bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and numerical investigation of a subsonic compressor with bend-skewed slot-casing treatment
Authors: Lu X , Chu W , Zhang Y , Zhu J
Published: December 2006

On the basis of the test results of discrete axial and blade angle slot casing treatment, a new type of casing treatment was designed for a subsonic axial flow compressor rotor by optimizing various geometry parameters. To obtain a wide operating range and to minimize penalties in terms of isentropic efficiency, seven compressor configurations incorporating casing treatments of 0, 16.6, 33.3, 50, 66.6, 83.3, and 100 per cent rotor exposures were experimentally investigated. The results showed that significant improvements in stall margin are possible in all exposures and insignificant isentropic efficiency sacrifices are recorded in some exposures. Nearly 21.43 per cent stall margin improvement in terms of the corrected mass flow-rate was achieved with 33.3 per cent rotor blade tip axial chord exposure. The compressor built with 16.6 per cent rotor exposure was the best configuration in terms of maximum isentropic efficiency gain.

The second issue of the paper was to offer a contribution to the understanding of the physical mechanism by which bend-skewed slot-casing treatment improves stall margin under subsonic conditions. By applying a concept similar to ‘Domain scaling’ approach (as often used in multistage turbomachinery flow-fields) to the interface between the rotor blade passage and end-wall treatments, a time-dependent three-dimensional numerical simulation was performed for the subsonic axial-flow compressor rotor with bend-skewed slot-casing treatment. The numerical results agreed well with the available experimental results. Detailed analyses of the coupled flow through bend-skewed slot-casing treatment and rotor blade passage under subsonic conditions led to some preliminary conclusions as to the flow physics involved in the stall margin improvements afforded by the use of bend-skewed slot-casing treatment.
Analysis of kinematics and solution of active/constrained forces of asymmetric 2UPU+X parallel manipulators
Authors: Lu Y , Hu B
Published: December 2006

A new family of asymmetric 2UPU+X parallel manipulators is proposed. It includes two identical UPU-type active legs and one X-type active leg which may be various five-degree-of-freedom serial mechanisms. First, their common kinematic characteristics and singularity are analysed, and some common formulae for analysing inverse-forward kinematics, solving active/constrained force transformation matrix and active/constrained forces, are derived. Second, three asymmetric 3-UPU, 2UPU + SPR, and 2UPU + RPRU parallel manipulators are created, their kinematics and singularity are analysed, and their active/constrained forces are solved.
A new method of creating expandable structure for spatial objects
Authors: Wei X-Z , Yao Y-A , Tian Y-B , Fang R
Published: December 2006

This paper presents a new method of creating expandable structure for spatial objects which are constructed by connecting a serial of parallelogram mechanisms whose edges are all equal in length with revolute joints. Any spatial object can be constructed with a certain number of basic cube units, and each basic cube unit is designed into an expandable one by being constructed with parallelogram mechanisms. By designing the basic cube unit in certain ways, not only can it be expanded and contracted synchronously, but also it can be expanded in some parts and contracted in others. During expansion, the basic cube unit is mobile with one degree of freedom. As a result, any spatial object assembled with these basic cube units is created into expandable structure, and that the entire structure can be expanded and contracted without being affected, even if there are some broken parts in it. To verify the feasibility of the method, two examples are provided.
Modelling and design of an exhaust manifold under thermomechanical loading
Authors: Park K H , Choi B L , Lee K W , Kim K S , Earmme Y Y
Published: December 2006

In the early stage of designing an exhaust manifold, a designer usually has to perform the fatigue analysis of each candidate of the exhaust manifold, and to decide whether or not it is satisfactory. In each case, elastoplastic stress analysis by the finite element method (FEM) is required, which is very time consuming considering the preprocessing and postprocessing of the FEM data. In this study, a thermal stress index is proposed for a practical application to the early stage of designing the exhaust manifold. Although this index (the ratio of the elastic effective stress to the yield stress) does not predict quantitatively the expected fatigue life, it is believed that it can be easily evaluated, and its merit lies in the quick estimation of the effect of the design parameters at the development stage without performing complete non-linear analysis of fatigue.
Thermal modelling of modern engines: A review of empirical correlations to estimate the in-cylinder heat transfer coefficient
Authors: Finol C A , Robinson K
Published: December 2006

Over the last 40 years, several empirical correlations have been developed to estimate heat fluxes from the combustion chambers of internal combustion engines. Some of these expressions are based on correlations to compute the Nusselt number for forced convection in turbulent flow inside circular tubes. The fundamental suitability of this kind of empirical model in representing the highly complex processes of in-cylinder heat transfer is questionable, but in practice the models have steadily improved owing to contributions from numerous investigators. Other correlations have a less theoretical basis than those of the Nusselt number form. Formulae of this type have been obtained from the application of simple statistical techniques to large datasets, taking into account several engine operational parameters and engine types. The resulting correlations provide reasonable estimates but perform poorly when extrapolated or applied to novel concepts. In this paper, the most important correlations are reviewed against the features of a modern diesel engine, and research requirements for future modelling developments are identified and discussed.
Developing a neural network and real genetic algorithm combined tool for an engine test bed
Authors: Wu Mian Hong , Lin Wanchang , Duan Shang Y
Published: December 2006

In the automotive industry, engine test engineers are required to deal with a huge quantity of experimental data obtained from engine test beds each day. Those data must be analysed to evaluate engine performance and to guide further engine test operations. In order to improve efficiency and reduce expenditure of time in engine testing, it is very important for engine test bed controllers to develop a mathematical model from existing engine test data. This paper presents an investigation of a neural network-genetic algorithm (GA) combined tool for engine modelling. In the modelling tool, a real-coded GA has been employed to train three different groups of neural networks (a multilayer perceptron group, a radial basis function group, and a bar function networks group) and then finally to find the most suitable neural network model for engine modelling. The experimental results given in this paper show that the proposed tool has been successfully used for Rover engine testing.
RETRACTED: Dynamic stability of a planetary gear train under the influence of variable meshing stiffness
Authors: Hbaieb R , Chaari F , Fakhfakh T , Haddar M
Published: December 2006

This article has been retracted at the request of the Editor and the Publishers.

Reason for Retraction: The results of a plagiarism investigation showed that the authors of this work (R Hbaieb, F Chaari, T Fakhfakh, and M Haddar) are in breach of the agreement that they signed in their Assignment of Copyright and Conditions of Publication form for JAUTO248, having copied substantial portions of material from the published paper: Lin, J. and Parker, R. G. Planetary gear parametric instability caused by mesh stiffness variation. Journal of Sound and Vibration, 2002, 249(1), 129-145 [DOI:10.1006/jsvi.2001.3848].

We apologize that this was not detected during the peer review process in 2006.
Systematic design process for frontal crashworthiness of aluminium-intensive electrical vehicle bodies
Authors: Hong Seung-Jun , Lee Dong-Chan , Jang Jae-Ho , Han Chang-Soo , Hedrick K
Published: December 2006

In the design of an aluminium-intensive body used for an electrical vehicle, a systems engineering approach, composed of system analysis, an optimization task to support the requirements, functional analysis, and a synthesis task, is introduced. Using these systems engineering concepts, the mounting and package requirements were determined through the estimation of force distribution and energy absorption of the front structure. The average acceleration, the effective crash spaces, and the collapse characteristics of an aluminiumintensive body were used for the idealization of the plastic collapse stiffness curve of the front longitudinal member. The geometric dimensions of rectangular and circular front longitudinal members in axial and bending collapse were determined by quasi-static simulations based on the approximation equations of axial and bending collapse modes. In the development process, a full vehicle crash test was performed to verify computer aided engineering (CAE) simulation and assess the feasibility of the design process.
Effects of ribs on S-frame crashworthiness
Authors: Hosseini-Tehrani P , Nikahd M
Published: December 2006

Safety and weight reduction continue to be the main drivers of structural developments. Better control of frontal collapse and avoidance of bending are the most important aspects of the design of front longitudinal members. Such members usually involve a curved section to provide clearance from mechanical systems, so it is difficult to prevent the onset of bending collapse, under end load, prior to the desired controlled longitudinal collapse of the box sections. While vertical ribs are formed into the walls of the box members to induce longitudinal buckling, it is found that inclining these at an angle is successful in cancelling the bending moment induced by the front end load. In this paper various configurations of incorporating formed ribs into the walls of the S-frame are considered and their effects on energy absorption and force response of the S-frame are studied. It is shown that, by using a proper arrangement of ribs in the walls of the S-frame, better crashworthiness characteristics may be achieved.
The use of micro-orifice nozzles and swirl in a small HSDI engine operating at a late split-injection LTC regime
Authors: Benajes J , Molina S , De Rudder K , Maroteaux D , Hamouda H Ben Hadj
Published: December 2006

This paper describes the investigation of low-temperature combustion (LTC) in a small single-cylinder research high-speed direct injection (HSDI) diesel engine. This engine is representative of passenger car turbocharged diesel engines equipped with a particulate trap and an oxidation catalyst. A medium-load operation mode has been evaluated where the diesel fuel is injected in two injection events close to top dead centre, and high levels of exhaust gas recirculation are used (near stoichiometric air-fuel ratios). The combustion is characterized by extremely low emission of nitrogen oxides (of the order of 10–15 parts per million) and low combustion noise. Three injector nozzles have been tested with 6, 12, and 18 orifices. The orifice diameters are in the range 70–120 μM and have been chosen to obtain injector nozzles with the same hydraulic flow. All three nozzles have been tested at a condition without swirl and at a mean swirl number of 1.7. The effects of the nozzle orifice number and swirl have been investigated by means of analysis of fuel spray, combustion, and emissions. It was found that when the number of orifices is increased, the rate of heat release during the first half of combustion is enhanced. However, during the second part of the combustion, interactions between sprays worsen the air-fuel mixing process and reduce the rate of heat release. Swirl was found to amplify the effects of spray interactions. While normally swirl speeds up the combustion in the second half of the combustion, the opposite happens when spray-spray interaction occurs.
The effect of leg fracture level and vehicle front-end geometry on pedestrian knee injury and response
Authors: Dunmore M C , Brooks R , Madeley N J , McNally D S
Published: December 2006

In this study a MADYMO® (mathematical dynamic modelling) model has been used to identify the influence of leg fracture on the injuries sustained by the pedestrian during front end impact with a vehicle. A factorial study of a MADYMO® pedestrian and vehicle model are used to investigate the effect of different leg fracture tolerances, geometry, and vehicle compliance on the criteria measured in the European Enhanced Vehicle-safety Committee (EEVC) pedestrian safety tests. These criteria include knee bending, knee shear response, and lower leg bone (tibia) acceleration. The main study examines the spread of typical values of lower limb tolerance based on reported literature and contrasts the response of weaker, low-strength bones, normal tolerance, and limbs which do not fracture. Results show that knee bending angles and therefore ligament strains are significantly increased when fracture does not occur, and are decreased in bones exhibiting a low-strength response. Bone fracture tolerance is shown to be a significant parameter influencing knee bending. The parameters are compared to show that knee shear is significantly influenced by vehicle bumper compliance and that both criteria are heavily influenced by bumper height. Vehicles with more aggressive geometry, higher bumpers, and larger bumper lead were considered for comparative purposes.
Structural behaviour of endodontically treated teeth under thermomechanical loading
Authors: Genovese K , Lamberti L , Pappalettere C
Published: December 2006

Choosing the optimal combination of post construction and restorative materials to minimize thermomechanical stresses in endodontically post-restored teeth is a very challenging task. In fact, while thermal properties of metallic alloys used for endodontic posts are rather similar to those of natural dental tissues, composite restorative materials used for constructing post and postcore usually possess better mechanical properties than metallic alloys. This may make it very difficult to evaluate directly thermomechanical stresses in the restored tooth.

Therefore, this paper presents a detailed analysis of the structural behaviour of several postendodontic restorations submitted to different combinations of thermomechanical load. The aim of the study is to compare the relative merits of different restoration concepts.

Three-dimensional finite element method (FE) analysis is carried out for an upper incisor restored with composite as well as metallic post systems. Furthermore, customized and standard post constructions are compared. Two loading cases are considered: (a) exposure to cold irritants in absence of mastication; (b) mastication of cold or hot foods. Effects of thermal field inhomogeneity and occlusal force magnitude are also included in the analysis. Because of the transient nature of thermal loads, relative performance of different restorations is investigated as the thermal perturbation spreads through the restored tooth.

Results indicate that composite post systems are globally more efficient than restorations including a metallic alloy post when thermal cycles and mastication act together. However, relative performance of different restoration concepts in the absence of mastication may depend strongly on the time of exposure to thermal irritants.
A finite element method comparison of wear in two metal-on-metal total hip prostheses
Authors: Cosmi F , Hoglievina M , Fancellu G , Martinelli B
Published: December 2006

The contact mechanics of two metal-on-metal (MOM) total hip prostheses was studied by means of the finite element method (FEM). The purpose of the work was to compare two total hip replacements (Durom™ and Metasul™) with regard to the amount of wear debris released. Wear on the bearing surfaces was evaluated following Reye hypotheses from the pressure distribution, computed by means of three-dimensional FEM models; an approximate analytical model based on Hertz contact theory has also been developed and discussed. The results show that in the dry friction condition the Durom™ joint releases almost twice as much wear volume as produced by the Metasul™ joint. Therefore, while Durom™ implants can improve hip stability by increasing the prosthetic impingement-free range of motion (PIF-ROM), Metasul™ prostheses can be a valuable solution whenever wear represents a critical choice factor.
Kansei and colour harmony models for townscape evaluation
Authors: Kinoshita Y , Cooper E. W. , Hoshino Y , Kamei K
Published: December 2006

Townscape colours have been a main factor in urban development. For townscape colours, keeping colour harmony within the environment is a common goal. Expressing characteristics and impressions of the town in townscape colours are other meaningful goals. The colour planning support system proposed here is intended to improve townscapes. The system offers some colour combination proposals based on three elements: colour harmony, impressions of the townscape, and cost for the change of colours. The objective of the present paper is to construct the colour harmony and Kansei evaluation models that evaluate colour combinations in the colour planning support system. The colour harmony equations by Moon and Spencer are employed for the construction of the colour harmony model. The Kansei model, which quantifies the impressions of the townscape, is constructed from the approach of Kansei engineering with neural networks. After the construction, evaluation experiments are conducted for 20 subjects to test the performance of both models. The results of the tests show sufficient correlation between model output and subject response for each model.
Robot assisted activity at a health service facility for the aged for ten weeks: An interim report of a long-term experiment
Authors: Wada K , Shibata T , Saito T , Tanie K
Published: December 2006

A long-term experiment using robot-assisted activity has been conducted at a health service facility for the aged since August 2003. Two therapeutic seal robots, named Paro, were introduced at the facility. This paper provides an interim report for 10 experimental weeks. Face scales, consisting of illustrations similar to people's faces, were used to evaluate participants' moods. The results indicate that the feelings and moods of the elderly improved by interacting with the seal robots. Moreover, the robots encouraged them to communicate with each other and with the caregivers.
Realization of comfortable space using brainwave signals
Authors: Watada J , Takagi M , Yubazaki N , Hirano H
Published: December 2006

It is difficult to define a comfortable space for people. This is partly because comfort relates to many attributes specifying a space, partly because all people have different preferences and also because even the same person changes his or her preference according to the state of health, body conditions, working state, and so on. Various parameters and attributes should be controlled in order to realize such a comfortable space according to the database of past usages. Information obtained from human bodies such as temperature, blood pressure, alpha waves, etc., can be employed to adjust the space to the best condition. The objective of the paper is to present the possibility that a space is able to be adjusted to a human condition based on human brainwaves.
Humanoid agent technology and its applications
Authors: Imamura K , Nishiyama T
Published: December 2006

In the software agent research field, the incorporation of intelligence and emotion into virtual humans (humanoid agents) created on a computer has been studied in order to establish smooth communication with users. In this paper, a system has been developed to simulate household renovations for family members with disabilities equipped with these technologies and emotion recognition technologies to establish more realistic agents. In this simulation system, a virtual character representing a person with a disability has been created. This simulated being will ‘experience’ the renovations before they are conducted. If there are any problems, they can be fed back to the renovation design. The developed emotion recognition method, to which transactional analysis is introduced, enables dialogue by taking the psychological states of the user and the humanoid agent into consideration.
Integrated design of function, usability, and aesthetics for automobile interiors: State of the art, challenges, and solutions
Authors: Lin Y , Zhang W. J.
Published: December 2006

This paper presents a critical review of aesthetic design with a focus on the application of vehicle interiors. In particular, the following aspects of the subject are covered: first, aesthetics and its relevance to product design; second, the integrated aesthetic design process; third, the evaluation of aesthetic responses; fourth, the notion of intelligent vehicle interiors; fifth, the computational methods for aesthetic design. Shortcomings in existing studies related to vehicle aesthetic design are identified and analysed. The methodology employed to conduct this review is such that a set of questions important to these aspects are defined first, and then existing studies are analysed on the basis of their provision of answers to these questions. At the end, several ideas are proposed, which are brought together as a software environment, with the goals of overcoming these identified shortcomings and advancing the automobile interior aesthetic design technology.
On-line power estimation of large diesel engines using acoustic emission and instantaneous crankshaft angular velocity
Authors: Douglas R M , Steel J A , Reuben R L , Fog T L
Published: December 2006

It is of interest to be able to gauge the power output of an engine from sensors that do not interfere with engine performance and are non-invasive. Acoustic emission (AE) analysis is one such technique, whereby information can be obtained from sensors placed on the external surface of the engine, requiring very little preparation. This paper shows that there is a strong relationship between AE energy and the variation of the instantaneous crankshaft angular velocity (ICAV) waveform over the engine cycle for a range of engine loads and that both types of measurement give a good indication of engine power on a ‘per cylinder’ basis.

AE and shaft encoder signals were acquired from two large (>7 MW), low-speed, two-stroke, diesel engines over a range of power outputs. The ICAV waveform (inferred from the shaft encoder signals) for one engine cycle was found to give a resolution that showed compression and expansion strokes of each cylinder. The variance of this waveform was found to correlate well with the power output of the engine, a finding that is in accord with those of a number of other authors. Additionally, the AE energy associated with fuel injection/combustion during each cycle was also related to engine power output, a finding that has not explicitly been reported elsewhere.

It is shown that, by combining both the AE and the ICAV data, and accounting for differences in engine specification such as number of cylinders, the observations of the two engines can be generalized, in that both the standard deviation in the ICAV waveform and the AE energy generated during the injection/combustion phase increase with increasing engine power output. This relationship can therefore be used to indicate engine power per cylinder and hence indicate whether cylinders are performing poorly. Provided that sufficiently robust sensors are available, such measurements could be made on-line and included in a preventative maintenance plan.
Sequential inversion technique and differential coefficient approach for accurate instantaneous emissions measurement
Authors: Madireddy M R , Clark N N
Published: December 2006

The need for accurate emissions measurements has coerced researchers into trying to reconstruct the true transient emission signal from that measured by the analyser. This paper discusses two such methods and examines the validity of those methods by testing them with real-time emissions data. The first method is the sequential inversion technique, which tries to reconstruct the input second by second, based on the measured response at each second and the dispersion characteristics of the analyser. The reconstruction was found to be accurate, but there were some constraints associated with the dispersion characteristics and the reconstruction failed if there was signal noise. The second method, the differential coefficients method (DCM) of Ajtay and Weilenmann, reconstructs the input signal by approximating the analyser input as a linear combination of the output and the output derivatives. When tested with real-time data, the DCM predicted the emission signal even when there was noise imposed on the signal. While the DCM is clearly a better prediction technique, the accuracy of the DCM is reduced when noise is added to the analyser input. The DCM, when coupled with cross-correlation techniques, can be a powerful tool in retrieving ‘lost’ information associated with the measurement delays and dispersion characteristics of the analyser.
Evaluation of the equivalence ratio-temperature region of diesel soot precursor formation using a two-stage Lagrangian model
Authors: Pickett L M , Caton J A , Musculus M P B , Lutz A E
Published: December 2006

The two-stage Lagrangian (TSL) reacting-jet model of Broadwell and Lutz is applied to n-heptane fuel jets to understand soot formation at diesel engine operating conditions. The model employs a diffusion-flame reactor and homogeneous core reactor with jet entrainment rates determined by empirical correlations. Detailed chemical kinetics, consisting of 696 species and 3224 reactions, are used for predictions of n-heptane oxidation and soot precursor formation up to seven-ring polycyclic aromatic hydrocarbons. Boundary conditions are based on realistic diesel operating conditions, mixing rates, and flame lift-off lengths. TSL soot precursor simulations are compared with closed-reactor (Senkin) predictions over a range of temperatures and equivalence ratios. Results show that the equivalence ratio-temperature region of soot precursor formation varies from the closed-reactor predictions and depends upon parameters such as ambient oxygen concentration, injection pressure, nozzle orifice size, and flame lift-off. The lack of a unique equivalence ratio-temperature region for soot precursor formation implies that the soot formation process depends upon the equivalence ratio-temperature path followed during jet mixing, and the residence time along the path.
Temporal soot evolution and diesel engine combustion: Influence of fuel composition, injection parameters, and exhaust gas recirculation
Authors: Kunte S , Bertola A , Obrecht P , Boulouchos K
Published: December 2006

This study deals with the investigation of the influence of fuel composition, injection parameters, and exhaust gas recirculation on not only engine-out, NOx, and particulate matter (PM) emissions but also on the temporal behaviour of soot formation and oxidation during combustion. Based on accurate measurements of exhaust emissions (gaseous components, particle number, and size distributions), in-cylinder temporal evolution of soot and temperature (computed from multicolour-pyrometry data), and analysis of the relevant parameters in direct-injection diesel engine combustion (calculation of heat release rates and different zone temperatures in the cylinder), insight has been gained with respect to the underlying mechanisms of the observed effects. Crank-angle-resolved data of the in-cylinder soot concentration have revealed the positive influence of the addition of water or of oxygenated diesel additives in diesel fuel in terms of reducing the soot formation and enhancing the soot oxidation rate. A clear linear correlation was found between the filter smoke number and KL signal at the end of the oxidation process. With respect to the particulate number or mass an exponential fit with KL at the end of main oxidation is shown.
A study of mixture formation processes in direct injection stratified charge gasoline engines by quantitative laser-induced fluorescence imaging and the infrared absorption method
Authors: Itoh T , Kakuho A , Hiraya K , Takahashi E , Urushihara T
Published: December 2006

Mixture formation processes were investigated of three types of direct injection stratified charge gasoline engine based on wall-guided, air-guided, and spray-guided concepts. Temporal and spatial variations of fuel concentration in the combustion chamber were measured by laser diagnostics such as quantitative laser-induced fluorescence (LIF) imaging and infrared absorption methods on a single-cylinder optical engine. It was found from the experiments that the direct injection gasoline engines based on both the wall-guided and air-guided concepts have long time intervals between the end of injection timing and ignition timing, and this demands early injection and ignition timings in the compression stroke, resulting in lower thermal efficiencies than those of the spray-guided concept. As for the spray-guided concept, fuel is ignited immediately after the end of injection, which enables near TDC (top dead centre) combustion, allowing lower fuel consumption than the other two. However, the condition for stable ignition and combustion achieved with the spray-guided concept is very narrow in terms of injection and ignition timings, so it is essential to widen the condition in order to make the concept a reality.
Construction of micron three-dimensional structures employing multi-photon polymerization
Authors: Filippidis G , Catherine J , Farsari M , Zorba V , Fotakis C
Published: December 2006

In the current paper, a study is made of the manufacture of three-dimensional structures of micron resolution using two- and three-photon polymerization. A femtosecond laser operating at a wavelength of 1028 nm is employed for the multi-photon polymerization processes. For the component manufacture, two different materials are used. The first material, used in two-photon polymerization, is an acrylate-based photo-polymer that polymerizes by employing green radiation. The second material, used in three-photon polymerization, is an ultraviolet (UV) -photopolymerizable acrylate composite.
New α′-Type ET Salt (ET)2H2F3 by Electrocrystallization Using Ionic Liquid
Authors: Yoshida Yukihiro , Sakata Masafumi , Saito Gunzi , Matsumoto Kazuhiko , Hagiwara Rika
Published: December 2006

A new ET-based cation radical salt α′-(ET)2H2F3 (ET: bis(ethylenedithio)tetrathiafulvalene) was obtained by an electrocrystallization method using a highly conductive ionic liquid (EMI)[F(HF)2.3] (EMI: 1-ethyl-3-methylimidazolium) as an electrolyte, and its structural, transport and magnetic properties were investigated. The salt shows the semiconducting behavior with an activation energy of 0.05–0.08 eV. Static susceptibility of 8.9 × 10−4 emu mol−1 at 300 K, in support of the transport behavior, is firm evidence of a Mott insulator.
Monitoring of EcoRV Digestions on a DNA-immobilized Quartz Crystal Microbalance
Authors: Takahashi Shuntaro , Matsuno Hisao , Furusawa Hiroyuki , Okahata Yoshio
Published: December 2006

Kinetic parameters of DNA digestions by EcoRV such as binding and dissociation rate constants of enzymes to DNA (kon and koff) and the site-specific cleavage reaction (kcat) could be obtained using a DNA-immobilized quartz-crystal microbalance (QCM).
Four Kinds of 21 Helical Assemblies with the Molecular Tilt as Well as Three-directional and Facial Chirality
Authors: Watabe Tsuyoshi , Hisaki Ichiro , Tohnai Norimitsu , Miyata Mikiji
Published: December 2006

Four kinds of 21 helical assemblies with a right- or left-handed screw with belly- or back-inside were confirmed in cocrystals of brucine. Discrimination of the different helicities owes to the molecular tilt as well as three-directional and facial chirality of the brucine molecule.
Unique folding of precursor microRNAs: Quantitative evidence and implications for de novo identification
Authors: NG Kwang Loong Stanley , Mishra Santosh K.
Published: December 2006

MicroRNAs (miRNAs) participate in diverse cellular and physiological processes through the post-transcriptional gene regulatory pathway. Hairpin is a crucial structural feature for the computational identification of precursor miRNAs (pre-miRs), as its formation is critically associated with the early stages of the mature miRNA biogenesis. Our incomplete knowledge about the number of miRNAs present in the genomes of vertebrates, worms, plants, and even viruses necessitates thorough understanding of their sequence motifs, hairpin structural characteristics, and topological descriptors. In this in-depth study, we investigate a comprehensive and heterogeneous collection of 2241 published (nonredundant) pre-miRs across 41 species (miRBase 8.2), 8494 pseudohairpins extracted from the human RefSeq genes, 12,387 (nonredundant) ncRNAs spanning 457 types (Rfam 7.0), 31 full-length mRNAs randomly selected from GenBank, and four sets of synthetically generated genomic background corresponding to each of the native RNA sequence. Our large-scale characterization analysis reveals that pre-miRs are significantly different from other types of ncRNAs, pseudohairpins, mRNAs, and genomic background according to the nonparametric Kruskal–Wallis ANOVA (p < 0.001). We examine the intrinsic and global features at the sequence, structural, and topological levels including %G+C content, normalized base-pairing propensity P(S), normalized minimum free energy of folding MFE(s), normalized Shannon entropy Q(s), normalized base-pair distance D(s), and degree of compactness F(S), as well as their corresponding Z scores of P(S), MFE(s), Q(s), D(s), and F(S). The findings will promote more accurate guidelines and distinctive criteria for the prediction of novel pre-miRs with improved performance.
Structural plasticity and Mg2+ binding properties of RNase P P4 from combined analysis of NMR residual dipolar couplings and motionally decoupled spin relaxation
Authors: Getz Melissa M. , Andrews Andy J. , Fierke Carol A. , Al-Hashimi Hashim M.
Published: December 2006

The P4 helix is an essential element of ribonuclease P (RNase P) that is believed to bind catalytically important metals. Here, we applied a combination of NMR residual dipolar couplings (RDCs) and a recently introduced domain-elongation strategy for measuring “motionally decoupled” relaxation data to characterize the structural dynamics of the P4 helix from Bacillus subtilis RNase P. In the absence of divalent ions, the two P4 helical domains undergo small amplitude (~13°) collective motions about an average interhelical angle of 10°. The highly conserved U7 bulge and helical residue C8, which are proposed to be important for substrate recognition and metal binding, are locally mobile at pico- to nanosecond timescales and together form the pivot point for the collective domain motions. Chemical shift mapping reveals significant association of Mg2+ ions at the P4 major groove near the flexible pivot point at residues (A5, G22, G23) previously identified to bind catalytically important metals. The Mg2+ ions do not, however, significantly alter the structure or dynamics of P4. Analysis of results in the context of available X-ray structures of the RNA component of RNase P and structural models that include the pre-tRNA substrate suggest that the internal motions observed in P4 likely facilitate adaptive changes in conformation that take place during folding and substrate recognition, possibly aided by interactions with Mg2+ ions. Our results add to a growing view supporting the existence of functionally important internal motions in RNA occurring at nanosecond timescales.
NMR structure of stem–loop D from human rhinovirus-14
Authors: Headey Stephen J. , Huang He , Claridge Jolyon K. , Soares Giselle A. , Dutta Kaushik , Schwalbe Martin , Yang Daiwen , Pascal Steven M.
Published: December 2006

The 5′-cloverleaf of the picornavirus RNA genome is essential for the assembly of a ribonucleoprotein replication complex. Stem–loop D (SLD) of the cloverleaf is the recognition site for the multifunctional viral protein 3Cpro. This protein is the principal viral protease, and its interaction with SLD also helps to position the viral RNA-dependent RNA polymerase (3Dpol) for replication. Human rhinovirus-14 (HRV-14) is distinct from the majority of picornaviruses in that its SLD forms a cUAUg triloop instead of the more common uYACGg tetraloop. This difference appears to be functionally significant, as 3Cpro from tetraloop-containing viruses cannot bind the HRV-14 SLD. We have determined the solution structure of the HRV-14 SLD using NMR spectroscopy. The structure is predominantly an A-form helix, but with a central pyrimidine–pyrimidine base-paired region and a significantly widened major groove. The stabilizing hydrogen bonding present in the uYACGg tetraloop was not found in the cUAUg triloop. However, the triloop uses different structural elements to present a largely similar surface: sequence and underlying architecture are not conserved, but key aspects of the surface structure are. Important structural differences do exist, though, and may account for the observed cross-isotype binding specificities between 3Cpro and SLD.
Adjunctive Aripiprazole in Bipolar I Depression
Authors: Sokolski Kenneth N
Published: December 2006

Background:

Aripiprazole has demonstrated efficacy in treatment of bipolar mania, as well as in the maintenance treatment of bipolar disorder. There has been only one report supporting a role for this agent in the depressed phase of the illness.

Objective:

To evaluate the effectiveness of adjunctive aripiprazole in bipolar I depressed patients who are nonresponders to standard therapy.

Methods:

Chart records were reviewed for all patients with bipolar I depression, diagnosed by Diagnostic and Statistical Manual of Mental Disorders, 4th revision, criteria between June 2004 and January 2006 from the Long Beach Veterans Affairs Mood Disorders Clinic. Included subjects had experienced moderate to marked depressive symptoms (Clinical Global Impression–Bipolar Depression ≥4) despite at least 2 months of treatment with adequate doses of at least one mood stabilizer. In addition, all subjects had been treated subsequently with aripiprazole 15–30 mg/day added to the existing regimen. Detailed chart notes were used to retrospectively rate symptoms. The presence or absence of each symptom was recorded before and after aripiprazole augmentation. Based on these data, Clinical Global Impression bipolar severity (CGI-BP-S) ratings and CGI-BP improvement scores for bipolar I depression were assigned.

Results:

Ten subjects met study criteria. Adjunctive aripiprazole given for 21–110 days resulted in significant improvements in CGI-BP-S depression ratings. Seven of 10 patients were assigned CGI-BP improvement ratings of much or very much improved. Adverse events were mild and included akathisia, nausea, and insomnia. Dose adjustments of aripiprazole or the addition of drugs to treat adverse effects excluded subjects from further data collection. No patient stopped aripiprazole due to adverse effects.

Conclusions:

This study adds to a previous report indicating beneficial effects of adjunctive aripiprazole in treatment of bipolar I depression. Double-blind, placebo-controlled investigations are needed to confirm these findings.
The Role of Olanzapine in the Treatment of Anorexia Nervosa
Authors: Dunican Kaelen C , DelDotto Dana
Published: December 2006

Objective:

To evaluate the role of olanzapine in the treatment of anorexia nervosa.

Data Sources:

Literature was obtained through searches of MEDLINE (1966–December 2006), EMBASE (1980–4th Quarter 2006), and PsycINFO (1985–December 2006) and a bibliographic review of published articles. Key terms used in the searches included anorexia nervosa, antipsychotics, eating disorders, olanzapine, and Zyprexa.

Study Selection And Data Extraction:

All English language articles that were identified from the search were evaluated. All primary literature was included in the review.

Data Synthesis:

In several case reports and most clinical trials, patients with anorexia nervosa successfully gained weight while being treated with olanzapine. Moreover, many patients treated with olanzapine achieved a healthy body weight. Case reports and trials identified additional benefits of olanzapine, including reduction in delusional thinking; improvement in body image, sleep, depressive symptoms, adherence to treatment, and eating-disorder symptoms; and decreased agitation and premeal anxiety.

Conclusions:

Preliminary evidence supports the use of olanzapine for treatment of anorexia nervosa by demonstrating that olanzapine 2.5–15 mg daily promotes weight gain and has positive effects on associated psychological symptoms. Limitations of the reported data include small sample size, low completion rate in clinical trials, and open-label trial design. Although olanzapine appears to have a potential role in the treatment of anorexia nervosa that has been unresponsive to other therapy, randomized, placebo-controlled studies with larger sample sizes are necessary to establish its role in therapy.
Livedoid Skin Reaction Probably Due to Imatinib Therapy
Authors: Martínez-González M Covadonga , Pozo Jesús del , Yebra-Pimentel María Teresa , Pérez Mónica , Almagro Manuel , Fonseca Eduardo
Published: December 2006

Objective:

To report 3 cases of skin rash with a peculiar livedoid pattern that were probably associated with imatinib therapy.

Case Summary:

In the first case, a 74-year-old male diagnosed with Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML), treated with imatinib 400 mg/day, developed a skin eruption with a livedoid pattern. Systemic corticosteroids were started, and skin lesions improved. The second case involved a 66-year-old male with Ph+ CML who was treated with imatinib 600 mg/day. After initiation of this treatment, he developed a skin rash with a livedoid pattern. The drug treatment was discontinued and then reintroduced. Topical corticosteroid treatment was started, resulting in total remission of the skin lesions. When the imatinib dose was progressively reintroduced, the skin lesions recurred. The patient died as a result of the progression of his disease. In the third case, a 43-year-old male with Ph+ acute lymphoblastic leukemia was treated with imatinib 600 mg/day. After a few days of treatment, the patient developed a skin rash with a livedoid pattern. He died as a result of probable septic shock.

Discussion:

Imatinib is a tyrosine kinase receptor inhibitor that inhibits BCR/ABL tyrosine kinase. There have been several published articles on cutaneous adverse reactions related to imatinib therapy. The most common cutaneous adverse event of imatinib is a rash with variable clinical presentation. The Naranjo probability scale indicated a probable relationship between imatinib and the rash in all 3 cases reported hero.

Conclusions:

Adverse reactions to imatinib that affect the skin occur frequently. They are strongly dose dependent, self-limiting, or easily managed by lowering the dose of imatinib and, if necessary, prescribing short-term therapy with a systemic corticosteroid. Clinicians should monitor patients taking imatinib and institute treatment quickly if a rash develops.
N-Acetylcysteine and Sodium Bicarbonate Versus N-Acetylcysteine and Standard Hydration for the Prevention of Radiocontrast-Induced Nephropathy Following Coronary Angiography
Authors: Schmidt Paul , Pang Dorothy , Nykamp Diane , Knowlton Gregory , Jia Haomiao
Published: December 2006

Background:

Radiocontrast-induced nephropathy (RCIN) is thought to be caused by renal ischemia and direct toxic effects on renal tubular cells brought on by contrast media. The combination of N-acetylcysteine (NAC) and hydration fluids (NaCI 0.9% or 0.45%) has been shown to reduce these deleterious effects and is commonly given prior to coronary angiography. The use of bicarbonate as the hydration anion has been shown to confer additional RCIN protection compared with that of saline. However, limited data are available regarding whether sodium bicarbonate hydration, proven to be beneficial alone, can further improve outcomes when given with NAC.

Objective:

To compare the incidence of RCIN in patients undergoing coronary angiography after pretreatment with NAC plus sodium bicarbonate hydration or NAC plus standard hydration (NaCI 0.9% or 0.45%).

Methods:

A retrospective, single-center study evaluated 96 patients who underwent coronary angiography from January 2002 to December 2005. Data were collected through electronic chart reviews.

Results:

Forty-seven patients received NAC and sodium bicarbonate for hydration and 49 received NAC and standard hydration. Baseline characteristics between the 2 groups were similar. All patients received at least one 600 mg oral dose of NAC before angiography was performed. RCIN was defined as impairment of renal function occurring within 72 hours of administering contrast media, indicated by an absolute increase in the serum creatinine level of 0.5 mg/dL or more. A total of 12.2% of the patients receiving NAC and standard hydration developed RCIN, versus 14.9% of the patients in the NAC and sodium bicarbonate group (p = 0.713).

Conclusions:

The addition of sodium bicarbonate to NAC does not appear to confer additional protection against the development of RCIN. Prospective, randomized, placebo-controlled trials are warranted to definitively determine how this combination compares with NAC and standard hydration in preventing RCIN.