bluuebunny/crossref_metadata_2025 huggingface dataset:
MEMS for In Situ Testing—Handling, Actuation, Loading, and Displacement Measurements
Authors: Haque M.A. , Espinosa H.D. , Lee H.J.
Published: February 2011

Mechanical testing of micro- and nanoscale materials is challenging due to the intricate nature of specimen preparation and handling and the required load and displacement resolution. In addition, in Situ testing requires the entire experimental setup to be drastically miniaturized, because conventional high-resolution microscopes or analytical tools usually have very small chambers. These challenges are increasingly being addressed using microelectromechanical systems (MEMS)-based sensors and actuators. Because of their very small size, MEMS-based experimental setups are the natural choice for materials characterization under virtually all forms of in Situ electron, optical, and probe microscopy. The unique advantage of such in Situ studies is the simultaneous acquisition of qualitative (up to near atomic visualization of microstructures and deformation mechanisms) and quantitative (load, displacement, flaw size) information of fundamental materials behavior. In this article, we provide a state-of-the-art overview of design and fabrication of MEMS-based devices for nanomechanical testing. We also provide a few case studies on thin films, nanowires, and nanotubes, as well as adhesion-friction testing with a focus on in Situ microscopy. We conclude that MEMS devices offer superior choices in handling, actuation, and force and displacement resolutions. Particularly, their tight tolerances and small footprints are difficult to match by off-the-shelf techniques.
Ancient Egyptian Pigments: The Examination of Some Coffins from the San Diego Museum of Man
Authors: Scott David A.
Published: February 2011

Egyptian pigments include the most successful synthetic blue pigment made, which has been in use for more than 2500 years. The nature of some Egyptian pigments, such as malachite, azurite, green earth, and calcite are briefly reviewed. The principal artworks examined here are a group of several 26th Dynasty coffins in the collection of the San Diego Museum of Man. This article examines the nature of the wooden substrate, binder, pigments, and alteration products. The conservation needs of the collection are of special importance. The pigments used in the coffins are malachite, orpiment, carbon black, calcite, and red ocher. Gum Arabic was used as a binder. Wood anatomical studies identified fig as the wood. This article also covers the degradation product, oxammite, resulting from the microbiological decay of textile threads on a Hawk Mummy.
Electronic Structure and Dynamics at Organic Donor/Acceptor Interfaces
Authors: Zhu Xiaoyang , Kahn Antoine
Published: February 2011

We present our understanding of the electronic energy landscape and dynamics of charge separation at organic donor/acceptor interfaces. The organic/organic interface serves as a valuable point of reference and plays an important role in emerging electronic and optoelectronic applications, particularly organic photovoltaics (OPVs). The key issue on electronic structure at organic donor/acceptor interfaces is the difference in the lowest unoccupied molecular orbitals or that in the highest occupied molecular orbitals. This difference represents an energy gain needed to overcome the exciton binding energy in a charge-separation process in OPV. A sufficiently large energy gain favors the formation of charge transfer (CT) states that are energetically close to the charge-separation state. At an organic donor/acceptor interface in an OPV device, these high-energy CT states, also called hot CT excitons, are necessary intermediates in a successful charge-separation process.
Time-Resolved X-Ray Scattering from Coherent Excitations in Solids
Authors: Trigo Mariano , Reis David
Published: February 2011

Recent advances in pulsed x-ray sources have opened up new opportunities to study the dynamics of matter directly in the time domain with picosecond to femtosecond resolution. In this article, we present recent results from a variety of ultrafast sources on time-resolved x-ray scattering from elementary excitations in periodic solids. A few representative examples are given on folded acoustic phonons, coherent optical phonons, squeezed phonons, and polaritons excited by femtosecond lasers. Next-generation light sources, such as the x-ray-free electron laser, will lead to improvements in coherence, flux, and pulse duration. These experiments demonstrate potential opportunities for studying matter far from equilibrium on the fastest time scales and shortest distances that will be available in the coming years.
Degradation of Spacecraft Materials in the Space Environment
Authors: Miller Sharon K.R. , Banks Bruce
Published: February 2011

When we think of space, we typically think of a vacuum containing very little matter that lies between the Earth and other planetary and stellar bodies. However, the space above Earth's breathable atmosphere and beyond contains many things that make designing durable spacecraft a challenge. Depending on where the spacecraft is flying, it may encounter atomic oxygen, ultraviolet and other forms of radiation, charged particles, micrometeoroids and debris, and temperature extremes. These environments on their own and in combination can cause degradation and failure of polymers, composites, paints and other materials used on the exterior of spacecraft for thermal control, structure, and power generation. This article briefly discusses and gives examples of some of the degradation experienced on spacecraft and flight experiments as a result of the space environment and the use of ground and space data to predict durability.
Debris/Micrometeoroid Impacts and Synergistic Effects on Spacecraft Materials
Authors: Grossman E. , Gouzman I. , Verker R.
Published: February 2011

In the last 40 years, the increased space activity created a new form of space environment of hypervelocity objects—space debris—that have no functional use. The space debris, together with naturally occurring ultrahigh velocity meteoroids, presents a significant hazard to spacecraft. Collision with space debris or meteoroids might result in disfunction of external units such as solar cells, affecting materials properties, contaminating optical devices, or destroying satellites. The collision normally results in the formation of additional debris, increasing the hazard for future missions. The hypervelocity debris effect is studied by retrieving materials from space or by using ground simulation facilities. Simulation facilities, which include the light gas gun and Laser Driven Flyer methods, are used for studying the materials degradation due to debris impact. The impact effect could be accelerated when occurring simultaneously with other space environment components, such as atomic oxygen, ultraviolet, or x-ray radiation. Understanding the degradation mechanism might help in developing materials that will withstand the increasing hazard from the space debris, allowing for longer space missions. The large increase in space debris population and the associated risk to space activity requires significant measures to mitigate this hazard. Most current efforts are being devoted to prevention of collisions by keeping track of the larger debris and avoiding formation of new debris.
Materials Challenges in Photovoltaic Energy Generation in Space
Authors: Zimmermann Claus G.
Published: February 2011

Virtually all spacecraft employ photovoltaic energy conversion for continuous power generation. Compared to their counterpart on Earth, photovoltaic modules in the space environment face a unique set of performance requirements. Among the most demanding ones are the need to have the highest possible specific power output with regard to mass and surface area while showing as little degradation as possible under intense particle and ultraviolet radiation during lifetimes of up to 15 years. In addition, the thermomechanical stresses induced by temperature fluctuations up to 200°C are not to result in additional electrical degradation. This article briefly outlines the state-of-the-art design solution to meet these requirements before it focuses on current materials issues in two core areas: On the solar cell itself, which requires new materials systems and cell concepts to surpass the efficiency of the lattice-matched triple junction solar cell technology, and on materials issues concerning the encapsulation of solar cells for space use. Closely linked to these materials challenges are testing-related issues that arise in verifying the expected material behavior during extended periods in the space environment. These are discussed in conjunction with the materials challenges.
Materials Screening and Applications of Plasmonic Crystals
Authors: Odom Teri W.
Published: February 2011

Surface plasmon polaritons are responsible for various optical phenomena, including negative refraction, enhanced optical transmission, and nanoscale focusing. Although many materials support plasmons, the choice of metal for most applications has been based on traditional plasmonic materials, such as Ag and Au, because there have been no side-by-side comparisons of different materials on well-defined, nanostructured surfaces. This article will describe how a multiscale patterning approach based on soft interference lithography can be used to create plasmonic crystals with different unit cell shapes—circular holes or square pyramids—which can be used as a platform to screen for new materials. The dispersion diagrams of plasmonic crystals made from unconventional metals will be presented, and the implications of discovering new optical coupling mechanisms and protein-sensing substrates based on Pd will be described. Finally, the opportunities enabled by this plasmonic library to dial into specific resonances for any angle or material will be discussed.
Macromolecular Templating for the Formation of Inorganic-Organic Hybrid Structures
Authors: Kato Takashi , Sakamoto Takeshi , Nishimura Tatsuya
Published: February 2011

Biominerals such as the nacre of shells, spicules of sea urchins, teeth, and bones are inorganic-organic hybrids that have highly controlled hierarchical and complex structures. These structures are formed in mild conditions, and the processes are controlled by macromolecular templates of proteins, peptides, and polysaccharides. Materials scientists can obtain ideas from the structures, properties, and formation processes of biominerals for use in creating synthetic, biomimetic materials. This article highlights bioinspired synthetic approaches to the development of organic/CaCO3hybrids using macromolecular templates. These hybrids have oriented, patterned, and 3D complex structures, as well as thin films with smooth surfaces. The structures are formed by templating synthetic and semisynthetic macromolecules. These materials have great potential for new functional materials.
Quantifying the Kinetics of Crystal Growth by Oriented Aggregation
Authors: Burrows Nathan D. , Yuwono Virany M. , Penn R. Lee
Published: February 2011

Oriented aggregation is a nonclassical crystal growth mechanism resulting in new secondary particles composed of crystallographically aligned primary crystallites. These secondary crystals often have unique and symmetry-defying morphologies, can be twinned, and can contain stacking faults and other significant defects. A wide range of materials, such as titanium dioxide, iron oxides, selenides and sulfides, and metal oxyhydroxides, are known to grow by oriented aggregation under certain conditions. Evidence for oriented aggregation also has been observed in natural materials. Over the last decade, reports of this crystal growth mechanism have appeared with increasing frequency in the scientific literature. The development of kinetic models aimed at improving our fundamental understanding as well as facilitating purposeful control over size, size distribution, and shape has ranged from simple dimer formation models to polymeric models and population balance models. These models have enabled detection and characterization of crystal growth by oriented aggregation using methods such as small-angle x-ray scattering, among others, in addition to transmission electron microscopy. As our fundamental understanding of oriented aggregation improves, novel and complex functional materials are expected to emerge. This article presents a summary of some recent results, methods, and models for characterizing crystal growth by oriented aggregation.
Bioinspired Hierarchical Crystals
Authors: Imai Hiroaki , Oaki Yuya
Published: February 2011

In the sophisticated architectures of various biominerals, a multilevel hierarchy of lengths from nanometers to millimeters is commonly observed. In this article, superstructures composed of inorganic crystals associated with organic molecules from carbonate-based biominerals were identified and categorized as mesocrystals, which are composed of crystallographically oriented crystals. For the production of hierarchically structured mesocrystals, two strategies using self-organized growth with organic agents in aqueous solution systems were proposed. Arranged structures of micrometric and nanometric units were induced with an insoluble gel matrix and soluble adsorbable organic molecules, respectively. Consequently, bioinspired hierarchical crystals were successfully achieved by combining the matrix and soluble species.
Astromaterials Research of Comet Wild 2: Terameters to Nanometers
Authors: Brennan Sean
Published: February 2011

Stardust, a NASA sample return mission, safely landed in the Utah desert in January 2006 after a seven-year mission, bringing with it the first cometary material from a known parent source, Comet 81P/Wild 2. One of the mission goals is to determine the starting material of the solar system. By sampling a comet, which has spent most of the past 4.6 Gyr beyond the orbit of Neptune, we expect to measure material presumed to be unaffected by the ignition of the sun. The Stardust spacecraft swept through the tail of the comet, collecting hundreds of micron-sized particles from that stream into aerogel, a low-density silica foam. An international team of materials scientists have studied the mineralogy, petrology, and elemental and isotopic abundance of these materials. Our group has studied elemental abundance using an x-ray microprobe; the morphology of the particles was examined using an x-ray microscope, which enables nanotomography of the particles while encased in aerogel. The unexpected conclusions are that much of the material from this comet was formed near the sun, after its ignition, and soon thereafter transported to the outer reaches of the solar system. These results have changed the way astrophysicists think about solar system formation.
Materials from Renewable Resources
Authors: Eichhorn Stephen J. , Gandini Alessandro
Published: February 2011

The drive for greater use of renewable materials is one that has recently gained momentum due to the need to rely less heavily on petroleum. These renewable materials are defined as such since they are derived from plant-based sources. Some renewable materials also offer properties that conventional materials cannot provide: hierarchical structure, environmental compatibility, low thermal expansion, and the ability to be modified chemically to suit custom-made applications. Nature's materials, particularly from plant- and animal-based polysaccharides and proteins, have hierarchical structures, and these structures can be utilized for conventional applications via biomimetic approaches. This issue begins with an article covering renewable polymers or plastics that can be used to generate block copolymers (where two polymers with specific functions are combined) as an alternative to conventional materials. Applications of renewable polymers, such as cellulose from plants, bacteria, and animal sources, are also covered. Also presented are the use of bacterial cellulose and other plant-based nanofibers for transparent electronic display screens and, in a wider sense, the use of cellulose nanofibers for composite materials, where renewable resources are required to generate larger amounts of material. Finally, this issue shows the use of biomimetic approaches to take the multifunctional properties of renewable materials and use these concepts, or the materials themselves, in conventional materials applications.
Displays from Transparent Films of Natural Nanofibers
Authors: Nakagaito Antonio Norio , Nogi Masaya , Yano Hiroyuki
Published: February 2011

Organic light-emitting diodes bring a whole new level of image quality, power consumption, and very thin profiles to displays. In addition, with the appropriate choice of a flexible substrate, paper-like flexible displays that are lightweight, robust, and conformable can be produced. This will make it possible to roll or fold the displays for portability or incorporate them in clothing as wearable displays. Plastic substrates are considered prospective materials due to their inherent flexibility and optical qualities. However, one of the major drawbacks of plastics is the large thermal expansion. The thermal expansion of the substrate has to be compatible with those of the layers deposited on it, otherwise these layers will become strained and crack during the thermal cycling involved in the display manufacture. One of the proposed solutions to reduce the thermal expansion of plastics without appreciable loss in transparency is to reinforce them with nanofibers. These nanofibers are already available in enormous quantities in nature, in the form of cellulose, with the caveat that they have to be extracted properly. Here we present the methodologies required to obtain the cellulose nanofibers and to produce optically transparent composites for use in flexible displays.
Biomimetics and Biotemplating of Natural Materials
Authors: Paris Oskar , Burgert Ingo , Fratzl Peter
Published: February 2011

Natural materials display a wealth of structures and fulfill a variety of functions. Hierarchical structuring is one of the keys to providing multifunctionality and to adapting to varying needs of an organism. As a consequence, the natural environment represents not only a direct and renewable source of useful materials, such as wood, plant fibers, or even proteins of pharmaceutical importance, but also an enormous “database” of structures with exceptional mechanical, optical, or magnetic properties. Rather than focusing on the direct use of natural materials, this article discusses the use of structures that appeared in evolution and have been implemented in artificial materials of an entirely different type and chemical composition. This may be done either by directly copying the structure (biotemplating) or by extracting the design principles encoded in them for the fabrication of novel bioinspired materials.
News and analysis on materials solutions to energy challenges
Authors: Arunachalam V.S. , Fleischer E.L.
Published: February 2011

When MRS Bulletin published its expanded special issue in April 2008, “Harnessing Materials for Energy,” it was not a project done lightly. The impetus for this effort was the desire to describe the veritable options that materials provide in energy technologies. These options can then be evaluated in the context of other imperatives such as economic viability and environmental concerns, which all interact to determine societal choices for energy.
Responsive surfaces for biomedical applications
Authors: Neoh K. G. , Kang E. T.
Published: February 2011

Much of the interaction of a material with its environment is governed by its surface, and modulation of the material's surface characteristics can vastly broaden its range of application. This review focuses on the tailoring of surfaces of materials to achieve specific changes in their responses to external stimuli to enhance their prospects for applications in the biomedical field. Combining the inherent properties of different classes of materials such as polymers, metals, mesoporous materials, and magnetic nanoparticles with a responsive surface presents unique opportunities. Applications include surface-modified filters for the effective adsorption and separation of biomolecules, materials for the promotion of cell adhesion or detachment for cell sheet engineering and regenerative medicine, actuators, or valves, and vehicles for the controlled and targeted delivery of therapeutic agents. The commonly used external stimuli are heat, pH, and light, and these, as well as electrical stimulation used in conjunction with conducting polymers, will be addressed in this review. Progress in the field of responsive surfaces has been rapid, and continuing research can be expected to result in more innovative and exciting developments. Nevertheless, much work remains to be done to meet the challenges in the translation of these systems from the laboratory to clinical applications.
Developments in characterizing soft matter
Authors: Donald Athene M.
Published: February 2011

Soft matter—also known as complex fluids—is a field of growing interest and importance, spanning many classes of materials, including polymers, biopolymers, colloids, and liquid crystals. Different approaches for microstructural characterization are more appropriate than those used for hard (and usually fully crystallized) materials such as metals and inorganic materials because of the time and length scales involved. This article discusses a range of techniques applicable to the characterization of soft matter, including environmental scanning electron microscopy (SEM) and microrheology. The former offers two key advantages for this class of material over conventional SEM because it requires neither a high vacuum—which is a problem for hydrated samples—nor that an insulator be coated with a conductive material. Microrheology is well suited to small volumes of fluid with low moduli that may be heterogeneous; it is capable of measuring gelation in real time.
Energy Quarterly
Authors: Yalisove Steve M. , Fleischer Elizabeth L.
Published: February 2011

Exciting and far-reaching experiments in sustainable energy have been conducted for the last 100 years in many parts of the world. Many of the initiatives work in their respective regions because of the availability of raw products or intense political will, as seen in Germany's solar effort and France's nuclear policy. Others result from the need to be self-reliant, such as the Brazilian effort to produce ethanol with their plentiful sugarcane crop and the Danish efforts to harvest offshore wind. Many of these experiments have been carried out at a large scale with the goal of producing more than 10–30% of the regions' energy needs.
Metallic composites processed via extreme deformation: Toward the limits of strength in bulk materials
Authors: Raabe Dierk , Choi Pyuck-Pa , Li Yujiao , Kostka Aleksander , Sauvage Xavier , Lecouturier Florence , Hono Kazuhiro , Kirchheim Reiner , Pippan Reinhard , Embury David
Published: February 2011

We review microstructures and properties of metal matrix composites produced by severe plastic deformation of multiphase alloys. Typical processings are wire drawing, ball milling, roll bonding, equal-channel angular extrusion, and high-pressure torsion of multiphase materials. Similar phenomena occur between solids in frictional contact such as in tribology, friction stir welding, and explosive joining. The resulting compounds are characterized by very high interface and dislocation density, chemical mixing, and atomic-scale structural transitions at heterointerfaces. Upon straining, the phases form into nanoscaled filaments. This leads to enormous strengthening combined with good ductility, as in damascene steels or pearlitic wires, which are among the strongest nanostructured bulk materials available today (tensile strength above 6 GPa). Similar materials are Cu-Nb and Cu-Ag composites, which also have good electrical conductivity that qualifies them for use in high-field magnets. Beyond the engineering opportunities, there are also exciting fundamental questions. They relate to the nature of the complex dislocation, amorphization, and mechanical alloying mechanisms upon straining and their relationship to the enormous strength. Studying these mechanisms is enabled by mature atomic-scale characterization and simulation methods. A better understanding of the extreme strength in these materials also provides insight into modern alloy design based on complex solid solution phenomena.
Atomic-scale design of radiation-tolerant nanocomposites
Authors: Demkowicz M. J. , Bellon P. , Wirth B. D.
Published: February 2011

Recent work indicates that materials with nanoscale architectures, such as nanolayered Cu-Nb composites and nanoscale oxide dispersion-strengthened steels, are both thermally stable and offer improved performance under irradiation. Current understanding of the atomic-level response of such materials to radiation yields insights into how controlling composition, morphology, and interface-defect interactions may further enable atomic-scale design of radiation-tolerant nanostructured composite materials. With greater understanding of irradiation-assisted degradation mechanisms, this bottom-up design approach may pave the way for creating the extreme environment—tolerant structural materials needed to meet the world's clean energy demand by expanding use of advanced fission and future fusion power.
Biomineralization and biotransformations of actinide materials
Authors: Neu Mary P. , Boukhalfa Hakim , Merroun Mohamed L.
Published: February 2011

Microorganisms moderate local chemical conditions and alter forms of metals indirectly or directly to meet their cellular, species, and consortia needs. The diversity of microorganisms and the complexity of biogeochemical systems ensures that bacterially mediated processes yield a wide range of products, which await discovery by material scientists. Few types of materials produced by environmental bacteria have been analyzed by modern chemical and material science methods. Research on actinide biomaterials has focused on the biomineralization of a few chemical forms of uranium, neptunium, and plutonium. The materials produced are molecular complexes, microcrystalline minerals (most commonly oxides and phosphates) within cells and biofilms, and mineral adsorbates. The actinide biomaterials that emerge from this new research area will impact nuclear waste isolation and increase our understanding of environmental and geological metal cycles and may yield new bioremediation methods and industrially useful materials.
Advances in actinide solid-state and coordination chemistry
Authors: Burns Peter C. , Ikeda Yasuhisa , Czerwinski Ken
Published: February 2011

Actinide solid-state and coordination chemistry has advanced through unexpected results that have further revealed the complex nature of the 5f elements. Nanoscale control of actinide materials is emerging, as shown by the creation of a considerable range of cluster and tubular topologies. Departures from established structural trends for actinyl ions are provided by cation-cation interactions in which an O atom of one actinyl ion is an equatorial ligand of a bipyramid of another actinyl ion. The solid-state structural complexity of actinide materials has been further demonstrated by open framework materials with interesting properties. The U(VI) tetraoxide core has been added to this cation's repertoire of coordination possibilities. The emergence of pentavalent uranium solid-state and coordination chemistry has resulted from the prudent selection of ligands. Finally, analogues of the uranyl ion have challenged our understanding of this normally unreactive functional group.
Nanoindentation in materials research: Past, present, and future
Authors: Oliver Warren C. , Pharr George M.
Published: February 2011

The method we introduced in 1992 for measuring hardness and elastic modulus by nanoindentation testing has been widely adopted and used in the characterization of mechanical behavior at small scales. Since its original development, the method has undergone numerous refinements and changes brought about by improvements to testing equipment and techniques, as well as advances in our understanding of the mechanics of elastic-plastic contact. In this article, we briefly review the history of the method, comment on its capabilities and limitations, and discuss some of the emerging areas in materials research where it has played, or promises to play, an important role.
Measuring the Symptom Burden of Lung Cancer: The Validity and Utility of the Lung Cancer Module of the M. D. Anderson Symptom Inventory
Authors: Mendoza Tito R. , Wang Xin Shelley , Lu Charles , Palos Guadalupe R. , Liao Zhongxing , Mobley Gary M. , Kapoor Shitij , Cleeland Charles S.
Published: February 2011

We conducted a study to establish the psychometric properties of a module of the M. D. Anderson Symptom Inventory (MDASI) developed specifically for patients with lung cancer (MDASI-LC). The MDASI measures 13 common “core” symptoms of cancer and its treatment. The MDASI-LC includes the 13 core MDASI symptom items and three lung cancer–specific items: coughing, constipation, and sore throat. MDASI-LC items were administered to three cohorts of patients with lung cancer undergoing either chemotherapy or chemoradiotherapy. Known-group validity and criterion (concurrent) validity of the MDASI-LC were evaluated using the Eastern Cooperative Oncology Group performance status and the 12-item Short-Form Health Survey. The internal consistency and test-retest reliability of the module were adequate, with Cronbach coefficient α-values of 0.83 or higher for all module items and subscales. The sensitivity of the MDASI-LC to changes in patient performance status (disease progression) and to continuing cancer treatment (effects of treatment) was established. Cognitive debriefing of a subset of participants provided evidence for content validity and indicated that the MDASI core items and three additional lung cancer–specific items were clear, relevant to patients, and easy to understand; only two patients suggested additional symptom items. As expected, the item “sore throat” was sensitive only for patients receiving chemoradiotherapy. The MDASI-LC is a valid, reliable, and sensitive symptom-assessment instrument whose use can enhance clinical studies of symptom status in patients with lung cancer and epidemiological and prevalence studies of symptom severity across various cancer types.
Cell‐ and Gene‐Based Therapeutic Strategies for Periodontal Regenerative Medicine
Authors: Rios Hector F. , Lin Zhao , Oh BiNa , Park Chan Ho , Giannobile William V.
Published: February 2011

Inflammatory periodontal diseases are a leading cause of tooth loss and are linked to multiple systemic conditions, such as cardiovascular disease and stroke. Reconstruction of the support and function of affected tooth‐supporting tissues represents an important therapeutic endpoint for periodontal regenerative medicine. An improved understanding of periodontal biology coupled with current advances in scaffolding matrices has introduced novel treatments that use cell and gene therapy to enhance periodontal tissue reconstruction and its biomechanical integration. Cell and gene delivery technologies have the potential to overcome limitations associated with existing periodontal therapies, and may provide a new direction in sustainable inflammation control and more predictable tissue regeneration of supporting alveolar bone, periodontal ligament, and cementum. This review provides clinicians with the current status of these early‐stage and emerging cell‐ and gene‐based therapeutics in periodontal regenerative medicine, and introduces their future application in clinical periodontal treatment. The paper concludes with prospects on the application of cell and gene tissue engineering technologies for reconstructive periodontology.
Autologous Platelet‐Rich Fibrin in the Treatment of Mandibular Degree II Furcation Defects: A Randomized Clinical Trial
Authors: Sharma Anuj , Pradeep A.R.
Published: February 2011

Background: Platelet‐rich fibrin (PRF), an intimate assembly of cytokines, glycan chains, and structural glycoproteins enmeshed within a slowly polymerized fibrin network, has the potential to accelerate soft and hard tissue healing. This double‐masked randomized study is designed to evaluate the effectiveness of autologous PRF in the treatment of mandibular degree II furcation defects compared with open flap debridement (OFD).

Methods: Using a split‐mouth design, 18 patients with 36 mandibular degree II furcation defects were randomly allotted and treated either with autologous PRF and OFD or OFD. Plaque index, sulcus bleeding index, probing depth, relative vertical and horizontal clinical attachment level, gingival marginal level, and radiographic bone defect were recorded at baseline and 9 months postoperatively. Comparison between indices between the test and control groups was performed using the paired t test except for plaque index and sulcus bleeding index data, which used the χ2 test.

Results: All clinical and radiographic parameters showed statistically significant improvement at the sites treated with PRF and OFD compared to those with OFD alone.

Conclusion: Within the limitation of this study, significant improvement with autologous PRF implies its role as a regenerative material in the treatment of furcation defects.
The removal of the trivalent chromium from the leather tannery wastewater: the optimisation of the electro-coagulation process parameters
Authors: GilPavas E. , Dobrosz-Gómez I. , Gómez-García M. Á.
Published: February 2011

The capacity of the electro-coagulation (EC) process for the treatment of the wastewater containing Cr3+, resulting from a leather tannery industry placed in Medellin (Colombia), was evaluated. In order to assess the effect of some parameters, such as: the electrode type (Al and/or Fe), the distance between electrodes, the current density, the stirring velocity, and the initial Cr3+ concentration on its efficiency of removal (%RCr+3), a multifactorial experimental design was used. The %RCr3+ was defined as the response variable for the statistical analysis. In order to optimise the operational values for the chosen parameters, the response surface method (RSM) was applied. Additionally, the Biological Oxygen Demand (BOD5), the Chemical Oxygen Demand (COD), and the Total Organic Carbon (TOC) were monitored during the EC process. The electrodes made of aluminium appeared to be the most effective in the chromium removal from the wastewater under study. At pH equal to 4.52 and at 28°C, the optimal conditions of Cr3+ removal using the EC process were found, as follows: the initial Cr3+ concentration=3,596 mg/L, the electrode gap=0.5 cm, the stirring velocity=382.3 rpm, and the current density=57.87 mA/cm2. At those conditions, it was possible to reach 99.76% of Cr3+removal, and 64% and 61% of mineralisation (TOC) and COD removal, respectively. A kinetic analysis was performed in order to verify the response capacity of the EC process at optimised parameter values.
Investigation of Cu(II) adsorption from aqueous solutions by NKF-6 zeolite
Authors: Zhang H. , Zhao D. , Chen L. , Yu X. J.
Published: February 2011

Adsorption of Cu(II) from aqueous solutions using NKF-6 zeolite was investigated by batch technique under ambient conditions. The adsorption was investigated as a function of pH, ionic strength, fulvic acid (FA), foreign ions and temperature. The results indicated that the adsorption of Cu(II) on NKF-6 zeolite gradually increases from 0 to 90% with increasing pH at pH<6.5, and maintains high level at pH>6.5. Outer-sphere complexation or ion exchange may be the main adsorption mechanism of Cu(II) to NKF-6 zeolite at low pH values, whereas the adsorption of Cu(II) at pH>6.5 is mainly dominated by inner-sphere complexation or precipitation. A positive effect of FA on Cu(II) adsorption onto NKF-6 zeolite is observed at low pH values, while a negative effect of FA is observed at high pH values. The thermodynamic parameters (i.e., ΔH0, ΔS0 and ΔG0) for the adsorption of Cu(II) were determined from the temperature dependent isotherms at 20, 40 and 60°C, respectively, and the results indicated that the adsorption reaction is favoured at low temperature. The results suggested that the adsorption process of Cu(II) on NKF-6 zeolite is spontaneous and exothermic.
Quantification of umu genotoxicity level of urban river water
Authors: Kameya T. , Nagato T. , Nakagawa K. , Yamashita D. , Kobayashi T. , Fujie K.
Published: February 2011

In recent years, the request of environmental safety management for carcinogenic substances, mutagenic substances and/or reproductive toxicity substances (CMR) has increased. This study focused on clarifying the genotoxicity level of environmental water and its release source by using the umu test provided in ISO13829. Although a genotoxicity index “induction ratio (IR)” is used in ISO13829, we normalised it to make it possible to compare various environmental water quantitatively to each other as a new index “genotoxic activity (GA=(IR-1)/Dose)”. Sample water was collected and concentrated to 100 times or 1,000 times by a solid phase extraction method. As the test results, it was found that GA level in actual river water varied widely from less than the determination limit of 23 [1/L] to 1,100 [1/L] by quantitative comparison, and the value was also equivalent to more than 50 times the level of tap water. The GA level of household wastewater was not so high, but the levels of treated water from wastewater treatment plant (WTP) were from 220 [1/L] to 3,200 [1/L]. Raw sewage of some WTP shows high level genotoxicity. A part of genotoxicity substances, for example 50%, could be removed by conventional wastewater treatment, but it was not enough to reduce the water environmental load of genotoxicity.
Comparison of four methods to assess biofilm development
Authors: Alnnasouri M. , Dagot C. , Pons M. -N.
Published: February 2011

Two nondestructive methods of biofilm quantification (optical density via a flatbed scanner and biofilm thickness) have been evaluated and compared to two destructive methods (Crystal Violet staining after biofilm disintegration and dry weight). The methods were tested on biofilms that developed on a modified rotating biological contactor (RBC) that was inoculated with urban wastewater and fed with a synthetic medium that mimicked slaughterhouse wastewater. The results of the different methods were highly correlated (coefficient of correlation greater than 0.8). This validation experiment confirms the ability of the scanning method to easily monitor the biofilm’s development over large surfaces without destruction of the biofilm.
Degradation mechanism of 4-chlorophenol with electrogenerated hydrogen peroxide on a Pd/C gas-diffusion electrode
Authors: Wang H. , Bian Z. Y. , Sun D. Z.
Published: February 2011

Using a self-made Pd/C gas-diffusion electrode as the cathode and a Ti/IrO2/RuO2 anode, the degradation of 4-chlorophenol has been investigated in an undivided electrolysis device by the electrochemical oxidation processes. The result indicated that the neutral aqueous solutions can accelerate 4-chlorophenol degradation during electrolysis. The removal efficiency of 4-chlorophenol and COD reached about 89.6% and 62.0% after 120 min electrolysis, respectively. It suggested that most of 4-chlorophenol was oxidised to intermediates using the Pd/C gas-diffusion electrode. Furthermore, the biodegradation ability of the solution was increased significantly during the electrolysis. The degradation of 4-chlorophenol was attributed to the cooperative oxidation processes including electrochemical oxidation at the anode and H2O2 and hydroxyl radical (HO·) produced by the reduction of oxygen at the cathode. Finally, main aromatic intermediates (e.g., hydroquinone and benzoquinone) and main aliphatic carboxylic intermediates (e.g., oxalic, malonic, maleic, succinic, fumaric, and dodecanoic acids) were identified by GC-MS. Moreover, a reaction scheme involving all these intermediates was proposed.
The effects of nutrient limitation (nitrogen and phosphorus) on BOD removal from post-coagulated Pinus radiata sulfite pulp and paper mill wastewater in a baffled aerated stabilisation basin–laboratory pilot scale study
Authors: Dewi R. , Van Leeuwen J. A. , Everson A. , Nothrop S. C. , Chow C. W. K.
Published: February 2011

The use of coagulation and flocculation for tertiary treatment of pulp and paper mill effluent was investigated, where the evaluation was based on the removal of nitrogen (N), phosphorus (P) and BOD from post-coagulated wastewater. The study was undertaken on laboratory scale aerobic stabilisation basins (ASB). Two post coagulated (alum) wastewaters were studied, where the BOD:N:P ratios were 100:1.3:0.06 and 100:1.3:0.3. These wastewaters were treated in two identical concurrent simulations (A & B). The influent ratio for ‘A’ was selected representing the composition of actual coagulated Pinus radiata sulfite pulp effluent mixed with paper mill effluent. The input composition for ‘B’ represented a typical P concentration found in existing pulp and paper mill effluents. Unmodified sludge collected from a mill-pond was added at 4% v/v to each simulation replicating the treatment conditions at full-scale. Similar high percentage removals of BOD and COD occurred after 28 days (two HRTs) which were 94 and 67% respectively for ‘A’, and 98 and 70% respectively for ‘B’, where both remained at steady state during the third HRT. A statistical analysis of the data revealed that there was no significant difference in the sample variance of the BOD and COD results.
Photocatalytic oxidation of ammonia by cadmium sulfide/titanate nanotubes synthesised by microwave hydrothermal method
Authors: Chen Y. -C. , Lo S. -L. , Ou H. -H. , Chen C. -H.
Published: February 2011

CdS/Titanate nanotubes (TNTs) were successfully synthesised by a simple, rapid, and reliable microwave hydrothermal method. The CdS nanoparticles synthesised using a 140-W microwave irradiation power at 423 K photodegraded 26% ammonia in water, while the photocatalytic efficiency increased to 52.3% using the synthesised CdS/TNTs composites. The results indicated that the CdS/TNTs photocatalysts possess improved photocatalytic activity than that of CdS or TNTs materials alone.
Long-term survival of Escherichia coli in lightweight aggregate filter media of constructed wastewater treatment wetlands
Authors: Paruch A. M.
Published: February 2011

A laboratory scale experiment on the survival of Escherichia coli in samples of filter media from a horizontal subsurface flow constructed wetland treating domestic wastewater was performed. A concentration of E. coli was examined in samples collected from a wetland filter filled with lightweight aggregates (LWA). All samples testing positive for E. coli contamination were used to examine the effect of storage time on the survival of E. coli at three temperature regimes: cold (4°C), mild (10°C) and warm (22°C). It was found that the mild storage condition favoured the growth and survival of E. coli in the tested LWA media. The growth in samples of the uppermost layer of the media lasted for 5.5 months, during which E. coli reached a maximum concentration of 6.4 × 103 MPN/100 g dry matter in the media. It was also observed that E. coli had a greater capacity to survive for extended periods of time in samples collected from the upper layer of the LWA filter compared to samples taken from the deeper layers. The survival of E. coli in the shallowest samples of the wetland filter was remarkably long and unexpected, lasting for a period of over 14 months.
Network Architecture and the Left-Right Spectrum
Authors: Taubinsky Dmitry
Published: February 2011

We study a model of opinion formation and analyze the link between network architecture and the “left-right spectrum” that frequently characterizes opinions and beliefs. We correct a key result of DeMarzo, Vayanos and Zwiebel (QJE, 2003) who claim that after some time, an agent’s position on a set of different issues will always be either “left” on all of those issues or “right” on all of those issues. We provide counterexamples to this claim and show that in the long-run an agent’s position can flip-flop between “left” on all issues and “right” on all issues indefinitely. However, we provide necessary and sufficient conditions for a stable left-right characterization of opinions to be possible in the long run. Roughly, a flip-flop will occur when agents give relatively little weight to the opinions of agents with similar political positions (including themselves). Following this intuition, we show that a simple sufficient condition is that agents become “stubborn” over time and give little weight to the opinions of others. Finally, we characterize classes of networks in which it is possible for agents to flip-flop between “left” and “right” indefinitely. We argue that qualitatively, these results are robust to alternative models of opinion formation.
A New-Generation Ultra-Long-Acting Basal Insulin With a Bolus Boost Compared With Insulin Glargine in Insulin-Naïve People With Type 2 Diabetes
Authors: Heise Tim , Tack Cees J. , Cuddihy Robert , Davidson Jaime , Gouet Didier , Liebl Andreas , Romero Enrique , Mersebach Henriette , Dykiel Patrik , Jorde Rolf
Published: February 2011

OBJECTIVE

Insulin degludec/insulin aspart (IDegAsp) is a soluble coformulation of the novel basal analog insulin degludec (IDeg: 70%) and insulin aspart (IAsp: 30%). We compared the safety and efficacy of IDegAsp, an alternative formulation (AF) (55% IDeg and 45% IAsp), and insulin glargine (IGlar) in insulin-naïve subjects with type 2 diabetes inadequately controlled with oral antidiabetic drugs.

RESEARCH DESIGN AND METHODS

In this 16-week, open-label trial, subjects (mean age 59.1 years, A1C 8.5%, BMI 30.3 kg/m2) were randomized to once-daily IDegAsp (n = 59), AF (n = 59), or IGlar (n = 60), all in combination with metformin. Insulin was administered before the evening meal and dose-titrated to a fasting plasma glucose (FPG) target of 4.0–6.0 mmol/L.

RESULTS

After 16 weeks, mean A1C decreased in all groups to comparable levels (IDegAsp: 7.0%; AF: 7.2%; IGlar: 7.1%). A similar proportion of subjects achieved A1C <7.0% without confirmed hypoglycemia in the last 4 weeks of treatment (IDegAsp: 51%; AF: 47%; IGlar: 50%). Mean 2-h postdinner plasma glucose increase was lower for IDegAsp (0.13 mmol/L) and AF (0.24 mmol/L) than IGlar (1.63 mmol/L), whereas mean FPG was similar (IDegAsp: 6.8 mmol/L; AF: 7.4 mmol/L; IGlar: 7.0 mmol/L). Hypoglycemia rates were lower for IDegAsp and IGlar than AF (1.2, 0.7, and 2.4 events/patient year). Nocturnal hypoglycemic events occurred rarely for IDegAsp (1 event) and IGlar (3 events) compared with AF (27 events).

CONCLUSIONS

In this proof-of-concept trial, once-daily IDegAsp was safe, well tolerated, and provided comparable overall glycemic control to IGlar at similar low rates of hypoglycemia, but better postdinner plasma glucose control.
Speed Enforcement Cameras in Charlotte, North Carolina
Authors: Moon Jae-Pil , Hummer Joseph E.
Published: February 2011

The City of Charlotte, North Carolina, conducted a pilot evaluation of the safety effect of speed enforcement cameras. The city selected 14 key corridors with high collisions, and an automated speed enforcement camera program was implemented in the corridors scattered throughout Charlotte from September 2004 through July 2006. In addition to comparing the net safety effectiveness before and after implementation of automated speed cameras, this study estimated long-term collision patterns from the speed enforcement program with the carryover safety effects after its termination by using an autoregressive integrated moving average (ARIMA) intervention analysis as well as a before–after analysis with comparison sites. The fitted ARIMA intervention model indicated that the treatment corridors demonstrated a significant reduction in collisions over the study periods. Furthermore, the speed camera program appeared to have significant carryover effects into the postintervention period, but collisions slowly returned to original levels. The before–after analysis with comparison sites also provided evidence that the effect of the speed camera program was to decrease collisions in the postintervention period.