bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrananocrystalline and Nanocrystalline Diamond Thin Films for MEMS/NEMS Applications
Authors: Sumant Anirudha V. , Auciello Orlando , Carpick Robert W. , Srinivasan Sudarsan , Butler James E.
Published: February 2011

There has been a tireless quest by the designers of micro- and nanoelectro mechanical systems (MEMS/NEMS) to find a suitable material alternative to conventional silicon. This is needed to develop robust, reliable, and long-endurance MEMS/NEMS with capabilities for working under demanding conditions, including harsh environments, high stresses, or with contacting and sliding surfaces. Diamond is one of the most promising candidates for this because of its superior physical, chemical, and tribomechanical properties. Ultrananocrystalline diamond (UNCD) and nanocrystalline diamond (NCD) thin films, the two most studied forms of diamond films in the last decade, have distinct growth processes and nanostructures but complementary properties. This article reviews the fundamental and applied science performed to understand key aspects of UNCD and NCD films, including the nucleation and growth, tribomechanical properties, electronic properties, and applied studies on integration with piezoelectric materials and CMOS technology. Several emerging diamond-based MEMS/NEMS applications, including high-frequency resonators, radio frequency MEMS and photonic switches, and the first commercial diamond MEMS product—monolithic diamond atomic force microscopy probes—are discussed.
Graphene: Materially Better Carbon
Authors: Fuhrer Michael S. , Lau Chun Ning , MacDonald Allan H.
Published: February 2011

Graphene, a single atom–thick plane of carbon atoms arranged in a honeycomb lattice, has captivated the attention of physicists, materials scientists, and engineers alike over the five years following its experimental isolation. Graphene is a fundamentally new type of electronic material whose electrons are strictly confined to a two-dimensional plane and exhibit properties akin to those of ultrarelativistic particles. Graphene's two-dimensional form suggests compatibility with conventional wafer processing technology. Extraordinary physical properties, including exceedingly high charge carrier mobility, current-carrying capacity, mechanical strength, and thermal conductivity, make it an enticing candidate for new electronic technologies both within and beyond complementary metal oxide semiconductors (CMOS). Immediate graphene applications include high-speed analog electronics and highly conductive, flexible, transparent thin films for displays and optoelectronics. Currently, much graphene research is focused on generating and tuning a bandgap and on novel device structures that exploit graphene's extraordinary electrical, optical, and mechanical properties.
Epitaxial Graphenes on Silicon Carbide
Authors: First Phillip N. , de Heer Walt A. , Seyller Thomas , Berger Claire , Stroscio Joseph A. , Moon Jeong-Sun
Published: February 2011

This article reviews the materials science of graphene grown epitaxially on the hexagonal basal planes of SiC crystals and progress toward the deterministic manufacture of graphene devices. We show that the growth of epitaxial graphene on Si-terminated SiC(0001) differs from growth on the C-terminated SiC(0001) surface, resulting in, respectively, strong and weak coupling to the substrate and to successive graphene layers. Monolayer epitaxial graphene on either surface displays the expected electronic structure and transport characteristics of graphene, but the non-graphitic stacking of multilayer graphene on SiC(0001) determines an electronic structure much different from that of graphitic multilayers on SiC(0001). This materials system is rich in subtleties, and graphene grown on the two polar faces of SiC differs in important ways, but all of the salient features of ideal graphene are found in these epitaxial graphenes, and wafer-scale fabrication of multi-GHz devices already has been achieved.
Recent Developments in Carbon Nanotube Sorting and Selective Growth
Authors: Liu Jie , Hersam Mark C.
Published: February 2011

Due to their high carrier mobilities, electromigration resistance, and tailorable optical properties, carbon nanotubes are promising candidates for high-performance electronic and optoelectronic applications. However, traditional synthetic methods have lacked control over the structure and properties of carbon nanotubes. This polydispersity problem has confounded efforts to take carbon nanotubes from the research laboratory to the marketplace, especially for electronic and optoelectronic applications, where reliable and reproducible performance is paramount. In recent years, the research community has devoted significant effort to this issue, leading to substantial advances in the preparation of monodisperse carbon nanotube materials. This article highlights the most recent and promising developments from two perspectives: post-synthetic sorting and selective growth of carbon nanotubes of predetermined physical and electronic structure. These complementary approaches have yielded improved uniformity in carbon nanotube materials, resulting in impressive advances in carbon nanotube electronic and optoelectronic technology.
Quantitative In Situ Mechanical Testing in Electron Microscopes
Authors: Legros M. , Gianola D.S. , Motz C.
Published: February 2011

This article is devoted to recent progress in the area of in situ electron microscopy (scanning and transmission) and will focus on quantitative aspects of these techniques as applied to the deformation of materials. Selected recent experiments are chosen to illustrate how these techniques have benefited from improvements ranging from sample preparation to digital image acquisition. Known for its ability to capture the underlying phenomena of plastic deformation as they occur, in situ electron microscopy has evolved to a level where fully instrumented micro- and nanomechanical tests can be performed simultaneously.
In Situ Scanning Probe Microscopy Nanomechanical Testing
Authors: Li Xiaodong , Chasiotis Ioannis , Kitamura Takayuki
Published: February 2011

Scanning probe microscopy (SPM) has undergone rapid advancements since its invention almost three decades ago. Applications have been extended from topographical imaging to the measurement of magnetic fields, frictional forces, electric potentials, capacitance, current flow, piezoelectric response and temperature (to name a few) of inorganic and organic materials, as well as biological entities. Here, we limit our focus to mechanical characterization by taking advantage of the unique imaging and force/displacement sensing capabilities of SPM. This article presents state-of-the-art in situ SPM nanomechanical testing methods spanning (1) probing the mechanical properties of individual one-dimensional nanostructures; (2) mapping local, nanoscale strain fields, fracture, and wear damage of nanostructured heterogeneous materials; and (3) measuring the interfacial strength of nanostructures. The article highlights several novel SPM nanomechanical testing methods, which are expected to lead to further advancements in nanoscale mechanical testing and instrumentation toward the exploration and fundamental understanding of mechanical property size effects in nanomaterials.
In SituElastic Strain Measurements—Diffraction and Spectroscopy
Authors: Spolenak R. , Ludwig W. , Buffiere J.Y. , Michler J.
Published: February 2011

Understanding the mechanical properties of materials is crucial for their reliable application as bulk materials as well as in a miniaturized form. The deformation of materials is usually non-uniform and, hence, needs to be characterized on a local level. The following article focuses on thein-Situdetermination of mechanical stresses in crystalline materials during deformation. This can be achieved by both diffraction as well as spectroscopical methods, where the elastic strain is the parameter measured, which is subsequently converted into stresses by the application of Hooke's law. Asin Situmeasurements require rapid data acquisition in conjunction with reasonable penetration depths, we will focus on x-rays. However, the different techniques described can be applied to any other diffraction probe as well. The description of diffraction techniques, which span the range from averaging techniques to 2D and 3D strain mapping, is complemented by a section on Raman spectroscopy as an alternative method for stress determination for non-metallic materials. Local stresses also can be correlated to local defect densities.
Organic/Inorganic Hybrids for Solar Energy Generation
Authors: Hsu Julia W.P. , Lloyd Matthew T.
Published: February 2011

Organic and hybrid (organic/inorganic) solar cells are an attractive alternative to traditional silicon-based photovoltaics due to low-temperature, solution-based processing and the potential for rapid, easily scalable manufacturing. Using oxide semiconductors, instead of fullerenes, as the electron acceptor and transporter in hybrid solar cells has the added advantages of better environmental stability, higher electron mobility, and the ability to engineer interfacial band offsets and hence the photovoltage. Further improvements to this structure can be made by using metal oxide nanostructures to increase heterojunction areas, similar to bulk heterojunction organic photovoltaics. However, compared to all-organic solar cells, these hybrid devices produce far lower photocurrent, making improvement of the photocurrent the highest priority. This points to a less than optimized polymer/metal oxide interface for carrier separation. In this article, we summarize recent work on examining the polymer structure, electron transfer, and recombination at the polythiophene-ZnO interface in hybrid solar cells. Additionally, the impact of chemical modification at the donor-acceptor interface on the device characteristics is reviewed.
Cooperative Electronic and Magnetic Properties of Self-Assembled Monolayers
Authors: Naaman Ron , Vager Zeev
Published: February 2011

Self-assembled monolayers (SAMs) of organic dipolar molecules have new electronic and magnetic properties that result from their organization, despite the relatively weak interaction among the molecules themselves. Here we review the origin of this cooperative effect and summarize work performed on spin selective electron transmission through SAMs. The spin selectivity observed, in some cases, is consistent with a model in which a SAM containing chiral dipolar molecules behaves like a magnetic layer. The magnetic properties result in the SAMs behaving as spin filters, even without applying an external magnetic field to the layer.
Advances in Scattering Probes for Materials
Authors: Evans Paul G. , Billinge Simon J.L.
Published: February 2011

Recent advances in x-ray and neutron sources, optics, and scattering methods are heralding a new age in the study of the structure and properties of complex materials. By providing unprecedented resolution in real space, reciprocal space, and time, new techniques address materials characterization challenges beyond anything possible before, at length scales ranging from the atomic scale to the mesoscale, and at times as short as femtoseconds. The high degree of coherence of third-generation synchrotron sources permits a new level of precision in the quantitative description and analysis of diffraction and scattering and allows beams with sizes probing individual nanostructures to be produced. As a result, in situx-ray and neutron analysis techniques now provide insight into the structure of nanomaterials and yield a more precise set of metrics describing the nanometer-scale structure of materials. Time resolution and in situ studies allow application of these techniques to materials driven far from equilibrium and to the challenging environment associated with materials processing.
X-Ray Probes for In Situ Studies of Interfaces
Authors: Fong D.D. , Lucas C.A. , Richard M.-I. , Toney M.F.
Published: February 2011

Surfaces and buried interfaces play critical roles in many environmental, catalytic, and tribological processes and in a wide variety of applications, including microelectronics and optoelectronics. Interfacial structure and composition are closely coupled to their surroundings, and probes that yield information about materials in situ are essential to obtain a thorough understanding of interface functions and properties. The highly brilliant, hard x-rays available from synchrotron light sources can easily penetrate through gas or liquid environments, or even solid thin-film overlayers, and enable real-time monitoring of the evolving chemistry and structure of the interface with atomic-scale resolution. Here we review the in situ study of interfaces by a variety of synchrotron x-ray scattering techniques and provide several examples of their application in electrochemical processes and thin-film island growth. We also discuss recent advances in analytical techniques and x-ray optics that are facilitating the in situ study of surfaces and buried interfaces with direct imaging.
Advances in Structural Studies of Materials Using Scattering Probes
Authors: Huq Ashfia , Welberry Richard , Bozin Emil
Published: February 2011

X-ray and neutron diffraction have been two key techniques for structural characterization of materials since their inception. If single crystals of the materials of interest cannot be synthesized, one has to resort to powder diffraction. This results in the loss of three-dimensional orientation information of the crystal, and one has to contend with the one-dimensional information that is inherent to powder diffraction, making it harder to analyze the data. The structural study of contemporary materials and their remarkable properties is a challenging problem, particularly when properties of interest result from interplay of multiple degrees of freedom. Very often these are associated with structural defects or relate to different length scales in a material. The signature of the defect-related phenomenon is visible as diffuse scattering in the diffraction pattern, and the signals associated with diffuse scattering are orders of magnitude smaller than Bragg scattering. Given these limitations, it is crucial to have high-resolution and high-intensity data along with the ability to carry out theoretical interpretation that goes beyond periodic lattice formalism of crystallography. Great advances have been achieved due to the advent of synchrotron and neutron sources, along with the availability of high-speed computational algorithms allowing materials scientists to work with a very small amount of sample (both single crystal and powder) and analyze vast amounts of data to unravel detailed structural descriptions that were not previously possible. This article presents some of these great advances in using scattering probes for materials characterization.
The Polyvalent Gold Nanoparticle Conjugate—Materials Synthesis, Biodiagnostics, and Intracellular Gene Regulation
Authors: Mirkin Chad A.
Published: February 2011

Advances in nanoscale directed assembly strategies have enabled researchers to analogize atomic assembly via chemical reactions and nanoparticle assembly, creating a new nanoscale “periodic table.” We are just beginning to realize the nanoparticle equivalents of molecules and extended materials and are currently developing the ground rules for creating programmable nanometer-scale coordination environments. The ability to create a diverse set of nanoscale architectures from one class of nanoparticle building blocks would allow for the synthesis of designer materials, wherein the physical properties of a material could be predicted and controlled a priori. Our group has taken the first steps toward this goal and developed a means of creating tailorable assembly environments using DNA-nanoparticle conjugates. These nanobioconjugates combine the discrete plasmon resonances of gold nanoparticles with the synthetically controllable and highly selective recognition properties of DNA. Herein, we elucidate the beneficial properties of these materials in diagnostic, therapeutic, and detection capabilities and project their potential use as nanoscale assembly agents to realize complex three-dimensional nanostructures.
Surface Modification Technologies for Durable Space Polymers
Authors: Kleiman J.I.
Published: February 2011

Many polymers, paints, and organic-based materials exposed to the space environment undergo dramatic changes and irreversible degradation of physical and functional characteristics. While many protective approaches, including protective coatings and mechanical metal foil wrapping or cladding—especially for synthesized bulk materials, are used to reduce the effects of the space environment, the protection of such materials in space remains a major challenge, especially for future long-duration exploration missions or permanent space stations. In addition to the traditional approaches, surface modification processes are used increasingly to protect or to impart new properties to materials used in the space environment. This article presents a brief overview of the present situation in the field of surface modification of space materials. A number of surface modification solutions that differ from the traditional protective coating approaches are discussed that change the surface properties of treated materials, thus protecting them from the hazards of low Earth orbit and geostationary orbit environments or imparting new functional properties. Examples of their testing, characterization, and applications are provided.
Lessons from Nature—Biomimetic Approaches to Minerals with Complex Structures
Authors: Sommerdijk Nico A.J.M. , Cölfen Helmut
Published: February 2011

In biology, organic-inorganic hybrid materials are used for several purposes, in particular, for protection and mechanical support. These materials are generally optimized for their function through precise control over the structure, size, shape, and assembly of the component parts and can be superior to many synthetic materials. The shapes and forms of minerals encountered in nature strongly contrast with those that are generally formed in a synthetic environment. According to current understanding, this is achieved through different modes of control: their shape can be controlled by restricting their growth to a confined space or by influencing their preferred direction of growth; in addition, for crystalline materials, polymorph selection and oriented nucleation are achieved through specific interactions between a template or additive and the developing nucleus. Also, controlled arrangement of nanoparticles into superstructures can lead to a complex structure. The understanding and, ultimately, the mimicking of these processes will provide new synthetic routes to specialized organic-inorganic hybrid materials. On the other hand, transformation of existing complex hierarchical natural structures such as wood or diatom frustules into other materials using shape-preserving chemistry is another approach toward minerals with complex biomimetic structure. The theme topic in this issue will focus on recent biomimetic and bioinspired approaches used to achieve control over the shape and organization of mineral and organic-inorganic hybrid materials. The different contributions will also highlight the advantages of these methods for advanced materials synthesis, and possible applications will be discussed.
Templating Approaches Using Natural Cellular Plant Tissue
Authors: Greil Peter
Published: February 2011

Biological preforms such as plant tissue offer a novel approach for manufacturing biomorphous ceramics with an anisotropic cellular micro- and macrostructure pseudomorphous to the natural template structure. Mimicking the hierarchical microstructure of the native template at different length scales from large vessels (mm) down to a cell wall microstructure (μm to nm) offers the possibility to tailor the local strut microstructure in biomorphous ceramics in order to improve mechanical properties at low density. Mineralization may be achieved by intercalation of the cell walls with an inorganic, metal organic, or organometallic sol. Heating above the pyrolysis temperature of the hydrocarbons forming the cell wall material in an inert atmosphere finally results in a positive replica of the cellular structure with a metal oxide/carbon composite forming the cell walls. Amorphous, nano- or microcrystalline C/Si-O-C(-N) composite materials are obtained by infiltration with a low viscosity preceramic polymeric precursor, such as polycarbosilane, -silazane, -siloxane, or a copolymer or mixture thereof. Pyrolysis into a biocarbon template and subsequent metal alloy melt or vapor infiltration and reaction at high temperatures above 1000°C is an alternate way to produce single and multiphase carbides and composites.
Biorenewable Multiphase Polymers
Authors: Robertson Megan L. , Hillmyer Marc A. , Mortamet Anne-Cécile , Ryan Anthony J.
Published: February 2011

Hybrid macromolecules composed of two or more covalently connected segments have the ability to self-assemble into nanostructured materials. These fascinating materials are used in applications ranging from footwear to bitumen modification to microelectronics. The number of technologies that utilize or could benefit from multiphase polymers is expanding at a rapid rate. This growth is due to the development of simple scalable synthetic technologies, a deeper understanding of their structure-property relationships, and their effectiveness as low-level additives. As industrial uses of self-assembled polymers become more prevalent, there will be a heightened focus on alternative preparative approaches that do not rely on petroleum feedstocks. Therefore the development of biorenewable multiphase polymers is an important research endeavor. In this article, we will explore the synthesis, self-assembly, and properties of renewable block and graft copolymers that contain aliphatic polyesters, as well as bio-sourced segmented polyurethanes. These two classes of multiphase polymers are the most promising and practical candidates for implementation in the next generation of sustainable materials.
Bacterial Nanocellulose as a Renewable Material for Biomedical Applications
Authors: Gatenholm Paul , Klemm Dieter
Published: February 2011

Nanocellulose, such as that produced by the bacteria Gluconacetobacter xylinus (bacterial cellulose, BC), is an emerging biomaterial with great potential as a biological implant, wound and burn dressing material, and scaffolds for tissue regeneration. BC has remarkable mechanical properties despite the fact that it contains up to 99% water. The water-holding ability is the most probable reason why BC implants do not elicit any foreign body reaction. Moreover, the nanostructure and morphological similarities with collagen make BC attractive for cell immobilization and cell support. The architecture of BC materials can be engineered over length scales ranging from nano to macro by controlling the biofabrication process. This article describes current and future applications of BC in the biomedical field.
How sunlight became a commodity in Germany
Authors: Ball Philip
Published: February 2011

If you had to guess which country produces the most electrical power from photovoltaics (PV), you would probably draw candidates from sunny places such as the Middle East, the Mediterranean, or the United States. Germany, with its gray northern European skies, seems an unlikely contender.
Macromolecular engineering and stimulus response in the design of advanced drug delivery systems
Authors: Jérôme Christine
Published: February 2011

Extensive research activity is currently devoted to controlled drug delivery systems, mainly as nano-sized particles. Although biocompatible and (bio)degradable polymers play a key role in this field, their shaping into colloidal particles (e.g., polymeric micelles and nanoparticles) usually requires the proper design of amphiphilic copolymers as effective stabilizers. Strategies for synthesizing these copolymers that preserve the intrinsic properties of the constitutive polymers are discussed in this article. Synthesis of amphiphilic copolymers with a more complex structure and endowed with functionality is also considered, with the purpose of enhancing the performance of the nanocarriers. The focus is increasingly on nanocarriers of the third generation, which resist coalescence and elimination by the immune system, and which are readily incorporated into chosen target cells. The more recent quest is for smart nanocarriers that exhibit the additional capacity of being stimuli-responsive.
Opportunities and challenges for first-principles materials design and applications to Li battery materials
Authors: Ceder Gerbrand
Published: February 2011

The idea of first-principles methods is to determine the properties of materials by solving the basic equations of quantum mechanics and statistical mechanics. With such an approach, one can, in principle, predict the behavior of novel materials without the need to synthesize them and create a virtual design laboratory. By showing several examples of new electrode materials that have been computationally designed, synthesized, and tested, the impact of first-principles methods in the field of Li battery electrode materials will be demonstrated. A significant advantage of computational property prediction is its scalability, which is currently being implemented into the Materials Genome Project at the Massachusetts Institute of Technology. Using a high-throughput computational environment, coupled to a database of all known inorganic materials, basic information on all known inorganic materials and a large number of novel “designed” materials is being computed. Scalability of high-throughput computing can easily be extended to reach across the complete universe of inorganic compounds, although challenges need to be overcome to further enable the impact of first-principles methods.
The science of oil drilling goes deep
Authors: Ball Philip
Published: February 2011

Advanced techniques can characterize the physical and chemical properties of oil and the porous rock containing it, but the proof is in the drilling. Spills are an inevitable risk, but natural microorganisms that feed off the hydrocarbons can help to clean them up.
Maintaining Brazil's ethanol fuel momentum
Authors: Robinson Arthur L.
Published: February 2011

The 1973–1974 First Energy Crisis was a cloud with a silver lining for Brazil. A severe negative balance of payments, as oil prices more than quadrupled, stimulated the birth of a bioethanol initiative based on fermented sugarcane, which vaulted the country into today's position as a world leader in the quest for renewable energy that promises to be green, affordable, and secure.
Materials for organic and hybrid inorganic/organic electronics
Authors: Marks Tobin J.
Published: February 2011

Materials scientists involved in synthesis are exceptionally skilled at designing and constructing individual molecules with the goal of introducing rationally tailored chemical and physical properties. However, the task of assembling such special molecules into organized, supramolecular structures with precise, nanometer-level organizational control to execute specific functions presents a daunting challenge. Soft and hard matter suitable for unconventional types of electronic circuitry represents a case in point and, in principal, offer capabilities not readily achievable with conventional silicon electronics. In this context, “unconventional” means circuitry that can span large areas, can be mechanically flexible and/or optically transparent, can be created by large-scale, high-throughput fabrication techniques, and has atomic-level tunability of properties. In the process of preparing, characterizing, and fabricating prototype devices with such materials, we learn many new things about the electronic and electrical properties of the materials and the interfaces between them. This account briefly overviews recent progress in three interconnected areas: (1) organic semiconductors for complementary π-electron circuits, (2) soft matter high-κ gate dielectrics for organic and inorganic electronics, and (3) metal-oxide semiconductors as components in such devices. Space limitations allow only touching upon selected highlights in this burgeoning field.
Computational modeling of actinide materials and complexes
Authors: Söderlind Per , Kotliar G. , Haule K. , Oppeneer P. M. , Guillaumont D.
Published: February 2011

In spite of being rare, actinide elements provide the building blocks for many fascinating condensed-matter systems, both from an experimental and theoretical perspective. Experimental observations of actinide materials are difficult because of rarity, toxicity, radioactivity, and even safety and security. Theory, on the other hand, has its own challenges. Complex crystal and electronic structures are often encountered in actinide materials, as well as pronounced electron correlation effects. Consequently, theoretical modeling of actinide materials and their 5f electronic states is very difficult. Here, we review recent theoretical efforts to describe and sometimes predict the behavior of actinide materials and complexes, such as phase stability including density functional theory (DFT), DFT in conjunction with an additional Coulomb repulsion U (DFT+U), and DFT in combination with dynamical mean-field theory (DFT+DMFT).
Spectroscopic characterization of actinide materials
Authors: Caciuffo R. , Buck E. C. , Clark D. L. , van der Laan G.
Published: February 2011

Advanced spectroscopic techniques provide new and unique tools for unraveling the nature of the electronic structure of actinide materials. Inelastic neutron scattering experiments, which address temporal aspects of lattice and magnetic fluctuations, probe electromagnetic multipole interactions and the coupling between electronic and vibrational degrees of freedom. Nuclear magnetic resonance clearly demonstrates different magnetic ground states at low temperature. Photoemission spectroscopy provides information on the occupied part of the electronic density of states and has been used to investigate the momentum-resolved electronic structure and the topology of the Fermi surface in a variety of actinide compounds. Furthermore, x-ray absorption and electron energy-loss spectroscopy have been used to probe the relativistic nature, occupation number, and degree of localization of 5f electrons across the actinide series. More recently, element- and edge-specific resonant and non-resonant inelastic x-ray scattering experiments have provided the opportunity of measuring elementary electronic excitations with higher resolution than traditional absorption techniques. Here, we will discuss results from these spectroscopic techniques and what they tell us of the electronic and magnetic properties of selected actinide materials.
Factors Influencing the Periodontal Referral Process
Authors: Park Christina H. , Thomas Mark V. , Branscum Adam J. , Harrison Ershal , Al‐Sabbagh Mohanad
Published: February 2011

Background: General dental practitioners (GPs) assess the periodontal status of patients and make decisions to treat patients or refer them to a periodontist. There is little information available regarding this process. The purpose of this study is to identify significant factors that GPs consider important in selecting a particular periodontist. The findings were compared and contrasted with responses of periodontists to gain perspectives from both groups involved in the referral process.

Methods: Data from an online cross‐sectional survey of GPs (n = 533) and periodontists (n = 533) who practice in the southeastern region of the United States (from the databases of the American Dental Association and American Academy of Periodontology member directories) were obtained.

Results: The specialist's clinical skill was identified as the most important factor influencing periodontal referrals by GPs, whereas periodontists identified a previous positive experience between a GP and periodontist as the most important factor. In a descending order of importance, the top three rating averages (rated out of five) by GPs were clinical skill (4.84), a previous positive experience between a GP and periodontist (4.57), and communication (4.52). The top three factors of periodontists were a previous positive experience between a GP and periodontist (4.66), communication (4.40), and the likelihood of a good patient and periodontist rapport (4.29).

Conclusions: The periodontist's clinical skill was chosen by GPs as the primary factor influencing the referral decisions of GPs. Periodontists perceived a previous positive experience between the GP and periodontist as the most influential factor. Further studies are required to gain more insight into the referral process.
Hard and Soft Tissue Changes After Crestal and Subcrestal Immediate Implant Placement
Authors: Koh Richard U. , Oh Tae‐Ju , Rudek Ivan , Neiva Gisele F. , Misch Carl E. , Rothman Edward D. , Wang Hom‐Lay
Published: February 2011

Background: The purpose of this study is to assess the influence of the placement level of implants with a laser‐microtextured collar design on the outcomes of crestal bone and soft tissue levels. In addition, we assessed the vertical and horizontal defect fill and identified factors that influenced clinical outcomes of immediate implant placement.

Methods: Twenty‐four patients, each with a hopeless tooth (anterior or premolar region), were recruited to receive dental implants. Patients were randomly assigned to have the implant placed at the palatal crest or 1 mm subcrestally. Clinical parameters including the keratinized gingival (KG) width, KG thickness, horizontal defect depth (HDD), facial and interproximal marginal bone levels (MBLs), facial threads exposed, tissue–implant horizontal distance, gingival index (GI), and plaque index (PI) were assessed at baseline and 4 months after surgery. In addition, soft tissue profile measurements including the papilla index, papilla height (PH), and gingival level (GL) were assessed after crown placement at 6 and 12 months post‐surgery.

Results: The overall 4‐month implant success rate was 95.8% (one implant failed). A total of 20 of 24 patients completed the study. At baseline, there were no significant differences between crestal and subcrestal groups in all clinical parameters except for the facial MBL (P = 0.035). At 4 months, the subcrestal group had significantly more tissue thickness gain (keratinized tissue) than the crestal group compared to baseline. Other clinical parameters (papilla index, PH, GL, PI, and GI) showed no significant differences between groups at any time. A facial plate thickness ≤1.5 mm and HDD ≥2 mm were strongly correlated with the facial marginal bone loss. A facial plate thickness ≤2 mm and HDD ≥3 were strongly correlated with horizontal dimensional changes.

Conclusions: The use of immediate implants was a predictable surgical approach (96% survival rate), and the level of placement did not influence horizontal and vertical bone and soft tissue changes. This study suggests that a thick facial plate, small gaps, and premolar sites were more favorable for successful implant clinical outcomes in immediate implant placement.
A Clinical and Histologic Evaluation of Gingival Fibroblasts Seeding on a Chitosan‐Based Scaffold and Its Effect on the Width of Keratinized Gingiva in Dogs
Authors: Lotfi Ghogha , Shokrgozar Mohammad Ali , Mofid Rasoul , Abbas Fatemeh Mashhadi , Ghanavati Farzin , Bagheban Alireza Akbarzadeh , Shariati Ramin Pajoum
Published: February 2011

Background:Finding biocompatible matrix materials capable of enhancing the procedures of gingival augmentation is a major concern in periodontal research. This has prompted the investigation of a safe grafting technique by means of synthetic or natural polymers. The objective of this study is to examine the effect of a gingival fibroblast cultured on a naturally derived (i.e., chitosan‐based) scaffold on the width of keratinized gingiva in dogs.

Methods:Gingival fibroblasts were cultured from a small portion of hard palates of five dogs. A bilayered chitosan scaffold was seeded with the gingival fibroblasts and transferred to dogs. Surgery was performed bilaterally, and the regions were randomly divided into two groups: chitosan only (control site) and chitosan + fibroblast (test site). Periodontal parameters, including probing depth and width of keratinized and attached gingiva, were measured at baseline and 3 months after surgery. A histologic evaluation was also performed on the healed grafted sites.

Results:Comparison of width of keratinized and attached gingiva in control and test sites showed that the mean width of keratinized and attached gingiva increased in each group after surgery. However, the difference between control and test groups was not statistically significant. Concerning the existence of the keratinized epithelium, exocytosis, and epithelium thickness, no significant difference was observed in test and control sites. The difference was significant in relation to rete ridge formation.

Conclusion:The tissue‐engineered graft consisting of chitosan + fibroblast was applied to gingival augmentation procedures and generated keratinized tissue without any complications usually associated with donor‐site surgery.
Caries Risk and Periodontitis in Patients With Coronary Artery Disease
Authors: Fadel Hani T. , Al‐Kindy Khalid A. , Mosalli Mohammed , Heijl Lars , Birkhed Dowen
Published: February 2011

Background: There is considerable variation in studies on the oral health of patients with coronary artery disease (CAD). The aims of this investigation are to study the caries risk profile using the Cariogram computer program and the periodontal disease severity in patients with CAD.

Methods: A total of 127 participants (54 test and 73 control) were included. Participants were asked about their general health and daily habits. Clinical examinations, radiographs, and salivary sampling were performed. Cariologic data were entered into the computer program for risk‐profile illustration. The onset of CAD conditions was also documented.

Results: Compared with controls, participants with CAD consumed less sugar, used fluoride toothpaste less frequently, and had significantly less favorable periodontal parameters (P <0.005). Generally, differences in cariologic parameters between the two groups were not significant. Significantly more participants with CAD exhibited low salivary‐secretion rates than controls. The actual chance (percentage) of avoiding new cavities according to the Cariogram was low in the test and control groups (31% and 40%, respectively; P <0.05). Only gingival recession was correlated with the onset of CAD.

Conclusions: Test and control groups had a relatively high caries risk. More severe periodontal disease was observed in participants with CAD.
Clinical and Patient‐Centered Outcomes After Minimally Invasive Non‐Surgical or Surgical Approaches for the Treatment of Intrabony Defects: A Randomized Clinical Trial
Authors: Ribeiro Fernanda V. , Casarin Renato C.V. , Palma Maria A.G. , Júnior Francisco H.N. , Sallum Enilson A. , Casati Márcio Z.
Published: February 2011

Background: The present study aims to compare the performance of minimally invasive non‐surgical and surgical approaches for the therapy of intrabony defects.

Methods: Twenty‐nine patients who presented with intrabony defects were randomly assigned to: 1) a minimally invasive non‐surgical technique (MINST) group, or 2) minimally invasive surgical technique (MIST) group. The chair time of each therapeutic procedure was calculated. The probing depth (PD), position of the gingival margin (PGM) and relative clinical attachment level (RCAL) were evaluated at 3 and 6 months after treatments. The patient perception of discomfort/pain experienced during and after therapy and patient satisfaction regarding treatments were also evaluated.

Results: Significant PD reductions, RCAL gains, and no changes in the PGM were obtained at 3 and 6 months in MINST and MIST groups (P <0.05). No differences were observed between groups at any time points (P >0.05). Patient‐oriented outcomes did not demonstrate differences between therapeutic approaches (P >0.05). Significant higher chair times were required in the MIST group than in the MINST group (P <0.05).

Conclusions: Minimally invasive non‐surgical and surgical approaches were successfully used for the treatment of intrabony defects and achieved periodontal health in association with negligible morbidity and suitable patient satisfaction. However, non‐surgical therapeutic modality presented an advantage in terms of a reduction of treatment chair time.
From mess to mass: a methodology for calculating storm event pollutant loads with their uncertainties, from continuous raw data time series
Authors: Métadier M. , Bertrand-Krajewski J. -L.
Published: February 2011

With the increasing implementation of continuous monitoring of both discharge and water quality in sewer systems, large data bases are now available. In order to manage large amounts of data and calculate various variables and indicators of interest it is necessary to apply automated methods for data processing. This paper deals with the processing of short time step turbidity time series to estimate TSS (Total Suspended Solids) and COD (Chemical Oxygen Demand) event loads in sewer systems during storm events and their associated uncertainties. The following steps are described: (i) sensor calibration, (ii) estimation of data uncertainties, (iii) correction of raw data, (iv) data pre-validation tests, (v) final validation, and (vi) calculation of TSS and COD event loads and estimation of their uncertainties. These steps have been implemented in an integrated software tool. Examples of results are given for a set of 33 storm events monitored in a stormwater separate sewer system.
Studies on photocatalytic activity of the synthesised TiO2 and Ag/TiO2 photocatalysts under UV and sunlight irradiations
Authors: Vaithiyanathan R. , Sivakumar T.
Published: February 2011

Photocatalytic decolorisation and degradation of Reactive Red 120 (RR 120) has been investigated under UV (365 nm) and solar light as radiation sources using synthesised nano titania catalyst prepared via sol-gel method. The study encompassed calcination of synthesised titania catalyst at a range of temperature up to 1,000°C. The effects of calcination temperature on titania catalyst have been evaluated on the decolorisation of RR 120. The analysis revealed complete decolorisation of dye solution in 100 min under UV light with the TiO2 catalyst calcined at 200°C. Only a maximum of 47% dye decolorisation was achieved under sunlight in 4 h with no improvement even after prolonged irradiation. In an endeavour to improve the catalytic activity, bare titania was modified with silver metal and a comprehensive study on the characteristics of silver modified catalyst was made. The result was an enhancement of the rate of decolorisation of dye under both UV and solar light sources. All the catalysts were characterised by XRD and BET analyses. Optimisation of the degradation of RR 120 has been carried out using the unmodified catalyst by varying the amount of catalyst, substrate concentration, pH of dye solution. Effects of addition of small amounts of various oxidants such as H2O2, KBrO3 and (NH4)2S2O8 have also been studied. Pseudo first order kinetics was observed in the photocatalytic decolorisation of dye. The mineralisation of RR 120 was monitored by TOC analysis.
Influence of natural organic matter on equilibrium adsorption of neutral and charged pharmaceuticals onto activated carbon
Authors: de Ridder D. J. , Verliefde A. R. D. , Heijman S. G. J. , Verberk J. Q. J. C. , Rietveld L. C. , van der Aa L. T. J. , Amy G. L. , van Dijk J. C.
Published: February 2011

Natural organic matter (NOM) can influence pharmaceutical adsorption onto granular activated carbon (GAC) by direct adsorption competition and pore blocking. However, in the literature there is limited information on which of these mechanisms is more important and how this is related to NOM and pharmaceutical properties. Adsorption batch experiments were carried out in ultrapure, waste- and surface water and fresh and NOM preloaded GAC was used. Twenty-one pharmaceuticals were selected with varying hydrophobicity and with neutral, negative or positive charge. The influence of NOM competition and pore blocking could not be separated. However, while reduction in surface area was similar for both preloaded GACs, up to 50% lower pharmaceutical removal was observed on wastewater preloaded GAC. This was attributed to higher hydrophobicity of wastewater NOM, indicating that NOM competition may influence pharmaceutical removal more than pore blocking. Preloaded GAC was negatively charged, which influenced removal of charged pharmaceuticals significantly. At a GAC dose of 6.7 mg/L, negatively charged pharmaceuticals were removed for 0–58%, while removal of positively charged pharmaceuticals was between 32–98%. Charge effects were more pronounced in ultrapure water, as it contained no ions to shield the surface charge. Solutes with higher log D could compete better with NOM, resulting in higher removal.
Evaluation of low-cost cathode catalysts for high yield biohydrogen production in microbial electrolysis cell
Authors: Wang L. , Chen Y. , Ye Y. , Lu B. , Zhu S. , Shen S.
Published: February 2011

As an ideal fuel due to the advantages of no pollution, high combustion heat and abundant sources, hydrogen gas can be produced from organic matter through the electrohydrogenesis process in microbial electrolysis cells. But in many MECs, platinum is often used as catalyst, which limits the practical applications of MECs. To reduce the cost of the MECs, Ni-based alloy cathodes were developed by electrodepositing. In this paper hydrogen production using Ni-W-P cathode was studied for the first time in a single-chamber membrane-free MEC. At an applied voltage of 0.9 V, MECs with Ni-W-P cathodes obtained a hydrogen production rate of 1.09 m3/m3/day with an cathodic hydrogen recovery of 74%, a Coulombic efficiency of 56% and an electrical energy efficiency relative to electrical input of 139%, which was the best result of reports in this study. The Ni-W-P cathode demonstrated a better electrocatalytic activity than the Ni-Ce-P cathode and achieved a comparable performance to the Pt cathode in terms of hydrogen production rate, Coulombic efficiency, cathodic hydrogen recovery and electrical energy efficiency at 0.9 V.
Polyhydroxyalkanoates (PHA) biosynthesis from kraft mill wastewaters: biomass origin and C:N relationship influence
Authors: Pozo G. , Villamar A. C. , Martínez M. , Vidal G.
Published: February 2011

The goal of this study is to evaluate the feasibility of PHA biosynthesis from kraft mill effluent using the batch system evaluating the biomass origin and C:N relationship influence. To evaluate feasibility, batch assays were carried out. Also, two levels of the BOD5:N:P relationship (100:5:1 and 100:1:0.2) and three different sludge origins were considered. Inocula were obtained from activated sludge treatment plants for a) sewage (SAS), b) paper mill (PAS) and c) kraft (KAS). The results show that the maximum Biological Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) removal was 80.5% and 59.7% respectively using KAS as inoculum. In these assays, kinetics constants were 17.9±3.2 mg L−1 and 46.5±1.2 d−1 for (KCOD) and (rmax), respectively under a BOD5:N:P relationship of 100:5:1. The maximum PHA accumulation was obtained under a BOD5:N:P relationship of 100:1:0.2 on the third day of batch assays using PAS sludge with 25.72% of the cells accumulating PHA and on the fifth day in batch using SAS and KAS sludge with 25.85% and 30.40% of cells accumulating PHA, respectively. Yields obtained for the 100:1:0.2 relationships ranged from 0.10–0.14 mg PHA mg−1 COD.