen als Modifikator in Nafion®‐Hybridmembranen
Authors: Scheffler R. , Huth A. , Hübner G. , Marschall R. , Caro J. , Wark M.
Published: December 2007

Im Teil I dieser Veröffentlichungsreihe wurden Nafion®‐basierte Hybridmaterialien mit Ionischen Flüssigkeiten als Modifikatoren vorgestellt [1]. Der hier vorliegende Teil II verfolgt den Ansatz, anorganische hydrophile Nanoteilchen aus TiO2 oder dem Zeolithen Mordenit einer kommerziellen Nafion®‐Dispersion zuzusetzen und durch Foliengießen Nafion®‐basierte Hybridmembranen zu erhalten. Die Protonenleitfähigkeit der erhaltenen Hybridmembranen wurde durch Impedanzspektroskopie unter praxisrelevanten Bedingungen charakterisiert. Ziel ist es, bei möglichst geringer Befeuchtung mit Wasserdampf in einem Temperaturbereich von 120 °C eine hohe Protonenleitfähigkeit zu erzielen. Der Nutzen dieses Konzeptes konnte prinzipiell gezeigt werden, denn für Temperaturen höher als 100 °C konnte der Abfall der Protonenleitfähigkeit, wie er bei reinem Nafion in starkem Maße auftritt, aufgrund des Wasserrückhaltes durch die anorganischen Modifikatoren deutlich verringert werden.
Globale Bilanzen als Wegweiser für nachhaltiges Wirtschaften
Authors: Pfennig A.
Published: December 2007

Klimawandel und nachhaltiges Wirtschaften bestimmen heute viele Diskussionen, die Medien und die Politik. Eine klare Einschätzung der Situation fällt schwer, obwohl alle Daten prinzipiell verfügbar sind, da sich die Zahlenwerte aufgrund ihrer Größe der Vorstellung entziehen. In dieser Arbeit werden einige wesentliche Bilanzen pro Kopf der Weltbevölkerung und damit in einer vorstellbaren Größenordnung aufgestellt. Dadurch wird deutlich, dass Limitierungen nicht alleine die verfügbare Energie und das freigesetzte CO2 sind, sondern auch die Landfläche. Es werden Zukunftsszenarien aufbauend auf Prognosen zur Bevölkerungsentwicklung und den Bilanzen verglichen, die auch zeigen, wie empfindlich die verbleibenden Freiräume von kulturellen Aspekten wie Ernährungsgewohnheiten und Kinderzahl abhängen. Basierend auf den Szenarien werden Schlussfolgerungen zu unterschiedlichen Technologien abgeleitet.
The Menshutkin Reaction in the Gas Phase and in Aqueous Solution: A Valence Bond Study
Authors: Su Peifeng , Ying Fuming , Wu Wei , Hiberty Philippe C. , Shaik Sason
Published: December 2007

The recently developed (L. Song, W. Wu, Q. Zhang, S. Shaik, J. Phys. Chem. A 2004, 108, 6017–6024) valence bond method coupled to a polarized continuum model (VBPCM) is applied to the Menshutkin reaction, NH3+CH3Cl→CH3NH3++Cl−, in the gas phase and in aqueous solution. The computed barriers and reaction energies at the level of the breathing orbital VB method (P. C. Hiberty, J. P. Flament, E. Noizet, Chem. Phys. Lett. 1992, 189, 259), BOVB and VBPCM//BOVB, are comparable to CCSD(T) and CCSD(T)//PCM results and to experimental values in solution. The gas‐phase reaction is endothermic and leads to an ion‐pair complex via a late transition state. By contrast, the reaction in the aqueous phase is exothermic and leads to separate solvated ions as reaction products, via an early transition state. The VB calculations provide also the reactivity parameters needed to apply the valence bond state correlation diagram method, VBSCD (S. Shaik, A. Shurki, Angew. Chem. Int. Ed. 1999, 38, 586). It is shown that the reactivity parameters along with their semiempirical derivations provide together a satisfactory qualitative and quantitative account of the barriers.
Simulation of high‐speed flows by an unstructured grid implicit method including real gas effects
Authors: Hashemi M. Y. , Jahangirian A.
Published: December 2007

The incorporation of real gas effects into an efficient dual‐time implicit method is presented for numerical simulation of high‐speed flows. Two‐dimensional compressible Navier–Stokes equations are discretized by an implicit approach in a real‐time basis. The resulting set of implicit nonlinear equations is then solved iteratively in pseudo‐time using a Runge–Kutta scheme. A control‐volume central difference approach is used for spatial discretization on unstructured grids. For an equilibrium chemically reacting air, simplified equations are used to calculate the thermodynamics and transport properties of equilibrium air. The method is applied to hypersonic laminar flows of air over a compression ramp and a circular cylinder. Computational results are compared with those of other numerical methods and experimental data. Excellent agreement is obtained for various flow and heat transfer characteristics. Considerable reduction in computational time has also been achieved compared with the original explicit method. Copyright © 2007 John Wiley & Sons, Ltd.
A staggered grid‐based explicit jump immersed interface method for two‐dimensional Stokes flows
Authors: Rutka Vita
Published: December 2007

In this paper the explicit jump immersed interface method (EJIIM) is applied to stationary Stokes flows. The boundary value problem in a general, non‐grid aligned domain is reduced by the EJIIM to a sequence of problems in a rectangular domain, where staggered grid‐based finite differences for velocity and pressure variables are used. Each of these subproblems is solved by the fast Stokes solver, consisting of the pressure equation (known also as conjugate gradient Uzawa) method and a fast Fourier transform‐based Poisson solver.

This results in an effective algorithm with second‐order convergence for the velocity and first order for the pressure. In contrast to the earlier versions of the EJIIM, the Dirichlét boundary value problem is solved very efficiently also in the case when the computational domain is not simply connected. Copyright © 2007 John Wiley & Sons, Ltd.
Children with asthma: Assessment and treatment in school settings
Authors: Bray Melissa A. , Kehle Thomas J. , Grigerick Sarah E. , Loftus Susan , Nicholson Heather
Published: December 2007

Asthma is a chronic disease of the airways. It affects approximately 12% of American children, and it appears that that incidence is increasing. Asthma in children negatively influences school‐based outcomes such as absenteeism and friendship formation. Potential triggers of asthma include environmental allergens, exercise, weather, and emotional states. These lead to airway swelling and muscle constriction, which ultimately block airflow and impede breathing. In addition to medical treatments, the implementation of psychologically based interventions has been efficacious in school settings. © 2007 Wiley Periodicals, Inc.
6,7‐diaza‐1‐methoxy‐ 5‐methyl‐2, 8‐dioxabicyclo[3.2.1]oct‐6‐ene. An unstable bicyclic precursor of a dioxa carbonyl ylide and carbenes by ylide ring opening
Authors: Czardybon Wojciech , Sokol Wojciech , Warkentin John , Werstiuk Nick Henry
Published: December 2007

Synthesis of a bicyclic 2,2‐dioxa oxadiazoline (6,7‐diaza‐1‐methoxy‐5‐methyl‐2,8‐dioxabicyclo[3.2.1]oct‐6‐ene) is reported. Its thermolysis at 27°C is about 200 times as fast as the thermolysis of a monocyclic oxadiazoline model system. Presumably, a cyclic dioxa carbonyl ylide is formed initially and the ylide then undergoes a bond scission to afford either a dioxacarbene or a dialkylcarbene or it cyclizes to an oxirane. A small fraction of a dialkylcarbene was trapped as the product of addition to dimethyl acetylenedicarboxylate (DMAD). Computations of the barriers to the loss of N2 from the oxadiazolines and to the formation of the carbenes from the carbonyl ylide resulting from thermolysis of the bicyclic oxadiazoline are compared to corresponding barriers for a similar monocyclic oxadiazoline. The rate acceleration is accounted for in terms of geometric factors. The complex products from the decomposition of the bicyclic oxadiazoline were not studied. Copyright © 2007 John Wiley & Sons, Ltd.
Vinyl polymerization of norbornene by mono‐ and trinuclear nickel complexes with indanimine ligands
Authors: Tang Guangrong , Lin Yue‐Jian , Jin Guo‐Xin
Published: December 2007

A series of new indanimine ligands [ArNCC2H3(CH3)C6H2(R)OH] (Ar = Ph, R = Me (1), R = H (2), and R = Cl (3); Ar = 2,6‐i‐Pr2C6H3, R = Me (4), R = H (5), and R = Cl (6)) were synthesized and characterized. Reaction of indanimines with Ni(OAc)2·4H2O results in the formation of the trinuclear hexa(indaniminato)tri (nickel(II)) complexes Ni3[ArN = CC2H3(CH3)C6H2(R)O]6 (Ar = Ph, R = Me (7), R = H (8), and R = Cl (9)) and the mononuclear bis(indaniminato)nickel (II) complexes Ni[ArNCC2H3(CH3)C6H2(R)O]2 (Ar = 2,6‐i‐Pr2C6H3, R = Me (10), R = H (11), and R = Cl (12)). All nickel complexes were characterized by their IR, NMR spectra, and elemental analyses. In addition, X‐ray structure analyses were performed for complexes 7, 10, 11, and 12. After being activated with methylaluminoxane (MAO), these nickel(II) complexes can polymerize norbornene to produce addition‐type polynorbornene (PNB) with high molecular weight Mv (106 g mol−1), highly catalytic activities up to 2.18 × 107 gPNB mol−1 Ni h−1. Catalytic activities and the molecular weight of PNB have been investigated for various reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 489–500, 2008
Neopenthyl glycol containing poly(propylene terephthalate)s: structure–properties relationships
Authors: Soccio M. , Lotti N. , Finelli L. , Gazzano M. , Munari A.
Published: December 2007

Poly(propylene/neopenthyl terephthalate) random copolymers (PPT‐PNT) and poly(neopenthyl terephthalate) (PNT) were synthesized and subjected to molecular characterization. Afterwards, the polyesters were examined by TGA, DSC, andX‐ray. The copolymers, which displayed a good thermal stability, at room temperature appeared as semicrystalline materials: the main effect of copolymerization was a lowering in the amount of crystallinity and a decrease of the melting temperature with respect to homopolymer PPT. XRD measurements allowed the identification of the PPT crystalline structure in all cases. Amorphous samples were obtained after melt quenching, with the exception of PPT‐PNT5, and an increment of Tg as the content of NT units is increased was observed due to the effect of the side methylene groups in the polymeric chain. The Wood equation described well Tg‐composition data. Lastly, the presence of a rigid‐amorphous phase was evidenced in the copolymers, whose amount depended on composition and on thermal treatment. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 170–181, 2008
Morphological and thermal properties of ABS/montmorillonite nanocomposites using two different ABS polymers and four different montmorillonite clays
Authors: Patiño‐Soto A. P. , Sanchez‐Valdes S. , Ramos‐deValle L. F.
Published: December 2007

ABS/Clay nanocomposites were prepared using two ABS with different Acrylonitrile (AN) contents and four montmorillonite clays; a natural clay (CNa+) and three modified clays, Cloisites 10A, 20A, and 30B. The composites were prepared in a twin‐screw extruder. Results were analyzed considering the effect of clay and ABS type, on the clay dispersion, intercalation and exfoliation, as well as on the storage modulus and thermal stability of the nanocomposites. XRD and TEM confirm that when using an ABS with higher AN content (ABS2), a better dispersion and intercalation–exfoliation can be obtained. Cloisites 20A and 30B, respectively the one with greater initial intergallery spacing, but lower polarity and with smaller inter‐gallery spacing but greater polarity, produce the ABS nanocomposites with the greater intergallery spacing. Both ABS polymers have similar storage modulus and Tg and in both cases, the modulus increases with the 4 wt % clay. This increase is greater with the modified clays and slightly greater with the ABS2. Tg, from tan δ, increases very little with the 4 wt % clay, but again, this is slightly greater with ABS2. TGA and flammability tests show that the dispersed clay enhances the thermal stability and that the ABS with higher AN content produces a greater increase in fire retardancy. Tests also show that the better thermal stability and fire retardancy is obtained with the Cloisites 20A or 30B. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 190–200, 2008
Negative ion dissociation of peptides containing hydroxyl side chains
Authors: Pu Dan , Cassady Carolyn J.
Published: December 2007

The dissociation of deprotonated peptides containing hydroxyl side chains was studied by electrospray ionization coupled with Fourier transform ion cyclotron resonance (ESI‐FTICR) via sustained off‐resonance irradiation collision induced dissociation (SORI‐CID). Dissociation under post‐source decay (PSD) conditions was performed by matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF). This work included hexapeptides with one residue of serine, threonine, or tyrosine and five inert alanine residues. During SORI‐CID and PSD, dissociation of [M–H]− yielded c‐ and y‐ions. Side‐chain losses of formaldehyde (HCHO) from serine‐containing peptides, acetaldehyde (CH3CHO) from threonine‐containing peptides, and 4‐methylene‐2,5‐cycohexadienone (C7H6O) from tyrosine‐containing peptides were generally observed in the negative ion PSD and SORI‐CID spectra. Side‐chain loss occurs much less from tyrosine‐containing peptides than from serine‐ and threonine‐containing peptides. This is probably due to the bulky side chain of tyrosine, resulting in steric hindrance and poor geometry for dissociation reactions. Additionally, a selective cleavage leading to the elimination of the C‐terminal residue from [M–H]− was observed from the peptides with serine and threonine at the C‐terminus. This cleavage does not occur in the dissociation of peptides with an amide group at the C‐terminus or peptides with neutral or basic residues at the C‐terminus. It also does not occur with tyrosine at the C‐terminus. Both the C‐terminal carboxylic acid group and the hydroxyl side chain of the C‐terminal residue must play important roles in the mechanism of C‐terminal residue loss. A mechanism involving both the C‐terminal carboxylic acid group and a hydroxyl side chain of serine and threonine is proposed. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of phenoxyacetic acid herbicides as biomarkers in human urine using liquid chromatography/triple quadrupole mass spectrometry
Authors: Lindh Christian H. , Littorin Margareta , Amilon Åsa , Jönsson Bo A. G.
Published: December 2007

Phenoxyacetic acids are widely used herbicides. The toxicity of phenoxyacetic acids is debated, but high‐level exposure has been shown to be hepatotoxic as well as nephrotoxic in animal studies. An inter‐species difference in toxic effects has been found, with dogs particularly susceptible. In this study a method using liquid chromatography/triple quadrupole mass spectrometry (LC/MS/MS) is described for the analysis of 4‐chloro‐2‐methylphenoxyacetic acid (MCPA), and its metabolite 4‐chloro‐2‐hydroxymethylphenoxyacetic acid (HMCPA), 2,4‐dichlorophenoxyacetic acid (2,4‐D), and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T) in human urine. The urine samples were treated by acid hydrolysis to degrade possible conjugations. The sample preparation was performed using solid‐phase extraction. Analysis was carried out using selected reaction monitoring (SRM) in the negative ion mode. Quantification of the phenoxyacetic acids was performed using [2H3]‐labeled MCPA and 2,4‐D as internal standards. The method was linear in the range 0.05–310 ng/mL urine and has a within‐run precision of 2–5%. The between‐run precision in lower concentration ranges was between 6–15% and between 2–8% in higher concentration ranges. The limit of detection was determined to 0.05 ng/mL. The metabolites in urine were found to be stable during storage at −20°C. To validate the phenoxyacetic acids as biomarkers of exposure, the method was applied in a human experimental oral exposure to MCPA, 2,4‐D and 2,4,5‐T. Two healthy volunteers received 200 µg of each phenoxyacetic acid in a single oral dose followed by urine sampling for 72 h post‐exposure. After exposure, between 90 and 101% of the dose was recovered in the urine. In the female subject, 23%, and in the male subject 17%, of MCPA was excreted as HMCPA. Copyright © 2007 John Wiley & Sons, Ltd.
Exploring Taiwanese high school students' conceptions of and approaches to learning science through a structural equation modeling analysis
Authors: Lee Min‐Hsien , Johanson Robert E. , Tsai Chin‐Chung
Published: December 2007

Previous research has established a close link between students' conceptions of learning and approaches to learning. Until recently, only a few quantitative studies have investigated the relationship between high school students' conceptions of learning science and the approaches they adopt to learning science. This study sought to address this gap in the literature by assessing these possible relationships empirically through the development of two questionnaires: The Conceptions of Learning Science (COLS) questionnaire and the Approaches to Learning Science (ALS) questionnaire. Four hundred and seventy‐four Taiwanese high school students were administered the COLS questionnaire and the ALS questionnaire. Results were entered into a structural equation model to elicit structural relations between students' conceptions of and their approaches to learning science. Overall, findings revealed that students holding constructivist conceptions of learning science tended to employ deep approaches to learning science. Conceptions of learning science such as “testing” and “calculate and practice” were also found to have effects on the surface approaches to learning science; the conceptions of learning science as “applying” and “understanding and seeing in a new way” had noticeable effects on deep approaches to learning science. This study employed quantitative methods to confirm further the structural relations existing between conceptions of learning science and the motives and strategies employed in learning science. Implications for implementing the study's findings into the context of the real‐world classroom are discussed. © 2007 Wiley Periodicals, Inc. Sci Ed, 92:191–220, 2008.
Making (electrical) connections: Exploring student agency in a school in India
Authors: Sharma Ajay
Published: December 2007

Students studying in government‐run schools in rural India possess much experiential knowledge of the world around them. This paper presents a narrative account of an ethnographic exploration of such students as they attempted to learn about electricity in an eighth‐grade classroom in a government‐run schools in a village in India. The paper shows how students having a rich experience with household electric circuits attempt, in a contingent and situated manner, to negotiate their role as students and participate in the school science discourse. The students' actions expressed agency that was contingent, situated, and aimed at selective appropriation of school science discourse for their own purposes. Such expressions of student agency indicate rich possibilities for meaningful learning of science in rural schools in India provided school science is made relevant for their lives and concerns. © 2007 Wiley Periodicals, Inc. Sci Ed 92:297–319, 2008
“A sketch is like a sentence”: Curriculum structures that support teaching epistemic practices of science
Authors: Enfield Mark , Smith Edward L. , Grueber David J.
Published: December 2007

This research reports on a study of curriculum materials development and use compared with the use of existing curriculum materials in an elementary classroom. The research explored the effect of explicit attention to epistemic practices in curriculum materials and the enactment of those materials. Epistemic practices include asking questions, collecting data, making descriptions of observations, finding patterns in the data, and developing scientific reasoning. Scaffolding considered the function, role, and purpose of epistemic practices in the community of science and the production of scientific knowledge. The designed curriculum was compared with an existing pedagogically similar curriculum to consider whether the scaffolding and explicitness affected enactment. Findings lead to the conclusion that enactment was impacted. Specifically, findings show that scaffolding in materials created more instances of students engaging in scientific reasoning. Similarly, the explicit description of epistemic practices supported the teacher in explicitly providing opportunities for children to learn about and use epistemic practices of science. Finally, when using the designed curriculum, teacher modifications during enactment showed to be more consistent with the intended instructional approach and also helpful for children in learning epistemic practices of science. © 2007 Wiley Periodicals, Inc.Sci Ed92:608–630, 2008
Hochreflektierende Beschichtungen auf Kunststoffoptiken
Authors: Munzert P. , Schulz U. , Kaiser N.
Published: December 2007

Die Herstellung von Metallbeschichtungen mit höchster Reflexion auf Substraten aus Kunststoff gehört heutzutage noch nicht zum Stand der Technik. Bei der Beschichtung organischer Substratmaterialien treten nach wie vor vielfältige Probleme auf, deren Ursachen zumeist nicht bekannt sind. Eines der Hauptprobleme ist dabei die unzureichende Haftfestigkeit der Schicht auf dem Kunststoffsubstrat. In Versuchen konnte gezeigt werden, dass Aluminium‐ und Silberschichten durch Vakuumbedampfung auf vielen verschiedenen Kunststoffen durchaus haftfest abscheidbar sind, wenn bestimmte Prozessparameter eingehalten werden.

Weitere Probleme sind das Erreichen hoher Reflexionswerte sowie die Klimastabilität der Metallschichten. Durch Rauigkeitsmessungen an verschiedenen Kunststoffproben und einem Vergleich mit den nach Beschichtung erzielten Reflexionswerten konnte der Einfluss der Oberflächenqualität des Substrats auf die Reflexion der Metallbeschichtung ermittelt werden. Besonders hohe Reflexionswerte von über 97% im sichtbaren Spektralbereich wurden sowohl mit geschützten Silberspiegeln als auch mit dielektrisch verstärktem Aluminium erreicht. Bei diesen Systemen wurde zwischen der Beschichtung auf Glas und Kunststoff kein Reflexionsunterschied festgestellt. Die dielektrischen Verstärkungsschichten erhöhen zudem die Klimastabilität der Aluminiumbeschichtung.
Nichtinvasive Elektronendichtemessungen an technischen Plasmen mittels 26,5 GHz‐Mikrowellen‐Interferometrie
Authors: Selenin V. , Schwabedissen A. , Bunse D.
Published: December 2007

Die Diagnostik von technischen Plasmen mittels Mikrowellen‐Interferometrie wird insbesondere im Vergleich zur traditionellen Langmuir‐Sondendiagnostik diskutiert. Ein neuartiges Mikrowellen‐Interferometer (MWI 2650) der JE PlasmaConsult GmbH wird vorgestellt, das auf starre Hohlleiter im Referenzarm verzichtet und stattdessen ein flexibles Koaxialkabel verwendet. Die direkte Anzeige der Elektronendichte sowie ein kalibrierter Ausgang zu einem Oszilloskop erleichtern die Bedienung des Gerätes. Neben Messungen der Plasmadichte an chemisch reaktiven bzw. schichtabscheidenen Plasmen, bei denen Langmuirsonden prinzipbedingt Begrenzungen haben, können mit dem MWI 2650 auch zeitaufgelöste Messungen der Elektronendichte an gepulsten Plasmen mit hoher Empfindlichkeit durchgeführt werden. Mit diesem Gerät gelang es, einen Peak der Elektronendichte im Afterglow von elektronegativen bzw. staubigen Plasmen experimentell nachzuweisen. Eine spezielle Version des MWI 2650 ist auch für die Diagnostik von Atmosphärendruck‐Plasmen geeignet.
Project New Hope: Volunteers Caring for Children in Need
Authors: Landis Kit L. , Loar Christine W.
Published: December 2007

PROJECT NEW HOPE is an ongoing, collaborative, community program that provides no‐cost surgical procedures to uninsured children in the Reno, Nevada, region.

CHILDREN WITH PHYSICAL ABNORMALITIES who cannot otherwise afford surgery are referred to the program by clinics, schools, and social workers.

VOLUNTEERS FROM THE HEALTH CARE sector and the community participate in the program and have treated almost 150 children since the program started in 1997.

STRUCTURED, FREE‐SURGERY programs can be set up in other health care facilities using guidelines outlined in this article. AORN J 86 (November 2007) 769–779.
Reuse and Recycling Practices in a Colombian Hospital
Authors: Arévalo Lyda C. , Carrillo‐Martínez César Manuel
Published: December 2007

REUSE AND RECYCLING of donated and purchased items can allow health care facilities in developing countries to remain financially viable and provide services to those who could not otherwise afford them.

IN ONE BOGOTÁ, COLOMBIA, HOSPITAL, surgical instrumentation professionals and other clinicians developed reuse and recycling protocols for the OR.

ALTHOUGH NOT ALL OF THE PRACTICES described would be acceptable in the United States, these practices are a direct consequence of the impact of poverty on health care systems in a developing country. AORN J 86 (November 2007) 791–797.
Cognitive control in autism spectrum disorders
Authors: Solomon Marjorie , Ozonoff Sally J. , Cummings Neil , Carter Cameron S.
Published: December 2007

Cognitive control refers to the ability to flexibly allocate mental resources to guide thoughts and actions in light of internal goals. Given the behavioral inflexibility exhibited by individuals with autism spectrum disorders (ASDs), it would appear they experience cognitive control deficits. Cognitive correlates of this behavioral inflexibility have been elusive in previous investigations. Study goals were to investigate deficits in cognitive control in ASDs; to explore its developmental trajectory; and to test whether control deficits are related to symptoms of inflexible thoughts and/or behaviors, and attention symptoms. Thirty‐one children and adolescents aged 8–17 with ASDs and 32 age, IQ, and gender matched control subjects completed cognitive, diagnostic, and behavorial assessments, as well as a measure of cognitive control involving overcoming a prepotent response tendency. Compared with typically developing control subjects, individuals with ASDs exhibited deficits in cognitive control. Younger children with ASDs did not demonstrate age‐related improvements in cognitive control. Modest relationships between cognitive control, IQ, and attention problems were found for the sample. Only the relationship between cognitive control and full‐scale IQ survived correction for multiple comparisons.
Linking learning and effective process implementation to mass customization capability
Authors: Huang Xiaowen , Kristal Mehmet Murat , Schroeder Roger G.
Published: December 2007

This study investigates the role of learning and effective process implementation in the development of mass customization capability. Building upon the knowledge‐based view of the firm, we argue that internal and external learning are two knowledge‐generation routines that contribute to effective process implementation. Effective process implementation, in turn, is a knowledge‐based manufacturing capability, which, as a function of internal and external learning, leads to mass customization capability. We employ structural equation modeling to empirically test the effects of learning on mass customization capability, mediated by effective process implementation, using survey data collected from 100 manufacturing plants in 3 industries and 6 countries. Our results provide empirical evidence supporting the proposed model of the effect of internal and external learning on mass customization capability, fully mediated by effective process implementation. This research is one of the first studies to integrate insights from the knowledge‐based view of the firm and mass customization. It complements the OM view of mass customization, which to date has largely focused on the technical side, by demonstrating the role of managerial practices and learning in cultivating mass customization capability in a manufacturing environment.
Iodine requirements during pregnancy, lactation and the neonatal period and indicators of optimal iodine nutrition
Authors: Delange François
Published: December 2007

Objective:This paper re-evaluates the requirements for iodine during pregnancy, lactation and the neonatal period, and formulates original proposals for the median concentrations of urinary iodine (UI) that indicate optimal iodine nutrition during these three critical periods of life. This paper also discusses the measurements that are used to explore thyroid functions during the same periods.

Design:An extensive and critical review of the literature on thyroid physiopathology during the perinatal period.

Setting:Human studies conducted in various regions throughout the world.

Subjects:Pregnant women, lactating women, and newborns.

Results:The following proposals are made after extensive review of the literature: the requirement for iodine by the mother during pregnancy is 250-300 μg day-1; during lactation the requirement is 225-350 μg day-1; and during the neonatal period the requirement of the infant is 90 μg day-1. The median UI that indicates an optimal iodine nutrition during these three periods should be in the range of 150-230 μg day-1. These figures are higher than recommended to date by the international agencies.

Conclusions:Pregnant women and young infants, but especially the second group, are more sensitive to the effects of an iodine deficiency (ID) than the general population because their serum thyroid-stimulating hormone (TSH) and thyroxine are increased and decreased, respectively, for degrees of ID that do not seem to affect thyroid function in the general population. Systematic neonatal thyroid screening using primary TSH could be the most sensitive indicator to monitor the process of ID control.
Evidence for a solar cycle influence on the infrared energy budget and radiative cooling of the thermosphere
Authors: Mlynczak Martin G. , Martin‐Torres F. Javier , Marshall B. Thomas , Thompson R. Earl , Williams Joshua , Turpin Timothy , Kratz David P. , Russell James M. , Woods Tom , Gordley Larry L.
Published: December 2007

We present direct observational evidence for solar cycle influence on the infrared energy budget and radiative cooling of the thermosphere. By analyzing nearly five years of data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, we show that the annual mean infrared power radiated by the nitric oxide (NO) molecule at 5.3 μm has decreased by a factor of 2.9. This decrease is correlated (r = 0.96) with the decrease in the annual mean F10.7 solar index. Despite the sharp decrease in radiated power (which is equivalent to a decrease in the vertical integrated radiative cooling rate), the variability of the power as given in the standard deviation of the annual means remains approximately constant. A simple relationship is shown to exist between the infrared power radiated by NO and the F10.7 index, thus providing a fundamental relationship between solar activity and the thermospheric cooling rate for use in thermospheric models. The change in NO radiated power is also consistent with changes in absorbed ultraviolet radiation over the same time period. Computations of radiated power using an empirical model show much less variability than observed by SABER.
Warming and salinification of intermediate and deep waters in the Irminger Sea and Iceland Basin in 1997–2006
Authors: Sarafanov Artem , Sokov Alexey , Demidov Alexander , Falina Anastasia
Published: December 2007

Recent intra‐decadal changes in temperature and salinity of the Labrador Sea Water and Nordic overflow waters are quantified on the basis of the CTD data from the repeats of the zonal transatlantic section along ∼60°N carried out in 1997, 2002, 2004 and 2006. The revealed changes, in general, point to a rapid transition to the warmer/saltier conditions at the intermediate and deeper levels in the Irminger Sea and Iceland Basin at the section latitude in 1997–2006. In particular, substantial steady warming and salinification of the Iceland–Scotland Overflow Water is revealed in both basins. The latter result means an abrupt reversal or, at least, almost a decade‐long interruption of the long‐term freshening of this water lasted since the mid‐1960s.
Reduction in temporal and spatial extent of the Indian summer monsoon
Authors: Ramesh K. V. , Goswami P.
Published: December 2007

In the backdrop of a changing climate, we investigate whether the Indian summer monsoon is changing either in terms of duration or spatial coverage. Such an analysis specifically for the continental Indian region has both conceptual and societal implications, and has been lacking. We show here, based on an analysis of daily gridded observed rainfall data for the period 1951–2003, that there are decreasing trends in both early and late monsoon rainfall and number of rainy days, implying a shorter monsoon over India. Similarly, there is a sharp decrease in the area that receives a certain amount of rainfall and number of rainy days during the season. These trends are consistent with other variables like OLR and rainfall from independent datasets; in particular, the land‐ocean temperature contrast has a decreasing trend, consistent with a weakening monsoon. The results emphasize need for careful regional analysis in drawing conclusions regarding agro‐ecological sustainability in a changing climate.
Improving PET Receptor Binding Estimates from Logan Plots Using Principal Component Analysis
Authors: Joshi Aniket , Fessler Jeffrey A , Koeppe Robert A
Published: December 2007

This work reports a principal component analysis (PCA)-based approach for reducing bias in distribution volume ratio ( DVR) estimates from Logan plots in positron emission tomography (PET). Comparison has been made of all existing bias-removal methods with the proposed PCA method, for both single-estimate PET studies and intervention studies where pre- and post-intervention estimates are made. Bias in Logan-based DVR estimates is because of the noise in the PET timeactivity curves (TACs) that propagates as correlated errors in dependent and independent variables of the Logan equation. Intervention studies show this same bias but also higher variance in DVR estimates. In this work, noise in the TACs was reduced by fitting the curves to a low-dimension PCA-based linear model, leading to reduced bias and variance in DVR. For validating the approach, TACs with realistic noise were simulated for a 11C-labeled tracer with carfentanil (CFN)-like kinetics for both single-measurement and intervention studies. Principal component analysis and existing methods were applied to the simulated data and their performance was compared by statistical analysis. The results indicated that existing methods either removed only part of the bias or reduced bias at the expense of precision. The proposed method removed ∼90% of the bias while also improving precision in both single- and dual-measurement simulations. After validation of the proposed method in simulations, PCA, along with the existing methods, was applied to human [11C]CFN data acquired for both single estimation of DVR and dual-estimation intervention studies. Similar results were observed in human scans as were seen in the simulation studies.
Functional Reactivity of Cerebral Capillaries
Authors: Stefanovic Bojana , Hutchinson Elizabeth , Yakovleva Victoria , Schram Vincent , Russell James T , Belluscio Leonardo , Koretsky Alan P , Silva Afonso C
Published: December 2007

The spatiotemporal evolution of cerebral microcirculatory adjustments to functional brain stimulation is the fundamental determinant of the functional specificity of hemodynamically weighted neuroimaging signals. Very little data, however, exist on the functional reactivity of capillaries, the vessels most proximal to the activated neuronal population. Here, we used two-photon laser scanning microscopy, in combination with intracranial electrophysiology and intravital video microscopy, to explore the changes in cortical hemodynamics, at the level of individual capillaries, in response to steady-state forepaw stimulation in an anesthetized rodent model. Overall, the microcirculatory response to functional stimulation was characterized by a pronounced decrease in vascular transit times (20% ± 8%), a dilatation of the capillary bed (10.9% ± 1.2%), and significant increases in red blood cell speed (33.0% ± 7.7%) and flux (19.5% ± 6.2%). Capillaries dilated more than the medium-caliber vessels, indicating a decreased heterogeneity in vessel volumes and increased blood flow-carrying capacity during neuronal activation relative to baseline. Capillary dilatation accounted for an estimated ˜18% of the total change in the focal cerebral blood volume. In support of a capacity for focal redistribution of microvascular flow and volume, significant, though less frequent, local stimulation-induced decreases in capillary volume and erythrocyte speed and flux also occurred. The present findings provide further evidence of a strong functional reactivity of cerebral capillaries and underscore the importance of changes in the capillary geometry in the hemodynamic response to neuronal activation.
Interactions of two vortices near step topography
Authors: Hinds A. K. , Johnson E. R. , McDonald N. R.
Published: December 2007

The general motion of a pair of point vortices of arbitrary circulations in two-dimensional ideal shallow water near topography in the form of rectilinear step is found using Hamiltonian techniques. Paths are determined by the constants of motion: energy, linear impulse, and circulation. The behavior of vortex patches in the same geometry is computed using contour dynamics. Comparisons of point vortex and patch trajectories are found to be close provided the vortex patch centroids are sufficiently far away from the escarpment. For special values of the constants of motion, vortex pairs that propagate steadily parallel to the escarpment without deformation are found (that is, vortex pair equilibrium states) and exist even when the circulation of each vortex has the same sign.
Loss-cone instability: Wave saturation by particle trapping
Authors: Zaslavsky A. , Krafft C. , Volokitin A.
Published: December 2007

The nonlinear mechanisms governing the interactions between whistler or lower hybrid waves and loss-cone type particles’ distributions in magnetized plasmas are of great importance if one considers the major role that waves of frequency below the electron cyclotron frequency play in space and thermonuclear fusion plasmas. Up to now, most of the numerical simulations have been devoted to study the nonlinear processes at work when the plasma is weakly relativistic and when the anisotropy of the particles’ distributions leads to the so-called maser instability. However, in many interesting cases, the particles’ energies are sufficiently weak to ensure the validity of the nonrelativistic approximation. In this framework, the paper studies the interaction at normal cyclotron resonances between lower hybrid waves and electron distributions presenting loss-cone like features. A theoretical Hamiltonian model and a corresponding numerical symplectic code are used to evidence and to explain the nonlinear mechanisms at work at the saturation stage of the loss-cone instability. Moreover, simple analytical expressions and scaling laws have been derived for the linear growth rates and the wave amplitude at saturation.
A density functional theory study on the binding of NO onto FePc films
Authors: Tran Ngoc L. , Kummel Andrew C.
Published: December 2007

To develop an atomistic understanding of the binding of NO with iron phthalocyanine (FePc), the interaction between NO (an electron withdrawing gas) and NH3 (an electron donating gas) with an isolated FePc molecule (monomer) was compared with density functional theory. The simulations show that NO strongly chemisorbs to the Fe metal and physisorbs to all the nonmetal sites. Additionally, when NO physisorbs to the inner ring nitrogens, NO subsequently undergoes a barrierless migration to the deep chemisorption well on the Fe metal. Conversely, NH3 only weakly chemisorbs to the Fe metal and does not bind to any other sites. Projected density of states simulations and analysis of the atomic charges show that the binding of NO to the FePc metal results in a charge transfer from the Fe metal to the NO chemisorbate; the opposite effect is observed for the binding of NH3 to the Fe metal. Simulations of NO binding to the Fe metal of a monolayer FePc film and FePc trimer were also performed to show that intermolecular FePc-FePc interactions have a negligible effect on the FePc electronic structure and NO binding.
Avoiding singularity problems associated with meta-GGA (generalized gradient approximation) exchange and correlation functionals containing the kinetic energy density
Authors: Gräfenstein Jürgen , Izotov Dmitry , Cremer Dieter
Published: December 2007

Convergence problems of meta-GGA (generalized gradient approximation) XC (exchange and correlation) functionals containing a self-interaction correction term are traced back to a singularity of the latter that occurs at critical points of the electron density. This is demonstrated for the bond critical point of equilibrium and stretched H2. A simple remedy is suggested that cures meta-XC functionals such as VSXC, TPSS, M05, M06, and their derivatives without extra cost.
Gas mixing with pulsed optical lattices
Authors: Ngalande Cedrick G. , Gimelshein Sergey F. , Shneider Mikhail N.
Published: December 2007

A two-step kinetic/continuum approach has been used to study the ability of optical lattices to improve mixing rates of neutral gas mixtures. The kinetic step uses the direct simulation Monte Carlo method to model the gas-lattice interaction over the laser pulse period. The continuum step based on the solution of Navier-Stokes equations utilizes the kinetic solution as initial condition, and predicts the gas evolution at spatial and temporal scales larger than those associated with the optical lattice.
Vibrational inelastic and charge transfer processes in H++H2 system: An ab initio study
Authors: Amaran Saieswari , Kumar Sanjay
Published: December 2007

State-resolved differential cross sections, total and integral cross sections, average vibrational energy transfer, and the relative probabilities are computed for the H++H2 system using the newly obtained ab initio potential energy surfaces at the full CI/cc-pVQZ level of accuracy which allow for both the direct vibrational inelastic and the charge transfer processes. The quantum dynamics is treated within the vibrational close-coupling infinite-order-sudden approximation approach using the two ab initio quasidiabatic potential energy surfaces. The computed collision attributes for both the processes are compared with the available state-to-state scattering experiments at Ec.m.=20eV. The results are in overall good agreement with most of the observed scattering features such as rainbow positions, integral cross sections, and relative vibrational energy transfers. A comparison with the earlier theoretical study carried out on the semiempirical surfaces (diatomics in molecules) is also made to illustrate the reliability of the potential energy surfaces used in the present work.
Dynamics of analyte binding onto a metallophthalocyanine: NO∕FePc
Authors: Bishop Sarah R. , Tran Ngoc L. , Poon Gary C. , Kummel Andrew C.
Published: December 2007

The gas-surface reaction dynamics of NO impinging on an iron(II) phthalocyanine (FePc) monolayer were investigated using King and Wells sticking measurements. The initial sticking probability was measured as a function of both incident molecular beam energy (0.09–0.4eV) and surface temperature (100–300K). NO adsorption onto FePc saturates at 3% of a monolayer for all incident beam energies and surface temperatures, suggesting that the final chemisorption site is confined to the Fe metal centers. At low surface temperature and low incident beam energy, the initial sticking probability is 40% and decreases linearly with increasing beam energy and surface temperature. The results are consistent with the NO molecule sticking onto the FePc molecules via physisorption to the aromatics followed by diffusion to the Fe metal center, or precursor-mediated chemisorption. The adsorption mechanism of NO onto FePc was confirmed by control studies of NO sticking onto metal-free H2Pc, inert Au(111), and reactive Al(111).
Interpolating moving least-squares methods for fitting potential energy surfaces: Improving efficiency via local approximants
Authors: Guo Yin , Tokmakov Igor , Thompson Donald L. , Wagner Albert F. , Minkoff Michael
Published: December 2007

The local interpolating moving least-squares (IMLS) method for constructing potential energy surfaces is investigated. The method retains the advantageous features of the IMLS approach in that the ab initio derivatives are not required and high degree polynomials can be used to provide accurate fits, while at the same time it is much more efficient than the standard IMLS approach because the least-squares solutions need to be calculated only once at the data points. Issues related to the implementation of the local IMLS method are investigated and the accuracy is assessed using HOOH as a test case. It is shown that the local IMLS method is at the same level of accuracy as the standard IMLS method. In addition, the scaling of the method is found to be a power law as a function of number of data points N, N−q. The results suggest that when fitting only to the energy values for a d-dimensional system by using a Qth degree polynomial the power law exponent q∼Q∕d when the energy range fitted is large (e.g., E<100kcal∕mol for HOOH), and q>Q∕d when the energy range fitted is smaller (E<30kcal∕mol) and the density of data points is higher. This study demonstrates that the local IMLS method provides an efficient and accurate means for constructing potential energy surfaces.
An automated integration-free path-integral method based on Kleinert’s variational perturbation theory
Authors: Wong Kin-Yiu , Gao Jiali
Published: December 2007

Based on Kleinert’s variational perturbation (KP) theory [Path Integrals in Quantum Mechanics, Statistics, Polymer Physics, and Financial Markets, 3rd ed. (World Scientific, Singapore, 2004)], we present an analytic path-integral approach for computing the effective centroid potential. The approach enables the KP theory to be applied to any realistic systems beyond the first-order perturbation (i.e., the original Feynman-Kleinert [Phys. Rev. A 34, 5080 (1986)] variational method). Accurate values are obtained for several systems in which exact quantum results are known. Furthermore, the computed kinetic isotope effects for a series of proton transfer reactions, in which the potential energy surfaces are evaluated by density-functional theory, are in good accordance with experiments. We hope that our method could be used by non-path-integral experts or experimentalists as a “black box” for any given system.