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1

Distal interlocking screws with a modular revision stem for revision total hip arthroplasty in severe bone defects.  

PubMed

A prospective study of 15 patients was designed to examine whether the modular cementless revision stem (Revitan curved; Zimmer GmbH, Winterthur, Switzerland) is suitable for stem revisions with a defective isthmus when distal interlocking screws are also used for fixation. During a follow-up period of 35.4 +/- 11.4 months (24-70 months), there was one stem loosening with screw breakage in a case of a stem that was too thin. According to Engh et al, bony ingrowth fixation of the stem occurred in 12 cases and stable fibrous fixation in 2 cases. The Harris Hip Score rose continuously from 44.7 +/- 12.9 points preoperatively to 75 +/- 10 points at 24 months. This concept of additional stem fixation with distal interlocking screws represents a useful treatment option for revision arthroplasty in rare cases of a defective isthmus. PMID:19577879

Fink, Bernd; Grossmann, Alexandra; Fuerst, Martin

2009-07-04

2

Stress analysis of the distal locking screws for femoral interlocking nailing  

Microsoft Academic Search

In femoral locked nailing, the distal locking screws are vulnerable to mechanical failure. Biomechanical studies have shown that the stress on these screws is substantially affected by the fit of the nail in the medullary canal. In this study, a “closed form” mathematical model based on elastic beam-column theory was developed to investigate how the nail–cortical contact, which was simulated

Jinn Lin; Son-Jyh Lin; Po-Quang Chen; Shu-Hua Yang

2001-01-01

3

Optimal alignment of the distal screws in the tibial nailing  

Microsoft Academic Search

Serious stress concentration around the regions near the distal nail?holes and the distal screws in conventional tibial interlocking nails has been reported in previous studies. A three?dimensional finite element model was used to study the interlocking nail, the fractured tibia and the locking screws. The distal screws were inserted into the tibial nail in different configurations. We found that the

2003-01-01

4

Reinforcing the role of the conventional C-arm - a novel method for simplified distal interlocking  

PubMed Central

Background The common practice for insertion of distal locking screws of intramedullary nails is a freehand technique under fluoroscopic control. The process is technically demanding, time-consuming and afflicted to considerable radiation exposure of the patient and the surgical personnel. A new concept is introduced utilizing information from within conventional radiographic images to help accurately guide the surgeon to place the interlocking bolt into the interlocking hole. The newly developed technique was compared to conventional freehand in an operating room (OR) like setting on human cadaveric lower legs in terms of operating time and radiation exposure. Methods The proposed concept (guided freehand), generally based on the freehand gold standard, additionally guides the surgeon by means of visible landmarks projected into the C-arm image. A computer program plans the correct drilling trajectory by processing the lens-shaped hole projections of the interlocking holes from a single image. Holes can be drilled by visually aligning the drill to the planned trajectory. Besides a conventional C-arm, no additional tracking or navigation equipment is required. Ten fresh frozen human below-knee specimens were instrumented with an Expert Tibial Nail (Synthes GmbH, Switzerland). The implants were distally locked by performing the newly proposed technique as well as the conventional freehand technique on each specimen. An orthopedic resident surgeon inserted four distal screws per procedure. Operating time, number of images and radiation time were recorded and statistically compared between interlocking techniques using non-parametric tests. Results A 58% reduction in number of taken images per screw was found for the guided freehand technique (7.4 ± 3.4) (mean ± SD) compared to the freehand technique (17.6 ± 10.3) (p < 0.001). Total radiation time (all 4 screws) was 55% lower for the guided freehand technique compared to conventional freehand (p = 0.001). Operating time per screw (from first shot to screw tightened) was on average 22% reduced by guided freehand (p = 0.018). Conclusions In an experimental setting, the newly developed guided freehand technique for distal interlocking has proven to markedly reduce radiation exposure when compared to the conventional freehand technique. The method utilizes established clinical workflows and does not require cost intensive add-on devices or extensive training. The underlying principle carries potential to assist implant positioning in numerous other applications within orthopedics and trauma from screw insertions to placement of plates, nails or prostheses.

2012-01-01

5

Intramedullary tibial nailing in distal third tibial fractures: distal locking screws and fracture non-union.  

PubMed

Distal third tibial fractures are prone to non-union following tibial nail insertion. The purpose of this study was to assess the union of distal third tibial fractures in patients who have undergone intra-medullary (IM) tibial nailing with one versus two distal locking screws. Sixty-five patients who had intramedullary tibial nail fixation were retrospectively analysed. Our results showed that 80% of non-unions in distal third fractures had only one distal locking screw compared to 20% who had two distal locking screws. This is statistically significant (p<0.01). We therefore conclude that two distal locking screws are essential for distal third fractures. PMID:17410364

Mohammed, Aso; Saravanan, Ramaswamy; Zammit, Jason; King, Richard

2007-04-05

6

Biomechanics of the interlocking nail  

Microsoft Academic Search

Conventional interlocking nails for the femur use an inclined proximal interlocking screw; the AO\\/ASIF universal interlocking nail utilizes a transverse interlocking screw which is anchored in cortical bone. The transverse position of the screw allows one to employ the nail for either the right or left side. The yield strength of the thinner diameter transverse screw, (thread 4.5 mm, core

C. Kinast; R. Frigg; S. M. Perren

1990-01-01

7

Distal interphalangeal joint arthrodesis of the lesser toes using the Barouk screw  

Microsoft Academic Search

A new method of fixation for distal interphalangeal (DIP) joint arthrodesis of the lesser toes using the Barouk screw has been used in five toes in five patients. The techniques as well as the advantages are discussed in this article. Deep infection, loss of fixation and failure of fusion were not evident in any of the cases.The Barouk screw fixation

S Jones; F Ali; A Genever; M. J Flowers; S. H Bostock

2003-01-01

8

Use of the intraosseous screw for unilateral upper molar distalization and found well balanced occlusion  

PubMed Central

Background The aim of this study was to present a temporary anchorage device with intraosseous screw for unilateral molar distalization to make a space for the impacted premolar and to found well balanced occlusion in a case. Case presentation A 13-year-old male who have an impacted premolar is presented with skeletal Class I and dental Class 2 relationship. The screw was placed and immediately loaded to distalize the left upper first and second molar. The average distalization time to achieve an overcorrected Class I molar relationship was 3.6 months. There was no change in overjet, overbite, or mandibular plane angle measurements. Mild protrusion (0.5 mm) of the upper left central incisor was also recorded. Conclusion Immediately loaded intraosseous screw-supported anchorage unit was successful in achieving sufficient unilateral molar distalization without anchorage loss. This treatment procedure was an alternative treatment to the extraction therapy.

Gelgor, Ibrahim Erhan; Karaman, Ali Ihya; Buyukyilmaz, Tamer

2006-01-01

9

The use of intraosseous screw for upper molar distalization: a case report.  

PubMed

The use of implants has made a major change in orthodontic treatment mechanics. They have replaced conventional unaesthetic and compliance dependent extraoral appliances with well accepted intraoral mechanics. Implants can be used in molar and canine distalization, intrusion and in extraoral force applications. In the present case report, treatment of a case using an intermaxillary fixation screw (IMF) will be presented. The treatment results will be evaluated using pretreatment, post distalization and post treatment cephalometric radiographs and dental casts. PMID:19212521

Polat-Ozsoy, Omür

2008-04-01

10

The Use of Intraosseous Screw for Upper Molar Distalization: A Case Report  

PubMed Central

The use of implants has made a major change in orthodontic treatment mechanics. They have replaced conventional unaesthetic and compliance dependent extraoral appliances with well accepted intraoral mechanics. Implants can be used in molar and canine distalization, intrusion and in extraoral force applications. In the present case report, treatment of a case using an intermaxillary fixation screw (IMF) will be presented. The treatment results will be evaluated using pretreatment, post distalization and post treatment cephalometric radiographs and dental casts.

Polat-Ozsoy, Omur

2008-01-01

11

Interlocking femoral components for revision arthroplasty with allografts.  

PubMed

The use of interlocking screws has been advocated to fix major proximal femoral allografts to femoral prostheses. This study examines the effect of interlocking screws on strength of the component. Model femoral components were tested in axial compression. Drilling one hole diagonally (lateral to medial), drilling one hole anterior to posterior, or drilling one diagonal hole plus one anterior-to-posterior hole did not significantly decrease failure load compared to controls with no holes. However, two diagonal holes or horizontal, medial-to-lateral holes were weaker. Four cases have been done with proximal femoral allografts fixed to porous-coated femoral components with proximal and distal interlocking screws. Initial results in these cases are good. PMID:2243214

Rodrigo, J J; Martin, R B; Reynolds, H B; Sharkey, N; Zissimos, S

1990-01-01

12

Comparison of bioabsorbable interference screws and posts for distal fixation in anterior cruciate ligament reconstruction.  

PubMed

Comparison of the results of bioabsorbable interference screws and posts for hamstring graft distal fixation in ACL reconstructions are presented. The results of 20 patients with bioabsorbable screws were compared to 22 patients with posts. The assessement was based on Lysholm-Gillquist and Marshall scores and the KT-1000 device. In the study group the points gained were 38.9 in the Lysholm-Gillquist and 12.89 in the Marshall scale. The average KT-1000 difference was 2.46 mm. In the control group the points gained were 32.93 in the Lysholm-Gillquist and 11.47 in the Marshall scale. The average KT-1000 difference was 2.5 mm. There were 14 patients in the study group with interference screw problems; in 2 the implants were removed. (1) There are no differences in outcome using bioabsorbable interference screws and posts for distal fixation of hamstring ACL grafts. (2) The lack of bioabsorbtion with poly L-lactide interference screws is frequent and causes problems. PMID:18064457

Gaweda, Krzysztof; Walawski, Jacek; Weg?owski, Robert; Krzyzanowski, Wojciech

2007-12-07

13

Treatment of displaced distal clavicle fractures with a single cortical screw.  

PubMed

The authors retrospectively evaluated the effects of a single cortical screw in the open reduction and internal fixation of displaced distal clavicle fractures. Fifteen patients without associated acromioclavicular joint dislocation were treated by open reduction and internal fixation with a single cortical screw (4.5-mm diameter, 60-mm length) between 2004 and 2011. Mean follow-up was 39.2 months (range, 13-84 months). Reduction with a fracture gap of less than 1 mm and solid union were achieved in all cases. Delayed superficial infection developed in 1 patient. All other patients had good to excellent final Constant-Murley functional results. PMID:23464937

Lin, Hsi-Hsien; Wang, Chien-Shun; Chen, Cheng-Fong; Chiang, Chao-Ching; Huang, Ching-Kuei; Chen, Wei-Ming; Liu, Chien-Lin

2013-03-01

14

Distal interphalangeal joint arthrodesis in extension using a headless compressive screw.  

PubMed

The aim of this study was to review the clinical outcome and complications in patients who underwent distal interphalangeal joint (DIPJ) fusion in extension using an axial screw with variable thread pitch (Mini Acutrak screw Acumed, LLC, Hillsboro, OR, USA). Thirty-eight cases of DIPJ or thumb IPJ were performed and assessed through patient satisfaction (hand function and pain) and radiographs. The quickDASH scores were assessed at a mean follow up of 8 months (range : 6 to 12 months). Ninety-three per cent of participants reported good or excellent functional outcome, with Quick DASH scores of less than 30. There were five complications noted (one superficial wound infection; two fractures; two screw cut-outs). All cases progressed to radiographic bony union at six months. PMID:23821966

Konan, Sujith; Das, Aditi; Taylor, Emma; Sorene, Elliot

2013-04-01

15

Radiation exposure to the surgeon during closed interlocking intramedullary nailing  

SciTech Connect

During interlocking intramedullary nailing of twenty-five femoral and five tibial fractures, the primary surgeon wore both a universal film badge on the collar of the lead apron and a thermoluminescent dosimeter ring on the dominant hand to quantify the radiation that he or she received. When distal interlocking was performed, the first ring was removed and a second ring was used so that a separate recording could be made for this portion of the procedure. At the conclusion of the study, all of the recorded doses of radiation were averaged. The average amount of radiation to the head and neck during the entire procedure was 7.0 millirems of deep exposure and 8.0 millirems of shallow exposure. The average dose of radiation to the dominant hand during insertion of the intramedullary nail and the proximal interlocking screw was 13.0 millirems, while the average amount during insertion of the distal interlocking nail was 12.0 millirems. Both of these averages are well within the government guidelines for allowable exposure to radiation during one-quarter (three months) of a year. Precautions that are to be observed during this procedure are recommended.

Levin, P.E.; Schoen, R.W. Jr.; Browner, B.D.

1987-06-01

16

The retrograde nail for distal femoral fractures in the elderly: high failure rate of the condyle screw and nut.  

PubMed

Displaced distal femoral fractures in elderly patients benefit from surgical fixation. We describe the use of a retrograde femoral nail to treat these fractures. The implant has a special condyle screw and nut that allows for manual compression of the fracture when there is an additional inter-condylar split. We present our results when using this implant to treat 16 patients over a 13-month period. The mean patient age was 78 years (range, 65-96 years). All 16 patients were available at the time of final follow up and proceeded to union at an average time of 11 weeks (range, 10-14 weeks). Twenty-six condyle screw and nuts were used. Ten out of 26 condyle screws in 10 out of 16 patients failed by disengaging at a mean time of 10 weeks (range, 8-12 weeks). Our union rate was unaffected by the nut and bolt disengaging. This would suggest that the condylar compression generated by the nut and bolt may not be critical for union. PMID:16499912

Singh, S K; El-Gendy, K A; Chikkamuniyappa, C; Houshian, S

2006-02-24

17

A new radiological method to detect dorsally penetrating screws when using volar locking plates in distal radial fractures. The dorsal horizon view.  

PubMed

Penetration of the dorsal screw when treating distal radius fractures with volar locking plates is an avoidable complication that causes lesions of the extensor tendon in between 2% and 6% of patients. We examined axial fluoroscopic views of the distal end of the radius to observe small amounts of dorsal screw penetration, and determined the ideal angle of inclination of the x-ray beam to the forearm when making this radiological view. Six volar locking plates were inserted at the wrists of cadavers. The actual screw length was measured under direct vision through a dorsal approach to the distal radius. Axial radiographs were performed for different angles of inclination of the forearm at the elbow. Comparing axial radiological measurements and real screw length, a statistically significant correlation could be demonstrated at an angle of inclination between 5° and 20°. The ideal angle of inclination required to minimise the risk of implanting over-long screws in a dorsal horizon radiological view is 15°. PMID:23908427

Haug, L C; Glodny, B; Deml, C; Lutz, M; Attal, R

2013-08-01

18

Bioabsorbable interference screw fixation of distal biceps ruptures through a single anterior incision: a single-surgeon case series and review of the literature  

Microsoft Academic Search

Introduction  We present a single-surgeon series of 14 acute ruptured distal biceps tendons repaired using a biotenodesis screw through\\u000a a single anterior incision.\\u000a \\u000a \\u000a \\u000a \\u000a Patients  The demographics of this population reveal a typical injury pattern and reflect the preponderance of distal biceps ruptures\\u000a in the middle aged, active male. Goniometric post-operative assessment of flexion, pronation and supination range demonstrates\\u000a excellent clinical function in

Will G. P. Eardley; Saurabh Odak; T. Simon Adesina; Richard P. Jeavons; Jim L. McVie

2010-01-01

19

Are there any differences in various polyaxial locking systems? A mechanical study of different locking screws in multidirectional angular stable distal radius plates.  

PubMed

Numerous angular stable plates for the distal radius exist, and technically based comparisons of the polyaxial locking interfaces are lacking. The aim of this mechanical study was to investigate three different locking interfaces of angular stable volar plates by cantilever bending: VA-LCP Two-Column Distal Radius Plates 2.4 mm (Synthes® GmbH, Oberdorf, Switzerland), IXOS® P4 (Martin, Tuttlingen, Germany) and VariAX™ (Stryker®, Duisburg, Germany). We assessed the strength of 0°, 5°, 10° and 15° screw locking angles and tested the bending strength from 10° to 5° angles by cyclic loading until breakage. The final setup repeated the above assessments by inclusion of four locking screws. The single screw-plate interfaces of the VA-LCP showed the highest bending moment at an angle of 0° and 5°, the IXOS® P4 at an angle of 10° and 15° and the VariAX™ when changing the insertion angle from 10° into 5°. The strength of polyaxial locking interfaces and mechanism of failure proved to be different among the examined plates. PMID:23449519

Mehling, Isabella; Scheifl, Rebekka; Mehler, Dorothea; Klitscher, Daniela; Hely, Hans; Rommens, Pol M

2013-04-01

20

[Design of an unconventional interlocked hip arthroplasty system (RIMAG) from Mexican femoral measurement].  

PubMed

The need in resolving massive bone losses in hip region caused by tumors, infections, trauma or failed arthroplasties in 17 years of the Bone Tumors Department of the National Rehabilitation Institute, Mexico City, and data obtained from different studies: 1) Biomechanic study of an unconventional hip arthroplasty system, 2) Tridimensional model of a human femur by the finite element method, 3) Biomechanical analysis of a system bone-implant for reconstruction of the proximal third of the femur by the finite element method, 4) Incidence of tumor and pseudotumor bone and soft tissue lesions of the hip, generated the project of designing an unconventional interlocked hip arthroplasty system for femur reconstruction. Two processes were done for adequate manufacturing and dimensioning: Anthropomorphometric study of Mexican femora; 2) Design of an unconventional hip arthroplasty system with the following characteristics: first, the arthroplasty system is constituted by an intramedullar stem, is fixated to femur with interlocking screws, this fixation method was inspired from the design of intramedullar nails of Dr. Fernando Colchero Rosas. The system has a second fixation system in the femur cut region, resolved by a fenestrated support introduced in the cortical wall. Once data was processed, the need for manufacturing 2 models was determined: 1) One for the proximal 11 cm of the femur and 2) other for the 12 distal cm. The height of interlocking screws, 2 models of intracortical proximal support (one fixated and one fixable with an expansible screw), were designed. Diameter, length of the stems, size of spacers and supports were determined for adequate interlocking fixation. We designed the instruments for assembling, impaction and orientation of the arthroplasty system. The system was presented to the Mexican Institute of Industrial Property, at March 15, 1996 and the patent was conceded April 19, 2007 (#245717). PMID:18669306

Martínez, Genaro Rico; Domínguez, Víctor H; Muller, José Antonio; Cedillo, Ernesto A Delgado; Roa, Josué Antonio Miranda; Montoya, Roberto C

21

The intramedullary hip screw.  

PubMed

The intramedullary hip screw is a short intramedullary nail with interlocking screws that can be used to treat subtrochanteric and intertrochanteric femur fractures. This nail, which has the biomechanical advantage of being an intramedullary appliance but can be placed percutaneously, is inserted under fluoroscopic control with the patient on a fracture table. Reaming is not usually necessary. In an initial limited series, complication rates are comparable with existing techniques. Possible future concepts and developments are discussed. PMID:10148378

King, D H; Seligson, D

1993-03-01

22

Use of the radial groove view intra-operatively to prevent damage to the extensor pollicis longus tendon by protruding screws during volar plating of a distal radial fracture.  

PubMed

The aims of this study were to assess the efficacy of a newly designed radiological technique (the radial groove view) for the detection of protrusion of screws in the groove for the extensor pollicis longus tendon (EPL) during plating of distal radial fractures. We also aimed to determine the optimum position of the forearm to obtain this view. We initially analysed the anatomy of the EPL groove by performing three-dimensional CT on 51 normal forearms. The mean horizontal angle of the groove was 17.8° (14° to 23°). We found that the ideal position of the fluoroscopic beam to obtain this view was 20° in the horizontal plane and 5° in the sagittal plane. We then intra-operatively assessed the use of the radial groove view for detecting protrusion of screws in the EPL groove in 93 fractures that were treated by volar plating. A total of 13 protruding screws were detected. They were changed to shorter screws and these patients underwent CT scans of the wrist immediately post-operatively. There remained one screw that was protruding. These findings suggest that the use of the radial groove view intra-operatively is a good method of assessing the possible protrusion of screws into the groove of EPL when plating a fracture of the distal radius. Cite this article: Bone Joint J 2013;95-B:1372-6. PMID:24078534

Lee, S K; Bae, K W; Choy, W S

2013-10-01

23

Selected problems in the bone union of complicated diaphyseal fractures treated with interlocking nail.  

PubMed

Background. This article discusses the effectiveness and technical problems encountered in the union of complications of diaphyseal fractures treated with interlocking nail. Material and methods. Between 2000-2003 we operated 35 patients for pseudoarthrosis (humerus - 6, femur - 13, tibia - 16). In a one-step procedure a plate was removed from the humerus (3 patients) or femur (4 patients), a retrograde interlocking nail was introduced, and spongy grafts were applied. In the remaining patients an external stabilizer or ZESPOL outer plate were first removed; then, after soft tissue healing, an anterograde nail was introduced sequentially using a closed technique. This method of nailing was also used in patients with plates that had previously been removed. The Dencker classification was used to evaluate outcome. Results. We achieved bone union in all cases. We observed intra- and post operative complications in 5 cases: breakage of distal locking screws in 4 patients, and breakage of 1 tibial nail. In closed nailing we encountered major difficulties in passing through the sclerotic edges of pseudoarthrosis, and it also proved extremely difficult to maintain the right direction of the reamer without a guiding wire, which was crucial for a successful operation. Conclusions. Interlocking nailing is an efficacious method of treatment of complications in fracture healing, but in some cases closed nailing of pseudoarthrosis is difficult. PMID:17597691

Kusz, Damian; Dudko, S?awomir; Wojciechowski, Piotr; Guzik, Henryk

2006-08-31

24

Femoral revision using long hydroxyapatite-coated interlocking stem  

Microsoft Academic Search

Introduction  Cementless femoral revision has become increasingly popular because the cementless implants provide the potential for long-term\\u000a biologic implant fixation. The IOTA interlocking femoral stem is a hydroxyapatite-coated stem with the option of interlocking\\u000a the stem distally. The aim of the current study was to evaluate the short-term results of IOTA interlocking stem.\\u000a \\u000a \\u000a \\u000a Materials and methods  We retrospectively reviewed the results of

R. Malhotra; Aman Dua; E. Krishna Kiran; S. Bhan

2008-01-01

25

Alcohol Ignition Interlock Programs  

Microsoft Academic Search

The alcohol ignition interlock is an in-vehicle DWI control device that prevents a car from starting until the operator provides a breath alcohol concentration (BAC) test below a set level, usually .02% (20 mg\\/dl) to .04% (40 mg\\/dl). The first interlock program was begun as a pilot test in California 18 years ago; today all but a few US states,

D. J. BEIRNESS; P. R. MARQUES

2004-01-01

26

Positive Position Interlock Concealment Shutter.  

National Technical Information Service (NTIS)

The patent relates to a positive position interlock concealment shutter for preventing the accidential or intentional actuation of a concealed interlock switch in a microwave oven when its door is in the open position. It comprises a moveable metal plate ...

E. W. Robinson A. V. D. Griek R. W. Kisielewski

1975-01-01

27

Interlocking and Euclidean rhythms  

Microsoft Academic Search

Several operations on Euclidean rhythms based on musical motivations are defined. The operations defined are complementation, alternation, and decomposition. Some mathematical properties are proved for each and the conditions under which a given operation preserves the Euclidean property are examined. Finally, connections are shown to interlocking Euclidean rhythms and tiling canons, and tiling quasi-canons are introduced.

Francisco Gómez-Martín; Perouz Taslakian; Godfried Toussaint

2009-01-01

28

SOFTWARE INTERLOCKS SYSTEM  

Microsoft Academic Search

In the year 2006, a first operational version of a new Java-based Software Interlock System (SIS) was introduced to protect parts of the SPS (Super Proton Synchrotron) complex, mainly CNGS (CERN Neutrinos to Gran Sasso), TI8 (SPS transfer line), and for some areas of the SPS ring. The SIS protects the machine through surveillance and by analyzing the state of

J. Wozniak; V. Baggiolini; D. Garcia Quintas; J. Wenninger

29

Malpractice of Epiphyseal Cannulated Screw Fixation in a Child with Avulsion Fracture of the Tibial Eminence Complicating with Lack of Knee Extension and Distal Femoral Fracture  

Microsoft Academic Search

Avulsion fracture of the tibial eminence is rare in children. This report describes a case of a 9-year -old boy who had been treated previously with an epiphyseal cannulated screw and washer , but without notchplasty , for an avulsion fracture of the tibial eminence. The patient subsequently presented with extension block and knee stif fness. After removal of the

Tsung-Ying Tsai; Jen-Huei Chang; Yu-Kai Yeh; Fu-Kai Chuang; Che-Wei Liu; Shyu-Jye Wang

30

49 CFR 236.820 - Switch, interlocked.  

Code of Federal Regulations, 2011 CFR

... 4 2011-10-01 2011-10-01 false Switch, interlocked. 236.820 Section 236.820...DEVICES, AND APPLIANCES Definitions § 236.820 Switch, interlocked. A switch within the interlocking limits the control of...

2011-10-01

31

49 CFR 236.820 - Switch, interlocked.  

Code of Federal Regulations, 2012 CFR

... 4 2012-10-01 2012-10-01 false Switch, interlocked. 236.820 Section 236.820...DEVICES, AND APPLIANCES Definitions § 236.820 Switch, interlocked. A switch within the interlocking limits the control of...

2012-10-01

32

Split spline screw  

NASA Astrophysics Data System (ADS)

A split spline screw type payload fastener assembly, including three identical male and female type split spline sections, is discussed. The male spline sections are formed on the head of a male type spline driver. Each of the split male type spline sections has an outwardly projecting load baring segment including a convex upper surface which is adapted to engage a complementary concave surface of a female spline receptor in the form of a hollow bolt head. Additionally, the male spline section also includes a horizontal spline releasing segment and a spline tightening segment below each load bearing segment. The spline tightening segment consists of a vertical web of constant thickness. The web has at least one flat vertical wall surface which is designed to contact a generally flat vertically extending wall surface tab of the bolt head. Mutual interlocking and unlocking of the male and female splines results upon clockwise and counter clockwise turning of the driver element.

Vranish, John M.

1993-11-01

33

Biomechanical comparison of axial load between cannulated locking screws and noncannulated cortical locking screws.  

PubMed

The goal of this study was to compare the biomechanical stability of cannulated locking screws and noncannulated cortical locking screws in a periarticular locking plate. Twelve fresh-frozen porcine tibias with a 1-cm gap created distal to the tibial plateau were used to simulate an unstable proximal tibial fracture. All specimens were fixed with a periarticular proximal lateral tibial locking plate and divided into 2 groups based on whether the proximal metaphyseal screw holes of the plate were inserted with either cannulated locking screws or noncannulated cortical locking screws. An axial compressive load was applied to cause failure in each specimen using a materials testing instrument. The axial stiffness and maximum failure strength in axial loading were recorded. Axial stiffness of the constructs using noncannulated cortical locking screw was significantly higher than that of the constructs using cannulated locking screws (P=.006). Axial failure strength of the constructs using noncannulated cortical locking screw was significantly higher than that of the constructs using cannulated locking screws (P=.002). The failure mode observed in all specimens was a permanent screw-bending deformity over the head-shaft junction of proximal metaphyseal screws, irrespective of whether they were cannulated or noncannulated cortical locking screws. Fixation with noncannulated cortical locking screws offered more stability than cannulated locking screws with regard to axial stiffness and failure strength in a porcine model with unstable proximal tibial fractures. PMID:24093710

Yang, Shan-Wei; Kuo, Shyh Ming; Chang, Shwu Jen; Su, Tian-Shiang; Chen, Hsiang-Ho; Renn, Jenn-Huei; Lin, Ting-Sheng

2013-10-01

34

Ignition Interlock Institutes: Promoting the Use of Interlocks and Improvements to Interlock Programs.  

National Technical Information Service (NTIS)

Under a cooperative agreement with NHTSA, MADD held a series of ignition interlock institutes across the United States between August 2009 and October 2012. The institutes were designed to bring teams of people from different States representing various o...

2013-01-01

35

Computer-Aided Safety Interlock Systems.  

National Technical Information Service (NTIS)

Industrial process systems must be locked-out of disastrous operation modes. Here the problem of safety interlock system design is formulated in sequential logic and computer-aided interlock capability developed. (Author)

D. F. Rudd J. R. Rivas

1973-01-01

36

49 CFR 236.772 - Machine, interlocking.  

Code of Federal Regulations, 2012 CFR

...Transportation 4 2012-10-01 2012-10-01 false Machine, interlocking. 236.772 Section 236.772 Transportation...SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.772 Machine, interlocking. An assemblage of manually operated...

2012-10-01

37

49 CFR 236.772 - Machine, interlocking.  

Code of Federal Regulations, 2011 CFR

...Transportation 4 2011-10-01 2011-10-01 false Machine, interlocking. 236.772 Section 236.772 Transportation...SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.772 Machine, interlocking. An assemblage of manually operated...

2011-10-01

38

49 CFR 236.753 - Limits, interlocking.  

Code of Federal Regulations, 2012 CFR

...FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION... Limits, interlocking. The tracks between the opposing home signals of an...

2012-10-01

39

49 CFR 236.753 - Limits, interlocking.  

Code of Federal Regulations, 2011 CFR

...FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION... Limits, interlocking. The tracks between the opposing home signals of an...

2011-10-01

40

2. ENVIRONMENT, FROM SOUTHEAST, SHOWING B&P INTERLOCKING TOWER, AUXILIARY INTERLOCKING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. ENVIRONMENT, FROM SOUTHEAST, SHOWING B&P INTERLOCKING TOWER, AUXILIARY INTERLOCKING BUILDING, AND POWER SUBSTATION - Baltimore & Potomac Interlocking Tower, Adjacent to AMTRAK railroad tracks in block bounded by Howard Street, Jones Falls Expressway, Maryland Avenue & Falls Road, Baltimore, Independent City, MD

41

Strength of an Interlocking FRP Connection.  

National Technical Information Service (NTIS)

The strength of an interlocking fiber-reinforced polymer (FRP) connection was measured in bending, and in-plane and out-of-plane shear. This connection allows the rapid assembly of FRP panels into houses, and can be used in interlocking mode only, or inte...

D. Duthinh K. Bajpai

2001-01-01

42

Case Report: A Technique to Remove a Jammed Locking Screw from a Locking Plate  

PubMed Central

Background Locking titanium plates revolutionized the treatment of osteoporotic and metaphyseal fractures of long bones. However as with any innovation, with time new complications are identified. One of the problems with titanium locking plates is removal of screws, often attributable to cold welding of screw heads into the locking screw holes. Several techniques have been described to overcome this problem. We describe a new easy technique to remove a jammed locking screw in a locking plate that is easily reproducible and suggest an algorithm to determine the method to remove screws from locking plates. Case Description A 57-year-old man underwent removal of a locking titanium plate from the distal femur. Because the screws could not be readily removed, we used a new technique to remove the jammed locking screws. A radial cut was made in the plate into the locking screw hole and wedged with an osteotome. This released the screw head from the locking screw hole. The screw holes were connected with radial cuts and jammed locking screws were removed in a similar fashion. Literature Review Instruments used for removal of locking screws, including conical extraction screws, hollow reamers, extraction bolts, modular devices, and carbide drill bits, have been described. However, these do not always work. Purposes and Clinical Relevance Removing screws from locking titanium plates can be difficult. There is no method of implant removal that can be universally applied. Therefore, this new technique and our algorithm may be used when removing screws from locking titanium plates.

Dunlop, Colin

2010-01-01

43

[Cement distribution in vertebroplasty pedicle screws with different designs].  

PubMed

The effects of deteriorated bone density become particularly apparent in cases where spinal instrumentation is needed. Cement augmentation of pedicle screws for better bone purchase became the subject of many studies, which proved the biomechanical superiority and the increased pullout strength of cement augmented screws. Inadequate, and sometimes dangerous, cement distribution made the need for development of special implants inevitable. Pedicle screws with side openings and a central drill hole allow cement augmentation through the implant and increase not only the screw diameter but also the interfacial strength between the three components (screw-cement-bone). Accordingly cement distribution can be affected by the selection of the side openings (size and position). Screws with conical core and distally situated side openings facilitate the development of uniform cement dough. PMID:20549485

Kafchitsas, K; Geiger, F; Rauschmann, M; Schmidt, S

2010-07-01

44

Interlocking egg-crate type grid assembly  

DOEpatents

Disclosed is an interlocking egg-crate hexagonal grid for supporting a nuclear fuel pin in a hexagonal array. The grid is formed from strips bent at an angle of about 120.degree. at each vertex. Over some faces of each hexagonal cell the strips are coplanar but are arranged, by stacking and interlocking, to avoid any double thickness of metal in that plane. Springs and dimples are formed in the faces of each cell to hold the fuel pin substantially centered.

Kast, Steven J. (Niskayuna, NY)

1987-01-01

45

Interlocking egg-crate type grid assembly  

DOEpatents

Disclosed is an interlocking egg-crate hexagonal grid for supporting a nuclear fuel pin in a hexagonal array. The grid is formed from strips bent at an angle of about 120/sup 0/ at each vertex. Over some faces of each hexagonal cell the strips are coplanar but are arranged, by stacking interlocking, to avoid any double thickness of metal in that plane. Springs and dimples are formed in the faces of each cell to hold the fuel pin substantially centered.

Kast, S.J.

1985-03-15

46

Radiation-free drill guidance in interlocking of intramedullary nails.  

PubMed

Intramedullary nailing is a technically demanding procedure which involves an excessive amount of x-ray acquisitions; one study lists as many as 48 to successfully complete the procedure. In this work, a novel low cost radiation-free drilling guide is designed to assist surgeons in completing the distal locking procedure without any x-ray acquisitions. Using an augmented reality fluoroscope that coregisters optical and x-ray images, we exploit solely the optical images to detect the drilling guide in order to estimate the tip position in real-time in x-ray. We tested over 200 random drill guide poses showing a mean tip-estimation error of 1.72 +/- 0.7mm which is significantly robust and accurate for the interlocking. In a preclinical study on dry bone phantom, three expert surgeons successfully completed the interlocking 56 out of 60 trials with no x-ray acquisition for guidance and an average time of 2 min. PMID:23285530

Diotte, Benoit; Fallavollita, Pascal; Wang, Lejing; Weidert, Simon; Thaller, Peter-Helmut; Euler, Ekkehard; Navab, Nassir

2012-01-01

47

Far cortical locking technology for fixation of periprosthetic distal femur fractures: a surgical technique.  

PubMed

Far cortical locking screws have been shown to form greater amounts of callus in ovine studies when compared to traditional locking plates. These screws have recently become available for clinical use. This article describes the indications and surgical technique for far cortical locking screws, with a focus on distal femur periprosthetic fractures. PMID:23408343

Ries, Zachary G; Marsh, J L

2013-02-13

48

Posterior Cervical Bone Screws  

Center for Biologics Evaluation and Research (CBER)

Text Version... Smith MD et al, Spine 1993: 18, 1984. Page 3. POSTERIOR CERVICAL BONE SCREWS ... Page 4. POSTERIOR CERVICAL BONE SCREWS ... More results from www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials

49

49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.  

Code of Federal Regulations, 2012 CFR

...false Electromechanical interlocking machine; locking between electrical and mechanical...340 Electromechanical interlocking machine; locking between electrical and mechanical... In electro-mechanical interlocking machine, locking between electric and...

2012-10-01

50

49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.  

Code of Federal Regulations, 2011 CFR

...false Electromechanical interlocking machine; locking between electrical and mechanical...340 Electromechanical interlocking machine; locking between electrical and mechanical... In electro-mechanical interlocking machine, locking between electric and...

2011-10-01

51

[Intramedullary interlocking of humeral fractures and nonunions with Seidel nail].  

PubMed

The advantages and disadvantages of interlocking Seidel's nails determined by their construction and the way of insertion were presented on the basis of own experience and literature. The advantages are strength and shape of the nails which are conductive to fragments stability and make insertion into humerus medullar canal easier. The tools set for insertion and locking of distal part. It doesn't truly protect from torsion displacements. Locking takes place by draw for a few weeks by external immobilization. The Seidel's nail has also disadvantages associated with proximal insertion. Unavoidable injury of supraspinatus tendon insertion can be the reason of loss of shoulder function. The antegrade fixation can cause pushing distal fragment downward by tip of the nail. It is necessary to control it's insertion under image intensifier. Presented disadvantages of Seidel's nail fixation didn't result in any problems in humerus fractures or pseudoarthroses healing. In one case it was necessary to perform additional decortication and space of fracture fulfillment with bone grafts. PMID:16158873

Modrzewski, Krzysztof; Urban, Tadeusz; Gaweda, Krzysztof

2005-01-01

52

Embolization of Dural Arteriovenous Fistulas with Interlocking Detachable Coils  

Microsoft Academic Search

Summary: Our clinical experience with interlocking detachable coils for the embolization of high-flow dural arteriovenous fistu- las is reported. Interlocking detachable coils are useful for transarterial and transvenous embolizations of dural arterio- venous fistulas because (a) immediate coil detachment is pos- sible, (b) the coils can be replaced easily, (c) detached coils rarely migrate, and (d) fewer interlocking detachable coils

Shin-ichi Yoshimura; Nobuo Hashimoto; Kiyoshi Kazekawa; Shogo Nishi; Kenji Sampei

53

Nonlinear aggregate interlock model for concrete pavements  

Microsoft Academic Search

The objective of the study was to develop a constitutive model that captures the nonlinear behavior of shear load transfer through aggregate interlock. A stepwise linear model was proposed. The model parameters were determined by optimizing numerically predicted to experimentally measured slab deflection basins. Continuous measurements of concrete deflection basins and truck loading were obtained using a specially designed large-scale

E. A. Jensen; W. Hansen

2006-01-01

54

Distal Pancreatectomy  

Microsoft Academic Search

\\u000a Resection of the body and tail of the pancreas is commonly referred to as distal pancreatectomy. Although potentially of benefit\\u000a to patients with pancreatic adenocarcinoma confined to the body or tail of the pancreas, such tumors commonly metastasize\\u000a prior to being discovered, and distal pancreatectomy for pancreatic carcinoma is a relatively uncommon procedure even at high\\u000a volume pancreatic surgery centers.

Andrew S. Resnick; Jeffrey A. Drebin

55

Arthrodesis of the distal interphalangeal joint: description of a new technique and clinical follow-up at 2 years  

Microsoft Academic Search

Introduction  Arthrodesis of the distal interphalangeal joint (DIPJ) is an accepted operative procedure to treat osteoarthritis, instability\\u000a and joint deformity. There is a wide spectrum of recommended operative techniques including cerclage wires, headless screws,\\u000a bio-resorbable pins and lag screws. Lag screw fixation remains one of the most accepted methods of fixation; however, problems\\u000a can occur in particular subsidence of the screw

L. C. Olivier; F. Gensigk; T. N. Board; D. Kendoff; U. Krehmeier; U. Wolfhard

2008-01-01

56

The biomechanical consequences of rod reduction on pedicle screws: should it be avoided?  

PubMed

BACKGROUND CONTEXT: Rod contouring is frequently required to allow for appropriate alignment of pedicle screw-rod constructs. When residual mismatch is still present, a rod persuasion device is often used to achieve further rod reduction. Despite its popularity and widespread use, the biomechanical consequences of this technique have not been evaluated. PURPOSE: To evaluate the biomechanical fixation strength of pedicle screws after attempted reduction of a rod-pedicle screw mismatch using a rod persuasion device. METHODS: Fifteen 3-level, human cadaveric thoracic specimens were prepared and scanned for bone mineral density. Osteoporotic (n=6) and normal (n=9) specimens were instrumented with 5.0-mm-diameter pedicle screws; for each pair of comparison level tested, the bilateral screws were equal in length, and the screw length was determined by the thoracic level and size of the vertebra (35 to 45 mm). Titanium 5.5-mm rods were contoured and secured to the pedicle screws at the proximal and distal levels. For the middle segment, the rod on the right side was intentionally contoured to create a 5-mm residual gap between the inner bushing of the pedicle screw and the rod. A rod persuasion device was then used to engage the setscrew. The left side served as a control with perfect screw/rod alignment. After 30 minutes, constructs were disassembled and vertebrae individually potted. The implants were pulled in-line with the screw axis with peak pullout strength (POS) measured in Newton (N). For the proximal and distal segments, pedicle screws on the right side were taken out and reinserted through the same trajectory to simulate screw depth adjustment as an alternative to rod reduction. RESULTS: Pedicle screws reduced to the rod generated a 48% lower mean POS (495±379 N) relative to the controls (954±237 N) (p<.05) and significantly decreased work energy to failure (p<.05). Nearly half (n=7) of the pedicle screws had failed during the reduction attempt with visible pullout of the screw. After reduction, decreased POS was observed in both normal (p<.05) and osteoporotic (p<.05) bone. Back out and reinsertion of the screw resulted in no significant difference in mean POS, stiffness, and work energy to failure (p>.05). CONCLUSIONS: In circumstances where a rod is not fully seated within the pedicle screw, the use of a rod persuasion device decreases the overall POS and work energy to failure of the screw or results in outright failure. Further rod contouring or correction of pedicle screw depth of insertion may be warranted to allow for appropriate alignment of the longitudinal rods. PMID:23769931

Paik, Haines; Kang, Daniel G; Lehman, Ronald A; Gaume, Rachel E; Ambati, Divya V; Dmitriev, Anton E

2013-06-13

57

49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312...Interlocking Standards § 236.312 Movable bridge, interlocking of signal appliances with...

2011-10-01

58

49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312...Interlocking Standards § 236.312 Movable bridge, interlocking of signal appliances with...

2012-10-01

59

Fabrication and Evaluation of a Noncompliant Molar Distalizing Appliance: Bonded Molar Distalizer  

PubMed Central

Objective Attempts to treat class II malocclusions without extraction in non-compliant patients have led to utilization of intraoral molar distalizing appliances. The purpose of this study was to investigate dental and skeletal effects of Bonded Molar Distalizer (BMD) which is a simple molar distalizing appliance. Materials and Methods Sixteen patients (12 girls, four boys) with bilateral half-cusp class II molar relationship, erupted permanent second molars and normal or vertical growth pattern were selected for bilateral distalization of maxillary molars via BMD. The screws were activated every other day, alternately. Lateral cephalograms and study models were obtained before treatment and after 11 weeks activation of the appliance. Results Significant amounts of molar distalization, molar distal tipping and anchorage loss were observed. The mean maxillary first molar distal movement was 1.22±0.936 mm with a distal tipping of 2.97±3.74 degrees in 11 weeks. The rate of distal movement was 0.48 mm per month. Reciprocal mesial movement of the first premolars was 2.26±1.12 mm with a mesial tipping of 4.25±3.12 degrees. Maxillary incisors moved 3.55±1.46 mm and tipped 9.87±5.03 degrees mesially. Lower anterior face height (LAFH) decreased 1.28±1.36 mm. Conclusion BMD is appropriate for distalizing maxillary molars, especially in patients with critical LAFH, although significant amounts of anchorage loss occur using this appliance.

Sodagar, A.; Ahmad Akhoundi, M. S.; Rafighii, A.; Arab, S.

2011-01-01

60

6. Detail of northeast corner of Shell Interlocking Tower, showing ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. Detail of northeast corner of Shell Interlocking Tower, showing ornamental east concrete beltcourse and tower shield with bronze numerals. - New York, New Haven, & Hartford Railroad, Shell Interlocking Tower, New Haven Milepost 16, approximately 100 feel east of New Rochelle Junction, New Rochelle, Westchester County, NY

61

The interlocking paradigm of cultural competence: A best practice approach  

Microsoft Academic Search

Cultural competence is a key factor in the delivery of quality psychiatric mental health (PMH) nursing care. The Interlocking Paradigm of Cultural Competence (IPCC) is a best-practice model developed from the work of Peplau, Leininger, Nichols, Campinha-Bacote, and Purnell. The IPCC has five interlocking factors (therapeutic, value, world view, process, and orientation) representing theoretical, philosophical, process, and assessment components. This

Barbara Jones Warren

2002-01-01

62

A MODEL FOR TRIALING ALCOHOL IGNITION INTERLOCKS IN QUEENSLAND  

Microsoft Academic Search

This paper describes the development of a model for the trialing of alcohol ignition interlocks with drink driving offenders in Queensland. A range of information sources were used to develop the model, including: an extensive review of the international literature relating to interlocks; an analysis of data relating to the operation of the Under the Limit rehabilitation program in Queensland;

Cynthia Schonfeld; Mary Sheehan

63

An advanced interlock solution for TTF2\\/XFEL RF stations  

Microsoft Academic Search

The main task of the interlock system is to prevent any damage from the cost expensive components of the RF station. The implementation of the interlock should guarantee a maximum uninterrupted time of operation which implies the implementation of self diagnostic and repair strategies on module basis. Additional tasks include collection and temporary storage of status information of individual channels;

H. Leich; S. Choroba; P. Duval; T. Grevsmuhl; V. Petrosyan; S. Weisse; R. Wenndorff

2005-01-01

64

A Configurable Interlock System for RF-Stations at XFEL  

Microsoft Academic Search

The main task of the interlock system is to prevent any damage to the cost expensive components of the RF station. The implementation of the interlock should guarantee a maximum of uninterrupted time of operation which includes the implementation of self diagnostic and repair strategies on module basis. Additional tasks include collection and temporary storage of status information of individual

M. Penno; T. Grevsmuhl; H. Leich; A. Kretzschmann; W. Kohler; B. Petrosyan; G. Trowitzsch; R. Wenndorff

2007-01-01

65

Synthesis of interlocked molecules by olefin metathesis  

NASA Astrophysics Data System (ADS)

A large body of work in the Grubbs group has focused on the development of functional-group tolerant ruthenium alkylidene catalysts that perform a number of olefin metathesis reactions. These catalysts have seen application in a wide range of fields, including classic total synthesis as well as polymer and materials chemistry. One particular family of compounds, interlocked molecules, has benefitted greatly from these advances in catalyst stability and activity. This thesis describes several elusive and challenging interlocked architectures whose syntheses have been realized through the utilization of different types of ruthenium-catalyzed olefin metathesis reactions. Ring-closing olefin metathesis has enabled the synthesis of a [c2]daisy-chain dimer with the ammonium binding site near the cap of the dimer. A deprotonated DCD possessing such a structural attribute will more forcefully seek to restore coordinating interactions upon reprotonation, enhancing its utility as a synthetic molecular actuator. Dimer functionalization facilitated incorporation into linear polymers, with a 48% size increase of an unbound, extended analogue of the polymer demonstrating slippage of the dimer units. Ongoing work is directed at further materials studies, in particular, exploring the synthesis of macroscopic networks containing the DCD units and analyzing the correlation between molecular-scale extension-contraction manipulations and resulting macro-scale changes. A "clipping" approach to a polycatenated cyclic polymer, a structure that resembles a molecular "charm bracelet", has been described. The use of ring-opening metathesis polymerization of a carbamate monomer in the presence of a chain transfer agent allowed for the synthesis of a linear polymer that was subsequently functionalized and cyclized to the corresponding cyclic analogue. This cyclic polymer was characterized through a variety of techniques, and subjected to further functionalization reactions, affording a cyclic polyammonium scaffold. Diolefin polyether fragments were coordinated and "clipped" around the ammonium sites within the polymer backbone using ring-closing olefin metathesis, giving the molecular "charm bracelet". Confirmation of the interlocked nature of the product was achieved via 1H NMR spectroscopy and two-dimensional diffusion ordered NMR spectroscopy. A simple strategy for a one-pot, multi-component synthesis of polyrotaxanes using acyclic diene metathesis polymerization was developed. The polyrotaxanes were characterized by traditional 1H NMR spectroscopy as well as size exclusion chromatography, and the interlocked topology was confirmed using two-dimension diffusion-ordered NMR spectroscopy. The dynamic, self-correcting nature of the ADMET polymerization was also explored through the equilibration of a capped polyammonium polymer in the presence of dibenzo-24-crown-8 ether and olefin metathesis catalysts. The efficiency and ease with which these mechanically interlocked macromolecules can be assembled should facilitate rapid modulation to achieve versatile polyrotaxane architectures. Flexible, switchable [c2]daisy-chain dimers (DCDs) were synthesized, where the macromer ammonium binding site was adjacent to the crown-type recognition structure and separated from the cap by an alkyl chain. A DCD of this topology is expected to have an extended structure in the bound conformation (when the ammonium was coordinated to the crown). Several different macromer candidates were designed to allow access to DCDs with flexible alkyl chains between the ammonium binding site and the cap, and a number of synthetic routes were explored in an effort to access these challenging materials. While the first generation DCD structure proved to be unstable due to a labile ester linkage, work is continuing toward the development of several cap structures in an effort to replace the ester linkage with an ether linkage, which, in the second generation model systems, has proven much more stable to the acidic and basic conditions necessary

Clark, Paul Gregory

66

Helical screw viscometer  

DOEpatents

A helical screw viscometer for the measurement of the viscosity of Newtonian and non-Newtonian fluids comprising an elongated cylindrical container closed by end caps defining a circular cylindrical cavity within the container, a cylindrical rotor member having a helical screw or ribbon flight carried by the outer periphery thereof rotatably carried within the cavity whereby the fluid to be measured is confined in the cavity filling the space between the rotor and the container wall. The rotor member is supported by axle members journaled in the end caps, one axle extending through one end cap and connectable to a drive source. A pair of longitudinally spaced ports are provided through the wall of the container in communication with the cavity and a differential pressure meter is connected between the ports for measuring the pressure drop caused by the rotation of the helical screw rotor acting on the confined fluid for computing viscosity.

Aubert, J.H.; Chapman, R.N.; Kraynik, A.M.

1983-06-30

67

Innovation: the induction heated screw.  

National Technical Information Service (NTIS)

The Research and Development Division at EDF has developed an original technique for heating, drying or baking powder products: the induction heated Archimedes screw. Its main characteristic is simultaneous heating of the screw and the sleeve. (author). 4...

B. Paya

1993-01-01

68

Blocks and Screws  

NSDL National Science Digital Library

In this lesson, each student is given a block of wood and a screw (or nail), and is asked to put the screw into the block, without any tool (like a screwdriver or hammer). Their efforts, with varying success, lead to a discussion of contrivances, using various items and strategies as make-do (contrived) tools for which they were not intended, and an exploration of many examples of contrivances or adaptive compromises and other imperfections in the living world, especially in humans. This situation may be better explained by evolution rather than the result of intelligent design.

Patterson, Tim

69

Microfabricated interlock system for precision alignment  

NASA Astrophysics Data System (ADS)

A mechanical interlock system is reported that achieves the manual alignment of two components accurate to within plus or minus 10 micrometers in three spatial coordinates. In addition, the system allows rapid component interchange. The system is based on a novel two stage application of the principles of the kinematic location of instrument components. A macro scale kinematic mount allows manual handling while a micro scale mount delivers the accuracy required. Silicon microfabrication methods are used to create features in the micron size range accurately and repeatable for the micro scale mount. Such a system could be used for fluidic, pneumatic, electrical, optical, or mechanical interconnects. We use it for the alignment of optics to flow channel in an optical flow cytometer which is part of a microfluidic total chemical analysis system we are developing.

Sabeti, Roya; Holl, Mark R.; Altendorf, Eric A.; Yager, Paul

1997-03-01

70

Distal femoral fit non-cemented arthroplasty in proximal deficient femur--early results.  

PubMed

Revision surgeries in failed proximal femoral pathologies following osteosynthesis or some kind of replacements pose a challenging task. These can be well managed by distally well fitted extensively coated hydroxyapatide long non-cemented interlocked Reef-Dupuy stem. Here a short series of 10 cases with average follow-up of 3 years is being presented. PMID:23785923

Kumar, Sanjay; Santra, Sabyasachi; Bhattacharyya, Arunangsu; Banerjee, Kallol

2012-11-01

71

Translaminar Facet Screw Fixation  

Microsoft Academic Search

significantly longer than that used by both Boucher and King due to an entry point at the base of the contralateral spinous process. This improves the technique by increasing the ef- fective working length of the screw on both sides of the facet joint resulting in increased strength of the fixation. This review focuses on the advantages of translaminar facet

Rick C. Sasso; Natalie M. Best

72

Interference screw fixation using bioabsorbable screw as void filler.  

PubMed

We evaluated interference screw fixation in a plug-tunnel construct using bioabsorbable screws as void fillers with different percentages of the screw removed. Nine-millimeter tunnels in a closed-cell foam block were filled with a 10-mm bioabsorbable screw, and 10-mm revision tunnels were placed in parallel with tunnel overlap resulting in removal of 10%, 25%, or 50% of the screw diameter. Synthetic bone plugs were fashioned to fit 10-mm tunnels. In all groups, the plugs were secured in standard interference fixation with a 9-mm metal screw between the void-filling bioabsorbable screw and plug. Failure loads for the control group (no revision tunnel) averaged 926 +/- 44 N, 10% (1024 +/- 129 N) and 25% (932 +/- 129 N) groups were not significantly different; failure load in the 50% diameter group (780 +/- 72 N) was significantly lower than all other groups (p < 0.001). Using a bioabsorbable screw as void filler provided mean load to failure not different from that of standard reconstruction when 10 and 25% of the diameter of the void-filling screw was removed. Load to failure was significantly lower when 50% of the void-filling screw diameter group was removed. This may be applicable in anterior cruciate ligament reconstruction where a previous tunnel void has to be addressed. PMID:22303758

Fullick, Robert; Parks, Brent; Hinton, Richard

2011-12-01

73

Guidewire Breakage: An Unusual Complication of Anterior Odontoid Cannulated Screw Fixation  

PubMed Central

The preferred treatment of a type II odontoid fracture is anterior odontoid screw fixation to preserve the cervical spine range of movement. This case report describes an unusual complication of guidewire breakage during anterior odontoid cannulated screw fixation for a 52-year-old patient who presented with a type II odontoid fracture after a motor vehicle accident. The distal segment of the guidewire was bent over the tip of the cannulated odontoid screw and broke off during guidewire withdrawal. The three months follow-up computed tomography examination of the cervical spine showed acceptable screw placement, good odontoid process alignment with incomplete fusion, and no migration of the fractured segment of the guidewire. It is recommended that the guidewire be withdrawn once the cannulated screw is passed through the fractured site into the odontoid process and a new guidewire be used in each surgical procedure instead of been reused to avoid metal stress fatigue that can result in easy breakage.

Bin-Nafisah, Sharaf; Almusrea, Khaled; Alfawareh, Mohamed

2011-01-01

74

BOWIE INTERLOCKING TOWER AND PASSENGER STATION. BOWIE, PRINCE GEORGES CO., ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

BOWIE INTERLOCKING TOWER AND PASSENGER STATION. BOWIE, PRINCE GEORGES CO., MD. Sec. 1201, MP 120.50. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

75

Perryville Interlocking Tower. Perryville, Cecil Co., MD. Sec. 1201, MP ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Perryville Interlocking Tower. Perryville, Cecil Co., MD. Sec. 1201, MP 59.10. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

76

Edgewood Interlocking Tower. Edgewood, Hareford Co., MD. Sec. 1201, MP ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Edgewood Interlocking Tower. Edgewood, Hareford Co., MD. Sec. 1201, MP 75.50. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

77

B & P Junction Substation & Interlocking Tower. Baltimore, Baltimore ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

B & P Junction Substation & Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.85. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

78

Union Junction Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Union Junction Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.49. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

79

DETAIL OF STANDARD INTERLOCKING MACHINE OPERATING LEVERS. LOCKING MECHANISM IS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL OF STANDARD INTERLOCKING MACHINE OPERATING LEVERS. LOCKING MECHANISM IS BELOW FLOOR. BOXES BEHIND SOME LEVERS HOUSE ELECTRICAL CONTACTS FOR SIGNALS. - Baltimore & Ohio Railroad, Z Tower, State Route 46, Keyser, Mineral County, WV

80

34. Boston switch interlocking tower. Central Falls, Providence Co., RI. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

34. Boston switch interlocking tower. Central Falls, Providence Co., RI. Sec. 4116, mp 190.40. - Northeast Railroad Corridor, Amtrak route between CT & MA state lines, Providence, Providence County, RI

81

21 CFR 876.4590 - Interlocking urethral sound.  

Code of Federal Regulations, 2013 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4590 Interlocking urethral sound. (a) Identification. An...

2013-04-01

82

Interphalangeal joint arthrodesis with oblique placement of an AO lag screw.  

PubMed

A damaged interphalangeal (IP) joint may be treated by fusion. Arthrodesis should leave the joint at the most functional angle and give sound bony union in the shortest possible time, maintaining maximum proximal and distal joint motion. The lateral oblique placement of a single AO lag screw, proximal to distal, achieves these aims. This method gives sufficient proximal bone for screw purchase and better control of the desired angle of fusion. This technique has led to fusion in 22 of 23 joints (96%), taking an average of 8.2 weeks. PMID:8014552

Teoh, L C; Yeo, S J; Singh, I

1994-04-01

83

Artificial nanomachines based on interlocked molecules  

NASA Astrophysics Data System (ADS)

The extension of the concept of machine to the molecular level is of great interest for the growth of nanoscience and the development of nanotechnology. A molecular machine can be defined as an assembly of a discrete number of molecular components (that is, a supramolecular structure) designed to perform a function through the mechanical movements of its components, which occur under appropriate external stimulation. Hence, molecular machines contain a motor part, that is a device capable of converting energy into mechanical work. Molecular motors and machines operate via nuclear rearrangements and, like their macroscopic counterparts, are characterized by the kind of energy input supplied to make them work, the manner in which their operation can be monitored, the possibility to repeat the operation at will, i.e., establishing a cyclic process, the timescale needed to complete a cycle of operation, and the performed function. Owing to the progresses made in several branches of chemistry, and to the better understanding of the operation mechanisms of molecular machines of the biological world, it has become possible to design and construct simple prototypes of artificial molecular motors and machines. Some examples based on rotaxanes, catenanes, and related interlocked molecules will be described.

Credi, Alberto

2006-08-01

84

Strength comparison of allogenic bone screws, bioabsorbable screws, and stainless steel screw fixation.  

PubMed

Allogenic bone screws are new to the fixation market and have yet to be tested against current fixation materials. An in vitro comparison of the same sizes of stainless steel, bioabsorbable, and allogenic bone screws was undertaken to assess screw resistance to the forces of bending, pullout, and shear. Using aluminum plates to support the screws, forces up to 1000 Newtons were applied to six to eight samples of each type of screw. During each test, stainless steel screws withstood the maximum force that could be exerted by the testing apparatus without failing (bending, 113.9 +/- 11.8 N mean +/- SE; pullout 999.1 +/- 33.7 N; and shear, 997.5 +/- 108.8 N). In each test, compared to bioabsorbable screws, allogenic bone screws failed faster (pullout, allogenic: 12.4 +/- 1.1 seconds vs. bioabsorbable, 120.6 +/- 13.8 seconds; p = .001; bending, allogenic: 53.4 +/- 4.8 seconds vs. bioabsorbable, 201.9 +/- 11.1 seconds; p = .001; shear, allogenic 13.5 +/- 1.4 seconds vs. bioabsorbable, 43.8 +/- 0.9 seconds; p = .001) under equivalent (pullout: bioabsorbable, 385.0 +/- 18.4 N vs. allogenic, 401.0 +/- 35.9 N; p = .001) or lower (bending, allogenic: 4.7 +/- 0.2 N vs. bioabsorbable, 11.0 +/- 0.9 N; p = .675; shear, allogenic: 312.1 +/- 15.5 N vs. bioabsorbable 680.9 +/- 8.5 N; p = .001) loads, and in a highly variable fashion. Overall, the bioabsorbable screws withstood the forces of bending, pullout, and shear better than the allogenic screws, and stainless steel screws outperformed both bioabsorbable and allogenic screws. Despite these results, allogenic screws could still be useful in compliant patients who would benefit from their osteoconductive properties. PMID:11858609

Rano, James A; Savoy-Moore, Ruth T; Fallat, Lawrence M

85

Arthroscopy-assisted minimally invasive removal of a plate in the distal femur.  

PubMed

We developed an arthroscopy-assisted minimally invasive procedure for removal of a plate in the distal femur. Under arthroscopic assistance, we made an arthrotomy in the middle of the screws attached to the plate in the knee joint; all screws were removed, except for those placed proximally that were too difficult to remove. An approximately 5-cm skin incision (the distal one half to one third of it was near the proximal end of the knee cavity) was made through the old incision scar under arthroscopic assistance, and visible screws were removed. Proximal screws that were not visible through this incision were removed percutaneously through new small stab incisions placed midway between every 2 screws under the control of an image intensifier. Then, a small arthrotomy was made through the distal portion of the approximately 5-cm incision, at the place where the plate entered the knee joint. Through this arthrotomy, any screws still attached to the plate within the knee joint were removed. Then, the plate was stripped from the distal femur, was pulled proximally, and was removed without difficulty. With the use of this procedure, we can concomitantly assess the condition of the intra-articular region. PMID:17157740

Kim, Young-Mo; Rhee, Kwang-Jin; Lee, June-Kyu; Hwang, Deuk-Soo; Yang, Jun-Young; Kim, Kyung-Cheon; Kim, Sung-Jae

2006-10-23

86

Molar distalization with bimetric molar distalization arches.  

PubMed

The aim of this study was to observe the clinical and cephalometric effects of intra-oral distalization with the maxillary bimetric arches. 3 girls and 1 boy with a mean age of 13.5 years with Class II skeletal and dental relationship were selected. Care was taken to select patients having a normal vertical growth pattern. Lateral cephalograms were taken at the beginning and at the end of the distalization period, which was approximately 3 months. To observe the distal movement, a metal marker was attached to the distal end of the buccal tube of the first molar. On each lateral cephalometric radiograph a reference plane perpendicular to the occlusal plane and passing through the point Sella was drawn to assess the amount of distalization. Cephalometric measurements indicated that the upper molars moved approximately 3 mm distally and that the lower incisors were proclined. PMID:9582621

Küçükkele?, N; Do?anay, A

1994-09-01

87

Anion-templated assembly of interpenetrated and interlocked structures.  

PubMed

The rational development of a general anion templation strategy for the construction of a variety of interpenetrated and interlocked molecular structures based upon the coupling of anion recognition with ion-pairing is described. The success of this anion templation methodology is demonstrated with the halide anion directed assembly of a series of novel [2]pseudorotaxanes containing pyridinium, pyridinium nicotinamide, imidazolium, benzimidazolium and guanidinium threading components and anion binding macrocyclic ligands. Interlocked [2]rotaxane and [2]catenane molecular structures are also synthesised using this anion templation protocol. These interlocked structures feature unique topologically defined hydrogen bond donating binding domains that exhibit a high degree of selectivity for chloride, the templating anion. A series of rhenium(I) bipyridyl containing [2]pseudorotaxane assemblies and a [2]rotaxane further highlight the potential this strategic anion templation approach has in future chemical sensor design and fabrication. PMID:16703125

Beer, Paul D; Sambrook, Mark R; Curiel, David

2006-03-08

88

PLC-based interlock system for superconducting magnets  

SciTech Connect

Conventional interlock systems rely heavily on hard-wired electromagnetic relays. Although this approach is well understood and has proven to be reliable, several drawbacks plague the designer as well as the repairman. If larger systems have to be implemented in relay logic, the complexity limit is soon reached; the systems become too bulky, and wiring expenses sky-rocket; moreover, the intelligence of those designs is limited in such a way that desirable features such as self-tests have to be left out. Additionally, relay interlocks are inherently inflexible: if the configuration of the system they protect has to change, a disproportional amount of time, work and money has to be invested in order to adapt the hard-wiring of the interlock system to the new requirements. Repair work is often unnecessarily delayed due to the lack of adequate documentation.

Agostini, R.C.; Barker, L.; Hodgers, J.; Reagan, D.; Walz, H.V. (Stanford Univ., CA (USA))

1989-10-01

89

Design review report for the hydrogen interlock preliminary design  

SciTech Connect

This report documents the completion of a preliminary design review for the hydrogen interlock. The hydrogen interlock, a proposed addition to the Rotary Mode Core Sampling (RMCS) system portable exhauster, is intended to support core sampling operations in waste tanks requiring flammable gas controls. The objective of this review was to validate basic design assumptions and concepts to support a path forward leading to a final design. The conclusion reached by the review committee was that the design was acceptable and efforts should continue toward a final design review.

Corbett, J.E.

1996-01-01

90

1. ENVIRONMENT, FROM NORTHWEST, SHOWING B&P INTERLOCKING TOWER AND POWER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. ENVIRONMENT, FROM NORTHWEST, SHOWING B&P INTERLOCKING TOWER AND POWER SUBSTATIONS - Baltimore & Potomac Interlocking Tower, Adjacent to AMTRAK railroad tracks in block bounded by Howard Street, Jones Falls Expressway, Maryland Avenue & Falls Road, Baltimore, Independent City, MD

91

46 CFR 111.70-7 - Remote control, interlock, and indicator circuits.  

Code of Federal Regulations, 2012 CFR

... (a) Overcurrent protection. A conductor of a control, interlock, or indicator...against overcurrent unless: (1) The conductor is wholly within the controller enclosure...control, interlock, or indicator circuit conductor; (3) There is an...

2012-10-01

92

Orientation of the "Lisfranc screw".  

PubMed

The reduction and stabilization of diastases between the medial cuneiform and the base of second metatarsal after a Lisfranc ligament injury is a crucial objective in the open reduction and internal fixation of these injuries. To achieve this objective, a single screw is used. The present practice is to insert the screw directed from the medial cuneiform bone into the base of the second metatarsal. This technique trick describes an easier method of insertion of the screw and one that possibly provides a better fixation. PMID:22549028

Panchbhavi, Vinod K

2012-11-01

93

B & P Junction Substation & Interlocking Tower; Howard Street ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

B & P Junction Substation & Interlocking Tower; Howard Street Bridge. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.85 - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

94

INTERLOCK SYSTEM FOR A FFAG COMPLEX IN KURRI  

Microsoft Academic Search

For basic research experiments of accelerator driven subcritical reactor (ADSR) system, an 150 MeV FFAG accelerator is now constructed in Kyoto University Research Reactor Institute (KURRI). The installed accelerator will be connected to the nuclear fuel assembly and be used for physical and chemical research using the proton beam produced by the accelerator. The highly secure and flexible interlock system

K. Takamiya; M. Tanigaki; A. Taniguchi; Y. Oki; H. Yashima; K. Takami; H. Yoshino; N. Abe; T. Takeshita; K. Mishima; S. Shiroya

95

Optimizing system coordination and overcurrent protection with zone selective interlocking  

Microsoft Academic Search

After a review of the currently available types of low-voltage circuit breakers and fuses, a discussion is presented of how to optimize low-voltage distribution for selectively coordinated systems through the use of properly selected overcurrent protection devices. Topics covered include how these components respond during overcurrent conditions and how system coordination is enhanced by zone selective interlocking

S. Yong; T. Michalak

1990-01-01

96

Description of a system for interlocking elevated temperature mechanical tests  

SciTech Connect

Long term mechanical creep and fatigue testing at elevated temperatures requires reliable systems with safeguards to prevent destruction of equipment, loss of data and negative environmental impacts. Toward this goal, a computer controlled system has been developed and built for interlocking tests run on elevated temperature mechanical test facilities. Sensors for water flow, water pressure, water leakage, temperature, power and hydraulic status are monitored to control specimen heating equipment through solid state relays and water solenoid valves. The system is designed to work with the default interlocks present in the RF generators and mechanical tests systems. Digital hardware consists of two National Instruments 1/0 boards mounted in a Macintosh IIci computer. Software is written in National Instruments LabVIEW. Systems interlocked include two MTS closed loop servo controlled hydraulic test frames, one with an RF generator and one with both an RF generator and a quartz lamp furnace. Control for individual test systems is modularized making the addition of more systems simple. If any of the supporting utilities fail during tests, heating systems, chill water and hydraulics are powered down, minimizing specimen damage and eliminating equipment damage. The interlock control is powered by an uninterruptible power supply. Upon failure the cause is documented in an ASCII file.

Schmale, D.T.; Poulter, G.A.

1995-07-01

97

Interlocked fabric and laminated fabric Kevlar 49/epoxy composites  

SciTech Connect

The mechanical behavior of a novel interlocked fabric reinforced Kevlar 49/epoxy composite has been measured and compared to those of a laminated Kevlar 49 fabric composite (which served as a reference material). Both composites were 5.0 mm thick, contained the same 50% in-plane fiber volume fraction and were fabricated in a similar manner using the same Dow DER 332 epoxy, Jeffamine T403-hardened resin system. The reference material (Material 1) was reinforced with seven plies of Dupont style 1033 Kevlar 49 fabric. A photomicrograph of a section polished parallel to one of the fiber directions is shown. The interlocked fabric was designed and woven for Sandia National Laboratories by Albany International Research Co., Dedham, MA. The main design criterion was to duplicate a sewn through-the-thickness fabric used in preliminary studies. The interlocked fabric composite (Material 2) contains roughly 4% by volume of through-the-thickness fiber reinforcement for the purpose of improving interlaminar strength. A photomicrograph of a section showing the warp-aligned binder yarns interlocking the six fabric plies together is shown. 2 refs., 8 figs.

Guess, T.R.; Reedy, E.D. Jr.

1988-01-01

98

How Does Learning Intent Affect Interlocking Directorates Dynamic?  

ERIC Educational Resources Information Center

|Purpose: Literature on board interlocks agrees that these inter-organizational ties are effective channels to exchange information and share knowledge. However, studies that consider the nature and the amount of knowledge that firms exchange are still relatively absent. Filling this gap, this paper aims to identify four types of mechanisms that…

Simoni, Michele; Caiazza, Rosa

2012-01-01

99

Flammable gas interlock spoolpiece flow response test plan and procedure  

SciTech Connect

The purpose of this test plan and procedure is to test the Whittaker electrochemical cell and the Sierra Monitor Corp. flammable gas monitors in a simulated field flow configuration. The sensors are used on the Rotary Mode Core Sampling (RMCS) Flammable Gas Interlock (FGI), to detect flammable gases, including hydrogen and teminate the core sampling activity at a predetermined concentration level.

Schneider, T.C., Fluor Daniel Hanford

1997-02-13

100

Helical Screw Expander Evaluation Project.  

National Technical Information Service (NTIS)

A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate t...

R. Mckay

1982-01-01

101

Posterior spinal arthrodesis for adolescent idiopathic scoliosis using pedicle screw instrumentation: does a bilateral or unilateral screw technique affect surgical outcome?  

PubMed

We reviewed 212 consecutive patients with adolescent idiopathic scoliosis who underwent posterior spinal arthrodesis using all pedicle screw instrumentation in terms of clinical, radiological and Scoliosis Research Society (SRS)-22 outcomes. In Group 1 (51 patients), the correction was performed over two rods using bilateral segmental pedicle screws. In Group 2 (161 patients), the correction was performed over one rod using unilateral segmental pedicle screws with the second() rod providing stability of the construct through two-level screw fixation at proximal and distal ends. The mean age at surgery was 14.8 years in both groups. Comparison between groups showed no significant differences with regard to age and Risser grade at surgery, pre- and post-operative scoliosis angle, coronal Cobb correction, length of hospital stay and SRS scores. Correction of upper thoracic curves was significantly better in Group 1 (p = 0.02). Increased surgical time and intra-operative blood loss was recorded in Group 1 (p < 0.001 and p = 0.04, respectively). The implant cost was reduced by mean 35% in Group 2 due to the lesser number of pedicle screws. Unilateral and bilateral pedicle screw techniques have both achieved excellent deformity correction in adolescent patients with idiopathic scoliosis, which was maintained at two-year follow-up. This has been associated with high patient satisfaction and low complication rates. PMID:23188910

Tsirikos, A I; Subramanian, A S

2012-12-01

102

Biomechanical comparison of endplate forces generated by uniaxial screws and monoaxial pedicle screws.  

PubMed

Current surgical treatment of idiopathic scoliosis involves the use of various segmental instrumentation. Various pedicle screws have allowed for improved correction. Although monoaxial screws have improved rotational control compared with polyaxial screws, their use may increase screw-bone interface or vertebral endplate forces if not inserted in an exactly straight trajectory. Uniaxial screws potentially decrease these forces while retaining the advantages of monoaxial screws with respect to better rotational control. The purpose of this study was to compare the vertebral endplate forces with monoaxial or uniaxial screws when being reduced to a rod. Thirty-two plastic, surrogate T11 vertebrae were prepared with monoaxial (n=16) or uniaxial (n=16) screws. Screw angles relative to inferior vertebral endplates were assessed with lateral radiographs. The vertebrae were fixed to a load cell, and loads were measured as the screw was reduced to a rod. Monoaxial screws demonstrated a linear progression of endplate force with increasing screw angle. Uniaxial screws demonstrated minimal endplate force until approximately 20°, coinciding with screwhead excursion angle. As this maximum excursion angle was passed, uniaxial screws demonstrated a force slope similar to the monoaxial screws.The measured endplate forces should be equivalent to forces at the screw-bone interface. The reduced force with uniaxial screws is expected to have less cranial-caudal plow potential as the screw is coupled to a rod for deformity correction. This could have potential implications for screw failure, especially in less dense bone. PMID:23027492

Essig, David A; Miller, Christopher P; Xiao, Ming; Ivancic, Paul; Jegede, Kola; Badrinath, Raghav; Smith, Brian G; Grauer, Jonathan N

2012-10-01

103

Unilateral molar distalization with a modified slider.  

PubMed

Although there are numerous publications on bilateral non-compliance molar distalization appliances, there is limited information on problems such as asymmetrical unilateral Class II malocclusions. The aim of the present investigation was to examine the distalization of molars unilaterally in patients with a unilateral Class II molar relationship utilizing a Keles Slider, designed without a bite plane. Ten girls (mean age 13.94 +/- 2.13 years) and seven boys (mean age 13.12 +/- 1.51 years) comprised the study material. Following insertion of the appliance, the patients were seen monthly and the screw was reactivated every 2 months. After a super-Class I molar relationship was achieved, the appliance was removed and the molars were stabilized with a Nance appliance for 2 months before the second-phase of orthodontic treatment. The Nance appliance was maintained in the palate until the end of canine distalization. Lateral cephalometric radiographs were obtained before and immediately after insertion of the molar distalizer. The results showed that the maxillary first molars were distalized bodily on average by 2.85 mm. The maxillary first premolars moved forward bodily 2 mm and were extruded 2.03 mm. In all, 1.32 mm of protrusion, 1.12 mm of extrusion, and 1.79 degrees of proclination of the upper incisors were observed. The mandibular incisors and mandibular molars erupted 0.83 and 0.95 mm, respectively. The unilateral Keles Slider distalized molars successfully to a Class I molar relationship. PMID:16648210

Sayinsu, Korkmaz; Isik, Fulya; Allaf, Ferdi; Arun, Tülin

2006-04-28

104

[Distal radio-ulnar prosthesis].  

PubMed

Many procedures have been proposed for the treatment of traumatic painful instabilities of the Distal Radio-Ulnar Joint (DRUJ). Moore-Darrach, Milch, Baldwin, Bowers, Kapandji-Sauvé. Except for the Milch procedure, the risk of painful instability of the ulnar stump is real, but not very frequent if the technique is correctly applied. When this complication occurs, the best way to ensure the ulnar stump stabilization is mechanical, by mean of a DRUJ Prosthesis which we were the first to imagine and build. Used in two cases, with or without remnant ulnar head, these two types of prosthesis seem to have been favourable. Obviously, it is too early to know the final value of this prosthesis, based only on two cases, but it seemed important to make it known as an additional possibility in the treatment of the DRUJ problems. These two types of prosthesis are conceived on original principles: cementless fixation but with screws and nuts giving immediate and definitive stability and allowing a fast rehabilitation. The articular pieces are composite, metal on H.D. Polythylene. The articular surface is spherical permitting all the mobilities of this complex joint. The two articular surfaces are supported by two pieces: the proximal part, holding a hollow hemisphere, inserted in the ulna and the same for the two types of prosthesis, and a distal part, holding the sphere; this part is different according to the type of the prosthesis. We are well aware that in time and with clinical experience, some of its secondary characteristics will evolve, mainly its fixation system. At the present time this prosthesis is indicated in two "second look" situations: painful ulnar stump instability after a Kapandji-Sauvé procedure, and after a Moore-Darrach procedure. Perhaps it will be used in unstable stumps after a Bowers procedure? It is possible that this prosthesis will be used primarlly in the future when its reliability has been definitively established. We are working towards this objective. PMID:1280973

Kapandji, A I

1992-01-01

105

Parallelization of the simplex method using the quadrant interlocking factorization  

SciTech Connect

This dissertation considers the parallelization of the simplex method of linear programming. Current implementations of the simplex method on sequential computers are based on a triangular factorization of the inverse of the current basis. An alternative decomposition designed for parallel computation, called the quadrant interlocking factorization, has previously been proposed for solving linear systems of equations. This research presents the theoretical justification and algorithms required to implement this new factorization in a simplex-based linear-programming system. Four algorithms are presented for updating the quadrant-interlocking factorization of the basis matrix when modified by a rank-one matrix. Parallel algorithms for producing the factorization in product form and for solving the linear systems of the simplex method are developed. The computations are scheduled to minimize the total execution time on a multiple-instructions multiple-data (MIMD) parallel computer that incorporates p identical processors sharing a common memory.

Zaki, H.A.

1987-01-01

106

NATIONAL SYNCHROTRON LIGHT SOURCE MEDICAL PERSONNEL PROTECTION INTERLOCK  

SciTech Connect

This report is founded on reports written in April 1987 by Robert Hettel for angiography operations at the Stanford Synchrotron Research Laboratory (SSRL) and a subsequent report covering angiography operations at the National Synchrotron Light Source (NSLS); BNL Informal Report 47681, June 1992. The latter report has now been rewritten in order to accurately reflect the design and installation of a new medical safety system at the NSLS X17B2 beamline Synchrotron Medical Research Facility (SMERF). Known originally as the Angiography Personnel Protection Interlock (APPI), this system has been modified to incorporate other medical imaging research programs on the same beamline and thus the name has been changed to the more generic Medical Personnel Protection Interlock (MPPI). This report will deal almost exclusively with the human imaging (angiography, bronchography, mammography) aspects of the safety system, but will briefly explain the modular aspects of the system allowing other medical experiments to be incorporated.

BUDA,S.; GMUR,N.F.; LARSON,R.; THOMLINSON,W.

1998-11-03

107

Logical consideration on lockout and trapped key interlock for machine.  

PubMed

"Lockout" is an important method for hazardous energy control to protect humans working at a place where they may be injured by unexpected release of hazardous energy. Actually, this administrative control is used in order to compensate for the incompleteness of the ZMS (Zero Mechanical State). This paper proposes the basic requirements for the "Lockout" used for machine maintenance work by applying the "principle of safety confirmation". In view of the above, the relation of "locking up the power switch in the OFF position", "withdrawing and possessing the key for hostage control" and "unlocking the movable guard for accessing to the working space" of the "trapped key interlock", which is alternative to "Lockout", should be made unate in terms of system. This paper formulates these interrelations, presents them in the form of interlock structure, and shows an example of configuration that can meet the required safety functions. PMID:20720338

Kimura, Makoto; Sugimoto, Noboru

2010-01-01

108

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage  

Microsoft Academic Search

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG

Gero S. M Kinzinger; Ulrike B Fritz; Franz-Günter Sander; Peter R Diedrich

2004-01-01

109

Formal Verification of a Railway Interlocking System using Model Checking  

Microsoft Academic Search

.   In this paper we describe an industrial application of formal methods. We have used model checking techniques to model and\\u000a formally verify a rather complex software, i.e. part of the “safety logic” of a railway interlocking system. The formal model\\u000a is structured to retain the reusability and scalability properties of the system being modelled. Part of it is defined

Alessandro Cimatti; Fausto Giunchiglia; Giorgio Mongardi; Dario Romano; Fernando Torielli; Paolo Traverso

1998-01-01

110

116. Photocopied August 1978. NEW INTERLOCKING STEEL SHEET PILING AT ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

116. Photocopied August 1978. NEW INTERLOCKING STEEL SHEET PILING AT PENSTOCK 52 IN THE FALL OF 1926. THE PILES FOR SUPPORTING THE HORIZONTAL ELEMENTS OF THE NEW FOREBAY APRON ARE IN PLACE BETWEEN THE NEW SHEET PILING AND THE FOREBAY WALL. VISIBLE BEYOND THE NEW SHEET PILING IS THE TIMBER SHEET PILING DRIVEN IN 1903 BY VON SCHON TO PREVENT WASHOUTS. (1006) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

111

Interlock Formation and Coiling of Meiotic Chromosome Axes During Synapsis  

PubMed Central

The meiotic prophase chromosome has a unique architecture. At the onset of leptotene, the replicated sister chromatids are organized along an axial element. During zygotene, as homologous chromosomes pair and synapse, a synaptonemal complex forms via the assembly of a transverse element between the two axial elements. However, due to the limitations of light and electron microscopy, little is known about chromatin organization with respect to the chromosome axes and about the spatial progression of synapsis in three dimensions. Three-dimensional structured illumination microscopy (3D-SIM) is a new method of superresolution optical microscopy that overcomes the 200-nm diffraction limit of conventional light microscopy and reaches a lateral resolution of at least 100 nm. Using 3D-SIM and antibodies against a cohesin protein (AFD1/REC8), we resolved clearly the two axes that form the lateral elements of the synaptonemal complex. The axes are coiled around each other as a left-handed helix, and AFD1 showed a bilaterally symmetrical pattern on the paired axes. Using the immunostaining of the axial element component (ASY1/HOP1) to find unsynapsed regions, entangled chromosomes can be easily detected. At the late zygotene/early pachytene transition, about one-third of the nuclei retained unsynapsed regions and 78% of these unsynapsed axes were associated with interlocks. By late pachytene, no interlocks remain, suggesting that interlock resolution may be an important and rate-limiting step to complete synapsis. Since interlocks are potentially deleterious if left unresolved, possible mechanisms for their resolution are discussed in this article.

Wang, Chung-Ju Rachel; Carlton, Peter M.; Golubovskaya, Inna N.; Cande, W. Zacheus

2009-01-01

112

Modular safety interlock system for high energy physics experiments  

SciTech Connect

A frequent problem in electronics systems for high energy physics experiments is to provide protection for personnel and equipment. Interlock systems are typically designed as an afterthought and as a result, the working environment around complex experiments with many independent high voltages or hazardous gas subsystems, and many different kinds of people involved, can be particularly dangerous. A set of modular hardware has been designed which makes possible a standardized, intergrated, hierarchical system's approach and which can be easily tailored to custom requirements.

Kieffer, J.; Golceff, B.V.

1980-10-01

113

Access control and interlock system at the Advanced Photon Source  

SciTech Connect

The Advanced Photon Source (APS) consists of a linac, position accumulator ring (PAR), booster synchrotron, storage ring, and up to 70 experimental beamlines. The Access Control and Interlock System (ACIS) utilizes redundant programmable logic controllers (PLCs) and a third hard-wired chain to protect personnel from prompt radiation generated by the linac, PAR, synchrotron, and storage ring. This paper describes the ACIS`s design philosophy, configuration, hardware, functionality, validation requirements, and operational experience.

Forrestal, J.; Hogrefe, R.; Knott, M.; McDowell, W.; Reigle, D.; Solita, L.; Koldenhoven, R.; Haid, D. [Argonne National Lab., IL (United States). Advanced Photon Source

1997-08-01

114

Neutral beam interlock system on TFTR using infrared pyrometry  

SciTech Connect

Although the region of the TFTR vacuum vessel wall which is susceptible to damage by neutral beam strike is armored with a mosaic of TiC-clad POCO graphite titles, at power deposition levels above 2.5 kW/cm/sup 2/ the armor surface temperature exceeds 1200/sup 0/C within 250 ms and itself becomes susceptible to damage. In order to protect the wall armor, a neutral beam interlock system based on infrared pyrometry measurement of the armor surface temperature was installed on TFTR. For each beamline, a three-fiber-optic telescope views three areas of approx.30 cm diameter centered on the armor hot spots for the three ion sources. Each signal is fiber-optic coupled to a remote 900 nm pyrometer which feeds analog signals to the neutral beam interrupt circuits. The pyrometer interlock system is designed to interrupt each of the twelve ion sources independently within 10 ms of the temperature exceeding a threshold settable in the range of 500 to 2300/sup 0/C. A description of the pyrometer interlock system and its performance will be presented.

Medley, S.S.; Kugel, H.W.; Kozub, T.A.; Lowrance, J.L.; Mastrocola, V.; Renda, G.; Young, K.M.

1986-06-01

115

Can Interlocked Grains Reduce the Mobility of Gravel Bed Rivers?  

NASA Astrophysics Data System (ADS)

Channel stability of gravel bed rivers is enhanced by coarsening and structural modification of the bed, which determines the bed's resistance to entrainment, and hence the mobility of particles on the bed. In this study we propose a grain-scale classification system that qualitatively and quantitatively describes grain-to-grain interactions of fluvially re-worked gravel beds. The quantitative measure takes the form of the ratio of the vertical plucking force (Fv) required to remove a grain from a static, dry bed to the weight of the grain (Fw). Fv/Fw is an empirical measure of the restraining effect of neighboring grains and can range between 1 when the bed is loosely packed to >> 1 when the grains are interlocked. Preliminary results from a large (30 m long and 0.86 m wide) flume channel suggest that individual grains range from being loosely arranged on the bed (mean Fv/Fw approx. = 1) to highly packed or interlocked grains (mean Fv/Fw approx. = 5). Preliminary data from ephemeral rivers suggests a mean Fv/Fw ratio of approximately 3. Other packing arrangements observed and measured both in the flume and in the field include imbricated, embedded, and partially buried grains. These results suggest that the equations for predicting the mobility of coarse heterogeneous sediments may require reexamination before application to channels downstream of dams and in other low sediment supply channels where tight interlocking is expected to occur.

Wydzga, A. M.; Hassan, M. A.; Venditti, J. G.; Dunne, T.

2005-12-01

116

Flammable gas interlock spoolpiece flow response test report  

SciTech Connect

The purpose of this test report is to document the testing performed under the guidance of HNF-SD-WM-TC-073, {ital Flammable Gas Interlock Spoolpiece Flow Response Test Plan and Procedure}. This testing was performed for Lockheed Martin Hanford Characterization Projects Operations (CPO) in support of Rotary Mode Core Sampling jointly by SGN Eurisys Services Corporation and Numatec Hanford Company. The testing was conducted in the 305 building Engineering Testing Laboratory (ETL). NHC provides the engineering and technical support for the 305 ETL. The key personnel identified for the performance of this task are as follows: Test responsible engineering manager, C. E. Hanson; Flammable Gas Interlock Design Authority, G. P. Janicek; 305 ETL responsible manager, N. J. Schliebe; Cognizant RMCS exhauster engineer, E. J. Waldo/J. D. Robinson; Cognizant 305 ETL engineer, K. S. Witwer; Test director, T. C. Schneider. Other support personnel were supplied, as necessary, from 305/306 ETL. The testing, on the flammable Gas Interlock (FGI) system spoolpiece required to support Rotary Mode Core Sampling (RMCS) of single shell flammable gas watch list tanks, took place between 2-13-97 and 2-25-97.

Schneider, T.C., Fluor Daniel Hanford

1997-03-24

117

Interlock and control systems for a sector at the APS  

SciTech Connect

This report describes some basic elements of the various Interlock and Control Systems associated with the Front Ends and Beamlines. Some systems serve only the Front Ends; other serve both the Front Ends and the Beamlines, while the Experimental Controls are for the Beamlines only. Specific system requirements and design specifications are not in the scope of this report. They will be presented in the descriptions of the Experimental Floor Personnel Safety System (XF-PSS or, more often, PSS) and Equipment Protection System (XF-EPS or EPS), which will expand on the overview presented here. The main focus here is on the PSS and EPS in the context of their interactions and interface to the Storage Ring Access Control Interlock System (ACIS), and Ring Controls. The other systems are only mentioned to make the cross section complete. This paper is the first in series of three reports that jointly provide a full description of sector interlocks. The second report describes the PSS, and the third -- the EPS.

Friedman, N.

1993-09-09

118

Fuzzy logic control of automated screw fastening  

Microsoft Academic Search

In this paper, we present an intelligent control strategy for automated screw fastening. In automated assembly processes, there are often found dedicated stations for various types\\/sizes of screw fastening. Problems found in current processes include cross-threading, screw jamming, slippage and the need to apply precise torque. The intelligent controller developed here supervises the integrated process of an electric driver mounted

Nitin Dhayagude; Zhiqiang Gao; Fouad Mrad

1996-01-01

119

Fuzzy logic control of automated screw fastening  

Microsoft Academic Search

In this paper, we present an intelligent control strategy for automated screw fastening. In automated assembly processes, there is a large number of dedicated stations for various types\\/sizes of screw fastening. Problems found in current processes include cross-threading, screw jamming, slippage and the need to apply precise torque. The intelligent controller developed supervises the integrated process of an electric driver

Fouad Mrad; Zhiqiang Gao; Nitin Dhayagude

1995-01-01

120

Distal movement of mandibular molars in adult patients with the skeletal anchorage system  

Microsoft Academic Search

The skeletal anchorage system (SAS) consists of titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible, or in both, as absolute orthodontic anchorage units. Distalization of the molars has been one of the most difficult biomechanical problems in traditional orthodontics, particularly in adults and in the mandible. However, it has now become

Junji Sugawara; Takayoshi Daimaruya; Mikako Umemori; Hiroshi Nagasaka; Ichiro Takahashi; Hiroshi Kawamura; Hideo Mitani

2004-01-01

121

Surgeon Perception of Cancellous Screw Fixation.  

PubMed

OBJECTIVES:: The ability of surgeons to optimize screw insertion torque in nonlocking fixation constructs is important for stability, particularly in osteoporotic and cancellous bone. This study evaluated screw torque applied by surgeons during synthetic cancellous fixation. It evaluated the frequency that screws were stripped by the surgeon, factors associated with screw stripping, and the ability of surgeons to recognize it. METHODS:: Ten surgeons assembled screw and plate fixation constructs into three densities of synthetic cancellous bone while screw insertion torque and axial force were measured. For each screw, the surgeon recorded a subjective rating as to whether or not the screw had been stripped. Screws were then advanced past stripping and stripped screws were identified by comparing the insertion torque applied by the surgeon to the measured stripping torque. RESULTS:: Surgeons stripped 109 of 240 screws (45.4%) and did not recognize stripping 90.8% of the time that it occurred. The tendency to strip screws was highly variable among individual surgeons (ranging from 16.7% to 83.3% stripped, p < 0.0001) and did not correlate to synthetic bone density in the range tested (p = 0.186), nor to rank as resident or attending surgeon (p = 0.437). Screws that were correctly recognized as stripped retained a mean 55.0% of maximum torque, less than when stripping was not recognized (79.6%, p = 0.005). CONCLUSIONS:: Surgeon perception is not reliable at preventing and detecting screw stripping at clinical torque levels in synthetic cancellous bone. Less aggressive insertion or standardized methods of insertion may improve the stability of nonlocking screw and plate constructs. PMID:23782959

Stoesz, Michael J; Gustafson, Peter A; Patel, Bipinchandra; Jastifer, James R; Chess, Joseph L

2013-06-18

122

Vascular injury involving proximal medial-to-lateral oblique locking screw insertion in tibial intramedullary nailing.  

PubMed

Orthopaedic surgeons have reported increased neurologic complications with the employment of next-generation tibial nail fixation with variable proximal and distal locking options. However, vascular injury due to oblique screw placement has not been documented. We describe a case in which a medial-to-lateral oblique locking screw led to significant vascular injury. The judicious use of these screws and their relative contribution to fracture stability should be carefully considered for individual cases. Additionally, drill penetration through the far tibial cortex may not be obvious and utilizing oscillation or reverse drilling techniques may be of benefit. Lastly, the forward thrust of the popliteal artery with the use of a positioning bump in the popliteal fossa may place the vascular structure at increased risk of injury. Employing means to avoid these injuries and minimize risks in pertinent patients is of utmost importance. PMID:21846016

Hussain, Waqas; Balach, Tessa; Leland, J Martin

2011-06-01

123

Distal Radius Fracture (Colles' Fracture)  

MedlinePLUS

... 2013 American Academy of Orthopaedic Surgeons Distal Radius Fractures (Broken Wrist) The radius is the larger of ... the wrist is called the distal end. A fracture of the distal radius occurs when the area ...

124

Metallurgical examination of gun barrel screws  

SciTech Connect

The examination was conducted to determine the extent of degradation that had occurred after a series of firings; these screws prevent live rounds of ammunition from being loaded into the firing chamber. One concern is that if the screw tip fails and a live round is accidentally loaded into the chamber, a live round could be fired. Another concern is that if the blunt end of the screw begins to degrade by cracking, pieces could become small projectiles during firing. All screws used in firing 100 rounds or more exhibited some degree degradation, which progressively worsened as the number of rounds fired increased. (SEM, metallography, x-ray analysis, and microhardness were used.) Presence of cracks in these screws after 100 fired rounds is a serious concern that warrants the discontinued use of these screws. The screw could be improved by selecting an alloy more resistant to thermal and chemical degradation.

Bird, E.L.; Clift, T.L.

1996-06-01

125

National Synchrotron Light Source angiography personnel protection interlock  

SciTech Connect

This document has been written to describe the safety system operation at the NSLS X17B2 beamline Synchrotron Medical Research Facility (SMERF). The angiography exposure process involves scanning a patient up and down through dual fixed-position x-ray beams; exposure is controlled by opening and closing a fast-acting Safety Shutter mechanism at precise times in relation to the up and down motion of the scan chair. The fast-acting Safety Shutter mechanism is the primary radiation-stopping element protecting the patient while the chair is at rest and while it is reversing directions during the scan. Its fail-safe and fast operation is essential for the safety of the patient. Operation of X17B2 as a human subject angiography station necessitates the implementation of a personnel protection interlock system that, in conjunction with the Safety Shutters: permits safe access to the patient exposure area while the synchrotron radiation beam is illuminating the upstream dual energy monochromator; allows a patient to be imaged by the monochromatized beam under the supervision of a Responsible Physician, with scan chair motion and precision shutter actuation regulated by an angiography control computer, while providing a suitable number of safeguards against accidental radiation exposure; has different modes of operation to accommodate equipment set-up, test, and calibration; and patient exposure; and ensures the quick extinction of the beam if a potentially unsafe condition is detected. The interlock system which performs these safety functions is called the Angiography Personnel Protection Interlock (APPI). The APPI Document is organized such that the level of detail changes from a general overview to detailed engineering drawings of the hardware system.

Gmuer, N.; Larson, R.; Thomlinson, W.

1992-06-01

126

National Synchrotron Light Source medical personnel protection interlock  

SciTech Connect

This report is founded on reports written in April 1987 by Robert Hettel for angiography operations at the Stanford Synchrotron Research Laboratory (SSRL) and a subsequent report covering angiography operations at the National Synchrotron Light Source (NSLS); BNL Informal Report 47681, June 1992. The latter report has now been rewritten in order to accurately reflect the design and installation of a new medical safety system at the NSLS X17B2 beamline Synchrotron Medical Research Facility (SMERF). Known originally as the Angiography Personnel Protection Interlock (APPI), this system has been modified to incorporate other medical imaging research programs on the same beamline and thus the name has been changed to the more generic Medical Personnel Protection Interlock (MPPI). This report will deal almost exclusively with the human imaging (angiography, bronchography, mammography) aspects of the safety system, but will briefly explain the modular aspects of the system allowing other medical experiments to be incorporated. This MPPI report is organized such that the level of detail changes from a general overview to detailed engineering drawings of the hardware system. The general overview is presented in Section 1.0, MPPI Operational Mode and Procedures. The various MPPI components are described in detail in Section 2.0. Section 3.0 presents some simplified logic diagrams and accompanying text. This section was written to allow readers to become familiar with the logic system without having to work through the entire set of detailed engineering drawings listed in the Appendix. Detailed logic specifications are given in Section 4.0. The Appendix also contains copies of the current MPPI interlock test procedures for Setup and Patient Modes.

Buda, S.; Gmuer, N.F.; Larson, R.; Thomlinson, W.

1998-11-01

127

An evaluation of the Swedish ignition interlock program.  

PubMed

The Swedish alcohol ignition interlock program for driving while intoxicated (DWI) offenders, both first-time as well as multiple offenders, was launched as a pilot project in 1999. It is a volunteer program and differs in some respects from other programs: It covers a period of 2 years, it includes very strict medical regulations entailing regular checkups by a physician, it does not require a prior period of hard suspension, and it focuses strongly on changes in alcohol habits. Records from the 5 years prior to the offence showed that DWI offenders are generally in a high-risk category long before their offense, with a four to five times higher accident rate (road accidents reported by the police) and a three to four times higher rate of hospitalization due to a road accident. Only 12% of the eligible DWI offenders took part in the program and, of these, 60% could be diagnosed as alcohol dependent or alcohol abusers. During the program, alcohol consumption is monitored through self-esteem questionnaires (AUDIT) and five different biological markers. Our data show a noticeable reduction in alcohol consumption among the interlock users. This, combined with the high rate of compliance with the regulations, probably accounts for the fact that there was no case of recidivism during the program. Preliminary findings also suggest a reduction in the annual accident rate for interlock users while in the program. It still is too early to draw any conclusions concerning the rate of recidivism after completion of the program due to an insufficient amount of data for analysis. Nevertheless, the preliminary results are so promising that the program will now be expanded to cover all of Sweden as well as to include all driver's license categories. PMID:16801125

Bjerre, Bo

2003-01-01

128

Interlocking director positions: an area of concern for electric utilities  

SciTech Connect

Congress passed the Federal Power Act in 1935 in an effort to remedy the abuses associated with the pyramiding of holding companies in the electric utility industry. The recent amendment to Section 305, with its broad requirements for reporting interlocking positions, may make it more difficult for electric utilities to get highly qualified individuals to serve as directors. Whether the increased reporting requirements will lead to further amendments of Section 305(b) remains uncertain, but the reports now required by Section 305(c) may be one informational data base for amendments to Section 305(b) extending the Federal Power Commission's jurisdiction. 52 references.

Merriman, R.M.; Tiano, J.R.

1980-01-01

129

Use of a Fibular Strut Allograft in an Osteoporotic Distal Humerus Fracture  

PubMed Central

In 2004, nearly 120 000 fragility fractures of the humerus were reported. As the US population ages, this number is expected to increase. Fractures of the distal humerus can be treated in a closed or open fashion. Open treatment includes open reduction and internal fixation or total elbow arthroplasty. Open reduction and internal fixation typically involves dual plating for increased stability and early mobility. We present a case in which dual plating failed due to lack of screw purchase in osteoporotic bone. This patient’s fracture was then revised with the use of a fibular strut allograft for improved stability and screw purchase. This method of fixation has not previously been described in the distal humerus and may prove useful in open fixation of osteoporotic distal humerus fractures.

Hildebrand, Gregory R.; Wright, David M.; Marston, Scott B.; Switzer, Julie A.

2012-01-01

130

Helical screw expander evaluation project  

NASA Astrophysics Data System (ADS)

A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

McKay, R.

1982-03-01

131

A comparative analysis of Ender's-rod and compression screw and side plate fixation of intertrochanteric fractures of the hip.  

PubMed

The purpose of this study is to compare the results of compression screw fixation and Ender's rods in the treatment of intertrochanteric fractures of the hip. A retrospective analysis of 77 cases of both unstable and stable cases of intertrochanteric fractures showed a higher incidence of complications in the Ender's group; these included backing out, distal femur fracture, need for a secondary procedure, external rotation deformity, and knee pain. Indications for the use of Ender's rods may be found among patients with burns, soft-tissue injuries of the proximal thigh, and patients refusing blood transfusions. Wiring of the distal ends of Ender's rods prevents backing out of the rods. Dacron tape has also been successfully used to prevent the distal ends of the rods from backing out in the last six of the 77 cases. The compression hip screw is a preferred treatment of choice in both stable and unstable intertrochanteric fractures. PMID:2364601

Rao, J P; Hambly, M; King, J; Benevenia, J

1990-07-01

132

12 CFR 212.9 - Effect of Interlocks Act on Clayton Act.  

Code of Federal Regulations, 2010 CFR

... false Effect of Interlocks Act on Clayton Act. 212.9 Section 212.9 Banks...212.9 Effect of Interlocks Act on Clayton Act. The Board regards the provisions...first three paragraphs of section 8 of the Clayton Act (15 U.S.C. 19) to have...

2009-01-01

133

12 CFR 212.9 - Effect of Interlocks Act on Clayton Act.  

Code of Federal Regulations, 2010 CFR

... false Effect of Interlocks Act on Clayton Act. 212.9 Section 212.9 Banks...212.9 Effect of Interlocks Act on Clayton Act. The Board regards the provisions...first three paragraphs of section 8 of the Clayton Act (15 U.S.C. 19) to have...

2010-01-01

134

49 CFR 1242.17 - Signals and interlockers (accounts XX-17-19 and XX-18-19).  

Code of Federal Regulations, 2012 CFR

... false Signals and interlockers (accounts XX-17-19 and XX-18-19). 1242...DEPARTMENT OF TRANSPORTATION (CONTINUED) ACCOUNTS, RECORDS AND REPORTS SEPARATION...1242.17 Signals and interlockers (accounts XX-17-19 and XX-18-19)....

2012-10-01

135

Design of a robotic tool for percutaneous instrument distal tip repositioning.  

PubMed

Manually performed image-guided percutaneous procedures are limited by targeting errors due to instrument misalignment, deflection and an inability to reposition the distal tip of the instrument after it has been percutaneously inserted. These limitations result in suboptimal instrument positioning that limits diagnosis and treatment for a variety of procedures as well as excessive procedure time and radiation dose (in the case of x-ray based imaging). Hence we are developing a robotic tool capable of repositioning the distal tip of a percutaneous instrument after a single insertion into the body. It is based on the concept of deploying a super-elastic pre-curved stylet from a concentric straight cannula. The proximal end of the cannula is attached to the distal end of a screw-spline that enables it to be translated and rotated with respect to the casing. Translation of the stylet relative to the cannula is achieved with a second threaded screw with a splined groove. The device is made of mostly plastic components and actuation is achieved using micro-stepper motors. Measurements of the maximum axial force for the cannula screw-spline and stylet screw were found to match those from design calculations. Evaluation of the mechanism positioning capability demonstrated sub-millimeter and sub-degree translation and angular accuracy. We foresee this robotic tool having wide application across a range of procedures such as biopsy, thermal ablation and brachytherapy seed placement. PMID:22254751

Walsh, Conor James; Franklin, Jeremy; Slocum, Alexander H; Gupta, Rajiv

2011-01-01

136

Comparative endurance testing of the Biomet Matthews Nail and the Dynamic Compression Screw, in simulated condylar and supracondylar femoral fractures  

PubMed Central

Background The dynamic compression screw is a plate and screws implant used to treat fractures of the distal femur. The Biomet Matthews Nail is a new retrograde intramedullary nail designed as an alternative surgical option to treat these fractures. The objective of this study was to assess the comparative endurance of both devices. Method The dynamic compression screw (DCS) and Biomet Matthews Nail (BMN) were implanted into composite femurs, which were subsequently cyclically loaded using a materials testing machine. Simulated fractures were applied to each femur prior to the application of load. Either a Y type fracture or a transverse osteotomy was prepared on each composite femur using a jig to enable consistent positioning of cuts. Results The Biomet Matthews Nail demonstrated a greater endurance limit load over the dynamic compression screw in both fracture configurations. Conclusion The distal locking screws pass through the Biomet Matthews Nail in a unique "cruciate" orientation. This allows for greater purchase in the bone of the femoral condyle and potentially improves the stability of the fracture fixation. As these fractures are usually in weak osteoporotic bone, the Biomet Matthews Nail represents a favourable surgical option in these patients.

O'Connor-Read, Laurence M; Davidson, Jerome A; Davies, Benjamin M; Matthews, Michael G; Smirthwaite, Paul

2008-01-01

137

Biodegradable Interference Screw Fixation Exhibits Pull-Out Force and Stiffness Similar to Titanium Screws  

Microsoft Academic Search

Recently, increased interest in biodegradable interference screws for bone-tendon-bone graft fixation has led to numerous screws becoming available. The implants are made from different polymers and have different designs, which might influence their mechanical properties. Several studies have reported a wide range of mechanical results for these screws using different biomechanical models. The aim of the present study is to

Andreas Weiler; Henning J. Windhagen; Michael J. Raschke; Andrea Laumeyer; Reinhard F. G. Hoffmann

1998-01-01

138

[Discrete distal gangrene].  

PubMed

The authors present their statistical findings from 114 cases of discrete distal gangrene. They stress the importance of a rigorous methodology to detect mechanical causes from the thoracic outlet syndrome and immunological causes, predominantly scleroderma, especially in women. It is important not to overlook blood diseases nor those cases which are a presentation of underlying cancer. Finally, the iatrogenic cause is now well known. Treatment depends on the causes of this distal lesion. However, in cases of severe connective tissue disease, the use of plasmapheresis is beginning to give interesting results. PMID:6842102

Cloarec, M; Graisely, B; Dumas, R; Caillard, P; Wurm, M; Le Moigne, C; Solvay, H; Kahn, M

1983-01-01

139

[Reconstruction after distal gastrectomy].  

PubMed

To select the best reconstruction method after distal gastrectomy, we analyzed the endoscopic features and gastrointestinal quality of life in patients who underwent either Billroth I or Roux-en-Y reconstruction. The Billroth I procedure is simpler, more physiologically normal, and allows easier endoscopic access to the duodenum. Although it is more complex, the Roux-en Y procedure can prevent bile reflux, is safe, and is superior to the Billroth I procedure both functionally and symptomatically. The Roux-en-Y procedure is thus one of the best options after distal gastrectomy. Selection of the reconstruction procedure should be based on clinical evidence. PMID:18939460

Katai, Hitoshi; Nunobe, Souya; Saka, Makoto; Fukagawa, Takeo; Sano, Takeshi

2008-09-01

140

The distal biceps tendon.  

PubMed

Distal biceps tendon ruptures continue to be an important injury seen and treated by upper extremity surgeons. Since the mid-1980s, the emphasis has been placed on techniques that limit complications or improve initial tendon-to-bone fixation strength. Recently, basic science research has expanded the knowledge base regarding the biceps tendon structure, footprint anatomy, and biomechanics. Clinical data have further delineated the results of conservative and surgical management of both partial and complete tears in acute or chronic states. The current literature on the distal biceps tendon is described in detail. PMID:23474326

Schmidt, Christopher C; Jarrett, Claudius D; Brown, Brandon T

2013-03-07

141

21 CFR 872.4880 - Intraosseous fixation screw or wire.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Intraosseous fixation screw or wire. 872.4880 Section 872... § 872.4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended...

2010-04-01

142

21 CFR 872.4880 - Intraosseous fixation screw or wire.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Intraosseous fixation screw or wire. 872.4880 Section 872... § 872.4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended...

2009-04-01

143

Results of the Bosworth method for unstable fractures of the distal clavicle  

Microsoft Academic Search

Summary.  \\u000a Eleven consecutive Neer’s type II unstable fractures of the distal third of the clavicle were treated by open reduction and\\u000a internal fixation, using a temporary Bosworth-type screw. In all cases, fracture healing occurred within 10 weeks. Shoulder\\u000a function was restored to the pre-injury level. A Bosworth-type screw fixation is a relatively easy and safe technique of open\\u000a reduction and

H. Yamaguchi; H. Arakawa; M. Kobayashi

1998-01-01

144

Distale Protektionsverfahren beim Karotisstent  

Microsoft Academic Search

Zusammenfassung Die endovaskuläre Behandlung von Karotisstenosen findet zunehmende Verbreitung. Bei der Karotisstentimplantation werden häufig temporäre Filter oder Okklusionsballons in die A. carotis interna distal der Stenose eingesetzt, um einen zusätzlichen Schutz vor zerebralen Embolien zu erreichen. Die Notwendigkeit einer solchen distalen Protektion ist wissenschaftlich allerdings immer noch umstritten. Die folgende Übersicht über die bestehenden Techniken und deren Ergebnisse soll eine kritische

J. Berkefeld; R. du Mesnil de Rochemont; M. Sitzer; F. E. Zanella

2004-01-01

145

Two potential causes of EPL rupture after distal radius volar plate fixation.  

PubMed

Rupture of the extensor pollicis longus tendon can occur after volar plate fixation of dorsally comminuted distal radius fractures. We attempted to identify the etiology of extensor pollicis longus tendon injury after volar plate fixation of the distal radius and potential solutions to this problem. After describing two case reports, we examine six cadaveric specimens and retrospectively review 10 selected patients to evaluate possible technique refinements to minimize damage to the extensor pollicis longus tendon during volar plating of the distal radius. We identify specific screw holes in three commercially available volar distal radius plates that direct the drill bit or prominent screw tips into the third extensor compartment. In addition, after reduction and plate fixation, bone fragments or dorsal gapping may predispose the extensor pollicis longus tendon to injury. We recommend either using shorter screw lengths or leaving the implicated plate holes unfilled. In addition, we suggest consideration of an open assessment of the third extensor compartment, if indicated, as performed through a small dorsal incision ulnar to Lister's tubercle. PMID:16770281

Benson, Eric C; DeCarvalho, Alex; Mikola, Elizabeth A; Veitch, John M; Moneim, Moheb S

2006-10-01

146

Detection of phosphatidylethanol (PEth) in the blood of drivers in an alcohol ignition interlock program  

PubMed Central

Objective The rate of failed interlock blood alcohol concentration (BAC) tests is a strong predictor of recidivism post-interlock and a partial proxy for alcohol use. Alcohol biomarkers measured at the start of an interlock program are known to correlate well with rates of failed BAC tests over months of interlock use. This study evaluates two methods of measuring low blood levels of the biomarker PEth (phosphatidylethanol). PEth is a 100% alcohol specific biomarker and strongly intercorrelated with several independent indicators of drinking driving risk, including 8 other biomarkers, 3 psychometric assessments, and the rate of failed interlock BAC tests during many months of interlock use. Does a more sensitive method of measuring PEth at program entry detect drinking even among those who subsequently log no failed interlock tests? Methods In a sample of 281 driver blood samples, PEth was measured by both high-performance liquid chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LCMSMS) in order to compare sensitivity and accuracy. The average rate of failed interlock BAC tests was the criterion measure for marker sensitivity. LCMSMS, calibrated to detect low levels of drinking as a possible measure of abstinence violation, was judged relative to the standard HPLC assay for PEth measured up to 4 µmol/L. Results The two methods showed a good quantitative relationship (r2>.86). LCMSMS detected positive PEth levels in samples that were below the limit of detection of the HPLC method. PEth measured by LCMSMS was positive for a higher proportion of DUI offenders who logged zero failed interlock BAC tests than were detected by HPLC. Conclusion Although HPLC is the widely used standard for measuring PEth in clinical alcoholism samples, the LCMSMS method, when calibrated to detect trace amounts of the major component of PEth, can detect abstinence levels of alcohol near zero intake and still correlate strongly with other indicators related to alcohol use and road safety.

Marques, Paul; Hansson, Therese; Isaksson, Anders; Walther, Lisa; Jones, Joseph; Lewis, Douglas; Jones, Mary

2011-01-01

147

Predicting cancellous bone failure during screw insertion.  

PubMed

Internal fixation of fractures often requires the tightening of bone screws to stabilise fragments. Inadequate application of torque can leave the fracture unstable, while over-tightening results in the stripping of the thread and loss of fixation. The optimal amount of screw torque is specific to each application and in practice is difficult to attain due to the wide variability in bone properties including bone density. The aim of the research presented in this paper is to investigate the relationships between motor torque and screw compression during powered screw insertion, and to evaluate whether the torque during insertion can be used to predict the ultimate failure torque of the bone. A custom test rig was designed and built for bone screw experiments. By inserting cancellous bone screws into synthetic, ovine and human bone specimens, it was established that variations related to bone density could be automatically detected through the effects of the bone on the rotational characteristics of the screw. The torque measured during screw insertion was found to be directly related to bone density and can be used, on its own, as a good predictor of ultimate failure torque of the bone. PMID:23466167

Reynolds, Karen J; Cleek, Tammy M; Mohtar, Aaron A; Hearn, Trevor C

2013-03-01

148

Metallurgical examination of gun barrel screws.  

National Technical Information Service (NTIS)

The examination was conducted to determine the extent of degradation that had occurred after a series of firings; these screws prevent live rounds of ammunition from being loaded into the firing chamber. One concern is that if the screw tip fails and a li...

E. L. Bird T. L. Clift

1996-01-01

149

Cost effectiveness of subaxial fusion--lateral mass screws versus transarticular facet screws.  

PubMed

As health care reform continues to evolve, demonstrating the cost effectiveness of spinal fusion procedures will be of critical value. Posterior subaxial cervical fusion with lateral mass screw and rod instrumentation is a well-established fixation technique. Subaxial transarticular facet fixation is a lesser known fusion technique that has been shown to be biomechanically equivalent to lateral mass screws for short constructs. Although there has not been a widespread adoption of transarticular facet screws, the screws potentially represent a cost-effective alternative to lateral mass rod and screw constructs. In this review, the authors describe an institutional experience with the use of lateral mass screws and provide a theoretical cost comparison with the use of transarticular facet screws. PMID:22746231

Ray, Wilson Z; Ravindra, Vijay M; Jost, Gregory F; Bisson, Erica F; Schmidt, Meic H

2012-07-01

150

Transarticular screw fixation using neuronavigation: Technique  

PubMed Central

Background: Transarticular screw placement needs highly accurate imaging. We assess the efficacy and accuracy of C1-C2 transarticular screw fixation using neuronavigation and also cast a technical note on the procedure. Materials and Methods: This study included a total of nine patients who underwent transarticular screw fixation using the neuronavigation system. A total of 15 screws were placed. All patients underwent postoperative CT scan with 3-Dimensional (3-D) reconstruction to check for the accuracy of implantation. Results: One patient had encroachment of the transverse foramen but there was no vertebral artery injury. There were no clinical complications or adverse sequelae. Conclusion: Neuronavigation is extremely helpful in C1-C2 transarticular screw fixation and gives excellent accuracy.

Dwarakanath, Srinivas; Suri, Ashish; Sharma, Bhavani Shankar

2007-01-01

151

Treatment of unstable distal radius fractures with the volar locking plate  

PubMed Central

Background Open reduction and internal fixation using an interlocking plate system has gained popularity for the treatment of dorsally displaced distal radius fractures. Purpose To evaluate the functional and radiological results of treating unstable distal radius fractures with the volar locking plate. Patients and methods A retrospective review was conducted of patients from one institution using the volar locking plate to treat intra-articular and extra-articular distal radius fractures. Unstable distal radius fractures in 15 patients, comprising 3 men and 12 women with a mean age of 64.4 years (34–76 years), were treated with a volar locking compression plate (Acu-Loc distal radius plate system; Acumed, Oregon, USA) and followed up for a minimum of 1 year. Fractures were classified using the AO classification. Radiographic parameters of preoperative, postoperative, and final follow-up radiographs were compared. The time to initiation of active range of motion was determined. Final follow-up range of motion and complications were reported. Results At final functional assessment, the scores of 5 patients were excellent, 7 patients good, and 3 patients fair according to Cooney's Clinical Scoring Chart. No non-union or infection occurred. Rupture of the flexor pollicis longus tendon occurred in 1 patient. Conclusion Treatment of unstable distal radius fractures with a volar locking plate leads to satisfactory results, provided the operative technique is carefully performed to prevent complications.

2011-01-01

152

Distal radioulnar joint injuries.  

PubMed

Distal radioulnar joint is a trochoid joint relatively new in evolution. Along with proximal radioulnar joint, forearm bones and interosseous membrane, it allows pronosupination and load transmission across the wrist. Injuries around distal radioulnar joint are not uncommon, and are usually associated with distal radius fractures,fractures of the ulnar styloid and with the eponymous Galeazzi or Essex_Lopresti fractures. The injury can be purely involving the soft tissue especially the triangular fibrocartilage or the radioulnar ligaments. The patients usually present with ulnar sided wrist pain, features of instability, or restriction of rotation. Difficulty in carrying loads in the hand is a major constraint for these patients. Thorough clinical examination to localize point of tenderness and appropriate provocative tests help in diagnosis. Radiology and MRI are extremely useful, while arthroscopy is the gold standard for evaluation. The treatment protocols are continuously evolving and range from conservative, arthroscopic to open surgical methods. Isolated dislocation are uncommon. Basal fractures of the ulnar styloid tend to make the joint unstable and may require operative intervention. Chronic instability requires reconstruction of the stabilizing ligaments to avoid onset of arthritis. Prosthetic replacement in arthritis is gaining acceptance in the management of arthritis. PMID:23162140

Thomas, Binu P; Sreekanth, Raveendran

2012-09-01

153

Distal radioulnar joint injuries  

PubMed Central

Distal radioulnar joint is a trochoid joint relatively new in evolution. Along with proximal radioulnar joint, forearm bones and interosseous membrane, it allows pronosupination and load transmission across the wrist. Injuries around distal radioulnar joint are not uncommon, and are usually associated with distal radius fractures,fractures of the ulnar styloid and with the eponymous Galeazzi or Essex_Lopresti fractures. The injury can be purely involving the soft tissue especially the triangular fibrocartilage or the radioulnar ligaments. The patients usually present with ulnar sided wrist pain, features of instability, or restriction of rotation. Difficulty in carrying loads in the hand is a major constraint for these patients. Thorough clinical examination to localize point of tenderness and appropriate provocative tests help in diagnosis. Radiology and MRI are extremely useful, while arthroscopy is the gold standard for evaluation. The treatment protocols are continuously evolving and range from conservative, arthroscopic to open surgical methods. Isolated dislocation are uncommon. Basal fractures of the ulnar styloid tend to make the joint unstable and may require operative intervention. Chronic instability requires reconstruction of the stabilizing ligaments to avoid onset of arthritis. Prosthetic replacement in arthritis is gaining acceptance in the management of arthritis.

Thomas, Binu P; Sreekanth, Raveendran

2012-01-01

154

Alignment of pedicle screws with pilot holes: can tapping improve screw trajectory in thoracic spines?  

PubMed Central

Pedicle screws are placed using pilot holes. The trajectory of pilot holes can be verified by pedicle sounding or radiographs. However, a pilot hole alone does not insure that the screw will follow the pilot hole. No studies have characterized the risk of misalignment of a pedicle screw with respect to its pilot hole trajectory. The objective of this study was to measure the misalignment angles between pedicle screws and pilot holes with or without tapping. Six human cadaveric thoracic spines were used. One hundred and forty pilot holes were created with a straight probe. Steel wires were temporarily inserted and their positions were recorded with CT scans. The left pedicles were tapped with 4.5 mm fluted tap and the right pedicles remained untapped. Pedicle screws (5.5 mm) were inserted into the tapped and untapped pedicles followed by CT scans. The trajectories of pilot holes and screws were calculated using three-dimensional vector analysis. A total of 133 pilot holes (95%) were inside pedicles. For the untapped side, 14 out of 68 (20%) screws did not follow the pilot holes and were outside the pedicles. For the tapped side, 2 out of 65 (3%) did not follow and breached the pedicles. The average misalignment angles between the screw and pilot hole trajectory were 7.7° ± 6.5° and 5.6° ± 3.2° for the untapped side and tapped side, respectively (P < 0.05). Most pedicle screws had lateral screw breach (13 out of 16) whereas most pilot holes had medial pedicle breach (6 out of 7). Tapping of pilot holes (1 mm undertap) helps align pedicle screws and reduces the risk of screw malposition. Although most pedicle screws had lateral breach, the risk of medial pedicle breach of the pilot holes must be recognized.

Erkan, Serkan; Hsu, Brian; Mehbod, Amir A.; Perl, John; Transfeldt, Ensor E.

2009-01-01

155

30 CFR 75.819 - Motor-starter enclosures; barriers and interlocks.  

Code of Federal Regulations, 2013 CFR

...LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.819 Motor-starter enclosures; barriers and interlocks. Compartment...

2013-07-01

156

Engineering of interlocked DNA G-quadruplexes as a robust scaffold  

PubMed Central

Interlock is a structural element in DNA G-quadruplexes that can be compared with the commonly used complementary binding of ‘sticky ends’ in DNA duplexes. G-quadruplex interlocking can be a basis for the assembly of higher-order structures. In this study, we formulated a rule to engineer (3 + 1) interlocked dimeric G-quadruplexes and established the folding topology of the designed DNA sequences by nuclear magnetic resonance spectroscopy. These interlocked G-quadruplexes are very stable and can serve as compact robust scaffolds for various applications. Different structural elements can be engineered in these robust scaffolds. We demonstrated the anti-HIV inhibition activity of the newly designed DNA sequences.

Phan, Anh Tuan; Do, Ngoc Quang

2013-01-01

157

49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.  

Code of Federal Regulations, 2010 CFR

...locking between electrical and mechanical levers. 236.340 Section 236.340 Transportation...locking between electrical and mechanical levers. In electro-mechanical interlocking...locking between electric and mechanical levers shall be maintained so that...

2009-10-01

158

49 CFR 236.340 - Electromechanical interlocking machine; locking between electrical and mechanical levers.  

Code of Federal Regulations, 2010 CFR

...locking between electrical and mechanical levers. 236.340 Section 236.340 Transportation...locking between electrical and mechanical levers. In electro-mechanical interlocking...locking between electric and mechanical levers shall be maintained so that...

2010-10-01

159

Fixed Bicortical Screw and Blade Implants as a Non-Standard Solution to an Edentulous (Toothless) Mandible  

PubMed Central

Aim This paper deals with the treatment of an atrophied toothless mandible with a fixing bridge carried by two non-standard implant systems. Methodology Four bicortical screws were implanted into the frontal part of the mandible and one implant on each side was placed into the distal area of the mandible as a support for a fixing bridge. Results During the years 2002 – 2007 the authors placed a total of 256 bicortical screw and 84 blade implants. During this period only four bicortical screws and one blade implant failed. The primary and secondary surgical success rate was therefore above 98%, while the prosthetic success rate was 100%. (Bridges which had to be re-fabricated due to implant failure were not taken into account.) Conclusion This approach is recommended as a highly successful and affordable option for a wide range of patients.

Strecha, Juraj; Jurkovic, Richard; Siebert, Tomas; Prachar, Patrik; Bartakova, Sonia

2010-01-01

160

Distal movement of mandibular molars in adult patients with the skeletal anchorage system.  

PubMed

The skeletal anchorage system (SAS) consists of titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible, or in both, as absolute orthodontic anchorage units. Distalization of the molars has been one of the most difficult biomechanical problems in traditional orthodontics, particularly in adults and in the mandible. However, it has now become possible to move molars distally with the SAS to correct anterior crossbites, maxillary dental protrusion, crowding, and dental asymmetries without having to extract premolars. This study evaluated the treatment and posttreatment changes during and after distalization of the mandibular molars. In 15 adult patients (12 women and 3 men), a total of 29 mandibular molars were successfully distalized with SAS. The amount of distalization and relapse and the type of tooth movement were analyzed with cephalometric radiographs and dental casts. The average amount of distalization of the mandibular first molars was 3.5 mm at the crown level and 1.8 mm at the root level. The average amount of relapse was 0.3 mm at both the crown and root apex levels. Of 29 mandibular molars, 9 were tipped back, and the others were translated distally in accordance with the established treatment goals. SAS is a viable modality to move mandibular molars for distally correcting anterior crossbites, malocclusions characterized by mandibular anterior crowding, and dental asymmetries. PMID:14765050

Sugawara, Junji; Daimaruya, Takayoshi; Umemori, Mikako; Nagasaka, Hiroshi; Takahashi, Ichiro; Kawamura, Hiroshi; Mitani, Hideo

2004-02-01

161

Practical clinical guidelines to prevent screw loosening.  

PubMed

The use of a screw-retained prosthesis on an osseointegrated implant is a popular treatment modality offering relative case in the removal of the restoration. One of the complications associated with this modality is the loosening of the abutment and coping screws. Loosening of the screws results in patient dissatisfaction, frustration to the dentist and, if left untreated, component fracture. There are several factors which contribute to the loosening of implant components which can be controlled by the restorative dentist and the lab technician. This article addresses the contributory factors and offers solutions which can be easily incorporated in the treatment. PMID:9117862

Hurson, S

1995-01-01

162

Reinforcement of osteosynthesis screws with brushite cement.  

PubMed

The fixation of osteosynthesis screws remains a severe problem for fracture repair among osteoporotic patients. Polymethyl-methacrylate (PMMA) is routinely used to improve screw fixation, but this material has well-known drawbacks such as monomer toxicity, exothermic polymerization, and nonresorbability. Calcium phosphate cements have been developed for several years. Among these new bone substitution materials, brushite cements have the advantage of being injectable and resorbable. The aim of this study is to assess the reinforcement of osteosynthesis screws with brushite cement. Polyurethane foams, whose density is close to that of cancellous bone, were used as bone model. A hole was tapped in a foam sample, then brushite cement was injected. Trabecular osteosynthesis screws were inserted. After 24 h of aging in water, the stripping force was measured by a pull-out test. Screws (4.0 and 6.5 mm diameter) and two foam densities (0.14 and 0.28 g/cm3) were compared. Cements with varying solid/liquid ratios and xanthan contents were used in order to obtain the best screw reinforcement. During the pull-out test, the stripping force first increases to a maximum, then drops to a steady-state value until complete screw extraction. Both maximum force and plateau value increase drastically in the presence of cement. The highest stripping force is observed for 6.5-mm screws reinforced with cement in low-density foams. In this case, the stripping force is multiplied by 3.3 in the presence of cement. In a second experiment, cements with solid/liquid ratio ranging from 2.0 to 3.5 g/mL were used with 6.5-mm diameter screws. In some compositions, xanthan was added to improve injectability. The best results were obtained with 2.5 g/mL cement containing xanthan and with 3.0 g/mL cements without xanthan. A 0.9-kN maximal stripping force was observed with nonreinforced screws, while 1.9 kN was reached with reinforced screws. These first results are very promising regarding screw reinforcement with brushite cement. However, the polyurethane foam model presents noninterconnected porosity and physiological liquid was not modelized. PMID:10458285

Van Landuyt, P; Peter, B; Beluze, L; Lemaître, J

1999-08-01

163

[Titanium porous-surface screw implant].  

PubMed

Titanium porous-surfaced screw implant was made by plasma-spray with Ti powder. The pore size was 80-300 microns. Two groups of implants were implanted in the mandibles of 15 dogs. Group A: porous-surfaced screw implant: Group B: smooth surface screw implant. The bone healing was evaluated by L. M. SEM. and shear strength testing. The results show that the osteo integration of two groups were completed after 12 weeks. The bone grew into porous surface. The shear strength of group A was significantly higher than that of group B. PMID:7489655

Zhang, H; Liu, B; Zhnag, X

1995-05-01

164

Bone changes after experimental osteotomies fixed with absorbable self-reinforced poly- l-lactide screws or metallic screws studied by plain radiographs, quantitative computed tomography and magnetic resonance imaging  

Microsoft Academic Search

The healing of the distal femoral osteotomy fixed with self-reinforced poly-l-lactide (SR-PLLA) or metallic screws in 16 rabbits was evaluated with plain radiographs, quantitative computed tomography and magnetic resonance imaging (MRI). At 36 weeks in the metallic fixation there was significantly more external callus than in the SR-PLLA fixation. On the metallic fixation side the cortical bone mineral density was

J. Viljanen; J. Kinnunen; S. Bondestam; A. Majola; P. Rokkanen; P. Törmälä

1995-01-01

165

LCP distal ulna hook plate as alternative fixation for fifth metatarsal base fracture.  

PubMed

Intramedullary screw fixation is the most common treatment for fifth metatarsal base fractures. Screw application does not achieve accurate reduction in fracture with small fragments, osteoporotic bone, or Lawrence zone 1 fractures, however. On the basis of similar anatomical architectures between the distal ulna and the fifth metatarsal base, the purpose of this study was to assess the results of a locking compression plate (LCP) distal ulna hook plate in stabilizing displaced zone 1 or 2 fifth metatarsal base fractures. Nineteen patients with Lawrence zone 1 (n = 12) or 2 (n = 7) fractures of the fifth metatarsal base were treated surgically with an LCP distal ulna hook plate. The patients were evaluated clinically and radiographically, and functional outcomes were graded by using the American Orthopaedic Foot and Ankle Society (AOFAS) midfoot scoring system. Radiographic bony union was obtained in all patients, at an average of 7.4 weeks. The mean AOFAS midfoot score improved from 26 (range, 0-45) preoperatively to 94 (range, 72-100) points at the final follow-up. There were three patients with post-traumatic cubometatarsal arthrosis and one patient with sural nerve neuropraxia. In our experience, the distal ulna hook plate achieves a high rate of bony consolidation and anatomically suitable fixation in zone 1 or 2 fifth metatarsal base fractures. We also suggest that the LCP distal ulna hook plate should be considered as an alternative treatment in multifragmentary, osteoporotic, and tuberosity avulsion (zone 1) fifth metatarsal base fractures. PMID:23412193

Lee, Sang Ki; Park, Ju Sang; Choy, Won Sik

2012-08-22

166

Inertial interlock bonding: A new approach to sputtering target construction  

SciTech Connect

Inertial interlock bonding (IIB) was developed to provide a reliable low cost automated method for joining dissimilar metal plates at low bulk bonding temperatures for the production of sputtering targets. Joining dissimilar metals at elevated temperatures creates residual stress from the differential thermal expansion of the bimetallic plates. The IIB method of joining dissimilar metal plates alleviates the need to increase the bulk temperature of the metal plates during bonding and thereby significantly reduces the residual stress. In IIB, the heat generated by inertial friction between two dissimilar metal plates is used to simultaneously (1) soften an intercalated ring that is forged into a matching T groove and (2) melt a thin solder layer that wets the other plate creating a reliable solder bond. While finite element modeling of the process indicates that the surface temperatures during bonding approach 1000 deg. C, the bulk temperature for the assembly remains below 70 deg. C. In this way, the differential thermal residual stress remains low, while a reliable bimetallic joint is formed. Results for joining tantalum to copper alloy plates for sputtering target applications are provided.

Wickersham, C. E. Jr.; Workman, David [Cabot Corporation, 157 Concord Road, Billerica, Massachusetts 01821 (United States); Edision Welding Institute, 1250 Arthur E Adams Drive, Columbus, Ohio 43221 (United States)

2007-01-15

167

Interlocking mats support drilling rig on frozen swamp  

SciTech Connect

This paper discusses how a company employed a unique mat system to reduce environmental impact and to support the drilling rig on its Astosch No. 1 exploratory well at Granite Point in the Trading Bay Wildlife Refuge. The site is on the west side of Cook Inlet. During winter, the travel time from Anchorage to the base camp near the Tyonek Indian village was 5 hr by ice road or 45 min by fixed wing aircraft. Eighteen miles of existing gravel roads were used from this base camp to the edge of the frozen muskeg swamp, and from there, they constructed 7 miles of ice road to the well site. They constructed a snow and ice pad with two impermeable liners and then installed Uni-Mat International Inc.'s patented interlocking mats for the final foundation. After moving in the rig, a snow berm was built around the perimeter of the location and an impermeable liner was then draped and secured over the berm.

Not Available

1991-04-15

168

Treatment of Symptomatic Distal Interphalangeal Joint Arthritis with Percutaneous Arthrodesis: a Novel Technique in Select Patients  

PubMed Central

Arthrodesis of the distal interphalangeal (DIP) joint is a reliable means of achieving pain relief in a symptomatic DIP joint afflicted by a variety of degenerative, inflammatory, or posttraumatic conditions. Successful arthrodesis is more reproducible when rigid compression of the joint is achieved. The emergence of an increasing number of commercially available headless or variable pitch compression screws reflects the growing trend among hand surgeons to utilize rigid stabilization of the DIP joint so that motion at more proximal levels can be initiated immediately without affecting arthrodesis rates. Successful closed percutaneous DIP arthrodesis can be achieved in a patient with hypertrophic osteoarthropathy, passively correctable deformity, and patients at increased risk for perioperative soft tissue complications associated with open arthrodesis. We present a novel percutaneous DIP fusion technique utilizing a cannulated headless compression screw in a select group of patients. The sagittal plane diameters of the distal and middle phalanges are templated. Cannulated headless compression screws, 2.4 and 3.0 mm, with short or long terminal threads at the leading end of the screw are selected based upon patient-specific anatomic considerations. Pain-free status and radiographic fusion were achieved in both patients (gout arthropathy, n?=?1; posttraumatic arthritis, n?=?1) at an average of 6 weeks postoperatively. Our current indications, along with pearls and pitfalls with this technique, are reviewed. In select patients, this percutaneous DIP joint arthrodesis is advantageous in comparison with open fusion techniques.

Ruchelsman, David E.; Hazel, Antony

2010-01-01

169

Screw osteosynthesis in the treatment of fracture lateral humeral condyle in children.  

PubMed

We reviewed the results of screw osteosynthesis for the treatment of fracture lateral condylar physis in twenty children whose average age was six years old (range, two to ten years) at the time of operation from January 1998 till December 2000. The average interval between the injury and the operation was three and half days (range, one day to two weeks). The average duration of follow up was one year (range, one year to two years). Osteosynthesis was revised in two patients due to anterior placement of screw and rotated distal fracture fragment. Osseous union was achieved in all twenty patients. The result was rated excellent in nineteen patients and good in one patient. PMID:14569766

Baharuddin, M; Sharaf, I

2001-12-01

170

Biomechanical evaluation of a medial knee reconstruction with comparison of bioabsorbable interference screw constructs and optimization with a cortical button  

Microsoft Academic Search

Current fixation techniques in medial knee reconstructions predominantly utilize interference screws alone for soft tissue\\u000a graft fixation. The use of concurrent fixation techniques as part of a hybrid fixation technique has also been suggested to\\u000a strengthen soft tissue fixation, although these hybrid fixation techniques have not been biomechanically validated. The purpose\\u000a was to biomechanically evaluate two distal tibial superficial MCL

Coen A. Wijdicks; Emily J. Brand; David J. Nuckley; Steinar Johansen; Robert F. LaPrade; Lars Engebretsen

2010-01-01

171

Reinforcement of osteosynthesis screws with brushite cement  

Microsoft Academic Search

The fixation of osteosynthesis screws remains a severe problem for fracture repair among osteoporotic patients. Poly-methyl-methacrylate (PMMA) is routinely used to improve screw fixation, but this material has well-known drawbacks such as monomer toxicity, exothermic polymerization, and nonresorbability. Calcium phosphate cements have been developed for several years. Among these new bone substitution materials, brushite cements have the advantage of being

P Van Landuyt; B Peter; L Beluze; J LemaÎtre

1999-01-01

172

[Distal femoral fractures].  

PubMed

Techniques of operative treatment of supra- and intercondylar fractures have changed in recent years. These changes refer to reduction techniques and implant selection. Operative approach concepts, which remained unchanged for several decades were critically evaluated and modified to a minimal invasive osteosynthesis [MIO]. This included for intraarticular fractures a trans-articular joint reconstruction and a retrograde plate osteosynthesis (TARPO). This technique result in better operative visualization and management of intraarticular comminution, saver fracture healing and better functional outcome. For extraarticular fractures a minimally invasive percutaneous plate osteosynthesis (MIPPO) via stab incisions only or retrograde intramedullary nailing is available. Beside that new strategies and techniques for the avoidance of axial malalignment, rotational deformities and leg length discrepancies are described, as well as a new plate generation (LISS: less invasive stabilization system), which behaves more like an internal fixator. The complex nature of combined fractures and soft tissue injuries of the distal femur and proximal tibia needs special attention and specific management. Distal femoral and proximal tibial fractures in young patients are usually caused by a high energy trauma. They are complicated by a high rate of systemic and local injuries to cartilage, ligaments and skin. The patients in this group with severe injuries need a detailed treatment algorithm, because the surgeon's individual skill, enthusiasm and wishful thinking frequently led to unsatisfactory results. A decision making scheme is presented specifically addressing timing and treatment modalities. PMID:9887674

Krettek, C; Schandelmaier, P; Richter, M; Tscherne, H

1998-01-01

173

Oil extraction of oleic sunflower seeds by twin screw extruder: influence of screw configuration and operating conditions  

Microsoft Academic Search

The objective of this study was to investigate the effects of screw configuration, position of screw elements and spacing between them allowing to realize oil extraction of oleic sunflower seeds on a twin-screw extruder. Experiments were conducted using a co-rotating twin-screw extruder (Model Clextral BC 45, France). Twelve screw profiles were examined to define the best performance (oil extraction yield,

I. Amalia Kartika; P. Y. Pontalier; L. Rigal

2005-01-01

174

Global ice-sheet system interlocked by sea level  

SciTech Connect

Denton and Hughes postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during later Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75/sup 0/N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet. But factors other than areal changes of the grounded Antarctic Ice Sheet may have strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate, but another potential influence was high-frequency climatic oscillations. It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm-high frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 /sup 14/C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide. Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.

Denton, G.H.; Hughes, T.J.; Karlen, W.

1986-01-01

175

The use of fusion mass screws in revision spinal deformity surgery.  

PubMed

STUDY DESIGN: To report the use of a posterior based 'fusion mass screw' (FMS) as a primary or salvage fixation point in a revision spinal deformity following a previous posterior spinal fusion (PSF). Our experience of this technique in a case report and the clinical and radiological results are reported. OBJECTIVES: To describe the technique and uses of the FMS as a primary/salvage fixation point in osteotomies in previously arthrodesed spinal deformity surgery. Obtaining fixation points to correct and stabilize a spinal deformity with coronal and sagittal imbalance in a previously arthrodesed spine during revision surgery can be challenging. Several alternate pedicle fixation techniques and laminar screw techniques have been described in the literature. However, there is no description of these techniques in the presence of a spinal fusion with distorted anatomy. A pedicle screw placed coronally across a thick posterior fusion mass can provide an alternate method of fixation in these cases with complex anatomy. METHODS: Two cases of complex spinal deformity and corrective spinal osteotomies using fusion mass screws (FMSs) placed coronally across the posterior fusion mass are described. The first case is an 8-year-old patient with Marfan's syndrome who developed a crank shaft phenomenon and severe thoracolumbar kyphoscoliosis following a previous PSF. The second case is a 53-year-old patient with coronal imbalance following PSF as a child using Harrington instrumentation who developed distal degeneration with stenosis in her remaining mobile segments. Both patients underwent vertebral column resection and osteotomy closure plus stabilisation using FMS. The clinical and radiological results and technique for insertion of the FMS are described. CONCLUSION: In this report, we present a novel method of using posterior FMSs to achieve fixation and correction in cases of revision deformity surgery with difficult anatomy. While we feel pedicle screws are the gold standard in deformity correction, knowledge of alternatives such as the FMS can allow surgeons to achieve stable constructs when faced with challenging situations. PMID:23744035

Lewis, Stephen J; Arun, Ranganathan; Bodrogi, Andrew; Lebel, David E; Magana, Sofia P; Dear, Taylor E; Witiw, Chris

2013-06-01

176

How pilot-hole size affects bone-screw pullout strength in human cadaveric cancellous bone  

PubMed Central

Objective Screw failure of cancellous bone screws is not uncommon. To compare the effect of varying pilot-hole size on pullout strength of cancellous bone screws in human cadaveric bone, we designed and performed a biomechanical study to allow quantitative analysis. Methods Three pairs of distal femurs and 4 pairs of proximal tibias from embalmed human cadavers were stabilized in a mould, and the bone cortex was overdrilled. Four sites in a linear transverse plane were randomly assigned, anatomically matched with the paired bone and drilled with either pilot-hole size 3.2 mm or 2.5 mm. The cancellous screw (Synthes noncannulated 4.5-mm shaft, 6.5-mm external diameter) was guided into the pilot hole and pulled on by a test frame (Instron 8874 biaxial servo-hydraulic test frame) with increasing force to the point of failure, and the forces at which failure resulted were compared. Results A comparison of 25 anatomically paired sites with a 2-tailed paired t test and Wilcoxon matched-pairs signed rank test indicated significantly stronger pullout strength (p = 0.047 and p = 0.047) of the 2.5-mm compared with the 3.2-mm pilot hole. Subanalysis of the 4 studied locations indicated that 3 supported the above findings and 1 supported a reverse trend. Conclusions Generally, cancellous screws demonstrated a significantly (p < 0.05) stronger hold using a smaller size pilot hole than the recommended standard diameter. All locations except the inner lateral site supported this finding.

Steeves, Mark; Stone, Craig; Mogaard, John; Byrne, Stephanie

2005-01-01

177

Axial loading cross screw fixation for the Austin bunionectomy.  

PubMed

The Austin procedure has become a common method of osteotomy for the correction of hallux abductovalgus when indicated. The V-type configuration is intrinsically stable but not without complications. One complication encountered is rotation and/or displacement of the capital fragment. We present the use of an axial loading screw in conjunction with a dorsally placed compression screw. The benefit to this technique lies in the orientation of the axial loading screw, because it is directed to resist the ground reactive forces while also providing a second point of fixation in a crossing screw design. In a head-to-head biomechanical comparison, we tested single dorsal screw fixation versus double screw fixation, including both the dorsal and the axial loading screws in 10 metatarsal Sawbones(®) (Pacific Research Laboratories Inc, Vashon, WA). Five metatarsals received single dorsal screw fixation and five received the dorsal screw and the additional axial loading screw. The metatarsals were analyzed on an Instron compression device for comparison; 100% of the single screw fixation osteotomies failed with compression at an average peak load of 205 N. Four of five axial loading double screw fixation osteotomies did not fail. This finding suggests that the addition of an axial loading screw providing cross screw orientation significantly increases the stability of the Austin osteotomy, ultimately decreasing the likelihood of displacement encountered in the surgical repair of hallux abductovalgus. PMID:21621434

Rigby, Ryan B; Fallat, Lawrence M; Kish, John P

2011-05-31

178

Distal arthrogryposis syndrome.  

PubMed

A 5-month-old male infant presented with weak cry, decreased body movements, tightness of whole body since birth, and one episode of generalized seizure on day 4 of life. He was born at term by elective caesarian section performed for breech presentation. The child had failure to thrive, contractures at elbow and knee joints, hypertonia, microcephaly, small mouth, retrognathia, and camptodactyly. There was global developmental delay. Abdominal examination revealed umbilical and bilateral inguinal hernia. Visual evoked response and brainstem evoked response audiometry were abnormal. Nerve conduction velocity was normal. Magnetic resonance imaging of brain revealed paucity of white matter in bilateral cerebral hemispheres with cerebellar and brain stem atrophy. The differential diagnoses considered in the index patient were distal arthrogryposis (DA) syndrome, cerebroculofacioskeletal syndrome, and Pena Shokier syndrome. The index patient most likely represents a variant of DA: Sheldon Hall syndrome. PMID:20300297

Kulkarni, K P; Panigrahi, I; Ray, M; Marwaha, R K

2008-05-01

179

Clinical application of combined fixation in the cervical spine using posterior transfacet screws and pedicle screws.  

PubMed

The aim of the present study was to describe the clinical application of combined fixation in the cervical spine using posterior transfacet and pedicle screws. Ten patients with cervical disorders requiring stabilization were treated from May 2006 to December 2008. The operative details varied depending on indication, the need for decompression, and the number of levels to be included in the spinal construct. Radiographic analysis of the fusion was performed after surgery. A total of 23 transfacet screws were inserted at or caudal to the C4/5 facet. A total of 21 pedicle screws were placed. All patients underwent operative treatment without neurovascular complications. Fusion was achieved in all patients. When performed appropriately, the method of using posterior transfacet screws in the caudal cervical joints combined with pedicle screw fixation in the cephalic cervical spine is reliable and deserves more widespread use. PMID:23232101

Liu, Guanyi; Ma, Weihu; Xu, Rongming; Godinsky, Ryan; Sun, Shaohua; Feng, Jianxiang; Zhao, Liujun; Hu, Yong; Zhou, Leijie; Liu, Jiayong

2012-12-08

180

Programmable controllers replace relays in MFTF-B personnel-safety interlocks  

SciTech Connect

This paper describes a new approach for implementing personnel safety interlocks logic using industrial-type programmable controllers. The logic for all personnel safety interlocks except those totally internal to a subsystem is implemented in two non-redundant controllers. A high degree of fail-safe reliability is achieved by augmenting the protective features intrinsic to each controller with those provided by a small amount of external support hardware. The controllers are interfaced to the host computer system via fiber optic data links to enable display of interlock and overall system status on the control room graphic displays. When fully implemented, the controllers will perform the equivalent of over 2000 discreet relay functions.

Branum, J.D.

1981-10-20

181

The alcohol interlock: an underutilized resource for predicting and controlling drunk drivers.  

PubMed

This report summarizes evidence presented during the Third Annual Ignition Interlock Symposium at Vero Beach, Florida, 29 October 2002. The ignition interlock prevents a car from starting when blood alcohol concentration (BAC) is elevated. We review some of our prior work as well as introduce previously unpublished results to demonstrate the manner in which the data recorded by the alcohol ignition interlock device can serve as an advance predictor of future driving under the influence (DUI) of alcohol risks. Data used in this current report represent approximately 2,200 ignition interlock users from Alberta, Canada, and about 8,000 interlock users from Quebec, Canada; the Alberta data set contained 5.5 million breath tests and the Quebec data 18.8 million breath tests. All tests are time and date stamped and this information was used to characterize patterns of BAC and vehicle use, and the relationship between BAC elevations and DUI offenses that accumulated after the interlock was removed from the vehicles. Findings from Cox regression show that BAC elevations >.02-.04% are more potent predictors of repeat DUI (p<.0001) than even prior DUI (p<.006), usually found to be the strongest indicator of driver risk. Prior DUI obviously has no use for scaling the risk of first-time offenders. Drivers who are both multiple offenders and who have more than a few elevated interlock BAC tests are much more likely to repeat DUI. The timing and pattern of elevated BAC tests provided during the time drivers were required to use an alcohol ignition interlock device are remarkably similar on both a daily basis and an hourly basis when the interlock programs from the two provinces are compared directly. Both provinces had higher rates of elevated tests on Saturday and Sunday, and the fewest elevated tests on Tuesdays. The absolute rate of elevated tests is similar despite the two provinces adhering to different interlock lockout points (.02% Quebec;.04% Alberta). Charts tracking the Monday-Friday timing of elevated BAC tests by hour are nearly identical for both provinces. The most elevated BAC tests occurred between 7 and 9 A.M. Monday to Friday, even though most vehicle start attempts occurred much later in the day. This higher rate of elevated morning BAC likely represents drinking from the prior evening with alcohol not yet cleared from circulation; those with elevated BAC in the early morning were more likely to have a repeat offense even after accounting for prior DUI and the higher overall rate of elevated BAC tests. This is viewed as evidence of a drinking problem that will lead to impaired driving after the controlling function of the interlock is removed. Policy changes are discussed that might take better advantage of interlock information to improve the public response to drunk driving. PMID:14522642

Marques, Paul R; Tippetts, A Scott; Voas, Robert B

2003-09-01

182

The alcohol interlock: an underutilized resource for predicting and controlling drunk drivers.  

PubMed

This report summarizes evidence presented during the Third Annual Ignition Interlock Symposium at Vero Beach, Florida, 29 October 2002. The ignition interlock prevents a car from starting when blood alcohol concentration (BAC) is elevated. We review some of our prior work as well as introduce previously unpublished results to demonstrate the manner in which the data recorded by the alcohol ignition interlock device can serve as an advance predictor of future driving under the influence (DUI) of alcohol risks. Data used in this current report represent approximately 2,200 ignition interlock users from Alberta, Canada, and about 8,000 interlock users from Quebec, Canada; the Alberta data set contained 5.5 million breath tests and the Quebec data 18.8 million breath tests. All tests are time and date stamped and this information was used to characterize patterns of BAC and vehicle use, and the relationship between BAC elevations and DUI offenses that accumulated after the interlock was removed from the vehicles. Findings from Cox regression (Marques et al., 2003) show that BAC elevations > .02-.04% are more potent predictors of repeat DUI (p < .0001) than even prior DUI (p < .006), usually found to be the strongest indicator of driver risk. Prior DUI obviously has no use for scaling the risk of first-time offenders. Drivers who are both multiple offenders and who have more than a few elevated interlock BAC tests are much more likely to repeat DUI. The timing and pattern of elevated BAC tests provided during the time drivers were required to use an alcohol ignition interlock device are remarkably similar on both a daily basis and an hourly basis when the interlock programs from the two provinces are compared directly. Both provinces had higher rates of elevated tests on Saturday and Sunday, and the fewest elevated tests on Tuesdays. The absolute rate of elevated tests is similar despite the two provinces adhering to different interlock lockout points (.02% Quebec; .04% Alberta). Charts tracking the Monday-Friday timing of elevated BAC tests by hour are nearly identical for both provinces. The most elevated BAC tests occurred between 7 and 9 A.M. Monday to Friday, even though most vehicle start attempts occurred much later in the day. This higher rate of elevated morning BAC likely represents drinking from the prior evening with alcohol not yet cleared from circulation; those with elevated BAC in the early morning were more likely to have a repeat offense even after accounting for prior DUI and the higher overall rate of elevated BAC tests. This is viewed as evidence of a drinking problem that will lead to impaired driving after the controlling function of the interlock is removed. Policy changes are discussed that might take better advantage of interlock information to improve the public response to drunk driving. PMID:16801123

Marques, Paul R; Tippetts, A Scott; Voas, Robert B

2003-01-01

183

Final design review report for the RMCS Flammable Gas Detection Interlock  

SciTech Connect

This report document the completion of the formal design review for the RMCS (Rotary Mode Core Sampling) flammable gas detector interlock. This hydrogen/flammable gas interlock, a proposed addition to the RMCS system portable exhauster, in intended to support core sampling operations in waste tanks requiring flammable gas controls. The objective of this review was to approve new drawings at the 100% design completion state. The conclusion reached by the review committee was that the design was acceptable and efforts should continue toward fabrication and delivery.

Corbett, J.E., Westinghouse Hanford

1996-08-20

184

Effects of Ignition Interlock Devices on DUI Recidivism: Findings from a Longitudinal Study in Hamilton County, Ohio  

Microsoft Academic Search

As demands for more effective legal remedies for drunk driving escalate, a number of states have authorized judges to use breath analyzer ignition interlock devices as an optional sanction in drunk driving cases. This research presents initial findings from a quasi-experimental study designed to evaluate the effectiveness of interlock devices as a deterrent to a repeated drunk driving arrest in

Barbara J. Morse; Delbert S. Elliott

1992-01-01

185

Standard industry components as I\\/O extension for an Interlock System at PITZ, MTF and XFEL  

Microsoft Academic Search

The main task of the interlock system is to prevent any damage of the costly components of the RF station. The implementation of the interlock must also guarantee a maximum uninterrupted time of operation which implies the implementation of self diagnostics and repair strategies on a modular basis. Additional tasks include collection and temporary storage of status information of individual

T. Grevsmuhl; M. Penno; M. Grimberg; L. Jachmann; W. Kohler; H. Leich; G. Trowitzsch; R. Wenndorff

2009-01-01

186

DOE 6430.1a compliance checklist for the rotary mode core sampling exhauster flammable gas interlock  

SciTech Connect

This document examines the Safety Class I criteria in DOE 6430.1a and determines applicability to the rotary mode core sampling exhauster flammable gas interlock. Purpose of the interlock is to prevent the design basis accident of deflagration in single shell flammable gas watchlist tank.

Robinson, J.D.

1995-09-01

187

Outcome of unstable distal radius fractures treated with open reduction and internal fixation versus external fixation.  

PubMed

The objective of this study was to compare the clinical results of unstable distal radius fractures treated with ORIF with plate and screws compared to EF. Patients with unstable distal radius fractures treated with ORIF or EF from January 2005 to December 2010 were reviewed in terms of the Modified Mayo Wrist Score, range of motion, pain, grip strength, and radiologic parameters. Results showed that there was no difference in the Modified Mayo Wrist Score between ORIF (17 patients) and EF (11 patients) (p = 0.07). The ORIF group had better wrist flexion, wrist extension, pronation and supination compared to the EF group (p < 0.05). There were no significant differences in terms of radial and ulnar deviation, grip strength, pain and postoperative radiologic parameters (p < 0.05). Better wrist flexion, wrist extension and forearm rotation can be expected in ORIF compared to EF in the management of unstable distal radius fractures. PMID:22745080

Estrella, Emmanuel P; Panti, Paulo L

2012-01-01

188

Biomechanical effects of screw fixation in second mandibular reconstruction plate.  

PubMed

The purpose of this study was to investigate biomechanical effects of second reconstruction plate with different combinations of fixed screws in patient with mandibular tumor resection by three-dimensional finite element analysis (FEA). The FEA models were consisted of defected mandible, reconstruction plate with different screw holes, and bone screws. The results indicated that application of the second reconstruction plate appeared to increase stability and decrease stress magnitude on the plates and screws accompanying with increasing screw number. For clinical cost consideration in usage of the second reconstruction plate, the conclusion showed that the second reconstruction plate could offer a better mechanical efficacy accompanying with increase of screw quantity, but single screw applied for the second plate fixation to defected mandible of tumor resection was enough to stabilize without increase of screw quantities. PMID:24110400

Chang, Ya-Wen; Liu, Pao-Hsin

2013-07-01

189

Distal femoral fracture through the screw hole of a ligament augmentation device fixation  

Microsoft Academic Search

Summary: Complications associated with fixation of artificial ligaments in augmented repair of the anterior cruciate ligament (ACL) have been reported throughout the literature. However, fractures following ligament augmentation device (LAD) fixation appear to be rare. We report the case of a 43-year-old woman, injured in a road accident, who sustained a depressed fracture of the tibial plateau and knee instability.

Christof Radler; Gerald E. Wozasek; Helmut Seitz; Vilmos Vécsei

2000-01-01

190

Distal interphalangeal joint arthrodesis: an analysis of complications.  

PubMed

One hundred thirty-nine patients underwent 181 arthrodeses of finger distal interphalangeal joints (144) and/or thumb interphalangeal joints (37). Techniques included (1) crossed Kirschner pins (111 joints), (2) interfragmentary wire and longitudinal Kirschner pin (43 joints), and (3) Herbert screw (27 joints). Each technique had a similar nonunion rate. There were 21 nonunions: 13 were pain free, 6 were successfully fused on the second attempt, 1 was painful (but the patient refused further surgery), and 1 was amputated. Inadequate bone stock, inadequate bone resection, premature pin removal, and infection appear to complicate the attainment of bony union. Twenty percent of the fusions had major complications (nonunion, malunion, deep infection, and osteomyelitis). Minor complications (dorsal skin necrosis, cold intolerance, proximal interphalangeal joint stiffness, paresthesias, superficial wound infection, and prominent hardware) occurred in 16% of the joints fused. PMID:1430956

Stern, P J; Fulton, D B

1992-11-01

191

Imaging of the distal airways.  

PubMed

Imaging techniques of the lung continue to advance, with improving ability to image the more distal airways. Two imaging techniques are reviewed: computed tomography and magnetic resonance with hyperpolarized helium-3. PMID:19962040

Tashkin, Donald P; de Lange, Eduard E

2009-12-01

192

Visuality in The Turn of the Screw: \\  

Microsoft Academic Search

Scarry is referring to the half-formed, transitory, vanishing quality of ghosts—a quality shared, more or less, by any mental image we might choose to form in the mind's eye. In this sense The Turn of the Screw is a perfect ghost story. It is a story about seeing ghosts, about picturing them, and perhaps about imagining them altogether. In fact,

Josh Rothman

193

Helical Screw Expander Evaluation Project. Final Report.  

National Technical Information Service (NTIS)

A functional 1-MW geothermal electric power plant that featured a helical screw expander was produced and then tested in Utah in 1978 to 1979 with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditi...

R. McKay

1982-01-01

194

A phenomenological study on twin screw extruders  

Microsoft Academic Search

Although more and more twin screw extruders are being used in the polymer industry, the theoretical background is relatively undeveloped. The literature abounds in contradictions and often informs the reader that all extrusion problems can be solved if a certain new design is considered. The development of successful machines has mainly been possible through the application of commercially valuable empirical

L. P. B. M. Janssen

1976-01-01

195

Load Transfer through Aggregate Interlock: Crack Width, Aggregate Type and Performance  

Microsoft Academic Search

It is well known that performance of plain jointed concrete pavements depends on aggregate interlock to transfer load from the one slab to the next. In order to quantify the relative contribution of crack width and the strength of the aggregate to the long- term performance of a plain jointed pavement, experimental sections of road were built using different aggregates

P J Strauss; B D Perrie; L du Plessis; D Rossmann

196

Development of Underwater Cutting Method of Interlocked Steel Pipe Piles Using Plasma Arc.  

National Technical Information Service (NTIS)

Interlocked steel pipe piles are driven into the ground for construction of piers located in rivers or the sea. In such cases underwater cutting is often required at the end of construction. Cutting of junction pipes is so hard that pipes will usually be ...

T. Fujita H. Imura K. Akahide T. Koseki M. Hashimoto

1988-01-01

197

The Use of Interlocking Prostheses for Both Temporary and Definitive Management of Infected Periprosthetic Femoral Fractures  

Microsoft Academic Search

Infected periprosthetic fractures around total hip arthroplasties are an extremely challenging problem. We describe our experience of managing infected periprosthetic femoral fractures using interlocking long-stem femoral prostheses either as temporary functional spacers or as definitive implants. The Cannulock (Orthodesign, Christchurch, United Kingdom) uncoated stem was used in 12 cases, and the Kent hip prosthesis (Biomet Merck, Bridgend, United Kingdom), in

Sujith Konan; Faizal Rayan; Andrew R. J. Manketelow; Fares S. Haddad

2011-01-01

198

46 CFR 111.70-7 - Remote control, interlock, and indicator circuits.  

Code of Federal Regulations, 2010 CFR

...load side of the motor and controller disconnect...device, except if the control functions require...In the design of a control, interlock, or...all practicable steps must be taken to...enclosure. If the control functions make it...the load side of a motor and controller...

2010-10-01

199

46 CFR 111.70-7 - Remote control, interlock, and indicator circuits.  

Code of Federal Regulations, 2010 CFR

...load side of the motor and controller disconnect...device, except if the control functions require...In the design of a control, interlock, or...all practicable steps must be taken to...enclosure. If the control functions make it...the load side of a motor and controller...

2009-10-01

200

Novel physically loaded and interlocked electrode developed for ionic polymer-metal composites (IPMCs)  

Microsoft Academic Search

Described is a novel fabrication process of manufacturing ionic polymeric metal composites (IPMC's) biomimetic sensors, actuators and artificial muscles equipped with physically loaded and interlocked (PLI) electrodes. The underlying principle of processing this novel PLI-IPMC's is to first physically load a conductive primary powder into the ionic polymer network forming a dispersed particulate layer. This primary layer functions as a

Mohsen Shahinpoor; Kwang J. Kim

2001-01-01

201

Patterns In Contingencies: The Interlocking of Formal and Informal Political Institutions in Contemporary Argentina  

ERIC Educational Resources Information Center

This article explores how the interlocking of formal and informal political institutions has affected the dynamics and performance of the Argentine democracy. Key institutional features of the Argentine political system have been a competitive form of federalism, loosely structured and political parties that are not ideologically unified,…

Llamazares, Ivan

2005-01-01

202

Homodyne reflectometer for neutral beam injection interlock on large helical device  

SciTech Connect

Neutral beam injection (NBI) into low-density plasmas can cause serious damage to the vacuum vessel wall. It is necessary to stop the NBI when the plasma terminates. This needs a reliable density monitor for NBI interlock. A three-channel homodyne reflectometer, installed on a large helical device was used for an NBI interlock. Microwaves of 28.5, 34.9, and 40.2 GHz were injected with O mode polarization. At present, a simple homodyne detection scheme is used. The reflected signal consists of a dc component due to local and reflected power and an ac component due to fluctuations in the position of the cutoff layer. Since the change in dc signal was very small, the root mean square value of the ac signal was used as the interlock signal. At present the 34.9 GHz O mode channel, whose O mode cutoff density is 1.5x10{sup 19} m{sup -3}, is used for the interlock. The system has been working since the first NBI experiments on LHD in 1999.

Tanaka, K.; Ejiri, A.; Ito, Y.; Kawahata, K.; Tokuzawa, T.; Osakabe, M.; Takeiri, Y. [National Institute for Fusion Science, Toki 509-5292 (Japan)

2006-10-15

203

Towards the formalization of railway interlocking system using Z-notations  

Microsoft Academic Search

Railway interlocking system is a safety critical system. Its malfunction can cause the loss of human life and severe injuries. To remove difficulties from this type of system better and advanced methodologies are required. This paper presents the use of Z-specification to specify the safety properties of the train system. The paper provides division of railway track into sectors and

Sher Afzal Khan; Nazir A. Zafar

2009-01-01

204

Interlocking and nonlinear saturation of double tearing modes in differentially rotating plasmas  

SciTech Connect

Interlocking and nonlinear saturation of double tearing modes (DTMs) in rotating plasmas are investigated in a reduced magnetohydrodynamic model. Differential plasma rotation is found to have a significant stabilizing effect on the DTM. Analysis for the threshold island width and locking frequency is carried out. The effect of the viscosity on the mode is also discussed.

Wang Xianqu; Xu Wenbin; Wang Zhengxiong [School of Physics and Optoelectronic Technology and College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024 (China); Wang Xiaogang [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China)

2011-01-15

205

Facile route to an all-organic, triply threaded, interlocked structure by templated dynamic clipping.  

PubMed

Encaged! Three-terminal interlocked molecular species were obtained by dynamic (2+3) assembly of a cagelike macro-bicycle around a trifurcated trispyridinium ? guest. The complex is stabilized by ?-? interactions and multiple [C-H???O] and [C-H???N] interactions. Uncomplexed guest molecules cocrystallize alongside the threaded complexes in the solid state, thus giving extended ?-stacked columns. PMID:23161742

Pun, Andrew; Hanifi, David A; Kiel, Gavin; O'Brien, Evan; Liu, Yi

2012-11-19

206

Engineering Task Plan for Hepa Filter Differential Pressure (DP) Fan Interlock Upgrades  

SciTech Connect

This document provides a plan for installation of Differential Pressure (DP) fan interlocks on the primary ventilation systems in selected Tank Farm facilities. This plan contains the engineering tasks required for installation and is summarized by the Acceptance for Beneficial Use list. Individuals responsible for each task are identified and scheduled accordingly.

SIMONS, S.R.

2000-05-19

207

The Time and Context-Contingent Nature of Intersectionality and Interlocking Oppressions  

Microsoft Academic Search

This article addresses the theoretical paradigm of intersectionality and interlocking oppressions, focusing on its evolution over time and place and application to the everyday lives of women. The objective is both to honor the roots of intersectional scholarship and to demonstrate the temporal and spatial nature of oppression and privilege. Theoretical concepts are illustrated by narratives from women who have

Wendy Hulko

2009-01-01

208

Lapidus bunionectomy: Early evaluation of crossed lag screws versus locking plate with plantar lag screw.  

PubMed

We compared outcomes of the Lapidus bunionectomy fixated with crossed lag screws versus a locking plate with a plantar lag screw. Forty patients who underwent Lapidus bunionectomy between August 2001 and May 2006 were evaluated in a combined retrospective and prospective fashion. Crossed lag screws were used in 19 of the patients, and a locking plate with a plantar lag screw was used in 21 of the patients. Other than fixation, the only interventional difference pertained to postoperative weight bearing, where those receiving the plate initiated full weight bearing on the operated foot at 4 weeks postoperative, as compared to 6 weeks for those receiving crossed screws. Overall, the mean preoperative AOFAS hallux score was 41.75 +/- 2.52, and the postoperative score was 90.48 +/- 8.41 (P < .0001). The overall mean preoperative first intermetatarsal angle was 15.3 degrees +/- 2.32 degrees , and long term the angle was 5.03 degrees +/- 2.86 degrees (P < .0001). When comparisons were made based on the method of fixation, use of an adjunct Akin osteotomy and surgery performed before 2003 were statistically significantly associated with crossed screw fixation, and the preoperative AOFAS score was statistically significantly higher in the locking plate fixation group. There were no statistically significant differences related to postoperative complications between the 2 fixation groups. In conclusion, the Lapidus bunionectomy fixated with a locking plate and a plantar lag screw allows earlier weight bearing in comparison with crossed lag screws, without a difference in complications. Level of Clinical Evidence: 2. PMID:19232969

Saxena, Amol; Nguyen, Aidan; Nelsen, Elise

209

Distal radius fractures: current concepts.  

PubMed

Despite the frequency of distal radius fractures, the optimal treatment remains without consensus opinion. A trend toward increased distal radius fracture open reduction and internal fixation has been identified, with biomechanical and clinical studies suggesting treatment advantages of certain fixation methods over others. Well-controlled patient trials are still missing to lend objective findings to management algorithms. This article reviews the literature over the past 5 years to guide our management regarding this common upper-extremity injury. PMID:22763062

Schneppendahl, Johannes; Windolf, Joachim; Kaufmann, Robert A

2012-07-03

210

Pedicle screw placement with O-arm and stealth navigation.  

PubMed

Various navigation systems are available to aid pedicle screw placement. The O-arm replaces the need for fluoroscopy and generates a 3-dimensional volumetric dataset that can be viewed as transverse, coronal, and sagittal images of the spine, similar to computed tomography (CT) scanning. The dataset can be downloaded to the Stealth system (Medtronic Navigation, Louisville, Colorado) for real-time intraoperative navigation.The main objectives of the current study were to assess (1) accuracy of pedicle screw placement using the O-arm/Stealth system, and (2) time for draping, positioning of the O-arm, and screw placement. Of 188 screws (25 patients), 116 had adequate images for analysis. The average time for O-arm draping was 3.5 minutes. Initial O-arm positioning was 6.1 minutes, and final positioning was 4.9 minutes. Mean time for screw placement, including O-arm draping and positioning and array attachment, was 8.1 minutes per screw. Mean time for screw placement alone was 5.9 minutes per screw. Screw placements on final O-arm images were on average 3.14 mm deeper than on the snapshot navigation images. Three screws (2.6%) breached the medial cortex, and 3 screws (2.6%) were misaligned and did not follow the pilot hole trajectory.The use of the O-arm/Stealth system was associated with a low rate of pedicle screw misalignment. The time to place screws was less than previously reported with CT navigation, but longer than conventional techniques. It is important to be aware of the potential discrepancy between snapshot navigation images and actual screw placement on final O-arm images. Our findings suggest that final screw positions may be deeper than awl positions appear on navigation images. PMID:22229616

Patil, Suresh; Lindley, Emily M; Burger, Evalina L; Yoshihara, Hiroyuki; Patel, Vikas V

2012-01-16

211

Intertrochanteric fractures in elderly high risk patients treated with Ender nails and compression screw  

PubMed Central

Background: Ender and Simon Weidner popularized the concept of closed condylocephlic nailing for intertrochanteric fractures in 1970. The clinical experience of authors revealed that Ender nailing alone cannot provide secure fixation in elderly patients with osteoporosis. Hence we conducted a study to evaluate the efficacy of a combined fixation procedure using Ender nails and a cannulated compression screw for intertrochanteric fractures. Materials and Methods: 76 patients with intertrochanteric fractures were treated using intramedullary Ender nails and cannulated compression screw from January 2004 to December 2007. The mean age of the patients was 80 years (range 70-105 years).Using the Evan’s system of classification 49 were stable and 27 unstable fractures. Inclusion criteria was high risk elderly patients (age > 70 years) with intertrochanteric fracture. The exclusion criteria included patients with pressure sores over the trochanteric region. Many patients had pre-existing co-morbidities like diabetes mellitus, hypertension, COPD, ischemic heart disease, CVA and coronary artery bypass surgery. The two Ender nails of 4.5mm each were passed across the fracture site into the proximal neck. This was reinforced with a 6.5 mm cannulated compression screw passed from the sub trochanteric region, across the fracture into the head. Results: The mean follow-up was 14 months (range 9-19 months) Average time to fracture union was 10 weeks (range 6-16 weeks). The mean knee ROM was 130° (± 5°). There was no case of nail penetration into hip joint. In five cases with advanced osteoporosis there was minimal migration of Ender nails distally. Conclusions: The Ender nailing combined with compression screw fixation in cases of intertrochanteric fractures in high risk elderly patients could achieve reliable fracture stability with minimal complications.

Gangadharan, Sidhartha; Nambiar, MR

2010-01-01

212

Pain and fracture after anterior cruciate ligament reconstruction caused by giant cell tumour of the distal femur.  

PubMed

The causes of pain after an anterior cruciate ligament (ACL) reconstruction are numerous and may have complex origins. We present an unusual case in which pain after an ACL reconstruction developed secondary to a giant cell tumour of the bone occurring around a fixation screw in the distal femur, with an associated fracture through the femoral tunnel of a previously well-functioning reconstruction. We discuss the aetiology and the treatment of a complex clinical scenario. PMID:24072827

Dowen, Daniel; Kakkar, Rahul; Dildey, Petra; Gerrand, Craig

2013-09-26

213

Load sharing properties of cervical pedicle screw-rod constructs versus lateral mass screw-rod constructs.  

PubMed

Lateral mass screws have a history of successful clinical use, but cannot always be used in the subaxial cervical spine. Despite safety concerns, cervical pedicle screws have been proposed as an alternative. Pedicle screws have been shown to be biomechanically stronger than lateral mass screws. No study, however, has investigated the load sharing properties comparing constructs using these screws. To investigate this, 12 fresh-frozen single cervical spine motion segments (C4-5 and C6-7) from six cadavers were isolated. They were randomized to receive either lateral mass or pedicle screw-rod constructs. After preloading, the segments were cyclically loaded with a uniplanar axial load from 0 to 90 N both with and without the construct in place. Pressure data at the disc space were continuously collected using a dynamic pressure sensor. The reduction in disc space pressure between the two constructs was calculated to see if pedicle screw and lateral mass screw-rod constructs differed in their load sharing properties. In both the pedicle screw and lateral mass screw-rod constructs, there was a significant reduction in the disc space pressures from the no-construct to construct conditions. The percentage decrease for the pedicle screw constructs was significantly greater than the percentage decrease for the lateral mass screw constructs for average pressure (p < or = 0.002), peak pressure (p < or = 0.03) and force (p < or = 0.04). We conclude that cervical pedicle screw-rod constructs demonstrated a greater reduction in axial load transfer through the intervertebral disc than lateral mass screw-rod constructs. Though there are dangers associated with the insertion of cervical pedicle screws, their use might be advantageous in some clinical conditions when increased load sharing is necessary. PMID:20119837

Dunlap, Bradley J; Karaikovic, Eldin E; Park, Hyung-Soon; Sokolowski, Mark J; Zhang, Li-Qun

2010-02-02

214

Failure analysis of broken pedicle screws on spinal instrumentation.  

PubMed

Revised spinal surgery is needed when there is a broken pedicle screw in the patient. This study investigated the pedicle screw breakage by conducting retrieval analyses of broken pedicle screws from 16 patients clinically and by performing stress analyses in the posterolateral fusion computationally using finite element (FE) models. Fracture surface of screws was studied by scanning electron microscope (SEM). The FE model of the posterolateral fusion with the screw showed that screws on the caudal side had larger axial stress than those on the cephalic side, supporting the clinical findings that 75% of the patients had the screw breakage on the caudal side. SEM fractography showed that all broken screws exhibited beach marks or striations on the fractured surface, indicating fatigue failure. Screws of patients with spinal fracture showed fatigue striations and final ductile fracture around the edge. Among the 16 patients who had broken pedicle screws 69% of them achieved bone union in the bone graft, showing that bone union in the bone graft did not warrant the prevention of screw breakage. PMID:15990065

Chen, Chen-Sheng; Chen, Wen-Jer; Cheng, Cheng-Kung; Jao, Shyh-Hua Eric; Chueh, Shan-Chang; Wang, Chang-Chih

2005-07-01

215

Effects of ignition interlock license restrictions on drivers with multiple alcohol offenses: a randomized trial in Maryland.  

PubMed Central

OBJECTIVES: This investigation sought to test the effectiveness of a statewide ignition interlock license restriction program for drivers with multiple alcohol-related traffic offenses. METHODS: A total of 1387 multiple offenders eligible for license reinstatement were randomly assigned to participate in an ignition interlock program (experimental group) or in the conventional postlicensing treatment program (control group). The arrest rates of these 2 groups for alcohol traffic offenses were compared for 1 year during the ignition interlock license restriction program and for 1 year after unrestricted driving privileges were returned. RESULTS: Participation in the interlock program reduced offenders' risk of committing an alcohol traffic violation within the first year by about 65%. The alcohol traffic violation rate during the first year was significantly less for participants in the interlock program (2.4%) than for those in the control group (6.7%). However, there was no statistically significant difference between these groups in the second year, after the interlock license restriction was lifted. CONCLUSIONS: Ignition interlock license restriction programs are effective at reducing recidivism among drivers with multiple alcohol offenses, at least while the restriction is in effect.

Beck, K H; Rauch, W J; Baker, E A; Williams, A F

1999-01-01

216

Simultaneous Use of Cannulated Reamer and Schanz Screw for Closed Intramedullary Femoral Nailing  

PubMed Central

Introduction. Closed reduction is a critical component of the intramedullary nailing and at times can be difficult and technically challenging resulting in increased operative time. Fluoroscopy is used extensively to achieve closed reduction which increases the intra-operative radiation exposure. Materials and Methods. Sixty patients with femoral diaphyseal fractures treated by locked intramedullary nailing were randomized in two groups. In group I, fracture reduction was performed under fluoroscopy with a cannulated reamer in the proximal fragment or with simultaneous use of a cannulated reamer in the proximal fragment and a Schanz screw in the distal fragment. Patients in group II had fracture reduction under fluoroscopy alone. Results. Closed reduction was achieved in 29 patients in group I and 25 patients in group II. The guide wire insertion time, time for nail insertion and its distal locking, total operative time, and total fluoroscopic time were 26.57, 27.93, 68.03, and 0.19 minutes in group I, compared with 30.87, 27.83, 69.93, and 0.24 minutes in group II, respectively. The average number of images taken to achieve guide wire insertion, for nail insertion and its locking and for the complete procedure in group I, respectively, was 12.33, 25.27, and 37.6 compared with 22.1, 26.17, and 48.27, respectively, in group II. Conclusion. The use of cannulated reamer in proximal fragment as intramedullary joystick and Schanz screw and in the distal fragment as percutaneous joystick facilitates closed reduction of the fracture during closed intramedullary femoral nailing with statistically significant reduction in guide wire insertion time and radiation exposure.

Rohilla, Rajesh; Singh, Roop; Magu, Narender K.; Devgan, Ashish; Siwach, Ramchander; Sangwan, Sukhbir Singh

2011-01-01

217

Retrospective Comparison of Percutaneous Fixation and Volar Internal Fixation of Distal Radius Fractures  

PubMed Central

A change in the practice of a single surgeon provided an opportunity for retrospective comparison of comparable cohorts treated with percutaneous fixation (17 patients) or a volar plate and screws (23 patients) an average of 30 months after surgery. The final evaluation was performed according to the Gartland and Werley and Mayo rating systems and the DASH questionnaire. There were no significant differences on the average scores for the percutaneous and volar plating groups, respectively: Gartland and Werley, 4 vs 5; Mayo, 82 vs 83; and DASH score 13 for both cohorts. Motion, grip, and radiographical parameters were likewise comparable. Volar internal plate and screw fixation can achieve results comparable to percutaneous fixation techniques in the treatment of fractures of the distal radius.

Lozano-Calderon, Santiago A.; Doornberg, Job N.

2007-01-01

218

Less Invasive Stabilization System for treatment of distal femur fractures.  

PubMed

The low profile of Less Invasive Stabilization System (LISS) plates allows them to be inserted between muscle and diaphysis with less bone exposure than that obtained with conventional plating techniques. In the unique LISS mechanism, unicortical screws thread into both plate and bone and allow the system to act as an internal fixator, with compressive pressure no longer bearing down on the periosteum. Results are minimal soft-tissue, periosteal, cortical, and vascular damage and no compromise in stability. This lesser degree of tissue disruption is hypothesized to accelerate bone healing, make bone grafting unnecessary, decrease infection rates, and prevent further injury by lessening overall surgical trauma. In a prospective, nonrandomized study conducted at a level I trauma center, we sought to determine the benefits of LISS plating in the treatment of distal femur fractures. Between January 1, 1998, and June 3, 2001, we treated 25 multiply injured adult patients admitted through the trauma department with 26 unstable distal femur fractures. Treatment involved minimally invasive plate osteosynthesis using LISS plating. Main outcome measures were time to union, postoperative complications, and functional impairment as measured with the SF-36v2 Health Survey. Results included no nonunions, no infections, no required bone grafting, and excellent range of motion and alignment. PMID:15195919

Ricci, Anthony R; Yue, James J; Taffet, Robert; Catalano, John B; DeFalco, Robert A; Wilkens, Kenneth J

2004-05-01

219

Torque stability of different abutment screws submitted to mechanical cycling.  

PubMed

Purpose: To evaluate the torque stability of different UCLA retention screws of single implant-supported crowns submitted to mechanical cycling. Materials and Methods: Crowns fabricated from nickel-chromium-molybdenum alloy were attached to external-hexagon implants and grouped by the different retention screws used (n = 10): Ti, titanium screws (BRUNIHT, Biomet 3i); Au, gold-palladium screws with 24-carat gold coating (Gold-Tite, Biomet 3i); TiC, titanium alloy (Ti-6Al-4V) screw with diamondlike carbon coating (Neotorque, Neodent); and TiN, Ti-6Al-4V screw with aluminum-titanium-nitride coating (Ti-Tite, Conexão). Three initial removal torque (RT) values were obtained for each screw after torque insertion using an analog torque gauge. The final RT was measured after mechanical cycling (1 × 106 cycles at 2 Hz under 130 N). Data were submitted to analysis of variance and the Fischer test. Results: Statistically significant differences were observed between the initial RT in groups Ti and TiN, and between TiC and TiN. No statistically significant difference was seen between mean RT obtained before and after mechanical cycling, except for the Ti screws. All groups exhibited similar torque maintenance after mechanical cycling. Conclusion: Although no significant difference was observed among groups for the final percentage of torque maintenance, the final RT values of the coated screws were higher than those of the noncoated screws. PMID:24066337

Vianna, Camila de Assis; Delben, Juliana Aparecida; Barão, Valentim A R; Ferreira, Mayara Barbosa; Dos Santos, Paulo Henrique; Assunçao, Wirley Gonçalves

220

Healing Results of Periprosthetic Distal Femur Fractures Treated with Far Cortical Locking Technology: A Preliminary Retrospective Study  

PubMed Central

Introduction Periprosthetic distal femur fractures are severe injuries occurring in the often osteoporotic bone of the elderly. Far cortical locking (FCL) screws, which have been shown to promote increased callus formation in animal models, have recently become available for clinical use. The purpose of this study is to report preliminary healing and complication rates of periprosthetic distal femur fractures treated with FCL constructs. Materials and Methods A retrospective review of 20 patients who underwent open reduction and internal fixation of periprosthetic distal femur fractures using FCL constructs was performed. Healing was assessed radiographically and clinically at 6, 12 and 24 weeks post-operatively. Construct failure was defined as any hardware breakage or bone-implant dissociation leading to loss of reduction. Results Complete data through the 24 week study period was available for 18/20 patients. Bridging callus was identified in 16/18 patients by the 24 week follow up for a healing rate of 88.9%. In patients that healed, the average time to medial bridging callus formation was 10.7±6.7 weeks, 11.0±6.6 weeks for anterior fracture line and 13.4±7.5 weeks for the posterior fracture line. both patients that failed to heal underwent revision surgery. Discussion The initial results of this study are comparable to results reported for distal femur periprosthetic fractures treated with locking plate fixation without FCL screws, although it was difficult to compare time to healing between previously published studies. It is the impression of the authors that callus appears earlier and is more robust and uniform between the three cortices in FCL cases compared to their previous experiences with traditional locking plate periprosthetic distal femur fractures. This work suggests that FCL screws may be superior to traditional locking constructs but further studies are needed to directly compare the two methods.

Ries, Zachary; Hansen, Kirk; Bottlang, Michael; Madey, Steven; Fitzpatrick, Daniel; Marsh, J.L.

2013-01-01

221

Comparison of the retro screw and standard interference screw for ACL reconstruction.  

PubMed

The objective of the study was to compare the load to failure between a retro screw (RS) and a standard interference screw (IS) for tibial-sided anterior cruciate ligament (ACL) fixation. We used 20 bovine tibia and extensor tendons for the study. A group of 10 specimens underwent IS fixation while the other 10 underwent RS fixation. Within each group, five specimens had graft suture in contact (interdigitating) with the screw threads. All specimens were tested on the MTS 858 Mini Bionix II (MTS Systems, Shakopee, MN). There was no statistically significant difference between the RS and IS with respect to peak load to failure. IS with suture interdigitation failed at an average of 520 N (range: 358 to 793 N), while the RS with suture interdigitation failed at 613 N (range: 438 to 1089 N). The IS without suture interdigitation failed at 654 N and the RS without suture interdigitation at 531 N. Specimens with a whipstitch in contact with the screw did not demonstrate higher pull out strength. The RS fixation strength appears to equal the IS. Graft suture contact with screw threads does not increase fixation strength. Based on this study, using a RS for tibial ACL soft tissue graft fixation is feasible and provides equal fixation strength compared with the standard IS. PMID:23057142

Wang, Robert Y; Arciero, Robert A; Obopilwe, Elifho; Mazzocca, Augustus D

2012-07-01

222

Solid and hollow pedicle screws affect the electrical resistance: A potential source of error with stimulus-evoked electromyography  

PubMed Central

Background: Although stimulus evoked electromyography (EMG) is commonly used to confirm the accuracy of pedicle screw placement. There are no studies to differentiate between solid screws and hollow screws to the electrical resistance of pedicle screws. We speculate that the electrical resistance of the solid and hollow pedicle screws may be different and then a potential source of error with stimulus-evoked EMG may happen. Materials and Methods: Resistance measurements were obtained from 12 pedicle screw varieties (6 screws of each manufacturer) across the screw shank based on known constant current and measured voltage. The voltage was measured 5 times at each site. Results: Resistance of all solid screws ranged from 0.084 ? to 0.151 ? (mean =0.118 ± 0.024 ?) and hollow screws ranged from 0.148 ? to 0.402 ? (mean = 0.285 ± 0.081 ?). There was a significant difference of resistance between the solid screws and hollow screws (P < 0.05). The screw with the largest diameter no matter solid screws or hollow screws had lower resistance than screws with other diameters. No matter in solid screws group or hollow screws group, there were significant differences (P < 0.05) between the 5.0 mm screws and 6.0 mm screws, 6.0 mm screws and 7.0 mm screws, 5.0 mm screws and 7.0 mm screws, 4.5 mm screws and 5.5 mm screws, 5.5 mm screws and 6.5 mm screws, 4.5 mm screws and 6.5 mm screws. The resistance of hollow screws was much larger than the solid screws in the same diameter group (P < 0.05). Conclusions: Hollow pedicle screws have the potential for high electrical resistance compared to the solid pedicle screws and therefore may affect the EMG response during stimulus-evoked EMG testing in pedicle screw fixation especially in minimally invasive percutaneous pedical screw fixation surgery.

Wang, Hongwei; Liao, Xinhua; Ma, Xianguang; Li, Changqing; Han, Jianda; Zhou, Yue

2013-01-01

223

Cervical and upper thoracic screwing for spinal fusion: strategy for its safe insertion to avoid major complications  

Microsoft Academic Search

There are several screwing techniques to attain cervical fusion such as pedicle screw, lateral mass screw, facet screw, transarticular\\u000a and laminar screw. Each screwing technique has advantages and disadvantages. In this study, we introduce our strategy for\\u000a safe screwing and its clinical results. Our strategy is as follows: lateral mass screw for C1, 3, 4, 5, 6 and pedicle screw

Koichi Sairyo; Toshinori Sakai; Kosaku Higashino; Tatsuya Tamura; Shinsuke Katoh; Natsuo Yasui

2009-01-01

224

[Evaluation of surgical repair of distal biceps tendon ruptures].  

PubMed

PURPOSE OF THE STUDY To present the results of surgical repair of ruptures of the distal tendon of the biceps brachii muscle and thus show the adequacy of this treatment. MATERIAL Between 1987 and 2006, 19 patients had surgery for distal biceps tendon rupture. Only one side was affected in each patient. All patients were men between 28 and 69 years (average age, 47.5 years) at the time of injury (surgery). When the patients were evaluated at the end of 2007, 18 patients were included, because one died a year after surgery. METHODS The surgical repair always included a single-incision anatomical reattachment into the radial tuberosity. In 11 patients, a modified Mac Reynolds method with screw and washer fixation was used; in seven patients the insertion was fixed with Mitek anchors and, in one, it was sutured to the adjacent soft tissues. The average follow-up was 7 years (range, 1 to 20.5 years). The patients were evaluated for the cause of injury, their physical activity, age, dominance of the injured arm, surgical procedure and complications. RESULTS In 18 patients surgical repair was done early and, in one, at 16 days after injury. In all of them the tendon was detached from its site of insertion, but never torn. The intra-operative complications included, in one patient, bleeding owing to iatrogenic damage to a branch of the brachial artery, and difficult separation of the tendon due to its previous healed injury in another patient. Early post-operative complications included superficial skin necrosis in one patient and transient neurological deficit of the dorsal brand of the radial nerve and of the lateral cutaneous nerve of the forearm in two and one patient, respectively. The late complications were heterotropic ossification in three patients and screw migration in the one treated by the Mac Reynolds method. Excellent results were recorded in 11 patients (61 %), and good outcomes with a slight restriction of motion or muscle strength not limiting the patient's physical activities were in six (33.5 %) patients; only one patient (5.5 %) experienced pain on moderate exercise and had recurrent heterotropic ossification. Apart from this condition, there was no difference in the frequency of complications associated with the method used. DISCUSSION Only sparse information on distal biceps tendon ruptures has been available in the relevant Czech literature and, if so, only small groups with short follow-ups have been involved. Conservative treatment or the methods of non-anatomical reattachment have poor functional outcomes. Much better results are achieved by anatomical reattachment. Based on our experience with the Mac Reynolds technique, an anterior single-incision approach using fixation with Mitek anchors can be recommended. CONCLUSIONS Early surgical repair involving anatomical reattachment from the anterior singleincision approach with two Mitek anchors is recommended when a rupture of the distal tendon insertion of the biceps brachii is diagnosed. Key words: biceps radii muscle, biceps tendon injury, tendon fixation, bone screw and washer use. PMID:19268049

Behounek, J; Hrubina, M; Skoták, M; Krumpl, O; Zahálka, M; Dvorák, J; Fucík, M

2009-02-01

225

49 CFR 236.401 - Automatic block signal system and interlocking standards applicable to traffic control systems.  

Code of Federal Regulations, 2012 CFR

...interlocking standards applicable to traffic control systems. 236.401 Section 236.401...MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Traffic Control Systems Standards § 236.401...

2012-10-01

226

49 CFR 236.401 - Automatic block signal system and interlocking standards applicable to traffic control systems.  

Code of Federal Regulations, 2011 CFR

...interlocking standards applicable to traffic control systems. 236.401 Section 236.401...MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Traffic Control Systems Standards § 236.401...

2011-10-01

227

Next Generation Fast RF Interlock Module and ATCA Adapter for ILC High Availability RF Test Station Demonstration  

SciTech Connect

High availability interlocks and controls are required for the ILC (International Linear Collider) L-Band high power RF stations. A new F3 (Fast Fault Finder) VME module has been developed to process both fast and slow interlocks using FPGA logic to detect the interlock trip excursions. This combination eliminates the need for separate PLC (Programmable Logic Controller) control of slow interlocks. Modules are chained together to accommodate as many inputs as needed. In the next phase of development the F3's will be ported to the new industry standard ATCA (Advanced Telecom Computing Architecture) crate (shelf) via a specially designed VME adapter module with IPMI (Intelligent Platform Management Interface). The goal is to demonstrate auto-failover and hot-swap for future partially redundant systems.

Larsen, R

2009-10-17

228

Research and application of absorbable screw in orthopedics: a clinical review comparing PDLLA screw with metal screw in patients with simple medial malleolus fracture.  

PubMed

Objective: To observe the therapeutic effect of absorbable screw in medial malleolus fracture and discuss its clinical application in orthopedics. Methods: A total of 129 patients with simple medial malleolus fracture were studied. Among them, 64 patients were treated with poly-D, L-lactic acid (PDLLA) absorbable screws, while the others were treated with metal screws. All the patients were followed up for 12-20 months (averaged 18.4 months) and the therapeutic effect was evaluated according to the American Orthopaedic Foot and Ankle Society clinical rating systems. Results: In absorbable screw group, we obtained excellent and good results in 62 cases (96.88%); in steel screw group, 61 cases (93.85%) achieved excellent and good results. There was no significant difference between the two groups. Conclusion: In the treatment of malleolus fracture, absorbable screw can achieve the same result compared with metal screw fixation. Absorbable screw is preferred due to its advantages of safety, cleanliness and avoiding the removal procedure associated with metallic implants. PMID:23384867

Tang, Jin; Hu, Jin-Feng; Guo, Wei-Chun; Yu, Ling; Zhao, Sheng-Hao

2013-02-01

229

Biomechanical analysis of expansion screws and cortical screws used for ventral plate fixation on the cervical spine  

PubMed Central

Compared to bicortical screws, the surgical risk of injuring intraspinal structures can be minimized with the use of monocortical screws. However, this reduction should not be achieved at the expense of the stability of the fixation. With monocortical stabilization, the expansion screws have the potential of absorbing high loads. Therefore, they are expected to be a suitable alternative to bicortical screws for revision surgeries and in osteoporotic bone. The purpose of this in vitro study was to investigate the stiffness of the two screw-plate systems used for ventral stabilization of the cervical spine, by focusing on the suitability of expansion screws as tools for revision treatments. The study was conducted in ten functional units of human cervical spines. The device sample stiffness was determined for four conditions using a turning moment of 2.25 N m each around one of the three principle axes. The conditions were native, destabilized, primarily stabilized with one of the screw-plate systems, followed by secondary stabilization using the expansion screw implant. The stabilized samples achieved a comparable, in most cases higher stiffness than the native samples. The samples undergoing secondary stabilization using expansion screws tend to display greater stiffness for all three axes compared to the primarily stabilized samples. The achieved tightening moment of the screws was higher than the one achieved with primary fixation. Both plates revealed similar primary stability. Revision surgeries with secondary instrumentation achieve a high stiffness of the screwed up segments. Monocortical expansion screws combined with a trapezoidal plate allow ventral stabilization of the cervical spine that is comparable to the plate fixation using bicortical screws.

Ullrich, Bernhard; Huber, Gerd; Morlock, Michael M.

2009-01-01

230

Biomechanical analysis of expansion screws and cortical screws used for ventral plate fixation on the cervical spine.  

PubMed

Compared to bicortical screws, the surgical risk of injuring intraspinal structures can be minimized with the use of monocortical screws. However, this reduction should not be achieved at the expense of the stability of the fixation. With monocortical stabilization, the expansion screws have the potential of absorbing high loads. Therefore, they are expected to be a suitable alternative to bicortical screws for revision surgeries and in osteoporotic bone. The purpose of this in vitro study was to investigate the stiffness of the two screw-plate systems used for ventral stabilization of the cervical spine, by focusing on the suitability of expansion screws as tools for revision treatments. The study was conducted in ten functional units of human cervical spines. The device sample stiffness was determined for four conditions using a turning moment of 2.25 N m each around one of the three principle axes. The conditions were native, destabilized, primarily stabilized with one of the screw-plate systems, followed by secondary stabilization using the expansion screw implant. The stabilized samples achieved a comparable, in most cases higher stiffness than the native samples. The samples undergoing secondary stabilization using expansion screws tend to display greater stiffness for all three axes compared to the primarily stabilized samples. The achieved tightening moment of the screws was higher than the one achieved with primary fixation. Both plates revealed similar primary stability. Revision surgeries with secondary instrumentation achieve a high stiffness of the screwed up segments. Monocortical expansion screws combined with a trapezoidal plate allow ventral stabilization of the cervical spine that is comparable to the plate fixation using bicortical screws. PMID:19588171

Röhl, Klaus; Ullrich, Bernhard; Huber, Gerd; Morlock, Michael M

2009-07-09

231

NSTX Protection And Interlock Systems For Coil And Powers Supply Systems  

SciTech Connect

NSTX at Princeton Plasma Physics Laboratory (PPPL) requires sophisticated plasma positioning control system for stable plasma operation. TF magnetic coils and PF magnetic coils provide electromagnetic fields to position and shape the plasma vertically and horizontally respectively. NSTX utilizes twenty six coil power supplies to establish and initiate electromagnetic fields through the coil system for plasma control. A power protection and interlock system is utilized to detect power system faults and protect the TF coils and PF coils against excessive electromechanical forces, overheating, and over current. Upon detecting any fault condition the power system is restricted, and it is either prevented from initializing or suppressed to de-energize coil power during pulsing. Power fault status is immediately reported to the computer system. This paper describes the design and operation of NSTX's protection and interlocking system and possible future expansion.

X. Zhao, S. Ramakrishnan, J. Lawson, C.Neumeyer, R. Marsala, H. Schneider, Engineering Operations

2009-09-24

232

Interlocked feedforward loops control cell type-specific Rhodopsin expression in the Drosophila eye  

PubMed Central

How complex networks of activators and repressors lead to exquisitely specific cell type determination during development is poorly understood. In the Drosophila eye, expression patterns of Rhodopsins define at least eight functionally distinct though related subtypes of photoreceptors. Here, we describe a role for the transcription factor gene defective proventriculus (dve) as a critical node in the network regulating Rhodopsin expression. dve is a shared component of two opposing, interlocked feedforward loops (FFLs). Orthodenticle and Dve interact in an incoherent FFL to repress Rhodopsin expression throughout the eye. In the R7 and R8 photoreceptors, a coherent FFL relieves repression by Dve while activating Rhodopsin expression. Therefore, this network uses repression to restrict, and combinatorial activation to induce cell type-specific expression. Further, Dve levels are finely tuned to yield cell type- and region-specific repression or activation outcomes. This interlocked FFL motif may be a general mechanism to control terminal cell fate specification.

Johnston, Robert J.; Otake, Yoshiaki; Sood, Pranidhi; Vogt, Nina; Behnia, Rudy; Vasiliauskas, Daniel; McDonald, Elizabeth; Xie, Baotong; Koenig, Sebastian; Wolf, Reinhard; Cook, Tiffany; Gebelein, Brian; Kussell, Edo; Nagakoshi, Hideki; Desplan, Claude

2011-01-01

233

An interwoven metal-organic framework combining mechanically interlocked linkers and interpenetrated networks.  

PubMed

New dibenzo[24]crown-8 ether derivatives were prepared that contain appendages with thioether donors that can coordinate to a metal ion. These macrocycles were then combined with 1,2-bis(pyridinium) ethane axles to create two types of [2]rotaxane ligands; those with the four thioether donors on the crown ether and those with six donor groups, four from the crown ether and two more attached to the stoppering groups of the dumbbell. The crown ethers and both types of [2]rotaxane ligands were allowed to react with Ag(I) ions to form metal-organic rotaxane framework (MORF) style coordination polymers. The interlocked hexadentate ligand forms the first example of a new type of lattice containing interwoven frameworks resulting from both interpenetration of frameworks due to the presence of an interlocked ligand and more classical interpenetration of independent frameworks. PMID:24019167

Frank, Nissa C; Mercer, Darren J; Loeb, Stephen J

2013-09-09

234

Design lessons from using programmable controllers in the MFTF-B personnel safety and interlocks system  

SciTech Connect

Applying programmable controllers in critical applications such as personnel safety and interlocks systems requires special considerations in the design of both hardware and software. All modern programmable controller systems feature extensive internal diagnostic capabilities to protect against problems such as program memory errors; however most, if not all present designs lack an intrinsic capability for detecting and countering failures on the field-side of their I/O modules. Many of the most common styles of I/O modules can also introduce potentially dangerous sneak circuits, even without component failure. This paper presents the most significant lessons learned to date in the design of the MFTF-B Personnel Safety and Interlocks System, which utilizes two non-redundant programmable controllers with over 800 I/O points each. Specific problems recognized during the design process as well as those discovered during initial testing and operation are discussed along with their specific solutions in hardware and software.

Branum, J.D.

1983-11-29

235

Transiliac-transsacral screws for posterior pelvic stabilization.  

PubMed

Typical posterior pelvic fixation constructs use one or more large screws inserted from the lateral iliac cortex into the safe upper sacral ala or body. As a result of the deforming forces acting perpendicular to the implant axis, routine iliosacral screw fixation may not provide adequate stabilization, especially in certain unstable injuries. Longer iliosacral screws that traverse the entire upper sacrum and exit the contralateral iliac cortex may improve holding power and also stabilize concomitant contralateral posterior pelvic injuries. These transiliac-transsacral screws are reliably safe to insert using routine intraoperative fluoroscopy, and they provide durable fixation. These screws require careful preoperative planning and more precise technical attention during insertion because they pass through both sacral alar zones. Transiliac-transsacral screws may be particularly useful in the presence of osteoporosis, significant posterior pelvic instability including spinopelvic dissociation, patient obesity, anticipated noncompliant behavior, bilateral posterior pelvic injuries, and nonunion procedures. PMID:21577075

Gardner, Michael J; Routt, M L Chip

2011-06-01

236

Missing Screw as a Rare Complication of Anterior Cervical Instrumentation  

PubMed Central

Although anterior cervical arthrodesis is an effective procedure for the treatment of cervical disorders, the method has some complications. Here, we describe this rare complication of cervical instrumentation with a literature review. A 23-year-old male patient was operated for a C6-C7 dislocation. At postoperative month 10, he presented with hemoptysis and dysphagia. Cervical roentgenograms showed anterior migrations of one broken screw and a plate-locking screw at the C6 corpus. One screw was missing. We concluded that the missing screw had perforated the esophagus and had been eliminated spontaneously through the gastrointestinal tract. No screw should migrate. Even loose screws should be noted in follow-up X-ray studies. If such findings are detected, a second operation for revision should be considered as soon as possible to prevent potentially fatal complications.

Duransoy, Yusuf Kurtulus; Mete, Mesut; Zengel, Baha; Selcuk?, Mehmet

2013-01-01

237

Coalescence of 3-phenyl-propynenitrile on Cu(111) into interlocking pinwheel chains  

NASA Astrophysics Data System (ADS)

3-phenyl-propynenitrile (PPN) adsorbs on Cu(111) in a hexagonal network of molecular trimers formed through intermolecular interaction of the cyano group of one molecule with the aromatic ring of its neighbor. Heptamers of trimers coalesce into interlocking pinwheel-shaped structures that, by percolating across islands of the original trimer coverage, create the appearance of gear chains. Density functional theory aids in identifying substrate stress associated with the chemisorption of PPN's acetylene group as the cause of this transition.

Luo, Miaomiao; Lu, Wenhao; Kim, Daeho; Chu, Eric; Wyrick, Jon; Holzke, Connor; Salib, Daniel; Cohen, Kamelia D.; Cheng, Zhihai; Sun, Dezheng; Zhu, Yeming; Einstein, T. L.; Bartels, Ludwig

2011-10-01

238

Successfully Exploiting Two Opposing Forces: A Rational Explanation for the “Interlocking Suture”  

Microsoft Academic Search

Background  Issues of poor circumareolar scars and asymmetry or malposition of the nipple–areola complex (NAC) are frequently associated\\u000a with those breast reduction or pexy techniques that rely on an ample excision of skin around the areola, either alone or associated\\u000a with a vertical scar in a circumvertical approach. To prevent such problems, in 2007 Hammond et al. introduced the “interlocking\\u000a suture.”

Bernardo RighiEnrico Robotti; Enrico Robotti

2011-01-01

239

D0 Central Tracking Solenoid Energization, Controls, Interlocks and Quench Protection Operating Procedures  

SciTech Connect

This procedure is used when it is necessary to operate the solenoid energization, controls, interlocks and quench detection system. Note that a separate procedure exists for operating the solenoid 'cryogenic' systems. Only D0 Control Room Operators or the Project Electrical Engineer are qualified to execute these procedures or operate the solenoid system. This procedure assumes that the operator is familiar with using the Distributed Manufacturing Automation and Control Software (DMACS).

Hance, R.; /Fermilab

1998-08-26

240

Formation of tough interlocking microstructures in silicon nitride ceramics by dynamic ripening  

Microsoft Academic Search

Ceramics based on Si3N4 have been comprehensively studied and are widely used in structural applications. The development of an interlocking microstructure of elongated grains is vital to ensure that this family of ceramics have good damage tolerance. Until now this has been accomplished by heating the appropriate powder compacts to temperatures above 1,700°C for extended periods. This procedure involves a

Zhijian Shen; Zhe Zhao; Hong Peng; Mats Nygren

2002-01-01

241

Model Checking Safety Critical Software with SPIN: an Application to a Railway Interlocking System  

Microsoft Academic Search

This paper describes an industrial application in formal verification. The analyzed system is the Safety Logic of an interlocking\\u000a system for the control of railway stations developed by Ansaldo. The Safety Logic is a process-based software architecture,\\u000a which can be configured to implement difierent functions and control stations of difierent topology.\\u000a \\u000a The applied technique, model checking, allows for the representation

Alessandro Cimatti; Fausto Giunchiglia; Giorgio Mongardi; Dario Romano; Fernando Torielli; Paolo Traverso

242

CT differentiation of distal pancreas fat replacement and distal pancreas agenesis  

Microsoft Academic Search

We aimed to describe CT signs useful for differentiation of distal agenesis from distal or dorsal pancreas lipomatosis. Multidetector\\u000a CT (MDCT) studies of five patients with distal pancreas agenesis (n = 2), distal lipomatosis (n = 1), distal short pancreas (n = 1), and distal pancreatectomy (n = 1) were retrospectively reviewed. Agenesis of dorsal pancreas can be diagnosed by the absence of body and tail of pancreas.

Musturay Karcaaltincaba

2006-01-01

243

A Note on the Effectiveness of the House-Arrest Alternative for Motivating DWI Offenders to Install Ignition Interlocks  

PubMed Central

Problem The effectiveness of ignition interlocks at reducing drunk driving has been limited by the ability of driving-while-intoxicated (DWI) offenders to avoid court orders to install the devices. Methods In a pilot program in New Mexico, four Santa Fe County judges imposed home confinement (via electronic monitoring bracelets) on offenders who claimed to have no car or no intention to drive. Interlock installation rates for Santa Fe County were compared with all other counties in New Mexico over a 2-year program and 2-year post-program period. Results During the two program years, 70% of the drivers convicted of DWI in Santa Fe County installed interlocks, compared to only 17% in the other counties, but when the program was terminated, the Santa Fe installation rate fell by 18.8 percentage points. Summary Mandating the alternative sanction of house arrest led to the highest reported interlock installation rate for DWI offenders. Impact on Industry Impaired driving is a substantial expense to employers, particularly when it bars driving that interferes with employment. Interlocks provide a method of protecting the public while permitting the offender to drive sober. This study was directed at increasing interlock use by DWI offenders.

Roth, Richard; Marques, Paul R.; Voas, Robert B.

2009-01-01

244

Interlocked host anion recognition by an indolocarbazole-containing [2]rotaxane.  

PubMed

The design, synthesis, structure, and anion-binding properties of the first indolocarbazole-containing interlocked structure are described. The novel [2]rotaxane molecular structure incorporates a neutral indolocarbazole-containing axle component which is encircled by a tetracationic macrocycle functionalized with an isophthalamide anion recognition motif. (1)H NMR and UV-visible spectroscopies and X-ray crystallography demonstrated the importance of pi-donor-acceptor, CH...pi, and electrostatic interactions in the assembly of pseudorotaxanes between the electron-deficient tetracationic macrocycle and a series of pi-electron-rich indolocarbazole derivatives. Subsequent urethane stoppering of one of these complexes afforded a [2]rotaxane, which was shown by (1)H NMR spectroscopic titration experiments to exhibit enhanced chloride and bromide anion recognition compared to its non-interlocked components. Computational molecular dynamics simulations provide further insight into the mechanism and structural nature of the anion recognition process, confirming it to involve cooperative hydrogen-bond donation from both macrocycle and indolocarbazole components of the rotaxane. The observed selectivity of the [2]rotaxane for chloride is interpreted in terms of its unique interlocked binding cavity, defined by the macrocycle isophthalamide and indolocarbazole N-H protons, which is complementary in size and shape to this halide guest. PMID:19296631

Brown, Asha; Mullen, Kathleen M; Ryu, Jay; Chmielewski, Micha? J; Santos, Sérgio M; Felix, Vitor; Thompson, Amber L; Warren, John E; Pascu, Sofia I; Beer, Paul D

2009-04-01

245

Screw-matrix method in dynamics of multibody systems  

Microsoft Academic Search

In the present paper the concept of screw in classical mechanics is expressed in matrix form, in order to formulate the dynamical\\u000a equations of the multibody systems. The mentioned method can retain the advantages of the screw theory and avoid the shortcomings\\u000a of the dual number notation. Combining the screw-matrix method with the tool of graph theory in Roberson\\/Wittenberg formalism.

Liu Yanzhu

1988-01-01

246

Surgical Treatment for Unstable Distal Clavicle Fracture with Micromovable and Anatomical Acromioclavicular Plate  

PubMed Central

Between 2006 and 2009, 18 patients of distal clavicle fracture were treated with micro-movable and anatomical acromioclavicular plate (MAAP) in our department. According to the Neer's classification, all cases were unstable with type IIA (12 cases) and type IIB (6 cases). Functional outcome was evaluated using the Karlsson's criteria. The mean follow-up was 18 months (range, 12-36months). No postoperative plate screws complication was observed. Osseous union could be achieved at a mean time of 12 weeks after operation in 18 patients (range, 8 -16 weeks). According to Karlsson's criteria, radiographic appearances and postoperative shoulder functional recovery revealed a good and excellent rate in these cases. We conclude that surgical treatment using MAAP seems to be a good option for unstable type II fractures of the distal clavicle. This technique allows for reliable fixation with early functional exercises and functional recovery.

Liu, Qingjun; Miao, Jianyun; Lin, Bin; Lian, Kejian

2012-01-01

247

Evaluation of screw loosening on new abutment screws and after successive tightening.  

PubMed

This study evaluated the loss of the torque applied after use of new screws and after successive tightening. Four infrastructures (IE), using UCLA castable abutment type, were cast in cobalt-chromium alloy and new abutment screws (G1) were used in a first moment. Subsequently, the same abutment screws were used a second time (G2) and more than two times (G3). The values of the torques applied and detorques were measured with a digital torque wrench to obtain the values of initial tightening loss (%). Data were analyzed by ANOVA and Tukey's test (?=0.05). Significant differences were observed between the G1 (50.71% ± 11.36) and G2 (24.01% ± 3.33) (p=0.000) and between G1 (50.71% ± 11.36) and G3 (25.60% ± 4.64) (p=0.000). There was no significant difference between G2 and G3 (p=0.774). Within the limitations of the study, it may be concluded that the percentage of the initial torque loss is lower when screws that already suffered the application of an initial torque were used, remaining stable after application of successive torques. PMID:21519649

Barbosa, Gustavo Seabra; Silva-Neto, João Paulo da; Simamoto-Júnior, Paulo Cezar; Neves, Flávio Domingues das; Mattos, Maria da Gloria Chiarello de; Ribeiro, Ricardo Faria

2011-01-01

248

[Fixation of periprosthetic femur fractures with the less invasive stabilization system (LISS)--a new minimally invasive treatment with locked fixed-angle screws].  

PubMed

The Less Invasive Stabilization System (LISS) is a minimally invasive technique indicated for fixation of periprosthetic fractures. This new system allows percutaneous placement of cortical-shaft screws and fixation of the fracture with fixed-angle locked screws with minimal surgical exposure of the mostly osteoporotic bone and without disturbance of the existing total joint replacement. Immediate range-of-motion exercises are begun postoperatively. A retrospective clinical review of 5 patients (2 total hip arthroplasties, 3 total knee arthroplasties) was performed to describe indications, surgical technique, intra- and postoperative complications and patient follow-up. Indications are periprosthetic distal femur fractures, per- and supracondylar fractures. Contraindications are none, except existing medical comorbidities. Extraarticular fractures were treated via stab incisions over the lateral femoral condyle. Fractures with intraarticular displacement were fixed via an anterolateral parapatellar approach to the knee joint. After anatomic reduction of femoral condyles, articular fragments are fixed with Kirschner wires, followed by closed reduction aligning the articular fragments controlling length, axis and rotation. The LISS is introduced proximally under the M. vastus lateralis along the femur. It is fixed with self-drilling cortical shaft screws, locked fixed-angle screws both proximally and distally. Range-of-motion exercises are begun on the second day postoperatively. Time to full weight bearing averaged 6-8 weeks depending on clinical and radiological findings. Benefits of the LISS technique include the minimally invasive approach with increased primary stability using monocortical fixings thus eliminating the need for spongiosaplasty and blood transfusion. Disadvantages of the percutaneous placement of the LISS include malplacement on the femur, proximal screw pull-out and postoperative rotational and axial malalignment. PMID:12594614

Kolb, W; Guhlmann, H; Friedel, R; Nestmann, H

2003-01-01

249

Modeling bicortical screws under a cantilever bending load.  

PubMed

Cyclic loading of surgical plating constructs can precipitate bone screw failure. As the frictional contact between the plate and the bone is lost, cantilever bending loads are transferred from the plate to the head of the screw, which over time causes fatigue fracture from cyclic bending. In this research, analytical models using beam mechanics theory were developed to describe the elastic deflection of a bicortical screw under a statically applied load. Four analytical models were developed to simulate the various restraint conditions applicable to bicortical support of the screw. In three of the models, the cortical bone near the tip of the screw was simulated by classical beam constraints (1) simply supported, (2) cantilever, and (3) split distributed load. In the final analytical model, the cortices were treated as an elastic foundation, whereby the response of the constraint was proportional to screw deflection. To test the predictive ability of the new analytical models, 3.5?mm cortical bone screws were tested in a synthetic bone substitute. A novel instrument was developed to measure the bending deflection of screws under radial loads (225?N, 445?N, and 670?N) applied by a surrogate surgical plate at the head of the screw. Of the four cases considered, the analytical model utilizing an elastic foundation most accurately predicted deflection at the screw head, with an average difference of 19% between the measured and predicted results. Determination of the bending moments from the elastic foundation model revealed that a maximum moment of 2.3?N m occurred near the middle of the cortical wall closest to the plate. The location of the maximum bending moment along the screw axis was consistent with the fracture location commonly observed in clinical practice. PMID:24105350

James, Thomas P; Andrade, Brendan A

2013-12-01

250

[The VB system: a new modular osteosynthesis material involving both screws and wires].  

PubMed

VB is an osteosynthesis system for the stabilisation of small fragments, which combines the benefits of both wires and screws. It is a modular system comprising a threaded pin and a ring. The threaded pin is first positioned. Then a ring is grasped and opened by the progressive angulation of a screwdriver. Still anchored on the screwdriver, the ring slides easily on the pin. It is clamped on the pin by simply removing the screwdriver and the pin is then cut. This modular system includes 1.8 and 1.1 mm pins and different types of rings (threaded or non threaded, with or without collars). The system is easy to handle and can be introduced using an open or percutaneous technique, allowing compression or distraction. Our preliminary series, performed in accordance with National clinical trial protocol (Huriet) consisted of 50 cases in 24 patients (five women and 19 men) with an average age of 48 years, and a follow-up of more than six months. Fourteen cases of fractures (28 implants) were treated as emergencies (two radial heads, one capitellum, one trochlea of the humerus, seven distal radius fractures, one trapezium, two metacarpals) and 12 cases (22 implants) were elective cases: arthrodesis (one trapezo-metacarpal, one intermetacarpal, two interphalangeal, two carpal), non-union (six scaphoids, one phalangeal) and one phalangeal malunion. Hardware removal was performed in 16 cases. No implant failure has been detected. One case, a DIP arthrodesis, had a suspicion of sepsis which led to the removal of the implants at six weeks. The results of this study have convinced us of the merits of the system, which combines the advantages of both wires and screws. The system allows the user to perform either distraction or compression, and to adjust the force by hand. Compared to the fixed amount of compression produced by lag screws, this feature seems to be a real step forward. PMID:11885383

Dubert, T; Valenti, P; Dinh, A; Osman, N

2002-01-01

251

Posttreatment evaluation of the distal jet appliance  

Microsoft Academic Search

This study analyzed molar distalization with the distal jet appliance, its effect on the anchor teeth, and the outcome at the completion of orthodontic treatment. Pretreatment, after distalization, and posttreatment lateral cephalometric radiographs were evaluated for 21 adolescent girls and 12 adolescent boys. The mean age of the subjects at the time of the pretreatment radiograph was 12.8 ± 2.2

Vonny Ngantung; Ram S. Nanda; S. Jay Bowman

2001-01-01

252

Percutaneous hemi-epiphysiodesis using transphyseal cannulated screws for genu valgum in adolescents  

PubMed Central

Purpose The purpose of this study was to assess percutaneous femoral distal hemi-epiphysiodesis using transphyseal cannulated screws in order to correct valgus angular deformities of the knee in pediatric and adolescent patients. Methods This is a prospective longitudinal study in which our experience with 52 patients is described. Results We evaluated 100 knees surgically managed for pathologic genu valgum over a 68-month period. The average age at surgery for boys and girls was 14 years and 7 months (range 12.7–15.1 years) and 13 years and 6 months (range 12.9–14.8 years), respectively. The pre-surgical tibiofemoral (T–F) angle was measured at between 14.17° and 35.3°, and the postoperative T–F was measured at between 6.2° and 15.8° (7.2° ± 0.65°, mean ± standard deviation), for an average correction of 0.73° ± 0.45° per month). The mean follow-up after surgery was 3.2 years (range 2.3–5.3 years). Conclusions We demonstrate a simple, fast and reproducible surgical technique for percutaneous epiphysiodesis with low morbidity, rapid rehabilitation and a rapid return to school and sports activities. We experienced no complications, such as overcorrection, undercorrection, postoperative hematoma or infection. We conclude that percutaneous screw epiphysiodesis is an excellent option for the treatment of genu valgum in adolescents.

Yamhure, Fernando Helo

2009-01-01

253

Noncompliance unilateral maxillary molar distalization:.  

PubMed

The aim of this prospective study was the three-dimensional (3-D) analysis of tooth movements after unilateral upper molar distalization by means of a noncompliance intraoral appliance, the Keles slider. This appliance exerts a distalizing force of 150 g at approximately the level of the center of resistance of the upper first molar. Twelve patients (six girls and six boys with a mean age of 13.1 years) with a unilateral Class II molar relationship participated in the study. Dental casts were taken immediately before placement and after removal of the appliance. The casts were digitized using a 3-D surface laser scanner and superimposed on a predefined area of the palate. The average unilateral upper first molar distal movement was 3.1 mm (range: 2.4 to 5.3 mm). Anchorage loss was expressed by a 2.1 mm (range: 0.8 to 3.8 mm) proclination of the central incisors and a 6.1 degrees mesial inclination of the ipsilateral first premolar (range: 1.7 degrees to 12.3 degrees ). There was approximately 1 mm of midline deviation toward the contralateral side and a 1.6 mm (range: 0.8 to 2.3 mm) buccal displacement of the contralateral first premolar. A substantial variation was observed among patients. Noncompliance unilateral upper molar distalization was an efficient treatment approach. There was, however, a substantial anchorage loss. Case selection is strongly recommended because significant anterior crowding, ectopic canines, or spacing can lead to significant anchorage loss. PMID:16637715

Mavropoulos, Anestis; Sayinsu, Korkmaz; Allaf, Ferdi; Kiliaridis, Stavros; Papadopoulos, Moschos A; Keles, Ahmet Ozlem

2006-05-01

254

Time derivatives of screws with applications to dynamics and stiffness  

Microsoft Academic Search

Screw quantities provide geometric insight into three-dimensional mechanics modeled by rigid bodies and lumped parameters. Four distinct cases of time differentiation are examined by combining fixed and moving body derivatives (fundamental to rigid body mechanics) with material and local derivatives (fundamental to continuum mechanics). Three combinations always yield another screw quantity while the most common, the material derivative with respect

Harvey Lipkin

2005-01-01

255

Complications of transpedicular screw fixation in the cervical spine  

Microsoft Academic Search

Today, posterior stabilization of the cervical spine is most frequently performed by lateral mass screws or spinous process wiring. These techniques do not always provide sufficient stability, and anterior fusion procedures are added secondarily. Recently, transpedicular screw fixation of the cervical spine has been introduced to provide a one-stage stable posterior fixation. The aim of the present prospective study is

E. Kast; K. Mohr; H.-P. Richter; W. Börm

2006-01-01

256

Pedicle screw insertion: computed tomography versus fluoroscopic image guidance  

PubMed Central

Computed tomography image-guided surgery (CTGS) clearly improves the accuracy of pedicle screw insertion. Recent reports claim that a fluoroscopy-guided system (FGS) offered high accuracy and easy application. However, the superiority of either technique remains unclear in clinical application. This study compares the accuracy of pedicle screws installed using CTGS with that of screws installed using FGS. Seventy-four screws inserted using FGS in 13 patients and 76 screws inserted using CTGS in 11 patients were compared. The study population included ten cases of vertebral fracture, five cases of degenerative spondylolisthesis, three cases of spondylolytic spondylolisthesis, two cases of tuberculous spondylitis, two cases of failed earlier back surgery and two case of ankylosing spondylitis with pseudarthrosis. The installed vertebral levels ranged from T8 to S1. Screw positions were assessed with postoperative radiographs and computed tomography. Sixty-nine (93.2%) screws were correctly placed in the FGS group, and seventy-three (96.1%) screws were correctly placed in the CTGS group (P?=?0.491). The results indicated that both image-guided systems offer high accuracy. However, the fluoroscope image-guided system could be considered the primary tool for lower thoracic and lumbosacral pedicle placement because it enables real-time navigation and does not require a preoperative CT scan.

Fu, Tsai-Sheng; Wong, Chak-Bor; Tsai, Tsung-Ting; Liang, Yen-Chiu; Chen, Lih-Huei

2007-01-01

257

An integrated model for the performance calculation of Screw Machines  

Microsoft Academic Search

There is a need to develop improved analytical procedures in order to improve performance, reduce noise emission and reduce the manufacturing costs of screw compressors. Most mathematical models, used by industry for screw compressor performance estimation and optimisation, are based on quasi one dimensional calculation of the governing flow equations in a control volume. Despite being fast and accurate for

Ahmed Kovacevic; Elvedin Mujic; Nikola Stosic; Ian K. Smith

258

Accuracy of Pedicle Screw Placement in Thoracic Spine Fractures  

Microsoft Academic Search

Background and Purpose: Transpedicular instrumentation in the thoracic spine is technically difficult because of small pedicle diameters. There are not many studies assessing in vivo accuracy, complications, and the revision rate of transpedicular screws in the thoracic spine. In this retrospective study 278 thoracic pedicle screws of 43 patients were assessed using a scoring system and postoperative computed tomography (CT)

Marty Zdichavsky; Michael Blauth; Christian Knop; Joachim Lotz; Christian Krettek; Leonard Bastian

2004-01-01

259

T1 intralaminar screws: an anatomic, morphologic study.  

PubMed

In some scenarios, such as complex revisions or tumor cases, intralaminar screw placement in the upper thoracic spine can be used to supplement or replace traditional pedicle screw placement. Despite the theortic feasibility of placing these screws, no thorough anatomic study has evaluated the morphology of the T1 lamina for screw placement.Anatomic data of the T1 lamina, including height, width (the upper, middle, and lower one-third segments), and length (with and without penetration of the facet articulation) were analyzed for 112 T1 vertebrae. The placement of screws with widths of 3.5 or 4 mm and screws with lengths of 24 or 26 mm in the T1 lamina was feasible in all of the laminas measured with the exception of 2 outliers. Furthermore, relationships were found between T1 lamina size and patient height and between T1 lamina size and sex, but no relationship was found between T1 lamina size and race.The morphology of the T1 lamina allows for the simple and safe placement of common screw diameters and is a viable salvage or alternative to the traditional pedicle screw. PMID:23590788

Weaver, John; Seipel, Shane; Eubanks, Jason

2013-04-01

260

Radiographic criteria for placement of translaminar facet screws  

Microsoft Academic Search

Background contextScrew fixation of the facet joint has been reported to stabilize the lumbar spine and facilitate spinal fusion. Accurate placement of translaminar facet screws (TLFSs) requires identification of the posterior spinal elements, and the facet joints in particular, which may be facilitated by intra-operative fluoroscopy.

Frank M Phillips; Erling Ho; Benjamin W Cunningham

2004-01-01

261

Screw dislocations in GaN  

SciTech Connect

GaN has received much attention over the past few years because of several new applications, including light emitting diodes, blue laser diodes and high-power microwave transistors. One of the biggest problems is a high density of structural defects, mostly dislocations, due to a lack of a suitable lattice-matched substrate since bulk GaN is difficult to grow in large sizes. Transmission Electron Microscopy (TEM) has been applied to study defects in plan-view and cross-sections on samples prepared by conventional techniques such as mechanical thinning and precision ion milling. The density of dislocations close to the sample surface of a 1 mm-thick HVPE sample was in the range of 3x109 cm-2. All three types of dislocations were present in these samples, and almost 50 percent were screw dislocations. Our studies suggest that the core structure of screw dislocations in the same material might differ when the material is grown by different methods.

Liliental-Weber, Zuzanna; Jasinski, Jacek B.; Washburn, Jack; O'Keefe, Michael A.

2002-02-15

262

Evaluation of a fiber reinforced drillable bone cement for screw augmentation in a sheep model--mechanical testing.  

PubMed

We evaluated the mechanical properties of a novel fiber reinforced calcium phosphate at time zero and after 12 weeks in vivo using a sheep long bone osteotomy model. Time zero data were obtained and compared by pullout testing of 4.5 mm bone screws from bone proper and overdrilled defects of 4.5 and 8 mm diameter. Defects were augmented with: polymethylmethacrylate (PMMA), calcium phosphate, and fiber reinforced calcium phosphate using cadaveric sheep tibiae. Twelve-week data were obtained from explanted tibiae of sheep that underwent unilateral tibial osteotomy surgery repaired with a locking compression plate. The most distal hole was overdrilled to 4.5 or 8 mm diameter, filled with fiber reinforced cement, drilled, tapped and a 4.5 mm screw was placed. Screw holding strength at t= 0 was significantly higher for reinforced when compared to nonreinforced cement, but not different from bone or PMMA in 4.5 mm defects. There was no difference in pullout strength for the 8 mm defect data. After 12 weeks fiber reinforced pullout strength increased by 45% and 8.9% for 4.5 and 8 mm defects, respectively, when compared to t= 0 testing. Fiber reinforced calcium phosphate bone cement can be drilled and tapped to support orthopedic hardware for trauma applications. PMID:20590681

Ahern, Benjamin J; Harten, Robert D; Gruskin, Elliott A; Schaer, Thomas P

2010-06-01

263

Failure of volar locking plate fixation of an extraarticular distal radius fracture: A case report  

PubMed Central

Background Volar locking plates provide significant structural stability to the distal radius. Failure of a volar locked plating is a rarely reported complication in the literature. Case Presentation A 40 year-old, obese female patient who presented with a displaced extraarticular distal radius fracture, underwent open reduction and internal fixation of the fracture using a volar locking plate. Radiographs taken at 10 weeks postoperatively showed failure of fixation with breakage of the four distal locking screws. A hardware removal was performed at 6 months, and the patient was then lost to follow-up. She presented again at 18 months after the first surgery, with significant pain, and radiographic signs of a radial collapse and a fracture-nonunion. A total wrist fusion was performed as the method of choice at that point in time. Conclusion Volar locked plating represents the new "gold standard" of distal radius fracture fixation. However, despite the stability provided by locking plates, hardware failure may occur and lead to a cascade of complications which will ultimately require a wrist fusion, as outlined in this case report. Additional structural support by bone grafting may be needed in selected cases of volar locked plating, particularly in patients with a high risk of developing a fracture-nonunion.

2010-01-01

264

Intraosseous screw fixation of anterior cervical graft construct after diskectomy.  

PubMed

This article describes a new technique of intraosseous screw fixation of the cervical spine, as well as a retrospective review of 27 patients who had anterior cervical interbody fusion after diskectomy and fixation with one intraosseous Herbert screw, with a minimum follow-up of 1 year. The study included 19 men and eight women. There were no neurologic complications at final follow-up evaluation. All patients had radiographic evidence of fusion. No screw breakage, back-out, or dislodgement occurred. Optimal intraoperative radiographic evaluation for accurate intraosseous screw placement is recommended. The use of intraosseous screw fixation is a useful addition to the armamentarium of the spine surgeon when fixation of anterior cervical graft after diskectomy is required. One hundred percent rate of union and prevention of complications related to the currently used anterior fixation systems are the major advantages of this method. PMID:8003829

Chang, K W; Lin, G Z; Liu, Y W; Suen, K L; Liang, P L

1994-04-01

265

A new volar plate DiPhos-RM for fixation of distal radius fracture: preliminary report.  

PubMed

We analyzed the efficiency of a new plate DiPhos-RM in CFR-PEEK [carbon-fiber-reinforced poly (etheretherketone)] for the volar fixation of distal radius fractures. The new plate's composition has the advantage of x-ray absolute transparency, therefore allowing to monitor the healing of the fracture. The desired combination of high strength and low rigidity is obtained through the use of the polymer composites CFR-PEEK. In this preliminary study (from March 2012 to June 2012), 10 cases of intra-articular distal radius fractures were treated with DiPhos-RM produced by Lima Corporate (Italy). The fractures were classified according to the AO classification, 4 fractures were type C1, 3 type C2, and 3 were A2. A preoperative computed tomography scan was carried out in all patients. One patient also underwent a postoperative computed tomography scan. Grip strength, range of motion, and DASH score were evaluated at follow-up. There were no cases of hardware failure. Specifically, no loss of position or alignment of fixed-angle locking screws or breakage of the plate were observed. Radiographic union was present at an average of 6 weeks (range, 5 to 8 wk). The overall preliminary experience with this new plate is favorable. The new plate is easy to apply and provides the surgeon dual options of fixed-angle or variable-angle screws. It was rigid enough to maintain the reduction also in AO type C articular fractures. PMID:23423235

Tarallo, Luigi; Mugnai, Raffaele; Adani, Roberto; Catani, Fabio

2013-03-01

266

Effect of DDGS, Moisture Content, and Screw Speed on the Physical Properties of Extrudates in Single Screw Extrusion  

Technology Transfer Automated Retrieval System (TEKTRAN)

Three isocaloric (3.5 kcal/g) ingredient blends containing 20, 30, and 40% (wb) DDGS along with soy flour, corn flour, fish meal, mineral and vitamin mix, with the net protein adjusted to 28% (wb) for all blends, were extruded in a single screw laboratory-scale extruder at screw speeds of 100, 130, ...

267

Screw Withdrawal Resistance of Types A and AB Sheet Metal Screws in Particleboard and Medium-Density Hardboard.  

National Technical Information Service (NTIS)

The common type A sheet metal screw has been replaced by type AB. To compare the face and edge withdrawal resistance of types A and AB screws, the Forest Products Laboratory evaluated their performance in eight particleboards and three medium-density hard...

M. J. Superfesky

1974-01-01

268

Estimating Driver Risk Using Alcohol Biomarkers, Interlock BAC Tests and Psychometric Assessments: Initial Descriptives  

PubMed Central

Aim To identify alcohol biomarker and psychometric measures that relate to drivers’ blood alcohol concentration (BAC) patterns from ignition interlock devices (IIDs). Design, Setting, Participants, Measurements In Alberta, Canada, 534 drivers, convicted of driving under the influence of alcohol (DUI), installed IIDs and agreed to participate in a research study. IID BAC tests are an established proxy for predicting future DUI convictions. Three risk groups were defined by rates of failed BAC tests. Program entry and followup blood samples (n=302, 171) were used to measure phosphatidyl ethanol (PETH), carbohydrate deficient transferrin (%CDT), gamma glutamyltransferase (GGT) and other biomarkers. Program entry urine (n=130) was analyzed for ethyl glucuronide (ETG) and ethyl sulfate (ETS). Entry hair samples were tested for fatty acid ethyl esters (FAEE) (n=92) and ETG (n=146). Psychometric measures included the DSM-4 Diagnostic Interview Schedule Alcohol Module, Alcohol Use Disorders Identification Test (AUDIT), the Timeline Followback (TLFB), the Drinker Inventory of Consequences (DRINC), and the Temptation and Restraint Inventory (TRI). Findings Except for FAEE, all alcohol biomarkers were significantly related to the interlock BAC test profiles; higher marker levels predicted higher rates of interlock BAC test failures. PETH, the strongest with an overall ANOVA F ratio of 35.5, had significant correlations with all nine of the other alcohol biomarkers and with 16 of 19 psychometric variables. Urine ETG and ETS were strongly correlated with the IID BAC tests. Conclusions The findings suggest several alcohol biomarkers and assessments could play an important role in the prediction and control of driver alcohol risk when relicensing.

Marques, Paul; Tippetts, Scott; Allen, John; Javors, Martin; Alling, Christer; Yegles, Michel; Pragst, Fritz; Wurst, Friedrich

2009-01-01

269

Coalescence of 3-phenyl-propynenitrile on Cu(111) into interlocking pinwheel chains.  

PubMed

3-phenyl-propynenitrile (PPN) adsorbs on Cu(111) in a hexagonal network of molecular trimers formed through intermolecular interaction of the cyano group of one molecule with the aromatic ring of its neighbor. Heptamers of trimers coalesce into interlocking pinwheel-shaped structures that, by percolating across islands of the original trimer coverage, create the appearance of gear chains. Density functional theory aids in identifying substrate stress associated with the chemisorption of PPN's acetylene group as the cause of this transition. PMID:21992333

Luo, Miaomiao; Lu, Wenhao; Kim, Daeho; Chu, Eric; Wyrick, Jon; Holzke, Connor; Salib, Daniel; Cohen, Kamelia D; Cheng, Zhihai; Sun, Dezheng; Zhu, Yeming; Einstein, T L; Bartels, Ludwig

2011-10-01

270

Detection of trace cobalt ions in in vivo plant cells using a voltammetric interlocking system.  

PubMed

This experiment was conducted to establish a system for detecting trace cobalt ions in water and plant tissues using a voltammetric in vivo sensor. Cyclic and stripping voltammetry was devised from hand-made, macro-type implantable three-electrode systems. The results reached micro and nano working ranges at 100 sec accumulation time. The statistical detection limit (S/N) was attained at 6.0 ng L(-1). For the in vivo application, direct assay of cobalt ions was carried out in Eichhornia crassipes (EC) deep tissue in real time with a preconcentration time of 100 s. Interfaced techniques can be interlocked with other control systems. PMID:23508160

Ly, Suw Young; Shin, Myoung Ho; Lee, Chang Hyun; Lee, Jin Hui; Kim, Mi Sook; Ji, Sang Woo; Park, Dong Won

2013-01-01

271

Case Reports: Ipsilateral Shoulder and Elbow Arthroplasty Using Custom Interlocking Prostheses  

PubMed Central

Ipsilateral shoulder and elbow arthritis is not an uncommon problem seen in patients of upper extremity surgeons. If arthroplasty is required in both joints, there is a significant risk of periprosthetic fracture resulting from the stress riser occurring between the implants. We report the placement of custom interlocking shoulder and elbow prostheses in a patient with rheumatoid arthritis. The elbow prosthesis with an uncemented humeral component was placed followed 18 months later by a custom-designed shoulder prosthesis. An internal strut between the two prostheses was created. Seven years postoperatively, the patient was asymptomatic with no radiographic signs of impending failure.

Baslaim, Abdullah M.; Regan, William D.

2008-01-01

272

Successful Transcatheter Embolization of Penetrating Aortic Ulcer Using Interlocking Detachable Coils  

SciTech Connect

A 54-year-old man with persistent chest pain was hospitalized for hypertension and DeBakey type IIIb aortic dissection. The false lumen of the dissection was almost completely thrombosed; however, a penetrating atherosclerotic ulcer (PAU) was observed 5 weeks later. At that time, we successfully embolized the PAU with a microcatheter and interlocking detachable coils (IDCs). The patient is well with no episodes of relapse in 20 months of follow-up. This case suggests the utility of the microcatheter and IDC system as an alternative to surgery.

Hama, Yukihiro; Kaji, Tatsumi; Iwasaki, Yoshie [Department of Radiology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042 (Japan); Hinokiyama, Kazuhiro; Shimizu, Masafumi [Department of Surgery II, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042 (Japan); Kusano, Shoichi [Department of Radiology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042 (Japan)

2000-09-15

273

Two levels above and one level below pedicle screw fixation for the treatment of unstable thoracolumbar fracture with partial or intact neurology  

PubMed Central

Background Treatment of unstable thoracolumbar fractures is controversial regarding short or long segment pedicle screw fixation. Although long level fixation is better, it can decrease one motion segment distally, thus increasing load to lower discs. Methods We retrospectively analyzed 31 unstable thoracolumbar fractures with partial or intact neurology. All patients were operated with posterior approach using pedicle screws fixed two levels above and one level below the fracture vertebra. No laminectomy, discectomy or decompression procedure was done. Posterior fusion was achieved in all. Post operative and at final follow-up radiological evaluation was done by measuring the correction and maintenance of kyphotic angle at thoracolumbar junction. Complications were also reported including implant failure. Results Average follow-up was 34 months. All patients had full recovery at final follow-up. Average kyphosis was improved from 26.7° to 4.1° postoperatively and to 6.3° at final follow-up. And mean pain scale was improved from 7.5 to 3.9 postoperatively and to 1.6 at final follow-up, All patients resumed their activity within six months. Only 4 (12%) complications were noted including only one hardware failure. Conclusion Two levels above and one level below pedicle screw fixation in unstable thoracolumbar burst fracture is useful to prevent progressive kyphosis and preserves one motion segment distally.

Modi, Hitesh N; Chung, Kook Jin; Seo, Il Woo; Yoon, Hoi Soo; Hwang, Ji Hyo; Kim, Hong Kyun; Noh, Kyu Cheol; Yoo, Jung Han

2009-01-01

274

Direct Arthroscopic Distal Clavicle Resection  

PubMed Central

Degenerative change involving the acromioclavicular (AC) is frequently seen as part of a normal aging process. Occasionally, this results in a painful clinical condition. Although AC joint symptoms commonly occur in conjunction with other shoulder pathology, they may occur in isolation. Treatment of isolated AC joint osteoarthritis is initially non-surgical. When such treatment fails to provide lasting relief, surgical treatment is warranted. Direct (superior) arthroscopic resection of the distal (lateral) end of the clavicle is a successful method of treating the condition, as well as other isolated conditions of the AC joint. The following article reviews appropriate patient evaluation, surgical indications and technique.

Lervick, Gregory N

2005-01-01

275

Expandable intramedullary nails for fixation of tibial shaft fractures.  

PubMed

Interlocking intramedullary nailing is currently the preferred treatment for most tibial fractures requiring operative treatment, with good results and a relatively low complication rate as reported in large clinical series. However, vascular and neurological complications caused by interlocking screws have been reported. In addition, insertion of distal interlocking screws can be technically demanding and may entail substantial exposure. We present the results with an expandable self-locking nail in the management of 52 AO type A and B tibial shaft fractures. The mean time to union was 15.8 weeks and the rate of union was 98%. The average surgical time was 60 minutes. Complications were those usually seen in diaphysis nailing and no complication was noted during nail expansion. Interlocking screws are not necessary, which reduces the risk of iatrogenic lesions. The expandable nail allows effective management of AO type A and B diaphyseal fractures of the tibia, a lower radiation exposure and shorter operative time. PMID:23409575

Ghafil, Dior; Ackerman, Pieter; Baillon, Renaud; Verdonk, Rene; Delince, Philippe

2012-12-01

276

SCREW COMPRESSOR CHARACTERISTICS FOR HELIUM REFRIGERATION SYSTEMS  

SciTech Connect

The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression.At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system. Therefore it is important to understand the isothermal and volumetric efficiencies of these machines to help properly design these compression systems to match the refrigeration process. This presentation summarizes separate tests that have been conducted on Sullair compressors at the Superconducting Super-Collider Laboratory (SSCL) in 1993, Howden compressors at Jefferson Lab (JLab) in 2006 and Howden compressors at the Spallation Neutron Source (SNS) in 2006. This work is part of an ongoing study at JLab to understand the theoretical basis for these efficiencies and their loss

Ganni, Venkatarao; Knudsen, Peter; Creel, Jonathan; Arenius, Dana; Casagrande, Fabio; Howell, Matt

2008-03-01

277

Screw Compressor Characteristics for Helium Refrigeration Systems  

NASA Astrophysics Data System (ADS)

The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression. At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system. Therefore it is important to understand the isothermal and volumetric efficiencies of these machines to help properly design these compression systems to match the refrigeration process. This presentation summarizes separate tests that have been conducted on Sullair compressors at the Superconducting Super-Collider Laboratory (SSCL) in 1993, Howden compressors at Jefferson Lab (JLab) in 2006 and Howden compressors at the Spallation Neutron Source (SNS) in 2006. This work is part of an ongoing study at JLab to understand the theoretical basis for these efficiencies and their loss mechanisms, as well as to implement practical solutions.

Ganni, V.; Knudsen, P.; Creel, J.; Arenius, D.; Casagrande, F.; Howell, M.

2008-03-01

278

Salvaging the Pullout Strength of Stripped Screws in Osteoporotic Bone  

PubMed Central

Our goal was to determine whether the pullout strength of stripped screw holes in osteoporotic bone could be increased with readily available materials from the operating room. We inserted 3.5-mm stainless steel nonlocking self-tapping cortical screws bicortically into 5 osteoporotic humeri. Each screw was first stripped by rotating it 1 full turn past maximum torque. In the control group, the screw was pulled out using an MTS machine (858; MTS Inc, Eden Prairie, Minnesota). In the treatment groups, the screw was removed, the hole was augmented with 1 of the 3 materials (stainless steel wire, polysorb suture, or polyethylene terephthalate glycol plastic sheet), and the screws were replaced and then pulled out. The effect of material on pullout strength was checked for significance (P < .05) using a general linearized latent and mixed model (Stata10; StataCorp, College Station, Texas). The mean (95% confidence interval) pullout strength for the unaugmented hole was 138 N (range 88-189), whereas the holes augmented with plastic, suture, or wire had mean pullout strengths of 255 N (range 177-333), 228 N (range 149-308), and 396 N (range 244-548), respectively. Although wire augmentation resulted in pullout strength that was significantly greater than that of the unaugmented screw, it was still below that of the intact construct.

Pechon, Pierre H. M.; Mears, Simon C.; Langdale, Evan R.; Belkoff, Stephen M.

2013-01-01

279

Comparison of Expansive Pedicle Screw and Polymethylmethacrylate-Augmented Pedicle Screw in Osteoporotic Sheep Lumbar Vertebrae: Biomechanical and Interfacial Evaluations  

PubMed Central

Background It was reported that expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) could be used to increase screw stability in osteoporosis. However, there are no studies comparing the two kinds of screws in vivo. Thus, we aimed to compare biomechanical and interfacial performances of EPS and PMMA-PS in osteoporotic sheep spine. Methodology/Principal Findings After successful induction of osteoporotic sheep, lumbar vertebrae in each sheep were randomly divided into three groups. The conventional pedicle screw (CPS) was inserted directly into vertebrae in CPS group; PMMA was injected prior to insertion of CPS in PMMA-PS group; and the EPS was inserted in EPS group. Sheep were killed and biomechanical tests, micro-CT analysis and histological observation were performed at both 6 and 12 weeks post-operation. At 6-week and 12-week, screw stabilities in EPS and PMMA-PS groups were significantly higher than that in CPS group, but there were no significant differences between EPS and PMMA-PS groups at two study periods. The screw stability in EPS group at 12-week was significantly higher than that at 6-week. The bone trabeculae around the expanding anterior part of EPS were more and denser than that in CPS group at 6-week and 12-week. PMMA was found without any degradation and absorption forming non-biological “screw-PMMA-bone” interface in PMMA-PS group, however, more and more bone trabeculae surrounded anterior part of EPS improving local bone quality and formed biological “screw-bone” interface. Conclusions/Significance EPS can markedly enhance screw stability with a similar effect to the traditional method of screw augmentation with PMMA in initial surgery in osteoporosis. EPS can form better biological interface between screw and bone than PMMA-PS. In addition, EPS have no risk of thermal injury, leakage and compression caused by PMMA. We propose EPS has a great application potential in augmentation of screw stability in osteoporosis in clinic.

Zhang, Bo; Xie, Qing-yun; Wang, Cai-ru; Liu, Jin-biao; Liao, Dong-fa; Jiang, Kai; Lei, Wei; Pan, Xian-ming

2013-01-01

280

Distal Myopathy with Rimmed Vacuoles  

PubMed Central

Distal myopathy with rimmed vacuoles (DMRV), is an autosomal recessive disorder with early adult onset, displays distal dominant muscular involvement and is characterized by the presence of numerous rimmed vacuoles in the affected muscle fibers. The pathophysiology of DMRV has not been clarified yet, although the responsible gene was identified as that encoding UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase involved in the biosynthesis of sialic acids. To identify defective carbohydrate moieties of muscular glycoproteins from DMRV patients, frozen skeletal muscle sections from seven patients with DMRV, as well as normal and pathological controls, were treated with or without sialidase or N-glycosidase F followed by lectin staining and lectin blotting analysis. The sialic acid contents of the O-glycans in the skeletal muscle specimens from the DMRV patients were also measured. We found that Arachis hypogaea agglutinin (PNA) lectin reacted strongly with sarcolemmal glycoproteins in the DMRV patients but not with those in control subjects. ?-Dystroglycan from the DMRV patients strongly associated with PNA lectin, although that from controls did not. The sialic acid level of the O-glycans in the DMRV muscular glycoproteins with molecular weights of 30 to 200 kd was reduced to 60 to 80% of the control level. The results show that impaired sialyl O-glycan formation in muscular glycoproteins, including ?-dystroglycan, occurs in DMRV.

Tajima, Youichi; Uyama, Eiichiro; Go, Shinji; Sato, Chihiro; Tao, Nodoka; Kotani, Masaharu; Hino, Hirotake; Suzuki, Akemi; Sanai¶, Yutaka; Kitajima, Ken; Sakuraba, Hitoshi

2005-01-01

281

Interlocked optimization and fast gradient algorithm for a seismic inverse problem  

SciTech Connect

Highlights: {yields} A 2D extension of the 1D nonlinear inversion of well-seismic data is given. {yields} Appropriate regularization yields a well-determined large scale inverse problem. {yields} An interlocked optimization loop acts as an efficient preconditioner. {yields} The adjoint state method is used to compute the misfit function gradient. {yields} Domain decomposition method yields an efficient parallel implementation. - Abstract: We give a nonlinear inverse method for seismic data recorded in a well from sources at several offsets from the borehole in a 2D acoustic framework. Given the velocity field, approximate values of the impedance are recovered. This is a 2D extension of the 1D inversion of vertical seismic profiles . The inverse problem generates a large scale undetermined ill-conditioned problem. Appropriate regularization terms render the problem well-determined. An interlocked optimization algorithm yields an efficient preconditioning. A gradient algorithm based on the adjoint state method and domain decomposition gives a fast parallel numerical method. For a realistic test case, convergence is attained in an acceptable time with 128 processors.

Metivier, Ludovic, E-mail: ludovic.metivier@gmail.com [LAGA, Universite Paris XIII, 99 Avenue Jean-Baptiste Clement, 93000 Epinay-Villetaneuse (France)

2011-08-10

282

The formation mechanisms of interlocked microstructures in low-carbon high-strength steel weld metals  

SciTech Connect

Microstructural features and the formation mechanisms of interlocked microstructures of acicular ferrite in a low-carbon high-strength steel weld metal were investigated by means of computer-aided three-dimensional reconstruction technique and electron backscattered diffraction analysis. Multiple nucleation on inclusions, sympathetic nucleation or repeated nucleation, hard impingement, mutual intersection, and fixed orientation relationships of acicular ferrite grains were observed. They were all responsible for the formation of interlocked microstructures in the weld metal. During the process of isothermal transformation, the pre-formed acicular ferrite laths or plates partitioned austenite grains into many small and separate regions, and the growth of later formed acicular ferrite grains was confined in these small regions. Thus, the crystallographic grain size became smaller with the increasing holding time. Highlights: Black-Right-Pointing-Pointer Acicular ferrite is formed by multiple nucleation and sympathetic nucleation. Black-Right-Pointing-Pointer Hard impingement and intersection of ferrite grains occur at later stages. Black-Right-Pointing-Pointer The pre-formed ferrite laths partition austenite grains into smaller regions. Black-Right-Pointing-Pointer The growth of later formed ferrite grains is confined in the smaller regions.

Wan, X.L.; Wang, H.H.; Cheng, L.; Wu, K.M., E-mail: wukaiming2000@yahoo.com

2012-05-15

283

Shear strength and fabric properties in granular media with interlocked particles  

NASA Astrophysics Data System (ADS)

We study granular materials characterized by the possibility of interlocking between the particles. The Interlocking is modeled as the combined effect of sliding and rolling resistance at the contacts, and it involves two contact parameters: a coefficient of sliding friction and a coefficient of rolling friction. This model is introduced within the framework of the Contact Dynamics method, and it is applied to investigate the effect of the two contact friction coefficients on the behavior of large polydisperse granular samples sheared in a numerical simple shear device. The macroscopic behavior of the samples is investigated in terms of the steady-state shear strength and the fabric properties of the packing. We find that two regimes can be distinguished in which the steady-state shear strength is controlled by either sliding friction or rolling friction. Moreover, our results show that the introduction of rolling friction strongly affects the microstructure of the packing. In particular, with high values of the sliding and rolling friction coefficients, the force-carrying backbone takes an increasingly columnar aspect involving a weak proportion of particles and affecting the mechanical role played by the weak network.

Estrada, Nicolas; Taboada, Alfredo; Radjai, Farhang

2009-06-01

284

Improved Interlock System at the Nuclear Structure Lab at Univ. of Notre Dame  

NASA Astrophysics Data System (ADS)

The current interlock system at the Nuclear Structure Lab (NSL) at the University of Notre Dame requires multiple procedures to be performed in order to start up one of the three accelerators. New features and equipment will be added to the current interlock system to allow access into the experimental rooms safely. This change is necessary because the planned addition of experimental equipment will allow beams from two accelerators to enter the same target hall. In order to minimize the impact of one experiment on another, access will be determined by active monitoring of the radiation levels in the rooms instead of the possibility of accelerated beam being present. New equipment planned to be used in the laboratory are personal dosimeter badges, with a monitor reader for a pass-by data exchange and monitor screens to display live radiation levels and access levels in all of the experimental rooms. This poster will present this procedure and explain how personnel can access the NSL rooms safely while the ion beams are on.

Lor, Xao; Lesher, Shelly; Stech, Ed

2010-11-01

285

Manufacture of composite screw rotors for air compressors by RTM process  

Microsoft Academic Search

Screw rotors, the key parts of screw compressors, are widely used in compressing air and refrigerant due to their high productivity, compact size, low noise and easy maintenance. In general, a screw compressor unit is composed of female and male rotors of complex geometric shape. The manufacturing cost and time of the screw rotors are high because the complicated helical

Jung Do Suh; Dai Gil Lee

2001-01-01

286

2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries - a case series  

Microsoft Academic Search

BACKGROUND: Screw fixation of pelvic ring fractures is a common, but demanding procedure and navigation techniques were introduced to increase the precision of screw placement. The purpose of this case series was the evaluation of screw misplacement rate and functional outcome of percutaneous screw fixation of pelvic ring disruptions using a 2D navigation system. METHODS: Between August 2004 and December

Florian Gras; Ivan Marintschev; Arne Wilharm; Kajetan Klos; Thomas Mückley; Gunther O Hofmann

2010-01-01

287

Intersection of screw dislocations in fcc crystals during torsional deformation  

NASA Astrophysics Data System (ADS)

Dislocation reactions, including dislocation intersections during various processes in crystals, play an important and often crucial role. This is most pronounced during plastic deformation of crystalline solids, which attracts particular interest from researchers. Intersection of screw dislocations in fcc crystals during their deformation by uniaxial tension and compression was studied by A. Cottrell [1]. It was shown that the intersection of similar screw dislocations moving toward each other results in the formation of interstitial thresholds on them; in the case of intersection of opposite screw dislocations, vacancy thresholds are formed on them.

Myshlyaev, M. M.

2012-03-01

288

Optically driven Archimedes micro-screws for micropump applications: multiple blade design  

NASA Astrophysics Data System (ADS)

We study the rotation of photo-driven Archimedes screw with multiple blades. The micron-sized Archimedes screws are readily made by the two-photon polymerization technique. Free-floating screws that are trapped by optical tweezers align in the laser irradiation direction, and rotate spontaneously. In this study we demonstrate that the rotation speeds of two-blade-screws is twice the rotation speed of one-blade-screw. However, more complex 3-blade-screws rotate slower than 2-blade-screws due to their limited geometry resolution at this micron scale.

Baldeck, Patrice L.; Lin, Chih-Lang; Lin, Yu-Sheng; Lin, Chin-Te; Chung, Tien-Tung; Bouriau, Michel; Vitrant, Guy

2011-09-01

289

Modeling the Length of Distal Radioulnar Ligaments  

Microsoft Academic Search

The distal radioulnar ligaments are essential contributors to wrist joint stability. We present a CT-based model for ligament displacement, in which ligaments are approximated by shortest paths in a 3D space with bone obstacles. This rst model allows for the study of distal ligaments biomechanics in vivo and non-invasively. We show that our simplied model gives surprising insight into distal

Liz Marai

290

Mini-Open or Percutaneous Bilateral Lumbar Transfacet Pedicle Screw Fixation: A Technical Note.  

PubMed

STUDY DESIGN:: Case report. OBJECTIVE:: To describe the technique used to place bilateral lumbar transfacet pedicle screws. SUMMARY OF BACKGROUND DATA:: Transfacet pedicle screw fixation is a growing alternative and biomechanically comparable with traditional pedicle screw fixation. There is no clear description of technique steps for placing transfacet pedicle screws available in the literature, despite recognizing that screw placement is not intuitive even with fluoroscopy, and is dissimilar to placing traditional pedicle screws or translaminar facet screws. METHODS:: We present two illustrative cases where bilateral transfacet pedicle screws were placed for posterior instrumentation following a step by step technique which can be used in a mini-open or percutaenous procedure. RESULTS:: Postoperatively, both patients had adequately placed transfacet pedicle screws bilaterally on x-ray imaging with one patient demonstrating fusion and intact fixation at 11 months follow up. CONCLUSIONS:: Transfacet pedicle screws were successfully placed in two patients in a stepwise technique described to achieve lumbar fusion. PMID:23222099

Chin, Kingsley Richard; Seale, Jason; Cumming, Vanessa

2012-12-01

291

The effect of screw insertion angle and thread type on the pullout strength of bone screws in normal and osteoporotic cancellous bone models.  

PubMed

Screw fixation can be extremely difficult to achieve in osteoporotic (OP) bone because of its low strength. This study determined how pullout strength is affected by placing different bone screws at varying angles in normal and OP bone models. Pullout tests of screws placed axially, and at angles to the pullout axis (ranging from 10° to 40°), were performed in 0.09 g cm(-3), 0.16 g cm(-3) and 0.32 g cm(-3) polyurethane (PU) foam. Two different titanium alloy bone screws were used to test for any effect of thread type (i.e. cancellous or cortical) on the screw pullout strength. The cancellous screw required a significantly higher pullout force than the cortical screw (p<0.05). For both screws, pullout strength significantly increased with increasing PU foam density (p<0.05). For screws placed axially, and sometimes at 10°, the observed mechanism of failure was stripping of the internal screw threads generated within the PU foam by screw insertion. For screws inserted at 10°, 20°, 30° and 40°, the resistance to pullout force was observed to be by compression of the PU foam material above the angled screw; clinically, this suggests that compressed OP bone is stronger than unloaded OP bone. PMID:20558097

Patel, Purvi S D; Shepherd, Duncan E T; Hukins, David W L

2010-06-16

292

Mandibular first molar with three distal canals  

PubMed Central

With the increasing number of reports of aberrant root canal morphology, the clinician needs to be aware of the variable anatomy. Various case reports have been published with the finding of middle mesial canal in mandibular first molar, however finding of middle distal canal in distal root of mandibular first molar is rare. This case report describes root canal treatment of two rooted mandibular first molar with five root canals (three in distal and two in mesial root), and Sert and Bayirli Type XVIII canal configuration in distal root.

Jain, Shweta

2011-01-01

293

Haemodynamics after distal splenorenal shunt.  

PubMed

Haemodynamic studies were made both preoperatively and 7--62 months after the operation in 17 cirrhotic patients subjected to distal splenorenal shunt. Patent shunt was demonstrated in all patients. Preoperatively all patients had hepatopetal portal flow. Postoperatively portography through percutaneous transhepatic portal vein cannulation demonstrated hepatopetal flow in nine patients and reversed flow in eight patients. Portal pressure was significantly decreased in both groups after the shunt (p less than 0.01). However, no differences in pre- and post-operative portal pressure were observed in the two patient groups. In patients with hepatopetal flow, minimal new collaterals without clear connection to gastroesophageal region could be demonstrated. Collateral formation in patients with reversed flow was more abandoned but, even in these cases, no connection to gastroesophageal region could be demonstrated. The results indicate that a continuous increase in liver resistance due to the progression of the liver disease is the main cause of changes in portal circulation. PMID:6538372

Kallio, H; Suoranta, H; Lempinen, M

1984-01-01

294

Distal limb and paw injuries.  

PubMed

Distal limb reconstruction is complicated by the paucity of local tissues and the frequent association of orthopedic injury with cutaneous loss. Second-intention healing or skin stretching techniques are used for wounds involving less than a 30% circumference of the limb. Skin grafts are recommended for reconstruction of larger superficial wounds after establishing a bed of granulation tissue or for immediate reconstruction of clean wounds overlying healthy muscle. Wounds complicated by orthopedic injury benefit from early reconstruction using vascularized tis-sue. Weight-bearing surface reconstruction and management of partial amputation injuries are functionally difficult because of the environmental stress placed on the paw pads. Paw pad grafts, paw pad transposition techniques, centralization of digits, and microvascular free tissue trans-fer of paw pads can be considered for weight-bearing surface reconstruction. Definitive guidelines describing when each of these techniques should be used have not been established. PMID:16787789

Fowler, David

2006-07-01

295

21 CFR 888.3070 - Pedicle screw spinal system.  

Code of Federal Regulations, 2013 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3070 Pedicle screw spinal system. ...22Cr-13Ni-5Mn stainless steel, Ti-6Al-4V, and unalloyed titanium, that allow the surgeon to build an implant...

2013-04-01

296

Application of Screw Calculus to the Evaluation of Manipulator Workspace.  

National Technical Information Service (NTIS)

In this paper, an analytical technique is presented that is based on screw calculus and dual-number matrices to derive the kinematic equations and the workspace formulations of manipulators. A computational procedure for the quantitative evaluation of wor...

L. M. Hsia T. W. Lee

1985-01-01

297

Lateral Mass Screw Fixation in the Cervical Spine  

Center for Biologics Evaluation and Research (CBER)

Text Version... posterior cervical spine may paradoxically result in ... these devices by undertrained spinal surgeons ... Nerve root injury attributed to screw placement ... More results from www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials

298

Three-dimensional bimetric maxillary distalization arches compared with a modifi ed Begg intraoral distalization system  

Microsoft Academic Search

SUMMARY The purpose of this study was to compare the dentofacial effects of two intraoral molar distalization techniques (three-dimensional bimetric maxillary distalization arches (3D-BMDA) and a modifi ed Begg intraoral distalization system (MBIDS)) in subjects requiring maxillary molar distalization. Twenty-one patients (12 females and 9 males, mean age pre-treatment: 14.7 ± 1.50 years) were treated with the 3D-BMDA and 17

Ayse Tuba Altug-Atac; Dilek Erdem; Züleyha Mirzen Arat

299

Screw thread parameter measurement system based on image processing method  

NASA Astrophysics Data System (ADS)

In the industrial production, as an important transmission part, the screw thread is applied extensively in many automation equipments. The traditional measurement methods of screw thread parameter, including integrated test methods of multiparameters and the single parameter measurement method, belong to contact measurement method. In practical the contact measurement exists some disadvantages, such as relatively high time cost, introducing easily human error and causing thread damage. In this paper, as a new kind of real-time and non-contact measurement method, a screw thread parameter measurement system based on image processing method is developed to accurately measure the outside diameter, inside diameter, pitch diameter, pitch, thread height and other parameters of screw thread. In the system the industrial camera is employed to acquire the image of screw thread, some image processing methods are used to obtain the image profile of screw thread and a mathematics model is established to compute the parameters. The C++Builder 6.0 is employed as the software development platform to realize the image process and computation of screw thread parameters. For verifying the feasibility of the measurement system, some experiments were carried out and the measurement errors were analyzed. The experiment results show the image measurement system satisfies the measurement requirements and suitable for real-time detection of screw thread parameters mentioned above. Comparing with the traditional methods the system based on image processing method has some advantages, such as, non-contact, easy operation, high measuring accuracy, no work piece damage, fast error analysis and so on. In the industrial production, this measurement system can provide an important reference value for development of similar parameter measurement system.

Rao, Zhimin; Huang, Kanggao; Mao, Jiandong; Zhang, Yaya; Zhang, Fan

2013-08-01

300

ACROMIOCLAVICULAR DISLOCATIONS--Open Reduction with Screw Fixation  

PubMed Central

Athletes with complete separation of the acromioclavicular joint were uniformly restored to full athletic competence by an operation consisting of direct repair of the involved ligamentous structures with temporary fixation by a metallic lag screw approximating the clavicle to the coracoid. The metallic fixation was left in place an average of eight weeks and the screw was then removed under local anesthesia. A number of professional and collegiate football players returned to the rigors of football with no discomfort or disability.

Meier, A. W.; Grannis, W. R.; Tanner, J. B.

1957-01-01

301

Translaminar screw fixation of the lumbar facet joints  

Microsoft Academic Search

Surgical Principle\\u000a \\u000a Posterior fusion of one or two levels of the lumbar spine with arthrodesis of the facet joints using screws. The technique\\u000a has been developed by one of us (Magerl [10–13]). It constitutes an improvement of a technique of transarticular screw fixation\\u000a first described by King in 1944 [7, 8] and modified by Boucher [3] (Figures 1a to 1c).

Bernard Jeanneret; Frank Kleinstiick; Friedrich Magerl

1995-01-01

302

Distally based dorsalis pedis island flap for a distal lateral electric burn of the big toe  

Microsoft Academic Search

Reconstruction of the small defects in the distal portion of the foot has always represented a difficult problem. A case of a young man with a deep electric burn of the distal lateral side of the big toe successfully treated with a distally based dorsalis pedis island flap based on the first dorsal metatarsal artery (FDMA) is presented. The donor

M. Governa; D. Barisoni

1996-01-01

303

Scoliosis correction with pedicle screws in Duchenne muscular dystrophy  

PubMed Central

This report describes the spinal fixation with pedicle-screw-alone constructs for the posterior correction of scoliosis in patients suffering from Duchene muscular dystrophy (DMD). Twenty consecutive patients were prospectively followed up for an average of 5.2 years (min 2 years). All patients were instrumented from T3/T4 to the pelvis. Pelvic fixation was done with iliac screws similar to Galveston technique. The combination of L5 pedicle screws and iliac screws provided a stable caudal foundation. An average of 16 pedicle screws was used per patient. The mean total blood loss was 3.7 l, stay at the intensive care unit was 77 h and hospital stay was 19 days. Rigid stabilisation allowed immediate mobilisation of the patient in the wheel chair. Cobb angle improved 77% from 44° to 10°, pelvic tilt improved 65% from 14° to 3°. Lumbar lordosis improved significantly from 20° to 49°, thoracic kyphosis remained unchanged. No problems related to iliac fixation, no pseudarthrosis or implant failures were observed. The average percentage of predicted forced vital capacity (%FVC) of the patients was 55% (22–94%) preoperatively and decreased to 44% at the last follow-up. There were no pulmonary complications. One patient with a known cardiomyopathy died intraoperatively due to a sudden cardiac arrest. The rigid primary stability with pedicle screws allowed early mobilisation of the patients, which helped to avoid pulmonary complications.

Hahn, Frederik; Hauser, Dominik; Espinosa, Norman; Blumenthal, Stefan

2007-01-01

304

Backflow in twin-screw-type multiphase pump  

SciTech Connect

The performance of a twin-screw-type multiphase pump was investigated from the viewpoints of backflow in a gap along the twin-screw shafts and of scaleup parameters. Although both the backflow and the scaleup parameters have been recognized as important factors in developing multiphase pumps, they have not yet been clarified. The twin-screw pump was equipped with pressure sensors, set in the multiphase-test facility, and experimented with under various conditions to clarify the relationship between backflow rates and factors such as differential pressure, gas-void fractions (GVF`s), and the rotation speed of the shaft. A physical model was proposed with the empirical relationship of pressure distribution along the screw, and was successfully associated with scaleup parameters, such as the geometrical data of the twin-screw pump. Then it was used successfully to simulate the backflow in twin-screw pumps on relatively broad experimental conditions, judging from the comparison between the model and the experimental data.

Egashira, Kazuyuki; Shoda, Shinji; Tochikawa, Tetsuro [Japan National Oil Corp., Chiba (Japan); Furukawa, Akinori [Kyushu Univ. (Japan)

1998-02-01

305

Topological and Conformational Effects on Electron Transfer Dynamics in Porphyrin-[60]Fullerene Interlocked Systems  

PubMed Central

The effect of molecular topology, and conformation on the dynamics of photoinduced electron transfer (ET) processes has been studied in interlocked electron donor-acceptor systems, specifically rotaxanes with zinc(II)-tetraphenylporphyrin (ZnP) electron donor and [60]fullerene (C60) as the electron acceptor. Formation or cleavage of coordinative bonds was used to induce major topological and conformational changes in the interlocked architecture. In the first approach, the tweezers-like structure created by the two ZnP stopper groups on the thread was used as a recognition site for complexation of 1,4-diazabicyclo[2.2.2]octane (DABCO), which creates a bridge between the two ZnP moieties on the rotaxane, generating a catenane structure. The photoinduced processes in the DABCO-complexed (ZnP)2-[2]catenate-C60 system were compared with those of the (ZnP)2-rotaxane-C60 precursor and the previously reported ZnP-[2]catenate-C60. Steady-state emission and transient absorption studies showed that a similar multistep ET pathway emerged for rotaxanes and catenanes upon photoexcitation at various wavelengths, ultimately resulting in a long-lived ZnP•+/C60•? charge separated radical pair state. However, the decay kinetics of the latter states clearly reflect the topological differences between the rotaxane, the catenate, and DABCO-complexed-catenate architectures. The lifetime of the long-distance ZnP•+–[Cu(I)phen2]+–C60•? charge separated state is more than four times longer in 3 (1.03 µs) than in 1 (0.24 µs) and approaches that in catenate 2 (1.1 µs). The results clearly showed that adoption of a catenane from a rotaxane topology inhibits the charge recombination process. In a second approach, the Cu(I) ion used as template to assemble the (ZnP)2–[Cu(I)phen2]+–C60 rotaxane was removed, and structural analysis suggested a major topographical change occurred, such that charge separation between the chromophores was no longer observed upon photoexcitation in nonpolar as well as polar solvents. Only ZnP and C60 triplet excited states were observed upon laser excitation. These results highlighted the critical importance of the central Cu(I) ion for long range ET processes in these large interlocked electron donor-acceptor systems.

de Miguel, Gustavo; Wolfrum, Silke

2012-01-01

306

Effects of Feed Rate and Screw Speed on Operating Characteristics and Extrudate Properties During Single-Screw Extrusion Cooking of Rice Flour  

Microsoft Academic Search

Cereal Chem. 76(2):236-242 Rice flour (37% moisture content) was used to examine the effects of feed rate and screw speed on the specific energy input during single-screw extrusion cooking. Torque, raised by decreasing screw speed or increasing feed rate, was found to be a power law function of the ratio of feed rate to screw speed (Fr\\/Ss) with r2 >

An-I Yeh; Yih-Mon Jaw

1999-01-01

307

The dislocation of agriculture and food: a network analysis of interlocking directorates in New Zealand's corporate economy  

Microsoft Academic Search

As a political project, ‘agri-food’ calls for improved communication between New Zealand's land-based industries and the business of food. Such communication may be enhanced by the sharing of company directors, a social practice whose interlocks create information flows across the economy. These flows can overcome market fragmentation and help establish a common sense of purpose. However, a social network analysis

B Wood

2011-01-01

308

Elites, Corporations, and the Wealth of Nations: How Historical Institutional Settings Shape Directorship Interlocks in Italy and Spain  

Microsoft Academic Search

Intercorporate relations represent the structure of a country's economic organization and influence key outcomes such as a country's overall competitiveness. Research on this topic has focused on the nature of these relations in terms of directorship interlocks, the incentives to establish them, and their behavioral and strategic consequences along a number of dimensions. However, less attention has been devoted to

Ruth V. Aguilera

2005-01-01

309

D0 Silicon Upgrade: D0 Central Tracking Solenoid: Specification for Solenoid Energization, controls, Interlocks and Quench Protection  

Microsoft Academic Search

This document has served as the specification for the energization, control, interlocking and quench protection systems for the DZERO superconducting solenoid installation. This does not include the cryogenics system. As the work proceeded, the details of the design were 'fleshed out' such that this document ultimately describes the system 'as built'. See 'Revisions to this document' for a description of

R. Hance; W. Jaskierney; S. Orr

1995-01-01

310

Definition and means of maintaining the process vacuum liquid detection interlock systems portion of the PFP safety envelope  

SciTech Connect

The HC-4, HC-7, HC-227s and the tank 50 High Level Liquid detection interlock systems detect the potential for a liquid up take into the 26 inch Vacuum Headers. All of the detectors are well upstream of the 26 inch Vacuum Liquid Detection system that is designed to prevent a criticality due to liquid uptake. Failure of any of the four glovebox liquid detection systems would not impact the operation of the 26 inch Vacuum Liquid Detection system. The systems are completely separate. The liquid detectors and interlocks were installed after an incident in HC-227s resulted in a significant volume of RMC feed grade plutonium solution to be drawn out of the glovebox and into the vacuum header. The vacuum trap liquid detection interlock system operability is verified by a weekly functional test per maintenance procedure 2222124. Removal of the HC-7 Liquid Detection Interlock system from the WHC-SD-CP-SDD-013 document will not impact this maintenance procedure.

THOMAS, R.J.

1999-09-01

311

An unusual two-fold interpenetrating polyrotaxane motif comprised of two interlocked sets of identical diamond nets  

NASA Astrophysics Data System (ADS)

A novel 3D coordination polymer [Cd2(cca)2(bib)3]?3H2O (1, H2cca = 4-carboxycinnamic acid, bib = 1,4-bis(imidazole)butane) has been synthesized. This compound exhibits an unusual two-fold interpenetrating polyrotaxane-like structure comprised of two interlocked sets of identical diamond nets.

Guo, Hua-dong; Fu, Zi-ao; Guo, Xian-min; Li, Xin-long; Chen, Rui-zhan; Qi, Yan-juan; Zou, Heng-ye

2013-04-01

312

Precise robot-assisted guide positioning for distal locking of intramedullary nails.  

PubMed

This paper presents a novel image-guided robot-based system to assist orthopedic surgeons in performing distal locking of long bone intramedullary nails. The system consists of a bone-mounted miniature robot fitted with a drill guide that provides rigid mechanical guidance for hand-held drilling of the distal screws' pilot holes. The robot is automatically positioned so that the drill guide and nail distal locking axes coincide, using a single fluoroscopic X-ray image. Since the robot is rigidly attached to the intramedullary nail or bone, no leg immobilization or real-time tracking is required. We describe the system and protocol and present a method for accurate and robust drill guide and nail hole localization and registration. The in vitro system accuracy experiments for fronto-parallel viewing show a mean angular error of 1.3 degrees (std = 0.4 degrees ) between the computed drill guide axes and the actual locking holes axes, and a mean 3.0 mm error (std = 1.1 mm) in the entry and exit drill point, which is adequate for successfully locking the nail. PMID:15889550

Yaniv, Ziv; Joskowicz, Leo

2005-05-01

313

Percutaneous plating of distal tibial fractures. Preliminary results in 21 patients.  

PubMed

We describe the surgical technique and report the outcome after closed reduction and percutaneous plating in 21 closed extraarticular distal tibial fractures using titanium LC-DCP. A long plate was pushed subcutaneously through a small incision at the medial malleolus and fixed with screws through stab incisions. Fracture reduction was anatomical or nearly anatomical without angular displacement in 14 cases, and considered acceptable in four cases. Two patients were reoperated because of malreduction. Seventeen fractures healed within 6 months. There were two delayed unions, and two non-unions. There were two deep infections, both in diabetic patients. Follow-up by an independent observer at on average 14 (5-25) months showed various symptoms such as slightly reduced ankle mobility (9/20), reduced walking ability (11/20) or tenderness around the plate (11/20). No patient complained of knee symptoms related to the surgery. Operative treatment of closed distal tibial shaft fractures with a long titanium plate provided good anatomical results and allowed in most patients early weight-bearing. In patients with soft tissues in good condition and no risk factor for infection percutaneous plate osteosynthesis might become an attractive treatment option for fractures in the distal tibia. PMID:15135281

Borg, Tomas; Larsson, Sune; Lindsjö, Ulf

2004-06-01

314

Fixation strength of biocomposite wedge interference screw in ACL reconstruction: effect of screw length and tunnel/screw ratio. A controlled laboratory study  

PubMed Central

Background Primary stability of the graft is essential in anterior cruciate ligament surgery. An optimal method of fixation should be easy to insert and provide great resistance against pull-out forces. A controlled laboratory study was designed to test the primary stability of ACL tendinous grafts in the tibial tunnel. The correlation between resistance to traction forces and the cross-section and length of the screw was studied. Methods The tibial phase of ACL reconstruction was performed in forty porcine tibias using digital flexor tendons of the same animal. An 8 mm tunnel was drilled in each specimen and two looped tendons placed as graft. Specimens were divided in five groups according to the diameter and length of the screw used for fixation. Wedge interference screws were used. Longitudinal traction was applied to the graft with a Servohydraulic Fatigue System. Load and displacement were controlled and analyzed. Results The mean loads to failure for each group were 295,44 N (Group 1; 9 × 23 screw), 564,05 N (Group 2; 9 × 28), 614,95 N (Group 3; 9 × 35), 651,14 N (Group 4; 10 × 28) and 664,99 (Group 5; 10 × 35). No slippage of the graft was observed in groups 3, 4 and 5. There were significant differences in the load to failure among groups (ANOVA/P < 0.001). Conclusions Longer and wider interference screws provide better fixation in tibial ACL graft fixation. Short screws (23 mm) do not achieve optimal fixation and should be implanted only with special requirements.

2010-01-01

315

Acquired distal renal tubular acidosis in man  

Microsoft Academic Search

Summary Distal renal tubular acidosis (dRTA) may complicate renal transplantation, liver cirrhosis, and obstructive uropathy. Indeed, its occurrence may be an early clue to an episode of rejection of the graft or to obstructive uropathy. The mechanism in most patients with dRTA is impaired distal secretion of protons. In some patients, however, back leak of protons from tubular lumen to

O. S. Better

1982-01-01

316

Pullout strength of misplaced pedicle screws in the thoracic and lumbar vertebrae - A cadaveric study  

PubMed Central

Background: The objective of this cadaveric study was to analyze the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of lower thoracic and lumbar pedicle screws. We also investigated the effect of bone mineral density (BMD), diameter of pedicle screws, and the region of spine on the pullout strength of pedicle screws. Materials and Methods: Sixty fresh human cadaveric vertebrae (D10–L2) were harvested. Dual-energy X-ray absorptiometry (DEXA) scan of vertebrae was done for BMD. Titanium pedicle screws of different diameters (5.2 and 6.2 mm) were inserted in the thoracic and lumbar segments after dividing the specimens into three groups: a) standard pedicle screw (no cortical perforation); b) screw with medial cortical perforation; and c) screw with lateral cortical perforation. Finally, pullout load of pedicle screws was recorded using INSTRON Universal Testing Machine. Results: Compared with standard placement, medially misplaced screws had 9.4% greater mean pullout strength and laterally misplaced screws had 47.3% lesser mean pullout strength. The pullout strength of the 6.2 mm pedicle screws was 33% greater than that of the 5.2 mm pedicle screws. The pullout load of pedicle screws in lumbar vertebra was 13.9% greater than that in the thoracic vertebra (P = 0.105), but it was not statistically significant. There was no significant difference between pullout loads of vertebra with different BMD (P = 0.901). Conclusion: The mean pullout strength was less with lateral misplaced pedicle screws while medial misplaced pedicle screw had more pullout strength. The pullout load of 6.2 mm screws was greater than that of 5.2 mm pedicle screws. No significant correlation was found between bone mineral densities and the pullout strength of vertebra. Similarly, the pullout load of screw placed in thoracic and lumbar vertebrae was not significantly different.

Saraf, Shyam K; Singh, Ravindra P; Singh, Vakil; Varma, Ashish

2013-01-01

317

An analytical investigation of high-temperature heat pump system with screw compressor and screw expander for power recovery  

Microsoft Academic Search

An analytical investigation of a high-temperature heat pump system was developed to estimate the thermal cycle and to assess the thermal fluids for their high-temperature delivery (up to 180°C) capacities without decomposition or the use of lubricant mechanisms. Then, a screw-type compressor was applied in the above conditions. Furthermore, a screw expander was also used as a replacement for the

I. Tamura; H. Taniguchi; H. Sasaki; R. Yoshida; I. Sekiguchi; M. Yokogawa

1997-01-01

318

Screw fixation of the syndesmosis: a cadaver model comparing stainless steel and titanium screws and three and four cortical fixation  

Microsoft Academic Search

We assessed syndesmotic set screw strength and fixation capacity during cyclical testing in a cadaver model simulating protected weight bearing. Sixteen fresh frozen legs with artificial syndesmotic injuries and a syndesmotic set screw made of stainless steel or titanium, inserted through three or four cortices, were axially loaded with 800N for 225,000 cycles in a materials testing machine. The 225,000

Annechien Beumer; Martin M. Campo; Ruud Niesing; Judd Day; Gert-Jan Kleinrensink; Bart A. Swierstra

2005-01-01

319

Helical Screw Expander Evaluation Project. Final report  

SciTech Connect

A functional 1-MW geothermal electric power plant that featured a helical screw expander was produced and then tested in Utah in 1978 to 1979 with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing operation on two-phase geothermal fluids. The Project also produced a computer-equipped data system, an instrumentation and control van, and a 1000-kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Additional testing was performed in Mexico in 1980 under a cooperative test program using the same test array, and machine efficiency was measured at 62% maximum with the rotors partially coated with scale, compared with approximately 54% maximum in Utah with uncoated rotors, confirming the importance of scale deposits within the machine on performance. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

McKay, R.

1982-03-01

320

Robotic distal pancreatectomy: a valid option?  

PubMed

Although reported in the literature, conventional laparoscopic approach for distal pancreatectomy is still lacking widespread acceptance. This might be due to two-dimensional vision and decreased range of motion to reach and safely dissect this highly vascularized retroperitoneal organ by laparoscopy. However, interest in minimally invasive access is growing ever since and the robotic system could certainly help overcome limitations of the laparoscopic approach in the challenging domain of pancreatic resection, notably in distal pancreatectomy. Robotic distal pancreatectomy with and without spleen preservation has been reported with encouraging outcomes for benign and borderline malignant disease. As a result of upgraded endowristed manipulation and three-dimensional visualization, improved outcome might be expected with the launch of the robotic system in the procedure of distal pancreatectomy. Our aim was thus to extensively review the current literature of robot-assisted surgery for distal pancreatectomy and to evaluate advantages and possible limitations of the robotic approach. PMID:24101006

Jung, M K; Buchs, N C; Azagury, D E; Hagen, M E; Morel, P

2013-10-01

321

Experimental observation of extremely weak optical scattering from an interlocking carbon nanotube array.  

PubMed

We experimentally demonstrate a nearly wavelength-independent optical reflection from an extremely rough carbon nanotube sample. The sample is made of a vertically aligned nanotube array, is a super dark material, and exhibits a near-perfect blackbody emission at T=450 K-600 K. No other material exhibits such optical properties, i.e., ultralow reflectance accompanied by a lack of wavelength scaling behavior. This observation is a result of the lowest ever measured reflectance (R=0.0003) of the sample over a broad infrared wavelength of 3 ?m < ? < 13 ?m. This discovery may be attributed to the unique interlocking surface of the nanotube array, consisting of both a global, large scale and a short-range randomness. PMID:21532663

Yang, Zu-Po; Hsieh, Mei-Li; Bur, James A; Ci, Lijie; Hanssen, Leonard M; Wilthan, Boris; Ajayan, Pulickel M; Lin, Shawn-Yu

2011-05-01

322

Interlocked optimization and fast gradient algorithm for a seismic inverse problem  

NASA Astrophysics Data System (ADS)

We give a nonlinear inverse method for seismic data recorded in a well from sources at several offsets from the borehole in a 2D acoustic framework. Given the velocity field, approximate values of the impedance are recovered. This is a 2D extension of the 1D inversion of vertical seismic profiles [18]. The inverse problem generates a large scale undetermined ill-conditioned problem. Appropriate regularization terms render the problem well-determined. An interlocked optimization algorithm yields an efficient preconditioning. A gradient algorithm based on the adjoint state method and domain decomposition gives a fast parallel numerical method. For a realistic test case, convergence is attained in an acceptable time with 128 processors.

Métivier, Ludovic

2011-08-01

323

An active interlock system for the NSLS x-ray ring insertion devices  

SciTech Connect

This paper describes the design and operation of an active interlock system which has been installed in the NSLS X-ray electron storage ing to protect the vacuum chamber from thermal damage by mis-steered high power photon beams from insertion devices (IDs). the system employs active beam position detectors to monitor beam motion in the ID straight sections and solid state logic circuitry to dump'' the stored beam in the event of a fault condition by interrupting the rf. To ensure a high degree of reliability, redundancy and continuous automatic checking has been incorporated into the design. Overall system integrity is checked periodically with beam at safe levels of beam current. 2 refs., 3 figs.

Nawrocky, R.J.; Biscardi, R.; Dabrowski, J.; Flannigan, J.; Ramamoorthy, S.; Rothman, J.; Smith, J.; So, I.; Thomas, M. (Brookhaven National Lab., Upton, NY (USA)); Decker, G. (Argonne National Lab., IL (USA))

1991-01-01

324

Radiation interlocks: The choice between conventional hard-wired logic and computer-based systems  

SciTech Connect

During the past few years, the use of computers in radiation safety systems has become more widespread. This is not surprising given the ubiquitous nature of computers in the modern technological world. But is a computer a good choice for the central logic element of a personnel safety system. Recent accidents at computer controlled medical accelerators would indicate that extreme care must be exercised if malfunctions are to be avoided. The Department of Energy has recently established a sub-committee to formulate recommendations on the use of computers in safety systems for accelerators. This paper will review the status of the committee's recommendations, and describe radiation protection interlock systems as applied to both accelerators and to irradiation facilities. Comparisons are made between the conventional relay approach and designs using computers. 6 refs., 6 figs.

Crook, K.F.

1986-11-01

325

D0 Central Tracking Solenoid Energizatino, Controls, Interlocks and Quench Protection Initial Validation Procedures  

SciTech Connect

This note presents the inspection and tests to be performed on the DZERO solenoid energization, controls, interlocks and quench protection system before it is energized for the first time. This test is to be performed with a 5000A jumper at the end of the bus instead of the solenoid. This system is based in DZERO room 511. A copy of this note shall be annotated, signed and dated by the person coordinating the procedure; and filed with the system maintenance records. Annotations shall include comments about any aspect of the procedure that is abnormal or unsuccessful. The following inspections and tests shall be performed by persons knowledgeable about the system. Each individual test step should be reviewed and understood before proceeding with that step.

Jaskierny, W.; Hance, R.; /Fermilab

1998-01-27

326

Interlocked grain growth of YBCO film on magnesium oxide as observed by scanning tunneling microscopy  

SciTech Connect

Thin films of YBa[sub 2]Cu[sub 3]O[sub 7] on MgO deposited by RF magnetron sputtering to study their superconducting behavior, were examined by a Scanning Tunneling Microscope. The films were deposited at room temperature, sintered exsitu at 850 C, 900 C, 930 C, 950 C and 980 C for 30 minutes each and cooled at rate of 100 C per hour in oxygen ambient. Topographic images taken in air show that the films which were initially amorphous in nature, gradually transform to a layered grain structure with the increase of sintering temperature. Films sintered at temperatures above 900 C are c-axis oriented and have a coarse grain structure. These grains layers of neighboring grains. The mechanism of interlocking of layers from adjacent grains and its possible influence on the superconducting properties has been discussed.

Rao, M.V.H.; Mishra, S.K.; Pathak, L.C.; Mathur, B.K.; Bhattacharya, D.; Chopra, K.L. (Indian Inst. of Technology, Kharagpur (India))

1993-03-01

327

The Community Structure of the European Network of Interlocking Directorates 2005-2010  

PubMed Central

The boards of directors at large European companies overlap with each other to a sizable extent both within and across national borders. This could have important economic, political and management consequences. In this work we study in detail the topological structure of the networks that arise from this phenomenon. Using a comprehensive information database, we reconstruct the implicit networks of shared directorates among the top 300 European firms in 2005 and 2010, and suggest a number of novel ways to explore the trans-nationality of such business elite networks. Powerful community detection heuristics indicate that geography still plays an important role: there exist clear communities and they have a distinct national character. Nonetheless, from 2005 to 2010 we observe a densification of the boards interlocks network and a larger transnational orientation in its communities. Together with central actors and assortativity analyses, we provide statistical evidence that, at the level of corporate governance, Europe is getting closer.

Heemskerk, Eelke M.; Daolio, Fabio; Tomassini, Marco

2013-01-01

328

The influence of screw configuration on the pretreatment performance of a continuous twin screw-driven reactor (CTSR).  

PubMed

A combination of a continuous twin screw-driven reactor (CTSR) and a dilute acid pretreatment was used for the pretreatment of biomass with a high cellulose content and high monomeric xylose hydrolyzate. With the newly modified CTSR screw configuration (Config. 3), the influences of the screw rotational speed (30-60 rpm), of the pretreatment conditions such as acid concentration (1-5%) and reaction temperature (160-175 °C) at the operating condition of biomass feeding rate (1.0 g/min) and acid feeding rate (13.4 mL/min) on the pretreatment performance were investigated. The cellulose content in the pretreated rape straw was 67.1% at the following optimal conditions: barrel temperature of 165 °C, acid concentration of 3.0% (w/v), and screw rotational speed of 30 rpm. According to the three screw configurations, the glucose yields from enzymatic hydrolysis were 70.1%, 72.9%, and 78.7% for screw Configs. 1, 2, and 3, respectively. PMID:23395738

Choi, Chang Ho; Um, Byung-Hwan; Oh, Kyeong Keun

2013-01-11

329

Unilateral distal molar movement with an implant-supported distal jet appliance.  

PubMed

With the guidance of the basis of the distal jet appliance, we present a new implant-supported distal jet appliance. In this case, we used a modified distal jet appliance that was supported by a palatal implant placed at the anterior edge of the rugae region of the palate for molar distalization. The treatment results were evaluated from lateral cephalometric and panoramic radiographs and dental casts. We conclude that an implant-supported modified distal jet appliance is effective in the correction of a Class II molar relationship. PMID:11999940

Karaman, A I; Basciftci, F A; Polat, O

2002-04-01

330

Periscope graft to extend distal landing zone in ruptured thoracoabdominal aneurysms with short distal necks.  

PubMed

Endovascular aneurysm repair (EVAR) of ruptured thoracoabdominal aortic aneurysms may be compromised or even impossible due to short proximal and/or distal necks or landing zones, respectively. Supra-aortic branches may limit the proximal anchorage and visceral or renal arteries the distal anchorage of endografts. While solutions have been proposed to overcome the problem of a short proximal neck, no technique has been described that solves the problem of a short distal neck. We present the "periscope technique," which allows extension of the distal landing zone and complete endovascular treatment of ruptured thoracoabdominal aneurysms with short distal necks using devices already stocked in most centers performing EVAR procedures. PMID:20299176

Rancic, Zoran; Pfammatter, Thomas; Lachat, Mario; Hechelhammer, Lukas; Frauenfelder, Thomas; Veith, Frank J; Criado, Frank J; Mayer, Dieter

2010-03-29

331

A DEM model for soft and hard rocks: Role of grain interlocking on strength  

NASA Astrophysics Data System (ADS)

The Discrete Element Method (DEM) is increasingly used to simulate the behavior of rock. Despite their intrinsic capability to model fracture initiation and propagation starting from simple interaction laws, classical DEM formulations using spherical discrete elements suffer from an intrinsic limitation to properly simulate brittle rock behavior characterized by high values of UCS/TS ratio associated with non-linear failure envelopes, as observed for hard rock like granite. The present paper shows that the increase of the interaction range between the spherical discrete elements, which increases locally the density of interaction forces (or interparticle bonds), can overcome this limitation. It is argued that this solution represents a way to implicitly take into account the degree of interlocking associated to the microstructural complexity of rock. It is thus shown that increasing the degree of interlocking between the discrete elements which represent the rock medium, in addition to enhancing the UCS/TS ratio, results in a non-linear failure envelop characteristic of low porous rocks. This approach improves significantly the potential and predictive capabilities of the DEM for rock modeling purpose. A special emphasis is put on the model ability to capture the fundamental characteristics of brittle rocks in terms of fracture initiation and propagation. The model can reproduce an essential component of brittle rock failure, that is, cohesion weakening and frictional strengthening as a function of rock damage or plastic strain. Based on model predictions, it is finally discussed that frictional strengthening may be at the origin of the brittle ductile transition occurring at high confining pressures.

Scholtès, Luc; Donzé, Frédéric-Victor

2013-02-01

332

Interlocking of chelae is a key factor for dominance hierarchy formation in crayfish.  

PubMed

We characterized the role of chelae during agonistic encounters of the crayfish Procambarus clarkii. Physical asymmetries in body length, body mass and chelae size were directly related to dominance hierarchy formation. More than 80% of winning crayfish had longer body and chelae lengths, and winners were usually heavier in body mass, even if their differences were less than 3% compared with losing opponents. In mismatched pairings, large crayfish with short chelae were beaten by small crayfish with large chelae. Three physical elements of body length, body mass and chelae length equally affected the outcome of agonistic bouts. Chelae restriction, in which chelae were tightly closed using rubber bands, affected the outcome of agonistic bouts between large and small crayfish. Before chelae restriction, large crayfish won in all pairings. Following chelae restriction for at least 30 days from the first encounters, the winning rate of large crayfish that were previous winners decreased significantly in the second encounters against the same opponents that were previous losers. The handicap of chelae restriction significantly prolonged the time to formation of the winner-loser relationship. Individual fights escalated during agonistic bouts between large crayfish with one chela restricted and small crayfish with intact chelae, whereas the number of fights increased but the duration of individual fights did not increase in large crayfish with both chelae restricted. Furthermore, when the chelae of both large and small crayfish were disabled, the dominance order was frequently not formed during 30 min of agonistic bouts. Preventing chelae from interlocking prevented escalation of agonistic bouts. We show that interlocking of chelae acted as a key factor for the formation of dominance hierarchy. PMID:22837457

Ueno, Ryusuke; Nagayama, Toshiki

2012-08-15

333

Windshield-wiper loosening: a complication of in situ screw fixation of slipped capital femoral epiphysis.  

PubMed

A retrospective review of patients treated for slipped capital femoral epiphysis (SCFE) by in situ screw fixation with a cannulated titanium screw was performed. Of the 18 hips with at least 1-year follow-up, windshield-wiper loosening of the cannulated screw in the femoral head had occurred in three. In all three cases, the screw had been left protruding > 1.5 cm from the anterolateral cortex of the femur. We postulate that with hip motion the protruding screw is toggled by the anterolateral soft tissues, causing a windshield-wiper effect in the femoral head, leading to eventual screw loosening. We believe that leaving the screw protruding from the fascia lata is a potential source of screw loosening by the windshield-wiper mechanism and now routinely place the screw head within 1.5 cm of the anterolateral cortex of the femur. PMID:8376561

Maletis, G B; Bassett, G S

334

Biomechanical analysis of pedicle screw density in spinal instrumentation for scoliosis treatment: first results.  

PubMed

Clinical studies reveal remarkable variation in screw patterns, or screw density in spinal instrumentation. Screw density may have a great impact on blood loss, operative time, radiation, risk of screw malposition, and cost. Thus, there is a need to understanding of the biomechanical effects of screw density so as to minimize the number of pedicle screws while ensuring safe and effective instrumentation. The objective of this study was to compare the deformity correction effects and bone-screw loadings of different pedicle screw densities in spinal instrumentation for scoliosis treatment. Spinal instrumentation simulations were performed on three scoliosis patients using 3 screw density patterns (low, preferred, and high screw density) proposed by two experienced surgeons and basic correction techniques: concave rod attachment, rod derotation, apical vertebral derotation, and convex side rod attachment. Simulation results showed that all tested screw densities generated quite similar correction, with differences between the achieved corrections all below 3°. The average bone-screw forces were 244±67N, 214±66 N, and 210±71 N, respectively for low, preferred, and high densities. It remains a complex challenge balancing the benefit of load sharing between more implants with the overconstraints and limited degrees of freedom introduced by the increased number of implants. Studies on additional screw densities and patterns proposed by more surgeons for a variety of cases, and using more diverse correction techniques are necessary to draw stronger conclusions and to recommend the optimal screw density. PMID:22744515

Wang, Xiaoyu; Aubin, Carl-Eric; Larson, A Noelle; Labelle, Hubert; Parent, Stefan

2012-01-01

335

Design of internal screw thread measuring device based on the Three-Line method principle  

NASA Astrophysics Data System (ADS)

In accordance with the principle of Three-Line, this paper analyze the correlation of every main parameter of internal screw thread, and then designed a device to measure the main parameters of internal screw thread. Internal thread parameters, such as the pitch diameter, thread angle and screw-pitch of common screw thread, terraced screw thread, zigzag screw thread were obtained through calculation and measurement. The practical applications have proved that this device is convenience to use, and the measurements have a high accuracy. Meanwhile, the application for the patent of invention has been accepted by the Patent Office (Filing number: 200710044081.5).

Hu, Dachao; Chen, Jianguo

2010-08-01

336

[Observations on before and after employ of screw of implant denture with SEM].  

PubMed

The loss of screw is one of the clinic complication in MDIC implant denture cases. The purpose of this study is to find the cause of loss of screw. The authors has studied MDIC implant denture with SEM before and after employ of the screw and found that the causes of screw loss were crevice corrosion and friction pressure. Crevice corrosion may promote the loss of screw. Base the above condition, it is necessary to select Ti-alloy screw and associat with anticorrosive measure in MDIC implant denture construction. PMID:10677963

Song, Y; Xu, J; Ma, X

1997-03-01

337

A processing method for orthodontic mini-screws reuse  

PubMed Central

Background: The possibility of mini-screws reuse would reduce treatment cost. The aim of this study is to introduce a new method (application of phosphoric acid 37% for 10 minutes followed by sodium hypochlorite 5.25% for 30 minutes) for cleansing of mini-screws and assessing the efficacy of this method. The effects of this processing on the insertion, removal, and fracture torques of mini-screws were evaluated. Materials and Methods: This experimental study was done in two parts. In part I the amount of calcium ion on mini-screws surfaces as an index of tissue remnants was assessed. In part II of this study, the effects of previous use, processing method, and resterilization on the insertion, removal, and fracture torques of mini-screws were assessed. Each part of this study had 3 groups; non-processed used (NP), processed used (P), and as-received (C). Each group had 16 samples in part I and 20 samples. Non parametric statistical tests were used in part I and one way ANOVA in part II. Results: The mean amount of calcium ion in groups non-processed (NP1), processed (P1), and control (C1) were 4.7, 0.43, and 0.02 ppm, respectively. The amount of calcium ion in group NP1 was significantly greater than in the other groups (P = 0.000), but the difference between groups P1 and C1 was not significant (P = 0.087). The mean insertion torque of group NP2 was lower than that of other groups (P < 0.05) but P2 and C2 did not have significant differences (P = 0.988). The mean of removal and fracture torque did not have significant differences among all groups. Conclusion: Cleaning of used mini-screws with phosphoric acid 37% (10 minutes) and sodium hypochlorite 5.25% (30 minutes) reduces tissue remnants to the level of as-received mini-screws. So it can be suggested as a processing method of used mini-screws. Previous insertion of mini-screws into the bone and above-mentioned processing method and resterilization with autoclave had no adverse effects on insertion, removal, and fracture torque values as mechanical properties indices.

Noorollahian, Saeed; Alavi, Shiva; Monirifard, Mohammad

2012-01-01

338

Percutaneous Iliac Screws for Minimally Invasive Spinal Deformity Surgery  

PubMed Central

Introduction. Adult spinal deformity (ASD) surgeries carry significant morbidity, and this has led many surgeons to apply minimally invasive surgery (MIS) techniques to reduce the blood loss, infections, and other peri-operative complications. A spectrum of techniques for MIS correction of ASD has thus evolved, most recently the application of percutaneous iliac screws. Methods. Over an 18 months 10 patients with thoracolumbar scoliosis underwent MIS surgery. The mean age was 73 years (70% females). Patients were treated with multi-level facet osteotomies and interbody fusion using expandable cages followed by percutaneous screw fixation. Percutaneous iliac screws were placed bilaterally using the obturator outlet view to target the ischial body. Results. All patients were successfully instrumented without conversion to an open technique. Mean operative time was 302 minutes and the mean blood loss was 480?cc, with no intraoperative complications. A total of 20 screws were placed successfully as judged by CT scanning to confirm no bony violations. Complications included: two asymptomatic medial breaches at T10 and L5, and one patient requiring delayed epidural hematoma evacuation. Conclusions. Percutaneous iliac screws can be placed safely in patients with ASD. This MIS technique allows for successful caudal anchoring to stress-shield the sacrum and L5-S1 fusion site in long-segment constructs.

Wang, Michael Y.

2012-01-01

339

Screw dislocations in GaN grown by different methods  

SciTech Connect

A study of screw dislocations in Hydride-Vapor-Phase-Epitaxy (HVPE) template and Molecular-Beam-Epitaxy (MBE) over-layers was performed using Transmission Electron Microscopy (TEM) in plan-view and in cross-section. It was observed that screw dislocations in the HVPE layers were decorated by small voids arranged along the screw axis. However, no voids were observed along screw dislocations in MBE overlayers. This was true both for MBE samples grown under Ga-lean and Ga-rich conditions. Dislocation core structures have been studied in these samples in the plan-view configuration. These experiments were supported by image simulation using the most recent models. A direct reconstruction of the phase and amplitude of the scattered electron wave from a focal series of high-resolution images was applied. It was shown that the core structures of screw dislocations in the studied materials were filled. The filed dislocation cores in an MBE samples were stoichiometric. However, in HVPE materials, single atomic columns show substantial differences in intensities and might indicate the possibility of higher Ga concentration in the core than in the matrix. A much lower intensity of the atomic column at the tip of the void was observed. This might suggest presence of lighter elements, such as oxygen, responsible for their formation.

Liliental-Weber, Z.; Zakharov, D.; Jasinski, J.; O'Keefe, M.A.; Morkoc, H.

2003-05-27

340

Screw dislocations in GaN grown by different methods.  

PubMed

A study of screw dislocations in hydride-vapor-phase-epitaxy (HVPE) template and molecular-beam-epitaxy (MBE) overlayers was performed using transmission electron microscopy (TEM) in plan view and in cross section. It was observed that screw dislocations in the HVPE layers were decorated by small voids arranged along the screw axis. However, no voids were observed along screw dislocations in MBE overlayers. This was true both for MBE samples grown under Ga-lean and Ga-rich conditions. Dislocation core structures have been studied in these samples in the plan-view configuration. These experiments were supported by image simulation using the most recent models. A direct reconstruction of the phase and amplitude of the scattered electron wave from a focal series of high-resolution images was applied. It was shown that the core structures of screw dislocations in the studied materials were filled. The filed dislocation cores in an MBE samples were stoichiometric. However, in HVPE materials, single atomic columns show substantial differences in intensities and might indicate the possibility of higher Ga concentration in the core than in the matrix. A much lower intensity of the atomic column at the tip of the void was observed. This might suggest presence of lighter elements, such as oxygen, responsible for their formation. PMID:15306067

Liliental-Weber, Z; Zakharov, D; Jasinski, J; O'Keefe, M A; Morkoc, H

2004-02-01

341

Percutaneous iliac screws for minimally invasive spinal deformity surgery.  

PubMed

Introduction. Adult spinal deformity (ASD) surgeries carry significant morbidity, and this has led many surgeons to apply minimally invasive surgery (MIS) techniques to reduce the blood loss, infections, and other peri-operative complications. A spectrum of techniques for MIS correction of ASD has thus evolved, most recently the application of percutaneous iliac screws. Methods. Over an 18 months 10 patients with thoracolumbar scoliosis underwent MIS surgery. The mean age was 73 years (70% females). Patients were treated with multi-level facet osteotomies and interbody fusion using expandable cages followed by percutaneous screw fixation. Percutaneous iliac screws were placed bilaterally using the obturator outlet view to target the ischial body. Results. All patients were successfully instrumented without conversion to an open technique. Mean operative time was 302 minutes and the mean blood loss was 480?cc, with no intraoperative complications. A total of 20 screws were placed successfully as judged by CT scanning to confirm no bony violations. Complications included: two asymptomatic medial breaches at T10 and L5, and one patient requiring delayed epidural hematoma evacuation. Conclusions. Percutaneous iliac screws can be placed safely in patients with ASD. This MIS technique allows for successful caudal anchoring to stress-shield the sacrum and L5-S1 fusion site in long-segment constructs. PMID:22900162

Wang, Michael Y

2012-07-29

342

Isolated intra-articular fracture of the distal ulna: a rare injury related to airbag deployment.  

PubMed

An isolated intra-articular and adjacent shaft fracture of the distal ulna is described. A 38-old-year woman driver sustained an automobile accident with subsequent airbag deployment injuring her left wrist. Imaging studies showed displacement of a radiovolar fragment and deformity of the ulnar articular surface. The fracture was reduced and internally fixed with 3, 3.5-mm, cannulated screws to avoid future difficulties in forearm rotation, ulnocarpal impaction, and late posttraumatic arthritis. The final outcome was excellent. Careful clinical and radiologic examination is strongly recommended for this type of fracture, which seems to be a part of the spectrum of upper limb injuries associated with airbag deployment. Such injuries can be expected to occur more frequently with the increasing use of airbags. PMID:16721248

Goikoetxea, Xabier; Garmilla, Iñaki; Etxebarria, Iñigo; Careaga, Miguel

2006-04-01

343

2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries - a case series  

PubMed Central

Background Screw fixation of pelvic ring fractures is a common, but demanding procedure and navigation techniques were introduced to increase the precision of screw placement. The purpose of this case series was the evaluation of screw misplacement rate and functional outcome of percutaneous screw fixation of pelvic ring disruptions using a 2D navigation system. Methods Between August 2004 and December 2007, 44 of 442 patients with pelvic injuries were included for closed reduction and percutaneous screw fixation of disrupted pelvic ring lesions using an optoelectronic 2D-fluoroscopic based navigation system. Operating and fluoroscopy time were measured, as well as peri- and postoperative complications documented. Screw position was assessed by postoperative CT scans. Quality of live was evaluated by SF 36-questionnaire in 40 of 44 patients at mean follow up 15.5 ± 1.2 month. Results 56 iliosacral- and 29 ramus pubic-screws were inserted (mean operation time per screw 62 ± 4 minutes, mean fluoroscopy time per screw 123 ± 12 seconds). In post-operative CT-scans the screw position was assessed and graded as follows: I. secure positioning, completely in the cancellous bone (80%); II. secure positioning, but contacting cortical bone structures (14%); III. malplaced positioning, penetrating the cortical bone (6%). The malplacements predominantly occurred in bilateral overlapping screw fixation. No wound infection or iatrogenic neurovascular damage were observed. Four re-operations were performed, two of them due to implant-misplacement and two of them due to implant-failure. Conclusion 2D-fluoroscopic navigation is a safe tool providing high accuracy of percutaneous screw placement for pelvic ring fractures, but in cases of a bilateral iliosacral screw fixation an increased risk for screw misplacement was observed. If additional ramus pubic screw fixations are performed, the retrograde inserted screws have to pass the iliopubic eminence to prevent an axial screw loosening.

2010-01-01

344

SEM and fractography analysis of screw thread loosening in dental implants.  

PubMed

Biological and technical failures of implants have already been reported. Mechanical factors are certainly of importance in implant failures, even if their exact nature has not yet been established. The abutment screw fracture or loosening represents a rare, but quite unpleasant failure. The aim of the present research is an analysis and structural examination of screw thread or abutment loosening compared with screw threads or abutment without loosening. The loosening of screw threads was compared to screw thread without loosening of three different implant systems; Branemark (Nobel Biocare, Gothenburg, Sweden), T.B.R. implant systems (Benax, Ancona, Italy) and Restore (Lifecore Biomedical, Chaska, Minnesota, USA). In this study broken screws were excluded. A total of 16 screw thread loosenings were observed (Group I) (4 Branemark, 4 T.B.R and 5 Restore), 10 screw threads without loosening were removed (Group II), and 6 screw threads as received by the manufacturer (unused) (Group III) were used as control (2 Branemark, 2 T.B.R and 2 Restore). The loosened abutment screws were retrieved and analyzed under SEM. Many alterations and deformations were present in concavities and convexities of screw threads in group I. No macroscopic alterations or deformations were observed in groups II and III. A statistical difference of the presence of microcracks were observed between screw threads with an abutment loosening and screw threads without an abutment loosening. PMID:17897496

Scarano, A; Quaranta, M; Traini, T; Piattelli, M; Piattelli, A

345

Comparative study on stress distribution around internal tapered connection implants according to fit of cement- and screw-retained prostheses  

PubMed Central

PURPOSE The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of ?=.05. RESULTS The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 µm/m at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. CONCLUSION Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit.

Lee, Mi-Young; Heo, Seong-Joo; Park, Eun-Jin

2013-01-01

346

Robot-Assisted Laparoscopic Distal Ureteral Surgery  

PubMed Central

Background: The use of robotic assistance in adult genitourinary surgery has been successful in many operations, leading surgeons to test its use in other applications as well. Methods: Based on our use during prostatectomy, we have applied robotic surgery to complex distal ureteral surgeries since 2004 with successful outcomes. Results: A series of 11 patients who underwent robot-assisted laparoscopic distal ureteral surgery is presented. These surgeries include distal ureterectomy for ureteral cancer with reimplantation, as well as reimplantation with and without Boari flap or psoas hitch for benign conditions. Conclusions: Robot-assisted laparoscopic surgery can be successfully applied to patients requiring distal ureteral surgery. Maintenance of the principles of open surgery is paramount.

Wagner, Joseph R.

2009-01-01

347

Intramedullary screw fixation for midshaft fractures of the clavicle  

PubMed Central

Open intramedullary fixation of 37 fresh midshaft clavicular fractures in 35 patients was performed using a 6.5 partially threaded cancellous screw. Mean age was 38 years (range 18–65). The screw was inserted from the medial fragment after retrograde drilling of that fragment. Average follow-up period was 21 months (range 9–36). Radiological evidence of union was apparent in all cases within six to eight weeks after surgery (mean 7.8). Two cases had intraoperative failure of fixation, nine complained of subcutaneous prominence of the screw head, five experienced decreased sensation over the site of incision, and three had symptoms of frozen shoulder. In conclusion, the technique is simple, affordable and it does not require special instrumentation or implants. It allows intramedullary compression, stability, stress sharing, minimal periosteal stripping, and early recovery after surgery.

2009-01-01

348

Mild coal gasification screw pyrolyzer development and design  

SciTech Connect

Our objective is to produce information and design recommendations needed for the development of an efficient continuous process for the mild gasification of caking bituminous coals. We have focused on the development of an externally heated pyrolyzer in which the sticky, reacting coal is conveyed by one or more screws. We have taken a multifaceted approach to forwarding the development of the externally-heated screw pyrolyzer. Small scale process experiments on a 38-mm single screw pyrolyzer have been a major part of our effort. Engineering analyses aimed at producing design and scaleup equations have also been important. Process design recommendations follow from these. We critically review our experimental data and experience, and information from the literature and equipment manufactures for the purpose of making qualitative recommendations for improving practical pyrolyzer design and operation. Benchscale experiments are used to supply needed data and test some preliminary concepts. 6 refs., 4 figs., 1 tab.

Camp, D.W.

1990-08-01

349

The distal venous anatomy of the finger.  

PubMed

An exhaustive anatomic dissection of all of the veins of the finger distal to the proximal interphalangeal joint was done. More than 3200 segments of veins were individually dissected out, measured, and recorded. From this survey new schematic diagrams have been drawn emphasizing the pertinent venous anatomy at the proximal, distal interphalangeal joints and eponychial levels. Suggestions are made for regions that are apt to have the largest vessels available for anastomosis. PMID:2022842

Smith, D O; Oura, C; Kimura, C; Toshimori, K

1991-03-01

350

[Distal protection devices in carotid stent].  

PubMed

Endovascular treatment of carotid stenoses is increasingly used. Frequently temporary occlusion balloons or filters are placed distal to the stenosis to gain additional protection against cerebral emboli. There is still a scientific debate about the usefulness of such distal protection devices. The following contribution reviews existing techniques and their clinical results and should allow for a critical discussion and selection of current techniques and materials. PMID:15549222

Berkefeld, J; du Mesnil de Rochemont, R; Sitzer, M; Zanella, F E

2004-10-01

351

Nonunion of the scaphoid distal pole.  

PubMed

This study was undertaken to determine the incidence of and assess factors affecting nonunion of scaphoid distal pole fractures. A total of 193 established scaphoid nonunions were treated in our clinics between the years 1999 and 2004; of which, eight cases involved the distal pole of the scaphoid. These were further analyzed to determine factors that may have contributed to the development of nonunion. This study reveals that distal pole nonunions account for 4.1% of all scaphoid nonunions. We found inadequate initial treatment to be the cause for nonunion in 63% of patients. Type IIC fracture pattern according to Posser's classification was seen in 100% of patients and a persistent Dorsal Intercalated Segmental Instability (DISI) pattern in 100% patients. In addition, 100% of fractures occurred at the watershed zone between the two vascular networks of the scaphoid. We believe the key features leading to the likelihood of nonunion at the distal pole include a Type IIC fracture pattern associated with a continued deforming force that eventually leads to a DISI deformity. The watershed area between the proximal vascular network supplying the waist and the distal one supplying the distal pole is especially vulnerable to poor healing. PMID:23413847

Oron, Amir; Gupta, Amitava; Thirkannad, Sunil

2013-01-01

352

Posttreatment evaluation of the distal jet appliance.  

PubMed

This study analyzed molar distalization with the distal jet appliance, its effect on the anchor teeth, and the outcome at the completion of orthodontic treatment. Pretreatment, after distalization, and posttreatment lateral cephalometric radiographs were evaluated for 21 adolescent girls and 12 adolescent boys. The mean age of the subjects at the time of the pretreatment radiograph was 12.8 +/- 2.2 years. The mean time for the correction of the Class II molar relationship was 6.7 +/- 1.7 months, and the mean total treatment time was 25.7 +/- 3.9 months. The results of this study showed that the distal jet appliance distalized the maxillary molars, but there was significant loss of anchorage. The distal jet also showed less tipping of the maxillary molars and better bodily movement of molars because the force was applied closer to the center of resistance. The observations of treatment outcome indicate that the 1.8-mm mean net anterior movement of the maxillary first molar was more than offset by the 4.8-mm mesial movement of the mandibular first molar. There was no significant increase in lower face height. Consequently the effect on the facial balance was negligible. PMID:11500660

Ngantung, V; Nanda, R S; Bowman, S J

2001-08-01

353

Ground-state thermodynamics of bistable redox-active donor-acceptor mechanically interlocked molecules.  

PubMed

Fashioned through billions of years of evolution, biological molecular machines, such as ATP synthase, myosin, and kinesin, use the intricate relative motions of their components to drive some of life's most essential processes. Having control over the motions in molecules is imperative for life to function, and many chemists have designed, synthesized, and investigated artificial molecular systems that also express controllable motions within molecules. Using bistable mechanically interlocked molecules (MIMs), based on donor-acceptor recognition motifs, we have sought to imitate the sophisticated nanoscale machines present in living systems. In this Account, we analyze the thermodynamic characteristics of a series of redox-switchable [2]rotaxanes and [2]catenanes. Control and understanding of the relative intramolecular movements of components in MIMs have been vital in the development of a variety of applications of these compounds ranging from molecular electronic devices to drug delivery systems. These bistable donor-acceptor MIMs undergo redox-activated switching between two isomeric states. Under ambient conditions, the dominant translational isomer, the ground-state coconformation (GSCC), is in equilibrium with the less favored translational isomer, the metastable-state coconformation (MSCC). By manipulating the redox state of the recognition site associated with the GSCC, we can stimulate the relative movements of the components in these bistable MIMs. The thermodynamic parameters of model host-guest complexes provide a good starting point to rationalize the ratio of GSCC to MSCC at equilibrium. The bistable [2]rotaxanes show a strong correlation between the relative free energies of model complexes and the ground-state distribution constants (K(GS)). This relationship does not always hold for bistable [2]catenanes, most likely because of the additional steric and electronic constraints present when the two rings are mechanically interlocked with each other. Measuring the ground-state distribution constants of bistable MIMs presents its own set of challenges. While it is possible, in principle, to determine these constants using NMR and UV-vis spectroscopies, these methods lack the sensitivity to permit the determination of ratios of translational isomers greater than 10:1 with sufficient accuracy and precision. A simple application of the Nernst equation, in combination with variable scan-rate cyclic voltammetry, however, allows the direct measurement of ground-state distribution constants across a wide range (K(GS) = 10-10(4)) of values. PMID:22741809

Fahrenbach, Albert C; Bruns, Carson J; Cao, Dennis; Stoddart, J Fraser

2012-06-28

354

Biodegradation of Inion fast-absorbing biodegradable plates and screws.  

PubMed

Biodegradable plates and screws are recommended for use in surgery of the craniofacial skeleton of children. To be effective and not interfere with growth of the child's skull, the plates must biodegrade sufficiently to release the holding power of the plate and screw within 1 year. It is also essential that excessive foreign body reaction and cyst formation does not occur when the plates and screws biodegrade. The purpose of this experimental study was to evaluate the rate of biodegradation of Inion CPS Baby biodegradable plates and screws under different clinical circumstances in the rabbit craniofacial skeleton and evaluate their efficacy for use in pediatric craniofacial surgery. Foreign body reaction would be evaluated. Inion baby plates and screws were tested in a rabbit model. Plates were applied to the frontal bone, over a bony defect of the parietal bone, to a nasal bone fracture, and inserted in the subcutaneous space over the occipital bone in thirty 6-week-old rabbits. Six rabbits were euthanized at 9, 12, 15, and 18 months' postoperative time point and examined for residual plates and screws. Bone from each surgical site was excised, fixed by immersion in 10% neutral-buffered formalin, decalcified in Immunocal solution, and examined by 7-microm paraffin sections stained with hematoxylin and eosin. At 9 months, the plates and screws had effectively biodegraded and no longer had holding power on the bones. Fragmentation of the implant material was noted. Residual implant material was still present on gross and histologic examination in rabbits at 9, 12, 15, and 18 months. Residue of a screw was still palpable in 1 rabbit at 18 months. There was no evidence of cyst formation in any of the examined specimens. Macrophages and giant cells were present in most of the specimens at 9, 12, 15, and 18 months. Findings from the current study revealed a relative short resorption time (9 mo) and normal inflammatory sequelae in an adult rabbit model. These findings suggest that these plates may be used safely in fixing the pediatric craniofacial skeleton. PMID:18520394

Losken, H Wolfgang; van Aalst, John A; Mooney, Mark P; Godfrey, Virginia L; Burt, Tripti; Teotia, Sumeet; Dean, Shay B; Moss, Jonathan R; Rahbar, Reza

2008-05-01

355

Evaluation of maxillary molar distalization with the distal jet: a comparison with other contemporary methods.  

PubMed

Maxillary molar distalization is an increasingly popular option for the resolution of Class II malocclusions. This communication describes the effects of one particular molar distalizing appliance, the distal jet, in a sample of 20 consecutively treated and growing subjects (11 females, nine males; mean starting age of 13) and compares these effects with those of similar devices. Pre- and postdistalization cephalometric radiographs and dental models were analyzed to determine the dental and skeletal effects. The distal jet appliances were constructed using a biomechanical couple to direct the distalizing force to the level of the maxillary first molar's center of resistance. The distal jet was the only appliance used during the distalization phase of treatment. Examination of the cephalometric tracings demonstrated that the crowns of the maxillary first molars were distalized an average of 3.2 mm into a Class I molar relationship. In the process, the first molars were tipped distally an average of 3.1 degrees, however, the amount of tipping in each case was influenced by the state of eruption of the second molar. In subjects whose second molars had erupted only to the level of the apical third of the first molar roots, distal tipping was almost twice that seen when the second molar had completed their eruption. Anchorage loss measured at the first premolars averaged 1.3 mm, but the crowns tipped 3.1 degrees distally because of the design of the appliance. The maxillary incisors were proclined an average of 0.6 degrees with minimal effect on the mandibular plane angle and lower facial height. This study suggests that the distal jet appliance effectively moves the maxillary molars distally into a Class I molar relationship with minimal distal tipping, however, some loss of anchorage is to be expected during this process. The distal jet appliance compares favorably with other intraoral distalization devices and with mechanics featuring mandibular protraction for the resolution of patients with Class II, despite the fact that these types of mechanics address different jaws. PMID:12401059

Bolla, Eugenio; Muratore, Filippo; Carano, Aldo; Bowman, S Jay

2002-10-01

356

Posterior fusion only for thoracic adolescent idiopathic scoliosis of more than 80?: pedicle screws versus hybrid instrumentation  

PubMed Central

The treatment of thoracic adolescent idiopathic scoliosis (AIS) of more than 80° traditionally consisted of a combined procedure, an anterior release performed through an open thoracotomy followed by a posterior fusion. Recently, some studies have reassessed the role of posterior fusion only as treatment for severe thoracic AIS; the correction rate of the thoracic curves was comparable to most series of combined anterior and posterior surgery, with shorter surgery time and without the negative effect on pulmonary function of anterior transthoracic exposure. Compared with other studies published so far on the use of posterior fusion alone for severe thoracic AIS, the present study examines a larger group of patients (52 cases) reviewed at a longer follow-up (average 6.7 years, range 4.5–8.5 years). The aim of the study was to evaluate the clinical and radiographic outcome of surgical treatment for severe thoracic (>80°) AIS treated with posterior spinal fusion alone, and compare comprehensively the results of posterior fusion with a hybrid construct (proximal hooks and distal pedicle screws) versus a pedicle screw instrumentation. All patients (n = 52) with main thoracic AIS curves greater than 80° (Lenke type 1, 2, 3, and 4), surgically treated between 1996 and 2000 at one institution, by posterior spinal fusion either with hybrid instrumentation (PSF–H group; n = 27 patients), or with pedicle screw-only construct (PSF–S group; n = 25 patients) were reviewed. There were no differences between the two groups in terms of age, Risser’s sign, Cobb preoperative main thoracic (MT) curve magnitude (PSF–H: 92° vs. PSF–S: 88°), or flexibility on bending films (PSF–H: 27% vs. PSF–S: 25%). Statistical analysis was performed using the t test (paired and unpaired), Wilcoxon test for non-parametric paired analysis, and the Mann–Whitney test for non-parametric unpaired analysis. At the last follow-up, the PSF–S group, when compared to the PSF–H group had a final MT correction rate of 52.4 versus 44.52% (P = 0.001), with a loss of ?1.9° versus ?11.3° (P = 0.0005), a TL/L correction of 50 versus 43% (ns), a greater correction of the lowest instrumented vertebra translation (?1.00 vs. ?0.54 cm; P = 0.04), and tilt (?19° vs. ?10°; P = 0.005) on the coronal plane. There were no statistically significant differences in sagittal and global coronal alignment between the two groups (C7-S1 offset: PSF–H = 0.5 cm vs. PSF–S = 0 cm). In the hybrid series (27 patients) surgery-related complications necessitated three revision surgeries, whereas in the screw group (25 patients) one revision surgery was performed. No neurological complications or deep wound infection occurred in this series. In conclusion, posterior spinal fusion for severe thoracic AIS with pedicle screws only, when compared to hybrid construct, allowed a greater coronal correction of both main thoracic and secondary lumbar curves, less loss of the postoperative correction achieved, and fewer revision surgeries. Posterior-only fusion with pedicle screws enabled a good and stable correction of severe scoliosis. However, severe curves may be amenable to hybrid instrumentation that produced analogous results to the screws-only constructs concerning patient satisfaction; at the latest follow-up, SRS-30 and SF-36 scores did not show any statistical differences between the two groups.

Bakaloudis, Georgios; Lolli, Francesco; Vommaro, Francesco; Martikos, Konstantinos; Parisini, Patrizio

2008-01-01

357

Fixation with reconstruction plates under critical conditions: the role of screw characteristics  

Microsoft Academic Search

Mandibular angular ostectomy defects in 12 sheep were bridged with a titanium plate system (THORP), designed according to the screw-plate-locking principle. Two screw designs (hollow and solid) and two rough (plasma-coated, sandblasted)-surface and one smooth (anodized)-surface structure were tested in a critical two-screw anchorage model. Fixation with two screws only per fragment was successful in only one-third of the cases.

Anna-Lisa Söderholm; Berton A. Rann; Kai Skutnabb; Christian Lindqvist

1996-01-01

358

The optimal transarticular c1-2 screw length and the location of the hypoglossal nerve  

Microsoft Academic Search

BACKGROUNDInjury to the hypoglossal nerve is a complication associated with transarticular C1-2 screw placement. This complication can be caused by a misdirected or too long screw. Little is known about the optimal screw length and its relationship to the hypoglossal nerve.METHODSTwenty cervical spine specimens were used to study the optimal length of the transarticular C1-2 screw. Using the Magerl technique,

Nabil A Ebraheim; Joseph R Misson; Rongming Xu; Richard A Yeasting

2000-01-01

359

Fiber inclination model for finite element analysis of three-dimensional angle interlock woven composite under ballistic penetration  

Microsoft Academic Search

A three-dimensional (3D) finite element model is created from finite element code LS-DYNA to simulate the ballistic penetration of a hemispherical cylindrical steel projectile into a 3D angle-interlock woven composite (3DAWC). ‘Fiber inclination model’ [Yang JM, Ma CL and Chou TW. Fiber inclination model of three-dimensional textile structural composites. J Compos Mater 1986; 20(9): 472—484] is employed to decompose the

Feng Cui; Baozhong Sun; Bohong Gu

2011-01-01

360

Kinematic Structure of Machines for Cutting Screws with a Variable Pitch  

Microsoft Academic Search

In some branches of the industry, for moving products subsequently subjected to required compaction and shaping, for example in production of plastic articles, screws with a variable pitch are used to ensure axially-directed compaction of the product. In general, in the process of manufacture of screws with a variable pitch, the actuating motion of the tool occurs along the screw

V. A. Vanin

2003-01-01

361

Defects in hexed gold prosthetic screws: A metallographic and tensile analysis  

Microsoft Academic Search

Statement of Problem. Prosthetic gold screw fracture remains a clinical problem in implant prosthodontics. Purpose. This study examined hexed gold prosthetic screws for internal defects and determined the effect of these defects on tensile strength. The microstructure, microhardness, and major constituents of the alloys also were determined. Material and Methods. Four intact hexed gold prosthetic screws, 1 from each of

Sameer K. Rambhia; William W. Nagy; Raymond A. Fournelle; Virendra B. Dhuru

2002-01-01

362

The effect of repeated torque on the ultimate tensile strength of slotted gold prosthetic screws  

Microsoft Academic Search

Statement of Problem. Repeated torque may alter the mechanical properties and fracture resistance of certain prosthetic retaining screws. Purpose. This study evaluated the effect of repeated torque and salivary contamination on the ultimate tensile strength of one type of slotted gold prosthetic retaining screw. Material and Methods. Forty-five slotted gold prosthetic screws from the same manufacturer (Implant Innovations) were divided

Mohammed A. Al Rafee; William W. Nagy; Raymond A. Fournelle; Virendra B. Dhuru; George K. Tzenakis; Charles E. Pechous

2002-01-01

363

A novel approach toward pedicle screw placement in the thoracic spine  

Microsoft Academic Search

Purpose of study: Because of the smaller size of the thoracic pedicle, primarily in the coronal plane, most surgeons have opted to avoid the used of transpedicular screws in the thoracic spine. A new technique for placement of screws through thoracic pedicles with and without lateral wall violation is described.Methods used: From April 1992 through February 1999, 1,064 pedicle screws

John Thalgott; Mark Kabins; James Giuffre

2002-01-01

364

Effect of an antirotation resistance form on screw loosening for single implant-supported crowns  

Microsoft Academic Search

Statement of problem: The gold screw of the single tooth implant-supported restoration has frequently been reported to exhibit the problem of screw loosening. Purpose: This in vitro study considered an antirotation resistance form with an increased moment arm length as a strategy to increase the net effect of the retaining screw preload. Material and methods: Three groups examined included (a)

Hoda Aboyoussef; Saul Weiner; David Ehrenberg

2000-01-01

365

Experimental determination of instantaneous screw axis in human motions. Error analysis  

Microsoft Academic Search

The location of the instantaneous screw axis (ISA) is essential in order to obtain useful kinematic models of the human body for applications such as prosthesis and orthoses design or even to help in disease diagnosis techniques. In this paper, dual vectors will be used to represent and operate with kinematic screws with the purpose of locating the instantaneous screw

Álvaro Page; Vicente Mata; Juan Víctor Hoyos; Rosa Porcar

2007-01-01

366

Failure Analysis of Ozark, Arkansas, Power Plant Socket-Head Cap Screws.  

National Technical Information Service (NTIS)

This research analyzed the socket-head cap screws which failed in the turbines of the Ozark Power Plant, Ozark, AR. The cause of failure was found to be fatigue in improperly heat-treated cap screws. The reduced fatigue strength of the cap screws was furt...

E. P. Cox

1976-01-01

367

Posterior thoracic segmental pedicle screw instrumentation: Evolving methods of safe and effective placement  

Microsoft Academic Search

The use of pedicle screw instrumentation in the spine has evolved over the last two decades. The initial use of pedicle screws began in the lumbar spine. As surgeons have become more comfortable with the complex anatomy required for accurate screw placement, the use of pedicle instrumentation has evolved to include their use in the thoracolumbar and thoracic spine. The

S. C. Zeiller; J. Lee; M. Lim; A. R. Vaccaro

2005-01-01

368

To retain or remove the syndesmotic screw: a review of literature  

Microsoft Academic Search

Introduction: Syndesmotic positioning screws are frequently placed in unstable ankle fractures. Many facets of adequate placement techniques have been the subject of various studies. Whether or not the syndesmosis screw should be removed prior to weight-bearing is still debated. In this study, the recent literature is reviewed concerning the need for removal of the syndesmotic screw. Materials and methods: A

T. Schepers

2010-01-01

369

A new approach in maxillary molar distalization: intraoral bodily molar distalizer.  

PubMed

The objectives of our study were to achieve bodily molar distalization, avoid distal tipping of molars, eliminate the need for patient cooperation (no headgear, no elastics, and no esthetic and social concern), and finally to minimize the treatment period and maximize the treatment efficiency. The study was carried out on 5 males and 10 females, a total of 15 patients. Mean age for the study group was 13.53 years. Dentally, all the patients had Class II molar relationship on both sides. The patients were in permanent dentition, second molars were erupted, and the lower dental arch was well aligned. Patients showed normal or sagittally directed growth pattern. Lateral cephalograms and study models were taken and analyzed before and after molar distalization. In the present study, in order to achieve maxillary molar distalization, a new intraoral appliance was developed. The intraoral bodily molar distalizer (IBMB) was composed of 2 parts: the anchorage unit and the distalizing unit. The anchorage unit was a wide Nance button, and the active unit consisted of distalizing springs. The springs had 2 components: the distalizer section of the spring applied a crown tipping force, while the uprighting section of the spring applied a root uprighting force on the first molars. A total of 230 g of distalizing force was used on both sides. After the distal movement of the first molars, the cephalometric results of 15 patients showed the following. Maxillary first molars were moved distally by an average of 5.23 mm (P <.001) without tipping or extrusion. Maxillary first premolars were moved 4.33 mm mesially (P <.001), tipped 2.73 degrees distally (P <.05), and extruded by 3.33 mm (P <.001). Maxillary central incisors were proclined by an average of 4.7 mm (P <.001) and tipped 6.73 degrees labially (P <.01). Model analysis showed that maxillary first molars were not rotated, and intermolar distance did not change after distal movement of molars. In conclusion, unlike most of the other molar distalization mechanics, this newly developed device achieved (1) bodily distal movement of maxillary molars and (2) eliminated dependence on patient cooperation and did not require headgear wear for molar root uprighting. PMID:10629518

Keles, A; Sayinsu, K

2000-01-01

370

Archaic and modern human distal humeral morphology.  

PubMed

The morphology of the proximal ulna has been shown to effectively differentiate archaic or premodern humans (such as Homo heidelbergensis and H. neanderthalensis) from modern humans (H. sapiens). Accordingly, the morphology of adjacent, articulating elements should be able to distinguish these two broad groups as well. Here we test the taxonomic utility of another portion of the elbow, the distal humerus, as a discriminator of archaic and modern humans. Principal components analysis was employed on a suite of log-raw and log-shape distal humeral measures to examine differences between Neandertal and modern human distal humeri. In addition, the morphological affinities of Broken Hill (Kabwe) E.898, an archaic human distal humeral fragment from the middle Pleistocene of Zambia, and five Pliocene and early Pleistocene australopith humeri were assessed. The morphometric analyses effectively differentiated the Neandertals from the other groups, while the Broken Hill humerus appears morphologically similar to modern human distal humeri. Thus, an archaic/modern human dichotomy-as previously reported for proximal ulnar morphology-is not supported with respect to distal humeral morphology. Relative to australopiths and modern humans, Neandertal humeri are characterized by large olecranon fossae and small distodorsal medial and lateral pillars. The seeming disparity in morphological affinities of proximal ulnae (in which all archaic human groups appear distinct from modern humans) and distal humeri (in which Neandertals appear distinct from modern humans, but other archaic humans do not) is probably indicative of a highly variable, possibly transitional population of which our knowledge is hampered by sample-size limitations imposed by the scarcity of middle-to-late Pleistocene premodern human fossils outside of Europe. PMID:16959299

Yokley, Todd R; Churchill, Steven E

2006-07-21

371

A bio-inspired swellable microneedle adhesive for mechanical interlocking with tissue  

NASA Astrophysics Data System (ADS)

Achieving significant adhesion to soft tissues while minimizing tissue damage poses a considerable clinical challenge. Chemical-based adhesives require tissue-specific reactive chemistry, typically inducing a significant inflammatory response. Staples are fraught with limitations including high-localized tissue stress and increased risk of infection, and nerve and blood vessel damage. Here inspired by the endoparasite Pomphorhynchus laevis, which swells its proboscis to attach to its host’s intestinal wall, we have developed a biphasic microneedle array that mechanically interlocks with tissue through swellable microneedle tips, achieving ~3.5-fold increase in adhesion strength compared with staples in skin graft fixation, and removal force of ~4.5?N?cm-2 from intestinal mucosal tissue. Comprising a poly(styrene)-block-poly(acrylic acid) swellable tip and non-swellable polystyrene core, conical microneedles penetrate tissue with minimal insertion force and depth, yet high adhesion strength in their swollen state. Uniquely, this design provides universal soft tissue adhesion with minimal damage, less traumatic removal, reduced risk of infection and delivery of bioactive therapeutics.

Yang, Seung Yun; O'Cearbhaill, Eoin D.; Sisk, Geoffroy C.; Park, Kyeng Min; Cho, Woo Kyung; Villiger, Martin; Bouma, Brett E.; Pomahac, Bohdan; Karp, Jeffrey M.

2013-04-01

372

Segmented instrumentation tube including a locking sleeve for interlocking the segments of the instrumentation tube  

DOEpatents

Segmented instrumentation tube including a locking sleeve for interlocking the segments of the instrumentation tube, so that the threaded ends of the instrumentation tube do not unthread when subjected to vibration, such an instrumentation tube being suitable for use in a nuclear reactor pressure vessel. The instrumentation tube has a first member having a threaded end portion that has a plurality of first holes circumferentially around the outside surface thereof. The instrumentation tube also has a second member having a threaded end portion that has a plurality of second holes circumferentially around the outside surface thereof. The threads of the second member are caused to threadably engage the threads of the first member for defining a threaded joint there between. A sleeve having an inside surface surrounds the end portion of the first member and the end portion of the second member and thus surrounds the threaded joint. The sleeve includes a plurality of first projections and second projections that outwardly extend from the inside surface to engage the first holes and the second holes, respectively. The outside surface of the sleeve is crimped or swaged at the locations of the first projections and second projections such that the first projections and the second projections engage their respective holes. In this manner, independent rotation of the first member with respect to the second member is prevented, so that the instrumentation tube will not unthread at its threaded joint. 10 figures.

Obermeyer, F.D.

1993-11-16

373

A Bio-Inspired Swellable Microneedle Adhesive for Mechanical Interlocking with Tissue  

PubMed Central

Achieving significant adhesion to soft tissues while minimizing tissue damage poses a considerable clinical challenge. Chemical-based adhesives require tissue-specific reactive chemistry, typically inducing a significant inflammatory response. Staples are fraught with limitations including high-localized tissue stress and increased risk of infection, and nerve and blood vessel damage. Here, inspired by the endoparasite Pomphorhynchus laevis which swells its proboscis to attach to its host’s intestinal wall, we have developed a biphasic microneedle array that mechanically interlocks with tissue through swellable microneedle tips, achieving ~ 3.5 fold increase in adhesion strength compared to staples in skin graft fixation, and removal force of ~ 4.5 N/cm2 from intestinal mucosal tissue. Comprising a poly(styrene)-block-poly(acrylic acid) swellable tip and non-swellable polystyrene core, conical microneedles penetrate tissue with minimal insertion force and depth, yet high adhesion strength in their swollen state. Uniquely, this design provides universal soft tissue adhesion with minimal damage, less traumatic removal, reduced risk of infection and delivery of bioactive therapeutics.

Yang, Seung Yun; O'Cearbhaill, Eoin D.; Sisk, Geoffroy C.; Park, Kyeng Min; Cho, Woo Kyung; Villiger, Martin; Bouma, Brett E.; Pomahac, Bohdan; Karp, Jeffrey M.

2013-01-01

374

The Contributions of Interlocking Loops and Extensive Nonlinearity to the Properties of Circadian Clock Models  

PubMed Central

Background Sensitivity and robustness are essential properties of circadian clock systems, enabling them to respond to the environment but resist noisy variations. These properties should be recapitulated in computational models of the circadian clock. Highly nonlinear kinetics and multiple loops are often incorporated into models to match experimental time-series data, but these also impact on model properties for clock models. Methodology/Principal Findings Here, we study the consequences of complicated structure and nonlinearity using simple Goodwin-type oscillators and the complex Arabidopsis circadian clock models. Sensitivity analysis of the simple oscillators implies that an interlocked multi-loop structure reinforces sensitivity/robustness properties, enhancing the response to external and internal variations. Furthermore, we found that reducing the degree of nonlinearity could sometimes enhance the robustness of models, implying that ad hoc incorporation of nonlinearity could be detrimental to a model's perceived credibility. Conclusion The correct multi-loop structure and degree of nonlinearity are therefore critical in contributing to the desired properties of a model as well as its capacity to match experimental data.

Saithong, Treenut; Painter, Kevin J.; Millar, Andrew J.

2010-01-01

375

Comparison of the differences in cephalometric parameters after active orthodontic treatment applying mini-screw implants or transpalatal arches in adult patients with bialveolar dental protrusion.  

PubMed

The purpose of this study was to compare the differences in cephalometric parameters after active orthodontic treatment applying mini-screw implants (G1) or transpalatal arches (G2) as anchorage in adult patients with bialveolar dental protrusion needing extraction of four premolars. A total of 34 Chinese patients (18-33 years) with bialveolar dental protrusion were randomly assigned to G1 and G2. Sliding mechanics and en-masse retraction of anterior teeth were applied to close extraction spaces. The changes in skeletal, dental and soft tissues were analyzed in both groups on lateral cephalograms before and after active orthodontic treatment. Independent samples and paired-samples t-tests were utilized to analyze the morphological changes in both groups. ANB angle was decreased in G1 and remained unchanged in G2 (P < 0.05). Upper incisors were retracted more in G1 than in G2 (P < 0.01). Upper incisors and molars were intruded in G1, but extruded in G2 (P < 0.01). Although the upper molars were found with no significant distalization (P > 0.05), there existed molars distalization in some patients. However, the maxillary molars in G2 were mesialized (P < 0.01). The intrusion of upper molars in G1 resulted in counterclockwise rotation of the mandible and decrease of SN-MP angle (P < 0.01). Upper lip linear measurements including UL-Y and UL-E were decreased more in G1 than in G2 (P < 0.05). Mini-screw implants provide absolute anchorage in vertical and sagittal directions. Better dental, skeletal and soft tissue changes could be achieved by mini-screw implants especially in hyperdivergent patients. Skeletal anchorage should be routinely recommended in patients with bialveolar dental protrusion. PMID:19602104

Liu, Y H; Ding, W H; Liu, J; Li, Q

2009-07-09

376

Benchtop comparison of a novel dynamic compression screw to a standard cortical screw: compression integrity and gap size over time during simulated resorption.  

PubMed

Literature reports the incidence of failed isolated foot and ankle fusions as up to 23%. A contributing factor is the natural bone resorption, which occurs resulting in loss of compression and gapping at the fusion site when standard static compression plates and screws are used. However, an innovative dynamic compression screw may provide lasting compression despite resorption. This benchtop study shows that the FxDEVICES spring-loaded dynamic POGO screw maintains more compression and more consistent compression rate during simulated resorption, as compared with a standard compression screw. The novel screw maintained much greater compression strength within the first millimeter of simulated resorption (13.57 vs 4.38 lb) and maintained greater compression strength at the test completion (1.14 vs 0 lb). The novel screw revealed a more consistent resorption rate over the duration of the simulation. Clinically, this may result in more stability and improved fusion rates. PMID:23548586

Kinmon, Kyle; Garzon, Desiree; Tacktill, Jordan; Vassello, Wayne

2013-04-02

377

Noimisothermal Model of Single Screw Extrusion of Generalized Newtonian Fluids  

Microsoft Academic Search

A nonisothermal model of Ike single screw extrusion processing of generalized Newtonian fluids is presented. Various temperature dependent forms of a generalized Newtonian fluid constitutive equation representing the Herschel-Bulkley fluid and its simplifications, including Bingham plastic, power law of Ostwald-de Waele, and Newtonian fluids, are applicable. The model includes the generally ignored transverse convection terms of the equation of energy.

Adeniyi Lawal; Dilhan M. Kalyon

1994-01-01

378

Cellulose and the twofold screw axis: Modeling and experimental arguments  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crystallography indicates that molecules in crystalline cellulose either have 2-fold screw-axis (21) symmetry or closely approximate it, leading to short distances between H4 and H1' across the glycosidic linkage. Therefore, modeling studies of cellobiose often show elevated energies for 21 structur...

379

Primary thoracoplasty and pedicle screw instrumentation in thoracic idiopathic scoliosis  

Microsoft Academic Search

Thoracoplasty in combination with spine fusion is an established method to address the rib cage deformity in idiopathic scoliosis. Most reports about thoracoplasty and scoliosis correction focused on Harrington or CD instrumentation. We report a retrospective analysis of 21 consecutive patients, who were treated with pedicle screw instrumentation for idiopathic thoracic scoliosis and concomitant thoracoplasty. Minimal follow up was 24

Kan Min; Beat Waelchli; Frederik Hahn

2005-01-01

380

Fuzzy Sliding Mode Control of a Ball Screw Driven Stage  

Microsoft Academic Search

Ball screw driven systems are widely used for motion control applications. In such systems, friction dominates the resulting performance and it should be compensated to achieve high precision in positioning and tracking. Hereby a friction model is introduced to describe dynamic behavior of the system and then three control strategies i.e. sliding mode control (SMC), complementary sliding mode control (CSMC)

M. Shams; M. Zarei-nejad; M. Safdari

2008-01-01

381

39. VIEW OF VESSEL STERNON IN DRYDOCK. NOTE TWIN SCREWS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

39. VIEW OF VESSEL STERN-ON IN DRYDOCK. NOTE TWIN SCREWS AND RUDDER. GENTLEMEN IN VIEW UNKNOWN Original 5'x5' photograph taken by Robert S. Douglas in 1966 - Pilot Schooner "Alabama", Moored in harbor at Vineyard Haven, Vineyard Haven, Dukes County, MA

382

Dynamics of parallel manipulators by means of screw theory  

Microsoft Academic Search

An approach to the dynamic analysis of parallel manipulators is presented. The proposed method, based on the theory of screws and on the principle of virtual work, allows a straightforward calculation of the actuator forces as a function of the external applied forces and the imposed trajectory. In order to show the generality of such a methodology, two case studies

J. Gallardo; J. M. Rico; A. Frisoli; D. Checcacci; M. Bergamasco

2003-01-01

383

Throttling means for geothermal streams. [helical screw expander  

Microsoft Academic Search

A helical screw expander for deriving energy from geothermally heated water is described. The expander includes a pair of helical rotors with helical structures fitted in an expansion chamber. The geothermally heated water is introduced into said chamber through a throttle port located at an end face of the expansion chamber, whereby precipitation which occurs as a consequence of reduction

Sprankle

1976-01-01

384

Bone registration method for robot assisted surgery: pedicle screw insertion  

Microsoft Academic Search

SUMMARY A registration method that identifies bone geometry with respect to a robotic manipulator arm is presented. Although the method is generally applicable to many orthopaedic internal fixation, it was only demonstrated for the insertion of pedicle screws in vertebral bodies for spine fixation. The method relies upon obtaining an impression of the vertebral bodies. Computed Tomography scans of both

K Abdel-Malek; D P McGowan; V K Goel; D Kowalski; A Hager

1997-01-01

385

INTERIOR VIEW OF JAMES HARRIS CUTTING SCREW THREADS INTO THE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

INTERIOR VIEW OF JAMES HARRIS CUTTING SCREW THREADS INTO THE INTERIOR OF FITTINGS ON ONE IN A BANK OF TAPPING MACHINES, EACH OPERATED BY THE SAME WORKER SIMULTANEOUSLY BUT TIMED TO REQUIRE WORKER ACTION AT INTERVALS THAT DO NOT INTERFERE WITH THE OTHER MACHINES. - Stockham Pipe & Fittings Company, Tapping Room, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

386

Plate and screw fixation for atlanto-axial subluxation  

Microsoft Academic Search

Summary Our experience with 30 cases of atlanto-axial dislocation, over the period of 3 years and 9 months, is described. A modified plate and screw method of fixation of the lateral masses of the atlas and axis was successfully used in these cases. The technical aspects and merits of the method, wherein a 100% union rate was achieved, with no

A. Goel; V. Laheri

1994-01-01

387

Stress Reduction at the Production of Bottle-Cap Screws.  

National Technical Information Service (NTIS)

To seal contents gastight on a large scale aluminium cap screws are produced on production lines where in a full extent stress at the operating positions is a fact harmful vapors, heat and other factors injurious to health. Only with new engineering the p...

V. Schach H. Schach H. Haeufgloeckner

1982-01-01

388

The Use of Small Titanium Screws for Orthodontic Anchorage  

Microsoft Academic Search

The use of conventional dental implants for orthodontic anchorage is limited by their large size. The purpose of this study was to quantify the histomorphometric properties of the bone-implant interface to analyze the use of small titanium screws as an orthodontic anchorage and to establish an adequate healing period. Overall, successful rigid osseous fixation was achieved by 97% of the

T. Deguchi; T. Takano-Yamamoto; R. Kanomi; J. K. Hartsfield; W. E. Roberts; L. P. Garetto

2003-01-01

389

Biomechanical comparison of two headless compression screws for scaphoid fixation.  

PubMed

This study compared compression generation between two headless compression screws: the Synthes 3.0-mm and the Acutrak standard. Twenty scaphoids were harvested from 10 pairs of fresh cadaveric forearms. A washer-shaped load cell was inserted between the halves of each scaphoid created by a simulated fracture via osteotomy. One scaphoid of each pair was tested with the Synthes and the other with the Acutrak. Parameters of interest were peak screw torque and fracture site compression. Differences in parameters of interest were checked for significance (p < .05) with paired t tests. No significant differences were shown in mean (+/- standard deviation) peak torque (57 +/- 28 Ncm vs. 55 +/- 32 Ncm; p < .84), compression immediately after insertion (119 +/- 54 N vs. 91 +/- 37 N; p < .15), or compression 5 min after insertion (32 +/- 30 N vs. 38 +/- 24 N; p < .61) between the Synthes and Acutrak screw fixations, respectively. The choice between these two screws to stabilize scaphoid waist fractures should be based on parameters other than compression generation, such as size, availability, cost, and ease of use of the implant. PMID:19995497

Pensy, Raymond A; Richards, Andrew M; Belkoff, Stephen M; Mentzer, Kurt; Andrew Eglseder, W

2009-01-01

390

Outpatient percutaneous screw fixation of the acute Jones fracture  

Microsoft Academic Search

Nine patients (8 men and 1 woman, ranging in age from 17 to 22 years) who sustained a Jones fracture were treated with percutaneous intramedullary screw fixation as outpatients. All of the patients were varsity athletes. Seven were Division I scholarship athletes. Beginning at 7 to 10 days after surgery, all patients were allowed weightbearing as tolerated with a CAM

Norman Mindrebo; K. Donald Shelbourne; Charles D. Van Meter; Arthur C. Rettig

1993-01-01

391

Complications with K-wire Insertion for Percutaneous Pedicle Screws.  

PubMed

STUDY DESIGN:: Retrospective Study. OBJECTIVE:: To determine the risk profile and complications associated with anterior vertebral body breach by K-wire during percutaneous pedicle screw insertion. SUMMARY OF BACKGROUND DATA:: Percutaneous techniques and indications are rapidly expanding with numerous studies now supporting the use of percutaneous pedicle screw stabilisation as an adjunct for multiple pathologies such as degenerative, tumour and trauma. With regards to complication rates, little has been documented. METHODS:: 525 consecutive percutaneous pedicle screws were retrospectively reviewed and the rate of anterior vertebral body breach was recorded, including any potential adverse clinical outcomes. RESULTS:: Of 525 percutaneous pedicle screw insertions, there were 7 anterior breaches recorded. We rated the breaches as a minor breach (<5 mm; n=3), moderate breach (5-25 mm; n=2) and major breach (>25 mm; n=2). Two patients had a postoperative ileus with a retroperitoneal haematoma on post-op CT scan. No patient required reoperation or blood transfusion. CONCLUSION:: The indications for minimally invasive spinal fusion have expanded to include conditions such as degenerative, trauma, deformity, infection and neoplasia. While the rate of anterior K-wire breach is low, the technique requires the acquisition of a new set of skills including the safe passage of a K-wire, and knowledge of potential complications that may ensue. PMID:23698104

Mobbs, Ralph J; Raley, Darryl A

2013-05-22

392

Gas Expansion Motor with Screw-Type Air Compressor.  

National Technical Information Service (NTIS)

This pilot project in the field of energy conversion aims to utilize the unused exergetic gradient in the gas fed into the furnaces of a glass fabrication plant by means of a gas expansion motor which drives a screw-type compressor. The experiences gained...

H. B. Fuehr

1983-01-01

393

Stability of two-fold screw axis structures for cellulose  

Technology Transfer Automated Retrieval System (TEKTRAN)

Diffraction crystallography indicates that most forms of crystalline cellulose have two-fold screw axis symmetry. Even if exact symmetry is absent, the degree of pseudo symmetry is very high. On the other hand, this symmetry leads to short contacts between H4 and H1' across the glycosidic linkage....

394

Two Turns of the Screw: Feminism and the Humanities.  

ERIC Educational Resources Information Center

Maintains that the humanities get "screwed" in the academy because they are feminized. Explores this process of "feminization," focusing on college English departments. Offers a different view of the relationship between "soft" humanities and "hard" disciplines, reconceived from a feminist perspective. (SR)

Heinzelman, Susan Sage

1988-01-01

395

Screw dislocation in zirconium: An ab initio study  

NASA Astrophysics Data System (ADS)

Plasticity in zirconium is controlled by 1/3<12¯10> screw dislocations gliding in the prism planes of the hexagonal close-packed structure. This prismatic and not basal glide is observed for a given set of transition metals like zirconium and is known to be related to the number of valence electrons in the d band. We use ab initio calculations based on the density functional theory to study the core structure of screw dislocations in zirconium. Dislocations are found to dissociate in the prism plane in two partial dislocations, each with a pure screw character. Ab initio calculations also show that the dissociation in the basal plane is unstable. We calculate then the Peierls barrier for a screw dislocation gliding in the prism plane and obtain a small barrier. The Peierls stress deduced from this barrier is lower than 21 MPa, which is in agreement with experimental data. The ability of an empirical potential relying on the embedded atom method (EAM) to model dislocations in zirconium is also tested against these ab initio calculations.

Clouet, Emmanuel

2012-10-01

396

A new approach in maxillary molar distalization: Intraoral bodily molar distalizer  

Microsoft Academic Search

The objectives of our study were to achieve bodily molar distalization, avoid distal tipping of molars, eliminate the need for patient cooperation (no headgear, no elastics, and no esthetic and social concern), and finally to minimize the treatment period and maximize the treatment efficiency. The study was carried out on 5 males and 10 females, a total of 15 patients.

Ahmet Keles; Korkmaz Sayinsu

2000-01-01

397

Factors affecting the accurate placement of percutaneous pedicle screws during minimally invasive transforaminal lumbar interbody fusion.  

PubMed

We retrospectively evaluated 488 percutaneous pedicle screws in 110 consecutive patients that had undergone minimally invasive transforaminal lumbar interbody fusion (MITLIF) to determine the incidence of pedicle screw misplacement and its relevant risk factors. Screw placements were classified based on postoperative computed tomographic findings as "correct", "cortical encroachment" or as "frank penetration". Age, gender, body mass index, bone mineral density, diagnosis, operation time, estimated blood loss (EBL), level of fusion, surgeon's position, spinal alignment, quality/quantity of multifidus muscle, and depth to screw entry point were considered to be demographic and anatomical variables capable of affecting pedicle screw placement. Pedicle dimensions, facet joint arthritis, screw location (ipsilateral or contralateral), screw length, screw diameter, and screw trajectory angle were regarded as screw-related variables. Logistic regression analysis was conducted to examine relations between these variables and the correctness of screw placement. The incidence of cortical encroachment was 12.5% (61 screws), and frank penetration was found for 54 (11.1%) screws. Two patients (0.4%) with medial penetration underwent revision for unbearable radicular pain and foot drop, respectively. The odds ratios of significant risk factors for pedicle screw misplacement were 3.373 (95% CI 1.095-10.391) for obesity, 1.141 (95% CI 1.024-1.271) for pedicle convergent angle, 1.013 (95% CI 1.006-1.065) for EBL >400 cc, and 1.003 (95% CI 1.000-1.006) for cross-sectional area of multifidus muscle. Although percutaneous insertion of pedicle screws was performed safely during MITLIF, several risk factors should be considered to improve placement accuracy. PMID:21720727

Kim, Moon-Chan; Chung, Hung-Tae; Cho, Jae-Lim; Kim, Dong-Jun; Chung, Nam-Su

2011-07-01

398

Complications After Open Distal Clavicle Excision  

PubMed Central

Isolated distal clavicle excision performed as an open procedure has been considered safe and, in the literature, has been considered the standard for comparison with arthroscopic distal clavicle excisions. However, we noticed isolated open distal clavicle excision was associated with a number of complications. We therefore raised two questions about the complication rate in a cohort of our patients who had undergone this procedure: (1) What was the complication rate and how did it compare to that in the existing literature on this subject? and (2) Were the complications in our cohort similar to those previously reported? We studied 42 patients who underwent an isolated distal clavicle excision between 1992 and 2003. There were 27 complications (64%), which was substantially higher than rates previously reported. Complications in our cohort not previously reported included continued acromioclavicular joint tenderness and scar hypertrophy. Our study suggests complications after open distal clavicle excisions may be more frequent than and may differ from previously reported rates and types. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Chronopoulos, Efstathis; Gill, Harpreet S.; Freehill, Michael T.; Petersen, Steve A.

2008-01-01

399

Placement of pedicle screws in thoracic idiopathic scoliosis: a magnetic resonance imaging analysis of screw placement relative to structures at risk  

Microsoft Academic Search

In posterior pedicle screw instrumentation of thoracic idiopathic scoliosis, screw malposition might cause significant morbidity\\u000a in tems of possible pleural, spinal cord, and aorta injury. Preoperative axial magnetic resonace images (MRI) in 12 consecutive\\u000a patients with right thoracic adolescent scoliosis, all with King type 3 curves, were analyzed in order to evaluate the relationship\\u000a between the inserted pedicle screw position

Ahmet Y?lmaz ?arlak; Levent Buluç; Hasan Tahsin Sar?soy; Kaya Memi?o?lu; Bilgehan Tosun

2008-01-01

400

Role of rod diameter in comparison between only screws versus hooks and screws in posterior instrumentation of thoracic curve in idiopathic scoliosis.  

PubMed

Since the introduction of Cotrel-Dubousset instrumentation in 1984, the correction techniques in scoliosis surgery have changed from Harrington principles of concave distraction to segmental realignment to a variety of possibilities including the rod rotation manoeuvres, and to segmental approximation via cantilever methods. Additionally, pedicle screw utilization in lumbar curves enhanced correction and stabilization of various deformities, and various studies have strongly supported the clinical advantages of lumbar pedicle screws versus conventional hook instrumentation. Pedicle screw constructs have become increasingly popular in the treatment of patients with spinal deformity. When applied to adolescent idiopathic scoliosis patients, pedicle screw fixation has demonstrated increased corrective ability compared with traditional hook/hybrid instrumentation. In our study, we do a retrospective review of idiopathic scoliosis patients (King 2-Lenke 1 B/C) treated with a selective thoracic posterior fusion using an all-screw construct versus a hybrid (pedicle screws and hooks) construct and, compare the percentage of correction of the scoliotic curves obtained with screws alone and screws and hooks. Special attention was given to the rod diameter and correction technique. Our results show that the percentage of correction of idiopathic thoracic scoliosis is similar when treating the scoliosis with rods and screws alone or with rods, screws and hooks; therefore, we and the majority of authors in the literature do not consider the rod section. This can be an important parameter in the evaluation of the superiority of treatment with screws only or screws and hooks. In our study, even if not of statistical significance, the better thoracic curve correction obtained with the hybrid group should be ascribed to the fact that in this group mostly 6 mm rods were used. PMID:21416281

Lamartina, Claudio; Petruzzi, Maria; Macchia, Marcello; Stradiotti, Paola; Zerbi, Alberto

2011-03-17

401

Comparison of stability of mandibular segments following the sagittal split ramus osteotomy with poly- l-lactic acid (PLLA) screws and titanium screws fixation  

Microsoft Academic Search

The purpose of this study was to retrospectively compare the stability of the mandible following the surgical orthodontic treatment by sagittal split ramus osteotomy (SSRO) and orthodontic multi-bracket treatment using fixation methods with poly-l-lactic acid (PLLA) or titanium screws. The sample examined was 23 subjects with PLLA screws (PLLA group) and 22 subjects with titanium screws (Titan group). Lateral cephalometric

Yasuo Oba; Akihiro Yasue; Kazuyuki Kaneko; Ryoko Uchida; Atsushi Shioyasono; Keiji Moriyama

2008-01-01

402

Long-term stability of angle-stable versus conventional locked intramedullary nails in distal tibia fractures  

PubMed Central

Background In the last years intramedullary nailing has become the treatment of choice for most displaced diaphyseal tibia fractures. In contrast intramedullary nailing of distal tibia fractures is accompanied by problems like decreased biomechanical stability. Nevertheless the indications for intramedullary nailing have been extended to include even more distal fractures. The purpose of this study was to compare long-term mechanical characteristics of angle-stable versus conventional locked intramedullary nails in the treatment of unstable distal tibia fractures. Therefore, the effect of time on the mechanical properties of biodegradable sleeves was assessed. Methods 8 pairs of fresh, frozen porcine tibiae were used. The expert tibial nail (Synthes) was equipped with either three conventional locking screws (CL) or the angle-stable locking system (AS), consisting of a special ASLS screw and a biodegradable sleeve. Biomechanical testing included torsional and axial loading at different time-points over 12 weeks. Results The AS group showed a significantly higher torsional stiffness at all time-points (at least 60%) compared to the CL group (p??0.05). For axial stiffness and range of motion significant differences were found in the AS group. Conclusions The angle-stable locking system (ASLS) with the biodegradable sleeve provides significantly higher long-term stability. Especially the differences determined under torsional loading in this study may have clinical relevance. The ASLS permits the potential to decrease complications like secondary loss of reduction and mal-/non-union.

2013-01-01

403

Risk Factors for Failure of Locked Plate Fixation of Distal Femur Fractures: An Analysis of 335 Cases.  

PubMed

OBJECTIVES:: Locked plating has become a standard method to treat supracondylar femur fractures. Emerging evidence indicates this method of treatment is associated with modest failure rates. The goals of this study were to determine risk factors for complications and to provide technical recommendations for locked plating of supracondylar femur fractures. DESIGN:: Retrospective review SETTING:: Three Level I or II Trauma Centers PATIENTS/PARTICIPANTS:: Three-hundred twenty-six patients with 335 distal femur fractures (OTA 33A or C, 33% open) treated with lateral locked plates were studied. The average patient age was 57 years (range 17 - 97 years), 55% were female, 34% obese, 19% diabetic, and 24% smokers. INTERVENTION:: All patients were managed with open reduction internal fixation (ORIF) using a lateral distal femoral locked plate construct that included locked screws in the distal fragment and either non-locked, locked or a combination of locked and non-locked screws in the proximal fragment. MAIN OUTCOME MEASUREMENTS:: Risk factors for re-operation to promote union, deep infection, and implant failure. RESULTS:: After the index procedure, 64 fractures (19%) required re-operation to promote union, including 30 that had a planned staged bone grafting due to metaphyseal defect after debridement of an open fracture. Independent risk factors for re-operation to promote union and deep infection included diabetes and open fracture. Risk factors for proximal implant failure included open fracture, smoking, increased body mass index, and shorter plate length. CONCLUSIONS:: The identified risk factors for re-operation to promote union and complications included open fracture, diabetes, smoking, increased body mass index, and shorter plate length. The majority of these factors are out of surgeon control, but are useful when considering prognosis. Use of relatively long plates is a technical factor that can reduce risk for fixation failure. PMID:23760176

Ricci, William M; Streubel, Philipp N; Morshed, Saam; Collinge, Cory; Nork, Sean E; Gardner, Michael J

2013-06-11

404

Three-dimensional bimetric maxillary distalization arches compared with a modified Begg intraoral distalization system.  

PubMed

The purpose of this study was to compare the dentofacial effects of two intraoral molar distalization techniques [three-dimensional bimetric maxillary distalization arches (3D-BMDA) and a modified Begg intraoral distalization system (MBIDS)] in subjects requiring maxillary molar distalization. Twenty-one patients (12 females and 9 males, mean age pre-treatment: 14.7 +/- 1.50 years) were treated with the 3D-BMDA and 17 (14 females and 3 males, mean age pre-treatment: 14.4 +/- 1.43 years) with the MBIDS. Measurements were recorded from lateral cephalometric radiographs taken at two different points in time: at the start of treatment for the MBIDS group and prior to distalization for the 3D-BMDA group (T1) and post-distalization (T2). Student's t- and paired t-tests were used to determine differences between and within the groups. The total amount of distalization for the 3D-BMDA and MBIDS groups was similar (3.55 and 3.27 mm, respectively). However, there were statistically significant differences in the length of the distalization period (3.4 and 6.5 months, respectively) and the amount monthly of distalization (1.11 and 0.54 mm, respectively). The most significant differences were observed in the mandibular dental arches and vertical facial dimensions. Anchorage loss in the mandible was greater in the 3D-BMDA group, whereas increases in facial dimensions were greater in the MBIDS group. Both 3D-BMDA and MBIDS techniques were found to be effective to obtain distal movement of the maxillary molars. In order to achieve successful results, the side-effects of each treatment modality on dentofacial structures need to be taken into consideration. PMID:17947349

Altug-Atac, Ayse Tuba; Erdem, Dilek; Arat, Züleyha Mirzen

2007-10-18

405

Distal tibiofibular ligaments. Analysis of function.  

PubMed

The function of the anterior tibiofibular ligament, of the syndesmosis between the distal parts of the tibia and fibula, and of the posterior tibiofibular ligament was elucidated by tracing mobility patterns before and after successive ligament transection in varying sequence. Eighteen osteoligamentous preparations were studied. Mobility was only minimally influenced by isolated cutting of the anterior tibiofibular ligament, and even complete cutting of the distal tibiofibular ligaments involved only minor abnormality in motion. However, external rotation was greatly increased by further cutting of the anterior part of the deltoid ligament or of the posterior talofibular ligament. This indicates that isolated injury of the anterior tibiofibular ligament must be rare, and total rupture of the distal tibiofibular structures is presumably as a rule combined with lesions of the anterior part of the deltoid ligament and/or of the posterior talofibular ligament. PMID:7102288

Rasmussen, O; Tovborg-Jensen, I; Boe, S

1982-08-01

406

Osteochondritis of the Distal Tibial Epiphysis  

PubMed Central

Osteochondritis of the distal tibial epiphysis is a very rare entity. 9 cases have been described in 7 articles and 8 other cases have been mentioned in textbooks. This paper describes the 10th case of osteochondritis of the distal tibial epiphysis and summarizes the clinical and radiological presentations of the 9 other cases. The etiology of this entity is well debated in the literature. We believe that it results from a vascular abnormality in the distal tibial epiphysis associated with a mechanical stress (trauma, excessive overload, etc.). Since it is a self-limited disease, the prognosis is good and the younger the patient is the better the prognosis will be. In general, this entity responds well to conservative treatment.

EL Hajj, Firass; Sebaaly, Amer; Kharrat, Khalil; Ghanem, Ismat

2012-01-01

407

Comparative study of ankle arthrodesis using cross screw fixation versus anterior contoured plate plus cross screw fixation.  

PubMed

Arthrodesis of the ankle joint is still the traditional treatment for symptomatic osteoarthritis. This comparative study was done to assess the functional outcome of open ankle fusion using either cross screw fixation (group A) or anterior contoured plate and cross screw fixation (group B) in a consecutive series of 22 patients. All the patients had the same inclusion criteria. All the patients in both groups underwent the same operative technique and were operated by the same surgeon. Mean follow-up was 26.8 months. The mean time to fusion was 18.8 weeks in group A and 16.8 weeks in group B (p = 0.046). The mean American Orthopaedic Foot and Ankle Society (AOFAS) Ankle and Hind foot score at the final follow-up was 79 in group A and 86 in group B (p = 0.23). Two patients in group A that went to non-union required re-arthrodesis using contoured plate and cross screw fixation; both attained eventual union. We conclude that anterior contoured plate plus cross screw fixation is a simple and reproducible technique for ankle arthrodesis that gives stable internal fixation and excellent clinical results. PMID:17260609

Kakarala, Gopikrishna; Rajan, Daniel T

2006-12-01

408

Bioresorbable screws reinforced with phosphate glass fibre: manufacturing and mechanical property characterisation.  

PubMed

Use of bioresorbable screws could eliminate disadvantages associated with metals such as removal operations, corrosion, MRI interference and stress shielding. Mechanical properties of bioresorbable polymers alone are insufficient for load bearing applications application as screws. Thus, reinforcement is necessary to try and match or surpass the mechanical properties of cortical bone. Phosphate based glass fibres were used to reinforce polylactic acid (PLA) in order to produce unidirectionally aligned (UD) and unidirectionally plus randomly distributed (UD/RM) composite screws (P40 UD and P40 UD/RM). The maximum flexural and push-out properties for the composite screws (P40 UD and P40 UD/RM) increased by almost 100% in comparison with the PLA screws. While the pull-out strength and stiffness of the headless composite screws were ?80% (strength) and ?130% (stiffness) higher than for PLA, those with heads exhibited properties lower than those for PLA alone as a result of failure at the heads. An increase in the maximum shear load and stiffness for the composite screws (?30% and ?40%) in comparison to the PLA screws was also seen. Maximum torque for the PLA screws was ?1000 mN m, while that for the composite screws were slightly lower. The SEM micrographs for P40 UD and P40 UD/RM screws revealed small gaps around the fibres, which were suggested to be due to buckling of the UD fibres during the manufacturing process. PMID:23122715

Felfel, R M; Ahmed, I; Parsons, A J; Rudd, C D

2012-08-21

409

Management of malunions of the distal radius.  

PubMed

Despite encouraging results from small case series, correction of distal radius malunion remains a challenging procedure with uncertain outcomes. The most appropriate treatment for a distal radius malunion is prevention. If a symptomatic malunion is discovered, correction should be undertaken as early as possible. It is recommended that action be taken within six months of the primary injury to decrease the negative impact of soft-tissue contracture on the eventual reconstruction. Although some patients complain about residual problems after malunion surgery, corrective surgery has been shown to improve both radiographic and functional outcomes, and may prevent future secondary problems. PMID:22554664

Haase, Steven C; Chung, Kevin C

2012-04-13

410

Triplication of distal chromosome 10q  

PubMed Central

We describe a patient with a de novo chromosomal aberration with karyotype 46,XY,10q+, presenting clinical features of partial duplication of distal chromosome 10q. Further studies using microsatellites and FISH showed a triplication of distal chromosome 10q. The rearrangement involved both maternal homologues and the middle chromosomal 10q fragment of the triplication was inverted, similar to previously reported chromosomal triplications. Chromosomal triplications may be more frequent than assumed and may share a common molecular mechanism.???Keywords: chromosome 10q; triplication; FISH; cytogenetics

Devriendt, K.; Matthijs, G.; Holvoet, M.; Schoenmakers, E.; Fryns, J.

1999-01-01

411

Ca(2+)-sensors and ROS-GC: interlocked sensory transduction elements: a review.  

PubMed

From its initial discovery that ROS-GC membrane guanylate cyclase is a mono-modal Ca(2+)-transduction system linked exclusively with the photo-transduction machinery to the successive finding that it embodies a remarkable bimodal Ca(2+) signaling device, its widened transduction role in the general signaling mechanisms of the sensory neuron cells was envisioned. A theoretical concept was proposed where Ca(2+)-modulates ROS-GC through its generated cyclic GMP via a nearby cyclic nucleotide gated channel and creates a hyper- or depolarized sate in the neuron membrane (Ca(2+) Binding Proteins 1:1, 7-11, 2006). The generated electric potential then becomes a mode of transmission of the parent [Ca(2+)](i) signal. Ca(2+) and ROS-GC are interlocked messengers in multiple sensory transduction mechanisms. This comprehensive review discusses the developmental stages to the present status of this concept and demonstrates how neuronal Ca(2+)-sensor (NCS) proteins are the interconnected elements of this elegant ROS-GC transduction system. The focus is on the dynamism of the structural composition of this system, and how it accommodates selectivity and elasticity for the Ca(2+) signals to perform multiple tasks linked with the SENSES of vision, smell, and possibly of taste and the pineal gland. An intriguing illustration is provided for the Ca(2+) sensor GCAP1 which displays its remarkable ability for its flexibility in function from being a photoreceptor sensor to an odorant receptor sensor. In doing so it reverses its function from an inhibitor of ROS-GC to the stimulator of ONE-GC membrane guanylate cyclase. PMID:22509149

Sharma, Rameshwar K; Duda, Teresa

2012-04-09

412

Pullout strength of anterior spinal instrumentation: a product comparison of seven screws in calf vertebral bodies  

PubMed Central

A lot of new implant devices for spine surgery are coming onto the market, in which vertebral screws play a fundamental role. The new screws developed for surgery of spine deformities have to be compared to established systems. A biomechanical in vitro study was designed to assess the bone–screw interface fixation strength of seven different screws used for correction of scoliosis in spine surgery. The objectives of the current study were twofold: (1) to evaluate the initial strength at the bone–screw interface of newly developed vertebral screws (Universal Spine System II) compared to established systems (product comparison) and (2) to evaluate the influence of screw design, screw diameter, screw length and bone mineral density on pullout strength. Fifty-six calf vertebral bodies were instrumented with seven different screws (USS II anterior 8.0 mm, USS II posterior 6.2 mm, KASS 6.25 mm, USS II anterior 6.2 mm, USS II posterior 5.2 mm, USS 6.0 mm, USS 5.0 mm). Bone mineral density (BMD) was determined by quantitative computed tomography (QCT). Failure in axial pullout was tested using a displacement-controlled universal test machine. USS II anterior 8.0 mm showed higher pullout strength than all other screws. The difference constituted a tendency (P = 0.108) when compared to USS II posterior 6.2 mm (+19%) and was significant in comparison to the other screws (+30 to +55%, P < 0.002). USS II posterior 6.2 mm showed significantly higher pullout strength than USS 5.0 mm (+30%, P = 0.014). The other screws did not differ significantly in pullout strength. Pullout strength correlated significantly with BMD (P = 0.0015) and vertebral body width/screw length (P < 0.001). The newly developed screws for spine surgery (USS II) show higher pullout strength when compared to established systems. Screw design had no significant influence on pullout force in vertebral body screws, but outer diameter of the screw, screw length and BMD are good predictors of pullout resistance.

Wahl, Dieter; Wild, Alexander; Krauspe, Rudiger; Schneider, Erich; Linke, Berend

2007-01-01

413

Distally based dorsalis pedis island flap for a distal lateral electric burn of the big toe.  

PubMed

Reconstruction of the small defects in the distal portion of the foot has always represented a difficult problem. A case of a young man with a deep electric burn of the distal lateral side of the big toe successfully treated with a distally based dorsalis pedis island flap based on the first dorsal metatarsal artery (FDMA) is presented. The donor site area of the dorsum of the foot was grafted, and deambulation was reassumed 3 weeks later. Advantages; limits and anatomical consideration regarding the viability of the flap are also discussed. PMID:8982547

Governa, M; Barisoni, D

1996-12-01

414

Partial rupture of the distal biceps tendon  

Microsoft Academic Search

We report on 7 cases of partial rupture of the distal biceps tendon. The mean patient age was 52 years (range, 38-58 years). There were 5 men and 2 women. The dominant arm was affected in all 7 patients. Pain was the chief complaint in all patients. Immobilization and physiotherapy were attempted in all patients, and 4 had at least

Dimitris G. Vardakas; Douglas S. Musgrave; Sokratis E. Varitimidis; Felix Goebel; Dean G. Sotereanos

2001-01-01

415

Molar distalization with the Herbst appliance  

Microsoft Academic Search

This article reviews the dental effects of the Herbst appliance as well as itslong-term effects on the dentition. The Herbst appliance exhibits a pronounced high-pull headgear effect on the maxillary molars. Without retention, the molars tend to return to their former anteroposterior positions after the removal of the appliance. These distal movements of the maxillary molars are favorable in Class

Meson Lai

2000-01-01

416

Distal Xq duplication and functional Xq disomy  

Microsoft Academic Search

Distal Xq duplications refer to chromosomal disorders resulting from involvement of the long arm of the X chromosome (Xq). Clinical manifestations widely vary depending on the gender of the patient and on the gene content of the duplicated segment. Prevalence of Xq duplications remains unknown. About 40 cases of Xq28 functional disomy due to cytogenetically visible rearrangements, and about 50

Damien Sanlaville; Caroline Schluth-Bolard; Catherine Turleau

2009-01-01

417

Triplane fracture of the distal tibia  

Microsoft Academic Search

A prospective study of 21 triplane fractures of the distal tibia is presented. Nineteen cases (90.5%) had lateral triplane fractures, while the other two (9.5%) had medial triplane fractures. Two fragment fractures were encountered in 12 cases (57%); three fragment fractures in six cases (29%), and four fragment fractures in the remaining three cases (14%). Fourteen cases (67%) were managed

E. El-Karef; H. I. Sadek; D. S. Nairn; C. H. Aldam; P. W. Allen

2000-01-01

418

Distal Airway Impairment in Obese Normoreactive Women  

PubMed Central

Background. Asthma-like symptoms are frequent in overweight and obesity, but the mechanism is unclear when airway hyperresponsiveness (AHR) is lacking. In this study, we focused on obese women with a clinical suspicion of asthma but negative methacholine challenge and tested distal airway hyperreactivity, explored by Forced Vital Capacity dose-response slope (FVC DRS). Objective. To question AHR at the distal airway level in obese women. Methods. A total of 293 symptomatic obese and nonobese women free of treatment were investigated. Methacholine challenge tests were undertaken, and patients were divided according to their results to the test. In hyperreactive and nonhyperreactive patients and in our total population, correlations, regression analyses, and analyses of covariance were performed to compare distal airway hyperreactivity in three groups of body mass index (BMI). Results. After adjusting for age and baseline respiratory values, the relationship between FVC and FEV1 (forced expiratory volume in one second) DRS was influenced by BMI, with a lower slope in obese than overweight and normal patients in our total population (P = 0.008) and in our nonhyperreactive one (P = 0.028). Conclusion. Distal airway hyperresponsiveness was observed in symptomatic wheezing obese women negative to methacholine challenge.

Marin, Gregory; Gamez, Anne Sophie; Molinari, Nicolas; Kacimi, Djamila; Paganin, Fabrice; Chanez, Pascal; Bourdin, Arnaud

2013-01-01

419

Ligamentous anatomy of the distal clavicle  

Microsoft Academic Search

We describe the insertional variations of supporting ligaments of the acromioclavicular joint, especially with respect to gender. We analyzed 41 cadaveric clavicles (22 female and 19 male) with attached ligaments. The distance between the insertion of the trapezoid ligament and the distal end of the clavicle was not significantly different between sexes, although that of the conoid ligament and the

Kevin J Renfree; Michael K Riley; Donna Wheeler; Joseph G Hentz; Thomas W Wright

2003-01-01

420

Therapeutic transplantation of the distal gut microbiota  

Microsoft Academic Search

Although it is generally accepted that the distal gut microbiota are relatively stable in healthy adult individuals, a collapse of the microbial community structure resulting from antibiotic therapy or pathogen presence can lead to gut dysfunction. However, recent findings demonstrate that it is possible to engraft new microbiota from a donor source, resulting in the restoration of gut functionality and

A Khoruts; M J Sadowsky

2011-01-01

421

Genetics Home Reference: Distal arthrogryposis type 1  

MedlinePLUS

... proteins to help regulate the tensing of muscle fibers (muscle contraction). It is unclear how mutations in the TPM2 and MYBPC1 genes lead to the joint abnormalities characteristic of distal arthrogryposis type 1. However, researchers speculate that contractures may be ...

422

Nonisothermal model of single screw extrusion of generalized Newtonian fluids  

SciTech Connect

A nonisothermal model of the single screw extrusion processing of generalized Newtonian fluids is presented. Various temperature dependent forms of a generalized Newtonian fluid constitutive equation representing the Herschel-Bulkley fluid and its simplifications, including Bingham plastic, power law of Ostwald-de Waele, and Newtonian fluids, are applicable. The model includes the generally ignored transverse convection terms of the equation of energy. The importance of keeping the transverse convection terms in the analysis is demonstrated by applying the model and comparing findings to experimental results involving the transverse flow temperature distributions in single screw extruders, available in the literature. The numerical instabilities, arising principally from the convection terms, generally encountered in high-Peclet-number extrusion flows, could be eliminated by the use of the streamline upwind/Petrov-Galerkin formulation. The model is sufficiently general to accommodate Navier's wall slip at the wall boundary condition commonly encountered during the processing of gels and concentrated suspensions.

Lawal, A.; Kalyon, D.M. (Stevens Inst. of Technology, Hoboken, NJ (United States). Highly Filled Materials Inst.)

1994-07-01

423

Detecting thrust bearing failure within a screw compressor  

SciTech Connect

A 3 1/2 mile ring of over 1000 superconducting magnets are needed to focus and drive the world`s highest energy particle smasher. 24 Refrigerators supply liquid helium to the magnets; 34 high pressure oil flooded screw compressors supply 285 psig helium gas to the refrigerators. The 400 h.p. screws are reliable machines that use 45 gallons of oil per minute to seal and lubricate the rotors, lubricate the bearings, and remove the heat of compression. These machines are spaced out in seven buildings over four miles. A minimum of 28 machines must be operating at all times. A contingent of operators start, stop, and monitor any machine from a distant control room. The 34 compressors have an average of 32,000 hours; 9 machines have over 40,000 hours; the highest is 55,000 hours.

Pallaver, C.

1994-05-01

424

Minimally invasive dynamic hip screw for fixation of hip fractures  

PubMed Central

We compared a minimally invasive surgical technique to the conventional (open approach) surgical technique used in fixation of hip fractures with the dynamic hip screw (DHS) device. Using a case-control design (44 cases and 44 controls), we tested the null hypothesis that there is no difference between the two techniques in the following outcome measures: duration of surgery, time to mobilisation and weight bearing postoperatively, length of hospital stay, mean difference of pre- and postoperative haemoglobin levels, position of the lag screw of the DHS device in the femoral head, and the tip–apex distance. The minimally invasive DHS technique had significantly shorter duration of surgery and length of hospital stay. There was also less blood loss in the minimally invasive DHS technique. The minimally invasive DHS technique produces better outcome measures in the operating time, length of hospital stay, and blood loss compared to the conventional approach while maintaining equal fixation stability.

Ho, Michael; Garau, Giorgio; Walley, Gayle; Oliva, Francesco; Panni, Alfredo Schiavone; Longo, Umile Giuseppe

2008-01-01

425

Release of elements from retrieved maxillofacial plates and screws.  

PubMed

Vitallium appliances and surrounding tissues were investigated to evaluate the release and accumulation of elements. Four microplates, sixteen screws and surrounding tissues were removed from three patients presenting inflammation 4 to 6 years after surgery and were submitted to SEM and X-ray microprobe analysis. Histology was performed on paraffin or PMMA sections of tissues.A continuous release of elements from metallic appliances into soft tissues was observed. Cobalt, chromium, and nickel were detected in soft and boney tissues in close proximity to the appliance. Aluminium, as a component of screw coatings, accumulated in soft tissues, and a remarkable amount of aluminium was detected in the dense lamella of lamellar bone. The results suggest that coatings containing aluminium should be avoided and the time these appliances are allowed to remain in patients should be shortened. Further studies on element release and the fate of aluminium in bone are warranted. PMID:16167115

Bertoldi, C; Pradelli, J M; Consolo, U; Zaffe, D

2005-09-01

426

Diffusion in a smectic liquid crystal with screw dislocations  

NASA Astrophysics Data System (ADS)

Screw dislocations provide barrier-free pathways that enhance interlayer diffusion in smectic liquid crystals and other layered materials. To explore this contribution to interlayer diffusion we study a ``random parking garage'' model in which a random walker can move between layers only by circling a dislocation core. We find that in such a layered system with a density of ? screw dislocations per unit area, with randomly chosen position, Burgers vector and phase, the ratio of interlayer to intralayer diffusion coefficients is D||/D?=(?b2/4?)ln R/a. Here b is the layer spacing, R is the layer radius, and a is the dislocation core size. Monte Carlo simulations are in agreement with this result. We discuss implications for both molecular simulation and experimental studies of diffusion in smectics.

Blumberg Selinger, Robin L.

2002-05-01

427

Alternative technique of cement augmentation of loosened pedicle screws -- technical note and presentation of two cases.  

PubMed

An alternative cement augmentation technique for pedicle screws is described, which was applied in two patients with mono- and bisegmental non-union after preceding multisegmental lumbar fusion. The correctly placed pedicle screws in S1 with diameters of 6 and 8.5 mm had severely enlarged the screw cavities due to segmental instability. Revision screws with 10 mm diameter demonstrated sufficient purchase only on the left side. Therefore, cement augmentation was performed for the right sided screws. After verification of intact pedicle borders, the cavity was filled up with PMMA bone cement. Afterwards, a Kirschner wire was positioned centrally, the hardening of the cement was awaited, the cement was gradually drilled and the screw was placed. In both patients, sufficient purchase of the cemented pedicle screws was documented. Screw insertion after awaiting the hardening of the bone cement in pedicles and vertebral bodies with huge defect situations seems to be an alternative to previous cement augmentation techniques of pedicle screws with the advantage, that the screws could be more easily unscrewed, if necessary. PMID:23452428

Kocak, T; Däxle, M; Reichel, H; Lattig, F

2013-01-01

428

Decompressive cervical laminectomy and lateral mass screw-rod arthrodesis. Surgical analysis and outcome  

PubMed Central

Background This study evaluates the outcome and complications of decompressive cervical Laminectomy and lateral mass screw fixation in 110 cases treated for variable cervical spine pathologies that included; degenerative disease, trauma, neoplasms, metabolic-inflammatory disorders and congenital anomalies. Methods A retrospective review of total 785 lateral mass screws were placed in patients ages 16-68 years (40 females and 70 males). All cases were performed with a polyaxial screw-rod construct and screws were placed by using Anderson-Sekhon trajectory. Most patients had 12-14-mm length and 3.5 mm diameter screws placed for subaxial and 28-30 for C1 lateral mass. Screw location was assessed by post operative plain x-ray and computed tomography can (CT), besides that; the facet joint, nerve root foramen and foramen transversarium violation were also appraised. Results No patients experienced neural or vascular injury as a result of screw position. Only one patient needed screw repositioning. Six patients experienced superficial wound infection. Fifteen patients had pain around the shoulder of C5 distribution that subsided over the time. No patients developed screw pullouts or symptomatic adjacent segment disease within the period of follow up. Conclusion decompressive cervical spine laminectomy and Lateral mass screw stabilization is a technique that can be used for a variety of cervical spine pathologies with safety and efficiency.

2011-01-01

429

Biomechanical evaluation of subtalar fusion: the influence of screw configuration and placement.  

PubMed

Common surgical procedures for subtalar fusion include joint resection, autologous bone grafting, and osteosynthesis with screws in a parallel screw configuration. Although fusion is a routine procedure, the reported rates of nonunion have been high. The present study assessed different screw configurations in terms of their rotational and bending stability in an artificial bone model and cadaver bone. Arthrodesis was always performed with 2 screws. Three different screw configurations were tested: parallel, counter-parallel, and a delta configuration. Two different screw designs were used: a cannulated, partially threaded screw (6.5-mm and 8.0-mm diameter) and a solid screw with a different thread design. Eight experimental groups were investigated as pilot studies in artificial bones and then 3 groups in cadaver bones. The parameters were the primary stiffness and deflection of the construct for loads simulating the internal-external rotation and supination-pronation. Delta positioning of the screws resulted in the greatest biomechanical stiffness and the lowest degrees of deflection of the arthrodesis in the artificial bones and cadaver bones. Increasing the screw diameter from 6.5 to 8.0 mm resulted in no additional stability of the arthrodesis in the artificial bones. The results of the present study have indicated that the delta configuration for arthrodesis results in the greatest construct stiffness and lower relative deflection between the talus and calcaneus in the positions tested. PMID:23333056

Hungerer, Sven; Eberle, Sebastian; Lochner, Susanne; Maier, Michael; Högel, Florian; Penzkofer, Rainer; Augat, Peter

2013-01-16

430

Management of odontoid fractures with percutaneous anterior odontoid screw fixation  

Microsoft Academic Search

Minimally invasive techniques have revolutionized the management of a variety of spinal disorders. The authors of this study\\u000a describe a new instrument and a percutaneous technique for anterior odontoid screw fixation, and evaluate its safety and efficacy\\u000a in the treatment of patients with odontoid fractures. Ten patients (6 males and 4 females) with odontoid fractures were treated\\u000a by percutaneous anterior

Yong-Long Chi; Xiang-Yang Wang; Hua-Zi Xu; Yan Lin; Qi-Shan Huang; Fang-Min Mao; Wen-Fei Ni; Sheng Wang; Li-Yang Dai

2007-01-01

431

Cellulose and the twofold screw axis: modeling and experimental arguments  

Microsoft Academic Search

Crystallography indicates that molecules in crystalline cellulose either have twofold screw-axis (21) symmetry or closely approximate it, leading to short distances between H4 and H1? across the glycosidic linkage. Therefore,\\u000a modeling studies of cellobiose often show elevated energies for 21 structures, and experimental observations are often interpreted in terms of intramolecular strain. Also, some computer models\\u000a of cellulose crystallites have

Alfred D. French; Glenn P. Johnson

2009-01-01

432

Investigation of seals with floating rings in a screw compressor  

Microsoft Academic Search

A number of screw compressors (SC) produced in the Soviet Union for air compression to a pressure of 1.5-2.5 kg\\/cm 2 use metallic labyrinth seals. The efficiency of these seals decreases rapidly as discharge pressure increases. Replacing these labyrinth seals by better designs can substantially reduce air leakage through the end seals of the SC and can improve their efficiency.

F. L. Yuditskii; B. L. Grinpress; Yu. L. Semenov

1972-01-01

433

Tibial Lengthening: Extraarticular Calcaneotibial Screw to Prevent Ankle Equinus  

Microsoft Academic Search

Between 2003 and 2006, we used an extraarticular, cannulated, fully threaded posterior calcaneotibial screw to prevent equinus\\u000a contracture in 10 patients (four male and six female patients, 14 limbs) undergoing tibial lengthening with the intramedullary\\u000a skeletal kinetic distractor. Diagnoses were fibular hemimelia (two), mesomelic dwarfism (two), posteromedial bow (one), hemihypertrophy\\u000a (one), poliomyelitis (one), achondroplasia (one), posttraumatic limb-length discrepancy (one), and

Mohan V. Belthur; Dror Paley; Gaurav Jindal; Rolf D. Burghardt; Stacy C. Specht; John E. Herzenberg

2008-01-01

434

Modelling of the Heating Process in a Thermal Screw  

NASA Astrophysics Data System (ADS)

The procedure of separating efficiently dry-stuff (proteins), fat, and water is an important process in the handling of waste products from industrial and commercial meat manufactures. One of the sub-processes in a separation facility is a thermal screw where the raw material (after proper mincing) is heated in order to melt fat, coagulate protein, and free water. This process is very energy consuming and the efficiency of the product is highly dependent on accurate temperature control of the process. A key quality parameter is the time that the product is maintained at temperatures within a certain threshold. A detailed mathematical model for the heating process in the thermal screw is developed and analysed. The model is formulated as a set of partial differential equations including the latent heat for the melting process of the fat and the boiling of water, respectively. The product is modelled by three components; water, fat and dry-stuff (bones and proteins). The melting of the fat component is captured as a plateau in the product temperature. The model effectively captures the product outlet temperature and the energy consumed. Depending on raw material composition, "soft" or "dry", the model outlines the heat injection and screw speeds necessary to obtain optimal output quality.

Zhang, Xuan; Veje, Christian T.; Lassen, Benny; Willatzen, Morten

2012-11-01

435

Twin screw wet granulation: the study of a continuous twin screw granulator using Positron Emission Particle Tracking (PEPT) technique.  

PubMed

In this paper, Positron Emission Particle Tracking (PEPT) techniques are utilised to track the trajectory of single particles through the mixing and conveying zones of a Twin Screw Granulator (TSG). A TSG consisting of conveying zones and mixing zones is used in this study. The mixing zones are arranged with kneading discs at an angle of 30°, 60° or 90°. Experiments were carried out using different mixing configurations with various screw speed and total mass flow rate. The PEPT data obtained were then utilised to obtain the residence time distribution (RTD) and the Peclet number in an attempt to gain some insight into the mixing of the process. The fill level of the granulator was also estimated to study the mechanism of granulation. As might be expected, it was shown that the residence time of the granulation process increases with decreasing screw speed. It also increases with increasing angle of the arrangement of kneading blocks in the mixing zones, but will decreases when powder feed rate is increased. The fill level of the mixing zone in particular increases when the screw speed decreases or when powder feed rate increases. Furthermore, the fill level of the granulator will increase when the mixing zone configuration changes from 30° to 90°. It is shown that the granulator is never fully filled, even using 90° mixer elements implying limited compaction which may explain why the granules produced are porous compared with those from a high shear mixer. Interestingly, the RTD analysis reveals that the extent of axial mixing in the mixing zone of the granulator does not change significantly for different configurations and process conditions. There is evidence of a tail in the RTD which implies some material hold up and channelling. PMID:22561951

Lee, Kai T; Ingram, Andy; Rowson, Neil A

2012-04-26

436

Intramedullary screw fixation of proximal fifth metatarsal fractures: a biomechanical study.  

PubMed

Intramedullary screw fixation is a popular technique for treatment of proximal fifth metatarsal fractures. The purpose of this study was to compare the fixation rigidity of a 5.5 mm partially threaded cannulated titanium screw, with presumed superior endosteal purchase, to a similar 4.5 mm screw. Acute fifth metatarsal fractures were simulated in cadavers, stabilized with intramedullary screws, and loaded to failure in three-point bending. The initial failure loads for the metatarsals fixed with 4.5 mm and 5.5 mm screws were not significantly different (332.4 N vs. 335.2 N, respectively), nor were the ultimate failure loads (849.8 N vs. 702.2 N, respectively). Based upon our results, maximizing screw diameter does not appear to be critical for fixation rigidity and may increase the risk of intraoperative or postoperative fracture. PMID:11503984

Shah, S N; Knoblich, G O; Lindsey, D P; Kreshak, J; Yerby, S A; Chou, L B

2001-07-01

437

Distal splenorenal shunt for portal hypertension.  

PubMed

A distal splenorenal shunt was performed electively in 25 patients with bleeding oesophageal varices. Early postoperative mortality was 16%. During the follow-up period (mean 41 months) three patients died, one of liver insufficiency and two of cardiac complications. Two patients of 17 survivors (12%) had endoscopically demonstrable varices. One of these patients had one upper gastrointestinal rebleeding period. The actual three year survival was 71%. Reverse portal blood flow was demonstrated postoperatively in eight of 17 patients (47%). In these cases the distal splenorenal shunt had in fact slowly turned to a total shunt. Even though in certain patients the original selectivity of the shunt is lost it gives a good long-term variceal decompression and certainly is a useful alternative in the treatment of selected good risk patients for bleeding oesophageal varices. PMID:6973313

Kallio, H; Lempinen, M

1981-01-01

438

The Epidemiology of Distal Radius Fractures  

PubMed Central

Distal radius fractures are one of the most common types of fractures, accounting for around 25% of fractures in the pediatric population and up to 18% of all fractures in the elderly age group. Although the pediatric and elderly populations are at the greatest risk for this injury, distal radius fractures still have a significant impact on the health and well-being of young adults. Data from the past 40 years has documented a trend towards an overall increase in the prevalence of this injury. For the pediatric population, this increase can likely be attributed to a surge in sports related activities. The growth of the elderly population and a rise in the number of active elderly are directly responsible for the increase seen in this age group. Understanding the epidemiology of this fracture is an important step towards the improvement of the treatment strategies and preventative measures which target this debilitating injury.

Nellans, Kate W.; Kowalski, Evan; Chung, Kevin C.

2012-01-01

439

A Review of Distal Ulnar Hemi-Resection Arthroplasty  

Microsoft Academic Search

15 patients with pain and disability on the ulnar side of the wrist were treated by distal ulnar hemiresection arthroplasty. The patients’ diagnoses fell into three groups, namely ulnocarpal impingement, primary osteoarthritis of the distal radio-ulnar joint and traumatic disruption of the distal radioulnar joint. Patients were assessed pre- and post-operatively on the basis of pain and forearm rotation. Grip

D. K. FAITHFULL; S. KWA

1992-01-01

440

A modified intramedullary nail interlocking design yields improved stability for fatigue cycling in a canine femur fracture model.  

PubMed

Intramedullary nailing has evolved to become the standard of care for most diaphyseal femoral and tibial fractures, as well as an expanding number of metaphyseal fractures. Owing to the unstable nature of some fractures, the intramedullary device may be subjected to significant stresses owing to a lack of solid cortical contact after nailing. In such cases, excessive interfragmentary motion (due to construct toggle) has been shown to occur. Such motion increases the likelihood of a non- or delayed-union. In the current study, two versions of a modified, angle stable interlocking design were subjected to fatigue testing in a segmental defect fracture model representing a canine femur. As a control, a third group of constructs were stabilized with a traditional nail that allowed a small amount of toggle. All constructs were subjected to 50,000 fatigue cycles representing 12 weeks of cage activity at physiologic levels of combined axial-torsional loading. Torsional testing pre- and post-fatigue revealed 4.6 +/- 1.3 degrees of toggle in the traditional nail and no toggle with the angle stable nail designs. The stable nails were also significantly stiffer in axial compression and torsion before and after cycling. These data indicate that the enhanced stability of the modified interlocking designs can be maintained throughout fatigue cycling in a challenging fracture model. PMID:22783763

Garlock, Adam N; Donovan, Jim; LeCronier, David J; Houghtaling, John; Burton, Stephen; Atkinson, Patrick J

2012-06-01

441

Precision timing and interlocks systems for FEL (Free-Electron Laser) heating experiments on MTX (Microwave Tokamak Experiment)  

NASA Astrophysics Data System (ADS)

A new precision timing system has been installed on the Microwave Tokamak Experiment (MTX) at Lawrence Livermore National Laboratory (LLNL). The purpose of the system is to synchronize the tokamak's plasma discharge with a 140-GHz, 2-GW microwave pulse generated by a free-electron laser (FEL). The installation involved modifying the existing sequencer system and adding Digital delay generators, three in-house-designed CAMAC modules and other components. The system controls placement of the 30-ns FEL pulse during the MTX plasma discharge. It also provides precision triggers for the microwave plasma diagnostics. These triggers are distributed over 100-Mbit/s fiber-optic links. The MTX interlock system has been expanded to provide personnel safety during FEL experiments, to protect the FEL and related equipment, and to control the path of the FEL beam starting from the FEL's output, through the beam transport system, and into the tokamak. This paper describes how the existing MTX timing and interlocks systems were upgraded to accommodate these new FEL experiments.

Petersen, D. E.

1989-09-01