bluuebunny/crossref_metadata_2025 huggingface dataset:
Cemented Femoral Fixation: The North Atlantic Divide
Authors: Dunbar Michael J.
Published: September 2009

European nations, especially Scandinavian countries, have used cemented fixation since the introduction of total hip arthroplasty. In Sweden, with arguably the best national-level data on prostheses survivorship, >90% of all stems are fixated with cement. In sharp contrast, it is estimated that in the United States, >88% of all femoral stems use cementless technology. This represents a diametrically opposed difference in philosophical approach: the so-called North Atlantic Divide. The departure in North America from cemented femoral stems can be traced to the coinage of the phrase “cement disease,” which implicated cement as a leading cause of osteolysis. This led to prolific innovation of uncemented technologies in North America, while European countries favored standardization enabled by the national arthroplasty registries. The term “cement disease” has been proven to be a misnomer, as supported by excellent outcomes from the Scandinavian registries, as well as excellent long-term outcomes for cemented stems in United States series, even in patients younger than 50 years. Like uncemented stems, there is variability in survivorship between femoral stems, and this appears to be related to specific design features. Despite the excellent long-term results, the use of cemented femoral components in Europe and Canada is decreasing in favor of uncemented stems. The reasons for this are not immediately obvious.
Acetabular Options: Notes From the Other Side
Authors: Corten Kristoff , Au Keegan , Bourne Robert B.
Published: September 2009

The socket remains the weakest link of primary total hip arthroplasty (THA). The revision rates of the socket are higher than those of the stem, with aseptic loosening and polyethylene wear being the most frequent indications for revision THA. Both cemented all-polyethylene cups and cementless sockets have benefited from stepwise improvements in surgical techniques and designs. In many countries, cementless sockets have replaced cemented cups during primary THA, with >90% of the acetabular components using a cementless fixation mode. The long-term prospective data of cementless sockets from high-volume centers show excellent and equivalent survivorship to cemented implants, but the insertion technique is easier and quicker. In addition, cementless sockets are more versatile than cemented all-polyethylene cups. With cementless sockets there is a move to increased porosity of the ingrowth surface, tri-bearing options, and enhanced locking mechanisms. There is a role for well-conducted randomized controlled trials to assess these new designs because data from various national registries show that the socket remains the weakest link of primary THA. Factors like sex, age, diagnosis, and bearing couples have a different and significant influence on the intermediate to long-term survivorship of contemporary cemented and cementless THA.
Algorithmic Approach for Reconstruction of Proximal Femoral Bone Loss in Revision Total Hip Arthroplasty
Authors: Higuera Carlos A. , Capello William , Barsoum Wael K.
Published: September 2009

Reconstruction of the femur depends on the quantity of bone loss and the quality of the remaining bone stock. Multiple classifications and reporting systems can be used to characterize the bone defect. We present a simple algorithmic approach for proximal femoral bone loss reconstruction during revision total hip arthroplasty. Quantity of bone loss is assessed using radiographs based on different classification systems, whereas quality of the remaining bone stock is assessed intraoperatively. Based on the type of proximal bone loss and the quality of the available bone, we describe our preferred reconstruction technique.

For minor bone loss, the metaphysis is expanded but intact with partially absent calcar. There is minimal bone loss anteriorly and posteriorly, and the diaphysis is intact. For significant bone loss, the metaphysis is compromised, and there is no calcar. There is minimal bone loss anteriorly and posteriorly. The available proximal bone may be thin, sclerotic, and incapable of support. However, the diaphysis is intact. For massive bone loss, there is complete circumferential bone loss in the metaphysis, extending to the diaphysis. The anterolateral bone and supporting subtrochanteric metaphyseal bone are absent. The metaphysis is not stable and will not offer rotational stability. There is massive bone loss anteriorly and posteriorly. The stability of the implant is dependent on distal diaphyseal fixation. For complete proximal bone loss, there is extensive circumferential segmental bone loss proximally and extensive cavitary loss involving the entire diaphysis. Additionally, there is extensive ectasia of the diaphysis.
Antibiotic Bone Cements: Their Use in Routine Primary Total Joint Arthroplasty is Justified
Authors: Dunbar Michael J.
Published: September 2009

The use of antibiotic bone cement in total hip arthroplasty (THA) is the standard of care in countries with long-standing national registries, as data from the registries demonstrates an improvement in survivorship by reducing the incidence of both septic and aseptic failures. There is reluctance in North America to embrace antibiotic bone cement, although the percentage of use is increasing. Reasons cited for not using antibiotic cement include lack of efficacy, adverse effects on mechanical properties, increased costs, bacterial resistance, and systemic toxicity. Little to no compelling data in the literature support these claims, and significant evidence refutes them, specifically: registry data and randomized controlled trials demonstrate a clear reduction in deep joint infections with the use of antibiotic bone cement; antibiotic bone cement has lower incidence of both septic and aseptic loosening, indicating no negative effect on mechanical properties; antibiotic bone cement is cost-effective, given its proven ability to reduce revision rates and prevent poor patient outcomes; there is no evidence to support bacterial resistance, and antibiotic bone cement may reduce the incidence of resistance; and there are no reported cases of systemic toxicity from manufacturer-prepared antibiotic cement in primary THA or total knee arthroplasty.

Based on the strong evidence supporting the benefits of antibiotic bone cement and the lack of evidence against its use, it is difficult to justify why antibiotic cement is not the standard of care for primary cemented THA in North America.
Computer-assisted TKA: Greater Precision, Doubtful Clinical Efficacy: Opposes
Authors: Mullaji Arun , Shetty Gautam M.
Published: September 2009

Despite improved precision of component placement and consistent and accurate restoration of neutral limb alignment, controversy persists regarding the clinical benefits of computer-assisted total knee arthroplasty (TKA). Computer-assisted TKA provides excellent information regarding gap equality and symmetry throughout the knee range of motion and allows precise, quantitative soft tissue release for deformities, especially in knees with severe flexion contractures and severe rigid valgus deformities. Hence accurate restoration of gap balance, joint line, and posterior femoral offset consequently improves functional results. Knee arthritis with complex extra-articular deformities and in situ hardware can be tackled appropriately using computer navigation where conventional techniques may be inadequate. It also allows intra-articular correction for extra-articular deformities due to malunions and facilitates extra-articular correction in cases with severe extra-articular tibial deformities. In obese patients, where the alignment of the limb is difficult to assess, computer navigation improves accuracy and reduces the number of outliers. The ability to quantify the precise amount of bone cuts and soft tissue releases needed to equalize gaps and restore alignment, reduced blood loss, and incidence of systemic emboli improves the safety of the procedure and hastens functional recovery of the patient. Hence, computer-assisted TKA not only provides greater precision, but also greater clinical benefit.
Precision Surgery
Authors: Dorr Lawrence D. , Deshmane Prashant
Published: September 2009

Accurate component placement in joint replacement cannot be overemphasized; despite many re-engineering efforts over the past 3 decades, failure rates at 10 years for total hip arthroplasty (THA) and total knee arthroplasty (TKA) remain constant. Intraoperative decisions with joint replacement have been facilitated with manual instrumentation and are affected by the surgeon's intuition, instinct, and experience. Current technology allows the development and use of high-tech instrumentation, which, irrespective of surgeon-dependent variables, gives intraoperative quantitative information on which precise placement of hip and knee components can be done. Component placement is the single most important technical maneuver the surgeon accomplishes to prevent mechanical complications, which will nearly eliminate outliers from very good and excellent results and revision as a consequence of technical errors; computer navigation has almost made it possible. In knees it gives precise component placement in the coronal and sagittal planes, and in hips it particularly improves acetabular component position by numerical control of inclination, anteversion, and most importantly center of rotation. Precision is enhanced even more when computer navigation is elevated to the next level, which is robotic guidance. The preoperative plan set by the surgeon is executed by the robotic tool while the surgeon manually controls the robotic arm. Bone preparation cannot exceed the boundaries the surgeon has set, as the surgeon's manual force will stop the robot and the error cannot be made. Robotic surgery has progressed in the unicompartmental knee, and this innovation is in the final stages of development in THA.
Extensor Mechanism Ruptures
Authors: Brooks Peter
Published: September 2009

The extensor mechanism of the knee consists of the quadriceps muscle and tendon, the patella, the patellar tendon, and the tibial tubercle. Disruption of any of these can lead to an extensor mechanism rupture and render an otherwise perfectly good total knee replacement (TKR) useless. Quadriceps tears associated with TKR are difficult to treat and associated with a poorer prognosis than in the native knee. Transosseous sutures tied over the distal pole of the patella are recommended. Patella fractures may heal in continuity or may involve a disruption of the extensor mechanism. The blood supply may have been compromised during TKR, so healing may be delayed. The patella component may be loose and need to be removed or revised.

Patellar tendon ruptures are the most common and serious form of extensor mechanism rupture. Prevention is more effective than treatment. Careful exposure during revision surgery includes anticipating the need for a quadriceps snip, pinning the tubercle to avoid avulsion, and preserving the fat pad during primary surgery. Treatment of patellar tendon ruptures is challenging. Primary repair may succeed in early intervention, but in established rupture, allograft reconstruction is often necessary. Achilles tendon allograft is preferred. The calcaneus fragment is embedded into the proximal tibia as a new tubercle, and the tendon is sutured into the remaining extensor mechanism. The repair is then protected using a cable loop from the superior pole of the patella to a drill hole in the upper tibia.
Radiation Therapy for Preventing Recurrence of Neurogenic Heterotopic Ossification
Authors: Cipriano Cara , Pill Stephan G. , Rosenstock Jeffrey , Keenan Mary Ann
Published: September 2009

Radiation therapy is commonly used to prevent heterotopic ossification, and the dose-dependent effects of this treatment have been well documented in patients after total hip arthroplasty (THA). However, the efficacy and dose requirement of radiation therapy to prevent heterotopic ossification of nonsurgical origin have not been studied. The purpose of this retrospective case-control study was to determine the effects of prophylactic radiation therapy on severe heterotopic ossification recurrence, postoperative range of motion (ROM), and wound healing in patients with heterotopic ossification secondary to neurologic deficits.

Selection was not blinded, and higher risk patients were generally assigned to the treatment group. Standard doses of radiation therapy did not adequately lower recurrence rates; in fact, there was a higher incidence of heterotopic ossification formation necessitating revision in the treatment group (15.0%) compared to the control group (5.1%). Moreover, patients who received radiation therapy were not more successful at maintaining intraoperative ROM over time. There was a similar incidence of delayed wound healing between groups (12.8% in the control group and 12.5% in the treatment group), and no other negative side effects or complications were observed.

These results suggest that the 700 cGy dose of radiation therapy typically used for the prophylaxis of heterotopic ossification associated with THA does not effectively prevent the recurrence of neurogenic heterotopic ossification in high-risk patients. Further studies are needed to determine whether higher doses of radiation therapy will provide more effective prophylaxis for heterotopic ossification.
Reconstruction of Humeral Head Defect for Locked Posterior Shoulder Dislocation
Authors: Modi Chetan S. , Wicks Laurence , Srinivasan Kuntrapaka
Published: September 2009

Locked posterior shoulder dislocation is a rare injury and is often missed on examination, usually due to inadequate imaging and potentially resulting in significant loss of shoulder function. An important feature of the physical examination is identification of the patient's inability to externally rotate their arm. These injuries are associated with defects in the humeral head articular surface, also known as reverse Hill-Sachs lesions. Medium-sized defects involving 25% to 50% of the articular surface can be reconstructed using several methods, including subscapularis or lesser tuberosity transfer, rotational osteotomy of the humerus, osteochondral autografting, and allograft reconstruction.

We describe reconstruction of a 40% anteromedial humeral head articular surface defect associated with a missed locked posterior shoulder dislocation. Our technique used a deltopectoral approach with soft tissue dissection through the rotator interval to enable direct access to the defect with preservation of the rotator cuff muscles. The impacted articular surface was elevated, and the void was filled with moldable putty consisting of tricalcium phosphate with carboxymethylcellulose (Calstrux; Stryker Biotech, Hopkinton, Massachusetts). The articular fragment was then secured in position with size 5 Ethibond (Ethicon, Inc, Somerville, New Jersey) bone sutures. The patient regained excellent function and range of motion, with computed tomography scanning at 9 months demonstrating a smooth humeral articular surface with excellent graft incorporation.

This technique avoids donor site morbidity and potential risks with allograft use while maintaining normal shoulder joint anatomy with preservation of the rotator cuff muscles for less complicated prosthetic reconstruction if required in the future.
Failed Total Knee Arthroplasty With Dislocated Rotating Platform Polyethylene Component
Authors: Bancroft Laura W. , Peterson Jeffrey J. , Blasser Kurt E.
Published: September 2009

The case:
A 61-year-old man presented with a painful right knee. The patient reported instability and restricted motion, which had become progressively worse and painful. AP and lateral radiographs (
Figure
) of the knee are shown.
Regulatory T Cells Negatively Regulate Neovasculature of Airway Remodeling via DLL4-Notch Signaling
Authors: Huang Miao-Tzu , Dai Yang-Shia , Chou Yu-Bin , Juan Yi-Hsiu , Wang Chih-Chiang , Chiang Bor-Luen
Published: September 2009

Regulatory T cells (Treg) have been shown to prevent the development of allergic asthma; however, the role of Treg in asthma with established airway remodeling is unknown. To address this, we exploited an OVA-induced chronic asthma mouse model wherein Treg were adoptively transferred to the mice at chronic stage of the model. We found that among the structural alterations of airway remodeling, Treg selectively reduced the vessel numbers in both peritracheal and peribronchial regions and the lung parenchyma. Extracellular matrix deposition, mucus metaplasia, muscular hyperplasia, and vasodilation, as were also induced by chronic allergen challenge, were not affected by Treg. TUNEL staining of the lung sections revealed an increased endothelial cell (EC) apoptosis in mice receiving Treg transfers compared with their asthmatic counterparts. By using Matrigel angiogenesis assays, we showed that Treg inhibited EC angiogenesis both in vitro and in vivo. Treg preferentially expressed Notch ligand DLL4, and an anti-DLL4 blocking Ab abrogated the inhibitory effect of Treg on EC tube formation. In vivo, decreased airway and lung vessel numbers as well as ameliorated airway hyperresponsiveness after Treg transfers were reverted when Treg-derived DLL4 signal was blocked by the anti-DLL4 Ab. Our findings demonstrate a novel function of Treg whereby Treg down-regulate remodeling angiogenesis via proapoptotic DLL4-Notch signaling, and suggest a therapeutic potential of Treg in alleviating airway hyperresponsiveness of chronic asthma.
A Role for Complement in the Enhanced Susceptibility of Steatotic Livers to Ischemia and Reperfusion Injury
Authors: He Songqing , Atkinson Carl , Evans Zachary , Ellett Justin D. , Southwood Mark , Elvington Andrew , Chavin Kenneth D. , Tomlinson Stephen
Published: September 2009

Hepatic steatosis typically renders the donor organ unusable, as donor organs with >30% steatosis are more likely to develop graft failure. The mechanisms leading to failure are not well defined, but steatosis enhances hepatic susceptibility to ischemia reperfusion injury (IRI). We investigated the role of complement in hepatic IRI in lean and steatotic (diet-induced) mice. Steatotic mice were significantly more susceptible to total warm hepatic IRI than lean mice as determined by serum alanine aminotransferase, histopathologically assessed damage, and 24-h survival. C3 deficiency protected both lean and steatotic mice from IRI, as determined by all measured outcomes. Furthermore, treatment of wild-type mice with the complement inhibitor CR2-Crry provided protection equivalent to that seen in C3-deficient mice. Importantly, although steatotic livers were much more susceptible to IRI than lean livers, by most measures there was no statistical difference between the level of IRI to steatotic or lean livers when complement was inhibited. To investigate the clinical relevance of these findings in the context of transplantation, we treated recipients of lean or steatotic liver grafts with saline or CR2-Crry. There was a marked reduction in graft inflammation and injury and significantly improved 7-day survival in CR2-Crry-treated recipients of either lean or steatotic grafts. These data indicate that complement plays a key role in the enhanced susceptibility of steatotic livers to IRI and suggest that complement inhibition represents a potential strategy to reduce the donor shortage by allowing the more routine use of marginal steatotic donor livers.
The treatment outcomes of tuberculosis among health care workers in a general hospital in the Mpumalanga province, South Africa
Authors: Ukpe Idongesit S. , Blitz Julia , Hugo Jannie , Nkosi Ralph , Mpangane Thembi , McLaren Sharon
Published: September 2009

Background: South Africa is one of the countries in the world with a high burden of tuberculosis (TB). High rates of unfavourable treatment outcomes have remained a feature of TB control in the country. The objective of the current study was to examine the treatment outcomes of TB among health care workers (HCWs) at a rural general hospital in the Mpumalanga province of the country, as well as the clinical care that was provided to the HCWs. The purpose of the study was to identify possible areas for improvement in the TB care services provided to HCWs in the hospital, especially with regard to their clinical management.Method: The research described in this article consists of a retrospective descriptive study. Relevant data on HCWs diagnosed with TB in the hospital during 2007, the TB care services offered to the HCWs, and the treatment outcomes of the HCWs were captured from the occupational health and TB control programme registers at the hospital onto a data capture sheet for the study and were subsequently analysed manually.Results: Nine HCWs, eight females and one male, were diagnosed and treated for TB in the hospital during 2007, an incidence rate of 941/100 000. Their ages ranged from 39 to 54 years, with a mean age of 48 years. By occupation, the nine HCWs consisted of six nurses (67%), one porter (11%), one general assistant (11%), and one clerk (11%). Of those treated for TB, seven (78%) had smearpositive pulmonary TB (PTB) and two (22%) had extra-pulmonary TB (EPTB). TB culture and drug susceptibility testing (DST) was undertaken for only one HCW. The HIV status was known for only two (22%) of the nine HCWs under review. Neither of the two HCWs with EPTB had the diagnosis confirmed by bacteriological or histopathological method. The seven HCWs with smear- positive PTB achieved a cure, and the two HCWs with EPTB successfully completed treatment, resulting in a treatment success rate of 100% for the nine HCWs.Conclusion: The HCWs at Themba Hospital in the Mpumalanga province of South Africa who were diagnosed and treated for TB during 2007 all achieved favourable treatment outcomes. However, in view of the high rate of HIV/TB co-infection and the increasing problem of drug-resistant TB in the country, the clinical care provided to HCWs with TB by the hospital should be improved with regard to routine HIV counselling and testing and the routine early provision of DST. A protocol for the comprehensive management of HCWs with TB is currently undergoing development.
Charged Particle Activation Analysis
Authors: Erramli Hassane
Published: September 2009

Radioactivation methods in general are essential for trace analysis because of their accuracy; among these methods, charged particle activation analysis (CPAA) is especially suitable for the determination of light elements such as boron, carbon, nitrogen, and oxygen at trace levels in materials. CPAA can also be used advantageously for other heavier elements if needed, and sometimes be a complement to neutron activation analysis, or even competes with it.

The CPAA is the best reference method because of its high sensitivity and selectivity. It permits the determination of the total concentration, regardless of chemical state. The surface contamination can be eliminated by etching after irradiation and absolute concentrations can be obtained by direct comparison with known compounds. There are no matrix effects and no need for reference samples.

This article describes and discusses, in more detail, the principle and some applications of CPAA. Examples are given of typical applications of CPAA technique such as the study the oxygen profiling in Czochralski‐silicon (Cz‐Si) substrates submitted to a rapid thermal annealing, and the study of the oxygen behavior in thermally treated Cz‐Si substrates by combining CPAA with ion channeling.
Atomic Force Microscopy: Contribution to the Birth of Nanocell Biology
Authors: Jena Bhanu P.
Published: September 2009

Throughout history, the development of new imaging tools has provided new insights into our perceptions of the living world, profoundly impacting human health. The invention of the light microscope over 300 years ago was the first catalyst that propelled us into the era of modern biology and medicine. Using the light microscope, a giant step into the gates of modern medicine was made with the discovery of the unit of life, the cell. The structure and morphology of normal and diseased cells, and of disease‐causing microorganisms, were revealed for the first time by the light microscope. Then, in 1938, with the birth of the electron microscope (EM), dawned a new era. Through the mid‐1940s and the 1950s, a number of subcellular organelles were discovered and their functions determined using the EM. Viruses, the new life forms were identified and observed for the first time, and implicated in diseases ranging from the common cold to acquired immune deficiency syndrome (AIDS). Despite the capability of the EM to image biological samples at near nanometer resolution, sample processing resulting in morphological alterations remained a major concern. Then in the early 1980s, scanning probe microscopy evolved, further extending our perception of the living world to the subnanometer realm. One such scanning probe microscope, the atomic force microscope (AFM), has helped overcome both limitations of light and electron microscopy, enabling determination of the three‐dimensional (3D) structure and dynamics of single biomolecules and live cells, at angstrom resolution. This unique capability of the AFM has provided a new understanding of the cell, through determination of 3D live cellular structure‐function, at nanometer to subnanometer resolution and in real time, contributing to the birth of the field ofnanocell biology. The story of how the use of the AFM resulted in the discovery of a new cellular structure, the “porosome”—the universal secretory machinery in cells—that allows an understanding of the general molecular machinery and mechanism of cell secretion, is briefly discussed in this article.
Detection of Microbial Water Quality Indicators and Fecal Waterborne Pathogens in Environmental Waters: A Review of Methods, Applications, and Limitations
Authors: Santo Domingo Jorge W. , Rice Eugene W.
Published: September 2009

Environmental waters are important reservoirs of pathogenic microorganisms, many of which are of fecal origin. In most cases, the presence of pathogens is determined using surrogate bacterial indicators. In other cases, direct detection of the pathogen in question is required. Microbiological methods to determine the presence of indicator organisms or pathogens in environmental samples vary depending on the target organism, sample type, need for quantification, speed of detection, sensitivity, and detection limits. Classical methods depend on cultivation steps while emerging techniques rely on detecting genetic signals from nucleic acid extracted from water samples. Regardless of the method, accurate detection is important to public health officials and monitoring agencies. In this article, we review some of the methods used to detect and quantify indicators of microbial water quality and human fecal pathogens as well as other issues relevant to water fecal pollution.
Measurement of Algal Toxins in the Environment
Authors: Botana Luis M , Louzao M. Carmen , Alfonso Amparo , Botana Ana M , Vieytes Mercedes R , Viñariño Natalia , Vale Carmen
Published: September 2009

Algal toxins are important from an analytical point of view because they need to be constantly scrutinized owing to the danger they pose to consumers when they concentrate in filter‐feeding shellfish or in drinking water and fish. Their chemical diversity is very large, with each group having many analogs. Each group has different pharmacological activities, although not all the mechanisms of action are understood. The main marine toxin groups are as follows: saxitoxin and analogs, okadaic acid and dinophysistoxins, azaspiracids, yessotoxins, pectenotoxins, cyclic imines, domoic acid, ciguatoxins, brevetoxins, palytoxin, gambierol, and polycavernoside. The main cyanobacterial toxins considered are hepatotoxins such as microcystins, nodularin, and cylindrospermopsin. The research concerning marine toxins is underdeveloped owing to a historic scarcity of standards. This has delayed not only the progress in their pharmacology but also the development of methods for detection and measurement. In the current situation, the mouse bioassay is the most common method being used to measure them. New methods are rapidly emerging as future solutions: (i) functional and nonanalytical methods, which provide information on their toxicity and quantify the toxin group (cell assays, receptor assays, biosensor assays), (ii) biochemical methods that do not provide information on toxicity (antibody‐based methods), and (iii) analytical methods, which identify the species in each toxin group, and can quantify those for which standards are available. The main drawback of these methods is the lack of toxicity equivalent factors, which allow the conversion of toxin amounts to toxic values of a reference toxin. None of these methods has been validated, and therefore much remains to be done in the field.
3
D
Neutron Imaging
Authors: Lehmann E. H. , Kaestner A. P.
Published: September 2009

This article describes the present status of neutron tomography (NT) as a valuable tool for scientific studies and for industry‐related investigations. Similar to X‐ray tomography, the determination of the volume data is based on a sequence of single projections of the object under investigation while it rotates around its vertical (or horizontal) axis. The reason why NT differs from X‐ray techniques in the interaction probability with matter, which causes alternative contrast variations, is outlined in detail.

On the basis of the presentation of principles, the description of existing facilities, tools for image postprocessing, and some examples of prominent application ranges are given. The article concludes with the outlook for further improvements and methodical development in NT.
The testing effect: The role of feedback and collaboration in a tertiary classroom setting
Authors: Vojdanoska Marija , Cranney Jacquelyn , Newell Ben R.
Published: September 2009

Successful retrieval on a test compared to just re‐studying material improves long‐term retention—a phenomenon called the ‘testing effect’. This study investigated the role of feedback and collaborative testing on the retention of course material in a tertiary educational setting. Tested material was better retained relative to non‐tested material (testing effect), and feedback facilitated correction of errors. Group testing produced higher performance on the initial, but not final test performance, compared to individual testing. This set of findings suggests that to encourage long‐term retention, educators should utilise individual formative testing with feedback; theoretical implications are also discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Supporting remote collaborative problem‐solving
Authors: Hansen Miriam , Spada Hans
Published: September 2009

We propose a framework of individual problem‐solving and communicative demands (IproCo) that bridges the gap between models from cognitive psychology and communication pragmatics. Furthermore, we present two experiments conducted to identify factors influencing the demands and to test possibilities for support. The experiments employed a remote collaborative picture‐sorting task with concrete and abstract pictures and applied non‐interactive conditions compared to interactive conditions. In a first experiment, the influence of the postulated demands on collaboration process and outcome was analysed, and the impact of shared applications was tested. In a second experiment, we evaluated instructional support measures consisting of model collaboration and a collaboration script. The collaboration process showed benefits of the support but the outcome did not. However, the support measures fostered the collaboration process even in the particularly difficult conditions with non‐interactive communication. We discuss the impact of the IproCo framework and apply it to other tasks. Copyright © 2009 John Wiley & Sons, Ltd.
Neural‐network‐based finite‐time H∞ control for extended Markov jump nonlinear systems
Authors: Luan Xiaoli , Liu Fei , Shi Peng
Published: September 2009

This paper presents a neural‐network‐based finite‐time H∞ control design technique for a class of extended Markov jump nonlinear systems. The considered stochastic character is described by a Markov process, but with only partially known transition jump rates. The sufficient conditions for the existence of the desired controller are derived in terms of linear matrix inequalities such that the closed‐loop system trajectory stays within a prescribed bound in a fixed time interval and has a guaranteed H∞ noise attenuation performance for all admissible uncertainties and approximation errors of the neural networks. A numerical example is used to illustrate the effectiveness of the developed theoretic results. Copyright © 2009 John Wiley & Sons, Ltd.
Recent Progress in Exploring Magnetocaloric Materials
Authors: Shen B. G. , Sun J. R. , Hu F. X. , Zhang H. W. , Cheng Z. H.
Published: September 2009

The magnetic refrigeration technique based on the magnetocaloric effect (MCE) has attracted increasing interest because of its high efficiency and environment friendliness. In this article, our recent progress in exploring effective MCE materials is reviewed with emphasis on the MCE in the LaFe13−xSixbased alloys discovered by us. These alloys show large entropy changes over a wide temperature range near room temperature. The effects of magnetic rare‐earth doping, interstitial atoms and high pressure on the MCE have been systematically studied. Special issues, such as appropriate approaches to determining the MCE associated with the first‐order magnetic transition, the depression of magnetic and thermal hysteresis, and the key factors determining the magnetic exchange in alloys of this kind, are discussed. The applicability of giant MCE materials to magnetic refrigeration near ambient temperature is evaluated. A brief review of other materials with significant MCE is also presented.
Highly Surface‐roughened “Flower‐like” Silver Nanoparticles for Extremely Sensitive Substrates of Surface‐enhanced Raman Scattering
Authors: Liang Hongyan , Li Zhipeng , Wang Wenzhong , Wu Youshi , Xu Hongxing
Published: September 2009

Surface‐enhanced Raman scattering (SERS) is a new optical spectroscopic analysis technique with potential for highly sensitive detection of molecules. Recently, many efforts have been made to find SERS substrates with high sensitivity and reproducibility. In this Research News article, we provide a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, “flower‐like” morphology by reducing silver nitrate with ascorbic acid in aqueous solutions. The nanometer‐scale surface roughness of the particles can provide several hot spots on a single particle, which significantly increases SERS enhancement. The incident polarization‐dependent SERS of individual particles is also studied. Although the different “hot spots” on a single particle can have a strong polarization dependency, the total Raman signals from an individual particle usually have no obvious polarization dependency. Moreover, these flower‐like silver particles can be measured by SERS with high enhancement several times, which indicates the high stability of the hot spots. Hence, the flower‐like silver particles here can serve as highly sensitive and reproducible SERS substrates.
Integrated multi‐echelon supply chain design with inventories under uncertainty: MINLP models, computational strategies
Authors: You Fengqi , Grossmann Ignacio E.
Published: September 2009

We address in this article a problem that is of significance to the chemical industry, namely, the optimal design of a multi‐echelon supply chain and the associated inventory systems in the presence of uncertain customer demands. By using the guaranteed service approach to model the multi‐echelon stochastic inventory system, we develop an optimization model to simultaneously determine the transportation, inventory, and network structure of a multi‐echelon supply chain. The model is an MINLP with a nonconvex objective function including bilinear, trilinear, and square root terms. By exploiting the properties of the basic model, we reformulate this problem as a separable concave minimization program. A spatial decomposition algorithm based on the integration of Lagrangean relaxation and piecewise linear approximation is proposed to obtain near global optimal solutions with reasonable computational expense. Examples for specialty chemicals and industrial gas supply chains with up to 15 plants, 100 potential distribution centers, and 200 markets are presented. © 2009 American Institute of Chemical Engineers AIChE J, 2010
Phenolic foams from wood tar resols
Authors: Dos‐Santos Cláudio G. , Costa Marcelo A. , De Morais Willy A. , Pasa Vânya M. D.
Published: September 2009

This article investigates resole‐type phenolic foams, in which 40% phenol was substituted with distilled oily fractions from wood tar. Different proportions of blowing agent, hexamethylenetetramine, and stabilizer, a sodium alkyl sulfate surface active agent, were used to produce a series of rigid foams, which were characterized by curing index, density and hardness. The average curing index was about 90% and densities ranged from 480 to 960 kg.m−3. A fractal dimension (Df) approach was used to assess the homogeneity of pores within the foams and an average (dimensionless) value of 2.6 was found, indicating a non uniform structure. Compressive strength tests of the foams gave values above 1.0 MPa, which is higher than those for typical phenolic foams. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of polymeric flame retardants containing phosphorus‐nitrogen‐bromide and their application in acrylonitrile‐butadiene‐styrene
Authors: Yan Li , Zheng Yubin , Liu Jianping , Shang Hongzhou
Published: September 2009

A series of polymeric flame retardants (PFRs) containing phosphorus‐nitrogen‐bromide were synthesized from spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC), 2‐methoxyl‐4,6‐dichloro‐1,3,5‐triazine (MDCT), and tetrabromobisphenol A (TBBPA). The influence of monomer ratio on their thermal stability was investigated by adjusting the proportion of SPDPC/MDCT (mol/mol) from 80/20 to 20/80. The flammability properties of the PFRs blended with ABS were evaluated using LOI and UL‐94 vertical test. The structures of the flame retardants were characterized by means of Fourier transform infrared spectra (FTIR) and proton nuclear magnetic resonance spectroscopy (1H‐NMR). The results show that the initial temperature of decomposition is 274°C and with 35% charring residue at 500°C when the ratio of SPDPC/MDCT is 50/50. V‐0 ratings in the UL‐94 vertical test were achieved at 20–30% loading of PFRs, when LOI values reached at least 26.9%. The flame retardancy is strongly dependent on the ratio of P, N, and Br. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Stable poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) microspheres via precipitation polymerization
Authors: Jiang Xuhong , Tu Weiping
Published: September 2009

Narrow‐dispersion or monodisperse with stable and smooth surface polymer microspheres were prepared without a significant coagulum by precipitation polymerization in the absence of any stabilizer. The monomer glycidyl metharylate (GMA) was copolymerized with ethyleneglycol dimethacrylate (EGDMA) as crosslinker by precipitation polymerization technique with 2,2′‐azobisisobutyronitrile as initiator in neat acetonitrile. The effects of the content of EGDMA on the polymerization characteristics and size/uniformity of the microspheres were investigated. The onset of the thermal degradation temperature at higher temperature and the swelling test suggest that the prepared particles were highly crosslinked. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of macroporous silica modified with optically active poly[N‐(oxazolinylphenyl)acrylamide] derivatives for potential application as chiral stationary phases
Authors: Tian Y. , Lu W. , Che Y. , Shen L. B. , Jiang L. M. , Shen Z. Q.
Published: September 2009

Enantiopure acrylamide derivatives, (S)‐N‐[o‐(4‐methyl‐4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenyl]acrylamide and (R)‐N‐[o‐(4‐phenyl‐4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenyl]acrylamide, were synthesized through the acylation of chiral 2‐oxazolinylanilines. The radical polymerization of the chiral monomers was carried out with (3‐mercaptopropyl)trimethoxysilane as a chain‐transfer agent to obtain the corresponding optically active prepolymers with a trimethoxysilyl group. By immobilizing the prepolymers on porous silica gel via the grafting‐to method, we prepared a new chiral stationary phase (CSP) and characterized it by elemental analysis, thermogravimetry, and Fourier transform infrared spectroscopy. The enantioseparation capacities of the CSPs were evaluated with high‐performance liquid chromatography toward several racemic compounds, including 1,1′‐bi‐2‐naphthol, benzoin, 2‐amino‐1‐butanol, and loxoprofen sodium under the normal‐phase mode. The results indicate that the CSPs exhibited improved chromatographic performances compared to their brush‐type analogs obtained by the alternative grafting‐from approach. Also, the column packed with poly{(R)‐N‐[o‐(4‐phenyl‐4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenyl]acrylamide}‐bonded silica was found to have an extent of enantioselectivity in the chiral resolution of some unmodified amino acids with reversed‐phase eluents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Properties and structural characterization of oxidized starch/PVA/α‐zirconium phosphate composites
Authors: Yang Yajuan , Liu Changhua , Chang Peter R. , Chen Yun , Anderson Debbie P. , Stumborg Mark
Published: September 2009

Two series of composites, i.e., polyvinyl alcohol (PVA)/oxidized starch (OST)/exfoliated α‐zirconium phosphate (POST‐ZrPn) and PVA/starch (ST)/exfoliated α‐zirconium phosphate (PST‐ZrPn), were fabricated using a casting and solvent evaporation method. The composites were characterized by Fourier transform infrared spectroscopy (FT‐IR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (XRD), scanning electron microscopy (SEM), tensile testing, and moisture uptake. Compared with PST‐ZrPn, POST‐ZrPn films with the same component ratio showed higher tensile strength (σb), lower elongation at break (εb) and improved water resistance. Additionally, in the POST‐ZrPn series, σb and εb increased with an increase in α‐zirconium phosphate (α‐ZrP) loading; however, higher α‐ZrP loads resulted in the aggregation of α‐ZrP particles. Compared with POST‐ZrP0, the values for σb, εb, and water resistance of POST‐ZrP3, containing 1.5 wt % α‐ZrP, were increased by 128.8%, 51.4%, and 30.2%, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of molecular weight of epoxidized‐natural rubber on viscosity and tack of pressure‐sensitive adhesives
Authors: Poh B. T. , Yong A. T.
Published: September 2009

The effect of molecular weight of rubber on viscosity and loop tack of rubber‐adhesives were studied using two grades of epoxidized‐natural rubber, i.e., ENR 25 and ENR 50. Coumarone–indene resin, gum rosin, and petro resin were used as tackifiers. Toluene was used as the solvent throughout the experiment. The adhesive was coated on polyethylene terephthalate (PET) substrate using a SHEEN hand coater. Viscosity was determined by a HAAKE Rotary Viscometer, whereas loop tack was measured by a Llyod Adhesion Tester operating at 10 cm/min. Results show that viscosity increases gradually upto a critical molecular weight of 6.8 × 104 and 3.9 × 104 for ENR 25 and ENR 50, respectively, before a rapid increase in viscosity is observed. Loop tack indicates maximum value at the respective critical molecular weights for the three tackifiers investigated suggesting the culmination of wettability. For both rubbers, loop tack increases with coating thickness due to the concentration effect of adhesive. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Aqueous dispersion polymerization of amphoteric polyacrylamide
Authors: Wu Yumin , Wang Chuanxing , Xu Jun
Published: September 2009

The terpolymer of acrylamide (AM), dimethylaminoethyl methacrylate methyl chloride (DMC), and acrylic acid (AA) was synthesized with their molar ratio of 70 : 15 : 15 through dispersion polymerization in aqueous solution of ammonium sulfate (AS), using poly(dimethylaminoethyl methacrylate methyl chloride) (PDMC) as stabilizer and 2,2′‐azobis(2‐amidinopropane) dihydrochloride (V‐50) as initiator. The particle size of the terpolymer ranged from 5 to 8 μm and the intrinsic viscosity was from 5.5 to 11.6 dL g−1. The terpolymer had anti‐ polyelectrolyte effect under low AS concentration, but polyelectrolyte effect with the concentration beyond 10%. Polymerization dispersion with low apparent viscosity, uniform particles, good stability, and high molecular weight terpolymer was obtained in single stage. The effects of varying concentrations of salt, stabilizer, and monomers on particle morphology and intrinsic viscosity were investigated. With increasing concentration of AS and PDMC, the intrinsic viscosity of terpolymer increased, then decreased afterward. However, it increased gradually with increase in monomer concentration. The particle size was enlarged with increasing of AS and monomer concentration and decreasing of PDMC concentration. The optimum condition was the concentrations of salt, stabilizer, and monomers 28%, 3.0%, and 8% to 15%, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of polypropylene‐graft‐cardanol by reactive extrusion and its composite material with bamboo powder
Authors: Chen Qinhui , Xue Hanyu , Lin Jinhuo
Published: September 2009

The polypropylene‐graft‐cardanol was prepared by reactive extrusion, which is solvent‐free melt process, continuous processing, and controllable over residence time. The effect of monomer and initiator concentration on grafting ratio, grafting efficiency, and melt flow index (MFI) was also studied. The yield was quantified by UV–vis spectrometer. The chemical structure was investigated by infrared spectroscopy and gel ratio. A possible mechanism was supposed. The particular structure of cardanol can retain the MFI value of matrix resins and prevent polypropylene (PP) from being decomposed. The grafting ratio could be easily obtained from an experimental formula deduced from the linearity relationship between grafting ratio and MFI. The effect of cardanol grafted onto PP on the compatibility of PP and bamboo powder was studied by contact angle measurements, scanning electron microscopy, and tensile properties test. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010