bluuebunny/crossref_metadata_2025 huggingface dataset:
Calvaria bone chamber—A new model for intravital assessment of osseous angiogenesis
Authors: Sinikovic Branko , Schumann Paul , Winkler Meike , Kuestermeyer Julian , Tavassol Frank , von See Constantin , Carvalho Carlos , Mülhaupt Rolf , Bormann Kai‐Hendrik , Kokemueller Horst , Meyer‐Lindenberg Andrea , Laschke Matthias W. , Menger Michael D. , Gellrich Nils‐Claudius , Rücker Martin
Published: August 2011

The faith of tissue engineered bone replacing constructs depends on their early supply with oxygen and nutrients, and thus on a rapid vascularization. Although some models for direct observation of angiogenesis are described, none of them allows the observation of new vessel formation in desmal bone. Therefore, we developed a new chamber model suitable for quantitative in vivo assessment of the vascularization of bone substitutes by intravital fluorescence microscopy. In the parietal calvaria of 32 balb/c mice a critical size defect was set. Porous 3D‐poly(L‐lactide‐co‐glycolide) (PLGA)‐blocks were inserted into 16 osseous defects (groups 3 and 4) while other 16 osseous defects remained unequipped (groups 1 and 2). By placing a polyethylene membrane onto the dura mater, the angiogenesis was mainly restricted to the osseous margins (groups 2 and 4). Microvascular density, angiogenesis, and microcirculatory parameters were evaluated repetitively during 22 days. In all animals, only a mild inflammatory reaction was observed with a climax after 2 weeks. The implantation of PLGA scaffolds resulted in a vascular growth directed towards the center of the defect as demonstrated by the significantly (p < 0.05) enhanced central microvascular densitiy from day 3 to day 22 when compared with unequipped chambers. The additional application of polyethylene membrane was found to reduce significantly the microvessel density mainly in the center of both scaffolds and defects. The present calvaria bone chamber allows for the first time to assess quantitatively the angiogenesis arising from desmal bone directly in vivo. Therefore, this chronic model may support the future research in the biological adequacy of bone substitutes. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
The biocompatibility and antimicrobial activity of nanocomposites from polyurethane and nano silicate platelets
Authors: Tseng Hsiang‐Jung , Lin Jiang‐Jen , Ho Tung‐Tso , Tseng Sheng‐Mao , Hsu Shan‐hui
Published: August 2011

Nanocomposites from a polyether‐type waterborne polyurethane (PU) and 0.1 wt % of silicate materials were prepared. The individual silicate materials were natural clays (montmorillonite and mica), their exfoliated clays [nano silicate platelets (NSP) and nano mica platelets], and NSP modified with C18 fatty amine (NSP‐S). The physico‐chemcical properties and antimicrobial activity of the nanocomposites were characterized in
vitro. The biostability and biocompatibility of the nanocomposites were evaluated in vivo. The nanocomposites exhibited various surface morphologies with phase separation of hard and soft domains in nanometric scales. The nanocomposite containing NSP (PU‐NSP) showed better endothelial cell attachment and gene expression. The better biocompatibility of PU‐NSP and PU‐NSP‐S was evidenced by the lower thickness of foreign body capsules in rat subcutaneous implantation. PU‐NSP had the least surface degradation in vivo as demonstrated by the electron microscopy and infrared spectroscopy. This may be associated with the different surface structure. PU‐NSP and PU‐NSP‐S showed strong bacteriostatic effects, which suggested that the nano clay in the polymer matrix may still interact with the microbes. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Maintenance of hepatic differentiation by hepatocyte attachment peptides derived from laminin chains
Authors: Kikkawa Yamato , Kataoka Akira , Matsuda Yuji , Takahashi Naoya , Miwa Takahiro , Katagiri Fumihiko , Hozumi Kentaro , Nomizu Motoyoshi
Published: August 2011

Hepatocytes rapidly lose hepatic functions upon isolation from liver, perhaps due to disrupted cell/matrix interactions. The matrix macromolecule laminin‐111 consists of three chains, α1, β1, and γ1; it is a major component of Matrigel, which can maintain hepatic differentiation. We previously showed that the A13 peptide (RQVFQVAYIIIKA, α1 chain 121–133) derived from mouse laminin α1 exhibits hepatocyte attachment activity and maintains hepatic differentiation. Here, we sought to identify hepatocyte adhesive sequences from the mouse laminin β1 and γ1 chains using 22 synthetic peptides that show biological activity for fibrosarcoma cells. Nine peptides showed hepatocyte attachment activity. Of these, B160 (VILQQSAADIAR, β1 chain 1607–1618), and C16 (KAFDITYVRLKF γ1 chain 139–150) exhibited the most potent activity. Hepatocytes cultured on both peptides also maintained expression of albumin, tyrosine aminotransferase, tryptophan‐2,3‐dioxygenase, and cytochrome P450. The morphology of hepatocytes on both peptides was a rounded shape typical for hepatic differentiation. We also characterized the nature of adhesion to the peptides. Heparin and EDTA inhibited cell attachment to both peptides, suggesting that hepatocyte attachment to the peptides was mediated by multiple receptors. The identification of active sequences regulating hepatic functions may facilitate the design of hepatocyte culture substrata that can regulate specific cellular behaviors in the context of a bioartificial liver. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
The effects of surface and biomolecules on magnesium degradation and mesenchymal stem cell adhesion
Authors: Liu Huinan
Published: August 2011

A novel class of biodegradable metals, magnesium (Mg) and Mg‐based alloys, has recently attracted much attention because of unique biodegradation and mechanical properties for medical applications. Ideally, Mg‐based devices should degrade no faster than the degradation products can be eliminated efficiently from the body. Additionally, for orthopedic and maxillofacial applications, the implant integration with the surrounding bone is critical for its clinical success. Therefore, it is necessary to thoroughly characterize Mg surface and degradation and investigate how these characteristics influence its interactions with essential cells, for example, bone marrow derived mesenchymal stem cells. The objectives of this study were to investigate (1) the effects of two surface conditions (the presence vs. absence of surface oxides) on Mg degradation and mesenchymal stem cell adhesion, and (2) the effects of two essential aqueous environments (the presence vs. absence of physiological ions and proteins) on Mg degradation. In an effort towards standardizing testing methods for Mg alloys, consistent and well‐controlled experimental methods were designed to characterize the surface and degradation of Mg and its interactions with cells. The results demonstrated that original surface (oxidized vs. polished) conditions had a less pronounced effect on regulating initial cell adhesion, but did affect surface morphology and composition of the Mg samples after 24 h of cell culture. The presence versus absence of biological ions and proteins had a significant effect on Mg degradation mode and rate. In conclusion, the material surface and anatomical sites of implantation dependent on the intended applications must be carefully considered while assessing Mg alloys in vitro or in vivo for medical applications. Standardized testing procedures and methods are critically needed for developing more effective medical‐grade Mg alloys. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Uterine and chorioallantoic angiogenesis and changes in the uterine epithelium during gestation in the viviparous lizard,niveoscincus conventryi(squamata: scincidae)
Authors: Ramírez‐Pinilla Martha Patricia , Parker Scott L. , Murphy Christopher R. , Thompson Michael B.
Published: August 2011

We used immunofluorescent confocal microscopy and scanning electron microscopy to quantify uterine vascularity and to describe uterine surface morphology during gestation in pregnant females of the lecithotrophic lizardNiveoscincus coventryi. As uterine angiogenesis and epithelial cell morphology are thought to be under progesterone control, we studied the effect of a progesterone receptor antagonist (mifepristone) on uterine and chorioallantoic microvasculature and features of the uterine epithelial surfaces. Although intussuceptive angiogenesis was observed in both, uterine and chorioallantoic, vascular beds during gestation, the only significant increases were in the diameters of the uterine vessels. An ellipsoid vessel‐dense area grows in the mesometrial hemisphere of the developing conceptus, which parallels the expansion of the allantois to form the chorioallantoic placenta. Uterine surface topography changed during gestation. In particular, uterine blood vessels bulge over the luminal surface to form marked ridges on the uterine embryonic hemisphere, especially during the last stage of pregnancy, and ciliated cells are maintained in the embryonic and abembryonic hemispheres but disappear in both the mesometrial and antimesometrial poles. This distinct regionalization of uterine ridges and ciliated cells in the uterine surface and in the shape of the epithelial component of the chorion might be related to the function of both chorioallantoic and yolk sac placentae during gestation. There was no significant difference between females treated with or without mifepristone, which may be related to the partial function of mifepristone as a progestin antagonist and/or with the function and time of action of progesterone in the uterus during gestation inN. coventryi. Differences in the pattern of angiogenesis and uterine surface morphology during gestation among squamates may be related to the functional diversity of the uterine component of the different placentae and probably reflect its diverse evolutionary history. J. Morphol., 2011. © 2011 Wiley Periodicals, Inc.
MR venography of the brain with enhanced vessel contrast using image‐domain high‐pass filtering of the susceptibility phase shift
Authors: Jin Zhaoyang , Xia Ling , Lou Min , Zhang Minming , Du Yiping P.
Published: August 2011

Purpose:

To develop a postprocessing algorithm that enhances the visibility of intracranial venous vasculature and reduces the artifacts in the display of susceptibility‐weighted images (SWI).

Materials and Methods:

Image‐domain high‐pass filters based on second‐order phase difference were applied to the complex 3D SWI data to enhance the susceptibility phase shift of the veins and suppress background signal in SWI. A multivariant statistical parameter was used to suppress the noise in air.

Results:

Magnetic resonance (MR) venography with enhanced susceptibility phase shift and reduced off‐resonance artifacts was obtained using the proposed filters. The background signal in the 3D MR venography data was well suppressed. Venous vasculature in the peripheral regions of the brain was well depicted and the adverse effect of noise in air in the maximum‐intensity projection display of the 3D SWI data was well suppressed.

Conclusion:

Image‐domain high‐pass filtering with second‐order phase difference provides an alternative display of 3D SWI data with enhanced visibility of the venous vasculature and effective suppression of artifacts. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.
Orienting the Demixion of a Diblock‐copolymer Using 193 nm Interferometric Lithography for the Controlled Deposition of Nanoparticles
Authors: Dirani Ali , Stehlin Fabrice , Dika Ihab , Spangenberg Arnaud , Grumbach Nathan , Gallani Jean‐Louis , Donnio Bertrand , Greget Romain , Begin‐Colin Sylvie , Demortière Arnaud , Soppera Olivier
Published: August 2011

DUV interferometric lithography and diblock copolymer self‐organization have successfully been combined to provide a simple and highly collective nanopatterning technique enabling the organization of nanoparticles over several orders of magnitude, from nanometre to millimetre. The nanostructural changes at the surface of the polymer film after thermal annealing have been monitored by AFM and the process parameters optimized for obtaining a long‐range organization of the lamellar domains. In particular, the impact of the annealing conditions and geometric parameters of the substrate patterns have been investigated. The nanopatterns resulting from the lamellar demixion of (PS‐b‐MMA) were used for a controlled deposition of nanoparticles. The affinity of the hydrophobic particles for the PS block was demonstrated, opening new doors towards the preparation of high‐density arrays of nanoparticles with potential applications in data storage.

magnified image
A simple and low‐cost device for generating hyperpolarized contrast agents using parahydrogen
Authors: Kadlecek Stephen , Vahdat Vahid , Nakayama Takeshi , Ng Danny , Emami Kiarash , Rizi Rahim
Published: August 2011

A detailed description of the construction and use of a device for hyperpolarization of select contrast agents is presented. The device is based on molecular incorporation of the spin‐order inherent to parahydrogen, followed by order transfer to a metastable heteronuclear alignment. Design considerations and experimental results relating to catalyst/solvent choice and handling, solvent heating, efficient gas entrainment and spin‐order transfer are described. The resulting degree of hyperpolarization is shown to be substantial, ranging from a few to over 50%, depending on the choice of target molecule. Finally, the use of the hyperpolarized agent is demonstrated in a series ofin vivoimages. Copyright © 2011 John Wiley & Sons, Ltd.
The significance of serial histopathology in a residual mass for outcome of intermediate risk stage 3 neuroblastoma
Authors: Marachelian Araz , Shimada Hiroyuki , Sano Hideki , Jackson Hollie , Stein James , Sposto Richard , Matthay Katherine K. , Baker David , Villablanca Judith G.
Published: August 2011

Background

To describe the serial histopathology of intermediate risk stage 3 neuroblastoma after chemotherapy, and correlate with residual mass at therapy completion and outcome.

Procedure

A retrospective review of intermediate risk stage 3 neuroblastoma patients treated 1989–2005 at Children's Hospital Los Angeles according to CCG 3881 or CCG 3961 protocols was performed, with central review of histopathology, radiology, and surgery.

Results

Eighteen patients treated per CCG 3881 (n = 9) or CCG 3961 (n = 9), with including 1 (n = 5), 2 (n = 9), ≥3 (n = 3), or unknown number (n = 1) of surgical procedures were included. At therapy completion, 10 patients had residual tumor: <10% original size (n = 3), >10% original size (n = 6) (5 MIBG avid; 4 with elevated catecholamines), and CT non‐measurable MIBG avid tumor (n = 1). Post‐chemotherapy histology showed tumor regression (n = 4); or maturation with (n = 6) or without (n = 2) Schwannian development. Histologic changes correlated with median tumor shrinkage of 80% (regressing tumors) and <25% (maturing tumors). Tumor size increased in one patient with maturing tumor and Schwannian development. Overall survival was 100%.

Conclusion

Post‐chemotherapy histopathology of intermediate risk stage 3 neuroblastoma was characterized by regression or maturation. Persisting residual and maturing tumors were not associated with tumor progression, despite MIBG uptake and/or elevated catecholamines, supporting observation only. Histopathology should be obtained in future studies to confirm these findings, and guide length of chemotherapy. Pediatr Blood Cancer 2012; 58: 675–681. © 2011 Wiley Periodicals, Inc.
Initial testing (stage 1) by the pediatric preclinical testing program of RO4929097, a γ‐secretase inhibitor targeting notch signaling
Authors: Kolb E. Anders , Gorlick Richard , Keir Stephen T. , Maris John M. , Lock Richard , Carol Hernan , Kurmasheva Raushan T. , Reynolds C. Patrick , Kang Min H. , Wu Jianrong , Houghton Peter J. , Smith Malcolm A.
Published: August 2011

RO4929097 is a potent and selective inhibitor of γ‐secretase and as a result is able to inhibit Notch pathway signaling. The activity of RO4929097 was evaluated against the in vivo panels of the Pediatric Preclinical Testing Program (PPTP). RO4929097 induced significant differences in event‐free survival (EFS) distribution compared to control in 6 of 26 (23%) of the evaluable solid tumor xenografts and in 0 of 8 (0%) of the evaluable ALL xenografts. The most consistent tumor growth delay effects were noted in the osteosarcoma panel. RO4929097 at the dose and schedule evaluated demonstrated little antitumor activity against childhood cancer xenografts. Pediatr Blood Cancer 2012; 58: 815–818. © 2011 Wiley Periodicals, Inc.
TP53 codon 72 polymorphisms in favorable histology Wilms tumors
Authors: Cost Nicholas G. , Mitui Midori , Khokhar Shama , Wickiser Jonathan E. , Baker Linda A. , Rakheja Dinesh
Published: August 2011

In Wilms tumor (WT), mutations in the gene encoding p53, TP53, are correlated with anaplasia; however TP53 variants have not been studied in favorable histology (FH) WTs. A single nucleotide polymorphism of TP53 encoding either arginine or proline at codon 72 is suggested to alter in vitro p53 behavior. Therefore, we analyzed tissue from 23 consecutive patients with FHWT to determine allelic and genotypic frequencies of Pro72 and Arg72 variants and correlate this with clinical outcomes. Interestingly, our cohort showed a statistically significant over‐representation of the Arg allele and Arg/Arg genotype. However, the genotypic and allelic frequencies showed no significant correlation with age, stage, or disease recurrence. Pediatr Blood Cancer 2012;59:326–328. © 2011 Wiley Periodicals, Inc.
Chemical reactivity of lithium‐doped fullerenes
Authors: Denis Pablo A.
Published: August 2011

The addition of free radicals and the 1,3 dipolar cycloaddition onto pristine and lithium‐doped C60 were studied by means of the Perdew–Burke–Ernzerhof (PBE) and M06‐2X density functionals. In all cases, lithium increased the reactivity even though for the 1,3 dipolar cycloaddition onto C60 the change observed with respect to bare C60 was minimal. Both functionals employed gave similar encapsulation energies for Li@C60 namely, 33.1 and 38.2 kcal/mol at the PBE/6‐31G* and M06‐2X/6‐31G*, respectively. However, the increased reactivity because of lithium doping determined at the PBE level is smaller as compared with that computed with the M06‐2X functional, whereas that determined at the second‐order Møller–Plesset (MP2) level is the largest one. For example, using the M06‐2X functional the binding energy of fluorine to Li@C60 is 28.5 kcal/mol larger than that determined for C60, whereas at the PBE/6‐31G* level it is predicted to be increased by 24.7 kcal/mol. The results clearly suggest that Li@C60 is a much better free radical scavenger than C60. Finally, the complex hindered rotations of lithium inside C60 are expected to be strongly inhibited because lithium doping increases the well depth between the cage center and the equilibrium position near the addition site of the lithium atom. Copyright © 2011 John Wiley & Sons, Ltd.
Statistical Monitoring of Time‐to‐Failure Data Using Rank Tests
Authors: Li Zhiguo , Zhou Shiyu , Sievenpiper Crispian , Choubey Suresh
Published: August 2011

A common type of reliability data is the right censored time‐to‐failure data. In this article, we developed a control chart to monitor the time‐to‐failure data in the presence of right censoring using weighted rank tests. On the basis of the asymptotic properties of the rank statistics, we derived the generic formulae for the operating characteristic functions of the control chart to show the relationship between type I error probability, type II error probability, sample size, and hazard rate change. We presented case studies to illustrate the design procedure and the effectiveness of the proposed control chart system. We also investigated and compared the performance of the proposed monitoring procedure with some available monitoring techniques for nonconformities. Copyright © 2011 John Wiley & Sons, Ltd.
Qualitative and quantitative topographical surface investigation and solvent effects on internal surface of polypropylene tubes
Authors: Barbosa Eduardo F. , Silva Luciano P.
Published: August 2011

An alternative way for plastic tubes surface analysis was presented, and the time course of the effects of solvent exposure was evaluated. Atomic force microscopy was used to qualitatively and quantitatively analyze internal tubes topography. Differences in nanoroughness parameters were shown as potential markers for quality control check to detect differences among brands and areas along each tube. Mass spectrometry analysis was carried out to evaluate the effects of some solvents after the intrinsic contact with the polymer. The obtained spectra did not allow the visualization of any leaching component, suggesting a low rate of some possible reaction or dissociative interaction caused by polymer and tested solvent interactions that were in concordance with principal component analysis. The use of these techniques as tools for quality control evaluation, or search for new support to biomolecules immobilization can be seen as important innovations and can be applied in several other investigative and developmental approaches. Copyright © 2011 John Wiley & Sons, Ltd.
Fabrication of Silicon/Polymer Composite Nanopost Arrays and Their Sensing Applications
Authors: Li Yunfeng , Zhang Junhu , Fang Liping , Wang Tieqiang , Zhu Shoujun , Li Yang , Wang Zhanhua , Zhang Liang , Cui Liying , Yang Bai
Published: August 2011

A novel technique is reported for fabricating silicon/polymer composite nanopost arrays by combining colloidal lithography and surface‐initiated atom‐transfer radical polymerization. The composite nanopost arrays possess a core/shell nanoarchitecture, with shells of poly(2‐hydroxyethyl methacrylate) and cores of silicon nanoposts. The polymer brush possesses quasi‐3D homogeneous nanoarchitectures due to the controllable polymerization process using the surface‐initiated atom‐transfer radical polymerization technique. The composite nanopost arrays are durable due to the particular nanoarchitectures. The backbone templates of the composites are silicon nanopost arrays directly etched from silicon substrates, and the polymer shell is covalently grafted from the arrays. The composite nanopost arrays exhibit vivid colors. Moreover, the colors of the composite nanopost arrays can be tuned from green to red by changing the thickness of film. Specifically, the composite nanopost arrays can be used as sensors to rapidly detect water vapors with high stability and reproducibility. Many different functional surfaces could be prepared through this technique using other functional monomers.
Effects of Water Molecules on Photoluminescence from Hierarchical Peptide Nanotubes and Water Probing Capability
Authors: Wang Minjie , Xiong Shijie , Wu Xinglong , Chu Paul K.
Published: August 2011

Photoluminescence (PL) spectra reveal that deficiency of water molecules in the channel cores of bioinspired hierarchical diphenylalanine (L‐Phe‐L‐Phe, FF) peptide nanotubes (PNTs) not only modifies the bandgap of the subnanometer crystalline structure formed by the self‐assembly process, but also induces a characteristic ultraviolet PL peak the position of which is linearly proportional to the number of water molecules in the PNTs. Addition or loss of water molecules gives rise to the UV PL redshift or blueshift. Density functional theory calculation also confirms that addition of water molecules to the PNTs causes splitting of the valence‐band peak, which corresponds to the shift and splitting of the observed UV PL peak. Water molecules play an important role in the biological properties of FF PNTs and the results demonstrate that the PL spectra can be used to probe the number of water molecules bonded to the FF molecules.
Multiple‐encoder layered space–time–frequency architecture with QR decomposition and M‐algorithm maximum‐likelihood detection
Authors: Huang Yuanliang
Published: August 2011

In this paper, to achieve the available spatial, temporal, and frequency diversities, and also to make the system implementation feasible for high‐speed orthogonal frequency division multiplexing multiple‐input multiple‐output multiplexing, a novel layered space–time–frequency (LSTF) transmitter architecture with multiple channel encoders is proposed with each independently coded information sub‐stream being threaded in the three‐dimensional (3‐D) space–time–frequency transmission resource array. The performance of a non‐iterative receiver consisting of a maximum‐likelihood detector with QR decomposition and M‐algorithm maximum‐likelihood detection is exploited, by employing irregular low‐density parity‐check code as the channel code. The threaded distribution of each coded information sub‐stream in the proposed LSTF architecture makes it achieve the spatial, temporal, and frequency diversities the same as the conventional single‐encoder LSTF architecture where coding is applied across the whole information stream, and simulation results show that the performance of the proposed multiple‐encoder LSTF architecture is very close to that of the conventional single‐encoder LSTF architecture. However, because of the use of multiple parallel encoders/decoders with a shorter codeword length, the proposed LSTF architecture has much lower hardware processing speed and complexity than that of the conventional LSTF architecture. Copyright © 2011 John Wiley & Sons, Ltd.
Characterization of the Energetic Plasticizer Methyl‐NENA
Authors: Izsák Dániel , Klapötke Thomas M.
Published: August 2011

The energetic plasticizer N‐methyl‐N‐(2‐nitroxyethyl)nitramine (2) and its precursor N‐methyl‐N‐(2‐nitroxyethyl)ammonium nitrate (1) were synthesized by nitration of 2‐(methylamino)ethanol and characterized by X‐ray crystallography, multinuclear NMR spectroscopy (1H, 13C, 14N), vibrational spectroscopy (IR and Raman), mass spectrometry and differential thermal analysis. The sensitivities were determined according to BAM methods and the detonation parameters were calculated with the EXPLO5 computer program to identify them as potentially explosive compounds.
The molecular basis of neurodegeneration in multiple sclerosis
Authors: Lassmann Hans , van Horssen Jack
Published: August 2011

Studies aimed to elucidate the pathogenesis of the disease and to find new therapeutic options for multiple sclerosis (MS) patients heavily rely on experimental autoimmune encephalomyelitis (EAE) as a suitable experimental model. This strategy has been highly successful for the inflammatory component of the disease, but had so far little success in the development of neuroprotective therapies, which are also effective in the progressive stage of the disease. Here we discuss opportunities and limitations of EAE models for MS research and provide an overview on the complex mechanisms leading to demyelination and neurodegeneration in this disease. We suggest that the underlying mechanisms involve adaptive and innate immunity. However, mitochondrial injury, resulting in energy failure, is a key element of neurodegeneration in MS and is apparently driven by radical production in activated microglia.
P–Tevolution and timing of a late Palaeozoic fore-arc system and its heterogeneous Mesozoic overprint in north-central Chile (latitudes 31–32°S)
Authors: WILLNER ARNE P. , MASSONNE HANS-JOACHIM , RING UWE , SUDO MASAFUMI , THOMSON STUART N.
Published: August 2011

In the late Palaeozoic fore-arc system of north-central Chile at latitudes 31–32°S (from the west to the east) three lithotectonic units are telescoped within a short distance by a Mesozoic strike-slip event (derived peakP–Tconditions in brackets): (1) the basally accreted Choapa Metamorphic Complex (CMC; 350–430°C, 6–9 kbar), (2) the frontally accreted Arrayán Formation (AF; 280–320°C, 4–6 kbar) and (3) the retrowedge basin of the Huentelauquén Formation (HF; 280–320°C, 3–4 kbar). In the CMC, Ar–Ar spot ages locally date white-mica formation at peakP–Tconditions and during early exhumation at 279–242 Ma. In a local garnet mica-schist intercalation (570–585°C, 11–13 kbar) Ar–Ar spot ages refer to the ascent from the subduction channel at 307–274 Ma. Portions of the CMC were isobarically heated to 510–580°C at 6.6–8.5 kbar. The age of peakP–Tconditions in the AF can only vaguely be approximated at ≥ 310 Ma by relict fission-track ages consistent with the observation that frontal accretion occurred prior to basal accretion. Zircon fission-track dating indicates cooling below ~ 280°C at ~ 248 Ma in the CMC and the AF, when a regional unconformity also formed. Ar–Ar white-mica spot ages in parts of the CMC and within the entire AF and HF point to heterogeneous resetting during Mesozoic extensional and shortening events at ~ 245–240 Ma, ~ 210–200 Ma, ~ 174–159 Ma and ~ 142–127 Ma. The zircon fission-track ages are locally reset at 109–96 Ma. All resetting of Ar–Ar white-mica ages is proposed to have occurred byin situdissolution/precipitation at low temperature in the presence of locally penetrating hydrous fluids. Hence syn- and postaccretionary events in the fore-arc system can still be distinguished and dated in spite of its complex heterogeneous postaccretional overprint.
Spectrum of radiological appearances of necrotising external otitis: a pictorial review
Authors: Mehrotra P , Elbadawey M R , Zammit-Maempel I
Published: August 2011

Necrotising external otitis, also known as malignant otitis externa, is an aggressive, resorptive osteomyelitis of the temporal bone. Although rare, necrotising external otitis is a potentially fatal disease, with complications which include temporomandibular joint osteomyelitis, sigmoid sinus thrombosis and meningitis. Imaging findings may be subtle, particularly in the early stages. We present a broad range of imaging findings which may occur in necrotising external otitis cases.
Wegener's granulomatosis mimicking skull base osteomyelitis
Authors: Sharma A , Deshmukh S , Shaikh A , Dabholkar J
Published: August 2011

Objective:

To report a case of Wegener's granulomatosis mimicking skull base osteomyelitis.

Case report:

A case of Wegener's granulomatosis is reported in a diabetic woman presenting with facial palsy and hearing loss. The clinical course of the disease was very similar to that of skull base osteomyelitis, especially since the patient was diabetic and the ear swab was positive for pseudomonas. The definitive diagnosis was made based on clinical presentation, imaging and serum antineutrophil cytoplasmic antibody testing. The patient was started on immunosuppressants, and her hearing loss and facial palsy recovered.

Conclusion:

Wegener's granulomatosis is a systemic disease with various manifestations. A high index of clinical suspicion is required to reach the correct diagnosis. The clinician should be alerted to the possibility of Wegener's granulomatosis in the presence of: systemic upset out of proportion to the apparent intensity of the local lesion; middle-ear disease failing to respond to conventional treatment; and a consistently raised erythrocyte sedimentation rate.
A study of the effect on accuracy of the introduction of a bellyboard as an immobilisation device to the radical radiotherapy treatment of prostate cancer patients
Authors: McIlwraith K A , Blyth C
Published: August 2011

Ensuring reproducibility in any radiotherapy technique is vital to ensure that a geometric miss does not occur. Patient position and comfort play a major part in the reproducibility of setups.

Purpose: To study the effect on accuracy of the introduction of a bellyboard to the existing prone technique used for radical radiotherapy treatment of prostate cancer.

Materials and Methods: Thirty patients were treated using the bellyboard in the standard method. Portal images were compared with those of a control group of patients who had treatment with no rigid immobilisation. Patients in both groups were males with prostate cancer, who underwent radical radiotherapy treatment. Images were analysed using anatomy matching, and deviations from the isocentre were noted.

Results: Statistical analysis of the results showed no statistical significance between the groups, though within the control group there were more deviations over 0.5 cm from the isocentre position than in the bellyboard group.

Conclusions: Introduction of the bellyboard was seen to be equivalent to the use of the control technique. When the deviations from isocentre position were evaluated for each group, the control group had more deviations over 0.5 cm than the bellyboard group.
Numerical validations of neural‐network‐based ionospheric tomography for disturbed ionospheric conditions and sparse data
Authors: Hirooka S. , Hattori K. , Takeda T.
Published: August 2011

Three‐dimensional ionospheric tomography is effective for investigations of the dynamics of ionospheric phenomena. However, it is an ill‐posed problem in the context of sparse data, and accurate electron density reconstruction is difficult. The Residual Minimization Training Neural Network (RMTNN) tomographic approach, a multilayer neural network trained by minimizing an objective function, allows reconstruction of sparse data. In this study, we validate the reconstruction performance of RMTNN using numerical simulations based on both sufficiently sampled and sparse data. First, we use a simple plasma‐bubble model representing the disturbed ionosphere and evaluate the reconstruction performance based on 40 GPS receivers in Japan. We subsequently apply our approach to a sparse data set obtained from 24 receivers in Indonesia. The reconstructed images from the disturbed and sparse data are consistent with the model data, except below 200 km altitude. To improve this performance and limit any discrepancies, we used information on the electron density in the lower ionosphere. The results suggest the restricted RMTNN‐tomography‐assisted approach is very promising for investigations of ionospheric electron density distributions, including studies of irregular structures in different regions. In particular, RMTNN constrained by low‐Earth‐orbit satellite data is effective in improving the reconstruction accuracy.
Ball Milling as a Tool Towards Solubility Problems in Synthesis – Simple and Solvent-free Preparation of K[B(CN)4]
Authors: Pawelke Roland
Published: August 2011

A simple ball milling route to the tetrayanoborate anion is presented: The K[B(CN)4] synthesis is one fine example, how a synthesis problem based on solubility may be solved by a ball milling approach. The solid state 13C- and 11B-MAS-NMR spectra have been recorded.
Urban development, power relations, and water redistribution as drivers of wetland change in the Tampa Bay Region Socioecosystem
Authors: Crisman Thomas , Larsen Gina , Trettin Carl , Perkerson Ralph , Nilsson Kenneth , Thurman Paul , Adjei Cornelius , Lewis David , Akiwumi Fenda , Landry Shawn , Zarger Rebecca , Rains Mark , Feit Sharon , Bell Susan
Published: August 2011

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Single-magnet rotary flowmeter for liquid metals
Authors: Priede Jānis , Buchenau Dominique , Gerbeth Gunter
Published: August 2011

We present a theory of single-magnet flowmeter for liquid metals and compare it with experimental results. The flowmeter consists of a freely rotating permanent magnet, which is magnetized perpendicularly to the axle it is mounted on. When such a magnet is placed close to a tube carrying liquid metal flow, it rotates so that the driving torque due to the eddy currents induced by the flow is balanced by the braking torque induced by the rotation itself. The equilibrium rotation rate, which varies directly with the flow velocity and inversely with the distance between the magnet and the tube, is affected neither by the electrical conductivity of the metal nor by the magnet strength. We obtain simple analytical solutions for the force and torque on slowly moving and rotating magnets due to eddy currents in a layer of infinite horizontal extent. The predicted equilibrium rotation rates qualitatively agree with the magnet rotation rate measured on a liquid sodium flow in stainless steel duct.
Impedance and modulus studies of magnetic ceramic oxide Ba2Co2Fe12O22 (Co2Y) doped with Bi2O3
Authors: Costa M. M. , Pires G. F. M. , Terezo A. J. , Graça M. P. F. , Sombra A. S. B.
Published: August 2011

Polycrystalline samples of a layered magnetic ceramic oxide, Ba2Co2Fe12O22 (Co2Y), doped with Bi2O3 were prepared by the solid state reaction method. The dielectric impedance properties were studied over the range of frequency between 1 Hz–1MHz and in the temperature range of 313–493 K, using the modulus formalism. The impedance plot showed a first semicircle at high frequency which was assigned to the grain intrinsic effect and a second semicircle, at lower frequencies, which corresponds to grain boundary polarization (conduction phenomenon). A complex modulus spectrum was used to understand the mechanism of the electrical transport process, which indicates that a non-exponential type of conductivity relaxation characterizes this material. The values of the activation energy of the compound (calculated both from dc conductivity and the modulus spectrum) are very similar, suggesting that the relaxation process may be attributed to the same type of charge carriers. The dielectric measurements were studied by fitting the electrical modulus with the Havriliak–Negami function, including the conductivity parameters. The study demonstrates that the investigation of dielectric relaxation, conductivity, and loss of the ferrite materials, as a function of temperature, are essential for future microwave absorption applications of this material.
Effect of a floating electrode on an atmospheric-pressure non-thermal arc discharge
Authors: Wang Zhi-Bin , Chen Guo-Xu , Wang Zhe , Ge Nan , Li He-Ping , Bao Cheng-Yu
Published: August 2011

Characteristics of the atmospheric non-thermal ac arc air plasmas produced by a plasma generator with a floating electrode are investigated. The measurements show that, with the help of the surface dielectric barrier discharges between the main electrodes and the floating electrode, the ignition voltage of the non-thermal arc discharges can be reduced significantly, and an arc discharge mode can be stabilized at high gas flow rates. The measured temperatures of the non-thermal arcs are at the level of 2000–3000 K under different operating conditions.
Susceptor assisted microwave annealing for recrystallization and dopant activation of arsenic-implanted silicon
Authors: Vemuri Rajitha N. P. , Gadre Mandar J. , Theodore N. D. , Chen W. , Lau S. S. , Alford T. L.
Published: August 2011

The increasing need for quicker and more efficient processing techniques motivates the study of the use of a single frequency applicator microwave cavity, along with an alumina-coated SiC susceptor, as an alternative to current post-implantation processing. The extent of Si recrystallization and repair of the damage caused by arsenic implantation into Si is determined by cross-section transmission electron microscopy and Raman spectroscopy. Dopant activation is evaluated by sheet resistance measurements. Secondary ion mass spectroscopy is used to compare the extent of diffusion that results from such microwave annealing with that experienced when using conventional rapid thermal annealing (RTA). The results show that, compared to susceptor-assisted microwave annealing, RTA caused undesired dopant diffusion. The SiC-alumina susceptor plays a significant role in supplying heat to the Si substrate and also acts as an assistor that helps a high-Z dopant, like arsenic, to absorb the microwave energy, using a microwave loss mechanism, which is a combination of ionic and dipole losses.
Magnetic and magnetoelectric properties of Ba2-xSrxNi2Fe12O22 single crystals with Y-type hexaferrite structure
Authors: Hiraoka Yuji , Nakamura Hiroyuki , Soda Minoru , Wakabayashi Yusuke , Kimura Tsuyoshi
Published: August 2011

We studied the magnetic and magnetoelectric properties of Ba2-xSrxNi2Fe12O22 single crystals over a wide composition range (0 ≤ x ≤ 1.5). All the crystals show a ferrimagnetic order at around 660 K. While a Sr-free crystal is simply ferrimagnetic down to the lowest temperature, a transition from the ferrimagnetic into a screw magnetic ordered state was observed at temperatures below 300 K in Sr-substituted crystals. The transition temperature monotonically increases with increasing Sr content, meaning that the screw ordered state is stabilized by the Sr-substitution. By applying a magnetic field perpendicular to the hexagonal c axis, the samples showing the ground-state screw order undergo successive metamagnetic transitions and exhibit magnetically induced ferroelectricity in some of the intermediate magnetic phases. In an intermediate magnetic phase, the largest electric polarization emerges (2 × 102 μC/m2 for x = 1.5 crystal), i.e., magnetoelectric effect. The evolution of the magnetic structures related to the magnetoelectric effect in x = 1.5 crystal was clarified by means of in-field neutron diffraction measurements. Though the magnetoelectric effect in the as-grown crystal was measurable only below ∼100 K due to its low resistivity, a post-annealing drastically enhances the resistivity and allows us to observe the magnetically induced ferroelectricity up to ∼175 K.
Reduction of lattice defects in proton-exchanged lithium niobate waveguides
Authors: Muller Heinrich G. , Stapleton Andrew D. , Foran Brendan J. , Radhakrishnan Gouri , Kim Hyun I. , Adams Paul M. , Lipeles Russell A. , Herman Paul
Published: August 2011

It is shown that the formation of water at the surface of protonated LiNbO3 can lead to the precipitation of disordered phases, causing undesirable degradation of the electro-optic properties of the material. These structural defects are observed to increase the conductivity, which leads to a slow build-up of space charges, believed to be a key reason for voltage bias drifts in LiNbO3 electro-optic devices. Annealing under a controlled partial pressure of water vapor is shown to minimize such damage to the crystal lattice. An additional reverse exchange process is proposed that further improves the stability of the crystal and its electro-optic properties.
Electromechanical response of (3-0) porous piezoelectric materials: Effects of porosity shape
Authors: Iyer Sumantu , Venkatesh T. A.
Published: August 2011

A three-dimensional finite element model is developed to accurately predict the complete electromechanical properties of porous piezoelectric materials with four geometric configurations of porosity, i.e., 3-0 type flat-cuboidal, 3-0 type spherical, 3-0 type short-cylindrical, and 3-1 type long-cylindrical porosity. The three-dimensional finite element model characterizes the complete electromechanical response of materials that belong to several symmetry classes, i.e., barium titanate (6mm), barium sodium niobate (mm2), and lithium niobate (3m). In general, the elastic, piezoelectric, and dielectric properties vary monotonically with increase in porosity volume fraction with the material properties in the longitudinal direction being the highest for the case of the materials with the 3-1 type long-cylindrical porosity for all three symmetry classes. The piezoelectric charge coefficient (dh) and the hydrostatic figure of merit (dh·gh) of the porous piezoelectric materials with the 3-0 type flat-cuboidal porosity are found to be significantly higher than those of the piezoelectric materials with spherical or short-cylindrical porosity. For example, in the barium titanate system, the differences in the dh and dh·gh values between the materials with the 3-0 type flat-cuboidal porosity and the materials with the 3-1 type long-cylindrical porosity are observed to be 223% and 1818% respectively, at 30% porosity volume fraction. Hence, piezoelectric materials with the 3-0 type flat-cuboidal porosity (that exhibit low aspect ratios with respect to the poling direction) could be better suited for hydrophone applications.
Onset of sphalerite to wurtzite transformation in ZnS nanoparticles
Authors: Sekhar Tiwary Chandra , Srivastava Chandan , Kumbhakar Pathik
Published: August 2011

In this work, the incubation period for the onset of sphalerite to wurtzite transformation in isolated ZnS nanoparticles 2 to 7 nm in size was determined via the in situ isothermal annealing of as-synthesized sphalerite nanoparticles in a transmission electron microscope (TEM). Nanoparticles sitting on the TEM grid were well separated from each other in order to minimize particle sintering during the annealing operation. The phase transformation onset was observed at 300 °C, 350 °C, and 400 °C after 90, 10, and 4 min, respectively. These time-temperature data for the phase transformation onset were then used to calculate the activation energy for the nucleation of the wurtzite phase in 2 to 7 nm sphalerite particles. The activation energy determined was 24 Kcal/mol.
Architecture of human telomerase RNA
Authors: Zhang Qi , Kim Nak-Kyoon , Feigon Juli
Published: August 2011

Telomerase is a unique reverse transcriptase that catalyzes the addition of telomere DNA repeats onto the 3′ ends of linear chromosomes and plays a critical role in maintaining genome stability. Unlike other reverse transcriptases, telomerase is unique in that it is a ribonucleoprotein complex, where the RNA component [telomerase RNA (TR)] not only provides the template for the synthesis of telomere DNA repeats but also plays essential roles in catalysis, accumulation, TR 3′-end processing, localization, and holoenzyme assembly. Biochemical studies have identified TR elements essential for catalysis that share remarkably conserved secondary structures across different species as well as species-specific domains for other functions, paving the way for high-resolution structure determination of TRs. Over the past decade, structures of key elements from the core, conserved regions 4 and 5, and small Cajal body specific RNA domains of human TR have emerged, providing significant insights into the roles of these RNA elements in telomerase function. Structures of all helical elements of the core domain have been recently reported, providing the basis for a high-resolution model of the complete core domain. We review this progress to determine the overall architecture of human telomerase RNA.
Large-scale navigational map in a mammal
Authors: Tsoar Asaf , Nathan Ran , Bartan Yoav , Vyssotski Alexei , Dell'Omo Giacomo , Ulanovsky Nachum
Published: August 2011

Navigation, the ability to reach desired goal locations, is critical for animals and humans. Animal navigation has been studied extensively in birds, insects, and some marine vertebrates and invertebrates, yet we are still far from elucidating the underlying mechanisms in other taxonomic groups, especially mammals. Here we report a systematic study of the mechanisms of long-range mammalian navigation. High-resolution global positioning system tracking of bats was conducted here, which revealed high, fast, and very straight commuting flights of Egyptian fruit bats (
Rousettus aegyptiacus
) from their cave to remote fruit trees. Bats returned to the same individual trees night after night. When displaced 44 km south, bats homed directly to one of two goal locations—familiar fruit tree or cave—ruling out beaconing, route-following, or path-integration mechanisms. Bats released 84 km south, within a deep natural crater, were initially disoriented (but eventually left the crater toward the home direction and homed successfully), whereas bats released at the crater-edge top homed directly, suggesting navigation guided primarily by distal visual landmarks. Taken together, these results provide evidence for a large-scale “cognitive map” that enables navigation of a mammal within its visually familiar area, and they also demonstrate the ability to home back when translocated outside the visually familiar area.