bluuebunny/crossref_metadata_2025 huggingface dataset:
NMR solution structure and function of the C‐terminal domain of eukaryotic class 1 polypeptide chain release factor
Authors: Mantsyzov Alexey B. , Ivanova Elena V. , Birdsall Berry , Alkalaeva Elena Z. , Kryuchkova Polina N. , Kelly Geoff , Frolova Ludmila Y. , Polshakov Vladimir I.
Published: May 2010

Termination of translation in eukaryotes is triggered by two polypeptide chain release factors, eukaryotic class 1 polypeptide chain release factor (eRF1) and eukaryotic class 2 polypeptide chain release factor 3. eRF1 is a three‐domain protein that interacts with eukaryotic class 2 polypeptide chain release factor 3 via its C‐terminal domain (C‐domain). The high‐resolution NMR structure of the human C‐domain (residues 277–437) has been determined in solution. The overall fold and the structure of the β‐strand core of the protein in solution are similar to those found in the crystal structure. The structure of the minidomain (residues 329–372), which was ill‐defined in the crystal structure, has been determined in solution. The protein backbone dynamics, studied using 15N‐relaxation experiments, showed that the C‐terminal tail 414–437 and the minidomain are the most flexible parts of the human C‐domain. The minidomain exists in solution in two conformational states, slowly interconverting on the NMR timescale. Superposition of this NMR solution structure of the human C‐domain onto the available crystal structure of full‐length human eRF1 shows that the minidomain is close to the stop codon‐recognizing N‐terminal domain. Mutations in the tip of the minidomain were found to affect the stop codon specificity of the factor. The results provide new insights into the possible role of the C‐domain in the process of translation termination.
Expression of Cyclic AMP-dependent Protein Kinase Isoforms in Human Cavernous Arteries: Functional Significance and Relation to Phosphodiesterase Type 4
Authors: Waldkirch Eginhard S. , Ückert Stefan , Sigl Katja , Satzger Imke , Geismar Ulrike , Langnäse Kristina , Richter Karin , Sohn Michael , Kuczyk Markus A. , Hedlund Petter
Published: May 2010

Introduction

The cyclic adenosine monophosphate-dependent protein kinase (cAK) is considered a key protein in the control of smooth muscle tone in the cardiovascular system. There is evidence that erectile dysfunction might be linked to systemic vascular disorders and arterial insufficiency, subsequently resulting in structural changes in the penile tissue. The expression and significance of cAK in human cavernous arteries (HCA) have not been evaluated.

Aims

To evaluate the expression of cAK isoforms in HCA and examine the role of cAK in the cyclic adenosine monophosphate (cAMP)- and cyclic guanosine monophosphate (cGMP)-mediated control of penile vascular smooth muscle.

Methods

The expression and distribution of phosphodiesterase type 4 (PDE4) and cAK isoforms in sections of HCA were investigated by means of immunohistochemistry and Western blot analysis. The effects of the cAK inhibitor Rp-8-CPT-cAMPS on the relaxation of isolated preparations of HCA (diameter > 100 µm) induced by rolipram, sildenafil, tadalafil, and vardenafil were studied using the organ bath technique.

Main Outcome Measures

Investigate the expression of cAK in relation to α-actin and PDE4 in HCA and evaluate the effects of an inhibition of cAK on the relaxation induced by inhibitors of PDE4 and PDE5 of isolated penile arteries.

Results

Immunosignals specific for cAKIα, IIα, and IIβ were observed within the wall of HCA. Double stainings revealed colocalization of cAK with α-actin and PDE4. The expression of cAK isoforms was confirmed by Western blot analysis. The reversion of tension induced by inhibitors of PDE4 and PDE5 of isolated penile vascular tissue were attenuated significantly by Rp-8-CPT-cAMPS.

Conclusions

Our results demonstrate the expression of cAK isoforms in the smooth musculature of HCA and its colocalization with PDE4. A significant role for cAK in the regulation mediated by cAMP and cGMP of vascular smooth muscle tone in HCA can also be assumed.
Physiology of Women’s Sexual Function: Basic Knowledge and New Findings
Authors: Salonia Andrea , Giraldi Annamaria , Chivers Meredith L. , Georgiadis Janniko R. , Levin Roy , Maravilla Kenneth R. , McCarthy Margaret M.
Published: May 2010

Introduction

Data concerning the physiology of female sexual functioning are still obtained from animal studies, but an increasing amount of novel evidence comes from human studies.

Aim

To gain knowledge of psychological and biologic physiology of women’s sexual functioning, mainly addressing sexual arousal and orgasm.

Methods

A broad-based literature review of current knowledge of the psychological and biologic physiology aspects of women’s sexual functioning.

Results

A comprehensive understanding of the anatomical, neurobiological, and psychological mechanisms behind sexual function and responses is of paramount importance. A biopsychological paradigm was considered when reviewing currently available data, thus considering aspects of: (i) sexual differentiation of the brain, which is critical for sex differentiation in behavior; (ii) central neurobiology of sexual function, highlighting specific and innovative findings from neuroimaging methods that enable visualization of active brain areas during arousal and orgasm; and (iii) peripheral functional anatomy, mainly addressing genital arousal and orgasm. Translational science was also covered, providing data about the actual role of sexual arousal in women in both procreation/reproduction and recreation/pleasure. The interaction between physiological and psychological states of women’s sexual response, nonspecific sexual response, interoceptive awareness, and flexibility of sexual interests have also been addressed.

Conclusion

Further research on normal physiology of women’s sexual function is needed in order to expand and “translate” current knowledge into the pathophysiological clinical setting. This manuscript encompasses data presented at the 3rd International Consultation on Sexual Medicine in Paris, France, July 10–13, 2009.
Exploring 3‐arylquinoxaline‐2‐carbonitrile 1,4‐di‐N‐oxides Activities Against Neglected Diseases with QSAR
Authors: Vicente Esther , Duchowicz Pablo R. , Ortiz Erlinda del V. , Monge Antonio , Castro Eduardo A.
Published: May 2010

This work reveals our efforts to continue identifying new active compounds against neglected diseases, such as malaria and tuberculosis. We took several 3‐arylquinoxaline‐2‐carbonitrile 1,4‐di‐N‐oxide derivative activity results from the reference literature and established useful quantitative structure–activity relationships. We hoped that the development ofin silicomodels would broaden our knowledge regarding the overwhelming problem of drug resistance to both illnesses. The optimized molecular structures of 60 compounds were represented by 1497 DRAGON‐type descriptors and subjected to linear regression analyses; the quantitative structure–activity relationships resulted predictive when searching for new active compounds. We obtained a rational guide for the proposal of new candidate structures whose activities still remain unknown.
Expression of Notch signalling‐related genes in normal and differentiating rat dental pulp cells
Authors: Sun Hantang , Kawashima Nobuyuki , Xu Jing , Takahashi Satomi , Suda Hideaki
Published: May 2010

Notch signalling is of fundamental importance to various processes during embryonic development and in adults. The possible role of Hey1, an important Notch signalling component, in odontoblast differentiation was evaluated in this study. Primary cultured dental pulp cells, derived from upper incisors of 5‐week‐old Wistar rats, were placed in α‐modification of Eagle's minimal essential medium supplemented with 10% Fetal Bovine Serum (FBS), and ascorbic acid (AA) and β‐glycerophosphate (β‐GP), with or without dexamethasone, and cultured on dishes coated with collagen type IA for 7 days. Conventional and real‐time Polymerase Chain Reaction (PCR) was performed to determine the expression of Notch‐related genes and dentin sialophosphoprotein as a marker of odontoblast differentiation. Dentin sialophosphoprotein and Hey1 expression was significantly increased and decreased in the presence of AA + β‐GP compared with controls, respectively. These findings suggest that Hey1 may be a negative regulator in odontoblast differentiation.
In vivo comparison of the accuracy of two electronic apex locators
Authors: Silveira Luiz F. M. , Petry Fernanda V. , Martos Josué , Neto João B. C.
Published: May 2010

The aim of this study was to analyse in vivo the accuracy of two apex locators, Root ZX and Novapex, to determine the position of the apical constriction. Twenty‐three human single‐rooted teeth to be extracted for periodontal reasons constituted the experiment. Endodontic access was obtained and the apical constriction was determined by one of the apex locators after initial crown‐down preparation. When the electronic marker indicated that the tip of the endodontic file was at the apical constriction, the teeth were filled with composite and then surgically removed. The presence of the endodontic file tip at the apical constriction was evaluated stereomicroscopically (30×) and confirming radiographs were exposed. The accuracy of Root ZX and Novapex was 91.7% and 81.8% respectively. Within the limits of this study, the evaluated apex locators have a similar clinical performance for the apical constriction location.
A comparison of cyclic fatigue resistance in reciprocating and rotary nickel‐titanium instruments
Authors: Wan Jeffrey , Rasimick Brian J. , Musikant Barry L. , Deutsch Allan S.
Published: May 2010

The cyclic fatigue resistance of four nickel‐titanium endodontic instruments was compared. K3, ProFile and GT Series X rotary instruments were examined along with SafeSiders reciprocating instruments. 30/0.04 instruments at 25 mm length were compared. Cyclic fatigue testing was conducted by operating instruments in artificially constructed stainless steel canals with 30° and 45° angles of curvature and 5 mm and 7.5 mm radii of curvature. The time and cycles to failure were recorded for 192 samples. Statistical analysis was performed with three‐way anova and the Student‐Neuman‐Keuls multiple comparisons testing. With a 5 min maximum running time, no SafeSiders samples were observed to separate. ProFile and GT Series X instruments were found to be significantly more resistant than K3 instruments (P < 0.001) for all experiment groups. There was no statistical difference between ProFile and GT Series X files (P < 0.582).
Expression of bone morphogenetic proteins (BMPs) receptors in patients with B‐cell chronic lymphocytic leukemia (B‐CLL)
Authors: DZIETCZENIA J. , WRÓBEL T. , JAŹWIEC B. , MAZUR G. , BUTRYM A. , PORĘBA R. , KULICZKOWSKI K.
Published: May 2010

Bone morphogenetic proteins (BMPs) are multifunctional cytokines which belong to transforming growth factor β (TGF β) superfamily. They regulate proliferation, differentiation, and apoptosis in a variety of cells including hematopoietic cells. BMPs act because of binding to two types of serine/threonine kinase receptors: BMP type I receptors (IA and IB) and BMP type II receptor. Deregulation of BMPs signaling pathways has been reported in some of human cancers, but the role of BMPs in hematopoietic malignancies remains unknown. The aim of our study was to examine the percentage of expression of BMPs receptors on lymphocytes of patients with B‐cell chronic lymphocytic leukemia (B‐CLL). A total of 46 patients with B‐CLL (27 men and 19 women) and 10 healthy persons were evaluated. Freshly isolated mononuclear cells were incubated with antibodies against BMPs receptors: BMPRIA, BMPRIB, and BMPRII and examined in 2‐color flow cytometry. On cells of patients with B‐CLL, the percentage of expression of BMP RIA, BMP RIB, and BMP RII was significantly higher than in normal cells of the control group. The percentage of the expression of BMP RIA and BMP RIB was higher in patients with advanced stage of disease.
Voluntary activation of ankle muscles is accompanied by subcortical facilitation of their antagonists
Authors: Geertsen Svend S. , Zuur Abraham T. , Nielsen Jens B.
Published: May 2010

Flexion and extension movements are organized reciprocally, so that extensor motoneurones in the spinal cord are inhibited when flexor muscles are active and vice versa. During and just prior to dorsiflexion of the ankle, soleus motoneurones are thus inhibited as evidenced by a depression of the soleus H‐reflex. It is therefore surprising that soleus motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) have been found not to be reduced and even facilitated during a voluntary dorsiflexion. The objective of this study was to investigate if MEPs, evoked by TMS, show a similar facilitation prior to and at the onset of contraction of muscles that are antagonists to the muscle in which the MEP is evoked and if so, examine the origin of such a facilitatory motor programme. Eleven seated subjects reacted to an auditory cue by contracting either the tibialis anterior (TA) or soleus muscle of the left ankle. TMS was applied to the hotspot of TA and soleus muscles on separate days. Stimuli were delivered prior to and at the beginning of contraction. Soleus MEPs were significantly facilitated when TMS was applied 50 ms prior to onset of plantar flexion. Surprisingly, soleus MEPs were also facilitated (although to a lesser extent) at a similar time in relation to the onset of dorsiflexion. TA MEPs were facilitated 50 ms prior to onset of dorsiflexion and neither depressed nor facilitated prior to plantar flexion. No difference was found between the facilitation of the soleus MEP and motor evoked responses to cervicomedullary stimulation prior to dorsiflexion, suggesting that the increased soleus MEPs were not caused by changes at a cortical level. This was confirmed by the observation that short‐latency facilitation of the soleus H‐reflex by subthreshold TMS was increased prior to plantar flexion, but not prior to dorsiflexion. These findings suggest that voluntary contraction at the ankle is accompanied by preceding facilitation of antagonists by a subcortical motor programme. This may help to ensure that the direction of movement may be changed quickly and efficiently during functional motor tasks.
Numerical Analysis of the Vaned Diffuser of a Transonic Centrifugal Compressor
Authors: Marconcini Michele , Rubechini Filippo , Arnone Andrea , Ibaraki Seiichi
Published: May 2010

A three-dimensional Navier–Stokes solver is used to investigate the flow field of a high pressure ratio centrifugal compressor for turbocharger applications. Such a compressor consists of a double-splitter impeller followed by a vaned diffuser. Particular attention is focused on the analysis of the vaned diffuser, designed for high subsonic inlet conditions. The diffuser is characterized by a complex three-dimensional flow field and influenced by the unsteady interaction with the impeller. Detailed particle image velocimetry flow measurements within the diffuser are available for comparison purposes.
Computation of Eigenvalues and Eigenvectors of a Mistuned Bladed Disk Via Unidirectional Taylor Series Expansions
Authors: Sinha Alok
Published: May 2010

This paper deals with the computation of eigenvalues and eigenvectors of a mistuned bladed disk. First, the existence of derivatives of repeated eigenvalues and corresponding eigenvectors is discussed. Next, an algorithm is developed to compute these derivatives. It is shown how a Taylor series expansion can be used to efficiently compute eigenvalues and eigenvectors of a mistuned system. Numerical examples are presented to corroborate the validity of theoretical analysis.
High-Fidelity Numerical Analysis of Per-Rev-Type Inlet Distortion Transfer in Multistage Fans—Part I: Simulations With Selected Blade Rows
Authors: Yao Jixian , Gorrell Steven E. , Wadia Aspi R.
Published: May 2010

Demands for improved performance and operability of advanced propulsion systems require an understanding of the physics of inlet flow distortion transfer and generation and the subsequent engine response. This also includes developing a high-fidelity characterization capability and suitable tools/rules for the design of distortion tolerant engines. This paper describes efforts to establish a high-fidelity prediction capability of distortion transfer and fan response via high-performance computing. The current CFD capability was evaluated with a focus of predicting the transfer of prescribed inlet flow distortions. Numerical simulations, comparison to experimental data, and analysis of two selected three-stage fans are presented. The unsteady Reynolds-Averaged Navier-Stokes (RANS) code PTURBO demonstrated remarkable agreement with data, accurately capturing both the magnitude and profile of total pressure and total temperature measurements. Part I of this paper describes the establishment of the required numerical simulation procedures. The computational domains are limited to the first three blade rows for the first multistage fan and the last three blade rows for the second fan. This paper presents initial validation and analysis of the total pressure distortion transfer and the total temperature distortion generation. Based on the established ground work of Part I, the entire two multistage fans were simulated with inlet distortion at normal operating condition and near stall condition, which is Part II of this paper. Part II presents the full range validation against engine test data and in-depth analysis of distortion transfer and generation mechanisms throughout the two fans.
Aerodynamics of a Letterbox Trailing Edge: Effects of Blowing Rate, Reynolds Number, and External Turbulence on Aerodynamic Losses and Pressure Distribution
Authors: Fiala N. J. , Johnson J. D. , Ames F. E.
Published: May 2010

A letterbox trailing edge configuration is formed by adding flow partitions to a gill slot or pressure side cutback. Letterbox partitions are a common trailing edge configuration for vanes and blades, and the aerodynamics of these configurations are consequently of interest. Exit surveys detailing total pressure loss, turning angle, and secondary velocities have been acquired for a vane with letterbox partitions in a large-scale low speed cascade facility. These measurements are compared with exit surveys of both the base (solid) and gill slot vane configurations. Exit surveys have been taken over a four to one range in chord Reynolds numbers (500,000, 1,000,000, and 2,000,000) based on exit conditions and for low (0.7%), grid (8.5%), and aerocombustor (13.5%) turbulence conditions with varying blowing rate (50%, 100%, 150%, and 200% design flow). Exit loss, angle, and secondary velocity measurements were acquired in the facility using a five-hole cone probe at a measuring station representing an axial chord spacing of 0.25 from the vane trailing edge plane. Differences between losses with the base vane, gill slot vane, and letterbox vane for a given turbulence condition and Reynolds number are compared providing evidence of coolant ejection losses, and losses due to the separation off the exit slot lip and partitions. Additionally, differences in the level of losses, distribution of losses, and secondary flow vectors are presented for the different turbulence conditions at the different Reynolds numbers. The letterbox configuration has been found to have slightly reduced losses at a given flow rate compared with the gill slot. However, the letterbox requires an increased pressure drop for the same ejection flow. The present paper together with a related paper (2008, “Letterbox Trailing Edge Heat Transfer—Effects of Blowing Rate, Reynolds Number, and External Turbulence on Heat Transfer and Film Cooling Effectiveness,” ASME, Paper No. GT2008-50474), which documents letterbox heat transfer, is intended to provide designers with aerodynamic loss and heat transfer information needed for design evaluation and comparison with competing trailing edge designs.
Adiabatic and Overall Effectiveness Measurements of an Effusion Cooling Array for Turbine Endwall Application
Authors: Facchini Bruno , Tarchi Lorenzo , Toni Lorenzo , Ceccherini Alberto
Published: May 2010

An experimental analysis for the evaluation of adiabatic and overall effectiveness of an effusion cooling geometry is presented in this paper. Chosen configuration is a flat plate with 98 holes, with a feasible arrangement for a turbine endwall. Fifteen staggered rows with equal spanwise and streamwise pitches (Sx/D=Sy/D=8.0), a length to diameter ratio of 42.9 and an injection angle of 30 deg are investigated. Measurements have been done on two different test samples made both of plastic material and stainless steel. Adiabatic tests were carried out in order to obtain adiabatic effectiveness bidimensional maps. Even if a very low conductivity material polyvinyl chloride was used, adiabatic tests on a typical effusion geometry suffer, undoubtedly, from conductive phenomena: a full three-dimensional finite element method postprocessing procedure for gathered experimental data was therefore developed for reckoning thermal fluxes across the surface and then correctly obtaining adiabatic effectiveness distributions. The objective of the tests performed on the conductive plate, having the same flow parameters as the adiabatic ones, was the estimation of overall efficiency of the cooled region. Experimental measurements were carried out imposing two different crossflow Mach numbers, 0.15 and 0.40, and varying blowing ratio from 0.5 to 1.7; effectiveness of the cooled surface was evaluated with a steady-state technique, using thermochromic liquid crystal wide band formulation. Results show that the postprocessing procedure correctly succeeded in deducting undesired thermal fluxes across the plate in adiabatic effectiveness evaluation. The increasing blowing ratio effect leads to lower adiabatic effectiveness mean values, while it makes overall effectiveness to grow. Finally, Reynolds-averaged Navier–Stokes steady-state calculations were performed employing an open source computational fluid dynamics code: an adiabatic case has been simulated using both a standard and an anisotropic turbulence model. Numerical achievements have then been compared with experimental measurements.
Changes in Collagen With Aging Maintain Molecular Stability After Overload: Evidence From an In Vitro Tendon Model
Authors: Willett Thomas L. , Labow Rosalind S. , Aldous Ian G. , Avery Nick C. , Lee J. Michael
Published: May 2010

Soft tissue injuries are poorly understood at the molecular level. Previous work using differential scanning calorimetry (DSC) has shown that tendon collagen becomes less thermally stable with rupture. However, most soft tissue injuries do not result in complete tissue rupture but in damaging fiber overextension. Covalent crosslinking, which increases with animal maturity and age, plays an important role in collagenous fiber mechanics. It is also a determinant of tissue strength and is hypothesized to inhibit the loss of thermal stability of collagen due to mechanical damage. Controlled overextension without rupture was investigated to determine if overextension was sufficient to reduce the thermal stability of collagen in the bovine tail tendon (BTT) model and to examine the effects of aging on the phenomenon. Baseline data from DSC and hydrothermal isometric tension (HIT) techniques were compared between two groups: steers aged 24–30 months (young group), and skeletally mature bulls and oxen aged greater than five years (old group). Covalent crosslinks were quantified by ion exchange chromatography. Overextension resulted in reduced collagen thermal stability in the BTT model. The Young specimens, showing detectably lower tissue thermomechanical competence, lost more thermal stability with overextension than did the old specimens. The effect on old specimens, while smaller, was detectable. Multiple overextension cycles increased the loss of stability in the young group. Compositional differences in covalent crosslinking corresponded with tissue thermomechanical competence and therefore inversely with the loss of thermal stability. HIT testing gave thermal denaturation temperatures similar to those measured with DSC. The thermal stability of collagen was reduced by overextension of the tendon—without tissue rupture—and this effect was amplified by increased cycles of overextension. Increased tissue thermomechanical competence with aging seemed to mitigate the loss of collagen stability due to mechanical overextension. Surprisingly, the higher tissue thermomechanical competence did not directly correlate with the concentration of endogenous enzymatically derived covalent crosslinking on a mole per mole of collagen basis. It did, however, correlate with the percentage of mature and thermally stable crosslinks. Compositional changes in fibrous collagens that occur with aging affect fibrous collagen mechanics and partially determine the nature of mechanical damage at the intermolecular level. As techniques develop and improve, this new information may lead to important future studies concerning improved detection, prediction, and modeling of mechanical damage at much finer levels of tissue hierarchy than currently possible.
Time-Resolved DPIV Investigation of Pulsatile Flow in Symmetric Stenotic Arteries—Effects of Phase Angle
Authors: Karri Satyaprakash , Vlachos Pavlos P.
Published: May 2010

The effect of phase angle between pressure and flow waveforms on the flow characteristics in stenosed compliant vessels for coronary (phase angle (PA) of approximately −225 deg) and peripheral flows (PA of approximately −45 deg) is investigated using time resolved digital particle image velocimetry. Synthetic arteries with 50% and 75% stenosis at various physiological conditions with Reynolds numbers (Re) of 250, 350, and 450 and corresponding Womersley parameter (α) of 2.7, 3.2, and 3.7 were studied; wall-shear stresses (WSSs), oscillatory shear index (OSI), and recirculation lengths were determined. Additionally, flow transitional characteristics were examined using power spectral density (PSD), wavenumber spectra, and turbulence statistics of the axial velocity component. It is observed that the coronary flow conditions exhibit lower wall-shear stresses and larger recirculation lengths compared with peripheral flows. Mean peak shear stresses can be as high as 150 dyn/cm2 and 92 dyn/cm2 for peripheral and coronary flows, respectively, with 50% stenosis at Re=450 and α=3.7. These values can be as high as 590 dyn/cm2 and 490 dyn/cm2, respectively, for the same conditions with 75% stenosis. The OSI is close to 0.5 near the reattachment point indicating fluctuating WSS over the entire cardiac cycle for both 50% and 75% stenosis. For 50% stenosis, the OSI fluctuated at various locations over the length of the vessel indicating several regions of recirculation in contrast to a distinct recirculation region observed for 75% stenosis. PSD plots across various cross-sections along the length of the vessel and wavenumber spectra along the centerline indicate that turbulence occurs only for 75% stenosis. For coronary flows, the streamwise locations where the flow transitions to turbulence and relaminarizes are approximately one diameter upstream compared with peripheral flows indicating that coronary flows are more susceptible to turbulence.
Strain Measurement of Pure Titanium Covered With Soft Tissue Using X-Ray Diffraction
Authors: Fujisaki Kazuhiro , Tadano Shigeru
Published: May 2010

Measurement of the stress and strain applied to implants and bone tissue in the human body are important for fracture prediction and evaluations of implant adaptation. The strain of titanium (Ti) materials can be measuring by X-ray diffraction techniques. This study applied X-ray diffraction to the skin tissue-covered Ti. Characteristic X-rays of Mo Kα were used and the X-rays diffracted from the Ti were detected through the covering skin tissue. The X-ray absorption by skin tissue is large under the diffracted X-rays detected in low angles because the length of penetration depends on the angle of inclination, equal to the Bragg angle. The effects of skin tissue to detect the diffracted X-rays were investigated in the experiments. And the strain measurements were conducted under bending loads applied to the Ti specimen. The effect of skin tissue was absorption of X-rays as well as the X-rays scattered from the physiological saline contained in the tissue. The X-rays scattered by the physiological saline creates a specific background pattern near the peaks from the (002) and (011) lattice planes of Ti in the X-ray diffraction profile. Diffracted X-rays from the Ti were detected after being transmitted through 1 mm thick skin tissue by Mo Kα. Individual peaks such as (010), (002), (011), and (110) were clearly established by using a parallel beam arrangement. The strains of (110) lattice planes were measured with or without the tissue cover were very similar. The strain of the (110) lattice planes of Ti could be measured by Mo Kα when the Ti specimen was located under the skin tissue.
Optimal Control of the Spine System
Authors: Xu Yunfei , Choi Jongeun , Reeves N. Peter , Cholewicki Jacek
Published: May 2010

The goal of this work is to present methodology to first evaluate the performance of an in vivo spine system and then to synthesize optimal neuromuscular control for rehabilitation interventions. This is achieved (1) by determining control system parameters such as static feedback gains and delays from experimental data, (2) by synthesizing the optimal feedback gains to attenuate the effect of disturbances to the system using modern control theory, and (3) by evaluating the robustness of the optimized closed-loop system. We also apply these methods to a postural control task, with two different control strategies, and evaluate the robustness of the spine system with respect to longer latencies found in the low back pain population. This framework could be used for rehabilitation design. To this end, we discuss several future research needs necessary to implement our framework in practice.
3D Critical Plaque Wall Stress Is a Better Predictor of Carotid Plaque Rupture Sites Than Flow Shear Stress: An In Vivo MRI-Based 3D FSI Study
Authors: Teng Zhongzhao , Canton Gador , Yuan Chun , Ferguson Marina , Yang Chun , Huang Xueying , Zheng Jie , Woodard Pamela K. , Tang Dalin
Published: May 2010

Atherosclerotic plaque rupture leading to stroke is the major cause of long-term disability as well as the third most common cause of mortality. Image-based computational models have been introduced seeking critical mechanical indicators, which may be used for plaque vulnerability assessment. This study extends the previous 2D critical stress concept to 3D by using in vivo magnetic resonance image (MRI) data of human atherosclerotic carotid plaques and 3D fluid-structure interaction (FSI) models to: identify 3D critical plaque wall stress (CPWS) and critical flow shear stress (CFSS) and to investigate their associations with plaque rupture. In vivo MRI data of carotid plaques from 18 patients scheduled for endarterectomy were acquired using histologically validated multicontrast protocols. Of the 18 plaques, histology-confirmed that six had prior rupture (group 1) as evidenced by presence of ulceration. The remaining 12 plaques (group 2) contained no rupture. The 3D multicomponent FSI models were constructed for each plaque to obtain 3D plaque wall stress (PWS) and flow shear stress (FSS) distributions. Three-dimensional CPWS and CFSS, defined as maxima of PWS and FSS from all vulnerable sites, were determined for each plaque to investigate their association with plaque rupture. Slice-based critical PWS and FSS were also calculated for all slices for more detailed analysis and comparison. The mean 3D CPWS of group 1 was 263.44 kPa, which was 100% higher than that from group 2 (132.77, p=0.03984). Five of the six ruptured plaques had 3D CPWS sites, matching the histology-confirmed rupture sites with an 83% agreement. Although the mean 3D CFSS (92.94 dyn/cm2) for group 1 was 76% higher than that for group 2 (52.70 dyn/cm2), slice-based CFSS showed no significant difference between the two groups. Only two of the six ruptured plaques had 3D CFSS sites matching the histology-confirmed rupture sites with a 33% agreement. CFSS had a good correlation with plaque stenosis severity (R2=0.40 with an exponential function fitting 3D CFSS data). This in vivo MRI pilot study using plaques with and without rupture demonstrates that 3D critical plaque wall stress values are more closely associated with atherosclerotic plaque rupture then critical flow shear stresses. Critical wall stress values may become indicators of high risk sites of rupture. Future work with a larger population will establish a possible CPWS-based plaque vulnerability classification.
Flow and Particle Dispersion in a Pulmonary Alveolus—Part II: Effect of Gravity on Particle Transport
Authors: Chhabra Sudhaker , Prasad Ajay K.
Published: May 2010

The acinar region of the human lung comprises about 300×106 alveoli, which are responsible for gas exchange between the lung and the blood. As discussed in Part I (Chhabra and Prasad, “Flow and Particle Dispersion in a Pulmonary Alveolus—Part I: Velocity Measurements and Convective Particle Transport,” ASME J. Biomech. Eng., 132, p. 051009), the deposition of aerosols in the acinar region can either be detrimental to gas exchange (as in the case of harmful particulate matter) or beneficial (as in the case of inhalable pharmaceuticals). We measured the flow field inside an in-vitro model of a single alveolus mounted on a bronchiole and calculated the transport and deposition of massless particles in Part I. This paper focuses on the transport and deposition of finite-sized particles ranging from 0.25 μm to 4 μm under the combined influence of flow-induced advection (computed from velocity maps obtained by particle image velocimetry) and gravitational settling. Particles were introduced during the first inhalation cycle and their trajectories and deposition statistics were calculated for subsequent cycles for three different particle sizes (0.25 μm, 1 μm, and 4 μm) and three alveolar orientations. The key outcome of the study is that particles ≤0.25 μm follow the fluid streamlines quite closely, whereas midsize particles (dp=1 μm) deviate to some extent from streamlines and exhibit complex trajectories. The motion of large particles ≥4 μm is dominated by gravitational settling and shows little effect of fluid advection. Additionally, small and midsize particles deposit at about two-thirds height in the alveolus irrespective of the gravitational orientation whereas the deposition of large particles is governed primarily by the orientation of the gravity vector.
The Influence of Bioreactor Geometry and the Mechanical Environment on Engineered Tissues
Authors: Osborne J. M. , O’Dea R. D. , Whiteley J. P. , Byrne H. M. , Waters S. L.
Published: May 2010

A three phase model for the growth of a tissue construct within a perfusion bioreactor is examined. The cell population (and attendant extracellular matrix), culture medium, and porous scaffold are treated as distinct phases. The bioreactor system is represented by a two-dimensional channel containing a cell-seeded rigid porous scaffold (tissue construct), which is perfused with a culture medium. Through the prescription of appropriate functional forms for cell proliferation and extracellular matrix deposition rates, the model is used to compare the influence of cell density-, pressure-, and culture medium shear stress-regulated growth on the composition of the engineered tissue. The governing equations are derived in O’Dea et al. “A Three Phase Model for Tissue Construct Growth in a Perfusion Bioreactor,” Math. Med. Biol., in which the long-wavelength limit was exploited to aid analysis; here, finite element methods are used to construct two-dimensional solutions to the governing equations and to investigate thoroughly their behavior. Comparison of the total tissue yield and averaged pressures, velocities, and shear stress demonstrates that quantitative agreement between the two-dimensional and long-wavelength approximation solutions is obtained for channel aspect ratios of order 10−2 and that much of the qualitative behavior of the model is captured in the long-wavelength limit, even for relatively large channel aspect ratios. However, we demonstrate that in order to capture accurately the effect of mechanotransduction mechanisms on tissue construct growth, spatial effects in at least two dimensions must be included due to the inherent spatial variation of mechanical stimuli relevant to perfusion bioreactors, most notably, fluid shear stress, a feature not captured in the long-wavelength limit.
Preparing for the Future: Reducing Gas Turbine Environmental Impact—IGTI Scholar Lecture
Authors: Cumpsty Nicholas A.
Published: May 2010

In the long term, the price of fuel will rise and it is now urgent to reduce carbon dioxide emissions to avoid catastrophic climate change. This lecture looks at power plant for electricity generation and aircraft propulsion, considering likely limits and possibilities for improvement. There are lessons from land-based gas turbines, which can be applied to aircraft, notably the small increases in efficiency from further increase in pressure ratio and turbine inlet temperature. Land-based gas turbines also point to the benefit of combining the properties of water with those of air to raise efficiency. Whereas the incentive to raise efficiency and reduce CO2 will force an increase in complexity of land-based power plant, the opportunities for this with aircraft are more limited. One of the opportunities with aircraft propulsion is to consider the whole aircraft operation and specification. Currently the specifications for new aircraft of take-off and climb thrust are not fully consistent with designing the engine for minimum fuel consumption and this will be addressed in some depth in the lecture. Preparing for the future entails alerting engineers to important possibilities and limitations associated with gas turbines which will mitigate climate change due to carbon dioxide emissions.
Some Lessons Learned
Authors: Cumpsty N. A.
Published: May 2010

This paper looks at some familiar results, concepts, and ideas in a different way, drawing out some common unifying threads. The topics addressed are one-, two-, and three-dimensions; axisymmetry and its breakdown; gaps and leakage paths; and computation fluid dynamics (CFD) and the limitation of perfection. Certain overlapping issues come up in each of the topic areas.
Experimental and Numerical Investigations on the Origins of the Bodywork Effect (K-Effect)
Authors: Coghe F. , Nsiampa N. , Rabet L. , Dyckmans G.
Published: May 2010

The integration of a high-hardness steel armor plate inside the bodywork of a vehicle may result in a decrease in the overall ballistic resistance. This phenomenon is referred to as the bodywork effect. The effect was examined for a 5.56×45 mm North Atlantic Treaty Organization (NATO) Ball projectile. Previously reported experimental work has confirmed the numerically based assumption that the bodywork effect was due to the flattening of the tip of the projectile upon perforation of the frontal bodywork plate prior to hitting the integrated armor. The amount of qualitative and quantitative experimental data has now been extended. In order to eliminate the data dispersion observed after perforating the bodywork, an adapted projectile geometry with a truncated nose was fired directly against the armor plate. Ballistic testing also involved firing a soft-core 5.56×45 mm projectile for which a similar mechanism was observed. A finite element code was used to simulate the impact process for the different types of projectiles. The parameters of the selected strength and failure models were experimentally determined for the high-hardness armor plate. As to the ballistic limit velocity and plugging morphology there is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities.
Statistical Comparisons Between Qualification Tests for Gun-Fired Projectiles
Authors: Cordes J. A. , Lee J. , Myers T. L. , Hader G. , Reinhardt L. , Kessler C. , Gray N. , Guevara M. A.
Published: May 2010

The U.S. Army uses several types of tests to increase the reliability of gun-fired munitions. Systems, subsystems, and components are gun fired to assess reliability. When failures are found, root-cause investigations are completed and parts may be redesigned. For instance, the 155 mm projectile Excalibur uses several types of tests to find failures and build reliability. Components are tested in a rail gun, a new soft-catch gun, and in soft recovery vehicles. With the rail gun, test projectiles are fired from a worn gun tube into a trough of water. The soft-catch gun, a hybrid system using both air and water, has a standard cannon tube and a series of catch tubes to stop a projectile. The third type of test, a soft recovery vehicle, uses a modified tactical Excalibur with a parachute for a soft landing. All three types of tests have on-board recorders to capture ballistic accelerations. Accelerometer data are used in failure investigations, redesign parts, and to design new projectiles. The purpose of this paper is to compare accelerations from different types of ballistic tests. Comparisons were done to determine if the tests were in the same statistical family. Comparisons are made for a United States MACS 5 charge. The maximum axial forces were the same for the soft-catch gun and the soft recovery vehicle. In the balloting directions, the rail gun and soft recovery vehicle had similar forces. The set forward forces differed in all three cases, reflecting the different catch mechanisms for the projectiles. Comparisons of g-forces were also made using shock response spectra. The shock response indicated that the damage potential is greatest for the rail gun tests, consistent with an increase rate of failures for some electronics.
The Conception of the Segmented Kinetic Energy Penetrators for Tank Guns
Authors: Magier Mariusz
Published: May 2010

In this paper we present possibilities of increasing the depth of penetration through a steel plate by using segmented kinetic energy penetrators. Conclusions about the possibilities of increasing the penetration depth were formulated based on the critical review of the literature, simulations, and firing test results. A new concept called “forced segmented penetration,” where applied penetrator is composed of two tungsten alloy pieces connected by a screwed steel muff, is presented in this paper. The axial deformation of the connecting muff during the penetration process results in a decrease in the distance between tungsten segments. For this reason the rear segment can hit the front segment to give it some additional kinetic energy, enhancing the penetration depth. Such type of segmented penetration phenomena was not presented earlier. The numerical analyses of the segmented penetrator of the new design are presented in this paper.
Extending Castigliano’s Theorems to Model the Behavior of Coupled Systems
Authors: Dym Clive L.
Published: May 2010

Extensions of the Castigliano theorems are developed in the context of modeling the behavior of both discrete coupled linear systems and various coupled beams. It is shown that the minimization of the displacement of a parallel system determined from Castigliano’s second theorem can be used to formally define the apportionment of loads among the system elements, while the minimization of the load in a series system determined from Castigliano’s first theorem can be used to formally define the apportionment of the displacement among the system elements. These extensions provide a means for apportioning loads in coupled continuous systems, as will be shown for the cases of coupled cantilever Timoshenko beams supporting discrete and continuous loads.
Electrical and reliability performances of nitrogen-incorporated silicon carbide dielectric by chemical vapor deposition
Authors: Cheng Yi-Lung , Chen Shiuan-An , Chiu Tai-Jung , Wu Jiung , Wei Bor-Jou , Chang Hung-Jui
Published: May 2010

The influence of nitrogen flow on the electrical properties of silicon carbide (SiC) barrier dielectrics prepared by plasma-enhanced chemical vapor deposition was reported. Experimental results showed that the leakage current and dielectric constant of the SiC film are reduced by increasing nitrogen flow rate. The thermal stability of the SiC film is greatly improved by doping nitrogen. The reliability of SiC barrier dielectrics deposited at various nitrogen flow rates was also investigated. The performance of dielectric breakdown is significantly improved for the nitrogen-incorporated SiC film due to its better capability in preventing copper (Cu) thermal diffusion. In addition, Cu electromigration performance is slightly enhanced by capping the SiC film deposited at a higher nitrogen flow rate because of the reinforcement of bonding strength with Cu.
Effect of iodotrifluoromethane plasma for reducing ultraviolet light irradiation damage in dielectric film etching processes
Authors: Ichihashi Yoshinari , Ishikawa Yasushi , Shimizu Ryu , Samukawa Seiji
Published: May 2010

Iodotrifluoromethane (CF3I) gas is one of the environmentally conscious perfluorocarbon gases because it has a very low global warming potential. The authors have found that CF3I gas plasma drastically reduces ultraviolet (UV) photon irradiation of ∼4.0 eV, which corresponds to the excitation energy at silicon dioxide (SiO2)/silicon (Si) interfaces, in comparison with octafluorocyclobutane (C4F8) gas. This results in reducing UV irradiation damage in dielectric film etching processes, which was experimentally confirmed by evaluating charge-pumping currents in metal insulator semiconductor field effect transistors fabricated by using CF3I gas etching. They have also demonstrated that a novel etching method using pulse-time modulation of CF3I gas plasma for the first time further reduced UV light irradiation damage.
Gβγ Activates GSK3 to Promote LRP6-Mediated β-Catenin Transcriptional Activity
Authors: Jernigan Kristin K. , Cselenyi Christopher S. , Thorne Curtis A. , Hanson Alison J. , Tahinci Emilios , Hajicek Nicole , Oldham William M. , Lee Laura A. , Hamm Heidi E. , Hepler John R. , Kozasa Tohru , Linder Maurine E. , Lee Ethan
Published: May 2010

A
Xenopus
reconstitution system reveals that the G protein Gβγ subunit contributes to β-catenin stabilization.
Maintaining Copper Supplies
Authors: Adler Elizabeth M.
Published: May 2010

Cardiac copper deficiency elicits a circulating signal that leads to an increase in circulating copper and in the abundance of a copper transporter in liver and intestine.
Lipophilic Bisphosphonates Are Potent Inhibitors of
Plasmodium
Liver-Stage Growth
Authors: Singh Agam Prasad , Zhang Yonghui , No Joo-Hwan , Docampo Roberto , Nussenzweig Victor , Oldfield Eric
Published: May 2010

Nitrogen-containing bisphosphonates, drugs used to treat bone resorption diseases, also have activity against a broad range of protists, including blood-stage
Plasmodium
spp. Here, we show that new-generation “lipophilic” bisphosphonates designed as anticancer agents that block protein prenylation also have potent activity against
Plasmodium
liver stages, with a high (>100) therapeutic index. Treatment of mice with the bisphosphonate BPH-715 and challenge with
Plasmodium berghei
sporozoites revealed complete protection (no blood-stage parasites after 28 days). There was also activity against blood-stage forms
in vitro
and a 4-day delay in the prepatent period
in vivo
. The lipophilic bisphosphonates have activity against a
Plasmodium
geranylgeranyl diphosphate synthase (GGPPS), as well as low nM activity against human farnesyl and geranylgeranyl diphosphate synthases. The most active inhibitor
in vitro
and
in vivo
had enzyme inhibitory activity similar to that of the other, less active compounds but was more lipophilic. Lipophilic bisphosphonates are thus promising leads for novel antimalarials that target liver-stage infection.