bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Functionalization of Water-etched Si(100)
Authors: Say Carmen , Queeney Kate T.
Published: February 2010

Etching of hydrogen-terminated Si(100) in deoxygenated water produces surfaces with a regular nanoscale topography. Surface infrared spectroscopy provides detailed information about this topography via interrogation of the silicon hydride species that populate this highly ordered surface. Here we investigate the feasibility of using siloxane chemistry to functionalize this surface while preserving the initial topography. The critical step in silanization to form high-quality organic layers is oxidative cleaning of the surface. By re-etching oxidized surfaces in hydrofluoric acid, we can repopulate surface hydride species and examine any apparent changes in topography that resulted from the oxidation step. We compare three different oxidation protocols and find that an SC-2 clean results in the least perturbation of the original topography. Preliminary results using both dynamic contact angle and atomic force microscopy suggest that the SC-2 oxidized surface can be functionalized with alkylsilane reagents to create a functionalized surface with regular, nanoscale topography, with all surface processing carried out under ambient conditions at or near room temperature.
Dislocation Arrays in Sapphire using Femtosecond Laser Irradiation
Authors: Moon Chiwon , Kanehira Shingo , Miura Kiyotaka , Tochigi Eita , Shibata Naoya , Ikuhara Yuichi , Hirao Kazuyuki
Published: February 2010

We investigated the formation mechanism and thermal behaviors of defects which were induced at a microscopic area inside (1120) sapphire. We used a femtosecond laser having a pulse width, wavelength, and repetition rate of 238 fs, 780 nm, and 1 kHz, respectively. Cracks were formed at the focal point along the {1102} and the {1100} planes by laser irradiation. The preferential crack formation on these planes was attributed to the different surface fracture energy between the crystallographic planes of sapphire. The cracks transformed into the array of discrete pores by the subsequent heat treatment above 1300 °C, which was due to the diffusive crack healing process. In addition, dislocations were also introduced at the interface between closed cracks.
Nanoporous Ni and Ni-Cu Fabricated by Dealloying
Authors: Hakamada Masataka , Chino Yasumasa , Mabuchi Mamoru
Published: February 2010

Metallic nanoporous architecture can be spontaneously attained by dealloying of a binary alloy. The nanoporous architecture can be often fabricated in noble metals such as Au and Pt. In this study, nanoporous Ni, Ni-Cu are fabricated by dealloying rolled Ni-Mn and Cu-Ni-Mn alloys, respectively. Unlike conventional Raney nickel composed of brittle Ni-Al or Cu-Al intermetallic compounds, the initial alloys had good workability probably because of their fcc crystal structures. After the electrolysis of the alloys in (NH4)2SO4 aqueous solution, nanoporous architectures of Ni and Ni-Cu with pore and ligament sizes of 10–20 nm were confirmed by scanning electron microscopy and transmission electron microscopy. X-ray diffraction analyses suggested that Ni and Cu atoms form a homogeneous solid solution in the Ni-Cu nanoporous architecture. The ligament sizes of nanoporous Ni and Ni-Cu were smaller than that of nanoporous Cu, reflecting the difference between diffusivities of Ni and Cu at solid/electrolyte interface. Ni can reduce the pore and ligament sizes of resulting nanoporous architecture when added to initial Cu-Mn alloys.
Nanoimprinted Glass Substrates for Nanoscale Growth Control of Transparent Conducting Oxide Films
Authors: Sugimoto Yuki , Akita Yasuyuki , Nakasone Yuta , Mita Masahiro , Oi Hideo , Yoshimoto Mamoru
Published: February 2010

The crystal growth of indium tin oxide (ITO) thin films on nanoimprinted glass substrates was examined by applying pulsed laser deposition. The nanoimprinted glass was fabricated by thermal nanoimprint using a nanostriped NiO thin film mold. The nanopatterned glass had a straight nanowire array with intervals of about 180 nm, and wire height of about 30 nm. The surface morphology of the ITO thin film grown on the nanoimprinted glass accurately reflected the morphology of the glass surface nanopattern. The ITO thin film on the imprinted glass exhibited preferentially (111)-oriented polycrystalline growth, and had 35% lower resistivity in the direction perpendicular to the nanowire array than that of the film grown on the nonpatterned commercial glass.
Electron Magnetic Resonance Studies on Nanowire and Nanoparticle Arrays
Authors: Amponsah Osei K , Rakhimov Rakhim R. , Barnakov Yuri A. , Lukaszew Rosa A , Owrutsky Jeffrey C , Pomfret Michael B , Noginova Natalia
Published: February 2010

Arrays of magnetic nanowires and well-oriented chains of superparamagnetic nanoparticles were fabricated using polymer and alumina membrane templates. The systems were characterized by SQUID and studied by electron magnetic resonance methods. Comparative analysis of the obtained results for different geometries and sizes of the magnetic inclusions is presented.
Interactions Between Carbon Nanotubes and Liquid Crystals in Binary Nematic Electro-Optic Cells
Authors: Georgiev Georgi Yordanov , Gombos Erin A , McIntyre Michael B , Mattera Michael F , Gati Peter A. , Cabrera Yaniel , Cebe Peggy
Published: February 2010

We studied the effects of multiwalled carbon nanotubes (MWCNTs) on the Freedericksz transition of a liquid crystal (LC) and calibrated the altitudinal angle of CNTs as a function of the electric field. In addition, we directed the azimuthal angle which gave us complete control of the 3D orientation of the CNTs. We constructed anti-parallel electro-optic cells using a nanocomposite at a concentration of 0.01% CNTs with 4-Cyano-4'-pentylbiphenyl (5CB) liquid crystal. This low concentration was necessary to achieve maximum transmission of electromagnetic radiation through the cell and to minimize the Van der Waals attraction between the CNTs responsible for their aggregation. We chose two dimensional microscopic transmission ellipsometry (2D-MTE) to measure the phaseshift of the polarized electromagnetic radiation through the cell and to derive from it the altitudinal angle of the CNTs. Our results show that in the presence of CNTs the Freedericksz transition occurs at 55% of the transitional electric field as compared to the control electro-optic cell without CNTs. The width of the Freedericksz transition narrows by a similar factor. The switching time of the cell decreased in the presence CNTs by 18.5%.
Fabrication of Ga-templates Using a Focused Ion Beam
Authors: Wang Hao , Hartman Greg C. , Williams Joshua , Gray Jennifer L.
Published: February 2010

There are many factors that have the potential to limit significant advances in device technology. These include the ability to arrange materials at shrinking dimensions and the ability to successfully integrate new materials with better properties or new functionalities. To overcome these limitations, the development of advanced processing methods that can organize various combinations of materials at nano-scale dimensions with the necessary quality and reliability is required. We have explored using a gallium focused ion beam (FIB) as a method of integrating highly mismatched materials with silicon by creating template patterns directly on Si with nanoscale resolution. These templates are potentially useful as a means of locally controlling topography at nanoscale dimensions or as a means of locally implanting Ga at specific surface sites. We have annealed these templates in vacuum to study the effects of ion dosage on local Ga concentration and topography. We have also investigated the feasibility of creating Ga nanodots using this method that could eventually be converted to GaN through a nitridation process. Atomic force microscopy and electron microscopy characterization of the resulting structures are shown for a variety of patterning and processing conditions.
Formation of ordered arrays of gold particles on silicon and silicon-dioxide by nanoindentation patterning
Authors: Ruffell Simon , Venkatachalam Dinesh Kumar , Shalav Avi , Elliman Robert G.
Published: February 2010

Ordered arrays of gold particles have been fabricated on gold-coated Si(100) surfaces by pre-patterning the surface with a nanoindenter. During thermal annealing the Au is observed to accumulate within the residual indents. Once nucleated, the Au particles grow at the expense of smaller surface particles via an Ostwald-ripening process. The size of the Au particles is controlled by the initial thickness of the deposited Au layer, the size of the indentation (which is controlled with a high degree of precision), and the annealing conditions. Particles of ˜200 nm dimensions are formed in indents of ˜1 μm dimensions whilst nanoparticles of ˜20 nm are observed in the smallest indents made (˜50 nm). We have also demonstrated patterning of Au by indentation of a Au layer sandwiched between two SiO2 films deposited on Si by plasma-enhanced chemical vapour deposition. Here, cracking of the SiO2 layer occurs allowing Au to diffuse to the surface at the indented locations during post-indentation annealing.
A Concurrent Multiscale Method for Coupling Atomistic and Continuum Models at Finite Temperatures
Authors: Picu Catalin , Mathew Nithin
Published: February 2010

A concurrent multi-scale modeling method for finite temperature simulation of solids is introduced. The objective is to represent far from equilibrium phenomena using an atomistic model and near equilibrium phenomena using a continuum model, the domain being partitioned in discrete and continuum regions, respectively. An interface sub-domain is defined between the two regions to provide proper coupling between the discrete and continuum models. While in the discrete region the thermal and mechanical processes are intrinsically coupled, in the continuum region they are treated separately. The interface region partitions the energy transferred from the discrete to the continuum into mechanical and thermal components by splitting the phonon spectrum into “low” and “high” frequency ranges. This is achieved by using the generalized Langevin equation as the equation of motion for atoms in the interface region. The threshold frequency is selected such to minimize energy transfer between the mechanical and thermal components. Mechanical coupling is performed by requiring the continuum degrees of freedom (nodes) to follow the averaged motion of the atoms. Thermal coupling is ensured by imposing a flux input to the atomistic region and using a temperature boundary condition for continuum. This makes possible a thermodynamically consistent, bi-directional coupling of the two models.
Designing Glasses with Tunable Structure and Properties by Computer Simulation
Authors: Huang Liping , Yuan Fenglin , Zhao Qing
Published: February 2010

A normal solid becomes stiffer when squeezed and softer when heated. In contrast, silica glass behaves the opposite way: its elastic moduli decrease upon compression and increase upon heating. Silica glass is also known to densify under compression and radiations. These have been long-standing mysteries in materials science. Using molecular dynamics simulation, we uncovered the structural origins of the anomalous thermo-mechanical behaviors and mechanisms of permanent densification in silica glass. Accordingly, these anomalies can be attributed to localized structural transitions, analogous to those that occur in the crystalline counterparts. The irreversible densification in silica glass is achieved through structural transition involving bond breaking and re-formation under a combination of high pressure and temperature. We further revealed that the anomalous thermo-mechanical behaviors are inherently connected to the ability of the glass to undergo permanent densification. Our computer simulations demonstrate that by processing in ways that gradually eliminates anomalous thermo-mechanical behaviors, degree of the glass to undergo densification can be eventually eradicated. This provides the conceptual foundation for the bottom-up design of new glasses with tunable structure and properties.
Discovery Learning Tools in Materials Science: Concept Visualization with Dynamic and Interactive Spreadsheets
Authors: Sinex Scott A. , Halpern Joshua B.
Published: February 2010

Many materials science concepts can be developed into animated, interactive spreadsheets to create engaging discovery learning tools. These Excel spreadsheets do not require programming expertise. Learning how to create and use these didactically useful spreadsheets is simple and new examples can be quickly created by teachers.
Building a Low Cost, Hands-on Learning Curriculum on Glass Science and Engineering using Candy Glass
Authors: Heffner William R. , Jain Himanshu
Published: February 2010

We have developed a program to connect students, as well as the general public, with glass science in the modern world through a series of hands-on activities and learning experiences using sucrose based glass (a.k.a. hard candy). The scientific content of these experiments progresses systematically, providing an environment to develop an understanding of glassy materials within a framework of “active prolonged engagement” with the material. Most of the experiments can be assembled in a high school lab, or even in a home setting with minimal cost, and yet are appropriate for inclusion in an undergraduate materials lab. The cost is minimized by utilizing common, everyday materials and devices. Some of the activities included in our experiments include: synthesis, density, refractive index determination, glass transition, crystallization, kinetics of devitrification, thermal properties, etc. Temperature measurement, temperature control, and even automated data collection are part of the experience, providing an open path for the students to continue their own interesting and creative ideas.
Authentic Science Research and the Utilization of Nanoscience in the Non-Traditional Classroom Setting
Authors: Day Deborah A. , Yu Zizi , Wang Zelun , Dalecki Jennifer , Jadbabaie Arian , Feng Emily Z. , Mattessich Thomas J. , Caragianis-Broadbridge Christine , Reed Mark A. , Munden Ryan
Published: February 2010

Applications of nanoscience in the non-traditional classroom have successfully exposed students to various methods of research with applications to micro- and nano-electronics. Activities obtained from the NanoSense website associated with current global energy and water concerns are solid examples. In this regard, all 36 students in the 2008-2009 Science Research Program (SRP) prepared and delivered individual and group lesson plans in addition to their authentic, year-long research projects. Two out of 36 students selected nanoscience based projects in preparation for science fair competition in 2009. Additionally, preliminary research was conducted while participating in the Center for Research on Interface Structures and Phenomena (CRISP) Research Experience for Teachers (RET) Program in summer 2008 which supported the idea of developing a photolithography kit. This kit is intended to introduce high school students to the fundamentals of photolithography. In this paper, the design, implementation and feasibility of this kit in the high school classroom is described as well as details involving individual and group nanoscience based projects. Supporting educational models include self-regulated learning (SRL) concepts; situated cognition; social constructivism; Renzulli's (1977) enrichment triad and Types I – III inquiry enrichment activities.
Materials Science as a High School Capstone Course for the Physics First Curriculum
Authors: Unterman Nathan A.
Published: February 2010

By changing the high school science curriculum from Freshman Science, Biology, Chemistry, and Physics (BCP); to Physics, Chemistry, and Biology (PCB), we have an opportunity to create a new Senior level science elective. The entire high school science core curriculum has been reviewed and parts rewritten to create a coherent, integrated program based on common themes such as energy, particulate nature of matter, and forces. Nanoconcepts including size and scale and surface area to volume ratio are integrated where appropriate. In our school, we began PCB during the 2008-2009 academic year. In anticipation of these students becoming upperclassmen, a capstone elective course of Materials Science has been developed based on scientific models and literacies shaped in the PCB course sequence. Deployment of this new model centered course is set for the 2010-2011 school year.
Design and Implementation of Professional Development Seminars in Coordination with Research Experience for Teachers (RET) and Focused on Professional Practices of Scientists and Engineers
Authors: Simmons Chelsey , Storm Kaye , Lichtenstein Gary , Pruitt Beth
Published: February 2010

Many programs promote professional development for teachers in laboratory settings. In fact, some research has shown these experiences can improve student achievement. However, it is unclear what aspect of the laboratory experience helps bring about this effect. In order to ensure all teachers participating in Stanford's Research Experiences for Teachers program received maximum benefit from the laboratory experience, supplementary seminars were delivered that emphasized a variety of skills and tasks required of career scientists and engineers. Teacher feedback indicates that participants found these seminars valuable and that they would prefer additional time for peer interaction and curriculum development.
Implementation of a Curriculum Leading to a Baccalaureate Degree in Nanoscale Science
Authors: Matyi Richard , Geer Robert E.
Published: February 2010

The College of Nanoscale Science and Engineering (CNSE) at the University at Albany has developed an academic curriculum leading to the degree of Bachelor of Science in Nanoscale Science. This curriculum represents a 132-credit program designed for completion in eight academic semesters and is consistent with the SUNY General Education Program requirements as implemented at the University at Albany. This curriculum comprises a cutting-edge, inherently interdisciplinary, academic program centered on scholarly excellence, educational quality, and technical and pedagogical innovation. The blueprint for this curriculum is comprised of four basic components: a “Foundational Principles”’ component, a “Core Competency” component, a “Concentration” component and a “Capstone Research/Design” component. The first two components are designed to integrate the dissemination of fundamental, cross-disciplinary, nanoscale science and engineering principles with the cultivation of the critical skill set necessary for advanced undergraduate coursework and interdisciplinary research. The remaining two components expand on these foundational skills to develop the topical expertise, technical depth, and independent research abilities that are essential to a well-rounded undergraduate educational experience. The combination of these instructional tools ensures a customizable and coherent undergraduate degree program that trains the student's intellect how to explore, discover, and innovate, while ensuring its proficiency in a specific nanoscale discipline. The outcome is a unique undergraduate experience that taps into CNSE's global academic leadership in nanoscale science and engineering to attract and educate a diverse and talented pool of qualified scientists and engineers at the baccalaureate level.
Development and Delivery of an Online Graduate Certificate in Materials Characterization for Working Professionals
Authors: Dickrell Pamela L. , Dempere Luisa A.
Published: February 2010

Within materials science and engineering industries there exists a need for continual professional development and lifelong learning. University materials science and engineering departments and materials related centers have highly qualified instructional faculty, and course management infrastructure that can be utilized to deliver needed continuing education to working professionals via distance learning. This work examines the development and first year delivery results of an online graduate certificate in modern materials characterization techniques for working scientists and engineers.
Biocompatible Phosphorus-based Monomers for Radical Polymerization
Authors: Dworak Claudia , Heller Christian , Varga Franz , Liska Robert
Published: February 2010

Novel biocompatible and biodegradable monomers based on phosphorus-containing vinyl esters and vinyl carbamates for radical photopolymerization were prepared. By photo-Differential Scanning Calorimetry (photo-DSC) the reactivity of the mono-, di- and trifunctional monomers was investigated. Furthermore, their cytotoxicity, mechanical properties and hydrolytic degradation behavior were evaluated, aiming at a future application of our compounds in the biomedical area.
Zr(IV)-immobilized Affinity Beads Prepared by Surface Template Polymerization for Capturing Phosphorylated Proteins
Authors: Uezu Kazuya , Mizuki Hidenobu , Ito Yudai , Harada Hisashi , Oshiumi Haruka
Published: February 2010

A novel immobilized metal affinity chromatography (IMAC) bead, Zr(IV)-immobilized resin, was prepared by surface template polymerization to enrich phosphorylated proteins and peptides from complex peptides mixtures. In order to enhance both the kinetics and the efficiency, large pathways for the proteins and peptides in the resin were formed, and the Zr(IV)-phosphate complexes were immobilized on the polymer surface. The morphology of the Zr(IV)-immobilized resin was evaluated the by measuring the specific surface area, pore volume, and pore distribution. The resin possessed large amount of the large-macro pores around 300 nm. The separation performance of β-casein from bovine serum albumin (BSA) solution was evaluated by phosphopeptide enrichment and MALDI-TOF MS analysis. The Zr(IV)-immobilized resin showed the high selectivity of the phosphopeptide.
Cell-Based Detection Using Electric Cell-Impedance Sensing
Authors: Mohanraj Bhavana , Schiele Nathan , Hynes Anne , Yan Zijie , Corr David T. , Dinu Cerasela Z , Chrisey Douglas B
Published: February 2010

Electric Cell-Impedance Sensing (ECIS) is a real-time transduction system that can be used to detect the presence of foreign particles or pathogens by measuring the changes in impedance or resistance of a cell monolayer grown on an electrode. Herein, we present the use of ECIS for the detection of the toxicity of silver nanoparticles on Madine Derby Canine Kidney (MDCK) epithelial cells as a function of changes in the cell confluence and barrier function of the cell monolayer. The barrier function is a measure of the number of tight junctions formed between confluent cells in a monolayer; tighter confluence leads to an increase in a barrier function and thus in the measured resistance. We were able to detect exposures as low as 1 μg of 20 nm silver nanoparticles per 105 cells within 2 hours; those exposures were quantified as a significant drop in impedance and a gradual decrease in the barrier function as compared to the controls. Future work would include the detection of protein toxins using impedance sensing as well as further analysis of the barrier function using fluorescent staining.
Bioinspired Inorganic/polymer Thin Films
Authors: Hirata Gustavo A. , Diaz Sandra Payan , Chen Po-Yu , Meyers Marc A. , McKittrick Joanna
Published: February 2010

Studies of hard biological materials such as marine shells, animal teeth, horns and bones have produced fascinating ideas for mimicking their micro/nanostructure in the lab. The nacre in the abalone shell has a well-defined organic/inorganic structure that has a fracture resistance that is much higher than the individual constituents. By using biocompatible materials we have fabricated zirconium nitride/ polymethylmethacrylate alternating layers that are based on the structure of nacre. A combination of DC-magnetron sputtering and pulsed laser deposition on (100) silicon substrates was used to fabricate multilayers in a single chamber without breaking the vacuum. The ZrN films showed nanocrystalline columnar growth on the silicon substrates or on the PMMA nanolayer. High resolution SEM analysis at the inorganic/organic interface revealed well formed, uniform thickness inorganic films which are separated by the polymeric layer (30-90 nm). The ratio of the ceramic/polymer is the same as in nacre. Nanoindentation hardness values of ˜ 20GPa were measured on both the ZrN single film, similar to published values, and the ZrN/PMMA composite layers and the elastic modulus remained constant, independent of the number of layers.
Bio-electrosprays and Aerodynamically Assisted Bio-jets, Flow Cytometry Concepts for Interrogating Living Cells and Whole Organisms
Authors: Jayasinghe Suwan N.
Published: February 2010

Bio-electrospraying and aerodynamically assisted bio-jetting are rapidly evolving approaches for directly handling living cells and organisms. In this article we demonstrate how these technologies now elucidated as being safe for handling living cells and organisms can be explored not only for tissue engineering and regenerative medicine but also in biology for single cell and organism diagnostics.
Unique Microstructure and Mechanical Properties from Melt Processing Poly(Lactide-co-Glycolide)/Poly(Trimethylene Carbonate)
Authors: Zhang Jianbin , Luo Lian , Lyu Suping , Pudil Bryant , Schley Jim , Benz Mike , Buckalew Adam , Chaffin Kim , Hobot Chris , Sparer Randy
Published: February 2010

Poly(lactide) (PLA) and its copolymers degrade through hydrolysis into non-toxic and water soluble metabolic products in vivo. They are ideal materials for resorbable biomedical applications such as drug delivery and tissue engineering. However, these polymers are brittle and often need to be toughened. One of the most effective toughening methods is reactive blending, in which additives are dispersed into polymer matrices as small particles with strong bonding between the two materials. In this paper, we studied toughening poly(lactide-co-glycolide) (PLGA) through reactive blending with poly(trimethylene carbonate) (PTMC). We observed warm-like micelle or swollen warm-like micelle structures created during the reactive blending process with a twin screw extruder at high temperature. The micelle structures were orientated along the extrusion direction with their length ranging from 50 to 1000 nm and diameters about 50 nm. This structure could be produced only with a twin screw extruder. When a batch mixer was used, the PTMC additive (10 to 30 wt%) formed spheres with diameters on the order of 100-500 nm. The PLGA/PTMC copolymers formed in situ were responsible to this microstructure. The mechanical properties of this blend were significantly improved over the pure PLGA.
Rapid Prototyping of Biomimetic Structures: Fabrication of Mosquito-like Microneedles by Two-Photon Polymerization
Authors: Gittard Shaun D. , Narayan Roger J , Ovsianikov Aleksandr , Chichkov Boris N.
Published: February 2010

Over the past twenty years, the use of rapid prototyping techniques for processing of medical devices has seen rapid growth. A number of rapid prototyping techniques currently exist for producing a broad range of medical devices using metals, ceramics, polymers, and composite materials. One promising rapid prototyping technology for creating medical devices with small scale features is two photon polymerization; this scalable photopolymerization technique enables processing of photosensitive materials such as organically-modified ceramic materials. In this study, two photon polymerization was used to produce microneedles that mimic the anatomy of the mosquito fascicle. The labrum of the mosquito was replicated in the mosquito-like microneedle. On the other hand, the maxillae of the mosquito were not replicated in the mosquito-like microneedle; the absence of these features was attributed to inadequate mechanical support of the maxillae. This study suggests that two photon polymerization and other rapid prototyping technologies may be used to produce biomimetic drug delivery devices that imitate the intricate structures found in nature.
Poly(1,3-Butylene Fumerate) and Poly(1,3-Butylene Fumerate)-co-(1,3-Butylene Maleate) as Electrospun Scaffold Materials
Authors: Cicotte Kirsten Nicole , Dirk Shawn M. , Hedberg-Dirk Elizabeth
Published: February 2010

Poly(butylene fumerate) (PBF) and poly(butylene fumerate)-co-(butylene maleate) (PBFcBM) have been synthesized from the ring opening and condensation reactions of maleic anhydride (MA) and 1,3-butanediol (BD). PBFcBM synthesized in this way contains greater than 85% maleate groups. Both PBF and PBFcBM have a glass transition temperature (Tg) below room temperature and therefore cannot be electrospun using the conventional electrospinning process as a non-porous film results. To facilitate production of nonwoven micro- and nano-fiber mats, a UV-source (λ=356 nm) was used in combination with a photoinitator loaded polymer solution to initiate the crosslinking reaction of the fumerate and maleate functional groups as the fibers were produced. The resulting non-woven fiber mats are potentially suitable scaffolds for tissue engineering and drug delivery application.
Development of Boron Cage Compound Nanocomposite Elastomers
Authors: Eastwood Eric Allen , Bowen Daniel Edward , Lee Mark W.
Published: February 2010

A wide variety of nanofillers of varying compositions have been used to create polymer nanocomposites, including tubes, wires, fibers, sheets, and particles. A new class of compounds has been identified for use as nanofillers, boron cage compounds. Boron cage compounds are discrete, icosahedral closed cage molecules of high boron content and examples include carboranes and dodecaborate salts. Several chemically modified boron cage compounds have been incorporated into polyolefin elastomers, such as poly(ethylene-co-vinyl acetate), poly(ethylene-co-vinyl acetate-co-vinyl alcohol), poly(ethylene-co-ethyl acrylate), and poly(ethylene-co-octene), among others. The resulting thermal and thermomechanical properties were evaluated in order to determine when plasticization and reinforcement occur to better understand the chemical structure/physical property relationships. Materials with a wide range of properties were produced, however under certain conditions, advanced materials were created with high boron contents, improved thermal stability, mechanical strength, and significant reinforcement.
Localizing GABA Receptors and Glutamate Transporters Using Conjugated Quantum Dots in Rat Cerebellum Slices
Authors: El Abed Abdel Illah , Baudot Anne , Chat Mireille , Ben Khalifa Sanaa , Louis Gérard
Published: February 2010

GABA and glutamate are known as the principal inhibitory and excitatory neurotransmitters in the vertebrate central nervous system, respectively. However, recent electro-physiological and immunogold data reported by Stell et al. [1] indicate that GABA may undergo also an excitatory action on presynaptic varicosities of parallel fibers (PFs) in the molecular layer of the rat cerebellum. PFs are axonal extensions, with a cross section of about 0.1 m, of the glutamatergic granule cells. Such an unexpected excitatory action of GABA indicates clearly the presence of GABA receptors in the PFs of granule cells. We show in this study that quantum dots may be used specifically and efficiently to label two endogenous synaptic proteins, namely R-GABAA-1 receptors (GABAA Rs) and glutamate transporters (VGLUT1) in order to target their localization in very small structures such as the presynaptic varicosities of the PFs, in agreement with the results recently reported by Stell et al..
A model for coupled electro-hydro-mechanical processes in fine grained soils accounting for gas generation and transport
Authors: Tamagnini Claudio , Jommi Cristina , Cattaneo Fabio
Published: March 2010

A theoretical and numerical model is developed for the quantitative analysis of coupled processes taking place in active waste containment systems, such as electrokinetic barriers or fences, in which alow intensity DC current is circulated across the clay barrier to move polar and non-polar contaminants. A novel feature of the proposed approach is the allowance for the presence of air in the pore space. Under unsaturated conditions, all transport coefficients involved in the electrokinetic process are strongly dependent on the degree of saturation of pore liquid. In order to assess the predictive capability of the proposed theory and to appreciate the impact of gas production at the electrodes, a series of numerical simulations of simple onedimensional electrokinetic tests have been performed. The results of the simulations compare reasonably well with data obtained from laboratory experiments performed on an illitic clayey silt. The numerical results indicate that the impact of gas production at the electrodes can be significant, even in low-intensity and short-duration treatments.
Sistema radicular do fórmio, sisal e bambu imperial
Authors: Medina Júlio César , Inforzato Romeu , Pettinelli Armando , Pinto Luiz Carlos de Toledo
Published: March 2010

Os autores apresentam e discutem os resultados de estudos preliminares sôbre o sistema radicular do fórmio (Phormium tenax Forster), sisal (Agave sisalana Perrine) e bambu .imperial (Bambusa vulgaris Schrad. var. vittata A. ,& C, Riv.). Concluem, que o sistema radicular do fórmio é relativamente raso, o do sisal bastante superficial é o do bambu imperial se limitada às primeiras carnadas do solo.
Influência da adubação com torta de café na germinação do algodoeiro
Authors: Ferraz C. A. Menezes , Fuzatto Mílton Geraldo , Gridi-Papp Imre L.
Published: March 2010

São apresentados os resultados de três ensaios com a finalidade de estudar o efeito da adubação com torta de café, na germinação do algodoeiro. Oa ensaios foram instalados em estufa, em 1961, utilizando-se a torta de café isoladamente e em combinação com fosforita de Olinda ou cloreto de potássio. Num dos ensaios foi testada uma mistura que continha 75%, em pêso, de torta de café e 25% de cloreto de potássio, em comparação com cloreto de potássio isoladamente. De modo geral, houve efeito prejudicial na aplicação da mistura de torta e cloreto de potássio, salvo no caso em que foi aplicada ao lado e abaixo do nível das sementes. O cloreto de potássio, isoladamente, não prejudicou a germinação. Num segundo ensaio foi estudada a mistura tendo 50% de torta de café e 50% de fosforita de Olinda. O efeito prejudicial foi menor que no ensaio anterior a presente mistura causou maiores prejuízos à germinação quando em contacto com as sementes; o mesmo não ocorreu quando aplicada ao lado do sulco de semeação. No terceiro ensaio foram testadas diversas épocas de aplicação, com as duas misturas acima citadas e torta de café. Notou-se uma tendência de melhoria na germinação quando os adubos foram aplicados com antecedência à semeação do algodoeiro.
Absorção de nutrientes pela batatinha
Authors: Gargantini H. , Blanco H. Garcia , Gallo J. Romano , Nóbrega Sylvio de A.
Published: March 2010

A marcha da absorção dos elementos nutritivos essenciais pela batatinha (Solanum tuberosum L.) foi estudada em plantas cultivadas em vasos de barro, interna, mente vidrados, e com capacidade para 10 quilos de terra. Em cada 10 dias, durante todo o ciclo vegetativo, eram colhidas plantas e analisados os teores de N, P, K, Ca, Mg e S. Tôdas as plantas receberam os mesmos cuidados em tratos culturais, fitossanitários e água. Propiciaram-se, ainda, iguais condições de fertilidade, dando-se a todos os vasos adubação completa, inclusive com os micronutrientes necessários ao bom desenvolvimento e produção da batata. Os resultados obtidos mostram que a batata absorve em grande quantidade o nitrogênio e o potássio, sendo o último em maior proporção. Dos outros elementos estudados, o fósforo, o cálcio, o magnésio e enxôfre, são absorvidos em pequenas quantidades, não ultrapassando nenhum dêles 16 kg/ha. Os dados mostram ainda que as quantidades totais necessárias de nitrogênio, potássio, magnésio e enxôfre são absorvidas pela cultura, até completar 50 dias após a germinação, enquanto o fósforo e o cálcio são requeridos desde o inicio até o final do ciclo vegetativo da planta.
Poliploidia artificial em seringueira (Hevea Brasiliensis Muell.-Arg.)
Authors: Mendes Luiz O. T. , Mendes A. J. Teixeira
Published: March 2010

Tendo em vista verificar se, com a duplicação do número de cromossômios, obter-se-iam seringueiras com vasos laticíferos de maior diâmetro que o observado em plantas normais e, conseqüentemente, de maior produção de látex, os autores, por meio de soluções de colchicina, trataram plantas recém-germinadas, assim obtendo poliplóides artificiais. No decurso dos trabalhos foi desenvolvida uma técnica especial, pela qual, de uma mesma semente de seringueira, eram obtidas duas plantas, uma normal e outra com o número duplo de cromossômios; dessa maneira, a planta normal se constitui em perfeita testemunha da planta poliplóide, podendo-se, assim, atribuir à poliploidia tôda e qualquer alteração que se venha a verificar na planta com o número duplo de cromossômios. Acreditam os autores que êsse mesmo processo poderá ser utilizado com êxito em outras plantas dicotiledôneas. Os resultados mostram que, nas plantas poliplóides, os estornas são maiores e em menor número, por unidade de superfície foliar, que nas plantas normais; observam-se também diferenças morfológicas nessas plantas, que se desenvolvem satisfatòriamente. Ainda não foram feitos estudos para a determinação do diâmetro dos vasos laticíferos. O material foi multiplicado por enxertia e está sendo incluído em experimentos a cargo da Seção de Plantas Tropicais.
Um rápido teste de campo para exocorte
Authors: Moreira S.
Published: March 2010

Procurando encontrar um teste de campo rápido e prático para identificar a presença do virus da exocorte em plantas cítricas, foram feitas sôbre-enxertias no viveiro e no pomar em plantas portadoras do virus, usando borbulhas de limoeiro cravo e de trifoliata. Em cinco meses apareceram os sintomas da exocorte nos ramos de limoeiro cravo e em 6-7 meses nos de trifoliata. Inoculando pés francos de limoeiro cravo, no viveiro, com borbulhas portadoras do virus e provocando a formação de ramos novos e vigorosos nessas plantas, os sintomas da exocorte apareceram nesses ramos quatro meses depois da inoculação. Êste último parece ser o melhor e mais rápido teste de campo para a exocorte, até agora descoberto.
Nova técnica para a contagem de cromossomos em amendoim (Arachis Hypogaea L.)
Authors: Medina Dixier M. , Conagin Cândida Helena T. M.
Published: March 2010

Dificuldades constantemente encontradas na determinação do número de cromossomos em Arachis trouxeram a necessidade de pesquisar novos métodos. Uma técnica eficiente foi então desenvolvida no laboratório de Citologia do Instituto Agronômico de Campinas e que consta do seguinte: a) pré-tratamento das raízes com solução saturada de paradiclorobenzeno à temperatura de 16 a 20°C durame 4-8 horas ou por uma solução 0,002 mo/1 de oxiquinoleína a 16°C durante 6 a 7 horas; b) hidrólise em orcenína acética (2% de orceína em ácido acético a 70%) e ácido clorídrico na proporção de 9:1; c) coloração e esmagamento em orceína acética a 1% em ácido acético a 45%. Tanto o paradiclorobenzeno como a oxiquinoleína produzem o eteito c-mitótico sôbre os cromossomos do amendoim, aumentando o número de células em metáfase e produzindo o espalhamento e o encurtamento dos cromossomos. Isso permite contá-los com a maior facilidade. São apresentados os detalhes da técnica bem como comentários sôbre o modo de ação do paradiclorobenzeno no material em questão.
Estado de agregação da terra-roxa (série chapadão) num ensaio de adubação de milho
Authors: Queiroz Neto José Pereira de , Grohmann F.
Published: March 2010

Com a finalidade de verificar a influência da adubação em cultura de milho sôbre o estado de agregação da terra-roxa (série Chapadão), foram feitas as análises de amostras de solo de um ensaio de adubação conduzido pela Seção de Cereais, a partir de 1963. O ensaio compreendia diversos tratamentos com estêrco, calcário e adubação mineral e fôra instalado em 27 parcelas homogêneas de um solo terra-roxa, da série Chapadão. Os resultados mostraram uma redução considerável do diâmetro médio dos agregados do solo das parcelas cultivadas em relação ao solo não cultivado há anos, que, de 1,25 mm, passou a oscilar normalmente entre 0,50 e 0,79. Um dos fatôres que mais contribuíram para essa quebra de tamanho de agregados foi o preparo intenso do solo. Observou-se uma correlação entre o teor de carbono das amostras e os diâmetros médios dos agregados. A aplicação de estêrco contribuiu para aumentar o tamanho dos agregados, quando não acompanhada de calcário e adubo mineral. Nenhuma correlação foi observada entre o estado de agregação e a produção de milho. A terra-roxa apresenta condições excepcionais de estrutura que permitem até o preparo intenso do solo sem que haja repercussões desfavoráveis sôbre o desenvolvimento dessa planta.
Observações sôbre o arroz dourado-precoce em São Paulo
Authors: Miranda Hilário da Silva , Souza Derly Machado de
Published: March 2010

O arroz Dourado-Precoce tem ciclo curto, 110-120 dias, e porte menor que o Dourado-Agulha, As plantas apresentam maior número de colmos e panículas. A relação comprimento-largura do cariopse é de 2,85, o que o inclui no grupo Agulha, de elevada cotação comercial. Ensaios de campo mostraram que o Dourado-Precoce é pouco menos produtivo que as variedades de arroz comumente indicadas para o cultivo de sequeiro. Apresentando, porém, ciclo mais curto, permite atrasar a época de plantio por quase um mês em relação às das variedades de ciclo normal. Pelo seu ciclo mais curto, a praga de arroz vermelho e prêto poderá ser controlada com maior facilidade.
Análise dos coeficientes de endogamia e de parentesco para qualquer nível de ploidia usando o pacote estatístico R
Authors: Peternelli Luiz Alexandre , Ferreira Fábio Medeiros , Rocha Rodrigo Barros , Barros Willian Silva , Barbosa Márcio Henrique Pereira
Published: March 2010

São poucos os softwares disponíveis para a análise de parentesco e, até a presente data, nenhum pode realizar a análise de parentesco para organismos poliplóides, com número par (2k) de cromossomos. Implementou-se junto ao programa R uma rotina capaz de executar a análise de parentesco para qualquer nível 2k de ploidia, número de indivíduos (ou populações) e número de gerações envolvidas na árvore genealógica. A função principal, calc.rxy() calcula o coeficiente de endogamia (F X) de cada indivíduo; coeficientes de parentesco (rXY) entre dois indivíduos quaisquer; e coeficiente de parentesco médio, variância, mínimo e máximo, para cada indivíduo. Ela pode mostrar a matriz completa de parentesco ou uma submatriz pré-definida de indivíduos selecionados. Adicionalmente, foram incluidas funções que servem para identificar erros de redundância dos dados originais (checar.nomes()) e para identificar os pares de indivíduos com rXY superior a certo limite especificado pelo pesquisador (corte.rxy()). Essas funções podem ser usadas na análise de pedigrees com um número elevado de indivíduos e poderão ser utilizadas pela comunidade científica livremente, sem restrições à plataforma operacional utilizada. Destaca-se a vantagem em se poder trabalhar com qualquer nível 2k de ploidia, mesmo quando existe a possibilidade de certo indivíduo ser oriundo de autofecundação, aspecto comum em várias espécies vegetais.
Enraizamento de estacas de Cana-do-Brejo
Authors: Azevedo Cláudia Pfaltzgraff Mariotto Ferreira de , Ferreira Paulo Cesar , Santos Joaquim Siqueira dos , Pasin Liliana Auxiliadora Avelar Pereira
Published: March 2010

A propagação vegetativa de espécies medicinais vem despertando o interesse de pesquisas agronômicas já que se constitui em ferramenta básica para qualquer cultivo em escala comercial. Neste contexto, este trabalho objetivou avaliar a propagação por estaquia da cana-do-brejo, considerando o tipo de estaca, a presença de folhas e o tipo de substrato no enraizamento. Foram utilizados dois tipos de substrato: areia e um composto 3:2:1 (terra, areia e húmus). Foram utilizadas estacas da porção apical e mediana, com folhas inteiras, meia folha e sem folha. O delineamento experimental foi inteiramente casualizado, com 10 repetições e esquema fatorial 3 x 2 x 2. Aos 60 dias foram avaliados a porcentagem de sobrevivência das estacas, o número de raízes, número de brotos, comprimento de maior raiz e a biomassa seca das raízes. Foram verificados o maior enraizamento e maior número de brotos nas estacas apicais com folha e meia-folha. Nas estacas medianas e apicais sem folha não se observou enraizamento efetivo nos substratos utilizados.
Tolerância de cultivares de cana-de-açúcar a herbicidas aplicados em pós-emergência
Authors: Souza Joseane Rodrigues de , Perecin Dilermando , Azania Carlos Alberto Mathias , Schiavetto Ana Regina , Pizzo Igor Vanzela , Candido Liliam Silvia
Published: March 2010

O presente trabalho teve por objetivo avaliar a tolerância de cultivares de cana-de-açúcar a herbicidas aplicados em pós-emergência inicial da soqueira. O experimento foi implantado em Ribeirão Preto (SP), no ano agrícola de 2007/2008. O delineamento experimental foi de blocos ao acaso, em esquema de parcelas subdivididas com 36 tratamentos em quatro repetições. Foram utilizadas as cultivares IACSP94-2094, IACSP94-2101, IACSP93-3046, IACSP94-4004, RB72454 e a IAC 86-2480 nas parcelas e os herbicidas, constituídos pela mistura pronta de diurom (1170g ha-1) + hexazinona (330 g ha-1); diurom (1865 g ha-1) + hexazinona (234 g ha-1); metribuzim; tebutiuron; amicarbazona e uma testemunha nas subparcelas. Foram avaliados os sintomas visuais de intoxicação, teor relativo de clorofila, eficiência fotoquímica máxima do fotossistema II, altura, estande, qualidade tecnológica da cana e a produção dos colmos. Concluiu-se que as cultivares IACSP94-2094, IACSP94-2101, IACSP93-3046, IACSP94-4004, RB72454 e IAC86-2480 não foram influenciadas pelos herbicidas, apenas ocorreram diferenças inerentes à própria genética. Observou-se apenas leves sintomas de intoxicação na fase inicial de desenvolvimento e não se constatou nenhum prejuízo ao conteúdo de clorofila, avaliado pelo teor relativo de clorofila. No sistema fotossintético houve pequeno prejuízo na fase inicial, quando avaliado pela eficiência fotoquímica máxima do FS II (Fv/Fm), mas que não foi suficiente para prejudicar a altura, o estande, a produção e a qualidade tecnológica das diferentes cultivares de cana-de-açúcar estudadas.
Efeito hormótico de gliphosate no desenvolvimento inicial de cana-de-açúcar
Authors: Silva Marcelo de Almeida , Aragão Natália Carolina , Barbosa Mariana de Almeida , Jeronimo Elisangela Marques , Carlin Samira Domingues
Published: March 2010

Efeito hormótico é definido como o efeito estimulante de pequenas doses de substâncias, as quais em doses maiores são inibitórias. Esta pesquisa objetivou verificar, em casa-de-vegetação, o efeito de subdoses do herbicida gliphosate no desenvolvimento inicial de cana-de-açúcar. Plantas de cana-de-açúcar foram obtidas de gemas isoladas plantadas em vasos plásticos de 2,5 L. Aos 50 dias após o plantio, gliphosate foi aplicado nas doses de 0; 1,8; 3,6; 7,2; 18; 36; 72; 180; 360 e 720 g e.a. ha-1. Aos 0 e 25 dias após a aplicação (DAA) foram avaliados altura da planta, número de perfilhos, número de folhas verdes, número de folhas secas e estimativa do conteúdo de clorofila (índice SPAD). Aos 25 DAA também foram determinadas a massa fresca e seca da parte aérea e raízes das plantas. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições. A dose de 1,8 g e.a. ha-1 de gliphosate estimulou as características de crescimento no desenvolvimento inicial da cana-de-açúcar. Esse efeito hormótico poderá ser utilizado como manejo da cultura para obter melhor exploração do ambiente de produção.