bluuebunny/crossref_metadata_2025 huggingface dataset:
The performance of steady‐state harmonic magnetic resonance elastography when applied to viscoelastic materials
Authors: Doyley Marvin M. , Perreard Irina , Patterson Adam. J. , Weaver John B. , Paulsen Keith M.
Published: July 2010

Purpose:

The clinical efficacy of breast elastography may be limited when the authors employ the assumption that soft tissues exhibit linear, frequency‐independent isotropic mechanical properties during the recovery of shear modulus. Thus, the purpose of this research was to evaluate the degradation in performance incurred when linear‐elastic MR reconstruction methods are applied to phantoms that are fabricated using viscoelastic materials.

Methods:

To develop phantoms with frequency‐dependent mechanical properties, the authors measured the complex modulus of two groups of cylindrical‐shaped gelatin samples over a wide frequency range (up to 1 kHz) with the established principles of time‐temperature superposition (TTS). In one group of samples, the authors added varying amounts of agar (1%–4%); in the other group, the authors added varying amounts of sucrose (2.5%–20%). To study how viscosity affected the performance of the linear‐elastic reconstruction method, the authors constructed an elastically heterogeneous MR phantom to simulate the case where small viscoelastic lesions were surrounded by relatively nonviscous breast tissue. The breast phantom contained four linear, viscoelastic spherical inclusions (10 mm diameter) that were embedded in normal gelatin. The authors imaged the breast phantom with a clinical prototype of a MRE system and recovered the shear‐modulus distribution using the overlapping‐subzone‐linear‐elastic image‐reconstruction method. The authors compared the recovered shear modulus to that measured using the TTS method.

Results:

The authors demonstrated that viscoelastic phantoms could be fabricated by including sucrose in the gelation process and that small viscoelastic inclusions were visible in MR elastograms recovered using a linear‐elastic MR reconstruction process; however, artifacts that degraded contrast and spatial resolution were more prominent in highly viscoelastic inclusions. The authors also established that the accuracy of the MR elastograms depended on the degree of viscosity that the inclusion exhibited.

Conclusions:

The results demonstrated that reconstructing shear modulus from other constitutive laws, such as viscosity, should improve both the accuracy and quality of MR elastograms of the breast.
Predictive modeling of lung motion over the entire respiratory cycle using measured pressure‐volume data, 4DCT images, and finite‐element analysis
Authors: Eom Jaesung , Xu Xie George , De Suvranu , Shi Chengyu
Published: July 2010

Purpose:

Predicting complex patterns of respiration can benefit the management of the respiratory motion for radiation therapy of lung cancer. The purpose of the present work was to develop a patient‐specific, physiologically relevant respiratory motion model which is capable of predicting lung tumor motion over a complete normal breathing cycle.

Methods:

Currently employed techniques for generating the lung geometry from four‐dimensional computed tomography data tend to lose details of mesh topology due to excessive surface smoothening. Some of the existing models apply displacement boundary conditions instead of the intrapleural pressure as the actual motive force for respiration, while others ignore the nonlinearity of lung tissues or the mechanics of pleural sliding. An intermediate nonuniform rational basis spline surface representation is used to avoid multiple geometric smoothing procedures used in the computational mesh preparation. Measured chest pressure‐volume relationships are used to simulate pressure loading on the surface of the model for a given lung volume, as in actual breathing. A hyperelastic model, developed from experimental observations, has been used to model the lung tissue material. Pleural sliding on the inside of the ribcage has also been considered.

Results:

The finite‐element model has been validated using landmarks from four patient CT data sets over 34 breathing phases. The average differences of end‐inspiration in position between the landmarks and those predicted by the model are observed to be for Patient P1, for Patient P2, for Patient P3, and for Patient P4 in the magnitude of error vector, respectively. The average errors of prediction at landmarks over multiple breathing phases in superior‐inferior direction are less than 3 mm.

Conclusions:

The prediction capability of pressure‐volume curve driven nonlinear finite‐element model is consistent over the entire breathing cycle. The biomechanical parameters in the model are physiologically measurable, so that the results can be extended to other patients and additional neighboring organs affected by respiratory motion.
Mechanistic formulation of a lineal‐quadratic‐linear (LQL) model: Split‐dose experiments and exponentially decaying sources
Authors: Guerrero Mariana , Carlone Marco
Published: July 2010

Purpose:

In recent years, several models were proposed that modify the standard linear‐quadratic (LQ) model to make the predicted survival curve linear at high doses. Most of these models are purely phenomenological and can only be applied in the particular case of acute doses per fraction. The authors consider a mechanistic formulation of a linear‐quadratic‐linear (LQL) model in the case of split‐dose experiments and exponentially decaying sources. This model provides a comprehensive description of radiation response for arbitrary dose rate and fractionation with only one additional parameter.

Methods:

The authors use a compartmental formulation of the LQL model from the literature. They analytically solve the model's differential equations for the case of a split‐dose experiment and for an exponentially decaying source. They compare the solutions of the survival fraction with the standard LQ equations and with the lethal‐potentially lethal (LPL) model.

Results:

In the case of the split‐dose experiment, the LQL model predicts a recovery ratio as a function of dose per fraction that deviates from the square law of the standard LQ. The survival fraction as a function of time between fractions follows a similar exponential law as the LQ but adds a multiplicative factor to the LQ parameter. The LQL solution for the split‐dose experiment is very close to the LPL prediction. For the decaying source, the differences between the LQL and the LQ solutions are negligible when the half‐life of the source is much larger than the characteristic repair time, which is the clinically relevant case.

Conclusions:

The compartmental formulation of the LQL model can be used for arbitrary dose rates and provides a comprehensive description of dose response. When the survival fraction for acute doses is linear for high dose, a deviation of the square law formula of the recovery ratio for split doses is also predicted.
Effects of breathing variation on gating window internal target volume in respiratory gated radiation therapya)
Authors: Cai Jing , McLawhorn Robert , Read Paul W. , Larner James M. , Yin Fang‐fang , Benedict Stanley H. , Sheng Ke
Published: July 2010

Purpose:

To investigate the effects of breathing variation on gating window internal target volume in respiratory gated radiation therapy.

Method and Materials:

Two‐dimensional dynamic MRI (dMRI) of lung motion was acquired in ten volunteers and eight lung cancer patients. Resorted dMRI using 4DCT acquisition method (RedCAM) was generated for selected subjects by simulating the image rebinning process. A dynamic software generated phantom (dSGP) was created by moving a solid circle (to mimic the “tumor”) with dMRI‐determined motion trajectories. The gating window internal target area (, 2D counterpart of ) was determined from both RedCAM and dSGP/dMRI. Its area , major axis , minor axis , and similarity were calculated and compared.

Results:

In the phantom study of 3 cm tumor, measurements of the from dSGP (, , and ) are significantly greater than those from RedCAM (, , and ). Similarly, the differences are significantly greater for the 1 cm tumor (, , and in dSGP; , , and in RedCAM). In patient studies, measurements of the from dMRI (, , and ) are also significantly greater than those from RedCAM (, , and ). Similarities were , , and in the 3 cm tumor phantom, 1 cm tumor phantom, and patient studies, respectively.

Conclusion:

can be underestimated by 4DCT due to breathing variations. An additional margin may be needed to account for this potential error in generating a . Cautions need to be taken when generating from 4DCT in respiratory gated radiation therapy, especially for small tumors with a large motion range .
Deformable lung registration between exhale and inhale CT scans using active cells in a combined gradient force approach
Authors: Yim Yeny , Hong Helen , Shin Yeong Gil
Published: July 2010

Purpose:

This article proposes an accurate and fast deformable registration method between end‐exhale and end‐inhale CT scans that can handle large lung deformations and accelerate the registration process.

Methods:

The density correction method is applied to reduce the density difference between two CT scans due to respiration and gravity. The lungs are globally aligned by affine registration and nonlinearly deformed by a demons algorithm using a combined gradient force and active cells. The use of combined gradient force allows a fast convergence in the lung regions with a weak gradient of the target image by taking into account the gradient of the source image. The use of active cells helps to accelerate the registration process and reduce the degree of deformation folding because it avoids unnecessary computation of the displacement for well‐matched lung regions.

Results:

The proposed method was tested with end‐exhale and end‐inhale CT scans acquired from eight normal subjects. The performance of the proposed method was evaluated through comparisons of methods that use a target gradient force or a combined gradient force, as well as methods with and without active cells. The proposed method with combined gradient force led to significantly higher accuracy compared to the method with target gradient force. For the entire lung, the proposed method provided a mean landmark error of . For the lower 30% part of the lungs, the Dice similarity coefficient and normalized cross correlation of the proposed method were higher than the original demon algorithm by 2.3% and 2.2% , respectively. The proposed method with an active cell led to fewer voxels with negative Jacobian values and a 55% decrease of processing time compared to the method without an active cell.

Conclusions:

The results show that the proposed method can accurately register lungs with large deformations and can considerably reduce the processing time. The proposed deformable registration technique can be used for quantitative assessments of air trapping in obstructive lung disease and for tumor motion tracking during the planning of radiotherapy treatments.
The water equivalence of solid phantoms for low energy photon beams
Authors: Hill Robin , Kuncic Zdenka , Baldock Clive
Published: July 2010

Purpose:

To compare and evaluate the dosimetric water equivalence of several commonly used solid phantoms for low energy photon beams.

Methods:

A total of ten different solid phantom materials was used in the study. ThePENELOPE Monte Carlo code was used to calculate depth doses and beam profiles in all the phantom materials as well as the dose to a small water voxel at the surface of the solid phantom. These doses were compared to the corresponding doses calculated in a water phantom. The primary photon beams used ranged in energy from 50 to 280 kVp.

Results:

A number of phantom materials had excellent agreement in dose compared to water for all the x‐ray beam energies studied. RMI457 Solid Water, Virtual Water, PAGAT, A150, and Plastic Water DT all had depth doses that agreed with those in water to within 2%. For these same phantom materials, the dose changes in the water voxel at the surface of the solid phantom were within 2%, except for A150, which agreed to within 2.7%. By comparison, the largest differences in depth doses occurred for Plastic Water (−21.7%) and polystyrene (17.6%) for the 50 kVp energy photon beam and 8 cm diameter field size. Plastic Water gave the largest difference in the normalized beam profiles with differences of up to 3.5% as compared to water. Surface dose changes, due to the presence of the solid phantom acting as the backscatter material, were found to be up to 9.1% for polystyrene with significant differences also found for Plastic Water, PMMA, and RW3 phantoms.

Conclusions:

The following solid phantoms can be considered water equivalent and are recommended for relative dosimetry of low energy photon beams: A150, PAGAT, Plastic Water DT, RMI457 Solid Water, and Virtual Water. However, the following solid phantoms give significant differences, compared to water, in depth doses, profiles, and/or in surface doses due to backscatter changes: Plastic Water, PMMA, polystyrene, PRESAGE, and RW3.
Measurement and verification of positron emitter nuclei generated at each treatment site by target nuclear fragment reactions in proton therapy
Authors: Miyatake Aya , Nishio Teiji , Ogino Takashi , Saijo Nagahiro , Esumi Hiroyasu , Uesaka Mitsuru
Published: July 2010

Purpose:

The purpose of this study is to verify the characteristics of the positron emitter nuclei generated at each treatment site by proton irradiation.

Methods:

Proton therapy using a beam on‐line PET system mounted on a rotating gantry port (BOLPs‐RGp), which the authors developed, is provided at the National Cancer Center Kashiwa, Japan. BOLPs‐RGp is a monitoring system that can confirm the activity distribution of the proton irradiated volume by detection of a pair of annihilation gamma rays coincidentally from positron emitter nuclei generated by the target nuclear fragment reactions between irradiated proton nuclei and nuclei in the human body. Activity is measured from a start of proton irradiation to a period of 200 s after the end of the irradiation. The characteristics of the positron emitter nuclei generated in a patient's body were verified by the measurement of the activity distribution at each treatment site using BOLPs‐RGp.

Results:

The decay curves for measured activity were able to be approximated using two or three half‐life values regardless of the treatment site. The activity of half‐life value of about 2 min was important for a confirmation of the proton irradiated volume.

Conclusions:

In each proton treatment site, verification of the characteristics of the generated positron emitter nuclei was performed by using BOLPs‐RGp. For the monitoring of the proton irradiated volume, the detection of generated in a human body was important.
Subtraction lung image for evaluating pulmonary ventilation in xenon‐enhanced CT
Authors: Sase Shigeru , Nakano Hideharu , Suzuki Hiroshi , Honda Mitsuru
Published: July 2010

Purpose:

The goal of this work was to develop a method of transforming a xenon‐enhanced CT (Xe‐CT) image of the lung, so as to overlap well with its baseline CT image, and creating a subtraction image (enhanced image minus baseline image), and to demonstrate the possibility of evaluating pulmonary ventilation using the subtraction image.

Methods:

Eight healthy menunderwent Xe‐CT lung studies. In protocol 1 for five subjects, 30% nonradioactive xenon (Xe) was inhaled for 2 min (washin) followed by air breathing for 4 min (washout). In protocol 2 for three subjects, only washin (30% Xe) for 2 min was applied. In each study, a specific range of the thorax (30 mm) in the supine position was scanned craniocaudally three times in the helical mode: At the start and end of washin and at the end of washout in protocol 1 and at 1 min intervals from the start to end of washin in protocol 2. After each study, 10‐mm‐thick CT images were reconstructed to have similar anatomical structures throughout the study. Two‐dimensional geometrical warping was performed on enhanced CT images so that they could geometrically overlap with the baseline CT image. Second to eighth degree polynomials were applied to the warping functions.

Results:

It was derived from the Kety model that subtraction images during washin would directly reflect pulmonary ventilation. Geometrical warping achieved an increase of 0.3%–22.0% in the area, for which ventilation could be evaluated in the subtraction image. In the cases in protocol 2 where the initial lung volume was well retained throughout the study, the ratios of the specific ventilation from the subtraction image to that from the specific ventilation map wereandfor the right and left lungs, respectively.

Conclusions:

A subtraction lung image during washin would provide quantitative information on pulmonary ventilation when the baseline and enhanced images could have close lung volume and these two images could overlap well. Image subtraction requires only two scans and therefore less radiation exposure compared to ordinary protocols in Xe‐CT. The proposed Xe‐CT subtraction method with the geometrical warping technique could be clinically utilized for evaluating pulmonary ventilation.
Dosimetric verification of the anisotropic analytical algorithm in lung equivalent heterogeneities with and without bone equivalent heterogeneities
Authors: Ono Kaoru , Endo Satoru , Tanaka Kenichi , Hoshi Masaharu , Hirokawa Yutaka
Published: July 2010

Purpose: In this study, the authors evaluated the accuracy of dose calculations performed by the convolution/superposition based anisotropic analytical algorithm (AAA) in lung equivalent heterogeneities with and without bone equivalent heterogeneities.

Methods: Calculations of PDDs using the AAA and Monte Carlo simulations (MCNP4C) were compared to ionization chamber measurements with a heterogeneous phantom consisting of lung equivalent and bone equivalent materials. Both 6 and 10 MV photon beams of and field sizes were used for the simulations. Furthermore, changes of energy spectrum with depth for the heterogeneous phantom using MCNP were calculated.

Results: The ionization chamber measurements and MCNP calculations in a lung equivalent phantom were in good agreement, having an average deviation of only . For both 6 and 10 MV beams, the average deviation was less than 2% for the and fields in the water‐lung equivalent phantom and the field in the water‐lung‐bone equivalent phantom. Maximum deviations for the field in the lung equivalent phantom before and after the bone slab were 5.0% and 4.1%, respectively. The Monte Carlo simulation demonstrated an increase of the low‐energy photon component in these regions, more for the field compared to the field.

Conclusions: The low‐energy photon by Monte Carlo simulation component increases sharply in larger fields when there is a significant presence of bone equivalent heterogeneities. This leads to great changes in the build‐up and build‐down at the interfaces of different density materials. The AAA calculation modeling of the effect is not deemed to be sufficiently accurate.
PTIP Promotes Chromatin Changes Critical for Immunoglobulin Class Switch Recombination
Authors: Daniel Jeremy A. , Santos Margarida Almeida , Wang Zhibin , Zang Chongzhi , Schwab Kristopher R. , Jankovic Mila , Filsuf Darius , Chen Hua-Tang , Gazumyan Anna , Yamane Arito , Cho Young-Wook , Sun Hong-Wei , Ge Kai , Peng Weiqun , Nussenzweig Michel C. , Casellas Rafael , Dressler Gregory R. , Zhao Keji , Nussenzweig André
Published: July 2010

PTIP in Immunoglobulin Switching

One of the hallmarks of humoral immunity is the ability of immunoglobulins (Ig) to undergo class switch recombination (CSR). Through genetic recombining of the Ig heavy chain, Igs maintain their antigen specificity but gain the ability to interact with different cell surface receptors required for successful pathogen clearance. CSR requires transcription at the Ig heavy chain locus to initiate genetic rearrangement. Changes in chromatin accessibility are thought to promote CSR-associated transcription.

Daniel
et al.

(p.
917
, published online 29 July; see the Perspective by

Singh and Demarco

) now show that trimethylation of histone 3 at lysine 4 (H3K4me3) controls the accessibility of the Ig heavy chain locus to CSR and that PTIP (Pax interaction with transcription-activation domain protein-1), a component of the histone methylase complex, is required for this modification. Mouse PTIP-deficient B cells exhibited impaired CSR. PTIP was required both for the recruitment RNA Polymerase II and for subsequent chromatin remodeling, including histone acetylation, which occurs during CSR. Largely independent of its function in transcription initiation in CSR, PTIP also associated with double-stranded DNA breaks during CSR and promoted genome stability. These dual functions of PTIP may be important for the precise coordination of chromatin accessibility and recombination required during CSR.
The preparation of 3H-labeled acyclic nucleoside phosphonates and study of their stability
Authors: Elbert Tomáš , Břehová Petra , Holý Antonín
Published: July 2010

9-(2-Phosphonomethoxyethyl)-2,6-diamino-[8-3H]purine (4), 9-(2-phosphonomethoxyethyl)-[8-3H]guanine (6) and (R)-9-(2-phosphonomethoxypropyl)-[8-3H]adenine (11) with specific activities of 10.9, 7.9 and 16 Ci/mmol, respectively, were prepared by a catalytic dehalogenation of the corresponding 8-bromo derivatives 1, 2 and 9. The rate of the exchange of the tritium label on C-8 of the purine ring in title compounds with the hydrogen of water under physiological pH at 20 °C was studied using 3H NMR. The loss of 3H-label attained 7% in [8-3H]tenofovir (11), 10% in [8-3H]PMEDAP (4) and 12% in [8-3H]PMEG (6) after the period of 3 weeks. Storage at a temperature of –196 °C in liquid nitrogen ensured a better than 97% radiochemical purity of the prepared labeled compounds even after a six-month period.
TOPOLOGICAL BLACK HOLES OF GAUSS–BONNET–YANG–MILLS GRAVITY
Authors: DEHGHANI M. H. , BOSTANI N. , POURHASAN R.
Published: July 2010

We present the asymptotically AdS solutions of Gauss–Bonnet gravity with hyperbolic horizon in the presence of a non-Abelian Yang–Mills field with the gauge semisimple group So(n(n-1)/2-1, 1). We investigate the properties of these solutions and find that the non-negative mass solutions in six and higher dimensions are real everywhere with spacelike singularities. They present black holes with one horizon and have the same causal structure as the Schwarzschild space–time. The solutions in five dimensions or the solutions in higher dimensions with negative mass are not real everywhere. In these cases, one needs a transformation to make the solutions real. These solutions may present a naked singularity, an extreme black hole, a black hole with two horizons, or a black hole with one horizon.
SYNTHESIS AND MORPHOLOGICAL CONTROL OF MONODISPERSED MICROSIZED CERIA PARTICLES
Authors: YIN S. , MINAMIDATE Y. , SATO T.
Published: July 2010

The morphological control of crystalline cerium oxide particles was realized by homogeneous precipitation process followed by calcination in air at 400°C. The effects of room temperature pre-aging time on the morphologies of final products were investigated. Monodispersed rod-like cerium carbonate precursor was produced at 70°C for 2 h using the solution without pre-aging treatment. In contrast, monodispersed spherical precursor and plate-like precursor were obtained under the same conditions after pre-aging the solution at 25°C for 72 and 144 h, respectively. Ceria particles with similar morphologies and particle size to those of carbonate precursor could be obtained after calcination in air at 400°C. The monodispersed spherical, rod-like, and plate-like cerium oxide particles were successfully synthesized.
SYNTHESIS OF ANISOTROPIC LEAD TITANATE POWDERS FOR TEMPLATED GRAIN GROWTH OF TEXTURED PIEZOELECTRIC CERAMICS
Authors: MA S. , FUH J. Y. H. , ZHANG Y. F. , LU L.
Published: July 2010

Needle-shaped PbTiO3 (PT) template particles were successfully synthesized using two different types of approaches, molten salt synthesis (MSS) and thermal synthesis method. In eutectic NaCl–KCl molten salt system, homogeneous and nonagglomerated needle-shaped PT particles were produced from PbO and needle-like TiO2 compound heated at 800–850°C for 2 h. The effect of heating temperature on the morphology of formed powders was studied in order to identify the optimum processing parameters. The template formation mechanism is discussed. Using thermal synthesis method, comparable needle-shaped PT crystalline particles were also obtained in one step. Plate-shaped PT powders were derived via flux synthesis. The effect of additives such as MnCl2 and LiF on the morphology of derived PT was studied. Adding a certain amount of MnCl2 led to the formation of well-defined plate-shaped PT particles. The structure and morphology of synthesized powders were characterized by means of X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM).
PREPARATION AND CHARACTERIZATION OF CHITOSAN–GOLD NANOCOMPOSITES FOR DRUG DELIVERY APPLICATION
Authors: LEE SEUNG-CHUL , LEE SANG-WHA , KANG IK-JOONG
Published: July 2010

Chitosan–gold nanocomposites were fabricated via a seed-mediated goldshell growth over chitosan–gold nanocomplex and examined as a potential biomedical agent for drug delivery. Chitosan–gold nanocomplex was formed by the electrostatic interaction between of cationic chitosan nanoparticles (ca. 50 nm) and anionic gold colloids (ca. 1–3 nm) and the subsequent reduction of gold salts was conducted to form the gold clusters over the chitosan nanoparticles in the presence of reducing ascorbic acid. The resultant nanocomposites (or nanoshells) exhibited the absorption peak around 580 nm that was clearly red-shifted by ca. 60 nm as compared to gold nanoparticles. Surface morphology and plasmonic properties of chitosan–gold nanocomposites were characterized by transmission electron microscopy, field emission scanning electron microscopy (including EDX), ultraviolet–visible spectroscopy, and zeta-potential meter.
THE OPTIMIZING CONDITIONS BY TAGUCHI METHOD FOR FABRICATING SEMI-SOLID Al–Zn–Mg ALLOY SLURRY BY COOLING PLATE METHOD
Authors: SHIM SUNG-YONG , PARK HYUNG-WON , JEONG IN-SANG , LIM SU-GUN
Published: July 2010

In order to optimize the condition for the semi-solid Al–Zn–Mg aluminium alloy fabricated by cooling plate method, the Taguchi design was used. The cooling plate method effectively separating the grains formed from the mold wall can be used to form a semi-solid material by flowing molten metal over an inclined Cu plate and casting in a mold for the near-net shape component. In Taguchi's design method, the higher signal vs noise (S/N) ratio the better. Therefore, the manufacturing conditions were arranged as a table of orthogonal arrays (L9(34)), and the influence of two factors, pouring temperature and cooling plate angle, was examined. From the observed microstructures, the grain size and aspect ratio were measured by image analyzer. The results indicated that the pouring temperature exerts the main effect on the spherical microstructures since the S/N ratio, which is the sensibility of the surrounding environment, was the highest. The optimum condition for the Al–Zn–Mg alloy was a cooling plate angle of 40° and a pouring temperature of 680°C. The grain size and aspect ratio were 70 μm and 1.3, respectively.
A STUDY ON THE SYNTHESIS OF ULTRA-FINE IN SITUNi3Al–Al2O3/TiC COMPOSITE POWDER
Authors: KIM DONG-WOONG , CHOI SUNG-HYUN , DO KYOUNG-ROK , LIM SU-GUN , AHN IN-SHUP
Published: July 2010

Titanium carbide ( TiC ) has a low density, relatively high thermal and electrical conductivity. TiC is also very stable, with a melting temperature of 3100°C and does not undergo phase transformations. These properties have attraction to apply cutting tool extensively. Recently, in order to improve the properties of cermet tool materials, most researches have been carried out on the development of new binder. Ni3Al intermetallic is an interesting material because it has a great advantage of application for some structural materials, especially at the high temperatures. Ni3Al has low density, high strength and good corrosion resistance properties, which recommend them for the application of high temperature structural material. In this study, we had investigated the effects of mechanical alloying time and annealing temperature on the Ni3Al–Al2O3/TiC phase formation. Raw powders to fabricate Ni3Al–Al2O3/TiC composite powders were Ni , Al , TiH2 and activated carbon. These powders were ball-milled in planetary milling jar in argon atmosphere. Ball-milled powders were annealed up to 1200°C in Ar + 4%H2 atmosphere. The mean particle size of 300 nm was obtained after 10 h ball-milling. Ni3Al–Al2O3/TiC composite powders were formed by annealing for 1 h over 1100°C.
IMPROVING THE SURFACE PROPERTIES OF INCONEL 718 BY APPLYING A CO2 LASER HEAT TREATMENT TO A HIGH-VELOCITY OXY-FUEL COATING OF WC-CrCo POWDER
Authors: CHO T. Y. , YOON J. H. , JOO Y. K. , ZHANG S. H. , CHO J. Y. , KANG J. H. , CHUN H. G. , KWON S. C. , LI MING-XI
Published: July 2010

A micron-sized WC-CrCo powder was coated onto an IN718 substrate using high-velocity oxy-fuel (HVOF) thermal spraying. To further improve the surface properties, the HVOF coating was heat-treated by a CO2 laser. The surface properties of both the coating and the laser-heated coating were then compared. The HVOF optimal coating process (OCP) for a coating with the highest surface hardness was determined with the Taguchi program. The friction and wear behaviors of the coating, an electrolytic hard chrome (EHC)-plated coating and IN718, were comparatively investigated via a reciprocating sliding wear test at both 25 and 450°C. The friction coefficient (FC) for all three samples decreased when the sliding surface temperature increased from 25 to 450°C. The FC of the coating decreased with increasing surface temperature: 0.33 ± 0.02 at 25°C to 0.26 ± 0.02 at 450°C; the coating had the lowest FC among the three samples. At both temperatures, the coating wear depth (WD) was smaller than those of the EHC sample and IN718. At room temperature, WC-CrCo and the EHC coatings had good wear resistance and had only a shallow WD. IN718, however, had poor wear resistance with 50 μm deep grooves created from fretting corrosion that arose during the 1500 reciprocating slides (2.5 Hz, 10 min sliding wear test). At 450°C, the coating WDs were much shallower than those for the EHC coating and IN718: 0.5-μm deep grooves compared to 60–70-μm deep grooves. These results proved that the coating provided a protective coating for IN718 and other metal components. With the OCP coating fabricated from the powders on the IN718 surface, the surface hardness increased 316% from 399 Hv to 1260 Hv. Furthermore, by laser heating the coating surface for 0.6 s, the hardness increased 44% from 1260 ±30 Hv to 1820 ±100 Hv, porosity decreased more than five times from 2.2 ± 0.3% to 0.4 ± 0.1%, and the coating thickness decreased 17% from 300 to 250 μm. These results showed that both the WC-CrCo powder coating and the laser-heating improved the surface properties of IN718.
THE MANUFACTURING OF NIOBIUM POWDER BY HUNTER PROCESS
Authors: YOON JAE-SIK
Published: July 2010

Niobium powder was fabricated by metallothermic reduction process using K2NbF7 as the raw material, KCl and KF as the diluents and Na as the reducing agent. The apparatus for the experiment was designed and built specifically for the present study. Varying properties of niobium powder depending on reaction temperature and excess of reducing agent were analyzed. The niobium particle size increased significantly as the reduction temperature increased from 993 to 1093 K. The particle size was fairly uniform at a given reaction temperature, varying from 0.2 μ m to 50 nm depending on the reaction temperature. The yield of niobium powder increased from 58 to 83% with an increase in reaction temperature. The average particle size of niobium powder was improved from 70 nm to 0.2 μ m with the increase in the amount of Na excess. In addition, the yield rate of Nb powder was 82% in the 5% excess sodium.
EFFECT OF REINFORCEMENT ON SLIDING WEAR BEHAVIORS OF HYPEREUTECTIC Al–Si COMPOSITES PREPARED BY POWDER METALLURGY
Authors: PARK SEUL-KI , CHOI JIN-MYUNG , KIM YONG-JIN , PARK IK-MIN , PARK YONG-HO
Published: July 2010

In this study, the effect of the reinforcement on the wear behavior of hypereutectic Al–Si composites was investigated by performing a ball-on-disk test. The specimens were manufactured by hot press after gas atomizing. Al–20Si–5TiC composite exhibited superior wear resistance than other composites used in this study.
PREPARATION OF WOLLASTONITE COATED WITH NANO-ALUMINIUM SILICATE AND ITS APPLICATION IN FILLING PA6
Authors: WANG CAILI , ZHENG SHUILIN , LIU GUIHUA , WANG LIJING , HUANG PENG , WANG ZHAOHUA
Published: July 2010

Taking wollastonite as raw material, aluminium sulfate and water glass as coating modifier, a new type of wollastonite coated with nano-aluminium silicate powder-materials was obtained by chemical depositing method. By modificating this powder-materials with silane and filling it in PA6, the PA6 composite materials were obtained. The modificated powder-materials were characterized by SEM, BET, XRD, EDX, and FT-IR. The mechanism of this powder-materials modificated by silane was discussed. It was shown that the surface of wollastonite was coated with nano-aluminium silicate evenly, the average grain size of aluminium silicate was 54 nm, filling 30% of this powder-materials modified by silane in PA6, the mechanical properties and the heat distortion temperature of the PA6 composites filled by it were notably enhanced.
A NEW FORMULA FOR THE EVALUATION OF THE IONIZATION ENERGY BASED ON THE ORBITAL EXPONENTS OF THE ATOMS OF 118 ELEMENTS OF THE PERIODIC TABLE
Authors: ISLAM NAZMUL , JANA ARINDAM
Published: July 2010

We propose a simple approach for the calculation of the ionization potentials of atoms in terms of their orbital exponents. The prescription is simple and utilizes only the simple Bohr equation with some modifications. We have pointed out that the atomic first ionization energy not only depends on the principal quantum number (n) but also on the azimuthal quantum number (l) of the orbital (n, l) on which the electron of interest is present. The formalism is tested through the calculation of the atomic ionization potentials of 118 elements of the periodic table. The orbital exponent values for 118 elements of the periodic table are computed following the suggestions of Reed. The calculated numerical results for a number of atoms are shown to agree quite well with their experimental counterparts. To perform the validity tests of the present scale of ionization potential, various physico-chemical properties of the atoms are also correlated on the basis of the computed ionization potential data. It is found that the stability of the half filled configuration depends on the orbital (n, l) on which the electron is present. The expressed periodic behavior and correlation of the most important physico-chemical properties of elements suggest that the present method of evaluation of the ionization potential of the atoms is quite a successful venture.
DFT STUDY OF GASEOUS CONFORMERS OF ASPARTIC ACID
Authors: HE LIANG JUN , FAN JIAN FEN , TANG MIN
Published: July 2010

Systematic and extensive conformational search of neutral aspartic acid in gas has been performed in this work. All the possible 1296 structures were optimized at the B3LYP /6-311++ G ** level and a total of 122 stable conformers were determined. Single-point energy computations were done at the MP2/aug-cc-pvdz level. The relative stabilities and structural characteristics of the 15 most stable conformers were discussed, shedding light on the influences of the arrangements of α- and β-carboxyls, intramolecular hydrogen bond interactions and the intramolecular ring tension on the molecular stabilities.
Intestine-specific transcription factor Cdx2 induces E-cadherin function by enhancing the trafficking of E-cadherin to the cell membrane
Authors: Funakoshi Shinsuke , Kong Jianping , Crissey Mary Ann , Dang Long , Dang Duyen , Lynch John P.
Published: July 2010

Cdx2 is an intestine-specific transcription factor required for normal intestinal epithelium development. Cdx2 regulates the expression of intestine-specific genes and induces cell adhesion and columnar morphogenesis. Cdx2 also has tumor-suppressor properties, including the reduction of colon cancer cell proliferation and cell invasion, the latter due to its effects on cell adhesion. E-cadherin is a cell adhesion protein required for adherens junction formation and the establishment of intestinal cell polarity. The objective of this study was to elucidate the mechanism by which Cdx2 regulates E-cadherin function. Two colon cancer cell lines were identified in which Cdx2 expression was associated with increased cell-cell adhesion and diminished cell migration. In both cell lines, Cdx2 did not directly alter E-cadherin levels but increased its trafficking to the cell membrane compartment. Cdx2 enhanced this trafficking by altering receptor tyrosine kinase (RTK) activity. Cdx2 expression diminished phosphorylated Abl and phosphorylated Rac levels, which are downstream effectors of RTKs. Specific chemical inhibition or short interfering RNA (shRNA) knockdown of c-Abl kinase phenocopied Cdx2's cell-cell adhesion effects. In Colo 205 cells, Cdx2 reduced PDGF receptor and IGF-I receptor activation. This was mediated by caveolin-1, which was induced by Cdx2. Targeted shRNA knockdown of caveolin-1 restored PDGF receptor and reversed E-cadherin membrane trafficking, despite Cdx2 expression. We conclude that Cdx2 regulates E-cadherin function indirectly by disrupting RTK activity and enhancing E-cadherin trafficking to the cell membrane compartment. This novel mechanism advances Cdx2's prodifferentiation and antitumor properties and suggests that Cdx2 may broadly regulate RTK activity in normal intestinal epithelium by modulating membrane trafficking of proteins.
Dynamics of tidal volume and ventilation heterogeneity under pressure-controlled ventilation during bronchoconstriction: a simulation study
Authors: Wongviriyawong Chanikarn , Winkler Tilo , Harris R. Scott , Venegas Jose G.
Published: July 2010

The difference in effectiveness between volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) on mechanically ventilated patients during bronchoconstriction is not totally clear. PCV is thought to deliver a more uniform distribution of ventilation than VCV, but the delivered tidal volume could be unstable and affected by changes in the degree of constriction. To explore the magnitude of these effects, we ran numerical simulations with both modes of ventilation in a network model of the lung in which we incorporated not only the pressure and flow dynamics along the airways but also the effect of cycling pressures and tissue tethering forces during breathing on the dynamic equilibrium of the airway smooth muscle (ASM) (Venegas et al., Nature 434: 777–782). These simulations provided an illustration of changes in airway radii, the total delivered tidal volume stability, and distribution of ventilation following a transition from VCV to PCV and during progressively increasing ASM activation level. These simulations yielded three major results. First, the ventilation heterogeneity and patchiness in ventilation during steady-state VCV were substantially reduced after the transition to PCV. Second, airway radius, tidal volume, and the distribution of ventilation under severe bronchoconstriction were highly sensitive to the setting of inspiratory pressure selected for PCV and to the degree of activation of the ASM. Third, the dynamic equilibrium of active ASM exposed to cycling forces is the major contributor to these effects. These insights may provide a theoretical framework to guide the selection of ventilation mode, the adjustment of ventilator settings, and the interpretation of clinical observations in mechanically ventilated asthmatic patients.
Adenovirus Targeting to Prostate-Specific Membrane Antigen through Virus-Displayed, Semirandom Peptide Library Screening
Authors: Wu Ping , Kudrolli Tarana A. , Chowdhury Wasim H. , Liu Minzhi M. , Rodriguez Ronald , Lupold Shawn E.
Published: July 2010

The convergence of phage-displayed peptide libraries and recombinant viral vectors launched a promising new direction in targeted viral gene therapeutics, but the translation of targeting peptides to functional cancer therapeutic agents has been challenging. Here, we report progress in developing a successful strategy to optimize targeted viral infection through adenovirus-displayed, semirandom peptide libraries. A phage-derived peptide targeting the prostate-specific membrane antigen (PSMA) was genetically incorporated into the adenoviral capsid Fiber protein and flanked by random peptide cassettes. The resulting adenovirus library was biopanned against PSMA-expressing cells and tumors to identify a PSMA-retargeted adenovirus. While the initial peptide alone could not target viral infection, the selected virus preferentially infects PSMA-expressing cells through the targeting peptide and infects LNCaP tumors after intravenous injection. Our results indicate that virus-displayed, semirandom peptide libraries can be used to optimize targeting infection. This approach represents a novel principle for developing targeted agents in a variety of disease models. Cancer Res; 70(23); 9549–53. ©2010 AACR.
Molecular Analysis of Non–Small Cell Lung Cancer Identifies Subsets with Different Sensitivity to Insulin-like Growth Factor I Receptor Inhibition
Authors: Gualberto Antonio , Dolled-Filhart Marisa , Gustavson Mark , Christiansen Jason , Wang Yu-Fen , Hixon Mary L. , Reynolds Jennifer , McDonald Sandra , Ang Agnes , Rimm David L. , Langer Corey J. , Blakely Johnetta , Garland Linda , Paz-Ares Luis G. , Karp Daniel D. , Lee Adrian V.
Published: July 2010

Purpose: This study aimed to identify molecular determinants of sensitivity of non–small cell lung cancer (NSCLC) to anti–insulin-like growth factor receptor (IGF-IR) therapy.

Experimental Design: A total of 216 tumor samples were investigated, of which 165 consisted of retrospective analyses of banked tissue and an additional 51 were from patients enrolled in a phase II study of figitumumab, a monoclonal antibody against IGF-IR, in stage IIIb/IV NSCLC. Biomarkers assessed included IGF-IR, epidermal growth factor receptor, IGF-II, IGF-IIR, insulin receptor substrate 1 (IRS-1), IRS-2, vimentin, and E-cadherin. Subcellular localization of IRS-1 and phosphorylation levels of mitogen-activated protein kinase and Akt1 were also analyzed.

Results: IGF-IR was differentially expressed across histologic subtypes (P = 0.04), with highest levels observed in squamous cell tumors. Elevated IGF-IR expression was also observed in a small number of squamous cell tumors responding to chemotherapy combined with figitumumab (P = 0.008). Because no other biomarker/response interaction was observed using classical histologic subtyping, a molecular approach was undertaken to segment NSCLC into mechanism-based subpopulations. Principal component analysis and unsupervised Bayesian clustering identified three NSCLC subsets that resembled the steps of the epithelial to mesenchymal transition: E-cadherin high/IRS-1 low (epithelial-like), E-cadherin intermediate/IRS-1 high (transitional), and E-cadherin low/IRS-1 low (mesenchymal-like). Several markers of the IGF-IR pathway were overexpressed in the transitional subset. Furthermore, a higher response rate to the combination of chemotherapy and figitumumab was observed in transitional tumors (71%) compared with those in the mesenchymal-like subset (32%; P = 0.03). Only one epithelial-like tumor was identified in the phase II study, suggesting that advanced NSCLC has undergone significant dedifferentiation at diagnosis.

Conclusion: NSCLC comprises molecular subsets with differential sensitivity to IGF-IR inhibition. Clin Cancer Res; 16(18); 4654–65. ©2010 AACR.
Monoclonal Antibodies to Fibroblast Growth Factor Receptor 2 Effectively Inhibit Growth of Gastric Tumor Xenografts
Authors: Zhao Wei-meng , Wang Lihong , Park Hangil , Chhim Sophea , Tanphanich Melanie , Yashiro Masakazu , Kim K. Jin
Published: July 2010

Purpose: Overexpression of fibroblast growth factor receptor 2 (FGFR2) may be a causative factor of a number of human tumors, especially gastric tumors of the poorly differentiated type. We investigated whether monoclonal antibodies (mAbs) directed against FGFR2 can inhibit the growth of tumors in xenograft models.

Experimental Design: We generated and characterized 3 mAbs that recognize different epitopes on FGFR2: GAL-FR21, GAL-FR22, and GAL-FR23. The ability of the mAbs to recognize the FGFR2IIIb and FGFR2IIIc isoforms of FGFR2 was determined, as was their ability to block binding of FGF ligands to FGFR2. The capability of the mAbs to inhibit FGF-induced FGFR2 phosphorylation and to downmodulate FGFR2 expression was also investigated. Finally, the ability of the anti-FGFR2 mAbs to inhibit tumor growth was determined by establishing xenografts of SNU-16 and OCUM-2M human gastric tumor cell lines in nude mice, treating with each mAb (0.5–5 mg/kg intraperitoneally twice weekly) and monitoring tumor size.

Results: Of the 3 mAbs, GAL-FR21 binds only the FGFR2IIIb isoform, whereas GAL-FR22 and GAL-FR23 bind to both the FGFR2IIIb and FGFR2IIIc forms, with binding regions respectively in the D3, D2-D3, and D1 domains of FGFR2. GAL-FR21 and GAL-FR22 blocked the binding of FGF2, FGF7 and FGF10 to FGFR2IIIb. GAL-FR21 inhibited FGF2 and FGF7 induced phosphorylation of FGFR2, and both mAbs downmodulated FGFR2 expression on SNU-16 cells. These mAbs effectively inhibited growth of established SNU-16 and OCUM-2M xenografts in mice.

Conclusions: Anti-FGFR2 mAbs GAL-FR21 and GAL-FR22 have potential for the treatment of gastric and other tumors. Clin Cancer Res; 16(23); 5750–58. ©2010 AACR.
The Serine Protease HtrA1 Specifically Interacts and Degrades the Tuberous Sclerosis Complex 2 Protein
Authors: Campioni Mara , Severino Anna , Manente Lucrezia , Tuduce Ioana L. , Toldo Stefano , Caraglia Michele , Crispi Stefania , Ehrmann Michael , He Xiaoping , Maguire Jacie , De Falco Maria , De Luca Antonio , Shridhar Viji , Baldi Alfonso
Published: July 2010

Hamartin and tuberin are products of the tumor suppressor genes TSC1 and TSC2, respectively. Mutations affecting either gene result in the tuberous sclerosis syndrome, a neurologic genetic disorder characterized by the formation of multiple benign tumors or hamartomas. In this study, we report the identification of TSC2, but not TSC1, as a substrate of HtrA1, a member of the human HtrA family proteins of serine proteases. We show the direct interaction and colocalization in the cytoplasm of HtrA1 and TSC2 and that HtrA1 cleaves TSC2 both in vitro and in vivo. Finally, we show that alterations in HtrA1 expression cause modifications in phosphorylation status of two downstream targets of TSC2: 4E-BP1 and S6K. Our data suggest that, under particular physiologic or pathologic conditions, HtrA1 degrades TSC2 and activates the downstream targets. Considering that HtrA1 levels are significantly increased during embryogenesis, we speculate that one of the targets of HtrA1 activity during fetal development is the TSC2-TSC1 pathway. Mol Cancer Res; 8(9); 1248–60. ©2010 AACR.