bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards Accurate Spectroscopic Identification of Species at Catalytic Surfaces: Anharmonic Vibrations of Formate on AuPt
Authors: Chan Matthew , Yamashita Koichi , Carrington Tucker , Manzhos Sergei 
Published: January 2013

ABSTRACTWe present a calculation of vibrational frequencies of formate on the AuPt(111) surface alloy including full anharmonicity and coupling of all six intramolecular degrees of freedom. This species is a key intermediate in methanol oxidation on this material. We use a modified version of the method of Manzhos and Carrington to compute the spectrum directly from a small number (<10,000) of DFT single-point energies, bypassing the construction of a potential energy surface. This is the first such calculation for a 4-atomic species at a surface. The spectrum is obtained using rectangular collocation and a small basis set of parameterized Hermite functions. The achievable accuracy of the order of several cm-1 corresponds to the typical experimental resolution. Using normal coordinates makes the equations simple and general and easily applicable to other systems. This calculation is doable on a PC. We predict that anharmonicity and coupling lower the fundamental frequencies by dozens of cm-1, which could affect species assignment.
Thermoelectric properties of Bi-FeSb2 nanocomposites: Evidence for phonon-drag effect
Authors: Pokharel Mani , Koirala Machhindra , Zhao Huaizhou , Lukas Kevin , Ren Zhifeng , Opeil Cyril 
Published: January 2013

AbstractThe thermoelectric properties of Bi-FeSb2 nanocomposites are reported. The electrical resistivity and the Seebeck coefficient measurements show a significant dependence on bismuth concentration. Our results reveal that the shifting of the Seebeck peak in FeSb2 nanocomposites is purely a grain size-effect. The thermal conductivity data indicates a presence of an electron-phonon interaction. Over all, our analysis of the the thermoelectric properties of Bi-FeSb2 nanocomposites provide additional evidence for phonon-drag in FeSb2.
Tantalum Nitride for Copper Diffusion Blocking on Thin Film (BiSb)2Te3
Authors: Hsu H. H. , Cheng C. H. , Lin C. K. , Chen K. Y. , Lin Y. L. 
Published: January 2013

ABSTRACTThis study demonstrates the feasibility of introducing a TaN thin film as a copper diffusion barrier for p-type (BiSb)2Te3 thermoelectric material. Compared to conventional Ni diffusion barrier, remarkably little void generation in Cu bulk or near Cu/TaN interface originated from Cu penetration is observed for TaN barrier after suffering the thermal budget of close to soldering. Diffusion behaviors of the barriers were analyzed by transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS) to make a deep understanding in clarifying interface diffusion effects among the Cu electrode, the barrier layer, and the (BiSb)2Te3thermoelectric layer.
Effects of La0.5Sr0.5CoO3 sol concentration on the microstructure and dielectric properties of Ba0.6Sr0.4TiO3 films prepared by sol-gel method on Ti substrate
Authors: Jiang Dan , Han Songwei , Zhao Xuelian , Cheng Jinrong 
Published: January 2013

ABSTRACTBa0.6Sr0.4TiO3 (BST) thin films were deposited on La0.5Sr0.5CoO3 (LSCO) buffered Ti substrates. Both BST and LSCO were prepared by sol-gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of LSCO sol concentration on the crystallinity and surface morphology of the films. The results show that with the increase of LSCO sol concentration, BST films show variation of the structure and dielectric properties. BST films for LSCO of 0.2 mol/L exhibit a better crystallinity and improved dielectric properties, with the tunability, dielectric constant and tanδ of 30%, 420 and 0.028 respectively.
Influence of microstructure and processing on mechanical properties of advanced Nb-silicide alloys
Authors: Seemüller C. , Heilmaier M. , Hartwig T. , Mulser M. , Adkins N. , Wickins M. 
Published: January 2013

ABSTRACTIn this study different powder metallurgical processing routes, commonly used for refractory metal based materials, were evaluated on their impact on mechanical properties of a multi-component Nb-20Si-23Ti-6Al-3Cr-4Hf (at.%) alloy. Powder was produced by gas-atomization or high energy mechanical alloying of elemental powders and then consolidated either by HIPing or powder injection molding (PIM). The PIM process requires fine particles. In this investigation powder batches of gas-atomized powder (< 25 μm) and mechanically alloyed powder (< 25 μm) were compacted via PIM. Fine (< 25 μm) and coarser (106-225 μm) particle fractions of gas-atomized powder were compacted via HIPing for comparison. Quantitative analysis of the resulting microstructures regarding porosity, phase formation, phase distribution, and grain size was carried out in order to correlate them with the ensuing mechanical properties such as compressive strength at various temperatures.
Semiconductive Properties of Alternating Mg/C Multi-layer Films with Hydroxylation Treatment
Authors: Chiba Masafumi , Endo Daisuke , Haruta Kenichi , Kimura Hideki , Kiyota Hideo 
Published: January 2013

ABSTRACTA Mg(OH)2–C transparent conductive film was prepared using the sputtering method by the initial formation of a Mg-C film generated by the alternate layering of Mg and C on a rotating substrate and subsequent exposure of the film to atmospheric water vapor. To examine the influence exerted by the Mg/C layers of the starting film sample on semiconductivity,evaluations of the electrical conductivity properties of the film during the hydroxylation process and the optical properties after the hydroxylation process were carried out. As a result, although no effects on the characteristics of the electrical conductivity properties associated with the composition or number of layers in the films could be confirmed, it was determined that the films possessed the characteristics of semiconductors. On the other hand, the optical properties were found to be affected by the composition and number of layers of the Mg/C films.
Chemotaxis of Mesenchymal Stem Cells in a Microfluidic Device
Authors: Choa Ruth , Mehta Manav , Lee Kangwon , Mooney David 
Published: January 2013

ABSTRACTAdult bone marrow derived mesenchymal stem cells (MSCs) represent an important source of cells for tissue regeneration. Control of MSC migration and homing is still unclear. The goal of this study was to identify potent chemoattractants for MSCs and characterize MSC chemotaxis using a microfluidic device as a model system and assay platform. The three chemokines compared in this study were CXCL7, CXCL12, and AMD 3100.Microfluidic devices made of polydimethysiloxane (PDMS) were fabricated by soft lithography techniques and designed to generate a stable linear chemokine gradient. Cell movements in response to the gradient were captured by timelapse photos and tracked over 24 hours. Chemokine potency was measured via several chemotaxis parameters including: velocity in the direction of interest (V), center of mass (Mend), forward migration indice (YFMI). The migratory paths of the cells were mapped onto a displacement plot and compared.The following results were measured in the direction of interest (towards higher concentrations of chemokine): For velocity, only cells exposed to CXCL12 had a statistically significant (p=.014) average velocity (V=0.19 ± 0.07 um/min) when compared to the control condition (V=0.06 ±0 .04 um/min). For the center of mass, where the displacement of cells from their starting positions were compared, again only CXCL12 (Mend= 53.9 ± 10.8 um) stimulated statistically significant (p = .013) displacement of cells compared to the control condition (Mend = 19.3 ± 16.1 um). For the forward migration index, the efficiency of cell movement was measured. Indices in both the CXCL12 (YFIM = 0.19 ± 0.08) and CXCL7 (YFIM = 0.09 ±0.03) conditions were statistically significant (p = .023 for CXCL12 and p = .035 for CXCL7) when compared with the control index (YFIM = .04 ± .02).This study demonstrated the use of microfluidic devices as a viable platform for chemotaxis studies. A stable linear chemokine gradient was maintained over a long time scale to obtain cell migration results. CXCL12 was quantitatively determined to be the most potent chemoattractant in this research; these chemoattractive properties promote its use in future developments to control MSC homing.
Wafer-Scale, Highly-Ordered Silicon Nanowires Produced by Step-and-Flash Imprint Lithography and Metal-Assisted Chemical Etching
Authors: Ho Jian-Wei , Wee Qixun , Dumond Jarrett , Zhang Li , Zang Keyan , Choi Wee Kiong , Tay Andrew A. O. , Chua Soo-Jin 
Published: January 2013

ABSTRACTA combinatory approach of Step-and-Flash Imprint Lithography (SFIL) and Metal-Assisted Chemical Etching (MacEtch) was used to generate near perfectly-ordered, high aspect ratio silicon nanowires (SiNWs) on 4" silicon wafers. The ordering and shapes of SiNWs depends only on the SFIL nanoimprinting mould used, thereby enabling arbitary SiNW patterns not possible with nanosphere and interference lithography (IL) to be generated. Very densely packed SiNWs with periodicity finer than that permitted by conventional photolithography can be produced. The height of SiNWs is, in turn, controlled by the etching duration. However, it was found that very high aspect ratio SiNWs tend to be bent during processing. Hexagonal arrays of SiNW with circular and hexagonal cross-sections of dimensions 200nm and less were produced using pillar and pore patterned SFIL moulds. In summary, this approach allows highlyordered SiNWs to be fabricated on a wafer-level basis suitable for semiconductor device manufacturing.
First Investigations on a TNM TiAl Alloy Processed by Spark Plasma Sintering
Authors: Voisin Thomas , Monchoux Jean-Philippe , Clemens Helmut , Couret Alain 
Published: January 2013

ABSTRACTThe processing of a TNM powder (Ti-43.9Al-4Nb-0.95Mo-0.1B, in at.%) by Spark Plasma Sintering (SPS) was investigated for the first time. SPS experiments were performed at varying temperatures. The microstructures of the products were analyzed and interpreted in reference to the available phase diagram. Results of tensile tests conducted at room temperature are also presented.
Optimal Medium Formulation for the Long‐Term Expansion and Maintenance of Human Periodontal Ligament Stem Cells
Authors: Jung Im‐Hee , Kwon Bo‐Sun , Kim Se‐Hee , Shim Hye‐Eun , Jun Choong‐Man , Yun Jeong‐Ho 
Published: January 2013

Background: Human periodontal ligament stem cells (hPDLSCs) are promising mesenchymal stem cells that are readily accessible. However, there is as yet no consensus as to the optimal culture medium for hPDLSCs. Thus, the purpose of the present study is to determine the optimal culture medium for long‐term expansion of hPDLSCs.Methods: hPDLSCs were isolated from healthy third molars, and the most widely used medium formulations in previous studies were used: 1) an α minimum essential medium–based medium formulation (MBM); and 2) a Dulbecco's minimum essential medium‐based medium formulation. Passage 5 (P5) and P8 were evaluated with the two media for cell proliferation, differentiation, and immunophenotype.Results: hPDLSCs that were primarily cultured in MBM were far more proliferated than those grown in DBM. In general, application of the MBM for longer periods produced greater cell growth and osteogenic differentiation. Furthermore, MBM‐precultured hPDLSCs exhibited a greater degree of cell proliferation and a greater production of mineralized tissue and alkaline phosphatase (ALP) activity in vitro, although the levels of both were dependent on the culture medium used. With respect to long‐term expansion, the P5 hPDLSCs grew and produced the largest amount of mineralized nodules faster than the P8 hPDLSCs, but both passages exhibited a similar phenotype for stemness and ALP activity.Conclusion: The present study indicates that the inherent capacity of hPDLSCs could be maintained until a later passage, P8 in MBM, and MBM appears to be an optimal choice for manipulating the finest and most stable hPDLSCs.
Discriminant Analysis for the Thin Periodontal Biotype Based on the Data Acquired From Three‐Dimensional Virtual Models of Korean Young Adults
Authors: Lee Seung‐Pyo , Kim Tae‐Il , Kim Hong‐Kyun , Shon Won‐Jun , Park Young‐Seok 
Published: January 2013

Background: There have been no objective criteria for classifying the periodontal biotype. The purpose of this study is to suggest clinical guidelines for discriminating the thin biotype, which might be susceptible to gingival recession, using statistical analyses based on the measurement of the dento‐gingival complex on three‐dimensional virtual models.Methods: From canine to canine, the area of the facial papilla, the facial surface area of the anterior tooth, the proportion of the dento‐papillary complex, clinical papillary length, and the clinical papillary angle were measured on a three‐dimensional virtual model of 133 young participants. In the clinical exam, the gingival transparency when probing was evaluated, and the classification into thin and non‐thin biotype groups was used as the gold standard. The data were analyzed by discriminant analysis.Results: Twenty‐nine participants (17 males and 12 females) belonged to the “thin group” according to the clinical evaluation. All variables were significantly different between groups (P <0.001). The results of discriminant function analysis showed that the sum of the area between each canine and lateral incisor, each lateral and central incisor, and the two central incisors was the best single determinant of biotype, and the sum of the papillary lengths between each canine and lateral incisor, each lateral and central incisor, and the two central incisors (PLSum5) was the next best choice. The cutoff value of PLSum5 was calculated to be 23.73 mm.Conclusions: PLSum5 >24 mm is the suggested criterion for identifying high‐risk thin biotype patients based on the comparison with the results from gingival transparency inspection. A clinical reevaluation of this criterion should be examined in additional studies for application in real clinical situations.
Comparing Mortality of Peritoneal and Hemodialysis Patients in the First 2 Years of Dialysis Therapy
Authors: Lukowsky Lilia R. , Mehrotra Rajnish , Kheifets Leeka , Arah Onyebuchi A. , Nissenson Allen R. , Kalantar-Zadeh Kamyar 
Published: January 2013

Summary

Background and objectives
There are conflicting research results about the survival differences between hemodialysis and peritoneal dialysis, especially during the first 2 years of dialysis treatment. Given the challenges of conducting randomized trials, differential rates of modality switch and transplantation, and time-varying confounding in cohort data during the first years of dialysis treatment, use of novel analytical techniques in observational cohorts can help examine the peritoneal dialysis versus hemodialysis survival discrepancy.

Design, setting, participants, & measurements
This study examined a cohort of incident dialysis patients who initiated dialysis in DaVita dialysis facilities between July of 2001 and June of 2004 and were followed for 24 months. This study used the causal modeling technique of marginal structural models to examine the survival differences between peritoneal dialysis and hemodialysis over the first 24 months, accounting for modality change, differential transplantation rates, and detailed time-varying laboratory measurements.

Results
On dialysis treatment day 90, there were 23,718 incident dialysis—22,360 hemodialysis and 1,358 peritoneal dialysis—patients. Incident peritoneal dialysis patients were younger, had fewer comorbidities, and were nine and three times more likely to switch dialysis modality and receive kidney transplantation over the 2-year period, respectively, compared with hemodialysis patients. In marginal structural models analyses, peritoneal dialysis was associated with persistently greater survival independent of the known confounders, including dialysis modality switch and transplant censorship (i.e., death hazard ratio of 0.52 [95% confidence limit 0.34–0.80]).

Conclusions
Peritoneal dialysis seems to be associated with 48% lower mortality than hemodialysis over the first 2 years of dialysis therapy independent of modality switches or differential transplantation rates.
Screening of Male Dialysis Patients for Fabry Disease by Plasma Globotriaosylsphingosine
Authors: Maruyama Hiroki , Takata Takuma , Tsubata Yutaka , Tazawa Ryushi , Goto Kiyoe , Tohyama Jun , Narita Ichiei , Yoshioka Hidekatsu , Ishii Satoshi 
Published: January 2013

Summary

Background and objectives
Previous reports of Fabry disease screening in dialysis patients indicate that α-galactosidase A activity alone cannot specifically and reliably identify appropriate candidates for genetic testing; a marker for secondary screening is required. Elevated plasma globotriaosylsphingosine is reported to be a hallmark of classic Fabry disease. The purpose of this study was to examine the usefulness of globotriaosylsphingosine as a secondary screening target for Fabry disease.

Design, setting, participants, & measurements
This study screened 1453 patients, comprising 50% of the male dialysis patients in Niigata Prefecture between July 1, 2010 and July 31, 2011. Screening for Fabry disease was performed by measuring the plasma α-galactosidase A enzyme activity and the globotriaosylsphingosine concentration, by high-performance liquid chromatography. Genetic testing and genetic counseling were provided.

Results
A low level of plasma α-galactosidase A activity (≤4.0 nmol/h per milliliter) was observed in 47 patients (3.2%). Of these, 3 (0.2%) had detectable globotriaosylsphingosine levels. These patients all had α-galactosidase A gene mutations: one was p.Y173X and two were the nonpathogenic p.E66Q. The patient with p.Y173X started enzyme replacement therapy. Subsequent screening of his family identified the same mutation in his elder sister and her children. Genetic testing for 33 of the other 44 patients detected 7 patients with p.E66Q. Thus, the plasma lyso-Gb3 screen identified Fabry disease with high sensitivity (100%) and specificity (94.3%).

Conclusions
Plasma globotriaosylsphingosine is a promising secondary screening target that was effective for selecting candidates for genetic counseling and testing and for uncovering unrecognized Fabry disease cases.
In vivo effects of two acidic soft drinks on shear bond strength of metal orthodontic brackets with and without resin infiltration treatment
Authors: Hammad Shaza M. , Enan Enas T. 
Published: January 2013

ABSTRACT

Objectives:
To evaluate the in vivo effects of two acidic soft drinks (Coca-Cola and Sprite) on the shear bond strength of metal orthodontic brackets with and without resin infiltration treatment. In addition, the enamel surface was evaluated, after debonding, using a scanning electron microscope.

Materials and Methods:
Sixty noncarious maxillary premolars, scheduled for extraction in 30 orthodontic patients, were used. Patients were randomly divided into two groups according to the soft drink tested (Coca-Cola or Sprite). In each group, application of resin infiltration (Icon. DMG, Hamburg, Germany) was done on one side only before bonding of brackets. Patients were told to rinse their mouth with their respective soft drink at room temperature for 5minutes, three times a day for 3months. Shear bond strength was tested with a universal testing machine. After shearing test, a scanning electron microscope was used to evaluate enamel erosion. Statistical analysis was performed by twoway analysis of variance followed by the least significant difference test.

Results:
The Coca-Cola group without resin infiltration showed the lowest resistance to shearing forces. Scanning electron micrographs of both groups after resin application showed a significant improvement compared with results without resin use, as the enamel appeared smoother and less erosive.

Conclusion:
Pretreatment with the infiltrating resin has proved to result in a significant improvement in shear bond strength, regardless of the type of soft drink consumed.
Effect of premolar extraction on mandibular third molar impaction in young adults
Authors: Türköz Çağrı , Ulusoy Çağrı 
Published: January 2013

ABSTRACT

Objective:
To test the null hypothesis that orthodontic therapy with or without premolar extraction does not result in any difference in third molar impaction.

Materials and Methods:
Two groups were formed: 22 patients in one group with first premolar extractions and 22 patients in the other group without extractions. All patients were nongrowing subjects who had normal gonial angles and were skeletal Class I at the beginning of treatment. The available space for third molars, inclination of second and third molars, and angle between the second and third molars were evaluated. Also, the correlation of measured parameters and type of orthodontic therapy with the eruption of third molars was evaluated.

Results:
Of the third molars, 81.8% were impacted in the nonextraction group and 63.6% were impacted in the extraction group. Impaction of mandibular third molars was significantly correlated to the pretreatment and posttreatment inclination of third molars and the angle between the second and third molars. In the extraction therapy group, the retromolar distance increased significantly with a mean of 1.30 ± 1.25 mm.

Conclusions:
When the inclination of the third molar is inconvenient, the tooth may remain impacted even if there is enough retromolar space.
An approximation to the cross sections of Z
l boson production at CLIC by using neural networks
Authors: Akkoyun Serkan , Kara Seyit 
Published: January 2013

Abstract
In this work, the possible dynamics associated with leptophilic Z
l boson at CLIC (Compact Linear Collider) have been investigated by using artificial neural networks (ANNs). These hypotetic massive boson Z
l have been shown through the process e
+
e
−→µ+µ−. Furthermore, the invariant mass distributions for final muons have been consistently predicted by using ANN. For these highly non-linear data, we have constructed consistent empirical physical formulas (EPFs) by appropriate feed-forward ANN. These ANNEPFs can be used to derive further physical functions which could be relevant to studying Z
l.