bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling and Optimization of Composite Rectangular Reciprocating Seals
Authors: Nikas G. K. , Sayles R. S.
Published: July 2006

A computational model of rectangular reciprocating seals, previously developed for elastomeric seals, has been extended to cover the mechanics and elastohydrodynamics (EHD) of composite seals comprising two polytetrafluoroethylene (PTFE) and one central elastomeric part, chemically bonded together. The model is demonstrated on a rotary vane actuator application and shown to produce realistic results regarding the contact pressure, film thickness, leakage, hydrodynamic friction force, and seal extrusion. Total computational time is very short, typically up to five hundredths of a second (0.05 s) on a 1.5 GHz personal computer. The main purpose of the model is the analysis and optimisation of said composite seal such that it outperforms the elastomeric seal (of exactly the same dimensions) in terms of leakage, hydro-dynamic friction, and extrusion in a wide range of operating conditions. For this goal, the PTFE-to-seal volume ratio of the composite seal is initially varied between zero and 90 per cent, and the results on leakage, hydrodynamic friction force, average film thickness in the sealing contact, and extrusion length of the composite seal are plotted and compared with those of the elastomeric seal for nominal operating conditions at three temperatures (−54, +22, and +99 °C) and for both flooded and starved lubricating conditions in order to find a first approximant to the optimum PTFE-to-seal volume ratio that gives the composite seal better overall sealing performance. Then, using the selected approximant of the optimum ratio, a parametric study is performed to compute the effects of seal interference (proportional to contact pressure), contact velocity, seal corner radius, and degree of lubricant starvation of the sealing contact on leakage, friction, and seal extrusion at the previously mentioned three temperatures for both flooded and starved contacts, thus establishing the regions of operating conditions and design parameters that benefit one seal or the other. It was found that, overall, the composite seal, despite a small (insignificant) disadvantage on leakage, significantly outperformed the elastomeric seal in terms of hydrodynamic friction and extrusion. Further optimization is possible, depending on performance priorities (for example, if leakage is valued more than friction, or wear more than leakage, etc.).
Reynolds Equations for Common Generalized Newtonian Models and an Approximate Reynolds-Carreau Equation
Authors: Bair S , Khonsari M. M.
Published: July 2006

Exact, closed-form, one-dimensional Reynolds equations are presented for the Ostwald-DeWaele model, the Ellis model, the Spriggs model, and the double-Newtonian Rabinowitsch and Ferry models. From numerical solutions for flowrate, an approximate Reynolds-Carreau equation is obtained. These models describe the wide range of constitutive shear responses that have been observed in lubricants at elevated pressure. It is hoped that the equations presented here will enable researchers to perform full elastohydrodynamic lubrication (EHL) simulations of the coupled elasticity and Reynolds equations for shear-thinning liquids.
Design Compensation for Fabrication Imperfections of Tuning-Fork Gyroscopes
Authors: Poreddy S , Pai P F , Feng Z C
Published: July 2006

Microelectromechanical systems (MEMS) gyroscopes consist of proof masses that are driven to vibration. The sensing of angular motion requires certain symmetry in the driven motion. This symmetry is destroyed by imperfections introduced during the device fabrication. Strategies at the design stage that can compensate for the effect of fabrication imperfections are proposed. Our analyses are conducted through a discrete coupled oscillator model. The results are further verified through a finite element model of a tuning-fork microgyroscope design.
Synthesis, Structure, and Reactivities of cis-Dimethyl(η1-allyl)gold(III) Complex. Diastereoselective Allylation of Aromatic Aldehyde
Authors: Sone Takuo , Ozaki Satoshi , Kasuga Noriko C , Fukuoka Atsushi , Komiya Sanshiro
Published: July 2006

cis-Dimethyl(η1-allyl)(triphenylphosphine)gold(III), cis-[AuMe2(η1-allyl)(PPh3)] (η1-allyl = allyl (1), crotyl (2), methallyl (3)) has been synthesized by reaction of cis-[AuMe2X(PPh3)] (X = I, NO3) with corresponding Grignard reagents. X-Ray structure analysis of 2 shows that 2 has a typical square planar cis configuration and the crotyl ligand binds to Au by η1-mode: orthorhombic, space group P212121, a = 9.816(2), b = 23.208(4), c = 9.5290(9) Å, Z = 4, R(Rw) = 0.037(0.041) with use of 2551 reflections. Reactions of 2 with HCl and Br2 selectively give 1-butene and 3-bromo-1-butene, respectively, indicating γ-regioselectivity of the reactions. Compounds 1—3 react with aldehydes and ketones to give the corresponding homoallyl alcohols. C–C bond formation also takes place at the γ-position of η1-allyl moiety selectively. The rate of the allylation reaction of carbonyl compounds decreases in the order of methallyl (3) > allyl (1) > crotyl (2) gold(III) complexes. The homoallyl alcohol formed by the reaction of 2 with benzaldehyde is a diastereoisomeric mixture of 2-methyl-1-phenyl-3-buten-1-ol, with high anti selectivity. Both the reaction rate and anti selectivity in the allylation reaction were reduced by addition of tertiary phosphines such as PPh3 and PCy3, and a 6-membered transition state has been proposed, which indicates coordination of the carbonyl group to a T-shape Au intermediate produced by dissociation of the PPh3 ligand.
Effect of Heat and Gases on the Photoluminescence of CdS Quantum Dots Confined in Silicate Glasses Prepared by the Sol–Gel Method
Authors: Fujii Tsuneo , Hisakawa Yuichiro , Winder Edmund J , Ellis Arthur B
Published: July 2006

The effects of heat (130, 200, and 600 °C) and added gases (NH3 and SO2) on the photoluminescence of CdS particles prepared by the sol–gel method were examined in order to elucidate the influence of the chemical environment on photoluminescence. Green and red photoluminescence (PL) were observed in non-heated samples. Exposure of the added gasses to the samples caused characteristic decreases of the green and red PLs. The intensity ratio of the green PL to that of the red PL for a 600-R sample (heated at 600 °C in H2S) showed a reversible behavior against exposure to SO2. These results indicate that there is adduct formation between CdS and SO2. The PL changes were fitted to the Langmuir adsorption isotherm model, and yielded the adduct formation constants. There are three emitting and three final states in the specimen.
Theoretical Study of the Transition Energies of the Visible Absorption Spectra of [RhCl6]3− and [RhCl5(H2O)]2− Complexes in Aqueous Solution
Authors: Endo Kazunaka , Saikawa Masahiko , Sugimoto Manabu , Hada Masahiko , Nakatsuji Hiroshi
Published: July 2006

Electron absorption spectra of [RhCl6]3− and [RhCl5(H2O)]2− complexes are studied theoretically by the ab initio symmetry adapted cluster (SAC)/SAC-CI method. Two maximum peaks of the visible absorption spectra in the range of 300—600 nm observed in aqueous solution are assigned to (1T1g; 1T2g) and mixing-(1B1, 1A2, 1B2; 2B1, 2A2, 2B2) states for [RhCl6]3− and [RhCl5(H2O)]2− complexes, respectively, in good agreement. These states are due to the forbidden d–d transitions from the Rh(dπ) + Ligand(pπ) bonding MOs to the Rh(dσ)-Ligand(pσ) antibonding MOs, leading to an weakening of the metal–ligand bonds.
Synthesis and Ion-Exchange Behavior of a New Three-Component Ion-Exchange Material: Zirconium(IV) Arsenate Vanadate
Authors: Qureshi Saidul Zafar , Khan Mubeen Ahmad , Rahman Nafisur
Published: July 2006

Zirconium(IV) arsenate vanadate was prepared by adding a mixture comprising 0.05 M sodium hydrogen arsenate and 0.05 M sodium metavanadate to an aqueous solution of zirconium(IV) dichloride oxide (0.05 M) in different volume ratios at pH 1. The material possessed a good ion-exchange capacity of 1.20 and 1.30 meq g−1 of exchanger for the Na+ and K+ ion, respectively, and was fairly stable in dilute mineral acids, but insoluble in water, acetic acid, formic acid, ethanol, and 1,4-dioxane. The distribution coefficients of a large number of metal ions were determined in different solvent systems.
Preparation and Characterization of Mononuclear Palladium(II) and Dinuclear Palladium(I) Complexes Containing a New Phosphine-Imine-Type Didentate Ligand, 8-(Dimethylphosphino)quinoline (Me2Pqn). Molecular Structures of cis-[Pd(Me2Pqn)2](BF4)2 and [Pd2Cl2(Me2Pqn)2]
Authors: Suzuki Takayoshi , Kashiwabara Kazuo , Fujita Junnosuke
Published: July 2006

A new phosphine ligand, 8-(dimethylphosphino)quinoline (Me2Pqn), and its palladium(I or II) complexes, [PdX2(Me2Pqn)] (X = Cl (1a), Br (1b), and I (1c)), [Pd(Me2Pqn)2](BF4)2 (2b), and [Pd2Cl2(Me2Pqn)2] (3), have been prepared and characterized. The structures of 2b and 3 have been determined by X-ray analysis. The crystal data and final R values are: for 2b, FW = 658.42, monoclinic, P21/n, a = 17.453(2), b = 10.453(2), c = 14.928(2) Å, β = 105.63(1)°, V = 2622.8(5) Å3, Dx = 1.667 Mg m−3, and Z = 4, R = 0.071 for 3908 reflections (|Fo| ≥ 3σ(|Fo|)); for 3, MW = 662.64, monoclinic, P21/n, a = 16.429(1), b = 12.191(1), c = 12.821(1) Å, β = 92.673(8)°, V = 2565.1(4) Å3, Dx = 1.714 Mg m−3, and Z = 4, R = 0.056 for 5136 reflections (|Fo| ≥ 3σ(|Fo|)). In 2b the square coordination plane formed by two long Pd–N (2.138(9) and 2.135(8) Å) and two Pd–P bonds (2.243(3) and 2.237(3) Å) is slightly distorted towards tetrahedral geometry, the dihedral angle between the two chelate planes formed by the Pd, P, and N atoms being 10.3(2)°. 3 is a dinuclear complex with a Pd–Pd bond (2.542(1) Å), Me2Pqn chelates to one Pd(I) center, and the N donor atom occupies the trans position to the Pd–Pd bond. The dihedral angle between the two coordination planes linked by the Pd–Pd bond is nearly a right angle, 82.13(6)°.
Chemistry of Organo Halogenic Molecules. 140. Role of the Reagent Structure on the Transformations of Hydroxy Substituted Organic Molecules with the N-Fluoro Class of Fluorinating Reagents
Authors: Zupan Marko , Iskra Jernej , Stavber Stojan
Published: July 2006

Hydroxy-substituted organic molecules were used as target molecules in investigations of the role of the reagent structure on the reactivity of three types of N–F class fluorinating reagents: 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) F-TEDA (1a), N-fluorobis(phenylsulfonyl)amine NSF (1b), and N-fluoropyridinium heptafluorodiborate–pyridine (1/1) NFP (1c). Methanol is stable, but hydroquinone is very quickly transformed in acetonitrile to quinone with F-TEDA at room temperature; on the other hand, NSF is less reactive, while oxidation with NFP is achieved only at an elevated temperature; a structure variation of the hydroquinone derivatives did not influence oxidation. Fluorination was achieved with monohydroxy-substituted aromatic compounds; a similar trend concerning the reactivity of N–F reagent (1) was also observed in reactions with 1- and 2-naphthol, while 9-phenanthrol gave 10,10-difluoro-9-(10H)-phenanthrenone with F-TEDA in acetonitrile and 9,10-phenanthrenequinone with NSF. Dealkylation was observed in a reaction with 4-methoxyphenol; although the thio analogue gave bis(4-methoxyphenyl) disulfide, the reactivity was changed and NSF was more reactive than F-TEDA and NFP.
Laser Flash Photolysis in High-Speed Photopolymer Coating Layers
Authors: Urano Toshiyuki , Nagasaka Hideki , Tsuchiyama Masaaki , Shimizu Shigeki , Kawazoe Katsurou , Shimizu Makoto , Yamaoka Tsuguo
Published: July 2006

The sensitization mechanisms of two systems of ketocoumarin dyes with a radical-generating reagent (10,10′-carbonylbis[1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano [6,7,8-ij]quinolizin-11-one] (KCD-J), 3,3′-carbonylbis]7-(diethylamino)coumarin] (KCD-DA) with 3,3′,4,4′-tetrakis(t-butyldioxycarbonyl)benzophenone (I) in poly(methylmethacrylate) film) and of two systems of coumarin dyes (10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one (CD-J), 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (CD-DA) with I in the film) have been investigated by laser flash photolysis using a total-reflection cell. The fluorescence of the dyes was efficiently quenched by I with static quenching distances of 8.1, 8.6, 15.0, and 10.9 Å for KCD-J, KCD-DA, CD-J, and CD-DA. The decay time of the triplet was moderately quenched by I with a quenching rate (kq) of 5.8 × 105 mol−1 dm3 s−1 for KCD-DA, and slightly with a kq of less than 1 × 105 mol−1 dm3 s−1 for KCD-J; none of the triplet was detected on CD-J and CD-DA. These results suggested that a static sensitization from the fluorescent-excited dyes to I is predominant in photoinitiation systems.
Reaction of Ketene Alkyl Trimethylsilyl Acetals with Dimethyl Acetylenedicarboxylate Catalyzed with Zirconium Tetrachloride
Authors: Mitani Michiharu , Sudoh Takahiro , Koyama Kikuhiko
Published: July 2006

When dimethyl acetylenedicarboxylate is reacted with ketene alkyl trimethylsilyl acetals in the presence of a catalytic amount of zirconium tetrachloride, dimethyl 2-alkoxycarbonyl-3-alkylidenebutanedioates are afforded. Although the silyl enol ether from acetophenone undergoes the same type of reaction, other trisubstituted silyl enol ethers such as those from butyrophenone and 3-pentanone fail to react with dimethyl acetylenedicarboxylate under these conditions.
A Facile and Quantitative Preparation of Activated Cyclic Sugar Derivatives Using HgBr2 and 2,4,6-Collidine
Authors: Matsuoka Koji , Nishimura Shin-Ichiro , Lee Yuan C
Published: July 2006

A combination of mercury(II) bromide (HgBr2) and 2,4,6-collidine was found to promote the formation of activated cyclic sugar derivatives such as 1,2-orthoesters and an oxazoline derivative in quantitative yields at room temperature. A slightly hindered skew like conformation of the lactose orthoester derivative was revealed by 1H NMR analysis. It was also suggested that the reaction of a lactose 1,2-orthoester with trimethylsilyl azide proceeded smoothly to give β-lactosyl azide stereoselectively which is a useful intermediate for constructing glycopeptides and neoglycoconjugates.
Stereospecific Acetolysis of threo- and erythro-2-Aryl-2-[1-(methylthio)ethyl]oxiranes
Authors: Miyauchi Hiroshi , Nakamura Toshio , Ohashi Naohito
Published: July 2006

Threo-2-aryl-2-[1-(methylthio)ethyl]oxiranes (1a—d) were reacted with acetic acid to give two types of unexpected ring-opening products, threo-1-acetoxy-2-aryl-3-methylthio-2-butanols (4a—d) and mono-O-acetyl derivatives of threo-2-aryl-2-methylthio-1,3-butanediol (5a—d and 6a—d). On the other hand, erythro-2-aryl-2-[1-(methylthio)ethyl]oxiranes (2a—d) gave erythro-1-acetoxy-2-aryl-3-methylthio-2-butanols (7a—d) and mono-O-acetyl derivatives of erythro-2-aryl-2-methylthio-1,3-butanediol (8a—d and 9a—d). It is suggested that these products are generated from thiiranium ionic intermediates, because they all completely retain the relative configuration of the starting oxiranes.
Stoichiometric Oxidation of Benzene to Phenol with Copper(II) Salts
Authors: Mori Miki , Nakai Toshihiro , Yahiro Hidenori , Nitta Masahiro , Sasaki Kazuo
Published: July 2006

Phenol is readily produced by some stoichiometric reactions of benzene with certain copper(II) salts. The main part of the reaction using copper(II) sulfate is estimated to be expressed by the following equation:

This reaction was carried out in a flow system at 300 °C, where a vapor mixture of benzene and water flowed through a packed bed of copper(II) sulfate supported on silica gel. The products were mainly phenol and CO2 with a trace amount of biphenyl. The phenol yield became appreciable at temperatures higher than 250 °C, and reached a maximum at ca. 300 °C. At higher temperatures, the CO2 yield increased along with the consumption of phenol. The percentage yield of phenol based on copper(II) salt was 86% at the highest. Although copper(II) phosphate was similarly useful, it required a higher reaction temperature (ca. 500 °C).
Cost Benefit with Early Operative Fixation of Unstable Ankle Fractures
Authors: Pietzik P , Qureshi I , Langdon J , Molloy S , Solan M
Published: July 2006

INTRODUCTION

Ankle fractures are common and many require surgical intervention. It has been well documented that a delay in fracture fixation results in increased length of hospital stay and increased complication rate. Initial delay can also allow swelling or blistering to develop which may necessitate a further delay in operative fixation for up to 1 week. The aim of the current study was to review the length of hospital in-patient stay for operative ankle fractures over the previous 12-month period at our hospital and compare this to the length of hospital stay following the introduction of a fast-track system for the fixation of these fractures (all fractures fixed within 48 h).

PATIENTS AND METHODS

A retrospective review of all ankle fractures managed by open reduction and internal fixation over a 12-month period was undertaken. A protocol was then agreed to openly reduce and fix these fractures at the earliest possible opportunity over the next 6-month period. We then collected the data on all ankle fractures that needed open reduction and internal fixation over this 6-month period. The pre-protocol and post-protocol groups were then compared for total hospital length of stay and complication rate.

RESULTS

In the 12-month retrospective review, there were 83 ankle fractures that required surgical intervention. Sixty-two of these had surgery within 48 h (mean length of stay, 5.4 days), and 21 had surgery after 48 h (mean length of stay, 9.5 days). There were 39 ankle fractures in the post-protocol group who all had surgery within 48 h (mean length of stay, 5 days). There was no increase in complication rate after implementation of the fast-track system.

CONCLUSIONS

This study shows that early operative intervention for ankle fractures reduces the length of hospital stay. Intensive physiotherapy and co-ordinated discharge planning are also essential ingredients for early discharge. Early operative fixation for unstable ankle fractures has substantial cost-saving implications with no increase in complication rate.
Ball Bearing (BB) Guns, Ease of Purchase and Potential for Significant Injury
Authors: Grocock C , McCarthy R , Williams DJ
Published: July 2006

INTRODUCTION

Ball bearing guns are used in the UK for war games, but they have the potential to cause severe injury if used incorrectly.

MATERIALS AND METHODS

A search was made for availability of these weapons, the ease of purchase and the potential for tissue damage.

RESULTS

These weapons are widely available on the Internet and are easy to purchase with no security checks. Once fully charged, an electric BB gun is capable of penetrating a cadaveric animal model at distances up to 5 m (1 m = 25 mm penetration, 3 m = 20 mm penetration, 5 m = 15 mm penetration).

CONCLUSIONS

BB guns are not toys and have a significant potential to cause injury.
Left Internal Mammary Artery Usage in Coronary Artery Bypass Grafting: A Measure of Quality Control
Authors: Karthik S , Fabri BM
Published: July 2006

INTRODUCTION

Over the last two decades, many studies have shown better long-term patency rates and survival in patients undergoing coronary artery bypass grafting (CABG) with left internal mammary artery (LIMA) to the left anterior descending artery (LAD). World-wide, LIMA is accepted as the ‘gold standard’ for surgical revascularisation and its usage has been steadily increasing.

PATIENTS AND METHODS

Between April 1997 and September 2001, a total of 4406 consecutive patients underwent coronary artery bypass grafting with revascularisation to the left anterior descending artery.

RESULTS

Of the study group, 4047 (91.8%) patients received LIMA to LAD, leaving 359 (8.2%) who did not. Six sub-groups of patients in whom LIMA usage was significantly less were the elderly (> 70 years of age), females, diabetics, patients having emergency CABG, poor left ventricular (LV) function (ejection fraction [EF] < 30%) and patients with respiratory disease.

CONCLUSIONS

Although the current focus in the UK is on mortality rates, we believe that it will not be long before this will also include the incidence of major morbidity after CABG such as stroke, myocardial infarction (MI), renal failure and sternal wound problems. We also believe that we should now consider LIMA usage as a marker of quality control after CABG.
Spontaneous Tooth Exfoliation, Maxillary Osteomyelitis and Facial Scarring following Trigeminal Herpes Zoster Infection
Authors: Pillai Kamala G , Nayar Kavitha , Rawal Yeshwant B
Published: July 2006

A case of trigeminal herpes zoster (HZ) infection affecting the left maxillary and ophthalmic divisions of the fifth cranial nerve in an immuno-competent patient is presented. Extremely rare complications such as osteonecrosis, spontaneous tooth exfoliation, secondary osteomyelitis and facial scarring were observed. Sequestrectomy, aciclovir and erythromycin stearate were effectively used in managing the case.
An In-Vitro Study of Microleakage Around Class V Cavities Bonded with a Self-Etching Material Versus a Conventional Two-Bottle System
Authors: Salim Sinan , Santini Ario , Husham Alyaa
Published: July 2006

Objective

To evaluate the microleakage around class V restorations restored with either a self-etching adhesive system or a conventional two-bottle adhesive system used with ‘total etch’ technique, and their recommended resin-based composites (RBC).

Methods

Two types of adhesive systems were used. A self-etching adhesive, Etch and Prime 3.0 (Degussa AG, Hanau, Germany), and a conventional two-bottle adhesive, Gluma Solid Bond (Heraeus Kulzer, Dormagen, Germany). The bonding systems were used in strict accordance with the manufacturers’ instructions, except that, with the two-bottle adhesive system, the cavities were filled with either a ‘wet’ or a ‘dry’ bonding technique, subsequent to acid-etching with 20% phosphoric acid. Etch & Prime 3.0 was used in conjunction with Degufill Mineral (Degussa, Hanau, Germany) RBC and Gluma Solid Bond with Flow Line RBC (Heraeus Kulzer, Dormagen, Germany). Standardised bucco-cervical cavities were prepared on the buccal and lingual surfaces of 15 extracted maxillary first premolar teeth; all cavity margins were in enamel. Ten of the resulting cavities (Group A) were restored using Etch & Prime 3.0 and Degufill Mineral, ten (Group B) using Gluma Solid Bond (Wet Bond), and ten (Group C) using Gluma Solid Bond (Dry Bond). Leakage scores at occlusal and gingival margins were calculated after thermocycling 500 times between baths, held at 5°C and 55°C, respectively, with 30 seconds dwell time in both. Data were analysed by the Fisher Exact Test.

Results

There was no statistically significant difference between the self-etching adhesive and conventional two-bottle adhesive systems at either the occlusal or the gingival margins. With the self-etching adhesive, there was no statistically significant difference in leakage scores between occlusal and gingival margins. There was a statistically significant difference between the occlusal and the gingival margins when a ‘wet’ or ‘dry’ bonding technique was used with the conventional two-bottle adhesive system.

Conclusions

The results suggest that the application of a conventional two-bottle bonding system used with a ‘total etch’ technique is better than that of a self-etching adhesive system. With the former, the use of a ‘wet’ bonding does not give better results than a ‘dry’ bonding technique.
Pharmaceutical Prescribing for Children
Authors: Hosey Marie Therese , Fayle Stephen , Palmer Nikolaus OA
Published: July 2006

This is the fifth paper in a series on the prescribing of medicines for children by dentists working in primary dental care. It deals with conscious sedation for children.
Training Standards in Implant Dentistry for General Dental Practitioners. A Report
Authors: Martin Michael V
Published: July 2006

In December 2005, the General Dental Council (GDC) convened a small working group to consider training standards for general dental practitioners (GDPs) who wish to practise implant dentistry. The membership of this group is given at the end of this report. The secretariat for the group was provided jointly by the GDC and the Faculty of General Dental Practice (UK). The remit of the group (which was independent of any organisation) was to consider what training standards would be necessary for a GDP before practising implant dentistry, to publish those standards, and then periodically to review them in the light of developments in implant dentistry. Such standards can be used not only by practitioners but also by the GDC in the consideration of patient complaints against dental practitioners who, allegedly, practise implant dentistry beyond the limits of their competence.
Changing World of Neuroscience and Clinical Practice: A Personal Perspective Part 2 — Adult Brain Injury
Authors: Ewing Jan
Published: July 2006

In the previous issue of Brain Impairment, Ewing (2006) described developments in the knowledge base underpinning clinical neuropsychology and implications for paediatric brain injury. This article discusses new research regarding post-injury recovery in the adult brain and its implications for clinical practice.
Oxidation Testing of Long-Life Turbine Oil Fluids. Can We Do Better?
Authors: Chasan DE , DiFrancesco SR , Ribeaud M
Published: July 2006

Four turbine oils formulated with varying types and concentrations of antioxidants were aged via D 943 exposure and examined extensively at 1000, 2000, 5000, and 10 000 h. Acid number, Rotary Pressure Vessel Oxidation Test (RPVOT), High Pressure Differential Scanning Calorimetry (HPDSC)RP, and sludge determinations were made at each time interval. Only a combined evaluation of the test results for the 10 000 h oil samples (a “Total Oxidation Products” approach) gave a reasonable estimation of the true oxidative state of the fluids. One shorter term test, ASTM D 6514, was found to give a fair prediction of the overall quality of the fluids at 10 000 h.
ASTM G 175 Interlaboratory Study on Forced Ignition Testing
Authors: Smith SR , Stoltzfus JM
Published: July 2006

ASTM G 175 is a standard test method for evaluating the ignition sensitivity and fault tolerance of oxygen regulators used for medical and emergency applications. To show the ASTM G 175 test method was repeatable at different laboratories, a series of interlaboratory tests were performed on medical oxygen regulators in late 2002. These tests were performed on six regulator designs at three laboratories. Three of the regulator models employed a compressed gas association (CGA) 870-style connection and the other three regulator models used a CGA 540-style connection. Five of the regulators were commercially available and the other one was a CGA 870-style regulator that was intentionally designed to tail the test. The results of the round robin tests are presented and discussed.
Binary rare earth Laves phases — an overview
Authors: Gschneidner, Jr. Karl A. , Pecharsky Vitalij K.
Published: July 2006

The rare earth metals form the largest subset of the AB
2 Laves phase compounds. The rare earth element (R) is always the larger A metal, and they form Laves phases with most of the Group 7–10 elements, plus Mg and Al. As with all Laves phases, the rare earth RB
2 compounds conform with the size rule which had been established in the mid 1930s. Electron concentration effects have also been observed in the RB
2 phases. A number of anomalies and unusual behaviors have been discovered over the years: the La deficiency in “LaNi2” and of R in other “RNi2” Laves phase compounds; the crystal structure sequence in the RMn2 compound series; the relationship between the Debye temperature and the radius ratio; the Ce valence in the CeB
2 compounds; and the thermodynamic nature of the magnetic transition in the RCo2 phases.
High-pressure crystal chemistry of binary intermetallic compounds
Authors: Demchyna Roman , Leoni Stefano , Rosner Helge , Schwarz Ulrich
Published: July 2006

Effects of high pressure on intermetallic compounds are reviewed with regards to structural stability and phase transitions. Changes of bonding properties and electronic structure are examplified by means of the elemental metals caesium and titanium, the latter forming an internal intermetallic compound at high pressures. After a short systematic overview regarding pressure effects, structural transformations in selected classes of intermetallic compounds like Zintl phases and AlB2-type arrangements precedes sections concerning high-pressure synthesis of Laves phases and intermetallic clathrates.
The effect of transition metal doping on thermal conductivity of YB66
Authors: Tanaka Takaho , Kamiya Koji , Numazawa Takenori , Sato Akira , Takenouchi Satoshi
Published: July 2006

The effect of transition metal doping in YB66 has been studied with respect to increase its thermal conductivity. Single crystals of YB66 doped with 4th, 5th and 6th group transition metals were grown by floating zone method. A detailed structure analysis suggested that an existing special B—B pair at the (1/4, 1/4, 1/4) site of YB66 could be attributed to a phonon scattering center that causes the amorphous-like low thermal conductivity. It was found that 5th and 6th group transition metals of V, Cr, Nb and Mo substitute the B—B pair. By contrast 4th group transition metals such as Ti and Zr were found to enter another (x, x, x) site with x ∼ 0.135. Thermal conductivity of both Nb-doped and undoped YB66 was measured in the range 4 K ≤ T ≤ 150 K. Nb doping increased thermal conductivity of YB66 with a factor of about 2.
Structural variations in Gd5Si4-xSnx: size vs. electronic effects
Authors: Mozharivskyj Yurij , Tsokol Alexandra O. , Miller Gordon J.
Published: July 2006

X-ray single crystal diffraction studies on the Gd5Si4xSnx series with 0 ≤ x ≤ 3 revealed an increase in the interslab T—T (T = Si, Sn) dimer distances and transition from Gd5Si4-type structures for 0 ≤ x ≤ 1.5 (d
T—T = 2.49–2.71 Å) to the Pu5Rh4-type structure for x = 2 (d
T—T = 3.04 Å). The Ti5Ga4-type structure, which is a stuffed version of the hexagonal Mn5Si3 structure, was observed for the Gd5SiSn3 sample (x = 3). Tight-binding linear-muffin-tin-orbital (TB-LMTO) calculations on Gd5Si2Sn2 show that the interslab (T1—T1) dimer stretching and the structural transition from the Gd5Si4-type to the Pu5Rh4-type results from the influence of the 5p atomic orbital energy and the larger size of the Sn atoms on the electronic structure, as compared to the Si and Ge atoms in Gd5Si4 and Gd5Si2Ge2.
Tin flux synthesis of rare-earth metal silicide compounds RESi1.7 (RE = Dy, Ho): a novel ordered structure derived from the AlB2 type
Authors: Roger Jérome , Babizhetskyy Volodymyr , Jardin Régis , Guérin Roland , Moinet Claude , Burkhardt Ulrich , Halet Jean-Francois
Published: July 2006

The binary rare-earth metal silicides RESi1.7 (RE = Dy, Ho) were prepared by tin flux synthesis between 800–1000 °C. Single crystals were obtained after electrochemical dissolving of molten ingots. Their crystal structures were determined from single-crystal X-ray data: orthorhombic symmetry, space group Imm2; unit cell parameters a = 19.144(1), b = 8.2562(3), c = 6.6571(3) Å and a = 19.063(1), b = 8.2120(2), c = 6.6313(2) Å for DySi1.7 and HoSi1.7, respectively. They represent a new ordered structure type, which is a derivative of the defect AlB2 type. The main structural feature is the occurrence of a vacancy ordering in the two-dimensional planar network of silicon atoms, leading to rows of edge-shared twelve-membered rings separated by distorted hexagonal rings. Structural comparison with the parent hexagonal silicide Yb3Si5 (Th3Pd5 type), the structure of which has been re-determined on single crystal, is also given.
Ge40.0Te5.3I8: synthesis, crystal structure, and properties of a new clathrate-I compound
Authors: Kovnir Kirill A. , Abramchuk Nikolay S. , Zaikina Julia V. , Baitinger Michael , Burkhardt Ulrich , Schnelle Walter , Olenev Andrei V. , Lebedev Oleg I. , Van Tendeloo Gustaaf , Dikarev Evgeny V. , Shevelkov Andrei V.
Published: July 2006

A new clathrate phase with the composition Ge40.0Te5.3I8 has been prepared and its structure determined from single crystal X-ray data. It crystallizes in the cubic space group Pm-3n with unit cell parameter a = 10.815(1) Å and Z = 1 (R = 0.031 for 272 independent reflections and 19 variables). Germanium and tellurium form a cationic clathrate framework hosting the guest iodine anions in cages of two different shapes. The cationic framework features a joint occupation on two of the three independent sites by germanium and tellurium, leading to the formation of Ge—Ge and Ge—Te bonds and vacancies on the third position. Electron diffraction and high-resolution electron microscopy reveal that the bulk material is not uniform; it contains domains showing a tendency for segregation of tellurium and germanium within the 4-fold positions of the space group P23, which is a subgroup of Pm-3n. Ge40.0Te5.3I8 is a diamagnetic semiconductor with a band gap of about 0.8 eV and its composition agrees with the Zintl formalism for the charge-balanced compounds.
Geometric variations and electron localizations in intermetallics: PbFCl type compounds
Authors: Nuss Jürgen , Wedig Ulrich , Jansen Martin
Published: July 2006

The structural relations of the intermetallic compounds Cu2Sb, Mn2Sb, Fe2As, Mn2As, Cr2As, Sc2Sb as well as of YTiSi and ZrSiS, all adopting the PbFCl structure, are discussed. In the course of these investigations, the crystal structures of Mn2Sb, Mn2As and Fe2As have been redetermined and refined from single crystal data. Bandstructures have been calculated in the framework of Density Functional Theory. The bonding properties are compared on the basis of partial densities of states, of the Crystal Orbital Hamilton Population (COHP) and of the Electron Localization Function (ELF). The trend of the d electrons to become more localized with increasing number leads to different bonding conditions in the compounds discussed.
Photography and Fiction
Authors: German Senta C.
Published: July 2006

This paper discusses the photographs published by Sir Arthur Evans of the Bronze Age site of Knossos on Crete and gives special attention to those that exhibit evidence of alteration. The altered images are divided into three categories: Retouched for Clarity, Reconstruction, and Falsification. It is argued that although Evans most frequently altered excavation photographs for benign purposes, he also occasionally changed images of the site and archaeological materials in order to reflect his desired historical interpretations.
Excavations on Thera and Therasia in the 19th Century
Authors: Tzachili Iris
Published: July 2006

The nineteenth-century excavations on Thera and Therasia took place at two periods: the first in 1866 and 1867 and the second in 1870. The investigations uncovered the Late Cycladic civilization of Thera, although at the time this could not be assigned to a chronological context, in the absence of any parallels: Minoan antiquities, the Cycladic civilization and the Mycenaean sites on the Greek mainland were all still undiscovered. The archaeological finds could not, therefore, be appreciated in their true historical dimensions. The excavations occasioned by the eruption of the volcano in 1867–70 were characterized by the approach and methods of the period, including evolutionism and the nascent Palaeolithic archaeology. These excavations were almost forgotten about for 100 years, partly because they were not related to ancient literary sources (as with Schliemann’s excavations conducted a little later), and partly because they could not be exploited for national purposes. This article provides a chronicle of the birth and evolution of these investigations
A Mesolithic Landscape in Greece
Authors: Runnels Curtis , Panagopoulou Eleni , Murray Priscilla , Tsartsidou Georgia , Allen Susan , Mullen Kevin , Tourloukis Evangelos
Published: July 2006

A survey was conducted in southern Greece in 2003 to test a predictive Mesolithic site-location model. We selected the coastal region of Kandia in the Argolid because the present shoreline is near the position of the early Holocene shoreline (c. 9,000 to 10,500 Cal BP). Marine transgression brought the shoreline near its present position by 9,000 Cal BP, flooding low-lying areas and creating a dynamic system of wetlands fed by springs and rivers. Our model predicted that Mesolithic sites were preferentially associated with freshwater wetlands in coastal zones, especially those areas that have small caves and rockshelters (shallow caves formed by overhangs of rock) that provided shelter and had optimal access to plants and animals at the intersection of woodland and aquatic habitats. Suitable caves and rockshelters (i.e. those large enough to have sheltered small bands of humans) were searched in an area of approximately 30 sq. km. Twenty-one sites with 1,713 associated lithic artifacts were recorded, 15 of which with microlithic assemblages of Mesolithic type are sites at the intersection between the higher elevations of the hinterland and the coastal wetlands. We interpret these Mesolithic sites as special activity sites or seasonally occupied residential sites that were part of a larger territory around the Argolic Gulf exploited by groups of foragers. This model is useful for the detection of Mesolithic sites in the eastern Mediterranean where similar environmental conditions existed in the early Holocene.
From sphaza to makoya!: a BA degree for court interpreters in South Africa
Authors: Moeketsi Rosemary , Wallmach Kim
Published: July 2006

In the past, court interpreters in the South African courts were compelled to serve under judges and magistrates, most of whom were agents of the apartheid system and who were therefore not concerned with the proper training of court interpreters nor encouraged any improvement in their working conditions. The meagre six-week orientation provided by the Justice College, historically the only attempt made to provide any sort of training for court interpreters, has always been ridiculed by court interpreters as a 'sphaza training', meaning insignificant and superficial. The inefficiency of the course can be attributed partly to its brevity, and partly to the lack of insight into the interpreting process which led to the service being misunderstood as a mere process of linguistic transfer from one language to another. Consequently, some interpreters feel justified in declining to take responsiblity for poor performance, claiming 'garbage in, garbage out', meaning that poor training begets poorly qualified, incompetent and unprofessional linguistic service providers. This article is an explication of how the University of South Africa addresses this situation by providing training in court interpreting. This training, embraced by most court interpreters as the makoya, 'the real thing', will hopefully improve the status of the service, renew the self-worth of practitioners and enhance their performance.
Does Lindley's LR estimation formula work for speech data? Investigation using long-term f0
Authors: Kinoshita Yuko
Published: July 2006

This article aims to investigate whether applying Lindley’s formula to speech data is justified. Our first problem is not knowing the true LR for any continuous parameters extracted from speech data: there have been no forensic speaker-identification studies with sufficiently large samples. However, with a good understanding of the parameter tested, we can to some degree predict how the LR should behave. How closely the LR estimates produced by Lindley’s formula match what is known about the parameter will tell us whether Lindley’s formula produces reliable LR estimates for speech data. The results of the experiments in this study seem to indicate that Lindley’s formula is indeed a useful tool to produce LR estimates of speech evidence, despite its omission of the occasion-to-occasion variation factor. The potential of long-term F0 as an additional piece of speech evidence seems to be very small, given that the LR of the test was found to be practically unity.
Ageing effects in a compacted bentonite: a microstructure approach
Authors: Delage P. , Marcial D. , Cui Y. J. , Ruiz X.
Published: July 2006

It is suspected that the as-compacted state of heavily compacted clays used as possible engineered barriers for nuclear waste disposal is time dependent, and that further change may occur in the material, even at constant water content and density. This paper presents an investigation of the time-dependent microstructure changes of an MX80 clay bentonite compacted at various dry densities and water contents. Microstructure investigation is based on mercury intrusion pore size distribution measurements and scanning electron microscopy (SEM). Results obtained by other researchers by using X-ray diffraction at low angles are also used. Statically compacted samples of MX80 were kept at constant volume and water content for various periods of time (1, 30 and 90 days) prior to mercury intrusion and SEM micro-structure investigation. A significant change in micro-structure with time was observed, characterised by a decrease in the inter-aggregate porosity and an increase in the very thin porosity not intruded by mercury (r < 3·7 nm). The former observation is related to the filling of inter-aggregate larger pores by exfoliation, and the latter observation is related to changes that occur in the aggregates within the smectite particles when suction is reduced. These changes are interpreted in the light of an investigation carried out on similar samples using low-angle X-ray diffraction. Changes inside the aggregates are governed by the progressive placement of interlayer water molecules inside the particles together with the subdivision of particles, which gives rise to an interparticle porosity that develops inside the aggregates.
Influence of the installation process on the performance of suction embedded plate anchors
Authors: Gaudin C. , O'Loughlin C. D. , Randolph M. F. , Lowmass A. C.
Published: July 2006

This paper describes a series of centrifuge tests performed in order to investigate the influence of the installation process on the capacity of a suction embedded plate anchor. A 1/145th reduced scale model suction caisson and plate anchor were used for this purpose, embedded in a normally consolidated clay sample. The full installation and retrieval process was simulated as well as loading of the anchor to failure. Results are compared with similar pullout tests where the anchor was pre-embedded manually in the sample. The keying process and the anchor capacity were also investigated. Results show a loss of performance of the suction embedded anchor immediately following the retrieval of the caisson due to weakening of the clay in the vicinity of the anchor. As the clay regains strength with time, the anchor capacity increases to match those of the jacked anchors. The normalised anchor capacity following consolidation agreed well with theoretical solutions. The loss of anchor embedment during the keying process was observed to be lower for the suction embedded anchors than for the jacked anchors, but both sets of data correlated closely with the load inclination at the anchor padeye.
Modelling wave attenuation by submerged resonators
Authors: Karambas T. V. , Gousidou M.
Published: July 2006

A system of mathematical models for linear wave propagation in a wave duct in the presence of submerged structures was developed and applied to study the dynamic interaction of the structures and the wave field. The presence of the structures and their dynamic coupling with the propagating waves was properly modelled and parameterised. Submerged structures of tubular form, double-peaked submerged structures and highly porous structures were tested. The phenomenon of resonance was revealed under certain conditions (when the structure width was of the order of half the wave length), resulting in a considerable increase of the efficiency of the structure in attenuating the incoming waves. The model produced satisfactory agreement with experiments performed in laboratory flumes.
The marine energy resource, constraints and opportunities
Authors: Bryden I. G.
Published: July 2006

The British Isles are blessed with highly energetic coastal waters, which offer opportunities for the exploitation of waves and tides for the generation of electricity. This paper looks at prospects for, and constraints upon, the long-term economic development of the wave and tidal resources. Technology already exists which is capable of the effective harnessing of marine resources. Proponents have estimated that up to 40% of the UK electricity supply could, eventually, come from wave and tidal sources. More conservative estimates suggest that the potential is somewhat lower than this but still substantial. The wave resource is recognised as being the larger but the tides do offer some very real advantages. Specifically, they are predictable, as they are driven by regular astronomic mechanisms. In addition, the energy flux density in many of the most attractive sites is formidable, offering the prospect of large-scale generation with relatively compact technology. Developers of both wave and tidal technology share economic as well as technical challenges and these must be overcome if new industries are to be established. The solutions require effort by scientists, engineers and, crucially, politicians.
Accumulation and elimination of dietary arsenobetaine in two species of fish, Atlantic salmon (Salmo salarL.) and Atlantic cod (Gadus morhuaL.)
Authors: Amlund Heidi , Francesconi Kevin A. , Bethune Claudette , Lundebye Anne-Katrine , Berntssen Marc H. G.
Published: July 2006

Despite the fact that marine fish contain relatively high concentrations of the naturally occurring arsenic compound arsenobetaine, little is known about the disposition of arsenobetaine in fish. We investigated the accumulation, distribution, and elimination of dietary arsenobetaine in Atlantic salmon (Salmo salar L.) and Atlantic cod (Gadus morhua L.), with the focus on muscle, liver, and kidney tissues. The fish were exposed to dietary arsenobetaine (24.7 ± 0.6 μg As/g feed) for three months, followed by a three-month depuration period. The two species showed marked differences in the accumulation and elimination of arsenobetaine. Total arsenic concentrations in Atlantic salmon increased significantly in muscle, liver, and kidney, whereas in Atlantic cod, a significant increase in total arsenic concentration was observed only in muscle. Elimination kinetics in muscle were distinct between the two species, with elimination half-lives from muscle tissue estimated at approximately 77 d in Atlantic cod and 37 d in Atlantic salmon, resulting in an absorption efficiency approximately twofold higher in Atlantic cod (15 ± 1%) compared to that in Atlantic salmon (8 ± 1%). The differences in arsenobetaine disposition studied in Atlantic salmon and Atlantic cod contribute to explain the differences in arsenic levels observed among marine fish.