bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving Biomaterials from a Cellular Point of View
Authors: Varanasi Venu Gopal , Vallortigara T. , Loomer P. M. , Saiz E. , Tomsia A. P. , Marshall S. J. , Marshall G. W. 
Published: April 2011

ABSTRACTBioactive glasses (6P55) used for coating Ti/Ti-alloy were tested for their in vitro behavior in a comparative study with commercial Bioglass™ (45S5) and commercial Ti alloy (Ti6Al4V). In vitro testing included pH and dissolution rate determination in simulated body fluid (SBF) along with in vitro cyto compatibility testing. It was seen in this work that 6P55 and 45S5 had similar dissolution behavior, demonstrating t½ dependence and maximum pH of approximately 8.1 after 10 days of immersion. This pH was reduce by 0.2 0.4 pH units when the in vitro V:A ratio was increased from 1 to 3. The dissolution rate of these glasses approached 0 after additional immersion tests after 15 days and the pH stablilized at less than 7.5. Cell culture studies showed that both glasses behaved in similar fashion after 16 hours in culture. Both glasses had an increase in cell numbers of close to 200-250%, whereas Ti6Al4V had a less pronounced cell number increase (∼ 180%)
Open-architecture Neural Probes Reduce Cellular Encapsulation
Authors: Seymour John , Kipke Daryl 
Published: April 2011

ABSTRACTIntracortical microelectrodes currently have the greatest potential for achieving a functional neural prosthesis in patients with neurodegenerative diseases or spinal cord injury. Device efficacy is lacking in long-term performance as seen in both chronological histology and biopotential recording studies.Some researchers have shown that small single polymer fibers (less than 7-μm diameter) do not induce an encapsulation layer in the rat subcutis so we have extended this concept to neural probe design. In this experiment we investigated the brain-tissue response of polymer probes with 4-μm feature sizes that are capable of withstanding insertion forces when penetrating the rat neocortex. This polymer probe has both a stiff penetrating shank (70-μm by 42-μm) and fine polymer structures (4-μm by 5-μm) that extend laterally from the shank. Our testing verifies that despite a flexible substrate and small dimensions, these devices are mechanically robust and practical as neural probes. We developed a microfabrication process using SU-8 and parylene to create the relatively thick probe shank and thin lateral arms.In vivo testing was conducted on seven Sprague-Dawley rats. These parylene devices were chronically implanted in the motor cortex for 4-weeks and then imaged using fluorescence microscopy. Cellular encapsulation and neuronal loss were assessed using a Hoechst counterstain and the immunomarker NeuN (neuronal nuclei).The tissue reactivity immediately around the fine-feature structures is greatly reduced, showing mild cell encapsulation (90±68% increase) relative to the probe shank (460±320% increase). Neuronal loss was only (21±25%) out to 25-μm relative to significant loss around the probe shank (47±19%). Additionally, laminin+, fibronectin+, and Ox42+ tissue often showed greater intensity and thickness at the shank, indicating that the dense scar formation typical of cortical implants was mitigated around the fine lateral structure.These results suggest that using MEMS-based microfabrication to create sub-cellular structures will significantly reduce encapsulation, which should extend the longevity of neural probes. We also believe this concept could be beneficial to any implantable sensor capable of scaled geometries.
Effects Of Laser Parameters On The Mechanical Response Of Laser Irradiated Micro-Joints
Authors: Mian Ahsan , Mahmood Tonfiz , Auner Greg , Witte Reiner , Herfurth Hans , Newaz Golam 
Published: April 2011

ABSTRACTThis paper is devoted to the laser irradiated joints between glass and polyimide. To facilitate bonding between them, a thin titanium film with a thickness of approximately 0.2 μm was deposited on glass wafers using the physical vapor deposition (PVD) process. Two sets of samples were fabricated where the bonds were created using diode and fiber lasers. The samples were subjected to tension using a microtester for bond strength measurements. The failure strengths of the bonds generated using fiber laser are quite consistent, while a wide variation of failure strengths are observed for the bonds generated with diode laser. Few untested samples were sectioned and the microstructures near the bond areas were studied using an optical microscope. The images revealed the presence of a sharp crack in the glass substrate near the bond generated with the diode laser. However, no such crack was observed in the samples made using fiber laser. To investigate further the reasons behind such discrepancy in bond quality, three-dimensional uncoupled finite element analysis (FEA) was conducted for both types of samples. The transient heat diffusion-based FEA model utilizes the laser power intensity distribution as a time dependent heat source to calculate the temperature distribution within the substrates as a function of time.
Solid State NMR Studies of the Aluminum Hydride Phases
Authors: Hwang Son-Jong , Bowman Robert C. , Graetz Jason , Reilly J. J. 
Published: April 2011

ABSTRACTSeveral solid state NMR techniques including magic-angle-spinning (MAS) and multiple-quantum (MQ) MAS experiments have been used to characterize various AlH3 samples. MAS-NMR spectra for the 1H and 27Al nuclei have been obtained on a variety of AlH3 samples that include the β- and γ- phases as well as the most stable α-phase. While the dominant components in these NMR spectra correspond to the aluminum hydride phases, other species were found that include Al metal, molecular hydrogen (H2), as well as peaks that can be assigned to Al-O species in different configurations. The occurrence and concentration of these extraneous components are dependent upon the initial AlH3 phase composition and preparation procedures. Both the β-AlH3 and γ-AlH3 phases were found to generate substantial amounts of Al metal when the materials were stored at room temperature while the α-phase materials do not exhibit these changes.
The Capacity Enhancement of Room Temperature Hydrogen Storage in HiPco SWNT by Electrochemical deposition of Palladium Nanoparticles
Authors: Lee Yong-Won , Bhowmick Ranadeep , Clemens Bruce M. 
Published: April 2011

ABSTRACTA Sieverts apparatus for small quantity samples has been implemented by employing a very small volume pressure reservoir and a sample chamber of less than 1 ml. The hydrogen storage capacity of a commercially available, HiPco (high pressure CO conversion) single-wall carbon nanotube (SWNT) was measured over a hydrogen pressure range of 0-35 Bar at room temperature. The sample contained approximately 5 wt% of residual Fe catalyst, and showed 0.17 wt% of hydrogen uptake capacity at 30 Bar of hydrogen pressure. Palladium nanoparticles were deposited on the SWNT via electrochemical method (EC) from H2PdCl4 solution. The storage capacity of the SWNT with EC-doped Pd was increased to 0.52 wt% at 30 Bar, which corresponds to the capacity enhancement by a factor between 2.8 and 3.1.
Novel Approach for Fabrication of Single-Crystalline Insulator/Si/Insulator Nanostructures
Authors: Fissel Andreas , Kuehne Dirk , Bugiel Eberhard , Osten H. Joerg 
Published: April 2011

ABSTRACTDouble-barrier insulator/Si/insulator nanostructures on Si(111) were prepared using molecular beam epitaxy. Ultrathin single-crystalline Si buried in a single-crystalline insulator matrix with sharp interfaces was obtained by a novel approach based on an epitaxial encapsulated solid-phase epitaxy. As an example, we demonstrate the growth of Si buried in Gd2O3 and the incorporation of epitaxial Si islands into single-crystalline Gd2O3. The I-V characteristic of the obtained nanostructures exhibited negative differential resistance at low temperatures, however, with a strong memory effect.
Development of CMR Manganite Sensors for Energy Measurement of the Linear Coherent Light Source Free Electron Laser Xray Pulses
Authors: Yong Grace J. , Kolagani Rajeswari M. , Cox David E. , Mundle Rajeh , Davidson Anthony L. , Friedrich Stephan , Ali Zaheer A. , Drury Owen B. , Li Lisa G. , Ott Linda L. , Liang Yong 
Published: April 2011

ABSTRACTWe are developing Colossal Magnetoresistive (CMR) manganite thin film bolometric sensors to be employed as total energy detectors for beam diagnostics of the Linear Coherent Light Source (LCLS) Free Electron Laser (FEL) (at the Stanford Linear Accelerator). LCLS is an ultra bright, ultra short coherent x-ray source whose peak brightness will exceed that of third generation x-ray sources by about ten orders of magnitude and average brightness by three orders of magnitudes. It is expected to produce 1012 x-rays per 200 fs pulse with a repeat frequency of 120 Hz through self-amplified stimulated emission. In characterizing the beam, it will be necessary to measure the total energy of the FEL pulse. The Advanced Detector Group at Lawrence Livermore Laboratory has developed a scheme for FEL total energy measurements based on bolometric detection and are collaborating with Towson University to implement such a detector using CMR manganite thin films. Here we discuss the basic scheme, results of simulations of the thermal response and the materials development efforts towards fabricating the thin film detectors.
Characteristics of Lateral Capacitor Based on High-K Materials
Authors: Kalkur Thottam , Azadpour Mark 
Published: April 2011

AbstractIn order to take advantage of continued interconnect scaling dimensions in very large scale integrated circuit technology, lateral capacitors with BST dielectric have been proposed. The lateral capacitors have been implemented by platinum/titanium metallization patterned by standard photolithographic techniques and ion-milling. The high-K dielectric BST has been deposited by spin-on MOD and radio frequency magnetron sputtering. The capacitance of lateral capacitor was found to increase with increase in thickness of BST and annealing temperature. The negative temperature dependence capacitance above room temperature shows that BST is in para-electric phase.
Ohmic Contact Behavior of Pt/Ni/Au to p-ZnO
Authors: Lee Ji-Myon , Kim Kyoung-Kook , Tampo Hitoshi , Yamada Akimasa , Niki Shigeru 
Published: April 2011

ABSTRACTThe electrical properties of single Pt (30 nm) and Pt (30 nm)/Ni (30nm)/Au(50nm) multilayer contacts on moderately doped p-ZnO (Na = 5.0 × 1017 /−3) were investigated. Although linear current-voltage characteristics were observed for all samples, a sample that was annealed for 1 min at a temperature above 500 °C resulted in an ohmic contact with good characteristics. The best ohmic contact to p-type ZnO was obtained using a Pt/Ni/Au multilayer contact that was annealed at 600 °C for 1 min under a N2 ambient, showing a specific contact resistance Rc of 1.97 × 10−5 Ω cm2. The fundamental mechanisms for the lower contact resistivity of Pt/Ni/Au contacts are discussed based on glancing angle x-ray diffraction results and Auger depth profile analysis of the multilayer alloying process. Furthermore, we fabricated a ZnO p-n homojunction using Pt/Ni/Au and Ti/Au as the p-type and n-type ohmic contact metal, respectively. The threshold voltage was determined to be about 3.7 V, comparable to the bandgap energy of ZnO.
Combinatorial Study on In-Ga-Zn-O Semiconductor Films as Active-channel Layers for Thin-film Transistor
Authors: Iwasaki Tatsuya , Itagaki Naho , Den Tohru , Kumomi Hideya , Nomura Kenji , Kamiya Toshio , Hosono Hideo 
Published: April 2011

ABSTRACTThe device characteristics of thin-film transistors (TFTs) having amorphous In-Ga-Zn-O channel layers with various chemical compositions were studied by using combinatorial synthesis techniques. The In-Ga-Zn-O films were prepared by a radio-frequency magnetron sputtering method at room temperature in mixed-gas atmosphere of argon and oxygen. The TFT libraries enabled us to systematically survey the device characteristics of the TFTs in a wide compositional range of channel materials. It is found that the TFT characteristics are very sensitive to the chemical composition ratio of In:Ga:Zn and depend also on the oxygen partial pressure during deposition. Some devices exhibited good performance of the field-effect mobility of ∼10 cm2V−1sec−1 and on-to-off current ratio of ∼108.
Computational Investigation Into the Adsorption of Pollutants Onto Mineral Surfaces: Arsenate and Dolomite
Authors: Austen Kat F. , Wright Kate , Slater Ben , Gale Julian D. 
Published: April 2011

ABSTRACTComputational modeling techniques have been used to investigate the interaction of arsenate with the dolomite (211) surface. The suitability of a variety of techniques has been assessed in the context of their applicability to the problem, in order to determine the least computationally expensive method of modeling the mineral-solution interface. To this end, various methods of solvating arsenate have been investigated, and a reliable solvation energy has been determined for the molecule. The adsorption geometry of the primary arsenate ion at the dolomite surface has been determined under vacuum conditions. Additionally, solvation of the dolomite surface has studied using molecular dynamics, and results show that there is some layering 2Å above the surface, and that dissociation of the water molecules occurs in this layer.
Nanochemistry: The Development and Implementation of a New Graduate Elective at the Middle Eastern Technical University in Turkey
Authors: Pitcher Michael 
Published: April 2011

ABSTRACTIt seems that a day cannot pass without reading a headline in the popular press or scientific magazines extolling the potential of nanotechnology and nanoscience. The excitement is justifiable and the new generation of researchers and workers in this discipline will need a whole new range of skills and vocabulary to understand and progress this exciting field and for it to reach its full potential. In higher education and research establishments around the world most nanoscience or nanotechnology courses and textbooks, that have been developed, have been done so by engineering or physics departments and approach the subject from that perspective. The interdisciplinary nature of nanoscience, however, also includes chemists, which until recently have had to rely on these courses and books to gain an insight into this rapidly developing field. This has changed in the last year, or so, with exciting new books being published by chemists and aimed at chemistry students of all levels, In addition, chemistry departments around the world, are beginning to develop nanochemistry classes, particularly at the graduate level. Presented here is the structure and content of a new graduate elective that has been offered at the Middle Eastern Technical University (METU) in Ankara, Turkey. This course was offered for the first time in spring 2006 and is designed primarily to introduce and equip chemistry graduate students with some of the skills and tools needed to contribute to the growing nano related research interests that are burgeoning on campus, in the country and in the world. The design of the course, the textbook used, comments from the students, etc are discussed.
Approach To An Interdisciplinary Bionanotechnology Education Program: International Network Perspective
Authors: Vaseashta Ashok , Irudayaraj J. , Vaseashta S. , Stamatin I. , Erdem A. 
Published: April 2011

ABSTRACTMaterials in reduced dimensions demonstrate size dependence and may exhibit properties different from the bulk. Nanomaterials are a fundamentally and entirely new class of materials with remarkable electrical, optical, and mechanical properties, thus offering unique applications. With a 9.7% increase in FY 2004-05 investments and an expected worldwide labor force shortage, education and training has become a key component of the National Nanotechnology Initiative (NNI). The slow response by the academic community to develop nanotechnology curriculum is evidenced by the small number of Universities offering fundamental undergraduate level courses in nanoscience and nanotechnology. There is a strong need to develop coercive undergraduate curriculum to equip the future engineers, scientists, and researchers charged with commercializing nanotechnology applications. We are in the process of developing and implementing some core courses and laboratory modules, which can easily adapt to either a major or minor in nanotechnology, nano-biotechnology, or nanoscience programs. The course modules are being developed by a multi-disciplinary team consisting of faculty in Physics, Agricultural and Biological Engineering, Materials Engineering, and Molecular Biology at Universities in the US, Europe, and the Consortium of South East European Network on Nanoscience and Technology (COSENT). The joint effort specifically addresses a sector of nanobiotechnology emphasizing applications in agricultural and biological systems through hands-on modules and experimental kits. Selected course and laboratory modules are being developed to be affordable, flexible, accessible, and appealing to a diverse student population from across basics sciences, life sciences, agriculture, and engineering departments. Internet ready, multimedia intensive curriculum and assessment modules will include self-directed individualized learning modules as well as team-based components capitalizing on collaborative learning to address complex problems and tasks. The capital cost and site sensitivity of much of the equipment used within nanoscience courses often limits its distribution to large research centers, despite the need for it in many disperse educational programs. The creation of this seamless integration will promote and encourage an international exchange of students and ideas within interdisciplinary research. We will present our unique approach to delivery of education and training at all levels employing converging technologies to an international audience and receive feedback to enhance the effectiveness of the program to better educate the task force of tomorrow.
An Undergraduate Nanotechnology Course for Classes of Multi-discipline students in Taiwan
Authors: Chen Chu Shiang , Lin Song Shiang 
Published: April 2011

ABSTRACTWe reported on our experiences with teaching several semesters of undergraduate nanotechnology courses at both the National Tsing Hua University (NTHU) and National Dong Hwa University (NDHU) in Taiwan. Students who were enrolled in our classes at NTHU represented many different disciplines, but mainly in the physical sciences, engineering and life sciences. In contrast, students who were enrolled in our classes at NDHU dominated in the social sciences and arts. There were some interesting differences in addition to the similarities in their attitude toward the nanotechnology. Since this course is aimed at introducing the nanotechnology to students trained in different disciplines, we emphasized the fundamentals, current status, potential applications, and possible consequences of nanotechnology. This course also explored the close ties between nano-science and engineering (NS/E) and our daily life. Furthermore, this course elaborated on the interrelationships of NS/E with other subjects, particularly the biomimetics, smart systems, and biotechnology.
Training Young Minds for Nanoscience and Technology: Issues and Challenges
Authors: Chattopadhyay Kamanio 
Published: April 2011

ABSTRACTThis article explores issues and challenges in the field of education in nanoscience and technology with special emphasis with respect to India, where an expanding programme of research in nano science and technology is in place. The article does not concentrate on actual curricula that are needed in nano science and technology education course. Rather it focuses on the desirability of nanoscience and technology education at different levels of education and future prospect of students venturing into this within the economic and cultural milieu of India. We argue that care is needed in developing the education programme in India. However, the risk is worth taking as the education on nanoscience and technology can bridge the man power gap not only in this area of technology but also related technologies of hardware and micro electronics for which the country is a promising destination at global level. This will also unlock the demographical advantage that India will enjoy in the next five decades.
Core-shell Ge Nanoparticles on Oxide Surfaces for Enhanced Interface Stability
Authors: Stanley Scott K. , Ekerdt John G. 
Published: April 2011

ABSTRACTGermanium nanoparticles are grown on HfO2 substrates by hot-wire chemical vapor deposition (HWCVD). The oxidation and thermal stability of these unmodified Ge nanoparticles are determined with X-ray photoelectron spectroscopy (XPS). Core-shell nanoparticles were then prepared by growing the Ge cores with HWCVD and selectively growing Si or C shell layers on the Ge cores by conventional CVD. The formation of core-shell nanoparticles was monitored with XPS and low energy ion scattering. Large differences are observed in the thermal stability and oxide formation for unmodified Ge and the different core-shell nanoparticles.
Ultrafast Photoconductivity in Organic Semiconductors
Authors: Ostroverkhova Oksana , Cooke David G. , Hegmann Frank A. , Anthony John E. , Podzorov Vitaly , Gershenson Michael E. , Jurchescu Oana D. , Palstra Thomas T.M. 
Published: April 2011

ABSTRACTWe present comprehensive study of ultrafast charge carrier dynamics in a variety of organic molecular crystals. In all samples, we observed sub-picosecond charge photogeneration and band-like transport, characterized by (i) an increase in charge carrier mobility as the temperature decreases in a wide temperature range of at least 20 K – 300 K and (ii) mobility anisotropy in the a-b plane of the crystals. The temperature dependence of the decay dynamics of the transient photoconductivity reveals the presence of shallow trapping sites in herring-bone-type-structured crystals (such as pentacene (Pc), tetracene (Tc), and rubrene (Rub)), while such traps are apparently absent in “brick-wall”-type crystals (such as functionalized pentacene (FPc)). We also report on the measurements of the charge carrier mobility anisotropy in the a-b plane of two types of FPc single crystals. Anisotropies of approximately 3.5 and 11.6 were obtained in the crystals characterized by crystal structures favoring two-dimensional and one-dimensional charge transport, respectively, consistent with the degree of π-overlap along different directions in the crystals.
Time-Integrated Photoluminescence Studies of In0.3Ga0.7As/GaAs Quantum Dot Molecules
Authors: Kerr William , Stoleru Valeria Gabriela , Pancholi Anup 
Published: April 2011

ABSTRACTWe investigate experimentally and theoretically optical and electronic properties of In0.3Ga0.7As/GaAs quantum dot molecules (QDMs) formed by two layers of self-assembled, vertically stacked quantum dots (QDs). Structures with In0.3Ga0.7As/GaAs QD layers separated by a thin GaAs barrier were grown by solid source molecular beam epitaxy, and were characterized by time-integrated photoluminescence (PL). For the temperature-dependent PL measurements a He-flow optical cryostat was used to control the temperature between 4 and 300 K. The experimentally observed behavior is in good agreement with that expected from our eight-band k·p calculations. Optical and electronic properties of these QDMs are further compared with those of dots grown under conditions that did not promote vertical organization.