bluuebunny/crossref_metadata_2025 huggingface dataset:
Transgenic mice studies demonstrate a role for platelet factor 4 in thrombosis: dissociation between anticoagulant and antithrombotic effect of heparin
Authors: Eslin Don E. , Zhang Chunyan , Samuels Kathleen J. , Rauova Lubica , Zhai Li , Niewiarowski Stefan , Cines Douglas B. , Poncz Mortimer , Kowalska M. Anna
Published: February 2004

The platelet-specific chemokine platelet factor 4 (PF4) is released in large amounts at sites of vascular injury. PF4 binds to heparin with high affinity, but its in vivo biologic role has not been defined. We studied the role of PF4 in thrombosis using heterozygote and homozygote PF4 knock-out mice (mPF4+/– and mPF4–/–, respectively) and transgenic mice overexpressing human PF4 (hPF4+). None of these lines had an overt bleeding diathesis, but in a FeCl3 carotid artery thrombosis model, all showed impaired thrombus formation. This defect in thrombus formation in the mPF4–/– animals was corrected by infusing hPF4 over a narrow concentration range. The thrombotic defect in the mPF4+/– and mPF4–/– animals was particularly sensitive to infusions of the negatively charged anticoagulant heparin. However, the same amount of heparin paradoxically normalized thrombus formation in the hPF4+ animals, although these animals were anticoagulated systemically. Upon infusion of the positively charged protein, protamine sulfate, the reverse was observed with mPF4+/– and mPF4–/– animals having improved thrombosis, with the hPF4+ animals having worsened thrombus formation. These studies support an important role for PF4 in thrombosis, and show that neutralization of PF4 is an important component of heparin's anticoagulant effect. The mechanisms underlying these observations of PF4 biology and their clinical implications remain to be determined.
The Discrimination of Faces and Their Emotional Content by Chimpanzees (Pan troglodytes)
Authors: PARR LISA A.
Published: February 2004

Abstract: The ability to recognize and discriminate conspecific faces and facial expressions has played a critical role in the evolution of social communication. Darwin was one of the first to speculate that human and nonhuman primate facial expressions share similar mechanisms for production and functions in expressing emotion. Since his seminal publication, numerous studies have attempted to unravel the meaning of animal signals, with the most success coming from the field of vocal communication, where researchers have identified the referential and emotional nature of specific vocalizations. Studies specifically addressing nonverbal facial displays, however, have faced numerous methodological challenges, including how to objectively describe facial movements and how to study the perception and production of these signals within a social context. In this paper, I will review my studies on chimpanzee face recognition, their ability to categorize facial expressions, and the extent to which chimpanzee facial expressions may convey information about emotion. Finally, recent studies from my lab have begun to address the role of auditory and visual cues in facial expression categorization. Chimpanzees were given the task of matching expressions according to which sensory modality was more salient, the visual or auditory component. For some expressions the visual modality was preferred, while for others the auditory modality was preferred. These data suggest that different social and ecological pressures may shift attention towards one sensory modality over another, such as during long‐distance communication or emotional conflict.
Emotional Facial Expressions in European‐American, Japanese, and Chinese Infants
Authors: CAMRAS LINDA A. , OSTER HARRIET , CAMPOS JOSEPH J. , BAKEMAND ROGER
Published: February 2004

Abstract: Charles Darwin was among the first to recognize the important contribution that infant studies could make to our understanding of human emotional expression. Noting that infants come to exhibit many emotions, he also observed that at first their repertoire of expression is highly restricted. Today, considerable controversy exists regarding the question of whether infants experience and express discrete emotions. According to one position, discrete emotions emerge during infancy along with their prototypic facial expressions. These expressions closely resemble adult emotional expressions and are invariantly concordant with their corresponding emotions. In contrast, we propose that the relation between expression and emotion during infancy is more complex. Some infant emotions and emotional expressions may not be invariantly concordant. Furthermore, infant emotional expressions may be less differentiated than previously proposed. Together with past developmental studies, recent cross‐cultural research supports this view and suggests that negative emotional expression in particular is only partly differentiated towards the end of the first year.
Sounds of Emotion
Authors: BACHOROWSKI JO‐ANNE , OWREN MICHAEL J.
Published: February 2004

Abstract:In his writing Darwin emphasized direct veridical links between vocal acoustics and vocalizer emotional state. Yet he also recognized that acoustics influence the emotional state of listeners. This duality—that particular vocal expressions are likely linked to particular internal states, yet may specifically function to influence others—lies at the heart of contemporary efforts aimed at understanding affect‐related vocal acoustics. That work has focused most on speech acoustics and laughter, where the most common approach has been to argue that these signals reflect the occurrence of discrete emotional states in the vocalizer. An alternative view is that the underlying states can be better characterized using a small number of continuous dimensions such as arousal (or activation) and a valenced dimension such as pleasantness. A brief review of the evidence suggests, however, that neither approach is correct. Data from speech‐related research provides little support for a discrete‐emotions view, with emotion‐related aspects of the acoustics seeming more to reflect to vocalizer arousal. However, links to a corresponding emotional valence dimension have also been difficult to demonstrate, suggesting a need for interpretations outside this traditional dichotomy. We therefore suggest a different perspective in which the primary function of signaling is not to express signaler emotion, but rather to impact listener affect and thereby influence the behavior of these individuals. In this view, it is not expected that nuances of signaler states will be highly correlated with particular features of the sounds produced, but rather that vocalizers will be using acoustics that readily affect listener arousal and emotion. Attributions concerning signaler states thus become a secondary outcome, reflecting inferences that listeners base on their own affective responses to the sounds, their past experience with such signals, and the context in which signaling is occurring. This approach has found recent support in laughter research, with the bigger picture being that the sounds of emotion—be they carried in speech, laughter, or other species‐typical signals—are not informative, veridical beacons on vocalizer states so much as tools of social influence used to capitalize on listener sensitivities.
Visual Field Information in the Face Perception of Chimpanzees (Pan troglodytes)
Authors: PLOTNIK JOSHUA , NELSON PETER A. , De WAAL FRANS B. M.
Published: February 2004

Abstract: Evidence for a visual field advantage (VFA) in the face perception of chimpanzees was investigated using a modification of a free‐vision task. Four of six chimpanzee subjects previously trained on a computer joystick match‐to‐sample paradigm were able to distinguish between images of neutral face chimeras consisting of two left sides (LL) or right sides (RR) of the face. While an individual's ability to make this distinction would be unlikely to determine their suitability for the VFA tests, it was important to establish that distinctive information was available in test images. Data were then recorded on their choice of the LL vs. RR chimera as a match to the true, neutral image; a bias for one of these options would indicate an hemispatial visual field advantage. Results suggest that chimpanzees, unlike humans, do not exhibit a left visual field advantage. These results have important implications for studies on laterality and asymmetry in facial signals and their perception in primates.
A Darwinian Legacy to Understanding Human Infancy
Authors: CAMPOS JOSEPH J. , THEIN SEINENU , OWEN DANIELA
Published: February 2004

Abstract:Darwin's influence on the study of emotional responding has largely centered on the study of the production of facial movement patterns. In this paper, we present evidence on the importance of considering facial and vocal patterns as signals that powerfully regulate behavior in infancy and early childhood. We review a series of studies showing that facial expressions and vocal expressions alone can regulate the behavior of infants and, in the case of vocal expressions, do so at ages earlier than most researchers have acknowledged. We also review studies on the enduring effects of social signals, documenting that even 8.5‐month‐olds show minimal retention of the effects of social signals, some 10‐month‐olds can retain the effects of social signals for 25 minutes, and 14‐month‐old can do so for a period of one hour after only two trials of signal exposure. Social signals not only regulate behavior, they also are part and parcel of an important and relatively unstudied phenomenon calledaffect sharing, which is evident by 11.5 months of age. Finally, we speculate on the constitutive role of social signals, especially those linked to what Ekman has called “basic emotions” in the generation of new emotions, such as pride, shame, and guilt.
Single-Crystalline Photochromism of Diarylethenes
Authors: Kobatake Seiya , Irie Masahiro
Published: February 2004

Diarylethene single crystals which exhibit thermally irreversible and fatigue-resistant photochromic reactions have been developed. Upon irradiation with ultraviolet light, the colorless diarylethene crystals turn yellow, red, blue, or green, depending on the substituents of the aryl groups. Dichroism of the photogenerated absorption spectra and in situ X-ray crystallographic analysis confirmed that the diarylethene molecules underwent photochromism in the single-crystalline phase. The photocyclization quantum yields were found to depend on the distance between the reactive carbon atoms in the crystal; the yields were close to unity when the distance is less than 4.2 Å. Multi-color photochromism was demonstrated for the crystals composed of two types of diarylethenes. The diarylethene single crystals showed reversible surface morphology changes upon photoirradiation.
Vaginal tampons as specimen collection device for the molecular diagnosis of non-ulcerative sexually transmitted infections in antenatal clinic attendees
Authors: Sturm P D J , Connolly Cathy , Khan Nasreen , Ebrahim Safiya , Sturm A Willem
Published: February 2004

Self-inserted vaginal tampons for the molecular diagnosis of non-ulcerative STIs were evaluated. Cervical and vaginal swabs, tampons and urines were collected from 185 first-time antenatal clinic attendees. Cultures and nucleic acid amplification assays (NAA) were performed. The sensitivity of PCR on tampons for Trichomonas vaginalis was with 94% (CI 85-98%) significantly higher ( P < 0.001) than culture (50%, CI 38-62%) or urine (53%, CI 41-65%). Neisseria gonorrhoeae culture had a sensitivity of 64% (CI 36-86%), strand displacement assay (SDA) had a sensitivity of 79% (CI 49-94%) using tampon specimens, 57% (CI 30-81%) using endocervical swabs and 43% (CI 19-70%) using urines. There was no difference in sensitivity of SDA for Chlamydia trachomatis using tampon specimens, urine or endocervical swabs. The specificity approached 100% for all assays on all specimens. NAA on tampons for the detection of T. vaginalis, N. gonorrhoeae and C. trachomatis identified more infections than assays on swabs or urines. This reached statistical significance for T. vaginalis only.
Low serum vitamin B12 levels in an outpatient HIV-infected population
Authors: Hepburn Matthew J , Dyal Kamal , Runser Lloyd A , Barfield Russell L , Hepburn Lisa M , Fraser Susan L
Published: February 2004

A retrospective review was conducted on serum vitamin B12 levels in an HIV-infected outpatient cohort, many of whom received antiretroviral therapy. B12 levels were obtained at most staging visits (every six months) and when clinically indicated. For each serum B12 level, laboratory values and clinical symptoms were recorded. Thirty-two patients (32/251 or 13%) had at least one low B12 level (<211pg/ mL) during the course of their HIV infection. Within two years of their initial HIV presentation, 6/57 patients had a low serum B12. Using multiple linear regression analysis, a higher serum B12 level was significantly associated with higher folate levels, African-American race, and lower mean corpuscular volume. B12 levels increased significantly after initiating antiretroviral therapy (416 vs 535 pg/mL, P = 0.04).

In conclusion, low serum B12 levels occur commonly among HIV-infected patients, even at early stages without overt symptoms of B12 deficiency. Antiretroviral therapy may increase serum B12 levels.
Accuracy of detecting irregular cardiac rhythms via telemedicine
Authors: Zenk Brenda M , Bratton Robert L , Flipse Thomas R , Page E Eugene
Published: February 2004

We evaluated the accuracy of an electronic stethoscope in the detection of irregular cardiac rhythms. Ten patients with either normal sinus rhythm or atrial fibrillation previously documented by electrocardiogram (ECG) were recruited from a local retirement community. Six senior family medicine resident physicians were asked to assess the cardiac rhythms of the subjects as either regular or irregular, in both a telemedical and an in-person examination. An ECG was obtained simultaneously as the gold standard. Forty-five of the 60 in-person assessments were correct, as were 49 of the 60 telemedicine assessments. The difference was not significant. Physician confidence in telemedical examination did not affect the accuracy of examination. The results of this study suggest that telemedicine-directed auscultation of patients may be just as successful as inperson examination for the detection of cardiac arrhythmias.
Possible Warfarin Failure Due to Interaction with Smokeless Tobacco
Authors: Kuykendall Jim R , Houle Michael D , Rhodes Richard S
Published: February 2004

OBJECTIVE

To report a case of possible interaction of smokeless tobacco with warfarin in a patient treated after several thromboembolic events.

CASE SUMMARY

A white man with a long history of smokeless tobacco use was unsuccessfully treated with warfarin up to 25–30 mg/day. International normalized ratio (INR) values never stabilized >2.0 over 4.5 years of therapy. This patient had experienced 3 myocardial infarctions (MIs) and 2 ischemic strokes between the ages of 29 and 31 years and experienced another MI at age 33 years. This was followed by several episodes of transient ischemic attacks at age 34 years. During the final year of warfarin treatment, tobacco use was terminated, followed by an increase in INR values from 1.1 to 2.3 within one week. Warfarin therapy was discontinued and smokeless tobacco use was reinstated and tapered slowly to discontinuation. Following warfarin discontinuation, ticlopidine therapy was initiated. Subsequently, this patient was placed on long-term clopidogrel therapy. Mechanisms responsible for this interaction have not been established, but would most likely involve an increased dietary source of vitamin K from tobacco.

DISCUSSION

Tobacco contains high levels of vitamin K, and its use may have contributed directly to the failure of warfarin therapy to achieve therapeutic INR levels in this patient. An objective causality scale indicates a probable association between this combination and the adverse effects. Smokeless tobacco use should be charted in patients undergoing warfarin therapy, and patients who desire to stop tobacco use should be aided in this process.

CONCLUSIONS

Possible health effects of smokeless tobacco may include potential drug interactions. These interactions may be based on pharmacodynamic and/or pharmacokinetic parameters involving any of the many pharmacologically active substituents of tobacco. Proposed mechanisms of drug interaction may include increased vitamin K levels in the diet.
Clinical Activities of an Academic Pediatric Pharmacy Team
Authors: Condren Michelle E , Haase Mark R , Luedtke Sherry A , Gaylor Allyson S
Published: February 2004

BACKGROUND

Pharmacy school faculty, residents, and students have been shown to positively impact patient care in multiple settings. However, their potential role in the care of pediatric patients has not been described.

OBJECTIVE

To document the contribution of pharmacy school faculty, residents, and students to the optimization of medical care for pediatric patients.

METHODS

All clinical interventions performed by faculty, residents, and students for pediatric patients seen from January through December 2002 were recorded and analyzed. The interventions were concurrently recorded using a handheld and desktop computer-based documentation system, the Pharmacist's Electronic Database for Interventions, developed by the pediatric practice team. Practice sites included general pediatrics, pediatric intensive care, neonatal intensive care, and ambulatory clinics.

RESULTS

Four faculty members, 5 residents, and 44 students collected intervention data. A total of 4605 interventions were performed for 3978 patients. The most common interventions performed were drug therapy change, pharmacokinetic monitoring, drug information, and medication histories/patient education. Drug added and drug deleted were the most frequent interventions performed in the drug therapy change category. The most common indications for which interventions were made were infectious (39.6%) and respiratory (23.3%) diseases. A total of 223 adverse drug events or medication errors were prevented or detected during the study period. Errors in dosing (overdose or underdose) were the most commonly encountered adverse events.

CONCLUSIONS

Pharmacy school faculty, residents, and students perform numerous clinical activities that play a significant role in the multidisciplinary care of pediatric patients.
The STEP Scale: A Measure of Short-Term Export Performance Improvement
Authors: Lages Luis Filipe , Lages Cristiana Raquel
Published: February 2004

This article is a direct response to a recent observation in the literature that managers appear to be short-term oriented in their assessment of the performance of an export venture ( Madsen 1998 ). On the basis of a cross-national survey of exporting firms, the authors present a three-dimensional scale for assessing managerial judgment of short-term export performance (i.e., the STEP scale). The three dimensions are (1) satisfaction with short-term performance improvement, (2) short-term exporting intensity improvement, and (3) expected short-term performance improvement. The scale presents evidence of reliability as well as convergent, discriminant, and nomological validity, and it reveals factorial similarity and factorial equivalence across both samples. The authors outline managerial and public policy implications that stem from the scale and identify avenues for further export marketing research.
A Study of the Service Encounter in Eight Countries
Authors: Keillor Bruce D. , Hult G. Tomas M. , Kandemir Destan
Published: February 2004

Drawing on the theory developed by the Nordic school of service marketing, the authors devise a model that involves the direct effects of technical (physical good quality) and functional (service quality and servicescape) elements of the service encounter on customers’ behavioral intentions. They test the model using service customers in the fast-food and grocery industries in eight countries (Australia, China, Germany, India, Morocco, the Netherlands, Sweden, and the United States). Notable differences exist between fast-food and grocery customers in the eight countries. The relative effects of the technical and functional service elements on behavioral intentions also differ significantly across countries.
Darstellung und H
∞-Regelung örtlich verteilter, linearer, zeitinvarianter Systeme
Authors: Reinschke Johannes
Published: February 2004

Der Beitrag befasst sich mit Regelstrecken, deren Ein- und Ausgangssignale neben der Zeit auch von örtlichen Koordinaten abhängen können. Für den modellgestützten Reglerentwurf mittels Standard-H
∞-Methoden wird die Klasse endlich-dimensionaler, örtlich verteilter, linearer, zeitinvarianter Systeme (so genannter 〟FDDLTI-Systeme〞) eingeführt. Das 〟Spillover〞-Problem kann durch eine robuste Stabilitätsanalyse bzw. einen robusten Reglerentwurf vermieden werden. Mögliche Anwendungen der hier entwickelten Theorie sind z.B. Regelungen der Wärmeleitung sowie von Membran- und Plattenschwingungen, insbesondere wenn die Platzierung der Sensoren und Aktuatoren nicht vorgegeben, sondern als Teil eines optimalen Reglerentwurfs zu bestimmen ist.
Flachheitsbasierter Entwurf von linearen und nichtlinearen Vorsteuerungen (Flatness-based Design of Linear and Nonlinear Feedforward Controls)
Authors: Hagenmeyer Veit , Zeitz Michael
Published: February 2004

Modellbasierte Vorsteuerungen werden zur gezielten Beeinflussung des Führungsverhaltens einer Regelung verwendet. Nominale Vorsteuerungen benötigen das inverse Modell der Regelstrecke. Die damit zusammenhängenden Probleme der Realisierbarkeit einer Vorsteuerung und deren Instabilität im Fall von nichtminimalphasigen Strecken können für flache Systeme gelöst werden. Dabei werden die Solltrajektorien der Steuerung und Regelung in den Koordinaten des flachen Ausgangs geplant. Der flachheitsbasierte Entwurf von linearen und nichtlinearen Vorsteuerungen wird beispielhaft für einen Arbeitspunktwechsel von SISO–Systemen erläutert und an einfachen Beispielen demonstriert.
Parameterrestriktionen bei der Identifikation am Beispiel des LSQ-Problems (Least Squares with a Single Quadratic Constraint)
Authors: Gröll Lutz
Published: February 2004

Verschiedenartige praktische Anwendungen führen auf LSQ-Probleme (Least-Squares-Probleme mit einer quadratischen Restriktion). Für diese Klasse von Problemen beschreibt der Beitrag einen numerisch robusten Algorithmus, der sich auf einen Satz von Moré stützt. Der Algorithmus löst das durch die Karush-Kuhn-Tucker-Bedingungen gegebene nichtlineare Gleichungssystem, indem er es auf eine skalare Gleichung für den Lagrange-Multiplikator reduziert. Zusätzlich werden Modifikationen für spezielle LSQ-Probleme vorgeschlagen.
99Tc detection in water samples by ICP-MS
Authors: Mas José L. , García-León M. , Bolívar J. P.
Published: February 2004

In this work three radiochemical procedures are presented for the determination of 99Tc in aqueous environmental samples by ICP-MS. Technetium is pre-concentrated from a dilute solution by a reduction-precipitation process using FeSO4 as the reducing agent. The precipitate is treated to extract and isolate Tc by three alternative methods which combine ionic exchange, with conventional or TEVA resins, and solvent extraction techniques using TBP. Special emphasis is paid to isolating the technetium from Mo and Ru, which are the major interfering elements for the mass spectrometric determination of 99Tc.
Limiting transport properties and hydration numbers of actinyl ions in pure water
Authors: Mauerhofer E. , Zhernosekov K. P. , Rösch Frank
Published: February 2004

The transport properties in pure water, i.e. the limiting ionic conductivity (λ°) and the limiting diffusion coefficient (D°), and the hydration numbers (N) of the singly and doubly charged uranyl, neptunyl, plutonyl and americyl ions MO2

n

+ (n = 1 or 2) have been calculated at 298.15K. A geometric model was applied in which the actinyl ions described by ellipsoids of revolution, with the axis O-M-O as axis of revolution, were transformed into spherical ions. The microscopic version of the Stokes–Einstein law has been used to derive the limiting transport properties of the ions. The main parameters involved in the calculations were the size of the bare ion, the effective cationic charge of the central actinide M, the viscosity of the water molecules in the first hydration shell of the ion and the size of this first hydration shell. The results obtained for the limiting transport properties and for the hydration numbers of the actinyl ions were found in good agreement with experimental data from the literature.
Optoelektronisches 3D-Positionsmesssystem (Optical 3D-Position Measuring System)
Authors: Abdelmalek Latifa , Hempel Eckhard , Fischer Harald
Published: February 2004

Die Positionserfassung bewegter Komponenten in der Robotik und Medizintechnik wird immer komplexer und erfordert in vielen Anwendungen die gleichzeitige Erfassung vieler Freiheitsgrade eines Objektes im Raum. Das führt zur Entwicklung von 3D-Sensoren, die die Raumlage der Roboter bzw. Instrumente bestimmen können. Ein optoelektronisches und berührungslos arbeitendes Messsystem zur dreidimensionalen Positionserfassung, basierend auf einem CCD-Flächenbildsensor, wurde entwickelt. Es kann sechs Freiheitsgrade erfassen, die drei translatorischen in x-, y- und z-Richtung und die drei rotatorischen um die jeweilige Koordinatenachse. Die experimentell bestimmten Auflösungen des Systems liegen für die x- und y-Richtung bei ca. 1 mm, für die z-Richtung bei 6 mm und für die Rotationen bei ca. 1º.
Affinitätsassay in der Mikrodialysekammer – ein generelles Prinzip für kontinuierlich messende Biosensoren (Affinity Assay in the Microdialysis Cell – a General Principle for On-line Measuring Biosensors)
Authors: Ehwald Rudolf
Published: February 2004

Verschiedene physikalische Größen – Fluoreszenzausbeute, Viskosität und osmotischer Partialdruck von Polymeren – wurden bisher zur Erfassung des Ligandenaustauschgleichgewichtes an einem Affinitätsrezeptor in einer Mikrodialyse-Kammer genutzt. Die Affinität des verwendeten Rezeptorproteins für die Liganden darf nicht zu hoch sein, da andernfalls der Ligandenaustausch zu langsam für einen On-line-Sensor erfolgt. Auf dieser Grundlage realisierte Sensoren für Glucose sind in das Unterhautfettgewebe implantierbar. Sie besitzen ein Anwendungspotenzial für das Blutglucose-Monitoring.
Affinitätssensor auf der Grundlage eines Membranosmometers (Affinity Sensor based on a Membrane Osmometer)
Authors: Krieftewirth Michael , Beyer Uwe , Doss Alexander , Ehwald Rudolf
Published: February 2004

Beim osmotischen Affinitätssensor wird die Konzentration von niedermolekularen Analytmolekülen gemessen, die einen polymeren Affinitätsliganden aus einem Komplex mit einem Affinitätsrezeptor verdrängen können. Der Ligandenaustausch findet in einem Mikro-Membran-Osmometer statt und führt zu einer Konzentrationsänderung der Polymere in der Osmometerzelle. Somit bewirkt der Ligandenaustausch eine Änderung der hydrostatischen Druckdifferenz gegenüber der Außenlösung. Da der Austausch von Dextranmolekülen an dem Lektin Concanavalin A durch Glucose relativ schnell und reversibel erfolgt, kann die Glucosekonzentration mit einem osmotischen Affinitätssensor kontinuierlich gemessen werden.
Quantitative comparisons of structures
Authors: Dziubek Kamil F. , Katrusiak Andrzej
Published: February 2004

Diagrams of the shortest selected non-bonding distances illustrating and measuring the structural differences have been employed for analysing polymorphs, isostructural crystals, and crystal structures at varied thermodynamical conditions. The diagrams efficiently compare the interatomic, intermolecular or interionic distances, describe quantitatively the crystal packings, and facilitate finding the molecular or ionic features responsible for the formation of polymorphs, isostructural crystals, or strains induced by changes of temperature or pressure. It appears as an immediate conclusion from comparing the interactions in a series of polymorphs and isostructural crystals, that the close packing rule plays the crucial role for the formation of these structures.
Determinations of crystallographic space group and atomic arrangements in oxide-ion-conducting Nd9.33(SiO4)6O2
Authors: Okudera Hiroki , Yoshiasa Akira , Masubuchi Yuji , Higuchi Mikio , Kikkawa Shinichi
Published: February 2004

In this paper we report single crystal X-ray diffraction study of an oxide-ion-conductor Nd9.33(SiO4)6O2 at 150 K. By detailed examinations of the atomic positions and an electron density distribution, it was clearly shown that Nd9.33(SiO4)6O2 has an apatite structure (space group P63/m) with no symmetry lowering or site-splitting. All oxygens in the hexagonal channel were located at their ideal positions (2a site at 0, 0, ¼) of the apatite structure, while their thermal displacements were highly anisotropic and that in the c-axis direction was more than four-times larger than those in other directions. Cation vacancies were located at the nine-coordinated 4f Nd site. The other Nd site (seven-coordinated 6h site) were basically fully occupied. This full occupation of the 6h Nd site makes potential waves inside the hexagonal channel smooth and transports of oxide-ions in the channel much easier. The distortion of SiO4 tetrahedron was not apparent. Crystallographic data at 150 K: Cell dimensions a = 9.5556(6) Å and c = 7.019(2) Å; F
(000) = 852; Z = 1; D
c = 5.779(2) g/cm3.
Comparative neutron and X-ray study of [PPN][HIr4(CO)9(μ-Ph2PCH2PPh2)]
Authors: Detti Serena , Forsyth V. Trevor , Roulet Raymond , Ros Renzo , Tassan Augusto , Schenk Kurt J.
Published: February 2004

The structure of this tetranuclear iridium cluster featuring a terminal Ir–H bond has been investigated by neutron crystallography using the D19 diffractometer at the Institut Laue Langevin in Grenoble. The structure, which is stabilized by numerous C–H⋯O=C hydrogen bonds, has no π–π stacking. The neutron study described here resolves a difficulty encountered in previous X-ray work where it proved impossible to locate reliably the position of hydrogen in the presence of heavy iridium atoms. Neutron crystallography offers unique advantages for this type of problem and in this case has provided the first reliable value for a terminal Ir–H distance of 1.618(14) Å and an intramolecular H–H contact of 2.40(2) Å.
EXAFS Spectroscopy – Fundamentals, Measurement Techniques, Data Evaluation and Applications in the Field of Phthalocyanines
Authors: Krishnan Venkata , Feth Martin P. , Wendel Eric , Chen Yu , Hanack Michael , Bertagnolli Helmut
Published: February 2004

EXAFS spectroscopy is a useful method for determining the local structure around a specific atom in disordered systems. This technique provides information about the coordination number, the nature of the scattering atoms surrounding a particular absorbing atom, the interatomic distance between the absorbing atom and the backscattering atoms, and Debye–Waller factor. The measurements are done with high energy X-rays, which are normally generated by synchrotron radiation sources. The data analysis is facilitated by specially developed program packages suitable for evaluation purposes. EXAFS spectroscopy is employed in several fields for a variety of applications. Here the structural characterization of a series of amorphous μ-oxo-bridged metallophthalocyanine dimers is presented. It is found that the phthalocyanine macrocycle has significant influence in the spectra and the results obtained are in agreement with the well-known structure of phthalocyanine complexes.
The Kinetics and Quantum Dynamics of Intramolecular Rearrangements in Highly Symmetrical Complexes: The Berry Pseudorotation
Authors: Merx Hendrik , Brickmann Jürgen
Published: February 2004

It is known that the intramolecular rearrangement of the ligands in trigonal-bipyramidal (TBP) molecules (e.g. PF5) follows a scheme first proposed by Berry and termed the Berry pseudorotation (BPR). There are 20 isomers, which are interconnected by 30 BPR reaction paths. In this paper, the time evolution of a given initial state is treated based on a set of first-order kinetic equations as well as on the basis of state-to-state tunneling processes. The dynamic equations are solved analytically using the eigenvalues and eigenvectors of the reaction-path connectivity matrix. It is shown that in the kinetic case the populations of all isomers approach an equilibrium value pi
(∞) = 1/20 while in the quantum case the individual isomers are never equivalent neither in time nor as time average. This fact is related to the strong regularity of the eigenvalue spectrum of the connectivity matrix for the reaction graph network. Consequently, pure quantum effects cannot be the basis for the occurrence of five equivalent ligands in PF5 (as was found experimentally).
Nanomaterials as Flow Regulators in Dry Powders
Authors: Zimmermann Ingfried , Eber M. , Meyer K.
Published: February 2004

From a physical point of view powders represent an intermediary state between solids and fluids. This holds especially with respect to their flow properties. Gravitational forces as well as interparticle forces are acting on particles in bulk powders. As long as the gravitational forces are prevailing the powder is able to flow. However as soon as the interparticle forces dominate the powder becomes cohesive. It does not flow any longer. Based on empirical observations highly dispersed Silicone dioxide is added to powders to improve their flowability. In the present paper we will present some findings obtained from studies on binary mixtures consisting of 0.2(m/m) of a nanoscaled material and corn starch. They give some insight into the mechanism of action of flow regulators. In addition they allow to classify flow regulators with respect to their efficiency as well as to their effectiveness. Furthermore the findings give hints on how to optimize existing flow regulators or to develop new improved ones.
Steady‐state pharmacokinetics of fluvastatin in healthy subjects following a new extended release fluvastatin tablet, Lescol® XL
Authors: Barilla Denise , Prasad Pratapa , Hubert Martine , Gumbhir‐Shah Kavita
Published: February 2004

This was an open‐label, randomized, three‐period, three‐treatment, multiple dose, crossover study in 12 healthy male and female subjects. This study evaluated single dose and steady‐state pharmacokinetics of fluvastatin following single and multiple dose administrations of a new extended release fluvastatin 8 h matrix tablet, Lescol® XL 80 mg and 160 mg doses once a day. The study also included a twice a day administration of an immediate release (IR) form of fluvastatin capsule, Lescol®, for comparative purposes. All doses were administered for 7 days. The safety and tolerability were also assessed. The pharmacokinetics of fluvastatin were evaluated on days 1 and 7 following each treatment. Fluvastatin systemic exposure was 50% less when administered as Lescol® XL 80 mg qd compared with Lescol® IR 40 mg bid. Conversely, fluvastatin systemic exposure was 22% higher when administered as Lescol® XL 160 mg qd compared with Lescol® IR 40 mg bid. Single doses of Lescol® XL 80 mg and 160 mg were dose proportional but, deviation (30%) from dose proportionality was observed for the Lescol® XL 160 mg at steady‐state. There appeared to be moderate (20%–40%) accumulation of serum fluvastatin maximal concentrations and exposure after multiple doses of Lescol® XL tablets. Both Lescol® XL 80 mg and 160 mg showed delayed absorption and longer apparent elimination half‐life compared with fluvastatin IR capsule. Single and multiple doses of fluvastatin were generally well tolerated in this healthy volunteer population. Adverse event profiles were consistent with the published safety profile of the marketed formulations. Aside from one incidence of creatine phosphokinase (CPK) elevation (following Lescol® XL 160 mg qd treatment), there were no safety concerns with any of the treatments when administered acutely (7 days). Copyright © 2004 John Wiley & Sons, Ltd.
Simple method for the assay of linezolid in Brain Heart Infusion broth by high‐performance liquid chromatography
Authors: Li Jian , Rayner Craig R. , Dixson Shirley , Nation Roger L.
Published: February 2004

A simple HPLC method was developed and validated for quantiﬁcation of linezolid in Brain Heart Infusion (BHI) broth. Eperezolid was employed as internal standard and the sample pre‐treatment procedure was simple. Calibration standards ranged from 0.05 to 16 mg/L. Accuracy was within 7.8% and reproducibility (RSD) was less than 8.3%. Recovery was approximately 100% at all concentrations examined. Linezolid was stable in the autosampler insert for at least 24 h at ambient temperature and in BHI for 72 h at 37°C. This assay is rapid and ideal for analysis of a large number of samples. Copyright © 2003 John Wiley & Sons, Ltd.
High performance liquid chromatographic analysis of dehydroepiandrosterone and its pharmaceutical tablet formulation
Authors: Aboul‐Enein Hassan Y.
Published: February 2004

A rapid, sensitive and stability indicating high performance liquid chromatographic method was developed and validated for the analysis of dehydroepiandrosterone (DHEA) in pharmaceutical tablet formulation. The analysis was done on a Supelcosil C18 column (25 cm × 4.6 mm i.d., 5 µm). The mobile phase consisted of methanol:sodium acetate buffer solution (5 g/L):acetic acid (500 mL/L), 57:42:1, v/v/v, adjusted to pH 5 at a ﬂow rate of 1 mL/min. Detection was carried out at a wavelength of 258 nm. The polynomial regression data for the calibration curve showed good linear relationship in the concentration range of 0.2–1 mg/mL with r = 0.9996. The method was validated for precision, accuracy and recovery. The limit of detection was found to be 50 ng/µL. The method was applied for the analysis of DHEA in its pharmaceutical tablet formulation. The effects of different buffers and alcohols on the retention of DHEA were studied and the role of acetic acid as an organic phase modiﬁer was also investigated. Copyright © 2003 John Wiley & Sons, Ltd.
Separation and determination of gentiopicroside and swertiamarin in Tibetan medicines by micellar electrokinetic electrophoresis
Authors: Zhao Shengguo , Liu Qing , Chen Xingguo , Hu Zhide
Published: February 2004

Micellar electrokinetic electrophoresis was employed to determine two active components, gentiopicroside (GE) and swertiamarin (SW) in one Tibetan preparation medicine named shiweilongdankeli, two Tibetan herbal medicines named Gentiana rhodantha and Gentiana kitag and three other Chinese Gentiana medicines named Gentiana scabra, Gentiana rigescens and Gentiana macrophylla. The dissociation constants of gentiopicroside and swertiamarin determined by MEKC were 7.71 and 6.25. The optimum buffer system was 70 mm borate–10 mm sodium dodecylsulfate (SDS) –6% (v/v) ispropanol (pH 9.0). The voltage was 15 kV and detection was at 254 nm. The lower limits of detection (deﬁned as a signal‐to‐noise ratio of about 3) were approximately 3.86 mg L−1 for GE and 5.88 mg L−1 for SW. The relative standard deviation of the migration time and peak area of the GE and SW were 2.33, 2.47 and 1.27, 2.19%, respectively and the recoveries of the two compounds were 96–104% for GE and 92–102% for SW. Copyright © 2003 John Wiley & Sons, Ltd.
Liquid chromatographic assay for the cyclic depsipeptide aplidine, a new marine antitumor drug, in whole blood using derivatization with trans‐4′‐hydrazino‐2‐stilbazole
Authors: Sparidans Rolf W. , Schellens Jan H. M. , López‐Lázaro Luis , Jimeno José M. , Beijnen Jos H.
Published: February 2004

A sensitive bio‐analytical assay for the depsipeptide aplidine in plasma has been modiﬁed and tested for human whole blood samples. The adapted method is based on reversed‐phase liquid chromatography and ﬂuorescence detection of the trans‐4′‐hydrazino‐2‐stilbazole derivative of the analyte. Aplidine is isolated from the matrix by solid‐phase extraction on an octadecyl modiﬁed silica stationary phase. After evaporation of the acetone eluate, the derivatization with the hydrazino reagent is performed in a water–acetonitrile mixture at pH = 4. The reaction mixture is injected directly into the chromatograph and the analyte is quantiﬁed by ﬂuorescence detection at 410 and 560 nm for excitation and emission, respectively. The method has been validated in the 2–100 ng/mL range, with 2 ng/mL being the lower limit of quantiﬁcation. Precision and accuracy both meet the current requirements for a bioanalytical assay. The stability of aplidine in whole blood at ambient temperature and at 37°C is limited; recoveries in the range 60–85% were observed after 7 h. Further, adequate stability of aplidine in plasma at −80 and −20°C for 35 months could now be demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
Toxicokinetic assessment of methylphenidate (Ritalin®) in a 13‐week oral toxicity study in dogs
Authors: Bakhtiar Ray , Ramos Luis , Tse Francis L. S.
Published: February 2004

Ritalin® or methylphenidate (MPH) is often prescribed for the treatment of attention deﬁcit hyperactivity disorder (ADHD) and narcolepsy. The therapeutic activity of MPH is principally due to d‐threo‐[2R,2′R]‐MPH. Hence, in order to establish a kinetic relationship between doses and exposure levels in a non‐rodent species, a 13‐week oral (capsule) toxicity study of d‐threo‐[2R,2′R]‐MPH was performed in beagle dogs. A previously reported chiral liquid chromatography tandem mass spectrometry (LC‐MS/MS) with a limit of quantiﬁcation (LLOQ) of 1.09 ng/ml was utilized. The results of this study indicated that MPH appeared to be rapidly absorbed in dogs following oral administration. The peak concentration was reached within 1–2 h. Based on the area under the curve (AUC) values, the plasma exposure of d‐MPH was over‐proportional to the dose. With the exception of two groups of animals (male/female, 7.5 mg/kg/day on day 1 and male/female, 3.0 mg/kg/day on week 7), the data showed no difference in MPH concentrations between the male and female dogs. Taking the statistical variations into account, concentrations of d‐MPH that were observed after 7.5 mg/kg/day doses of d‐MPH and 15 mg/kg/day doses of the racemate were similar. Following the racemate doses, the concentrations of l‐MPH were consistently higher than those of the d‐isomer. No accumulation of MPH was observed after 13 weeks of repeated daily administration. Copyright © 2003 John Wiley & Sons, Ltd.
Quantitative determination of p‐aminosalicylic acid and its degradation product m‐aminophenol in pellets by ion‐pair high‐performance liquid chromatography applying the monolithic Chromolith Speedrod RP‐18e column
Authors: Vasbinder E. , Van der Weken G. , Vander Heyden Y. , Baeyens W. R. G. , Debunne A. , Remon J. P. , García‐Campaña A. M.
Published: February 2004

An ion‐pair high performance liquid chromatographic method was developed for the simultaneous determination of p‐aminosalicylic acid (PAS) and its degradation product m‐aminophenol (MAP) in a newly developed multiparticular drug delivery system. Owing to the concencentration differences of PAS and MAP, acetanilide and sulfanilic acid were used as internal standards, respectively. The separation was performed on a Chromolith SpeedROD RP‐18e column, a new packing material consisting of monolithic rods of highly porous silica. The mobile phase composition was of 20 mm phosphate buffer, 20 mm tetrabutylammonium hydrogen sulphate and 16% (v/v) methanol adjusted to pH 6.8, at a ﬂow‐rate of 1.0 mL/min, resulting in a run‐time of about 6 min. Detection was by UV at 233 nm. The method was validated and proved to be useful for stability testing of the new dosage form. Separation efﬁciency was compared between the new packing material Chromolith SpeedROD RP‐18e and the conventional reversed‐phase cartridge LiChroCART 125‐4 (5 µm). A robustness test was carried out on both columns and different separation parameters (retention, resolution, run time, temperature) were determined. Copyright © 2004 John Wiley & Sons, Ltd.
Development of a fully coupled control‐volume finite element method for the incompressible Navier–Stokes equations
Authors: Ammara Idriss , Masson Christian
Published: February 2004

This paper proposes and investigates fully coupled control‐volume finite element method (CVFEM) for solving the two‐dimensional incompressible Navier–Stokes equations. The proposed method borrows many of its features from the segregated CVFEM described by Baliga et al. Thus finite‐volume discretization is employed on a colocated grid using either the MAW or the FLO schemes and an element‐by‐element assembling procedure is applied for the construction of the discretizations equations. In this paper, and unlike the case for most fully coupled formulations available in the literature, the Poisson pressure equation has been retained from the segregated approach. The use of a pressure equation leads to an unfavourable size increase of the fully coupled linear system, but significantly improves the system's conditioning. The fully coupled system obtained is solved using an ILUT preconditioned GMRES algorithm. The other important element in this paper is the proposal of a Newton linearization of the convection terms in lieu of the common Picard iteration procedure. A systematic comparison between two segregated and four fully coupled fomulations has been presented which has allowed for an evaluation of the individual benefits and strengths of the coupling and linearization procedure by studying lid‐driven cavity problems and flows past a circular cylinder. All coupled formulations have proven to be significantly superior both in robustness and efficiency, as compared with the segregated formulation. In some circumstances, the coupled methods yield a converged solution of the system of discretized equations constructed using the FLO scheme, while the segregated formulations diverge. Compared to Picard's linearization, Newton's linearization is more efficient at reducing the number of iterations needed to converge, but requires more computational effort per iteration from the linear equation solver. Furthermore, the Jacobian matrix should include contributions from the nonlinearity appearing at both the governing‐equation level and the interpolation‐scheme level to ensure Newton's method convergence. The key element in guaranteeing successful, fully coupled solutions lies in the use of an efficient linear equation solver and preconditioner. Copyright © 2004 John Wiley & Sons, Ltd.
A Lagrangian Discontinuous Galerkin‐type method on unstructured meshes to solve hydrodynamics problems
Authors: Loubère R. , Ovadia J. , Abgrall R.
Published: February 2004

This paper concerns a new Lagrangian Discontinuous Galerkin‐type method to solve 2D fluid flows on unstructured meshes. By using a basis of Bernstein polynomials of degree m in each triangle, we define a diffusion process which ensures positivity and stability of the scheme. The discontinuities of the physical variables at the interfaces between cells are solved with an acoustic Riemann solver. A remeshing/remapping process is performed with a particle method: the remapping is locally conservative and its accuracy can be adapted to the accuracy of the numerical method. Copyright © 2004 John Wiley & Sons, Ltd.
Analytical formulas for the velocity field induced by an infinitely thin vortex ring
Authors: Yoon Sam S. , Heister Stephen D.
Published: February 2004

Three different analytical solutions are presented for a potential vortex ring using three different streamfunctions. Verification studies confirm that all three approaches are valid. It is found that the solution obtained using the Biot–Savart law is the most efficient method due to its simplicity. It is shown that all analytical results are accurate to within machine accuracy and sample calculations are included. Copyright © 2004 John Wiley & Sons, Ltd.