bluuebunny/crossref_metadata_2025 huggingface dataset:
Stream restoration strategies for reducing river nitrogen loads
Authors: Craig Laura S , Palmer Margaret A , Richardson David C , Filoso Solange , Bernhardt Emily S , Bledsoe Brian P , Doyle Martin W , Groffman Peter M , Hassett Brooke A , Kaushal Sujay S , Mayer Paul M , Smith Sean M , Wilcock Peter R
Published: January 2008

Despite decades of work on implementing best management practices to reduce the movement of excess nitrogen (N) to aquatic ecosystems, the amount of N in streams and rivers remains high in many watersheds. Stream restoration has become increasingly popular, yet efforts to quantify N‐removal benefits are only just beginning. Natural resource managers are asking scientists to provide advice for reducing the downstream flux of N. Here, we propose a framework for prioritizing restoration sites that involves identifying where potential N loads are large due to sizeable sources and efficient delivery to streams, and when the majority of N is exported. Small streams (1st–3rd order) with considerable loads delivered during low to moderate flows offer the greatest opportunities for N removal. We suggest approaches that increase in‐stream carbon availability, contact between the water and benthos, and connections between streams and adjacent terrestrial environments. Because of uncertainties concerning the magnitude of N reduction possible, potential approaches should be tested in various landscape contexts; until more is known, stream restoration alone is not appropriate for compensatory mitigation and should be seen as complementary to land‐based best management practices.
A Literature Analysis of the WAG Injectivity Abnormalities in the CO2 Process
Authors: Rogers John D. , Grigg Reid B.
Published: January 2008

As a result of research in the 1950s and 1960s, carbon dioxide (CO2) flooding has been implemented at the pilot and project stage in the petroleum industry since the early 1970s. A plethora of articles have been produced on the problems and successes of using CO2 as an enhanced oil recovery process. A number of the operational problems regarding full-scale implementation have been settled to some degree. The WAG (water alternating with gas) technique to improve mobility efficiency of the higher mobile CO2 gas over the lower mobile reservoir fluids was an evolutionary step in the technical and economic implementation of CO2 as a tertiary recovery process. This combination of two improved oil recovery processes (waterflooding and gas injection) resulted in a problem that has perplexed the industry since implementing the pilot studies in the early 1970s. A recent survey conducted by New Mexico Petroleum Recovery Research Center (NMPRRC) on CO2 flooding indicated that injectivity abnormalities during WAG cycles has been a crucial limiting factor in many projects. Additionally the WAG process has been expanded to include most gas injection processes of enhancing hydrocarbon recovery - immiscible and miscible processes.

Based on the fluid flow properties of CO2 and other IOR gases, one would intuitively expect that gas injectivity would be greater than the waterflood brine injectivity. However, in practice this behavior is not always observed. In addition, water injectivity may be higher or lower than the waterflood brine injectivity. What is more perplexing is that some reservoirs may lose injectivity and others may increase injectivity after the first slug of gas (CO2) is injected. In addition, this phenomenon may occur on a local scale. Injection wells in the same field and reservoir may have significantly different behavior. A number of researchers have studied and proposed reasons for this phenomenon over the past 20 years.

This paper summarizes the hypothesis and theories as to the causes and expectations of injectivity behavior in various CO2 and gas flooded reservoirs. The intent of the paper is to:

Provide a concise compendium to the current understanding of the WAG mechanism and predictability, Provide a comprehensive single source review of the causes and conditions of injectivity abnormalities in CO2/gas flood EOR projects, Aid in formulating the direction of research, and Help operators develop operational and design strategies for current and future projects as well as input parameters for simulating current and future projects.
Using Wellhead Sampling Data to Predict Reservoir Saturation Pressure
Authors: Yi Xiangyi
Published: January 2008

The PVT properties of reservoir fluids, which include saturation pressure, gas oil ratio, volume factor, viscosity, and compressibility, are keyparameters to a series of calculations such as reserve and production, in whichsaturation pressure is more important in oil field development. The main methodto determine the saturation pressure is from bottomhole sampling data.

This paper attempts to develop a method to predict the saturation pressurebased on the information from wellhead sampling. The method presented in thispaper is first to exploit the combination relation of the fluid specificgravity and gas-oil ratio, then calculate saturation pressure and plot therelationship curve. The accuracy of the saturation pressure predicted by themethod has been found very good.

The method introduced in the paper can solve some problems that saturationpressure can not be determined because samples are not available, it reducesthe possibility of production reduction because of sampling. It can reduce theamounts of samples from deep wells, which can lower costs.

Introduction

The PVT properties of reservoir fluids, which include saturation pressure, gasoil ratio, volume factor, viscosity, and compressibility, are key parameters toa series of calculations such as reserve and production, in which saturationpressure is more important in oil field development.

In oil field development, saturation pressure is a very important parameter.Typically, it is determined by subsurface sampling in laboratory. Though thismethod is direct and reliable, the drawbacks are also obvious:The sampled wells must be uniform distributed on a plane;Using a small choke controls production for a certain period of time toreach stabilization;Bad conditions or unacceptable samples alter the working system thatinfluences the normal production at some of sampled wells.

All of those will affect the normal production. For example, there are thirtysubsurface oil samples ever year in Kelamay Oil Filed in China, which requiresmore than fifty sampled wells. If the production is forty tons per well, whosechoke is 4 mm (the sampled wells are usually high-yield wells in reservoir).Sampling requires changing the choke size from 4 mm to 1.5 mm, therefore, theproduction will reduce 50%. Typically, one week is the shortest period ofcontrolling producing, then there are nearly 2,000 tons as production reductionfrom the fifty wells. Therefore, a number of petroleum engineers look for anindirect method that can get saturation pressure by exploiting plenty of datafrom laboratory. The many methods are recently introduced in literature1–3.However, those methods are good to some specific oil reservoirs, and they cannot ideally validated by case histories. Therefore, it is necessary to use theactual cases in Kelamay oil field to study this field.
New Concept in Well Testing: The Compact Cyclone Multiphase System
Authors: Scott Bentley N. , Kvamsdal Dag
Published: January 2008

A compact cyclone multiphase meter (CCM meter) developed by Statoil and Kværner Process Systems utilizes a compact gas liquid cyclone to separate liquid and gas, before individual measurement of the two phases by conventional single phase instruments, followed by re-mixing downstream of the measurement section. The most unique feature of this cyclone is the simple control scheme which provides for large turn down ratios. The instrumentation has been implemented into the water cut analyzer electronics to provide for a complete stand alone system. Field test data will be presented along with its impact on reservoir management.
Integration of Conventional Fracturing, Coiled Tubing, and Retrievable Tool Technology
Authors: McConkey Stuart , Stromquist Marty
Published: January 2008

This paper presents a new method for accessing thin, gas-bearing sands in previously completed shallow wells in western Canada. Of the thousands of shallow gas wells completed in this large field, many contain gas zones that were never completed. Many of these zones were believed to be uneconomical or too thin to be completed with conventional limited-entry fracturing technology. As gas prices have increased, these previously bypassed gas zones have become more attractive to operators in the area. Now, an improved recompletion technique integrates conventional fracturing, coiled tubing, and retrievable downhole tool technology to access the previously bypassed gas zones.
Selective Chemical Water Shutoffs Utilizing Through-Tubing Inflatable Packer Technology
Authors: Plante Mark E. , Mackenzie Gordon R. J.
Published: January 2008

This paper will outline the history, and operation of a Through-Tubing selective injection tool used for the purpose of water shutoffs. This tool is an inflatable, re-settable, coiled tubing-conveyed straddle packer assembly designed to run through production tubing and isolate a portion of perforated, screened, slotted, or open hole allowing precise placement of water blocking chemicals, Acidizing, or chemical fluids.

The paper will include a description of 18 field runs of this tool used for water blocking chemicals from 1995 through October 1999 and will examine the 3 case histories listed below in more detail: Through-Tubing selective water shut-off polymer job through casing perforations with a single packerThrough-Tubing selective water shut-off polymer job of an intermediate zone in 4.5" casingThrough-Tubing selective water shut-off polymer job of an intermediate zone in 3.5" screen liner
How To Approximate Effects of Geomechanics in Conventional Reservoir Simulation
Authors: Settari A. T. , Bachman R. C. , Walters D. A.
Published: January 2008

Geomechanics is often represented in conventional reservoir simulators by pressure dependent treatment of porosity and/or permeability. The paper gives a systematic treatment of the subject and shows different methods for pressure-dependent approximations.

Although there is no single method that would provide the best approximation under all circumstances, reasonable approximations exist in several situations. For porosity coupling, the primary factor is the type of deformation. Accurate approximations are given for the cases of uniform depletion with different deformation assumptions. For permeability coupling, new methods have been developed and tested against coupled simulations.

The results show clearly that large errors can result from simple approaches, in estimating both reservoir pressure decline and well productivity/injectivity.
Predictors of Non-carious Loss of Cervical Tooth Tissues
Authors: Chan D. C. N. , Browning W. D. , Pohjola R. , Hackman S. , Myers M. L.
Published: January 2008

Clinical Relevance

In this sample of subjects, age, premolars and the presence of corrosive factors were found to be significantly associated with NLCTT. The long-term success of treating such a lesion is dependent on properly identifying and eliminating the etiologic factors.
Polymerization Efficiency of Different Photocuring Units Through Ceramic Discs
Authors: Jung H. , Friedl K. H. , Hiller K. A. , Furch H. , Bernhart S. , Schmalz G.
Published: January 2008

Clinical Relevance

The ability of modern light curing units to photocure luting resin through ceramic restorations is dependent on the type of light source, ceramic thickness and use of a self-curing catalyst.
SEM Evaluation of a Non-rinse Conditioner and a Self-etching Adhesive Regarding Enamel Penetration
Authors: Miranda M. S. , Cal Neto J. O. A. P. , Barceleiro M. O. , Dias K. R. H. C.
Published: January 2008

Clinical Relevance

Although the use of self-etching systems has resulted in regular etch patterns, they have provided less demineralization, preserving enamel surfaces.
Influence of Curing Methods and Matrix Type on the Marginal Seal of Class II Resin-based Composite Restorations In Vitro
Authors: Hofmann N. , Hunecke A.
Published: January 2008

Clinical Relevance

Selection of photo-curing protocol (high intensity vs soft-start) and matrix type (transparent vs metal) did not influence the margin quality and marginal seal of Class II resin-based composite restorations.
Immediate Bonding to Bleached Enamel
Authors: El-din A. K. Nour , Miller B. H. , Griggs J. A. , Wakefield C.
Published: January 2008

Clinical Relevance

When immediate bonding to bleached enamel is to be implemented, organic-solvent based adhesives are not capable of eliminating or reducing the adverse effect of bleaching systems on bond strength.
Repair Strength of Dental Amalgams
Authors: Shen C. , Speigel J. , Mjör I. A.
Published: January 2008

Clinical Relevance

The proper technique of condensing amalgam to the surface of an old amalgam is critical to establishing a bond between the new and old amalgams.
Pulse-delay Curing: Influence of Initial Irradiance and Delay Time on Shrinkage Stress and Microhardness of Restorative Composites
Authors: Pfeifer C. S. C. , Braga R. R. , Ferracane J. L.
Published: January 2008

Clinical Relevance

New photoactivation protocols need to be tested before being recommended for clinical use. This study suggests that pulse-delay curing may be an efficient way to reduce polymerization shrinkage stress without compromising degree of conversion or polymer network structure.
Bond Strengths of a 1-Step Self-etching System to Caries-affected and Normal Dentin
Authors: Pereira P. N. R. , Nunes M. F. , Miguez P. A. , Swift E. J.
Published: January 2008

Clinical Relevance

The 1-step self-etching adhesive had significantly higher mean bond strength to normal dentin than to caries-affected dentin. Although Single Bond had a similar tendency, bonds to normal dentin and caries-affected dentin were not significantly different.
Load Capability of Excessively Flared Teeth Restored with Fiber-reinforced Composite Posts and All-ceramic Crowns
Authors: Naumann M. , Preuss A. , Frankenberger R.
Published: January 2008

Clinical Relevance

The fracture resistance of excessively flared endodontically-treated teeth (ETT) without ferrule preparation is not acceptable. Adhesively luted FRC posts with 2 mm ferrule are recommended.
Creep as a Mechanism for Sealing Amalgams
Authors: Osborne J. W.
Published: January 2008

Clinical Relevance

Creep may be a major factor in amalgam sealing from microleakage. Creep expansion causes amalgam to fill in the tooth/amalgam interface gap and causes the restoration to extrude out of the preparation.
Core Buildup Repair Using a Clear Matrix: A Case Report and Clinical Technique
Authors: Ajlouni R. , Ajlouni K. , Denehy G. E.
Published: January 2008

Clinical Relevance

In some cases, cores fractured between the impression and delivery stage may be predictably restored to original contour, allowing for delivery of the crown.
Comparison of Temperature Changes in the Pulp Chamber Induced by Various Light Curing Units, In Vitro
Authors: Yazici A. R. , Müftü A. , Kugel G. , Perry R. D.
Published: January 2008

Clinical Relevance

The thickness of the residual dentin is a critical factor in the reducing thermal transfer to pulp, and this transfer varies with the curing unit used.
Step-cure Polymerization: Effect of Initial Light Intensity on Resin/Dentin Bond Strength in Class I Cavities
Authors: Santos A. J. S. , Sarmento C. F. , Abuabara A. , Aguiar F. H. B. , Lovadino J. R.
Published: January 2008

Clinical Relevance

Step-cure polymerization using a combination of low initial light intensity (10 seconds at 200–250 mW/cm2) followed by final high intensity irradiation provides an increase in resin/dentin bond strength in box-shaped cavities.
Effect of Rotary Instrumentation on Composite Bond Strength with Simulated Pulpal Pressure
Authors: Gupta R. , Tewari S.
Published: January 2008

Clinical Relevance

The bur and its speed may be a factor for improved bonding.
Quantitative Comparison of the Water Permeable Zone Among Four Types of Dental Adhesives Used with a Dual-cured Composite
Authors: Chang J. , Platt J. A. , Yi K. , Cochran M. A.
Published: January 2008

Clinical Relevance

When placing a dual-cured composite, variation in the permeability of adhesive interfaces may affect bonding quality and longevity.
Correlation Between the Amount of Linear Polymerization Shrinkage and Cuspal Deflection
Authors: Lee S-Y. , Park S-H.
Published: January 2008

Clinical Relevance

When restoring teeth with Class II cavities, the amount of polymerization shrinkage value of composites determines the amount of cuspal deflection of teeth. Thus, resin composites with low polymerization shrinkage should be used to reduce cuspal deflection.
Microleakage in Conventional and Bonded Amalgam Restorations: Influence of Cavity Volume
Authors: Silva A. F. , Piva E. , Demarco F. F. , Sobrinho L. Correr , Osinaga P. W. R.
Published: January 2008

Clinical Relevance

The volume of cavity preparations showed no influence on amalgam restoration microleakage. In most situations, bonded amalgam performed similarly to conventional amalgam restorations. It was also found that microleakage was higher in margins located in cementum-dentin.
Effect of Water Storage on the Bonding Effectiveness of 6 Adhesives to Class I Cavity Dentin
Authors: De Munck J. , Shirai K. , Yoshida Y. , Inoue S. , Van Landuyt K. L. , Lambrechts P. , Suzuki K. , Shintani H. , Van Meerbeek B.
Published: January 2008

Clinical Relevance

Recently developed “user-friendly” adhesives do not perform as well as traditional 3-step etch-and-rinse adhesives in the long term.
Individualized Wedge
Authors: González-López S. , Bolaños-Carmona M. V. , Navajas-Rodríguez de Mondelo J. M.
Published: January 2008

Clinical Relevance

The use of an individualized wedge with resin allows proximal contours to be reproduced and an adequate contact point to be obtained in Class II composite esthetic restorations.
Randomized Clinical Trial on the Efficacy of a New Bleaching Lacquer for Self-application
Authors: Zantner C. , Derdilopoulou F. , Martus P. , Kielbassa A. M.
Published: January 2008

Background: This study evaluated the clinical efficacy and duration of effectiveness of a new bleaching lacquer for self-application without the use of mouth guards. It compared two different application times. Methods: Forty-six adult subjects who requested bleaching treatment were selected to participate in this randomized, single-blind (examiner-blinded), single center, two-group trial. The subjects were randomly divided into two groups (n=23 each), each being instructed to bleach (8% carbamide peroxide) their six maxillary anterior teeth for two weeks. Daily contact time in Group 1 was 20 minutes once a day and, in Group 2, the time was 20 minutes twice a day. Efficacy was measured subjectively using the Chromascop Complete shade scores obtained at baseline and after one, two and three weeks, as well as after one, three, six and nine months. Results: After two weeks of treatment, the teeth in the Group 1 subjects exhibited a 2.4 ± 0.2 mean shade scores improvement compared to baseline (p<0.001; t-test for paired samples), and the subjects' teeth in Group 2 exhibited a 3.5 ± 0.1 mean shade scores improvement (p<0.001). However, the difference between both groups was not statistically significant (p>0.05). The observed effects were stable for six months.

Conclusions: It can be concluded that the new bleaching lacquer is efficacious; however, a double application does not seem to be obligatory.
Performance of a Conventional Sealant and a Flowable Composite on Minimally Invasive Prepared Fissures
Authors: Francescut P. , Lussi A.
Published: January 2008

Clinical Relevance

Preparation prior to fissure sealing did not enhance the performance of the sealant. However, if caries is suspected and an enameloplasty has to be performed, opening the fissure with a diamond bur and sealing it with a conventional sealer is recommended.
Surface Geometry of Four Nanofiller and One Hybrid Composite After One-step and Multiple-step Polishing
Authors: Jung M. , Eichelberger K. , Klimek J.
Published: January 2008

Clinical Relevance

Two of the four nanocomposites were significantly smoother, while the remaining two had a surface quality similar to that of a hybrid composite. In all cases, a three-step polishing system was more efficient than a two-step or one-step procedure on all composites.
Restoration of Erosion Associated with Gastroesophageal Reflux Caused by Anorexia Nervosa Using Ceramic Laminate Veneers: A Case Report
Authors: Hayashi M. , Shimizu K. , Takeshige F. , Ebisu S.
Published: January 2008

Clinical Relevance

Ceramic laminate veneers are useful to restore incisors suffering from severe erosion.
In Vitro Inhibition of Bacterial Growth Using Different Dental Adhesive Systems
Authors: Walter R. , Duarte W. R. , Pereira P. N. R. , Heymann H. O. , Swift E. J. , Arnold R. R.
Published: January 2008

Clinical Relevance

All materials tested, especially iBond, have a potential long-term antibacterial effect against the oral bacteria tested.
Effect of Carbamide Peroxide Treatments on the Metal-ion Release and Microstructure of Different Dental Amalgams
Authors: Gurgan S. , Kiremitci A. , Yalcin F. , Alpaslan T. , Yazici E.
Published: January 2008

Clinical Relevance

Carbamide peroxide bleaching releases metal-ions from dental amalgam.
Clinical Evaluation of 15% Carbamide Peroxide on the Surface Microhardness and Shear Bond Strength of Human Enamel
Authors: Metz M. J. , Cochran M. A. , Matis B. A. , Gonzalez C. , Platt J. A. , Lund M. R.
Published: January 2008

Clinical Relevance

The clinical use of whitening chemicals should provide patients with some degree of certainty that there are no detrimental effects over time. Loss of surface hardness and polymerization inhibition are areas of concern in the literature and need clinical validation for both the practitioner and patient.
Factors Associated with Microleakage in Class II Resin Composite Restorations
Authors: Idriss S. , Abduljabbar T. , Habib C. , Omar R.
Published: January 2008

Clinical Relevance

Even though marginal gap size was not shown to be a direct predictor for the extent of microleakage in resin composite restorations, both material and placement technique appear to be important determinants in microleakage and, thus, probably in clinical outcomes.
Effects of New Formulas of Bleaching Gel and Fluoride Application on Enamel Microhardness: An In Vitro Study
Authors: Costa J. Bda , Mazur R. F.
Published: January 2008

Clinical Relevance

The results of this study suggest that tooth bleaching may lead to a reduction in enamel micro-hardness. Nonetheless, the application of a high concentration fluoride post-bleaching treatment may increase enamel microhardness and may restore enamel hardness to a level similar to non-bleached enamel, if the bleaching formula contains fluoride, potassium or ACP.
Effects of Filling Techniques on the Regional Bond Strength to Lateral Walls in Class I Cavities
Authors: Félix S. A. , González-López S. , Mauricio P. D. , Aguilar-Mendoza J. A. , Bolaños-Carmona M. V.
Published: January 2008

Clinical Relevance

Using either total-etch or self-etch adhesives, the incremental technique is the optimal method to insert resin-based composites in large Class I cavities.
Clinical Effectiveness of Two Microabrasion Materials for the Removal of Enamel Fluorosis Stains
Authors: Loguercio A. D. , Correia L. D. , Zago C. , Tagliari D. , Neumann E. , Gomes O. M. M. , Barbieri D. B. , Reis A.
Published: January 2008

Clinical Relevance

PREMA and Opalustre are effective, conservative methods for improving the appearance of fluorosis-affected teeth; however, faster results can be obtained with Opalustre. The results of this study show that the majority of subjects reported being satisfied after microabrasion treatment.
Influence of Thermal Cycling on Dentin Bond Strengths of Single-step Self-etch Adhesive Systems
Authors: Asaka Y. , Amano S. , Rikuta A. , Kurokawa H. , Miyazaki M. , Platt J. A. , Moore B. K.
Published: January 2008

Clinical Relevance

Some of the bonding systems used in this study have achieved unchanged dentin bond strengths after thermal cycling. Therefore, by choosing appropriate adhesive systems, the simplified clinical procedures offered by single-step self-etch systems can be exploited even after thermal cycle stress.
Composite Depth of Cure Obtained with QTH and LED Units Assessed by Microhardness and Micro-Raman Spectroscopy
Authors: Santos G. B. , Medeiros I. S. , Fellows C. E. , Muench A. , Braga R. R.
Published: January 2008

Clinical Relevance

Lower depth of cure with the LED unit, compared to the QTH unit, is associated with different light scattering due to differences in spectral emission.
Shear Bond Strength of Two Resin Cements to Human Root Dentin Using Three Dentin Bonding Agents
Authors: Gogos C. , Stavrianos C. , Kolokouris I. , Economides N. , Papadoyannis I.
Published: January 2008

Clinical Relevance

The application of 15% EDTA solution was shown to be an alternative to the commonly used 37% phosphoric acid in the bonding procedures of resin cements. The self-etching adhesive tested was found to improve bond strength more than one-bottle adhesives.
The Effect of Energy Application Sequence on the Microtensile Bond Strength of Different C-factor Cavity Preparations
Authors: Maghaireh G. , Bouschlicher M. R. , Qian F. , Armstrong S. R.
Published: January 2008

Clinical Relevance

Light curing of resin composites in high C-factor cavity preparations using a high irradiance energy application sequence may lead to decreased bond strength. However, the high irradiance energy application sequence did not result in lower bond strengths in lower C-factor cavity preparations.
Influence of Curing Rate of Resin Composite on the Bond Strength to Dentin
Authors: Benetti A. R. , Asmussen E. , Peutzfeldt A.
Published: January 2008

Clinical Relevance

When deciding on a specific curing protocol, dental professionals should be aware of the advantages and limitations of each curing mode.
Effect of Curing Mode on Microtensile Bond Strength to Dentin of Two Dual-cured Adhesive Systems in Combination with Resin Luting Cements for Indirect Restorations
Authors: Arrais C. A. G. , Giannini M. , Rueggeberg F. A. , Pashley D. H.
Published: January 2008

Clinical Relevance

The separate step of light curing the adhesive resin component of some fourth and fifth generation dual-cured adhesive systems may be eliminated prior to cementation of an indirect resin composite restoration without deterioration in microtensile bond strength.
10-year Clinical Evaluation of a Self-etching Adhesive System
Authors: Akimoto N. , Takamizu M. , Momoi Y.
Published: January 2008

Clinical Relevance

This 10-year clinical evaluation of a self-etching adhesive system showed only slight marginal change of some restorations; however, these changes were not severe. Consequently, these clinical conditions did not require replacement, since no recurrent caries were present. Clinically, these data demonstrate that this self-etching adhesive system is acceptable for placement of a long-term adhesive restoration in human teeth.
Bond Strength of Different Adhesive Systems to Dental Hard Tissues
Authors: Yazici A. R. , Çelik Ç , Özgünaltay G. , Dayangaç B.
Published: January 2008

Clinical Relevance

Bond strength to dental hard tissues was dependent upon the type of adhesive system used and varied with respect to tooth regions.
Bond Strengths of All-Ceramics: Acid vs Laser Etching
Authors: Gökçe B. , Özpinar B. , Dündar M. , Çömlekoglu E. , Sen B. H. , Güngör M. A.
Published: January 2008

Clinical Relevance

For surface modification of the inner surfaces of ceramic restorations, the etching pattern obtained by dental lasers could be an alternative to conventional acid etching.
Postoperative Sensitivity: A Comparison of Two Bonding Agents
Authors: Browning W. D. , Blalock J. S. , Callan R. S. , Brackett W. W. , Schull G. F. , Davenport M. B. , Brackett M. G.
Published: January 2008

Clinical Relevance

Postoperative sensitivity to cold is a common problem that negatively impacts the patient's dental experience. For this group of participants and over this relatively short period, bonded composite restorations placed in a manner and timeframe consistent with those generally used in private-practice were seen to be less sensitive to cold than they were preoperatively.
Clinical Performance and Wear Resistance of Two Compomers in Posterior Occlusal Restorations of Permanent Teeth: Six-Year Follow-up
Authors: Lund R. G. , Sehn F. P. , Piva E. , Detoni D. , Moura F. R. R. , Cardoso P. E. C. , Demarco F. F.
Published: January 2008

Clinical Relevance

The restoration quality has decreased and the wear increased for two compomers placed in the occlusal surface of permanent posterior teeth after six years; however, the restorations were clinically acceptable at the end of the evaluation.
Visualization of Marginal Integrity of Resin-Enamel Interface by Holographic Interferometry
Authors: Panduric V. , Demoli N. , Tarle Z. , Šariri K. , Mandic V. N. , Knezevic A. , Šutalo J.
Published: January 2008

Clinical Relevance

Holographic interferometry offers precise insight into both the frequency and location of cohesive fractures through its fringe information. If flowable composites are not used as a first layer, fringe distribution indicates cohesive fractures as a consequence of composite polymerization.
Surface Texture of Four Nanofilled and One Hybrid Composite After Finishing
Authors: Jung M. , Sehr K. , Klimek J.
Published: January 2008

Clinical Relevance

Compared to a hybrid composite, with one exception, nanocomposites were significantly smoother after finishing with rigid rotary instruments and after using Sof-Lex discs. Using a 30 μm diamond caused detrimental surface alteration on nanofiller and hybrid composites.
A Study of Microleakage in Class II Composite Restorations Using Four Different Curing Techniques
Authors: Gharizadeh N. , Moradi K. , Haghighizadeh M. H.
Published: January 2008

Clinical Relevance

For bonded direct Class II restorations, the use of transparent matrices or metal matrices combined with light conducting instruments, such as light tips, should be favored because marginal leakage is significantly lower when compared to using metal matrices alone.
The Influence of One-step Polishing Systems on the Surface Roughness and Microhardness of Nanocomposites
Authors: Korkmaz Y. , Ozel E. , Attar N. , Aksoy G.
Published: January 2008

Clinical Relevance

One-step polishing systems exhibited similar or better surface roughness values when compared to multi-step polishing systems. In all groups, mylar-strip created surfaces showed lower microhardness values than polished surfaces. Different polishing procedures did not effect the microhardness of nanocomposites. One-step polishing systems may be a good choice for polishing nanocomposites, resulting in reduced chair time.
The Effect of Curing Units and Staining Solutions on the Color Stability of Resin Composites
Authors: Yazici A. R. , Çelik Ç , Dayangaç B. , Özgünaltay G.
Published: January 2008

Clinical Relevance

The color stability of resin composites did not vary based on the type of light curing unit. The effect of staining solutions on color changes in resin composites was resin composite and immersion time-dependent.
Adhesion to Er:YAG Laser-prepared Dentin After Long-term Water Storage and Thermocycling
Authors: Amaral F. L. B. , Colucci V. , Souza-Gabriel A. E. , Chinelatti M. A. , Palma-Dibb R. G. , Corona S. A. M.
Published: January 2008

Clinical Relevance

Simulation of thermal stress and long-term degradation presented in the oral environment adversely affected the adhesion of an etch & rinse adhesive system to Er:YAG laser-irradiated dentin.
Effect of Pre-heating Resin Composite on Restoration Microleakage
Authors: Wagner W. C. , Aksu M. N. , Neme A. L. , Linger J. B. , Pink F. E. , Walker S.
Published: January 2008

Clinical Relevance

The results of this study indicate that preheating composites can improve adaptation of resin composites to tooth structure. This technique significantly reduced microleakage. However, delaying light curing of the preheated composite after placement appears to be counterproductive and diminishes the positive effects from the preheating treatment. Flowable liner was less effective than preheating the composite in reducing microleakage.
Microleakage in Overflared Root Canals Restored with Different Fiber Reinforced Dowels
Authors: Erkut S. , Gulsahi K. , Caglar A. , Imirzalioglu P. , Karbhari V. M. , Ozmen I.
Published: January 2008

Clinical Relevance

Based on the in vitro results of this study, restoration of a tooth with an overflared root canal, using individually shaped polyethylene reinforced dowels, may help to reduce microleakage.
On the interaction of ductile damage and materials softening of a Ni-base alloy during hot deformation
Authors: Rüf Guntram , Sommitsch Christof , Buchmayr Bruno
Published: January 2008

Macro- and micromechanically motivated damage models have been validated in the critical temperature range of 900 °C – 1000 °C with respect to their applicability and precision in fracture prediction using a commercial finite element code and by the means of an experimental database. The evaluation of the experimental and the calculated fracture strains corresponding to an averaged critical damage value shows major deviation for all models except the model of effective stresses based on the work of Lemaitre. The results have been improved further for 1000 °C either by using a microstructure model to consider dynamic recrystallization or the coupling of the flow stress and the damage parameter calculation.

Electron backscatter diffraction analysis showed that cracks always started at grain boundaries but with the onset of dynamic recrystallization at higher temperatures crack growth also seems to take place within recrystallized grains.
Relaxation of semiconductor nanostructures using molecular dynamics with analytic bond order potentials*
Authors: Scheerschmidt Kurt , Kuhlmann Volker
Published: January 2008

Molecular dynamics simulations using empirical potentials have been performed to describe atomic interactions during the relaxation of nanostructures. To include the quantum mechanical nature of atomic bonding a tight-binding based bond order potential is developed applying analytically the first six moments. The bond order potential is improved using new on-site and -terms of the local density of states. The applicability of the bond order potential and resulting enhancements in structural predictions are analyzed recalculating quantum dot relaxations and interface defects arising during bonding of two wafers with twist rotation misalignment. The most important property proposed by the extended bond order potential is an increased stiffness of the bonds which give modifications of local atomic arrangements near defects.
Examination of phase transformations in the system Fe–N–C by means of nitrocarburising reactions and secondary annealing experiments; the α + ∊ two-phase equilibrium
Authors: Nikolussi Marc , Leineweber Andreas , Bischoff Ewald , Jan Mittemeijer Eric
Published: January 2008

The until now controversially discussed existence of the two-phase equilibrium α-Fe + ∊-Fe3(N, C)1+x in the ternary system Fe – N – C was proven by the investigation (optical microscopy, X-ray diffraction, Electron Backscatter Diffraction) of compound-layer microstructures generated by gaseous nitrocarburising of pure iron and subsequent secondary annealing experiments under static inert-gas atmosphere. The invariant transition reaction γ-Fe4N + Fe3C → α-Fe + ∊-Fe3(N, C)1+x could be shown to proceed at a (single) temperature (at constant pressure of 1 atm) between 833 K and 843 K.
On the evolution of secondary hardening carbides in a high-speed steel characterised by APFIM and SANS
Authors: Leitner Harald , Clemens Helmut , Akre Johann , Danoix Frederic , Staron Peter
Published: January 2008

Secondary hardening carbides in high-speed steels are very important microstructural constituents, responsible for the excellent properties of this type of steel. Therefore, detailed knowledge about their precipitation behaviour with respect to type, size and chemical composition is of paramount interest. Atom probe field ion microscopy and small-angle neutron scattering have emerged to be important techniques for the characterisation of nanometre-sized precipitates, such as secondary hardening carbides. In this paper, the precipitation behaviour of the high-speed steel HS6-5-2 with the nominal composition (in wt.%) Fe-0.9C-4.1Cr-6.4W-5Mo-1.8V was investigated. Differently tempered specimens were analysed to determine size, volume fraction and chemical composition of the secondary hardening carbides using a three-dimensional tomographic atom probe and small-angle neutron scattering. The results obtained from both techniques were compared with emphasis on the chemical composition of the precipitates.
Mechanisms of elastodynamic erosion of electron-beam thermal barrier coatings
Authors: Zisis Athanasios , Fleck Norman A.
Published: January 2008

The elastodynamic response of a columnar thermal barrier coating to normal impact by a spherical particle is explored using an explicit finite element method. The transient stress state involves a tensile component at the edge of each column, and this may lead to erosion. The contact problem can be simplified to the impact of a single column by an inclined wedge. The peak tensile stress is determined as a function of geometry of column and level of friction between wedge and columns. The initiation of a crack from a pre-existing flaw within the column is explored. The implications of the various calculations are discussed for erosion of thermal barrier coatings.
Directed assembly of fluidic networks by buckle delamination of films on patterned substrates
Authors: Moon Myoung-Woon , Chung Seok , Lee Kwang-Ryeol , Oh Kyu Hwan , Stone Howard A. , Hutchinson John W.
Published: January 2008

A method to create networks of intricate fluidic channels formed from metals and ceramics is proposed and demonstrated. The method exploits buckle delamination of a thin compressed film bonded to a substrate. A low adhesion layer coinciding with the desired layout of the channel network is laid down prior to deposition of the film. Once triggered, the buckle delamination propagates along the low adhesion pathways driven by release of the elastic energy stored in the film, assembling the entire channel network without external intervention. Strips, tapered strips and a selection of grids are demonstrated for diamond-like carbon films bonded to Si substrates with gold providing low adhesion. Control of the film thickness (15 to 260) and the width of the low adhesion regions (200 to microns) enables the cross-sectional area of the channel to be defined precisely with height determined by the buckle amplitude (40 to 500). The channel network has been integrated with a microfluidic interface formed from polydimethylsiloxane. Pressure-driven flow of two miscible streams shows convectively enhanced mixing in these nanoscale buckled channels.
Crystal chemistry of interfaces formed between two different non-metallic, inorganic structures
Authors: Andeen David , Lange F. F.
Published: January 2008

Epitaxial relations are often described by the mismatch of lattice parameters between the two materials. When the structures forming the epitaxial interface are dissimilar, the lattice mismatch is often less meaningful because of the different geometrical arrangement of atoms in the two structures. In a previous paper, it was shown that two rules of crystal chemistry, widely known as Pauling's rules, namely cation/anion coordination and charge balance, could be applied to understand the epitaxy of (0001) ZnO (wurtzite) on (111) MgAl2O4 (spinel) substrates. It was then shown that the same rules could be applied to predict and confirm the epitaxy of (101) SiO2 (cristobalite) on (0001) Al2O3 (sapphire). Here, the same rules are applied to explain the epitaxy of four other dissimilar structures that have been previously published by others, including SrTiO3 on Ni c(2 × 2) S, TiO2 (anatase) on LaAlO3, TiO2 (rutile) on r-plane Al2O3, and Zr1−x
(Y
x
)O2 on (0001) Al2O3.
Internal stresses and phase stability in multiphase environmental barrier coatings
Authors: Faber K. T. , Weyant C. M. , Harder Bryan , Almer Jonathan , Lee Kang
Published: January 2008

The use of silicon-based ceramics in power generation applications is limited by recession of the passivating SiO2 when it reacts with water-vapor to form a volatile hydroxide. Environmental barrier coatings are used to prevent diffusion of reactive species to the structural ceramic substrate. Often these barriers are multilayered and/or multiphase to provide optimal thermal expansion match, microstructural stability, as well as low diffusivities. High energy X-rays are used to assess internal stress as well as phase content and stability in two coating systems: alloyed Ta2O5 for Si3N4 and strontium-aluminosilicates for SiC/SiC. In particular, the role of phase transitions and precipitation on the coating internal stresses is evaluated along with their ramifications for coating lifetime.
Reactions in the sintering of MgAl2O4 spinel doped with LiF
Authors: Reimanis Ivar E. , Kleebe Hans-Joachim
Published: January 2008

Reactions between MgAl2O4 and LiF during low-temperature sintering have been examined by transmission electron microscopy. It is shown that the presence of LiF at elevated temperatures leads to the formation of a defect MgAl2O4 spinel phase containing oxygen vacancies due to the incorporation of both Li and F ions into the crystal lattice. Consequently, densification is promoted via the diffusion of oxygen vacancies. Note that neither of the lithium aluminate phases, LiAlO2 and Li2Al4O7, were detected.
Crack-tip strain fields in collagen biomaterials for skin tissue engineering
Authors: Lee Joshua T. , Wachsmann-Hogiu Sebastian , Shaw Michael C.
Published: January 2008

The objective of this investigation was to determine the notch-tip strain fields in Type-I collagen biomaterials. Experiments were performed in-situ in a fixture mounted on the stage of an optical stereozoom microscope with edge-notched Type-I collagen tensile specimens. Image markers were added around the notch, and a tensile strain was applied. High-resolution images were collected at different levels of far-field strain. Image analysis was performed to measure the displacements of individual surface markers. The resultant displacement fields were analyzed to yield in-plane surface strain profiles along trajectories perpendicular to the crack plane. The results revealed significant local strain amplifications near the notch tip of nearly twenty times. These results are discussed in light of existing constitutive models for crack-tip strain fields.
Detailed mtDNA genotypes permit a reassessment of the settlement and population structure of the Andaman Islands
Authors: Barik S.S. , Sahani R. , Prasad B.V.R. , Endicott P. , Metspalu M. , Sarkar B.N. , Bhattacharya S. , Annapoorna P.C.H. , Sreenath J. , Sun D. , Sanchez J.J. , Ho S.Y.W. , Chandrasekar A. , Rao V.R.
Published: January 2008

The population genetics of the Indian subcontinent is central to understanding early human prehistory due to its strategic location on the proposed corridor of human movement from Africa to Australia during the late Pleistocene. Previous genetic research using mtDNA has emphasized the relative isolation of the late Pleistocene colonizers, and the physically isolated Andaman Island populations of Island South‐East Asia remain the source of claims supporting an early split between the populations that formed the patchy settlement pattern along the coast of the Indian Ocean. Using whole‐genome sequencing, combined with multiplexed SNP typing, this study investigates the deep structure of mtDNA haplogroups M31 and M32 in India and the Andaman Islands. The identification of a so far unnoticed rare polymorphism shared between these two lineages suggests that they are actually sister groups within a single haplogroup, M31′32. The enhanced resolution of M31 allows for the inference of a more recent colonization of the Andaman Islands than previously suggested, but cannot reject the very early peopling scenario. We further demonstrate a widespread overlap of mtDNA and cultural markers between the two major language groups of the Andaman archipelago. Given the “completeness” of the genealogy based on whole genome sequences, and the multiple scenarios for the peopling of the Andaman Islands sustained by this inferred genealogy, our study hints that further mtDNA based phylogeographic studies are unlikely to unequivocally support any one of these possibilities. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
Investigating health at Kerma: Sacrificial versus nonsacrificial individuals
Authors: Buzon Michele R. , Judd Margaret A.
Published: January 2008

This analysis examines heterogeneity in risks by assessing the health status of individuals in two distinct burial contexts from the Nubian site of Kerma: sacrificial (n = 100) and nonsacrificial (n = 190) burial areas dated to the classic Kerma period (∼1750–1500 BC). Indicators of physiological stress that were examined include cribra orbitalia, dental enamel hypoplasia, tibial osteoperiostitis, and femur length. The analysis presented here shows that the people interred in the sacrificial and nonsacrificial burial contexts at Kerma in Upper Nubia had similar health profiles that were comparable with other contemporaneous samples from the region. If sacrificial individuals did not experience the same risk of death as nonsacrificial individuals, it was not evident in the frequencies of nonspecific stress indicators. However, this differential risk of death may be blurred by our inability to examine nonadults for childhood disease. This research demonstrates the complexities involved in understanding the multiple factors that result in heterogeneity in skeletal samples. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
The Blout Laboratory at Harvard Medical School from 1957 to 1972
Authors: Simons Elizabeth R.
Published: January 2008

Elkan R. Blout's laboratory at the Children's Cancer Research Foundation and Harvard Medical School pioneered many approaches to the synthesis, conformation and structural studies of polypeptides, biopolymers and selected proteins. Here the early days (1957–1972) of his research group are remembered. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 336–337, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com