bluuebunny/crossref_metadata_2025 huggingface dataset:
Laboratory Evaluation of Total Knee Replacements (TKRs) to Restore Normal Function
Authors: Vasquez Luis , Walker Peter S. , Yildirim Gokce
Published: August 2010

In a composite of various activities, the normal knee moves through a range of flexion of up to 155 deg, while at all angles there are normal ranges of “laxity,” both in an anterioposterior direction and in internal-external rotation. The ideal goal is that after a total knee replacement (TKR), the knee moves in a similar way, hence, providing the same amount of stability and freedom of motion. Our goal was to device a standardized testing method for evaluating proposed new TKR designs or existing designs. We developed a desktop knee machine, which subjects knees to combinations of forces and moments at a range of flexion angles. The proposed test method would compare the laxity motions of a given design model with the data from normal knee specimens. The TKRs were designed in the computer and then SLA models were made for testing. Computer analysis used RAPIDFORM software to calculate the laxities. In order to specify the testing method, in particular, the compressive, shear, and torque loads, we tested three different knee models with a range of loads. The magnitudes of the loads were proportionately less than in vivo due to the limitations of SLA models. When testing normal knee specimens, there were no frictional effects due to the exceedingly low coefficient of friction at the joint surfaces. However, in metal-plastic TKRs, the friction can affect the laxity and, hence, the kinematics, considerably. Hence this behavior had to be reproduced in our test method. The conclusion from our experiments was that testing should be carried out at a minimum of two compressive loading conditions, one representing low shear/torque ratios and the other, high shear/torque ratios, in order to obtain a realistic representation of the behavior of new TKR designs.
Design and Performance of Plastic Modular Adaptors for External Transtibial Prostheses
Authors: Torrealba Rafael R. , M. Muller-Karger Carmen
Published: August 2010

There is a very large need for prosthetic components in developing countries, where such devices are imported and prohibitively expensive. The present work explores the possibility of developing and manufacturing prosthetic components locally in Venezuela, preserving high quality and function. We aimed to develop a kit of plastic modular adaptors for external transtibial prostheses. The project was divided in four stages that covered design, stress analyses, manufacture, and function assessment of the components. The design process is presented in detail, resulting in a prototype that comprises four adaptors of simple design. Their response was studied with stress analysis using the Finite Element Method applying static loads for different instants of gait during the stance phase. Then, five kits of adaptors were manufactured with thermoplastic material using conventional metal-working machines. The resulting components were lighter and cheaper than equivalent imported metallic ones. The kits were adapted to four patients and assessed via gait analysis. A very good function was observed with no significant differences in spatiotemporal gait parameters.
The Quickstand: A Portable Device to Facilitate Standing Up
Authors: Arkenbout Ewout , Herder Just
Published: August 2010

Most current sit-to-stand devices are electrically powered. These devices, typically chairs, are for home use and are not portable. Yet there is a great need for a device that can be used anywhere. This paper proposes a novel portable device, named the QuickStand. Its working principle is based on a spring which provides partial support. When sitting down, this spring stores energy, which becomes available in getting up. A lock avoids undesired release of spring energy. The device is adjustable to subjects and chairs, making it very versatile. A prototype was manufactured. Technical evaluation showed the ability to provide around 150 N of support force over the whole range of motion. The device was successfully tested on a subject with a full body muscle disorder.
Periprosthetic Tissue Removal in Minimally Invasive Hip Refix Procedures
Authors: Kraaij Gert
Published: August 2010

An alternative to conventional revision surgery of loosened hip prostheses is a new minimally invasive refixation procedure. This procedure requires the removal of periprosthetic fibrous tissue. The aim of this preliminary study is to evaluate which technique is most suitable for minimally invasive periprosthetic tissue removal: a Ho:YAG laser or a VAPR-2 coblation system. The clinical situation of a loosened prosthesis was simulated by several cadaveric femora, each implanted with a hip prosthesis. Artificially created periprosthetic lesions were filled with a fibrous tissue substitute. Using this fibrous tissue substitute, we measured temperatures in vitro at different distances from the site of removal. Temperatures during removal were recorded both inside the fibrous tissue and in the surrounding bone. This study demonstrated that temperatures generated in the bone do not result in thermal damage. Temperatures inside the fibrous tissue are sufficiently high to remove the fibrous tissue. Using the laser instead of the coblation system for the removal of fibrous tissue resulted in higher temperatures, thus, a faster removal of fibrous tissue. Additionally, the laser takes less effort to be integrated with the new surgical instrument and, therefore, we consider it a promising tool. However, when translating the results to clinical practice, the limitations of this study should be kept in mind. The equipment was set to typical presets; different settings (pulse frequency, pulse energy, and activated time) might affect the procedure’s success and risks. Care must be taken with respect to generated temperatures at larger distances from the place of removal. The use of the Ho:YAG laser, as well as VAPR coblation, might form a small risk for thermal damage to healthy surrounding tissues. Further research on apparatus settings and removal strategy is necessary before this technique can be applied for the removal of fibrous tissue in the clinical setting.
Device Process Integration: A New Device Fabrication Approach
Authors: Gautham Viswanadam , Ajay Agarwal
Published: August 2010

Microelectromechanical systems (MEMS) devices have gained considerable attention in medical and automotive applications due to their vast advantages in fault detection. However, the cost for MEMS devices has been a challenge for the device manufacturing industry due to the final packaging of the devices. It is considered expensive compared with device fabrication in certain applications. Majority of MEMS devices are still housing traditional packaging methods due to difficulty in handling and yield loss. The advanced interconnect solutions based on thin silicon carrier and through silicon via are being developed to interconnect integrated circuits and other devices at high densities. Can such technologies be used for MEMS device interconnections? It is really a challenge for MEMS designers and engineers due to the MEMS elements present in the devices. In this paper, we present a device fabrication process to realize interconnects that are fabricated prior to the MEMS elements are defined and processed in the device wafer. The interconnects are filled by doped polysilicon and device wafers with such prefabricated vertical interconnects can be used as the starting wafers for any device processing including optoelectronic and MEMS. The process details and their characterization are elaborated along with the physical and electrical analysis of such interconnections.
Vaginal Approach for Uterus Separation During Laparoscopic Hysterectomy
Authors: Gahler Mart M. C. , van de Berg Nick N. J. , Rhemrev Johann , Jansen Frank W. , van den Dobbelsteen John
Published: August 2010

Every year more than 15.000 total hysterectomy procedures are performed in the Netherlands. From all these procedures, only a minor part is done via a laparoscopic approach. One reason for this is the high complexity of the procedure. The uterus is difficult to reach with the laparoscopic tools and nearby structures are easily damaged. Especially, the separation of the uterus at the fornix needs to be done with great care and is time consuming (i.e., typically takes more than 15–20 min). This results in long procedure times. To resolve part of these difficulties, a new instrument has been designed that enables separation of the uterus via a vaginal approach. The device uses a cutting mechanism to safely separate the uterus from the vagina wall. The design allows the application of an existing manipulator to mobilize the uterus for better access of laparoscopic tools. A prototype of the separation tool, MobiSep, has been manufactured. The new separation principle has been evaluated in a test setup. Over the device a tubular piece of tissue was mounted, resembling the vagina wall. The results show that the time needed for full separation is on average 102 (s). The maximum driving force needed to cut the tissue is found to be 50 (N), which can be applied manually. It is expected that this prototype is intuitive to use, can contribute to the reduction of the complexity of laparoscopic hysterectomy procedures and can reduce the total procedure time.
Hertz Contact Based Scaling of Puncture Forces for Large Scale Needle Prototypes Using a Gelatinous Tissue Phantom
Authors: Figueredo Stacy L. , Slocum Alexander H.
Published: August 2010

In order to test small scale medical devices, it is often necessary to prototype them on a larger scale such that proof-of-concept tests can be made more affordably and design details can be tested more easily. This article discusses a method of scaling large needle prototypes for testing in a gelatin phantom such that puncture forces match those expected for the actual-size needle when puncturing tissue. Using Hertz contact force equations to account for the differences in prototype materials and size, as well as for the tissue phantom properties, 10× scale prototype needles were inserted into a gelatin phantom and puncture forces were compared with those of a real scale prototype in bovine liver tissue. Results showed that for a 19 gauge (1.06 mm) stainless steel needle tip, where a maximum doctor-applied load of 5 N was desired to pierce liver tissue, loads of 0.44 N using Hertz point contact, and 0.31 N using Hertz line contact methods were predicted to puncture liver tissue, and an average load of 0.31 N was observed in force-displacement measurements. With a 10× scale stereolithographed needle prototype, Hertz point contact predicted a load of 0.31 N to puncture a gelatin phantom, Hertz line contact theory predicted 0.37 N, and an average load of 0.73 N observed in force displacement measurements. Similar contact mechanics based scaling methods might be applied to cutting devices.
Design of an Endoscope Lens Shielding Device for Use in Laparoscopic Procedures
Authors: Anderson Sterling , Zimmerman Julia , Houston Emily , Farino Kevin , Begg Nikolai
Published: August 2010

In recent years, laparoscopic surgical procedures have revolutionized many gynecological and abdominal procedures, leading to dramatic reductions in recovery time and scarring for the patient. While techniques and instruments for performing laparoscopic surgery have improved over the years, loss of vision through the endoscopic lens caused by fog, liquid, and solid debris common to laparoscopic procedures remains a significant problem. In this paper, a shielding mechanism that maintains visibility through the laparoscope by removing debris from the distal end of the lens is presented. This device provides an inexpensive and convenient alternative to the current practice of removing, cleaning, and re-inserting the laparoscope during surgical procedures. This device is shown in multiple trials to repeatably remove debris from the distal tip of the lens, thereby restoring vision for the surgeon without requiring removal or reinsertion of the endoscope.
Rotary Ultrasonic Machining of Dental Ceramics: A Preliminary Study on Subsurface Cracks
Authors: Li Zhichao , Cong Weilong , Stanco Matthew , Xu Zhigang , Pei Zhijian , Treadwell Clyde
Published: August 2010

Commercially available dental computer aided design/computer aided manufacture (CAD/CAM) systems usually use abrasive machining processes such as diamond grinding and milling. One of the major disadvantages of abrasive machining processes is subsurface cracks. In the present paper, rotary ultrasonic machining (RUM) technology is introduced into machining of alumina dental ceramics. The subsurface cracks are observed under scanning electron microscope. Effects of ultrasonic vibration on the subsurface cracks are also investigated. Results show that RUM is a very promising process to significantly reduce subsurface cracks in CAD/CAM of dental ceramics.
Mechanical Testing Device for Viscoelastic Biomaterials
Authors: Berg Jeff , Nelson Carl A.
Published: August 2010

The geometric configuration of material specimens can present challenges in fixturing such that the boundary conditions influence test results and skew accurate assessment of material properties. This can further be complicated by specimens of low stiffness such that existing equipment is not optimized for the necessary range of forces and displacements. In this paper, we describe a new device for determining viscoelastic material properties of small biologic specimens and show early results from its use. The mechanical design, control system, and theoretical underpinnings are presented.
3D Foot Plate For Diagnosis of Abnormal Range of Motion in the Hindfoot
Authors: Tuijthof Gabrielle J. M. , Pontesilli Martina , van der Zwaag Hanneke , Jonges Remmet , Maas Mario , van de Geer Stefan G. , Blankevoort Leendert
Published: August 2010

Careful diagnosis of ankle joints with suspected ligamentous trauma is necessary. Accurate 3D stress test techniques can assist in this but the devices used to stress the foot relative to the lower leg are inapt for clinical application. The goal was to evaluate whether a newly designed 3D foot plate fulfills the requirements of the intended users who are the radiology technicians and the patients. Criteria on functionality included position and fixation of the foot in extreme dorsiflexion (45 Å), plantarflexion (85 Å), inversion (55 Å), eversion (55 Å), internal (50 Å) and external rotation (50 Å), compatibility with imaging systems, and sufficient accuracy and reliability. Criteria on usability included the presence of sense of control by manual loading, successful application in 95% of an adult human population, operation within around 100 s. and low mental effort by self-explaining capability of the device. The design was based on a Stewart platform. The dimensions were determined graphically and a fixation mechanism was developed based on friction. A prototype was built from wood and plastics. This was evaluated in a CT-scanner for accuracy and reliability with four subjects. A usability test was performed with 20 radiology technicians who were asked to perform four tasks with the prototype and fill out a questionnaire. The prototype can reach all extreme foot positions for adults with varying anthropometric dimensions. Except two outliers, the accuracy of reaching an extreme foot position is 0.3–6 Å and its reliability is 0.3–3.5 Å. All radiology technicians agreed that the device could be operated by one person with minor physical and mental effort (NASA XLT median 3.5–11%). The tasks were executed with a median time of 91 s. (20–513 s.) and a median error of 0 (0–6). Its appearance was found professional and reliable. Improvement of the rubber hinges, the fixation mechanism and loading protocol could increase accuracy. Concluding, the 3D foot plate fulfills the majority of criteria and is well-received by the intended users. This demonstrates its high potential for clinical use.
The Characteristics of Innovative, Medical Devices
Authors: Holtta-Otto Katja , Saunders Matthew , Seepersad Carolyn
Published: August 2010

It is not easy to design an innovative and successful product in any field of engineering. Medical device design is further complicated by strict regulations. Current engineering design methods provide help in designing a good product, but the designer lacks tools that help him or her create an innovative, commercially successful product. In this study, we analyzed 51 innovative, award-winning medical devices against their competition to identify what made those products stand out from the competition. The method was focused on finding engineering-level characteristics that made the products successful and whether the characteristics of success in the medical device industry are similar to those of other industries. We used a set of innovation categories that have been shown to apply to mechanical engineering products. The results show that the most innovative medical devices were innovative in at least three categories. Overall, a majority (greater than 60%) of the award-winning medical devices exhibited enhanced user interactions, with a similar percentage displaying enhanced environmental interactions and architectural changes, compared with only 20% of devices offering an additional function. We conclude that designers of innovative medical devices need better design methods that extend beyond the functionality of the products.
Polymer Rigidity Control for Endoscopic Shaft Guide ”PlastoLock”: A Feasibility Study
Authors: Loeve Arjo , Bosma Johannes H. , Breedveld Paul , Dodou Dimitra , Dankelman Jenny
Published: August 2010

Flexible endoscopes are used for diagnostic and therapeutic interventions in the human body for their ability to be advanced through tortuous trajectories. However, this very same property causes difficulties as well. For example, during surgery a rigid shaft would be more beneficial since it provides more stability and allows for better surgical accuracy. In order to keep the flexibility and obtain rigidity when needed, a shaft guide with controllable rigidity could be used. In this article we introduce the PlastoLock concept, which uses thermoplastics that are reversibly switched from rigid to compliant by changing their temperature from 5 °C to 43 °C. These materials are used to make a shaft that can be rendered flexible to follow the flexible endoscope and rigid to guide it. To find polymers that are suitable for the PlastoLock concept an extensive database and internet search was performed. The results suggest that many suitable materials are available or can be custom synthesized to meet the requirements. The thermoplastic polymer Purasorb® PLC 7015 was obtained and a dynamic mechanical analysis showed that it is suitable for the PlastoLock concept. A simple production test indicated that this material is suitable for prototyping by molding. Overall, the results in this article show that the PlastoLock concept can offer simple, scalable solutions for medical situations that desire stiffness at one instance and flexibility at another.
A Breakthrough From an Unexpected Corner: Turning an Old Technology Into a Paradigm Shift
Authors: Winzker Dietmar , Pretorius Leon
Published: August 2010

This paper elucidates the history, the design philosophy of innovation and the transformation of an old process-technology into a breakthrough, evidence-based therapy with international medical acceptance, verification of effectiveness as well as the strategic business model employed. Pulsed electromagnetic field therapy (PEMFT) was not medically acceptable and was, until recently in disrepute, professionally speaking. A revisiting of the technology with reference to the partially inconsistent, yet positive anecdotal results obtained, gave rise to in-depth analysis as well as scientific research conducted by independent institutions which resulted in the identification of the key physiological parameters which in turn could be related to a significant improvement of pathologies. By applying and promoting a systems approach as practiced by engineers who were involved in complex multidisciplinary projects for many years, a different perspective on the innovative development of PEMF therapy was established. The innovative process-based therapy working mainly at cellular and self-regulation level was a paradigmatic departure from the indication-based therapy as applied to pharmaceutical therapy. Over the past 10 years exceptional breakthroughs of the nonsymptom based therapy have been documented through clinical trials, scientific medical investigations and the publication of relevant literature. The turn-around of the old and insufficiently understood technology into an innovative, significant, scientific breakthrough-technology, requires a paradigm shift which is analogous to working in a different culture. It is surmised that this paradigm shift will strongly influence medical schools and practitioners over the next 5–10 years. The authors, as “outsiders” to the medical discipline, bring an engineering perspective to bear on the development of innovative but system-integrated medical devices which can promote the medical device industry and bring system engineering approaches into the realm of medical technology and therapy. Both authors have presented a number of papers at international conferences individually and in partnership on the topics of strategic business leadership and business transformation, system thinking and holistic management model development for high technology companies.
Optical Coherence Tomography Characterization of Balloon Diameter and Wall Thickness
Authors: Azarnoush Hamed , Bourezak Rafik , Vergnole Sebastien , Lamouche Guy , Boulet Benoit
Published: August 2010

An intravascular optical coherence tomography probe is integrated in a computerized angioplasty balloon deployment system. The resulting setup can be useful in many applications. In this paper, based on the acquired intraluminal images, we achieve a detailed assessment of the diameter and wall thickness of the inflated balloon at different pressures. Such analysis is helpful in testing the balloon quality, in assessing deformation model, or in validating new balloon designs.
An Articulating Tool for Endoscopic Screw Delivery
Authors: Petrzelka Joseph , Chatzigeorgiou Dimitris , Menon Manas C. , Lustrino Michelle E. , Stefanov-Wagner Clara J. , Slocum Alexander H. , Agarwal Suresh K.
Published: August 2010

This paper describes the development of an articulating endoscopic screw driver that can be used to place screws in osteosynthetic plates during thoracoscopic surgery. The device is small enough to be used with a 12 mm trocar sleeve and transmits sufficient torque to fully secure bone screws. The articulating joint enables correct screw alignment at obtuse angles of up to 60 deg from the tool axis. A novel articulating joint is presented, wherein a flexible shaft both transmits torque and actuates the joint; antagonist force is provided by a superelastic spring. Screws are secured against the driver blade during insertion and with a retention mechanism that can passively release the screw when it has been securely placed in the bone. The prototype has been fitted with a blade compatible with 2.0 mm and 2.3 mm self-drilling screws although a different driver blade or drill bit can easily be attached. Efficacy of the tool is demonstrated by securing an osteosynthetic plate to a rib in a mock surgical setup. This tool enables minimally invasive, thoracoscopic rib fixation.
Design of Pressurized Metered Dose Inhalers Modeling of Internal Flow and Atomization
Authors: Versteeg Henk , Shaik Abdul Qaiyum
Published: August 2010

Pressurized metered-dose inhalers (pMDIs) have been the most effective therapeutic treatment for controlling lung diseases such as asthma and COPD. The flow through a two-orifice system of pMDI is very complex and poorly understood. Previous experimental work has shown that metastability may play a significant role in determining the flow conditions inside pMDIs. In this paper, we present the findings of a homogeneous equilibrium model with those of a delayed equilibrium model (DEM) accounting for propellant metastability. These results are compared with the available experimental and numerical predictions Further, the DEM was applied with HFA propellants R134A and R227, and the results were compared with traditional propellant R12.
A Testbed for Multilumen Steerable Needle Experiments
Authors: Das Jadav , Rucker D. Caleb , Webster Robert J.
Published: August 2010

Steerable needles offer the potential to turn corners during insertion, thereby avoiding obstacles, reducing tip placement error and enabling a less invasive access to challenging anatomical locations. In this paper, we describe an experimental testbed designed to facilitate experiments with several popular steering mechanisms. One such mechanism makes use of asymmetric forces generated by a bevel tip for actuating steerable needles, and another uses multiple concentric precurved tubes that can change the needle shaft shape by rotating within one another and extending telescopically. The experimental testbed consists of a new robotic actuation unit for controlling axial rotation and linear translation of multiple tubes. It also includes stereo-optical cameras and a magnetic tracking system for the feedback of needle shape and tip location. The setup can be used in future work for model validation and closed-loop feedback control of steerable needles and cannulae.
Feasibility and Design of a Low-Cost Prosthetic Knee Joint Using a Compliant Member for Stance-Phase Control
Authors: Harrison Daniel G. , Andrysek Jan , Cleghorn William L.
Published: August 2010

This paper is concerned with the feasibility and design of a low-cost prosthetic knee joint that uses a compliant member for stance-phase control. A mechanical locking mechanism was used in conjunction with a compliant control axis to achieve automatic stance-phase locking. The concept was developed with the aid of computer-aided engineering software and was validated through the fabrication and testing of a simplified prototype made of an injection moldable polymer. A prosthetic knee joint was then designed, incorporating the compliant member concept. After modeling, fabrication, and laboratory testing, a pilot study was conducted in a clinical setting. A simple gait analysis showed asymmetric gait patterns that demonstrated the need for improved swing-phase control and damping, while qualitative feedback indicated the desire to reduce the noise produced by the knee. The knee provided the automatic stance-phase control for which it was designed and shows significant potential to evolve into a highly functioning, low-cost knee.
Infrared Thermal Imaging-Based Automatic Tumor Tracking During Breast Cancer Radiotherapy
Authors: Zhou Debao , Bai Dr. Jing
Published: August 2010

In the United States, about one out of eight women has been diagnosed with breast cancer. This year, about 200,000 new cases of invasive breast cancer are expected to be diagnosed in the U.S. Radiation therapy is a standard procedure to treat breast cancer. During the radiation therapy, the high energy penetration radiation is used to destroy the cancer cells. However, radiation damages normal cells as well, and any movement of the patient’s body during the treatment will expose more normal cells to the radiation. In order to reduce the unnecessary radiation to normal cells, a real-time infrared (IR) thermal image-based tumor tracking system for breast cancer radiotherapy is developed in this research. In the system, the real-time feedback of breast tumor locations consists of the images taken by an IR thermal camera system. A serial six-degree-of-freedom manipulator is used to realize the real-time position and orientation adjustment of the X-ray radiation head (i.e., a linear accelerator). There are several advantages of this system: (i) IR radiation is not harmful to human body. (ii) Quick image acquisition can be achieved. Faster control speed can lead to less radiation on normal cells through the quick response of the system if the radiation head is away from the target by some reason. All these will increase the radiation effectiveness. With the reduced radiation to the patients, the therapy can be safer and more protective than the traditional methods.
Finite Element Modeling of Inverted (Inside Out) Soft Contact Lenses
Authors: Conrad Fabian , Ehrmann Klaus , Choo Jennifer D. , Holden Brien A.
Published: August 2010

Soft contact lenses (SCLs) can be inserted inside out with consequences for optical, mechanical, and on-eye comfort performance. Wearing lenses inside out may also cause corneal deformation especially with silicone hydrogel lenses. Since inside out insertion of SCLs cannot always be avoided, it is important to study their effects, and it may even be feasible to use these inside out forces to reshape the cornea. To study these possible scenarios, a finite element (FE) based model capable of simulating the inversion of soft contact lenses was developed and validated by comparing modeled results with laboratory measurements of lenses in right side and inside out conformations. In this study, the front surface contour of five SCLs (four commercially available and one custom design) was determined using a profile projector. The lenses were turned inside out, and the front surface contour was remeasured. The thickness profile obtained by a profilometer was “added” to the front surface shape in both orientations to derive the back surface shape. A detailed nonlinear 2D axisymmetric FE model of each lens in its right side in state was created, and the lens was inverted by applying a rigid probe. The modeled and measured inverted lens shapes were compared with respect to parameter alterations (sagittal depth (sag) and diameter) and overall geometry changes using a Procrustes analysis. Measured and modeled results revealed very substantial geometry changes when turning the lens inside out; however, the maximum sagittal deviation between measured and modeled inside out lens shapes was less than 0.05 mm over the central 6 mm half chord. Overall, the modeled results matched the inverted geometries for both parameter changes as well as overall shape changes. The developed FE model is able to predict the geometry of soft contact lenses when they are inverted.
Design of a Novel Device to Provide Assured Seating of Bone Implanted Fiducial Markers
Authors: Mitchell Jason , Labadie Robert F. , Fitzpatrick J. Michael
Published: August 2010

Microstereotactic frames are a subset of stereotactic frames. They are smaller than traditional frames, and they employ small discrete anchors that are screwed into a patient’s bony anatomy, typically the skull. These anchors provide points of attachment for the frame and also serve as markers that provide a bridge between image space and physical space. Both these markers and the anatomy of interest are imaged in a CT or MRI scanner, and their positions are established relative to one another. The microstereotactic frame is then custom made so that, when it is attached to the anchors, it will guide a surgical instrument to an anatomical target. These frames offer advantages over stereotactic frames, including increased targeting accuracy and patient comfort. Firm placement of these anchors is critical as any movement will cause errors in the imaging localization, frame design, or frame attachment. Anchor placement is complicated by the variation in bone density and by the obscuring tissue and bleeding that make visual confirmation of seating very difficult. A novel device called the PosiSeat™ is presented that provides assured seating for bone-implanted anchors.
A New Method in the Design of a Dynamic Pedorthosis for Children With Residual Clubfoot
Authors: Rizza Robert , Liu XueCheng , Thometz John , Lyon Roger , Tassone Channing
Published: August 2010

Clubfoot is a common pediatric orthopaedic deformity. Despite the popularity of Ponseti’s method and night splints such as the Denis–Browne method, there is still an 11–47% rate of deformity relapse reported in the literature. The technique to make traditional orthotics is dependent on a nonweight-bearing casting or foot imprint. These splints outdate clinical treatment trends and only apply to patients who are of nonwalking age. This study shows that a new procedure utilizing computer aided design and the finite element method can be employed to develop a customized weight-bearing dynamic orthotic. In addition, the plantar pressure distribution and the trajectory of the center of this pressure distribution are used to design the orthotic. It is shown that the trajectory of the center of pressure, traditionally used in gait analysis, can be used not only to quantify the severity of the foot deformity but to design a custom orthotic as well. Also, the new procedure allows the custom orthotic to be designed and analyzed within a day. The new orthotic design is composed of soft foam interior layers and a polymer supportive exterior layer. It is proved that rapid prototyping technologies employing selective laser sintering can be used to construct these layers to produce a custom orthotic within a 24 h time frame.
Design and Preliminary Evaluation of a Novel Brace for Boutonniere Deformity
Authors: Rentschler Mark E. , Macdonald Scott A.
Published: August 2010

Boutonniere deformities are a common injury to the extensor mechanism of the finger. The deformity results in fixed contraction in the middle finger joint and is severely debilitating to functionality. Due to the complexity of the extensor mechanism, surgical repair is difficult, which usually requires multiple procedures, and in some cases is unsuccessful. Nonsurgical treatment of the deformity has not dramatically improved in many years and usually requires long-term use of braces and physical therapy. This work is focused on design and preliminary evaluation of an improved boutonniere brace to correct the deformity with emphasis on lower costs, integrating therapeutic techniques such as heat and motion to increase blood flow and patient comfort. A review of the current state of the art is presented along with the design approach used to develop an improved device. Experimental test results are also presented. This work demonstrates a new device and approach for treatment of boutonniere deformities that may translate to treatment of other conditions such as arthritis.
Crystallization, metastable phases, and demixing in a hafnia-titania nanolaminate annealed at high temperature
Authors: Cisneros-Morales Massiel Cristina , Aita Carolyn Rubin
Published: September 2010

Nanolaminate films with a nominal 5 nm HfO2–4 nm TiO2 bilayer architecture are sputter deposited on unheated fused silica and Au-coated glass substrates. Films on fused silica are postdeposition annealed from 573 to 1273 K and characterized by x-ray diffraction, scanning electron microscopy, Raman microscopy, and UV-visible-near IR spectrophotometry. The films show weak but progressive crystallization into orthorhombic (o) HfTiO4 when annealed up to 973 K. o-HfTiO4 is expected to form under bulk thermodynamic equilibrium conditions in the case of complete mixing of the bilayer components. Annealing above 973 K produces a crystallization sequence that is not predicted by bulk thermodynamics, ultimately involving o-HfTiO4 demixing to form monoclinic HfO2 doped with Ti and rutile TiO2 doped with Hf. These phases have a higher atomic density than o-HfTiO4 and segregate into discrete mesoscopic features. The authors propose that o-HfTiO4 demixing into higher density phases is a mechanism for thermal stress relief at high temperature. Demixing results in a major loss of optical transparency in the visible and ultraviolet spectral regions.
Effect of process conditions on the microstructural formation of dc reactively sputter deposited AlN
Authors: Ekpe Samuel D. , Jimenez Francisco J. , Dew Steven K.
Published: September 2010

Thin film aluminum nitride (AlN), because of its attractive properties, is a material with many applications. Its microstructure and hence properties are greatly influenced by the deposition process conditions. In this work, AlN was reactively deposited in a dc magnetron sputtering system at different proportions of nitrogen in the process gas mixture and at different process conditions. The microstructure and composition of the films were analyzed using x-ray diffraction data, energy dispersive spectroscopy, and scanning electron microscopy. Results show that for a process gas pressure of 0.67 Pa, a magnetron power of 100 W, and a substrate-target distance of 10 cm, a near stoichiometeric AlN can be prepared at nitrogen proportions as low as 20%. At these process conditions, (002) was the preferred crystal orientation. Dense fibrous structures were obtained, especially at low deposition rates with high proportions of nitrogen. Increase in magnetron power and decrease in distance result in a more porous structure. High kinetic energies (average) of the sputtered Al particles and high deposition rates tend to favor AlN(101) formation, while low kinetic energies of the Al particles and low deposition rates generally favor more of the AlN(100) formation.
X-ray photoemission spectroscopy of Sr2FeMoO6 film stoichiometry and valence state
Authors: Rutkowski M. , Hauser A. J. , Yang F. Y. , Ricciardo R. , Meyer T. , Woodward P. M. , Holcombe A , Morris P. A. , Brillson L. J.
Published: September 2010

The authors have used a combination of monochromatized x-ray photoemission spectroscopy and Rutherford backscattering spectrometry to develop a protocol for determining bulk film stoichiometry and charge state of Sr2FeMoO6 epitaxial films These studies identify an optimum ion sputtering process for removing surface contaminants while avoiding preferential sputtering of film constituents or alteration of their characteristic valence states. For Sr2FeMoO6, low energy (500 eV), glancing incidence Ar+ sputtering for short (tens of seconds) periods is successful in achieving stoichiometric compositions and characteristic charge states of the film constituents. The evolution of composition and valence state with sputtering provides a guide to measure stoichiometry and charge state of complex oxide thin films in general.
Formation of nanoscale clusters during the initial stages of CaF2 growth on miscut Si(111)
Authors: Kidd T. E. , Davis S. , Klein D. , Matveeva V. , Sifeeva V. , Becker N. G.
Published: September 2010

The initial stages of high temperature CaF2 growth by molecular beam epitaxy on Si(111) substrates with a 3° miscut were characterized using atomic force microscopy and low energy electron diffraction. At a growth temperature of 750 °C, electron diffraction measurements showed that the surface retained the (3×1) surface reconstruction up to a deposition thickness of at least 1.2 nm. The overall topography of the surface was defined by atomically flat terraces decorated with a large number of clusters. These clusters were confined to step edges and were typically 10–20 nm tall. The clusters appear to nucleate at the top of step edges and then grow in size until they extend across the step onto the neighboring terrace below. These results indicate that in this growth regime, the CaF2 molecules diffuse across terraces to aggregate into relatively large nanostructures after the formation of a thin wetting layer. The unusually rounded features and large heights seen in these clusters appear to arise from the topography of substrate terraces.
Low-energy ion bombardment to tailor the interfacial and mechanical properties of polycrystalline 3C-silicon carbide
Authors: Liu Fang , Li Carolina H. , Pisano Albert P. , Carraro Carlo , Maboudian Roya
Published: September 2010

Low-energy Ar+ ion bombardment of polycrystalline 3C-silicon carbide (poly-SiC) films is found to be a promising surface modification method to tailor the mechanical and interfacial properties of poly-SiC. The film average stress decreases as the ion energy and the bombardment time increase. Furthermore, this treatment is found to change the strain gradient of the films from positive to negative values. The observed changes in stress and strain gradient are explained by ion peening and thermal spikes models. In addition, the poly-SiC films show a significant enhancement in corrosion resistance by this treatment, which is attributed to a reduction in surface energy and to an increase in the compressive stress in the near-surface region.
A New Mixing Diagnostic and Gulf Oil Spill Movement
Authors: Mezić Igor , Loire S. , Fonoberov Vladimir A. , Hogan P.
Published: September 2010

Mixing Chaos

Modeling the future movement of chaotic fluids is the basis for predicting the weather and ocean currents. Usually parcels of fluid are traced and geometrical and statistical approaches incorporate parameters for mixing and chaos, as well as the resulting uncertainty.

Mezić
et al.

(p.
486
, published online 2 September; see the Perspective by

Thiffeault

) adapted this approach to consider different mixing and stretching regimes to improve predictions. As a test, they simulated and successfully predicted the spread of oil patches from the Deepwater Horizon oil spill in a model for the Gulf of Mexico.
ABC Transporters Involved in Export of Cell Surface Glycoconjugates
Authors: Cuthbertson Leslie , Kos Veronica , Whitfield Chris
Published: August 2010

Complex glycoconjugates play critical roles in the biology of microorganisms. Despite the remarkable diversity in glycan structures and the bacteria that produce them, conserved themes are evident in the biosynthesis-export pathways. One of the primary pathways involves representatives of the ATP-binding cassette (ABC) transporter superfamily. These proteins are responsible for the export of a wide variety of cell surface oligo- and polysaccharides in both Gram-positive and Gram-negative bacteria. Recent investigations of the structure and function of ABC transporters involved in the export of lipopolysaccharide O antigens have revealed two fundamentally different strategies for coupling glycan polymerization to export. These mechanisms are distinguished by the presence (or absence) of characteristic nonreducing terminal modifications on the export substrates, which serve as chain termination and/or export signals, and by the presence (or absence) of a discrete substrate-binding domain in the nucleotide-binding domain polypeptide of the ABC transporter. A bioinformatic survey examining ABC exporters from known oligo- and polysaccharide biosynthesis loci identifies conserved nucleotide-binding domain protein families that correlate well with themes in the structures and assembly of glycans. The familial relationships among the ABC exporters generate hypotheses concerning the biosynthesis of structurally diverse oligo- and polysaccharides, which play important roles in the biology of bacteria with different lifestyles.
Origins and Evolution of Antibiotic Resistance
Authors: Davies Julian , Davies Dorothy
Published: August 2010

Antibiotics have always been considered one of the wonder discoveries of the 20th century. This is true, but the real wonder is the rise of antibiotic resistance in hospitals, communities, and the environment concomitant with their use. The extraordinary genetic capacities of microbes have benefitted from man's overuse of antibiotics to exploit every source of resistance genes and every means of horizontal gene transmission to develop multiple mechanisms of resistance for each and every antibiotic introduced into practice clinically, agriculturally, or otherwise. This review presents the salient aspects of antibiotic resistance development over the past half-century, with the oft-restated conclusion that it is time to act. To achieve complete restitution of therapeutic applications of antibiotics, there is a need for more information on the role of environmental microbiomes in the rise of antibiotic resistance. In particular, creative approaches to the discovery of novel antibiotics and their expedited and controlled introduction to therapy are obligatory.
Development and application of an empirical multifrequency method for backscatter classification
Authors: De Robertis Alex , McKelvey Denise R. , Ressler Patrick H.
Published: September 2010

We evaluated the feasibility of identifying major acoustic scatters in North Pacific ecosystems based on empirical measurements of relative frequency response. Acoustic measurements in areas where trawl catches were dominated by single taxa indicated that it might be possible to discern among key groups of scatterers such as fish with gas-filled swimbladders, euphausiids, myctophids, and jellyfish. To establish if walleye pollock ( Theragra chalcogramma ), a key species in the ecosystem, can be separated reliably from other groups under prevailing conditions, we developed a method based on the normal deviate (or Z score) to identify backscatter consistent with the pollock relative frequency response. We evaluated the performance of the method by comparing it with the traditional method of species identification (i.e., directed trawl catches and subjective interpretation of echograms) during five large-scale acoustic surveys of the eastern Bering Sea. Pollock abundance estimates employing the multifrequency method were highly correlated with those using the traditional method, which indicates that the multifrequency method performs well in this situation. In this environment, multifrequency methods will allow more inferences to be drawn when direct sampling of organisms is limited and will also complement existing abundance surveys by improving species classification and providing information about key nontarget species.
Equilibrium studies of triphenyltin(IV) complexes with glycine, glycyl-glycine, and glycyl-glycyl-glycine in different aqueous solutions of ethanol
Authors: Jabbari Morteza , Gharib Farrokh
Published: September 2010

The protonation equilibria of glycine (gly), glycyl-glycine (gly-gly), and glycyl-glycyl-glycine (gly-gly-gly) and their formation constants with triphenyltin(IV) chloride were studied over a wide pH range (pH 1–11), using a combination of spectrophotometric and potentiometric methods at constant temperature (25 °C), different ethanol–water mixtures (50%–80%, v/v), and constant ionic strength (0.1 mol dm–3 NaClO4). Least-squares regression calculations are consistent with the formation of ph3SnHL+, ph3SnL, and ph3SnH–1L– complex species, where L– represents the fully dissociated form of each ligand. The stability constant of the formed complexes in different media were analyzed in terms of Kamlet, Abboud, and Taft (KAT) parameters. Single-parameter correlations of the stability constants versus α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity), and for π* (dipolarity/polarizability) are relatively poor in all solutions, but multi-parameter correlations represent significant improvements with regard to the single- and dual-parameter models. Linear correlation is observed when the experimental logβxyz values are plotted versus the calculated ones, while all the KAT parameters are considered. Also, the stability constant values of the formed complexes are determined in zero percent of organic solvent using the Yasuda–Shedlovsky extrapolation approach. Finally, the results are discussed in terms of the effect of solvent on complexation.