bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Approach to Creation of Biomimetic Scaffolds for Tissue Engineering
Authors: Belenkaya Bronislava , Shepelev Aleksey , Sakharova Valentina 
Published: June 2019

ABSTRACTIn tissue engineering, a successful tissue scaffold is not simply a 3D-micro/nanofibered, highly porous environment that mimics a native extra cellular matrix (ECM). To maintain an ideal medium for cells to grow and proliferate, the biodegradable scaffold should be generally hydrophilic and should serve as a reservoir of cell nutrients, growth factors and other components present in the blood flow. Synthetic biodegradable polymers have found wide applications in micro/nanofibered scaffolding materials because of their proven biocompatibility, availability of established processing techniques, good mechanical properties and controlled, regulated biodegradation time. But, high hydrophobicity of these polymers does not allow to realize a moist environment in the scaffold typical for native ECM and favorable for the cells.We have recently found that electrospun polymeric blends of polyvinylpyrrolidone (PVP) and poly-d,l-lactide (PDLL) provide mechanically strong micro/nanofibered materials of high hydrophilicity. These materials have a regulated absorption ability of blood or other biological liquids of up to ~8-10 g/g without swelling or changing the shape of the fibers. As demonstrated by spectroscopy and differential scanning calorimetry, strong polymer chains assembly of PDLL-PVP occurs when the corresponding blends are processed into micro/nanofibers by electrospinning or casted into films. The polymer chain assembly is not affected by absorbed liquids. The matrices preserve their liquid absorption ability after drying. Preliminary testing of matrices in humans demonstrated a high efficacy of the scaffolds for wound healing acceleration.
Silica Coated Multifunctional Plasmonic Nanoparticles for Theranostics
Authors: Sotiriou G.A. , Pratsinis S.E. 
Published: June 2019

ABSTRACTHybrid magnetic/plasmonic nanoparticles possess properties originating from each individual material. Such properties are beneficial for biological applications including bio-imaging, targeted drug delivery, in vivo diagnosis and therapy. Limitations regarding their stability and toxicity, however, challenge their safe use. Here, the one-step flame synthesis of composite SiO2-coated Ag/Fe2O3 nanoparticles is demonstrated. The hermetic SiO2 coating does not influence the morphology, the superparamagnetic properties of the iron oxide particles and the plasmonic optical properties of the silver particles. Therefore, the hybrid SiO2-coated Ag/Fe2O3 nanoparticles exhibit desired properties for their employment in bio-applications.
Elemental Analysis and Current-Voltage Characteristics of LiZnP and LiZnAs Samples for Solid-State Neutron Detectors
Authors: Montag Benjamin W. , Reichenberger Michael A. , Arpin Kevin R. , Nelson Kyle A. , Ugorowski Philip B. , McGregor Douglas S. 
Published: June 2019

ABSTRACTResearch for a reliable solid-form semiconductor neutron detector continues because such a device would have greater efficiency, in a compact form, than present day gas-filled 3He and 10BF3 detectors. The 6Li(n,t)4He reaction yields a total Q value of 4.78 MeV, larger than 10B, and easily identified above background radiations. Hence, devices composed of either natural Li (nominally 7.5% 6Li) or enriched 6Li (usually 95% 6Li) may provide a semiconductor material for compact high efficiency neutron detectors. A sub-branch of the III-V semiconductors, the filled tetrahedral compounds, AIBIICV, known as Nowotny-Juza compounds, are known for their desirable cubic crystal structure, and were originally studied for photonic applications. Equimolar portions of Li, Zn, and P or As were sealed under vacuum (10-6 Torr) in quartz ampoules with a graphite lining, loaded into a compounding furnace, and heated to 560 °C to form the ternary compound, LiZnP or LiZnAs, and further annealed to promote crystallization. The chemical composition of the synthesized starting material was confirmed at Galbraith Laboratories, Inc. by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), which showed the compounds were reacted in equal ratios, 1-1-1, to form ternary compounds. Bulk single crystal samples were grown by a high temperature technique described elsewhere. Samples were cut, polished, and prepared for electrical characterization by depositing a Ti/Au contact onto one side of the one of the samples and using silver epoxy to form the other contact. Current-voltage curves were collected for a sample with silver epoxy for both anode and cathode contact, and for a sample with a Ti-Au anode contact and silver epoxy cathode contact. A much higher resistivity was calculated, 6.6 x 1010 Ω·cm, for the sample with a Ti-Au contact compared the high conductivity seen with the sample using silver epoxy contacts.
The Initial Phase of Photoelectrochemical Anodization of Si in Alkaline Media Investigated by Synchrotron Radiation Photoelectron Spectroscopy (SRPES) and Scanning Probe Microscopy (SPM)
Authors: Letilly M. , Skorupska K. , Aggour M. , Kanis M. , Lewerenz H.-J. 
Published: June 2019

ABSTRACTAnodic oxide formation and chemical and electrochemical etching of n-Si(111) have been investigated in alkaline media. Due to the complexity of the processes, the investigation has been restricted to the initial phase where a transitory anodic photocurrent peak is observed slightly positive from the open circuit potential (ocp). In-system photoelectron spectroscopy, performed at the U 49/2 beamline at Bessy, shows sub-monolayer silicon surface oxidation and remnant H-termination, indicating island-type oxide formation. Scanning probe microscopy shows the formation of macropores with 300-500 nm diameter and an average depth of 5-8 nm. The discussion comprises chemical and electrochemical dissolution mechanisms and routes to development of nanoemitter fuel generating devices.
Supramolecular Self-assembly of Chlorins in an Aerosolized Droplet to Synthesize Biomimetic Antennas
Authors: Shah Vivek B. , Biswas Pratim 
Published: June 2019

ABSTRACTNatural light harvesting organisms have evolved to harvest sunlight efficiently. Green sulfur bacteria, which contain chlorosomes, can survive in extremely low light conditions mainly because of efficient light absorption and transfer of energy, facilitated by the assembled dye molecules. Due to these reasons, chlorosomes have been used in dye sensitized solar cells to improve the light absorption and performance. The chlorosome absorption spectrum is fixed and their size is dependent on the organism. Various solution-based techniques have been developed for synthesizing mimics by supramolecular self-assembly. However, controlling the size of agglomerates and their subsequent deposition on surfaces to fabricate a device is difficult. In this work, a one-step aerosol-based self-assembly technique has been developed for the first time, to assemble and deposit chlorin (Bacteria chlorophyll mimics) agglomerates. A shift in absorption spectra of 79 nm which is comparable to the natural system was obtained. The analysis shows that kinetics of nucleation play an important role in assembly.
Surface Modification to a-SiC Photocathode Using Ruthenium Nanoparticles
Authors: Zhu Feng , Matulionis Ilvydas , Gaillard Nicolas , Chang Yuancheng , Hu Jian , Gallon Josh , Madan Arun 
Published: June 2019

AbstractIn this paper we described using ruthenium (Ru) nanoparticles for surface modification on our hybrid PV/a-SiC photocathode for hydrogen production by water splitting under sunlight. Ru nanoparticles with size less than 5nm in diameter made the photocathode showed promising results: in an aqueous electrolyte an anodic shift of photocurrent onset potential around 450 mV and an increase in the photocurrent density up to 1.8mA/cm2 from a negligible value. Initial discussion the influence of Ru nanoparticles is presented.
Simulation of a single dopant nanowire transistor
Authors: Asenov Asen , Georgiev Vihar 
Published: June 2019

ABSTRACTNowadays the silicon technology is capable of delivering sub-10 nm devices where ‘every atom counts’. Manipulation of atoms with high precision on such a scale, in principle, can lead to technological innovations, such as transistors with extremely short gate length, quantum computing components and optoelectronic devices. One possible strategy to create this next generation of devices is to precisely place individual discrete dopants (such as phosphorous atoms) in a nanoscale transistor.In this paper, we report a systematic study of quantum transport simulation of an impact that precisely positioned dopants have on the performance of ultimately scaled gate-all-around silicon nanowire transistors (SNWT) designed for digital circuit applications. Due to strong inhomogeneity of self-consistent electrostatic potential, a full 3-D real-space Non Equilibrium Green’s Function (NEGF) formalism is used. The simulations are carried out for an n-channel NWT with a 2.2 x 2.2 nm2 cross-section and a 6 nm channel length, where locations of precisely arranged dopants in the source drain extensions and in the channel region have been varied. The individual dopants act as localized scatters and, hence, impact of electron transport is directly correlated to the position of the single dopants. As a result, a large variation in the ON-current and modest variation of the subthreshold slope are observed in the ID-VG characteristics when comparing devices with microscopically different discrete dopant configuration. Introducing of channel surface roughness in the Ch Sym 1 wire induces a threshold voltage shift and ON-current variation in the device due to scattering. The variations of the current-voltage characteristics are analyzed with reference to the behaviour of the transmission coefficients. Our calculations provide guidance for a future development of the next generation components with sub-10 nm dimensions for the semiconductor industry.
Conductivity measurement of individual SnS nanoparticles by Peak Force AFM
Authors: Prastani C. , Vetushka A. , Hývl M. , Fejfar A. , Nanu M. , Nanu D. , Schropp R. E. I. , Rath J. K. 
Published: June 2019

ABSTRACTPeak Force Atomic Force Microscope is a new technique to characterize fragile materials such as nanoparticles with high accuracy with only one measurement. Unlike the tapping mode AFM, Peak Force AFM operates at a frequency below the resonant frequency of the cantilever. This allows for a direct control of the forces and avoids lateral forces that may damage the sample as in contact mode AFM. Furthermore, the performance characteristics of Peak Force AFM are suitable to work also in Tunneling AFM (TUNA) mode, enabling the study of the electrical properties of materials.In this work SnS nanoparticles capped with tri-n-octylphosphine oxide (TOPO) have been characterized. By means of Peak Force AFM it is possible to measure simultaneously topography and current maps of nanoparticles, yielding information about the shape, size and the conductivity of even a single nanoparticle. The topography map clearly showed single nanoparticles with a size less than 5 nm and spherical shape. In the conductivity map it is possible to discern the same nanoparticles, the correlation with the topography map is evident. This confirms the conduction (though not calibrated) of SnS nanoparticles. This type of measurements has been repeated many times in order to check the reproducibility of this technique. Moreover, the same nanoparticles have been measured also by Torsional Resonant TUNA AFM in order to compare it with Peak Force AFM. By means of TR-TUNA it was possible to measure the topography of SnS nanoparticles capped with TOPO but not the current. Besides, the resolution of the topography map acquired by TR-TUNA AFM is inferior to Peak Force AFM. From this comparison it has been found that the conductivity of nanoparticles, even if they are capped with TOPO, can be measured by Peak Force AFM, a result that thus far has been difficult to achieve by other types of AFM.
Effects of Operating Conditions on Bimodal Atomic Force Microscopy
Authors: Chakraborty Ishita , Yablon Dalia G. 
Published: June 2019

ABSTRACTBimodal Atomic Force Microscopy (AFM) is a recently developed dynamic AFM technique. Recent work [1] has shown the existence of different regimes of operation in Bimodal AFM depending on the operating conditions. The current work focuses on the effects of different operating parameters while imaging an impact copolymer blend of polypropylene (PP) and ethylene-propylene (E-P) rubber. The higher mode amplitude and phase contrasts reverse at different points between the PP and rubber regions as the free amplitude of the higher eigenmode is increased. The observed contrast reversal suggests that the cantilever kinetic energy and its free air drive input energy play a role in determining the regimes of operation. Understanding the role of cantilever dynamics in determining these operation regimes will help guide a more rational operation of Bimodal AFM.
Synthesis of Iron-containing Nanomaterials by “Greener” Methods and Their Use for Disinfection of Water
Authors: Kharisov Boris I. , Pérez Betsabee Olvera , de Casas Ortiz Edgar G. , Kharissova Oxana V. , Corona María del Rayo Camacho , Jiménez Pérez Victor M. , Dias Rasika 
Published: June 2019

ABSTRACTMethods of “green” synthesis of nanoparticles of elemental iron (zero-valent iron, NZVI), its oxides and hydroxides using natural products are reviewed. In particular, the use of biological agents such as extracts of various plants, tea, soya, table sugar and glucose, as reductants and as capping agents is shown. The techniques involved are simple, environmentally friendly and generally one-pot processes. Water disinfection using iron nanomaterials against viruses and bacteria is also examined.
Advances in sustainable fluorine-free CSD YBa2Cu3O7 thin films
Authors: Vermeir Pieter , Feys Jonas , Pollefeyt Glenn , Verslyppe Bram , De Brabandere Asha , Verbeken Kim , Bäcker Michael , Lommens Petra , Schaubroeck Joseph , De Buysser Klaartje , Van Driessche Isabel 
Published: June 2019

ABSTRACTChemical solution deposition techniques are a very competitive low cost method to achieve coated conductors. Recently, fluorine-free CSD methods have made a great progress for the preparation of YBCO thin films and became a sustainable alternative for the well-known trifluoroacetate CSD approach. By elucidating the reaction mechanism behind this new approach, finally giving an answer to the question why it is possible to fabricate YBCO films without TFA, different processing routes were discovered giving rise to high superconducting YBCO films (>1MA.cm-2). Each route has it's own benefits. One specific route offers the opportunity to tune the crystallographic orientation. By changing one process parameter, a shift from complete c-axis to complete a-axis orientation is observed. This can be very useful for e.g. Josephson Junctions.We particularly investigated the fundamental reaction mechanism of each reaction route, with the focus on the corresponding barium compound. Although good superconducting properties are obtained, still one major drawback limits industrial implementation: thickness. It is observed that a critical thickness of ∼500 nm eliminates the superconducting properties. Therefore, this paper gives a summary of all progress made regarding to fluorine-free water-based CSD YBCO thin films with emphasis on the possibility to control the crystallization rate.
Silicon Carbide Radiation Detectors: Progress, Limitations and Future Directions
Authors: Ruddy Frank H. 
Published: June 2019

ABSTRACTSilicon carbide has long been a promising material for semiconductor applications in high-temperature environments. Although silicon carbide radiation detectors were demonstrated more than a half century ago, the unavailability of high-quality materials and device manufacturing techniques hindered further development until about twenty years ago. In the late twentieth century, the development of advanced SiC crystal growth and epitaxial chemical vapor deposition methods spurred rapid development of silicon carbide charged particle, X-ray and neutron detectors. The history and status of silicon carbide radiation detectors as well as the influence of materials and device packaging limitations on future detector development will be discussed. Specific silicon carbide materials development needs will be identified.
High Resolution X-Ray Imaging with Thin SrI2-Scintillator Screens
Authors: Alaribe Leonard , Fauler Alex , Cecilia Angelica , Santos Rolo Tomy Dos , Fiederle Michael , Burger Arnold 
Published: June 2019

ABSTRACTMuch has been reported on the excellent performance of the Eu2+ activated SrI2-scintillator in spectroscopic applications, like the high light yield (97 660 ph/MeV) and good energy resolution (2.7% FWHM at 662 keV). The exploitation of these properties for other application fields is limited by the hygroscopic nature of the SrI2. Single crystal scintillating screens exhibit high spatial resolution, this combined with the high density, high effective atomic number, and the high light yield of the SrI2 could be used for high resolution X-ray imaging.Some of the questions we tried to answer in this work are the following: owing to the excellent performance of the SrI2-scintillator in spectroscopic applications, how would it perform in X-ray imaging applications. X-ray images are described based on their (spatial) resolution and contrast, how would they look like when recorded using the SrI2-scintillator detector.First a packaging technique was developed that protected the hygroscopic screens during the measurements. Our results show a high resolution of the images obtained with thin SrI2-scintillator screens both in 2D radiography and 3D tomography measurements. With these results, we think that the SrI2-scinitillator is not only a candidate for spectroscopic applications, but also for high resolution X-ray imaging purposes.
Linear Polarization Rotation Study of the Microwave-Induced Magnetoresistance Oscillations in the GaAs/AlGaAs System
Authors: Ramanayaka A. N. , Ye Tianyu , Liu H-C. , Mani R. G. , Wegscheider W. 
Published: June 2019

ABSTRACTMicrowave-induced zero-resistance states appear when the associated B-1-periodic magnetoresistance oscillations grow in amplitude and become comparable to the dark resistance of the two-dimensional electron system (2DES). Existing theories have made differing predictions regarding the influence of the microwave polarization in this phenomenon. We have investigated the effect of rotating, in-situ, the polarization of linearly polarized microwaves relative to long-axis of Hall bars. The results indicate that the amplitude of the magnetoresistance oscillations is remarkably responsive to the relative orientation between the linearly polarized microwave electric field and the current-axis in the specimen. At low microwave power, P, experiments indicate a strong sinusoidal variation in the diagonal resistance Rxx vs. θ at the oscillatory extrema of the microwave-induced magnetoresistance oscillations. Interestingly, the phase shift θ0 for maximal oscillatory Rxx response under photoexcitation is a strong function of the magnetic field, the extremum in question, and the magnetic field orientation.
Exciton Gas versus Electron Hole Liquid in the Double Quantum Wells
Authors: Babichenko Vladimir S. , Polishchuk Ilya Ya. 
Published: June 2019

ABSTRACTThe many-body correlation effects in the spatially separated electron and hole layers in the coupled quantum wells (CQW) are investigated. A special case of the many-component electron-hole system is considered, ν>>1 being the number of the components. Keeping the main diagrams in the parameter 1/ν allows us to justify the selection of the RPA diagrams. The ground state of the system is found to be the electron-hole liquid with the energy smaller than the dense exciton gas phase. The possible connection is discussed between the results obtained and the experiments in which the inhomogeneous state in the CQW is found.
Emission and X ray diffraction in AlGaAs/ InGaAs Quantum wells with embedded InAs Quantum dots
Authors: Tamayo R. Cisneros , Moreno I.J. Gerrero , Hernandez A. Vivas , Espinola J.L. Casas , Shcherbyna L. 
Published: June 2019

ABSTRACTThe photoluminescence (PL), its temperature dependence and X-ray diffraction (XRD) have been studied in MBE grown GaAs/AlGaAs/InGaAs/AlGaAs /GaAs quantum wells (QWs) with InAs quantum dots embedded in the center of InGaAs layer in the freshly prepared states and after the thermal treatments during 2 hours at 640 or 710 °C. The structures contained two buffer (Al0.3Ga0.7As/In0.15Ga0.85As) and two capping (In0.15Ga0.85As / Al0.3Ga0.7As) layers. The temperature dependences of PL peak positions have been analyzed in the temperature range 10-500K with the aim to investigate the QD composition and its variation at thermal annealing. The experimental parameters of the temperature variation of PL peak position in the InAs QDs have been compared with the known one for the bulk InAs crystals and the QD composition variation due to Ga/Al/In inter diffusion at thermal treatments has been detected. XRD have been studied with the aim to estimate the capping/buffer layer compositions in the different QW layers in freshly prepared state and after the thermal annealing. The obtained emission and XRD data and their dependences on the thermal treatment have been analyzed and discussed.
EPR and emission study of silicon suboxide nanopillars
Authors: Bratus’ V. , Indutnyi I. , Shepeliavyi P. , Torchynska T. 
Published: June 2019

ABSTRACTThe results of correlated electron paramagnetic resonance (EPR) and photoluminescence (PL) study of obliquely deposited porous SiOxfilms after step-by-step 15 min annealing within 105 min in vacuum at 950°C are presented. The low intensity symmetrical and featureless EPR line with a g-value g=2.0044 and a linewidth of 0.77 mT has been detected in as-sputtered films and attributed to dangling bonds (DB) of silicon atoms in amorphous SiOxdomains withx=0.8. Successive annealing results in decreasing this line and the appearance of an intense EPR line with g=2.0025, linewidth of 0.11 mT and a hyperfine doublet with 1.6 mT splitting. According to the parameters this spectrum has been attributed to theEXcenter, a hole delocalized over four non-bridging oxygen atoms grouped around a Si vacancy in SiO2. The impact of chemical treatment before annealing and duration of anneals on the defect system, and a correlation of the PL intensity with decreasing of theDBEPR signal are discussed.
New Paramagnetic Center and High Conductivity in a-Si1-xRux:H Thin Films
Authors: He Jian , Li Wei , Xu Rui , Guo An-ran , Wang Yin , Jiang Ya-dong 
Published: June 2019

ABSTRACTIn this work, the metallic element Ru is introduced into a-Si:H. The structural and electrical properties of the films doped with Ru have been investigated. Raman spectra reveal that the addition of Ru disarranges further the intrinsically disordered amorphous network and generates more coordinated defects. Meanwhile, a new paramagnetic signal, associated with the holes localized in valence band tail, has been observed. Moreover, the conductivity increases by about nine orders of magnitude with the increase of doping concentration, and the temperature coefficient of resistance (TCR) results show that this material may have a potential application in the infrared detectors.