bluuebunny/crossref_metadata_2025 huggingface dataset:
Elektrische TopDrive AC‐Motoren und Umrichter für die Öl‐ und Gasindustrie
Authors: von Ehrenstein Christian
Published: April 2013

Bohranlagen für die Öl‐ und Gasindustrie werden im stark zunehmenden Maß mit so genannten elektrischen TopDrives und zugehöriger Umrichtertechnik ausgestattet. TopDrives sind für die Drehbewegung des Bohrgestänges verantwortlich und somit eine der Hauptkomponenten einer Bohranlage. Elektrische TopDrives zeichnen sich durch eine deutlich gesteigerte Servicefreundlichkeit, durch geringe Stillstands‐Zeiten und durch eine hohe Effizienz aufgrund von Umrichtertechnik in Kombination mit intelligenter Software aus.

AC TopDrive motors for oil‐ and gas industry. Drilling rigs for the oil and gas industry are increasingly being fitted with electric topdrives. Topdrives are responsible for turning the drill string and are thus a key component of a drilling rig. Electric topdrives are characterised by clearly improved service friendliness, shorter stoppage times and high efficiency due to the use of variable frequency drive technology in combination with intelligent software.
NÖT – von der Bauweise zum System
Authors: Schubert Wulf , Lauffer Harald
Published: April 2013

Der Begriff NÖT wurde von Rabcewicz geschaffen, der ihn erstmalig beim Geomechanik Kolloquium 1962 verwendete. In seinem damaligen Beitrag fasst er die während der letzten Dekaden entwickelten Tunnelbaumethoden und die Vorstellungen über die Mechanik der Vorgänge im Gebirge zusammen. Aufbauend auf vorliegenden Erfahrungen und Erkenntnissen haben überwiegend österreichische Ingenieure diese Methode entwickelt und umgesetzt. Standen anfänglich Probleme einer praktischen Umsetzung im Vordergrund, so war doch klar, dass die traditionellen Planungsgrundsätze der Vergangenheit angehörten. Deswegen musste man sich noch überwiegend auf Erfahrungen und Beobachtungen stützen. Von Anfang an wurde die Bedeutung von Messungen zur ingenieurmäßigen Erfassung des Gebirgsverhaltens erkannt und deren Weiterentwicklung laufend vorangetrieben. Parallel zur erfolgreichen Anwendung der Methode in allen Gebirgsarten wurden auch Vertragsmodelle entwickelt, die eine faire Vergütung bei wechselhaftem und unvorhersehbarem Gebirgsverhalten ermöglichen.

Zur Gewährleistung einer strukturieren geotechnischen Planung wurde eine eigene Richtlinie erarbeitet. Für den Erfolg der Methode sind entscheidungswillige und sachkundige Auftraggeber, eine entsprechende Baustellenorganisation, qualifizierte Ingenieure und Mineure, eine praxisorientierte Forschung und Ausbildung und schlussendlich ein intensiver Erfahrungsaustausch notwendig.

NATM – from a construction method to a system

The term NATM was introduced by Rabcewicz during a lecture at the Geomechanics Colloquium in 1962. In this lecture, he summarizes the development of tunnelling methods and insight into mechanical processes in the ground over the last decades, and points out the positive experience made with a combination of shotcrete and rock bolts instead of the traditional timber or steel supports. Building on experience and development around the world, it has been Austrian engineers who have systematically developed and applied the method. In the beginning technological questions played a major role, but it was also clear that traditional design methods were no longer applicable. Thus it was still unavoidable to rely heavily on experience and observation. The importance of measurements for observing the system behaviour has been acknowledged, and techniques have been developed considerably further since then. Parallel to gaining more experience with the method in all kinds of ground conditions, contractual practices have also been further developed with the aim of establishing rules, which allow fair compensation of the contractor in spite of all the inherent uncertainties. In Austria, tunnel design practice has been standardized by the introduction of a guideline.

Some of the factors contributing to the success of the method are the awareness of the client of his responsibilities, appropriate site organization, qualified engineers and miners, practically oriented research and education, as well as extensive exchange of experience.
Triple echo steady‐state (TESS) relaxometry
Authors: Heule Rahel , Ganter Carl , Bieri Oliver
Published: April 2013

Purpose

Rapid imaging techniques have attracted increased interest for relaxometry, but none are perfect: they are prone to static (B0) and transmit (B1) field heterogeneities, and commonly biased by T2/T1. The purpose of this study is the development of a rapid T1 and T2 relaxometry method that is completely (T2) or partly (T1) bias‐free.

Methods

A new method is introduced to simultaneously quantify T1 and T2 within one single scan based on a triple echo steady‐state (TESS) approach in combination with an iterative golden section search. TESS relaxometry is optimized and evaluated from simulations, in vitro studies, and in vivo experiments.

Results

It is found that relaxometry with TESS is not biased by T2/T1, insensitive to B0 heterogeneities, and, surprisingly, that TESS‐T2 is not affected by B1 field errors. Consequently, excellent correspondence between TESS and reference spin echo data is observed for T2 in vitro at 1.5 T and in vivo at 3 T.

Conclusion

TESS offers rapid T1 and T2 quantification within one single scan, and in particular B1‐insensitive T2 estimation. As a result, the new proposed method is of high interest for fast and reliable high‐resolution T2 mapping, especially of the musculoskeletal system at high to ultra‐high fields. Magn Reson Med 71:230–237, 2014. © 2013 Wiley Periodicals, Inc.
Probing lung microstructure with hyperpolarized noble gas diffusion MRI: theoretical models and experimental results
Authors: Yablonskiy Dmitriy A. , Sukstanskii Alexander L. , Quirk James D. , Woods Jason C. , Conradi Mark S.
Published: April 2013

The introduction of hyperpolarized gases (3He and129Xe) has opened the door to applications for which gaseous agents are uniquely suited—lung MRI. One of the pulmonary applications, diffusion MRI, relies on measuring Brownian motion of inhaled hyperpolarized gas atoms diffusing in lung airspaces. In this article we provide an overview of the theoretical ideas behind hyperpolarized gas diffusion MRI and the results obtained over the decade‐long research. We describe a simple technique based on measuring gas apparent diffusion coefficient (ADC) and an advanced technique, in vivo lung morphometry, that quantifies lung microstructure both in terms of Weibel parameters (acinar airways radii and alveolar depth) and standard metrics (mean linear intercept, surface‐to‐volume ratio, and alveolar density) that are widely used by lung researchers but were previously available only from invasive lung biopsy. This technique has the ability to provide unique three‐dimensional tomographic information on lung microstructure from a less than 15 s MRI scan with results that are in good agreement with direct histological measurements. These safe and sensitive diffusion measurements improve our understanding of lung structure and functioning in health and disease, providing a platform for monitoring the efficacy of therapeutic interventions in clinical trials. Magn Reson Med 71:486–505, 2014. © 2013 Wiley Periodicals, Inc.
Reconstruction of magnetic resonance imaging by three‐dimensional dual‐dictionary learning
Authors: Song Ying , Zhu Zhen , Lu Yang , Liu Qiegen , Zhao Jun
Published: April 2013

Purpose

To improve the magnetic resonance imaging (MRI) data acquisition speed while maintaining the reconstruction quality, a novel method is proposed for multislice MRI reconstruction from undersampled k‐space data based on compressed‐sensing theory using dictionary learning.

Theory and Methods

There are two aspects to improve the reconstruction quality. One is that spatial correlation among slices is used by extending the atoms in dictionary learning from patches to blocks. The other is that the dictionary‐learning scheme is used at two resolution levels; i.e., a low‐resolution dictionary is used for sparse coding and a high‐resolution dictionary is used for image updating. Numerical experiments are carried out on in vivo 3D MR images of brains and abdomens with a variety of undersampling schemes and ratios.

Results

The proposed method (dual‐DLMRI) achieves better reconstruction quality than conventional reconstruction methods, with the peak signal‐to‐noise ratio being 7 dB higher. The advantages of the dual dictionaries are obvious compared with the single dictionary. Parameter variations ranging from 50% to 200% only bias the image quality within 15% in terms of the peak signal‐to‐noise ratio.

Conclusion

Dual‐DLMRI effectively uses the a priori information in the dual‐dictionary scheme and provides dramatically improved reconstruction quality. Magn Reson Med 71:1285–1298, 2014. © 2013 Wiley Periodicals, Inc.
Local anesthetic effects on gene transcription in human skeletal muscle biopsies
Authors: Trappe Todd A. , Standley Robert A. , Liu Sophia Z. , Jemiolo Bozena , Trappe Scott W. , Harber Matthew P.
Published: April 2013

Introduction: We examined if epinephrine in the local anesthetic to help control incision‐related bleeding interferes with molecular measurements obtained with the Duchenne‐Bergström percutaneous needle biopsy technique for sampling human skeletal muscle. Methods: Three groups received 2.5–3.0 ml of 1% lidocaine in 2 injections: (1) 0.5–1.0 ml superficially, which varied among the groups according to (i) −Epi; intra‐ and subcutaneous without epinephrine, (ii) +Epi −Fascia; intra‐ and subcutaneous with epinephrine, avoiding the fascia, and (iii) +Epi +Fascia; intra‐ and subcutaneous with epinephrine, directing a small amount (∽0.2 ml) into the fascia area; and (2) ∽2.0 ml without epinephrine into the fascia area for all subjects. A muscle biopsy was obtained 5–10 min later for IL‐6 and MuRF‐1 mRNA levels. Results: IL‐6 mRNA levels were low in −Epi and +Epi −Fascia, but ∽300‐fold higher in +Epi +Fascia. MuRF‐1 mRNA levels were similar among the groups. Conclusions: Lidocaine with epinephrine can confound intramuscular measurements from needle biopsies, but this can be avoided with a careful injection approach. Muscle Nerve 48: 591–593, 2013
Empowering Elderly Women with Osteoarthritis Through Hands‐On Exploration of Adaptive Equipment Concepts
Authors: Flinn Sharon R. , Sanders Elizabeth B.‐N. , Yen Wei‐Ting , Sommerich Carolyn M. , Lavender Steven A.
Published: April 2013

The study investigated the participation experiences of elderly women with hand limitations in a maketools‐inspired activity for improving bottle openability and verified the usefulness of the results from this approach. Participatory design was used to stimulate participants' hands‐on fabrication of new bottle lid concepts. Air‐dry modeling clay, Crayola Model Magic® (Crayola LLC, 1100 Church Lane Easton, PA 18044‐0431), clay modeling tools sets and empty bottles were the tools used to explore feasible and user‐envisioned ideal lids that could potentially reduce hand pain and improve function when opening bottles. Twenty‐five elderly women fully participated in the study. They generated 36 bottle lid design concepts. Qualitative analysis identified inclusion of four primary design features as follows: 1) surface texture; 2) increased leverage through lid shape or diameters; 3) increased contact surface with palm/fingers through lid shape or height; and 4) facilitation of alternative grip types. The major limitations of the study were inclusion of only women participants and healthier persons living in a retirement community. Future research is needed to investigate the bottle lid preferences of men and persons with more severe hand function living in places other than independent living communities. Copyright © 2013 John Wiley & Sons, Ltd.
Development of electrical conductivity in PP/HDPE/MWCNT nanocomposite by melt mixing at very low loading of MWCNT
Authors: Bhagat Narendra A. , Shrivastava Nilesh K. , Suin Supratim , Maiti Sandip , Khatua Bhanu B.
Published: April 2013

A method of developing an electrical conductivity in polypropylene (PP) with a very low loading of multiwalled carbon nanotube (MWCNT) by melt‐mixing method was described. PP/high‐density polyethylene (HDPE; 70/30, w/w) was melt blended simultaneously in the presence of MWCNT using two sequential heating protocol (MWCNT was first interacted with HDPE chain at 140°C followed by melt blending of PP at 200°C). Very interestingly, a cocontinuous morphology in the blend was found even for very high asymmetric composition. This has been explained in terms of barrier effect of the MWCNT dispersed selectively in the HDPE phase that restricts the phase inversion into the matrix droplet morphology. A simple method was used for proper dispersion, distribution, and formation of effective conducting network path [carbon nanotube (CNT)–CNT contact] of MWCNT through cocontinuous HDPE phase (minor phase) into PP matrix of the blend which in turn enhanced the electrical conductivity of the nanocomposite with minimum percolation threshold. The percolation threshold of PP/HDPE/MWCNT nanocomposite found at 0.352 wt% loading of MWCNT, which is significantly lower than those reported for developing electrical conductivity in PP/MWCNT nanocomposite. Phase morphology, extent of dispersion and location of the MWCNT in the blend has been investigated with a scanning and transmission electron microscopy. Thermal and mechanical properties of PP/HDPE/MWCNT nanocomposite with variation of MWCNT loading have also been studied. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers
Secondary findings from non‐invasive prenatal testing for common fetal aneuploidies by whole genome sequencing as a clinical service
Authors: Lau Tze Kin , Jiang Fu Man , Stevenson Robert J. , Lo Tsz Kin , Chan Lin Wai , Chan Mei Ki , Lo Pui Shan Salome , Wang Wei , Zhang Hong‐Yun , Chen Fang , Choy Kwong Wai
Published: April 2013

Objective

To report secondary or additional findings arising from introduction of non‐invasive prenatal testing (NIPT) for aneuploidy by whole genome sequencing as a clinical service.

Methods

Five cases with secondary findings were reviewed.

Results

In Case 1, NIPT revealed a large duplication in chromosome 18p, which was supported by arrayCGH of amniocyte DNA, with final karyotype showing mosaic tetrasomy 18p. In Case 2, a deletion in the proximal long arm of chromosome 18 of maternal origin was suspected and confirmed by arrayCGH of maternal white cell DNA. In Case 3, NIPT was negative for trisomies 21 and 18. In‐depth analysis for deletions/duplications was requested when fetal structural anomalies were detected at routine scan. A deletion in the proximal long arm of chromosome 3 was found and confirmed by karyotyping. In Case 4, NIPT correctly predicted confined placental mosaicism with triple trisomy involving chromosomes X, 7 and 21. In Case 5, NIPT correctly detected a previously unknown maternal mosaicism for 45X.

Conclusion

Non‐invasive prenatal testing is able to detect a wide range of fetal, placental and maternal chromosomal abnormalities. This has important implications on patient counseling when an abnormality is detected by NIPT. © 2013 John Wiley & Sons, Ltd.
Anticandidal activity of cobalt containing sunflower oil‐based polymer
Authors: Singh Taruna , Khan Nazia Umar , Shreaz Sheikh , Hashmi Athar Adil
Published: April 2013

Bioactive metal cobalt containing sunflower oil‐based polyesteramide resin was developed by condensation polymerization reaction among oil‐derived sunflower fatty amide diol, adipic acid, and cobalt chloride. Microwave‐assisted synthesis was used throughout the reaction as it enhances reaction rate, gives higher yield, and greater purity of the products. Spectroscopic techniques, such as Fourier transform infrared spectroscopy and proton‐nuclear magnetic resonance, have been used to establish the structure of the polymers. Presence of cobalt in polymer has been confirmed through atomic absorption spectroscopy. Standard laboratory methods such as acid value, hydroxyl value, saponification value, iodine value, specific gravity, and viscosity were used to study the physicochemical characteristics of the polymers. Thermal behavior of the polymer was analyzed using thermogravimetry/differential thermal analysis. The synthesized polymers were evaluated for their biological activity. This study indicates that the synthesized polymer has significant antifungal activity against Candida, including azole‐resistant strains, advocating further investigation for clinical applications in the treatment of fungal infections. POLYM. ENG. SCI., 53:2650–2658, 2013. © 2013 Society of Plastics Engineers
Deformation velocity dependence on tensile fracture characteristics of polypropylene injection molding parts
Authors: Ota Yoshinori , Ito Hiroshi , Ishikawa Masaru
Published: April 2013

To clarify the mechanism of the deformation and fracture in a low‐velocity impact test on the isotactic polypropylene (i‐PP) sheet made by injection molding, the change of the style of fracture and the form of deformation was examined while changing the speed of the striker in a low‐velocity impact test. In the injection molding sheet, an oriented skin layer of some thickness is formed on the surface of the sample sheet. By the stress perpendicular to the orientation direction of the skin layer, crazes were formed easily in parallel with the orientation direction in this layer, and cracks were formed from there. Because these cracks bring the sample sheet a strong restraint of strain, a high stress concentration occurs at the end of this crack even if the formation of the oriented layer is limited on the surface of the sample sheet only, and the low‐velocity impact test leads the sample sheet to a brittle fracture. As a result, the injection molding sheet that forms oriented structure on its surface causes the ductility‐brittleness transform at a lower velocity of deformation compared with the nonoriented sheet. POLYM. ENG. SCI., 53:2659–2665, 2013. © 2013 Society of Plastics Engineers
Morphologies and crystal structures of styrene–acrylonitrile/isotactic polypropylene ultrafine fibers fabricated by melt electrospinning
Authors: Cao Li , Dong Mu , Zhang Anyang , Liu Yong , Yang Weimin , Su Zhiqiang , Chen Xiaonong
Published: April 2013

Ultrafine fibers or fiber web is an attractive material for its high aspect ratio or porous structure which is welcomed in various applications. In this study, ultrafine fibers (5–10 μm) of styrene–acrylonitrile (SAN) copolymer/isotactic polypropylene (iPP) blends were produced by melt electrospinning, SAN acted as a polymeric nucleating agent (PNA) in iPP fibers. Wide‐angle X‐ray diffraction, differential scanning calorimetry, scanning electron microscopy, and polarized optical microscopy were used to investigate the morphologies and the crystal structures of SAN/iPP electrospun fibers. The results showed that SAN/iPP melt formed microfibers with different morphologies and crystallinities through electrostatic stretching. The morphological distribution of SAN in iPP fibers depended on the SAN content, and the distribution influenced its nucleating activity and the final crystal structure of SAN/iPP electrospun fibers. After annealing treatment, the molecular chains of iPP in the confined SAN/iPP microfibers disorientated and rearranged, leading to the formation of a mixture of α‐ and γ‐crystal forms. The relative amount of the γ‐crystal form depended on PNA's concentration, annealing temperature and annealing time. Melt electrospun iPP fibers prepared in this study were collected as fiber webs that can be used for protective clothing material, filtration media, reinforcement for composites, and so on. POLYM. ENG. SCI., 53:2674–2682, 2013. © 2013 Society of Plastics Engineers
Proteomic analysis reveals that CD147/EMMPRIN confers chemoresistance in cancer stem cell‐like cells
Authors: Kang Min Jueng , Kim Hwang‐Phill , Lee Kyeong‐seob , Yoo Young‐Dong , Kwon Yong‐Tae , Kim Kristine M. , Kim Tae‐You , Yi Eugene C.
Published: April 2013

Cancer stem cells (CSCs) are a subpopulation of tumor cells that can self‐renew, metastasize, and promote cancer recurrence. A comprehensive characterization of the CSC proteome has been hampered due to their scarcity and rapid differentiation. Here, we present a systematic analysis of the cell‐surface proteome using a CSC‐like cell line derived from MDA‐MB453 breast cancer cells, which exhibited a CD44+/CD24− (where CD is cluster of differentiation) phenotype and chemoresistance. We identified differentially expressed proteins in CSC‐like cells, including upregulated plasma membrane proteins such as CD44, CD133, epidermal growth factor receptor (EGFR), CD147, cadherin 1, integrins, and catenin (cadherin‐associated protein), beta 1 (CTNNB1), using an in‐situ biotinylation approach followed by MS analysis. We examined the role of CD147 in the promotion of CSC growth and survival, and demonstrated that inhibition of CD147 with a monoclonal antibody induced significant inhibition of cell growth. siRNA‐mediated silencing of CD147 gene expression restored the sensitivity of CSC‐like cells to 5‐fluorouracil (5‐FU), along with decreasing the expression of thymidylate synthase, p‐AKT, and β‐catenin, while increasing the expression of p‐glycogen synthase kinase (GSK)3β. Increased CD147 expression in the CSC‐like cells, as seen by proteomic analysis, and the functional consequences of CD147 overexpression in CSC‐like cells suggest that CD147 may be one of the critical cell‐surface proteins involved in promoting chemoresistance and survival in CSCs.
Expression, purification and proteomic analysis of recombinant histone H4 acetylated at lysine 16
Authors: Kallappagoudar Satish , Dammer Eric B. , Duong Duc Minh , Seyfried Nicholas T. , Lucchesi John C.
Published: April 2013

Many histone covalent modifications have been identified and shown to play key regulatory roles in eukaryotic transcription, DNA damage repair, and replication. In vitro experiments designed to understand the mechanistic role of individual modifications require the availability of substantial quantities of pure histones, homogeneously modified at specific residues. We have applied the amber stop codon/suppressor tRNA strategy to the production of histone H4 acetylated at lysine 16, a particularly important isoform of this histone. Our success relies on adapting the H4 DNA sequence to the codon preference of E. coli and on preventing the premature decay of the H4 mRNA. These modifications to the original procedure render it easily applicable to the generation of any covalently modified histone H4 isoform.
Facile synthesis and electro‐optic activities of new polycarbonates containing tricyanofuran‐based nonlinear optical chromophores
Authors: Deng Guowei , Bo Shuhui , Zhou Tingting , Huang Heyan , Wu Jieyun , Liu Jialei , Liu Xinhou , Zhen Zhen , Qiu Ling
Published: April 2013

Two series of novel electro‐optic (EO) polycarbonates containing two different kinds of nonlinear optical (NLO) chromophores with tricyanofurane (TCF) electron acceptor have been successfully prepared through the facile polycondensation between diol NLO chromophore and bisphenol A bis(chloroformate). These new polycarbonates which were characterized by 1H‐NMR and Fourier transform infrared exhibited good solubility in common polar organic solvents. They also showed glass transition temperatures (Tg) in the range of 124–156 °C. The morphology studies indicated that these polycarbonates had good film quality before and after corona poling. The EO coefficients (r33) of two polycarbonates films were up to 45 pm/V (PC‐TCFC‐2) and 75 pm/V (PC‐DFTC‐3) at the wavelength of 1310 nm. Moreover, good temporal stability of the poling‐induced dipole alignment was also achieved, and the resulting poled films of PC‐TCFC‐2 and PC‐DFTC‐3 could retain 90 and 80% of the initial EO activities at 85 °C for more than 500 h, respectively. Both EO activity and temporal stability results were better than the guest–host EO polymers containing the same concentration chromophores, which indicated that such kind of polycarbonates could effectively suppress the intermolecular electrostatic interaction and translate microscopic molecular hyperpolarizability into macroscopic EO activity. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2841–2849.
Platinum and gold diffusion monitor vacancy profiles induced into silicon wafers by aluminum alloying
Authors: Abdelbarey D. , Kveder V. , Schröter W. , Seibt M.
Published: April 2013

In this paper, we use the gold and platinum marker method, to confirm our preliminary finding that aluminum indiffusion into Si crystal during so‐called “aluminum gettering” (AlG) can result in the injection of vacancies into Si crystal. Depth profiles of Au in p‐type Si have been studied by the DLTS after diffusion at 850 °C for 2 h prior to and subsequent to AlG. The donor concentration attributed to Aus is about two orders of magnitude higher compared with that measured in samples without AlG. Similar results were also observed for Pt. The increase in Pts or Aus concentration in the silicon bulk provides the most direct evidence so far that AlG with 400 nm Al layer, for 50 min at 1100 °C injects vacancies with non‐equilibrium concentrations of about 1015 cm−3. The possible mechanism of vacancies generation is discussed.
Pressure studies of multicarrier conduction in undoped InN grown on GaN buffer
Authors: Dmowski L. H. , Konczewicz L. , Suski T. , Contreras S. , Lu H. , Schaff W. J.
Published: April 2013

The importance of multicarrier contributions to electrical conductivity in epitaxial InN layered structures has been debated for last few years. In this work hydrostatic pressure was used to verify multicarrier conduction in nominally undoped InN layers with In‐growth polarity. To distinguish between different types of carriers the mobility spectrum analysis was applied, based on conductivity tensor components σxx and σxy measured as a function of magnetic field. Different contributions to the electric conduction (including the surprising presence of holes) and their evolution with pressure have been shown.
Extracting the hybrid functional mixing parameter from a GW quasiparticle approach
Authors: Mitra Chandrima
Published: April 2013

Relying on quasiparticle GW electronic structure calculations we present an approach to obtain an “optimal value” of the so called “mixing parameter,” α, in hybrid functional calculations. We show that when this “optimal” amount of exact exchange (we denote this as αopt) is mixed with the semi‐local PBE exchange‐correlation functional, the net quasiparticle corrections to the PBE Kohn–Sham eigenvalues attain a minimum value. We employ this approach to perovskite oxide insulators SrTiO3 and PbTiO3 and compare that to the widely studied semiconductor compounds, Si and Ge. A system dependence of the optimal choice of the mixing parameter is revealed.
Corrosion resistance and cytotoxicity of a MgF2 coating on biomedical Mg–1Ca alloy via vacuum evaporation deposition method
Authors: Li N. , Li Y. D. , Wang Y. B. , Li M. , Cheng Y. , Wu Y. H. , Zheng Y. F.
Published: April 2013

To reduce the biocorrosion rate and enhance the biocompatibility by surface modification, MgF2 coatings were prepared on Mg–1Ca alloy using vacuum evaporation deposition method. The average thickness of the coating was about 0.95 µm. The results of immersion test and electrochemical test indicated that the corrosion rate of Mg–1Ca alloy was effectively decreased after coating with MgF2. The MgF2 coating induced calcium phosphate deposition on Mg–1Ca alloy. After 72 h culture, MG63 cells and MC3T3‐E1 cells were well spread on the surface of the MgF2‐coated Mg–1Ca alloy, while few cells were observed on uncoated Mg–1Ca alloy samples. In summary, MgF2 coating showed beneficial effects on the corrosion resistance and thus improved cell response of the Mg–1Ca alloy effectively and should be a good surface modification method for other biomedical magnesium alloys. Copyright © 2013 John Wiley & Sons, Ltd.
Using group‐based latent class transition models to analyze chronic disability data from the National Long‐Term Care Survey 1984–2004
Authors: White Toby A. , Erosheva Elena A.
Published: April 2013

Latent class transition models track how individuals move among latent classes through time, traditionally assuming a complete set of observations for each individual. In this paper, we develop group‐based latent class transition models that allow for staggered entry and exit, common in surveys with rolling enrollment designs. Such models are conceptually similar to, but structurally distinct from, pattern mixture models of the missing data literature. We employ group‐based latent class transition modeling to conduct an in‐depth data analysis of recent trends in chronic disability among the U.S. elderly population. Using activities of daily living data from the National Long‐Term Care Survey (NLTCS), 1982–2004, we estimate model parameters using the expectation–maximization algorithm, implemented in SAS PROC IML. Our findings indicate that declines in chronic disability prevalence, observed in the 1980s and 1990s, did not continue in the early 2000s as previous NLTCS cross‐sectional analyses have indicated. Copyright © 2013 John Wiley & Sons, Ltd.
NIR Photoresponsive Crosslinked Upconverting Nanocarriers Toward Selective Intracellular Drug Release
Authors: Yang Yanmei , Velmurugan Bhaarathy , Liu Xiaogang , Xing Bengang
Published: April 2013

An NIR‐responsive mesoporous silica coated upconverting nanoparticle (UCNP) conjugate is developed for controllable drug delivery and fluorescence imaging in living cells. In this work, antitumor drug doxorubicin (Dox) molecules are encapsulated within cross‐linked photocaged mesoporous silica coated UCNPs. Upon 980 nm light irradiation, Dox could be selectively released through the photocleavage of theo‐nitrobenzyl (NB) caged linker by the converted UV emission from UCNPs. This NIR light‐responsive nanoparticle conjugate demonstrates high efficiency for the controlled release of the drug in cancer cells. Upon functionalization of the nanocarrier with folic acid (FA), this photocaged FA‐conjugated silica‐UCNP nanocarrier will also allow targeted intracellular drug delivery and selective fluorescence imaging towards the cell lines with high level expression of folate receptor (FR).
Colloid‐in‐Liquid Crystal Gels that Respond to Biomolecular Interactions
Authors: Agarwal Ankit , Sidiq Sumyra , Setia Shilpa , Bukusoglu Emre , de Pablo Juan J. , Pal Santanu Kumar , Abbott Nicholas L.
Published: April 2013

This paper advances the design of stimuli‐responsive materials based on colloidal particles dispersed in liquid crystals (LCs). Specifically, thin films of colloid‐in‐liquid crystal (CLC) gels undergo easily visualized ordering transitions in response to reversible and irreversible (enzymatic) biomolecular interactions occurring at the aqueous interfaces of the gels. In particular, LC ordering transitions can propagate across the entire thickness of the gels. However, confinement of the LC to small domains with lateral sizes of ∼10 μm does change the nature of the anchoring transitions, as compared to films of pure LC, due to the effects of confinement on the elastic energy stored in the LC. The effects of confinement are also observed to cause the response of individual domains of the LC within the CLC gel to vary significantly from one to another, indicating that manipulation of LC domain size and shape can provide the basis of a general and facile method to tune the response of these LC‐based physical gels to interfacial phenomena. Overall, the results presented in this paper establish that CLC gels offer a promising approach to the preparation of self‐supporting, LC‐based stimuli‐responsive materials.
Amorphous Ni(OH)2 Nanoboxes: Fast Fabrication and Enhanced Sensing for Glucose
Authors: Nai Jianwei , Wang Shuqian , Bai Yang , Guo Lin
Published: April 2013

Inspired by Pearson's hard and soft acid‐base (HSAB) principle, uniform amorphous Ni(OH)2 nanoboxes with intact shell structures and various sizes are quickly fabricated by deliberately selecting S2O32− as the coordinating etchant toward Cu2O templates and optimizing the reaction conditions. It is found that not only the solvent system but also the employing of a surfactant is vital for the fabrication of the nanoboxes. Ni(OH)2 nanoboxes, as an example, demonstrate an improved electrochemical sensing ability for glucose, which might be due to their amorphous and hollow structural features.
Research of the Continuous Casting Slab Transverse Cracking During Retarded Cooling Process
Authors: Wu MaoMeng , Yu Hao , Fan YonFei , Wang FengXian , Wang JianJing
Published: April 2013

In this paper, the reason of 50Mn2V transverse cracking is studied by optical metallographic, SEM and in situ analysis system. Results show that the pearlite is surrounded by the net‐like pro‐eutectoid ferrite which locates at the former austenite grain boundary, the hydrogen content (ca.2 × 10−4 wt%) exceeds the critical solubility in room temperature structure, divers types, and sizes inclusions (10–100 µm), plenty of fissures (2–50 µm) and classical cleavage fracture surface are obviously observed, meanwhile, a great degree of elements segregation (P, S, V, Ni, Cr correspond to 1.757, 1.674, 1.729, 1.475, 1.195, respectively) and a poorly 0.9283 integral density exist in this blank. From the above, internal gas pressure should be the dominant factor that leads the transverse embrittlement, while internal stresses, element segregation, and defects play an ancillary role.
Optimization of Fine Hydro‐Blanking
Authors: Wang Jang‐Ping , Huang Guo‐Ming , Lee Hsien‐Der , Chen Chih‐Chun , Chen Te‐Tsun , Chen Chia‐Ling
Published: April 2013

Optimization of the process of the fine hydro‐blanking is proposed. In this approach, the V‐ring indenter carved on the work piece substitutes for the guide plate that is used by the conventional fine blanking and is pressurized by hydraulic pressure. In addition, the counter force is also replaced by hydraulic pressure to produce a uniform back‐pressure by acting as the ejector. To find the final optimal solution, the Taguchi‐FE method is adopted to simulate and find the optimal factors according to the Taguchi technology. Once the optimal factors were chosen, a hybrid system that combined the artificial neural network (ANN) with the genetic algorithm (GA) is used to search and find the final optimal solution. It was observed that the V‐ring cavity on the work‐piece has the same efficacy as conventional fine blanking. In addition, the results of the experiment and finite element simulation using the optimal factors were compared. It was found that the study could achieve its stated objectives.
Optimization in Rolling and Cooling Process of Line Pipe Steels
Authors: Agarwal Pradeep , Sah Rameshwar , Madhusudhan Raj Gopalan , Manjini Sambandam , Chandra Ashish
Published: April 2013

Optimized microstructure and mechanical properties are the key requirements for line pipe steels. In the hot rolling process, it can be achieved through optimization in rolling schedule and cooling process. The present study uses hot strip mill modeling (HSMM) interface to model hot rolling process. Two API line pipe grades equivalent to “API X‐70 & API X‐80” have been modeled for its final microstructure and mechanical properties based on thermal, mechanical, and microstructural changes occurring during hot rolling. The model has been validated with plant data and test results. Austenite recrystallization model has been validated against calculated flow stresses from actual roll forces applied. Phase transformation model has been validated with the final microstructure and mechanical properties. The API X‐70 grade shows strain accumulation (i.e., no recrystallization) in the finish rolling stage only, while the X‐80 grade carries the strain accumulation from the roughing passes also, resulting in very fine grain ferrite. It is due to high retained strain before the phase transformation on run out table. The predicted properties by the model are in close proximity for multiple coils and different locations in the coil for both the grades.
Effect of Inclusions and Precipitates on Hydrogen Embrittlement of Mn‐Alloyed Austenitic Stainless Steels
Authors: Pulkkinen Heikki , Papula Suvi , Todoshchenko Olga , Talonen Juho , Hänninen Hannu
Published: April 2013

The aim of this study was to characterize the inclusions and precipitates of the six austenitic stainless steel test materials by the INCA analysis program as well as to examine the capability of inclusions and precipitates to act as hydrogen traps by utilizing the thermal desorption spectroscopy (TDS). Especially, the hydrogen trapping capability of nano‐sized Nb‐precipitates of the steel 204Cu/Nb was of interest. On the INCA results it was noticed that the average sizes of the inclusions as well as the distribution and the amount of the oxide inclusions were about the same in all test materials. In comparison to the other grades, the distribution of inclusions and precipitates was significantly different in the niobium‐alloyed 204Cu/Nb steel containing a large number of small micro‐ and nano‐sized niobium precipitates. In the TDS study, it was observed that the TDS spectra of 201B, 204Cu, and 204Cu/Nb were similar, although the inclusion and precipitation distribution of these steels differs considerably between the materials. Thus, it was assumed that the nano‐sized Nb‐precipitates or other inclusions were not able to trap sufficiently hydrogen to their interface, which would result in a better resistance against delayed cracking.
Behindertengerechte Geh‐ und Radwegüberführung "Gottlieberstraße" in Konstanz ‐ Entwurf und Ausführung
Authors: Hornecker G. , Baumgärtner R.
Published: April 2013

Mit einer räumlichen Stahlfachwerk‐Konstruktion wurde in einem sensiblen innerstädtischen Umfeld in Konstanz eine behindertengerechte Geh‐ und Radwegverbindung realisiert. Die asymmetrische Brückenlösung paßt zu dem Umfeld. Die Gestaltung, insbesondere der konkave Grundriß, entspringt der sich natürlich ergebenden örtlichen Situation. Im folgenden Aufsatz wird auf Fragen der Entwurfsentstehung, der Gründungsproblematik, der Konstruktion und Statik des Tragwerks und der Herstellung eingegangen.
Der Überbau der Eisenbahn‐Bogenbrücke über den Rhein zwischen Ludwigshafen und Mannheim
Authors: Hugle F. , Krämer G. , Matuschek J. , Stiglat K. , Weyer U.
Published: April 2013

In diesem Aufsatz wird das Entstehen der neuen Eisenbahnbrücke über den Rhein zwischen Ludwigshafen und Mannheim beschrieben. Sie verbindet die Länder Rheinland‐Pfalz und Baden‐Württemberg und liegt im Zuge der Ausbaustrecke Mainz‐Mannheim bei km 069,038 der DB‐Strecke Nr. 3522.

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Talbrücke Korntal‐Münchingen, Teil 2 ‐ Ausschreibung, Vergabe und Bau
Authors: Bernhardt K. , Mohr B. , Saul R. , Binder B. , Kaßelmann M. , Reuter R. , Häderle M. U.
Published: April 2013

Im Februarheft dieser Zeitschrift wurde der Entwurf der Talbrücke Korntal‐Münchingen mit zahlreichen Plänen ausführlich dargestellt. In diesem Beitrag wird nun über die Ausschreibung, Vergabe und insbesondere über die Baudurchführung berichtet. Die monolithische Bauweise (Betongelenke zwischen Pfeiler und Überbau) sowie der Verbundbereich mit Rohrfachwerk und Gußknoten prägen diesen Brückenbau.
Olympiastadion Berlin ‐ Die neue Tribünenüberdachung
Authors: Stroetmann R. , Schneider R.
Published: April 2013

Das Olympiastadion Berlin wird zur Zeit unter strengen Auflagen des Denkmalschutzes umfassend modernisiert und instandgesetzt. Ein Teil der umfangreichen Baumaßnahmen ist der Neubau der Tribünenüberdachung. Hierbei handelt es sich um eine leichte und weit auskragende Fachwerkkonstruktion aus Stahlhohlprofilen, die mit einer oberen und unteren Membranhaut sowie im inneren Dachbereich mit einer Glaseindeckung versehen wird. Nach einer kurzen Beschreibung der geschichtlichen Entwicklung des Stadions und der Gesamtbaumaßnahme wird über Entwurf, Konstruktion, Berechnung und Ausführung der neuen Tribünenüberdachung berichtet.
Rechenmethode zur Einschätzung des Langzeit‐Tragverhaltens von Stahlkonstruktionen
Authors: Goto Y. , Kawanishi N.
Published: April 2013

Um die Kosten über die gesamte Lebensdauer möglichst exakt abzuschätzen, ist eine Voraussage des Langzeit‐Tragverhaltens erforderlich. Hier wird eine neue Rechenmethode vorgestellt, die die Wirkung von Korrosion und die Wirkung der Reparatur der korrosionsbefallenen Stellen auf die Langzeit‐Tragfähigkeit berücksichtigt. Die neue Berechnungsmethode erfaßt zusätzlich, neben den konventionellen Kontrollparametern wie Lasten und Verschiebung, noch die Änderung des Querschnitts von Konstruktionselementen. Nebenbei kann diese Rechenmethode auch andere Schadenseinwirkungen über die Zeit infolge großer äußerer Lasten, wie z. B. Erdbebenlasten, erfassen.
Ein Vorschlag zur Bemessung einer gekrümmten Brücke mit offenem Querschnitt unter Verwendung von diagonalen Querträgern
Authors: Hayashikawa T. , Hirasawa H.
Published: April 2013

Die Torsionssteifigkeit eines zweistegigen Plattenbalkens ist wegen des offenen Querschnitts nicht groß. Somit ist es schwierig, diesen Querschnittstyp bei einer im Grundriß gekrümmten Trägerbrücke zu verwenden. Es ist erforderlich, den Träger zu verstärken, damit keine Torsionsverformungen auftreten. Dieser Beitrag schlägt vor, die I‐Träger auf neue Weise mit Querträgern zu verstärken. Die Querträger werden dabei im unteren Bereich des Hauptträgers an die Hauptträger angeschlossen, aber nicht rechtwinklig, sondern diagonal. Dieses System hat keine Horizontalverbände, jedoch erfüllen die diagonal verlaufenden Querträger den gleichen Zweck. Das Anbringen der Querträger im unteren Bereich der Hauptträger hat die Wirkung eines Untergurtverbandes. Die Ergebnisse aus der FEM‐Untersuchung zeigen, daß mit dem neuen System geringere Verformungen, kleinere Spannungsverteilungen und eine günstige Lastverteilung zwischen den beiden Hauptträgern erreicht werden.
Verdeckte Rechteck‐Hohlprofil‐Verbindungen unter Zugbelastung
Authors: Willibald S. , Puthli R. S. , Packer J. A.
Published: April 2013

Die geschlossene Querschnittsform von Hohlprofilen ermöglicht besonders ästhetische Bauwerke, in denen die Konstruktion offen gezeigt wird. Eine frei sichtbare Dachkonstruktion fasziniert und weckt das Interesse des Betrachters an den Zusammenhängen von Konstruktion und Kräftefluß. Architekten wollen durch eine gleichmäßige Struktur eine elegante Gesamtkonstruktion erreichen. Hierbei sind typische Stoßverbindungen meist störend, da sie eine Unterbrechung der eigentlichen Struktur darstellen. Im Gegensatz zu den typischen Stoßverbindungen, wie Kopfplatten‐ oder Laschenverbindungen mit geschlitztem Hohlprofil, ermöglichen die sogenannten verdeckten Knotenverbindungen ein von Außen unsichtbares Stoßen des Hohlprofils. Die nicht‐konstruktive Abdeckung über der eigentlichen Verbindung ermöglicht die optische Fortsetzung der Struktur.

Eine versuchstechnische und numerische Studie zu dieser Verbindungsart bei Zugbelastung ist durchgeführt worden. Der Hauptaugenmerk dieser Studie lag auf dem plötzlichen Bruch des Hohlprofils durch die örtlich begrenzte Lasteinleitung am Schweißnahtende. Neben einer Literaturstudie zu dieser im Eurocode 3 bisher nicht berücksichtigten Versagensart wird ein Nachweisbeispiel zu einer verdeckten Knotenverbindung gegeben.
Fußgängerbrücken: Drei Wettbewerbe in Heilbronn, Ulm und Weil am Rhein
Authors: Schäfer A. , Andelfinger J. , Strobl W.
Published: April 2013

Die drei Entwürfe für Fußgängerbrücken sind im Rahmen von Wettbewerben, durch die intensive Auseinandersetzung mit der gestellten Aufgabe, entwickelt worden. Die Entwürfe wurden jeweils mit Preisen prämiert.
Entwurf und Ausführung einer Bogenbrücke über die Bahnanlagen in Mühlacker
Authors: Angelmaier V. , Bothner R.
Published: April 2013

Die innerstädtische Bogenbrücke in Mühlacker über die Gleisanlagen im Bahnhofsbereich stellt ein Beispiel für eine konstruktive Zusammenarbeit von kommunaler Verwaltung, Ingenieurbüro und ausführenden Baufirmen dar.

Geschildert werden die einzelnen, in enger Abstimmung mit der Stadtverwaltung und dem Gemeinderat ablaufenden Entwurfsschritte bis hin zur Bauausführung, und belegt wird, daß auch auf kommunaler Planungsebene mit einem gegenüber Innovationen aufgeschlossenen Bauherrn und kooperativen Planungs‐ und Baupartnern durchaus Stadtbild prägende Brückenentwürfe realisierbar sind.
Stahlguß im modernen Brückenbau
Authors: Angelmaier V.
Published: April 2013

Der Beitrag stellt eine Standortbestimmung hinsichtich der Anwendung von Stahlguß im Brückenbau insbesondere bei Hohlprofilkonstruktionen in bezug auf Lehre und Forschung, aktuelles Regelwerk sowie Herstellung und Gütesicherung dar. Am Beispiel von zwei ausgeführten Brücken werden praktische Erfahrungen vorgestellt.
Neue Terrasse Dresden: Balkon an der Elbe
Authors: Fink R. , Schäfer Ch.
Published: April 2013

Der Beitrag stellt die massive Stahlbetonplatte und ihre Unterspannung (Neue Terrasse) am Kongreßzentrum Dresden vor. Der Schwerpunkt wird auf die Probleme der Verformungsbegrenzung, des Schwingungsverhaltens und des Brandschutzes sowie auf die Lösungen bei der Realisierung gelegt.
Innovativer Schutz gegen Schiffsanprall für die Brücke Rosario‐Victoria über den Paraná (Argentinien)
Authors: Saul R. , Hopf S. , Humpf K. , Platsch A.
Published: April 2013

Die Schrägseilbrücke über den Paraná mit einer Mittelöffnung von 350 m und einer Gesamtlänge von 608 m, ihre Vorlandbrücken auf beiden Seiten des Flusses mit Längen von 2377 m bzw. 1131 m sowie die 12 Schutzeinrichtungen zur Sicherung der Brücke gegen den Anprall von Schiffen bis zu 100000 dwt sind die wesentlichen Bauwerke der neuen, als BOT‐Projekt errichteten Straßenverbindung zwischen den Städten Rosario und Victoria, Argentinien.

Nach einer allgemeinen Beschreibung der Baumaßnahme wird über die Schutzeinrichtungen berichtet, die aus Verbund‐Großbohrpfählen aus hochfestem Stahl StE 690 und den zugehörigen Pfahlkopfplatten bestehen und für die Absorption der Energie der ‐ nach probabilistischen Kriterien definierten ‐ Bemessungsschiffe ausgelegt wurden. Die Bemessung für plastische Grenztragfähigkeit und ‐verformungen dieser Opferkonstruktionen erforderte einige ungewöhnliche Annahmen, die durch Modellversuche abgesichert wurden.
Die Aufgaben der Schweißaufsicht im Kranbau
Authors: Brandl M. , Köfler E. , Hanke R. , Fiedler M.
Published: April 2013

Im Kranbau werden aufgrund der Leichtbauweise und der dynamischen Beanspruchung hohe Anforderungen an die Stahlkonstruktion gestellt. Hochfeste Werkstoffe wie insbesondere die Feinkornbaustähle und deren schweißtechnische Verarbeitung spielen eine zentrale Rolle in der Produktion.

Entsprechend vielseitig und verantwortungsvoll sind die Aufgaben der Schweißaufsicht: Sie reichen von Werkstoffen und Schweißverfahren über die Schweißerqualifikation und Verfahrensprüfungen bis zu Reparaturanweisungen und Produktivitätssteigerung.
Meßwertgestützte Beurteilung des Gebrauchsverhaltens einer Stahlverbund‐Autobahnbrücke
Authors: Hannawald F. , Reintjes K.‐H. , Graße W.
Published: April 2013

Beim Neubau schlanker Verbundbrücken treten gelegentlich zu große Verformungen in der Gradiente auf, deren Folge kostenintensive Ausgleichsmaßnahmen sind. Ursache sind oft die zeitabhängigen Verformungen des Bauwerkes, die sich infolge Kriechens des Betons einstellen und deren Größen in Abhängigkeit vom Herstellungsverfahren und der Querschnittsausbildung unterschiedlich starken Einfluß haben. Weitere Kriterien der Gebrauchstauglichkeit stellen das Schwingungsverhalten sowie die sich unter Gebrauchslasten einstellenden Rißbreiten dar.

Das Bestreben, schlanker und damit materialsparender zu bauen, hat somit zur Folge, daß man sich in Bereichen bewegt, welche hinsichtlich der Gebrauchstauglichkeit als kritisch zu bewerten sind und genauere Kenntnisse über das Materialverhalten erfordern. Daher wird ergänzend zu den aktuellen Bemessungskonzepten der Verbundträgerrichtlinie und des EC 4‐2 das reale Steifigkeits‐ und Tragverhalten im Bereich der Gebrauchslasten am Beispiel der Unionbrücke Dresden‐Radebeul genauer untersucht. Ein geeignetes Mittel hierfür sind meßtechnische Untersuchungen, über die im folgenden berichtet wird.