International Nuclear Information System (INIS)

Fracture toughness data of pre-cracked Charpy single-edge bend, SE(B), specimens are compared with those of standard compact, C(T), specimens in the upper shelf and ductile-to-brittle transition regimes. Charpy sized SE(B) specimens provide ductile fracture toughness data, which are compatible with those of standard C(T) specimens. Statistical methods such as the exponential curve fitting method (ECF), the engineering lower bound toughness method (ELB), and the Master Curve method (MC) are used to provide meaningful lower bound cleavage fracture toughness estimates from the toughness scatter of the Charpy sized SE(B) specimens in the ductile-to-brittle transition regime. In this regime, according to the ELB and MC methods, SE(B) specimens provide cleavage toughness data, which tend to be non-conservative compared to those of standard C(T) specimens. However, analyses based on the ...

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Advances in the theory and practice of stress corrosion cracking (SCC) are reviewed for the period 1965-1990. The proceedings of two landmark conferences are used as a basis for discussion: Ohio State University (1967) and Kohler, WI (1988). The discussion is developed around the following topics: metal-environment combinations, testing, fractography, metallurgical aspects, electrochemical aspects and crack chemistry, mechanisms, and prediction and mitigation. It is concluded that the main developments since 1967 are the recognition of the lack of specificity of SCC environments, the use of slow strain rate and fracture mechanics testing, quantitative SEM fractography, studies of grain boundary structure and compositions, transient electrochemistry of bare metal surfaces, measurement and modelling of crack chemistry, elaboration of several SCC models, including slip-dissolution and film induced cleavage, and mitigation by alloy development or ...

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Tibial Shaft Fractures in Children

CERN Document Server

In this paper we have studied the relation between the intutionistic fuzzy left (respectively right) ideals of {\\Gamma}-semiring and that of operator semiring. Thereafter, we have established that the Lattices of all intutionistic fuzzy left (respectively right) ideal of {\\Gamma}-semiring is equivalent to that of Left operator semiring. We proved that Then there exist an inclusion preserving bijection ({\\mu}_{A,}\\u{psion}_{A})$\\rightarrow$({\\mu}_{B}^{+'},\\u{psion}_{B}^{+'}) between the lattices of all intuitionistic fuzzy right ideals (respectively intuitionistic fuzzy ideals) of S and the lattices of all intuitionistic fuzzy right ideals (respectively intuitionistic fuzzy ideals) of L. Where ({\\mu}_{A},\\u{psion}_{A}) is an intuitionistic fuzzy right (respectively intuitionistic fuzzy ideals) ideal of S. Also we ...

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In this paper, bond cleavage reactions are discussed in relation to the softening and solubilization of coal. Were used 9,10-dihydroanthracene (DHA) and 9,10-dihydrophenanthrene (DHP) as models of hydrogen donating compounds in coal, and bibenzyl, 1,2-diethane, benzylphenylether, and 1,5-dibenzylnaphthalene were used as models of bridge structure compounds. They were compared mutually, as to reactivity of coal against DHA and DHP. For the homolytic cleavage of bridges, DHA with excellent radical supplement performance provided excellent hydrogen donating performance. While, for the ipso-position cleavage of bridges, it was found that DHP can act as an effective hydrogen donor. For the reaction between coal and hydrogenated aromatic compounds, cleavage of relatively weak bonds, such as ether linkage and dimethylene linkage, occurred at about 380{degree}C, and hydrogen from DHA or DHP was consumed. On the ...

International Nuclear Information System (INIS)

The purpose of this study was to determine the optimal technique for delivering postoperative radiotherapy for vulvar cancer and other tumors requiring treatment of the inguinal nodes. This project compared tumor coverage and normal tissue sparing for the 5 main radiotherapy techniques that are used to treat vulvar cancer. The intensity-modulated radiation therapy (IMRT) plan was undesirable because it resulted in an excessive dose to portions of the central pelvic structures. The photon thunderbird with skin match was unacceptable because it underdosed a portion of the groin region. The electron thunderbird was ideal for thin patients but was not applicable for most patients because of excessive dose to the skin and subcutaneous tissues. The photon through-and-through and the photon thunderbird with deep match were acceptable in most situations. In thin patients, where the depth of the inguinal vessels is less than 3 cm, the electron thunderbird is the technique ...

International Nuclear Information System (INIS)

The properties of the ideal gas of classical (nonquantum) tachyons are considered. Starting from the definition of thermodynamic functions for this system, it may be found that tachyons and bradyons gases are similar. (AA).

UK PubMed Central (United Kingdom)

(1).—Varieties of spinal injuries, the three groups of common usage: fractures, dislocations, fracture-dislocations. Shall not refer in detail to fractures of the spinous or transverse processes....Full Text Available

International Nuclear Information System (INIS)

The paper deals with sixteen cases of acetabular fractures studied with CT. After a short description of the normal CT findings, the different kind of fractures are reported. The usefulness of CT examination in evaluating acetabular fractures and their complications is confirmed both in conservative treatment and surgical approach.

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... Accession Number : ADA136144. Title : Characteristics of the Mechanical Properties and the Fractures of an Alpha Beta Titanium Alloy,. ...

UK PubMed Central (United Kingdom)

Strong aqueous ammonium hydroxide used to remove N-acyl protecting groups from synthetic oligoribonucleotides causes removal of some alkylsilyl protecting groups from 2'-hydroxyls and leads to chain...Full Text Available

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BackgroundNumerous microRNAs (miRNAs) have heterogeneous ends resulting from imprecise cleavages by processing nucleases and from various non-templated nucleotide additions. The...Full Text Available

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Membrane cofactor protein (MCP or gp45-70) of the complement system is a cofactor for factor I-mediated cleavage of fluid-phase C3b and C3b-like C3, which opens the thioester bond. In the present study...Full Text Available

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BackgroundBrevican is a member of the lectican family of aggregating extracellular matrix (ECM) proteoglycans that bear chondroitin sulfate (CS) chains. It is highly expressed in...Full Text Available

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Cellular cholesterol homeostasis is controlled by sterol-regulated proteolysis of membrane-bound transcription factors called sterol-regulatory element binding proteins (SREBPs). CPP32, a cysteine protease,...Full Text Available

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Ternary copper(II) complexes [Cu(L1)B](ClO4) (1, 2) and [Cu(L2)B](ClO4) (3, 4), where HL1 and HL2 are tridentate NSO- and ONO-donor Schiff bases and B is a heterocyclic base, viz. dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 1 and 3) or dipyrido[3,2-a:2',3'-c]phenazine (dppz, 2 and 4), were prepared and their DNA binding and photoinduced DNA cleavage activity studied. Complex 1, structurally characterized by single-crystal X-ray crystallography, shows an axially elongated square-pyramidal (4 + 1) coordination geometry in which the monoanionic L1 binds at the equatorial plane. The NN-donor dpq ligand exhibits an axial-equatorial binding mode. The complexes display good binding propensity to calf thymus DNA, giving a relative order 2 (NSO-dppz) > 4 (ONO-dppz) > 1 (NSO-dpq) > 3 (ONO-dpq). They cleave supercoiled pUC19 DNA to its nicked circular form when treated with 3-mercaptopropionic acid (MPA) by formation of hydroxyl radicals as the ...

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... s excellent water quality and ideal temperature conditions. Oyster aquaculture operations on the Damariscotta lease about 100 acres ... ...

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Background:High-energy fractures of posterior tibial plateau always need surgical treatment. Generally, posterior fragments of these fractures could not be exposed and reduced...Full Text Available

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IntroductionSeizures with or without trauma may cause fractures that occur commonly in epileptic seizures. Fracture risk is less reported in non-epileptic seizures. Some metabolic...Full Text Available

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BackgroundHip fracture patients often have an impaired nutritional status at the time of fracture, which can result in a higher complication rate, prolonged rehabilitation time and...Full Text Available

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We report a case of stress fracture of the clavicle associated with sternocostoclavicular hyperostosis. A 60-year-old man sustained a stress fracture of the right clavicle with no history of trauma. On radiography, hyperostosis of the anterior chest wall and ankylosis of the sternoclavicular joint were evident in addition to the fracture. Fracture healing was uneventful after 2.5 months. Ankylosis of the sternoclavicular joint may have caused increased stress at the midshaft of the clavicle by daily activity or minor trauma. Such a fracture is a rare complication of sternocostoclavicular hyperostosis. (orig.)

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Background Fracture healing in osteoporosis is delayed. Quality and speed of fracture healing in osteoporotic fractures are crucial with regard to the outcome of patients. The question arises whether established antiosteoporotic drugs can further improve fracture healing. Materials and methods Osteoporosis manifests predominantly in the metaphyseal bone. Nevertheless, an established metaphyseal fracture model is lacking. A standardized metaphyseal fracture-healing model with stable plate fixation was developed for rat tibiae. The healing process was analyzed by biomechanical, gene expression, and histomorphometric methods in ovariectomized (OVX) and sham-operated rats (SHAM), compared to standardized estrogen (E)- and raloxifene (R)-supplemented diets. Results Estrogen and raloxifene impro...

Science.gov (United States)

MINC stands for Multiple INteracting continua.'' It is an approximate method for modeling fluid and heat flow in fractured- porous media, developed by Pruess and Narasimhan (1982, 1985) at the Lawrence Berkeley Laboratory. The method is applicable to flow processes in which an important aspect is the exchange of fluid, heat, or chemical species between fractures and unfractured rock. Examples include production and injection operations in fractured geothermal reservoirs, water-flooding, steamflooding, and other methods for enhanced oil recovery from fractured reservoirs, as well as chemical transport and contaminant migration in fractured rock. MINC can only be applied to media in which the fractures are sufficiently well connected so that a continuum treatment of flow in the fracture network can be made.

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The aim of this study was the evaluation of contralateral hip fractures after a previous hip fracture. For this retrospective analysis patients were selected from the database of the LUMC, a teaching hospital in the south-west of the Netherlands. We analyzed all patients with a second fracture of a hip between 1992 and 2007. The exclusion criteria were high impact trauma and patients with diseases or medication known to have a negative effect on bone metabolism. A total of 1,604 hip fractures were identified. The possible predictive factors for the second fracture and descriptive statistics related to surgery (Hb and HT before and after the operation, total amount of intra- and postoperative blood loss, type of osteosynthesis, complications, time of death after the last fracture, time betw...

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In this Letter, we present Quantum Mechanics/Molecular Mechanics (QM/MM) calculations on molecules containing a 2-deoxycytidine-3prime-monophosphate moiety (3prime-dCMPH). In particular, we examine the effect that including neighbouring nucleotides at the Molecular Mechanic (MM) level has on the calculated electron affinities and on the energetic barriers of the C3prime-O3prime bond cleavage. Our results demonstrate that the surrounding nucleotides relocate the excess electron from the p* orbital of the base to a diffuse phosphate-centred orbital, leading to the formation of a dipole-bound anion state. Both the electron affinities and the activation energy of C3prime-O3prime bond cleavage are strongly increased.

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Rock fracture characterization documents a total of 1496 fractures in unit 2 of the Tshirege Member of the Bandelier Tuff along 6013 feet of Los Alamos Canyon`s north wall adjacent to Operational Unit 1098. Geologically termed joints, these fractures likely owe their primary origin to brittle failure during the cooling contraction of the tuff after its emplacement nearly 1 million years ago. Subsequent tectonic movement along the Pajarito Fault system has modified fracture strikes, dips, apertures, and linear density. From a background linear density of approximately 20 fractures per 100-foot interval along the canyon wall, fracture density increases to values in excess of 50 fractures per 100-foot interval in a zone at and immediately east of the Omega West reactor building TA-2-1. This increase in fracture density is ...

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of fracture -stimulated geothermal reservoirs; 2) the development of ... of the mathematical simulation model of geothermal reservoirs. ...

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No abstract prepared.

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International Nuclear Information System (INIS)

The present work is a research of the effect of helium on the microstructure, mechanical properties and fracture behaviors of a type 316 austenitic steel. Helium implantation was performed by 30-MeV #alpha#-particle injection on very small size specimens, using a cyclotron. Average helium content in a He-deposited region was up to 2000 appm He. In the case of 2000appm He implantation, intergranular fracture was sometimes observed on the helium deposited region after tensile test at room temperature. At elevated temperature test, however, this material showed the transition of fracture mode from transgranular-ductile fracture at 773K to intergranular fracture at 873. In the case of 500 appm He implantation, the transition of fracture mode was recognized at a temperature range of 873K to 973K. (author).

International Nuclear Information System (INIS)

Over 300 cases of femoral neck fractures following radiotherapy for intrapelvic malignant tumor have been reported in various countries since Baensch reported this disease in 1927. In Japan, 40 cases or so have been reported, and cases of bilateral femoral neck fractures have not reached to ten cases. The authors experienced a case of 75 year-old female who received radiotherapy for cancer of the uterus, and suffered from right femoral neck fracture 3 months after and left femoral neck fracture one year and half after. As clinical symptoms, she had not previous history of trauma in bilateral femurs, but she complained of a pain in a hip joint and of gait disturbance. The pain in left femoral neck continued for about one month before fracture was recognized with roentgenogram. As histopathological findings, increase of fat marrow, decrease of bone trabeculae, and its marked ...

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Interbedded limestones and dolomites of the Cambrian Conococheague Formation cropping out northwest of Lancaster exhibit contrasting rheological behavior during deformation. Dolomite beds are uncleaved and form concentric F[sub 1] recumbent folds with hinges trending northeast, parallel to the trend of the Appalachian orogen. Limestone beds show subhorizontal S[sub 1] cleavage with southeast-plunging extension lineations defined by fibrous calcite and ubiquitous smear lineations. In limestone beds, intrafolial F[sub 1] folds with curvilinear hinges are sheath folds flattened in the S[sub 1] cleavage. In zones of most intense shear, F[sub 1] hinges parallel the regional northwest directed tectonic transport direction. In 1969, the author attributed the variation in intrafolial F[sub 1] fold-hinge orientation to hinge-parallel buckling due to constrictional bulk strain. This interpretation, however, is not consistent with the absence of ...

UK PubMed Central (United Kingdom)

Suicide substrate β, γ-bidentate Rh(III)ATP (RhATP) was used to map the metal ion-binding site in yeast phosphoglycerate kinase (PGK). Cleavage of the RhATP-inactivated enzyme with...Full Text Available

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Back pain from osteoporosis is commonly related to compression fractures. The patient with vertebral compression fractures additionally suffers from an ongoing risk of recurrent fractures and postural abnormalities that can result in impaired respiratory function, leading to increased risk of morbidity. Weakened back muscles, especially the back extensor group, are felt to contribute significantly to this risk. The combination of pharmacologic and nonpharmacologic interventions, through physical activity, exercise, and modalities, are potential interventions that could be used to help reduce the pain of osteoporotic compression fractures as well as potentially reducing recurrent fracture rates.

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We introduce a weak order ideal property that suffices for establishing the Evans-Griffith Syzygy Theorem. We study this weak order ideal property in settings that allow for comparison between homological algebra over a local ring R versus a hypersurface ring R =R/(x^n). Consequently we solve some relevant cases of the Evans-Griffith syzygy conjecture over local rings of unramified mixed characteristic p, with the case of syzygies of prime ideals of Cohen-Macaulay local rings of unramified mixed characteristic being noted. We reduce the remaining considerations to modules annihilated by p^s, s>0, that have finite projective dimension over a hypersurface ring.

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... turbine blade heat-transfer and study the heat-transfer augmentation in idealized geometry and its ... responsible for heat transfer augmentation. ...

CERN Document Server

A process has been proposed to increase the efficiency of an ideal Otto cycle via a quantum heat engine that has no cooler reservoir. We show that such a process is not feasible.

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Mineral deposition or alteration is commonly found at fracture-block interfaces is fissured, geothermal reservoirs. In response to pressure reduction in the fissures such mineralization, if less permeable than the matrix rock, will retard the flow of fluid from the blocks to the fissures and is termed fracture skin in this paper. The problem of fluid flow to a production well in a double-porosity reservoir with fracture skin was analyzed theoretically. One of the findings of the analysis was that fully transient block-to-fissure flow can be approximated by pseudo-steady state flow if fracture skin permeability is sufficiently low. Type curves generated by numerical inversion of Laplace transform solutions are used to cooroborate the results of a finite-difference model of steam transport to a well in a naturally fissured, geothermal reservoir with fracture skin.

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The understanding of transport processes that occur in naturally fractured geothermal systems is far from being complete. Often, evaluation and numerical simulations of fractured geothermal reservoirs, are carried out by assuming equivalent porous media and homogeneous petrophysical properties within big matrix blocks. The purpose of this paper, is to present a comparison between results obtained from numerical studies of a naturally fractured reservoir treated as a simple porous medium and the simulation of some real aspects of the fractured reservoir. A general conclusion outlines the great practical importance of considering even approximately, the true nature of such systems. Our results show that the homogeneous simplified evaluation of the energy resource in a fractured system, could result in unrealistic estimates of the reservoir capacity to generate electricity.

CERN Document Server

By using a laser and maser in tandem, it is possible to obtain laser action in the hot exhaust gases involved in heat engine operation. Such a "quantum afterburner" involves the internal quantum states of working gas atoms or molecules as well as the techniques of cavity quantum electrodynamics and is therefore in the domain of quantum thermodynamics. As an example, it is shown that Otto cycle engine performance can be improved beyond that of the "ideal" Otto heat engine.

International Nuclear Information System (INIS)

Intracapsular femoral neck fractures remain unsolved fractures even after improvement in techniques of diagnosis and internal fixation. Individuals who sustain displaced femoral neck fractures are at high risk of developing avascular necrosis and non-union. Although several methods for predicting the viability of femoral head have been reported, they are not effective or widely used because of unreliability, potential complications and technical difficulties. Dynamic MRI was introduced in the recent past as a simple, non-invasive technique to predict the femoral head viability after the femoral neck fractures. In this study role of dynamic MRI was studied in 30 patients with 31 intracapsular femoral neck fractures. Fractures were divided in to three types according to dynamic curve patterns on MRI evaluation and were followed up for 6 months to 2 years to ...

UK PubMed Central (United Kingdom)

Osteoporotic vertebral fractures often lead to pain and disability. They can be successfully treated, and possibly prevented, by injecting cement into the vertebral body, a procedure known as vertebroplasty....Full Text Available

UK PubMed Central (United Kingdom)

BackgroundThere have been reports both supporting and refuting an inverse relationship between hip fracture and hip osteoarthritis (OA). We explore this relationship using a case-control...Full Text Available

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A scintimetric study using Tc-99m MDP was made of 54 patients with delayed union, nonunion, or late segmental collapse of the femoral head, 4-92 months after femoral neck fracture. In radiographically verified collapse, the radionuclide uptake ratio between the femoral head on the fractured and on the intact side (HHR) was significantly higher than in fractures resulting in delayed union or nonunion. On the basis of scintimetric and radiographic findings, the patients with healing disturbances could be divided into three groups, characterized by the following features: (1) Satisfactory post-reduction position of the fracture without subsequent redisplacement and a high HHR, which as a rule turned out to be delayed union; (2) The same radiographic pattern but with a lower HHR, which in most cases resulted in nonunion; (3) Inadequate reduction or early redisplacement of the fracture ...

UK PubMed Central (United Kingdom)

Current drug treatments for post-menopausal osteoporosis cannot eliminate bone fractures, possibly because the mechanisms responsible for bone loss are not fully understood. Although research within...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundThis case series report discusses patients presenting with hemorrhage and hemodymanic compromise due to severe pelvic fractures and undergoing intraoperative angioembolization...Full Text Available

UK PubMed Central (United Kingdom)

OBJECTIVE:To evaluate the profile of osteoporosis treatment among patients hospitalized due to hip fractures at a tertiary-level university hospital. To compare the impact of hospitalization...Full Text Available

UK PubMed Central (United Kingdom)

Background: Intramedullary fixation of midclavicular fractures may be a better option than non-operative treatment for high performance/professional athletes because of the potential reduction...Full Text Available

UK PubMed Central (United Kingdom)

Background:The present study measured longitudinal changes in bone turnover markers in elderly patients with vertebral fracture and investigated the relationship among bone turnover...Full Text Available

UK PubMed Central (United Kingdom)

The use of cementless threaded cups in THA is a well-established treatment. Fractures of the cups are rare complications recorded in individual cases with material defects being discussed as the primary...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundThe effects of intervention programs on health-related quality of life (HRQOL) of patients with hip fracture have not been well studied. We hypothesized that older patients...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The Idaho National Engineering Laboratory (INEL) has been conducting geothermal reservoir research and testing sponsored by the US Department of Energy (DOE) since 1983. The INEL research program is primarily aimed at the development of reservoir engineering techniques for fractured geothermal reservoirs. Numerical methods have been developed which allow the simulation of fluid flow and heat transfer in complex fractured reservoirs. Sensitivity studies have illustrated the importance of incorporating the influence of fractures in reservoir simulations. Related efforts include fracture characterization, geochemical reaction kinetics and field testing.

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... MATHEMATICAL PREDICTION, BODIES, SKIN(ANATOMY), SONIC BOOM, BIOPHYSICS, WOUND BALLISTICS, BONE FRACTURES, SKULL. ...

International Nuclear Information System (INIS)

Japanese Mar 1999 p. 371-372 Japan Shi, Dequan Yamazaki, Takashi

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Self-expanding metallic stent insertion has been widely applied for the palliative treatment of malignant esophageal strictures. Although it is known as an easy, safe, and effective procedure, complications are well known and include things such as stent migration and esophageal stent occlusion caused by tumor in growth. However, metallic stent fractures have been rarely reported in the esophagus, especially for nitinol stents. We report a case of a stent fracture associated with migration in a patient with a malignant esophageal stricture near the gastroesophageal junction. It is highly probable that the stent fracture was due to chemical erosion of the stent caused by gastric juice

British Library Electronic Table of Contents (United Kingdom)

Abstract TLR9 recognizes unmethylated CpG-containing DNA commonly found in bacteria. Synthetic oligonucleotides containing CpG-motifs (CpG ODNs) recapitulate the activation of TLR9 by microbial DNA, whereas inversion of the CG dinucleotide within the CpG motif to GC (GpC ODNs) renders such ODNs inactive. This difference cannot be attributed to binding of ODNs to the full-length TLR9 ectodomain, as both CpG and GpC ODNs bind comparably. Activation of murine TLR9 requires cleavage into an active C-terminal fragment, which binds CpG robustly. We therefore compared the ability of CpG and GpC ODNs to bind to full-length and C-terminal TLR9, and their impact on the cleavage of TLR9. We found that CpG binds better to C-terminal TLR9 when compared with GpC, despite comparably low binding of both O...

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Different sized ROIs within the femoral head and different modes of calculation were used in (/sup 99m/Tc)MDP scintimetry after femoral neck fracture. In preoperative scintimetry, correction for increased trochanteric uptake gave the best discrimination, whereas in postoperative scintimetry the direct ratio fractured/intact femoral head was superior. The change in ROI size had little influence.

International Nuclear Information System (INIS)

The threshold stress intensities for stress corrosion crack propagation in beta titanium alloy 38-6-44, Ti3Al-8V-6Cr-4Mo-4Zr, has been determined in salt water and methanolic solutions. The alloy was immune to stress corrosion cracking (SCC) in aqueous sodium chloride solutions (marine atmosphere). However, in methanolic solutions, the alloy was very susceptible to SCC. This marked susceptibility in methanolic solutions can be mitigated by the addition of an inhibitor: sodium nitrate. Crack extension in the alloy was transgranular and failure occurred by brittle quasi-cleavage in methanolic solutions.

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Schemata for modelling combustion processes do not yet include reaction rates for oxygenated fuels like methylal (DMM) which is considered as an additive or replacement for diesel due to its low sooting propensity. Density functional theory (DFT) studies of the possible reaction pathways for different dissociation steps of methylal are presented. Cleavage of a hydrogen bond to the methoxy group or the central carbon atom were simulated at the BLYP/6-311++G{sup **} level of theory. The results are compared to the experiment when dissociating and/or ionising DMM with femtosecond pulses. (author) 1 fig., 1 tab., 1 ref.

British Library Electronic Table of Contents (United Kingdom)

In this study, the influence of Beryllium (Be) content on the fracture behaviour of Al?15%Mg2Si composite was investigated. The results showed an increase in mechanical properties with increasing of Be content. The stress?strain curves of samples showed a same category of serrations reflecting non-uniform deformation. Scanning electron microscopy was employed to examine the crack nucleation and fracture model. The results indicate that Al?15%Mg2Si composite shows different behaviours of crack initiation and fracture for samples with and without Be. Differences observed in the fracture behaviour were attributed to microstructural changes as well as morphological aspects of primary Mg2Si particles.

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Forty-five patients with recent cervical hip fractures were included in a prospective, clinical, radiographic and sequential scintimetric study. Striking changes in radionuclide uptake over the entire hip region on the fracture side were found during the first 5 postoperative months. Fractures that healed without complications showed the highest relative femoral head uptake at 1 week and a peak value at 6 weeks, followed by a gradual decline at the subsequent examinations. Fractures with complications (redisplacement, nonunion, or late segmental collapse) showed a lower initial uptake and a more gradual increase and only a slight tendency towards increased uptake after 3 months. The accuracy in predicting nonunion with scintimetric examination alone is high both at 1 and at 6 weeks, and the accuracy is almost equally high with combined scintimetric, radiographic, and clinical assessment 3-5 months ...

British Library Electronic Table of Contents (United Kingdom)

This paper presents a procedure for transferring the CTOD fracture toughness obtained from laboratory specimens to an equivalent CTOD for structural components, taking constraint loss into account. The Weibull stress criterion is applied to correct the CTOD for constraint loss, which leads to an equivalent CTOD ratio, b, defined as b=d/dWP, where d and dWP are CTODs of the standard fracture toughness specimen and the structural component, respectively, at the same level of the Weibull stress. The CTOD ratio b is intended to apply to the fracture assessment of ferritic steel components to stress levels beyond small-scale yielding. Nomographs are given to determine the b-value as a function of the crack type and size in the component, the yield-to-tensile ratio of the material and the Weibul...

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The conference proceedings contains 30 papers of which five are abstracted separately. The subjects covered include fatigue crack growth in aircraft materials, fractographic measurements, fatigue cracks in nylon 66 blends, cyclic inelastic deformation aspects, prestressing, tensile cracks in creeping solids, creep-crack-growth in 304 stainless steel, high-temperature fatigue, parallel impact loading, numerical fracture dynamic code, J-resistance curves, specimen geometry effects, reactor piping systems, temperature dependence of fracture toughness, small-scale yielding, compact specimens, power hardening materials, semi-empirical fracture analyses, pipeline girth welds, wrought steels, and A36 bridge steels.

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A model is developed to represent mechanical strain, stress-enhanced dissolution, and shear dilation as innately hysteretic and interlinked processes in rough contacting fractures. The model is incorporated into a numerical simulator designed to examine permeability change and thermal exchange in chemically active and deformable fractured reservoirs. A candidate engineered geothermal reservoir system (EGS) is targeted. The mechanistic model is able to distinguish differences between the evolution of fluid transmission characteristics of (1) small scale, closely spaced fractures, and (2) large-scale, more widely spaced fractures. Alternate realizations of fracture frequency and scale, exhibiting identical initial bulk permeability, lead to significantly different conclusions regarding perme...

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Twenty-six patients with late complications following femoral neck fracture were examined with both skeletal and bone marrow radionuclide scintimetry. There was no correlation between the methods with respect to the quantitative assessment of femoral head vascularity based on different uptake ratios comparing the fractured and the intact side. Skeletal scintimetry always had good image quality and permitted reliable differentation between nonunion of the fracture and late segmental collapse, in contrast to bone marrow scintimetry which gave poor image quality. Skeletal scintimetry thus seems superior to bone marrow scintimetry for assessment and differential diagnosis of late complications following femoral neck fracture. It is emphasized that the physiological mechanisms for radionuclide uptake must be taken into account when comparing scintimetric studies using different tracers.

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Between 25 and 30 percent of total known petroleum reserves are contained within oil-laden fractured reservoirs where the dominant flow path is through the fractures. Economic oil recoveries from fractured reservoirs depend on a better understanding of the flow in fractures and networks of fractures. However, the flow of heavy oil and water, and particularly the flow regime map for two-phase immiscible flow has received less attention in contrast with gas-liquid flow in fractures. This paper discussed the use of flow pattern observations in a Hele-Shaw cell to generate two-phase flow regime maps. The paper investigated the effect of fracture gap and fluid viscosities on flow regimes. A correlation based on different flow and fracture properties was developed to define flow transition conditions between flow regimes. The ...

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A central issue to be addressed within the Nevada Nuclear Waste Storage Investigations (NNWSI) is the role which fractures will play as the variably saturated, fractured rock mass surrounding the waste package responds to heating, cooling, and episodic infiltration events. Understanding the role of fractures during such events will, in part, depend on our ability to make geophysical measurements of perturbations in the moisture distribution in the vicinity of fractures. In this study we first examine the details of the perturbation in the moisture distribution in and around a fracture subjected to an episodic infiltration event, and then integrate that behavior over the scale at which moisture measurements are likely to be made during the Engineered Barrier Design Test of the NNWSI project. To model this system we use the TOUGH hydrothermal code and fracture and ...

UK PubMed Central (United Kingdom)

The t-butyldimethylsilyl group is shown to be an ideal protecting group for the 2T-hydroxyl function of ribonucleosides during the synthesis of ribonucleotides using any of nine commonly used condensing...Full Text Available

UK PubMed Central (United Kingdom)

Background and Objectives:Sound enamel manifests peak transparency in the near-IR (NIR) at 1310-nm, therefore the near-IR is ideally suited for high contrast imaging...Full Text Available

UK PubMed Central (United Kingdom)

Atrial septal defect closure is now routinely performed using a percutaneous approach under echocardiographic guidance. Centrally located, secundum defects are ideal for device closure but there is...Full Text Available

UK PubMed Central (United Kingdom)

The overarching goal of medical training is to nurture the growth of knowledgeable, caring and insightful clinicians guided by the ideals of medical professionalism. Recent definitions of professional...Full Text Available

UK PubMed Central (United Kingdom)

The conventional IMRT planning process involves two stages in which the first stage consists of fast but approximate idealized pencil beam dose calculations and dose optimization and the second...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Delivering the promise of personalised medicine is the challenge that the current generation of scientists face. The variations in human physiology and disease are considerable, and designing appropriate strategies to deliver what has been promised will require access to tissue from a large number of volunteers. The NHS provides an ideal infrastructure for sample acquisition, but requires two things to make this available?public consent and support for extra manpower and administration. There is a disconnection between the NHS and tissue based research that needs to be addressed on a number of levels to provide a translational platform. This should enable the path to be beaten to provide the ideal tailored treatment for future patients; one that preserves quality of life by curing the dise...

CERN Document Server

We develop a framework based on microeconomic theory from which the ideal gas like market models can be addressed. A kinetic exchange model based on that framework is proposed and its distributional features have been studied by considering its moments. Next, we derive the moments of the CC model (Eur. Phys. J. B 17 (2000) 167) as well. Some precise solutions are obtained which conform with the solutions obtained earlier. Finally, an output market is introduced with global price determination in the model with some necessary modifications.

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By comparison of standard entropies theoretically calculated and determined from gas-chromatographic data for 40 halo-aliphatic and halo-aromatic compounds 8 organic iodine compounds among them, adsorbed on graphitized thermal carbon black it was found that in all the cases the molecular model of ideal two-dimensional gas is a sufficiently good approximation. It was shown that for a number of systems the agreement can be improved if the vibrations of the center of molecular mass relative to the surface are taken into account

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Purpose: In an experimental study, the correlation between the trabecular bone density of the different regions of the proximal femur and the fracture load in the setting of femoral neck fractures was examined. Methods: The bone mineral density 41 random proximal human femora was estimated by single-energy quanitative CT (SE-QCT). The trabecular bone density was measured at the greatest possible extracortical volume at midcapital, midneck and intertrochanteric level and in the 1 cm"3 volumes of the centres of these regions in a standardised 10 mm thick slice in the middle of the femoral neck axis (in mg/ml Ca-hydroxyl apatite). The proximal femora were then isolated and mounted on a compression/bending device under two-legged stand conditions and loaded up to the point when a femoral neck fracture occurred. Results: Statistical analysis revealed a linear correlation between the trabecular bone density and the ...

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AIM: To define the value of digital radiography with a clinical flat panel detector system for evaluation of wrist fractures in comparison with state of the art storage phosphor radiography. MATERIAL AND METHODS: Hard copy images of 26 fractured wrist specimens were acquired with the same exposure dose on a state of the art storage phosphor radiography system and a clinical flat panel detector. Image features like cortical bone surface, trabecular bone, soft tissues and fracture delineation were independently analysed by 4 observers using a standardised protocol. Image quality ratings were evaluated with an analysis of variance (ANOVA). RESULTS: Flat panel detector radiographs were rated superior with respect to cortical and trabecular bone representation as well as fracture evaluation, while storage phosphor radiographs produced better soft tissue detail. CONCLUSION: In some of the observed image ...

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Strain rate effects for the high strength, metastable beta-titanium alloy Ti-8Mo-8V-2Fe-3Al are assessed in terms of tensile and fracture toughness behavior. It is shown that as the strain rate increases the yield strength, ultimate tensile strength, and ductility also increase. As a result of the decrease in the amount of intergranular fracture as the strain rate is increased, the dynamic fracture toughness values K/sub Id/ are greater than those obtained under static conditions as given by K/sub Q/.

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Two patients with femoral neck fractures, one displaced and one undisplaced, are presented. Preoperative intravital staining with tetracycline and Tc-MDP scintimetry both showed intact femoral head circulation while Tc-MDP-scintimetry 1 week after operation showed pronounced circulatory deficiency. SR"8"5-scintimetry performed at the same time was inconclusive. Segmental collapse was observed radiographically, 8 and 12 months postoperatively. The major vascular injury resulting in avascularity most probably occured during the procedure of osteosynthesis, and Tc-MDP-scintimetry was found suitable for early postoperative recognition of avascular necrosis in both fractures. (author).

Science.gov (United States)

[12] Kusy, R. P. and Turner, D. T.: Influence of molecular-weight ofpoly(methyl methacrylate)on fracture morphology in notched tension, Polymer. ...

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... University, Fracture and Reliability Research Institute, Sendai, Miyagi (Japan)

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1972. United States Narayanan, GH Archbold, TF Univ. of California Press.;

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Purpose: To evaluate MR imaging of the hip in patients with a clinically suspected impacted fracture of the femoral neck in cases where conventional plain films show negative or equivocal findings. Material and Methods: Twenty-seven such patients were prospectively examined by MR imaging with a 1.0 T unit, within 24 hours of admittance to hospital. A coronal T1-weighted turbo spin-echo sequence (n=27), and a coronal STIR sequence (n=25) or a coronal T2-weighted turbo spin-echo fast saturation sequence (n=2) were used. The evaluations were made by 2 radiologists with experience in musculoskeletal radiology. Results: There were 6 patients with a petrochanteric fracture, 2 without and 4 with slight displacement. Five patients had an impacted fracture of the femoral neck, and 3 had a fracture of the superior pubic bone. Of 2 patients with advanced arthrosis, i had an impacted femoral neck ...

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To evaluate injury patterns of facet joints and associated soft tissue injuries in patients with acute traumatic cervical facet joint injuries. From among patients with cervical spine trauma, 27 with facet joint injuries, as seen on CT and MRI, were chosen for this study. CT scans were analyzed with regard to the location of facet joint injury, the presence or absence of facet dislocation or fracture, and other associated fractures. MR images were analyzed with regard to ligament injury, intervertebral disc injury, intervertebral disc herniation, and spinal cord injury. The most common location of facet joint injury was C6-7 level(n=10), followed by C5-6(n=8). Among these 27 patients with facet joint injuries, 12(44%) had bilateral injuries and 15(56%) unilateral injuries. Facet fractures were present in 17 cases(63%) and the fracture of inferior facet was more frequent than superior. Patterns of ...

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The authors propose a method for determining the risk of femoral neck fracture in osteoporotic patients that is not based on densitometric techniques. The method is based on a structural analysis performed by a computer on data taken from a single digital anteroposterior projection of the hip. From the image, the effective cross-sectional area and cross-sectional moment of inertia are computed from attenuation principles. Together with other geometric measurements, these data are used in an engineering analysis to compute the yield strength of the proximal femur, under stress applied through the acetabulum in a one-legged stance. An index of fracture risk based on the ratio of estimated yield strength to body weight is proposed. Ultimately it is expected that this work will allow the clinician to estimate hip fracture risk in osteoporotic patient using widely available existing technology, a goal which has eluded bone ...

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Background There is increasing recognition that lower nurse staffing levels are associated with higher morbidity and mortality among medical and surgical patients. The degree to which this applies to elderly patients with hip fractures is unclear. Questions/purposes We conducted a pilot study using administrative data as an initial step in investigating the relationship between nurse staffing levels and in-hospital mortality among elderly patients with hip fractures. Patients and Methods We retrospectively reviewed administrative data for 13,343 patients 65?years or older with a primary diagnosis of hip fracture admitted to 39 Michigan hospitals between 2003 and 2006. We used logistic regression to calculate the change in predicted probability of in-hospital death conferred by differences ...

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Development drilling from Chevron-operated Platform Hermosa, located on OCS-P 0316 of the Point Arguello field, began on January 30, 1987. To date, seven development wells have been drilled in to the northwest-southeast-trending, doubly plunging anticlinal structure. The results from drilling have confirmed the presence of intense folding and fracturing in the targeted Monterey Formation. Over 700 ft of conventional core were recovered from the B-2 well in the lower Sisquoc and Monterey Formations. Analysis of the core material has yielded important information on lithologic variations and fracture patterns in the productive Monterey Formation. Initial results of core studies, DST data, and wireline studies indicate a correlation between rock type and fracturing. Fracture trends and directional permeability suggested by drill-stem testing may affect future drilling patterns in the field.

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ABSTRACT Crack tip opening angle (CTOA) is becoming one of the most accepted methods for characterizing fully plastic fracture. It provides a measure of the resistance to fracture for a material in cases where there is a large degree of stable-tearing crack extension during the fracture process. Our current pipeline research uses the CTOA test as an alternative, or addition, to the CTOD (crack tip opening displacement) and the fracture energy characterization provided by the J-integral approach. A test technique was developed for measurement of CTOA that uses a modified double cantilever beam (MDCB) specimen. A digital camera and image analysis software were used to record the progression of the crack tip and to estimate the CTOA. In this article, CTOA data on crack growth orientations per...

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Experimental results of quasi-static and dynamic fracture of particle-filled polymer composite (PFPCM) "ALTUGLAS EI CH25" with a matrix of polymethylmethacrylate (PMMA) are reported in this paper. PMMA matrix is filled with rubber particles, as result a shock-resistant transparent composite is produced. The main task was to investigate experimentally and theoretically the fracture toughness of this composite under static and dynamic loading. A high-rate loading has been created by impulse magnetic field. Analysis of fracture process and its relation with the load parameters and material microstructure have been established. Application of the original testing method enabled determination of fracture toughness at very short loading times and comparison of the results with material dynamic p...

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Addition of the silane PPh[sub 2]CH[sub 2]CH[sub 2]SiMe[sub 2]H (chelH, 1a) to Pt(COD)[sub 2] (COD = cycloocta-1,5-diene) affords in high yield the cis-bis chelate Pt(chel)[sub 2] (2); formation of the same product from Pt(COD)(X)Y (X = Y = Me; X = Me, Y = Cl) has been shown by NMR spectroscopy ([sup 1]H, [sup 31]P, [sup 195]Pt) to proceed via prior coordination of chelH through P to afford Pt(chelH)[sub 2](X)(Y) (cis and trans isomers) and through intermediacy of PtH(chel)[sub 2]Cl (22) in which P trans to Si at Pt(IV) leads to an exceptionally low [sup 2]J(Pt-P) = 1084 Hz. Cleavage of Pt-Si bonds in 2 by HCl can be controlled to give the monochelate species Pt(chel)(chelH)Cl (7), from which chelH is displaced by PMe[sub 2]Ph, or trans-PtH(PPh[sub 2]CH[sub 2]SiMe[sub 2]Cl)[sub 2]Cl (9). Products related to 9 result from Pt-Si bond cleavage by I[sub 2] or MeI. Using the analogue PPh[sub 2]CH[sub 2]CH[sub 2]SiMe(Ph)H (1c) of 1a, the analogue ...

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Two no-carrier-added "1"2"5I-labelled photoaffinity rapamycin analogs were prepared: 7-demethoxy-7-(4-azido-3-"1"2"5I-benzyloxy) rapamycin and its C_2_8-C_2_9 seco analog. The key reactions of the synthesis were substitution of the C_7 methoxyl of rapamycin with 4-azido-3-tributylstannylbenzyloxy group, exchange of tributyltin with "1"2"5I using Na"1"2"5I and Chloramine-T, and a ZnCl_2 mediated retro-Aldol cleavage of the C_2_8-C_2_9 bond of rapamycin. (author).

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Abstract:- Increased expression of matrix metalloproteinase (MMP)-2, -3 and -9 has been demonstrated in Crohn-s disease fistulas, but it is unknown whether these enzymes are biologically active and represent a therapeutic target. Therefore, we investigated the proteolytic activity of MMPs in fistula tissue and examined the effect of inhibitors, including clinically available drugs that beside their main action also suppress MMPs. Fistula specimens were obtained by surgical excision from 22 patients with Crohn-s disease and from 10 patients with fistulas resulting from other causes. Colonic endoscopic biopsies from six controls were also included. Total functional MMP activity was measured by a high-pressure liquid chromatography (HPLC)-based, fluorogenic MMP-substrate cleavage assay, and t...

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Nowadays, the studies are focused on the search of better electrocatalysts that promote the complete oxidation of ethanol/bioethanol to CO2. To that end, amorphous bi-catalytic catalysts of composition Ni59Nb40Pt1-xYx (Y=Cu, Ru, x=0.4% at.) have been developed, obtained by mechanical alloying, resulting in higher current densities and an improvement in tolerance to adsorbed CO vs. Ni59Nb40Pt1 catalyst. By using voltammetric techniques, the appearance of three oxidation peaks can be observed. The first peak could be associated with the electrooxidative process of ethanol/bioethanol to acetaldehyde, the second peak could be the oxidation of acetaldehyde to acetic acid, and the last peak might be the final oxidation to CO2. Chrono-amperometric experiments show qualitative poisoning of catalyt...

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Colorectal cancer is the second most common cause of cancer death in the world and about half of the patients with colorectal cancer require adjuvant therapy after surgical resection. Therefore, the eradication of cancer cells via chemotherapy constitutes a viable approach to treating patients with colorectal cancer. In this study, the effects of bufalin isolated from a traditional Chinese medicine were evaluated and characterized in HT-29 and Caco-2 human colon cancer cells. Contrary to its well-documented apoptosis-promoting activity in other cancer cells, bufalin did not cause caspase-dependent cell death in colon cancer cells, as indicated by the absence of significant early apoptosis as well as poly(ADP-ribose) polymerase and caspase-3 cleavage. Instead, bufalin activated an autophagy...

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The concept of unstable burst fracture has been discussed since over 50 years and this injury has received much attention in the literature as regards its radiological diagnosis and clinical treatment. The purpose of this article is to review the way we use imaging to diagnose the injury and to guide treatment.

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The radiation life time of reactor pressure vessel (RPV) is the most important limiting factor for the term of exploitation of the whole power unit. The main degradation mechanism of RPV metal is the neutron induced embrittlement. Processes of radiation ageing running in RPV metal lead to fracture toughness decrease and to increased probability of brittle fracture of the vessel under thermal shocks. This explains the importance of RPV integrity assessment and rest life time management

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A selected series of 24 patients with displaced medial femoral neck fracture, treated with closed reduction and osteosynthesis with cancellous bone screws (ASIF), were investigated. During an observation period of 6 to 26 months, serial hip joint scintigraphies were performed and compared with serial X-ray examinations. At the first scintigraphic examination performed on average 5-6 weeks after the fracture, two separate investigators found a decreased amount of activity or no activity in the femoral head of 10 and 8 patients, respectively. At the second scintigraphic examination performed on average 11.1 weeks after the fracture both investigators found no activity or a decreased amount of activity in 8 patients. This figure declined to 7 during the following period, because one patient with decreased activity was recorded as having normal activity 15 months after the fracture. These 7 patients all ...

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This book provides an analysis of pathophysiologic concepts of trauma and reviews the effectiveness of the available imaging modalities in acute trauma of various organ system. Topics covered are chest injuries; abdominal trauma; fractures of long bones; the foot and ankle; the knee; hand and wrist; the elbow; the shoulder; the pelvis hips; the spine; the skull and facial trauma and the clinical assessment of multiple injuries patients. Comparative evaluation of diagnostic techniques of radiography is discussed. Normal anatomy and bone fractures along with soft-tissue injuries are described.

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In accordance with the Nuclear Regulatory Commission regulation regarding groundwater travel times at geologic repositories, various models of unsaturated flow in fractured tuff have been developed and implemented to assess groundwater travel times at the potential repository at Yucca Mountain, Nevada. Kaplan used one-dimensional models to describe the uncertainty and sensitivity of travel times to various processes at Yucca Mountain. Robey and Arnold et al. used a two-dimensional equivalent continuum model (ECM) with inter- and intra-unit heterogeneity in an attempt to assess fast-flow paths through the unsaturated, fractured tuff at Yucca Mountain (GWTT-94). However, significant flow through the fractures in previous models was not simulated due to the characteristics of the ECM, which requires the matrix to be nearly saturated before flow through the fractures is initiated. In the current study ...

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A 2-year follow-up regarding healing complications, such as redisplacement, nonunion, and segmental collapse of the femoral head, was performed in 306 patients operated on for femoral neck fracture and examined with "9"9"mTechnetium-MDP scintimetry within 2 weeks postoperatively. Scintimetric evaluation was performed by selecting regions of interest over the femoral head on the fracture side and the intact side and by comparing the uptake. A femoral head ratio fractured/intact side thus was obtained. Of 199 patients with an intact femoral head uptake (ratio #<=# 1.0), 181 showed no signs of healing complications at 2 years, whereas 18 had developed healing complications. Of 107 cases with a deficient femoral-head uptake (ratio < 1.0), 96 had developed healing complications within 2 years from the operation, while 11 cases had no signs of radiographic complications. We conclude that "9"9"mTc-MDP scintimetry performed ...

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Three kinds of thin AZ31 wrought magnesium alloys sheets were used in order to investigate the influence of the second phase particles on fracture toughness. From the theoretical model, the ratio of {lambda}{sub p}/d{sub p} would be estimated 5 {proportional_to} 6. On the other hand, from the microstructural observation, average particle spacing on each material was sample A: 13.1 {mu}m, sample B: 14.1, and sample C: 12 {mu}. In addition, average particle size on each sample was sample A: 2.1, sample B: 1.9, and sample C: 2.3 {mu}m. Therefore, the ratio of {lambda}{sub p}/d{sub p} calculated from fracture surface observation would be predicted 6 {proportional_to} 7. In comparison with the result of the prediction by theoretical analysis was in good agreement with the result of fracture toughness observation. It was found that the variation in plane-strain fracture toughness on AZ31 were affected by both ...

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Femoral head vitality before, during and at various intervals from the operation was determined by tetracycline labeling and/or _9_9 sp (m)Tc-MDP scintimetry. In a three-year follow-up, healing prognosis could be determined by scintimetry 3 weeks from operation; deficient femoral head vitality predicting healing complications and retained vitality predicting uncomplicated healing. A comparison between pre- and postoperative scintimetry indicated that further impairment of the femoral head vitality could be caused by the operative procedure, and as tetracycline labeling prior to and after fracture reduction in 370 fractures proved equivalent, it was concluded that the procedure of osteosynthesis probably was responsible for capsular vessel injury, using a four-flanged nail. The four-flanged nail was compared with a low-traumatic method of osteosynthesis, two hook-pins, in a prospective randomized 14 month study, and the postoperative femoral ...

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A solar thermophotovoltaic (STPV) system has both terrestrial and space applications because thermal energy storage can be utilized. Excellent properties (heat of fusion=1800 j/gm and melting temperature=1680 K) make silicon the ideal thermal storage material for an STPV system. Using a one dimensional model with tapering of the silicon storage material, it was found that several hours of running time with modest lengths ({approximately}15 cm) of silicon are possible. Calculated steady-state efficiencies for an STPV system using an Er-YAG selective emitter and ideal photovoltaic (PV) cell model are in the range of 15{percent}{endash}17{percent}. Increasing the taper of the storage material improves both efficiency and power output. {copyright} {ital 1996 American Institute of Physics.}

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Application of an optimization technique to extract the non-ideal parameters of gas absorption with chemical reactions process was described. The gas absorption was modeled using mass transfer theory to represent the realistic behaviors of an absorber. The model was a highly non-linear iterative model which correlated the overall rate of absorption as the function of unknown non-ideal parameters, including the physical liquid mass transfer coefficient and the wetted interfacial area of of packings. The optimization program was developed to minimize the sum of squares of relative errors between the model predictions and the experimental data. Four sets of experimental data (case studies) with different operating conditions were used for extracting parameters. Comparisons between predicted and experimental measured overall absorption rate were in good agreement, average absolute value of relative errors not exceeding 5.4 %. 18 refs., 3 tabs., 4 ...

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Ideal free distribution (IFD) models are perhaps the group of mathematical models of behavior that have been the most widely and successfully applied by empiricists. These models can be applied to nearly any situation in which consumers compete?by any mechanism?for resources that are patchily distributed in their environment. Although IFD models have come to be broadly accepted, experiments that simultaneously test more than a single prediction are rare. Instead, investigators normally either test (1) for a relationship between the distribution of consumers and the distribution of resources or (2) whether average fitnesses are equal across resource patches. We conducted experiments with pea aphids (Acyrthosiphon pisum Harris) feeding on two patches of fava beans (Vicia faba L.) to fully in...

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In association with excavation of the No. 135 steam producing well in the Onikubi geothermal power plant in Miyagi Prefecture, shapes of production zones and drilling-induced fracture (DIF) were acquired from the borehole televiewer (BHTV) data. The BHTV logging shoots sound waves onto well walls of wells filled with fluid and detects the reflection waves to investigate the state of the well walls. Vertical fracture with opening lengths from 2 to 3 m were found at depths of about 1232 m and 1312 m. Water run-off has occurred at a depth of about 1312 m during the excavation, to which these vertical fractures might have contributed possibly. In depths of about 1232 m and 1312 m, fractures inclining toward north-east direction and south-west direction are predominant. Some fractures in the depth of about 1333 m incline toward east-south-east direction and west-north-west direction. ...

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In order to achieve micro-wound, intelligence and high efficiency for fracture setting, intelligent setting system for fracture is proposed in accordance with biomechanics and fracture therapy theory. In the comprehensive medical system based on C-shape-arm X-machine, image processing and analysis is the core, programmable logical controller and stepping motor are important driving parts controlling mechanical parts. Six degree of freedom dynamics sensor ensures to control accurately force and moment. On the foundation of analyzing X-ray image peculiarities, method of processing and analysis is put forward, combining time domain with frequency domain. After mining domain knowledge in depth, setting actions is quantized into three non-continuous steps and is parameterized into two angles and one distance aiming at femoral-neck fracture. Objective features are extracted by virtue of three power ...

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In allusion to the explosion of a urea reactor took place in a fertilizer plant at Pingyin, Shandong, China, a series of evidence collection and inspection jobs which includes collecting operation condition and parameters, sampling the explosion fracture, reactor body apart from explosion fracture, and leak detection medium and its hangover, etc., had been carried out firstly. Based on these jobs, farther analysis and computation work has been done to the structural and materials characteristics and the operation condition of the urea reactor, including compositions, metallographic phases, tensile properties, impact energy, strain ageing characteristics, and fracture toughness of the urea reactor steels, the compositions of leak detection medium and its hangover in the urea reactor, and ex...

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Million-atom molecular-dynamics (MD) simulations are performed to study the structure, mechanical properties, and dynamic fracture in nanophase Si{sub 3}N{sub 4}. The authors find that intercluster regions are highly disordered: 50% of Si atoms in intercluster regions are three-fold coordinated. Elastic moduli of nanophase Si{sub 3}N{sub 4} as a function of grain size and porosity are well described by a multiphase model for heterogeneous materials. The study of fracture in the nanophase Si{sub 3}N{sub 4} reveals that the system can sustain an order-of-magnitude larger external load than crystalline Si{sub 3}N{sub 4}. This is due to branching and pinning of the crack front by nanoscale microstructures.

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The electrochemical behaviour and fracture morphology of homogenized and sensitized type SAE 304 stainless steel U bent specimens, in 3% NaCl solution, at pH=2.0 and pH=7.0 both at room temperature and 100"0C was studied. Polarization curves, galvanostatic and potentiostatic experiments were run. It could be observed that high temperature and low pH favour transgranular cracking and longer sensitization times lower fracture time and tend to give rise to intergranular fracture. Light sensitization can produce transgranular cracking even at room temperature, when the homogenized alloy does not present stress-corrosion cracking for the same condition. (Author).

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In the paper results of the investigation on the effect of microstructure on room temperature tensile properties and fracture toughness of two-phase #alpha#+#beta# titanium alloy Ti-6Al-2Mo-2Cr have been presented. Microstructure has been varied by changes in the cooling rate from the solution treatment temperature and aging time and temperature. Mechanical properties examined show dependence on the treatment conditions, especially aging conditions. It has been attributed mainly to the amount and morphology of #alpha# phase obtained after heat treatment. The higher volume fraction of lamellar #alpha# structure, the higher fracture toughness. (author)

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... Another solution, hybrid vehicles, combine two sources of energy (electric and chemical), reducing the global consumption of fossil fuels. Fuel cell vehicles are also one of the most promising technologies for the future, with the capacity to use any fuel - hydrogen being the ideal fuel ecologically, but constrained by infrastructure and storage issues. This book explores all these different solutions for moving our vehicles from fossil ...

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Momentum- and speed-dependent Maxwell-Boltzmann equilibrium distributions have been derived for tachyons and compared with the corresponding relativistic distributions. This is followed by a calculation of the mean, most probable and r.m.s. speeds for both the relativistic and tachyonic distributions. The ideal gas of tachyons is discussed, including calculations of the internal energy and entropy. In each case a comparison is made with the corresponding bradyonic results. It is found that tachyons behave just like bradyons in the high-temperature limit, but have markedly different behaviour at low temperatures.

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It is maintained that special features of FFTF make it an ideal system to test sodium boiling detection techniques by acoustic/neutronic methods and to test the response of acoustic/neutronic sensors to vibrations. It is shown that accumulated research results indicate that such tests in FFTF are feasible, predictable, promising and safe. (author).

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...Butley river and Ore estuary, Boyton Marshes attracts breeding wading birds in spring and ducks, geese and swans in winter. It's also ... During spring and autumn, it is an ideal place to see migrant wading birds, gulls and terns. Insh Marshes Insh ... Spring is also an excellent time to visit. Leighton Moss Leighton Moss is the largest reedbed in north-west England, and home ... When they leave in spring, wading birds take centre stage. Watch it all take place from our viewing centre and hide,...

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In a reactor environment, the surface of a limiter or wall is primarily determined by the mechanism of erosion and deposition of surface material. It should be possible to use pellet injection to reduce net erosion to zero everywhere if low-Z materials are used for the surface. Erosion rates can, in general, be minimized by large area limiters and high plasma temperatures, which transmit power to the walls with less sputtering. Under ideal steady state conditions the wall surface is dominated by metallurgical effects in the wall.

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Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) has been proposed several years ago as an approach for quantitative analysis of Laser-Induced Breakdown Spectroscopy spectra. Recently developed refinement of the spectral processing method is described in the present work. Accurate quantitative results have been demonstrated for several metallic alloys. However, the degree of accuracy that can be achieved with Calibration-Free Laser-Induced Breakdown Spectroscopy analysis of generic samples still needs to be thoroughly investigated. The authors have undertaken a systematic study of errors and biasing factors affecting the calculation in the Calibration-Free Laser-Induced Breakdown Spectroscopy spectra processing. These factors may be classified in three main groups: 1) experimental aberrations (intensity fluctuations and inaccuracy in the correction for spectral efficiency of a detection system), 2) inaccuracy in theoretical parameters used for calculations (Stark ...

UK PubMed Central (United Kingdom)

Background:The manufacturers of oral bisphosphonates (alendronate, risedronate) recommend avoiding use of these drugs in patients with renal impairment. However, many patients who...Full Text Available

UK PubMed Central (United Kingdom)

Secondary caries and restoration fracture remain the two most common problems in restorative dentistry. Release of fluoride ions (F) could be a substantial benefit because F could enrich neighboring...Full Text Available

UK PubMed Central (United Kingdom)

IntroductionIrradiation of normal, non-malignant bone during cancer therapy can lead to atrophy and increased risk of fracture at several skeletal sites, particularly...Full Text Available

Science.gov (United States)

To maintain operational readiness, military personnel engage in vigorous physical and training activities that carry risk for injury. A 1-year prospective cohort study, starting April 1996, was conducted at Fort Bragg, North Carolina among 1,965 members of the 82nd Airborne Division to quantify musculoskeletal injuries. Information collected included type of injury, site, circumstances, and resultant limited duty days. These soldiers suffered 508 overuse injuries (including 38 stress fractures), 1,415 traumatic injuries (including 100 fractures), and 101 unclassified injuries. Injury rates were 6.8% per soldier per month for traumatic injury and 2.4% for overuse injury (totaling 1.2 injuries per soldier per year). Injuries resulted in 22,041 limited duty days, averaging 11 days per injury and 13 days per soldier (4.5% of total workdays). Fractures and stress fractures/reactions produced the most days ...

Science.gov (United States)

The papers contained in this volume provide an overview of recent theoretical and experimental research related to the fracture toughness and fatigue crack growth characteristics of titanium alloys. Topics discussed include room temperature fatigue crack propagation in beta-titanium alloys, fatigue crack growth rate acceleration in alpha+beta Ti alloys, influence of transformed beta microstructures on fatigue crack growth rates in Ti-6Al-4V, and the role of inclusion and pore content on the fracture toughness of powder processed blended elemental Ti-10V-2Fe-3Al. Papers are also presented on fatigue crack growth measurements in an alpha-beta titanium alloy, the effects of thermal processing variation on the properties of Ti-6Al-4V, and the effect of microstructure on ductility and fracture toughness of alpha+beta titanium alloys.

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With regard to a fracture system in the Hijiori hot dry rock artificial reservoir, an attempt was made on an interpretation which integrates different data. Major factors that characterize development and performance of an artificial reservoir are composed of a fracture system in rocks, which acts as circulating water paths, a heat exchange face and a reservoir space. The system relates not only with crack density distribution, but also with cracks activated by water pressure fracturing, cracks generating acoustic emission (AE), and cracks working as major flow paths, all of which are characterized by having respective behaviors and roles. Characteristics are shown on AE cluster distribution, crack distribution, production zone and estimated stress fields. Mutual relationship among these elements was discussed based on the Coulomb`s theory. The most important paths are characterized by distribution of slippery cracks. ...

International Nuclear Information System (INIS)

Dynamic fracture toughness tests were performed on materials which had been subjected to one of three long-time post weld type stress relief heat treatments: 48 hours at 1000/degree/F (538/degree/C), 24 hours at 1125/degree/F (607/degree/C), and 48 hours at 1125/degree/F (607/degree/C). Linear elastic K/sub Id/ results were obtained at low temperatures while J-integral techniques were utilized to evaluate dynamic fracture toughness over the transition and upper shelf temperature ranges. Tensile, Charpy impact, and drop weight nil-ductility transition tests as well as room temperature, air environment fatigue crack growth rate tests (SA508 Cl 2a only) were also performed. The fracture toughness of both materials exceeded the ASME specified minimum reference toughness K/sub IR/ curve. 17 refs.

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Analyses of the date obtained from the instrumented impact test and of its correlation with static and dynamic J integral values and various tensile properties are made in this study. It is shown that a dynamic bending yield load recorded in the instrumented Charpy V test can be easily converted to a dynamic tensile yield stress using Server's equation. It is also possible to estimate a true fracture strain, COD value, and SZW easily if the load point displacement is recorded. Temperature dependency of Charpy V energy and J integral values is rather well simulated by a curve fitting method. However, a half value transition temperture obtained in that method has no physical meaning. Dynamic J sub(ID) is larger than a static J sub(IC) in the ductile fracture range in this study. This rise is proportional to the yield stress ratio sigmasub(yd)/sigmasub(y)(--1.2-1.3). It is found, therefore, that the following relation exists in the both ...

International Nuclear Information System (INIS)

Past elastic-plastic fracture studies for leak-before-break (LBB) assessment of low alloy steel pipings have been focused mostly on the behavior of base metals and their weld metals. In contrast, the heat-affected zone (HAZ) of a welded pipe has not been studied in detail primarily because the size of the HAZ is too small to make specimens for mechanical properties measurements. In this study, microstructural analyses, microhardness tests, tensile tests and J-R tests have been conducted as a function of distance from a fusion line and temperature for HAZ materials of SA106Gr.C low alloy piping steels. For the ferrite-pearlite steels such as SA106Gr.C, the HAZ specimens showed a higher yield strength and fracture toughness compared with those of its base metal. These characteristics, despite of grain coarsening, can be explained by cleaner microstructures of HAZ materials with a finer morphology of carbides compared with pearlitic-ferritic base ...

UK PubMed Central (United Kingdom)

Non-cemented femoral fixation in hip arthroplasty has become the standard of practice in the USA. However, recent literature has brought attention to an increasing incidence of periprosthetic femur...Full Text Available

UK PubMed Central (United Kingdom)

An 82-year-old female, with left femoral neck fracture was scheduled for left hip hemiarthroplasty, under spinal anaesthesia. She had been suffering from diabetes, hypertension, lung cancer and was...Full Text Available

UK PubMed Central (United Kingdom)

The hierarchical arrangement of collagen and mineral into bone tissue presumabley maximizes fracture resistance with respect to the predominant strain mode in bone. Thus, the ability of cortical...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundBallet Dancers have been shown to have a relatively high incidence of stress fractures of the foot and ankle. It was our objective to examine MR imaging patterns of bone...Full Text Available

UK PubMed Central (United Kingdom)

There is increasing evidence of a biochemical link between lipid oxidation and bone metabolism. Paraoxonase 1 (PON1) prevents the oxidation of low-density lipoprotein (LDL) and metabolizes biologically...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This case report makes evident that in a 75 years old patient with a (cured) femoral neck fracture 15 years ago a refracture at the same site following a new trauma could not be detected by conventional X-ray. The follow-up of a radionuclide bone study, however, enabled the dignosis of a refracture. From these findings, it is further evident that the decreased bone metabolism in older patients has to be considered. Thus, although the initial bone scan following the trauma is negative, a follow-up scan should be performed within a 4 day-period.

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The authors present a guide to the imaging of facial fractures. It is illustrated with conventional radiographs and computed tomograms; the magnetic resonance images primarily suggest the potential applications of this technique. This book provides a source of imaging information on facial trauma. A section on pertinent anatomy is followed by a systematic discussion of the common isolated and complex facial fractures. Perspectives are offered on some commonly seen but infrequently described relationships, such as the tripod-LeFort II association. Consideration is also given to related soft-tissue injuries. The book includes a brief chapter on the type and utility of supplementary imaging studies in the evaluation of those intracranial injuries that may occur concurrently.

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Posttraumatic tibia valga is a well-recognized complication following fracture of the upper tibial metaphysis in young children. We present a case of a child who developed a valgus deformity following fracture of the proximal tibia and fibula in which quantitative bone scintigraphy at 5 months after injury demonstrated increased uptake at the proximal tibial growth plate with proportionally greater uptake on the medial side. This finding suggests that the valgus deformity in this patient was due to a relative increase in vascularity and consequent overgrowth of the medial portion of the proximal tibial physis.

Science.gov (United States)

The viability of osteocytes can be demonstrated in sawn decalcified sections of bone by their lactate dehydrogenase activity. In the cancellous bone of the femoral head, the proportion of lacunae containing viable osteocytes decreased from 88 +/- 7% (mean +/- SD) at 10-29 years to 58 +/- 12% (P Ultimate compressive strength did not correlate with osteocyte viability. In the femoral head there is gradual, age-related reduction in osteocyte viability that can be more pronounced in hip fracture. Osteocyte death may affect bone quality by impairing repair of fatigue damage. PMID:8275364

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The crack growth behavior and fracture toughness of two laminated metal composites (6090/SiC/25p laminated with 5182 and ultrahigh-carbon steel laminated with brass) have been studied in both ``crack arrester`` and ``crack divider`` orientations. The mechanisms of crack growth were analyzed and extrinsic toughening mechanisms were found to contribute significantly to the toughness. The influence of laminate architecture (layer thickness and component volume function), component material properties and residual stress on these mechanisms and the resulting crack growth resistance are discussed.

International Nuclear Information System (INIS)

The report summarizes ten years of experience in the analysis and evaluation of ultrasonic testing data measured in turbine and generator rotors. Apart from the information on type, position, size and distribution of flaws, the expert knowledge achieved in an interpretation of ultrasonic signals yields further insight, as e.g.: - Confirmation of assumptions taken as a basis for fracture-mechanical analysis of these flaws with regard to crack initiation and crack growth under low-cycle fatigue conditions (O=0.7-1 Rp 0.2, N<25.000 growth in length); - enhanced information on a correlation of ultrasonic testing data with the real flaw size. (orig.).

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It is known that in size reduction of the granular structure of ferrite and ferrite-pearlite steels the temperature of the transformation from ductile to brittle condition is lowered. This effect can also be caused by an increase in the dispersity of intragrain and intergrain segregations (sulfides, carbonitrides, and segregations of impurity atoms), which accompanies grain size reduction and promotes initiation and propagation of cracks. In order to clarify the mechanism of fracture of steel in the region of the ductile-brittle transition steel 45 with different grain sizes and pearlite morphologies has been investigated.

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The project involved several studies of vesicles and micelles and their constituent surfactants. The primary objective of the project was an elucidation of factors involved in the stabilization and destabilization of vesicles and micelles. Work was performed on seven individual studies. Several different types of novel cleavable surfactants were synthesized, including systems with two chains and two head groups, and their aqueous micelles and vesicles were characterized by methods including dynamic laser light scattering (to give aggregate sizes) and differential scanning calorimetry (to give vesicle bilayer phase transition temperatures). A cleavable surfactant is stable under certain conditions but liable under other conditions with respect to cleavage to give nonsurfactant products and/or other surfactants with different properties. The destruction of several cleavable surfactant-derived aggregates was demonstrated, indicating that they have potential as ...

International Nuclear Information System (INIS)

This report briefly describes the studies on the mechanism of in vivo DNA repairing by the author in Research Reactor Institute, Kyoto Univ. for the past 30 years. First, the ability of UV radiation to induce transformation was investigated with viral DNA. The formation of thymine-thymine dimer was found harmful to organisms and such dimers were removable by UV-radiation at a low frequency. The mutability was determined in three different E.coli strains with mutator gene, mutT, mutS or mutL. The ability to excise 8-oxoguanin developed in primer DNA was deficient in mutT and miss-pairing left after DNA replication could not be recovered in mutL and mutS strains. Further, DNA repairing mechanism was investigated in other microorganisms; single-strand cleavage caused by exposure to BNCB radiation (boron-neutron-captured beam) could not be repaired in E. coli. Whereas for Deinococcus radiodurans, of which survival rate was not decreased by #gamma#-ray radiation at 5 ...

British Library Electronic Table of Contents (United Kingdom)

We describe a method for the analysis of multi-site phosphorylation in serine/threonine (Ser/Thr)-rich protein sequences. Site-specific mutagenesis was used to introduce tryptic cleavage sites in the serine glutamine/threonine glutamine cluster domain (SCD) of the human checkpoint protein kinase (Chk2). The mutant proteins were shown to autophosphorylate on residues that are inducibly phosphorylated when mammalian cells are exposed to ionizing radiation (serine 33/35, serine 516, threonine 68 and threonine 432). Five Ser/Thr clusters within the SCD were flanked by arginine or lysine residues to produce tryptic peptides for nanospray liquid chromatography (nanoLC)/linear quadrupole ion trap Fourier transform ion cyclotron resonance mass spectrometry. Phosphorylation sites were assigned usin...

International Nuclear Information System (INIS)

A comprehensive dataset of NDV genome sequences was evaluated using bioinformatics to characterize the evolutionary forces affecting NDV genomes. Despite evidence of recombination in most genes, only one event in the fusion gene of genotype V viruses produced evolutionarily viable progenies. The codon-associated rate of change for the six NDV proteins revealed that the highest rate of change occurred at the fusion protein. All proteins were under strong purifying (negative) selection; the fusion protein displayed the highest number of amino acids under positive selection. Regardless of the phylogenetic grouping or the level of virulence, the cleavage site motif was highly conserved implying that mutations at this site that result in changes of virulence may not be favored. The coding sequence of the fusion gene and the genomes of viruses from wild birds displayed higher yearly rates of change in virulent viruses than in viruses of low virulence, suggesting that an ...

Science.gov (United States)

In the course of observing by means of Auger spectroscopy graphite gasification reactions catalyzed by metals, it has been found that in the presence of hydrogen, nickel appears to diffuse from the surface into the bulk of the graphite. When potassium is deposited on graphite, it is volatilized above 400/sup 0/C. Surprisingly the production of methane and carbon dioxide from the reaction of graphite and steam was catalyzed by potassium at as low a temperature as 250/sup 0/C. It has been shown that literature on the alkylation of benzene with synthesis gas is erroneous and that the products reported are due to Lewis acid catalyzed cracking of benzene. A novel cobalt mediated, reversible cleavage of a vinyl-hydrogen bond has been discovered. All products from the thermal decomposition of tetralin have been identified. The stereochemistry of cis-1, 2 dihydrotetralin was determined. In the utilization of the water gas shift reaction as a reducing agent for model coal ...

Science.gov (United States)

Besides the multifunctionality, another equally important aspect of nanoparticles is their engineerability to control the geometrical and chemical properties during fabrication. In this work, we exploited this aspect to define asymmetric surface chemistry of an iron oxide nanosphere by controlling the topology of ligand expression on its surface resulting in a particle with two faces, one displaying only amines and the other only thiols. Specifically, amine-functionalized iron oxide nanospheres were attached on a solid support via a crosslinker containing a disulfide bridge. Liberation of the nanosphere using thiolytic cleavage created thiols on the portion of the particle's surface that interacted with the solid support. Employing a solid-phase strategy and a step-by-step addition of particles, the two unique faces on the same nanosphere served as fittings to assemble them into linear nano-chains. Assembly of chains with various lengths and aspect ratios was ...

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As part of studies into the siting of a deep repository for nuclear waste, Swedish Nuclear Fuel and Waste Management Company (SKB) has commissioned the Alternative Models Project (AMP). The AMP is a comparison of three alternative modeling approaches for geosphere performance assessment for a single hypothetical site. The hypothetical site, arbitrarily named Aberg is based on parameters from the Aespoe Hard Rock Laboratory in southern Sweden. The Aberg model domain, boundary conditions and canister locations are defined as a common reference case to facilitate comparisons between approaches. This report presents the results of a discrete fracture pathways analysis of the Aberg site, within the context of the SR 97 performance assessment exercise. The Aberg discrete fracture network (DFN) site model is based on consensus Aberg parameters related to the Aespoe HRL site. Discrete fracture pathways are identified from canister ...

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In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. However, exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). Experimental data are presented on the fracture toughness and crack growth rates (CGRs) of wrought and cast austenitic SSs, including weld heat-affected-zone materials, that were irradiated to fluence levels as high as {approx} 2x 10{sup 21} n/cm{sup 2} (E > 1 MeV) ({approx} 3 dpa) in a light water reactor at 288-300 C. The results are compared with the data available in the literature. The effects of material composition, irradiation dose, and water chemistry on CGRs ...

International Nuclear Information System (INIS)

The 2- and 8-azido trimer 5'-triphosphate photoprobes of 2-5A have been enzymatically synthesized from [#gamma#-"3"2P]2-azidoATP and [#alpha#-"3"2P]8-azidoAPT by 2-5A synthetase from rabbit reticulocyte lysates. Identification and structural determination of the 2- and 8-azido adenylate trimer 5'-triphosphates were accomplished by enzymatic hydrolyses with T2 RNase, snake venom phosphodiesterase, and bacterial alkaline phosphatase. Hydrolysis products were identified by HPLC and PEI-cellulose TLC analyses. The 8-azido photoprobe of 2-5A displaces p_3A_4["3"2P]pCp from RNase L with affinity equivalent to p_3A_3. The 8-azido photoprobe also activates RNase L to hydrolyze poly(U)["3"2P]pCp 50% at 7 /times/ 10/sup /minus/9/ M in core-cellulose assays. The 2- and 8-azido photoprobes and authentic p_3A_3 activate RNase L to cleave 28S and 18S rRNA to specific cleavage products at 10/sup /minus/9/ M in rRNA cleavage assays. The nucleotide binding ...

International Nuclear Information System (INIS)

Ultraviolet light can be used to immobilize biomolecules onto thiol reactive surfaces in order to, e.g., make biosensors. The mechanism involves light-induced formation of free, reactive thiol groups in disulphide containing molecules. This technology allows for the creation of arrays of biomolecules with a high degree of reproducibility, circumventing the need for often expensive nano/micro-dispensing technologies. The ultimate size of the immobilized spots is defined by the focal area of the UV beam. Light-induced immobilization has the added benefit that the immobilized molecules will be spatially oriented and covalently bound to the surface. In this paper, we demonstrate the utility of a sensor array created with the new sensor technology when integrated into a microfluidic system. Protein arrays made using light-induced immobilization showed successful antigen/antibody binding in a flow cell allowing the visualisation of real time binding and enzyme activity. This new technology ...

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Simulations and experiments have been carried out to explore using a plastic scintillator as a dosimetry probe in the vicinity of a pulsed bremsstrahlung source in the range 4 to 20 MeV. Taking advantage of the tissue-equivalent properties of this detector in conjunction with the use of a fast digital signal processor near real-time dosimetry was shown to be possible. The importance of accounting for a broad energy electron beam in bremsstrahlung production, and photon scattering and build-up, in correctly interpreting dosimetry results at long stand-off distances is highlighted by comparing real world experiments with ideal geometry simulations. Close agreement was found between absorbed energy calculations based upon spectroscopic techniques and calculations based upon signal integration, showing a ratio between 10 MeV absorbed dose to 12 MeV absorbed dose of 0.66 at a distance of 91.4 m from the accelerator. This is compared with an ...

Science.gov (United States)

Near-ideal Schottky barrier contacts to n-type Al0.22Ga0.78N have been developed by a two-step surface treatment technique. Plasma etching of the AlxGa1-xN surface prior to Schottky metal deposition, combined with sequential chemical treatment of the etched surface, holds promise for developing high quality low-leakage Schottky contacts for low noise applications and for recessed gate high electron mobility transistors. In this work, the effect of postetch chemical treatment of the n-type Al0.22Ga0.78N surface on the performance of the Ni/Au based Schottky contact has been investigated. Three different types of chemical treatment: viz, reactive ion etching, reactive ion etching plus dipping in hot aqua regia, and reactive ion etching plus dipping in hot KOH, are studied. Detailed current-voltage studies of three different surface treated diodes and a comparison with as-deposited diodes reveal significant improvement in the diode characteristics. The latter surface ...

International Nuclear Information System (INIS)

The feasibility of developing a fusion power monitor based on a fluid activation detector is considered here. The activation fluid may be either a liquid or a gas and its composition can be selected from a number of candidate materials to provide desired activation and decay characterisitcs. Performance calculations indicate that ordinary water would be a nearly ideal activation fluid. The "1"6O(n,p)"1"6N reaction has a threshold at about 10 MeV and a cross section energy dependence giving it a predominant response for unmoderated D-T fusion neutrons. Adequate activation can be obtained at moderate flow rates for remote counting away from the high radiation area of the reactor. The 7.16 sec half-life of "1"6N is ideal for remote counting with subsequent decay in a small hold-up tank to eliminate activity build-up in the recycled water.

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We suggest and describe the use of a binary pseudo-random (BPR) grating as a standard test surface for measurement of the modulation transfer function (MTF) of interferometric microscopes. Knowledge of the MTF of a microscope is absolutely necessary to convert the measured height distribution of a surface undergoing metrology into an accurate power spectral density (PSD) distribution. For an'ideal' microscope with an MTF function independent of spatial frequency out to the Nyquist frequency of the detector array with zero response at higher spatial frequencies, a BPR grating would produce a flat 1D PSD spectrum, independent of spatial frequency. For a'real' instrument, the MTF is found as the square root of the ratio of the PSD spectrum measured with the BPR grating to the'ideal,' spatial frequency independent, PSD spectrum. We present the results from a measurement of the MTF of MicromapTM-570 ...

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Wet limestone scrubbing is once again becoming a popular technology for removal of sulfur dioxide (SO{sub 2}) from power plant emissions. Critical to the operation of wet limestone flue gas desulfurization (FGD) systems is accurate chemical analysis of scrubber solids. The analytical technique of thermogravimetry is ideal for this application, as the instrument can give precise readings of the principal scrubber solids components, calcium sulfite/sulfate hemihydrate, calcium sulfate dihydrate (gypsum), and unused calcium carbonate. The data provides plant chemists, engineers, and operators with information needed to fine-tune scrubber operation and detect process upsets. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Developing a modern electric power sector is necessary for economic growth and development to proceed. Institutions to implement an IRP (integrated resource planning) process do not exist in many countries. Hainan`s economy is growing rapidly with a concomitant increase in electricity demand. This is an ideal time in Hainan`s development to implement an IRP process. The challenge is for Hainan to develop institutions and incentive mechanisms for HEPCO (Hainan Electric Power Co.) to adopt cost-based pricing, run DSM programs, construct renewable generating plants, etc. One proposal is to great a Hainan government-wide IRP committee.

British Library Electronic Table of Contents (United Kingdom)

The paper takes as its starting point the diffusion of ICT applications associated with so-called 'customer relationship management' (CRM). CRM encourages organisations to shift their understanding of customers from an episodic and transaction-based perspective to one that emphasises continuous 'relationship management'. CRM applications thus promise to deliver more, real-time accurate information about consumer habits and behaviours therefore allowing organisations to maximise their extraction of business value. This paper explores the ways in which such inscriptive technologies are not merely referential but also constitutive of contemporary re-presentations and ideals of the consuming subject. Focusing on what we might call the 'digital doubles' of customer relationship management the a...

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A high pressure waterjet has been used to study the surface roughening of superalloys as preparation for thermal spraying. Designed experiments for Mar-M 509 and Rene 80 were carried out for the effects of jet pressure and mass of water delivered per unit area. Comparisons were made of several superalloys in terms of erosion, surface roughness and topology. The mechanism of jet erosion of Rene 80 was studied in relation to its metallurgical microstructure. An MCrAlY coating by shrouded plasma spray was made over a waterjet prepared surface with excellent bonding and having an ideally clean interface.

Science.gov (United States)

A discussion of some of the difficulties with previous analyses of the resistivity of A-15 compounds is given. Precise high-temperature data on ..cap alpha..-particle- and electron-damaged Nb/sub 3/Ge and Nb/sub 3/Sn samples with different defect concentrations are presented here and analyzed in a simple way with use of a phenomenological model based on the idea that the ideal resistivity must approach some limiting value in the regime where the mean free path becomes comparable to the interatomic spacing.

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Trapped ions are a near ideal system to study quantum information processing due to the high degree of control over the ion's external confinement and internal degrees of freedom. We demonstrate the key steps necessary for trapped ion quantum computing and focus on phonon-mediated entangling gates. We highlight several key algorithms implemented over the last decade with these gates and give a detailed description of Grover's quantum database search implemented with two trapped ion qubits.

International Nuclear Information System (INIS)

A thermodynamic model was used to estimate enthalpy of solution of carbon dioxide (CO_2) in methyldiethanolamine (MDEA) aqueous solutions. The model was based on a set of equations for chemical equilibria, phase equilibria, charge, and mass balances. Non-ideality in the liquid phase was taken into account by interaction parameters fitted to (vapor + liquid) equilibrium data. The enthalpies of solution of CO_2 were derived from the model using classical thermodynamic relations and were compared to experimental values obtained in previous works.

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This article gives a survey of the history, properties and applications of 'Kevlar' aramide fibers. For example, the 'Kevlar' para-aramide fiber is used in compound materials in ship-, aircraft- and vehicle construction. 'Kevlar' is used as a replacement for asbestos, for example in brakes, clutches and seals or as rubber reinforcement (tyres, conveyor belts, hoses). The aramide fibers also offer manufacturers of ropes, hawsers and cables a near ideal range of properties. (MM).

British Library Electronic Table of Contents (United Kingdom)

Ascochyta blight causes significant yield loss in pulse crops worldwide. Integrated disease management is essential to take advantage of cultivars with partial resistance to this disease. The most effective practices, established by decades of research, use a combination of disease-free seed, destruction or avoidance of inoculum sources, manipulation of sowing dates, seed and foliar fungicides, and cultivars with improved resistance. An understanding of the pathosystems and the inter-relationship between host, pathogen and the environment is essential to be able to make correct decisions for disease control without compromising the agronomic or economic ideal. For individual pathosystems, some components of the integrated management principles may need to be given greater consideration tha...

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The design of High-Voltage, Direct-Current transmission cables insulated with oil-impregnated cellulose paper is constrained by the maximum temperature and the maximum steady-state and transient stresses (voltage gradients) that the cable insulation can reliably withstand over the desired operating lifetime. Because the electrical stresses in the insulation are related in a very complex fashion to temperature, applied voltage and cable geometry, iterative techniques are required to compute the values of these stresses. Digital computers are ideally suited for these iterative techniques. This paper presents the principal equations and logic needed to develop suitable computer programs.

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In an ideal system the surface of the dish is perfectly parabolic (no contour flaws are present), and the sun rays fall on the dish surface parallel to the focal axis (no sun tracking flaws are present). These two conditions are not realizable in practice; in this case, the parabolic dish system is called real system. In this paper a procedure for analysing the flux distribution on the receiver internal surfaces is presented for a cavity receiver with a real parabolic dish collector. First, the theoretical principles are discussed. Then the effect of the inaccuracy in the collector and in the sun tracking on the insolation pattern is described using an example.

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The development of detailed chemical kinetic reaction mechanisms for analysis of autoignition and knocking of hydrocarbon fuels is described. In particular, kinetic processes of concern for the oxidation of complex hydrocarbon fuel molecules are emphasized. The wide ranges of temperature and pressure which are encountered by end gases in automobile engine combustion chambers result in extreme demands on reaction mechanisms which are intended to describe knocking conditions and predict rates of combustion and ignition. The reactions and chemical species which are most important in each temperature and pressure regime are discussed, and the validation of these reaction mechanisms through comparison with idealized experimental results is described. 53 refs., 8 figs., 5 tabs.

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The linear integral equation based computer code (RON: Roger Oleg Nikolai), which was recently developed at Argonne National Laboratory, was used to calculate the self-amplified spontaneous emission (SASE) performance of the free-electron laser (FEL) being built at Argonne. Signal growth calculations under different conditions are used for estimating tolerances of actual design parameters. The radiation characteristics are discussed, and calculations using an ideal undulator magnetic field and a real measured magnetic field will be compared and discussed.

Science.gov (United States)

A hyperbolic Stefan problem based on the linearized Gurtin-Pipkin heat conduction law is considered. The temperature and free boundary are controlled by a thermostat acting on the boundary. This feedback control is based on temperature measurements performed by real thermal sensors located within the domain containing the two-phase system and/or at its boundary. Three different types of thermostats are analyzed: simple switch, relay switch, and a Preisach hysteresis operator. The resulting models lead to integrodifferential hyperbolic Stefan problems with nonlinear and nonlocal boundary conditions. Existence results are proved in all the cases. Uniqueness is also shown, except in the situation corresponding to the ideal switch.

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This work reviews the differences in fuel economy between two direct injection diesel engine versions through the use of a First Law energy balance and a Second Law availability balance. Both experimental data and simulated results are used in the analysis. The use of an engine simulation allowed the important processes in each engine to be analyzed and a Second Law effectiveness calculated. The availability balances and effectiveness values are used to determine the effect of major engine components on the fuel economy. A comparison is also made with an ideal engine with selected perfect or reversible processes.

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Dual energy X-ray absorptiometry (Hologic QDR-1000) was used to quantitatively analyze the diagnosis and prevention of osteoporosis. The peak bone mineral density (BMD) of the spine appeared in normal men in their twenties and in normal women in their thirties. There was acceleration of bone loss in the 50 to 60 year age bracket (premenopause and postmenopause) in normal women. On the contrary, the peak BMD of the femoral neck in normal men and women appeared in their twenties after which it decreased slightly with age. Comparison showed that the femoral neck BMD of normal women was lower than that of men throughout all ages. The fracture threshold, 0.756 g/cm[sup 2] for the spine, was obtained by scanning 73 females with spinal fractures, the mean BMDs for L2-L4 at the 90th percentile level were used as the fracture threshold. The fracture threshold of femoral neck fracture was the ...

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Volumetric properties of liquid mixtures of neon and hydrogen have been calculated using path integral hybrid Monte Carlo simulations. Realistic potentials have been used for the three interactions involved. Molar volumes and excess volumes of these mixtures have been evaluated for various compositions at 29 and 31.14 K, and 30 atm. Significant quantum effects are observed in molar volumes. Quantum simulations agree well with experimental molar volumes. Calculated excess volumes agree qualitatively with experimental values. However, contrary to the existing understanding that large positive deviations from ideal mixtures are caused due to quantum effects in Ne{endash}H{sub 2} mixtures, both classical as well as quantum simulations predict the large positive deviations from ideal mixtures. Further investigations using two other Ne{endash}H{sub 2} potentials of Lennard{endash}Jones (LJ) type show that excess volumes are very sensitive to the ...

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Secondary ischemic necrosis of femoral head due to loss of blood supply following to femoral neck fracture is well known. The regional distribution of bone-seeking radiopharmaceuricals in the skeleton can depend on a number of factors, but bone blood flow is a major physiological determinant of regional skeletal uptake of Tc-99m polyphosphate and bone imaging may thus be used for the evaluation of vascularity of the femoral head. The authors made a comparative study of scintigraphic findings and operative findings of 28 cases of femoral neck fracture treated at Kyung Hee University Hospital from April 1980 to May 1984. The results were as follows: 1. In 16 cases of proven avascular necorsis of femoral head, scintigraphy showed absent or decreased activity in 14 cases (87.5%), while radiography showed increased density in 10 cases (62.5%). 2. In 12 cases of proven vital femoral head, scintigraphy showed increased activity in 9 cases (75%) and ...

International Nuclear Information System (INIS)

Methodology based on probabilistic fracture mechanics (PFM) is finding increasing acceptability in demonstrating safety of Nuclear Power Plant (NPP) piping. In PFM, the methods of fracture mechanics and reliability theory are combined for assessing the reliability of components, which contain cracks. In this work, reliability assessment of Tarapur Atomic Power Plant (TAPP) 3-4 Primary Heat Transport (PHT) piping is done using PFM. Monte Carlo simulation with stratified sampling is used as a variance reduction technique. PFM model assumes a pre-existing circumferential surface crack before the start of plant operation. The crack grows in size during the lifetime of the plant due to the fatigue loading. This part-through wall crack having escaped hydro-test and pre-service inspection, may result in either a through wall flaw (leak) or may lead to the rupture of the piping. R6 method is used as failure criteria. Steam generator inlet (SGI), steam ...

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Fine-grained AZ31 magnesium alloy sheets were prepared through hot rolling process. The superplastic properties of hot-rolled AZ31 Mg alloy was examined by uniaxial tensile tests at a temperature range 250{proportional_to}450 C and strain rate range 0.7 x 10{sup -3}{proportional_to}1.4 x 10{sup -1} s{sup -1}. Optical and scanning electronic microscope (SEM) were used to observe the microstructure evolution and fracture behavior in superplastic deformation of AZ31 Mg alloy and the values of deformation activation energy at various temperatures were calculated. It is demonstrated that, the hot-rolled AZ31 alloy begins to exhibit superplasticity from 300 C and a maximum elongation of 362.5% is obtained at 400 C and 0.7 x 10{sup -3} s{sup -1}. In the temperature range 300{proportional_to}400 C, the dominant superplastic deformation mechanism is grain boundary sliding (GBS) controlled by grain boundary diffusion and the influence of temperature on the ...

Science.gov (United States)

BACKGROUND: Although definitions vary, infected nonunion has been defined as a state of failure of union and persistence of infection at the fracture site for 6 to 8 months.>). Infected nonunions of the supracondylar region of the femur are uncommon and are mostly due to a severe open fracture with extensive comminution and segmental bone loss or after internal fixation of a comminuted closed fracture. Associated factors include exposed bone devoid of vascularized periosteal coverage for more than 6 weeks, purulent discharge, a positive bacteriological culture from the depth of the wound, and histologic evidence of necrotic bone containing empty lacunae. Soft-tissue loss with multiple sinuses, osteomyelitis, osteopenia, complex deformities with limb-length inequality, stiffness of the adjacent joint, polybacterial multidrug-resistant infection, and smoking all complicate treatment and recovery. Although uncommon in ...

International Nuclear Information System (INIS)

A retrospective study was made of all radionuclide (RN) bone images performed at our institution over a two-year period to evaluate femoral head viability after nonpathologic fracture of the femoral neck. Twelve patients had avascular femoral heads during the perioperative period, of which nine had adequate follow-up. Seven of these nine patients had follow-up bone images. Revascularization occurred in four patients, while three had persistent absence of femoral head uptake. With clinical follow-up ranging from four to 29 months (median: 14 months), only two of these nine patients developed clinical or radiographic evidence of osteonecrosis. RN bone imaging performed in the perioperative period does not reliably predict the development of post-traumatic osteonecrosis of the femoral head and, at present, should not be used to determine prospectively method of treatment of femoral neck fracture.

Science.gov (United States)

Muscular fatigue in the training athlete or military recruit has been hypothesized to cause increased bone strain that may contribute to the development of a stress fracture. Under normal circumstances, muscles exert a protective effect by contracting to reduce bending strains on cortical bone surfaces. In vivo strain studies in dogs show that muscle fatigue following strenuous exercise elevates bone strain and changes strain distribution. However, a similar experiment has yet to be performed in humans. The purpose of this work was to test the hypothesis in humans that strenuous fatiguing exercise causes an elevation in bone strain. It was also hypothesized that this elevation is greater in younger people than in older people due to the decline in muscle strength and endurance that normally occurs with age. To test these hypotheses, strain in the tibiae of seven human volunteers was measured during walking before and after a period of fatiguing exercise. Neither ...

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Purpose: In an experimental study, the correlation between the trabecular bone density of the different regions of the proximal femur and the fracture load in the setting of femoral neck fractures was examined. Methods: The bone mineral density 41 random proximal human femora was estimated by single-energy quanitative CT (SE-QCT). The trabecular bone density was measured at the greatest possible extracortical volume at midcapital, midneck and intertrochanteric level and in the 1 cm{sup 3} volumes of the centres of these regions in a standardised 10 mm thick slice in the middle of the femoral neck axis (in mg/ml Ca-hydroxyl apatite). The proximal femora were then isolated and mounted on a compression/bending device under two-legged stand conditions and loaded up to the point when a femoral neck fracture occurred. Results: Statistical analysis revealed a linear correlation between the trabecular bone density and the ...

International Nuclear Information System (INIS)

AIM: To assess the impact of the introduction of a computed tomography (CT) imaging protocol for multi-trauma patients on the workload, overall diagnostic yield, and effect on detection of cervical spine injury and pneumothorax. METHOD: Between February 1997 and April 2004, all patients presenting acutely to the Emergency Department (ED) with haemodynamically stable trauma (Abbreviated Injury Scale 3 or more) involving more than two body systems were imaged with a comprehensive pre-set helical CT protocol (including non-contrast head, cervical spine: cranio-cervical and cervico-thoracic junctions; and oral and intravenous contrast-enhanced thoracic, abdomen and pelvis) after initial triage and a standard trauma series of radiographs (chest, lateral C-spine and pelvis). Diagnosis of cervical spine fracture and pneumothorax was noted before and after the CT protocol was carried out and findings from all studies were recorded prospectively. RESULTS: Over the 7-year ...

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Participants in the conference selected to attend two different working group sessions. The working groups discussed different perspectives of system-based approaches to osteoporosis and fracture care. The group on postfracture case management recommended that nurse case managers be used to improve communication among patients, orthopaedic surgeons, and those providing ongoing clinical care. The hospital working group discussed the impact of and barriers to improved postfracture management in the hospital setting. The health systems group emphasized the difference between a closed system in which long-term benefits of interventions were more likely to be appreciated than in fee for service systems. The health information technology group discussed the advantages and challenges of electroni...

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Femoral head replacement was performed for femoral neck fracture or femoral head necrosis on 36 hips of 34 patients on whom Tc-99m MDP scintigraphy was done for analysis of radioisotope uptake around the prosthesis. In the cases with satisfactory clinical course after replacement surgery the uptake was high in the area between the prosthesis and the trochanter, in the area of the stem tip of the prosthesis and in the acetabular area. The high uptake decreased gradually and reached a normal level by 8 months after surgery. The cases with no decrease of high uptake by 8 months after surgery were considered to have had an eventful postoperative course associated with some complication such as infection, fracture, loosening etc. Tc-99m MDP scintigraphy was useful for early detection of complications and to evaluate progress of the operated patients. (author)

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The present authors have previously developed a new method for Probabilistic Fracture Mechanics (PFM), which they call Recursive Distribution (RD) method. The method is based on the construction of the Lebesgue-Stieltjes measure through a deterministic mapping defining a crack growth process. In the present paper, its theoretical background is first discussed, and the Lebesgue decomposition of the measure is given. Then a numerical example of a Light Water Reactor (LWR)`s piping problem is solved by the present method, and the results are compared with those of the Monte Carlo (MC) method. In addition to leakage probability, a variation in stress cycles of the marginal distribution of an aspect ratio of a semi-elliptical surface crack is calculated, which will be used in a study on LBB evaluation.

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Even though the currently intensive research efforts on high- temperature superconducting materials have not yet converged on a well specified practical material, the indications are that such a material may be quite brittle, anisotropic, and may contain many flaws such as microcracks and voids at grain boundaries. Consequently, practical applications of high temperature superconducting materials will require a very careful strength analysis based on fracture mechanics considerations. Because of the high sensitivity of the strength of such materials to the presence of defects, methods of quantitative non-destructive evaluation may be expected to play an important role in strength determinations. This proposal is concerned with the use of ultrasonic methods to detect and characterize isolated cracks, clusters of microcracks and microcracks distributed throughout the material. Particular attention has been, and will continue to be devoted to relating ultrasonic ...

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The three tasks were completed during this reporting period. During this quarter, work focused on a local structural analysis of the Table Rock field, greater Green River basin (GGRB) in southwestern Wyoming. The ultimate objective of the local analysis is to apply the techniques developed and demonstrated during earlier phases of the project in the Rulison Field area of the Piceance basin for sweet-spot delineation. The primary goal of this work is to focus in on the Table Rock field area in the northern Washakie basin of the Greater Green River basin in support of Union Pacific Resources and DOE planned horizontal drilling efforts. The work plan for the quarter of April 1, 1998--June 30, 1998 consisted of three tasks: (1) Acquire necessary seismic data and depth-convert, (2) Map major fault geometry and analyze displacement vectors, (3) Develop and initiate a natural fracture prediction study.

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Statement of problem Because noble dental casting alloys for metal ceramic restorations have a wide range of mechanical properties, knowledge of these properties is needed for rational alloy selection in different clinical situations where cast metal restorations are indicated. Purpose The purpose of this study was to compare the mechanical properties and examine both the fracture and polished surfaces of 6 noble casting alloys that span many currently marketed systems. Five alloys were designed for metal ceramic restorations, and a sixth Type GPT has Type IV alloy for fixed prosthodontics (Maxigold KF) was included for comparison. Material and methods Specimens (n=6) meeting dimensional requirements for ISO Standards 9693 and 8891 were loaded to failure in tension using a universal testin...

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Analytical and numerical methods have been used in this investigation to model the behavior of geothermal systems under exploitation. The work is divided into three parts: (1) development of a numerical code, (2) theoretical studies of geothermal systems, and (3) field applications. A new single-phase three-dimensional simulator, capable of solving heat and mass flow problems in a saturated, heterogeneous porous or fractured medium has been developed. The simulator uses the integrated finite difference method for formulating the governing equations and an efficient sparse solver for the solution of the linearized equations. In the theoretical studies, various reservoir engineering problems have been examined. These include (a) well-test analysis, (b) exploitation strategies, (c) injection into fractured rocks, and (d) fault-charged geothermal reservoirs.

International Nuclear Information System (INIS)

A series of SiAlON materials with a cordierite-based matrix were annealed for different lengths of time to cause crystallization of the glass phase. Their fracture toughness, hardness, and elastic modulus were measured from room temperature up to 1100"0C. The fracture toughness generally decreased with temperature. Short time annealing raised toughness at lower temperatures, while further annealing lowered it back to the value for as-hot pressed materials. At higher test temperatures annealing had no effect on toughness. This annealing behavior is significantly different from that previously reported in the system SaAlON-YAG. Hardness decreased monotonically with temperature for all samples. Both hardness and the elastic modulus were not affected by the annealing treatment. At elevated temperatures appreciable scatter of modulus results allowed only a rough trend of decrease with temperature to be observed.

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Purpose. We report a case of Ewing's sarcoma in the right distal femur in a 6-year-old male to demonstrate how dynamic contrast-enhanced magnetic resonance imaging (DEMRI) findings predicted histopathology. Materials and methods. DEMRI was performed at presentation and during and after completion of chemotherapy and radiation therapy. Histopathologic studies were done at presentation, at 77 weeks (20 weeks after a pathological fracture), and from the en bloc resection at 104 weeks. Results. DEMRI predicted the early tumor response, absence of tumor recurrence, presence of necrosis and lack of fracture healing, confirmed by histopathology. Conclusion. DEMRI is a clinically useful tool in managing Ewing's sarcoma. (orig.)

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The nucleation of microdamage under dynamic loading was investigated through planar impact experiments accomplished with a light gas gun. The microscopic observation of recovered and sectioned specimens showed that microcracks were nucleated only by cracking of brittle particles inside material. However, for comparison the in situ static tensile tests on the same material conducted with a scanning electron microscope showed that the microcracks were nucleated by many forms those were fracture of ductile matrix, debonding particles from matrix and cracking of brittle particles. The quantitative metallographic observations of the specimens subjected to impact loading showed that most of the cracked particles were situated on grain boundaries of the aluminum matrix. These facts suggested the concept of critical size and incubation time of submicroscopic cavities in the dynamic case and the mechanism of embryo-damage induced nucleation by fracture ...

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The effect of tsub(A) austenitization temperature in heating for quenching as well as in the cycle of high-temperature thermomechanical treatment (HTMT) on structure, mechanical properties and fracture mode of 40KhN2MA structural steel is investigated. It is shown that heating up to 1200 deg C does not affect essentially sigmasub(b) and sigmasub(0.2) of a quenched material but increases fracture toughness of 200 deg C - tempered precracked specimens and is accompanied by a decrease of impact strength and plasticity of vee-notched specimens. The optimum complex of mechanical properties is attained upon combined treatment comprising heating up to 1200 deg C and HTMT with deformation at 850 deg C.

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A new evaluation of the 1% time strain limit for creep strength and the isochronous stress/strain relationship was to be undertaken for the type 800 alloy, based on up to date experimental data. After the evaluation of the 1% time strain limit curves and time fracture curves of individual melts, multilinear regression analyses were made to clear up the relationship between parameters of the creep behaviour such as creep strength, 1% time strain limit and time fracture strain on the one hand and metallurgical parameters such as C, Ti, Al, Ni, Cr contents or grain size and type of manufacture, on the other hand. Based on the knowledge gained from these calculations, new limits were determined for HTR material specifications for variants of the 800 alloy of the Rk, NT, DE, and HT type. (orig./DG).