bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Ni electroplating techniques towards stress-free microelectromechanical system-based sensors and actuators
Authors: Matovic J
Published: November 2006

The bimaterial cantilevers are frequently used in microsensors and microactuators. A bimaterial element consists of two layers of materials with different physical properties and/or deposited under different conditions. For this reason, mechanical stresses of various origins appear along the layers and between them, causing initial deformation of the cantilever. Further, a necessary condition for the optimum response of a bimaterial cantilever to an external stimulus is that Young's moduli of both layers are approximately equal. In thermal cantilever-based actuators commonly met in practice, the first layer is usually made of SiO2, PolySi, or SiNx, whereas the second is made of Al or Au. The Young's moduli of these materials differ significantly and thus the maximum sensitivity is difficult to achieve.

To ensure the planarity of the free cantilever, the common goal during fabrication is to obtain low internal stresses within both layers, which sometimes represent a severe technological limitation in high-temperature processes. This work presents a new method of stress compensation between the bimaterial cantilever layers. SiO2, PolySi, or SiNx are still used for the first layer, whereas nickel is used for the second layer. Nickel has many advantages and favourable mechanical properties compared with previously used aluminium and gold.
Development of a multi-material micropump
Authors: Richter M , Congar Y , Nissen J , Neumayer G , Heinrich K , Wackerle M
Published: November 2006

In this paper, the design of a multi-material micropump will be described. The micropump inhibits a very simple design and therefore is very cost efficient. The pump consists of one plastic part, one metal diaphragm, and three piezo lead-zirconate titanate (PZT) ceramics. The PZT ceramics, glued on a metal diaphragm, form two active valves (inlet and outlet valve) and one actuation diaphragm. The valve seats, the pump chamber, and the inlet/outlet interfacing channels are formed in the plastic body. Due to its function principle, the micropump is able to pump bidirectionally. The design of the micropump covers bubble tolerant and self-priming features. Therefore, design measures have been carried out to realize a large compression ratio and to reduce the capillary pressures of bubbles in the pump chamber. The pump is able to handle gases and liquids. The plastic body is made of poly-ether-ether-ketone, and the metal diaphragm is made of stainless steel. Therefore, a good chemical resistance will be given. First prototypes of the actuation unit have been manufactured and tested successfully. Each actuation unit is able to performa stroke ofmore than 40 μm. Furthermore, the plastic body has been realized by milling, and preliminary measurements were carried out. For future work, the development and optimization of an improved micropump using microinjection moulding instead of milling are envisaged.
Tribology of capillary blood flow
Authors: Secomb T. W. , Hsu R , Pries A. R.
Published: November 2006

The capillaries, with diameters typically in the range of 4 to 8 μm, are the terminal branches of the circulatory system. Blood is a concentrated suspension, containing 40-45 per cent volume of red blood cells (erythrocytes) suspended in plasma. These cells must undergo large deformations while passing through capillaries. Even so, the resistance to blood flow measured in capillary-sized glass tubes is less than would be expected based on the viscosity of blood measured in bulk. Theoretical analyses, in which the red blood cell is modelled as an elastic axisymmetric shell and lubrication theory is used to analyse the motion of plasma around the cell, provide a quantitative explanation for this behaviour. The walls of capillaries in vivo have been found to be lined with an endothelial surface layer of macromolecules with thickness of the order 1 μm. This layer interacts mechanically with moving red blood cells, and may protect them from damage as they traverse the irregularities of the microcirculation numerous times during the typical 120-days lifetime of each red blood cell.
Theoretical studies of elastohydrodynamic lubrication of artificial hip joints
Authors: Jin Z. M.
Published: November 2006

Theoretical studies of fluid-film lubrication in artificial hip joints are reviewed. The importance of developing effective numerical tools to solve realistic and complex lubrication problems in artificial hip joints has been emphasized. The elastic deformation of the bearing surfaces has been shown to play a dominant role in promoting elastohydrodynamic lubrication in various forms of artificial hip joints using different bearing surfaces. Both the bearing geometry and the structural supports can have a significant effect on the predicted lubricant film thickness. The importance of elastic deformation is further enhanced synergistically with the transient variation in load and speed to ensure a maximum effectiveness of the transient elastohydrodynamic lubrication mechanism in artificial hip joints. The recent application of the fast Fourier transform technique, in conjunction with the finite-element method to calculate the elastic deformation, not only enables more complex structural supports to the acetabular cup to be considered, but also offers the potential of analysing both transient and mixed lubrication problems in artificial hip joints.
Oral tribology
Authors: Zhou Z. R. , Zheng J
Published: November 2006

The application of oral tribology is a rapidly growing and expanding field. This article deals with the main problems of oral tribology, such as dental wear, temporomandibular joint (TMJ), and saliva. Main progress in these topics obtained by the authors and from the literatures is reviewed. Wear of human teeth, restorative materials, and their applications to archaeology have been emphasized. Tribological behaviours of saliva and TMJ have been presented. The problems and challenges of fundamental research in oral tribology have been discussed at the end of the article.
Introduction to biotribology: Animal locomotion
Authors: Alexander R McN
Published: November 2006

Limbs of vertebrate animals have synovial joints. Many arthropod joints and the hinges of bivalve molluscs owe their mobility to components that bend, rather than to surfaces that slide over each other. No lubrication systems have been described for the few sliding surfaces in invertebrate joints. Peak forces on animal joints tend to be roughly proportional to (body mass)2/3. The fin spines of some fishes have modified joints at their bases, which enable the fish to lock the spine in the erect position.

The ventral surfaces of crawling animals, including earthworms, snakes, and snails, slide over the ground. The conditions required for forward progress are discussed. Particularly, interesting tribological questions arise in the case of snails, which crawl on a mucus trail. For running animals, fast turns and other manoeuvres involving acceleration may be limited by friction with the ground.

The feet of insects and geckos adhere to solid surfaces, enabling these animals to climb vertical walls and even to walk on ceilings. Van der Waals adhesion seems to be responsible in the case of geckos and capillary adhesion in many insects. The trap of pitcher plants captures insects by making the adhesive mechanism ineffective.
Micromechanics in biogenic hydrated silica: Hinges and interlocking devices in diatoms
Authors: Gebeshuber I. C. , Crawford R. M.
Published: November 2006

Diatoms are single-celled organisms with rigid parts in relative motion at the micrometre scale and below. These biogenic hydrated silica structures have elaborate shapes, interlocking devices, and, in some cases, hinged structures. The silica shells of the diatoms experience various forces from the environment and also from the cell itself when it grows and divides, and the form of these micromechanical parts has been evolutionarily optimized during the last 150 million years or more, achieving mechanical stability. Linking structures of several diatom species such as Aulacoseira, Corethron, and Ellerbeckia are presented in high-resolution SEM images and their structure and presumed functions are correlated. Currently, the industry for micro- and nanoelectromechanical devices (MEMS and NEMS) puts great effort into investigating tribology on the micro- and nanometre scale. It is suggested that micro- and nanotribologists meet with diatomists to discuss future common research attempts regarding biomimetic ideas and approaches for novel and/or improved MEMS and NEMS with optimized tribological properties.
Introduction to lumbar total disc replacement: Factors that affect tribological performance
Authors: Hall R. M. , Brown T. D. , Fisher J , Ingham E , Mendoza S. A. , Mayer H. M.
Published: November 2006

Total disc arthroplasty offers both theoretical and practical advantages over fusion surgery as a treatment for low back pain. In the majority of cases, these relatively new devices owe much of their evolution to the success of other total joint replacements, in particular, hip and knee prostheses, which have been developed over the last four decades. The demands on these new joints are substantial, and although short-term data appear to demonstrate good outcomes in a significant proportion of patients, medium- and longer-term results are sparse. The wear performance of these devices should be emphasized as a possible cause of failure through both adverse biological reactions, such as osteolysis, and inappropriate biomechanics, similar to that observed in a small proportion but numerically significant number of hip and knee prostheses. This article reviews the current technology in terms of the performance parameters these devices are required to operate within and the evidence for future problems akin to those observed in other joint arthroplasties. The article calls for more rigorous preclinical testing and follow-up protocols, based on the technologies and procedures developed for the current range of conventional hip and knee replacements.
Tribology of artifical hip joints
Authors: Unsworth A
Published: November 2006

Artificial hip joints have historically simply replaced the geometrical architecture of the worn natural joints using materials that were known to be biocompatible and possessing low wear properties. More recently, the emphasis has been on more advanced tribological design in which the body's natural lubricant combined with improved surface technology conspire to produce fluid-film lubrication and consequently lower wear.

These advances make it possible for recipients to lead more active lives and to do so for a longer time without the increased risks of premature failure due to loosening caused by osteolytic action which itself can be the result of wear debris produced in walking.

In this paper, the future of the artificial joints is discussed from a point of view of improved tribological knowledge being utilized to improve the design of artificial hip joints.
Tribology of skin
Authors: Sivamani R. K. , Maibach H. I.
Published: November 2006

Tribological studies of skin provide valuable insight into how the properties of skin are altered with various conditions and chemical treatments. This work reviews the frictional and the electrical properties of the skin surface, with an emphasis on the measurement of the friction coefficient. Many designs have been utilized and past studies have included numerous probe geometries and materials. An advantage of tribological measurements is that they offer a non-invasive way to quantitatively measure skin hydration and health. Skin friction seems to be dependent on several factors such as age, anatomical site, and skin hydration. The design of the measuring instrument and the probe geometry and material also affect the friction measurement. Clinically, it was found that skin with decreased hydration, as with psoriasis or atopic dermatitis, had a reduced friction coefficient and an increased resistance to current flow. Chemical treatments influence skin hydration level and affect the friction coefficient. Application of water and isopropyl alcohol increased and decreased the friction coefficient, respectively. A discussion of emollients and moisturizers is included with an emphasis on describing ‘greasiness’ and ‘stickiness’ quantitatively. Tribological measurements are a multi-faceted and non-invasive way to quantify skin hydration and health.
The natural synovial joint: Properties of cartilage
Authors: Ateshian G. A. , Hung C. T.
Published: November 2006

Articular cartilage is the bearing material that lines the ends of the bones of synovial joints. Its primary function is to reduce friction and wear at the articulations of the musculoskeletal system. The tribological properties of cartilage are intimately related to its structure and mechanical properties. The modes of lubrication in cartilage extend beyond the traditional mechanisms of fluid-film or boundary lubrication. The purpose of this review is to describe the salient properties of articular cartilage necessary to understand the unique biotribology of diarthrodial joints.
Study of hydration lubrication on cartilage surface using evanescent wave
Authors: Ikeuchi K , Naka M. H.
Published: November 2006

In human joints, hydrated surface layer is formed on articular cartilage with proteoglycan molecules exposed to the surface. The mechanism of lubrication between the surface layer and a prism was studied experimentally with a porcine knee cartilage. When total reflection is achieved, the field of evanescent wave is formed near the prism surface. The reflectance is attenuated when collagen fibre approaches the prism. Thus, collagen fibre content close to the interface can be estimated from the attenuation of reflectance. Friction force and attenuation of reflectance increase during sliding under load due to exudation of water from the surface layer. After short preloading (10 s), high reflectance, low friction force, and low adhesion force are kept until the end of the sliding test for 20 s. In contrast, the effect of hydration lubrication is almost lost during preloading for a long time (300 s). The experimental result shows that attachment of the proteoglycan molecules to the prism causes both adhesion and friction and the water attracted by the proteoglycan molecules in the surface layer prevents adhesion and reduce friction. The mechanism of hydration lubrication in this study is supported by the positive correlation between adhesive force and friction force.
Case illustration of a decision framework for health, environment, and safety management
Authors: Vinnem J. E. , Aven T
Published: November 2006

This paper presents and discusses a case in order to illustrate the application of a recently developed decision framework for management of health, environment, and safety. The case relates to the implementation of new equipment on an offshore platform and shows how a regime based on predefined risk acceptance criteria is replaced by systematic risk reduction processes, emphasizing aspects of uncertainties and manageability in addition to the calculated risk results. Although the starting point is the offshore oil and gas industry, the problem and discussion are to a large extent general and could also be applied in other areas.
On probabilistic safety assessment in the case of zero failures
Authors: Coolen F. P. A.
Published: November 2006

Probabilistic safety assessment often depends on the quantification of the frequencies of failures, on the basis of zero failures in the available data. A variety of estimates for such frequencies have been suggested in the literature, mainly within the classical and Bayesian statistical frameworks, and with emphasis on the constant failure rate of an exponential distribution. In this paper, this problem is considered from the perspective of non-parametric predictive inference (NPI), where the main difference from the established approaches is the use of lower and upper probabilities, leading to lower and upper estimates for the constant exponential failure rate instead of point estimates. On the basis of zero failures observed, the lower estimate for the failure rate is zero; so interest is mostly in the upper failure rate. Such lower and upper estimates reflect the indeterminacy due to the data scarcity. The NPI-based upper estimate for the failure rate depends not only on the length of the failure-free period represented as data but also on the required or chosen length of the future period considered in the risk assessment, in a possibly surprising manner. The use of failure rate estimates in probabilistic safety assessment is discussed, and a more straightforward predictive approach is suggested.
Optimization of system reliability using chaos-embedded self-organizing hierarchical particle swarm optimization
Authors: Bachlaus M , Shukla N , Tiwari M. K. , Shankar R
Published: November 2006

This paper addresses a reliability optimization problem, where the motive is to select the best components for series and series-parallel systems such that system reliability becomes maximized while simultaneously minimizing the cost, weight, and volume. Previous formulation of the problem has implicit restrictions, i.e. it either maximizes system reliability or minimizes the cost. Thus, in order to give a realistic view to the model, a comprehensive objective function has been formulated by combining the normalized values of reliability, cost, weight, and volume. In this paper, a chaos-embedded hierarchical particle swarm optimization (CE-HPSO) algorithm has been proposed to solve the problems arising in the optimization of system reliability using redundancy. The salient features of the proposed algorithm are the use of chaotic sequences and time-varying acceleration coefficients which are responsible for diversifying the search space. Moreover, to restrict the premature convergence, a hierarchical particle swarm optimizer has been used in the proposed algorithm. The performance of the CE-HPSO algorithm has been tested on three benchmark problems and the comparisons are made with genetic algorithm results. In order to check the scalability of the proposed solution methodology, small and large problems are also considered. The results demonstrate the benefits of the proposed algorithm for solving this type of problem.
A binary decision diagram method for phased mission analysis of non-repairable systems
Authors: Dunnett S. J. , Andrews J. D.
Published: November 2006

Phased mission analysis is carried out to predict the reliability of systems which undergo a series of phases, each with differing requirements for success, with the mission objective being achieved only on the successful completion of all phases. Many systems from a range of industries experience such missions. The methods used for phased mission analysis are dependent upon the repairability of the system during the phases. If the system is non-repairable, fault-tree-based methods offer an efficient solution. For repairable systems, Markov approaches can be used.

This paper is concerned with the analysis of non-repairable systems. When the phased mission failure causes are represented using fault trees, it is shown that the binary decision diagram (BDD) method of analysis offers advantages in the solution process. A new way in which BDD models can be efficiently developed for phased mission analysis is proposed. The paper presents a methodology by which the phased mission models can be developed and analysed to produce the phase failure modes and the phase failure likelihoods.
Bayesian reliability demonstration for systems with redundancy
Authors: Rahrouh M , Coolen F. P. A. , Coolen-Schrijner P
Published: November 2006

Zero-failure testing for Bayesian reliability demonstration (BRD) is studied, aiming at minimal expected costs of testing and process failure. For the process after testing, reliability is formulated in terms of failure-free periods, based on the assumption that failure in the process would be catastrophic, causing the process to be discontinued and incurring high costs. BRD is considered for systems with redundancy, which are required to perform multiple independent types of task. Optimal BRD testing is also considered in combination with flexibility in the system redundancy, where more components can be installed to reduce test effort. Attention is restricted to systems with exchangeable components, with testing only at the component level. Generalizations are briefly discussed at the end of this paper.
Risk modelling of fires and explosions in open-sided offshore platform modules
Authors: Lewthwaite J. L. , Andrews J. D. , Dunnett S. J. , Gregory C. A. J. , Smith R
Published: November 2006

Incidents involving fires and explosions present a major hazard to the workforce on offshore oil and gas platforms. Following the Piper Alpha Disaster in 1988, platform operators for the UK sector are required to submit safety cases for approval by the Health and Safety Executive. A key requirement of these safety cases is that hazards associated with an accidental release of hydrocarbons have been demonstrated to be as low as reasonably practicable.

This paper aims to describe a process for estimating the expected number of fatalities on offshore platforms with open-sided modules using a Monte Carlo simulation method implemented within the safety and reliability of offshore structures (SAROS) software. The process involves estimation of the frequency and magnitude of jet fires, pool fires, and explosions. This is combined with the distribution of the workforce over the platform at the time of the incident to predict the risk of fatality.
Bitumen Surface Energy Characterization by Inverse Gas Chromatography
Authors: Hefer Arno W. , Little Dallas N. , Herbert Bruce E.
Published: November 2006

Modern surface energy theory has been identified in recent years as an attractive tool by which to select compatible bitumen-aggregate combinations. In addition, this approach offers the potential to quantitatively assess moisture susceptibility of these material combinations. The success of implementing this technology depends on the availability of techniques that allow efficient and reliable surface energy characterization of the materials under consideration. This paper focuses on bitumen surface energy characterization employing inverse gas chromatography (IGC). The authors report detail column preparation and test methodologies, and provide a precision statement for this technique. Analysis procedures and results presented demonstrate successful application of this technique with modern thermodynamic theory to acquire bitumen surface energy components. The technique allows testing at different temperatures and results are in agreement with conceptual and theoretical expectations. Surface energies derived from IGC compare reasonably well with mechanical surface tension values from the literature. Results suggest that surface energies do not vary considerably between different bitumen types, indicative of the controlling role of aggregate type in bitumen-aggregate adhesion.
Quasiperiodic-periodic structures by projection in two stages: an illustrative example
Authors: Quandt Alexander , Ben-Abraham Shelomo I.
Published: November 2006

Recently we have modified a two-stage variant of the cut-and-project method used to generate layered 8-fold (Ben-Abraham, 2004) and 12-fold (Ben-Abraham et al., 2004) quasiperiodic structures in three dimensions, and obtained 8-fold, 10-fold and 12-fold quasiperiodic structures via cut-and-project from various four dimensional lattices (Ben-Abraham and Quandt, 2006). However four dimensions are certainly not the most suitable playground to illustrate the basics of our general two-stage projection method. To this end we cut and project a periodic structure in three dimensions onto two-dimensional physical space, such that a second cut and projection onto a line yields a quasiperiodic structure. This simple example contains all of the basic elements of our two-stage projection method, but now the essential steps may directly be visualized.
The common role of water molecule and lone electron pair as a bond-valence mediator in oxalate complexes: the crystal structures of Rb2(C2O4) · H2O and Tl2(C2O4)
Authors: Echigo Takuya , Kimata Mitsuyoshi
Published: November 2006

The crystal structure of rubidium oxalate monohydrate, Rb2(C2O4) · H2O, has been refined using an imaging-plate diffractometer system and graphite-monochromatized MoK

α
radiation. The complex crystallizes in the monoclinic system, space group C2/c, with unit cell dimensions of a = 9.617(6), b = 6.353(5), c = 11.010(8) Å, β = 109.46(3)°, V = 634.2(8) Å3, and Z = 4. The structure was solved and refined to R = 0.026 for 2646 independent reflections [I
o > 2σ(I
o)]. In Rb2(C2O4) · H2O, oxalate anions [(C2O4)2–] and cations (Rb+) constitute a two-dimensional layered structure parallel to (001); interlayered water molecules (H2O)0 occupy a well-defined position and form hydrogen bonds to the layers to prop up the structure, where (H2O)0 is structurally an essential component. The relationship among the crystal structures of M2(C2O4) · nH2O (M = Li+, Na+, K+, Rb+, Cs+, Tl+, NH4
+, Ag+; n = 0, 1, 2) showed that ionic radii of the cations decide whether the corresponding oxalate complexes have water molecules or not. On the other hand, anhydrous thallium oxalate, Tl2(C2O4), has a similar structure to Rb2(C2O4) · H2O except for the water molecules. Tl+ cation exhibits stereochemical activity of its 6s2 lone electron pairs (LEP), which is absent from Rb+ in the latter oxalate. Comparison between interlayer spaces occupied by LEP and (H2O)0 in these two structures reveals the existence of the first uncharged substitution: 2 × LEP → (H2O)0, where the directions of the former occupants are opposite to each other, and nearly perpendicular to a dipole direction of the latter. In the layer sites of these two structures, two LEP of Tl+ seem to work like a dipole moment of the water molecule in Rb-oxalate monohydrate by shifting away from the nucleus to stabilize the structure of Tl2C2O4. The crucial role common to water molecules and LEP which acts as a bond-valence mediator in oxalate complexes is discussed quantitatively in terms of a valence-matching principle.
Synthesis and crystal structure of Sr(AsO3OH) and Ba(AsO3OH): crystal chemistry of related MHXO4 (X = As, P, S) compounds
Authors: Mihajlović Tamara , Effenberger Herta
Published: November 2006

Crystals of M(AsO3OH) (M = Sr and Ba) were synthesized under hydrothermal conditions; single-crystal X-ray structure investigations were performed. The average structure of Sr(AsO3OH) exhibits three crystallographically different hydrogen bonds; two of them are related by -1 symmetry [space group P-1, a = 7.349(2) Å, b = 7.057(2) Å, c = 7.460(2) Å, α = 95.20(3)°, β = 104.78(3)°, γ = 88.11(3)°, Z = 4]. Weak superstructure reflections were detected which are responsible for a larger cell volume [space group P-1, a = 9.038(2) Å, b = 11.732(2) Å, c = 15.356(3) Å, α = 71.66(3)°, β = 75.16(3)°, γ = 89.11(3)°, Z = 16]. All inversion centres restricting the hydrogen bonds are avoided in the super cell. As a result, a completely ordered atomic arrangement is obtained. The arsenate tetrahedra are linked by hydrogen bonds to polar chains with branches in [110] and [110], respectively; they are linked by the Sr atoms. The compounds CaHPO4 (monetite), CaHAsO4 (weilite), α-SrHPO4
α-NaHSO4, and HgHPO4 have roughly the same arrangements of the M(= Ca, Sr, Na, Hg) and X(= P, As, S) atoms; however their hydrogen-bonding schemas are principally different. For the detailed comparison, the non-standard unit cell was chosen for Sr(AsO3OH) [space group F-1, a = 14.697(3), b = 28.230(5), c = 14.920(3) Å, α = 95.20(3)°, β = 104.78(3)°, γ = 88.11(3)°, Z = 64]. The structural refinement of Ba(AsO3OH) confirmed isotypy with γ-Sr(PO3OH), K(SO3OH), and K(SeO3OH) [space group Pbca
a = 8.581(2), b = 9.896(2), c = 19.417(4) Å, Z = 16]. Sr(AsO3OH) and Ba(AsO3OH) are characterized by short (strong) hydrogen bonds.
Single crystal X-ray structure analysis of the spin ladder compounds SrCu2O3 and Sr2Cu3O5 between 300 K and 100 K
Authors: Sparta Karine , Löffert Achim , Gross Christoph , Aßmus Wolf , Roth Georg
Published: November 2006

This work presents room temperature single crystal X-ray diffraction measurements of the spin ladder compounds SrCu2O3 (Cmmm, a = 3.948(2) Å, b = 11.626(4) Å, c = 3.509(1) Å, Z = 2) and Sr2Cu3O5 (Immm, a = 3.395(2) Å, b = 3.941(1) Å, c = 18.662(5) Å, Z = 2), and the evolution of their structures from room temperature down to 100 K. We confirm the structure of SrCu2O3 previously described in the literature from X-ray powder and electron diffraction measurements, and report a new modification for Sr2Cu3O5 with an unusual CuO5 trigonal bipyramidal coordination.
New hybrid diphosphates Ln
2(NH2(CH2)2NH2)(HP2O7)2 · 4 H2O(Ln = Eu, Tb, Er): synthesis, single crystal and powder X-ray crystal structure
Authors: Capitelli Francesco , El Bali Brahim , Essehli Rachid , Lachkar Mohammed , da Silva Iván
Published: November 2006

Crystals of lanthanide ethylenediamine diphos phates Ln2
(NH2(CH2)2NH2)(HP2O7)2 · 4 H2O (Ln = Eu (1), Tb (2), Er (2)) have been synthesized and investigated by single crystal X-ray diffractometry (Eu and Tb phases) and by powder X-ray diffractometry (Er phase). The three structures resulted to be isostructural within triclinic space group P-1, with unit cell parameters of a = 6.5050(6) Å; b = 6.9990(2) Å; c = 9.8450(9) Å; α = 81.548(5)°; β = 80.631(19)°; γ = 88.369(9)°; V = 437.44(6) Å3
(1), a = 6.4360(7) Å; b = 6.9480(12) Å; c = 9.816(4) Å; α = 81.987(19)°; β = 80.595(16)°; γ = 88.591(13)°; V = 428.82(19) Å3
(2), a = 6.39658(2) Å; b = 6.86682(2) Å; c = 9.78849(3) Å; α = 81.6811(4)°; β = 80.2304(3)°; γ = 88.3812(3)°; V = 419.255(3) Å3
(3).The three-dimensional network is built up by the repetition of ab-parallel layers of LnO8 polyhedra corner-sharing with (HP2O7) groups; ethylenediamine molecules lie between such layers, acting both as receptors and donors in strong hydrogen bonds which assure the stabilizing of the entire framework.
Initiation of Maintenance Antiinflammatory Medication in Asthmatic Children in a Pediatric Emergency Department
Authors: Lehman Heather K. , Lillis Kathleen A. , Shaha Steven H. , Augustine Marilyn , Ballow Mark
Published: December 2006

BACKGROUND. Despite National Asthma Education and Prevention Program guidelines recommending the use of daily controller medication in patients with persistent asthma, less than half of children requiring emergency department treatment for asthma exacerbations are receiving antiinflammatory therapy.

OBJECTIVE. The purpose of this study was to evaluate a pediatric emergency department–based intervention designed to affect the prescribing practices of primary care physicians to better comply with national asthma guidelines. The intervention involved initiating maintenance antiinflammatory therapy in children with an asthma exacerbation who met guidelines for persistent disease but were not on antiinflammatory medications.

METHODS. Guardians of children 2 to 18 years of age presenting to the pediatric emergency department with an asthma exacerbation were asked to complete an asthma survey. Patients were classified into severity categories. Those with persistent disease not on antiinflammatory medications were given a 2-week supply of medication and were instructed to follow-up with their primary care physicians to obtain a prescription for the antiinflammatory medication. Patient adherence information was obtained through telephone calls, pharmacy claims data, and physician office records.

RESULTS. Forty-seven of 142 patients met criteria and were enrolled in the intervention. Seven patients were lost to follow-up. Of the remaining 40 patients, 28 followed-up with their primary care physician. Of these patients, 75% were continued on an antiinflammatory medication. Primary care physicians were significantly more likely to continue an antiinflammatory prescription in patients with severe persistent asthma (88.9% vs 68.4% of mild- or moderate-persistent asthmatics). Of the 28 patients who followed-up with their primary care physician, 13 had a prescription written, dispensed, and reported using the medication at the time of follow-up.

CONCLUSIONS. Pediatric emergency department physicians can successfully partner with primary care physicians to implement national guidelines for children requiring maintenance antiinflammatory asthma therapy. Patient nonadherence continues to be a significant barrier for asthma management.
Impact of Pediatric Critical Illness and Injury on Families: A Systematic Literature Review
Authors: Shudy Marysia , de Almeida Mary Lihinie , Ly Susan , Landon Christopher , Groft Stephen , Jenkins Tammara L. , Nicholson Carol E.
Published: December 2006

OBJECTIVE. We sought to inform decision-making for children and families by describing what is known and remains unknown about the impact of childhood critical illness and injury on families. This report also was designed as a tool for research planning and design so that meaningful studies are performed and duplication is avoided.

DESIGN. After a national scholarship competition and the identification of 3 medical student summer scholars, a literature search was conducted by using the National Library of Medicine and a PubMed keyword search system at the National Institutes of Health.

RESULTS. A total of 115 reports were reviewed and assigned to the 5 following categories characterizing the impact of pediatric critical illness/injury on families: stressors, needs, specific domains (psychological, physical, social), coping, and interventions. The reports reviewed indicate that pediatric critical illness and injury is stressful for the entire family. The effects on parents, siblings, and marital cohesion were variably described. Needs of family members (eg, rest, nutrition, communication) were identified as being unmet in many studies. Permanent impact on siblings and marital relationships has been considered detrimental, but these conclusions are not adequately quantified in presently available studies. Reviewed reports minimally investigated cultural diversity, effects on fathers versus mothers, siblings, socioeconomic status, and financial burden. Studies were often anecdotal and included small sample sizes. Methodologic limitations were numerous and varied and seriously narrowed the significance of the studies we reviewed. The reports that we evaluated were largely limited to those of English-speaking families, white people, and married mothers.

CONCLUSIONS. Future research should use more rigorous methods in the measurement of impact of childhood critical illness and injury on families. Families of critically ill and injured children would benefit from the practitioners of pediatric critical care acquiring enhanced knowledge and sensitivity about famliy communication and dynamics.
Direct Medical Costs of Bronchiolitis Hospitalizations in the United States
Authors: Pelletier Andrea J. , Mansbach Jonathan M. , Camargo Carlos A.
Published: December 2006

OBJECTIVES. Although bronchiolitis is the leading cause of hospitalization for infants, there are limited data describing the epidemiology of bronchiolitis hospitalizations, and the associated cost is unknown. Our objective was to determine nationally representative estimates of the frequency of bronchiolitis hospitalizations and its associated costs.

PATIENTS AND METHODS. We analyzed the 2002 Health Care Utilization Project-National Inpatient Sample, a federal, stratified random survey of hospital discharges. For admissions age <2 years with a discharge diagnosis of bronchiolitis (International Classification of Diseases, Ninth Revision, Clinical Modification, code 466.1), we used nationally representative weighted estimates to determine frequency and total hospital charges. Costs were estimated from reported charges by applying hospital-specific cost/charge ratios based on all-payer inpatient cost.

RESULTS. In 2002, an estimated 149000 patients were hospitalized with bronchiolitis. Frequency of hospitalizations was higher among children age <1 year of age, male gender, and nonwhite race. Mean length of stay was 3.3 days. Total annual costs for bronchiolitis-related hospitalizations were $543 million, with a mean cost of $3799 per hospitalization. Mean cost of bronchiolitis with a codiagnosis of pneumonia was $6191. In a multivariate analysis controlling for 3 confounding factors (including length of stay), cost per hospitalization was higher for children ≥1 year and lower for those in the South versus Northeast.

CONCLUSIONS. Bronchiolitis admissions cost more than $500 million annually. A codiagnosis of bronchiolitis and pneumonia almost doubles the cost of the hospitalization. Inpatient health care costs of bronchiolitis are higher than estimated previously and highlight the need for initiatives to safely reduce bronchiolitis hospitalizations and thereby decrease health care costs.
Epidemiology, Complications, and Cost of Hospitalization in Children With Laboratory-Confirmed Influenza Infection
Authors: Ampofo Krow , Gesteland Per H. , Bender Jeffery , Mills Michelle , Daly Judy , Samore Matthew , Byington Carrie , Pavia Andrew T. , Srivastava Rajendu
Published: December 2006

BACKGROUND. Influenza causes significant morbidity among children. Previous studies used indirect case ascertainment methods with little cost data. We sought to measure the burden of laboratory-confirmed influenza from hospitalized children.

METHODS. We conducted a retrospective cohort study during 3 viral seasons at Primary Children's Medical Center (Salt Lake City, UT). Children ≤18 years of age who were hospitalized with laboratory-confirmed influenza infection were included. Outcomes included hospitalization rates, complications including intensive care unit stays, mechanical ventilation, length of stay, and total hospital costs.

RESULTS. A total of 325 children had hospitalizations attributable to influenza over 3 viral seasons: 28% <6 months of age, 33% between 6 and 23 months of age; and 39% >2 years of age; 37% had high-risk medical conditions. Population-based rates of hospitalization for Salt Lake County residents ranged from 6.3 to 252.7 per 100000 children. The highest rates were in children younger than 6 months, and rates decreased with increasing age. Forty-nine (15%) children had an ICU stay; 27 required mechanical ventilation, and half of these patients were >2 years of age. Total hospital cost for the cohort was $2 million; 55% was accounted for by children >2 years of age. Length of stay and total hospital costs were significantly higher in all children >2 years of age compared with children <6 months of age and were comparable to all children 6 to 23 months of age.

CONCLUSIONS. Proven influenza infection in children results in substantial hospital resource utilization and morbidity. Nationwide, the median hospital costs may total $55 million. Our data support the Advisory Committee on Immunization's recommendations to expand the use of influenza vaccine to children >2 years of age.
Assessing Children’s Heart Sounds at a Distance With Digital Recordings
Authors: Finley John P. , Warren Andrew E. , Sharratt Geoffrey P. , Amit Minoli
Published: December 2006

OBJECTIVE. The objective of this study was to assess whether computer-stored digital sound recordings can be used to distinguish innocent from pathologic systolic murmurs.

METHODS. Recordings of 55 children aged 1 month to 19 years were made remotely with the use of a digital stethoscope and were e-mailed to a computer in our center for later assessment. Eight-second recordings were made by a physician in 2 to 4 locations on the chest. Three cardiologists who were blinded to the diagnosis reviewed the recordings independently using stethophones to assess the splitting of the second heart sound and whether murmurs were innocent or pathologic. Diagnoses were confirmed with echocardiography.

RESULTS. Seventeen children had innocent murmurs and 38 had pathologic murmurs. For the 3 cardiologists, sensitivity was 0.87 to 1.0, specificity was 0.82 to 0.88, negative predictive value was 0.75 to 1.0, and positive predictive value was 0.93 to 0.95. Assessment of splitting of second heart sound was highly accurate.

CONCLUSIONS. Digital recordings of children’s heart sounds allow reliable differentiation between innocent and pathologic murmurs. Use of this technology may allow remote diagnosis of childhood murmurs and avoid the expense and stress of travel to pediatric cardiology centers for some children. Cardiologists who use recordings should assess their diagnostic accuracy before clinical application.
Tracking Trichophyton tonsurans Through a Large Urban Child Care Center: Defining Infection Prevalence and Transmission Patterns by Molecular Strain Typing
Authors: Abdel-Rahman Susan M. , Simon Steve , Wright Krista J. , Ndjountche Liliane , Gaedigk Andrea
Published: December 2006

OBJECTIVES. Trichophyton tonsurans is the single most common cause of pediatric dermatophytoses in North America and is observed with increasing frequency in other countries. This investigation was designed to gain insight into the natural course of T tonsurans infection.

PATIENTS AND METHODS. This 2-year prospective, longitudinal study evaluated all preschool-aged children attending a single child care center. Scalp cultures were collected monthly from each child in attendance, and the presence of disease symptoms recorded at each visit. Dermatophyte genotype was assigned based on the combination of stable sequence variations (2 length variants, 8 single-nucleotide polymorphisms, a 10-base pair insertion, a 14-base pair deletion) present in 2 gene loci.

RESULTS. A total of 3541 scalp cultures were collected from 446 children during 24 months. Twenty-two percent to 51% of scalp cultures per month were positive, contributing 1390 fungal cultures of which 1048 were typeable. Among children with multiple typeable isolates, 51% exclusively carried the same strain, 37% demonstrated a single predominant strain with secondary strains transiently acquired, and 12% harbored a different strain of T tonsurans with each typeable culture. The probability that the same strain persisted in subsequent months was 0.898 and unlikely to have arisen by chance. Rates of symptomatic disease were significantly different between exclusive, predominant, and transient carriers of T tonsurans.

CONCLUSIONS. In contrast to dermatophyte infections in older individuals, where symptomatic disease seems to be a consequence of pathogen acquisition and carriers can be traced to an index case, in this preschool-aged population infection was endemic, and symptomatic disease seemed to represent activation of a single strain that persisted on the scalp.
A Logistic Regression Model for Predicting the Upstream Extent of Fish Occurrence Based on Geographical Information Systems Data
Authors: Fransen Brian R. , Duke Steven D. , McWethy L. Guy , Walter Jason K. , Bilby Robert E.
Published: November 2006

Regulations governing human activities in streams and riparian zones frequently differ depending on whether or not a stream reach supports fish. Fish presence or absence is usually determined by sampling or by assuming the presence of fish if the stream exhibits certain physical characteristics. Field surveys of fish occurrence in streams are time consuming and expensive. Inference of fish presence from simple thresholds of physical attributes, such as gradient or channel width alone, is inaccurate. We attempted to improve the accuracy and efficiency of this determination by developing a geographical information systems (GIS)-based predictive model. A 10-m digital elevation model incorporated field data on fish distribution from 517 streams in western Washington State and GIS-derived representations of the physical characteristics of stream networks. A model predicting the upstream extent of fish occurrence was derived using logistic regression models coupled with a heuristic “stopping rule.” Candidate variables included stream gradient, upstream basin area, elevation, and mean annual precipitation. When assessed against independent survey data, 91.9% of the occupied fish habitat was correctly classified by the model. Errors were generally small, but occasional large errors did occur and were most frequently associated with barriers to fish movement. Smaller errors occurred in marginal habitats, streams of low topographic relief, and streams that originated from headwater ponds. Use of this type of model, coupled with targeted field survey in areas most likely to be associated with model error, would greatly improve the efficiency and accuracy of current classification schemes.
Emigration of Fish from Two South Carolina Cooling Reservoirs
Authors: Paller M. H. , Fletcher D. E. , Standora M. M. , Grabowski T. B. , Jones T. A. , Dyer S. A. , Isely J. J.
Published: November 2006

We assessed fish escapement from two South Carolina reservoirs, Par Pond and L Lake, from spring 2002 through summer 2003. Escapement was greatest in the spring and early summer, with lake chubsucker Erimyzon sucetta dominating the escapement catch in early spring and several sunfishes Lepomis spp. dominating in late spring and early summer. Most of the escaping centrarchids were bluegill L. macrochirus, warmouth L. gulosus, and redbreast sunfish L. auritus in L Lake and warmouths, bluegills, dollar sunfish L. marginatus, and spotted sunfish L. punctatus in Par Pond. Escapement was enhanced by high reservoir water levels and surface discharge over the spillway. Escapement declined during periods of hypolimnetic release from bottom discharge gates. Location of the Par Pond discharge structure in the littoral zone rather than the pelagic zone as in L Lake contributed to greater escapement of littoral species in Par Pond. Species composition in the escapement catches and reservoirs was not significantly correlated. Relatively low escapement from L Lake and Par Pond compared with that in other reservoirs may have been related to the configuration of the discharge structures, low water levels during 2002, fish habitat preferences, species composition and abundance in the reservoirs, and low rates of discharge.
Linking Angling Catch Rates and Fish Learning under Catch-and-Release Regulations
Authors: Askey Paul J. , Richards Shane A. , Post John R. , Parkinson Eric A.
Published: November 2006

Many recreational fisheries are subject to varying degrees of catch-and-release fishing through regulations and conservation-minded anglers. Clearly, releasing a proportion of the catch improves conservation of the fishery, yet it is not clear how the released catch contributes to angling quality. If fish change their behavior to lower their individual catchability after they have been caught, then angler catch rates may not be proportional to fish density. Therefore, even catch-and-release fisheries could exhibit poor angling quality if there is sufficiently high angler effort. We tested this idea by experimentally fishing five small lakes that contained rainbow trout Oncorhynchus mykiss in the interior of British Columbia. We found that with sustained effort of 8 angler-hours · d−1 · ha−1 and complete release of the catch, catch rates quickly dropped within 7–10 d. Given the individual capture histories of tagged fish, the most parsimonious catchability model incorporated learning and heterogeneity into intrinsic catchability. The best-fit parameter values suggest that the population contained a group of highly catchable fish that were quickly caught and then learned to avoid hooks. There was a seasonal decrease in catchability that was independent of angling; however, it was not sufficient to explain the data. Our results indicate that catch rates may decline because of high angling effort even when the number of fish remains constant. Therefore, management goals that go beyond conservation issues and attempt to maximize angler satisfaction must account for effort density on a recreational fishery.