bluuebunny/crossref_metadata_2025 huggingface dataset:
Conduction Band Edge of TiO2-SnO2 Solid Mixtures Tuning for Photoelctrochemical Applications
Authors: Simiyu Justus , Aduda Bernard , Mwabora Julius Mwakondo
Published: September 2009

We report investigation of effect of conduction band edge on the dye injection and transport by preparation of (Ti,Sn)O2 solid mixtures in ratios of 80:20 and 90:10 as possible applications in dye sensitized solar cells. SEM micrographs showed highly porous with nanometer sized particles of around 6 - 10μm diameter. X-ray diffraction patterns showed strong TiO2 anatase peaks with crystal orientation directions (101) being the strongest in both the solid mixtures and in pure TiO2. XPS studies have shown an apparent chemical shift for Ti 2p and O1s core level spectra with an energy difference between the unmodified and the solid mixture being 0.65eV. Initial I-V studies have shown high Voc but low short circuit photocurrent, showing a possible unfavorable band edge shift between the semiconductor and the dye LUMO level.
Hybrid Gold Architectures for Sensing and Catalytic Applications
Authors: Song Hyunjoon
Published: September 2009

Exquisite control of surface functionality is essential to tailor the chemical and physical properties of metal nanocrystals to the requirements of specific applications. Hybridization of gold nanoparticles with other components such as polymers and metal oxides can effectively introduce appropriate functionalities on the surface without changing their own properties, and thereby become a basic architecture for various applications such as sensors and catalysts. In the present work, we report two hybrid nanostructures comprising gold nanocrystals. PDMAEMA (poly(dimethylaminoethylmethacrylate))–gold hybrid nanocrystals were synthesized via a polyol process, which produced carboxylate functionality on the gold surface. This hybrid structure was employed for a sensitive pH-sensor in solution. On the other hand, porous silica-gold hybrid nanoreactors were produced by selective etching of gold cores from gold@silica core-shell particles. The nanoreactor framework exhibited high and controllable activity on the reduction of aromatic nitroxides. These two examples of hybrid gold architectures would be able to apply for other metal and metal oxide systems to develop biosensors and energy production catalysts.
Seedless Templated Growth of Hetero-Nanostructures for Novel Microelectronics Devices
Authors: Iacopi Francesca , Rooyackers Rita , Loo Roger , Vanherle Wendy , Milenin Alexey , Arstila Kai , Verhulst Anne , Takeuchi Shotaro , Bender Hugo , Caymax Matty , Hantschel Thomas , Vandooren Anne , Vereecken Philippe M , De Gendt Stefan , Heyns Marc
Published: September 2009

The feasibility of a templated seedless approach for growing segmented p-i-n nanowires –based diodes based on selective epitaxial growth is demonstrated. Such diodes are the basic structure for a TunnelFET device. This approach has the potential for being easily scalable at a full-wafer processing, and there is no theoretical limitation for control on nanowires growth and properties when scaling down their diameters, as opposed to an unconstrained vapor-liquid-solid growth. Moreover, Si/SixGe1-x hetero-structures are implemented, showing that this can improve the TFET ON current not only thanks to the lowered barrier for the band-to-band source-channel tunneling, but additionally thanks to its lower thermal budget for growth, allowing for better control of the abruptness of the doping profile at the source-channel tunneling interface.
Synthesis and Electrical Characterization of Tin Oxide Nanostructures
Authors: Berengue Olivia Maria , Dalmaschio Cleocir J. , Conti Tiago G. , Chiquito Adenilson J. , Leite Edson R.
Published: September 2009

Sn3O4 nanobelts were grown by a carbothermal evaporation process of SnO2 powders in association with the well known vapour-solid mechanism (VS). The nanobelts crystal structure was investigated by x-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), raman spectroscopy and field emission gun scanning electron microscopy (FEG-SEM). The structural and morphological characterization has confirmed the growth of single crystal nanobelts. The electrical characterization (current-voltage, temperature-dependent resistance curves) of individual Sn3O4 nanobelts was performed at different temperatures and light excitation. The experiments revealed a semiconductor – like character as evidenced by the resistance decreasing at high temperatures. The transport mechanism was identified as the variable range hopping.
Optical and Electrical Properties of TiO2 Nanotubes Grown by Titanium Anodization
Authors: Alivov Yahya , Kuryatkov Vladimir , Pandikunta Mahesh , Rajanna Gautam , Johnstone Daniel , Bernussi Ayrton , Nikishin Sergey A , Fan Z. Y.
Published: September 2009

In this work we investigated the structural, electrical, and optical properties of titanium dioxide (TiO2) nanotubes (NTs) formed by electrochemical anodization of Ti metal sheets in NH4F+glycerol electrolyte at different anodization voltages (Va) and acid concentrations. Our results revealed that TiO2 NTs can be grown in a wide range of anodization voltages from 10 V to 240 V. The maximum NH4F acid concentration, at which NTs can be formed, decreases with the anodization voltage, which is 0.7% for Va<60V, and decreases to 0.1% at Va =240 V. Glancing angle X-ray diffraction (GAXRD) experiments show that as-grown amorphous TiO2 transforms to anatase phase after annealing at 400 oC, and further transforms to rutile phase at annealing temperatures above 500 oC. Samples grown in 30-120 voltage range have higher crystal quality as seen from anatase (101) peak intensity and reduced linewidth. The electrical resistivity of the NTs varies with Va concentration and increases by eight orders of magnitude when Va increases from 10 V to 240 V. This is consistent with cathodoluminescense studies which showed improved optical properties for samples grown in this voltage range. Optical properties of samples were also studied by low temperature photoluminescence. Temperature dependent I-V and photo-induced current transient spectroscopy were employed to analyze electrical properties and defect structure on NT samples.
Mechanical Properties of Polymer Blends Having Shape-memory Capability
Authors: Behl Marc , Ridder Ute , Wagermaier Wolfgang , Kelch Steffen , Lendlein Andreas
Published: September 2009

The general design principle of shape-memory polymers (SMP) requires two key compo-nents: covalent or physical crosslinks (hard domains) determining the permanent shape and switching domains fixing the temporary shape as well as influencing the switching temperature Tsw. In conventional thermoplastic SMP hard and switching domains determining segments are combined in one macromolecule, e.g. block copolymers such as polyurethanes. Recently, binary polymer blends having shape-memory properties, from two different multiblock copolymers have been presented, whereby the first one is providing the segments forming hard domains and the second one the segments forming the switching domains. Besides the shape-memory proper-ties, the mechanical properties of such materials are application relevant. Here we investigate how the blend composition influences mechanical properties of this new class of shape-memory materials.
Multiphase Polymer Networks with Shape-Memory
Authors: Kelch Steffen , Behl Marc , Kamlage Stefan , Lendlein Andres
Published: September 2009

Tailoring of properties and functions of shape-memory polymer networks to the requirements of specific applications demands a knowledge-based approach. A comprehensive database enabling the analysis of structure-property relationships is obtained by the systematic variation of molecular parameters. In detail we investigated the influence of the nature of thermal transition on the shape-memory behavior of polymer networks. Furthermore, additional amorphous phases were introduced enabling tailoring of elastic properties especially in the temporary shape as a consequence of the formed polymer morphology. Enabling higher elasticity, adjustable hydrolytic degradability, and the possibility to tailor the transition temperature of shape-memory to a temperature between room temperature and body temperature are considered to be substantial steps to improve the applicability of these active polymers in medicine.
Shape-Memory Properties of Radiopaque Micro-Composites from Amorphous Polyether Urethanes Designed for Medical Application
Authors: Cui Jing , Kratz Karl , Lendlein Andreas
Published: September 2009

Biocompatible shape-memory polymers are of high significance for application in medical devices or instruments for minimally invasive surgery. To follow the medical device placement or changes in shape of the device in vivo by imaging methods like X-ray techniques, radiopacity of the polymer is required. In this work, we explored the shape-memory properties of radiopaque polymer composites prepared by incorporation of barium sulphate micro-particles in a biomedical grade polyether urethane (PEU) by co-extrusion technique. The filler content was varied from 5 wt% to 40 wt%, which was confirmed by thermal gravimetric analysis (TGA) measurements, while the particle distribution was visualized by scanning electron microscopy (SEM). The thermal and mechanical properties of the composites were investigated by means of dynamic mechanical analysis at varied temperature (DMTA) and tensile tests. The shape-memory properties of PEU composites were quantified in cyclic, thermomechanical experiments.
A significant increase in Young’s modulus and a decrease in elongation at break were observed for PEU composites with increasing content of BaSO4, while the DMTA results were not affected by incorporation of the fillers. All samples exhibited excellent shape-memory properties with shape fixity rates (Rf) above 98% and values for shape recovery rate (Rr) in the range of 81% to 93%. The maximum stress (σmax) obtained under constant strain recovery conditions increased from 0.6 MPa to 1.4 MPa with raising amount of BaSO4, while the corresponding temperature (Tσ,max) as well as the switching temperature (Tsw) determined under stress-free conditions remained constant for all polymer composites.
Thermomechanical Behaviour of Biodegradable Shape-memory Polymer Foams
Authors: Madbouly Samy A , Kratz Karl , Klein Frank , Lüetzow Karola , Lendlein Andreas
Published: September 2009

Shape-memory polymer foams based on poly(ω-pentadecalactone) (PPDL) and poly(ε-caprolactone) (PCL) multiblock copolymer with 60 wt% PCL content were prepared by environmentally-friendly high pressure supercritical carbon dioxide scCO2 foaming technique. A foam with a density of approximately 0.11 ± 0.02 g/cm3 and an average pore size of 150-200 μm with excellent compressibility and shape-memory properties was created at 25 bar/s depressurization rate in the temperature range between 78 and 84 °C. The shape-memory behavior of this foam was investigated using different programming modules, such as, under stress-free condition and under constant strain condition. The thermally-induced shape-memory effect (SME) was found to be strongly dependent on the programming conditions. Excellent shape fixity has been observed for all foams indicating the high efficiency of the switching domains to fix the temporary shape by crystallization. The stress recovery of this foam could be controlled by changing compression percentage (εc%) at a constant compression temperature. The production of these foams with unprecedented properties by commercially available processing equipment raises much hope with the potential to provide new materials with a unique combination of shape-memory properties and porous structure as well as desired properties for many industrial and biomedical applications
The Normal and Shear Strength of the Cell-Implant Interface: Accelerated Negative Buoyancy as a Method of Cell Adhesion Assessment
Authors: Griffiths Helen J , Collier Charles Andrew , Clyne T William
Published: September 2009

The strength of adhesion at the cell-substrate interface is an important parameter in the design of many prosthetic implant material surfaces, due to the desire to create and maintain a strong implant-tissue bond. This study focuses on the mechanical strength of the interface and the ease of cell removal from ceramic coatings using normal and shear forces, but also looks at cell proliferation rates on the same series of surfaces.

This systematic study of cell proliferation and adhesion has been carried out on a series of oxide coated Ti6Al4V based substrates with a range of surface morphologies and chemistries. Oxide coatings were formed using Plasma Electrolytic Oxidation (the PEO process).
Cells were seeded at a low concentration onto substrates and proliferation monitored for up to three weeks. The same cell concentrations were seeded on samples for adhesion testing. These were cultured for a few days to ensure well established adhesion of viable cells. The normal and shear strength of osteoblasts (bone cells) and chondrocytes (cartilage cells) adhered to these substrates was measured using accelerated negative buoyancy within an ultracentrifuge.

The variation in proliferation rates on, and adhesive strengths to, the range of coatings, is discussed and related to morphological and chemical differences in the coatings. A comparison is made between the normal and shear strengths of the cell-coating bonds and the differences between the behaviour of the two cell types discussed.
The MAESFLO Device: A Complete Microfluidic Control System
Authors: Goulpeau Jacques , Taniga Vélan , Kieffer Charles-André
Published: September 2009

In spite of considerable efforts, flow control in micro-channels remains a challenge owing to the very small ratio of channel/supply-system volumes, as well as the induction of spurious flows by extremely small pressure or geometry changes. We present here a robust and complete system for flow control in complex microchannel network that both monitors and controls all the flow relevant parameters, that is to say flow rate and pressure. Based on a dynamic control of reservoir pressures at the end of each channel and external thermal flow-sensors, all the parameters are measured with a precision down to 25 μBar and 2nL/min. Thanks to adaptative feed back control loop, the MAESFLO can control either the flow rate or the pressure with high stability over long period whatever the microsystem characteristics. Compared to classic pumps, a significant increase of stability has been reached as no mechanical parts are involved. Indeed the flow rate is pulse free and is stable down to 0.1% of the full scale. Besides, pressure control enables to achieve short response time (less than hundreds of millisec). The MAESFLO is thus a unique system to control flow in complex network architecture and can be considered as an alternative to integrated micro-valves using only external equipments. Indeed, the MAESFLO can stop the flow to nearly zero in one or several branches of a complex microfluidic network while keeping other flows constant. Sequential manipulation of liquids in a definite part of a micro-device is thus possible without expensive and time consuming fabrication processes. It can be particularly useful when dealing with washing steps in the case of biological assay for example. Controlling flow with short response time along with high precision is also a key issue in microfluidic. By combining pressure actuation with flowrate monitoring, short response time are achievable keeping a high precision flow rate. It can be particularly useful for droplet generation and size control, droplet on demand generation, long time living cell perfusion and drug injection… In this work we will present the benefit to control and monitor both pressure and flow rate with the MAESFLO. A lot of information can be extracted from these simple parameters, as hydraulic resistance, monophasic and biphasic apparent viscosity, the volume and the position of a trapped air bubble and many more. The proof of concept of stop flow control will also be shown with experimental results stressing the advantages of the “virtual micro-valve”.
Miniaturized Silicon Apertures for Lipid Bilayer Reconstitution Experiments
Authors: Goryll Michael , Chaplot Nipun
Published: September 2009

Ion channels reconstituted into lipid bilayer membranes can be used as a very sensitive and selective platform for high-throughput drug screening applications. In order to employ suspended lipid bilayer membranes for these experiments in form of a “lab-on-a-chip” configuration, a robust and affordable platform is required. In our study, we investigated the feasibility of hosting lipid bilayer membranes across micron-size apertures ranging from 5 μm – 50 μm in silicon. On these substrates, lipid bilayers were formed and characterized concerning their seal resistance, capacitance and breakdown voltage. Seal resistance values of up to 60 GΩ could be achieved repeatedly on these substrates.
Efficient Nanoporous Silicon Membranes for Integrated Microfluidic Separation and Sensing Systems
Authors: Ileri Nazar , Létant Sonia E. , Britten Jerald , Nguyen Hoang , Larson Cindy , Zaidi Saleem , Palazoglu Ahmet , Faller Roland , Tringe Joseph W. , Stroeve Pieter
Published: September 2009

Nanoporous devices constitute emerging platforms for selective molecule separation and sensing, with great potential for high throughput and economy in manufacturing and operation. Acting as mass transfer diodes similar to a solid-state device based on electron conduction, conical pores are shown to have superior performance characteristics compared to traditional cylindrical pores. Such phenomena, however, remain to be exploited for molecular separation. Here we present performance results from silicon membranes created by a new synthesis technique based on interferometric lithography. This method creates millimeter sized planar arrays of uniformly tapered nanopores in silicon with pore diameter 100 nm or smaller, ideally-suited for integration into a multi-scale microfluidic processing system. Molecular transport properties of these devices are compared against state-of-the-art polycarbonate track etched (PCTE) membranes. Mass transfer rates of up to fifteen-fold greater than commercial sieve technology are obtained. Complementary results from molecular dynamics simulations on molecular transport are reported.
Doped ZnO Colloids for Cancer Detection - Bio-Imaging and Cytotoxicity Study
Authors: Wu Linda Y.L. , Loh June , Fu Sheng , Tok Alfred I.Y. , Zeng Xianting , Kwek Leong Chuan , Boey Freddy Y.C.
Published: September 2009

We report the synthesis and surface modification of bio-friendly ZnO based colloids, which have been used for cancer cell detection providing significant advantages on quantum confinement effects, high emission brightness in UV to blue-violate range, non-toxicity and a unique dual color imaging feature. The ZnO nanoparticles were single crystal nanoparticles having spherical shape in size of 1-2 or 4-5 nm depending on the surface capping agents. All the colloidal solutions were stable for 30-45 days. The surface capping is a more effective technique in controlling the nanoparticle size, while dopants are effective in modifying the bandgap and optical properties. Unique dual colour images with blue colour in nucleus and turquoise colour in cytoplasm were obtained using either pure ZnO or Co doped ZnO colloids on human osteosarcoma (Mg-63) cells. The dual colour function is the combined effects of quantum confinement and the bio-compatible surface capping groups. The cytotoxicity study proved no cell proliferation by the nanoparticles up to the concentration of 1000 μg/mL, which is the highest concentration reported so far. Since a dosage of only 50-100μM is enough for the in vivo detection on rate, these ZnO colloids have high potential for use as the detection media for Lab-on-a-Chip devices.
A incorporação de novos temas e saberes nos estudos em saúde coletiva: o caso do uso da categoria gênero
Authors: Villela Wilza , Monteiro Simone , Vargas Eliane
Published: September 2009

Este artigo objetiva refletir sobre a incorporação da categoria gênero nos estudos acadêmicos em saúde coletiva, tendo por referência algumas das características da área, como a interdisciplinaridade, o compromisso com as demandas da sociedade, o diálogo com os trabalhadores de saúde e a sintonia com as políticas de saúde implementadas no país. Para tanto, foi realizado um levantamento dos artigos indexados na base SciELO que referem gênero e saúde como descritores, classificando-os quanto aos temas em foco, à abordagem metodológica, à população estudada e ao tipo de uso da categoria gênero. A análise dos resultados revela a heterogeneidade no uso da categoria na produção acadêmica selecionada, que, eventualmente, pode ser explicada pelas especificidades da área. Pretende-se, com este trabalho, fomentar a reflexão sobre maneiras de incrementar a abordagem de gênero nos estudos em saúde coletiva de modo a superar diferenças entre os campos de conhecimento.
AN EVALUATION OF THE RELATIVE EFFICACY OF AND CHILDREN'S PREFERENCES FOR TEACHING STRATEGIES THAT DIFFER IN AMOUNT OF TEACHER DIRECTEDNESS
Authors: Heal Nicole A. , Hanley Gregory P. , Layer Stacy A.
Published: September 2009

The manner in which teachers mediate children's learning varies across early childhood classrooms. In this study, we used a multielement design to evaluate the efficacy of three commonly implemented strategies that varied in teacher directedness for teaching color‐ and object‐name relations. Strategy 1 consisted of brief exposure to the target relations followed by an exclusively child‐led play period in which correct responses were praised. Strategy 2 was similar except that teachers prompted the children to vocalize relations and corrected errors via model prompts. Strategy 3 incorporated the same procedures as Strategy 2 except that a brief period of teacher‐initiated trials was arranged; these trials involved the use of prompt delay between questions and prompts, and correct responses resulted in tokens and back‐up activity reinforcers. Children's preferences for the different teaching strategies were also directly assessed. Strategy 3 was most effective in promoting the acquisition and generalization of the color‐ and object‐name relations and was also most preferred by the majority of children, Strategy 1 was the least effective, and Strategy 2 was typically the least preferred. Implications for the design of early educational environments based on evidence‐based values are discussed.
INCREASING SEAT BELT USE ON A COLLEGE CAMPUS: AN EVALUATION OF TWO PROMPTING PROCEDURES
Authors: Clayton Michael C. , Helms Bridgett P.
Published: September 2009

Seat belt use is an important factor in the prevention of automobile accidents involving injuries and fatalities. The current study used a multielement design to compare the “Click It or Ticket” and “Please Buckle Up—I Care” procedures. Results indicate that the Click It or Ticket prompt resulted in a 20‐percentage‐point increase in seat belt use, and Please Buckle Up—I Care resulted in a 14‐percentage‐point increase.
EFFECTS OF STIMULANT MEDICATION UNDER VARIED MOTIVATIONAL OPERATIONS
Authors: Mace F. Charles , Prager Kevin L. , Thomas Karen , Kochy Jane , Dyer Tim J. , Perry Lora , Pritchard Duncan
Published: September 2009

We evaluated the evocative effects of four conditions (high‐ and low‐preference activities, low and divided attention) and stimulant medication on the behavior of a 16‐year‐old boy with attention deficit hyperactivity disorder and moderate mental retardation. All behavior (activity engagement, activity changes, inappropriate touching, rude behaviors, and physical aggression) improved with stimulant medication in most conditions, but undesirable behaviors were not reduced to acceptable levels in all conditions. This finding suggests that stimulant medication may be a valuable adjunct to function‐based interventions.
INFLUENCING PRESCHOOLERS' FREE‐PLAY ACTIVITY PREFERENCES: AN EVALUATION OF SATIATION AND EMBEDDED REINFORCEMENT
Authors: Hanley Gregory P. , Tiger Jeffrey H. , Ingvarsson Einar T. , Cammilleri Anthony P.
Published: September 2009

The present study evaluated the effects of classwide satiation and embedded reinforcement procedures on preschoolers' activity preferences during scheduled free‐play periods. The goal of the study was to increase time allocation to originally nonpreferred, but important, activities (instructional zone, library, and science) while continuing to provide access to all free‐play activities. The satiation intervention applied to preferred activities resulted in increased time allocation to the instructional and science activities, the customized embedded reinforcement interventions resulted in increased time allocation to all three target activities, and high levels of attendance to the instructional and library activities were maintained during follow‐up observations. Implications for the design of preschool free‐play periods are discussed.
EVALUATING PROGRESS IN BEHAVIORAL PROGRAMS FOR CHILDREN WITH AUTISM SPECTRUM DISORDERS VIA CONTINUOUS AND DISCONTINUOUS MEASUREMENT
Authors: Cummings Anne R. , Carr James E.
Published: September 2009

We evaluated the influence of two different frequencies of data collection on skill acquisition and maintenance within behavioral treatment programs for children with autism spectrum disorders. Six children were taught multiple skills in up to four different behavioral programs. Half of the skills were measured continuously (i.e., trial by trial), and the other half were measured discontinuously (i.e., first trial only). When differences were detected, quicker acquisition was typically associated with discontinuous measurement, and stronger maintenance was typically associated with continuous measurement.
Assessment of Self‐Report Measures for Predicting Population Prevalence of Periodontitis
Authors: Eke Paul I. , Dye Bruce
Published: September 2009

Background: Self‐report measures have been used successfully for the surveillance of chronic diseases in adult populations. This pilot study assessed the use of self‐report oral health measures for predicting the population prevalence of periodontitis in United States adults.

Methods: Data were collected from 456 subjects participating in a 2007 study conducted by the Centers for Disease Control and Prevention. Each subject answered eight predetermined oral health self‐report questions obtained from in‐person interviews and were given a full‐mouth periodontal examination using the National Health and Nutrition Examination Survey protocol. The predictiveness of measures from these self‐report questions was assessed by multivariable logistic regression modeling measuring receiver operating characteristic (ROC) statistics, sensitivity, and specificity.

Results: Multivariable modeling incorporating self‐report measures on gum disease, loose teeth, and tooth appearance alone were most useful in predicting the prevalence of severe periodontitis and improved with the addition of demographic and risk factor variables, yielding an ROC value of 0.93, sensitivity of 54.6%, and specificity of 98% at the observed 4.8% prevalence of disease. Scaling and root planing treatments, loose teeth, and the use of mouthwash, combined with demographic and risk factor covariates, were moderately useful in predicting total periodontitis.

Conclusions: Multivariable modeling of specific self‐report oral health measures is promising for predicting the population prevalence of severe periodontitis, confirming earlier assessments from a national survey. These results justify further assessments of self‐report oral health measures for use in the surveillance of periodontitis in the adult United States population.
Relationship Between Gingival Angiopoietin‐1 Concentrations and Depth of the Adjacent Gingival Sulcus
Authors: Lester S. Reid , Bain Jennifer L. , Serio Francis G. , Harrelson Bradley D. , Johnson Roger B.
Published: September 2009

Background: The purpose of this study was to assess concentrations of angiopoietin (Ang)‐1 at various stages of gingival inflammation. Ang‐1 is an anti‐inflammatory mediator present in various inflammatory diseases. However, its presence during the pathogenesis of gingival inflammation has not been established in vivo.

Methods: Gingiva was obtained from 110 human donors before extraction of the adjacent teeth. The tissue was grouped based on adjacent probing depth and bleeding on probing (BOP). Gingiva adjacent to a ≤3‐mm sulcus without BOP was classified as “normal” (N); gingiva adjacent to a 3‐mm sulcus with BOP was classified as “diseased, slight” (DS); gingiva adjacent to a 4‐ to 6‐mm sulcus featuring BOP was classified as “diseased, moderate” (DM); and gingiva adjacent to >6‐mm sulci was classified as “diseased, severe” (DSev). Tissues were solublized, and concentrations of interleukin (IL)‐1β and −6, tumor necrosis factor (TNF)‐α, endothelin (ET)‐1, Ang‐1, vascular cell adhesion molecule (VCAM)‐1, and vascular endothelial growth factor (VEGF) were assessed by enzyme‐linked immunosorbent assay. Data were compared by factorial analysis of variance, the post hoc Tukey test, and the Pearson correlation test. Groups were defined as significantly different when P <0.05.

Results: Gingival concentrations of IL‐1β and −6, TNF‐α, VEGF, and ET‐1 were significantly greater, and VCAM‐1 and Ang‐1 were significantly lower, in DSev and DM than in N and DS tissues (P <0.05). In addition, gingival concentrations of IL‐6, VEGF, and ET‐1 were significantly greater, and VCAM‐1 and Ang‐1 were significantly lower, in DSev than in DM tissues (P <0.05). There were significant positive correlations among sulcular depth, IL‐1β and −6, TNF‐α, VEGF, and ET‐1 and negative correlations among VCAM‐1, Ang‐1, sulcular depth, and the other biomarkers (P <0.001).

Conclusions: Depleted tissue concentrations of Ang‐1 may allow gingival inflammation to become more severe because VEGF and ET‐1 secretion become less inhibited. Thus, the tissues become edematous and more likely to develop BOP.
Clinical, Microbiologic, and Biochemical Effects of Subgingival Administration of a Xanthan‐Based Chlorhexidine Gel in the Treatment of Periodontitis: A Randomized Multicenter Trial
Authors: Paolantonio Michele , D'Ercole Simonetta , Pilloni Andrea , D'Archivio Domenico , Lisanti Luca , Graziani Filippo , Femminella Beatrice , Sammartino Gilberto , Perillo Letizia , Tetè Stefano , Perfetti Giorgio , Spoto Giuseppe , Piccolomini Raffaele , Perinetti Giuseppe
Published: September 2009

Background: The use of locally delivered antibacterials containing chlorhexidine (CHX) was proposed to improve the effectiveness of non‐surgical periodontal treatment. The present multicenter randomized study investigated the effects of a xanthan‐based chlorhexidine (Xan‐CHX) gel used as an adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis.

Methods: Ninety‐eight systemically healthy subjects with moderate to advanced periodontitis were recruited in four centers (59 females and 39 males; aged 24 to 58 years). For each subject, two experimental sites located in two symmetric quadrants were chosen with probing depths (PD) ≥5 mm and positive for bleeding on probing (BOP). These two sites were randomized at the split‐mouth level with one receiving a single SRP treatment and the other receiving a single SRP + Xan‐CHX gel treatment. Supragingival plaque, modified gingival index, PD, clinical attachment level (CAL), and BOP were evaluated at baseline (prior to any treatment) and after 3 and 6 months. At the same times, subgingival microbiologic samples and gingival crevicular fluid (GCF) were collected for the analysis of total bacterial counts (TBCs), including the identification of eight putative periodontopathogens, and alkaline phosphatase (ALP) activity, respectively.

Results: The Xan‐CHX treatment group showed greater improvements compared to the SRP group for PD and CAL at 3 and 6 months (P <0.001). The differences in PD reduction between the treatments were 0.87 and 0.83 mm at 3 and 6 months, respectively (P <0.001); for CAL, these were 0.94 and 0.90 mm, respectively (P <0.001). Similar behavior was seen when the subgroup of pockets ≥7 mm was considered. The percentage of sites positive for BOP was similar between the treatments at each time point. For the comparisons between the treatment groups, no differences were seen in the TBCs and GCF ALP activity at baseline and 6 months; in contrast, slightly, but significantly, lower scores were recorded for the Xan‐CHX treatment group at 3 months (P = 0.018 and P = 0.045, respectively). Moreover, greater reductions in the percentages of sites positive for the eight putative periodontopathic bacteria were generally seen for the Xan‐CHX treatment group compared to SRP alone.

Conclusions: The adjunctive use of Xan‐CHX gel promoted greater PD reductions and CAL gains compared to SRP alone. These results were concomitant with better microbiologic and biochemical outcomes when Xan‐CHX gel use was added to SRP, particularly up to 3 months after treatment.
Cross‐Sectional Study of Vitamin D and Calcium Supplementation Effects on Chronic Periodontitis
Authors: Miley D. Douglas , Garcia M. Nathalia , Hildebolt Charles F. , Shannon William D. , Couture Rex A. , Anderson Spearie Catherine L. , Dixon Debra A. , Langenwalter Eric M. , Mueller Cheryl , Civitelli Roberto
Published: September 2009

Background:A low dietary intake of vitamin D and calcium hastens bone loss and osteoporosis. Because vitamin D metabolites may also alter the inflammatory response and have antimicrobial effects, we studied whether the use of vitamin D and calcium supplements affects periodontal disease status.

Methods:A cohort of 51 subjects receiving periodontal maintenance therapy was recruited from two dental clinics; 23 were taking vitamin D (≥400 IU/day) and calcium (≥1,000 mg/day) supplementation, and 28 were not taking such supplementation. All subjects had at least two interproximal sites with ≥3 mm clinical attachment loss. Daily calcium and vitamin D intake (from food and supplements) were estimated by nutritional analysis. The following clinical parameters of periodontal disease were recorded for the mandibular posterior teeth: gingival index, probing depth, cemento‐enamel junction–gingival margin distance (attachment loss), bleeding on probing, and furcation involvement. Posterior photostimulable‐phosphor bitewing radiographs were taken to determine cemento‐enamel junction–alveolar crest distances (alveolar crest height loss). Data were analyzed with a repeated‐measures multivariate analysis of variance.

Results:Compared to subjects who did not take vitamin D and calcium supplementation, supplement takers had shallower probing depths, fewer bleeding sites, lower gingival index values, fewer furcation involvements, less attachment loss, and less alveolar crest height loss. The repeated‐measures analysis indicated that collectively these differences were borderline significant (P= 0.08).

Conclusions:In these subjects receiving periodontal maintenance therapy, there was a trend for better periodontal health with vitamin D and calcium supplementation. More expanded longitudinal studies are required to determine the potential of this relationship.
Periodontal Conditions of Sites Treated With Gingival‐Augmentation Surgery Compared to Untreated Contralateral Homologous Sites: A 10‐ to 27‐Year Long‐Term Study
Authors: Agudio G. , Nieri M. , Rotundo R. , Franceschi D. , Cortellini P. , Pini Prato G.P.
Published: September 2009

Background: The aim of this retrospective long‐term split‐mouth study was to compare the periodontal conditions of sites treated with gingival‐augmentation procedures to untreated homologous contralateral sites over a long period of time (10 to 27 years).

Methods: Fifty‐five subjects with 73 sites (test group) lacking attached gingiva associated with recessions were treated by means of submarginal free gingival grafts (SMFGGs) and marginal free gingival grafts (MFGGs). The 73 contralateral homologous sites (control group), with or without recession and with or without attached gingiva, were not treated. Patients were recalled every 4 months during the follow‐up period (10 to 27 years). Clinical variables, including recession depth, amount of keratinized tissue (KT), and probing depth (PD), were measured in treated and untreated sites at baseline, at 1 year, and at the end of the follow‐up period.

Results: At the end of the follow‐up period, recession was reduced in all treated sites (1.5 ± 1.0 mm for SMFGG and 1.3 ± 0.9 mm for MFGG), whereas it was increased in the untreated sites (−0.7 ± 0.7 mm for SMFGG and −1.0 ± 0.5 mm for MFGG). In the treated sites, the increased KT remained quite stable during the follow‐up period. PD remained stable (1 mm) in the treated and untreated sites.

Conclusions: The sites treated with gingival‐augmentation surgery showed a tendency for coronal displacement of the gingival margin with a reduction in recession. The contralateral untreated sites showed a tendency for apical displacement of the gingival margin with an increase in the existing recessions.
Clinical and Histologic Evaluation of Non‐Surgical Periodontal Therapy With Enamel Matrix Derivative: A Report of Four Cases
Authors: Mellonig James T. , Valderrama Pilar , Gregory Holly J. , Cochran David L.
Published: September 2009

Background: Enamel matrix derivative (EMD) is a composite of proteins that was demonstrated histologically to work as an adjunct to periodontal regenerative surgical therapy. The purpose of this study was to evaluate the clinical and histologic effects of EMD as an adjunct to scaling and root planing.

Methods: Four patients with severe chronic periodontitis and scheduled to receive complete dentures were accrued. Probing depth and clinical attachment levels were obtained. Unlimited time was allowed for hand and ultrasonic instrumentation. A notch was placed in the root ≥1 to 2 mm from the apical extent of root planing. EMD was inserted into the pocket, and a periodontal dressing was placed. Patients were seen every 2 weeks for plaque control. At 6 months post‐treatment, soft tissue measurements were repeated, and the teeth were removed en bloc and prepared for histomorphologic analysis.

Results: Probing depth reduction and clinical attachment level gain were obtained in three‐fourths of the specimens. Three of the four specimens analyzed histologically demonstrated new cementum, bone, periodontal ligament, and connective tissue attachment coronal to the notch. In one specimen, the gingival margin had receded below the notch.

Conclusions: The results were unexpected and may represent an aberration. However, the substantial reduction in deep probing depths and clinical attachment level gain in three of four specimens, in addition to the histologic findings of new cementum, new bone, a new periodontal ligament, and a new connective tissue attachment, suggest that EMD may be useful as an adjunct to scaling and root planing in single‐rooted teeth.
Comparisons of Subgingival Microbial Profiles of Refractory Periodontitis, Severe Periodontitis, and Periodontal Health Using the Human Oral Microbe Identification Microarray
Authors: Colombo Ana Paula V. , Boches Susan K. , Cotton Sean L. , Goodson J. Max , Kent Ralph , Haffajee Anne D. , Socransky Sigmund S. , Hasturk Hatice , Van Dyke Thomas E. , Dewhirst Floyd , Paster Bruce J.
Published: September 2009

Background: This study compared the subgingival microbiota of subjects with refractory periodontitis (RP) to those in subjects with treatable periodontitis (GRs = good responders) or periodontal health (PH) using the Human Oral Microbe Identification Microarray (HOMIM).

Methods: At baseline, subgingival plaque samples were taken from 47 subjects with periodontitis and 20 individuals with PH and analyzed for the presence of 300 species by HOMIM. The subjects with periodontitis were classified as having RP (n = 17) based on mean attachment loss (AL) and/or more than three sites with AL ≥2.5 mm after scaling and root planing, surgery, and systemically administered amoxicillin and metronidazole or as GRs (n = 30) based on mean attachment gain and no sites with AL ≥2.5 mm after treatment. Significant differences in taxa among the groups were sought using the Kruskal‐Wallis and χ2 tests.

Results: More species were detected in patients with disease (GR or RP) than in those without disease (PH). Subjects with RP were distinguished from GRs or those with PH by a significantly higher frequency of putative periodontal pathogens, such as Parvimonas micra (previously Peptostreptococcus micros or Micromonas micros), Campylobacter gracilis, Eubacterium nodatum, Selenomonas noxia, Tannerella forsythia (previously T. forsythensis), Porphyromonas gingivalis, Prevotella spp., Treponema spp., and Eikenella corrodens, as well as unusual species (Pseudoramibacter alactolyticus, TM7 spp. oral taxon [OT] 346/356, Bacteroidetes sp. OT 272/274, Solobacterium moorei, Desulfobulbus sp. OT 041, Brevundimonas diminuta, Sphaerocytophaga sp. OT 337, Shuttleworthia satelles, Filifactor alocis, Dialister invisus/pneumosintes, Granulicatella adiacens, Mogibacterium timidum, Veillonella atypica, Mycoplasma salivarium, Synergistes sp. cluster II, and Acidaminococcaceae [G‐1] sp. OT 132/150/155/148/135) (P <0.05). Species that were more prevalent in subjects with PH than in patients with periodontitis included Actinomyces sp. OT 170, Actinomyces spp. cluster I, Capnocytophaga sputigena, Cardiobacterium hominis, Haemophilus parainfluenzae, Lautropia mirabilis, Propionibacterium propionicum, Rothia dentocariosa/mucilaginosa, and Streptococcus sanguinis (P <0.05).

Conclusion: As determined by HOMIM, patients with RP presented a distinct microbial profile compared to patients in the GR and PH groups.
Maternal Periodontal Disease and Soluble Fms‐Like Tyrosine Kinase‐1 Expression
Authors: Horton Amanda L. , Boggess Kim A. , Moss Kevin L. , Beck James , Offenbacher Steven
Published: September 2009

Background: This study was conducted to examine the relationship between maternal periodontal disease and plasma angiogenic factor expression of soluble fms‐like tyrosine kinase (sFlt)‐1.

Methods: This was a nested case‐control study of 220 women, including 45 healthy women with evidence of active periodontal disease, 98 women without evidence of active periodontal disease, 13 women with fetal exposure to oral pathogens, and 64 women without fetal exposure to oral pathogens. Active periodontal disease was defined as the presence of moderate/severe periodontal disease and evidence of periodontal disease progression. Fetal exposure to oral pathogens was determined by fetal immunoglobulin M (IgM) umbilical cord seropositivity. Maternal plasma was collected at <26 weeks of gestation; umbilical cord blood was collected at delivery. sFlt‐1 was measured with an immunoradiometric assay. Demographic and medical data were chart abstracted. Maternal variables and sFlt‐1 concentrations were compared between cases and controls using the Student t and χ2 tests and analysis of variance.

Results: The median sFlt‐1 concentration at the time of enrollment for all women was 2,374 pg/ml (interquartile range [IQR]: 1,504 to 3,194 pg/ml). Women with evidence of fetal exposure to oral pathogens had significantly higher sFlt‐1 concentrations compared to IgM‐negative fetuses (3,383 pg/ml [IQR: 2,610 to 4,244 pg/ml] versus 2,123 pg/ml [IQR: 1,456 to 3,011 pg/ml]; P = 0.03).

Conclusion: Fetal exposure to oral pathogens was associated with increased plasma concentrations of sFlt‐1 early in pregnancy.
Organic and Mineral Input Management to Enhance Crop Productivity in Central Kenya
Authors: Chivenge P. , Vanlauwe B. , Gentile R. , Wangechi H. , Mugendi D. , van Kessel C. , Six J.
Published: September 2009

Organic resources (ORs) are important nutrient inputs in tropical agriculture. Combined with mineral fertilizers, they form the backbone of integrated soil fertility management. This study was conducted to determine the medium‐ to long‐term influence of OR quality and quantity on maize productivity and to evaluate the occurrence of additive benefits in terms of extra grain yield produced by the combined application of ORs and N fertilizers. Farmyard manure, high quality Mexican sunflower [Tithonia diversifolia (Hemsl.) A. Gray], intermediate quality calliandra (Calliandra calothyrsus Meisn.) and maize (Zea mays L.), and low quality silky‐oak (Grevillea robusta A. Cunn. ex R. Br.) sawdust were incorporated into the soil at equivalent rates of 1.2 and 4 Mg C ha−1 yr−1 in Embu (clayey) and Machanga (sandy soil), together with a control to which no OR was added. All plots were split, with one half receiving 120 kg N ha−1 season−1 as CaNH4NO3. The ORs, except sawdust and maize, improved maize grain yields compared with the control at both sites. Greatest mean maize yields (i.e., 4.9 and 2.3 Mg ha−1 season−1, in Embu and Machanga, respectively) over 10 seasons were observed with the high rate of Mexican sunflower, but was not significantly different from calliandra and manure. Generally, maize yields were greater with higher than lower OR rates, except for maize and sawdust. Although N fertilizer additions to the ORs improved grain yields in Embu, the increase was marginal; resulting in negative interactive effects of applying ORs with N fertilizers, especially with high‐N ORs. Thus high‐N ORs should not be applied in combination with N fertilizers, especially at such high fertilizer N rates.
Estimating Genetic Coefficients for the CSM‐CERES‐Maize Model in North Carolina Environments
Authors: Yang Zhengyu , Wilkerson Gail G. , Buol Gregory S. , Bowman Daryl T. , Heiniger Ronnie W.
Published: September 2009

CSM‐CERES‐Maize has been extensively used worldwide to simulate corn growth and grain production, but has not been evaluated for use in North Carolina. The objectives of this study were to calibrate CSM‐CERES‐Maize soil parameters and genetic coefficients using official variety trial data, evaluate model performance in North Carolina, and determine the suitability of the fitting technique using variety trial data for model calibration. The study used yield data for 53 maize genotypes collected from multiple locations over a 10‐yr period. A stepwise calibration procedure was utilized: (i) two genetic coefficients which determine anthesis and physiological maturity dates were adjusted based on growing degree day requirements for each hybrid; and (ii) plant available soil water and rooting profile were adjusted iteratively with two other genetic coefficients affecting yield. Cross validation was used to evaluate the suitability of this approach for estimating soil and genetic coefficients. The root mean squared errors of prediction (RMSEPs) were similar to fitting errors. Results indicate that CSM‐CERES‐Maize can be used in North Carolina to simulate corn growth under nonlimiting N conditions and variety trial data can be used for estimating genetic coefficients. Hybrid average simulated yields matched measured yields well across a wide range of environments, and simulated hybrid yield rankings were in close agreement with rankings based on measured yields. Data from several site‐years could not be used in fitting genetic coefficients due to large root mean squared errors. In some cases, this could be attributed to a weather event, such as a late‐season hurricane.