bluuebunny/crossref_metadata_2025 huggingface dataset:
Origin and influence of water‐induced chain relaxation phenomena in chitosan biopolymers
Authors: Kobaisi Mohammad Al , Murugaraj Pandiyan , Mainwaring David E.
Published: December 2011

Chain dynamics, probed by dielectric spectroscopy, provide a route to further understanding of the molecular interactions induced by hydration, degree of crosslinking, and microstructural changes occurring on swelling of biopolymers such as chitosan, which is becoming a focus for biomedical engineering and therapeutic delivery. The basis of the β‐wet relaxation peak is established as segmental chain relaxation between chitosan water bridges and related to its hysteresis induced by microstructural changes during wetting and dewetting cycles. Linear expansion probes the hysteresis arising from bridging water interactions during the hydration–dehydration paths which is also shown in the resultant ionic conductivity. β‐wet relaxation and ionic conductivity exhibit identical hysteresis behavior with both degrees of chemical crosslinking and water contents. X‐ray diffraction shows that the degree of crosslinking and hydration also influences the degree of disorder of the polymer chains changing both the crystalline phase fraction and lattice dimensions. These molecular interactions provide power law behavior between β‐wet relaxation dynamics and ionic mobility over five orders of magnitude for all degrees of chemical crosslinking and water bridging which is independent of the significant hysteresis in these properties indicative of scaling behavior within the noncrystalline gel phase. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Modulation of cell responses by creating surface submicron topography and amine functionalities
Authors: Chen Jian‐Je , Ho Quoc‐Phong , Wang Meng‐Jiy
Published: December 2011

The incorporation of biological function into synthetic polymers provides particular potential for advances in studying the complex interactions between biomolecules and materials. We developed a simple method to create polymer with submicron features on surface of polystyrene‐co‐maleic anhydride (PSMAA) using a combination of phase‐separation and spin coating method. The nanostructured PSMAA which was rarely utilized as biomaterials was further functionalized by doping with dopamine or by treating with nitrogen containing plasma. This study demonstrated a straightforward method that the creation of topographical cues alone improves the biocompatibility of PSMAA thin film. The cell proliferation increased more significantly to ∼1.8‐ and 2.5‐fold on dopamine blended and N2/H2 plasma treated PSMAA films when compared to that on the flat sample, respectively. The overall results showed that the integration of microenvironment and chemical functionalities into materials provide promising effects for promoting mammalian cell growth. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
"The quest for biomarkers": Are we on the right technical track?
Authors: Boschetti Egisto , Chung Maxey C. M. , Righetti Pier Giorgio
Published: December 2011

The discovery phase of biomarkers of diagnostic or therapeutic interest started a decade ago with the very rapid development of proteomic investigations. In spite of the development of innovative technologies and multiple approaches, the "harvest" is still modest. Various reasons justified the encountered difficulties and most of them have been circumvented by specific sample treatments or dedicated analytical approaches. Nevertheless, the situation of very modest biomarker discovery level did not change much. This review intends to specifically analyze the main approaches used for biomarker discovery phase and evaluate related advantages and disadvantages. Thus, preliminary sample treatments such as fractionation, depletion and reduction of dynamic concentration range will critically be discussed and then the main differential expression investigation methods analyzed. Combinations of technologies are also discussed along with possible proposals to federate associations of complementary technologies for better chances of success.
Functional protease profiling for diagnosis of malignant disease
Authors: Findeisen Peter , Neumaier Michael
Published: December 2011

Clinical proteomic profiling by mass spectrometry (MS) aims at uncovering specific alterations within mass profiles of clinical specimens that are of diagnostic value for the detection and classification of various diseases including cancer. However, despite substantial progress in the field, the clinical proteomic profiling approaches have not matured into routine diagnostic applications so far. Their limitations are mainly related to high‐abundance proteins and their complex processing by a multitude of endogenous proteases thus making rigorous standardization difficult. MS is biased towards the detection of low‐molecular‐weight peptides. Specifically, in serum specimens, the particular fragments of proteolytically degraded proteins are amenable to MS analysis. Proteases are known to be involved in tumour progression and tumour‐specific proteases are released into the blood stream presumably as a result of invasive progression and metastasis. Thus, the determination of protease activity in clinical specimens from patients with malignant disease can offer diagnostic and also therapeutic options. The identification of specific substrates for tumour proteases in complex biological samples is challenging, but proteomic screens for proteases/substrate interactions are currently experiencing impressive progress. Such proteomic screens include peptide‐based libraries, differential isotope labelling in combination with MS, quantitative degradomic analysis of proteolytically generated neo‐N‐termini, monitoring the degradation of exogenous reporter peptides with MS, and activity‐based protein profiling. In the present article, we summarize and discuss the current status of proteomic techniques to identify tumour‐specific protease‐substrate interactions for functional protease profiling. Thereby, we focus on the potential diagnostic use of the respective approaches.
High mobility group protein AT‐hook 1 (HMGA1) is associated with the development of androgen independence in prostate cancer cells
Authors: Takeuchi Ichiro , Takaha Natsuki , Nakamura Terukazu , Hongo Fumiya , Mikami Kazuya , Kamoi Kazumi , Okihara Koji , Kawauchi Akihiro , Miki Tsuneharu
Published: December 2011

BACKGROUND

We previously reported that the level of high mobility group protein AT‐hook 1 (HMGA1) is low in androgen‐dependent prostate cancer (PCa) cells (LNCaP), but is high in androgen‐independent PCa cells (DU145 and PC‐3) and that HMGA1 is a strong candidate gene playing a potential role in the progression of PCa. These findings have prompted us to evaluate the effect of HMGA1 on developing androgen independency, which is associated with the progression of PCa.

METHODS

Expression of HMGA1 in PCa cells and mouse tissues was examined by Western blot. In order to examine the effect of HMGA1 on cell growth under androgen‐deprived condition, we transfected HMGA1 into LNCaP cells, and siRNA into both DU145 and PC‐3 cells, respectively.

RESULTS

Androgen‐deprivation induced an increase in the level of HMGA1 in LNCaP cells in vitro and in vivo, but did not in normal prostate tissue. Overexpression of HMGA1 maintained the cell growth of LNCaP under androgen‐deprived condition. Furthermore, knockdown of HMGA1 suppressed the cell growth of DU145 and PC‐3.

CONCLUSIONS

These data suggest that elevated expression of HMGA1 is associated with the transition of PCa cells from androgen‐sensitive to androgen‐independent growth and plays a role in the cell growth of androgen‐independent PCa cells. Prostate 72:1124–1132, 2012. © 2011 Wiley Periodicals, Inc.
Androgen receptor overexpression alters binding dynamics of the receptor to chromatin and chromatin structure
Authors: Urbanucci Alfonso , Marttila Saara , Jänne Olli A. , Visakorpi Tapio
Published: December 2011

BACKGROUND

Castration‐resistant prostate cancers (CRPCs) overexpress often androgen receptor (AR). Here, we investigated the effect of AR overexpression on the dynamics of AR loading and RNA polymerase II (RNA Pol II) recruitment to chromatin. Acetylation of histone 3 (AcH3) on lysines 9 and 14 (K9 and K14) was also studied.

METHODS

We used an LNCaP‐based AR overexpression cell line model that includes a control line and two sublines, LNCaP‐ARmo and LNCaP‐ARhi, which overexpress AR twofold to threefold and fourfold to fivefold, respectively. Cells were exposed to 1 or 100 nM of dihydrotestosterone (DHT). Chromatin immunoprecipitation (ChIP) on the promoters and enhancers of prostate specific antigen (PSA) and transmembrane protease, serine 2 (TMPRSS2) genes was performed. qRT‐PCR was used to measure the levels of PSA and TMPRSS2 transcripts.

RESULTS

Upon stimulation with 1 nM DHT, AR and RNA Pol II were recruited onto PSA and TMPRSS2 enhancer regions to a greater extent (P < 0.05) in AR‐overexpressing cells compared to control cells. The difference in AR loading between the control and AR‐overexpressing cells was abolished by a higher DHT concentration. The ratio of AcH3/H3 was increased in AR‐overexpressing cells. The induction of transcription of PSA and TMPRSS2 occurred earlier in the AR‐overexpressing cells.

CONCLUSIONS

Our findings suggest that the levels of AR potentiate the recruitment of the AR, as well as components of the basic transcription machinery, to chromatin and affect the acetylation of histones in the presence of low levels of androgens. These changes result in enhanced gene transcription of AR target genes. Prostate 72:1223–1232, 2012. © 2011 Wiley Periodicals, Inc.
TP53INP1 as new therapeutic target in castration‐resistant prostate cancer
Authors: Giusiano Sophie , Baylot Virginie , Andrieu Claudia , Fazli Ladan , Gleave Martin , Iovanna Juan Lucio , Taranger‐Charpin Colette , Garcia Stéphane , Rocchi Palma
Published: December 2011

BACKGROUND

Prostate cancer (PC) is one of the most common malignancies in industrialized countries, and the second leading cause of cancer‐related death in the United States. We recently showed that over‐expression of tumor protein 53‐induced nuclear protein 1 (TP53INP1), a cell stress response protein, is a worse prognostic factor in PC, particularly predictive of biological cancer relapse. Moreover, treatment of castration‐sensitive (CS) LNCaP tumor cells with a TP53INP1 antisense oligonucleotide (TP53INP1 ASO) inhibits proliferation and induces apoptosis. The aim of this study was to investigate variations of TP53INP1 expression in PC during androgen withdrawal therapy and in castration‐resistant prostate cancer (CRPC).

METHODS

Quantitative measurements of immunohistochemical expression of TP53INP1 using high‐throughput densitometry, assessed on digitized microscopic tissue micro‐array images were correlated with hormone therapy (HT) status in human PC. Northern blot analysis of TP53INP1 after castration was performed in LNCaP xenograft. Treatment of CR C4‐2 tumor cells in vitro with TP53INP1 ASO was analyzed. We also analyzed the effect of TP53INP1 ASO treatment in vivo on tumor xenograft growth.

RESULTS

TP53INP1 protein expression decreases during HT and increases after HT in human CRPC. TP53INP1 mRNA increases significantly in CR tumors of LNCaP xenograft. Moreover, treatment of CR C4‐2 cells with TP53INP1 ASO downregulates TP53INP1 protein level, inhibits proliferation, and induces apoptosis. Finally, in vivo, TP53INP1 ASO treatment significantly inhibits the tumoral progression of CR C4‐2 xenograft and enhances docetaxel cytotoxicity.

CONCLUSIONS

These results suggest that TP53INP1 could be considered as a relevant‐specific target for molecular therapy of CRPC. Prostate 72:1286–1294, 2012. © 2011 Wiley Periodicals, Inc.
Variations in the exome of the LNCaP prostate cancer cell line
Authors: Spans Lien , Atak Zeynep Kalender , Van Nieuwerburgh Filip , Deforce Dieter , Lerut Evelyne , Aerts Stein , Claessens Frank
Published: December 2011

BACKGROUND

The LNCaP cell line is widely used as a model for prostate cancer. However, information on protein‐changing mutations, genetic heterogeneity and genetic (in)stability is largely lacking for these cells.

METHODS

Next‐generation sequencing of the LNCaP exome revealed many single nucleotide variants (SNVs). To help identify the mutations that are most likely drivers of the oncogenic process, we developed an in silico protocol, which can be adapted for other exome analyses.

RESULTS

We detected 1,802 non‐synonymous SNVs and 218 small insertions and deletions in the LNCaP exome. We confirm the known mutations in the androgen receptor and the PTEN gene, but most other mutations remained undescribed until now. The presence of 38 out of 42 SNVs was confirmed in monoclonal as well as in polyclonal LNCaP derivatives. Moreover, most variants were also detectable in LNCaP mRNA.

CONCLUSIONS

We provide an extensive database of genetic variations in the protein‐coding part of the genome of LNCaP cells, which should be taken into consideration when using LNCaP cells or its derivatives as models for prostate cancer. From the analysis of several LNCaP‐derived cultures and clones, we can confirm that the cell line is heterozygous for a large number of variants and that both the variant and the wild‐type allele can be simultaneously expressed as mRNA. The fact that the SNVs in the E‐cadherin, CDK4, Notch1, and PlexinB1 genes are absent in some of the subclones strongly indicates a degree of genetic instability. Prostate 72:1317–1327, 2012. © 2011 Wiley Periodicals, Inc.
Cediranib inhibits both the intraosseous growth of PDGF D‐Positive prostate cancer cells and the associated bone reaction
Authors: Najy Abdo J. , Jung Young Suk , Won Joshua J. , Conley‐LaComb M. Katie , Saliganan Allen , Kim Chong Jai , Heath Elisabeth , Cher Michael L. , Bonfil R. Daniel , Kim Hyeong‐Reh Choi
Published: December 2011

BACKGROUND

The major cause of death in prostate cancer (PCa) cases is due to distant metastatic lesions, with the bone being the most prevalent site for secondary colonization. Utilization of small molecule inhibitors to treat bone metastatic PCa have had limited success either as monotherapies or in combination with other chemotherapeutics due to intolerable toxicities. In the current study, we developed a clinically relevant in vivo intraosseous tumor model overexpressing the platelet‐derived growth factor D (PDGF D) to test the efficacy of a newly characterized vascular endothelial growth factor receptor (VEGFR)/PDGFR inhibitor, cediranib (also called AZD2171).

METHODS

An intratibial‐injection model was established utilizing DU145 cells with or without increased PDGF D expression. Tumor‐bearing mice were treated by daily gavage administration of cediranib and/or weekly i.p. injection of docetaxel for 7 weeks. Tibiae were monitored by in vivo/ex vivo X‐rays and histomorphometry analysis was performed to estimate tumor volume and tumor‐associated trabecular bone growth.

RESULTS

Cediranib reduced intraosseous growth of prostate tumors as well as tumor‐associated bone responses. When compared to the standard chemotherapeutic agent docetaxel, cediranib exhibited a stronger inhibition of tumor‐associated bone response. The efficacy of cediranib was further enhanced when the drug was co‐administered with docetaxel. Importantly, the therapeutic benefits of cediranib and docetaxel are more prominent in intraosseous prostate tumors overexpressing PDGF D.

CONCLUSION

These novel findings support the utilization of cediranib, either alone or in combination with docetaxel, to treat bone metastatic PCa exhibiting PDGF D expression. Prostate 72:1328–1338, 2012. © 2011 Wiley Periodicals, Inc.
Interface properties of OFETs based on an air‐stable n‐channel perylene tetracarboxylic diimide semiconductor
Authors: Lüttich Franziska , Lehmann Daniel , Friedrich Marion , Chen Zhihua , Facchetti Antonio , Borczyskowski Christian von , Zahn Dietrich R. T. , Graaf Harald
Published: December 2011

In this study, several experimental techniques were employed to gain insights into the molecular interactions at the interfaces in organic field‐effect transistors (OFETs). A self‐assembled monolayer (SAM) was applied to the gate insulator to influence the interactions at the interface. Macroscopic electrical measurements, microscopic potentiometry, absorption/luminescence spectroscopy, and ellipsometry are combined to study top‐contact OFETs based on an air‐stable n‐channel perylene derivative. They show clearly the advantage and capability of local electrical investigations compared to DC electrical characterization. The DC electrical measurements provide an improvement of the electron mobilities within the channel and unchanged contact resistances (within the error bars). Only the potentiometry allowed a deeper insight: It reveals a small decrease of the source contact resistance and a drain bias dependence of the mobility, which decreases due to prior hydrophobization of the SiO2 gate insulator. This is attributed to different charge carrier trap concentrations and injection barriers in the organic semiconductor near the dielectric interface caused by diffused water which is discussed in detail. The optical absorption/luminescence spectroscopy and ellipsometry indicate an unchanged ordered molecular arrangement with a molecular tilt angle of (33 ± 4)° with respect to the dielectric surface and rather weak intermolecular interaction for the devices with treated and untreated SiO2.
Carrier dynamics under two‐ and single‐photon excitation in bulk GaN
Authors: Ščajev Patrik , Jarašiūnas Kęstutis , Okur Serdal , Özgür Ümit , Morkoç Hadis
Published: December 2011

Carrier diffusion and recombination features in freestanding 200 µm thick GaN were studied using light‐induced transient grating, time‐resolved free‐carrier absorption, and photoluminescence techniques. Under two‐photon excitation (527 nm, 8 ps), in‐plane carrier diffusion paved the way for determining the hole and ambipolar carrier diffusion coefficients (Dh = 0.8 and Da = 1.6 cm2/s) and their temperature dependence. The nearly inverse correlation between the diffusivity and carrier lifetime in the 80–800 K range was ascribed to nonradiative carrier recombination at the extended defects. Very low density of dislocations, in mid‐105 cm−2, provided extremely long lifetime values, up to 40 ns at 300 K and 120 ns at 800 K. Under single‐photon excitation (267 nm, 100 fs), the initial very fast transient of photoluminescence decay at 3.4 eV was described by carrier diffusion normal to the surface, reabsorption of emission, and surface recombination. The nonequilibrium processes in the entire 80–800 K range can be reliably analyzed by a free electron–hole model.
Semipolar GaInN quantum well structures on large area substrates
Authors: Scholz Ferdinand , Schwaiger Stephan , Däubler Jürgen , Tischer Ingo , Thonke Klaus , Neugebauer Silvio , Metzner Sebastian , Bertram Frank , Christen Jürgen , Lengner Holger , Thalmair Johannes , Zweck Josef
Published: December 2011

In order to deposit semipolar GaN layers on foreign substrates while still starting the growth along the c‐direction, we have etched trenches into r‐plane and n‐plane sapphire wafers. The GaN MOVPE growth then starts from c‐plane‐like sidewalls of these trenches, eventually leading to semipolar $\{ 11{\bar {2}}2\} $ and $\{ 10{\bar {1}}1\} $ surfaces with very good properties. GaInN quantum wells grown on such surfaces show very uniform properties on $\{ 10{\bar {1}}1\} $ surfaces, but still reflect the stripe geometry on $\{ 11{\bar {2}}2\} $ surfaces by a slightly larger In uptake at the stripe coalescence regions.

magnified image

Semipolar GaN stripes with top $\{ 10{\bar {1}}1\} $ surface grown on grooved n‐plane sapphire.
Ground state switching in InGaN/GaN quantum dot molecules
Authors: Schulz Stefan , O'Reilly Eoin P.
Published: December 2011

We present a detailed analysis of the electronic properties of In0.25Ga0.75N/GaN quantum dot (QD) molecules using an sp3 tight‐binding model, including strain and built‐in fields. The influence of the interdot separation is studied in detail. Our analysis reveals that, even if we assume two identical QDs, the molecular description of bonding and anti‐bonding states breaks down for the single‐particle states. This behavior originates from two effects, the strain field and the built‐in potential. The strain field interactions between the two QDs suppress the ability to form bonding and anti‐bonding hole states. Additionally, the built‐in potential along the c‐axis leads with increasing separation to a ground state switching between the two QDs. This is related to the behavior of the built‐in potential in an isolated QD, where the potential drops back quickly toward zero, and may even change sign outside a strained c‐plane QD.
Density‐functional‐based prediction of a spin‐ordered open‐shell singlet in an unpassivated graphene nanofilm
Authors: Pederson Mark R.
Published: December 2011

I briefly review some of the methods, developed at the Naval Research Laboratory, that were used in a variety of collaborations with the Frauenheim group. To aid experimental understanding at that time, we attempted to predict equilibrium structures and also provide calculated vibrational spectra for direct comparison to experimental measurements. Most of our work was on carbon‐based systems with a heavy focus on fullerenes and diamond. More recently another pure carbon compound, graphene, has received much attention. In this paper, I present applications of density‐functional‐based spectroscopic techniques to a single graphene nanofilm and confirm that spin polarization can occur at the edge states. However, antiferromagnetic ordering is preferred over ferromagnetic ordering. By extracting a Heisenberg Hamiltonian from the calculations the energy of the various spin multiplets can be estimated through diagonalization of this Hamiltonian. The Perdew–Burke–Ernzerhof–density‐functional theory (PBE‐DFT) results indicate that both antiferromagnetic and ferromagnetic graphene structures are vibrationally stable but that the lowest‐energy eigenstate of the system is an open‐shell singlet with a gap of approximately 14 cm−1 to the open‐shell triplet state. Consistent with recent work that stabilizes graphene nanofilms via adsorption onto metal surfaces the density functional results presented here show that small graphene nanofilms, while vibrationally stable, will exothermically form previously identified fullerene structures. Vibrational excitation spectra for the 54‐atom graphene and fullerene structures are calculated to provide spectroscopic means for distinguishing between the two structures.
Transparent and Conducting Graphene–RNA‐Based Nanocomposites
Authors: Sharifi Faranak , Bauld Reg , Ahmed M. Shafiq , Fanchini Giovanni
Published: December 2011

Ribonucleic acid (RNA) is proposed as a nonionic surfactant for the efficient exfoliation of graphite in thin flakes of few‐layer graphene and the subsequent preparation of transparent and conducting thin films. Parameters such as the type of RNA used and the size of starting graphite flakes are demonstrated to be essential for obtaining RNA–graphene thin films of good quality. A model explaining the exfoliation of graphene by RNA in water is suggested. A number of post‐ and predeposition treatments (including thermal annealing, functionalization of the films, and the preoxidation of graphite) are critical to improve the performance of graphene–RNA nanocomposites as transparent conductors. The study establishes an ideal link between RNA and graphene, the fundamental building blocks for nanobiology and carbon‐based nanotechnology.
Efficient Gene Delivery to Mesenchymal Stem Cells by an Ethylenediamine‐Modified Polysaccharide from Mulberry Leaves
Authors: Deng Wen‐Wen , Cao Xia , Wang Miao , Yang Yan , Su Wei‐Yan , Wei Ya‐Wei , Ou‐Yang Zhen , Yu Jiang‐Nan , Xu Xi‐Ming
Published: December 2011

This study investigates the use of a natural polysaccharide isolated from mulberry leaves as a nonviral gene vector. Ethylenediamine is chemically grafted to the backbone of a polysaccharide from mulberry leaves (MPS) to acquire nucleic acid binding affinity. A particle‐size observation indicates that the cationic mulberry leaf polysaccharide (CMPS) can efficiently combine with plasmid transforming growth factor β1 (TGF‐β1) to form nanoscaled particles. In addition, the electrophoresis assay indicates a retarded plasmid migration when the CMPS/pTGF‐β1 weight ratio is increased to 30:1. The in vitro cell transfection experiment is performed based on bone marrow mesenchymal stem cells (MSCs) derived from rat femurs and tibias, and the findings reveal that the complex with a CMPS/pTGF‐β1 weight ratio of 50:1 exhibits the highest cell transfection effect, which is significantly higher than that of branched poly(ethyleneimine) (PEI) (25 kDa; p = 0.001, Student's t‐test) and slightly higher than Lipofectamine 2000. Moreover, the cytotoxicity assay also demonstrates that all of these tested complexes and the plasmid TGF‐β1 are nontoxic to mesenchymal stem cells (MSCs). The results of the living cell imaging confirm that more of the CMPS/plasmid TGF‐β1 nanoparticles can be taken up and at a faster rate by the MSCs than by the positive control Lipofectamine 2000; these data are consistent with the transfection efficiency data. Together, these results suggest that the CMPS/pTGF‐β1 nanoparticle can potentially be developed into a promising alternative for the transfer of therapeutic genes into cells.
Unconventional Layer‐by‐Layer Assembly: Surface Molecular Imprinting and Its Applications
Authors: Xu Huaping , Schönhoff Monika , Zhang Xi
Published: December 2011

Layer‐by‐layer assembly (LbL) is a rich, versatile, and powerful technique for fabricating multilayer thin films with controlled architecture and functions. Singly charged, uncharged, or water‐repellent molecules cannot be used directly in conventional LbL assembly. This problem can be solved with unconventional LbL methods, by employing the preassembly of building blocks in solution and the use of these assemblies for LbL formation at the interface. This Concept summarizes different methods of unconventional LbL assembly, including electrostatic complex formation, hydrogen‐bonded complexes, block‐copolymer micelles, and π–π interaction complexes. These preassembly treatments endow the building blocks with enhanced abilities for advanced functionality, in particular, surface molecular imprinting, a new concept emerging from unconventional LbL. Molecular imprinting approaches are thus conceptually described based on different types of interactions and their great potential in applications is demonstrated by examples such as selective surface patterning and selective filtration.
Die Visualisierung des Kraftflusses in Stahlbaukonstruktionen
Authors: Moldenhauer Herbert
Published: December 2011

Kraftflüsse sind in vielen Lehrbüchern des Stahl‐ und Maschinenbaus zur Veranschaulichung der Bauteilbeanspruchung dargestellt. Obwohl der Kraftflussbegriff umstritten und nicht näher definiert ist, assoziiert der Leser damit meist eine Analogie zu Stromlinienbildern aus der Hydromechanik. Vergleicht man die differentielle Kontinuitätsgleichung der Hydromechanik mit den differentiellen Gleichgewichtsbedingungen der Statik, so gibt es jedoch eine termweise Übereinstimmung. Der Geschwindigkeitsvektor entspricht einem Kraftflussvektor. Die integrierten Kraftflussvektoren liefern die Kraftflusslinien. Diese verlaufen zwischen dem Ort der Krafteinleitung und dem Ort des reaktiven Lagers. Lastfreie Ränder werden von den Kraftlinien nur tangiert.

Der Aufwand für die Visualisierung der Kraftflusslinien ist gering. Zwischen den Kraftflussvektoren und den Spannungskomponenten aus FEM‐Programmen bestehen einfache Beziehungen. Die Integration der vektoriellen Richtungsfelder kann mit grafischer Standardsoftware zu Kraftflusslinien durchgeführt werden. Der Einsatz einer Spezialsoftware ist an keiner Stelle erforderlich. An zahlreichen Beispielen wird die quantitative Erfassung des Kraftflusses demonstriert und ihr Nutzen insbesondere für den Stahlbau aufgezeigt.

Load path visualization for steel constructions. Load path sketches illustrate the load distribution in structural components and can be found in many engineering textbooks. Although there is no stringent definition for a load path, the reader associates an analogy to streamlines from hydromechanics. The law of conservation of mass and the static equations of equilibrium show a term‐wise agreement. Thus, the fluid flow velocity vector corresponds to a load path vector. By integrating these directional fields, one obtains the streamlines and load path lines. A load path starts at the point of an applied load and ends at a supporting point reacting the applied load. Free boundaries are touched but not crossed by the load path.

There is little effort to visualize the load path. Due to simple relations between load path vectors and stress components from FEM‐programs, integration of the directional vector fields is possible with standard graphical software, thus resulting in load path lines. No special software is ever needed. Numerous examples will show the practical application of the load path concept and the special use for steel constructions.
Biege‐ und Biegedrillknicknachweise nach Eurocode 3 anhand von Berechnungen nach Theorie 2. Ordnung
Authors: Feldmann Markus , Sedlacek Gerhard , Wieschollek Matthias , Szalai József
Published: December 2011

Walzprofile und ähnlich gestaltete geschweißte Profile haben eine Haupttragebene, die möglichst voll ausgenutzt werden soll, indem Stabilitätsversagen quer zur Haupttragebene verhindert wird.

DIN EN 1993‐1‐1 [2] behandelt Stabilitätsnachweise quer zur Haupttragebene inform von Biegeknick‐ oder Biegedrillknicknachweisen nach zwei möglichen Verfahren: dem Verfahren mit Anwendung der Theorie 2. Ordnung durch Vorgabe von geometrischen Ersatzimperfektionen, das allgemeingültig sein sollte, und dem Verfahren mit Knick‐ und Biegedrillknickbeiwerten, die für bestimmte häufige Fälle objektorientiert angewendet werden können.

Der vorliegende Beitrag behandelt die Nachweise mit Theorie 2. Ordnung mit geometrischen Ersatzimperfektionen, die entsprechend DIN EN 1993‐1‐1 [2] allgemeingültig als Eigenformen bei Ausweichen aus der Haupttragebene definiert sind. Zur Bestimmung bietet sich eine Rechnerunterstützung an, die nicht nur die modalen Verschiebungen, sondern auch die modalen Biegemomente in den maßgebenden Gurten des Querschnitts liefert. Dadurch werden die Nachweise übersichtlich und einfach und münden in einen Nachweis des Ausnutzungsgrades in der Haupttragebene, der durch einen Faktor f infolge der Biegemomente aus der Haupttragebene vergrößert wird. Beispiele aus der Praxis erläutern die überraschend einfache Anwendung.

Flexural and lateral torsional buckling checks of steel frames according to Eurocode 3 using 2nd order analysis. Sections of rolled profiles or similar welded profiles have due to their strong axis an in‐plane‐resistance that should be exploited by preventing out‐of‐plane stability failure about the weak axis. DIN EN 1993‐1‐1 [2] gives rules for out‐of‐plane stability checks (lateral flexural or lateral torsional buckling) that can be performed according to one of the following methods: the method using 2nd order analysis for which equivalent geometric imperfection are defined and that is considered as a generic method, and the method with member checks using flexural or lateral torsional buckling curves, that have been determined for frequent cases (object‐oriented method).

This contribution treats out‐of‐plane stability checks using 2nd order analysis with equivalent geometric imperfections, that have been defined in DIN EN 1993‐1‐1 [2] as elastic buckling modes. To determine these functions computer‐assistance is required, that gives not only the modal displacements, but also the modal bending moments for the relevant flanges of the profiles.

The use of out‐of‐plane modal bending moments makes the assessments clear and simple. They lead to the assessment of the in‐plane utilisation rates, which are enhanced by a factor f due to the out‐of‐plane bending moments. Worked examples from practical applications illustrate the surprising simplicity of use.
Zum Einsatz von Betondübeln im Verbundbau (Teil 2) – Nichtruhende Beanspruchung
Authors: Mangerig Ingbert , Wagner Robert , Burger Sascha , Wurzer Otto , Zapfe Cedrik
Published: December 2011

Beim Einsatz von Betondübeln in Bauwerken unter nichtruhenden Beanspruchungen sind hinreichende Erkenntnisse zum Ermüdungsverhalten erforderlich. Auf der Grundlage experimenteller Untersuchungen wurde unter Verwendung von Rechenansätzen des örtlichen Konzepts ein Berechnungsprinzip erarbeitet, welches einen zuverlässigen Nachweis gegen Versagen durch Werkstoffermüdung gestattet. Der vorliegende Beitrag schließt an den ersten, im Dezember 2011 erschienen Beitrag [28] an.

The application of concrete dowels in composite constructions (Part 2) – Dynamic loading. Substantial understanding of fatigue properties of concrete dowels promotes applications of such composite structures in a non stationary load environment. Hence a calculation procedure was developed based on push‐out tests, beam tests and numerical analysis of peak stress in order to provide a safe design against fatigue failure. This paper follows the first part, which was published at the end of 2011 [28].
Physicochemical properties of new starches isolated from Dioscorea opposita Thunb. bulbils
Authors: Zhou Hongying , Wang Jianhua , Fang Xinsheng , Sun Yinshi , Dou Xinghai
Published: December 2011

Morphological, crystal, and physicochemical properties, such as AM content, swelling power, solubility, and pasting properties of starches isolated from three different Shanyaodou (the bulbils of Dioscorea opposita Thunb., named Huaishanyao, Xichangmaoshanyao, and Maoshanyao, respectively) were investigated. The yield of starches was in the range 12.5–20.8% (dry starch/fresh whole bulbils). The AM content of Shanyaodou starches ranged from 33.3 to 36.7%. The shape of the three bulbils starch granules varied from round to oval or elliptic. The mean particle diameter of starch granules varied from 20.17 to 26.34 µm. Shanyaodou starches exhibited a C‐type XRD pattern and the degree of crystallinity was in the range 31.0–34.9%. The pasting peak viscosity, trough viscosity, and final viscosity of Shanyaodou starches ranged from 291.1 to 414.7, 210.8 to 227.0, and 350.0 to 359.2 rapid visco units (RVU), respectively, and the pasting temperature was in the range 83.6–87.3°C. The results showed that some of the Shanyaodou starches could be used in foods production as a thickening agent. The simple method of extraction and the high yield of starch from Shanyaodou might be attractive for production of Shanyaodou starch.
A study of integral sliding mode control with input constraint for engine idling‐speed control
Authors: Zhang Yang , Kurihara Nobuo
Published: December 2011

This paper proposes an approach to the provision of sliding mode control (SMC) with input constraint for engine idling‐speed control. The aim of this experiment is to improve the stability of the system against disturbances such as fuel purges and torque loads. A steady‐state error occurs because, in practice, the control input is restricted when an integral type SMC is employed to achieve stabilization. A modification to this approach is proposed that effectively uses compensation gain and variable switching gain. The compensation gain is derived from the control input difference, and the variable switching gain is described as an exponential function of the hyperplane. A mean‐value engine model with dead time and disturbances is constructed in Matlab/Simulink. The simulation results show that the issue relating to steady‐state deviation can be successfully solved with regard to disturbances having bias power; also, robustness is maintained during engine speed fluctuations. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Multiple‐frame precoding and multi‐D mapping for BICM over ergodic NAF relay channels
Authors: Rodríguez Leonardo Jiménez , Tran Nghi H. , Le‐Ngoc Tho
Published: December 2011

This paper proposes the idea of precoding over multiple cooperative frames with multi‐dimensional (multi‐D) mapping for a bit interleaved coded modulation system over an ergodic non‐orthogonal amplify‐and‐forward (NAF) half‐duplex single‐relay channel. The benefits of multiple‐frame precoding and multi‐D labeling are analyzed in two different regions: the error‐floor region to exploit diversity and the turbo pinch‐off region for near‐capacity performance. In the error‐floor area, it is shown that the diversity gain function of the considered system is th power of that of uncoded cooperative systems, where Nf is the number of precoded cooperative frames and dH is the minimum Hamming distance of the outer code. To optimize the asymptotic coding gain, it is then shown that the source and relay must transmit orthogonally for best asymptotic performance. In the turbo pinch‐off region, we demonstrate that the proposed system concatenated with a simple outer binary code can be employed to achieve near‐capacity performance. Using union bounding techniques, we show that the optimal multi‐D labeling for NAF relaying shall maximize the average Euclidean distance between all pairs in the multi‐D rotated constellation whose labels differ in only 1 bit. The extrinsic information transfer charts are then used to match the outer code, the multi‐D mapping, and the precoder. It is demonstrated that the proposed system is also promising for NAF relaying in the turbo pinch‐off region, in the sense that it can operate below the achievable rate achieved by a conventional coded modulation scheme. Copyright © 2011 John Wiley & Sons, Ltd.
Morphogenesis in sea urchin embryos: linking cellular events to gene regulatory network states
Authors: Lyons Deirdre C. , Kaltenbach Stacy L. , McClay David R.
Published: December 2011

Gastrulation in the sea urchin begins with ingression of the primary mesenchyme cells (PMCs) at the vegetal pole of the embryo. After entering the blastocoel the PMCs migrate, form a syncitium, and synthesize the skeleton of the embryo. Several hours after the PMCs ingress the vegetal plate buckles to initiate invagination of the archenteron. That morphogenetic process occurs in several steps. The nonskeletogenic cells produce the initial inbending of the vegetal plate. Endoderm cells then rearrange and extend the length of the gut across the blastocoel to a target near the animal pole. Finally, cells that will form part of the midgut and hindgut are added to complete gastrulation. Later, the stomodeum invaginates from the oral ectoderm and fuses with the foregut to complete the archenteron.

In advance of, and during these morphogenetic events, an increasingly complex input of transcription factors controls the specification and the cell biological events that conduct the gastrulation movements. WIREs Dev Biol 2012, 1:231–252. doi: 10.1002/wdev.18

This article is categorized under:

Gene Expression and Transcriptional Hierarchies > Gene Networks and Genomics

Early Embryonic Development > Gastrulation and Neurulation

Comparative Development and Evolution > Model Systems
Internalizing the vegetal cell mass before and during amphibian gastrulation: vegetal rotation and related movements
Authors: Winklbauer Rudolf , Damm Erich W.
Published: December 2011

The movement of the prospective mesoderm and endoderm to the interior of the amphibian embryo starts in the vegetal cell mass well before the onset of overt gastrulation. By an animally directed movement of cells, the vegetal mass constricts its outer part and expands its inner region including the blastocoel floor, in a process of pregastrulation emboly. Further internalization of the vegetal region has been studied in the Xenopus embryo. At the onset of gastrulation, vegetal rotation sets in at the periphery of the vegetal cell mass, first dorsally and then spreading laterally and ventrally. It consists of an intense inward surging of cells due to active cell rearrangements that can be observed in explants of the vegetal cell mass. In its course, the blastocoel floor expands further and becomes apposed to the blastocoel roof. The boundary between apposed floor and roof forms Brachet's cleft. Another effect of vegetal rotation is the downward and inward movement of the mesodermal marginal zone, constituting the first phase of involution. Together, the upward and outward movement of the peripheral vegetal mass and the downward and inward translocation of the marginal zone lead to an apparent rotation of the whole peripheral region of the gastrula. Vegetal rotation continues to contribute to endoderm internalization to near the end of gastrulation. WIREs Dev Biol 2012, 1:301–306. doi: 10.1002/wdev.26

This article is categorized under:

Early Embryonic Development > Gastrulation and Neurulation
Axillary and Supraclavicular Recurrences are Rare after Axillary Lymph Node Dissection in Breast Cancer
Authors: Siponen Elina T. , Vaalavirta Leila A. , Joensuu Heikki , Leidenius Marjut H. K.
Published: December 2011

Background

This study was designed to evaluate the incidence of and risk factors for axillary recurrence (AR) and supraclavicular recurrence (SR) in breast cancer patients with axillary lymph node dissection.

Methods

The study was based on 1,180 patients with unilateral invasive breast cancer operated between January 2000 and December 2003. The median duration of follow‐up was 78 months.

Results

The 7‐year AR incidence was 0.7% and SR incidence was 1.3%. Twelve of the 14 SR patients and 4 of the 8 AR patients had concomitant distant recurrences. No risk factors for AR were identified. Histological tumor grade III as well as estrogen and progesterone negativity were risk factors for SR. SR, but not AR, was an independent risk factor for poor breast cancer‐specific survival [hazard ratio, 10.116; P < 0.0001]. Among N1 patients, the extent of radiotherapy (RT) had no influence on regional recurrences. Among N2–N3 patients, the 7‐year regional recurrence rates were 34.3% in patients without RT, 0% in patients with local RT, and 1.2% in patients with locoregional RT (P < 0.0001).

Conclusions

AR and SR are rare events that often are detected concomitantly with distant metastases. SRs are associated with aggressive disease and poor survival. Our results also suggest that regional RT reduces regional recurrences in N2–N3 patients but not in N1 patients, but the retrospective, nonrandomized study setting renders this conclusion as uncertain.
Optimum leaf size predicted by a novel leaf energy balance model incorporating dependencies of photosynthesis on light and temperature
Authors: Okajima Yuki , Taneda Haruhiko , Noguchi Ko , Terashima Ichiro
Published: December 2011

To clarify relationships between leaf size and the environment variables, we constructed an energy balance model for a single leaf incorporating Leuning's stomatal conductance model and Farquhar's leaf photosynthesis model. We ran this model for various environmental conditions paying particular attention to the leaf boundary layer. The leaf size maximizing the rate of photosynthesis per unit leaf area (A) at a high irradiance differed depending on the air temperature. In warm environments, A increased with decrease in leaf size, whereas in cool environments, there was the leaf size maximizing A. With the increase in leaf size, the CO2 concentration inside the leaf (Ci) decreased and the leaf temperature increased, both due to lower boundary layer conductance. At low air temperatures, the negative effect of low Ci on A in large leaves was compensated by the increase in leaf temperature towards the optimum temperature for A. This balance determined the optimum leaf size for A at low air temperatures. With respect to water use efficiency, large leaves tended to be advantageous, especially in cool environments at low‐to‐medium irradiances. Some temperature‐dependent trends in leaf size observed in nature are discussed based on the present results.
Pulmonary perfusion imaging using MRI: clinical application
Authors: Ley Sebastian , Ley-Zaporozhan Julia
Published: December 2011

Background

Lung perfusion is one of the key components of oxygenation. It is hampered in pulmonary arterial diseases and secondary due to parenchymal diseases.

Methods

Assessment is frequently required during the workup of a patient for either of these disease categories.

Results

This review provides insight into imaging techniques, qualitative and quantitative evaluation, and focuses on clinical application of MR perfusion.

Conclusion

The two major techniques, non-contrast-enhanced (arterial spin labeling) and contrast-enhanced perfusion techniques, are discussed.
Beyond Absenteeism: Father Incarceration and Child Development
Authors: Geller Amanda , Cooper Carey E. , Garfinkel Irwin , Schwartz-Soicher Ofira , Mincy Ronald B.
Published: December 2011

High rates of incarceration among American men, coupled with high rates of fatherhood among men in prison, have motivated recent research on the effects of parental imprisonment on children’s development. We use data from the Fragile Families and Child Wellbeing Study to examine the relationship between paternal incarceration and developmental outcomes for approximately 3,000 urban children. We estimate cross-sectional and longitudinal regression models that control not only for fathers’ basic demographic characteristics and a rich set of potential confounders, but also for several measures of pre-incarceration child development and family fixed effects. We find significant increases in aggressive behaviors and some evidence of increased attention problems among children whose fathers are incarcerated. The estimated effects of paternal incarceration are stronger than those of other forms of father absence, suggesting that children with incarcerated fathers may require specialized support from caretakers, teachers, and social service providers. The estimated effects are stronger for children who lived with their fathers prior to incarceration but are also significant for children of nonresident fathers, suggesting that incarceration places children at risk through family hardships including and beyond parent-child separation.