bluuebunny/crossref_metadata_2025 huggingface dataset:
SRPK2 Phosphorylates Tau and Mediates the Cognitive Defects in Alzheimer's Disease
Authors: Hong Yi , Chan Chi Bun , Kwon Il-Sun , Li Xuekun , Song Mingke , Lee Hyun-Pil , Liu Xia , Sompol Pradoldej , Jin Peng , Lee Hyoung-gon , Yu Shan Ping , Ye Keqiang
Published: November 2012

Serine-arginine protein kinases 2 (SRPK2) is a cell cycle-regulated kinase that phosphorylates serine/arginine domain-containing proteins and mediates pre-mRNA splicing with unclear function in neurons. Here, we show that SRPK2 phosphorylates tau on S214, suppresses tau-dependent microtubule polymerization, and inhibits axonal elongation in neurons. Depletion of SRPK2 in dentate gyrus inhibits tau phosphorylation in APP/PS1 mouse and alleviates the impaired cognitive behaviors. The defective LTP in APP/PS1 mice is also improved after SRPK2 depletion. Moreover, active SRPK2 is increased in the cortex of APP/PS1 mice and the pathological structures of human Alzheimer's disease (AD) brain. Therefore, our study suggests SRPK2 may contribute to the formation of hyperphosphorylated tau and the pathogenesis of AD.
Sensory Neuron Downregulation of the Kv9.1 Potassium Channel Subunit Mediates Neuropathic Pain following Nerve Injury
Authors: Tsantoulas Christoforos , Zhu Lan , Shaifta Yasin , Grist John , Ward Jeremy P. T. , Raouf Ramin , Michael Gregory J. , McMahon Stephen B.
Published: November 2012

Chronic neuropathic pain affects millions of individuals worldwide, is typically long-lasting, and remains poorly treated with existing therapies. Neuropathic pain arising from peripheral nerve lesions is known to be dependent on the emergence of spontaneous and evoked hyperexcitability in damaged nerves. Here, we report that the potassium channel subunit Kv9.1 is expressed in myelinated sensory neurons, but is absent from small unmyelinated neurons. Kv9.1 expression was strongly and rapidly downregulated following axotomy, with a time course that matches the development of spontaneous activity and pain hypersensitivity in animal models. Interestingly, siRNA-mediated knock-down of Kv9.1 in naive rats led to neuropathic pain behaviors. Diminished Kv9.1 function also augmented myelinated sensory neuron excitability, manifested as spontaneous firing, hyper-responsiveness to stimulation, and persistent after-discharge. Intracellular recordings fromex vivodorsal root ganglion preparations revealed that Kv9.1 knock-down was linked to lowered firing thresholds and increased firing rates under physiologically relevant conditions of extracellular potassium accumulation during prolonged activity. Similar neurophysiological changes were detected in animals subjected to traumatic nerve injury and provide an explanation for neuropathic pain symptoms, including poorly understood conditions such as hyperpathia and paresthesias. In summary, our results demonstrate that Kv9.1 dysfunction leads to spontaneous and evoked neuronal hyperexcitability in myelinated fibers, coupled with development of neuropathic pain behaviors.
Mechanisms Generating Dual-Component Nicotinic EPSCs in Cortical Interneurons
Authors: Bennett Corbett , Arroyo Sergio , Berns Dominic , Hestrin Shaul
Published: November 2012

Activation of cortical nicotinic receptors by cholinergic axons from the basal forebrain (BF) significantly impacts cortical function, and the loss of nicotinic receptors is a hallmark of aging and neurodegenerative disease. We have previously shown that stimulation of BF axons generates a fast α7 and a slow non-α7 receptor-dependent response in cortical interneurons. However, the synaptic mechanisms that underlie this dual-component nicotinic response remain unclear. Here, we report that fast α7 receptor-mediated EPSCs in the mouse cortex are highly variable and insensitive to perturbations of acetylcholinesterase (AChE), while slow non-α7 receptor-mediated EPSCs are reliable and highly sensitive to AChE activity. Based on these data, we propose that the fast and slow nicotinic responses reflect differences in synaptic structure between cholinergic varicosities activating α7 and non-α7 classes of nicotinic receptors.
Enhanced cAMP Response Element-Binding Protein Activity Increases Neuronal Excitability, Hippocampal Long-Term Potentiation, and Classical Eyeblink Conditioning in Alert Behaving Mice
Authors: Gruart Agnès , Benito Eva , Delgado-García José M. , Barco Angel
Published: November 2012

The activity-regulated transcription factor cAMP response element-binding protein (CREB) is an essential component of the molecular switch that controls the conversion of short-term into long-term forms of plasticity, including those underlying long-term memory. Previous research in acute brain slices of transgenic animals expressing constitutively active CREB variants has revealed that enhancing CREB activity increases the intrinsic excitability of neurons and facilitates the late phase of long-term potentiation (LTP) in the Schaffer collateral pathway. Here, we report similar changes in plasticity at the Schaffer collateral pathway in alert behaving mice. Forebrain expression of a strong constitutively active CREB variant, VP16–CREB, enhancedin vivoLTP evoked in the Schaffer collateral pathway and caused significant changes in the input/output curve and paired-pulse facilitation in CA3–CA1 synapses, which could be explained by the increased excitability of hippocampal pyramidal neurons. In addition, classical eyeblink conditioning in transgenic mice and control littermates showed larger conditioned responses in mutant mice that were associated to a transient increase in the acquisition rate and in the concomitant learning-dependent change in synaptic strength. The sustained chronic activation of CREB activity, however, impaired the performance in this task. Our experiments demonstrate that the sustained enhancement of CREB function alters the physiology and plasticity of hippocampal circuits in behaving animals and that these changes have important consequences in associative learning.
Channel Noise from Both Slow Adaptation Currents and Fast Currents Is Required to Explain Spike-Response Variability in a Sensory Neuron
Authors: Fisch Karin , Schwalger Tilo , Lindner Benjamin , Herz Andreas V. M. , Benda Jan
Published: November 2012

Spike-timing variability has a large effect on neural information processing. However, for many systems little is known about the noise sources causing the spike-response variability. Here we investigate potential sources of spike-response variability in auditory receptor neurons of locusts, a classic insect model system. At low-spike frequencies, our data show negative interspike-interval (ISI) correlations and ISI distributions that match the inverse Gaussian distribution. These findings can be explained by a white-noise source that interacts with an adaptation current. At higher spike frequencies, more strongly peaked distributions and positive ISI correlations appear, as expected from a canonical model of suprathreshold firing driven by temporally correlated (i.e., colored) noise. Simulations of a minimal conductance-based model of the auditory receptor neuron with stochastic ion channels exclude the delayed rectifier as a possible noise source. Our analysis suggests channel noise from an adaptation current and the receptor or sodium current as main sources for the colored and white noise, respectively. By comparing the ISI statistics with generic models, we find strong evidence for two distinct noise sources. Our approach does not involve any dendritic or somatic recordings that may harm the delicate workings of many sensory systems. It could be applied to various other types of neurons, in which channel noise dominates the fluctuations that shape the neuron's spike statistics.
Reading “New” Religious Movements Historically
Authors: Jones Douglas FitzHenry
Published: November 2012

This article surveys the relationship of the Heaven's Gate movement to the cultural context of science fiction while also engaging broader issues in the retrospective account of violence in new religious movements. Against theories that see violence as the consequence of social isolation and the escalating confusion of representation and reality, I argue that members of Heaven's Gate were not only “tapped in” to the reality outside the group but were markedly self-conscious about their engagement with that reality through the medium of science fiction. Using Heaven's Gate as an example, I propose that we read the concepts espoused by new religious movements in the past not in light of their fate but rather as imbedded in the historical realities in which they originally functioned in a meaningful and deliberate fashion.
Decline of a Moral Panic
Authors: Reichert Jenny , Richardson James T.
Published: November 2012

Negative perceptions resulting from heavy media exposure surrounding membership in minority religions affect how individuals process information about such group membership. This was apparent in the United States during moral panics in the second half of the twentieth century involving new religious movements (often called “cults”) and individuals actually or allegedly involved in Satanism. This negatively biased information processing presumably carried over into the legal system. One important example involved judges and jurors charged with determining guilt and proper punishment for crimes of persons suspected of Satanist group activity. An analysis of jury decision-making in civil and criminal cases from the height of the Satanism scare in the late 1980s and early 1990s reveals some possibly biased judgments toward individuals and organizations allegedly and admittedly involved in Satanic practice. An examination of more recent legal cases shows that, although media coverage of Satanist groups has diminished, cases still occur in which allegations of Satanic practice may be used as a means of generating bias, illustrating the persistence of such ideas in society. However, courts more recently have become more discerning in dealing with such claims, and with Satanism itself, thus contributing to the decline of moral panic.
From the Unification Church to the Unification Movement and Back
Authors: Bromley David G. , Blonner Alexa
Published: November 2012

Two widely observed patterns in the development of new religious movements are a gradual organizational and theological settling of the movement and a transition in leadership from the founder/leader(s) to their successors.1 We report here on the confluence of these two developments in Unificationism over the last several years. This report is based on personal interviews over the last two years with a number of Unificationist leaders and members involved in managing organizational changes. Information also has been drawn from public and members-only websites where internal conversations and new policies are available. Two principal changes in Unificationist organization have occurred. First, longstanding tensions between established church and social movement forms of organization are being resolved in favor of the former.2 Second, Reverend Sun Myung Moon had begun passing organizational leadership to several of his children before his death in September 2012. Both these processes have involved considerable turmoil, overlapping and interacting with one another, and they offer a unique opportunity to observe and record the process of simultaneous transformations of organization and leadership.
Influence of the Nano-mesh Metal Electrode to Light Excitation of Carriers in Semiconductor
Authors: Masunaga Kumi , Nakamura Kenji , Kitagawa Ryota , Tsutsumi Eishi , Nakanishi Tsutomu , Fujimoto Akira , Nishizawa Hideyuki , Asakawa Koji
Published: November 2012

A thin metal film with nano-apertures, called “nano-mesh electrode,” generates near-field lights near the electrode. We investigated carrier excitations in semiconductors by the near-field light. Finite-difference time-domain (FDTD) method revealed that when the infrared light irradiates the Au nano-mesh electrode on Ge, near-field lights are generated and absorbed in the surface region of the Ge. In order to measure the photocurrent involved by near-filed lights, we fabricated a Schottky cell and applied a Au nano-mesh electrode on the n-type Ge. The efficiency of the Schottky cell with the Au nano-mesh electrode improved in infrared region compared to plain the Au-film Schottky cell. The agreement between theoretical simulations and experiments indicates that near-field lights enhance the carrier excitation in the semiconductor.
Reliability studies of pentacene based thin film transistors
Authors: Ledru R. , Pleutin S. , Grouiez B. , Zander D. , Bejbouji H. , Lmimouni K. , Vuillaume D.
Published: November 2012

The complex admittance of the Si+/SiO2/Pentacene/Au (metal/oxide/pentacene) thin film junctions is investigated under ambient conditions. The results are compared with the ones obtained for the corresponding Si+/SiO2/Au junctions (i.e. a small part of the surface left free from pentacene) which constitutes the “reference” of our samples. This allows us to extract the “organic” part of the dielectric response from the whole spectrum. Our data clearly show that the admittance is decomposed in three main contributions. At low frequencies, a contribution attributed to proton diffusion through the oxide is seen. This diffusion is shown to be anomalous and is believed to be also at the origin of the bias stress effect observed in organic field effect transistors. At higher frequencies, two dipolar contributions are evidenced, attributed to defects located one at the organic/oxide interface or within the organic, and the other in the bulk of the oxide. These two dipolar responses show different dynamic properties that manifest themselves in the admittance in the form of a Debye contribution for the defects located in the oxide, and of a Cole-Cole contribution for the defects related to the organic.
Low-cost lithographically patterned source/drain bottom contacts for high mobility p-type organic thin film transistors
Authors: Mueller Robert , Smout Steve , Willegems Myriam , Genoe Jan , Heremans Paul
Published: November 2012

Short channel organic thin film transistors in bottom-gate, bottom contact configuration use typically gold metallization for the source and drain contacts because this metal can easily be cleaned from photoresist residuals by oxygen plasma or ultraviolet-ozone and allows also surface modification by self-assembled monolayers (e.g. thiols). Alternative low-cost bottom contact metallization for high performance short-channel organic thin film transistors are scarce because of the incompatibility of the bottom contact material with the cleaning step. In this work a new process flow, involving a temporary thin aluminum protection layer, is presented. Short channel (3.4 μm) pentacene transistors with lithographical defined and thiol modified silver source/drain bottom contacts (25 nm thick, on a 2 nm titanium adhesion layer) prepared according to this process achieved a saturation mobility of 0.316 cm2/(V.s), and this at a metal cost below 1% of the standard 30 nm thick gold metallization.
Enhanced 1.5 μm luminescence lifetime of vacuum deposited erbium-doped organic thin films for optical amplification applications
Authors: Galindo Christophe , Divay Laurent , Soyer Françoise , Chastaing Evelyne , Bisaro Renato , Le Barny Pierre
Published: November 2012

Inorganic erbium-doped glasses are widely used in telecommunications due to the sharp intra-atomic 4I13/2 → 4I15/2 transition in the 4f orbital of erbium resulting in an emission at ∼ 1.5 μm, which is the low loss window of silica optical fibres. The limited erbium concentration of about 1020 ions/cm3 in inorganic erbium-doped glasses and the low absorption coefficient of the Er3+ ions, imply that relatively long lengths of fibre are required. Organic erbium complexes present higher absorption cross sections due to the photosensitization of erbium by the organic conjugated ligands and broader emission bands than those of the free Er3+ ions. Such properties open the possibility to develop compact, low power and broadband infrared emitting devices. We present the study of an organic fluorinated erbium complex exhibiting 1.5 μm luminescence lifetime of several hundreds of microseconds measured on thin film. The organic complex has been deposited by vacuum sublimation technique. This deposition method allows the realization of an erbium-doped thin film without the help of an organic polymer matrix, which is a potential source of vibrationnal luminescence quenching. We report the synthesis, the sublimation process, and the characterization of the thin films. The chemical structure of the complex is assessed by FTIR, NMR and MALDI-TOF. Chemical integrity of the thin film after vacuum deposition is determined by FTIR. The morphology of the thin film is characterized by X-ray diffraction experiments. The optical properties of the thin film are determined by spectroscopic ellipsometry, UV-Vis-NIR absorption spectroscopy and time resolved NIR photoluminescence spectroscopy.
Rare-Earth Doped Nanoparticles in Security Printing Applications
Authors: Cross William , Blumenthal Tyler , Kellar Jon , May P. Stanley , Meruga Jeevan , Luu QuocAnh
Published: November 2012

In this work, lanthanide-doped, sodium yttrium fluoride nanocrystals were prepared and dispersed in a solvent consisting of 90 vol% toluene and 10 vol% methyl benzoate. Poly (methyl methacrylate) polymer was dissolved in the solvent, in addition to the nanocrystals. Inks were printed using direct-write techniques. Substrates used included Kapton®, bond paper, metal and glass. Stencil patterns and QR codes were printed with these inks. An overview of direct write printing for security applications is given. On many substrates, these printed traces are difficult to detect in ambient lighting, but can be easily read using near-infrared (NIR) illumination, making them very useful for covert and semi-covert security printing applications.
Preparation of spherical, ordered colloidal aggregates using inkjet printing
Authors: Sowade Enrico , Blaudeck Thomas , Baumann Reinhard R.
Published: November 2012

In this paper we report about combining inkjet printing technology and self-assembly as a scalable manufacturing tool for spherical, well-ordered aggregates. The aggregates consist of a high number of ordered colloidal nanospheres arranged as ball-shaped structures. Applying inkjet printing based on the principle of droplet ejection the spherical aggregates can be deposited on various surfaces in dry environment and under ambient conditions. The aggregation of the nanospheres is independent of the surface energy of the substrate leading to the assumption that the main part of the assembly and aggregation process takes place in-flight [1].

By applying inkjet printing with an adapted control signal, small droplets of a water-based ink formulation containing monodisperse polystyrene nanoparticles are ejected out of the inkjet nozzles. The ejected droplets serve as a confined geometry for the nanospheres in the carrier liquid during evaporation. As a result, the particles form stable ball-shaped aggregates with hexagonal order. Due to the in-flight self-assembly of the nanospheres, our approach is suitable for any solid surface in dry environment and allows the deposition of the ball-shaped aggregates in appropriate patterns.
Roll-to-Roll Graphene Synthesis by Using Microwave Plasma Chemical Vapor Deposition at Low Temperature
Authors: Yamada Takatoshi , Ishihara Masatou , Kim Jaeho , Hasegawa Masataka , Iijima Sumio
Published: November 2012

We reported continuous depositions of grahene films on copper foils with A4 width using roll-to-toll microwave plasma chemical vapor deposition (MWPCVD) technique. A pair of winder and unwinder was built into an MWPCVD apparatus. Surface-wave plasma enabled us to deposit large-area graphene film (substrate stage is of 480 mm x 300 mm) at temperatures below 400 ºC. In Raman spectra, G- and G’-band attributed to graphene were obtained. In addition, Dand D’-band originated from defects and/or edges were detected. These results suggested that the obtained graphene films consisted of flake boundaries and defects. After the transferring graphene onto the polyethylene terephthalate film, uniform transmittance and sheet resistance were confirmed.
High electric insulation and hard protective waterproof coating on metal foil for flexible solar cell and smart paper
Authors: Murahara Masataka , Sato Yuji , Ohkawara Toshio
Published: November 2012

An electric insulation resistant coating has been developed by using photo-oxidized silicone oil. The silicone oil was exposed to ultraviolet⊈light in the air; which transformed the organic silicone oil into an inorganic amorphous glass film. Conventional large-area solar panels and smart papers are made of glass or plastic; in addition to being well insulated, waterproof, transparent, and hard, the panels are desirable to be light in weight and flexible. Here, metal foil is dipped into dimethylsiloxane silicone oil, and the silicone oil on the foil surface is irradiated with Xe2 excimer lamplight. Oxygen adsorbed on the sample surface is photo-excited by the irradiation to produce active oxygen. This active oxygen reacts with the silicone oil photo-excited and forms inorganic glass. With the process of the photo-oxidation, the silicone oil is vitrified, being inorganic.
Photo-oxidized Coating on the Optical Materials for High Power Laser Resistance and Waterproof
Authors: Sato Yuji , Matsunaga Eiichi , Okamoto Yoshiaki , Murahara Masataka
Published: November 2012

A photo-oxidized thin film, which transformed the organic silicone oil into inorganic glass, was coated on optical materials surface by using Xe2 excimer lamp at room temperature. This technique has enabled an optical thin coating capable of transmitting ultraviolet rays [UV] of wavelengths under 200 nm and possessing the characteristics of hardness, strain-free, resistance to high power laser, and resistance to water. UV and IR spectroscopic analysis was carried out for investigation of the oxidized silicone oil. The results revealed that the absorption peak of the CH3 group at 2900 cm-1 decreased as the irradiation time of the excimer lamp increased, and the transmittance of the light in the 172 nm wavelengths conversely became high. The UV transmittance of the silicone oil was 29.2 % before the lamp irradiation; and it improved to 90.6 % after the irradiation for 120 minutes. Moreover, in order to evaluate for resistance to laser damage [J/cm2/10 ns], the films were further irradiated with the Nd: YAG laser of ω [1.06 μm] or 2ω [0.503 μm]. The silica glass substrate had almost same laser tolerance in ω and 2ω, 112 J/cm2 and 113 J/cm2, respectively. The laser damage threshold of the photo-oxidized 100 nm thick film formed on the fused silica substrate was 72 J/cm2 in ω and 107 J/cm2 in 2ω.
Hydroxyapatite Pickering PolyHIPEs And “Thermo”HIPEs As Injectable Scaffolds For Tissue Engineering
Authors: Zhou Shengzhong , Bismarck Alexander , Steinke Joachim H.G.
Published: November 2012

Two types of porous materials derived from emulsion templates are described as potential scaffolds for tissue engineering. Novel oil-in-water particle stabilised, Pickering High Internal Phase Emulsions (HIPE) stabilised with hydroxyapatite (HAp) nanoparticles were prepared and polymerised to form stable polyHIPEs. By adding a water soluble glycidyl methacrylate (GMA) derivatised dextran as monomer to the continuous aqueous phase of the HIPEs, these Pickering-HIPEs stabilised by nontoxic biocompatible HAp nanoparticles, can be used as templates to manufacture interconnected high porosity macroporous hydrogels. A second type of emulsion templated “poly”HIPE was prepared without the need for covalent crosslinking chemistry which was replaced by a thermally-induced non-covalent scaffold forming process (thermoHIPE). These scaffolds form close to body temperature and potentially offer a new approach to the formation of injectable scaffolds for tissue engineering.
Porous scaffold made from collagen and liposomes coated with plant derived polysaccharide - in vivo study
Authors: Zarnescu Otilia , Moldovan Lucia , Trif Mihaela , Moisei Magdalena , Gaspar Alexandra , Leau Florin
Published: November 2012

The purpose of this study was to investigate the in vivo biocompatibility of a new composite made from collagen and liposomes coated with plant derived polysaccharide using a rat subcutaneous implantation model. Histological observation has shown that after five days post-implantation, granulation tissue with vascular dilatation and inflammatory cell infiltration was formed adjacent to the implanted scaffold. After two weeks post-implantation, scaffold was highly infiltrated with cells and many of multinucleated giant cells were found to be aligned along the implant/tissue interface. At four weeks the scaffold was completely infiltrated with cells and a fibrous connective capsule isolate the implanted scaffold from the surrounding tissue. The inflammatory response to the implanted scaffold was assessed by immunohistochemical staining for interleukin 1β. IL-1β was demonstrated early in the post-implantation period (five days), but after two weeks, the intensity of IL-1β staining was on the decline. In vivo studies based on histological and immunohistochemical observations showed that throughout the period of implantation, composite scaffold was well tolerated by the host animals and immune responses to the implant were moderate. The observations are consistent with the normal wound healing response to subcutaneous implantation of biomaterials. The results from the in vivo study indicate a good biocompatibility for porous scaffold made from collagen and liposomes coated with plant derived polysaccharide.
New approaches for the local prevention of osteoporotic fractures
Authors: Janvier P. , Schnitzler V. , Bouler J.-M. , Gauthier O. , Despas C. , Walcarius A. , Fayon F. , Massiot D. , Montavon G. , Mellier C. , Bujoli B.
Published: November 2012

Combining Bisphophonates (BPs) and Calcium Phosphate Cement (CPC) to form a new medical device for the local treatment of Osteoporosis is a promising challenge. Our formulation was optimized from an apatitic-type CPC and we have shown that the best solution consists in introducing the bisphosphonate (Alendronate) in the calcium deficient apatite (CDA), a solid component of the cement, through a chemical exchange reaction. The cement obtained was characterized by 31P NMR and high frequency impedance for monitoring the CPC setting. The presence of Alendronate in the cement was also demonstrated by 31P NMR which has been also used to characterize the chemical transformation of α-TCP (main component of the apatitic cement) during the setting process. BP absorption/desorption experiments have been realized on cement blocks, under continuous flow condition, to model the release profile of the Alendronate. In vivo experiments showed promising results in terms of resorbability of the Alendronate–loaded cement while promoting new bone formation. The same methodology is considered to introduce gallium, a potential inhibitor of osteoclastic resorption, in a CPC formulation. First experiments have shown that gallium can be incorporated in calcium phosphate ceramics (i.e. β-TCP) where gallium is part of the network.
Synthesis of Biodegradable Composite for Knee Cartilage Prosthesis Joint
Authors: Pérez-Reyes J.C. , Carbajal-De la Torre G. , Espinosa-Medina M. A. , Ibarra-Bracamontes L. A. , Villagómez-Galindo M. , Rubio-Rosas E.
Published: November 2012

Osteoarthritis is a very complex illness of the joints that affects cartilage and subcondral bone. At the last years, researching has been focused in the development and characterization of composite materials, evaluating their structural properties. Some o those composite materials are constituted by organic and inorganic compounds forming hybrids. These materials can improve their properties due to the interaction of reinforcement hard particles in the polymeric matrix. The interest on the composite biomaterials has been increased on the biomedical applications such as tissue regenerating based in synthetic polymers with biodegradable and biocompatible properties whose can be reinforced by calcium phosphates. In this sense, hydroxyapatite [Ca10(PO4)6(OH)2] is often used for biological implants due its mineral phase similitude with bone microstructure and tissue compatibility. Similarly, polylactic acid (PLA) is a used polymer for implant applications due physicochemical and biocompatibility properties, and short degradation time also. In order to obtain a composite that can be used as a regenerating material on the osteoarthritis problem, in this work a (90/10 wt.%) polylactic/hydroxyapatite hybrid composite was produced by chemical synthesis and characterized by X-ray diffraction, SEM, FT-IR and TGA/DSC techniques.
Fractal-based image texture analysis of trabecular bone architecture for assessment of bone health: bone aging in Mexican men
Authors: Navarrete M. , Cedillo E. , Solís L. , Villegas CH , Alvarado JA , Godínez FA
Published: November 2012

Two methods based on fractal image analysis were used to extract the architectural features of the anisotropic structure of trabecular bone from scanning electron microscope (SEM) images of sliced bone samples in order to assess the bone’s medical condition. Two methods applied were Box-Counting (BC) and Fast Fourier Transform (FFT). Tests with synthetic images of known fractal dimension aided in the interpretation of the fractal dimension (FD) profiles. Samples from L3 vertebrae were removed from Mexican male donors at the time of necropsy and evaluated using computed axial tomography (CAT) scans. Three sliced samples in normal, osteopenic and osteoporotic conditions were identified in order to compare both methods across a range of samples. The three-dimensional projection of the FD profile reflected a multifractal behavior of the trabecular architecture and clearly showed the differences in texture between the three conditions studied: normal, osteopenic and osteoporotic. In addition, the results suggest that the FFT method provides an accurate and consistent estimated for characterizing trabecular bone than the BC method.
A look into the interaction of metal oxide thin films with biological media: Albumin and Fibrinogen adsorption
Authors: Silva-Bermudez P. , Muhl S. , Rivera M. , Rodil S. E.
Published: November 2012

In the present work, the adsorption of albumin and fibrinogen on Ta, Nb, Ti and Zr oxidesthin films deposited on Si (100) wafers by magnetron sputtering was studied in order to get a better understanding of the correlation among the surface properties of these oxides and the protein adsorption phenomena on their surfaces. The surface energy, hydrophobicity, chemical composition, roughness and atomic order of the films were characterized. The films were immersedfor 45 minutes in single protein solutions; either albumin or fibrinogenand the adsorbed protein layer on the films was studied ex-situ in a dry ambient using bothX-ray photoelectron spectroscopy and atomic force microscopy.

The adsorption of albumin and fibrinogen on the films modified the surface morphology and decreased the surface roughness for all the four different metal oxides. The XPS results confirmed the presence of the protein on the surface of the films and showed that the two proteins studied were adsorbed without undergoing a major chemical decomposition. A correlation between the surface roughness,the polar component of the surface energy of the films and the atomic percentage of nitrogen on the films after protein adsorption, an indirect signal of the amount of protein adsorbed, was found for albumin and fibrinogen adsorption on Ta, Nb and Ti oxides; the largest the roughness or the polar component the largest amount of adsorbed protein.
ZETA POTENTIAL STUDY OF BARIUM HEXAGONAL FERRITES (BaFe12O19) FOR DRUG RELEASE
Authors: Torres-Cadenas S. , Escudero-García R. , Espítia-Cabrera I. , Contreras-García M.E.
Published: November 2012

Advances in nanotechnology observe new applications in many areas. Recently a great extent of research has been focused on the study of magnetic nanoparticles due to their potential application in areas such as bioscience and medicine. Magnetic nanoparticles are frequently used in biomedical and biotechnology applications since these particles associated to a given medicine are good candidates for drug release.

In this work zeta potential measurements of both hexagonal barium ferrites (magnetic nanoparticles), and an antibiotic known as tetracycline were carried out. The knowledge of the measured values establishes the possibility of bringing the two particles together in order to adsorb the tetracycline on the magnetic nanoparticles, since the surface charge play an essential role in the adsorption of the pharmaceutical drug on nanomaterials (i.e., tetracycline on barium ferrites).

Experimental results show the feasibility to adsorb tetracycline nanoparticles on barium hexaferrite solids at pH 7.0, based on the knowledge of the opposite electrical surface charge of the two solid species through the zeta potential measurement.
Synthesis and characterization of copolymeric micelles loaded with Taxol® as potential drug delivery systems for cancer treatment
Authors: Tapia L.V. , Castro J.S. , Martinez C.A. , Garcia P.E. , Rodriguez C.A. , Deymier P.A.
Published: November 2012

Taxol (Paclitaxel) is a very potent anticancer drug used in chemotherapy treatments. Due to its hydrophobic nature, toxic solubilizing agents are used to administer the drug via intravenously. However, this systemic administration is associated with toxic side effects and drug limited efficacy. An alternative to these problems are polymeric micelles. The effectiveness of this drug delivery system is related to its size, modification of pharmacokinetics, drug delivery control and toxicity reduction. In this study, micelles based on methoxy Poly(ethylene glycol)-block-Poly(ε-caprolactone) (mPEG-b-PCL) copolymer loaded with Taxol were synthesized thorough an uncommon method namely powder formulation, using tert-butanol as co-solvent, to our knowledge no reported previously for these micells. Taxol was conjugated to the hydrophobic block of mPEG-b-PCL copolymer. Characterization of this system was done by means of Fourier Transform Infrared Spectroscopy (FT-IR) and Field Emission Scanning Electron Microscopy (FESEM), observing good results as compared to previous reports.
Finite Element Stress Analysis of Cast Metal Inlays Restored Posterior Teeth
Authors: Sandu L. , Topală F. , Porojan S. , Babeş V.
Published: November 2012

Cast metal inlays have overall characteristics unavailable in any other restorative procedure, including low restoration wear, low wear of opposing teeth, lack of breakage, burnishability, malleability, and proven long term service. They replace missing teeth structures, without doing anything to reinforce the remaining structures. Stress concentrations can manifest themselves in various forms of failures. The aim of the study was to investigate the effect of preparation design on stress distribution in molars with different class II preparations and restored with cast metal inlays.

3D models of premolars and molars were created: intact teeth, unrestored teeth with class II preparations with different tapers (between 0 and 10 degree); the same teeth restored with metalic inlays. The geometries of the intact teeth were obtained by 3D scanning using a manufactured device. With Rhinoceros modeling program the preparations and the appropriately inlays were designed. These were exported in Ansys finite element analysis software for structural simulations. Stresses were registred around the occlusal contact areas. For the studied cases, the stress values were not significant influenced by the taper of the preparation. In the teeth restored with cast metal inlays, the von Mises equivalent stress values were similar to those in the intact tooth.

From biomechanical point of view, it was demonstrated that class II cast metal inlays on posterior teeth restore the original strength of the teeth. Taking into account the other characteristics of these restorations, they remain the standard of care for long-term rehabilitations. A taper between 0 and 10 degree of the preparation is not decisive for the stress values.
Aging Effects of As-deposited and Passivated Cobalt Slanted Columnar Thin Films
Authors: Schmidt Daniel , Schubert Eva , Schubert Mathias
Published: November 2012

Aging effects of as-deposited and passivated slanted columnar thin films from cobalt determined by generalized ellipsometry within the visible spectral region are reported. Slanted columnar thin films have been grown by glancing angle electron beam deposition and sub-sequently coated with Al2O3 by an atomic layer deposition process. An anisotropic Bruggeman effective medium approximation developed for highly ordered three dimensional metal nanostructures is employed to analyze spectroscopic Mueller matrix ellipsometry data. Our model approach allows for determination of biaxial optical and structural properties as well as fractions of multiple film constituents. While the optical properties of the uncoated film change over time, the alumina passivation layer prevents oxidation in air and therefore aging effects; however, it affects the intrinsic bulk-like Co optical properties.
Electron beam synthesis of 3D metal nanostructures from fluoride precursors
Authors: Ghatak Jay , Gnanavel T , Guan Wei , Möbus Günter
Published: November 2012

Various metal fluoride crystals were subjected to electron beam irradiation at 200 and 300 kV using transmission electron microscopy in order to study in-situ fabrication of 3D metal nanostructures. Lithium fluoride, cobalt fluoride and aluminum fluoride salt fragments were chemically reduced and transformed by the electron beam to the corresponding metals. Using live video recording we observe that LiF crystals decompose in a unique way different to all other metal-halides. Li diffuses rapidly out of the salt crystal and covers its surface and the surrounding C-support film to many microns distance, where at random positions nucleation, growth and annihilation of Li nanorods and some nanospheres is observable. Decomposition of CoF2 also involves non-local synthesis of Co nanoparticles, mostly facetted, however, these are stable, without annihiliation, and their positioning seems to follow some degree of self-organisation. AlF3 transforms locally to Al grains inside the irradiated area only, and grain growth occurs to sizes proportional to the beam intensity. Findings are discussed in terms of displacement energy differences between the materials.
Morphological Evolution during Growth and Erosion on Vicinal Si(100) Surfaces: From Electronic Structure Analyses to Atomistic and Coarse-Grained Modeling
Authors: Liu Da-Jiang , Ackerman David M. , Guo Xiaofang , Albao Marvin A. , Roskop Luke , Gordon Mark S. , Evans James W.
Published: November 2012

Stepped Si(100) surfaces exhibit alternating stiff SA and meandering SB steps, and thus constitute a so-called AB-vicinal surface. Both growth by Molecular Beam Epitaxy (MBE) or Chemical Vapor Deposition (CVD), and erosion by ion sputtering or chemical etching, induce step pairing, although different factors contribute. In addition, more complex pattern formation often occurs during step train motion. We synthesize recent developments in modeling of these processes ranging from ab-initio electronic structure approaches for key surface energetics, to atomistic lattice-gas modeling, to coarse-grained sharp-interface (front-tracking) and smeared-interface (phase-field) step dynamics approaches. We briefly describe development of new formalisms related to coarse-grained approaches, as well as selected results for step pairing.
Towards highly efficient solar cells based on merocyanine dyes
Authors: Steinmann Vera , Kronenberg Nils M. , Lenze Martin R. , Deppisch Manuela , Bürckstümmer Hannah , Würthner Frank , Meerholz Klaus
Published: November 2012

We present the development of highly efficient merocyanine solar cells at the example of the dye MD376. Due to their unique processing flexibility, merocyanines have been applied in solution- as well as vacuum-processed organic photovoltaics. In fully vapor-deposited MD376 single cells, efficiencies up to 5.0% were achieved while maintaining a rather simple device setup with only four organic layers. Moreover, MD376 has been successfully introduced to vacuum-processed tandem cell structures, reporting a high open-circuit voltage of 2.1 V.
Directed Assembly of Model Block Copolymer-PCBM Blend System for Photovoltaic Applications
Authors: Singh G. , Kulkarni M. M. , Smilgies D. , Sides S. , Berry B. , Raghavan D. , Bucknall D.G. , Sumpter B , Karim A.
Published: November 2012

Block copolymers are considered to be highly attractive materials with regards to future applications of nanomaterials and nanostructures owing to their self-assembling nature. Block copolymers, when supplied with sufficient energy, phase separate at the nanoscales to form periodically ordered structures in the nanometer-scale range. A diversity of architectures can be accessed via composition control of individual block components. An exciting area of application for block copolymer self assembly is organic photovoltaic devices (OPV‟s) where it is expected that the very high interfacial area of the blocks with ∼10-20 nm domain spacing would be highly advantageous for exciton diffusion and separation. For this purpose BCPs composed of amorphous (non-conjugated) polymers can also serve as a template for directed assembly of nanoparticles. Zone annealing is a well established method predominantly utilized for metallurgical and semi-conductor purification processes, where recrystallization and oriented grain growth occur on the planar front formed by the cooling-edge of the zone. We have previously applied this process to create highly ordered BCP cylinders that are parallel to the substrate with orientational control, long range order and faster ordering kinetics than conventional thermal annealing. In the present paper, we extend this idea to block copolymer - [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend system and report how the presence of PCBM nanoparticles influence the micro-phase separation behavior of cylinder forming poly(styrene-b-2-vinyl pyridine) under a dynamic thermal gradient field. A range of scattering techniques have been on the BCP:PCBM blend system, including grazing incidence small angle x-ray scattering (GISAXS) experiments to characterize in-plane and lateral ordering of BCP-PCBM blend system.
Naphthodithiophene-Diketopyrrolopyrrole Small Molecule Donors for Efficient Solution-Processed Solar Cells
Authors: Loser Stephen , Bruns Carson J. , Miyauchi Hiroyuki , Ortiz Rocío Ponce , Facchetti Antonio , Stupp Samuel I. , Marks Tobin J.
Published: November 2012

We report the synthesis, characterization, and implementation of various naphtho[2,3- b:6,7-b’]dithiophene (NDT)-based donor molecules for organic photovoltaics (OPVs) When NDT(TDPP)2 (TDPP = thiophene-capped diketopyrrolopyrrole) contains all branched 2- ethylhexyl chains and is combined with the electron acceptor PC61BM, a power conversion efficiency (PCE) of 4.06±0.6% is achieved. This respectable PCE is attributed to the broad, high oscillator strength visible absorption, the ordered molecular packing, and a high hole mobility of 0.04 cm2·V-1·s-1. We find utilizing linear C-12 side chains on either the TDPP or NDT framework dramatically increases the d-spacing, which directly correlates with inferior OPV device performance. This leads to the conclusion that the selection of an appropriate side chain plays a key role in determining OPV device performance of a small molecule donor.
Stable Colloids of Paclitaxel Nanoparticles Coated with PEGylated Polyelectrolyte Shells
Authors: Shutava Tatsiana G. , Arapov Kirill A. , Pattekari Pravin P. , Lvov Yuri M. , Levchenko Tatyana S. , Sawant Rupa R. , Torchilin Vladimir P.
Published: November 2012

A novel nanoparticulated form of the poorly water-soluble anticancer drug paclitaxel (PTX) suitable for intravenous administration has been developed using sonication-assisted layer-by-layer (LbL) assembly. The nanoparticles contain up to 70 wt.% of the drug and consist of 150-180 nm solid crystal paclitaxel cores coated with 20-30 nm thick shells of alternative layers of PEGylated poly-L-lysine and heparin. Dispersions of PTX nanoparticles are stable in different biological solvents at concentrations up to 5 mg/ml. Intravenous administration of the LbL-coated nano-crystalline PTX to mice via tail injection provided the preliminary confirmation of their safety and tolerability.
Structure and Low Concentration Self Assembly of Food Grade Bacterial Cellulose Nano-Whiskers
Authors: Khandelwal Mudrika , Windle Alan H.
Published: November 2012

Nata-de-coco (bacterial cellulose) forms nanowhiskers with a larger aspect ratio owing to higher crystalline, longer and thinner microfibrils than those formed by cellulose from other sources. Suspension of these nanowhiskers undergoes transition from isotropic to liquid crystalline phase at a very low concentration of about 0.05 wt% in water and through a broad biphasic region. Formation of nematic as well as cholesteric phase is presented in this work.
3-D Chiral Photonic Crystals Replicated from Butterfly Wing Scales
Authors: Mille Christian , Tyrode Eric C. , Corkery Robert W.
Published: November 2012

Three dimensional silica photonic crystals with the gyroid minimal surface structure have been synthesized using the butterfly Callophrys rubi as a template. The replicas are synthesized with a high degree of fidelity, which is confirmed by the spectral and morphological characterization. Further, the material is shown to be optically active.
Excitation of plasmon and guided-mode resonances in thin film silicon solar cells
Authors: Haug F.-J. , Söderström K. , Naqavi A. , Battaglia C. , Ballif C.
Published: November 2012

Thin film silicon solar cells are an attractive option for the production of sustainable energy but their low response at long wavelengths requires additional measures for absorption enhancement. The most successful concepts are based on light scattering interface textures whose understanding is greatly facilitated by considering a superposition of periodic textures that diffract the light into oblique angles, ideally beyond the critical angle of total internal reflection. Because the thickness of the active layers is on the same scale as the wavelength, interference of diffracted waves gives rise to resonance phenomena. We discuss the absorption enhancement in terms of a perturbation approach using the modal structure of a corresponding device with flat interfaces.
Microstructural Modeling of Electrical Behavior in CNT Polymer Composites
Authors: Xu S. , Rezvanian O. , Peters K. , Zikry M.A.
Published: November 2012

A three-dimensional (3D) carbon nanotube (CNT) resistor network computational model was developed to investigate the electrical conductivity, and current and thermal flow in polymer composites with randomly dispersed CNTs. A search algorithm was developed to determine conductive paths for 3D CNT arrangements and to account for electron tunneling effects. By coupling Maxwell specialized finite-element (FE) formulation with Fermi-based tunneling resistance, specialized FE techniques were then used to obtain current density evolution for different CNT/polymer dispersions and tunneling distances. These computational approaches address the limitations of percolation theories that are used to estimate electrical conductivity of CNTs. The predictions indicate that tunneling distance significantly affects 3D electrical conductivity and thermal distributions.