bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficacy and Safety of Low-Carbohydrate Diets
Authors: Bravata Dena M. , Sanders Lisa , Huang Jane , Krumholz Harlan M. , Olkin Ingram , Gardner Christopher D. , Bravata Dawn M. 
Published: April 2003

ContextLow-carbohydrate diets have been popularized without detailed evidence of their efficacy or safety. The literature has no clear consensus as to what amount of carbohydrates per day constitutes a low-carbohydrate diet.ObjectiveTo evaluate changes in weight, serum lipids, fasting serum glucose, and fasting serum insulin levels, and blood pressure among adults using low-carbohydrate diets in the outpatient setting.Data SourcesWe performed MEDLINE and bibliographic searches for English-language studies published between January 1, 1966, and February 15, 2003, with key words such as low carbohydrate, ketogenic, and diet.Study SelectionWe included articles describing adult, outpatient recipients of low-carbohydrate diets of 4 days or more in duration and 500 kcal/d or more, and which reported both carbohydrate content and total calories consumed. Literature searches identified 2609 potentially relevant articles of low-carbohydrate diets. We included 107 articles describing 94 dietary interventions reporting data for 3268 participants; 663 participants received diets of 60 g/d or less of carbohydrates—of whom only 71 received 20 g/d or less of carbohydrates. Study variables (eg, number of participants, design of dietary evaluation), participant variables (eg, age, sex, baseline weight, fasting serum glucose level), diet variables (eg, carbohydrate content, caloric content, duration) were abstracted from each study.Data ExtractionTwo authors independently reviewed articles meeting inclusion criteria and abstracted data onto pretested abstraction forms.Data SynthesisThe included studies were highly heterogeneous with respect to design, carbohydrate content (range, 0-901 g/d), total caloric content (range, 525-4629 kcal/d), diet duration (range, 4-365 days), and participant characteristics (eg, baseline weight range, 57-217 kg). No study evaluated diets of 60 g/d or less of carbohydrates in participants with a mean age older than 53.1 years. Only 5 studies (nonrandomized and no comparison groups) evaluated these diets for more than 90 days. Among obese patients, weight loss was associated with longer diet duration (P = .002), restriction of calorie intake (P = .03), but not with reduced carbohydrate content (P = .90). Low-carbohydrate diets had no significant adverse effect on serum lipid, fasting serum glucose, and fasting serum insulin levels, or blood pressure.ConclusionsThere is insufficient evidence to make recommendations for or against the use of low-carbohydrate diets, particularly among participants older than age 50 years, for use longer than 90 days, or for diets of 20 g/d or less of carbohydrates. Among the published studies, participant weight loss while using low-carbohydrate diets was principally associated with decreased caloric intake and increased diet duration but not with reduced carbohydrate content.
The effect of a prior cognitive interview on children's acceptance of misinformation
Authors: Holliday Robyn E. 
Published: April 2003

AbstractThis research examined whether a Cognitive interview facilitates correct recall in children aged 4 to 5 and 9 to 10 years, and whether a Cognitive interview given before post‐event misinformation reduces children's reporting of suggestions on subsequent memory tests. Children were presented with an event followed the next day by a Cognitive or a Memorandum interview. Children were then read a post‐event summary containing misleading suggestions. The next day all children were given both standard test and modified forced‐choice cued‐recall tests. The free recall phase of the Cognitive interview elicited the greatest number of correct details. Age differences were found such that 9‐ to 10‐year‐old children's reports were more accurate and more complete than those of the 4‐ to 5‐year‐olds. More correct person, action and object details were reported in a Cognitive interview. Misinformation effects were found in both age groups on the standard test whereas on the modified test such an effect was only found in the 4‐ to 5‐year‐olds. Children's reporting of suggestions was unaffected by prior interview. Copyright © 2003 John Wiley & Sons, Ltd.
Mental reinstatement of the misinformation context and the misinformation effect in children and adults
Authors: Roebers Claudia M. , McConkey Kevin M. 
Published: April 2003

AbstractThe present study investigated the effects of mental reinstatement of the context in which misleading information about an event was presented on later recognition memory for the event. Five‐year‐olds, 7‐year‐olds and adults were shown a short video depicting a children's adventure and were asked a set of misleading questions to introduce misinformation one week later. Before the recognition memory test was administered another week later, half of the participants were given instructions to mentally reinstate the context of the misleading interview. Memory was assessed with a set of forced‐choice recognition questions once in the misleading interview context and for the children a second time at home one week later. When participants were instructed to mentally reinstate the context of the misleading interview prior to the recognition test, false memory reports occurred more often for adults than for children and had a stronger impact on peripheral information than on central information for both 7‐year‐olds and adults. When 5‐ and 7‐year‐olds were tested at home, false memory reports decreased. Thus, reinstating the context of an interview introducing misinformation can reduce the accuracy of memory reports; the context dependence of both accurate and inaccurate memory reports in children and adults is discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Surface Functionalization of Thermoplastic Polymers for the Fabrication of Microfluidic Devices by Photoinitiated Grafting
Authors: Rohr T. , Ogletree D.F. , Svec F. , Fréchet J.M.J. 
Published: April 2003

AbstractPhotografting has been used for the surface modification of a wide range of commercial commodity polymers such as poly‐ styrene, poly(methyl methacrylate), poly(dimethyl siloxane), polycarbonate, Parylene C, polypropylene, cyclic olefin copolymer, and hydrogenated polystyrene that are useful substrate materials for the fabrication of microfluidic chips. Since the chain propagation is initiated after UV light‐activated abstraction of a hydrogen atom from the surface of channels within the materials, their permeability for UV light was tested and polyolefins were found to be the best candidates. A number of monomers with a variety of functional groups such as perfluorinated, hydrophobic, hydrophilic, reactive, acidic, basic, and zwitterionic have been successfully grafted from the surface of selected substrates, and the grafting efficiency determined using X‐ray photoemission spectroscopy. Layered surface structures were prepared by consecutive grafting of different monomers. Our approach also enables photolithographic patterning of surfaces and specific functionalization of confined areas within the microchannel.
Reactive Ion Etching of Cylindrical Polyferrocenylsilane Block Copolymer Micelles: Fabrication of Ceramic Nanolines on Semiconducting Substrates
Authors: Cao L. , Massey J.A. , Winnik M.A. , Manners I. , Riethmüller S. , Banhart F. , Spatz J.P. , Möller M. 
Published: April 2003

AbstractThe diblock copolymers, poly(isoprene‐block‐ferrocenyldimethylsilane) (PI‐b‐PFDMS) and poly(ferrocenyldimethylsilane‐block‐dimethylsiloxane) (PFDMS‐b‐PDMS), form cylindrical micelles with an organometallic polyferrocenylsilane core in a solvent of hexanes. These cylindrical micelles were deposited onto a Si substrate from solution by either spin or dip coating, and upon reactive ion etching, continuous ceramic nanolines with lengths of micrometers and widths as small as 8 nm were created. The nanolines were characterized by scanning force microscopy (SFM) and transmission electron microscopy (TEM), and were shown to contain Fe, Si, and O from X‐ray photoelectron spectroscopy (XPS) studies. The widths of the nanolines could be varied from ca. 8 to 30 nm, depending on the composition of the corona (PI or PDMS). The oriented deposition of these cylindrical micelles can be achieved along pre‐patterned grooves on a resist film using capillary forces. Following treatment with hydrogen or oxygen plasma, oriented ceramic nanolines can be fabricated. The approach reported here represents a relatively simple method to create ceramic nanolines with large aspect ratio on semiconducting substrates.
Stabilization of Isolated Hydrous Amorphous and Tetragonal Zirconia Nanoparticles Through the Formation of a Passivating Alumina Shell
Authors: Kirsch B.L. , Tolbert S.H. 
Published: April 2003

AbstractIn this work, we explore the high‐temperature phase stability of isolated, alumina‐coated zirconia nanocrystals with a goal of understanding how interfacial energy affects phase stability. Isolated tetragonal and hydrous amorphous zirconia colloids were synthesized and coated with alumina through the hydrolysis of aluminum isopropoxide. Alumina‐coated samples exhibited phase behavior that was markedly different from that of the uncoated analogs. Uncoated tetragonal particles transformed to the monoclinic phase at 1100 °C while alumina‐coated tetragonal particles did not transform until 1400 °C. Uncoated hydrous amorphous particles crystallized to the tetragonal phase after heating at 600 °C and transformed to the monoclinic phase after heating at 800 °C. Alumina‐coated hydrous amorphous particles crystallized only after heating at 1050 °C, and transformed to the monoclinic phase after heating at 1400 °C. Differences in phase behavior are postulated to depend on the zirconia–alumina interface, which must be disrupted before zirconia particles can fuse and facilitate the tetragonal‐to‐monoclinic phase transition. By coating the nanocrystals with a thin alumina shell and studying the resultant phase stability, we explore the effect of reproducibly modified interfacial chemistry on phase behavior in nanoscale ceramic composites.
Fast and High‐Contrast Electro‐optical Switching of Liquid‐Crystalline Physical Gels: Formation of Oriented Microphase‐Separated Structures
Authors: Mizoshita N. , Hanabusa K. , Kato T. 
Published: April 2003

AbstractFast and high‐contrast responses with low driving voltages in twisted nematic (TN) cells are achieved for anisotropically oriented structures of liquid‐crystalline physical gels. They are prepared by hydrogen‐bonded aggregation of an L‐lysine‐based gelator in nematic liquid crystals. When the mixtures of the nematic liquid crystals and the gelator are prepared in TN cells, fibrous aggregates of the gelator align along the twisted‐nematic orientation of the liquid crystal, forming oriented phase‐separated structures.
Stabilized Blue Emission from Polyfluorene‐Based Light‐Emitting Diodes: Elimination of Fluorenone Defects
Authors: Gong X. , Iyer P.K. , Moses D. , Bazan G.C. , Heeger A.J. , Xiao S.S. 
Published: April 2003

AbstractPolyfluorene (PF)‐based light‐emitting diodes (LEDs) typically exhibit device degradation under operation with the emergence of a strong low‐energy emission band (at ∼ 2.2–2.4 eV). This longer wavelength band converts the desired blue emission to blue–green or even yellow. We have studied both the photoluminescence (PL) and electroluminescence (EL) of PFs with different molecular structures and found that the low‐energy emission band originates from fluorenone defects which are introduced by photo‐oxidization, thermal oxidation, or during device fabrication. X‐ray photo‐emission spectroscopy (XPS) results show that the oxidation of PF is strongly catalyzed by the presence of calcium. The fluorenone defects generate a stronger contribution to the EL than to the PL. By utilization of a novel electron‐transporting material as a buffer layer between the emissive PF and the Ca/Ag (Ba/Ag) cathode, the blue EL emission from the PF was stabilized.
Infiltrating Semiconducting Polymers into Self‐Assembled Mesoporous Titania Films for Photovoltaic Applications
Authors: Coakley K.M. , Liu Y. , McGehee M.D. , Frindell K.L. , Stucky G.D. 
Published: April 2003

AbstractInterpenetrating networks of organic and inorganic semiconductors are attractive for photovoltaic cells because electron transfer between the two semiconductors splits excitons. In this paper we show that films of titania with a uniform distribution of pore sizes can be made using a block copolymer as a structure‐directing agent, and that 33 % of the total volume of the film can be filled with a semiconducting polymer.
Metal Nanostructures with Hollow Interiors
Authors: Sun Y. , Mayers B. , Xia Y. 
Published: April 2003

AbstractWe have recently developed a simple and versatile route to the large‐scale synthesis of metal nanostructures with well‐defined hollow interiors. The key step of this process involves a replacement reaction between the surface of a nanoscale template and the solution of an appropriate salt precursor. The capability and feasibility of this method have been demonstrated by preparing hollow nanostructures of gold with a range of different morphologies (e.g., triangular rings, prism‐shaped boxes, cubic boxes, spherical capsules, and tubes). In addition to gold, this method also worked well for other metals such as platinum and palladium (see Figure for an SEM image of Pd nanotubes). These metal nanostructures with hollow interiors are useful as fillers for generation of ultralight composites; they are also interesting for new types of applications that include use as components for highly sensitive colorimetric sensors and as effective, recoverable catalysts.
Fullerene‐like WS2 Nanoparticles: Superior Lubricants for Harsh Conditions
Authors: Rapoport L. , Fleischer N. , Tenne R. 
Published: April 2003

AbstractWS2 nanoparticles with closed‐cage structure (fullerene‐like IF) are already being synthesized in macroscopic amounts from the respective oxide nanoparticles. They have been studied as superior solid lubricants under harsh conditions in recent years. Under severe contact conditions both fluids and greases are squeezed out from the contact area and consequently do not provide adequate lubrication conditions. Addition of even a small amount of IF nanoparticles to the oil was found to reduce the friction coefficient and wear rate, and increase the load‐bearing capacity of the friction pairs. Furthermore, IF nanoparticles were impregnated into polymer and metal coatings and into self‐lubricating porous metal parts, and were found to alleviate both friction and wear remarkably well. In another set of experiments, IF nanoparticles were shown to provide excellent tribological behavior for the contact between a ceramic alumina block and silicon nitride ball.The mechanism for the impro
ved tribological behavior of the IF nanoparticles is being investigated. In addition to the rolling friction, gradual exfoliation of the IF onions and transfer of monomolecular WS2 sheets onto the metal surface (third body transfer) is shown to play a major role in alleviating friction and wear. This work suggests numerous applications for this new solid‐state nanolubricant.
Oxide‐Assisted Growth of Semiconducting Nanowires
Authors: Zhang R.‐Q. , Lifshitz Y. , Lee S.‐T. 
Published: April 2003

AbstractIn this contribution, we outline oxide‐assisted growth (OAG) (distinct from the conventional metal‐catalytic vapor–liquid–solid (VLS) process) for the growth of nanostructured materials. This synthesis technique, in which oxides instead of metals play an important role in inducing the nucleation and growth of nanowires, is capable of producing large quantities of high‐purity silicon nanowires with a preferential growth direction, uniform size, and long length, without the need for a metal catalyst. The OAG 1D nanomaterials synthesis is complementary to, and coexistent with, the conventional metal‐catalyst VLS approach, and can be utilized to produce nanowires from a host of materials other than Si including Ge nanowires, carbon nanowires, silicon and SnO2 nanoribbons, and Group III–V and II–VI compound semiconductor nanowires.
Synthesen mit anionischen Templaten
Authors: Vilar Ramón 
Published: April 2003

AbstractIm Unterschied zu den gut untersuchten templatgesteuerten Synthesen mit kationischen und neutralen Templaten sind nur wenige Beispiele von Synthesen mit anionischen Templaten bekannt. Dies wurde einigen der intrinsischen Eigenschaften der Anionen wie der diffusen Elektronenhülle, der Empfindlichkeit gegen pH‐Änderungen und ihrer relativ hohen Freien Solvatationsenergien zugeschrieben. Allerdings zeigt die zunehmende Zahl von Aggregaten, die mit anionischen Templaten erhalten und im Laufe der letzten Jahre beschrieben wurden, dass diese Einschränkungen nicht so entscheidend sind wie zunächst gedacht. Dieser Aufsatz fasst die wichtigsten Ergebnisse im Bereich anionengesteuerter Templatreaktionen zur Synthese einer breiten Vielfalt anorganischer und organischer Aggregate (z. B. Makrocyclen, Käfige, Helicate, Rotaxane und kontinuierliche Strukturen) zusammen. Ziel ist es, einen Anstoß zu weitergehenden Forschungen in dieser jungen Teildisziplin der Supramolekularen Chemie zu geben.
Phosphaorganische Chemie: Panorama und Perspektiven
Authors: Mathey François 
Published: April 2003

AbstractDie gesamte phosphororganische Chemie wurde mit Beginn der siebziger Jahre infolge der Entdeckung stabiler phosphororganischer Derivate mit Koordinationszahlen des Phosphors von 1 oder 2 aufgefrischt. Bezüglich ihrer Chemie gleichen diese Verbindungen ihren reinen Kohlenstoff‐Analoga. Dieser Aufsatz widmet sich der Analogie zwischen den Phosphorderivaten und den entsprechenden Alkenen, Alkinen und Carbenen, wobei jede Verbindungsklasse anhand ihrer Synthese, ihrer Reaktivität und ihres Koordinationstyps kurz vorgestellt wird. Des Weiteren werden besondere Elektronenkonfigurationen der Phosphorverbindungen behandelt, darunter P‐P‐Einelektronenbindungen, gespannte Bindungen und aromatische Systeme. Abschließend wird auf mögliche Anwendungen dieser Chemie zur Herstellung molekularer Materialien und in der homogenen Katalyse verwiesen.
Gemini‐Tenside: neue synthetische Vektoren zur Gentransfektion
Authors: Kirby Anthony J. , Camilleri Patrick , Engberts Jan B. F. N. , Feiters Martin C. , Nolte Roeland J. M. , Söderman Olle , Bergsma Mark , Bell Paul C. , Fielden Matthew L. , García Rodríguez Cristina L. , Guédat Philippe , Kremer Andreas , McGregor Caroline , Perrin Christele , Ronsin Gaël , van Eijk Marcel C. P. 
Published: April 2003

AbstractDie oberflächenaktiven Eigenschaften kationischer Gemini‐Tenside werden zur Lösung des komplexen Problems der Gentransfektion in Zellen verwendet. Von nahezu 250 getesteten Substanzen, denen etwa 20 verschiedene Struktur‐Typen zugrunde liegen, zeigten viele eine gute In‐vitro‐Transfektionsaktivität. Das Tensid bindet und komprimiert DNS wirkungsvoll. Strukturelle und rechnerische Untersuchungen liefern ein brauchbares Modell des geformten Lipoplexes. Der Lipoplex kann durch die äußeren Membranen verschiedener Zelltypen dringen und so ins Cytoplasma gelangen. Die Freisetzung aus dem Endosom – ein Schlüsselschritt der Transfektion – könnte durch Veränderungen im Aggregationsverhalten des Lipoplexes bei fallendem pH‐Wert kontrolliert werden. Dies deutet auf ein Loslösen der DNS aus dem Lipoplex vor dem Eintritt in den Zellkern hin, wo das neue Gen mit hoher Effizienz exprimiert werden kann.
Ungewöhnliche Komplexchemie der Seltenerdelemente: große Ionenradien – kleine Koordinationszahlen
Authors: Dehnicke Kurt , Greiner Andreas 
Published: April 2003

AbstractSeltenerdelemente weisen wegen ihrer großen Ionenradien bei relativ niedrigen Oxidationszahlen in ihren Komplexen im Allgemeinen große Koordinationszahlen mit schwachen Metall‐Ligand‐Bindungen auf. Die Instabilität der Konfiguration dieser Komplexe in Lösung macht sie für die homogene Katalyse vielfach ungeeignet. Abhilfe versprechen Komplexe mit niedrigen Koordinationszahlen an den Metallatomen. Diese lassen sich auf klassischem Weg durch Verwendung voluminöser Liganden oder neuerdings durch Ligandengruppen mit besonderen Metall‐Ligand‐Bindungseigenschaften herstellen. Anhand von Komplexen mit dem sperrigen Bis(trimethylsilyl)amido‐Liganden und mit den “schlanken” Phosphaniminato‐Liganden (NPR3−) wird dieses Konzept vorgestellt und die Eignung dieser Komplexe als Katalysatoren für die Ringöffnungspolymerisation von Lactonen beschrieben.
Anion‐Templated Synthesis
Authors: Vilar Ramón 
Published: April 2003

AbstractIn contrast to the well‐studied templating properties of cationic and neutral species there are relatively few examples of anion‐templated syntheses. This is attributed to some of the intrinsic properties of anions such as their diffuse nature, pH sensitivity, and their relative high solvation free energies. However, the increasing number of anion‐templated assemblies reported over the past few years demonstrates that these limitations are not as critical as first thought. This review summarizes the most important results on the use of anions as directing agents for the syntheses of a wide range of inorganic and organic assemblies (such as macrocycles, cages, helicates, rotaxanes, and extended structures). It is hoped that this will stimulate a closer look into this emerging area of supramolecular chemistry.
Phospha‐Organic Chemistry: Panorama and Perspectives
Authors: Mathey François 
Published: April 2003

AbstractSince the beginning of the seventies, organophosphorus chemistry has been completely rejuvenated by the discovery of stable derivatives in which phosphorus has the coordination numbers one or two. The chemistry of these compounds mimics the chemistry of their all‐carbon analogues. In this Review article this analogy is discussed for the phosphorus counterparts of alkenes, alkynes, and carbenes. In each case, the synthesis, reactivity, and coordination modes are briefly examined. Some special electronic configurations are also discussed, which include one‐electron PP bonds, strained bonds, and aromatic systems. To conclude, some potential applications of this chemistry in the areas of molecular materials and homogeneous catalysis are presented.
Gemini Surfactants: New Synthetic Vectors for Gene Transfection
Authors: Kirby Anthony J. , Camilleri Patrick , Engberts Jan B. F. N. , Feiters Martin C. , Nolte Roeland J. M. , Söderman Olle , Bergsma Mark , Bell Paul C. , Fielden Matthew L. , García Rodríguez Cristina L. , Guédat Philippe , Kremer Andreas , McGregor Caroline , Perrin Christele , Ronsin Gaël , van Eijk Marcel C. P. 
Published: April 2003

AbstractThe superior surfactant properties of cationic gemini surfactants are applied to the complex problem of introducing genes into cells. Of almost 250 new compounds tested, of some 20 different structural types, a majority showed very good transfection activity in vitro. The surfactant is shown to bind and compact DNA efficiently, and structural studies and calculations provide a working picture of the “lipoplex” formed. The lipoplex can penetrate the outer membranes of many cell types, to appear in the cytoplasm encapsulated within endosomes. Escape from the endosome—a key step for transfection—may be controlled by changes in the aggregation behavior of the lipoplex as the pH falls. The evidence suggests that DNA may be released from the lipoplex before entry into the nucleus, where the new gene can be expressed with high efficiency.