bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructural characteristics of spermatogenesis in Pallas's mastiff bat, Molossus molossus (Chiroptera: Molossidae)
Authors: Beguelini Mateus R. , Taboga Sebastião R. , Morielle‐Versute Eliana
Published: January 2012

Despite the large number of species, their wide distribution, and unique reproductive characteristics, Neotropical bats have been poorly studied, and important aspects of the reproduction of these animals have not been elucidated. We made an ultrastructural analysis of spermatogenesis in Molossus molossus (Molossidae). The process of spermatogonial differentiation is similar to that found in other bats and is also relatively similar to that of Primates, with three main spermatogonia types: Ad, Ap, and B. Meiotic divisions proceed similarly to those of most mammals, and spermiogenesis is clearly divided into 12 steps, in the middle of the range known for bats (9–16 steps). Formation of the acrosome is similar to that known from other mammals; however, the ultrastructure of spermatozoa was found to have unique characteristics, including many wavy acrosomal projections on its surface, which seems to be specific for the family Molossidae. Comparing the ultrastructure of the spermatozoon of M. molossus with other bats already study, we observed that three characters vary: morphology of the outer dense fibers, of the perforatorium, and of the spermatozoon head. The great similarity of morphological characters between M. molossus and Platyrrhinus lineatus suggests that M. molossus is more closely related to the Phyllostomidae than to the Rhinolophidae and the Vespertilionidae. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.
Synthesis of [14C]boceprevir, [13C3]boceprevir, and [D9]boceprevir, a hepatitis C virus protease inhibitor
Authors: Ren Sumei , Royster Pernilla , Lavey Carolee , Hesk David , McNamara Paul , Koharski David , Truong Van , Borges Scott
Published: January 2012

Boceprevir is a hepatitis C virus (HCV) NS3 protease inhibitor for HCV treatment. [14C]Boceprevir (SCH 503034, trade name Victrelis) was synthesized from K14CN in 11 steps with an overall yield of 16.4%. [13C3]Boceprevir was synthesized in 16 steps with a 2.5% overall yield. The carbon‐13 in the molecule was distributed along the peptide chain. [D9]Boceprevir was synthesized from [D9]‐t‐butylamine in four steps with an overall yield of 69%. Copyright © 2012 John Wiley & Sons, Ltd.
Optimization of a quadrupole ion storage trap as a source for time‐of‐flight mass spectrometry
Authors: Dangi Beni B. , Ervin Kent M.
Published: January 2012

Designs of a quadrupole ion trap (QIT) as a source for time‐of‐flight (TOF) mass spectrometry are evaluated for mass resolution, ion trapping, and laser activation of trapped ions. Comparisons are made with the standard hyperbolic electrode ion trap geometry for TOF mass analysis in both linear and reflectron modes. A parallel‐plate design for the QIT is found to give significantly improved TOF mass spectrometer performance. Effects of ion temperature, trapped ion cloud size, mass, and extraction field on mass resolution are investigated in detail by simulation of the TOF peak profiles. Mass resolution (m/Δm) values of several thousand are predicted even at room temperature with moderate extraction fields for the optimized design. The optimized design also allows larger radial ion collection size compared with the hyperbolic ion trap, without compromising the mass resolution. The proposed design of the QIT also improves the ion–laser interaction volume and photon collection efficiency for fluorescence measurements on trapped ions. Copyright © 2011 John Wiley & Sons, Ltd.
Mixed discretization schemes for electromagnetic surface integral equations
Authors: Ylä‐Oijala P. , Kiminki S. P. , Cools K. , Andriulli F. P. , Järvenpää S.
Published: January 2012

In developing accurate and stable discretization schemes for integral equations, important steps are the choices of the basis and testing functions. In the electromagnetic surface integral equations, the unknown quantities, the equivalent electric and magnetic surface current densities, are by default divergence conforming and therefore should be expanded with the divergence‐conforming basis functions. The choice of the testing functions however is less obvious and depends on the choice of the basis functions and the properties of the integral operators. We develop stable and well‐defined discretization procedures where the operators are tested either their range or on the dual of their range. This requires the use of non‐conventional finite‐elements spaces, called ‘dual spaces’, and non‐traditional testing procedures. We show with numerical examples that in most cases, testing the operators on the dual of their range leads to improved solution accuracy compared with testing the operators on their range. For the integral equations of the first kind, this agrees with the conventional Galerkin's scheme, but for the integral equations of the second kind, this requires the use of Petrov–Galerkin type discretization schemes with appropriate curl‐conforming (dual) testing functions. Copyright © 2012 John Wiley & Sons, Ltd.
Motor performance of young dystrophic mdx mice treated with long‐circulating prednisolone liposomes
Authors: Weller Charlotte , Zschüntzsch Jana , Makosch Gregor , Metselaar Josbert M. , Klinker Florian , Klinge Lars , Liebetanz David , Schmidt Jens
Published: January 2012

For Duchenne muscular dystrophy (DMD), a common myopathy that leads to severe disability, no causal therapy is available. Glucocorticosteroids improve patients' muscle strength, but their long‐term use is limited by negative side effects. Thus, pharmacological modifications of glucocorticosteroids are required to increase the efficacy by drug targeting. Liposomal encapsulation augments systemic half‐life and local tissue concentrations of glucocorticosteroids and, at the same time, reduces systemic side effects. In this study, the efficacy of novel, long‐circulating, polyethylene‐glycol‐coated liposomes encapsulating prednisolone was compared with free prednisolone in the treatment of mdx mice, a well‐established animal model for DMD. Using an objective and sensitive computerized 24‐hr detection system of voluntary wheel‐running in single cages, we demonstrate a significant impairment of the running performance in mdx compared with black/10 control mice aged 3–6 weeks. Treatment with liposomal or free prednisolone did not improve running performance compared with saline control or empty liposomes. Histopathological parameters, including the rate of internalized nuclei and fiber size variation, and mRNA and protein expression levels of transforming growth factor (TGF)‐β and monocytes chemotactic protein (MCP)‐1 also remained unchanged. Bioactivity in skeletal muscle of liposomal and free prednisolone was demonstrated by elevated mRNA expression of muscle ring finger protein 1 (MuRF1), a mediator of muscle atrophy, and its forkhead box transcription factors (Foxo1/3). Our data support the assessment of voluntary running to be a robust and reproducible outcome measure of skeletal muscle performance during the early disease course of mdx mice and suggest that liposomal encapsulation is not superior in treatment efficacy compared with conventional prednisolone. Our study helps to improve the future design of experimental treatment in animal models of neuromuscular diseases. © 2012 Wiley Periodicals, Inc.
ID2: A negative transcription factor regulating oligodendroglia differentiation
Authors: Chen Xing‐Shu , Zhang Yu‐Hang , Cai Qi‐Yan , Yao Zhong‐Xiang
Published: January 2012

Remyelination of the central nervous system in multiple sclerosis patients is often incomplete. Remyelination depends on normal oligodendrogenesis and the differentiation of oligodendrocyte precursor cells (OPC) into mature oligodendrocytes (OL). Inhibitor of DNA binding (ID), a transcription factor, is thought to inhibit oligodendrogenesis and the differentiation of OPC. This Mini‐Review aims to reveal the roles of and mechanisms used by IDs (mainly ID2) in this process. An interaction between ID2 and retinoblastoma tumor suppressor is responsible for the cell cycle transition from G1 to S. The translocation of ID2 between the nucleus and cytoplasm is regulated by E47 and OLIG. An interaction between ID2 and OLIG mediates the inhibitory effects of bone morphogenic proteins and G protein‐coupled receptor 17 on oligodendroglia differentiation. ID2 expression is regulated by Wnt and histone deacetylases during the differentiation of OPC. ID4, another member of the ID family, functions similarly to ID2 in regulating the differentiation of OPC. The main difference is that ID4 is essential for oligodendrogenesis, whereas ID2 is nonessential. This could have important implications for demyelinating diseases, and interfering with these pathways might represent a viable therapeutic approach for these diseases. © 2012 Wiley Periodicals, Inc.
Altered microtubule dynamics in Mecp2‐deficient astrocytes
Authors: Nectoux Juliette , Florian Cedrick , Delepine Chloe , Bahi‐Buisson Nadia , Khelfaoui Malik , Reibel Sophie , Chelly Jamel , Bienvenu Thierry
Published: January 2012

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by mutations in the gene MECP2 encoding the methyl‐CpG binding protein 2. This genetic disease affects predominantly girls and is characterized by a period of normal development that lasts for 8–18 months, followed by neurologic regression affecting both motor and mental abilities. Previous studies performed on brains from RTT subjects and Mecp2‐deficient mice showed striking changes in neuronal maturation and dendritic arborization. Recently, we showed that expression of stathmin‐like 2 (STMN2) was significantly reduced in fibroblasts from RTT patients, and similar results were obtained in the cerebellum of Mecp2‐deficient mice. Because assembly and dynamics of microtubules are known to be modulated by STMN2, we studied microtubule dynamics in brain cells from Mecp2‐deficient mice. We observed that Mecp2 deficiency affects microtubule dynamics in astrocytes from Mecp2‐deficient mice. Our data reinforce the fact that the loss of Mecp2 in astrocytes may influence the onset and progression of RTT. These results imply that Mecp2 has a stabilizing role in microtubule dynamics and that Mecp2 deficiency, which is associated with STMN2 down‐regulation, could lead to impaired microtubule stability, hence explaining the dendritic abnormalities observed in RTT brains. © 2012 Wiley Periodicals, Inc.
Herpes simplex virus type 1 induces nuclear accumulation of hyperphosphorylated tau in neuronal cells
Authors: Álvarez Gema , Aldudo Jesús , Alonso María , Santana Soraya , Valdivieso Fernando
Published: January 2012

Herpes simplex virus type 1 (HSV‐1) is a neurotropic virus that remains latent in host neurons. Viral DNA replication is a highly structured process in which the redistribution of nuclear proteins plays an important role. Although tau is most widely known as a microtubule‐associated protein found in a hyperphosphorylated state in the brains of patients with Alzheimer's disease (AD), this protein has also been detected at other sites such as the nucleolus. Here, we establish that HSV‐1 infection gives rise to an increase in tau phosphorylation and that hyperphosphorylated tau accumulates in the nucleus, forming defined structures in HSV‐1‐infected neuronal cells reminiscent of the common sites of viral DNA replication. When tau expression in human neuroblastoma cells was specifically inhibited using an adenoviral vector expressing a short hairpin RNA to tau, viral DNA replication was not affected, indicating that tau is not required for HSV‐1 growth in neuronal cells. Given that HSV‐1 is considered a risk factor for AD, our results suggest a new way in which to understand the relationships between HSV‐1 infection and the pathogenic mechanisms leading to AD. © 2012 Wiley Periodicals, Inc.
Implementation teams: A new lever for organizational change
Authors: Higgins Monica C. , Weiner Jennie , Young Lissa
Published: January 2012

This paper introduces a team form called an “implementation team”—a team charged with designing and leading the implementation of an organization‐wide change strategy—and investigates this team type in a context ripe for change, U.S. public school systems. Unlike prior teams research that has focused on teams as diagnostic collectives or strategic decision‐making bodies, this study forwards the notion that teams can be used to implement organizational change. In this study, we examined how positional and tenure diversity and work context relate to team member learning, a critical factor in sustaining organizational change. Results from 25 school district instructional improvement strategy teams over two years challenge some basic assumptions regarding what constitutes a “real team.” We find that some taken‐for‐granted aspects of teams, such as team member stability, may not be central or even appropriate when considering “real teams” in this change context; rather than stability of team membership, the stability of members' roles may matter most. We conclude by suggesting that scholars further investigate this team form and reframe, reconsider, and renew their conceptualizations of “real teams,” especially for teams engaged in implementing organizational change. Copyright © 2012 John Wiley & Sons, Ltd.
Sociometric badges: Using sensor technology to capture new forms of collaboration
Authors: Kim Taemie , McFee Erin , Olguin Daniel Olguin , Waber Ben , Pentland Alex “Sandy”
Published: January 2012

This article introduces sociometric badges as a research tool that captures with great accuracy fine‐scale speech patterns and body movements among a group of individuals at a scale that heretofore has been impossible in groups and teams studies. Such a tool offers great potential for studying the changing ecology of team structures and new modes of collaboration. Team boundaries are blurring as members disperse across multiple cultures, convene through various media, and operate in new configurations. As the how and why of collaboration evolves, an opportunity emerges to reassess the methods used to capture these interactions and to identify new tools that might help us create synergies across existing approaches to teams research. We offer sociometric badges as a complement to existing data collection methods—one that is well‐positioned to capture real‐time collaboration in new forms of teams. Used as one component in a multi‐method approach, sociometric badges can capture what an observer or cross‐sectional survey might miss, contributing to a more accurate understanding of group dynamics in new teams. We also revisit traditional teams research to suggest how we might use these badges to tackle long‐standing challenges. We conclude with three case studies demonstrating potential applications of these sociometric badges. Copyright © 2012 John Wiley & Sons, Ltd.
Endonasal endoscopic exposure of the internal carotid artery: An anatomical study
Authors: Fortes Felipe S. G. , Pinheiro‐Neto Carlos D. , Carrau Ricardo L. , Brito Rubens V. , Prevedello Daniel M. , Sennes Luiz U.
Published: January 2012

Objectives/Hypothesis:

The aim of this work was to define the anatomical landmarks, limitations, and difficulties of obtaining internal carotid artery (ICA) exposure via endonasal endoscopic approaches (EEA).

Study Design:

Cadaveric descriptive study.

Methods:

The ICA was dissected via EEA in 10 cadaveric specimens (20 sides) prepared with intravascular injections of colored silicone. We carried the ICA dissection from the cavernous to the distal parapharyngeal segments through a transpterygoid corridor.

Results:

The transpterygoid approach provided adequate exposure of the lacerum and horizontal petrous ICA. Additional exposure of the ICA and the infrapetrous area required resection of the eustachian tube (ET) and the fibrocartilaginous tissue of the foramen lacerum after a medial maxillectomy and resection of the pterygoid plates. The main anatomical landmarks to the corresponding ICA segment include: the vidian nerve that points to the lacerum and horizontal segments, the mandibular nerve (V3) that heralds the petrous segment, the foramen ovale and the ET that signal toward the carotid canal, and the posterior trunk of the mandibular nerve (V3) and the ET that mark the parapharyngeal segment.

Conclusions:

EEAs provide access to the ICA from its cavernous to the distal parapharyngeal segments. A stepwise approach is critical to its exposure and control. Surgeons must be aware of its frequently tortuous three‐dimensional course and the intimate relation of the vessel to the carotid canal and the cartilage of the foramen lacerum.
Current dysphonia trends in patients over the age of 65: Is vocal atrophy becoming more prevalent?
Authors: Davids Taryn , Klein Adam M. , Johns Michael M.
Published: January 2012

Objectives/Hypothesis:

The current trends in geriatric voice referrals including the number of patients over the age of 65 years seen per year, the common diagnostic patterns, and specifically the number of patients with vocal atrophy were assessed.

Study Design:

Retrospective cohort study.

Methods:

A retrospective chart review of all patients seen at the Emory Voice Center for otolaryngologic complaints between the years of 2004 and 2009 was performed.

Results:

Of the 6,360 patients seen over a 6‐year period, 21% were over the age of 65 years. Fifty‐eight percent of patients over the age of 65 years had vocal complaints, with the most common diagnoses being vocal atrophy (25%), neurologic vocal dysfunction (23%), and vocal fold immobility (19.2%). Of those patients diagnosed with vocal atrophy, the majority opted for voice therapy (57%), followed by reassurance (39%), and injection laryngoplasty (6%). There was a statistically significant improvement in mean pretherapy and post‐therapy voice‐related quality of life (VRQOL) score.

Conclusions:

As the number of people in the over 65‐year‐old age bracket increases, so do the number of geriatric referrals. Although diagnostic trends remain the same, vocal atrophy is becoming more prevalent, with a large number of patients seeking intervention. This will likely result in an increased need for health resources in the future.
Sharps exposures among otolaryngology–head and neck surgery residents
Authors: Vanhille Derek L. , Maiberger Patrick G. , Peng Angela , Reiter Evan R.
Published: January 2012

Objectives/Hypothesis:

Examine the incidence of sharps exposures among otolaryngology residents, assess characteristics of exposures, and determine rates of reporting these potentially career‐ and life‐impacting exposures.

Study Design:

Cohort study of otolaryngology–head and neck surgery residents.

Methods:

Survey was administered online to otolaryngology residents in the spring of 2008, gathering demographic information, characteristics of sharps exposures, and residents' self‐reporting of sharps exposures.

Results:

Among 1,407 otolaryngology residents nationwide, 231 completed the survey. Of these, 168 (72.7%) had at least one sharps exposure during residency, with most due to solid‐bore needles (51.7%) and occurring in the operating room (67%). Fifty percent of residents reported exposures occurring in postgraduate year (PGY)‐3 or PGY‐4, whereas exposures occurred at slightly lower rates in the other PGYs. There was no difference in incidence of sharps exposures based on gender (Fisher exact test, P = .2742) or history of sharps exposure during medical school (Fisher exact test, P = .7559). Seventy‐four participants had an exposure that they did not report to the hospital, with the most common reason for not reporting being the perceived burden of the hospital testing protocol.

Conclusions:

Otolaryngology residents report a high rate of sharps exposures during residency training, with a significant number of these exposures going unreported. Better education may be needed to help decrease these often preventable workplace exposures and to improve compliance with reporting and testing procedures.
The Ronkin number of an exponential sum
Authors: Silipo James
Published: January 2012

We give an intrinsic estimate of the number of connected components of the complementary set to the amoeba of an exponential sum with real spectrum improving the result of Forsberg, Passare and Tsikh in the polynomial case and that of Ronkin in the exponential one.
Positivity properties for the clamped plate boundary problem on the ellipse and strip
Authors: Render Hermann , Ghergu Marius
Published: January 2012

The positivity preserving property for the biharmonic operator with Dirichlet boundary condition is investigated. We discuss here the case where the domain is an ellipse (that may degenerate to a strip) and the data is a polynomial function. We provide various conditions for which the positivity is preserved.
Fabrication of Chitosan Single‐Component Microcapsules With a Micrometer‐Thick and Layered Wall Structure by Stepwise Core‐Mediated Precipitation
Authors: Han Yuanyuan , Tong Weijun , Zhang Yuying , Gao Changyou
Published: January 2012

Incubation of CaCO3 microparticles in chitosan (CS) solution at pH 5.2 and following with ethylenediaminetetraacetic acid disodium salt (EDTA) treatment resulted in CS single‐component microcapsules with an ultra‐thick wall structure. Repeating the incubation caused stepwise increase of wall thickness and finally resulted in CS microcapsules with a layered structure. This unique method is mediated by precipitation of CS on the CaCO3 particles as a result of pH increase caused by the partial dissolution of CaCO3. The obtained CS capsules are stable at neutral pH.
Novel Source of Trifluoromethyl Radical As Efficient Initiator for the Polymerization of Vinylidene Fluoride
Authors: Boschet Frédéric , Ono Taizo , Ameduri Bruno
Published: January 2012

A persistent perfluoroalkyl radical (PPFR), perfluoro‐3‐ethyl‐2,4‐dimethyl‐3‐pentyl, is shown to be a good source of •CF3 radicals and a useful radical capable of initiating the polymerization of vinylidene fluoride (VDF). NMR characterizations of the resulting PVDF homopolymers showed that polymerization of VDF was exclusively initiated by •CF3 radicals. The addition of •CF3 radical onto VDF was regioselective leading to CF3‐CH2‐CF2‐PVDF and the CF3 end‐group acted as an efficient label to assess the molecular weights by 19F NMR spectroscopy. Various [PPFR]0/[VDF]0 initial molar ratios lead to CF3–PVDF–CF3 of different molecular weights. When that ratio decreased, both the molecular weights and the thermostability of these PVDFs increased, showing less defects of chaining and higher crystallinity.
Distortion engineering – interim results after one decade research within the Collaborative Research Center
Authors: Zoch H.‐W.
Published: January 2012

The result of distortion during manufacturing and its removal or correction totally amounts to similar economical losses in industry as known by wear or corrosion phenomena. Therefore over a long time high efforts have been taken to avoid or minimize distortion, starting with basic investigations at the beginning of the last century. The increasing importance led to intensified research, culminating in the late 90's with several investigations on steel grades and productions routes and their impact on dimensional changes. Focussing on separated aspects and influencing parameters before, the establishment of the Collaborative Research Center “Distortion Engineering” at Bremen University, funded by the Deutsche Forschungsgemeinschaft (DFG), first time treated distortion as a system attribute and result of the entire process chain. After 11 years of project work in the CRC, which ends in 2011, a summary of achievements and outlook on further investigations is given.
Distortion of rings due to inhomogeneous temperature distribution
Authors: Surm H. , Frerichs F. , Lübben T. , Hoffmann F. , Zoch H.‐W.
Published: January 2012

In this paper, experimental results regarding the effect of asymmetric temperature distributions on shape changes of different ring types due to heat treatment will be presented. The main part of the distortion can be attributed to a distortion mechanism which is caused by the interaction of an inhomogeneous temperature distribution and the corresponding local phase transformation: In particular plastic strains by transformation plasticity dominate the change in roundness and the change of the angle of the raceways. To evaluate the portion on roundness deviation which can be attributed to sole thermal stress and/or transformation plasticity effects, experiments with rings produced from austenitic steel (material SAE 304) were examined. In addition, conical rings were heat treated, since the ring geometry has a large influence on the temperature fields during heat treatment. The experimental results were compared with the theoretical description of distortion potential by strain analysis, to identify the necessary inhomogeneous distribution of different carriers of the distortion potential which lead to the observed change in roundness deviation.
Process integrated distortion compensation of large bearing rings
Authors: Stark P. , Fritsching U. , Hunkel M. , Hansmann D.
Published: January 2012

Bearing rings (d ⪈ 1000 mm, material: 42CrMo4) may be quenched directly after the hot rolling process with the use of adapted jet fields. Specific asymmetric cooling conditions for controlled heat treatment processes shall be utilized for distortion compensation. The feasibility of liquid quenching techniques (water jet cooling a) in water b) in ambient air and c) spray cooling) is investigated experimentally concerning the achievable cooling curves of the ring specimen and the resulting heat transfer coefficients on its surface. The influence of the distribution of the quenching intensities around the ring's circumference on the achievable distortion compensation behaviour is investigated both experimentally in a jet nozzle field and through numerical simulations.
Parameters of distortion in forging gear wheel blanks
Authors: Rentsch H.
Published: January 2012

The gear wheel manufacture is one of the key technologies for power train systems and in automotive industry. These complex high performance parts require stable processes and narrow tolerances in order to control the manufacturing costs. Experimental analyses show that the material flow in disk‐like gear wheel blanks made of 20MnCr5 can vary significantly. This is of significance as a correlation between the dishing after case‐hardening of the gear wheel blanks and the material flow was found. Besides experimental findings, finite element (FE) analyses of the influence of process parameters and perturbations on the distortion of forged gear wheel blanks have been carried out. A temperature gradient over the height of the workpiece is assumed to be largely responsible for the observed material flow variations and the related dishing of the forged gear wheel blanks.
Anisotropies and inhomogeneities in the microstructure of the case hardening steel SAE 5120
Authors: Eisbrecher I. , Clausen B. , Hunkel M. , Rentsch R.
Published: January 2012

Distortion is an effect of inhomogeneous strain behavior. It can be initiated by plasticity due to thermal or transformation stresses (such as yielding, creep and transformation plasticity), phase transformations or strains during phase transformations. Inhomogeneities in microstructure and anisotropies constitute a distortion potential. Based on this knowledge several investigations were carried out on forged disks with a centered hole made of low alloy steel SAE 5120 (EN 20MnCr5) because both inhomogeneity and anisotropy have been observed in the microstructure of this material. Disks have been forged from continuous cast and hot rolled bar material. They show an inhomogeneous banded microstructure that is explicitly orientated in the direction of the two manufacturing processes. By forging, the initial microstructure of the bar material is influenced significantly: the segregation bands parallel to the rolling direction are deformed into a typical pattern. Besides this inhomogeneity in microstructure also the inhomogeneities of the bar material, such as center segregations from continuous casting, can still be observed in the deformed material. Gear blanks were machined from these disk blanks. It has been shown that the original position of the gear blank inside the disk blank influences the distortion [1]. The underlying reason remained unclear and investigations on this topic are discussed in this paper.
Semi‐optical in‐process‐metrology to determine the roundness deviation of bearing rings during heat treatment
Authors: Gafsi H. , Goch G.
Published: January 2012

This paper presents two different systems for measuring the roundness deviation of bearing rings during heating and gas quenching. During heating in a furnace, laser triangulation is applied to measure absolute values for the ring's mean radius and ovality. Afterwards, the ring is quenched in a gas nozzle field equipped with a semi‐optical measurement system consisting of twelve tactile and twelve optical sensors independent from each other. Before quenching, the tactile sensors measure in‐situ the absolute mean radius of the near 900°C hot ring and its roundness deviation from ovality up to pentagonality. Based on this information, the optical sensors measure in‐process the change of the roundness deviation during the gas quenching, as the tactile sensors cannot be used in high speed gas jets due to turbulence.
Some recent developments in modelling of heat‐treatment phenomena in steel within the collaborative research centre SFB 570 “Distortion Engineering”
Authors: Wolff M. , Böhm M. , Bökenheide S. , Dalgiç M.
Published: January 2012

It is the aim to present some developments in modelling of distortion‐related phenomena during heat treatment of steel in the context of the Collaborative Research Centre SFB 570 “Distortion Engineering” at the Bremen University, Germany. Taking this into account, a survey will be given and some results will be exemplarily presented. This work is the first contribution to the session “Modelling of material behaviour within the CRC Distortion Engineering” of the 3rd International Conference on Distortion Engineering, Bremen, 2011. The following articles by Hunkel 2011 [1] and by Bökenheide et al. 2011 [2] deal in detail with the steel qualities 100Cr6 (SAE 52100) and 20MnCr5 (SAE 5120), respectively. Here, more general aspects of the subsequent phenomena are in the focus: Phase transformations (PT) and transformation‐induced plasticity (TRIP) during quenching and heating, plastic behaviour of (supercooled) austenite as well as creep during heating and austenitising. The following items will be considered in particular: Experiments and processing strategies for experimental data, model approaches and results for single phenomena of material behaviour. Many assertions have a general character not linked to special steel sorts. We will also address open questions and possible perspectives.
Modelling of phase transformations and transformation plasticity of a continuous casted steel 20MnCr5 incorporating segregations
Authors: Hunkel M.
Published: January 2012

In general, material data for heat treatment simulations are assumed to be isotropic and homogeneous (except the carbon dependency for case hardening simulations). But it was found for the conventional continuous casted case hardening steel 20MnCr5 (SAE 5120) that segregations lead to anisotropic and inhomogeneous properties especially during phase transformations. This paper reviews the work within the Collaborative Research Centre SFB 570 “Distortion Engineering” on determination of segregations and its influence on phase transformations and plasticity as well as the subsequent modelling and simulation.
Numerical distortion simulation of roller bearing rings
Authors: Grohmann O. , Rentsch R. , Heinzel C. , Brinksmeier E.
Published: January 2012

Research within the collaborative research center SFB 570 “Distortion Engineering” has identified effects of the material flow and the strain distribution in metal forming on the distortion of parts. Within this paper the influence of the distortion potential of roller bearings resulting from the hot metal forming process in the industrial manufacturing chain is of special interest. In an experimental study an out‐of‐roundness of the bearings was detected, possibly caused by the shearing process of bar stocks. As a result of the shearing condition both front ends of the cylindrical billet are deformed and oval in shape. This shape deviation is taken into account and transferred into a FE‐model. However, this completes the boundary conditions for the hot metal forming simulation. As a result the simulation proved that the inaccurate geometry causes ring distortion and results in stresses due to a varying strain distribution in the rings.
Influence of austenitisation and transformation hardening on the residual stress development of laser beam treated components made of 20MnCr5
Authors: Sakkiettibutra J. , Kamau E. N.
Published: January 2012

In steel forming process chains residual stresses affect the final form of work pieces. This may have a detrimental effect, e. g. in the case of released residual stresses during laser welding of a shaft‐hub connection, or may be used purposefully, as in the case of a selective application of residual stresses in thermal pre‐stressing. During final heat treatment or rather hardening, distortion is essentially changed. In order to control or exploit the effect of residual stresses, they must be determined at first and their formation has also to be understood. One often neglected influence on the residual stresses is the dependence of the local flow stress, which strongly changes due to the structural transformation. Especially for processes with a high heating and cooling rate the incomplete austenitisation limits the structural hardening during cooling. For both of the applications mentioned above, it will be demonstrated how this influence can be taken into account based on a model and how this influence affects the absolute quantity of residual stresses. The modeled shape changes and residual stresses results are substantiated using speckle photography, laser triangulation, x‐ray and neutron diffraction measurements.
Method to describe interdependencies of state characteristics related to distortion
Authors: Wuest T. , Klein D. , Seifert M. , Thoben K.‐D.
Published: January 2012

The product state can be described through its state characteristics. In each process step some state characteristics are changed to add value to the product. It is also important to be aware of how state characteristics change over time and valuable to understand the interdependencies between different state characteristics. The purpose of this paper is to develop a method, which describes and illustrates interdependencies between relevant state characteristics along a production process chain with the goal to increase transparency for the stakeholders of the product. The process chain of a bearing ring within the project CRC 570 Distortion Engineering and interdependencies of relevant state characteristics connected to distortion and distortion potential will be used as an example to illustrate the above‐mentioned method. A discussion on limitations and benefits of this approach will serve as a conclusion.
Efficiency and heterogeneity of public spending in education among Italian regions
Authors: Sibiano Piergiacomo , Agasisti Tommaso
Published: January 2012

The Italian educational system is strictly regulated by the Ministry of Education. However, there are strong differences in educational inputs and outputs among regions, as can be noticed by analysing the allocation of public budgets to the regions and their students' (average) performance in national and international test scores. A general institutional change is ongoing in Italy, that is, the decentralisation of competencies from the State to the regions (federalism). Some insights are necessary about the efficiency of public spending on education in a comparative perspective across regions. To estimate efficiency scores, a nonparametric technique called data envelopment analysis was used. The unit of analysis comprises the 18 Italian regions, with the focus on the lower secondary education. Then, a second‐stage Tobit regression was used to detect the factors affecting efficiency. The results corroborate the difference between the North and South of Italy (the regions in the North outperform their counterparts in the South). When looking at the regional socioeconomic context, gross domestic product per capita appears as the key determinant of efficiency. Copyright © 2012 John Wiley & Sons, Ltd.
Stability Studies of Crude Plant Material of Bacopa monnieri and Quantitative Determination of Bacopaside I and Bacoside A by HPLC
Authors: Srivastava Pratibha , Raut Hema N. , Puntambekar Hemalata M. , Desai Anagha C.
Published: January 2012

Introduction

Bacopa monnieri (BM) contains several dammarane‐type triterpenoid saponins including bacopaside I and bacoside A. These bioactive compounds may be used as chemical markers for the quality control of different BM products used for promoting mental health and intellect.

Objective

Quantification of bacopaside I and bacoside A in crude plant material of BM stored under the stability study conditions by HPLC.

Methodology

Crude BM samples were stored at long‐term (LS; 30°C and 65% RH), accelerated (AS; 40°C and 75% RH) and real‐time (RT) study conditions. HPLC of BM extracts was carried out using a LiChroCART Purospher® STAR RP‐18 endcapped column along with a guard column, Purospher STAR RP 18e 4.0 4.0 mm 5 µm using a gradient of acetonitrile (A) and water containing 0.05% (v/v) orthophosphoric acid (B) at a flow rate 1.5 mL/min with UV detection at 205 nm.

Results

The linear range of bacopaside I and bacoside A was 0.2 to 1 mg/mL. With the help of a regression equation the coefficient of determination (r2) values for bacopaside I and bacoside A were found to be > 0.999 and > 0.994 respectively. Relative standard deviation (RSD) values were < 4.0 for all the concentrations injected (n = 3). The HPLC study indicated that BM samples kept under LS condition are rich in saponin contents as compared with the samples stored under AS and RT study conditions.

Conclusion

The study indicated that BM plant material should be used fresh to obtain maximum concentration of active saponins or it should be stored under LS conditions up to 3 months. Copyright © 2012 John Wiley & Sons, Ltd.
Performance ratio revisited: is PR > 90% realistic?
Authors: Reich Nils H. , Mueller Bjoern , Armbruster Alfons , van Sark Wilfried G. J. H. M. , Kiefer Klaus , Reise Christian
Published: January 2012

In this study, we investigate the performance ratio (PR) of about 100 German photovoltaic system installations. Monitored PR is found to be systematically lower by ~2–4% when calculated with irradiation data obtained by pyranometers (henceforth denoted as PRPyr) as compared with irradiation amounts measured by reference cells (denoted as PRSi). Annual PRSi for the ~100 systems is found to be between ~70% and ~90% for the year 2010, with a median PR of ~84%. Next, simulations were performed to determine loss mechanisms of the top 10 performing systems, revealing a number of these loss mechanisms may still allow for some optimization. Despite the fact that we do not see such values from our monitoring data base up to now, we believe PRSi values above 90% are realistic even today, using today's commercially available components, and should be expected more frequently in the future. This contribution may help in deepening our knowledge on both energy loss mechanisms and efficiency limits on the system level and standardization processes of system‐related aspects. Copyright © 2012 John Wiley & Sons, Ltd.
Influence of surface texture on the defect‐induced breakdown behavior of multicrystalline silicon solar cells
Authors: Kwapil Wolfram , Nievendick Jan , Zuschlag Annika , Gundel Paul , Schubert Martin C. , Warta Wilhelm
Published: January 2012

The defect‐induced diode breakdown behavior in multicrystalline silicon solar cells, which is located at recombination active crystal defects, is influenced by the surface texturization because the wet chemical treatment selectively etches grain boundaries and dislocations, resulting in etch pits. On textured surfaces, the defect‐induced breakdown voltage is decreased, and the slope of the local reverse I–V characteristics in breakdown is steeper. We find that the local defect‐induced breakdown voltage correlates with the depth of the etch pits. It is suggested that the enhanced electric field in the space charge region at the tip could be superimposed by an electric field around metallic precipitates because of the internal Schottky contact formation with the surrounding silicon. The combined electric field could be responsible for the dependence of the defect‐induced breakdown behavior on the surface texture. Copyright © 2012 John Wiley & Sons, Ltd.
The photochemistry of the self‐healing chromophore Disperse Orange 11
Authors: Westfall Nathan J. , Dirk Carl W.
Published: January 2012

Recent interest in the self‐healing ability of the laser dye 1‐amino‐2‐methylanthraquinone, Disperse Orange 11, has lead us to investigate the possible alternative mechanisms of action, either intramolecular proton transfer (PT) or twisted intramolecular charge transfer (TICT) formation. AMPAC semiempirical PM3 CI (all single excited configurations) potential energy surfaces searches have been conducted with either reaction mechanism. Based purely on the potential energy surface results, no state, S0, T1, or S1, seems especially likely to be kinetically favorable for PT. The T1 state is favorable thermodynamically for PT. However, the S1 state TICT reaction is both thermodynamically favorable and kinetically preferred over all PT reactions. There is also a favorable T1 TICT reaction, but much slower kinetically on the triplet surface than S1 TICT. The Wentzel–Kramers–Brillouin (WKB) method has been used to ascertain proton tunneling contributions to PT. Even with proton tunneling, S1 TICT is still more highly favored, though proton tunneling could make the T1 PT reaction competitive depending on the rate of intersystem crossing. We also examine spectroscopic properties of PT transfer and TICT reaction path entities in comparison with published experimental evidence. However, this comparison leads to ambiguous findings that suggest that electronic spectral properties alone will not fully clarify the mechanism. Overall, results suggest that the TICT mechanism is the most likely for optical damage and self‐repair for Disperse Orange 11, and might be considered for the damage and repair mechanisms for other organic solid state laser materials. Copyright © 2012 John Wiley & Sons, Ltd.
Molecular modeling of hair keratin/peptide complex: Using MM‐PBSA calculations to describe experimental binding results
Authors: Azoia Nuno G. , Fernandes Margarida M. , Micaêlo Nuno M. , Soares Cláudio M. , Cavaco‐Paulo Artur
Published: January 2012

Molecular dynamics simulations of a keratin/peptide complex have been conducted to predict the binding affinity of four different peptides toward human hair. Free energy calculations on the peptides' interaction with the keratin model demonstrated that electrostatic interactions are believed to be the main driving force stabilizing the complex. The molecular mechanics–Poisson‐Boltzmann surface area methodology used for the free energy calculations demonstrated that the dielectric constant in the protein's interior plays a major role in the free energy calculations, and the only way to obtain accordance between the free energy calculations and the experimental binding results was to use the average dielectric constant. Proteins 2012;. © 2012 Wiley Periodicals, Inc.
MAPPING RIVER DEPTH FROM PUBLICLY AVAILABLE AERIAL IMAGES
Authors: Legleiter C. J.
Published: January 2012

Remote sensing could facilitate efficient characterization of river systems for research and management purposes, provided that suitable image data are available and that the information derived therefrom is reliable. This study evaluated the utility of public domain multispectral images for estimating flow depths in a small stream and a larger gravel‐bed river, using data acquired through a task‐oriented consortium and the National Agricultural Imagery Program (NAIP). Field measurements were used to calibrate image‐derived quantities to observed depths and to assess depth retrieval accuracy. A band ratio‐based algorithm yielded coherent, hydraulically reasonable bathymetric maps for both field sites and three different types of image data. Applying a spatial filter reduced image noise and improved depth retrieval performance, with a strong calibration relationship (R2 = 0.68) and an observed (field‐surveyed) versus predicted (image‐derived) R2 of 0.6 for tasked images of the smaller stream. The NAIP data were less useful in this environment because of geo‐referencing errors and a coarser spatial resolution. On the larger river, NAIP‐derived bathymetry was more accurate, with an observed versus predicted R2 value of 0.64 for a compressed county mosaic easily accessible via the Internet. Comparison of remotely sensed bathymetric maps with field surveys indicated that although the locations of pools were determined accurately, their full depth could not be detected because of limited sensor radiometric resolution. Although a number of other constraints also must be considered, such as the need for local calibration data, depth retrieval from publicly available image data is feasible under appropriate conditions. Copyright © 2012 John Wiley & Sons, Ltd.
Secure communication for the Internet of Things—a comparison of link‐layer security and IPsec for 6LoWPAN
Authors: Raza Shahid , Duquennoy Simon , Höglund Joel , Roedig Utz , Voigt Thiemo
Published: January 2012

The future Internet is an IPv6 network interconnecting traditional computers and a large number of smart objects. This Internet of Things (IoT) will be the foundation of many services and our daily life will depend on its availability and reliable operation. Therefore, among many other issues, the challenge of implementing secure communication in the IoT must be addressed. In the traditional Internet, IPsec is the established and tested way of securing networks. It is therefore reasonable to explore the option of using IPsec as a security mechanism for the IoT. Smart objects are generally added to the Internet using IPv6 over Low‐power Wireless Personal Area Networks (6LoWPAN), which defines IP communication for resource‐constrained networks. Thus, to provide security for the IoT based on the trusted and tested IPsec mechanism, it is necessary to define an IPsec extension of 6LoWPAN. In this paper, we present such a 6LoWPAN/IPsec extension and show the viability of this approach. We describe our 6LoWPAN/IPsec implementation, which we evaluate and compare with our implementation of IEEE 802.15.4 link‐layer security. We also show that it is possible to reuse crypto hardware within existing IEEE 802.15.4 transceivers for 6LoWPAN/IPsec. The evaluation results show that IPsec is a feasible option for securing the IoT in terms of packet size, energy consumption, memory usage, and processing time. Furthermore, we demonstrate that in contrast to common belief, IPsec scales better than link‐layer security as the data size and the number of hops grow, resulting in time and energy savings. Copyright © 2012 John Wiley & Sons, Ltd.