Altitude deviations : breakdowns of an error tolerant system

DOT National Transportation Integrated Search

1991-12-01

This project was a demonstration of the use of live aerial video recorded from a rotary wing aircraft operated by the Fairfax County, Virginia Police Department and transmitted to ground stations for re-transmission and use by Fairfax County and Virg...

National Centers for Environmental Prediction

Science.gov Websites

Modeling Mesoscale Modeling Marine Modeling and Analysis Teams Climate Data Assimilation Ensembles and Post and are available via /nwprod/lib: bacio w3 sp nemsio The following will be used only when Post is set : gmake nmm NMM with post: gmake nmm_post GSM only: gmake gsm GSM with post: gmake gsm_post GSM w

Estimate the effective connectivity in multi-coupled neural mass model using particle swarm optimization

NASA Astrophysics Data System (ADS)

Shan, Bonan; Wang, Jiang; Deng, Bin; Zhang, Zhen; Wei, Xile

2017-03-01

Assessment of the effective connectivity among different brain regions during seizure is a crucial problem in neuroscience today. As a consequence, a new model inversion framework of brain function imaging is introduced in this manuscript. This framework is based on approximating brain networks using a multi-coupled neural mass model (NMM). NMM describes the excitatory and inhibitory neural interactions, capturing the mechanisms involved in seizure initiation, evolution and termination. Particle swarm optimization method is used to estimate the effective connectivity variation (the parameters of NMM) and the epileptiform dynamics (the states of NMM) that cannot be directly measured using electrophysiological measurement alone. The estimated effective connectivity includes both the local connectivity parameters within a single region NMM and the remote connectivity parameters between multi-coupled NMMs. When the epileptiform activities are estimated, a proportional-integral controller outputs control signal so that the epileptiform spikes can be inhibited immediately. Numerical simulations are carried out to illustrate the effectiveness of the proposed framework. The framework and the results have a profound impact on the way we detect and treat epilepsy.

NAM - Eta to NMM conversion 20060613

Science.gov Websites

North American Mesoscale (NAM) time slot. Currently the the Eta forecast model is used for the NAM, but Eta and its output will be available at the same time. There will be some minor addition of products MB per file (time step). - The following fields will be added: - omega @ 10, 20, & 30 mb - height

Reverse Dynamization: Influence of Fixator Stiffness on the Mode and Efficiency of Large-Bone-Defect Healing at Different Doses of rhBMP-2.

PubMed

Glatt, Vaida; Bartnikowski, Nicole; Quirk, Nicholas; Schuetz, Michael; Evans, Christopher

2016-04-20

Reverse dynamization is a technology for enhancing the healing of osseous defects. With use of an external fixator, the axial stiffness across the defect is initially set low and subsequently increased. The purpose of the study described in this paper was to explore the efficacy of reverse dynamization under different conditions. Rat femoral defects were stabilized with external fixators that allowed the stiffness to be modulated on living animals. Recombinant human bone morphogenetic protein-2 (rhBMP-2) was implanted into the defects on a collagen sponge. Following a dose-response experiment, 5.5 μg of rhBMP-2 was placed into the defect under conditions of very low (25.4-N/mm), low (114-N/mm), medium (185-N/mm), or high (254-N/mm) stiffness. Reverse dynamization was evaluated with 2 different starting stiffnesses: low (114 N/mm) and very low (25.4 N/mm). In both cases, high stiffness (254 N/mm) was imposed after 2 weeks. Healing was assessed with radiographs, micro-computed tomography (μCT), histological analysis, and mechanical testing. In the absence of dynamization, the medium-stiffness fixators provided the best healing. Reverse dynamization starting with very low stiffness was detrimental to healing. However, with low initial stiffness, reverse dynamization considerably improved healing with minimal residual cartilage, enhanced cortication, increased mechanical strength, and smaller callus. Histological analysis suggested that, in all cases, healing provoked by rhBMP-2 occurred by endochondral ossification. These data confirm the potential utility of reverse dynamization as a way of improving bone healing but indicate that the stiffness parameters need to be selected carefully. Reverse dynamization may reduce the amount of rhBMP-2 needed to induce healing of recalcitrant osseous lesions, reduce the time to union, and decrease the need for prolonged external fixation. Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.

Stability of radial head and neck fractures: a biomechanical study of six fixation constructs with consideration of three locking plates.

PubMed

Burkhart, Klaus Josef; Mueller, Lars P; Krezdorn, David; Appelmann, Philipp; Prommersberger, Karl J; Sternstein, Werner; Rommens, Pol M

2007-12-01

Open reduction and internal fixation of radial neck fractures can lead to secondary loss of reduction and nonunion due to insufficient stability. Nevertheless, there are only a few biomechanical studies about the stability achieved by different osteosynthesis constructs. Forty-eight formalin-fixed, human proximal radii were divided into 6 groups according to their bone density (measured by dual-energy x-ray absorptiometry). A 2.7-mm gap osteotomy was performed to simulate an unstable radial neck fracture, which was fixed with 3 nonlocking implants: a 2.4-mm T plate, a 2.4-mm blade plate, and 2.0-mm crossed screws, and 3 locking plates: a 2.0-mm LCP T plate, a 2.0-mm 6x2 grid plate, and a 2.0-mm radial head plate. Implants were tested under axial (N/mm) and torsional (Ncm/ degrees ) loads with a servohydraulic materials testing machine. The radial head plate was significantly stiffer than all other implants under axial as well as under torsional loads, with values of 36 N/mm and 13 Ncm/ degrees . The second-stiffest implant was the blade plate, with values of 20 N/mm and 6 Ncm/ degrees . The weakest implants were the 2.0-mm LCP, with values of 6 N/mm and 2 Ncm/ degrees , and the 2.0-mm crossed screws, with values of 18 N/mm and 2 Ncm/ degrees . The 2.4-mm T plate, with values of 14 N/mm and 4 Ncm/ degrees , and the 2.0-mm grid plate, with values of 8 N/mm and 4 Ncm/ degrees came to lie in the midfield. The 2.0-mm angle-stable plates-depending on their design-allow fixation with comparable or even higher stability than the bulky 2.4-mm nonlocking implants and 2.0-mm crossed screws.

Reverse Dynamization

PubMed Central

Glatt, Vaida; Bartnikowski, Nicole; Quirk, Nicholas; Schuetz, Michael; Evans, Christopher

2016-01-01

Background: Reverse dynamization is a technology for enhancing the healing of osseous defects. With use of an external fixator, the axial stiffness across the defect is initially set low and subsequently increased. The purpose of the study described in this paper was to explore the efficacy of reverse dynamization under different conditions. Methods: Rat femoral defects were stabilized with external fixators that allowed the stiffness to be modulated on living animals. Recombinant human bone morphogenetic protein-2 (rhBMP-2) was implanted into the defects on a collagen sponge. Following a dose-response experiment, 5.5 μg of rhBMP-2 was placed into the defect under conditions of very low (25.4-N/mm), low (114-N/mm), medium (185-N/mm), or high (254-N/mm) stiffness. Reverse dynamization was evaluated with 2 different starting stiffnesses: low (114 N/mm) and very low (25.4 N/mm). In both cases, high stiffness (254 N/mm) was imposed after 2 weeks. Healing was assessed with radiographs, micro-computed tomography (μCT), histological analysis, and mechanical testing. Results: In the absence of dynamization, the medium-stiffness fixators provided the best healing. Reverse dynamization starting with very low stiffness was detrimental to healing. However, with low initial stiffness, reverse dynamization considerably improved healing with minimal residual cartilage, enhanced cortication, increased mechanical strength, and smaller callus. Histological analysis suggested that, in all cases, healing provoked by rhBMP-2 occurred by endochondral ossification. Conclusions: These data confirm the potential utility of reverse dynamization as a way of improving bone healing but indicate that the stiffness parameters need to be selected carefully. Clinical Relevance: Reverse dynamization may reduce the amount of rhBMP-2 needed to induce healing of recalcitrant osseous lesions, reduce the time to union, and decrease the need for prolonged external fixation. PMID:27098327

Strength properties of interlocking compressed earth brick units

NASA Astrophysics Data System (ADS)

Saari, S.; Bakar, B. H. Abu; Surip, N. A.

2017-10-01

This study presents a laboratory investigation on the properties of interlocking compressed earth brick (ICEB) units. Compressive strength, which is one of the most important properties in masonry structures, is used to determine masonry performance. The compressive strength of the ICEB units was determined by applying a compressive strength test for 340 units from four types of ICEB. To analyze the strength of the ICEB units, each unit was capped by a steel plate at the top and bottom to create a flat surface, and then ICEB was loaded until failure. The average compressive strength of the corresponding ICEB units are as follows: wall brick, 19.15 N/mm2; beam brick, 16.99 N/mm2; column brick, 13.18 N/mm2; and half brick, 11.79 N/mm2. All the ICEB units had compressive strength of over 5 N/mm2, which is the minimum strength for a load-bearing brick. This study proves that ICEB units may be used as load-bearing bricks. The strength of ICEBs is equal to that of other common bricks and blocks that are currently available in the market.

Effects of mannan oligosaccharide and virginiamycin on the cecal microbial community and intestinal morphology of chickens raised under suboptimal conditions.

PubMed

Pourabedin, Mohsen; Xu, Zhengxin; Baurhoo, Bushansingh; Chevaux, Eric; Zhao, Xin

2014-05-01

There is an increasing movement against use of antibiotic growth promoters in animal feed. Prebiotic supplementation is a potential alternative to enhance the host's natural defense through modulation of gut microbiota. In the present study, the effect of mannan oligosaccharide (MOS) and virginiamycin (VIRG) on cecal microbial ecology and intestinal morphology of broiler chickens raised under suboptimal conditions was evaluated. MOS and VIRG induced different bacterial community structures, as revealed by denaturing gradient gel electrophoresis of 16S rDNA. The antibiotic treatment reduced cecal microbial diversity while the community equitability increased. A higher bacterial diversity was observed in the cecum of MOS-supplemented birds. Quantitative polymerase chain reaction results indicated that MOS changed the cecal microbiota in favor of the Firmicutes population but not the Bacteroidetes population. No difference was observed in total bacterial counts among treatments. MOS promoted the growth of Lactobacillus spp. and Bifidobacterium spp. in the cecum and increased villus height and goblet cell numbers in the ileum and jejunum. These results provide a deeper insight into the microbial ecological changes after supplementation of MOS prebiotic in poultry diets.

Stability of knee ligament complex of Thiel-embalmed cadaver compared to in vivo knee.

PubMed

Völlner, Florian; Pilsl, Ulrike; Craiovan, Benjamin; Zeman, Florian; Schneider, Michael; Wörner, Michael; Grifka, Joachim; Weber, Markus

2017-07-01

The first biomechanical evaluation of new implants is usually carried out with cadavers. Fixation of Thiel-embalmed cadavers is supposed to preserve the histological structure, colour and consistency of the tissue and has a low risk of infection and toxicity. However, the biomechanical properties of Thiel-fixated tissue are still unknown. The aim of this study was to quantify the effect of the Thiel-embalming method on the elastic properties of the ligament complex of the knee compared to in vivo knees during total knee arthroplasty. The results of biomechanical tensile tests with 10 Thiel-embalmed knees were compared with the findings of 10 patients who underwent total knee arthroplasty with a standardised knee balancer at our department. We reconstructed the force-elongation curves of the medial and lateral ligament complex and calculated the stiffness in direct correlation with overall soft tissue stability in full extension and in 90° of flexion. All curves consisted of a non-linear part at the beginning and a linear part from about 80N onwards. In full extension, median stiffness in the cadavers was 26.6N/mm for the medial compartment and 31.6N/mm for the lateral compartment. The values for in vivo were 25.7N/mm for the medial compartment and 25.3N/mm for the lateral compartment (p=0.684 for the medial compartment and p=0.247 for the lateral compartment). In 90° of flexion, median stiffness in the cadaver group was 24.7N/mm for the medial compartment and 22.2N/mm for the lateral compartment. In vivo, median stiffness was 30.3N/mm for the medial compartment and 29.2N/mm for the lateral compartment (p=0.009 for the medial compartment and p=0.143 for the lateral compartment). Stiffness of the medial and lateral ligament complex in the knee was comparable between Thiel-embalmed cadavers and in vivo patients during total knee arthroplasty. Thiel fixation seems to preserve the soft tissue properties similar to those in vivo. Copyright © 2017 Elsevier Ltd. All

The biomechanical effect of artificial and human bone density on stopping and stripping torque during screw insertion.

PubMed

Tsuji, Matthew; Crookshank, Meghan; Olsen, Michael; Schemitsch, Emil H; Zdero, Rad

2013-06-01

Orthopedic surgeons apply torque to metal screws manually by "subjective feel" to obtain adequate fracture fixation, i.e. stopping torque, and attempt to avoid accidental over-tightening that leads to screw-bone interface failure, i.e. stripping torque. Few studies have quantified stripping torque in human bone, and only one older study from 1980 reported stopping/ stripping torque ratio. The present aim was to measure stopping and stripping torque of cortical and cancellous screws in artificial and human bone over a wide range of densities. Sawbone blocks were obtained having densities from 0.08 to 0.80g/cm(3). Sixteen fresh-frozen human femurs of known standardized bone mineral density (sBMD) were also used. Using a torque screwdriver, 3.5-mm diameter cortical screws and 6.5-mm diameter cancellous screws were inserted for adequate tightening as determined subjectively by an orthopedic surgeon, i.e. stopping torque, and then further tightened until failure of the screw-bone interface, i.e. stripping torque. There were weak (R=0.25) to strong (R=0.99) linear correlations of absolute and normalized torque vs. density or sBMD. Maximum stopping torques normalized by screw thread area engaged by the host material were 15.2N/mm (cortical screws) and 13.4N/mm (cancellous screws) in sawbone blocks and 20.9N/mm (cortical screws) and 6.1N/mm (cancellous screws) in human femurs. Maximum stripping torques normalized by screw thread area engaged by the host material were 23.4N/mm (cortical screws) and 16.8N/mm (cancellous screws) in sawbone blocks and 29.3N/mm (cortical screws) and 8.3N/mm (cancellous screws) in human femurs. Combined average stopping/ stripping torque ratios were 80.8% (cortical screws) and 76.8% (cancellous screws) in sawbone blocks, as well as 66.6% (cortical screws) and 84.5% (cancellous screws) in human femurs. Surgeons should be aware of stripping torque limits for human femurs and monitor stopping torque during surgery. This is the first study of the

A new phase of ThC at high pressure predicted from a first-principles study

NASA Astrophysics Data System (ADS)

Guo, Yongliang; Qiu, Wujie; Ke, Xuezhi; Huai, Ping; Cheng, Cheng; Han, Han; Ren, Cuilan; Zhu, Zhiyuan

2015-08-01

The phase transition of thorium monocarbide (ThC) at high pressure has been studied by means of density functional theory. Through structure search, a new phase with space group P 4 / nmm has been predicted. The calculated phonons demonstrate that this new phase and the previous B2 phase are dynamically stable as the external pressure is greater than 60 GPa and 120 GPa, respectively. The transformation from B1 to P 4 / nmm is predicted to be a first-order transition, while that from P 4 / nmm to B2 is found to be a second-order transition.

Different PEEK qualities irradiated with light of different wavelengths: Impact on Martens hardness.

PubMed

Lümkemann, Nina; Eichberger, Marlis; Stawarczyk, Bogna

2017-09-01

To assess the impact of irradiation on Martens hardness parameters of different PEEK qualities filled with titanium dioxide (TiO 2 ), namely PEEK/0%, PEEK/20%, and PEEK/>30%. For Martens hardness (HM) measurements, 40 specimens of each PEEK quality were fabricated and air-abraded with 50μm Al 2 O 3 . HM parameters of PEEK specimens were measured initially and stepwise after irradiating for 5, 10, 20, 30, 40, 60, 80, 100, 180, 360 and 540s using light units with different wavelength: Elipar S10 (430-480nm), EyeVolutionMAX (385-390nm+465-470nm), Translux CL (380-500nm) and bre.Lux Power Unit (370-500nm). HM parameters of 10 human teeth were measured initially on enamel and dentin. Data was analysed using 3-way ANOVA with partial eta-squared (η P 2 ) and post-hoc Tuckey-HSD-test (p<0.05). PEEK qualities followed by the wavelength showed the highest effect on Martens hardness (p<0.013). PEEK/>30% (197.35±19.9N/mm 2 ), followed by PEEK/20% (191.45±15.49 N/mm 2 ) showed significantly higher values for HM than PEEK/0% (189.55±16.89N/mm 2 ). PEEK/>30% (5.49±0.4kN/mm) and PEEK/20% (5.38±0.26kN/mm 2 ) presented higher indentation modulus (E IT ) than PEEK/0% (4.77±0.36kN/mm 2 ). Irradiated with wavelength of 430-480nm (PEEK/0%: 193.28N/mm 2 , PEEK20%: 198.83N/mm 2 , PEEK/>30%: 200.5N/mm 2 ) indicated higher HM compared to specimens irradiated with 380-500nm (PEEK/0%: 186.63N/mm 2 , PEEK20%: 191.05N/mm 2 , PEEK/>30%: 196.13N/mm 2 ). Irradiation using 430-480nm (PEEK/0%: 4.95kN/mm 2 , PEEK20%: 5.52kN/mm 2 , PEEK/>30%: 5.59kN/mm 2 ) and 370-500nm (PEEK/0%: 4.92kN/mm 2 , PEEK20%: 5.43kN/mm 2 , PEEK/>30%: 5.53kN/mm 2 ) indicated higher E IT values compared to specimens irradiated with 380-500nm (PEEK/0%: 4.72kN/mm 2 , PEEK20%: 5.34kN/mm 2 , PEEK/>30%: 5.47kN/mm 2 ). Duration of irradiation presented no impact on results. Enamel (HM: 2263.6±405.16, E IT : 63.16±19.24) and dentin (HM: 468.2±30.77N/mm 2 , E IT : 14.14±4.59kN/mm 2 ) presented significantly higher HM and E

Percutaneous osteoplasty with a bone marrow nail for fractures of long bones: experimental study.

PubMed

Nakata, Kouhei; Kawai, Nobuyuki; Sato, Morio; Cao, Guang; Sahara, Shinya; Tanihata, Hirohiko; Takasaka, Isao; Minamiguchi, Hiroyuki; Nakai, Tomoki

2010-09-01

To develop percutaneous osteoplasty with the use of a bone marrow nail for fixation of long-bone fractures, and to evaluate its feasibility and safety in vivo and in vitro. Six long bones in three healthy swine were used in the in vivo study. Acrylic cement was injected through an 11-gauge bone biopsy needle and a catheter into a covered metallic stent placed within the long bone, creating a bone marrow nail. In the in vitro study, we determined the bending, tug, and compression strengths of the acrylic cement nails 9 cm long and 8 mm in diameter (N = 10). The bending strength of the artificially fractured bones (N = 6) restored with the bone marrow nail and cement augmentation was then compared with that of normal long bones (N = 6). Percutaneous osteoplasty with a bone marrow nail was successfully achieved within 1 hour for all swine. After osteoplasty, all swine regained the ability to run until they were euthanized. Blood tests and pathologic findings showed no adverse effects. The mean bending, tug, and compression strengths of the nail were 91.4 N/mm(2) (range, 75.0-114.1 N/mm(2)), 20.9 N/mm(2) (range, 6.6-30.4 N/mm(2)), and 103.0 N/mm(2) (range, 96.3-110.0 N/mm(2)), respectively. The bending strength ratio of artificially fractured bones restored with bone marrow nail and cement augmentation to normal long bone was 0.32. Percutaneous osteoplasty with use of a bone marrow nail and cement augmentation appears to have potential in treating fractures of non-weight-bearing long bones. Copyright 2010 SIR. Published by Elsevier Inc. All rights reserved.

Department of Defense Base Closure and Realignment Report

DTIC Science & Technology

1993-03-01

European NATO allies wili continue to grapple with shaping 3n evolving regional security framework capable of crisis management and conflict prevention, as...Personnel, Arlington, Virginia (including the Office of Military Manpower Management . Arlington, Virg;uda) Naval Air Systems Command, Arlington, Virginia...Hawaii Enlisted Personnel Management Center, New Orleans, Louisiana Naval Computer & Telecommunications Station, New Orleans, Louisiana Naval Air Station

Efficient and rapid Agrobacterium-mediated genetic transformation of durum wheat (Triticum turgidum L. var. durum) using additional virulence genes.

PubMed

Wu, Huixia; Doherty, Angela; Jones, Huw D

2008-06-01

Genetic transformation of wheat, using biolistics or Agrobacterium, underpins a range of specific research methods for identifying genes and studying their function in planta. Transgenic approaches to study and modify traits in durum wheat have lagged behind those for bread wheat. Here we report the use of Agrobacterium strain AGL1, with additional vir genes housed in a helper plasmid, to transform and regenerate the durum wheat variety Ofanto. The use of the basic pSoup helper plasmid with no additional vir genes failed to generate transformants, whereas the presence of either virG542 or the 15 kb Komari fragment containing virB, virC and virG542 produced transformation efficiencies of between 0.6 and 9.7%. Of the 42 transgenic plants made, all but one (which set very few seeds) appeared morphologically normal and produced between 100 and 300 viable seeds. The transgene copy number and the segregation ratios were found to be very similar to those previously reported for bread wheat. We believe that this is the first report describing successful genetic transformation of tetraploid durum wheat (Triticum turgidum L. var. durum) mediated by Agrobacterium tumefaciens using immature embryos as the explant.

High-efficiency Agrobacterium-mediated transformation of Norway spruce (Picea abies) and loblolly pine (Pinus taeda)

NASA Technical Reports Server (NTRS)

Wenck, A. R.; Quinn, M.; Whetten, R. W.; Pullman, G.; Sederoff, R.; Brown, C. S. (Principal Investigator)

1999-01-01

Agrobacterium-mediated gene transfer is the method of choice for many plant biotechnology laboratories; however, large-scale use of this organism in conifer transformation has been limited by difficult propagation of explant material, selection efficiencies and low transformation frequency. We have analyzed co-cultivation conditions and different disarmed strains of Agrobacterium to improve transformation. Additional copies of virulence genes were added to three common disarmed strains. These extra virulence genes included either a constitutively active virG or extra copies of virG and virB, both from pTiBo542. In experiments with Norway spruce, we increased transformation efficiencies 1000-fold from initial experiments where little or no transient expression was detected. Over 100 transformed lines expressing the marker gene beta-glucuronidase (GUS) were generated from rapidly dividing embryogenic suspension-cultured cells co-cultivated with Agrobacterium. GUS activity was used to monitor transient expression and to further test lines selected on kanamycin-containing medium. In loblolly pine, transient expression increased 10-fold utilizing modified Agrobacterium strains. Agrobacterium-mediated gene transfer is a useful technique for large-scale generation of transgenic Norway spruce and may prove useful for other conifer species.

Comments on "J. Vera et. al., Soil water balance trial involving capacitance and neutron probe measurements"

USDA-ARS?s Scientific Manuscript database

Vera et al. (2009) compared estimates of soil profile water content (mm) to a depth of 0.8 m made with the neutron moisture meter (NMM) and a multi-depth capacitance probe (MDCP), using measurements replicated in four drainage lysimeters (5 m x 5 m x 1.5-m deep). The NMM estimates of water content w...

Effects of diets containing different concentrations of mannanoligosaccharide or antibiotics on growth performance, intestinal development, cecal and litter microbial populations, and carcass parameters of broilers.

PubMed

Baurhoo, B; Ferket, P R; Zhao, X

2009-11-01

The effects of 2 levels of mannanoligosaccharide (MOS) in feed were compared with antibiotic growth promoters on growth performance, intestinal morphology, cecal and litter microbial populations, and carcass parameters in broilers raised in a sanitary environment. Dietary treatments included: 1) antibiotic growth promoter-free diet (control), 2) VIRG (diet 1 + 16.5 mg/kg of virginiamycin), 3) BACT (diet 1 + 55 mg/kg of bacitracin), 4) LMOS (diet 1 + 0.2% MOS), and 5) HMOS (diet 1 + 0.5% MOS). Birds were randomly assigned to 3 replicate pens/treatment (n = 55/pen). Body weight and feed intake were recorded weekly throughout 38 d. At d 14, 24, and 34, a 1-cm segment of duodenum, jejunum, and ileum was used in morphological analysis (n = 9 birds/d per treatment). At the same bird ages, cecal contents were assayed for lactobacilli, bifidobacteria, Salmonella, Campylobacter, and Escherichia coli, whereas litter was analyzed for Salmonella, Campylobacter, and E. coli. Carcass yields (breast fillet and tenders, thigh, drumstick, and wing) were determined at d 38. Body weight, feed conversion, and carcass yields did not differ among treatments. In contrast to birds fed VIRG or BACT, LMOS and HMOS consistently increased (P < 0.05) villi height and goblet cell number per villus in all intestinal segments at d 24 and 34. Bifidobacteria concentrations were higher (P < 0.05) in LMOS- and HMOS-fed birds at all time points. Birds and litter from all treatments were free of Salmonella. At d 14 and 24, cecal E. coli and Campylobacter counts were not different among treatments. In comparison to birds fed control, at d 34, BACT, LMOS, and HMOS significantly reduced (P < 0.05) cecal E. coli concentrations, whereas Campylobacter counts were reduced (P < 0.05) by VIRG, BACT, and LMOS. Litter bacterial counts were not altered by dietary treatments. In conclusion, under conditions of this study, MOS conferred intestinal health benefits to chickens by improving its morphological

Ion-Induced Afterpulsing in the Neutron Multiplicity Meter's Photomultiplier Tubes

NASA Astrophysics Data System (ADS)

Nedlik, Christopher; Schnee, Richard; Bunker, Raymond; Chen, Yu; Neutron Multiplicity Meter Collaboration

2013-10-01

The nature of the dark matter in the Universe remains a mystery in modern physics. A leading candidate, Weakly Interacting Massive Particles (WIMPs), may be detectable via scattering from nuclear targets in terrestrial detectors, located underground to prevent fake signals from cosmic-ray showers. The Neutron Multiplicity Meter (NMM) is a detector capable of measuring the muon-induced neutron flux deep underground, a problematic background for WIMP detection. The NMM is a 4.4-tonne Gd-loaded water-Cherenkov detector atop a 20-kilotonne lead target in the Soudan Mine. It measures high-energy neutrons (>50 MeV) by moderating and then detecting (via Gd capture gammas) the secondary neutrons emerging from the lead following a high-energy neutron interaction. The short time scale (~10 μs) for neutron capture in Gd-loaded water enables a custom multiplicity trigger to discriminate against the dominant gamma-ray background. Despite excellent rejection of the gamma-ray-induced background, NMM neutron-candidate events are not entirely background-free. One type of background is from ion-induced afterpulsing (AP) in the four 20'' Hamamatsu R7250 photomultiplier tubes (PMTs) used to monitor the NMM's two water tanks. We show that ion-induced AP in the PMTs can mimic the NMM's low-energy neutron response, potentially biasing a candidate event's measured multiplicity. We present detailed studies of the AP in order to allow identification of AP-induced background events.

Effect of formation and state of interface on joint strength in friction stir spot welding for advanced high strength steel sheets

NASA Astrophysics Data System (ADS)

Taniguchi, Koichi; Matsushita, Muneo; Ikeda, Rinsei; Oi, Kenji

2014-08-01

The tensile shear strength and cross tension strength of friction stir spot welded joints were evaluated in the cases of lap joints of 270 N/mm2 grade and 980 N/mm2 grade cold rolled steel sheets with respect to the stir zone area, hardness distribution, and interface condition between the sheets. The results suggested that both the tensile shear strength and cross tension strength were based on the stir zone area and its hardness in both grades of steel. The "hook" shape of the interface also affected the joint strength. However, the joining that occurred across the interfaces had a significant influence on the value of the joint strength in the case of the 270 N/mm2 grade steel.

Sunrise/sunset thermal shock disturbance analysis and simulation for the TOPEX satellite

NASA Technical Reports Server (NTRS)

Dennehy, C. J.; Welch, R. V.; Zimbelman, D. F.

1990-01-01

It is shown here that during normal on-orbit operations the TOPEX low-earth orbiting satellite is subjected to an impulsive disturbance torque caused by rapid heating of its solar array when entering and exiting the earth's shadow. Error budgets and simulation results are used to demonstrate that this sunrise/sunset torque disturbance is the dominant Normal Mission Mode (NMM) attitude error source. The detailed thermomechanical modeling, analysis, and simulation of this torque is described, and the predicted on-orbit performance of the NMM attitude control system in the face of the sunrise/sunset disturbance is presented. The disturbance results in temporary attitude perturbations that exceed NMM pointing requirements. However, they are below the maximum allowable pointing error which would cause the radar altimeter to break lock.

Improving the Non-Hydrostatic Numerical Dust Model by Integrating Soil Moisture and Greenness Vegetation Fraction Data with Different Spatiotemporal Resolutions.

PubMed

Yu, Manzhu; Yang, Chaowei

2016-01-01

Dust storms are devastating natural disasters that cost billions of dollars and many human lives every year. Using the Non-Hydrostatic Mesoscale Dust Model (NMM-dust), this research studies how different spatiotemporal resolutions of two input parameters (soil moisture and greenness vegetation fraction) impact the sensitivity and accuracy of a dust model. Experiments are conducted by simulating dust concentration during July 1-7, 2014, for the target area covering part of Arizona and California (31, 37, -118, -112), with a resolution of ~ 3 km. Using ground-based and satellite observations, this research validates the temporal evolution and spatial distribution of dust storm output from the NMM-dust, and quantifies model error using measurements of four evaluation metrics (mean bias error, root mean square error, correlation coefficient and fractional gross error). Results showed that the default configuration of NMM-dust (with a low spatiotemporal resolution of both input parameters) generates an overestimation of Aerosol Optical Depth (AOD). Although it is able to qualitatively reproduce the temporal trend of the dust event, the default configuration of NMM-dust cannot fully capture its actual spatial distribution. Adjusting the spatiotemporal resolution of soil moisture and vegetation cover datasets showed that the model is sensitive to both parameters. Increasing the spatiotemporal resolution of soil moisture effectively reduces model's overestimation of AOD, while increasing the spatiotemporal resolution of vegetation cover changes the spatial distribution of reproduced dust storm. The adjustment of both parameters enables NMM-dust to capture the spatial distribution of dust storms, as well as reproducing more accurate dust concentration.

Development of extended WRF variational data assimilation system (WRFDA) for WRF non-hydrostatic mesoscale model

NASA Astrophysics Data System (ADS)

Pattanayak, Sujata; Mohanty, U. C.

2018-06-01

The paper intends to present the development of the extended weather research forecasting data assimilation (WRFDA) system in the framework of the non-hydrostatic mesoscale model core of weather research forecasting system (WRF-NMM), as an imperative aspect of numerical modeling studies. Though originally the WRFDA provides improved initial conditions for advanced research WRF, we have successfully developed a unified WRFDA utility that can be used by the WRF-NMM core, as well. After critical evaluation, it has been strategized to develop a code to merge WRFDA framework and WRF-NMM output. In this paper, we have provided a few selected implementations and initial results through single observation test, and background error statistics like eigenvalues, eigenvector and length scale among others, which showcase the successful development of extended WRFDA code for WRF-NMM model. Furthermore, the extended WRFDA system is applied for the forecast of three severe cyclonic storms: Nargis (27 April-3 May 2008), Aila (23-26 May 2009) and Jal (4-8 November 2010) formed over the Bay of Bengal. Model results are compared and contrasted within the analysis fields and later on with high-resolution model forecasts. The mean initial position error is reduced by 33% with WRFDA as compared to GFS analysis. The vector displacement errors in track forecast are reduced by 33, 31, 30 and 20% to 24, 48, 72 and 96 hr forecasts respectively, in data assimilation experiments as compared to control run. The model diagnostics indicates successful implementation of WRFDA within the WRF-NMM system.

Exploration of stable compounds, crystal structures, and superconductivity in the Be-H system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Shuyin, E-mail: yushuyin2014@gmail.com; Zeng, Qingfeng; Zhang, Litong

2014-10-15

Using first-principles variable-composition evolutionary methodology, we explored the high-pressure structures of beryllium hydrides between 0 and 400 GPa. We found that BeH{sub 2} remains the only stable compound in this pressure range. The pressure-induced transformations are predicted as Ibam→P3{sup -}m1→R3{sup -}m→Cmcm→P4/nmm, which occur at 24, 139, 204 and 349 GPa, respectively. P3{sup -}m1 and R3{sup -}m structures are layered polytypes based on close packings of H atoms with Be atoms filling all octahedral voids in alternating layers. Cmcm and P4/nmm contain two-dimensional triangular networks with each layer forming a kinked slab in the ab-plane. P3{sup -}m1 and R3{sup -}m aremore » semiconductors while Cmcm and P4/nmm are metallic. We have explored superconductivity of both metal phases, and found large electron-phonon coupling parameters of λ = 0.63 for Cmcm with a T{sub c} of 32.1-44.1 K at 250 GPa and λ = 0.65 for P4/nmm with a T{sub c} of 46.1-62.4 K at 400 GPa. The dependence of T{sub c} on pressure indicates that T{sub c} initially increases to a maximum of 45.1 K for Cmcm at 275 GPa and 97.0 K for P4/nmm at 365 GPa, and then decreases with increasing pressure for both phases.« less

The diagnosis of severe thunderstorms with high-resolution WRF model

NASA Astrophysics Data System (ADS)

Litta, A. J.; Mohanty, U. C.; Idicula, Sumam Mary

2012-04-01

Thunderstorm, resulting from vigorous convective activity, is one of the most spectacular weather phenomena in the atmosphere. A common feature of the weather during the pre-monsoon season over the Indo-Gangetic Plain and northeast India is the outburst of severe local convective storms, commonly known as `Nor'westers'(as they move from northwest to southeast). The severe thunderstorms associated with thunder, squall lines, lightning and hail cause extensive losses in agricultural, damage to structure and also loss of life. In this paper, sensitivity experiments have been conducted with the Non-hydrostatic Mesoscale Model (NMM) to test the impact of three microphysical schemes in capturing the severe thunderstorm event occurred over Kolkata on 15 May 2009. The results show that the WRF-NMM model with Ferrier microphysical scheme appears to reproduce the cloud and precipitation processes more realistically than other schemes. Also, we have made an attempt to diagnose four severe thunderstorms that occurred during pre-monsoon seasons of 2006, 2007 and 2008 through the simulated radar reflectivity fields from NMM model with Ferrier microphysics scheme and validated the model results with Kolkata Doppler Weather Radar (DWR) observations. Composite radar reflectivity simulated by WRF-NMM model clearly shows the severe thunderstorm movement as observed by DWR imageries, but failed to capture the intensity as in observations. The results of these analyses demonstrated the capability of high resolution WRF-NMM model in the simulation of severe thunderstorm events and determined that the 3 km model improve upon current abilities when it comes to simulating severe thunderstorms over east Indian region.

Stress analysis on passenger deck due to modification from passenger ship to vehicle-carrying ship

NASA Astrophysics Data System (ADS)

Zubaydi, A.; Sujiatanti, S. H.; Hariyanto, T. R.

2018-03-01

Stress is a basic concept in learning about material mechanism. The main focus that needs to be brought to attention in analyzing stress is strength, which is the structural capacity to carry or distribute loads. The structural capacity not only measured by comparing the maximum stress with the material’s yield strength but also with the permissible stress required by the Indonesian Classification Bureau (BKI), which certainly makes it much safer. This final project analyzes stress in passenger deck that experiences modification due to load changes, from passenger load to vehicle one, carrying: 6-wheels truck with maximum weight of 14 tons, a passenger car with maximum weight of 3.5 tons, and a motorcycle with maximum weight of 0.4 tons. The deck structure is modelled using finite element software. The boundary conditions given to the structural model are fix and simple constraint. The load that works on this deck is the deck load which comes from the vehicles on deck with three vehicles’ arrangement plans. After that, software modelling is conducted for analysis purpose. Analysis result shows a variation of maximum stress that occurs i.e. 135 N/mm2, 133 N/mm2, and 152 N/mm2. Those maximum stresses will not affect the structure of passenger deck’s because the maximum stress that occurs indicates smaller value compared to the Indonesian Classification Bureau’s permissible stress (175 N/mm2) as well as the material’s yield strength (235 N/mm2). Thus, the structural strength of passenger deck is shown to be capable of carrying the weight of vehicles in accordance with the three vehicles’ arrangement plans.

A methodological approach for the biomechanical cause analysis of golf-related lumbar spine injuries.

PubMed

Sim, Taeyong; Jang, Dong-Jin; Oh, Euichaul

2014-01-01

A new methodological approach employing mechanical work (MW) determination and relative portion of its elemental analysis was applied to investigate the biomechanical causes of golf-related lumbar spine injuries. Kinematic and kinetic parameters at the lumbar and lower limb joints were measured during downswing in 18 golfers. The MW at the lumbar joint (LJ) was smaller than at the right hip but larger than the MWs at other joints. The contribution of joint angular velocity (JAV) to MW was much greater than that of net muscle moment (NMM) at the LJ, whereas the contribution of NMM to MW was greater rather than or similar to that of JAV at other joints. Thus, the contribution of JAV to MW is likely more critical in terms of the probability of golf-related injury than that of NMM. The MW-based golf-related injury index (MWGII), proposed as the ratio of the contribution of JAV to MW to that of NMM, at the LJ (1.55) was significantly greater than those at other joints ( < 1.05). This generally corresponds to the most frequent occurrence of golf-related injuries around the lumbar spine. Therefore, both MW and MWGII should be considered when investigating the biomechanical causes of lumbar spine injuries.

Effects of meat addition on pasta structure, nutrition and in vitro digestibility.

PubMed

Liu, Tingting; Hamid, Nazimah; Kantono, Kevin; Pereira, Loveena; Farouk, Mustafa M; Knowles, Scott O

2016-12-15

In our study, semolina flour was substituted with beef emulsion (EM) at three different levels of 15, 30 and 45% (w/w) to develop a pasta with enhanced nutritional profile. The protein, fat, and water content significantly increased with addition of meat. The addition of meat enhanced the pasta gluten network. The redness and yellowness of cooked pasta increased with meat addition. Tensile strength increased from 0.018N/mm(2) in the control sample to 0.046N/mm(2) in 45% beef emulsion (45EM) sample. All meat-containing samples had significantly higher elasticity than control (0.039N/mm(2)). GI significantly decreased and IVPD value increased in 45EM sample. Five essential amino acids (leucine, lysine, methionine, threonine, tryptophan) in pasta digesta increased significantly with increasing meat addition. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mixture models with entropy regularization for community detection in networks

NASA Astrophysics Data System (ADS)

Chang, Zhenhai; Yin, Xianjun; Jia, Caiyan; Wang, Xiaoyang

2018-04-01

Community detection is a key exploratory tool in network analysis and has received much attention in recent years. NMM (Newman's mixture model) is one of the best models for exploring a range of network structures including community structure, bipartite and core-periphery structures, etc. However, NMM needs to know the number of communities in advance. Therefore, in this study, we have proposed an entropy regularized mixture model (called EMM), which is capable of inferring the number of communities and identifying network structure contained in a network, simultaneously. In the model, by minimizing the entropy of mixing coefficients of NMM using EM (expectation-maximization) solution, the small clusters contained little information can be discarded step by step. The empirical study on both synthetic networks and real networks has shown that the proposed model EMM is superior to the state-of-the-art methods.

Local Application of Gelatin Hydrogel Sheets Impregnated With Platelet-Derived Growth Factor BB Promotes Tendon-to-Bone Healing After Rotator Cuff Repair in Rats.

PubMed

Tokunaga, Takuya; Ide, Junji; Arimura, Hitoshi; Nakamura, Takayuki; Uehara, Yusuke; Sakamoto, Hidetoshi; Mizuta, Hiroshi

2015-08-01

To determine whether the local application of platelet-derived growth factor BB (PDGF-BB) in hydrogel sheets would promote healing and improve histologic characteristics and biomechanical strength after rotator cuff (RC) repair in rats. To assess the effect of PDGF-BB on tendon-to-bone healing we divided 36 adult male Sprague-Dawley rats treated with bilateral surgery to repair the supraspinatus tendon at its insertion site into 3 groups: group 1 = suture-only group; group 2 = suture and gelatin hydrogel sheets impregnated with phosphate-buffered saline (PBS); and group 3 = suture and gelatin hydrogel sheets impregnated with PDGF-BB (0.5 μg). Semiquantitative histologic evaluation was carried out 2, 6, and 12 weeks later; cell proliferation was assessed 2 and 6 weeks postoperatively by immunostaining for proliferating cell nuclear antigen (PCNA), and biomechanical testing, including ultimate load to failure, stiffness, and ultimate stress to failure, was performed 12 weeks after the operation. At 2 weeks, the average percentage of PCNA-positive cells at the insertion site was significantly higher in group 3 (40.5% ± 2.4%) than in group 1 (32.1% ± 6.9%; P = .03) and group 2 (31.9% ± 3.7%; P = .02). At 2 and 6 weeks, the histologic scores were similar among the 3 groups. At 12 weeks, the histologic score was significantly higher in group 3 (10.3 ± 0.8) than in group 1 (8.5 ± 0.5; P = .002) or group 2 (8.8 ± 0.8; P = .009), whereas ultimate load to failure, stiffness, and ultimate load to stress (normal control population, 44.73 ± 9.75 N, 27.59 ± 4.32 N/mm, and 21.33 ± 4.65 N/mm(2), respectively) were significantly higher in group 3 (28.28 ± 6.28 N, 11.05 ± 2.37 N/mm, and 7.99 ± 2.13 N/mm(2), respectively) than in group 1 (10.44 ± 1.98 N, 4.74 ± 1.31 N/mm, and 3.28 ± 1.27 N/mm(2), respectively; all P < .001) or group 2 (11.85 ± 2.89 N, 5.86 ± 1.75 N/mm, and 3.31 ± 0.80 N/mm(2), respectively; all P < .001). The placement of a PDGF

The Effects of Man-Marking on Work Intensity in Small-Sided Soccer Games

PubMed Central

Ngo, Jake K.; Tsui, Man-Chung; Smith, Andrew W.; Carling, Christopher; Chan, Gar-Sun; Wong, Del P.

2012-01-01

The aim of this study was to examine the effect of manipulating defensive rules: with and without man-marking (MM and NMM) on exercise intensity in 3 vs. 3 small- sided games (SSGs). Twelve adolescent soccer players (age: 16.2 ± 0.7 years; body mass: 55.7 ± 6.4 kg; body height: 1.70 ± 0.07 m) participated in this repeated measures study. Each participant performed in four different SSGs formats: 3 vs. 3 MM with and without goals and 3 vs. 3 NMM with and without goals. Each SSG lasted 3 x 4 minutes interspersed with 4 minutes passive recovery. The percentage heart rate reserve (%HRreserve) was recorded continuously during SSG and session-rating of perceived exertion (session-RPE) after the SSG. MANOVA showed that defensive rule had significant effects on intensity (F = 5.37, p < 0.01). Specifically, MM during SSG induced significantly higher %HRreserve compared to NMM (Goal: 80.5 vs. 75.7%; No goal: 80.5 vs. 76.1%; p < 0.05, effect size = 0.91-1.06), irrespective of the presence or absence of goals. However, only MM with the presence of goals induced significant higher session-RPE compared to NMM (7.1 vs. 6. 0; p < 0.05, effect size = 1.36), whereas no difference in session-RPE was observed between MM and NMM (7.4 vs. 6.9; p > 0.05, effect size = 0.63) when no goals were used. Higher intra-class reliability and lower coefficient of variation values were also reported in MM as compared to NMM. This study in youth soccer players shows there is ~4.5% increase in heart rate response by using the man-marking in 3 vs. 3 SSG thus the intensity of SSG can be significantly increased when using man-marking tactics. Key pointsIntensity level of exercise during games can be raised if man-marking rule is adopted.No significant differences in perceived exertion were found in no goal SSG with and without man-marking.Adding goals in 3 vs. 3 SSG can lower perceived exertion without leading to large variations in intensity level. PMID:24149127

A comparison of bicortical and intramedullary screw fixations of Jones' fractures.

PubMed

Husain, Zeeshan S; DeFronzo, Donna J

2002-01-01

Two different fixations for treatment of Jones' fracture were tested in bone models and cadaveric specimens to determine the differences in the stability of the constructs. A bicortical 3.5-mm cannulated cortical screw and an intramedullary 4.0-mm partially threaded cancellous screw were tested using physiologic loads with an Instron 8500 servohydraulic tensiometer (Instron Corporation, Canton, MA). In bone models, the bicortical construct (n = 5, 87+/-23 N) showed superior fixation strength (p = .0009) when compared to the intramedullary screw fixation (n = 5, 25+/-13 N). Cadaveric testing showed similar statistical significance (p = .0124) with the bicortical construct (n = 5, 152+/-71 N) having greater load resistance than the intramedullary screw fixation (n = 4, 29+/-20 N). In bone models, the bicortical constructs (23+/-9 N/mm) showed over twice the elastic modulus than the intramedullary screw fixations (9+/-4 N/mm) with statistical significance (p = .0115). The elastic modulus in the cadaveric group showed a similar pattern between the bicortical (19+/-17 N/mm) and intramedullary (9+/-6 N/mm) screw constructs. Analysis of the bicortical screw failure patterns revealed that screw orientation had a critical impact on fixation stability. The more distal the exit site of the bicortical screw was from the fracture site, the greater the load needed to displace the fixation.

Monoaxial Pedicle Screws Are Superior to Polyaxial Pedicle Screws and the Two Pin External Fixator for Subcutaneous Anterior Pelvic Fixation in a Biomechanical Analysis

PubMed Central

Vaidya, Rahul; Onwudiwe, Ndidi; Roth, Matthew; Sethi, Anil

2013-01-01

Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113 Nmm monoaxial, 3.638 ± 0.108 Nmm Click-x; 3.634 ± 0.147 Nmm Pangea) than the exfix system (2.882 ± 0.054 Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360 N) than exfixes (160 N) and polyaxial devices which failed if distracted greater than 4 cm (157 N Click-x or 138 N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360 N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems. PMID:24368943

Monoaxial pedicle screws are superior to polyaxial pedicle screws and the two pin external fixator for subcutaneous anterior pelvic fixation in a biomechanical analysis.

PubMed

Vaidya, Rahul; Onwudiwe, Ndidi; Roth, Matthew; Sethi, Anil

2013-01-01

Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113 Nmm monoaxial, 3.638 ± 0.108 Nmm Click-x; 3.634 ± 0.147 Nmm Pangea) than the exfix system (2.882 ± 0.054 Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360 N) than exfixes (160 N) and polyaxial devices which failed if distracted greater than 4 cm (157 N Click-x or 138 N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360 N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems.

Comparison of ultrasonic suture welding and traditional knot tying in a rabbit rotator cuff repair model.

PubMed

Nho, Shane J; Cole, Brian J; Mazzocca, Augustus D; Williams, James M; Romeo, Anthony A; Bush-Joseph, Charles A; Bach, Bernard R; Hallab, Nadim J

2006-01-01

The purpose of this study is to evaluate ultrasonic suture welding of monofilament suture in an animal model of rotator cuff repair with biomechanical and histologic analyses. We randomly assigned 46 shoulders in 23 rabbits to 1 of 3 treatment groups: sham-operated (n = 15), knotted (n = 15), and welded (n = 16). Supraspinatus defects were surgically created and acutely repaired with suture anchors loaded with either No. 2-0 Ethibond for knotted group or No. 2-0 nylon for welded shoulders. Eighteen weeks postoperatively, all animals were killed, and the shoulders underwent either biomechanical testing or histologic analysis. The maximum stress of the sham-operated group (20.6 N/mm2) was significantly greater than that of both the knotted (10.2 N/mm2) and welded (8.3 N/mm2) groups (P < .05), but no differences were observed between the knotted and welded groups. Although some histologic changes were noted, none was considered to be significant to distinguish either group.

Technology for the manufacture of Diabetic Rosogolla.

PubMed

Chavan, R S; Prajapati, P S; Chavan, S R; Jana, A

2014-01-01

Diabetic Rosogolla was manufactured by using low-fat cow milk. Six different combinations viz. type of chhana and two different concentrations (40° and 50° Brix) of cooking medium. All of the experimental samples and control were analyzed for physico-chemical, textural, and sensory properties. A 40° Brix concentration of cooking medium was preferred to give a highly acceptable Diabetic Rosogolla. The average composition of Diabetic Rosogolla is moisture-52.20%, fat-4.46%, protein-12.78%, sorbitol-29.66%, and ash-0.89%. Similarly, the rheological properties were hardness-7.85 N, cohesiveness-0.54, springiness-6.06 mm, gumminess-3.8 N, chewiness-26.07 Nmm, fracture force-4.1 N, adhesiveness-0.0272 Nmm, and stiffness-2.17 N/mm. This protocol can be adopted at commercial level and be used to serve the customers who desire fewer calories but cannot resist having the sweets after their meal.

Simulation of two-phase flow in horizontal fracture networks with numerical manifold method

NASA Astrophysics Data System (ADS)

Ma, G. W.; Wang, H. D.; Fan, L. F.; Wang, B.

2017-10-01

The paper presents simulation of two-phase flow in discrete fracture networks with numerical manifold method (NMM). Each phase of fluids is considered to be confined within the assumed discrete interfaces in the present method. The homogeneous model is modified to approach the mixed fluids. A new mathematical cover formation for fracture intersection is proposed to satisfy the mass conservation. NMM simulations of two-phase flow in a single fracture, intersection, and fracture network are illustrated graphically and validated by the analytical method or the finite element method. Results show that the motion status of discrete interface significantly depends on the ratio of mobility of two fluids rather than the value of the mobility. The variation of fluid velocity in each fracture segment and the driven fluid content are also influenced by the ratio of mobility. The advantages of NMM in the simulation of two-phase flow in a fracture network are demonstrated in the present study, which can be further developed for practical engineering applications.

Investigating Anomalies in the Output Generated by the Weather Research and Forecasting (WRF) Model

NASA Astrophysics Data System (ADS)

Decicco, Nicholas; Trout, Joseph; Manson, J. Russell; Rios, Manny; King, David

2015-04-01

The Weather Research and Forecasting (WRF) model is an advanced mesoscale numerical weather prediction (NWP) model comprised of two numerical cores, the Numerical Mesoscale Modeling (NMM) core, and the Advanced Research WRF (ARW) core. An investigation was done to determine the source of erroneous output generated by the NMM core. In particular were the appearance of zero values at regularly spaced grid cells in output fields and the NMM core's evident (mis)use of static geographic information at a resolution lower than the nesting level for which the core is performing computation. A brief discussion of the high-level modular architecture of the model is presented as well as methods utilized to identify the cause of these problems. Presented here are the initial results from a research grant, ``A Pilot Project to Investigate Wake Vortex Patterns and Weather Patterns at the Atlantic City Airport by the Richard Stockton College of NJ and the FAA''.

An ex vivo mechanical evaluation of single versus double semitubular plate fixation of a transverse distal-third scapular osteotomy in the dog.

PubMed

Mair, Jacqueline J; Belkoff, Stephen M; Boudrieau, Randy J

2003-01-01

To compare single versus double semitubular plate fixation for scapular body fractures. Ex vivo mechanical study. Eighteen paired cadaveric canine scapulae. Transverse scapular body osteotomies were created in the distal third of 18 pairs of scapulae. One scapula of each pair was repaired with a single plate, whereas the contralateral scapula was repaired with 2 plates. Initial strength and stiffness of the constructs were measured in 10 pairs of scapulae. Eight pairs of scapulae underwent cyclic loading and then were subjected to failure testing. Double-plate fixation was significantly stronger (3,899 +/- 632 N) but not stiffer (614 +/- 130 N/mm) than the single-plate fixation (3,238 +/- 935 N and 537 +/- 202 N/mm, respectively). Cyclic loading variables were not significantly different between the 2 methods of fixation. After cyclic loading, double-plate fixation was significantly stronger (2,916 +/- 618 N) than single-plate fixation (2,347 +/- 495 N). There was no significant difference (P =.11) in stiffness between double- versus single-plate fixations: 734 +/- 247 N/mm and 595 +/- 139 N/mm, respectively. Double-plate fixation was generally stronger and stiffer than single-plate fixation. Because all constructs failed at loads that greatly exceeded those estimated to occur clinically, any difference between the 2 methods of fixation probably is not clinically relevant. Single-plate fixation may be of sufficient strength for fixation of scapular body fractures. Copyright 2003 by The American College of Veterinary Surgeons

Evaluation of the Biodurability of Polyurethane-Covered Stent Using a Flow Phantom

PubMed Central

Kim, Dong Hyun; Choi, Jung Ryul; Byun, Ju Nam; Kim, Young Chul; Ahn, Young Moo

2001-01-01

Objective To evaluate the biodurability of the covering material in retrievable metallic stents covered with polycarbonate polyurethane. Materials and Methods Using a peristaltic pump at a constant rate of 1ml/min, bile was recirculated from a reservoir through a long tube containing four stents. Each of these was removed from the system every two weeks and a radial tensile strength test and scanning electron microscopy (SEM) were performed. Each stent, removed at 2, 4, 6 and 8 weeks, was compared with a control stent not exposed to bile juice. Results Gross examination showed that stents were intact at 2 weeks, but at 4, 6 and 8 weeks cracks were observed. The size of these increased gradually in accordance with the duration of exposure, and at 8 weeks several large holes in the polyurethane membrane were evident. With regard to radial tensile strength, extension and peak load at break were 84.47% and 10.030 N/mm, 54.90% and 6.769 N/mm, 16.55% and 2.452 N/mm, 11.21% and 1.373 N/mm at 0, 2, 4 and 6 weeks, respectively. Scanning electron microscopy at 2 weeks revealed intermittent pitting and cracking, and examination at 4, 6 and 8 weeks showed that the size of these defects was gradually increasing. Conclusion When the polyurethane membrane was exposed to bile, biodegradation was first observed at week two and increased gradually according to the duration of exposure. PMID:11752974

Impact of different rectangular wires on torsional expression of different sizes of buccal tube.

PubMed

Ajami, Shabnam; Boroujeni, Afshar-Rasti

2018-01-01

Torsions in rectangular wires are the essential part of corrections in the finishing stage of treatment. Moreover the greatest amounts of torques are applied in the molar areas. a clinically effective moment is between 5 and 20 Nmm. In this study we have decided to evaluate the impact of different tube sizes and different dimensions of wires with different modulus of elasticities on the amount torsional bond strength of molar tubes. 60 human impacted molar teeth were collected. A buccal tube was bonded on the buccal surface of all the samples by using light cured adhesive resin. After that, the teeth were mounted in a hard acrylic block. According to the size of buccal tube and the rectangular wires to be tested 4 groups will be designed. Torsional force was applied by instron machine. The torque angle at 5Nmm and at 20Nmm point will be calculated: which means, how many degrees of torque is required to reach the maximum 20Nmm moment from the minimum 5Nmm.One-way ANOVA was used to compare torque angle in all of the groups. The least amount of clinically significant angle was 2.2 ᵒ in the 0.017×0.025 SS and the largest amount of it was 23.7 ᵒ in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. But, this angle was 19.9 ᵒand 13.6 ᵒ in 0.019×0.025 SS and 0.019×0.025 TMA archwire in 0.022×0.028 molar tube. The 0.017×0.025 SS archwire in 0.018×0.025 molar tube had the lowest clinically significant angle. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube. Key words: Torsional efficacy, rectangular wires, buccal tubes, torque angle.

Impact of different rectangular wires on torsional expression of different sizes of buccal tube

PubMed Central

Boroujeni, Afshar-Rasti

2018-01-01

Background Torsions in rectangular wires are the essential part of corrections in the finishing stage of treatment. Moreover the greatest amounts of torques are applied in the molar areas. a clinically effective moment is between 5 and 20 Nmm. In this study we have decided to evaluate the impact of different tube sizes and different dimensions of wires with different modulus of elasticities on the amount torsional bond strength of molar tubes. Material and Methods 60 human impacted molar teeth were collected. A buccal tube was bonded on the buccal surface of all the samples by using light cured adhesive resin. After that, the teeth were mounted in a hard acrylic block. According to the size of buccal tube and the rectangular wires to be tested 4 groups will be designed. Torsional force was applied by instron machine. The torque angle at 5Nmm and at 20Nmm point will be calculated: which means, how many degrees of torque is required to reach the maximum 20Nmm moment from the minimum 5Nmm.One-way ANOVA was used to compare torque angle in all of the groups. Results The least amount of clinically significant angle was 2.2 ᵒ in the 0.017×0.025 SS and the largest amount of it was 23.7 ᵒ in the 0.017×0.025 TMA in 0.018×0.025 slot molar tube. But, this angle was 19.9 ᵒand 13.6 ᵒ in 0.019×0.025 SS and 0.019×0.025 TMA archwire in 0.022×0.028 molar tube. Conclusions The 0.017×0.025 SS archwire in 0.018×0.025 molar tube had the lowest clinically significant angle. The largest amount was seen in group 0.017×0.025 TMA in 0.018×0.025 slot molar tube. Key words: Torsional efficacy, rectangular wires, buccal tubes, torque angle. PMID:29670712

Shear bond strength of brackets on restorative materials: Comparison on various dental restorative materials using the universal primer Monobond® Plus.

PubMed

Ebert, Thomas; Elsner, Laura; Hirschfelder, Ursula; Hanke, Sebastian

2016-03-01

The purpose of this work was to analyze surfaces consisting of different restorative materials for shear bond strength (SBS) and failure patterns of metal and ceramic brackets. Bonding involved the use of a universal primer (Monobond® Plus, Ivoclar Vivadent). Six restorative materials were tested, including one composite resin (Clearfil Majesty™ Posterior, Kuraray Noritake Dental), one glass-ceramic material (IPS Empress® Esthetic, Ivoclar Vivadent), one oxide-ceramic material (CORiTEC Zr transpa Disc, imes-icore), two base-metal alloys (remanium® star, Dentaurum; Colado® CC, Ivoclar Vivadent), and one palladium-based alloy (Callisto® 75 Pd, Ivoclar Vivadent). Bovine incisors served as controls. Both metal and ceramic brackets (discovery®/discovery® pearl; Dentaurum) were bonded to the restorative surfaces after sandblasting and pretreatment with Monobond® Plus. A setup modified from DIN 13990-2 was used for SBS testing and adhesive remnant index (ARI)-based analysis of failure patterns. The metal brackets showed the highest mean SBS values on the glass-ceramic material (68.61 N/mm(2)) and the composite resin (67.58 N/mm(2)) and the lowest mean SBS on one of the base-metal alloys (Colado® CC; 14.01 N/mm(2)). The ceramic brackets showed the highest mean SBS on the glass-ceramic material (63.36 N/mm(2)) and the lowest mean SBS on the palladium-based alloy (38.48 N/mm(2)). Significant differences between the metal and ceramic brackets were observed in terms of both SBS values and ARI scores (p < 0.05). Under both bracket types, fractures of the composite-resin and the glass-ceramic samples were observed upon debonding. Opaque restorative materials under metal brackets were found to involve undercuring of the adhesive. Monobond® Plus succeeded in generating high bond strengths of both bracket types on all restorative surfaces. Given our observations of cohesive fracture (including cases of surface avulsion) of the composite-resin and the glass

Curvature measurement with photonic crystal fiber based Mach-Zehnder interferometer

NASA Astrophysics Data System (ADS)

Deng, Ming; Tang, Chang-Ping; Zhu, Tao; Rao, Yun-Jiang

2011-05-01

A PCF-based MZI with regular and high-contrast fringe pattern is fabricated by splicing a section of PCF in between two SMFs with a commercial available fusion splicer. Its resonant wavelength is sensitive to external bending with a sensitivity of 3.046nm/m but independent on temperature. To that end, we also propose another kind of bending sensor with higher sensitivity of 5.129nm/m. This device is constructed by combining an LPG and an MZI with zero offset at the second splice. It is anticipated that the high sensitive structures will find applications in robot arms and artificial limbs.

The Neural Basis of Taste-visual Modal Conflict Control in Appetitive and Aversive Gustatory Context.

PubMed

Xiao, Xiao; Dupuis-Roy, Nicolas; Jiang, Jun; Du, Xue; Zhang, Mingmin; Zhang, Qinglin

2018-02-21

The functional magnetic resonance imaging (fMRI) technique was used to investigate brain activations related to conflict control in a taste-visual cross-modal pairing task. On each trial, participants had to decide whether the taste of a gustatory stimulus matched or did not match the expected taste of the food item depicted in an image. There were four conditions: Negative match (NM; sour gustatory stimulus and image of sour food), negative mismatch (NMM; sour gustatory stimulus and image of sweet food), positive match (PM; sweet gustatory stimulus and image of sweet food), positive mismatch (PMM; sweet gustatory stimulus and image of sour food). Blood oxygenation level-dependent (BOLD) contrasts between the NMM and the NM conditions revealed an increased activity in the middle frontal gyrus (MFG) (BA 6), the lingual gyrus (LG) (BA 18), and the postcentral gyrus. Furthermore, the NMM minus NM BOLD differences observed in the MFG were correlated with the NMM minus NM differences in response time. These activations were specifically associated with conflict control during the aversive gustatory stimulation. BOLD contrasts between the PMM and the PM condition revealed no significant positive activation, which supported the hypothesis that the human brain is especially sensitive to aversive stimuli. Altogether, these results suggest that the MFG is associated with the taste-visual cross-modal conflict control. A possible role of the LG as an information conflict detector at an early perceptual stage is further discussed, along with a possible involvement of the postcentral gyrus in the processing of the taste-visual cross-modal sensory contrast. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

Intrinsic Predictive Factors of Noncontact Lateral Ankle Sprain in Collegiate Athletes

PubMed Central

Kobayashi, Takumi; Yoshida, Masahiro; Yoshida, Makoto; Gamada, Kazuyoshi

2013-01-01

Background: Lateral ankle sprain (LAS) is one of the most common injuries in sports. Despite extensive research, intrinsic factors that predict initial and recurrent noncontact LAS remain undefined. Purpose: To identify the predictive factors of initial and recurrent noncontact LAS, focusing on ankle flexibility and/or alignment in collegiate athletes. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 191 athletes were assessed during the preseason for factors predictive of noncontact LAS. The baseline measurements included weightbearing dorsiflexion range of motion (ROM), leg-heel angle, foot internal rotation angle in plantar flexion, classification according to the mortise test, and navicular–medial malleolus (NMM) distance. Occurrence of noncontact LAS and participation in practice and games were prospectively recorded for 11 months. Results: Of the 191 athletes assessed, 169 (145 males, 24 females) completed the study; 125 athletes had a history of ankle sprain. During the observational period, 16 athletes suffered noncontact LAS (0.58 per 1000 athlete-exposures) consisting of 4 initial sprains and 12 recurrences. The hazard ratio estimated by a Cox regression analysis showed that athletes with an NMM distance ≥4.65 cm were 4.14 times more likely to suffer an initial noncontact LAS than were athletes with a shorter NMM distance (95% confidence interval, 1.12-14.30) and that athletes with a weightbearing dorsiflexion ROM >49.5° were 1.12 times as likely to suffer a recurrent noncontact LAS compared with athletes with a lower ROM (95% confidence interval, 1.05-1.20). Conclusion: NMM distance predicts initial noncontact LAS, and weightbearing dorsiflexion ROM predicts recurrent noncontact LAS. PMID:26535263

Optimization Of Fluoride Glass Fiber Drawing With Respect To Mechanical Strength

NASA Astrophysics Data System (ADS)

Schneider, H. W.; Schoberth, A.; Staudt, A.; Gerndt, Ch.

1987-08-01

Heavy metal fluoride fibers have attracted considerable attention recently as lightguides for infrared optical devices. Besides the optical loss mechanical performance of the fiber is of major interest. At present fiber strength suffers from surface crystallization prior to or during fiber drawing. We developed an etching method for the preparation of preforms with clean surface. Drawing these preforms under optimized conditions in a dry atmosphere results in fibers with improved strength. So far, mean value of 400 N/mm2 tensile strength have been achieved. Maximum values of 800 N/mm2 measured on etched fibers indicate an even higher strength potential for the material itself.

Type IV Effector Proteins Involved in the Medicago-Sinorhizobium Symbiosis.

PubMed

Nelson, Matthew S; Chun, Chan Lan; Sadowsky, Michael J

2017-01-01

In this study, we investigated genetic elements of the type IV secretion system (T4SS) found in Sinorhizobium spp. and the role they play in symbiosis. Sinorhizobium meliloti and S. medicae each contain a putative T4SS similar to that used by Agrobacterium tumefaciens during pathogenesis. The Cre reporter assay for translocation system was used to validate potential effector proteins. Both S. meliloti and S. medicae contained the effector protein TfeA, which was translocated into the host plant. Sequence analysis revealed the presence of a nod box involved in transcriptional activation of symbiosis-related genes, upstream of the transcriptional regulator (virG) in the Sinorhizobium T4SS. Replicate quantitative reverse transcription-polymerase chain reaction analyses indicated that luteolin, released by roots and seeds of Medicago truncatula, upregulated transcription of tfeA and virG. Mutations in the T4SS apparatus or tfeA alone resulted in reduced numbers of nodules formed on M. truncatula genotypes. In addition, S. meliloti KH46c, which contains a deletion in the T4SS, was less competitive for nodule formation when coinoculated with an equal number of cells of the wild-type strain. To our knowledge, TfeA is the first T4SS effector protein identified in Sinorhizobium spp. Our results indicate that Sinorhizobium i) uses a T4SS during initiation of symbiosis with Medicago spp., and ii) alters Medicago cells in planta during symbiosis. This study also offers additional bioinformatic evidence that several different rhizobial species may use the T4SS in symbiosis with other legumes.

Mini-Fragment Fixation Is Equivalent to Bicortical Screw Fixation for Horizontal Medial Malleolus Fractures.

PubMed

Wegner, Adam M; Wolinsky, Philip R; Robbins, Michael A; Garcia, Tanya C; Amanatullah, Derek F

2018-05-01

Horizontal fractures of the medial malleolus occur through application of valgus or abduction force through the ankle that creates a tension failure of the medial malleolus. The authors hypothesize that mini-fragment T-plates may offer improved fixation, but the optimal fixation construct for these fractures remains unclear. Forty synthetic distal tibiae with identical osteotomies were randomized into 4 fixation constructs: (1) two parallel unicortical cancellous screws; (2) two parallel bicortical cortical screws; (3) a contoured mini-fragment T-plate with 2 unicortical screws in the fragment and 2 bicortical screws in the shaft; and (4) a contoured mini-fragment T-plate with 2 bicortical screws in the fragment and 2 unicortical screws in the shaft. Specimens were subjected to offset axial tension loading on a servohydraulic testing system and tracked using high-resolution video. Failure was defined as 2 mm of articular displacement. Analysis of variance followed by a Tukey-Kramer post hoc test was used to assess for differences between groups, with significance defined as P<.05. The mean stiffness (±SD) values of both mini-fragment T-plate constructs (239±83 N/mm and 190±37 N/mm) and the bicortical screw construct (240±17 N/mm) were not statistically different. The mean stiffness values of both mini-fragment T-plate constructs and the bicortical screw construct were higher than that of a parallel unicortical screw construct (102±20 N/mm). Contoured T-plate constructs provide stiffer initial fixation than a unicortical cancellous screw construct. The T-plate is biomechanically equivalent to a bicortical screw construct, but may be superior in capturing small fragments of bone. [Orthopedics. 2018; 41(3):e395-e399.]. Copyright 2018, SLACK Incorporated.

Implant material and design alter construct stiffness in distal femur locking plate fixation: a pilot study.

PubMed

Schmidt, Ulf; Penzkofer, Rainer; Bachmaier, Samuel; Augat, Peter

2013-09-01

Construct stiffness affects healing of bones fixed with locking plates. However, variable construct stiffness reported in the literature may be attributable to differing test configurations and direct comparisons may clarify these differences. We therefore asked whether different distal femur locking plate systems and constructs will lead to different (1) axial and rotational stiffness and (2) fatigue under cyclic loading. We investigated four plate systems for distal femur fixation (AxSOS, LCP, PERI-LOC, POLYAX) of differing designs and materials using bone substitutes in a distal femur fracture model (OTA/AO 33-A3). We created six constructs of each of the four plating systems. Stiffness under static and cyclic loading and fatigue under cyclic loading were measured. Mean construct stiffness under axial loading was highest for AxSOS (100.8 N/mm) followed by PERI-LOC (80.8 N/mm) and LCP (62.6 N/mm). POLYAX construct stiffness testing showed the lowest stiffness (51.7 N/mm) with 50% stiffness of AxSOS construct testing. Mean construct stiffness under torsional loading was similar in the group of AxSOS and PERI-LOC (3.40 Nm/degree versus 3.15 Nm/degree) and in the group of LCP and POLYAX (2.63 Nm/degree versus 2.56 Nm/degree). The fourth load level of > 75,000 cycles was reached by three of six AxSOS, three of six POLYAX, and two of six PERI-LOC constructs. All others including all LCP constructs failed earlier. Implant design and material of new-generation distal femur locking plate systems leads to a wide range of differences in construct stiffness. Assuming construct stiffness affects fracture healing, these data may influence surgical decision-making in choosing an implant system.

RELATIONSHIP BETWEEN RIGIDITY OF EXTERNAL FIXATOR AND NUMBER OF PINS: COMPUTER ANALYSIS USING FINITE ELEMENTS

PubMed Central

Sternick, Marcelo Back; Dallacosta, Darlan; Bento, Daniela Águida; do Reis, Marcelo Lemos

2015-01-01

Objective: To analyze the rigidity of a platform-type external fixator assembly, according to different numbers of pins on each clamp. Methods: Computer simulation on a large-sized Cromus dynamic external fixator (Baumer SA) was performed using a finite element method, in accordance with the standard ASTM F1541. The models were generated with approximately 450,000 quadratic tetrahedral elements. Assemblies with two, three and four Schanz pins of 5.5 mm in diameter in each clamp were compared. Every model was subjected to a maximum force of 200 N, divided into 10 sub-steps. For the components, the behavior of the material was assumed to be linear, elastic, isotropic and homogeneous. For each model, the rigidity of the assembly and the Von Mises stress distribution were evaluated. Results: The rigidity of the system was 307.6 N/mm for two pins, 369.0 N/mm for three and 437.9 N/mm for four. Conclusion: The results showed that four Schanz pins in each clamp promoted rigidity that was 19% greater than in the configuration with three pins and 42% greater than with two pins. Higher tension occurred in configurations with fewer pins. In the models analyzed, the maximum tension occurred on the surface of the pin, close to the fixation area. PMID:27047879

Selective recognition of parallel and anti-parallel thrombin-binding aptamer G-quadruplexes by different fluorescent dyes

PubMed Central

Zhao, Dan; Dong, Xiongwei; Jiang, Nan; Zhang, Dan; Liu, Changlin

2014-01-01

G-quadruplexes (G4) have been found increasing potential in applications, such as molecular therapeutics, diagnostics and sensing. Both Thioflavin T (ThT) and N-Methyl mesoporphyrin IX (NMM) become fluorescent in the presence of most G4, but thrombin-binding aptamer (TBA) has been reported as the only exception of the known G4-forming oligonucleotides when ThT is used as a high-throughput assay to identify G4 formation. Here, we investigate the interactions between ThT/NMM and TBA through fluorescence spectroscopy, circular dichroism and molecular docking simulation experiments in the absence or presence of cations. The results display that a large ThT fluorescence enhancement can be observed only when ThT bind to the parallel TBA quadruplex, which is induced to form by ThT in the absence of cations. On the other hand, great promotion in NMM fluorescence can be obtained only in the presence of anti-parallel TBA quadruplex, which is induced to fold by K+ or thrombin. The highly selective recognition of TBA quadruplex with different topologies by the two probes may be useful to investigate the interactions between conformation-specific G4 and the associated proteins, and could also be applied in label-free fluorescent sensing of other biomolecules. PMID:25245945

Does Man Marking Influence Running Outputs and Intensity During Small-Sided Soccer Games?

PubMed

Aasgaard, Mats; Kilding, Andrew E

2018-06-20

Aasgaard, M and Kilding, AE. Does man marking influence running outputs and intensity during small-sided soccer games? J Strength Cond Res XX(X): 000-000, 2018-Small-sided games (SSGs) are considered an effective training tool for physical development in soccer. Small-sided games can be modified in several ways to manipulate the physical demands to best match the game demands, player characteristics, and session objectives. The aim of this study was to compare the physiological, perceptual, and Global Positioning System (GPS)-derived time-motion characteristics of man marking (MM) vs. non-man marking (NMM) in 2v2, 3v3, and 4v4 SSGs. In an acute crossover design, 8 amateur soccer players (mean age ± SD: 23.6 ± 3.3 years) played 2v2, 3v3, and 4v4 SSGs consisting of 4 × 4-minute bouts, with 2-minute passive recovery. During all SSGs, players wore a heart rate (HR) monitor and GPS unit and reported their rating of perceived exertion (RPE). Average percent HR (%HRave) induced small to moderate effects with MM compared with NMM (%Δ = 1-2.7%; effect size [ES] = 0.22-0.65). Comparisons between MM formats indicated a decrease in %HRave with increased player numbers (%Δ = 1.6-3.5%; ES = 0.39-0.86). Perceptual load increased with MM compared with NMM (%Δ = 6.7-17.6%; ES = 0.66-2.09), whereas increases in player numbers (MM only) reduced RPE output (%Δ = 9.4-24.3%; ES = 1.14-3.61). Time-motion characteristics revealed substantially greater total distance covered in MM irrespective of player number (%Δ = 6.8-14.7%; ES = 1.34-2.82). There were very likely increases in distances covered at striding (13.1-17.8 km·h) (%Δ: 23.4-33.2; ES = 2.42-4.35) and high-intensity running (HIR) (17.9-21 km·h) (%Δ: 47.3-104; ES = 0.91-1.68) for MM compared with NMM irrespective of player number. In conclusion, MM substantially elevated perceptual load and distances from striding to HIR regardless of player number, whereas differences between NMM and MM for internal load remain unclear

Mechanical effects of third-order movement in self-ligated brackets by the measurement of torque expression.

PubMed

Major, Thomas W; Carey, Jason P; Nobes, David S; Heo, Giseon; Major, Paul W

2011-01-01

Axial rotation of orthodontic wire produces buccal or lingual root movement and is often referred to as third-order movement or "torque expression." The objective of this study was to quantify torque expression in 3 self-ligation bracket systems (Damon Q, Ormco, Orange, Calif; In-Ovation R, GAC, Bohemia, NY; and Speed, Strite Industries, Cambridge, Ontario, Canada) during loading and unloading. A stepper motor was used to rotate a wire in a fixed bracket slot from -15° to 63° in 3° increments, and then back to -15°. The bracket was mounted on top of a load cell that measured forces and moments in all directions. Damon's and In-Ovation's maximum average torque values at 63° were 105 and 113 Nmm, respectively. Many Speed brackets experienced premature loss of torque between 48° and 63°, and the average maximum was 82 Nmm at 54°. The torque plays for Damon, In-Ovation, and Speed were 11.3°, 11.9°, and 10.8°, respectively. Generally, In-Ovation expressed the most torque at a given angle of twist, followed by Damon and then Speed. However, there was no significant difference between brackets below 34 Nmm of torque. From a clinical perspective, the torque plays between brackets were virtually indistinguishable. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Biomechanical measurements of stopping and stripping torques during screw insertion in five types of human and artificial humeri.

PubMed

Aziz, Mina Sr; Tsuji, Matthew Rs; Nicayenzi, Bruce; Crookshank, Meghan C; Bougherara, Habiba; Schemitsch, Emil H; Zdero, Radovan

2014-05-01

During orthopedic surgery, screws are inserted by "subjective feel" in humeri for fracture fixation, that is, stopping torque, while trying to prevent accidental over-tightening that causes screw-bone interface failure, that is, stripping torque. However, no studies exist on stopping torque, stripping torque, or stopping/stripping torque ratio in human or artificial humeri. This study evaluated five types of humeri, namely, human fresh-frozen (n = 19), human embalmed (n = 18), human dried (n = 15), artificial "normal" (n = 13), and artificial "osteoporotic" (n = 13). An orthopedic surgeon used a torque screwdriver to insert 3.5-mm-diameter cortical screws into humeral shafts and 6.5-mm-diameter cancellous screws into humeral heads by "subjective feel" to obtain stopping and stripping torques. The five outcome measures were raw and normalized stopping torque, raw and normalized stripping torque, and stopping/stripping torque ratio. Normalization was done as raw torque/screw-bone interface area. For "gold standard" fresh-frozen humeri, cortical screw tests yielded averages of 1312 N mm (raw stopping torque), 30.4 N/mm (normalized stopping torque), 1721 N mm (raw stripping torque), 39.0 N/mm (normalized stripping torque), and 82% (stopping/stripping torque ratio). Similarly, fresh-frozen humeri gave cancellous screw average results of 307 N mm (raw stopping torque), 0.9 N/mm (normalized stopping torque), 392 N mm (raw stripping torque), 1.2 N/mm (normalized stripping torque), and 79% (stopping/stripping torque ratio). Of the five cortical screw parameters for fresh-frozen humeri versus other groups, statistical equivalence (p ≥ 0.05) occurred in four cases (embalmed), three cases (dried), four cases (artificial "normal"), and four cases (artificial "osteoporotic"). Of the five cancellous screw parameters for fresh-frozen humeri versus other groups, statistical equivalence (p ≥ 0.05) occurred in five cases (embalmed), one case (dried), one case (artificial "normal

Torque efficiency of different archwires in 0.018- and 0.022-inch conventional brackets.

PubMed

Sifakakis, Iosif; Pandis, Nikolaos; Makou, Margarita; Eliades, Theodore; Katsaros, Christos; Bourauel, Christoph

2014-01-01

To compare the archwires inserted during the final stages of the orthodontic treatment with the generated moments at 0.018- and 0.022-inch brackets. The same bracket type, in terms of prescription, was evaluated in both slot dimensions. The brackets were bonded on two identical maxillary acrylic resin models, and each model was mounted on the orthodontic measurement and simulation system. Ten 0.017 × 0.025-inch TMA and ten 0.017 × 0.025-inch stainless steel archwires were evaluated in the 0.018-inch brackets. In the 0.022-inch brackets, ten 0.019 × 0.025-inch TMA and ten 0.019 × 0.025-inch stainless steel archwires were measured. A 15° buccal root torque (+15°) and then a 15° palatal root torque (-15°) were gradually applied to the right central incisor bracket, and the moments were recorded at these positions. A t-test was conducted to compare the generated moments between wires within the 0.018- and 0.022-inch bracket groups separately. The 0.017 × 0.025-inch archwire in the 0.018-inch brackets generated mean moments of 9.25 Nmm and 14.2 Nmm for the TMA and stainless steel archwires, respectively. The measured moments in the 0.022-inch brackets with the 0.019 × 0.025-inch TMA and stainless steel archwires were 6.6 Nmm and 9.3 Nmm, respectively. The 0.017 × 0.025-inch stainless steel and β-Ti archwires in the 0.018-inch slot generated higher moments than the 0.019 × 0.025-inch archwires because of lower torque play. This difference is exaggerated in steel archwires, in comparison with the β-Ti, because of differences in stiffness. The differences of maximum moments between the archwires of the same cross-section but different alloys were statistically significant at both slot dimensions.

Anatomic suture anchor versus the Broström technique for anterior talofibular ligament repair: a biomechanical comparison.

PubMed

Waldrop, Norman E; Wijdicks, Coen A; Jansson, Kyle S; LaPrade, Robert F; Clanton, Thomas O

2012-11-01

Despite the popularity of the Broström procedure for secondary repair of chronic lateral ankle instability, there have been no biomechanical studies reporting on the strength of this secondary repair method, whether using suture fixation or suture anchors. The purpose of our study was to perform a biomechanical comparison of the ultimate load to failure and stiffness of the traditional Broström technique using only a suture repair compared with a suture anchor repair of the anterior talofibular ligament (ATFL) at time zero. We believed that fixation strength of the suture anchor repair would be closer to the strength of the native ligament and allow more aggressive rehabilitation. Controlled laboratory study. Twenty-four fresh-frozen cadaveric ankles were randomly divided into 4 groups of 6 specimens. One group was an intact control group, and the other groups consisted of the traditional Broström and 2 suture anchor modifications (suture anchors in talus or fibula) of the Broström procedure. The specimens were loaded to failure to determine the strength and stiffness of each construct. In load-to-failure testing, ultimate failure loads of the Broström (68.2 ± 27.8 N; P = .013), suture anchor fibula (79.2 ± 34.3 N; P = .037), and suture anchor talus (75.3 ± 45.6 N; P = .027) repairs were significantly lower than that of the intact (160.9 ± 72.2 N) ATFL group. Stiffness of the Broström (6.0 ± 2.5 N/mm; P = .02), suture anchor fibula (6.8 N/mm ± 2.7; P = .05), and suture anchor talus (6.6 N/mm ± 4.0; P = .04) repairs were significantly lower than that of the intact (12.4 N/mm ± 4.1 N/mm) ATFL group. The 3 repair groups were not significantly different from each other, but all 3 were substantially lower in strength and stiffness when compared to the intact ATFL. The use of suture anchors to repair the ATFL produces a repair that can withstand loads to failure similar to the suture-only Broström repair. However, all 3 repair groups were much weaker than

Mechanical design of experimental apparatus for FIREX cryo-target cooling

NASA Astrophysics Data System (ADS)

Iwamoto, A.; Norimatsu, T.; Nakai, M.; Sakagami, H.; Fujioka, S.; Shiraga, H.; Azechi, H.

2016-05-01

Mechanical design of an experimental apparatus for FIREX cryo-target cooling is described. Gaseous helium (GHe) sealing system at a cryogenic environment is an important issue for laser fusion experiments. The dedicated loading system was designed for a metal gasket. We take U-TIGHTSEAL® (Usui Kokusai Sangyo Kaisha. Ltd.) with an indium plated copper jacket as an example. According to its specification, a linear load of 110 N/m along its circumference is the optimum compression; however a lower load would still maintain helium (He) leak below the required level. Its sealing performance was investigated systematically. Our system demanded 27 N/mm of the load to keep He leak tightness in a cryogenic environment. Once leak tightness was obtained, it could be reduced to 9.5 N/mm.

Galvanised steel to aluminium joining by laser and GTAW processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sierra, G.; Universite Montpellier 2, Laboratoire de Mecanique et Genie Civil, UMR 5508 CNRS, Montpellier, 34095; Peyre, P.

A new means of assembling galvanised steel to aluminium involving a reaction between solid steel and liquid aluminium was developed, using laser and gas tungsten arc welding (GTAW) processes. A direct aluminium melting strategy was investigated with the laser process, whereas an aluminium-induced melting by steel heating and heat conduction through the steel was carried out with the GTAW process. The interfaces generated during the interaction were mainly composed of a 2-40 {mu}m thick intermetallic reaction layers. The linear strength of the assemblies can be as high as 250 N/mm and 190 N/mm for the assemblies produced respectively by lasermore » and GTAW processes. The corresponding failures were located in the fusion zone of aluminium (laser assemblies), or in the reaction layer (GTAW assemblies)« less

Stochastic study of solute transport in a nonstationary medium.

PubMed

Hu, Bill X

2006-01-01

A Lagrangian stochastic approach is applied to develop a method of moment for solute transport in a physically and chemically nonstationary medium. Stochastic governing equations for mean solute flux and solute covariance are analytically obtained in the first-order accuracy of log conductivity and/or chemical sorption variances and solved numerically using the finite-difference method. The developed method, the numerical method of moments (NMM), is used to predict radionuclide solute transport processes in the saturated zone below the Yucca Mountain project area. The mean, variance, and upper bound of the radionuclide mass flux through a control plane 5 km downstream of the footprint of the repository are calculated. According to their chemical sorption capacities, the various radionuclear chemicals are grouped as nonreactive, weakly sorbing, and strongly sorbing chemicals. The NMM method is used to study their transport processes and influence factors. To verify the method of moments, a Monte Carlo simulation is conducted for nonreactive chemical transport. Results indicate the results from the two methods are consistent, but the NMM method is computationally more efficient than the Monte Carlo method. This study adds to the ongoing debate in the literature on the effect of heterogeneity on solute transport prediction, especially on prediction uncertainty, by showing that the standard derivation of solute flux is larger than the mean solute flux even when the hydraulic conductivity within each geological layer is mild. This study provides a method that may become an efficient calculation tool for many environmental projects.

Macroscopic neural mass model constructed from a current-based network model of spiking neurons.

PubMed

Umehara, Hiroaki; Okada, Masato; Teramae, Jun-Nosuke; Naruse, Yasushi

2017-02-01

Neural mass models (NMMs) are efficient frameworks for describing macroscopic cortical dynamics including electroencephalogram and magnetoencephalogram signals. Originally, these models were formulated on an empirical basis of synaptic dynamics with relatively long time constants. By clarifying the relations between NMMs and the dynamics of microscopic structures such as neurons and synapses, we can better understand cortical and neural mechanisms from a multi-scale perspective. In a previous study, the NMMs were analytically derived by averaging the equations of synaptic dynamics over the neurons in the population and further averaging the equations of the membrane-potential dynamics. However, the averaging of synaptic current assumes that the neuron membrane potentials are nearly time invariant and that they remain at sub-threshold levels to retain the conductance-based model. This approximation limits the NMM to the non-firing state. In the present study, we newly propose a derivation of a NMM by alternatively approximating the synaptic current which is assumed to be independent of the membrane potential, thus adopting a current-based model. Our proposed model releases the constraint of the nearly constant membrane potential. We confirm that the obtained model is reducible to the previous model in the non-firing situation and that it reproduces the temporal mean values and relative power spectrum densities of the average membrane potentials for the spiking neurons. It is further ensured that the existing NMM properly models the averaged dynamics over individual neurons even if they are spiking in the populations.

Controlling retention, selectivity and magnitude of EOF by segmented monolithic columns consisting of octadecyl and naphthyl monolithic segments--applications to RP-CEC of both neutral and charged solutes.

PubMed

Karenga, Samuel; El Rassi, Ziad

2011-04-01

Monolithic capillaries made of two adjoining segments each filled with a different monolith were introduced for the control and manipulation of the electroosmotic flow (EOF), retention and selectivity in reversed phase-capillary electrochromatography (RP-CEC). These columns were called segmented monolithic columns (SMCs) where one segment was filled with a naphthyl methacrylate monolith (NMM) to provide hydrophobic and π-interactions, while the other segment was filled with an octadecyl acrylate monolith (ODM) to provide solely hydrophobic interaction. The ODM segment not only provided hydrophobic interactions but also functioned as the EOF accelerator segment. The average EOF of the SMC increased linearly with increasing the fractional length of the ODM segment. The neutral SMC provided a convenient way for tuning EOF, selectivity and retention in the absence of annoying electrostatic interactions and irreversible solute adsorption. The SMCs allowed the separation of a wide range of neutral solutes including polycyclic aromatic hydrocarbons (PAHs) that are difficult to separate using conventional alkyl-bonded stationary phases. In all cases, the k' of a given solute was a linear function of the fractional length of the ODM or NMM segment in the SMCs, thus facilitating the tailoring of a given SMC to solve a given separation problem. At some ODM fractional length, the fabricated SMC allowed the separation of charged solutes such as peptides and proteins that could not otherwise be achieved on a monolithic column made from NMM as an isotropic stationary phase due to the lower EOF exhibited by this monolith. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of the Rock Fragmentation Process by a Single TBM Cutter Using a Voronoi Element-Based Numerical Manifold Method

NASA Astrophysics Data System (ADS)

Liu, Quansheng; Jiang, Yalong; Wu, Zhijun; Xu, Xiangyu; Liu, Qi

2018-04-01

In this study, a two-dimensional Voronoi element-based numerical manifold method (VE-NMM) is developed to analyze the granite fragmentation process by a single tunnel boring machine (TBM) cutter under different confining stresses. A Voronoi tessellation technique is adopted to generate the polygonal grain assemblage to approximate the microstructure of granite sample from the Gubei colliery of Huainan mining area in China. A modified interface contact model with cohesion and tensile strength is embedded into the numerical manifold method (NMM) to interpret the interactions between the rock grains. Numerical uniaxial compression and Brazilian splitting tests are first conducted to calibrate and validate the VE-NMM models based on the laboratory experiment results using a trial-and-error method. On this basis, numerical simulations of rock fragmentation by a single TBM cutter are conducted. The simulated crack initiation and propagation process as well as the indentation load-penetration depth behaviors in the numerical models accurately predict the laboratory indentation test results. The influence of confining stress on rock fragmentation is also investigated. Simulation results show that radial tensile cracks are more likely to be generated under a low confining stress, eventually coalescing into a major fracture along the loading axis. However, with the increase in confining stress, more side cracks initiate and coalesce, resulting in the formation of rock chips at the upper surface of the model. In addition, the peak indentation load also increases with the increasing confining stress, indicating that a higher thrust force is usually needed during the TBM boring process in deep tunnels.

The effect of eccentric and concentric calf muscle training on Achilles tendon stiffness.

PubMed

Morrissey, Dylan; Roskilly, Anna; Twycross-Lewis, Richard; Isinkaye, Tomide; Screen, Hazel; Woledge, Roger; Bader, Dan

2011-03-01

To compare in vivo effects of eccentric and concentric calf muscle training on Achilles tendon stiffness, in subjects without tendinopathy. Thirty-eight recreational athletes completed 6 weeks eccentric (6 males, 13 females, 21.6  ±  2.2 years) or concentric training (8 males, 11 females, 21.1  ±  2.0 years). Achilles tendon stiffness, tendon modulus and single-leg jump height were measured before and after intervention. Exercise adherence was recorded using a diary. All data are reported as mean  ±  SD. Groups were matched for height and weight but the eccentric training group were more active at baseline (P < 0.05). Tendon stiffness was higher in the eccentrically trained group at baseline compared to the concentrically trained group (20.9  ±  7.3 N/mm v 13.38  ±  4.66 N/mm; P = 0.001) and decreased significantly after eccentric training (to 17.2 ( ±  5.9) N/mm (P = 0.035)). There was no stiffness change in the concentric group (P = 0.405). Stiffness modulus showed similar changes to stiffness. An inverse correlation was found between initial, and subsequent, reduction in stiffness (r = -0.66). Jump height did not change and no correlation between stiffness change and adherence was observed in either group (r = 0.01). Six weeks of eccentric training can alter Achilles tendon stiffness while a matched concentric programme shows no similar effects. Studies in patients with Achilles tendinopathy are warranted.

A Sterile 20 Family Kinase and Its Co-factor CCM-3 Regulate Contractile Ring Proteins on Germline Intercellular Bridges.

PubMed

Rehain-Bell, Kathryn; Love, Andrew; Werner, Michael E; MacLeod, Ian; Yates, John R; Maddox, Amy Shaub

2017-03-20

Germ cells in most animals are connected by intercellular bridges, actin-based rings that form stable cytoplasmic connections between cells promoting communication and coordination [1]. Moreover, these connections are required for fertility [1, 2]. Intercellular bridges are proposed to arise from stabilization of the cytokinetic ring during incomplete cytokinesis [1]. Paradoxically, proteins that promote closure of cytokinetic rings are enriched on stably open intercellular bridges [1, 3, 4]. Given this inconsistency, the mechanism of intercellular bridge stabilization is unclear. Here, we used the C. elegans germline as a model for identifying molecular mechanisms regulating intercellular bridges. We report that bridges are actually highly dynamic, changing size at precise times during germ cell development. We focused on the regulation of bridge stability by anillins, key regulators of cytokinetic rings and cytoplasmic bridges [1, 4-7]. We identified GCK-1, a conserved serine/threonine kinase [8], as a putative novel anillin interactor. GCK-1 works together with CCM-3, a known binding partner [9], to promote intercellular bridge stability and limit localization of both canonical anillin and non-muscle myosin II (NMM-II) to intercellular bridges. Additionally, we found that a shorter anillin, known to stabilize bridges [4, 7], also regulates NMM-II levels at bridges. Consistent with these results, negative regulators of NMM-II stabilize intercellular bridges in the Drosophila egg chamber [10, 11]. Together with our findings, this suggests that tuning of myosin levels is a conserved mechanism for the stabilization of intercellular bridges that can occur by diverse molecular mechanisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Locking plate fixation provides superior fixation of humerus split type greater tuberosity fractures than tension bands and double row suture bridges.

PubMed

Gaudelli, Cinzia; Ménard, Jérémie; Mutch, Jennifer; Laflamme, G-Yves; Petit, Yvan; Rouleau, Dominique M

2014-11-01

This paper aims to determine the strongest fixation method for split type greater tuberosity fractures of the proximal humerus by testing and comparing three fixation methods: a tension band with No. 2 wire suture, a double-row suture bridge with suture anchors, and a manually contoured calcaneal locking plate. Each method was tested on eight porcine humeri. A osteotomy of the greater tuberosity was performed 50° to the humeral shaft and then fixed according to one of three methods. The humeri were then placed in a testing apparatus and tension was applied along the supraspinatus tendon using a thermoelectric cooling clamp. The load required to produce 3mm and 5mm of displacement, as well as complete failure, was recorded using an axial load cell. The average load required to produce 3mm and 5mm of displacement was 658N and 1112N for the locking plate, 199N and 247N for the double row, and 75N and 105N for the tension band. The difference between the three groups was significant (P<0.01). The average load to failure of the locking plate (810N) was significantly stronger than double row (456N) and tension band (279N) (P<0.05). The stiffness of the locking plate (404N/mm) was significantly greater than double row (71N/mm) and tension band (33N/mm) (P<0.01). Locking plate fixation provides the strongest and stiffest biomechanical fixation for split type greater tuberosity fractures. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomechanical evaluation of a single-row versus double-row repair for complete subscapularis tears.

PubMed

Wellmann, Mathias; Wiebringhaus, Philipp; Lodde, Ina; Waizy, Hazibullah; Becher, Christoph; Raschke, Michael J; Petersen, Wolf

2009-12-01

The purpose of the study was to compare a single-row repair and a double-row repair technique for the specific characteristics of a complete subscapularis lesion. Ten pairs of human cadaveric shoulder human shoulder specimens were tested for stiffness and ultimate tensile strength of the intact tendons in a load to failure protocol. After a complete subscapularis tear was provoked, the specimens were assigned to two treatment groups: single-row repair (1) and a double-row repair using a "suture bridge" technique (2). After repair cyclic loading a subsequent load to failure protocol was performed to determine the ultimate tensile load, the stiffness and the elongation behaviour of the reconstructions. The intact subscapularis tendons had a mean stiffness of 115 N/mm and a mean ultimate load of 720 N. The predominant failure mode of the intact tendons was a tear at the humeral insertion site (65%). The double-row technique restored 48% of the ultimate load of the intact tendons (332 N), while the single-row technique revealed a significantly lower ultimate load of 244 N (P = 0.001). In terms of the stiffness, the double-row technique showed a mean stiffness of 81 N/mm which is significantly higher compared to the stiffness of the single-row repairs of 55 N/mm (P = 0.001). The double-row technique has been shown to be stronger and stiffer when compared to a conventional single-row repair. Therefore, this technique is recommended from a biomechanical point of view irrespectively if performed by an open or arthroscopic approach.

Influence of Abutment Design on Stiffness, Strength, and Failure of Implant-Supported Monolithic Resin Nano Ceramic (RNC) Crowns.

PubMed

Joda, Tim; Huber, Samuel; Bürki, Alexander; Zysset, Philippe; Brägger, Urs

2015-12-01

Recent technical development allows the digital manufacturing of monolithic reconstructions with high-performance materials. For implant-supported crowns, the fixation requires an abutment design onto which the reconstruction can be bonded. The aim of this laboratory investigation was to analyze stiffness, strength, and failure modes of implant-supported, computer-assisted design and computer-aided manufacturing (CAD/CAM)-generated resin nano ceramic (RNC) crowns bonded to three different titanium abutments. Eighteen monolithic RNC crowns were produced and loaded in a universal testing machine under quasi-static condition according to DIN ISO 14801. With regard to the type of titanium abutment, three groups were defined: (1) prefabricated cementable standard; (2) CAD/CAM-constructed individualized; and (3) novel prefabricated bonding base. Stiffness and strength were measured and analyzed statistically with Wilcoxon rank sum test. Sections of the specimens were examined microscopically. Stiffness demonstrated high stability for all specimens loaded in the physiological loading range with means and standard deviations of 1,579 ± 120 N/mm (group A), 1,733 ± 89 N/mm (group B), and 1,704 ± 162 N/mm (group C). Mean strength of the novel prefabricated bonding base (group C) was 17% lower than of the two other groups. Plastic deformations were detectable for all implant-abutment crown connections. Monolithic implant crowns made of RNC seem to represent a feasible and stable prosthetic construction under laboratory testing conditions with strength higher than the average occlusal force, independent of the different abutment designs used in this investigation. © 2014 Wiley Periodicals, Inc.

Soil profile water content determination:Spatiotemporal variability of electromagnetic and neutron probe sensors in access tubes

USDA-ARS?s Scientific Manuscript database

Since the late 1980s, electromagnetic (EM) sensors for determination on of soil water content from within nonmetallic access tubes have been marketed as replacements for the neutron moisture meter (NMM); however, the accuracy, variability and physical significance of EM sensor field measurements hav...

Combined active and passive microwave remote sensing of vegetated surfaces at l-band

USDA-ARS?s Scientific Manuscript database

In previous work the distorted Born approximation (DBA) of volume scattering was combined with the numerical solutions of Maxwell equations (NMM3D) for a rough surface to calculate the radar backscattering coefficient for the Soil Moisture Active Passive (SMAP) mission. The model results were valida...

Influence of Joint Configuration on the Strength of Laser Welded Presshardened Steel

NASA Astrophysics Data System (ADS)

Kügler, H.; Mittelstädt, C.; Vollertsen, F.

Presshardened steel is used in nowadays automotive production. Due to its high strength, sheet thicknesses can be reduced which results in decreasing weight of car body components. However, because of microstructure softening and coating agglomerations in the seam, welding is still a challenge. In this paper laser beam welding of 22MnB5 with varying energy input per irradiated area is presented. It is found that increasing energy input per seam length reduces tensile strength. Using a small spot size of 200 μm, tensile strength of 1434 N/mm2 can be reached in bead on plate welds. In lap welds tensile strength is limited because of coating particles agglomerating at the melt pool border line. However, the resulting strength is higher when using several small weld seams than using one seam with the same total seam width. With three weld seams, each 0.5mm in width, tensile strength of 911N/mm2 is reached in lap welding.

Performance of nanoscale metallic multilayer systems under mechanical and thermal loading

NASA Astrophysics Data System (ADS)

Economy, David Ross

Reports of nanoscale metallic multilayers (NMM) performance show a relatively high strength and radiation damage resistance when compared their monolithic components. Hardness of NMMs has been shown to increase with increasing interfacial density (i.e. decreasing layer thickness). This interface density-dependent behavior within NMMs has been shown to deviate from Hall-Petch strengthening, leading to higher measured strengths during normal loading than those predicted by a rule of mixtures. To fully understand why this occurs, other researchers have looked at the influence of the crystal structures of the component layers, orientations, and compositions on deformation processes. Additionally, a limited number of studies have focused on the structural stability and possible performance variation between as-deposited systems and those exposed to mechanical and thermal loading. This dissertation identified how NMM as-deposited structures and performance are altered by mechanical loading (sliding/wear contact) and/or thermal (such as diffusion, relaxation) loading. These objectives were pursued by tracking hardness evolution during sliding wear and after thermal loading to as-deposited stress and mechanical properties. Residual stress progression was also examined during thermal loading and supporting data was collected to detail structural and chemical changes. All of these experimental observations were conducted using Cu/Nb NMMs with 2 nm, 20 nm, or 100 nm thick individual layers deposited with either 1 microm or 10 microm total thicknesses with two geometries (Cu/Nb and Nb/Cu) on (100) Si. Wear boxes were performed on Cu/Nb NMM using a nanoindentation system with a 1 microm conical diamond counterface. After nano-wear deformation, the hardness of the deformed regions significantly rose with respect to as-deposited measurements, which further increased with greater wear loads. Additionally, NMMs with thinner layers showed less volume loss as measured by laser

Combined active and passive microwave remote sensing of soil moisture for vegetated surfaces at L-band

USDA-ARS?s Scientific Manuscript database

The distorted Born approximation (DBA) combined with the numerical solutions of Maxwell equations (NMM3D) has been used for the radar backscattering model for the SMAP mission. The models for vegetated surfaces such as wheat, grass, soybean and corn have been validated with the Soil Moisture Active ...

Compressive strength and initial water absorption rate for cement brick containing high-density polyethylene (HDPE) as a substitutional material for sand

NASA Astrophysics Data System (ADS)

Ali, Noorwirdawati; Din, Norhasmiza; Sheikh Khalid, Faisal; Shahidan, Shahiron; Radziah Abdullah, Siti; Samad, Abdul Aziz Abdul; Mohamad, Noridah

2017-11-01

The rapid growth of today’s construction sector requires high amount of building materials. Bricks, known to have solid properties and easy to handle, which leads to the variety of materials added or replaced in its mixture. In this study, high density polyethylene (HDPE) was selected as the substitute materials in the making of bricks. The reason behind the use of HDPE is because of its recyclable properties and the recycling process that do not emit hazardous gases to the atmosphere. Other than that, the use of HDPE will help reducing the source of pollution by avoiding the millions of accumulated plastic waste in the disposal sites. Furthermore, the material has high endurance level and is weatherproof. This study was carried out on experimenting the substitute materials in the mixture of cement bricks, a component of building materials which is normally manufactured using the mixture of cement, sand and water, following a certain ratios, and left dried to produce blocks of bricks. A series of three different percentages of HDPE were used, which were 2.5%, 3.0% and 3.5%. Tests were done on the bricks, to study its compressive strength and the initial water absorption rate. Both tests were conducted on the seventh and 28th day. Based on the results acquired, for compressive strength tests on the 28th day, the use of 2.5% of HDPE shown values of 12.6 N/mm2 while the use of 3.0% of HDPE shown values of 12.5 N/mm2. Onto the next percentage, 3.5% of HDPE shown values of 12.5 N/mm2.

Quadriceps tendon rupture: a biomechanical comparison of transosseous equivalent double-row suture anchor versus transosseous tunnel repair.

PubMed

Hart, Nathan D; Wallace, Matthew K; Scovell, J Field; Krupp, Ryan J; Cook, Chad; Wyland, Douglas J

2012-09-01

Quadriceps rupture off the patella is traditionally repaired by a transosseous tunnel technique, although a single-row suture anchor repair has recently been described. This study biomechanically tested a new transosseous equivalent (TE) double-row suture anchor technique compared with the transosseous repair for quadriceps repair. After simulated quadriceps-patella avulsion in 10 matched cadaveric knees, repairs were completed by either a three tunnel transosseous (TT = 5) or a TE suture anchor (TE = 5) technique. Double-row repairs were done using two 5.5 Bio-Corkscrew FT (fully threaded) (Arthrex, Inc., Naples, FL, USA) and two 3.5 Bio-PushLock anchors (Arthrex, Inc., Naples, FL, USA) with all 10 repairs done with #2 FiberWire suture (Arthrex, Inc., Naples, FL). Cyclic testing from 50 to 250 N for 250 cycles and pull to failure load (1 mm/s) were undertaken. Gap formation and ultimate tensile load (N) were recorded and stiffness data (N/mm) were calculated. Statistical analysis was performed using a Mann-Whitney U test and survival characteristics examined with Kaplan-Meier test. No significant difference was found between the TE and TT groups in stiffness (TE = 134 +/- 15 N/mm, TT = 132 +/- 26 N/mm, p = 0.28). The TE group had significantly less ultimate tensile load (N) compared with the TT group (TE = 447 +/- 86 N, TT = 591 +/- 84 N, p = 0.04), with all failures occurring at the suture eyelets. Although both quadriceps repairs were sufficiently strong, the transosseous repairs were stronger than the TE suture anchor repairs. The repair stiffness and gap formation were similar between the groups.

Unraveling the history of complex zoned garnets from the North Motagua Mélange (Guatemala)

NASA Astrophysics Data System (ADS)

Barickman, M. H.; Martin, C.; Flores, K. E.; Harlow, G. E.; Bonnet, G.

2016-12-01

The Guatemala Suture Zone (GSZ) is situated in central Guatemala, between the North American and Caribbean plates. Two serpentinite mélanges straddle the Motagua Fault system: the North Motagua Mélange (NMM) and the South Motagua Mélange (SMM). In this study, chemically zoned garnet grains from four eclogite blocks from the NMM were analyzed by EMPA for major elements and LA-ICP-MS for trace elements to unravel the geological history of the eclogites. These eclogites typically consist of euhedral to subhedral garnets, partly retrogressed omphacite grains, and accessory minerals such as phengite and epidote as inclusions in garnet. EBSD was employed to examine apparent garnet inclusions in garnet. The garnet grains in NMM eclogites display complex chemical zonations: all grains roughly show a spessartine-rich core, an almandine-rich core and/or intermediate zone, and a pyrope and grossular-rich rim. Additionally, crystal resorption can be observed between the different zones, and the pyrope-grossular rim can display oscillatory zoning. Finally, grossular-rich zones (crystallographically syntactic) within garnet are present in all studied samples. REE and spider diagrams do not show any significant difference in the patterns of the different zones within the garnet, or indicating that the chemical environment from which each garnet zone grew was broadly the same. The lack of significant variation in LILE content indicates that a fluid influx during garnet growth is unlikely. Consequently, we interpret that garnet grains grew in a largely closed system; however, the presence of the grossular-rich zones, argues for occasional excursions into conditions when either two garnets crystallized or Ca-rich overgrowths that were largely resorbed prior to subsequent continued garnet growth.

rhPDGF-BB promotes early healing in a rat rotator cuff repair model.

PubMed

Kovacevic, David; Gulotta, Lawrence V; Ying, Liang; Ehteshami, John R; Deng, Xiang-Hua; Rodeo, Scott A

2015-05-01

Tendon-bone healing after rotator cuff repair occurs by fibrovascular scar tissue formation, which is weaker than a normal tendon-bone insertion site. Growth factors play a role in tissue formation and have the potential to augment soft tissue healing in the perioperative period. Our study aim was to determine if rhPDGF-BB delivery on a collagen scaffold can improve tendon-to-bone healing after supraspinatus tendon repair compared with no growth factor in rats as measured by (1) gross observations; (2) histologic analysis; and (3) biomechanical testing. Ninety-five male Sprague-Dawley rats underwent acute repair of the supraspinatus tendon. Rats were randomized into one of five groups: control (ie, repair only), scaffold only, and three different platelet-derived growth factor (PDGF) doses on the collagen scaffold. Animals were euthanized 5 days after surgery to assess cellular proliferation and angiogenesis. The remaining animals were analyzed at 4 weeks to assess repair site integrity by gross visualization, fibrocartilage formation with safranin-O staining, and collagen fiber organization with picrosirius red staining, and to determine the biomechanical properties (ie, load-to-failure testing) of the supraspinatus tendon-bone construct. The repaired supraspinatus tendon was in continuity with the bone in all animals. At 5 days, rhPDGF-BB delivery on a scaffold demonstrated a dose-dependent response in cellular proliferation and angiogenesis compared with the control and scaffold groups. At 28 days, with the numbers available, rhPDGF-BB had no effect on increasing fibrocartilage formation or improving collagen fiber maturity at the tendon-bone insertion site compared with controls. The control group had higher tensile loads to failure and stiffness (35.5 ± 8.8 N and 20.3 ± 4.5 N/mm) than all the groups receiving the scaffold, including the PDGF groups (scaffold: 27 ± 6.4 N, p = 0.021 and 13 ± 5.7 N/mm, p = 0.01; 30 µg/mL PDGF: 26.5 ± 7.5 N, p = 0.014 and 13

Inventory of File sref_nmm.t03z.pgrb132.ctl.grib2

Science.gov Websites

UGRD analysis U-Component of Wind [m/s] 006 10 m above ground VGRD analysis V-Component of Wind [m/s of Wind [m/s] 018 250 mb VGRD analysis V-Component of Wind [m/s] 019 500 mb HGT analysis Geopotential Height [gpm] 020 500 mb UGRD analysis U-Component of Wind [m/s] 021 500 mb VGRD analysis V-Component of

Inventory of File sref_nmm.t03z.pgrb221.ctl.grib2

Science.gov Websites

UGRD analysis U-Component of Wind [m/s] 006 10 m above ground VGRD analysis V-Component of Wind [m/s of Wind [m/s] 018 250 mb VGRD analysis V-Component of Wind [m/s] 019 500 mb HGT analysis Geopotential Height [gpm] 020 500 mb UGRD analysis U-Component of Wind [m/s] 021 500 mb VGRD analysis V-Component of

Inventory of File sref_nmm.t03z.pgrb243.ctl.grib2

Science.gov Websites

UGRD analysis U-Component of Wind [m/s] 006 10 m above ground VGRD analysis V-Component of Wind [m/s of Wind [m/s] 018 250 mb VGRD analysis V-Component of Wind [m/s] 019 500 mb HGT analysis Geopotential Height [gpm] 020 500 mb UGRD analysis U-Component of Wind [m/s] 021 500 mb VGRD analysis V-Component of

Inventory of File sref_nmm.t03z.pgrb212.ctl.grib2

Science.gov Websites

UGRD analysis U-Component of Wind [m/s] 006 10 m above ground VGRD analysis V-Component of Wind [m/s of Wind [m/s] 018 250 mb VGRD analysis V-Component of Wind [m/s] 019 500 mb HGT analysis Geopotential Height [gpm] 020 500 mb UGRD analysis U-Component of Wind [m/s] 021 500 mb VGRD analysis V-Component of

Inventory of File sref_nmm.t03z.pgrb216.ctl.grib2

Science.gov Websites

UGRD analysis U-Component of Wind [m/s] 006 10 m above ground VGRD analysis V-Component of Wind [m/s of Wind [m/s] 018 250 mb VGRD analysis V-Component of Wind [m/s] 019 500 mb HGT analysis Geopotential Height [gpm] 020 500 mb UGRD analysis U-Component of Wind [m/s] 021 500 mb VGRD analysis V-Component of

Biomechanical properties of patellar and hamstring graft tibial fixation techniques in anterior cruciate ligament reconstruction: experimental study with roentgen stereometric analysis.

PubMed

Adam, Frank; Pape, Dietrich; Schiel, Karin; Steimer, Oliver; Kohn, Dieter; Rupp, Stefan

2004-01-01

Reliable fixation of the soft hamstring grafts in ACL reconstruction has been reported as problematic. The biomechanical properties of patellar tendon (PT) grafts fixed with biodegradable screws (PTBS) are superior compared to quadrupled hamstring grafts fixed with BioScrew (HBS) or Suture-Disc fixation (HSD). Controlled laboratory study with roentgen stereometric analysis (RSA). Ten porcine specimens were prepared for each group. In the PT group, the bone plugs were fixed with a 7 x 25 mm BioScrew. In the hamstring group, four-stranded tendon grafts were anchored within a tibial tunnel of 8 mm diameter either with a 7 x 25 mm BioScrew or eight polyester sutures knotted over a Suture-Disc. The grafts were loaded stepwise, and micromotion of the graft inside the tibial tunnel was measured with RSA. Hamstring grafts failed at lower loads (HBS: 536 N, HSD 445 N) than the PTBS grafts (658 N). Stiffness in the PTBS group was much greater compared to the hamstring groups (3500 N/mm versus HBS = 517 N/mm and HSD = 111 N/mm). Irreversible graft motion after graft loading with 200 N was measured at 0.03 mm (PTBS), 0.38mm (HBS), and 1.85mm (HSD). Elasticity for the HSD fixation was measured at 0.67 mm at 100 N and 1.32 mm at 200 N load. Hamstring graft fixation with BioScrew and Suture-Disc displayed less stiffness and early graft motion compared to PTBS fixation. Screw fixation of tendon grafts is superior to Suture-Disc fixation with linkage material since it offers greater stiffness and less graft motion inside the tibial tunnel. Our results revealed graft motion for hamstring fixation with screw or linkage material at loads that occur during rehabilitation. This, in turn, may lead to graft laxity.

A biomechanical comparison of four different cementless press-fit stems used in revision surgery for total knee replacements.

PubMed

Zdero, Radovan; Saidi, Kevan; Mason, Stephanie A; Schemitsch, Emil H; Naudie, Douglas D R

2012-11-01

Few biomechanical studies exist on femoral cementless press-fit stems for revision total knee replacement (TKR) surgeries. The aim of this study was to compare the mechanical quality of the femur-stem interface for a series of commercially available press-fit stems, because this interface may be a 'weak link' which could fail earlier than the femur-TKR bond itself. Also, the femur-stem interface may become particularly critical if distal femur bone degeneration, which may necessitate or follow revision TKR, ever weakens the femur-TKR bond itself. The authors implanted five synthetic femurs each with a Sigma Short Stem (SSS), Sigma Long Stem (SLS), Genesis II Short Stem (GSS), or Genesis II Long Stem (GLS). Axial stiffness, lateral stiffness, 'offset load' torsional stiffness, and 'offset load' torsional strength were measured with a mechanical testing system using displacement control. Axial (range = 1047-1461 N/mm, p = 0.106), lateral (range = 415-462 N/mm, p = 0.297), and torsional (range = 115-139 N/mm, p > 0.055) stiffnesses were not different between groups. The SSS had higher torsional strength (863 N) than the other stems (range = 167-197 N, p < 0.001). Torsional failure occurred by femoral 'spin' around the stem's long axis. There was poor linear correlation between the femur-stem interface area versus axial stiffness (R = 0.38) and torsional stiffness (R = 0.38), and there was a moderate linear correlation versus torsional strength (R = 0.55). Yet, there was a high inverse linear correlation between interfacial surface area versus lateral stiffness (R = 0.79), although this did not result in a statistical difference between stem groups (p = 0.297). These press-fit stems provide equivalent stability, except that the SSS has greater torsional strength.

The biomechanics of plate fixation of periprosthetic femoral fractures near the tip of a total hip implant: cables, screws, or both?

PubMed

Shah, S; Kim, S Y R; Dubov, A; Schemitsch, E H; Bougherara, H; Zdero, R

2011-09-01

Femoral shaft fractures after total hip arthroplasty (THA) remain a serious problem, since there is no optimal surgical repair method. Virtually all studies that examined surgical repair methods have done so clinically or experimentally. The present study assessed injury patterns computationally by developing three-dimensional (3D) finite element (FE) models that were validated experimentally. The investigation evaluated three different constructs for the fixation of Vancouver B1 periprosthetic femoral shaft fractures following THA. Experimentally, three bone plate repair methods were applied to a synthetic femur with a 5 mm fracture gap near the tip of a total hip implant. Repair methods were identical distal to the fracture gap, but used cables only (construct A), screws only (construct B), or cables plus screws (construct C) proximal to the fracture gap. Specimens were oriented in 15 degrees adduction to simulate the single-legged stance phase of walking, subjected to 1000 N of axial force, and instrumented with strain gauges. Computationally, a linearly elastic and isotropic 3D FE model was developed to mimic experiments. Results showed excellent agreement between experimental and FE strains, yielding a Pearson linearity coefficient, R2, of 0.92 and a slope for the line of best data fit of 1.06. FE-computed axial stiffnesses were 768 N/mm (construct A), 1023 N/mm (construct B), and 1102 N/mm (construct C). FE surfaces stress maps for cortical bone showed Von Mises stresses, excluding peaks, of 0-8 MPa (construct A), 0-15 MPa (construct B), and 0-20 MPa (construct C). Cables absorbed the majority of load, followed by the plates and then the screws. Construct A yielded peak stress at one of the empty holes in the plate. Constructs B and C had similar bone stress patterns, and can achieve optimal fixation.

Histological and biomechanical analysis of porous additive manufactured implants made by direct metal laser sintering: a pilot study in sheep.

PubMed

Stübinger, Stefan; Mosch, Isabel; Robotti, Pierfrancesco; Sidler, Michéle; Klein, Karina; Ferguson, Stephen J; von Rechenberg, Brigitte

2013-10-01

It was the aim of this study to analyze osseointegrative properties of porous additive manufactured titanium implants made by direct metal laser sintering in a sheep model after an implantation period of 2 and 8 weeks. Three different types of implants were placed in the pelvis of six sheep. In each sheep were placed three standard machined (M), three sandblasted and etched (SE), and three porous additive manufactured (AM) implants. Of these three implants (one per type) were examined histologically and six implants were tested biomechanically. Additionally a semiquantitative histomorphometrical and qualitative fluorescent microscopic analysis were performed. After 2 and 8 weeks bone-to-implant-contact (BIC) values of the AM surface (2w: 20.49% ± 5.18%; 8w: 43.91% ± 9.69%) revealed no statistical significant differences in comparison to the M (2w: 20.33% ± 11.50%; 8w: 25.33% ± 4.61%) and SE (2w: 43.67 ± 12.22%; 8w: 53.33 ± 8.96%) surfaces. AM surface showed the highest increase of the BIC between the two observation time points. Considering the same implantation period histomorphometry and fluorescent labelling disclosed no significant differences in the bone surrounding the three implants groups. In contrast Removal-torque-test showed a significant improve in fixation strength (P ≤ 0.001) for the AM (1891.82 ± 308, 44 Nmm) surface after eight weeks in comparison to the M (198.93±88,04 Nmm) and SE (730.08 ± 151,89 Nmm) surfaces. All three surfaces (M, SE, and AM) showed sound osseointegration. AM implants may offer a possible treatment option in clinics for patients with compromised bone situations. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

Biomechanical Analysis of an Arthroscopic Broström Ankle Ligament Repair and a Suture Anchor-Augmented Repair.

PubMed

Giza, Eric; Whitlow, Scott R; Williams, Brady T; Acevedo, Jorge I; Mangone, Peter G; Haytmanek, C Thomas; Curry, Eugene E; Turnbull, Travis Lee; LaPrade, Robert F; Wijdicks, Coen A; Clanton, Thomas O

2015-07-01

Secondary surgical repair of ankle ligaments is often indicated in cases of chronic lateral ankle instability. Recently, arthroscopic Broström techniques have been described, but biomechanical information is limited. The purpose of the present study was to analyze the biomechanical properties of an arthroscopic Broström repair and augmented repair with a proximally placed suture anchor. It was hypothesized that the arthroscopic Broström repairs would compare favorably to open techniques and that augmentation would increase the mean repair strength at time zero. Twenty (10 matched pairs) fresh-frozen foot and ankle cadaveric specimens were obtained. After sectioning of the lateral ankle ligaments, an arthroscopic Broström procedure was performed on each ankle using two 3.0-mm suture anchors with #0 braided polyethylene/polyester multifilament sutures. One specimen from each pair was augmented with a 2.9-mm suture anchor placed 3 cm proximal to the inferior tip of the lateral malleolus. Repairs were isolated and positioned in 20 degrees of inversion and 10 degrees of plantarflexion and loaded to failure using a dynamic tensile testing machine. Maximum load (N), stiffness (N/mm), and displacement at maximum load (mm) were recorded. There were no significant differences between standard arthroscopic repairs and the augmented repairs for mean maximum load and stiffness (154.4 ± 60.3 N, 9.8 ± 2.6 N/mm vs 194.2 ± 157.7 N, 10.5 ± 4.7 N/mm, P = .222, P = .685). Repair augmentation did not confer a significantly higher mean strength or stiffness at time zero. Mean strength and stiffness for the arthroscopic Broström repair compared favorably with previous similarly tested open repair and reconstruction methods, validating the clinical feasibility of an arthroscopic repair. However, augmentation with an additional proximal suture anchor did not significantly strengthen the repair. © The Author(s) 2015.

Embalmed and fresh frozen human bones in orthopedic cadaveric studies: which bone is authentic and feasible?

PubMed Central

2012-01-01

Background and purpose The most frequently used bones for mechanical testing of orthopedic and trauma devices are fresh frozen cadaveric bones, embalmed cadaveric bones, and artificial composite bones. Even today, the comparability of these different bone types has not been established. Methods We tested fresh frozen and embalmed cadaveric femora that were similar concerning age, sex, bone mineral density, and stiffness. Artificial composite femora were used as a reference group. Testing parameters were pullout forces of cortex and cancellous screws, maximum load until failure, and type of fracture generated. Results Stiffness and type of fracture generated (Pauwels III) were similar for all 3 bone types (fresh frozen: 969 N/mm, 95% confidence interval (CI): 897–1,039; embalmed: 999 N/mm, CI: 875–1,121; composite: 946 N/mm, CI: 852–1,040). Furthermore, no significant differences were found between fresh frozen and embalmed femora concerning pullout forces of cancellous screws (fresh frozen: 654 N, CI: 471–836; embalmed: 595 N, CI: 365–823) and cortex screws (fresh frozen: 1,152 N, CI: 894–1,408; embalmed: 1,461 N, CI: 880–2,042), and axial load until failure (fresh frozen: 3,427 N, CI: 2,564–4290; embalmed: 3,603 N, CI: 2,898–4,306). The reference group showed statistically significantly different results for pullout forces of cancellous screws (2,344 N, CI: 2,068–2,620) and cortex screws (5,536 N, CI: 5,203–5,867) and for the axial load until failure (> 7,952 N). Interpretation Embalmed femur bones and fresh frozen bones had similar characteristics by mechanical testing. Thus, we suggest that embalmed human cadaveric bone is a good and safe option for mechanical testing of orthopedic and trauma devices. PMID:22978564

Nickel titanium T-loop wire dimensions for en masse retraction.

PubMed

Almeida, Layene; Ribeiro, Alexandre; Parsekian Martins, Renato; Viecilli, Rodrigo; Parsekian Martins, Lídia

2016-09-01

To compare the force system produced by nickel-titanium T-loop springs made with wires of different dimensions. Thirty compound T-loop springs were divided into three groups according to the dimensions of the nickel-titanium wire used for its design: 0.016" × 0.022", 0.017" × 0.025", and 0.018" × 0.025". The loops were tested on the Orthodontic Force Tester machine at an interbracket distance of 23 mm and activated 9 mm. The force in the y-axis and the moment in the x-axis were registered while the calculated moment to force ratio was recorded at each .5 mm of deactivation. The data were analyzed by three analyses of variance of repeated measures to detect differences and interactions between deactivation and wire size on force, moment, and moment-force ratios (M/F). All groups had significantly different forces (P < .001). The 0.016" × 0.022" wire produced 1.78N of force while the 0.017" × 0.025" and the 0.018" × 0.025" produced 2.81 N and 3.25 N, respectively. The 0.016" × 0.022" wire produced lower moments (11.6 Nmm) than the 0.017" × 0.025" and 0.018" × 0.025" wires, which produced similar moments (13.9 Nmm and 14.4Nmm, respectively). The M/F produced was different for all groups; 0.016" × 0.022" T-loops produced 6.7 mm while the 0.017" × 0.025" and 0.018" × 0.025" T-loops produced 5.0 mm and 4.5 mm, respectively. An interaction was detected for all variables between deactivation and groups. The larger wires tested produced higher forces with slight increase on the moments, but the M/F produced by the 0.016" × 0.022" wire was the highest found.

Effects of sodium hypochlorite on Agave tequilana Weber bagasse fibers used to elaborate cyto and biocompatible hydrogel films.

PubMed

Tovar-Carrillo, Karla Lizette; Nakasone, Kazuki; Sugita, Satoshi; Tagaya, Motohiro; Kobayashi, Takaomi

2014-09-01

Waste bagasse of Agave tequilana-Weber fibers treated with sodium hydroxide was used to elaborate hydrogel films. The bagasse was offered in an alternative use for the preparation of hydrogel films by phase inversion method without crosslinking and further purification of cellulose. The effect on the properties of the obtained films was studied when the chemical treatment of the agave fibers was changed. It was found that the resultant hydrogels showed increment in tensile from 40 N/mm(2) to 56 N/mm(2) with the increase of sodium hypochlorite concentration from 1 to 10 vol.%, respectively. With regard to biocompatibility properties of the hydrogel films, platelet adhesion, clotting time and protein adsorption were investigated. Analysis of the morphology of adherent NIH3T3 fibroblast indicated that the projected cell area, aspect ratio and long axis gradually increased with the increment of sodium hypochlorite content in the agave treatment. It was presented that the chemical treatment affects cell adhesion and morphology and lignin content remains in the brown fibers. Copyright © 2014 Elsevier B.V. All rights reserved.

Feasibility of a Braided Composite for Orthopedic Bone Cast

PubMed Central

Evans, Katherine R; Carey, Jason P

2013-01-01

A tubular braided composite bone cast for improving the efficiency and quality of bone fracture treatment is investigated. Finite element analysis was used to evaluate stress concentrations in fracture sites supported with plate and tubular casts. The stress in a plated bone is 768 % of that in a whole bone at the same location, while it is only 47 % in a bone with a tubular cast. Three unbroken synthetic humeri were mechanically tested using an in-vitro long bone testing procedure developed in-house to find their stiffness at 20° and 60° abduction; these were found to be 116.8 ± 1.5 N/mm and 20.63 ± 0.02 N/mm, respectively. A 2 cm gap osteotomy was cut through the diaphysis in each bone. The bones were casted with a Kevlar/Cold cure composite, with calculated braid angles and thicknesses that Closely matched bone propoerties. The stiffness tests were repeated, and the results were within 10 % of the unbroken bone. This novel method of bone casting is promising if other clinical challenges can be minimized. PMID:23459455

Vertical force and torque analysis during mechanical preparation of extracted teeth using hand ProTaper instruments.

PubMed

Glavičić, Snježana; Anić, Ivica; Braut, Alen; Miletić, Ivana; Borčić, Josipa

2011-08-01

The purpose was to measure and analyse the vertical force and torque developed in the wider and narrower root canals during hand ProTaper instrumentation. Twenty human incisors were divided in two groups. Upper incisors were experimental model for the wide, while the lower incisors for the narrow root canals. Measurements of the force and torque were done by a device constructed for this purpose. Differences between the groups were statistically analysed by Mann-Whitney U-test with the significance level set to P<0.05. Vertical force in the upper incisors ranged 0.25-2.58 N, while in the lower incisors 0.38-6.94 N. Measured torque in the upper incisors ranged 0.53-12.03 Nmm, while in the lower incisor ranged 0.94-10.0 Nmm. Vertical force and torque were higher in the root canals of smaller diameter. The increase in the contact surface results in increase of the vertical force and torque as well in both narrower and wider root canals. © 2010 The Authors. Australian Endodontic Journal © 2010 Australian Society of Endodontology.

Reuse of industrial sludge as construction aggregates.

PubMed

Tay, J H; Show, K Y; Hong, S Y

2001-01-01

Industrial wastewater sludge and dredged marine clay are high volume wastes that needed enormous space at landfill disposal sites. Due to the limitation of land space, there is an urgent need for alternative disposal methods for these two wastes. This study investigates the possibility of using the industrial sludge in combination with marine clay as construction aggregates. Different proportions of sludge and clay were made into round and angular aggregates. It was found that certain mix proportions could provide aggregates of adequate strength, comparable to that of conventional aggregates. Concrete samples cast from the sludge-clay aggregates yield compressive strengths in the range of 31.0 to 39.0 N/mm2. The results showed that the round aggregates of 100% sludge and the crush aggregates of sludge with up to 20% clay produced concrete of compressive strengths which are superior to that of 38.0 N/mm2 for conventional aggregate. The study indicates that the conversion of high volume wastes into construction materials is a potential option for waste management.

Feasibility of a braided composite for orthopedic bone cast.

PubMed

Evans, Katherine R; Carey, Jason P

2013-01-01

A tubular braided composite bone cast for improving the efficiency and quality of bone fracture treatment is investigated. Finite element analysis was used to evaluate stress concentrations in fracture sites supported with plate and tubular casts. The stress in a plated bone is 768 % of that in a whole bone at the same location, while it is only 47 % in a bone with a tubular cast. Three unbroken synthetic humeri were mechanically tested using an in-vitro long bone testing procedure developed in-house to find their stiffness at 20° and 60° abduction; these were found to be 116.8 ± 1.5 N/mm and 20.63 ± 0.02 N/mm, respectively. A 2 cm gap osteotomy was cut through the diaphysis in each bone. The bones were casted with a Kevlar/Cold cure composite, with calculated braid angles and thicknesses that Closely matched bone propoerties. The stiffness tests were repeated, and the results were within 10 % of the unbroken bone. This novel method of bone casting is promising if other clinical challenges can be minimized.

Synthesis and characterization of iron based superconductor Nd-1111

NASA Astrophysics Data System (ADS)

Alborzi, Z.; Daadmehr, V.

2018-06-01

Polycrystalline sample of NdFeAsO0.8F0.2 was prepared by one-step solid-state reaction method. The structural and electrical properties of sample were characterized through XRD pattern and the 4-probe method. The critical temperature was obtained at 56 K. The crystal structure was tetragonal with P4/nmm:2 symmetry group.

The Mosquito Repellent Citronellal Directly Potentiates Drosophila TRPA1, Facilitating Feeding Suppression.

PubMed

Du, Eun Jo; Ahn, Tae Jung; Choi, Min Sung; Kwon, Ilmin; Kim, Hyung-Wook; Kwon, Jae Young; Kang, KyeongJin

2015-10-01

Citronellal, a well-known plant-derived mosquito repellent, was previously reported to repel Drosophila melanogaster via olfactory pathways involving but not directly activating Transient Receptor Potential Ankyrin 1 (TRPA1). Here, we show that citronellal is a direct agonist for Drosophila and human TRPA1s (dTRPA1 and hTRPA1) as well as Anopheles gambiae TRPA1 (agTRPA1). Citronellal-induced activity is isoform-dependent for Drosophila and Anopheles gambiae TRPA1s. The recently identified dTRPA1(A) and ag-TRPA1(A) isoforms showed citronellal-provoked currents with EC50s of 1.0 B1 0.2 and 0.1 B1 0.03 mM, respectively, in Xenopus oocytes, while the sensitivities of TRPA1(B)s were much inferior to those of TRPA1(A)s. Citronellal dramatically enhanced the feeding-inhibitory effect of the TRPA1 agonist N-methylmaleimide (NMM) in Drosophila at an NMM concentration that barely repels flies. Thus, citronellal can promote feeding deterrence of fruit flies through direct action on gustatory dTRPA1, revealing the first isoform-specific function for TRPA1(A).

First-principles prediction of low-energy structures for AlH3

NASA Astrophysics Data System (ADS)

Sun, Shoutian; Ke, Xuezhi; Chen, Changfeng; Tanaka, Isao

2009-01-01

We report density-functional calculations that predict ten different low-energy structures for aluminum hydride AlH3 with space groups Pnma , P6/mmm , I4/mcm , P4/mbm , P4/nmm , Pm3¯m , P21/m , P21/c , Pbcm , and P4/n . Phonon calculations within harmonic approximation reveal unstable modes in the P6/mmm , I4/mcm , P4/mbm , P4/nmm , Pm3¯m , P21/m , and P21/c structures, indicating that they are unstable at low temperatures. The calculations show that the thermodynamic stabilities for AlH3 with space groups Pnma , Pbcm , and P4/n are overall close to the existing α - and γ-AlH3 . From x-ray powder-diffraction patterns, the simulated main-peak positions for AlH3 (P4/n) are in good agreement with experimental δ-AlH3 . A full Rietveld analysis reveals that the fitting space groups R3¯c , Pbcm , and Pnma to the experimental x-ray powder-diffraction pattern of α-AlH3 gives almost the same satisfactory result.

Curvature and Temperature Measurement Based on a Few-Mode PCF Formed M-Z-I and an Embedded FBG.

PubMed

Liu, Hui; Yang, Hangzhou; Qiao, Xueguang; Wang, Yongqiang; Liu, Xiaochong; Lee, Yen-Sian; Lim, Kok-Sing; Ahmad, Harith

2017-07-27

We have experimentally demonstrated an optical fiber Mach-Zehnder interferometer (MZI) structure formed by a few-mode photonic crystal fiber (PCF) for curvature measurement and inscribed a fiber Bragg grating (FBG) in the PCF for the purpose of simultaneously measuring temperature. The structure consists of a PCF sandwiched between two multi-mode fibers (MMFs). Bending experimental results show that the proposed sensor has a sensitivity of -1.03 nm/m -1 at a curvature range from 10 m -1 to 22.4 m -1 , and the curvature sensitivity of the embedded FBG was -0.003 nm/m -1 . Temperature response experimental results showed that the MZI's wavelength, λ a , has a sensitivity of 60.3 pm/°C, and the FBG's Bragg wavelength, λ b , has sensitivity of 9.2 pm/°C in the temperature range of 8 to 100 °C. As such, it can be used for simultaneous measurement of curvature and temperature over ranges of 10 m -1 to 22.4 m -1 and 8 °C to 100 °C, respectively. The results show that the embedded FBG can be a good indicator to compensate the varying ambient temperature during a curvature measurement.

Design of Ceramic Springs for Use in Semiconductor Crystal Growth in Microgravity

NASA Technical Reports Server (NTRS)

Kaforey, M. F.; Deeb, C. W.; Matthiesen, D. H.

1999-01-01

Segregation studies can be done in microgravity to reduce buoyancy driven convection and investigate diffusion-controlled growth during the growth of semiconductor crystals. During these experiments, it is necessary to prevent free surface formation in order to avoid surface tension driven convection (Marangoni convection). Semiconductor materials such as gallium arsenide and germanium shrink upon melting, so a spring is necessary to reduce the volume of the growth chamber and prevent the formation of a free surface when the sample melts. A spring used in this application must be able to withstand both the high temperature and the processing atmosphere. During the growth of gallium arsenide crystals during the GTE Labs/USAF/NASA GaAs GAS Program and during the CWRU GaAs programs aboard the First and Second United States microgravity Laboratories, springs made of pyrolytic boron nitride (PBN) leaves were used. The mechanical properties of these PBN springs have been investigated and springs having spring constants ranging from 0.25 N/mm to 25 N/mm were measured. With this improved understanding comes the ability to design springs for more general applications, and guidelines are given for optimizing the design of PBN springs for crystal growth applications.

Evaluating the effects of pentoxifylline administration on experimental pressure sores in rats by biomechanical examinations

PubMed Central

Velaei, Kobra; Torkman, Giti; Rezaie, Fatemealsadat; Amini, Abdollah; Noruzian, Mohsen; Tavassol, Azaedh; Bayat, Mehernoush

2012-01-01

This study used a biomechanical test to evaluate the effects of pentoxifylline administration on the wound healing process of an experimental pressure sore induced in rats. Under general anesthesia and sterile conditions, experimental pressure sores generated by no. 25 Halsted mosquito forceps were inflicted on 12 adult male rats. Pentoxifylline was injected intraperitoneally at a dose of 50 mg/kg daily from the day the pressure sore was generated, for a period of 20 days. At the end of 20 days, rats were sacrificed and skin samples extracted. Samples were biomechanically examined by a material testing instrument for maximum stress (N mm2), work up to maximum force (N), and elastic stiffness (N/mm). In the experimental group, maximum stress (2.05±0.15) and work up to maximum force (N/mm) (63.75±4.97) were significantly higher than the control group (1.3±0.27 and 43.3±14.96, P=0.002 and P=0.035, respectively). Pentoxifylline administration significantly accelerated the wound healing process in experimental rats with pressure sores, compared to that of the control group. PMID:23091522

Evaluating the effects of pentoxifylline administration on experimental pressure sores in rats by biomechanical examinations.

PubMed

Velaei, Kobra; Bayat, Mohammad; Torkman, Giti; Rezaie, Fatemealsadat; Amini, Abdollah; Noruzian, Mohsen; Tavassol, Azaedh; Bayat, Mehernoush

2012-09-01

This study used a biomechanical test to evaluate the effects of pentoxifylline administration on the wound healing process of an experimental pressure sore induced in rats. Under general anesthesia and sterile conditions, experimental pressure sores generated by no. 25 Halsted mosquito forceps were inflicted on 12 adult male rats. Pentoxifylline was injected intraperitoneally at a dose of 50 mg/kg daily from the day the pressure sore was generated, for a period of 20 days. At the end of 20 days, rats were sacrificed and skin samples extracted. Samples were biomechanically examined by a material testing instrument for maximum stress (N mm(2)), work up to maximum force (N), and elastic stiffness (N/mm). In the experimental group, maximum stress (2.05±0.15) and work up to maximum force (N/mm) (63.75±4.97) were significantly higher than the control group (1.3±0.27 and 43.3±14.96, P=0.002 and P=0.035, respectively). Pentoxifylline administration significantly accelerated the wound healing process in experimental rats with pressure sores, compared to that of the control group.

Biomechanical effect of the configuration of screw hole style on locking plate fixation in proximal humerus fracture with a simulated gap: A finite element analysis.

PubMed

Zhang, Ya-Kui; Wei, Hung-Wen; Lin, Kang-Ping; Chen, Wen-Chuan; Tsai, Cheng-Lun; Lin, Kun-Jhih

2016-06-01

Locking plate fixation for proximal humeral fractures is a commonly used device. Recently, plate breakages were continuously reported that the implants all have a mixture of holes allowing placement of both locking and non-locking screws (so-called combi plates). In commercialized proximal humeral plates, there still are two screw hole styles included "locking and dynamic holes separated" and "locking hole only" configurations. It is important to understand the biomechanical effect of different screw hole style on the stress distribution in bone plate. Finite element method was employed to conduct a computational investigation. Three proximal humeral plate models with different screw hole configurations were reconstructed depended upon an identical commercialized implant. A three-dimensional model of a humerus was created using process of thresholding based on the grayscale values of the CT scanning of an intact humerus. A "virtual" subcapital osteotomy was performed. Simulations were performed under an increasing axial load. The von Mises stresses around the screw holes of the plate shaft, the construct stiffness and the directional displacement within the fracture gap were calculated for comparison. The mean value of the peak von Mises stresses around the screw holes in the plate shaft was the highest for combi hole design while it was smallest for the locking and dynamic holes separated design. The stiffness of the plate-bone construct was 15% higher in the locking screw only design (132.6N/mm) compared with the combi design (115.0N/mm), and it was 4% higher than the combi design for the locking and dynamic holes separated design (119.5N/mm). The displacement within the fracture gap was greatest in the combi hole design, whereas it was smallest for the locking hole only design. The computed results provide a possible explanation for the breakages of combi plates revealed in clinical reports. The locking and dynamic holes separated design may be a better

A Biomechanical Comparison Of Pin Configurations Used For Percutaneous Pinning Of Distal Tibia Fractures In Children.

PubMed

Brantley, Justin; Majumdar, Aditi; Jobe, J Taylor; Kallur, Antony; Salas, Christina

2016-01-01

Percutaneous pin fixation is often used in conjunction with closed-reduction and cast immobilization to treat pediatric distal tibia fractures. The goal of this procedure is to maintain reduction and provide improved stabilization, in effort to facilitate a more anatomic union. We conducted a biomechanical study of the torsional and bending stability of three commonly used pin configurations in distal tibia fracture fixation. A transverse fracture was simulated at the metaphyseal/diaphyseal junction in 15 synthetic tibias. Each fracture was reduced and fixed with two Kirschner wires, arranged in one of three pin configurations: parallel, retrograde, medial to lateral pins entering at the medial malleolus distal to the fracture (group A); parallel, antegrade, medial to lateral pins entering at the medial diaphysis proximal to the fracture (group B); or a cross-pin configuration with one retrograde, medial to lateral pin entering the medial malleolus distal to the fracture and the second an antegrade, medial to lateral pin entering at the medial diaphysis proximal to the fracture (group C). Stability of each construct was assessed by resistance to torsion and bending. Resistance to external rotation stress was significantly higher in group A than group B (P = 0.044). Resistance to internal rotation stress was significantly higher in group C than group B (P = 0.003). There was no significant difference in torsional stiffness when comparing group A with group C. Under a medial-directed load, group B and C specimens were significantly stiffer than those in group A (28 N/mm and 24 N/mm vs. 14 N/mm for A; P = 0.001 and P = 0.009, respectively). None of the three pin configurations produced superior results with respect to all variables studied. Group A configuration provided the highest resistance to external rotation forces, which is the most clinically relevant variable under short-cast immobilization. Parallel, retrograde, medial to lateral pins entering at the medial

A preliminary biomechanical study of a novel carbon-fibre hip implant versus standard metallic hip implants.

PubMed

Bougherara, Habiba; Zdero, Rad; Dubov, Anton; Shah, Suraj; Khurshid, Shaheen; Schemitsch, Emil H

2011-01-01

Total hip arthroplasty is a widespread surgical approach for treating severe osteoarthritis of the human hip. Aseptic loosening of standard metallic hip implants due to stress shielding and bone loss has motivated the development of new materials for hip prostheses. Numerically, a three-dimensional finite element (FE) model that mimicked hip implants was used to compare a new hip stem to two commercially available implants. The hip implants simulated were a novel CF/PA12 carbon-fibre polyamide-based composite hip stem, the Exeter hip stem (Stryker, Mahwah, NJ, USA), and the Omnifit Eon (Stryker, Mahwah, NJ, USA). A virtual axial load of 3 kN was applied to the FE model. Strain and stress distributions were computed. Experimentally, the three hip stems had their distal portions rigidly mounted and had strain gauges placed along the surface at 3 medial and 3 lateral locations. Axial loads of 3 kN were applied. Measurements of axial stiffness and strain were taken and compared to FE analysis. The overall linear correlation between FE model versus experimental strains showed reasonable results for the lines-of-best-fit for the Composite (Pearson R(2)=0.69, slope=0.82), Exeter (Pearson R(2)=0.78, slope=0.59), and Omnifit (Pearson R(2)=0.66, slope=0.45), with some divergence for the most distal strain locations. From FE analysis, the von Mises stress range for the Composite stem was much lower than that in the Omnifit and Exeter implants by 200% and 45%, respectively. The preliminary experiments showed that the Composite stem stiffness (1982 N/mm) was lower than the metallic hip stem stiffnesses (Exeter, 2460 N/mm; Omnifit, 2543 N/mm). This is the first assessment of stress, strain, and stiffness of the CF/PA12 carbon-fibre hip stem compared to standard commercially-available devices. Copyright © 2010 IPEM. Published by Elsevier Ltd. All rights reserved.

Does footprint preparation influence tendon-to-bone healing after rotator cuff repair in an animal model?

PubMed

Ficklscherer, Andreas; Loitsch, Thomas; Serr, Michaela; Gülecyüz, Mehmet F; Niethammer, Thomas R; Müller, Hans-Helge; Milz, Stefan; Pietschmann, Matthias F; Müller, Peter E

2014-02-01

The aim of this study was to investigate the influence of footprint spongialization and radiofrequency ablation on rotator cuff repair outcomes compared with an untreated group in a rat model. We randomly assigned 189 Sprague-Dawley rats to either a spongialization, radiofrequency ablation, or untreated group. After separation of the supraspinatus tendon from the greater tubercle, the footprint was prepared by removing the cortical bone with a burr (spongialization), was prepared by ablating soft tissue with a radiofrequency ablation device, or was left unaltered (untreated). Biomechanical testing (after 7 weeks, n = 165) and histologic analysis after 1 and 7 weeks (n = 24) followed reinsertion. The mean load to failure was 17.51 ± 4.46 N/mm(2) in the spongialization group, 15.56 ± 4.85 N/mm(2) in the radiofrequency ablation group, and 19.21 ± 5.19 N/mm(2) in the untreated group. A significant difference was found between the spongialization and radiofrequency ablation groups (P = .0409), as well as between the untreated and radiofrequency ablation groups (P = .0014). There was no significant difference between the spongialization and untreated groups (P = .2456). The mean area of fibrocartilage transition, characterized by the presence of type II collagen, was larger after 1 and 7 weeks in the spongialization group (0.57 ± 0.1 mm(2) and 0.58 ± 0.1 mm(2), respectively) and untreated group (0.51 ± 0.1 mm(2) and 0.51 ± 0.2 mm(2), respectively) than in the radiofrequency ablation group (0.11 ± 0.1 mm(2) and 0.4 ± 0.1 mm(2), respectively) with P < .05 and P < .01. The results of this study show that radiofrequency ablation of the footprint results in a poor biomechanical and histologic outcome in an animal model. No preparation of the footprint has the same effect as spongialization. Different techniques of footprint preparation in rotator cuff repair may influence tendon-to-bone healing. Copyright © 2014 Arthroscopy Association of North America. Published by

A comparative assessment of torque generated by lingual and conventional brackets.

PubMed

Sifakakis, Iosif; Pandis, Nikolaos; Makou, Margarita; Eliades, Theodore; Katsaros, Christos; Bourauel, Christoph

2013-06-01

The aim of this study was to assess the effect of bracket type on the labiopalatal moments generated by lingual and conventional brackets. Incognito™ lingual brackets (3M Unitek), STb™ lingual brackets (Light Lingual System; ORMCO), In-Ovation L lingual brackets (DENTSPLY GAC), and conventional 0.018 inch slot brackets (Gemini; 3M Unitek) were bonded on identical maxillary acrylic resin models with levelled and aligned teeth. Each model was mounted on the orthodontic measurement and simulation system and 10 0.0175 × 0.0175 TMA wires were used for each bracket type. The wire was ligated with elastomerics into the Incognito, STb, and conventional brackets and each measurement was repeated once after religation. A 15 degrees buccal root torque (+15 degrees) and then a 15 degrees palatal root torque (-15 degrees) were gradually applied to the right central incisor bracket. After each activation, the bracket returned to its initial position and the moments in the sagittal plane were recorded during these rotations of the bracket. One-way analysis of variance with post hoc multiple comparisons (Tukey test at 0.05 error rate) was conducted to assess the effect on bracket type on the generated moments. The magnitude of maximum moment at +15 degrees ranged 8.8, 8.2, 7.1, and 5.8 Nmm for the Incognito, STb, conventional Gemini, and the In-Ovation L brackets, respectively; similar values were recorded at -15 degrees: 8.6, 8.1, 7.0, and 5.7 Nmm, respectively. The recorded differences of maximum moments were statistically significant, except between the Incognito and STb brackets. Additionally, the torque angles were evaluated at which the crown torque fell well below the minimum levels of 5.0 Nmm, as well as the moment/torque ratio at the last part of the activation/deactivation curve, between 10 and 15 degrees. The lowest torque expression was observed at the self-ligating lingual brackets, followed by the conventional brackets. The Incognito and STb lingual brackets

The Damper Spring Unit of the Sentinel 1 Solar Array

NASA Technical Reports Server (NTRS)

Doejaaren, Frans; Ellenbroek, Marcel

2012-01-01

The Damper Spring Unit (DSU, see Figure 1) has been designed to provide the damping required to control the deployment speed of the spring driven solar array deployment in an ARA Mk3 or FRED based Solar Array in situations where the standard application of a damper at the root-hinge is not feasible. The unit consists of four major parts: a main bracket, an eddy current damper, a spring unit, an actuation pulley which is coupled via Kevlar cables to a synchro-pulley of a hinge. The damper slows down the deployment speed and prevents deployment shocks at deployment completion. The spring unit includes 4 springs which overcome the resistances of the damper and the specific DSU control cable loop. This means it can be added to any spring driven deployment system without major modifications of that system. Engineering models of the Sentinel 1 solar array wing have been built to identify the deployment behavior, and to help to determine the optimal pulley ratios of the solar array and to finalize the DSU design. During the functional tests, the behavior proved to be very sensitive for the alignment of the DSU. This was therefore monitored carefully during the qualification program, especially prior to the TV cold testing. During TV "Cold" testing the measured retarding torque exceeded the max. required value: 284 N-mm versus the required 247 N-mm. Although this requirement was not met, the torque balance analysis shows that the 284 N-mm can be accepted, because the spring unit can provide 1.5 times more torque than required. Some functional tests of the DSU have been performed without the eddy current damper attached. It provided input data for the ADAMS solar array wing model. Simulation of the Sentinel-1 deployment (including DSU) in ADAMS allowed the actual wing deployment tests to be limited in both complexity and number of tests. The DSU for the Sentinel-1 solar array was successfully qualified and the flight models are in production.

Force delivery of NiTi orthodontic arch wire at different magnitude of deflections and temperatures: A finite element study.

PubMed

Razali, M F; Mahmud, A S; Mokhtar, N

2018-01-01

NiTi arch wires are used widely in orthodontic treatment due to its superelastic and biocompatibility properties. In brackets configuration, the force released from the arch wire is influenced by the sliding resistances developed on the arch wire-bracket contact. This study investigated the evolution of the forces released by a rectangular NiTi arch wire towards possible intraoral temperature and deflection changes. A three dimensional finite element model was developed to measure the force-deflection behavior of superelastic arch wire. Finite element analysis was used to distinguish the martensite fraction and phase state of arch wire microstructure in relation to the magnitude of wire deflection. The predicted tensile and bending results from the numerical model showed a good agreement with the experimental results. As contact developed between the wire and bracket, binding influenced the force-deflection curve by changing the martensitic transformation plateau into a slope. The arch wire recovered from greater magnitude of deflection released lower force than one recovered from smaller deflection. In contrast, it was observed that the plateau slope increased from 0.66N/mm to 1.1N/mm when the temperature was increased from 26°C to 46°C. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of an ADP analog on isometric force and ATPase activity of active muscle fibers.

PubMed

Karatzaferi, Christina; Myburgh, Kathryn H; Chinn, Marc K; Franks-Skiba, Kathleen; Cooke, Roger

2003-04-01

The role played by ADP in modulating cross-bridge function has been difficult to study, because it is hard to buffer ADP concentration in skinned muscle preparations. To solve this, we used an analog of ADP, spin-labeled ADP (SL-ADP). SL-ADP binds tightly to myosin but is a very poor substrate for creatine kinase or pyruvate kinase. Thus ATP can be regenerated, allowing well-defined concentrations of both ATP and SL-ADP. We measured isometric ATPase rate and isometric tension as a function of both [SL-ADP], 0.1-2 mM, and [ATP], 0.05-0.5 mM, in skinned rabbit psoas muscle, simulating fresh or fatigued states. Saturating levels of SL-ADP increased isometric tension (by P'), the absolute value of P' being nearly constant, approximately 0.04 N/mm(2), in variable ATP levels, pH 7. Tension decreased (50-60%) at pH 6, but upon addition of SL-ADP, P' was still approximately 0.04 N/mm(2). The ATPase was inhibited competitively by SL-ADP with an inhibition constant, K(i), of approximately 240 and 280 microM at pH 7 and 6, respectively. Isometric force and ATPase activity could both be fit by a simple model of cross-bridge kinetics.

Mechanical Properties Studies of Components Formulation for Mixing Process Contain of Polypropylene, Polyethylene, and Aluminium Powder

NASA Astrophysics Data System (ADS)

Hamsi, A.; Dinzi, R.

2017-03-01

Certain powder and others components can induce toxic reactions if not properly handled in the mixing stage. During handling, the small particles can become airborne and be trapped in the lungs, another concern is inhomogeneities in the mixing process. Uniform quantities of the particles of the components are needed in all portions of the mixture. This paper reports the results of mechanical properties studies of mixing three components formulation for mixing process. Contain of Polyethylene (PE), Polyprophylene (PP) and Aluminium Powder. Powder mixer, Autodesk mold flow and computer based on excell method was carried out to study the influence of each formulation component on the flow %, PE 20% and Aluminium powder 2%. Macroscopic optic and macro photo was carried out to identify the homogenity of mixing, tensile test for identify the strength of component after mixing. Finally the optimal tensile test with composition PP 785,PE 20% and Aluminium powder 2% at speed 52 rpm, temperature 1500C, the tensile strength 20,92 N/mm2. At temperature 1600C, speed 100 rpm the optimum tensile strength 17,91 N/mm2. The result of simulation autodesk mold flow adviser the filling time 6 seconds. Otherwise on manual hot hidraulic press the time of filling 10 seconds.

Development and calibration of a compact self-sensing atomic force microscope head for micro-nano characterization

NASA Astrophysics Data System (ADS)

Guo, Tong; Wang, Siming; Zhao, Jian; Chen, Jinping; Fu, Xing; Hu, Xiaotang

2011-12-01

A compact self-sensing atomic force microscope (AFM) head is developed for the micro-nano dimensional measurement. This AFM head works in tapping mode equipped with a commercial self-sensing probe. This kind of probe can benefit not only from the tuning fork's stable resonant frequency and high quality factor but also from the silicon cantilever's reasonable spring constant. The head is convenient to operate by its simplicity of structure, since it does not need any optical detector to measure the bending of the cantilever. The compact structure makes the head ease to combine with other measuring methods. According to the probe"s characteristics, a method is proposed to quickly calculate the cantilever"s resonance amplitude through measuring its electro-mechanical coupling factor. An experiment system is established based on the nano-measuring machine (NMM) as a high precision positioning stage. Using this system, the approach/retract test is carried out for calibrating the head. The tests can be traced to the meter definition by interferometers in NMM. Experimental results show that the non-linearity error of this AFM head is smaller than 1%, the sensitivity reaches 0.47nm/mV and the measurement stroke is several hundreds of nanometers.

A novel dental implant abutment with micro-motion capability--development and biomechanical evaluations.

PubMed

Chen, Yen-Yin; Chen, Weng-Pin; Chang, Hao-Hueng; Huang, Shih-Hao; Lin, Chun-Pin

2014-02-01

The aim of this study was to develop a novel dental implant abutment with a micro-motion mechanism that imitates the biomechanical behavior of the periodontal ligament, with the goal of increasing the long-term survival rate of dental implants. Computer-aided design software was used to design a novel dental implant abutment with an internal resilient component with a micro-motion capability. The feasibility of the novel system was investigated via finite element analysis. Then, a prototype of the novel dental implant abutment was fabricated, and the mechanical behavior was evaluated. The results of the mechanical tests and finite element analysis confirmed that the novel dental implant abutment possessed the anticipated micro-motion capability. Furthermore, the nonlinear force-displacement behavior apparent in this micro-motion mechanism imitated the movement of a human tooth. The slope of the force-displacement curve of the novel abutment was approximately 38.5 N/mm before the 0.02-mm displacement and approximately 430 N/mm after the 0.03-mm displacement. The novel dental implant abutment with a micro-motion mechanism actually imitated the biomechanical behavior of a natural tooth and provided resilient function, sealing, a non-separation mechanism, and ease-of-use. Copyright © 2013 Academy of Dental Materials. All rights reserved.

Periodontal ligament hydrostatic pressure with areas of root resorption after application of a continuous torque moment.

PubMed

Hohmann, Ansgar; Wolfram, Uwe; Geiger, Martin; Boryor, Andrew; Sander, Christian; Faltin, Rolf; Faltin, Kurt; Sander, Franz Guenter

2007-07-01

To evaluate the risk of root resorption, individual finite element models (FEMs) of extracted human maxillary first premolars were created, and the distribution of the hydrostatic pressure in the periodontal ligament (PDL) of these models was simulated. A continuous lingual torque of 3 Nmm and 6 Nmm respectively was applied in vivo to the aforementioned teeth. After extraction, FEMs of these double-rooted teeth were created based on high-resolution microcomputed tomographics (micro CT, voxel size: 35 microns). This high volumetric resolution made the recognition of very small resorption lacunae possible. Scanning electron micrographs of the root surfaces were created as well. This enabled the investigation of advantages and disadvantages of the different imaging techniques from the viewpoint of the examination of root resorption. Using the FEMs, the same loading conditions as applied in vivo were simulated. The results of clinical examination and simulations were compared using the identical roots of the teeth. The regions that showed increased hydrostatic pressure (>0.0047 MPa) correlated well with the locations of root resorption for each tooth. Increased torque resulted in increased high-pressure areas and increased magnitudes of hydrostatic pressure, correlating with the experiments. If hydrostatic pressure exceeds typical human capillary blood pressure in the PDL, the risk of root resorption increases.

Palm Oil Fuel Ash (POFA) and Eggshell Powder (ESP) as Partial Replacement for Cement in Concrete

NASA Astrophysics Data System (ADS)

Ezdiani Mohamad, Mazizah; Mahmood, Ali A.; Min, Alicia Yik Yee; Nur Nadhira A., R.

2018-03-01

This study is an attempt to partially replace Ordinary Portland cement (OPC) in concrete with palm oil fuel ash (POFA) and eggshell powder (ESP). The mix proportions of POFA and ESP were varied at 10% of cement replacement and compared with OPC concrete as control specimen. The fineness of POFA is characterized by passing through 300 μm sieve and ESP by passing through 75 μm sieve. Compressive strength testing was conducted on concrete specimens to determine the optimum mix proportion of POFA and ESP. Generally the compressive strength of OPC concrete is higher compared to POFA-ESP concrete. Based on the results of POFA-ESP concrete overall, it shows that the optimum mix proportion of concrete is 6%POFA:4% ESP achieved compressive strength of 38.60 N/mm2 at 28 days. The compressive strength of OPC concrete for the same period was 42.37 N/mm2. Higher water demand in concrete is needed due to low fineness of POFA that contributing to low compressive strength of POFA-ESP concrete. However, the compressive strength and workability of the POFA-ESP concrete were within the ranges typically encountered in regular concrete mixtures indicating the viability of this replacement procedure for structural and non-structural applications.

The FALL3D Ash Cloud Dispersion Model and its Implementation at the Buenos Aires VAAC

NASA Astrophysics Data System (ADS)

Folch, A.; Suaya, M.; Costa, A.; Viramonte, J.

2009-12-01

Airborne volcanic ash and aerosols threat aerial navigation and affect the quality of air at medium to large distances downwind from the volcano. Airplane re-routing and airport disruption carry important socioeconomic consequences at regional and national levels. Models to forecast volcanic ash clouds constitute, together with satellite imagery, a valuable predictive tool during a crisis. FALL3D is an Eulerian ash cloud dispersion model based on the advection-diffusion-sedimentation equation. The model runs at any scale, from regional to global. The dispersion model is off-line coupled with global (e.g. GFS, NMM-b) and mesoscalar (e.g. NMM-b, WRF, ETA) meteorological models and with re-analysis datasets. FALL3D has been recently installed at the Buenos Aires VAAC, depending on the Argentinean National Meteorological Service (SMN). In this presentation we summarize the characteristics of the model and its implementation at the VAAC, including the different domains, the meteorological forecast inputs (ETA or GFS) and the scenarios assumed for some critical volcanoes (Chaitén, Llaima, Lascar, etc.). Pre-defined scenarios are necessary to give an early first order prediction when data is poor or unavailable. This is particularly critical in Central Andes, were most active volcanoes are located in remote areas with poor or inexistent monitoring.

Thermodynamic and Thermophysical Properties of Combustion Products (Selected Pages)

DTIC Science & Technology

1980-11-26

z01- -- m -" - 0000 -101 12 - o 0, - evp- -F - mt ::: -LA - 10 10 44 1 0 4 . 10 -20 20~ FUEL - OXYGEN + AMMONIA (02 + NH3 ) 103 Boi -0,6--%0 Po-.,2...BeAit H. B., MeA- para ALoKJajtos. Liepioronoulca, AH CCCI’, UeAes S. A., ryca porn A. B., Ha3.a. Mit-sO xNmm npom-CTN CCCI’, 1971, 325 peaaco H. M

On continuous and discontinuous approaches for modeling groundwater flow in heterogeneous media using the Numerical Manifold Method: Model development and comparison

NASA Astrophysics Data System (ADS)

Hu, Mengsu; Wang, Yuan; Rutqvist, Jonny

2015-06-01

One major challenge in modeling groundwater flow within heterogeneous geological media is that of modeling arbitrarily oriented or intersected boundaries and inner material interfaces. The Numerical Manifold Method (NMM) has recently emerged as a promising method for such modeling, in its ability to handle boundaries, its flexibility in constructing physical cover functions (continuous or with gradient jump), its meshing efficiency with a fixed mathematical mesh (covers), its convenience for enhancing approximation precision, and its integration precision, achieved by simplex integration. In this paper, we report on developing and comparing two new approaches for boundary constraints using the NMM, namely a continuous approach with jump functions and a discontinuous approach with Lagrange multipliers. In the discontinuous Lagrange multiplier method (LMM), the material interfaces are regarded as discontinuities which divide mathematical covers into different physical covers. We define and derive stringent forms of Lagrange multipliers to link the divided physical covers, thus satisfying the continuity requirement of the refraction law. In the continuous Jump Function Method (JFM), the material interfaces are regarded as inner interfaces contained within physical covers. We briefly define jump terms to represent the discontinuity of the head gradient across an interface to satisfy the refraction law. We then make a theoretical comparison between the two approaches in terms of global degrees of freedom, treatment of multiple material interfaces, treatment of small area, treatment of moving interfaces, the feasibility of coupling with mechanical analysis and applicability to other numerical methods. The newly derived boundary-constraint approaches are coded into a NMM model for groundwater flow analysis, and tested for precision and efficiency on different simulation examples. We first test the LMM for a Dirichlet boundary and then test both LMM and JFM for an

Beta-tricalcium phosphate plugs for press-fit fixation in ACL reconstruction--a mechanical analysis in bovine bone.

PubMed

Mayr, Hermann O; Hube, Robert; Bernstein, Anke; Seibt, Alexander B; Hein, Werner; von Eisenhart-Rothe, Ruediger

2007-06-01

The goal of this study was to test fixation properties of microporous pure beta-tricalcium phosphate (TCP) plugs (porosity 40%) for press-fit fixation of the ACL graft using patellar tendons with and without bone blocks. We set out to establish whether it is possible, in this way, to obtain results comparable with those of interference screw fixation of bone-tendon-bone (BTB) grafts in terms of cyclic loading and load-to-failure. In a bovine model 30 ACL grafts were fixed in tibial drill holes, divided into three groups: 10 BTB grafts fixed with TCP press-fit plugs (7x25 mm), 10 pure patellar tendon grafts with TCP press-fit plugs (7x25 mm), and 10 BTB grafts with metal interference screws (7x25 mm). All grafts were tested by cyclic loading (50-200 N) and loaded until failure in a tensiometer. Under cyclic loading one interference screw fixation failed. None of the TCP plug fixations failed. After 1500 cycles the displacement of the graft in the drill hole for BTB fixed with screws was 3.6+/-7.8 mm, for BTB/TCP plugs 1.6+/-3.4 mm, and for the pure tendon/TCP grafts 1.4+/-0.4 mm. Regarding cyclic loading the pure tendon/TCP system was significantly superior to BTB (p=0.007). The load-to-failure for the BTB/interference screw group was 908+/-539 N with a stiffness of 94+/-36 N/mm, 936+/-245 N for the BTB/TCP cylinder group with a stiffness of 98+/-12 N/mm, and 673+/-159 N for the pure tendon/TCP group with a stiffness of 117+/-9 N/mm. In terms of pull-out load the BTB/TCP system was significantly better than the pure tendon/TCP group (p=0.011). However, pure tendon/TCP grafts achieved significantly greater stiffness (p=0.002) than the BTB system. Press-fit fixation with microporous pure beta-TCP plugs of BTB grafts or patellar tendon grafts without bone blocks for ACL reconstruction leads to primary stability comparable with that achieved by fixation with metal interference screws in case of BTB grafts.

Strength of suture anchor versus transosseous tunnel in anatomic reconstruction of the ankle lateral ligaments: a biomechanical study.

PubMed

Li, Hong-Yun; Hua, Ying-Hui; Wu, Zi-Ying; Chen, Bo; Chen, Shi-Yi

2013-11-01

The purpose of this study was to compare the biomechanical characteristics of fixation with 2-suture anchors versus transosseous tunnel fixation in anatomic reconstruction of the ankle lateral ligaments. Six matched pairs of human cadaveric ankles underwent anatomic lateral ankle reconstruction, and fixation of the graft on the talus was achieved with 2 suture anchors or a transosseous tunnel. Ankles for the transosseous tunnel group were chosen at random, with the paired contralateral ankles used for the 2-suture anchor group. Half of the peroneus brevis tendon was harvested as a graft. For each technique, one end of the tendon was secured to the original insertion point of the anterior talofibular ligament (ATFL) at the talus, whereas the other end was armed with 2 No. 5 nonabsorbable sutures (Ethicon, Somerville, NJ) and passed through the bone tunnel in the fibula. Biomechanical testing was performed by applying the force in line with the graft. Load to failure was determined at a displacement rate of 50 mm/min. The load-displacement curve, maximum load at failure (N), and stiffness (N/mm) were recorded and compared between the 2 techniques. There was no difference between constructs in the 2-suture anchor group and the transosseous tunnel group in terms of the ultimate load and stiffness (161.8 ± 47.6 N v 171.9 ± 76.0 N; P = .92; 4.59 ± 1.85 N/mm v 5.77 ± 1.98 N/mm; P = .35). Most constructs failed because of anchor pullout in the 2-suture anchor group (5 of 6) and fracture of the bony bridge in the transosseous tunnel group (6 of 6). The strength of fixation with suture anchors in anatomic reconstruction of the ankle lateral ligaments was equivalent to transosseous tunnel fixation as determined with biomechanical testing. However, this study did not prove that one is advantageous over the other. Both techniques showed excellent biomechanical results. Therefore, the 2-suture anchor fixation approach can be safely used in anatomic reconstruction of the

Unilateral Outer Bow Expanded Cervical Headgear Force System: 3D Analysis Using Finite Element Method.

PubMed

Geramy, Allahyar; Mortezai, Omid; Esmaily, Masomeh; Darvishpour, Hojat

2015-04-01

Headgears are among the effective orthodontic appliances to achieve treatment goals. Unilateral molar distal movement is sometimes needed during an orthodontic treatment, which can be achieved by an asymmetric headgear. Different unilateral headgears have been introduced. The main goal of this study was to analyze the force system of unilateral expanded outer bow asymmetric headgears by the finite element method (FEM). Six 3D finite element models of a mesiodistal slice of the maxilla containing upper first molars, their periodontal ligaments (PDLs), cancellous bone, cortical bone, and a cervical headgear with expanded outer bow attached to maxillary first molars were designed in SolidWorks 2010 and meshed in ANSYS Workbench ver. 12.1. The models were the same except for the degree of outer bow expansion. The outer bow ends were loaded with 2 N force. The distal driving force and the net moment were evaluated. A decrease in the distalizing force in the normal side molar from 1.69 N to 1.37 N was shown by increasing the degree of unilateral expansion. At the same time, the force increased from 2.19 N to 2.49 N in the expanded side molar. A net moment increasing from 2.26 N.mm to 4.64 N.mm was also shown. Unilateral outer bow expansion can produce different distalizing forces in molars, which increase by increasing the expansion.

A study on polypropylene encapsulation and solidification of textile sludge.

PubMed

Kumari, V Krishna; Kanmani, S

2011-10-01

The textile sludge is an inevitable solid waste from the textile wastewater process and is categorised under toxic substances by statutory authorities. In this study, an attempt has been made to encapsulate and solidify heavy metals and dyes present in textile sludge using polypropylene and Portland cement. Sludge samples (2 Nos.) were characterized for pH (8.5, 9.5), moisture content (1.5%, 1.96%) and chlorides (245mg/L, 425.4mg/L). Sludge samples were encapsulated into polypropylene with calcium carbonate (additive) and solidified with cement at four different proportions (20, 30, 40, 50%) of sludge. Encapsulated and solidified cubes were made and then tested for compressive strength. Maximum compressive strength of cubes (size, 7.06cm) containing sludge (50%) for encapsulation (16.72 N/mm2) and solidification (18.84 N/mm2) was more than that of standard M15 mortar cubes. The leachability of copper, nickel and chromium has been effectively reduced from 0.58 mg/L, 0.53 mg/L and 0.07 mg/L to 0.28mg/L, 0.26mg/L and BDL respectively in encapsulated products and to 0.24mg/L, BDL and BDL respectively in solidified products. This study has shown that the solidification process is slightly more effective than encapsulation process. Both the products were recommended for use in the construction of non-load bearing walls.

Evaluation of a nontoxic rigid polymer as connecting bar in external skeletal fixators.

PubMed

Störk, Christoph K; Canivet, Philippe; Baidak, Alexandre A; Balligand, Marc H

2003-01-01

To investigate the mechanical characteristics of a nontoxic, low-cost, rigid polymer (RP) and to compare the structural and mechanical properties of a full-frame external skeletal fixator (ESF) with either RP connecting bars, polymethylmethacrylate (PMMA) connecting bars, or stainless-steel (SS) clamps and connecting bars. In vitro mechanical evaluation. Mechanical properties were assessed using an in vitro bone fracture model with a bilateral uniplanar ESF (type II). Identical ESF were built with connecting bars using RP (n = 8), PMMA (n = 8), and SS connecting bars and clamps (System Meynard; n = 3). Nondestructive mechanical tests were performed in uniaxial compression (AC) and craniocaudal (CC) 4-point bending, as well as fatigue AC. Composite stiffness for each specimen and for each loading mode was calculated from 6 replicate measures using the slope of the load displacement curve at small displacements. RP, PMMA, and SS ESF constructs yielded mean +/- SD composite stiffness values of 227 +/- 15, 381 +/- 30, and 394 +/- 9 N/mm in AC and of 35 +/- 2, 24 +/- 2, and 15 +/- 0 N/mm in CC, respectively. Structural and mechanical properties of RP are satisfactorily rigid and fatigue resistant for its use as a connecting bar in ESF. RP connecting bars in an ESF are a reliable, versatile, nontoxic and inexpensive option for the veterinary surgeon. Copyright 2003 by The American College of Veterinary Surgeons

Reuse of wastewater sludge with marine clay as a new resource of construction aggregates.

PubMed

Tay, J H; Show, K Y; Lee, D J; Hong, S Y

2004-01-01

The disposal of sludge from wastewater treatment presents highly complex problems to any municipality. Most of the sludge disposal methods have varying degrees of environmental impact. Hence, it is necessary to explore potential areas of reuse in order to alleviate sludge disposal problems and to conserve natural resources. Industrial sludge and marine clay are two forms of high-volume wastes. Using these wastes as a resource of raw materials to produce construction aggregates would enable large-scale sludge reuse. The aggregates were produced at various sludge-clay combinations containing 0, 20, 50, 80 and 100% clay contents, respectively. The pelletized aggregates displayed lower particle densities ranged between 1.48 and 2.25 g/cm3, compared to the density of granite at 2.56 g/cm3. Good 28-day concrete compressive strength of 38.5 N/mm2 achieved by the 100% sludge aggregate was comparable to the value of 38.0 N/mm2 achieved of the granite control specimens. The leachate contamination levels from the aggregates after 150 days were found acceptable when used in concrete, indicating insignificant environmental contamination. The heat flow study showed increases in heat flow at the temperatures of 480 degrees C and between 660 degrees C and 900 degrees C, indicating a need for the extension of heating time around these temperatures.

Biomechanical adaptations of mice cortical bone submitted to three different exercise modalities

PubMed Central

Frajacomo, Fernando Tadeu Trevisan; Falcai, Maurício José; Fernandes, Cleverson Rodrigues; Shimano, Antonio Carlos; Garcia, Sérgio Britto

2013-01-01

Objective To compare the adaptive effects of three non-weight bearing exercise on bone mechanical properties. Methods 24 male Balb/c mice (22-25g), were randomly divided into four groups (n=6): sedentary group (S); swimming group (N) which performed sessions five times per week for 60 min progressively; resistance group (R), which performed climbing exercise with progressive load, three times per week; and combined group (C), which performed the same protocols aforementioned being three times a week according to N protocol and two times a week the R protocol during eight weeks. Biomechanical tests, load until failure and stiffness evaluation of shinbone was performed after animals have been sacrificed. Results Stiffness values were statistically higher only in the isolated modalities groups (N and R, 41.68 ± 10.43 and 41.21 ± 11.38 N/mm, respectively) compared with the S group (28.48 ± 7.34 N/mm). However, taking into consideration the final body mass, relative values, there was no difference in the biomechanical tests among the groups. Conclusion Data from the present investigation demonstrated a favorable influence of muscle contraction in lower impact isolated exercise modalities on absolute stiffness values, i.e.groups N and R, whereas the combined group (C) did not present any statistical significant difference compared to sedentary group. Level of Evidence II, Prospective Comparative Study. PMID:24453691

Achilles Tendon Properties of Minimalist and Traditionally Shod Runners.

PubMed

Histen, Katherine; Arntsen, Julia; L'Hereux, Lauren; Heeren, James; Wicki, Benjamin; Saint, Sterling; Aerni, Giselle; Denegar, Craig R; Joseph, Michael F

2017-04-01

Tendon adapts to load through alterations in its composition and mechanical properties. Mechanical adaptation to increased load often involves increases in cross-sectional area (CSA), stiffness, and modulus. Runners exhibit these adaptations. To determine if runners wearing minimalist shoes had larger and stiffer Achilles tendons (AT) than traditionally shod runners. Cross-sectional study of well-trained, traditionally and minimally shod runners. Laboratory assessment of trained runners. 23 men (11 traditional, 12 minimalist) and 8 women (6 traditional, 2 minimalist). Runners wearing minimalist shoes had 4.2 ± 1.6 y of training experience in minimalist shoes. The authors used diagnostic ultrasound and isokinetic dynamometry to generate a force-elongation curve and its derivatives. Minimalist runners had a greater CSA: mean difference (MD) = 9.2 mm 2 , stiffness (MD = 268.1 N/mm), and modulus (MD = 202.9 MPa). ATs of minimalist runners experienced greater stress (MD 8.6 N/mm 2 ) during maximal voluntary isometric contraction of the plantar-flexor muscles due to greater force of contraction (MD 798.9 N). The AT in minimalist runners adapts by increasing size, stiffness, and modulus, which is consistent with our understanding of mechanical adaptation of tendon to increased loading. Increased stress to the AT likely requires a slow transition to minimalist running to allow the AT to adapt without evidence of injury.

Creating Strategic Visions

DTIC Science & Technology

1990-10-15

3010 o, AuTOVON 242-3010. - =n~m~m i ma ll lil~ m mm m i mii FOREWORD This futures study presents an analysis and discussion of a program used at the U.S...Operations Research Society, and The Planning Forum . iv CREATING STRATEGIC VISIONS 1 Introduction. The United States Army War College (USAWC) prepares its...consideration and time must be given to a program that attempts to help these potential leaders learn how to create strategic visions. In this paper

Inventory of File sref_nmm.t03z.pgrb221.p1.f00.grib2

Science.gov Websites

ground VGRD analysis V-Component of Wind [m/s] 015 surface WEASD analysis Water Equivalent of Accumulated day acc f Convective Precipitation [kg/m^2] 018 surface WEASD 0-0 day acc f Water Equivalent of Potential Temperature [K] 403 surface NCPCP 0-0 day acc f Large-Scale Precipitation (non-convective) [kg/m^2

Inventory of File sref_nmm.t03z.pgrb212.p1.f06.grib2

Science.gov Websites

surface WEASD 6 hour fcst Water Equivalent of Accumulated Snow Depth [kg/m^2] 016 surface APCP 3-6 hour surface WEASD 3-6 hour acc Water Equivalent of Accumulated Snow Depth [kg/m^2] 019 surface CSNOW 6 hour (non-convective) [kg/m^2] 417 surface SNOM 3-6 hour acc Snow Melt [kg/m^2] 418 surface LHTFL 0-6 hour

Inventory of File sref_nmm.t03z.pgrb221.p1.f06.grib2

Science.gov Websites

surface WEASD 6 hour fcst Water Equivalent of Accumulated Snow Depth [kg/m^2] 016 surface APCP 3-6 hour surface WEASD 3-6 hour acc Water Equivalent of Accumulated Snow Depth [kg/m^2] 019 surface CSNOW 6 hour surface NCPCP 3-6 hour acc Large-Scale Precipitation (non-convective) [kg/m^2] 404 surface SNOM 3-6 hour

Inventory of File sref_nmm.t03z.pgrb212.p1.f00.grib2

Science.gov Websites

Relative Humidity [%] 014.1 10 m above ground UGRD analysis U-Component of Wind [m/s] 014.2 10 m above ground VGRD analysis V-Component of Wind [m/s] 015 surface WEASD analysis Water Equivalent of Accumulated Relative Humidity [%] 033.1 30-0 mb above ground UGRD analysis U-Component of Wind [m/s] 033.2 30-0 mb

Inventory of File sref_nmm.t03z.pgrb132.p1.f00.grib2

Science.gov Websites

TSOIL analysis Soil Temperature Validation to deprecate [K] 403 0-0.1 m below ground SOILW analysis Volumetric Soil Moisture Content [Fraction] 404 0.1-0.4 m below ground TSOIL analysis Soil Temperature Validation to deprecate [K] 405 0.1-0.4 m below ground SOILW analysis Volumetric Soil Moisture Content

Inventory of File sref_nmm.t03z.pgrb132.p1.f06.grib2

Science.gov Websites

6 hour fcst Soil Temperature Validation to deprecate [K] 403 0-0.1 m below ground SOILW 6 hour fcst Volumetric Soil Moisture Content [Fraction] 404 0.1-0.4 m below ground TSOIL 6 hour fcst Soil Temperature Validation to deprecate [K] 405 0.1-0.4 m below ground SOILW 6 hour fcst Volumetric Soil Moisture Content

A Biomechanical Comparison of 3 Different Arthroscopic Lateral Ankle Stabilization Techniques in 36 Cadaveric Ankles.

PubMed

Cottom, James M; Baker, Joseph S; Richardson, Phillip E; Maker, Jared M

Arthroscopic lateral ankle stabilization has become an increasingly popular option among foot and ankle surgeons to address lateral ankle instability, because it combines a modified Broström-Gould procedure with the ability to address any intra-articular pathologic findings at the same session. The present study evaluated 3 different constructs in a cadaveric model. Thirty-six fresh frozen cadaver limbs were used, and the anterior talofibular ligament was identified and sectioned. The specimens were then placed into 1 of 3 groups. Group 1 received a repair with a single-row, 2-suture anchor construct; group 2 received repair with a novel, double-row, 4-anchor knotless construct; and group 3 received repair with a double-row, 3-anchor construct. Specimens were then tested for stiffness and load to ultimate failure using a customized jig. Stiffness was measured in each of the groups and was 12.10 ± 5.43 (range 5.50 to 22.24) N/mm for group 1, 13.40 ± 7.98 (range 6.71 to 36.28) N/mm for group 2, and 12.55 ± 4.00 (range 6.48 to 22.14) N/mm for group 3. No significant differences were found among the 3 groups in terms of stiffness (p = .939, 1-way analysis of variance, ɑ = 0.05). The groups were tested to failure, with observed force measurements of 156.43 ± 30.39 (range 83.69 to 192.00) N for group 1, 206.62 ± 55.62 (range 141.37 to 300.29) N for group 2, and 246.82 ± 82.37 (range 164.26 to 384.93) N for group 3. Statistically significant differences were noted between groups 1 and 3 (p = .006, 1-way analysis of variance, ɑ = 0.05). The results of the present study have shown that a previously reported arthroscopic lateral ankle stabilization procedure, when modified with an additional proximal suture anchor into the fibula, results in a statistically significant increase in strength in terms of the maximum load to failure. Additionally, we have described a previously unreported, knotless technique for arthroscopic lateral ankle

Stiffness map of the grasping contact areas of the human hand.

PubMed

Pérez-González, Antonio; Vergara, Margarita; Sancho-Bru, Joaquin L

2013-10-18

The elasticity and damping of the soft tissues of the hand contribute to dexterity while grasping and also help to stabilise the objects in manipulation tasks. Although some previous works have studied the force-displacement response of the fingertips, the responses in all other regions of the hand that usually participate in grasping have not been analysed to date. In this work we performed experimental measurements in 20 subjects to obtain a stiffness map of the different grasping contact areas of the human hand. A force-displacement apparatus was used to simultaneously measure force and displacement at 39 different points on the hand at six levels of force ranging from 1N to 6N. A non-linear force-displacement response was found for all points, with stiffness increasing with the amount of force applied. Mean stiffness for the different points and force levels was within the range from 0.2N/mm to 7.7N/mm. However, the stiffness range and variation with level of force were found to be different from point to point. A total of 13 regions with similar stiffness behaviours were identified. The stiffness in the fingertips increased linearly with the amount of force applied, while in the palm it remained more constant for the range of forces considered. It is hypothesised that the differences in the stiffness behaviour from one region to another allow these regions to play different roles during grasping. © 2013 Elsevier Ltd. All rights reserved.

Enamel microstructure and microstrain in the fracture of human and pig molar cusps.

PubMed

Popowics, T E; Rensberger, J M; Herring, S W

2004-08-01

The role of microstructure in enamel strain and breakage was investigated in human molar cusps and those of the pig, Sus scrofa. Rosette strain gauges were affixed to cusp surfaces (buccal human M3, n=15, and lingual pig M1, n=13), and a compressive load was applied to individual cusps using an MTS materials testing machine. Load and strain data were recorded simultaneously until cusp fracture, and these data were used to estimate enamel stresses, principal strains, and stiffness. Fractured and polished enamel fragments were examined in multiple planes using scanning electron microscopy (SEM). Human cusp enamel showed greater stiffness than pig enamel (P=0.02), and tensile stress at yield was higher (17.9 N/mm2 in humans versus 8.9 N/mm2 in pigs, P=0.06). SEM revealed enamel rod decussation in both human and pig enamel; however, only pig enamel showed a decussation plane between rod and inter-rod crystallites. Human inter-rod enamel was densely packed between rods, whereas in pig enamel, inter-rod enamel formed partitions between rows of enamel rods. Overall, human enamel structure enabled molar cusps to withstand horizontal tensile stress during both elastic and plastic phases of compressive loading. In contrast, pig cusp enamel was less resistant to horizontal tensile stresses, but appeared to fortify the enamel against crack propagation in multiple directions. These structural and biomechanical differences in cusp enamel are likely to reflect species-level differences in occlusal function.

Unilateral Outer Bow Expanded Cervical Headgear Force System: 3D Analysis Using Finite Element Method

PubMed Central

Mortezai, Omid; Esmaily, Masomeh; Darvishpour, Hojat

2015-01-01

Objectives: Headgears are among the effective orthodontic appliances to achieve treatment goals. Unilateral molar distal movement is sometimes needed during an orthodontic treatment, which can be achieved by an asymmetric headgear. Different unilateral headgears have been introduced. The main goal of this study was to analyze the force system of unilateral expanded outer bow asymmetric headgears by the finite element method (FEM). Materials and Methods: Six 3D finite element models of a mesiodistal slice of the maxilla containing upper first molars, their periodontal ligaments (PDLs), cancellous bone, cortical bone, and a cervical headgear with expanded outer bow attached to maxillary first molars were designed in SolidWorks 2010 and meshed in ANSYS Workbench ver. 12.1. The models were the same except for the degree of outer bow expansion. The outer bow ends were loaded with 2 N force. The distal driving force and the net moment were evaluated. Results: A decrease in the distalizing force in the normal side molar from 1.69 N to 1.37 N was shown by increasing the degree of unilateral expansion. At the same time, the force increased from 2.19 N to 2.49 N in the expanded side molar. A net moment increasing from 2.26 N.mm to 4.64 N.mm was also shown. Conclusion: Unilateral outer bow expansion can produce different distalizing forces in molars, which increase by increasing the expansion. PMID:26622282

Numerical Simulation of Callus Healing for Optimization of Fracture Fixation Stiffness

PubMed Central

Steiner, Malte; Claes, Lutz; Ignatius, Anita; Simon, Ulrich; Wehner, Tim

2014-01-01

The stiffness of fracture fixation devices together with musculoskeletal loading defines the mechanical environment within a long bone fracture, and can be quantified by the interfragmentary movement. In vivo results suggested that this can have acceleratory or inhibitory influences, depending on direction and magnitude of motion, indicating that some complications in fracture treatment could be avoided by optimizing the fixation stiffness. However, general statements are difficult to make due to the limited number of experimental findings. The aim of this study was therefore to numerically investigate healing outcomes under various combinations of shear and axial fixation stiffness, and to detect the optimal configuration. A calibrated and established numerical model was used to predict fracture healing for numerous combinations of axial and shear fixation stiffness under physiological, superimposed, axial compressive and translational shear loading in sheep. Characteristic maps of healing outcome versus fixation stiffness (axial and shear) were created. The results suggest that delayed healing of 3 mm transversal fracture gaps will occur for highly flexible or very rigid axial fixation, which was corroborated by in vivo findings. The optimal fixation stiffness for ovine long bone fractures was predicted to be 1000–2500 N/mm in the axial and >300 N/mm in the shear direction. In summary, an optimized, moderate axial stiffness together with certain shear stiffness enhances fracture healing processes. The negative influence of one improper stiffness can be compensated by adjustment of the stiffness in the other direction. PMID:24991809

Comparison of two-transsacral-screw fixation versus triangular osteosynthesis for transforaminal sacral fractures.

PubMed

Min, Kyong S; Zamorano, David P; Wahba, George M; Garcia, Ivan; Bhatia, Nitin; Lee, Thay Q

2014-09-01

Transforaminal pelvic fractures are high-energy injuries that are translationally and rotationally unstable. This study compared the biomechanical stability of triangular osteosynthesis vs 2-transsacral-screw fixation in the repair of a transforaminal pelvic fracture model. A transforaminal fracture model was created in 10 cadaveric lumbopelvic specimens. Five of the specimens were stabilized with triangular osteosynthesis, which consisted of unilateral L5-to-ilium lumbopelvic fixation and ipsilateral iliosacral screw fixation. The remaining 5 were stabilized with a 2-transsacral-screw fixation technique that consisted of 2 transsacral screws inserted across S1. All specimens were loaded cyclically and then loaded to failure. Translation and rotation were measured using the MicroScribe 3D digitizing system (Revware Inc, Raleigh, North Carolina). The 2-transsacral-screw group showed significantly greater stiffness than the triangular osteosynthesis group (2-transsacral-screw group, 248.7 N/mm [standard deviation, 73.9]; triangular osteosynthesis group, 125.0 N/mm [standard deviation, 66.9]; P=.02); however, ultimate load and rotational stiffness were not statistically significant. Compared with triangular osteosynthesis fixation, the use of 2 transsacral screws provides a comparable biomechanical stability profile in both translation and rotation. This newly revised 2-transsacral-screw construct offers the traumatologist an alternative method of repair for vertical shear fractures that provides biplanar stability. It also offers the advantage of percutaneous placement in either the prone or supine position. Copyright 2014, SLACK Incorporated.

Numerical simulation of callus healing for optimization of fracture fixation stiffness.

PubMed

Steiner, Malte; Claes, Lutz; Ignatius, Anita; Simon, Ulrich; Wehner, Tim

2014-01-01

The stiffness of fracture fixation devices together with musculoskeletal loading defines the mechanical environment within a long bone fracture, and can be quantified by the interfragmentary movement. In vivo results suggested that this can have acceleratory or inhibitory influences, depending on direction and magnitude of motion, indicating that some complications in fracture treatment could be avoided by optimizing the fixation stiffness. However, general statements are difficult to make due to the limited number of experimental findings. The aim of this study was therefore to numerically investigate healing outcomes under various combinations of shear and axial fixation stiffness, and to detect the optimal configuration. A calibrated and established numerical model was used to predict fracture healing for numerous combinations of axial and shear fixation stiffness under physiological, superimposed, axial compressive and translational shear loading in sheep. Characteristic maps of healing outcome versus fixation stiffness (axial and shear) were created. The results suggest that delayed healing of 3 mm transversal fracture gaps will occur for highly flexible or very rigid axial fixation, which was corroborated by in vivo findings. The optimal fixation stiffness for ovine long bone fractures was predicted to be 1000-2500 N/mm in the axial and >300 N/mm in the shear direction. In summary, an optimized, moderate axial stiffness together with certain shear stiffness enhances fracture healing processes. The negative influence of one improper stiffness can be compensated by adjustment of the stiffness in the other direction.

Investigation on Mechanical and Fatigue behaviour of Aluminium Based SiC/ZrO2 Particle Reinforced MMC

NASA Astrophysics Data System (ADS)

Ramesh, S.; Govindaraju, N.; Suryanarayan, C. P.

2018-04-01

The study is the work on Aluminium Metal Matrix Composites (MMC’s), which have wider applications in automobile, aerospace and defense industries, hi-tech engineering and power transmission due to their lightweight, high strength and other unique properties. The Aluminium Matrix Composites (AMC’s) refer to a kind of light weight high performance Aluminium centric material system. AMC’s consist of a non-metallic reinforcement which when included into aluminium matrix offers an advantage over the base material. Reinforcements like SiC, B4C, Al2O3, TiC, TiB2, TiO2 are normally preferred to improve mechanical properties of such composites. Here Aluminium 6061 is preferred as matrix material, while silicon carbide (SiC) and Zirconium di-oxide (ZrO2) is selected as reinforcement compounds. Conventional Stir casting procedure is employed to fabricate the necessary composites compositions, which are I. Al:SiC::100:5 and II. Al:ZrO2:SiC::100:3:2. Experimental results depict that the composition II provides higher hardness of 53.6 RHN as opposed to 45.8 RHN of composition I. In tensile strength composition II demonstrates 96.43 N/mm2 as opposed to 67.229 N/mm2 tensile strength of composition II. The fatigue test indicate a expected number of life cycles to failure of 105 cycles for composition II and over 104 cycles for composition I, at stress ranges of 79.062 MPa and 150.651 MPa respectively.

Ultrasensitive detection of uranyl by graphene oxide-based background reduction and RCDzyme-based enzyme strand recycling signal amplification.

PubMed

Li, Ming-Hui; Wang, Yong-Sheng; Cao, Jin-Xiu; Chen, Si-Han; Tang, Xian; Wang, Xiao-Feng; Zhu, Yu-Feng; Huang, Yan-Qin

2015-10-15

We proposed a novel strategy which combines graphene oxide-based background reduction with RCDzyme-based enzyme strand recycling amplification for ultrahigh sensitive detection of uranyl. The RCDzyme is designed to contain a guanine (G)-rich sequence that replaces the partial sequence in an uranyl-specific DNAzyme. This multifunctional probe can act as the target recognition element, DNAzyme and the primer of signal amplification. The presence of UO2(2+) can induce the cleavage of the substrate strands in RCDzyme. Then, each released enzyme strand can hybridize with another substrate strands to trigger many cycles of the cleavage by binding uranyl, leading to the formation of more G-quadruplexes by split guanine-rich oligonucleotide fragments. The resulting G-quadruplexes could bind to N-methyl-mesoporphyrin IX (NMM), causing an amplified detection signal for the target uranyl. Next, graphene oxide-based background reduction strategy was further employed for adsorbing free ssDNA and NMM, thereby providing a proximalis zero-background signal. The combination of RCDzyme signal amplification and proximalis zero-background signal remarkably improves the sensitivity of this method, achieving a dynamic range of two orders of magnitude and giving a detection limit down to 86 pM, which is much lower than those of related literature reports. These achievements might be helpful in the design of highly sensitive analytical platform for wide applications in environmental and biomedical fields. Copyright © 2015 Elsevier B.V. All rights reserved.

Dimensionally stable and bioactive membrane for guided bone regeneration: An in vitro study

PubMed Central

Rowe, Matthew J.; Kamocki, Krzysztof; Pankajakshan, Divya; Li, Ding; Bruzzaniti, Angela; Thomas, Vinoy; Blanchard, Steve B.; Bottino, Marco C.

2015-01-01

Composite fibrous electrospun membranes based on poly(DL-lactide) (PLA) and poly(ε-caprolactone) (PCL) were engineered to include borate bioactive glass (BBG) for the potential purposes of guided bone regeneration (GBR). The fibers were characterized using scanning and transmission electron microscopies, which respectively confirmed the submicron fibrous arrangement of the membranes and the successful incorporation of BBG particles. Selected mechanical properties of the membranes were evaluated using the suture pullout test. The addition of BBG at 10 wt.% led to similar stiffness, but more importantly, it led to a significantly stronger (2.37±0.51 N*mm) membrane when compared to the commercially available Epiguide® (1.06±0.24 N*mm) under hydrated conditions. Stability (shrinkage) was determined after incubation in a phosphate buffer solution from 24 h up to 9 days. The dimensional stability of the PLA:PCL-based membranes with or without BBG incorporation (10.07-16.08%) was similar to that of Epiguide® (14.28%). Cell proliferation assays demonstrated a higher rate of pre-osteoblasts proliferation on BBG-containing membranes (6.4-fold) over BBG-free membranes (4-5.8-fold) and EpiGuide® (4.5-fold), following 7 days of in vitro culture. Collectively, our results demonstrated the ability to synthesize, via electrospinning, stable, polymer-based submicron fibrous BBG-containing membranes capable of sustaining osteoblastic attachment and proliferation—a promising attribute in guided bone regeneration. PMID:25953329

A Dynamic Programming Approach to the Daily Routing of Aeromedical Evacuation System Missions

DTIC Science & Technology

1989-06-08

1 AEX 1 HSV 1 ADW 4 NKT 2 BYH 1 NKX 1 MXF 3 *CAE 1 ROA 1 SZL 1 *SBD 1 BLV 4 BOS 1 CMI 2 AGS 1 WRI 1 SAW 2 BHM 1 NHZ 1 BTL 1 YNG 1 RST 1 ...LAX 1 BLV 4 BKF 4 HSV 3 NIP 3 PVD 4 *CHD 1 NQA 2 BLV 3 SWF 1 ABQ 2 GUS I DHN 1 RME 2 NKX 2 OSC 2 *MEI 1 EWR 3 SAW 2 CBM 1 WRI 2 BYH I *NMM 1 PBG 1

Rotator Cuff Repair with a Tendon-Fibrocartilage-Bone Composite Bridging Patch

PubMed Central

Ji, Xiaoxi; Chen, Qingshan; Thoreson, Andrew R.; Qu, Jin; An, Kai-Nan; Amadio, Peter C.; Steinmann, Scott P.; Zhao, Chunfeng

2015-01-01

Background To compare the mechanical performance of a rotator cuff repaired with a novel tendon-fibrocartilage-bone composite bridging patch vs the traditional Mason-Allen repair in an in vitro canine model. Methods Twenty shoulders and 10 bridging patches from patellar tendon were harvested. The patches were trimmed and sliced into 2 layers. An infraspinatus tendon tear was created in each shoulder. Modified Mason-Allen sutures were used to repair the infraspinatus tendon to the greater tuberosity, with or without the bridging patch (bridging patch group and controls, respectively). Shoulders were loaded to failure under displacement control at a rate of 0.5mm/sec. Findings The ultimate tensile load was significantly higher in the bridging patch group than control (mean [SD], 365.46 [36.45] vs 272.79 [48.88] N; P<.001). Stiffness at the greater tuberosity repair site and the patch-infraspinatus tendon repair site was significantly higher than the control repair site (93.96 [27.72] vs 42.62 [17.48] N/mm P<.001; 65.94 [24.51] vs 42.62 [17.48] N/mm P=.02, respectively). Interpretation The tendon-fibrocartilage-bone composite bridging patch achieved higher ultimate tensile load and stiffness at the patch–greater tuberosity repair site compared with traditional repair in a canine model. This composite tissue transforms the traditional tendon-to-bone healing interface (with dissimilar tissues) into a pair of bone-to-bone and tendon-to-tendon interfaces, which may improve healing quality and reduce retear rate. PMID:26190097

Rotator cuff repair with a tendon-fibrocartilage-bone composite bridging patch.

PubMed

Ji, Xiaoxi; Chen, Qingshan; Thoreson, Andrew R; Qu, Jin; An, Kai-Nan; Amadio, Peter C; Steinmann, Scott P; Zhao, Chunfeng

2015-11-01

To compare the mechanical performance of a rotator cuff repaired with a novel tendon-fibrocartilage-bone composite bridging patch vs the traditional Mason-Allen repair in an in vitro canine model. Twenty shoulders and 10 bridging patches from patellar tendon were harvested. The patches were trimmed and sliced into 2 layers. An infraspinatus tendon tear was created in each shoulder. Modified Mason-Allen sutures were used to repair the infraspinatus tendon to the greater tuberosity, with or without the bridging patch (bridging patch group and controls, respectively). Shoulders were loaded to failure under displacement control at a rate of 0.5mm/s. The ultimate tensile load was significantly higher in the bridging patch group than control (mean [SD], 365.46 [36.45] vs 272.79 [48.88] N; P<.001). Stiffness at the greater tuberosity repair site and the patch-infraspinatus tendon repair site was significantly higher than the control repair site (93.96 [27.72] vs 42.62 [17.48] N/mm P<.001; 65.94 [24.51] vs 42.62 [17.48] N/mm P=.02, respectively). The tendon-fibrocartilage-bone composite bridging patch achieved higher ultimate tensile load and stiffness at the patch-greater tuberosity repair site compared with traditional repair in a canine model. This composite tissue transforms the traditional tendon-to-bone healing interface (with dissimilar tissues) into a pair of bone-to-bone and tendon-to-tendon interfaces, which may improve healing quality and reduce retear rate. Copyright © 2015 Elsevier Ltd. All rights reserved.

Extended healing validation of an artificial tendon to connect the quadriceps muscle to the Tibia: 180-day study.

PubMed

Melvin, Alan J; Litsky, Alan S; Mayerson, Joel L; Stringer, Keith; Juncosa-Melvin, Natalia

2012-07-01

Whenever a tendon or its bone insertion is disrupted or removed, existing surgical techniques provide a temporary connection or scaffolding to promote healing, but the interface of living to non-living materials soon breaks down under the stress of these applications, if it must bear the load more than acutely. Patients are thus disabled whose prostheses, defect size, or mere anatomy limit the availability or outcomes of such treatments. Our group developed the OrthoCoupler™ device to join skeletal muscle to prosthetic or natural structures without this interface breakdown. In this study, the goat knee extensor mechanism (quadriceps tendon, patella, and patellar tendon) was removed from the right hind limb in 16 goats. The device connected the quadriceps muscle to a stainless steel bone plate on the tibia. Mechanical testing and histology specimens were collected from each operated leg and contralateral unoperated control legs at 180 days. Maximum forces in the operated leg (vs. unoperated) were 1,400 ± 93 N (vs. 1,179 ± 61 N), linear stiffnesses were 33 ± 3 N/mm (vs. 37 ± 4 N/mm), and elongations at failure were 92.1 ± 5.3 mm (vs. 68.4 ± 3.8 mm; mean ± SEM). Higher maximum forces (p = 0.02) and elongations at failure (p=0.008) of legs with the device versus unoperated controls were significant; linear stiffnesses were not (p=0.3). We believe this technology will yield improved procedures for clinical challenges in orthopedic oncology, revision arthroplasty, tendon transfer, and tendon injury reconstruction. Copyright © 2011 Orthopaedic Research Society.

Separate vertical wiring for the fixation of comminuted fractures of the inferior pole of the patella.

PubMed

Song, Hyung Keun; Yoo, Je Hyun; Byun, Young Soo; Yang, Kyu Hyun

2014-05-01

Among patients over 50 years of age, separate vertical wiring alone may be insufficient for fixation of fractures of the inferior pole of the patella. Therefore, mechanical and clinical studies were performed in patients over the age of 50 to test the strength of augmentation of separate vertical wiring with cerclage wire (i.e., combined technique). Multiple osteotomies were performed to create four-part fractures in the inferior poles of eight pairs of cadaveric patellae. One patella from each pair was fixed with the separate wiring technique, while the other patella was fixed with a combined technique. The ultimate load to failure and stiffness of the fixation were subsequently measured. In a clinical study of 21 patients (average age of 64 years), comminuted fractures of the inferior pole of the patellae were treated using the combined technique. Operative parameters were recorded from which post-operative outcomes were evaluated. For cadaveric patellae, whose mean age was 69 years, the mean ultimate loads to failure for the separate vertical wiring technique and the combined technique were 216.4±72.4 N and 324.9±50.6 N, respectively (p=0.012). The mean stiffness for the separate vertical wiring technique and the combined technique was 241.1±68.5 N/mm and 340.8±45.3 N/mm, respectively (p=0.012). In the clinical study, the mean clinical score at final follow-up was 28.1 points. Augmentation of separate vertical wiring with cerclage wire provides enough strength for protected early exercise of the knee joint and uneventful healing.

Effects of Platelet-Rich Plasma and Indomethacin on Biomechanics of Rotator Cuff Repair.

PubMed

Meadows, Molly C; Levy, David M; Ferry, Christopher M; Gardner, Thomas R; Teratani, Takeshi; Ahmad, Christopher S

We conducted a study to determine if platelet-rich plasma (PRP) enhances the strength of rotator cuff repair (RCR) and if concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs) affects PRP efficacy. We also wanted to determine the optimal centrifugation protocol for making PRP from rats. This study used 48 rats, 14 in a centrifugation protocol and 34 in an operative protocol. Six syngeneic rats from the operative group were used as PRP blood donors; the other 28 operative rats underwent bilateral RCRs. The Autologous Conditioned Plasma system (Arthrex) was used to prepare leukocyte-poor PRP. One shoulder was randomized to an intratendinous PRP injection, and the other received normal saline. Each rat was also randomly placed on a postoperative diet, either a regular diet or an indomethacin-enhanced diet. After rats were euthanized at 3 weeks, specimens were dissected to isolate the supraspinatus tendon at its humeral attachment, which was subjected to biomechanical testing. PRP prepared with a protocol of 5 minutes × 1300 revolutions per minute had the highest platelet index. Mean (SD) energy to failure was significantly higher (P = .03) in tendons treated with PRP, 11.7 (7.3) N-mm, than in tendons treated with saline, 8.7 (4.6) N-mm. Both groups (PRP, saline) showed no significant differences between tendons treated with NSAIDs and those not treated with NSAIDs. Intraoperative application of PRP enhances energy to failure after RCR in rats. There were no differences in biomechanical strength with NSAID use and no interactions between PRP and NSAID use.

Do bisphosphonates inhibit direct fracture healing?: A laboratory investigation using an animal model.

PubMed

Savaridas, T; Wallace, R J; Salter, D M; Simpson, A H R W

2013-09-01

Fracture repair occurs by two broad mechanisms: direct healing, and indirect healing with callus formation. The effects of bisphosphonates on fracture repair have been assessed only in models of indirect fracture healing. A rodent model of rigid compression plate fixation of a standardised tibial osteotomy was used. Ten skeletally mature Sprague-Dawley rats received daily subcutaneous injections of 1 µg/kg ibandronate (IBAN) and ten control rats received saline (control). Three weeks later a tibial osteotomy was rigidly fixed with compression plating. Six weeks later the animals were killed. Fracture repair was assessed with mechanical testing, radiographs and histology. The mean stress at failure in a four-point bending test was significantly lower in the IBAN group compared with controls (8.69 Nmm(-2) (sd 7.63) vs 24.65 Nmm(-2) (sd 6.15); p = 0.017). On contact radiographs of the extricated tibiae the mean bone density assessment at the osteotomy site was lower in the IBAN group than in controls (3.7 mmAl (sd 0.75) vs 4.6 mmAl (sd 0.57); p = 0.01). In addition, histological analysis revealed progression to fracture union in the controls but impaired fracture healing in the IBAN group, with predominantly cartilage-like and undifferentiated mesenchymal tissue (p = 0.007). Bisphosphonate treatment in a therapeutic dose, as used for risk reduction in fragility fractures, had an inhibitory effect on direct fracture healing. We propose that bisphosphonate therapy not be commenced until after the fracture has united if the fracture has been rigidly fixed and is undergoing direct osteonal healing.

Biomechanics and strain mapping in bone as related to immediately-loaded dental implants

PubMed Central

Du, Jing; Lee, Jihyun; Jang, Andrew; Gu, Allen; Hossaini-Zadeh, Mehran; Prevost, Richard; Curtis, Don; Ho, Sunita

2015-01-01

The effects of alveolar bone socket geometry and bone-implant contact on implant biomechanics, and resulting strain distributions in bone were investigated. Following extraction of lateral incisors on a cadaver mandible, immediate implants were placed and bone-implant contact area, stability and bone strain were measured. In situ biomechanical testing coupled with micro X-ray microscope (μ-XRM) illustrated less stiff bone-implant complexes (701-822 N/mm) compared with bone-periodontal ligament (PDL)-tooth complexes (791-913 N/mm). X-ray tomograms illustrated that the cause of reduced stiffness was due to reduced and limited bone-implant contact. Heterogeneous elemental composition of bone was identified by using energy dispersive X-ray spectroscopy (EDS). The novel aspect of this study was the application of a new experimental mechanics method, that is, digital volume correlation, which allowed mapping of strains in volumes of alveolar bone in contact with a loaded implant. The identified surface and subsurface strain concentrations were a manifestation of load transferred to bone through bone-implant contact based on bone-implant geometry, quality of bone, implant placement, and implant design. 3D strain mapping indicated that strain concentrations are not exclusive to the bone-implant contact regions, but also extend into bone not directly in contact with the implant. The implications of the observed strain concentrations are discussed in the context of mechanobiology. Although a plausible explanation of surgical complications for immediate implant treatment is provided, extrapolation of results is only warranted by future systematic studies on more cadaver specimens and/or in vivo small scale animal models. PMID:26162549

Effect of intraplaque angiogenesis to atherosclerotic rupture-prone plaque induced by high shear stress in rabbit model

PubMed Central

Qiu, Juhui; Lei, Daoxi; Hu, Jianjun; Yin, Tieying; Zhang, Kang; Yu, Donghong

2017-01-01

Abstract Atherosclerotic prone-rupture plaque is mainly localized in the region of the entrance to the stenosis with high shear stress and the reasons are largely unknown. Our hypothesis is that such a distribution of cells in atherosclerotic plaque may depend on the angiogenesis. Silastic collars induced regions of high shear stress (20.68 ± 5.27 dynes/cm2) in the upstream flow and low shear stress (12.25 ± 1.28 dynes/cm2) in the downstream flow in carotid arteries. Compared with the low shear stress region, plaques in the high shear stress region showed more intraplaque haemorrhaging, less collagen and higher apoptotic rates of vascular smooth muscle cells; endothelial cells (ECs) in the high shear stress region were characterized with integrity and high endothelial nitric oxide synthase (eNOS) expression (1570.3 ± 345.5% vs 172.9 ± 49.9%). The number of intraplaque microvessels is very high in the high shear stress region (15 ± 1.8 n/mm2 vs 3.5 ± 0.4 n/mm2), and the microvessels in the plaque show ECs were abnormal, with membrane blebs, intracytoplasmic vacuoles and leukocyte infiltration. Our current study reveals that the integrity of the endothelium and the vulnerability of atherosclerotic plaques are simultaneously localized in high shear stress regions, and we provide evidence for the first time that microvessels in the intraplaque maybe responsible for rupture-prone plaque formation in the high shear stress region. PMID:28798867

Redesigning the continuous vacuum sealer packaging machine to improve the processing speed

NASA Astrophysics Data System (ADS)

Belo, J. B.; Widyanto, S. A.; Jamari, J.

2017-01-01

Vacuum sealer as a product packaging tool of food products to be able to vacuum air inside the plastic which is filled with food products and it causes the pressure lower. In this condition, the optimal heating temperature is reached in a shorter time, so that damage on plastic sealer of vacuumed food products could be prevented to be more effective and efficient. The purpose of this redesigning is to design a vacuum sealer packaging machine continuously through a conveyor mechanism on the packaging quality, time of processing speed of vacuuming food product in the plastic package. This designing process is conducted through several steps of designing and constructing tools until the products are ready to operate. Data analysis is done through quality test of vacuum and sealer to the plastic thickness of 75 µm, 80 µm, and 100 µm with temperature of 170°C, 180°C, 190°C and vacuum duration of 5 seconds, 8 seconds, and 60 seconds. Results of this designing process indicate that vacuum sealer works practically and more optimally with the time of vacuum processing speed of 0 to 1 minute/s; whereas, the pressure of vacuuming suction is until 1e-5 MPa. The results of tensile strength test are at a maximum of 32,796 (N/mm2) and a minimum of 20,155 (N/mm2) and the analysis of plastic composite with EDX. This result shows that the vacuum pressure and the quality of vacuum sealer are better and more efficient.

Sintering of MSW fly ash for reuse as a concrete aggregate.

PubMed

Mangialardi, T

2001-10-12

The sintering process of municipal solid waste (MSW) fly ash was investigated in order to manufacture sintered products for reuse as concrete aggregates. Four types of fly ash resulting from different Italian MSW incineration plants were tested in this study. A modification of the chemical composition of MSW fly ash--through a preliminary four-stage washing treatment of this material with water--was attempted to improve the chemical and mechanical characteristics of sintered products.The sintering treatment of untreated or washed fly ash was performed on cylindrical compact specimens (15 mm in diameter and 20mm in height) at different compact pressures, sintering temperatures and times.The sintering process of untreated MSW fly ashes proved to be ineffective for manufacturing sintered products for reuse as a construction material, because of the adverse chemical characteristics of these fly ashes in terms of sulfate, chloride, and vitrifying oxide contents.A preliminary washing treatment of MSW fly ash with water greatly improved the chemical and mechanical characteristics of sintered products and, for all the types of fly ash tested, the sintered products satisfied the Italian requirements for normal weight aggregates for use in concretes having a specified strength not greater than 12 and 15N/mm(2), when measured on cylindrical and cubic specimens, respectively.A compact pressure of 28 N/mm(2), a sintering temperature of 1140 degrees C, and a sintering time of 60 min were the best operating conditions for manufacturing sintered products of washed MSW fly ash.

The comparative biomechanics of the reinforced interdental crossover and the Stout loop composite splints for mandibular fracture repair in dogs.

PubMed

Kitshoff, A M; de Rooster, H; Ferreira, S M; Burger, D; Steenkamp, G

2013-01-01

To describe a new technique, the reinforced interdental crossover composite splint (RIC), for transverse mandibular fracture repair in dogs. This technique was compared biomechanically with the established reinforced interdental Stout loop composite splint (RIS) technique. Six pairs of mandibles from young adult small breed dogs were used for the study. Osteotomies were created in a standardized fashion and fixed with either RIC or RIS. All composite splint constructs were tested biomechanically with a cantilever bending force, using a single column testing machine at a rate of 2 mm/min. The time of application, amount of composite used, ultimate force, stiffness, total displacement, and total energy absorbed during displacement of the rostral mandibular segment were calculated and compared between the two groups. No significant difference was found when comparing the time of application of the RIC and the RIS techniques. All implants failed by either composite resin fracture over the region of the osteotomy or by fracture between the first and second molar followed by detachment of the resin from the lingual enamel surface of the first molar. Differences between the RIC and RIS in force (80.5 N ± 40.3 and 51.8 N ± 27.4. respectively) and stiffness (16.2 N/mm ± 4.4 and 10.1 N/mm ± 4.1 respectively) were significant (p = 0.03). However differences between the two techniques in displacement and total energy absorbed were not significant. In experimentally fractured mandibles of young adult dogs there is evidence that RIC is biomechanically similar to RIS.

Ba 2TeO: A new layered oxytelluride

DOE PAGES

Besara, T.; Ramirez, D.; Sun, J.; ...

2015-02-01

For single crystals of the new semiconducting oxytelluride phase, Ba 2TeO, we synthesized from barium oxide powder and elemental tellurium in a molten barium metal flux. Ba 2TeO crystallizes in tetragonal symmetry with space group P4/nmm (#129), a=5.0337(1) Å, c=9.9437(4) Å, Z=2. The crystals were characterized by single crystal x-ray diffraction, heat capacity and optical measurements. Moreover, the optical measurements along with electronic band structure calculations indicate semiconductor behavior with a band gap of 2.93 eV. Resistivity measurements show that Ba 2TeO is highly insulating.

Adhesion of a fluorinated poly(amic acid) with stainless steel surfaces

NASA Astrophysics Data System (ADS)

Jung, Youngsuk; Song, Sunjin; Kim, Sangmo; Yang, Yooseong; Chae, Jungha; Park, Tai-Gyoo; Dong Cho, Myung

2013-01-01

The authors elucidate an origin and probable mechanism of adhesion strength change at an interface of fluorinated poly(amic acid) and stainless steel. Fluorination provides favorable delamination with release strength weaker than 0.08 N/mm from a metal surface, once the amount of residual solvent becomes less than 35 wt. %. However, the release strength critically depends on film drying temperature. Characterization on stainless steel surfaces and thermodynamic analyses on wet films reveal a drying temperature of 80 °C fosters interaction between the metal oxides at stainless steel surface and the free electron donating groups in poly(amic acid).

Charge Fluctuations in the NdO1-xFxBiS2 Superconductors

NASA Astrophysics Data System (ADS)

Athauda, Anushika; Mizuguchi, Yoshikazu; Nagao, Masanori; Neuefeind, Joerg; Louca, Despina

2017-12-01

The local atomic structure of superconducting NdO1-xFxBiS2 (x = 0.2 and 0.4) is investigated using neutron diffraction and the pair density function analysis technique. In the non-superconducting x = 0.2 composition, ferrodistortive displacements of the pyramidal sulfur ions break the tetragonal symmetry and a superlattice structure emerges with peaks appearing at h + k odd reflections superimposed on the even reflections of the P4/nmm symmetry. In the superconducting x = 0.4 composition, similar ferrodistortive displacements are observed but with different magnitudes coupled with in-plane Bi distortions which are indicative of charge fluctuations.

Screw-blade fixation systems in Pauwels three femoral neck fractures: a biomechanical evaluation.

PubMed

Knobe, Matthias; Altgassen, Simon; Maier, Klaus-Jürgen; Gradl-Dietsch, Gertraud; Kaczmarek, Chris; Nebelung, Sven; Klos, Kajetan; Kim, Bong-Sung; Gueorguiev, Boyko; Horst, Klemens; Buecking, Benjamin

2018-02-01

To reduce mechanical complications after osteosynthesis of femoral neck fractures, improved fixation techniques have been developed including blade or screw-anchor devices. This biomechanical study compares different fixation systems used for treatment of unstable femoral neck fractures with evaluation of failure mode, load to failure, stiffness, femoral head rotation, femoral neck shortening and femoral head migration. Standardized Pauwels type 3 fractures (AO/OTA 31-B2) with comminution were created in 18 biomechanical sawbones using a custom-made sawguide. Fractures were stabilized using either SHS-Screw, SHS-Blade or Rotationally Stable Screw-Anchor (RoSA). Femurs were positioned in 25 degrees adduction and ten degrees posterior flexion and were cyclically loaded with an axial sinusoidal loading pattern of 0.5 Hz, starting with 300 N, with an increase by 300 N every 2000 cycles until bone-implant failure occurred. Mean failure load for the Screw-Anchor fixation (RoSA) was 5100 N (IQR 750 N), 3900 N (IQR 75 N) for SHS-Blade and 3000 N (IQR 675 N; p = 0.002) for SHS-Screw. For SHS-Screw and SHS-Blade we observed fracture displacement with consecutive fracture collapse as the main reason for failure, whereas RoSA mainly showed a cut-out under high loadings. Mean stiffness at 1800 N was 826 (IQR 431) N/mm for SHS-Screw, 1328 (IQR 441) N/mm for SHS-Blade and 1953 (IQR 617) N/mm for RoSA (p = 0.003). With a load of 1800 N (SHS-Screw 12° vs. SHS-Blade 7° vs. RoSA 2°; p = 0.003) and with 2700 N (24° vs. 15° vs. 3°; p = 0.002) the RoSA implants demonstrated a higher rotational stability and had the lowest femoral neck shortening (p = 0.002), compared with the SHS groups. At the 2700 N load point, RoSA systems showed a lower axial (p = 0.019) and cranial (p = 0.031) femoral head migration compared to the SHS-Screw. In our study, the new Screw-Anchor fixation (RoSA) was superior to the comparable SHS implants regarding rotational

Symmetry-Breaking Transitions in RECuAs 2-xP x (RE=Sm, Gd, Ho, and Er)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mozharivskyj, Yurij

Structural changes resulting in lower symmetries can be understood in terms of electronic instabilities and Coulomb interactions. The interplay of these two interrelated factors is complicated and difficult to analyze. The RECuAs 2-xP x phases, because of the variation in the chemical content (As/P substitution), allow, with the aid of band structures, Madelung energies and Landau theory, a partial unraveling of the forces important in the symmetry-breaking transitions in RECuAs 2-xP x (RE = Sm, Gd, Ho and Er). Distortions of the P layers in SmCu 1.15P 2, GdCuP 2.20 and ErCuP 2 are usefully thought of asmore » generalized Peierls distortions, i.e., they lower the electronic (and total) energy and lead to more stable structures. On the other hand, the P4/nmm → Pmmn transitions, which are observed in all studied arsenophosphide series and occur upon substitution of P for As, originate from the B1g vibrational mode and are structural adaptations to smaller P atoms. These transitions provide tighter atomic packing and better Coulomb interactions. Configurational contribution to the entropy becomes important in stabilizing the mixed occupancy in the RECuAs 2-xP x arsenophosphides. While geometric and electronic factors favor separation of the As and P atoms over two different crystallographic sites, configurational entropy stabilizes the As/P mixing on these two sites.;Progress in the research on RECuAs 2-xP x was dependent upon the ability of Landau theory to predict, explain and dismiss structural models and transitions. The space group Pmmn (arising from the B 1g vibrational mode) in all mixed arsenophosphides and the existence of these mixed arsenophosphides followed from the analysis of GdCuAs 2 and GdCuP 2, using Landau theory. The impossibility of obtaining the high-symmetry structure (P4/nmm) and the low symmetry structure (Pnmm) at the same temperature for the displacive continuous symmetry-breaking transition P4/ nmm → Pmmn led to the conclusion, later

Does experimental low back pain change posteroanterior lumbar spinal stiffness and trunk muscle activity? A randomized crossover study.

PubMed

Wong, Arnold Y L; Parent, Eric C; Prasad, Narasimha; Huang, Christopher; Chan, K Ming; Kawchuk, Gregory N

2016-05-01

While some patients with low back pain demonstrate increased spinal stiffness that decreases as pain subsides, this observation is inconsistent. Currently, the relation between spinal stiffness and low back pain remains unclear. This study aimed to investigate the effects of experimental low back pain on temporal changes in posteroanterior spinal stiffness and concurrent trunk muscle activity. In separate sessions five days apart, nine asymptomatic participants received equal volume injections of hypertonic or isotonic saline in random order into the L3-L5 interspinous ligaments. Pain intensity, spinal stiffness (global and terminal stiffness) at the L3 level, and the surface electromyographic activity of six trunk muscles were measured before, immediately after, and 25-minute after injections. These outcome measures under different saline conditions were compared by generalized estimating equations. Compared to isotonic saline injections, hypertonic saline injections evoked significantly higher pain intensity (mean difference: 5.7/10), higher global (mean difference: 0.73N/mm) and terminal stiffness (mean difference: 0.58N/mm), and increased activity of four trunk muscles during indentation (P<0.05). Both spinal stiffness and trunk muscle activity returned to baseline levels as pain subsided. While previous clinical research reported inconsistent findings regarding the association between spinal stiffness and low back pain, our study revealed that experimental pain caused temporary increases in spinal stiffness and concurrent trunk muscle co-contraction during indentation, which helps explain the temporal relation between spinal stiffness and low back pain observed in some clinical studies. Our results substantiate the role of spinal stiffness assessments in monitoring back pain progression. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of second-order bracket-archwire misalignments on loads generated during third-order archwire rotation in orthodontic treatment.

PubMed

Romanyk, Dan L; George, Andrew; Li, Yin; Heo, Giseon; Carey, Jason P; Major, Paul W

2016-05-01

To investigate the influence of a rotational second-order bracket-archwire misalignment on the loads generated during third-order torque procedures. Specifically, torque in the second- and third-order directions was considered. An orthodontic torque simulator (OTS) was used to simulate the third-order torque between Damon Q brackets and 0.019 × 0.025-inch stainless steel archwires. Second-order misalignments were introduced in 0.5° increments from a neutral position, 0.0°, up to 3.0° of misalignment. A sample size of 30 brackets was used for each misalignment. The archwire was then rotated in the OTS from its neutral position up to 30° in 3° increments and then unloaded in the same increments. At each position, all forces and torques were recorded. Repeated-measures analysis of variance was used to determine if the second-order misalignments significantly affected torque values in the second- and third-order directions. From statistical analysis of the experimental data, it was found that the only statistically significant differences in third-order torque between a misaligned state and the neutral position occurred for 2.5° and 3.0° of misalignment, with mean differences of 2.54 Nmm and 2.33 Nmm, respectively. In addition, in pairwise comparisons of second-order torque for each misalignment increment, statistical differences were observed in all comparisons except for 0.0° vs 0.5° and 1.5° vs 2.0°. The introduction of a second-order misalignment during third-order torque simulation resulted in statistically significant differences in both second- and third-order torque response; however, the former is arguably clinically insignificant.

Separate Vertical Wiring for the Fixation of Comminuted Fractures of the Inferior Pole of the Patella

PubMed Central

Song, Hyung Keun; Yoo, Je Hyun; Byun, Young Soo

2014-01-01

Purpose Among patients over 50 years of age, separate vertical wiring alone may be insufficient for fixation of fractures of the inferior pole of the patella. Therefore, mechanical and clinical studies were performed in patients over the age of 50 to test the strength of augmentation of separate vertical wiring with cerclage wire (i.e., combined technique). Materials and Methods Multiple osteotomies were performed to create four-part fractures in the inferior poles of eight pairs of cadaveric patellae. One patella from each pair was fixed with the separate wiring technique, while the other patella was fixed with a combined technique. The ultimate load to failure and stiffness of the fixation were subsequently measured. In a clinical study of 21 patients (average age of 64 years), comminuted fractures of the inferior pole of the patellae were treated using the combined technique. Operative parameters were recorded from which post-operative outcomes were evaluated. Results For cadaveric patellae, whose mean age was 69 years, the mean ultimate loads to failure for the separate vertical wiring technique and the combined technique were 216.4±72.4 N and 324.9±50.6 N, respectively (p=0.012). The mean stiffness for the separate vertical wiring technique and the combined technique was 241.1±68.5 N/mm and 340.8±45.3 N/mm, respectively (p=0.012). In the clinical study, the mean clinical score at final follow-up was 28.1 points. Conclusion Augmentation of separate vertical wiring with cerclage wire provides enough strength for protected early exercise of the knee joint and uneventful healing. PMID:24719149

The polymethyl methacrylate cervical cage for treatment of cervical disk disease Part III. Biomechanical properties.

PubMed

Chen, Jyi-Feng; Lee, Shih-Tseng

2006-10-01

In a previous article, we used the PMMA cervical cage in the treatment of single-level cervical disk disease and the preliminary clinical results were satisfactory. However, the mechanical properties of the PMMA cage were not clear. Therefore, we designed a comparative in vitro biomechanical study to determine the mechanical properties of the PMMA cage. The PMMA cervical cage and the Solis PEEK cervical cage were compressed in a materials testing machine to determine the mechanical properties. The compressive yield strength of the PMMA cage (7030 +/- 637 N) was less than that of the Solis polymer cervical cage (8100 +/- 572 N). The ultimate compressive strength of the PMMA cage (8160 +/- 724 N) was less than that of the Solis cage (9100 +/- 634 N). The stiffness of the PMMA cervical cage (8106 +/- 817 N/mm) was greater than that of the Solis cage (6486 +/- 530 N/mm). The elastic modulus of the PMMA cage (623 +/- 57 MPa) was greater than that of the Solis cage (510 +/- 42 MPa). The elongation of PMMA cage (43.5 +/- 5.7%) was larger than that of the Solis cage (36.1 +/- 4.3%). Although the compressive yield strength and ultimate compressive strength of the PMMA cervical cage were less than those of the Solis polymer cage, the mechanical properties are better than those of the cervical vertebral body. The PMMA cage is strong and safe for use as a spacer for cervical interbody fusion. Compared with other cage materials, the PMMA cage has many advantages and no obvious failings at present. However, the PMMA cervical cage warrants further long-term clinical study.

Maternal maya ancestry and birth weight in Yucatan, Mexico.

PubMed

Azcorra, Hugo; Vázquez-Vázquez, Adriana; Mendez, Nina; Carlos Salazar, Juan; Datta-Banik, Sudip

2016-05-01

The purpose of this study was to analyze the association between maternal Maya ancestry and the birth weight of infants born in Yucatan, Mexico, during 2013. A total of 30,435 singletons born at term (≥37 weeks) in Yucatan during 2013 were analyzed. Birth weights, gestational ages, and maternal socioeconomic data were provided by the Ministry of Health of Yucatan. Maternal Maya ancestry was defined by the presence of Maya surnames in: (1) non-Maya surnames (NM-NM), (2) one Maya surname (NM-M), and (3) two Maya surnames (M-M). Biological and socioeconomic parameters were compared between the categories of ancestry through one-way analysis of variance (ANOVA) and a multiple regression model was used to analyze the association between ancestry and infants' birth weight controlling for influence of covariates. Mean birth weight was 3,114 g (SD = 406) (NM-NM: 3,150 g [SD = 404], NM-M: 3,106 g [SD = 402], M-M: 3,088 g [SD = 408]). With the biological and socioeconomic variables statistically adjusted for, the presence of one and two maternal Maya surnames was associated with decreases in birth weight of 42 g and 63 g, respectively. None of the interactions between ancestry and other predictors was statistically significant. The lower mean birth weights of Maya infants are consistent with studies reporting poor growth and nutritional status of Maya children from Yucatan. Historically adverse socioeconomic conditions experienced by the Maya population are probably linked to the relatively lower birth weights of their infants. Am. J. Hum. Biol. 28:436-439, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Development of the mechanical properties of engineered skin substitutes after grafting to full-thickness wounds.

PubMed

Sander, Edward A; Lynch, Kaari A; Boyce, Steven T

2014-05-01

Engineered skin substitutes (ESSs) have been reported to close full-thickness burn wounds but are subject to loss from mechanical shear due to their deficiencies in tensile strength and elasticity. Hypothetically, if the mechanical properties of ESS matched those of native skin, losses due to shear or fracture could be reduced. To consider modifications of the composition of ESS to improve homology with native skin, biomechanical analyses of the current composition of ESS were performed. ESSs consist of a degradable biopolymer scaffold of type I collagen and chondroitin-sulfate (CGS) that is populated sequentially with cultured human dermal fibroblasts (hF) and epidermal keratinocytes (hK). In the current study, the hydrated biopolymer scaffold (CGS), the scaffold populated with hF dermal skin substitute (DSS), or the complete ESS were evaluated mechanically for linear stiffness (N/mm), ultimate tensile load at failure (N), maximum extension at failure (mm), and energy absorbed up to the point of failure (N-mm). These biomechanical end points were also used to evaluate ESS at six weeks after grafting to full-thickness skin wounds in athymic mice and compared to murine autograft or excised murine skin. The data showed statistically significant differences (p <0.05) between ESS in vitro and after grafting for all four structural properties. Grafted ESS differed statistically from murine autograft with respect to maximum extension at failure, and from intact murine skin with respect to linear stiffness and maximum extension. These results demonstrate rapid changes in mechanical properties of ESS after grafting that are comparable to murine autograft. These values provide instruction for improvement of the biomechanical properties of ESS in vitro that may reduce clinical morbidity from graft loss.

Fast degradable citrate-based bone scaffold promotes spinal fusion.

PubMed

Tang, Jiajun; Guo, Jinshan; Li, Zhen; Yang, Cheng; Xie, Denghui; Chen, Jian; Li, Shengfa; Li, Shaolin; Kim, Gloria B; Bai, Xiaochun; Zhang, Zhongmin; Yang, Jian

2015-07-21

It is well known that high rates of fusion failure and pseudoarthrosis development (5~35%) are concomitant in spinal fusion surgery, which was ascribed to the shortage of suitable materials for bone regeneration. Citrate was recently recognized to play an indispensable role in enhancing osteconductivity and osteoinductivity, and promoting bone formation. To address the material challenges in spinal fusion surgery, we have synthesized mechanically robust and fast degrading citrate-based polymers by incorporating N-methyldiethanolamine (MDEA) into clickable poly(1, 8-octanediol citrates) (POC-click), referred to as POC-M-click. The obtained POC-M-click were fabricated into POC-M-click-HA matchstick scaffolds by compositing with hydroxyapatite (HA) for interbody spinal fusion in a rabbit model. Spinal fusion was analyzed by radiography, manual palpation, biomechanical testing, and histological evaluation. At 4 and 8 weeks post surgery, POC-M-click-HA scaffolds presented optimal degradation rates that facilitated faster new bone formation and higher spinal fusion rates (11.2±3.7, 80±4.5 at week 4 and 8, respectively) than the poly(L-lactic acid)-HA (PLLA-HA) control group (9.3±2.4 and 71.1±4.4) (p<0.05). The POC-M-click-HA scaffold-fused vertebrates possessed a maximum load and stiffness of 880.8±14.5 N and 843.2±22.4 N/mm, respectively, which were also much higher than those of the PLLA-HA group (maximum: 712.0±37.5 N, stiffness: 622.5±28.4 N/mm, p<0.05). Overall, the results suggest that POC-M-click-HA scaffolds could potentially serve as promising bone grafts for spinal fusion applications.

Torque resistance of different stainless steel wires commonly used for fixed retainers in orthodontics.

PubMed

Arnold, Dario T; Dalstra, Michel; Verna, Carlalberta

2016-06-01

Movements of teeth splinted by fixed retention wires after orthodontic treatment have been observed. The aetiological factors for these movements are unknown. The aim of this in vitro study was to compare the resistance to torque of different stainless steel wires commonly used for fixed retainers in orthodontics. Torquing moments acting on a retainer wire were measured in a mechanical force testing system by applying buccal crown torque to an upper lateral incisor in both a 3-teeth and in a 2-teeth setup. Seven stainless steel wires with different shape, type (plain, braided, coaxial, or chain) and dimensions were selected for this study. For a torquing angle of 16.2° in the 3-teeth setup torsion moments can vary between 390 cNmm and 3299 cNmm depending on the retainer wire. For the 2-teeth setup the torsion moments are much smaller. Exposure to the flame of a butane-gas torch for 10 seconds to anneal the wire reduces the stiffness of the retainer wire. Clinicians must select wires for fixed retainers very carefully since the difference in resistance to torque is large. A high level of torque control can be achieved with a plain 0.016 × 0.016-inch or a braided 0.016 × 0.022-inch stainless steel wire. A tooth attached by a retainer wire to only one neighbouring tooth is less resistant to torque than a tooth connected to two neighbouring teeth. Annealing a retainer wire with a flame reduces the stiffness of the wire markedly and can lead to a non-uniform and non-reproducible effect.

Dynamic locking screw improves fixation strength in osteoporotic bone: an in vitro study on an artificial bone model.

PubMed

Pohlemann, Tim; Gueorguiev, Boyko; Agarwal, Yash; Wahl, Dieter; Sprecher, Christoph; Schwieger, Karsten; Lenz, Mark

2015-04-01

The novel dynamic locking screw (DLS) was developed to improve bone healing with locked-plate osteosynthesis by equalising construct stiffness at both cortices. Due to a theoretical damping effect, this modulated stiffness could be beneficial for fracture fixation in osteoporotic bone. Therefore, the mechanical behaviour of the DLS at the screw-bone interface was investigated in an artificial osteoporotic bone model and compared with conventional locking screws (LHS). Osteoporotic surrogate bones were plated with either a DLS or a LHS construct consisting of two screws and cyclically axially loaded (8,500 cycles, amplitude 420 N, increase 2 mN/cycle). Construct stiffness, relative movement, axial screw migration, proximal (P) and distal (D) screw pullout force and loosening at the bone interface were determined and statistically evaluated. DLS constructs exhibited a higher screw pullout force of P 85 N [standard deviation (SD) 21] and D 93 N (SD 12) compared with LHS (P 62 N, SD 28, p = 0.1; D 57 N, SD 25, p < 0.01) and a significantly lower axial migration over cycles compared with LHS (p = 0.01). DLS constructs showed significantly lower axial construct stiffness (403 N/mm, SD 21, p < 0.01) and a significantly higher relative movement (1.1 mm, SD 0.05, p < 0.01) compared with LHS (529 N/mm, SD 27; 0.8 mm, SD 0.04). Based on the model data, the DLS principle might also improve in vivo plate fixation in osteoporotic bone, providing enhanced residual holding strength and reducing screw cutout. The influence of pin-sleeve abutment still needs to be investigated.

Reconstruction of a quadriceps tendon tear using Polyvinylidene fluoride sutures and patellar screw fixation: A biomechanical study.

PubMed

Sellei, R M; Bauer, E; Hofman, M; Kobbe, P; Lichte, P; Garrison, R L; Pape, H C; Horst, K

2015-12-01

Acute quadriceps tendon tears are infrequent injuries requiring surgical treatment. Improved stability after surgical repair may allow for earlier weight-bearing and range of motion. Therefore, a new implant was tested and compared with the "gold standard", using transosseous sutures. Quadriceps tendon tears were constructed using a cadaveric model of 12 fresh matched-pair specimens (aged 61-97; mean age: 82 years). The biomechanical testing compared non-absorbable suture anchors (Polyvinylidene fluoride) versus transosseous absorbable sutures (Polydioxanon). Following anatomic reconstruction, the repaired specimens were loaded until they failed (testing machine: Hounsfield H10KM, Redhill, United Kingdom; maximum force: 1000 N; load speed: 25 mm/min; maximum test length: 150 mm; pre-load: 5 N). Values for load until tear displacement, maximum load until complete failure of the construct (pullout or breakage of the sutures or anchors) and stiffness of the reconstruction were recorded. The stiffness found in the Polyvinylidene fluoride reconstruction (mean 9.83 N/mm) (standard deviation (SD) 7.75) showed a significant increase compared to the Polydioxanon reconstruction (mean 6.66 N/mm (SD 3.32); P=0.045). Transosseous fixation showed comparable results to the suture anchor system. There was no significant difference found in the maximum load to tear displacement (PVDF: 290.88 N (SD 106.01) vs. PDS: 266.75 N (SD 82.61); P=0.358). Using the Polyvinylidene fluoride thread showed comparable results to the established method in reconstruction of ruptured quadriceps tendon. Stiffness of the Polyvinylidene fluoride thread reconstruction was even greater than Polydioxanon thread. Improved stiffness may facilitate healing and is suggested as clinical relevance in reconstruction. Copyright © 2015 Elsevier B.V. All rights reserved.

Unit Fire Direction Center Training Program for the 81mm Mortar

DTIC Science & Technology

1985-02-01

rotor* It to IM Ui. Army ftoioardi instltuto for IM üEaotOfH ond It It «0 Motor NMM. *•••• «o not Sod «« fctonoM. WQTt, Thrt «oiMrcfi *OOMCI * m« to...Virginia 22333-5600 REPORT * PERIOD COVERCO Interim Report June 1983-June 1984 «. PERFORMING OR6. REPORT NUMBER I. CONTRACT OR GRANT NUMBCRf«) MDA ...command for the FFE? A B C D riet Mc M&- 3§± sec MTM. rat US SM tffl sm. mi Htll Iff TMt ! EZ9 E3B NOTE: EOM, mark as Tgt CD 06

2011 Einstein Fellows Chosen

NASA Astrophysics Data System (ADS)

2011-03-01

ASA has announced the selection of the 2011 Einstein Fellows who will conduct research related to NASA's Physics of the Cosmos program, which aims to expand our knowledge of the origin, evolution, and fate of the Universe. The Einstein Fellowship provides support to the awardees for three years, and the Fellows may pursue their research at a host university or research center of their choosing in the United States. The new Fellows will begin their programs in the fall of 2011. The new Einstein Fellows and their host institutions are listed below: * Akos Bogdan (Smithsonian Astrophysical Observatory, Cambridge, Mass.) * Samuel Gralla (University of Maryland, College Park, Md.) * Philip Hopkins (University of California at Berkeley) * Matthew Kunz (Princeton University, Princeton, N.J.) * Laura Lopez (Massachusetts Institute of Technology, Cambridge, Mass.) * Amy Reines (National Radio Astronomy Observatory, Charlottesville, Virg.) * Rubens Reis (University of Michigan, Ann Arbor) * Ken Shen (Lawrence Berkeley National Laboratory, Berkeley, Calif.) * Jennifer Siegal-Gaskins (California Institute of Technology, Pasadena) * Lorenzo Sironi (Harvard University, Cambridge, Mass.) NASA has two other astrophysics theme-based fellowship programs: the Sagan Fellowship Program, which supports research into exoplanet exploration, and the Hubble Fellowship Program, which supports research into cosmic origins. More information on the Einstein Fellowships can be found at: http://cxc.harvard.edu/fellows/

Label-free and enzyme-free detection of transcription factors with graphene oxide fluorescence switch-based multifunctional G-quadruplex-hairpin probe.

PubMed

Zhu, Desong; Wang, Lei; Xu, Xiaowen; Jiang, Wei

2016-01-15

Transcription factors (TFs) play pivotal roles in the regulation of a variety of essential cellular processes and some of them have been recognized as potential diagnostic markers and therapeutic targets of some diseases. Sensitive and accurate detection of TFs is of great importance to better understanding their roles in gene regulation and evaluation of disease state. Here, we developed a simple, label-free and enzyme-free new fluorescent strategy for the detection of TFs by graphene oxide (GO) fluorescence switch-based multifunctional G-quadruplex-hairpin probe (MGHP). The MGHP possessed of three functions simultaneously, adsorbing onto GO with the loop part, binding to target with the stem part and serving as signal carrier with the terminal G-quadruplex. First, the MGHP was adsorbed quickly to GO. Next, the TF bound to the stem part of MGHP to form a huge target-MGHP complex, which led to desorption of the complex from GO. Finally, NMM was inserted into G-quadruplex in the complex to yield an enhanced fluorescence response. The GO used here, as a fluorescence switch, could quickly and efficiently quench the fluorescence of NMM inserted into the MGHP absorbed on the GO, guaranteeing a high signal-to-noise ratio. Sensitive detection of purified NF-κB p50 and HeLa cell nuclear extracts were achieved with detection limits of 0.2nM and 7.8ng/µL, respectively. Moreover, this proposed strategy could be used to screen inhibitors of NF-κB p50 activity. The strategy proposed here might offer a new potential approach for reliable quantification of TFs in clinical diagnostics and treatment research of some diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Corneal Crosslinking With Rose Bengal and Green Light: Efficacy and Safety Evaluation.

PubMed

Zhu, Hong; Alt, Clemens; Webb, Robert H; Melki, Samir; Kochevar, Irene E

2016-09-01

To evaluate crosslinking of cornea in vivo using green light activation of Rose Bengal (RGX) and assess potential damaging effects of the green light on retina and iris. Corneas of Dutch belted rabbits were de-epithelialized, then stained with Rose Bengal and exposed to green light, or not further treated. Corneal stiffness was measured by uniaxial tensiometry. Re-epithelialization was assessed by fluorescein fluorescence. Keratocytes were counted on hematoxylin and eosin (H&E)-stained sections, and iris cell damage was assessed by lactate dehydrogenase staining. Thermal effects on the blood-retinal barrier (BRB) were assessed by fluorescein angiography and those on photoreceptors, retinal pigment epithelium (RPE), and choriocapillaris by light microscopy and transmission electron microscopy. RGX (10-min irradiation; 150 J/cm) increased corneal stiffness 1.9-fold on day 1 (1.25 ± 0.21 vs. 2.38 ± 0.59 N/mm; P = 0.036) and 2.8-fold compared with controls on day 28 (1.70 ± 0.74 vs. 4.95 ± 1.86 N/mm; P = 0.003). Keratocytes decreased only in the anterior stroma on day 1 (24.0 ± 3.0 vs. 3.67 ± 4.73, P = 0.003) and recovered by day 28 (37.7 ± 8.9 vs. 34.5 ± 2.4, P = 0.51). Iris cells were not thermally damaged. No evidence of BRB breakdown was detected on days 1 or 28. Retina from RGX-treated eyes seemed normal with RPE cells showing intact nuclei shielded apically by melanosomes, morphologically intact photoreceptor outer segments, normal outer nuclear layer thickness, and choriocapillaris containing intact erythrocytes. The substantial corneal stiffening produced by RGX together with the lack of significant effects on keratocytes and no evidence for retina or iris damage suggest that RGX-initiated corneal crosslinking may be a safe, rapid, and effective treatment.

Label-free and sensitive detection of T4 polynucleotide kinase activity via coupling DNA strand displacement reaction with enzymatic-aided amplification.

PubMed

Cheng, Rui; Tao, Mangjuan; Shi, Zhilu; Zhang, Xiafei; Jin, Yan; Li, Baoxin

2015-11-15

Several fluorescence signal amplification strategies have been developed for sensitive detection of T4 polynucleotide kinase (T4 PNK) activity, but they need fluorescence dye labeled DNA probe. We have addressed the limitation and report here a label-free strategy for sensitive detection of PNK activity by coupling DNA strand displacement reaction with enzymatic-aided amplification. A hairpin oligonucleotide (hpDNA) with blunt ends was used as the substrate for T4 PNK phosphorylation. In the presence of T4 PNK, the stem of hpDNA was phosphorylated and further degraded by lambda exonuclease (λ exo) from 5' to 3' direction to release a single-stranded DNA as a trigger of DNA strand displacement reaction (SDR). The trigger DNA can continuously displace DNA P2 from P1/P2 hybrid with the help of specific cleavage of nicking endonuclease (Nt.BbvCI). Then, DNA P2 can form G-quadruplex in the presence of potassium ions and quadruplex-selective fluorphore, N-methyl mesoporphyrin IX (NMM), resulting in a significant increase in fluorescence intensity of NMM. Thus, the accumulative release of DNA P2 led to fluorescence signal amplification for determining T4 PNK activity with a detection limit of 6.6×10(-4) U/mL, which is superior or comparative with established approaches. By ingeniously utilizing T4 PNK-triggered DNA SDR, T4 PNK activity can be specifically and facilely studied in homogeneous solution containing complex matrix without any external fluorescence labeling. Moreover, the influence of different inhibitors on the T4 PNK activity revealed that it also can be explored to screen T4 PNK inhibitors. Therefore, this label-free amplification strategy presents a facile and cost-effective approach for nucleic acid phosphorylation related research. Copyright © 2015 Elsevier B.V. All rights reserved.

Material properties and fractography of an indirect dental resin composite

PubMed Central

Quinn, Janet B.; Quinn, George D.

2011-01-01

Objectives Determination of material and fractographic properties of a dental indirect resin composite material. Methods A resin composite (Paradigm, 3M-ESPE, MN) was characterized by strength, static elastic modulus, Knoop hardness, fracture toughness and edge toughness. Fractographic analyses of the broken bar surfaces was accomplished with a combination of optical and SEM techniques, and included determination of the type and size of the failure origins, and fracture mirror and branching constants. Results The flexure test mean strength ± standard deviation was 145 MPA ± 17 MPa, and edge toughness, Te, was 172 N/mm ±12 N/mm. Knoop hardness was load dependent, with a plateau at 0.99 GPa ± .02 GPa. Mirrors in the bar specimens were measured with difficulty, resulting in a mirror constant of approximately 2.6 MPa·m1/2. Fracture in the bar specimens initiated at equiaxed material flaws that had different filler concentrations that sometimes were accompanied by partial microcracks. Using the measured flaw sizes, which ranged from 35 µm to 100 µm in size, and estimates of the stress intensity shape factors, fracture toughness was estimated to be 1.1 MPa·m1/2 ± 0.2 MPa·m1/2. Significance Coupling the flexure tests with fractographic examination enabled identification of the intrinsic strength limiting flaws. The same techniques could be useful in determining if clinical restorations of similar materials fail from the same causes. The existence of a strong load-dependence of the Knoop hardness of the resin composite is not generally mentioned in the literature, and is important for material comparisons and wear evaluation studies. Finally, the edge toughness test was found promising as a quantitative measure of resistance to edge chipping, an important failure mode in this class of materials. PMID:20304478

Engine-driven preparation of curved root canals: measuring cyclic fatigue and other physical parameters.

PubMed

Peters, Ove A; Kappeler, Stefan; Bucher, Willi; Barbakow, Fred

2002-04-01

An increasing number of engine-driven rotary systems are marketed to shape root canals. Although these systems may improve the quality of canal preparations, the risk for instrument fracture is also increased. Unfortunately, the stresses generated in rotary instruments when shaping curved root canals have not been adequately studied. Consequently, the aim of an ongoing project was to develop a measurement platform that could more accurately detail physical parameters generated in a simulated clinical situation. Such a platform was constructed by fitting a torque-measuring device between the rotating endodontic instrument and the motor driving it. Apically directed force and instrument insertion depth were also recorded. Additional devices were constructed to assess cyclic fatigue and static fracture loads. The current pilot study evaluated GT rotary instruments during the shaping of curved canals in plastic blocks as well as "ISO 3630-1 torque to fracture" and number of rotations required for fatigue fracture. Results indicated that torques in excess of 40 Nmm were generated by rotary GT-Files, a significantly higher figure than static fracture loads (less than 13 Nmm for the size 20. 12 GT-File). Furthermore, the number of rotations needed to shape simulated canals with a 5 mm radius of curvature in plastic blocks was 10 times lower than the number of rotations needed to fracture instruments in a "cyclic fatigue test". Apical forces were always greater than 1 N, and in some specimens, scores of 8 N or more were recorded. Further studies are required using extracted natural teeth, with their wide anatomical variation, in order to reduce the incidence of fracture of rotary instruments. In this way, the clinical potential of engine-driven rotary instruments to safely prepare curved canals can be fully appreciated.

PMMA-augmented SI screw: a biomechanical analysis of stiffness and pull-out force in a matched paired human cadaveric model.

PubMed

Grechenig, Stephan; Gänsslen, Axel; Gueorguiev, Boyko; Berner, Arne; Müller, Michael; Nerlich, Michael; Schmitz, Paul

2015-10-01

Current literature data and clinical experience show that the number of pelvic fractures continuously rises due to the increasing elderly population. In the elderly with suspected osteoporosis additional implant augmentation with bone cement seems to be an option to avoid secondary displacement. There are no reported biomechanical data in the literature comparing the fixation strength (and anchorage) of standard and augmented SI screws so far. The purpose of this study was to assess the biomechanical performance of cement-augmented versus non-augmented SI screws in a human cadaveric pelvis model. Six human cadaveric pelvises preserved with the method of Thiel were used in this study. Each pelvis was split to a pair of 2 hemi-pelvises, assigned to 2 different groups for instrumentation with one non-augmented or one contralateral cement-augmented SI screw, placed in the body of S1 in a randomized fashion. The osteosynthesis followed a standard procedure with 3D controlled percutaneous iliosacral screw positioning. A biomechanical setup for a quasistatic pullout test of each SI screw was used. Construct stiffness and maximum pullout force were calculated from the load-displacement curve of the machine data. Statistical evaluation was performed at a level of significance p = .05 for all statistical tests. Stiffness and pullout force in the augmented group (501.6 N/mm ± 123.7, 1336.8 N ± 221.1) were significantly higher than in the non-augmented one (289.7 N/mm ± 97.1, 597.7 N ± 115.5), p = .04 and p = .014, respectively. BMD influenced significantly the pullout force in all study groups. Cement augmentation significantly increased the fixation strength in iliosacral screw osteosynthesis of the sacrum in a biomechanical human cadaveric model. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanical and structural characteristics of the new BONE-LOK cortical-cancellous internal fixation device.

PubMed

Cachia, Victor V; Culbert, Brad; Warren, Chris; Oka, Richard; Mahar, Andrew

2003-01-01

The purpose of this study was to evaluate the structural and mechanical characteristics of a new and unique titanium cortical-cancellous helical compression anchor with BONE-LOK (Triage Medical, Inc., Irvine, CA) technology for compressive internal fixation of fractures and osteotomies. This device provides fixation through the use of a distal helical anchor and a proximal retentive collar that are united by an axially movable pin (U.S. and international patents issued and pending). The helical compression anchor (2.7-mm diameter) was compared with 3.0-mm diameter titanium cancellous screws (Synthes, Paoli, PA) for pullout strength and compression in 7# and 12# synthetic rigid polyurethane foam (simulated bone matrix), and for 3-point bending stiffness. The following results (mean +/- standard deviation) were obtained: foam block pullout strength in 12# foam: 2.7-mm helical compression anchor 70 +/- 2.0 N and 3.0-mm titanium cancellous screws 37 +/- 11 N; in 7# foam: 2.7-mm helical compression anchor 33 +/- 3 N and 3.0-mm titanium cancellous screws 31 +/- 12 N. Three-point bending stiffness, 2.7-mm helical compression anchor 988 +/- 68 N/mm and 3.0-mm titanium cancellous screws 845 +/- 88 N/mm. Compression strength testing in 12# foam: 2.7-mm helical compression anchor 70.8 +/- 4.8 N and 3.0-mm titanium cancellous screws 23.0 +/- 3.1 N, in 7# foam: 2.7-mm helical compression anchor 42.6 +/- 3.2 N and 3.0-mm titanium cancellous screws 10.4 +/- 0.9 N. Results showed greater pullout strength, 3-point bending stiffness, and compression strength for the 2.7-mm helical compression anchor as compared with the 3.0-mm titanium cancellous screws in these testing models. This difference represents a distinct advantage in the new device that warrants further in vivo testing.

Fast degradable citrate-based bone scaffold promotes spinal fusion

PubMed Central

Tang, Jiajun; Guo, Jinshan; Li, Zhen; Yang, Cheng; Xie, Denghui; Chen, Jian; Li, Shengfa; Li, Shaolin; Kim, Gloria B.; Bai, Xiaochun; Zhang, Zhongmin; Yang, Jian

2015-01-01

It is well known that high rates of fusion failure and pseudoarthrosis development (5~35%) are concomitant in spinal fusion surgery, which was ascribed to the shortage of suitable materials for bone regeneration. Citrate was recently recognized to play an indispensable role in enhancing osteconductivity and osteoinductivity, and promoting bone formation. To address the material challenges in spinal fusion surgery, we have synthesized mechanically robust and fast degrading citrate-based polymers by incorporating N-methyldiethanolamine (MDEA) into clickable poly(1, 8-octanediol citrates) (POC-click), referred to as POC-M-click. The obtained POC-M-click were fabricated into POC-M-click-HA matchstick scaffolds by compositing with hydroxyapatite (HA) for interbody spinal fusion in a rabbit model. Spinal fusion was analyzed by radiography, manual palpation, biomechanical testing, and histological evaluation. At 4 and 8 weeks post surgery, POC-M-click-HA scaffolds presented optimal degradation rates that facilitated faster new bone formation and higher spinal fusion rates (11.2±3.7, 80±4.5 at week 4 and 8, respectively) than the poly(L-lactic acid)-HA (PLLA-HA) control group (9.3±2.4 and 71.1±4.4) (p<0.05). The POC-M-click-HA scaffold-fused vertebrates possessed a maximum load and stiffness of 880.8±14.5 N and 843.2±22.4 N/mm, respectively, which were also much higher than those of the PLLA-HA group (maximum: 712.0±37.5 N, stiffness: 622.5±28.4 N/mm, p<0.05). Overall, the results suggest that POC-M-click-HA scaffolds could potentially serve as promising bone grafts for spinal fusion applications. PMID:26213625

Thermal debonding of ceramic brackets: an in vitro study.

PubMed

Crooks, M; Hood, J; Harkness, M

1997-02-01

Thermal debonding has been developed to overcome the problems of enamel damage and high forces when debonding ceramic orthodontic brackets. However, the temperature changes with thermal debonding have the potential to damage the tooth tissues. The principal aims of this study are, first, to investigate the effects of resin type, resin thickness, and debonding force on the temperature changes in human premolars during thermal debonding of ceramic brackets and, second, to record the sites of bond failure and damage to the tooth surface. Ceramic brackets were attached to each specimen by using one of four types of bonding resin in a controlled thick or thin resin layer. The ceramic debonding unit (Dentaurum, Pforzheim, Germany) was used to thermally debond the brackets with either a 40 or 80 Nmm torsional force. Higher temperature changes at the pulpal wall (> 10 degrees C in some 40 Nmm torsional force specimens) always occurred with Concise (3M Dental Products, St. Paul, Minn.) and Transbond (Unitek/3M Dental Products, Monrovia, Calif.) resins, and lower temperature changes (< 5 degrees C) with Quasar (Rocky Mountain Orthodontics, Denver, Colo.) and Ortho. B.S. (Dentaurum, Pforzheim, Germany) resins. In general, resin thickness was not significantly associated with buccal surface or pulpal wall temperature changes. However, temperature changes at the pulpal wall were significantly associated with the temperature changes at the buccal surface (r = 0.76), with the temperature of the thermal debonder blade for thin resin layer specimens (r = 0.50), and the time required to debond the bracket for both thick (r = 0.74) and thin (r = 0.63) resin layer specimens. In most specimens, the site of bond failure occurred at the bracket-resin interface. There was no evidence of enamel damage after bracket removal.

Ultimate force and stiffness of 2-piece zirconium dioxide implants with screw-retained monolithic lithium-disilicate reconstructions.

PubMed

Joda, Tim; Voumard, Benjamin; Zysset, Philippe K; Brägger, Urs; Ferrari, Marco

2018-04-01

The aims were to analyze stiffness, ultimate force, and failure modes of a 2-piece zirconium dioxide (ZrO 2 ) implant system. Eleven 2-piece ZrO 2 implants, each mounted with ZrO 2 abutments plus bonded monolithic lithium disilicate (LS 2 ) restorations, were grouped for 3.3mm (A) and 4.1mm (B) diameter samples. Quasi-static load was monotonically applied under a standardized test set-up (loading configuration according to DIN ISO 14801). The ultimate force was defined as the maximum force that implants are able to carry out until fracture; stiffness was measured as the maximum slope during loading. An unpaired t-test was performed between group A and B for ultimate force and stiffness (p<0.05). Force-displacement curves revealed statistically homogenous inner-group results for all samples. Failure modes showed characteristic fractures at the neck configuration of the implants independent of the diameter. Mean stiffness was 1099N/mm (±192) for group A, and significantly lower compared to group B with 1630N/mm (±274) (p<0.01); whereas mean ultimate force was 348N (±53) for group A, and significantly increased for group B with 684N (±29) (p<0.0001). The examined 2-piece ZrO 2 implant system mounted to LS 2 -restorations seems to be a stable unit under in-vitro conditions with mechanical properties compared to loading capacity of physiological force. The metal-free implant reconstructions demonstrated high stiffness and ultimate force under quasi-static load for single tooth replacement under consideration of the dental indication of narrow and standard diameter implants. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

A new method for sudden mechanical perturbation with axial load, to assess postural control in sitting and standing.

PubMed

Claus, Andrew P; Verrel, Julius; Pounds, Paul E I; Shaw, Renee C; Brady, Niamh; Chew, Min T; Dekkers, Thomas A; Hodges, Paul W

2016-05-03

Sudden application of load along a sagittal or coronal axis has been used to study trunk stiffness, but not axial (vertical) load. This study introduces a new method for sudden-release axial load perturbation. Prima facie validity was supported by comparison with standard mechanical systems. We report the response of the human body to axial perturbation in sitting and standing and within-day repeatability of measures. Load of 20% of body weight was released from light contact onto the shoulders of 22 healthy participants (10 males). Force input was measured via force transducers at shoulders, output via a force plate below the participant, and kinematics via 3-D motion capture. System identification was used to fit data from the time of load release to time of peak load-displacement, fitting with a 2nd-order mass-spring-damper system with a delay term. At peak load-displacement, the mean (SD) effective stiffness measured with this device for participants in sitting was 12.0(3.4)N/mm, and in standing was 13.3(4.2)N/mm. Peak force output exceeded input by 44.8 (10.0)% in sitting and by 30.4(7.9)% in standing. Intra-class correlation coefficients for within-day repeatability of axial stiffness were 0.58 (CI: -0.03 to 0.83) in sitting and 0.82(0.57-0.93) in standing. Despite greater degrees of freedom in standing than sitting, standing involved lesser time, downward displacement, peak output force and was more repeatable in defending upright postural control against the same axial loads. This method provides a foundation for future studies of neuromuscular control with axial perturbation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Torque expression of 0.018 and 0.022 inch conventional brackets.

PubMed

Sifakakis, Iosif; Pandis, Nikolaos; Makou, Margarita; Eliades, Theodore; Katsaros, Christos; Bourauel, Christoph

2013-10-01

The aim of this study was to assess the effect of the moments generated with low- and high-torque brackets. Four different bracket prescription-slot combinations of the same bracket type (Mini Diamond® Twin) were evaluated: high-torque 0.018 and 0.022 inch and low-torque 0.018 and 0.022 inch. These brackets were bonded on identical maxillary acrylic resin models with levelled and aligned teeth and each model was mounted on the orthodontic measurement and simulation system (OMSS). Ten specimens of 0.017 × 0.025 inch and ten 0.019 × 0.025 inch stainless steel archwires (ORMCO) were evaluated in the low- and high-torque 0.018 inch and 0.022 inch brackets, respectively. The wires were ligated with elastomerics into the brackets and each measurement was repeated once after religation. Two-way analysis of variance and t-test were conducted to compare the generated moments between wires at low- and high-torque brackets separately. The maximum moment generated by the 0.017 × 0.025 inch stainless steel archwire in the 0.018 inch brackets at +15 degrees ranged from 14.33 and 12.95 Nmm for the high- and low-torque brackets, respectively. The measured torque in the 0.022 inch brackets with the 0.019 × 0.025 inch stainless steel archwire was 9.32 and 6.48 Nmm, respectively. The recorded differences of maximum moments between the high- and low-torque series were statistically significant. High-torque brackets produced higher moments compared with low-torque brackets. Additionally, in both high- and low-torque configurations, the thicker 0.019 × 0.025 inch steel archwire in the 0.022 inch slot system generated lower moments in comparison with the 0.017 × 0.025 inch steel archwire in the 0.018 inch slot system.

Load response and gap formation in a single-row cruciate suture rotator cuff repair.

PubMed

Huntington, Lachlan; Richardson, Martin; Sobol, Tony; Caldow, Jonathon; Ackland, David C

2017-06-01

Double-row rotator cuff tendon repair techniques may provide superior contact area and strength compared with single-row repairs, but are associated with higher material expenses and prolonged operating time. The purpose of this study was to evaluate gap formation, ultimate tensile strength and stiffness of a single-row cruciate suture rotator cuff repair construct, and to compare these results with those of the Mason-Allen and SutureBridge repair constructs. Infraspinatus tendons from 24 spring lamb shoulders were harvested and allocated to cruciate suture, Mason-Allen and SutureBridge repair groups. Specimens were loaded cyclically between 10 and 62 N for 200 cycles, and gap formation simultaneously measured using a high-speed digital camera. Specimens were then loaded in uniaxial tension to failure, and construct stiffness and repair strength were evaluated. Gap formation in the cruciate suture repair was significantly lower than that of the Mason-Allen repair (mean difference = 0.6 mm, P = 0.009) and no different from that of the SutureBridge repair (P > 0.05). Both the cruciate suture repair (mean difference = 15.7 N/mm, P = 0.002) and SutureBridge repair (mean difference = 15.8 N/mm, P = 0.034) were significantly stiffer than that of the Mason-Allen repair; however, no significant differences in ultimate tensile strength between repair groups were discerned (P > 0.05). The cruciate suture repair construct, which may represent a simple and cost-effective alternative to double-row and double-row equivalent rotator cuff repairs, has comparable biomechanical strength and integrity with that of the SutureBridge repair, and may result in improved construct longevity and tendon healing compared with the Mason-Allen repair. © 2017 Royal Australasian College of Surgeons.

Biomechanical Assessment of the Dorsal Spanning Bridge Plate in Distal Radius Fracture Fixation: Implications for Immediate Weight-Bearing.

PubMed

Huang, Jerry I; Peterson, Bret; Bellevue, Kate; Lee, Nicolas; Smith, Sean; Herfat, Safa

2017-04-01

The goal of this study was to compare the biomechanical stability of a 2.4-mm dorsal spanning bridge plate with a volar locking plate (VLP) in a distal radius fracture model, during simulated crutch weight-bearing. Five paired cadaveric forearms were tested. A 1-cm dorsal wedge osteotomy was created to simulate an unstable distal radius fracture with dorsal comminution. Fractures were fixed with a VLP or a dorsal bridge plate (DBP). Specimens were mounted to a crutch handle, and optical motion-tracking sensors were attached to the proximal and distal segments. Specimens were loaded in compression at 1 mm/s on a servohydraulic test frame until failure, defined as 2 mm of gap site displacement. The VLP construct was significantly more stable to axial load in a crutch weight-bearing model compared with the DBP plate (VLP: 493 N vs DBP: 332 N). Stiffness was higher in the VLP constructs, but this was not statistically significant (VLP: 51.4 N/mm vs DBP: 32.4 N/mm). With the crutch weight-bearing model, DBP failed consistently with wrist flexion and plate bending, whereas VLP failed with axial compression at the fracture site and dorsal collapse. Dorsal spanning bridge plating is effective as an internal spanning fixator in treating highly comminuted intra-articular distal radius fracture and prevents axial collapse at the radiocarpal joint. However, bridge plating may not offer advantages in early weight-bearing or transfer in polytrauma patients, with less axial stability in our crutch weight-bearing model compared with volar plating. A stiffer 3.5-mm DBP or use of a DBP construct without the central holes may be considered for distal radius fractures if the goal is early crutch weight-bearing through the injured extremity.

Biaxial Mechanical Evaluation of Absorbable and Nonabsorbable Synthetic Surgical Meshes Used for Hernia Repair: Physiological Loads Modify Anisotropy Response.

PubMed

Cordero, A; Hernández-Gascón, B; Pascual, G; Bellón, J M; Calvo, B; Peña, E

2016-07-01

The aim of this study was to obtain information about the mechanical properties of six meshes commonly used for hernia repair (Surgipro(®), Optilene(®), Infinit(®), DynaMesh(®), Ultrapro™ and TIGR(®)) by planar biaxial tests. Stress-stretch behavior and equibiaxial stiffness were evaluated, and the anisotropy was determined by testing. In particular, equibiaxial test (equal simultaneous loading in both directions) and biaxial test (half of the load in one direction following the Laplace law) were selected as a representation of physiologically relevant loads. The majority of the meshes displayed values in the range of 8 and 18 (N/mm) in each direction for equibiaxial stiffness (tangent modulus under equibiaxial load state in both directions), while a few achieved 28 and 50 (N/mm) (Infinit (®) and TIGR (®)). Only the Surgipro (®) mesh exhibited planar isotropy, with similar mechanical properties regardless of the direction of loading, and an anisotropy ratio of 1.18. Optilene (®), DynaMesh (®), Ultrapro (®) and TIGR (®) exhibited moderate anisotropy with ratios of 1.82, 1.84, 2.17 and 1.47, respectively. The Infinit (®) scaffold exhibited very high anisotropy with a ratio of 3.37. These trends in material anisotropic response changed during the physiological state in the human abdominal wall, i.e. T:0.5T test, which the meshes were loaded in one direction with half the load used in the other direction. The Surgipro (®) mesh increased its anisotropic response (Anis[Formula: see text] = 0.478) and the materials that demonstrated moderate and high anisotropic responses during multiaxial testing presented a quasi-isotropic response, especially the Infinit(®) mesh that decreased its anisotropic response from 3.369 to 1.292.

Morphologic and biomechanical comparison of spinous processes and ligaments from scoliotic and kyphotic patients.

PubMed

Beaubien, Brian P; Freeman, Andrew L; Buttermann, Glenn R

2016-01-25

The spinous processes and supraspinous and interspinous ligaments (SSL and ISL, respectively) limit flexion and may relate to spinal curvature. Spinous process angles and mechanical properties of explanted human thoracic posterior SSL/ISL complexes were compared for scoliosis (n=14) vs. kyphosis (n=8) patients. The median thoracic coronal Cobb angle for scoliosis patients was 48°, and sagittal angles for kyphosis patients was 78°. Spinous processes were gripped and four strain steps of 4% were applied and held. Percent relaxation was calculated over each step, equilibrium load data were fit to an exponential equation, and a Kelvin model was fit to the load from all four curves. Failure testing was also performed. Median ligament complex dimensions from scoliosis and kyphosis patients were, respectively: ISL width=16.5mm and 16.0mm; SSL width=4.3mm and 3.8mm; ISL+SSL area=17.2mm and 25.7mm; these differences were not significant. Significant differences did exist in terms of spinous process angle vs. spine axis (47° for scoliosis and 32° for kyphosis) and SSL thickness (2.1mm for scoliosis and 3.0mm for kyphosis). Fourth-step median relaxation was 42% for scoliosis and 49% for kyphosis. Median linear region stiffness was 42N/mm for scoliosis and 51N/mm for kyphosis. Median failure load was 191N for scoliotic and 175N for kyphotic ligaments. Differences in loading, relaxation, viscoelastic and failure parameters were not statistically significant, except for a trend for greater initial rate of relaxation (T1) for scoliosis ligaments. However, we found significant morphological differences related to the spinous processes, which suggests a need for future biomechanical studies related to the musculoskeletal aspects of spinal alignment and posture. Copyright © 2015 Elsevier Ltd. All rights reserved.

Investigation of transport properties of FeTe compound

NASA Astrophysics Data System (ADS)

Lodhi, Pavitra Devi; Solanki, Neha; Choudhary, K. K.; Kaurav, Netram

2018-05-01

Transport properties of FeTe parent compound has been investigated by measurements of electrical resistivity, magnetic susceptibility and Seebeck coefficient. The sample was synthesized through a standard solid state reaction route via vacuum encapsulation and characterized by x-ray diffraction, which indicated a tetragonal phase with space group P4/nmm. The parent FeTe compound does not exhibit superconductivity but shows an anomaly in the resistivity measurement at around 67 K, which corresponds to a structural phase transition along with in the vicinity of a magnetic phase transition. In the low temperature regime, Seebeck coefficient, S(T), exhibited an anomalous dip feature and negative throughout the temperature range, indicating electron-like charge carrier conduction mechanism.

Application of ceramic superconductors in high speed turbines

NASA Technical Reports Server (NTRS)

Mcmichael, C. K.; Lamb, M. A.; Lin, M. W.; Ma, K. B.; Chu, W. K.

1992-01-01

A turbine system was modified to adapt melt textured YBa2Cu3O(7-delta) (YBCO) with high energy permanent magnets to form a hybrid superconducting magnetic bearing (HSMB). The HSMB/turbine prototype has achieved a static axial thrust capacity exceeding 41 N/sq cm (60 psi) and a radial magnetic stiffness of 7 N/mm in a field cooled state at 77 K. A comparison was made between different configurations of magnets and superconductor for radial stability, axial instability, and force hystereses. This systematic study lead to a greater understanding of the interactions between YBCO and high energy permanent magnets to define design parameters for high rotational devices using the HSMB design.

An Operational Configuration of the ARPS Data Analysis System to Initialize WRF in the NM'S Environmental Modeling System

NASA Technical Reports Server (NTRS)

Case, Jonathan; Blottman, Pete; Hoeth, Brian; Oram, Timothy

2006-01-01

The Weather Research and Forecasting (WRF) model is the next generation community mesoscale model designed to enhance collaboration between the research and operational sectors. The NM'S as a whole has begun a transition toward WRF as the mesoscale model of choice to use as a tool in making local forecasts. Currently, both the National Weather Service in Melbourne, FL (NWS MLB) and the Spaceflight Meteorology Group (SMG) are running the Advanced Regional Prediction System (AIRPS) Data Analysis System (ADAS) every 15 minutes over the Florida peninsula to produce high-resolution diagnostics supporting their daily operations. In addition, the NWS MLB and SMG have used ADAS to provide initial conditions for short-range forecasts from the ARPS numerical weather prediction (NWP) model. Both NM'S MLB and SMG have derived great benefit from the maturity of ADAS, and would like to use ADAS for providing initial conditions to WRF. In order to assist in this WRF transition effort, the Applied Meteorology Unit (AMU) was tasked to configure and implement an operational version of WRF that uses output from ADAS for the model initial conditions. Both agencies asked the AMU to develop a framework that allows the ADAS initial conditions to be incorporated into the WRF Environmental Modeling System (EMS) software. Developed by the NM'S Science Operations Officer (S00) Science and Training Resource Center (STRC), the EMS is a complete, full physics, NWP package that incorporates dynamical cores from both the National Center for Atmospheric Research's Advanced Research WRF (ARW) and the National Centers for Environmental Prediction's Non-Hydrostatic Mesoscale Model (NMM) into a single end-to-end forecasting system. The EMS performs nearly all pre- and postprocessing and can be run automatically to obtain external grid data for WRF boundary conditions, run the model, and convert the data into a format that can be readily viewed within the Advanced Weather Interactive Processing System

Incorporation of star measurements for the determination of orbit and attitude parameters of a geosynchronous satellite: An iterative application of linear regression

NASA Astrophysics Data System (ADS)

Phillips, D.

1980-10-01

Currently on NOAA/NESS's VIRGS system at the World Weather Building star images are being ingested on a daily basis. The image coordinates of the star locations are measured and stored. Subsequently, the information is used to determine the attitude, the misalignment angles between the spin axis and the principal axis of the satellite, and the precession rate and direction. This is done for both the 'East' and 'West' operational geosynchronous satellites. This orientation information is then combined with image measurements of earth based landmarks to determine the orbit of each satellite. The method for determining the orbit is simple. For each landmark measurement one determines a nominal position vector for the satellite by extending a ray from the landmark's position towards the satellite and intersecting the ray with a sphere with center coinciding with the Earth's center and with radius equal to the nominal height for a geosynchronous satellite. The apparent motion of the satellite around the Earth's center is then approximated with a Keplerian model. In turn the variations of the satellite's height, as a function of time found by using this model, are used to redetermine the successive satellite positions by again using the Earth based landmark measurements and intersecting rays from these landmarks with the newly determined spheres. This process is performed iteratively until convergence is achieved. Only three iterations are required.

Temperature insensitive bending sensor based on in-line Mach-Zehnder interferometer

NASA Astrophysics Data System (ADS)

Chen, Xue; Yu, Yongqin; Xu, Xiaomei; Huang, Quandong; Ou, Zhilong; Wang, Jishun; Yan, Peiguang; Du, Chenlin

2014-09-01

A simple and compact fiber bending sensor based on the Mach-Zehnder interferometer was proposed. A photonic crystal fiber (PCF) with a length of 10 mm was spliced by collapsing air holes with two conventional single mode fibers to consist of an all fiber bending sensor. The sensitivity of 0.53 nm/m-1 was obtained at 1586 nm for the curvature range from 0 to 8.514 m-1. The temperature sensitivity was very low. The measurement error due to the temperature effect was about 8.68×10-3 m-1/°c, and the temperature effect in the curvature measurement could be ignored. This device can avoid the cross sensitivity of the temperature in the curvature measurement.

The AFGL Four Color Infrared Sky Survey: Catalog of Observations at 4. 2, 11.0, 19.8 and 27.4 micrometers

DTIC Science & Technology

1976-09-17

m 0 La ro - - -- - - - - -NNý ý7- miC4’ to in Uve 0 11Nmm 1 v m rvv 0I " m0 -in mC4-- m ko So int 0i~ m1 Li fnMf 4090WMT -N M M G T w m m O O t nvi...Woi’CDr’ nq:;; IT0 C -1-4400 4 l1 1 in L v00N’I0qI W10𔃺(IN 010 n 0(to 0 g NNr m O~ InI 01’ N C a M0 N014n r(N TOi~ni~i N ChIT n0n N m v0 W0101 N

Biomechanics of Two External Fixator Devices Used in Rat Femoral Fractures.

PubMed

Osagie-Clouard, Liza; Kaufmann, Joshua; Blunn, Gordon; Coathup, Melanie; Pendegrass, Catherine; Meeson, Richard; Briggs, Timothy; Moazen, Mehran

2018-05-04

The use of external fixators allows for the direct investigation of newly formed interfragmentary bone, and the radiographic evaluation of the fracture. We validated the results of a finite element model with the in vitro stiffness' of two widely used external fixator devices used for in vivo analysis of fracture healing in rat femoral fractures with differing construction (Ti alloy ExFix1 and PEEK ExFix2). Rat femoral fracture fixation was modelled using two external fixators. For both constructs an osteotomy of 2.75 mm was used, and offset maintained at 5 mm. Tufnol, served as standardized substitutes for rat femora. Constructs were loaded under axial compression and torsion. Overall axial and torsional stiffness were compared between the in vitro models and FE results. FE models were also used to compare the fracture movement and overall pattern of von Mises stress across the external fixators. In vitro axial stiffness of ExFix1 was 29.26 N/mm ± 3.83 compared to ExFix2 6.31 N/mm ± 0.67 (p* < 0.05). Torsional stiffness of ExFix1 was 47.5 Nmm/° ± 2.71 compared to ExFix2 at 19.1 Nmm/° ± 1.18 (p* < 0.05). FE results predicted similar comparative ratios between the ExFix1 and 2 as the in vitro studies. FE results predicted considerably larger interfragmentary motion in the ExFix2 comparing to ExFix1. We demonstrated significant differences in the stiffness' of the two external fixators as one would expect from such variable designs; yet, importantly we validated the utility of an FE model for the analysis and prediction of changes in fracture mechanics dependent on fixator choice. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

A methodological evaluation and predictive in silico investigation into the multi-functionality of arginine in directly compressed tablets.

PubMed

ElShaer, Amr; Kaialy, Waseem; Akhtar, Noreen; Iyire, Affiong; Hussain, Tariq; Alany, Raid; Mohammed, Afzal R

2015-10-01

The acceleration of solid dosage form product development can be facilitated by the inclusion of excipients that exhibit poly-/multi-functionality with reduction of the time invested in multiple excipient optimisations. Because active pharmaceutical ingredients (APIs) and tablet excipients present diverse densification behaviours upon compaction, the involvement of these different powders during compaction makes the compaction process very complicated. The aim of this study was to assess the macrometric characteristics and distribution of surface charges of two powders: indomethacin (IND) and arginine (ARG); and evaluate their impact on the densification properties of the two powders. Response surface modelling (RSM) was employed to predict the effect of two independent variables; Compression pressure (F) and ARG percentage (R) in binary mixtures on the properties of resultant tablets. The study looked at three responses namely; porosity (P), tensile strength (S) and disintegration time (T). Micrometric studies showed that IND had a higher charge density (net charge to mass ratio) when compared to ARG; nonetheless, ARG demonstrated good compaction properties with high plasticity (Y=28.01MPa). Therefore, ARG as filler to IND tablets was associated with better mechanical properties of the tablets (tablet tensile strength (σ) increased from 0.2±0.05N/mm(2) to 2.85±0.36N/mm(2) upon adding ARG at molar ratio of 8:1 to IND). Moreover, tablets' disintegration time was shortened to reach few seconds in some of the formulations. RSM revealed tablet porosity to be affected by both compression pressure and ARG ratio for IND/ARG physical mixtures (PMs). Conversely, the tensile strength (σ) and disintegration time (T) for the PMs were influenced by the compression pressure, ARG ratio and their interactive term (FR); and a strong correlation was observed between the experimental results and the predicted data for tablet porosity. This work provides clear evidence of the

[Engine-driven preparation of curved root canals: a platform to assess physical parameters].

PubMed

Peters, O A; Kappeler, S; Bucher, W; Barbakow, F

2001-01-01

The number of engine-driven rotary instruments available on the market is steadily increasing. These instruments enable clinicians to prepare better shaped root canals, however, rotary instruments have a higher risk for fracture than hand instruments. Unfortunately, the stresses placed on engine-driven rotary instruments in curved canals are insufficiently studied. The aim of this study was to develop a device which could measure more accurately the physical parameters influencing rotary instruments in curved canals. For this purpose, a specially designed machine was constructed to measure the torque which develops between the rotary instrument and the motor. Apical forces and penetration depths could also be directly measured in real time. A variety of other measurements was also possible because of other special set-ups integrated into the device. In the current study torque was assessed for GT-Files, size 35 with a .12 and sizes 20 with a .12 to .06 taper. In additions to preparations in simulated canals in plastic blocks, the "ISO 3630-1 specification for fracture moment" and "number of cycles till fatigue fracture" was measured. The findings indicated that when instruments were used for preparations, torques up to 40 Nmm were present. This exceeded the static fracture load, which was less than than 13 Nmm for the size 20 with .12 taper. In contrast, the number of rotations were more than 10 times lower when shaping canals in plastic blocks with a 5 mm radius of curvature than the number of rotations to fracture in the "cyclic fatigue test". This suggests that a GT-instrument could be used in ten canals. The apical force was always greater than 1 N and occasionally, 8 N or more was recorded. Further studies on natural teeth with varying canal geometries are required using the specially developed torsional machine to reduce the incidence of instrument fracture. In this way an efficient clinical potential can be confirmed for engine-driven rotary instruments in

A novel use of 3D printing model demonstrates the effects of deteriorated trabecular bone structure on bone stiffness and strength.

PubMed

Barak, Meir Max; Black, Margaret Arielle

2018-02-01

Trabecular bone structure is crucial to normal mechanical behavior of bones. Studies have shown that osteoporosis negatively affects trabecular bone structure, mainly by reducing bone volume fraction (BV/TV) and thus increasing fracture risk. One major limitation in assessing and quantifying the effect of this structural deterioration is that no two trabecular structures are identical. Thus, when we compare a group of healthy bones against a different group of bones that experienced resorption (i.e. decreased BV/TV) we only discover an "average" mechanical effect. It is impossible to quantify the mechanical effect of individual structural deterioration for each sample, simply because we never have the same sample in both states (intact and deteriorated structure). 3D printing is a new technology that can assist in overcoming this issue. Here we report a preliminary study that compares a healthy 3D printed trabecular bone model with the same model after bone resorption was simulated. Since the deteriorated structural bone model is derived from the healthy one, it is possible to directly estimate (percentage wise) the decrease of tissue stiffness and strength as a result of bone resorption for this specific structure. Our results demonstrate that a relatively small decrease in BV/TV (about 8%) leads to a dramatic decrease in structural strength (24%) and structural stiffness (17%), (P < 0.01). Structural strength decreased from an average of 9.14 ± 2.85MPa to 6.97 ± 2.44MPa, while structural stiffness decreased from an average of 282.5 ± 63.4N/mm to 233.8 ± 51.2N/mm. This study demonstrates that 3D printing is a novel and valuable tool for quantifying the effect of structural deterioration on the mechanical properties of trabecular bone. In the future, this approach may help us attain better personal fracture risk assessments by CT scanning, 3D printing and mechanically testing individual bone replicas from patients suffering excessive bone resorption. Copyright

Biomechanical Comparison of Superior Versus Anterior Plate Position for Fixation of Distal Clavicular Fractures: A New Model.

PubMed

Wilkerson, James; Paryavi, Ebrahim; Kim, Hyunchul; Murthi, Anand; Pensy, Raymond A

2017-01-01

Although most clavicular fractures are amenable to nonoperative management, metadiaphyseal fractures are considerably more complex, with rates of suboptimal healing as high as 75% when treated nonoperatively. The poor results are ascribed to the deforming forces on the distal clavicle from the surrounding muscles and the weight of the arm. It recently has been noted that some operative fixations of these fractures are also failing when a standard superiorly placed plate is used. We hypothesized that anterior plating, when compared with superior plating, improves the strength and durability of the construct by redirecting the axis of the major deforming force across rather than in line with the screws of the construct. Six pairs of fresh-frozen human cadaveric clavicles with the scapula attached by the coracoclavicular ligaments were osteotomized just medial to the ligaments and plated with a standard 3.5-mm limited-contact dynamic compression plate. Specimens were potted and mounted on a materials testing system machine, preserving the anatomic relationship of the clavicle and scapula. They were then loaded through the coracoclavicular ligaments to mimic the weight of the arm pulling inferiorly. Each specimen was loaded with 375 N at 1 Hz for 2000 cycles. Sequential loading was then applied at 25-N intervals until failure. Statistical analysis was performed using a Wilcoxon signed-rank test. The superiorly plated specimens failed after fewer cycles and with lower force than the anteriorly plated specimens. The median number of cycles to failure was 2082 for anterior plated specimens and 50 for superiorly plated (P = 0.028). The median load to failure was 587.5 N in the anterior group and 375 N in the superior group (P = 0.035). The median stiffness was 46.13 N/mm for anterior and 40.45 N/mm for superior (P = 0.375) plates. Anteriorly plated distal third clavicular fractures have superior strength and durability compared with fractures plated superiorly when using a

Double-Row Capsulolabral Repair Increases Load to Failure and Decreases Excessive Motion.

PubMed

McDonald, Lucas S; Thompson, Matthew; Altchek, David W; McGarry, Michelle H; Lee, Thay Q; Rocchi, Vanna J; Dines, Joshua S

2016-11-01

Using a cadaver shoulder instability model and load-testing device, we compared biomechanical characteristics of double-row and single-row capsulolabral repairs. We hypothesized a greater reduction in glenohumeral motion and translation and a higher load to failure in a mattress double-row capsulolabral repair than in a single-row repair. In 6 matched pairs of cadaveric shoulders, a capsulolabral injury was created. One shoulder was repaired with a single-row technique, and the other with a double-row mattress technique. Rotational range of motion, anterior-inferior translation, and humeral head kinematics were measured. Load-to-failure testing measured stiffness, yield load, deformation at yield load, energy absorbed at yield load, load to failure, deformation at ultimate load, and energy absorbed at ultimate load. Double-row repair significantly decreased external rotation and total range of motion compared with single-row repair. Both repairs decreased anterior-inferior translation compared with the capsulolabral-injured condition, however, no differences existed between repair types. Yield load in the single-row group was 171.3 ± 110.1 N, and in the double-row group it was 216.1 ± 83.1 N (P = .02). Ultimate load to failure in the single-row group was 224.5 ± 121.0 N, and in the double-row group it was 373.9 ± 172.0 N (P = .05). Energy absorbed at ultimate load in the single-row group was 1,745.4 ± 1,462.9 N-mm, and in the double-row group it was 4,649.8 ± 1,930.8 N-mm (P = .02). In cases of capsulolabral disruption, double-row repair techniques may result in decreased shoulder rotational range of motion and improved load-to-failure characteristics. In cases of capsulolabral disruption, repair techniques with double-row mattress repair may provide more secure fixation. Double-row capsulolabral repair decreases shoulder motion and increases load to failure, yield load, and energy absorbed at yield load more than single-row repair. Published by

A biomechanical comparison of 2 transosseous-equivalent double-row rotator cuff repair techniques using bioabsorbable anchors: cyclic loading and failure behavior.

PubMed

Spang, Jeffrey T; Buchmann, Stefan; Brucker, Peter U; Kouloumentas, Panos; Obst, Tobias; Schröder, Manuel; Burgkart, Rainer; Imhoff, Andreas B

2009-08-01

A novel double-row configuration was compared with a traditional double-row configuration for rotator cuff repair. In 10 matched-pair sheep shoulders in vitro repair was performed with either a double-row technique with corkscrew suture anchors for the medial row and insertion anchors for the lateral row (group A) or a double-row technique with a new tape-like suture material with insertion anchors for both the medial and lateral rows (group B). Each specimen underwent cyclic loading from 10 to 150 N for 100 cycles, followed by unidirectional failure testing. Gap formation and strain within the repair area for the first and last cycles were analyzed with a video digitizing system, and stiffness and failure load were determined from the load-elongation curve. The results were similar for the 2 repair types. There was no significant difference between the ultimate failure loads of the 2 techniques (421 +/- 150 N in group A and 408 +/- 66 N in group B, P = .31) or the stiffness of the 2 techniques (84 +/- 26 N/mm in group A and 99 +/- 20 N/mm in group B, P = .07). In addition, gap formation was not different between the repair types. Strain over the repair area was also not different between the repair types. Both tested rotator cuff repair techniques had high failure loads, limited gap formation, and acceptable strain patterns. No significant difference was found between the novel and conventional double-row repair types. Two double-row techniques-one with corkscrew suture anchors for the medial row and insertion anchors for the lateral row and one with insertion anchors for both the medial and lateral rows-provided excellent biomechanical profiles at time 0 for double-row repairs in a sheep model. Although the sheep model may not directly correspond to in vivo conditions, all-insertion anchor double-row constructs are worthy of further investigation.

Biomechanical properties of double- and single-row suture anchor repair for surgical treatment of insertional Achilles tendinopathy.

PubMed

Beitzel, Knut; Mazzocca, Augustus D; Obopilwe, Elifho; Boyle, James W; McWilliam, James; Rincon, Lina; Dhar, Yasmin; Arciero, Robert A; Amendola, Annunziato

2013-07-01

Because of intratendinous ossifications, retrocalcaneal bursitis, or intratendinous necrosis commonly found in insertional tendinosis, it is often necessary to detach the tendon partially or entirely from its tendon-to-bone junction. Double-row repair for insertional Achilles tendinopathy will generate an increased contact area and demonstrate higher biomechanical stability. Controlled laboratory study. Eighteen cadaver Achilles tendons were split longitudinally and detached, exposing the calcaneus; an ostectomy was performed and the tendon was reattached to the calcaneus in 1 of 2 ways: 2 suture anchors (single row) or a 4-anchor (double row) construct. Footprint area measurements over time, displacement after cyclic loading (2000 cycles), and final load to failure were measured. The double-row refixation technique was statistically superior to the single-row technique in footprint area measurement initially and 5 minutes after repair (P = .009 and P = .01, respectively) but not after 24 hours (P = .713). The double-row construct demonstrated significantly improved measures for peak load (433.9 ± 84.3 N vs 212.0 ± 49.7 N; P = .042), load at yield (354.7 ± 106.2 N vs 198.7 ± 39.5 N; P = .01), and slope (51.8 ± 9.9 N/mm vs 66.7 ± 16.2 N/mm; P = .021). Cyclic loading did not demonstrate significant differences between the 2 constructs. Double-row construct for reinsertion of a completely detached Achilles tendon using proximal and distal rows resulted in significantly larger contact area initially and 5 minutes after repair and led to significantly higher peak load to failure on destructive testing. In treatment for insertional Achilles tendinosis, the tendon often has to be detached and anatomically reattached to its insertion at the calcaneus. To our knowledge there is a lack of biomechanical studies supporting either a number or a pattern of suture anchor fixation. Because the stresses going across the insertion site of the Achilles tendon are significant

[Odontoid bending stiffness after anterior fixation with a single lag screw: biomechanical study].

PubMed

Buchvald, P; Čapek, L; Barsa, P

2015-01-01

PURPOSE OF THE STUDY The aim of the experiment was to compare the bending stiffness of an intact odontoid process with bending stiffness after its simulated type II fracture was fixed with a single lag screw. The experiment was done with a desire to answer the question of whether a single osteosynthetic screw is sufficient for good fixation of a type II odontoid fracture. MATERIAL AND METHODS The C2 vertebrae of six cadavers were used. With simultaneous measurement of odontoid bending stiffness, the occurrence of a fracture (type IIA, Grauer's modification of the Anderson- D'Alonzo classification) was simulated using action exerted by a tearing machine in the direction perpendicular to the odontoid axis. Each odontoid fracture was subsequently treated by direct osteosynthesis with a single lag screw inserted in the axial direction by a standard surgical procedure in order to provide conditions similar to those achieved by routine surgical management. The treated odontoid process was subsequently subjected to the same tearing machine loading as applied to it at the start of the experiment. The bending stiffness measured was then compared with that found before the fracture occurred. The results were statistically evaluated by the t-test for paired samples at the level of significance α = 0.05. RESULTS The average value of bending stiffness for odontoid processes of intact vertebrae at the moment of fracture occurrence was 318.3 N/mm. After single axial lag screw fixation of the fracture, the average bending stiffness for the odontoid processes treated was 331.3 N/mm. DISCUSSION Higher values of bending stiffness after screw fixation were found in all specimens and, in comparison with the values recorded before simulated fractures, the increase was statistically significant. CONCLUSIONS The results of our measurements suggest that the single lag screw fixation of a type IIA odontoid fracture will provide better stability for the fracture fragment-C2 body complex on

Anatomic and Biomechanical Comparison of Traditional Bankart Repair With Bone Tunnels and Bankart Repair Utilizing Suture Anchors

PubMed Central

Judson, Christopher H.; Charette, Ryan; Cavanaugh, Zachary; Shea, Kevin P.

2016-01-01

Background: Traditional Bankart repair using bone tunnels has a reported failure rate between 0% and 5% in long-term studies. Arthroscopic Bankart repair using suture anchors has become more popular; however, reported failure rates have been cited between 4% and 18%. There have been no satisfactory explanations for the differences in these outcomes. Hypothesis: Bone tunnels will provide increased coverage of the native labral footprint and demonstrate greater load to failure and stiffness and decreased cyclic displacement in biomechanical testing. Study Design: Controlled laboratory study. Methods: Twenty-two fresh-frozen cadaveric shoulders were used. For footprint analysis, the labral footprint area was marked and measured using a Microscribe technique in 6 specimens. A 3-suture anchor repair was performed, and the area of the uncovered footprint was measured. This was repeated with traditional bone tunnel repair. For the biomechanical analysis, 8 paired specimens were randomly assigned to bone tunnel or suture anchor repair with the contralateral specimen assigned to the other technique. Each specimen underwent cyclic loading (5-25 N, 1 Hz, 100 cycles) and load to failure (15 mm/min). Displacement was measured using a digitized video recording system. Results: Bankart repair with bone tunnels provided significantly more coverage of the native labral footprint than repair with suture anchors (100% vs 27%, P < .001). Repair with bone tunnels (21.9 ± 8.7 N/mm) showed significantly greater stiffness than suture anchor repair (17.1 ± 3.5 N/mm, P = .032). Mean load to failure and gap formation after cyclic loading were not statistically different between bone tunnel (259 ± 76.8 N, 0.209 ± 0.064 mm) and suture anchor repairs (221.5 ± 59.0 N [P = .071], 0.161 ± 0.51 mm [P = .100]). Conclusion: Bankart repair with bone tunnels completely covered the footprint anatomy while suture anchor repair covered less than 30% of the native footprint. Repair using bone tunnels

Anatomic and Biomechanical Comparison of Traditional Bankart Repair With Bone Tunnels and Bankart Repair Utilizing Suture Anchors.

PubMed

Judson, Christopher H; Charette, Ryan; Cavanaugh, Zachary; Shea, Kevin P

2016-01-01

Traditional Bankart repair using bone tunnels has a reported failure rate between 0% and 5% in long-term studies. Arthroscopic Bankart repair using suture anchors has become more popular; however, reported failure rates have been cited between 4% and 18%. There have been no satisfactory explanations for the differences in these outcomes. Bone tunnels will provide increased coverage of the native labral footprint and demonstrate greater load to failure and stiffness and decreased cyclic displacement in biomechanical testing. Controlled laboratory study. Twenty-two fresh-frozen cadaveric shoulders were used. For footprint analysis, the labral footprint area was marked and measured using a Microscribe technique in 6 specimens. A 3-suture anchor repair was performed, and the area of the uncovered footprint was measured. This was repeated with traditional bone tunnel repair. For the biomechanical analysis, 8 paired specimens were randomly assigned to bone tunnel or suture anchor repair with the contralateral specimen assigned to the other technique. Each specimen underwent cyclic loading (5-25 N, 1 Hz, 100 cycles) and load to failure (15 mm/min). Displacement was measured using a digitized video recording system. Bankart repair with bone tunnels provided significantly more coverage of the native labral footprint than repair with suture anchors (100% vs 27%, P < .001). Repair with bone tunnels (21.9 ± 8.7 N/mm) showed significantly greater stiffness than suture anchor repair (17.1 ± 3.5 N/mm, P = .032). Mean load to failure and gap formation after cyclic loading were not statistically different between bone tunnel (259 ± 76.8 N, 0.209 ± 0.064 mm) and suture anchor repairs (221.5 ± 59.0 N [P = .071], 0.161 ± 0.51 mm [P = .100]). Bankart repair with bone tunnels completely covered the footprint anatomy while suture anchor repair covered less than 30% of the native footprint. Repair using bone tunnels resulted in significantly greater stiffness than repair with suture

Analysis of the torque capacity of a completely customized lingual appliance of the next generation

PubMed Central

2014-01-01

Introduction In lingual orthodontic therapy, effective torque control of the incisors is crucial due to the biomechanical particularities associated with the point of force application and the tight link between third order deviations and vertical tooth position. Aim The aim of the present in vitro investigation was to analyze the torque capacity of a completely customized lingual appliance of the next generation (WIN) in combination with different finishing archwire dimensions. Methods Using a typodont of the upper arch carrying the WIN appliance, slot filling and undersized individualized β-titanium archwires were engaged. Horizontal forces ranging from 0 to 100 cN were applied at the central incisor by means of spring gauges. The resulting angular deviations were recorded and the corresponding torque moments were calculated. Results For fullsize archwires (0.018”×0.018” β-titanium and 0.018”×0.025” β-titanium), an initial torque play of 0-2° had to be overcome prior to the development of an effective torque moment. Thereafter, a linear correlation between torque angle and torque moment developed for both archwire dimensions with steeper slopes calculated for the specimens with the larger dimension. A torque moment of 2 Nmm required for effective torque correction was noted after a minimum of 2-3° of twist for the 0.018”×0.018” β-titanium wires as compared to 2-4° for the 0.018”×0.025” β-titanium study sample. When undersized archwires were analyzed (0.0175”×0.0175” β-titanium), the measured torque play ranged from 5-7°. After 8-12° of torque angle, the threshold of 2 Nmm was reached. A linear relationship between twist angle and torque moment in which the steepness of the slopes was generally flatter than the ones calculated for the slot filling archwires was noted. Conclusions Given the high precision of the bracket slot-archwire-combination provided with the WIN appliance, an effective torque control can be clinically

Validation of SMAP Radar Vegetation Data Cubes from Agricultural Field Measurements

NASA Astrophysics Data System (ADS)

Tsang, L.; Xu, X.; Liao, T.; Kim, S.; Njoku, E. G.

2012-12-01

The NASA Soil Moisture Active/Passive (SMAP) Mission will be launched in October 2014. The objective of the SMAP mission is to provide global measurements of soil moisture and its freeze/thaw state. These measurements will be used to enhance understanding of processes that link the water, energy and carbon cycles, and to extend the capabilities of weather and climate prediction models. In the active algorithm, the retrieval is performed based on the backscattering data cube, which are characterized by two surface parameters, which are soil moisture and soil surface rms height, and one vegetation parameter, the vegetation water content. We have developed a physical-based forward scattering model to generate the data cube for agricultural fields. To represent the agricultural crops, we include a layer of cylinders and disks on top of the rough surface. The scattering cross section of the vegetation layer and its interaction with the underground soil surface were calculated by the distorted Born approximation, which give explicitly three scattering mechanisms. A) The direct volume scattering B) The double bounce effect as, and C) The double bouncing effects. The direct volume scattering is calculated by using the Body of Revolution code. The double bounce effects, exhibited by the interaction of rough surface with the vegetation layer is considered by modifying the rough surface reflectivity using the coherent wave as computed by Numerical solution of Maxwell equations of 3 Dimensional simulations (NMM3D) of bare soil scattering. The rough surface scattering of the soil was calculated by NMM3D. We have compared the physical scattering models with field measurements. In the field campaign, the measurements were made on soil moisture, rough surface rms heights and vegetation water content as well as geometric parameters of vegetation. The three main crops lands are grassland, cornfield and soybean fields. The corresponding data cubes are validated using SGP99, SMEX02

Superionic Phases of the 1:1 Water–Ammonia Mixture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bethkenhagen, Mandy; Cebulla, Daniel; Redmer, Ronald

We report four structures for the 1:1 water–ammonia mixture showing superionic behavior at high temperature with the space groups P4/ nmm, Ima2, Pma2, and Pm, which have been identified from evolutionary random structure search calculations at 0 K. Analyzing the respective pair distribution functions and diffusive properties the superionic phase is found to be stable in a temperature range between 1000 and 6000 K for pressures up to 800 GPa. We propose a high-pressure phase diagram of the water–ammonia mixture for the first time and compare the self-diffusion coefficients in the mixture to the ones found in water and ammonia.more » Lastly, possible implications on the interior structure of the giant planets Uranus and Neptune are discussed.« less

Superionic Phases of the 1:1 Water–Ammonia Mixture

DOE PAGES

Bethkenhagen, Mandy; Cebulla, Daniel; Redmer, Ronald; ...

2015-09-21

We report four structures for the 1:1 water–ammonia mixture showing superionic behavior at high temperature with the space groups P4/ nmm, Ima2, Pma2, and Pm, which have been identified from evolutionary random structure search calculations at 0 K. Analyzing the respective pair distribution functions and diffusive properties the superionic phase is found to be stable in a temperature range between 1000 and 6000 K for pressures up to 800 GPa. We propose a high-pressure phase diagram of the water–ammonia mixture for the first time and compare the self-diffusion coefficients in the mixture to the ones found in water and ammonia.more » Lastly, possible implications on the interior structure of the giant planets Uranus and Neptune are discussed.« less

Label-free logic modules and two-layer cascade based on stem-loop probes containing a G-quadruplex domain.

PubMed

Guo, Yahui; Cheng, Junjie; Wang, Jine; Zhou, Xiaodong; Hu, Jiming; Pei, Renjun

2014-09-01

A simple, versatile, and label-free DNA computing strategy was designed by using toehold-mediated strand displacement and stem-loop probes. A full set of logic gates (YES, NOT, OR, NAND, AND, INHIBIT, NOR, XOR, XNOR) and a two-layer logic cascade were constructed. The probes contain a G-quadruplex domain, which was blocked or unfolded through inputs initiating strand displacement and the obviously distinguishable light-up fluorescent signal of G-quadruplex/NMM complex was used as the output readout. The inputs are the disease-specific nucleotide sequences with potential for clinic diagnosis. The developed versatile computing system based on our label-free and modular strategy might be adapted in multi-target diagnosis through DNA hybridization and aptamer-target interaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical fiber curvature sensor based on MMF-SCF-MMF structure

NASA Astrophysics Data System (ADS)

Wang, Qi; Liu, Yu

2018-07-01

A sensitive curvature sensor based on MMF-SCF-MMF (MMF: multimode fiber; SCF: seven core fiber) structure is proposed. The multimode fiber (MMF) are used to improve the light coupling efficiency between the input singlemode fiber (SMF) and the seven-core fiber (SCF), and the seven-core fiber is used as the main element for curvature measurement. Experimental results show that the best curvature sensitivity reaches 41.46453 nm/m-1 in the range of 0.094 m-1-0.567 m-1. The temperature sensitivity is up to 59.02 pm/°C in the range of 20 °C-55 °C. The optical curvature sensors are widely used for buildings structure health monitoring and mechanical engineering due to the advantages of compact structure, anti-electromagnetic interference, and low cost.

Thermal, optical, and dielectric properties of fluoride Rb2TaF7

NASA Astrophysics Data System (ADS)

Pogorel'tsev, E. I.; Mel'nikova, S. V.; Kartashev, A. V.; Gorev, M. V.; Flerov, I. N.; Laptash, N. M.

2017-05-01

The thermal, optical, and dielectric properties of fluoride Rb2TaF7 were investigated. It was observed that the variation in chemical pressure in fluorides A 2 +TaF7 caused by the cation substitution of rubidium for ammonium does not affect the ferroelastic nature of structural distortions, but leads to stabilization of the high- and low-temperature phases and enhancement of birefringence. The entropy of the phase transition P4/nmm ↔ Cmma is typical of the shift transformations, which is consistent with a model of the initial and distorted phase structures. The anisotropy of chemical pressure causes the change of signs of the anomalous strain and baric coefficient dT/ dp of Rb2TaF7 as compared with the values for its ammonium analog.

Host and Bacterial Proteins That Repress Recruitment of LC3 to Shigella Early during Infection

PubMed Central

Baxt, Leigh A.; Goldberg, Marcia B.

2014-01-01

Shigella spp. are intracytosolic gram-negative pathogens that cause disease by invasion and spread through the colonic mucosa, utilizing host cytoskeletal components to form propulsive actin tails. We have previously identified the host factor Toca-1 as being recruited to intracellular S. flexneri and being required for efficient bacterial actin tail formation. We show that at early times during infection (40 min.), the type three-secreted effector protein IcsB recruits Toca-1 to intracellular bacteria and that recruitment of Toca-1 is associated with repression of recruitment of LC3, as well as with repression of recruitment of the autophagy marker NDP52, around these intracellular bacteria. LC3 is best characterized as a marker of autophagosomes, but also marks phagosomal membranes in the process LC3-associated phagocytosis. IcsB has previously been demonstrated to be required for S. flexneri evasion of autophagy at late times during infection (4–6 hr) by inhibiting binding of the autophagy protein Atg5 to the Shigella surface protein IcsA (VirG). Our results suggest that IcsB and Toca-1 modulation of LC3 recruitment restricts LC3-associated phagocytosis and/or LC3 recruitment to vacuolar membrane remnants. Together with published results, our findings suggest that IcsB inhibits innate immune responses in two distinct ways, first, by inhibiting LC3-associated phagocytosis and/or LC3 recruitment to vacuolar membrane remnants early during infection, and second, by inhibiting autophagy late during infection. PMID:24722587

Synthesis and characterization of Ca-doped LaMnAsO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yong; Straszheim, Warren E.; Das, Pinaki

Here, we report on our attempt to hole-dope the antiferromagnetic semiconductor LaMnAsO by substitution of the La 3+ site by Ca 2+. We use neutron and x-ray diffraction, magnetic susceptibility, and transport techniques to characterize polycrystalline (La 1–xCa x)MnAsO samples prepared by solid-state reaction and find that the parent compound is highly resistant to substitution with an upper limit x ≤ 0.01. Magnetic susceptibility of the parent and the x = 0.002(x nom = 0.04) compounds indicate a negligible presence of magnetic impurities (i.e., MnO or MnAs). Rietveld analysis of neutron and x-ray diffraction data shows the preservation of bothmore » the tetragonal (P4/nmm) structure upon doping and the antiferromagnetic ordering temperature, T N = 355 ± 5 K.« less

Ba 2TeO as an optoelectronic material: First-principles study

DOE PAGES

Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; ...

2015-05-21

The band structure, optical and defects properties of Ba 2TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba 2TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical band gap1. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show a infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba 2TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneousmore » formation of the donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.« less

Strength Analysis of Coconut Fiber Stabilized Earth for Farm Structures

NASA Astrophysics Data System (ADS)

Enokela, O. S.; P. O, Alada

2012-07-01

Investigation of the strength characteristic of soil from alluvial deposit of River Benue in makurdi stabilized with coconut fiber as a stabilizer was carried as local building material for farm structure. Processed coconut fibers were mixed with the soil at four different mix ratios of 1% fiber, 2% fiber, 3% fiber and 4% fiber by percentage weight with 0% fiber as control. Compaction test and compressive strength were carried out on the various stabilizing ratio. From the compaction test, the correlation between the maximum dry density and optimum moisture content is a second order polynomial with a coefficient of 63% obtained at1.91kg/m3and 20.0% respectively while the compressive strength test shows an optimum failure load of 8.62N/mm2 at 2%fibre:100% soil mix ratio at 2.16 maximum dry density.

Physical properties of high performance fluoride ion conductor BaSnF4 thin films by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Patro, L. N.; Ravi Chandra Raju, N.; Meher, S. R.; Kamala Bharathi, K.

2013-09-01

This article presents the results on the growth and characterization of BaSnF4 thin films on glass substrates prepared by pulsed laser deposition technique. The structural results of BaSnF4 thin film carried out by glancing angle X-ray diffraction technique indicates the formation of the film with similar structure (tetragonal, P4/nmm) to the bulk target material. The absorption coefficient and band gap of the film is determined by suitable analysis of the transmittance spectra. The transport properties of the thin films are studied using impedance spectroscopy in the temperature range of 323-573 K. The frequency-dependent imaginary part of impedance plot shows that the conductivity relaxation is non-Debye in nature. The scaling behavior of the imaginary part of impedance at various frequencies indicates temperature-independent relaxation behavior.

Fiber-optic extrinsic Fabry-Perot interferometer strain sensor with <50 pm displacement resolution using three-wavelength digital phase demodulation.

PubMed

Schmidt, M; Werther, B; Fuerstenau, N; Matthias, M; Melz, T

2001-04-09

A fiber-optic extrinsic Fabry-Perot interferometer strain sensor (EFPI-S) of ls = 2.5 cm sensor length using three-wavelength digital phase demodulation is demonstrated to exhibit <50 pm displacement resolution (<2nm/m strain resolution) when measuring the cross expansion of a PZT-ceramic plate. The sensing (single-mode downlead-) and reflecting fibers are fused into a 150/360 microm capillary fiber where the fusion points define the sensor length. Readout is performed using an improved version of the previously described three-wavelength digital phase demodulation method employing an arctan-phase stepping algorithm. In the resent experiments the strain sensitivity was varied via the mapping of the arctan - lookup table to the 16-Bit DA-converter range from 188.25 k /V (6 Volt range 1130 k ) to 11.7 k /Volt (range 70 k ).

Development of kenaf mat for slope stabilization

NASA Astrophysics Data System (ADS)

Ahmad, M. M.; Manaf, M. B. H. Ab; Zainol, N. Z.

2017-09-01

This study focusing on the ability of kenaf mat to act as reinforcement to laterite compared to the conventional geosynthetic in term of stabilizing the slope. Kenaf mat specimens studied in this paper are made up from natural kenaf fiber with 3mm thickness, 150mm length and 20mm width. With the same size of specimens, geosynthetic that obtain from the industry are being tested for both direct shear and tensile tests. Plasticity index of the soil sample used is equal to 13 which indicate that the soil is slightly plastic. Result shows that the friction angle of kenaf mat is higher compared to friction between soil particles itself. In term of resistance to tensile load, the tensile strength of kenaf mat is 0.033N/mm2 which is lower than the tensile strength of geosynthetic.

Synthesis and characterization of Ca-doped LaMnAsO

DOE PAGES

Liu, Yong; Straszheim, Warren E.; Das, Pinaki; ...

2018-05-18

Here, we report on our attempt to hole-dope the antiferromagnetic semiconductor LaMnAsO by substitution of the La 3+ site by Ca 2+. We use neutron and x-ray diffraction, magnetic susceptibility, and transport techniques to characterize polycrystalline (La 1–xCa x)MnAsO samples prepared by solid-state reaction and find that the parent compound is highly resistant to substitution with an upper limit x ≤ 0.01. Magnetic susceptibility of the parent and the x = 0.002(x nom = 0.04) compounds indicate a negligible presence of magnetic impurities (i.e., MnO or MnAs). Rietveld analysis of neutron and x-ray diffraction data shows the preservation of bothmore » the tetragonal (P4/nmm) structure upon doping and the antiferromagnetic ordering temperature, T N = 355 ± 5 K.« less

Crystallographic and magnetic structure of UCu{sub 1.5}Sn{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Purwanto, A.; Robinson, R.A.; Nakotte, H.

1996-04-01

We report on the crystallographic and magnetic structures of the antiferromagnet UCu{sub 1.5}Sn{sub 2}, as determined by x-ray and neutron powder diffraction. It crystallizes in the tetragonal CaBe{sub 2}Ge{sub 2} structure type, with space group P/4nmm, and we find no site disorder between two different Sn2{ital c} sites, in contrast with a previous report. UCu{sub 1.5}Sn{sub 2} orders antiferromagnetically with a N{acute e}el temperature of about 110 K. This is unusually high among uranium intermetallics. The uranium moments align along the {ital c} axis in a collinear arrangement but alternating along the {ital c} axis. The low-temperature uranium moment ismore » 2.01{mu}{sub {ital B}}. {copyright} {ital 1996 American Institute of Physics.}« less

Weather Research and Forecasting Model Sensitivity Comparisons for Warm Season Convective Initiation

NASA Technical Reports Server (NTRS)

Watson, Leela R.; Hoeth, Brian; Blottman, Peter F.

2007-01-01

Mesoscale weather conditions can significantly affect the space launch and landing operations at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). During the summer months, land-sea interactions that occur across KSC and CCAFS lead to the formation of a sea breeze, which can then spawn deep convection. These convective processes often last 60 minutes or less and pose a significant challenge to the forecasters at the National Weather Service (NWS) Spaceflight Meteorology Group (SMG). The main challenge is that a "GO" forecast for thunderstorms and precipitation is required at the 90 minute deorbit decision for End Of Mission (EOM) and at the 30 minute Return To Launch Site (RTLS) decision at the Shuttle Landing Facility. Convective initiation, timing, and mode also present a forecast challenge for the NWS in Melbourne, FL (MLB). The NWS MLB issues such tactical forecast information as Terminal Aerodrome Forecasts (TAFs), Spot Forecasts for fire weather and hazardous materials incident support, and severe/hazardous weather Watches, Warnings, and Advisories. Lastly, these forecasting challenges can also affect the 45th Weather Squadron (45 WS), which provides comprehensive weather forecasts for shuttle launch, as well as ground operations, at KSC and CCAFS. The need for accurate mesoscale model forecasts to aid in their decision making is crucial. Both the SMG and the MLB are currently implementing the Weather Research and Forecasting Environmental Modeling System (WRF EMS) software into their operations. The WRF EMS software allows users to employ both dynamical cores - the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM). There are also data assimilation analysis packages available for the initialization of the WRF model- the Local Analysis and Prediction System (LAPS) and the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS). Having a series of initialization options and WRF cores, as well as many

Biomechanics of a Bone-Periodontal Ligament-Tooth Fibrous Joint

PubMed Central

Lin, Jeremy D.; Özcoban, Hüseyin; Greene, Janelle; Jang, Andrew T.; Djomehri, Sabra; Fahey, Kevin; Hunter, Luke; Schneider, Gerold A; Ho, Sunita P.

2013-01-01

This study investigates bone-tooth association under compression to identify strain amplified sites within the bone-periodontal ligament (PDL)-tooth fibrous joint. Our results indicate that the biomechanical response of the joint is due to a combinatorial response of constitutive properties of organic, inorganic, and fluid components. Second maxillary molars within intact maxillae (N=8) of 5-month-old rats were loaded with a μ-XCT-compatible in situ loading device at various permutations of displacement rates (0.2, 0.5, 1.0, 1.5, 2.0 mm/min) and peak reactionary load responses (5, 10, 15, 20 N). Results indicated a nonlinear biomechanical response of the joint, in which the observed reactionary load rates were directly proportional to displacement rates (velocities). No significant differences in peak reactionary load rates at a displacement rate of 0.2 mm/min were observed. However, for displacement rates greater than 0.2 mm/min, an increasing trend in reactionary rate was observed for every peak reactionary load with significant increases at 2.0 mm/min. Regardless of displacement rates, two distinct behaviors were identified with stiffness (S) and reactionary load rate (LR) values at a peak load of 5 N (S5 N=290–523 N/mm) being significantly lower than those at 10 N (LR5 N=1–10 N/s) and higher (S10N–20 N=380–684 N/mm; LR10N–20 N=1–19 N/s). Digital image correlation revealed the possibility of a screw-like motion of the tooth into the PDL-space, i.e., predominant vertical displacement of 35 μm at 5 N, followed by a slight increase to 40 μm at 10 N and 50 μm at 20 N of the tooth and potential tooth rotation at loads above 10 N. Narrowed and widened PDL spaces as a result of tooth displacement indicated areas of increased apparent strain within the complex. We propose that such highly strained regions are “hot spots” that can potentiate local tissue adaptation under physiological loading and adverse tissue adaptation under pathological loading

A novel technique of intra-spinous process injection of PMMA to augment the strength of an inter-spinous process device such as the X STOP.

PubMed

Idler, Cary; Zucherman, James F; Yerby, Scott; Hsu, Ken Y; Hannibal, Matthew; Kondrashov, Dimitriy

2008-02-15

Biomechanical. To determine if cement injection into the spinous process will improve compression strength. The X STOP (St. Francis Medical Technologies) has been shown to be a safe and effective means for decompressing 1- or 2-level lumbar spinal stenosis (LSS). The X STOP is indicated for LSS patients with osteoporosis, but contraindicated for patients with severe osteoporosis. In an attempt to address these LSS patients with demonstrably weaker bone, a technique to strengthen the spinous process with polymethylmethacrylate (PMMA) injection is presented. Nine pairs of adjacent fresh frozen cadaveric lumbar vertebrae were DEXA scanned before testing. They were randomly assigned to the PMMA group and a control group. Nine of the specimens were injected with PMMA. Each spinous process was then compressed between 2 X STOPs. The testing model was designed to simulate the loading of a 2-level X STOP placement. The mean load to failure and stiffness values of the treated and untreated groups were calculated. The specimens were inspected carefully for PMMA infiltration and extrusion. The mean bone mineral density (BMD) values of the control and PMMA treatment groups were 0.99 +/- 0.13 g/cm and 0.98 +/- 0.10 g/cm, respectively; P > 0.616. The mean volume of cement injected was 2.2 +/- 0.3 cc. The mean failure load values of the control and PMMA treatment groups were 1250 +/- 627 N and 2386 +/- 1034 N, respectively; P < 0.001. The mean stiffness values of the control and PMMA treatment groups were 296 +/- 139 N/mm and 381 +/- 131 N/mm, respectively; P > 0.059. Most specimens had flow of the cement into the laminae and some into the facet and pedicle. No PMMA was found within the spinal canal. This first reported technique of posterior element vertebroplasty may increase the indications and success for patients with decreased BMD who seek an interspinous implant such as the X STOP. A possible role may exist in increasing the effectiveness of such devices. However, clinical

Subfailure injury of the rabbit anterior cruciate ligament.

PubMed

Panjabi, M M; Yoldas, E; Oxland, T R; Crisco, J J

1996-03-01

Ligamentous injuries range in severity from a simple sprain to a complete rupture. Although sprains occur more frequently than complete failures, only a few studies have investigated the phenomena of these subfailure injuries. The purpose of our study was to document the changes in the load-deformation curve until the failure point, after the ligament has been subjected to an 80% subfailure stretch. Thirteen paired fresh rabbit bone-anterior cruciate ligament-bone preparations were used. One of the pairs (control) was stretched until failure; the other (experimental) was first stretched to 80% of the failure deformation of the control and then stretched to failure. Comparisons were made between the load-deformation curves of the experimental and control specimens. The nonlinear load-deformation curves were characterized by eight parameters: failure load (Ffail), failure deformation (Dfail), energy until failure (Efail), deformations measured at 5, 10, 25, and 50% of the failure load (D5, D10, D25, and D50, respectively), and stiffness measured at 50% of the failure force (K50). There were no significant differences in the values for Ffail, Dfail, and Efail between the experimental and control ligaments (p > 0.33). In contrast, the deformation values were all larger for the experimental than the control ligaments (p > 0.01). The deformations D5, D10, D25, and D50 (mean +/- SD) for the control were 0.36 +/- 0.13, 0.49 +/- 0.23, 0.81 +/- 0.35, and 1.23 +/- 0.41 mm. The corresponding deformations for the experimental ligaments were, respectively, 209, 186, 153, and 130% of the control values. K50 was also greater for the experimental ligament (125.0 +/- 41.7 N/mm compared with 108.7 +/- 31.4 N/mm, p < 0.03). These findings indicate that even though the strength of the ligament did not change due to a subfailure injury, the shape of the load-displacement curve, especially at low loads, was significantly altered. Under the dynamic in vivo loading conditions of daily

Tensile and Torsional Structural Properties of the Native Scapholunate Ligament.

PubMed

Pang, Eric Quan; Douglass, Nathan; Behn, Anthony; Winterton, Matthew; Rainbow, Michael J; Kamal, Robin N

2018-02-17

The ideal material for reconstruction of the scapholunate interosseous ligament (SLIL) should replicate the mechanical properties of the native SLIL to recreate normal kinematics and prevent posttraumatic arthritis. The purpose of our study was to evaluate the cyclic torsional and tensile properties of the native SLIL and load to failure tensile properties of the dorsal SLIL. The SLIL bone complex was resected from 10 fresh-frozen cadavers. The scaphoid and lunate were secured in polymethylmethacrylate and mounted on a test machine that incorporated an x-y stage and universal joint, which permitted translations perpendicular to the rotation/pull axis as well as nonaxial angulations. After a 1 N preload, specimens underwent cyclic torsional testing (±0.45 N m flexion/extension at 0.5 Hz) and tensile testing (1-50 N at 1 Hz) for 500 cycles. Lastly, the dorsal 10 mm of the SLIL was isolated and displaced at 10 mm/min until failure. During intact SLIL cyclic torsional testing, the neutral zone was 29.7° ± 6.6° and the range of rotation 46.6° ± 7.1°. Stiffness in flexion and extension were 0.11 ± 0.02 and 0.12 ± 0.02 N m/deg, respectively. During cyclic tensile testing, the engagement length was 0.2 ± 0.1 mm, the mean stiffness was 276 ± 67 N/mm, and the range of displacement was 0.4 ± 0.1 mm. The dorsal SLIL displayed a 0.3 ± 0.2 mm engagement length, 240 ± 65 N/mm stiffness, peak load of 270 ± 91 N, and displacement at peak load of 1.8 ± 0.3 mm. We report the torsional properties of the SLIL. Our novel test setup allows for free rotation and translation, which reduces out-of-plane force application. This may explain our observation of greater dorsal SLIL load to failure than previous reports. By matching the natural ligament with respect to its tensile and torsional properties, we believe that reconstructions will better restore the natural kinematics of the wrist and lead to improved outcomes. Future clinical studies should aim to investigate this

A new methodological approach to assess cardiac work by pressure-volume and stress-length relations in patients with aortic valve stenosis and dilated cardiomyopathy.

PubMed

Alter, P; Rupp, H; Rominger, M B; Klose, K J; Maisch, B

2008-01-01

In experimental animals, cardiac work is derived from pressure-volume area and analyzed further using stress-length relations. Lack of methods for determining accurately myocardial mass has until now prevented the use of stress-length relations in patients. We hypothesized, therefore, that not only pressure-volume loops but also stress-length diagrams can be derived from cardiac volume and cardiac mass as assessed by cardiac magnetic resonance imaging (CMR) and invasively measured pressure. Left ventricular (LV) volume and myocardial mass were assessed in seven patients with aortic valve stenosis (AS), eight with dilated cardiomyopathy (DCM), and eight controls using electrocardiogram (ECG)-gated CMR. LV pressure was measured invasively. Pressure-volume curves were calculated based on ECG triggering. Stroke work was assessed as area within the pressure-volume loop. LV wall stress was calculated using a thick-wall sphere model. Similarly, stress-length loops were calculated to quantify stress-length-based work. Taking the LV geometry into account, the normalization with regard to ventricular circumference resulted in "myocardial work." Patients with AS (valve area 0.73+/-0.18 cm(2)) exhibited an increased LV myocardial mass when compared with controls (P<0.05). LV wall stress was increased in DCM but not in AS. Stroke work of AS was unchanged when compared with controls (0.539+/-0.272 vs 0.621+/-0.138 Nm, not significant), whereas DCM exhibited a significant depression (0.367+/-0.157 Nm, P<0.05). Myocardial work was significantly reduced in both AS and DCM when compared with controls (129.8+/-69.6, 200.6+/-80.1, 332.2+/-89.6 Nm/m(2), P<0.05), also after normalization (7.40+/-5.07, 6.27+/-3.20, 14.6+/-4.07 Nm/m(2), P<0.001). It is feasible to obtain LV pressure-volume and stress-length diagrams in patients based on the present novel methodological approach of using CMR and invasive pressure measurement. Myocardial work was reduced in patients with DCM and noteworthy

WRF Simulation over the Eastern Africa by use of Land Surface Initialization

NASA Astrophysics Data System (ADS)

Sakwa, V. N.; Case, J.; Limaye, A. S.; Zavodsky, B.; Kabuchanga, E. S.; Mungai, J.

2014-12-01

The East Africa region experiences severe weather events associated with hazards of varying magnitude. It receives heavy precipitation which leads to wide spread flooding and lack of sufficient rainfall in some parts results into drought. Cases of flooding and drought are two key forecasting challenges for the Kenya Meteorological Service (KMS). The source of heat and moisture depends on the state of the land surface which interacts with the boundary layer of the atmosphere to produce excessive precipitation or lack of it that leads to severe drought. The development and evolution of precipitation systems are affected by heat and moisture fluxes from the land surface within weakly-sheared environments, such as in the tropics and sub-tropics. These heat and moisture fluxes during the day can be strongly influenced by land cover, vegetation, and soil moisture content. Therefore, it is important to represent the land surface state as accurately as possible in numerical weather prediction models. Improved modeling capabilities within the region have the potential to enhance forecast guidance in support of daily operations and high-impact weather over East Africa. KMS currently runs a configuration of the Weather Research and Forecasting (WRF) model in real time to support its daily forecasting operations, invoking the Non-hydrostatic Mesoscale Model (NMM) dynamical core. They make use of the National Oceanic and Atmospheric Administration / National Weather Service Science and Training Resource Center's Environmental Modeling System (EMS) to manage and produce the WRF-NMM model runs on a 7-km regional grid over Eastern Africa.SPoRT and SERVIR provide land surface initialization datasets and model verification tool. The NASA Land Information System (LIS) provide real-time, daily soil initialization data in place of interpolated Global Forecast System soil moisture and temperature data. Model verification is done using the Model Evaluation Tools (MET) package, in order

Unraveling the polymetamorphic history of garnet-bearing metabasites: Insights from the North Motagua Mélange (Guatemala Suture Zone)

NASA Astrophysics Data System (ADS)

Bonnet, G.; Flores, K. E.; Martin, C.; Harlow, G. E.

2014-12-01

The Guatemala Suture Zone is the fault-bound region in central Guatemala that contains the present North American-Caribbean plate boundary. This major composite geotectonic unit contains a variety of ophiolites, serpentinite mélanges, and metavolcano-sedimentary sequences along with high-grade schists, gneisses, low-grade metasediments and metagranites thrusted north and south of the active Motagua fault system (MFS). The North Motagua Mélange (NMM) outcrops north of the MFS and testifies the emplacement of exhumed subduction assemblages along a collisional tectonic setting. The NMM is composed of a serpentinite-matrix mélange that contains blocks of metabasites (subgreenschist facies metabasalt, grt-blueschist, eclogite, grt-amphibolite), vein-related rocks (jadeitite, omphacitite, albitite, mica-rock), and metatrondhjemites. Our new detailed petrographic and thermobarometric study on the garnet-bearing metabasites reveals a complex polymetamorphic history with multiple tectonic events. Eclogites show a classical clockwise PT path composed of (a) prograde blueschist/eclogite facies within garnet cores, (b) eclogite facies metamorphic peak at ~1.7 GPa and 620°C, (c) post-peak blueschist facies, (d) amphibolite facies overprint, and (e) late stage greenschist facies. Two types of garnet amphibolite blocks can be found, the first consist of (a) a relict eclogite facies peak at ~1.3 GPa and 550°C only preserved within anhedral garnet cores, and (b) surrounded by a post-peak amphibolite facies. In contrast, the second type displays a prograde amphibolite facies at 0.6-1.1 GPa and 400-650°C. The eclogites metamorphic peak suggests formation in a normal subduction zone at ~60 km depth, a subsequent exhumation to the middle section of the subduction channel (~35 km), and a later metamorphic reworking at lower P and higher T before its final exhumation. The first type of garnet amphibolite shows a similar trajectory as the eclogites but at warmer conditions. In

The mechanical properties of brick containing recycled concrete aggregate and polyethylene terephthalate waste as sand replacement

NASA Astrophysics Data System (ADS)

Sheikh Khalid, Faisal; Bazilah Azmi, Nurul; Natasya Mazenan, Puteri; Shahidan, Shahiron; Ali, Noorwirdawati

2018-03-01

This research focuses on the performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate. This study aims to determine the mechanical properties such as compressive strength and water absorption of composite brick containing recycled concrete aggregate (RCA) and polyethylene terephthalate (PET) waste. The bricks specimens were prepared by using 100% natural sand, they were then replaced by RCA at 25%, 50% and 75% with proportions of PET consists of 0.5%, 1.0% and 1.5% by weight of natural sand. Based on the results of compressive strength, only RCA 25% with 0.5% PET achieve lower strength than normal bricks while others showed a high strength. However, all design mix reaches strength more than 7N/mm2 as expected. Besides that, the most favorable mix design that achieves high compressive strength is 75% of RCA with 0.5% PET.

Superconductivity in YTE2Ge2 compounds (TE = d-electron transition metal)

NASA Astrophysics Data System (ADS)

Chajewski, G.; Samsel-Czekała, M.; Hackemer, A.; Wiśniewski, P.; Pikul, A. P.; Kaczorowski, D.

2018-05-01

Polycrystalline samples of YTE2Ge2 with TE = Co, Ni, Ru, Rh, Pd and Pt were synthesized and characterized by means of X-ray powder diffraction and low-temperature electrical resistivity and specific heat measurements, supplemented by fully relativistic full-potential local-orbital band structure calculations. We confirm that most of the compounds studied crystallize in a body-centered tetragonal ThCr2S2 -type structure (space group I 4 / mmm) and have three-dimensional Fermi surfaces, while only one of them (YPt2Ge2) forms with a primitive tetragonal CaBe2Ge2 -type unit cell (space group P 4 / nmm) and possesses quasi-two-dimensional Fermi surface sheets with some nesting. Physical properties data show conventional superconductivity in the phases with TE = Co, Pd and Pt, i.e. independently of the structure type (and hence the dimensionality of the Fermi surface).

Pressure-induced superconductivity in the giant Rashba system BiTeI.

PubMed

VanGennep, D; Linscheid, A; Jackson, D E; Weir, S T; Vohra, Y K; Berger, H; Stewart, G R; Hennig, R G; Hirschfeld, P J; Hamlin, J J

2017-03-08

At ambient pressure, BiTeI exhibits a giant Rashba splitting of the bulk electronic bands. At low pressures, BiTeI undergoes a transition from trivial insulator to topological insulator. At still higher pressures, two structural transitions are known to occur. We have carried out a series of electrical resistivity and AC magnetic susceptibility measurements on BiTeI at pressure up to  ∼40 GPa in an effort to characterize the properties of the high-pressure phases. A previous calculation found that the high-pressure orthorhombic P4/nmm structure BiTeI is a metal. We find that this structure is superconducting with T c values as high as 6 K. AC magnetic susceptibility measurements support the bulk nature of the superconductivity. Using electronic structure and phonon calculations, we compute T c and find that our data is consistent with phonon-mediated superconductivity.

Genetic evidence for direct sensing of phenolic compounds by the VirA protein of Agrobacterium tumefaciens.

PubMed Central

Lee, Y W; Jin, S; Sim, W S; Nester, E W

1995-01-01

The virulence (vir) genes of Agrobacterium tumefaciens are induced by low-molecular-weight phenolic compounds and monosaccharides through a two-component regulatory system consisting of the VirA and VirG proteins. However, it is not clear how the phenolic compounds are sensed by the VirA/VirG system. We tested the vir-inducing abilities of 15 different phenolic compounds using four wild-type strains of A. tumefaciens--KU12, C58, A6, and Bo542. We analyzed the relationship between structures of the phenolic compounds and levels of vir gene expression in these strains. In strain KU12, vir genes were not induced by phenolic compounds containing 4'-hydroxy, 3'-methoxy, and 5'-methoxy groups, such as acetosyringone, which strongly induced vir genes of the other three strains. On the other hand, vir genes of strain KU12 were induced by phenolic compounds containing only a 4'-hydroxy group, such as 4-hydroxyacetophenone, which did not induce vir genes of the other three strains. The vir genes of strains KU12, A6, and Bo542 were all induced by phenolic compounds containing 4'-hydroxy and 3'-methoxy groups, such as acetovanillone. By transferring different Ti plasmids into isogenic chromosomal backgrounds, we showed that the phenolic-sensing determinant is associated with Ti plasmid. Subcloning of Ti plasmid indicates that the virA locus determines which phenolic compounds can function as vir gene inducers. These results suggest that the VirA protein directly senses the phenolic compounds for vir gene activation. PMID:8618878

New Intermetallic Ternary Phosphide Chalcogenide AP2-xXx (A = Zr, Hf; X = S, Se) Superconductors with PbFCl-Type Crystal Structure

NASA Astrophysics Data System (ADS)

Kitô, Hijiri; Yanagi, Yousuke; Ishida, Shigeyuki; Oka, Kunihiko; Gotoh, Yoshito; Fujihisa, Hiroshi; Yoshida, Yoshiyuki; Iyo, Akira; Eisaki, Hiroshi

2014-07-01

We have synthesized a series of intermetallic ternary phosphide chalcogenide superconductors, AP2-xXx (A = Zr, Hf; X = S, Se), using the high-pressure synthesis technique. These materials have a PbFCl-type crystal structure (space group P4/nmm) when x is greater than 0.3. The superconducting transition temperature Tc changes systematically with x, yielding dome-like phase diagrams. The maximum Tc is achieved at approximately x = 0.7, at which point the Tc is 6.3 K for ZrP2-xSex (x = 0.75), 5.5 K for HfP2-xSex (x = 0.7), 5.0 K for ZrP2-xSx (x = 0.675), and 4.6 K for Hfp2-xSx (x = 0.5). They are typical type-II superconductors and the upper and lower critical fields are estimated to be 2.92 T at 0 K and 0.021 T at 2 K for ZrP2-xSex (x = 0.75), respectively.

A novel pH-responsive interpolyelectrolyte hydrogel complex for the oral delivery of levodopa. Part II: characterization and formulation of an IPEC-based tablet matrix.

PubMed

Ngwuluka, Ndidi C; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Khan, Riaz A; Pillay, Viness

2015-03-01

This study was undertaken in order to apply a synthesized interpolyelectrolyte complex (IPEC) of polymethacrylate and carboxymethylcellulose as a controlled release oral tablet matrix for the delivery of the model neuroactive drug levodopa. The IPEC (synthesized in Part I of this work) was characterized by techniques such as Fourier Transform Infra-Red (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), Advanced DSC (ADSC), and Scanning Electron Microscopy (SEM). The tablet matrices were formulated and characterized for their drug delivery properties and in vitro drug release. FTIR confirmed the interaction between the two polymers. The IPEC composite generated tablet matrices with a hardness ranging from 19.152-27.590 N/mm and a matrix resilience ranging between 42 and 46%. An IPEC of polymethacrylate and carboxymethylcellulose was indeed an improvement on the inherent properties of the native polymers providing a biomaterial with the ability to release poorly soluble drugs such as levodopa at a constant rate over a prolonged period of time. © 2014 Wiley Periodicals, Inc.

The mechanical behavior of nanoscale metallic multilayers: A survey

NASA Astrophysics Data System (ADS)

Zhou, Q.; Xie, J. Y.; Wang, F.; Huang, P.; Xu, K. W.; Lu, T. J.

2015-06-01

The mechanical behavior of nanoscale metallic multilayers (NMMs) has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces existing in the NMMs dictates the unique behavior of this special class of structural composite materials. While there have been a number of reviews on the mechanical mechanism of microlaminates, the rapid development of nanotechnology brought a pressing need for an overview focusing exclusively on a property-based definition of the NMMs, especially their size-dependent microstructure and mechanical performance. This article attempts to provide a comprehensive and up-to-date review on the microstructure, mechanical property and plastic deformation physics of NMMs. We hope this review could accomplish two purposes: (1) introducing the basic concepts of scaling and dimensional analysis to scientists and engineers working on NMM systems, and (2) providing a better understanding of interface behavior and the exceptional qualities the interfaces in NMMs display at atomic scale.

Slow-light-enhanced energy efficiency for graphene microheaters on silicon photonic crystal waveguides

PubMed Central

Yan, Siqi; Zhu, Xiaolong; Frandsen, Lars Hagedorn; Xiao, Sanshui; Mortensen, N. Asger; Dong, Jianji; Ding, Yunhong

2017-01-01

Slow light has been widely utilized to obtain enhanced nonlinearities, enhanced spontaneous emissions and increased phase shifts owing to its ability to promote light–matter interactions. By incorporating a graphene on a slow-light silicon photonic crystal waveguide, here we experimentally demonstrate an energy-efficient graphene microheater with a tuning efficiency of 1.07 nmmW−1 and power consumption per free spectral range of 3.99 mW. The rise and decay times (10–90%) are only 750 and 525 ns, which, to the best of our knowledge, are the fastest reported response times for microheaters in silicon photonics. The corresponding figure of merit of the device is 2.543 nW s, one order of magnitude better than results reported in previous studies. The influence of the length and shape of the graphene heater to the tuning efficiency is further investigated, providing valuable guidelines for enhancing the tuning efficiency of the graphene microheater. PMID:28181531

Tuning the ground state of the Kondo lattice in UT Bi2 (T = Ag, Au) single crystals

NASA Astrophysics Data System (ADS)

Rosa, Priscila; Luo, Yongkang; Pagliuso, Pascoal; Bauer, Eric; Thompson, Joe; Fisk, Zachary

2015-03-01

Motivated by the interesting magnetic anisotropy found in the Ce-based heavy fermion family Ce TX2 (T = transition metal, X = pnictogen), here we study the novel U-based parent compounds U TBi2 (T = Ag, Au) by combining magnetization, electrical resistivity, and heat-capacity measurements. The single crystals, synthesized by the self-flux method, also crystallize in the tetragonal HfCuSi2-type structure (space group P4/nmm). Interestingly, although UAgBi2 is a low- γ antiferromagnet below TN = 181 K, UAuBi2 is a moderately heavy uniaxial ferromagnet below Tc = 22 K. Nevertheless, both compounds display the easy-magnetization direction along the c-axis and a large magnetocrystalline anisotropy. Our results point out to an incoherent Kondo behaviour in the paramagnetic state and an intricate competition between crystal field effects and two anisotropic exchange interactions, which lead to the remarkable difference in the observed ground states.

Site selectivity on chalcogen atoms in superconducting La(O,F)BiSSe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Masashi, E-mail: Tanaka.Masashi@nims.go.jp; Matsushita, Yoshitaka; Fujioka, Masaya

2015-03-16

Single crystals of La(O,F)BiSSe were grown by using a CsCl flux method. Single crystal X-ray structural analysis reveals that the crystal structure is isostructural to the BiS{sub 2}- or BiSe{sub 2}-based compounds crystallizing with space group P4/nmm (lattice parameters a = 4.1110(2) Å, c = 13.6010(7) Å). However, the S atoms are selectively occupied at the apical site of the Bi-SSe pyramids in the superconducting layer. The single crystals show a superconducting transition at around 4.2 K in the magnetic susceptibility and resistivity measurements. The superconducting anisotropic parameter is determined to be 34–35 from its upper critical magnetic field. The anisotropy is in the same range withmore » that of other members of the La(O,F)BiCh{sub 2} (Ch = S, Se) family under ambient pressure.« less

Mechanical evaluation of aluminum alloy ring fixator.

PubMed

Tosborvorn, Somboon; Cheechareon, Sukrom; Ruttanuchun, Kittiput; Sirivedin, Suparerk; Rhienumporn, Chaitawat

2006-11-01

To test the homemade ring fixator as a tool for correction of bony deformity. The authors developed an aluminum alloy ring fixator and tested it to find out the accuracy of manufacturing and strength of the ring systems under axial load with the Roundness Testing Machine and Lloyd Universal Testing Machine. The mean diameter of the twenty five-drill holes was 6.5843872 +/- 0.0521594 mm (mean +/- SD). Distance between particular drill holes, which reflected the precision of drilling, had a high accuracy with standard deviation from 0.1138 to 0.1870 mm. The roundness of the rings was 0.2421376 +/- 0.12437977 mm (mean +/- SD). The system structure had minimal permanent deformity at breaking point, mean yield strength of the system was 4786.9 +/- 14.353 N (mean +/- SD). This was caused by the failure of the wire. Mean stiffness of the system was 127 N./mm. The aluminum alloy ring fixator was strong enough and well tolerated for clinical usage

Pressure-induced superconductivity in the giant Rashba system BiTeI

DOE PAGES

VanGennep, D.; Linscheid, A.; Jackson, D. E.; ...

2017-01-27

We present that at ambient pressure, BiTeI exhibits a giant Rashba splitting of the bulk electronic bands. At low pressures, BiTeI undergoes a transition from trivial insulator to topological insulator. At still higher pressures, two structural transitions are known to occur. We have carried out a series of electrical resistivity and AC magnetic susceptibility measurements on BiTeI at pressure up to ~40 GPa in an effort to characterize the properties of the high-pressure phases. A previous calculation found that the high-pressure orthorhombic P4/nmm structure BiTeI is a metal. We find that this structure is superconducting with T c values asmore » high as 6 K. AC magnetic susceptibility measurements support the bulk nature of the superconductivity. Using electronic structure and phonon calculations, we compute T c and find that our data is consistent with phonon-mediated superconductivity.« less

DoD Manual for Standard Data Elements

DTIC Science & Technology

1989-07-01

U4W333Iininin0.0. -)-6-6)---6- Z.............Law0C 44-Lawu Inn44....Jým --- ...- ..... -LaWzaýa ZaW aW>u 0 wwJ 22-. - Lawammi nmm4mm m mm awmwwww w2Z...a a 0 ON wzwzn i 0... ta L--za tun w awawww 4 0 UL OOOOO&WO ~ a. 0- C9 w~a 44U - . = X Z~(n~nZZ4 4 0 44 uJ0 - 0.4- 4-4 &. L 0 Z0000U W b, ta atS w xu...Z -a CW 1 04 Il-w lWa-I- - * U.zU 4 000 2 4N00 ZaW --0-aU.Ji.0 4c 0 W W M- o-t M ma- 0a-s--~0U- ZIW 2 j P- 0W I-a >1(AO i 4 U00.4K 11a-I--I-- j~ at

Fabricaton of brick without burning process

NASA Astrophysics Data System (ADS)

Zultiniar; Fadli, A.; Yenti, S. R.; Drastinawati; Thariq, M. R. A.

2018-04-01

Brick is a material with many applications on building materials. The purpose of this research is to study the effect of fly ash addition and hardening time on mechanical properties of brick produced. Brick was formed by mixing cement, clay, water and fly ash with addition point was 0;0,3;0,6;0,9;1,2 kg weight. Brick was dried at room temperature for 7, 14 and 21 days. The result showed that compressive strength with addition 0,6 kg fly ash for 21 days was the the strongest where that’s value was 9,375 N/mm2. The highest porosity was get in on 21,34 % with 1,2 fly ash addition. The result of TCLP showed that for Pb, Cu, Cr content was still below the quality standards based on PP No.85 TH 1999 and still considered harmless. Leachate value for Pb of 3,10 mg/L, 1,213 mg/L for Cr and 4,374 mg/L for Cu.

[An epidemiological study of the distinct histological types of cutaneous melanoma in relation to other variables of the disease].

PubMed

Morales Suárez-Varela, M M; Llopis González, A; Lacasaña Navarro, M; Agudo Ferrándiz, J; Segarra Castelló, L

1992-03-01

A retrospective descriptive study is carried out from the whole of malignant cutaneous melanomas diagnosed at the Dermatology Service of the General University Hospital of Valencia (HGUV), during the period 1977-1987, in which the 80% of the whole of the cases in the province of Valencia are diagnosed, specifically 247 patients are studied. The ones located on the leg stand out 21%, followed by posterior thorax 14% and face 12%. Likewise, differences statistically significant p less than 0.001 are observed among the distinct histological types of cutaneous malignant melanoma (CMM) with regard to the depth of the tumours invasion (measured in Clark levels and millimetres of depth), mitosis/area, mitosis index and prognosis index. Being the lentigo of malignant melanoma (LMM) the histological type diagnosed in earlier phases, hence it is the most capable variant of curative treatment, just the opposite that happens to the nodular malignant melanoma (NMM), that is normally diagnosed in more advanced phases of the illness.

Microtensile bond strength of different acrylic teeth to high-impact denture base resins.

PubMed

Colebeck, Amanda C; Monaco, Edward A; Pusateri, Christopher R; Davis, Elaine L

2015-01-01

This study evaluated the effect of denture base acrylic, denture tooth composition, and ridge-lap surface treatment on the microtensile bond strength (μTBS) of three commercially available denture teeth and two injection denture processing systems. Sixteen experimental groups were formed (n = 3), according to denture tooth surface treatment (no treatment or surface treatment recommended by the manufacturer), denture base processing technique and acrylic (SR-Ivocap-Ivocap Plus or Success-Lucitone 199), and tooth type-composition at bonding interface (BlueLine DCL-PMMA, Portrait IPN-PMMA, Phonares II-PMMA, Phonares II-NHC). Rectangular bar specimens with a 1 mm(2) cross sectional area were fabricated and subsequently thermocycled at 10,000 cycles between 5°C and 55°C with a 15-second dwell time. Select specimens underwent μTBS testing in a universal testing machine with a 1 kN load cell at 0.5 mm/min crosshead speed. Data were analyzed statistically by two and three-way ANOVA and Tukey post hoc test (α = 0.05). Mean μTBS ranged between 56.2 ± 5.6 and 60.8 ± 5.0 N/mm(2) for the Ivocap Plus specimens and 13.3 ± 5.12 to 60.1 ± 6.0 N/mm(2) for the Lucitone 199 specimens. Among the Ivocap specimens, BlueLine DCL and Phonares II NHC had significantly higher μTBS than Portrait IPN to Ivocap Plus acrylic. There were no statistically significant differences among Blueline, Phonares II PMMA, and Phonares II NHC, or between Phonares II PMMA and Portrait IPN. Within the Luctione 199 specimens, there was a significantly higher μTBS for BlueLine DCL and Phonares II NHC denture teeth with the manufacturer-recommended surface treatment when compared to control surface. BlueLine, Portrait, and Phonares II PMMA groups achieved significantly higher mean μTBS than the Phonares II NHC group. There were no statistically significant differences among BlueLine, Portrait, and Phonares II PMMA groups. When evaluating the μTBS of PMMA and NHC denture teeth to base resins, a

Medial versus lateral supraspinatus tendon properties: implications for double-row rotator cuff repair.

PubMed

Wang, Vincent M; Wang, Fan Chia; McNickle, Allison G; Friel, Nicole A; Yanke, Adam B; Chubinskaya, Susan; Romeo, Anthony A; Verma, Nikhil N; Cole, Brian J

2010-12-01

Rotator cuff repair retear rates range from 25% to 90%, necessitating methods to improve repair strength. Although numerous laboratory studies have compared single-row with double-row fixation properties, little is known regarding regional (ie, medial vs lateral) suture retention properties in intact and torn tendons. A torn supraspinatus tendon will have reduced suture retention properties on the lateral aspect of the tendon compared with the more medial musculotendinous junction. Controlled laboratory study. Human supraspinatus tendons (torn and intact) were randomly assigned for suture retention mechanical testing, ultrastructural collagen fibril analysis, or histologic testing after suture pullout testing. For biomechanical evaluation, sutures were placed either at the musculotendinous junction (medial) or 10 mm from the free margin (lateral), and tendons were elongated to failure. Collagen fibril assessments were performed using transmission electron microscopy. Intact tendons showed no regional differences with respect to suture retention properties. In contrast, among torn tendons, the medial region exhibited significantly higher stiffness and work values relative to the lateral region. For the lateral region, work to 10-mm displacement (1592 ± 261 N-mm) and maximum load (265 ± 44 N) for intact tendons were significantly higher (P < .05) than that of torn tendons (1086 ± 388 N-mm and 177 ± 71 N, respectively). For medial suture placement, maximum load, stiffness, and work of intact and torn tendons were similar (P > .05). Regression analyses for the intact and torn groups revealed generally low correlations between donor age and the 3 biomechanical indices. For both intact and torn tendons, the mean fibril diameter and area density were greater in the medial region relative to the lateral (P ≤ .05). In the lateral tendon, but not the medial region, torn specimens showed a significantly lower fibril area fraction (48.3% ± 3.8%) than intact specimens

The influence of distal screw length on the primary stability of volar plate osteosynthesis--a biomechanical study.

PubMed

Baumbach, Sebastian F; Synek, Alexander; Traxler, Hannes; Mutschler, Wolf; Pahr, Dieter; Chevalier, Yan

2015-09-08

Extensor tendon irritation is one of the most common complications following volar locking plate osteosynthesis (VLPO) for distal radius fractures. It is most likely caused by distal screws protruding the dorsal cortex. Shorter distal screws could avoid this, yet the influence of distal screw length on the primary stability in VLPO is unknown. The aim of this study was to compare 75 to 100% distal screw lengths in VLPO. A biomechanical study was conducted on 11 paired fresh-frozen radii. HRpQCT scans were performed to assess bone mineral density (BMD) and bone mineral content (BMC). The specimens were randomized pair-wise into two groups: 100% (group A) and 75% (group B) unicortical distal screw lengths. A validated fracture model for extra-articular distal radius fractures (AO-23 A3) was used. Polyaxial volar locking plates were mounted, and distal screws was inserted using a drill guide block. For group A, the distal screw tips were intended to be flush or just short of the dorsal cortex. In group B, a target screw length of 75% was calculated. The specimens were tested to failure using a displacement-controlled axial compression test. Primary biomechanical stability was assessed by stiffness, elastic limit, and maximum force as well as with residual tilt, which quantified plastic deformation. Nine specimens were tested successfully. BMD and BMC did not differ between the two groups. The mean distal screw length of group A was 21.7 ± 2.6 mm (range: 16 to 26 mm), for group B 16.9 ± 1.9 mm (range: 12 to 20 mm). Distal screws in group B were on average 5.6 ± 0.9 mm (range: 3 to 7 mm) shorter than measured. No significant differences were found for stiffness (706 ± 103 N/mm vs. 660 ± 124 N/mm), elastic limit (177 ± 25 N vs. 167 ± 36 N), maximum force (493 ± 139 N vs. 471 ± 149 N), or residual tilt (7.3° ± 0.7° vs. 7.1° ± 1.3°). The 75% distal screw length in VLPO provides similar primary stability to 100

Knotted versus knotless suture bridge repair of the achilles tendon insertion: a biomechanical study.

PubMed

Cox, Joseph T; Shorten, Peter L; Gould, Gregory C; Markert, Ronald J; Barnett, Michael D; Laughlin, Richard T

2014-11-01

Surgical treatment of insertional Achilles tendinopathy often involves detachment and debridement of the Achilles tendon insertion. A recent study has shown that knotted suture bridge fixation of the Achilles to the calcaneus is biomechanically superior to single-row fixation, but there is an absence of literature on the use of different suture bridge constructs to repair the Achilles tendon. There will be no significant difference in the load to failure, mode of failure, tendon strain, tendon stiffness, repair site gapping, or footprint size when comparing knotted suture bridge repair to knotless suture bridge repair of the Achilles tendon after detachment for insertional Achilles tendinopathy. Controlled laboratory study. A single specimen from each pair of 10 cadaveric Achilles tendons was randomized to 1 of 2 Achilles insertion repair groups: knotted (n = 10) or knotless (n = 10) suture bridge repair. Repaired footprint size was measured, and then cyclic testing from 10 to 100 N for 2000 cycles was performed. This was followed by measurement of tendon strain, repair site displacement, load to failure, and tendon stiffness. The knotted suture bridge repair had a significantly higher load to failure compared with the knotless suture bridge (mean ± SD, 317.8 ± 93.6 N vs 196.1 ± 12.1 N, respectively; P = .001). All constructs failed at the tendon-suture interface. Tendon strain after cyclic testing was significantly greater in the knotless (1.20 ± 1.05) compared with the knotted (0.39 ± 0.4) suture repair groups (P = .011). There was no significant difference in footprint size between the knotted (230.3 ± 63.3 mm(2)) and knotless (248.5 ± 48.8 mm(2)) groups (P = .40). There was also no significant difference in stiffness (knotted = 76.4 ± 8.0 N/mm; knotless = 69.6 ± 10.9 N/mm; P = .17) and repair site displacement after cyclic testing (knotted = 2.8 ± 1.2 mm; knotless = 3.6 ± 1.1 mm; P = .17). During suture bridge repair of the Achilles tendon after

Accelerating Dust Storm Simulation by Balancing Task Allocation in Parallel Computing Environment

NASA Astrophysics Data System (ADS)

Gui, Z.; Yang, C.; XIA, J.; Huang, Q.; YU, M.

2013-12-01

Dust storm has serious negative impacts on environment, human health, and assets. The continuing global climate change has increased the frequency and intensity of dust storm in the past decades. To better understand and predict the distribution, intensity and structure of dust storm, a series of dust storm models have been developed, such as Dust Regional Atmospheric Model (DREAM), the NMM meteorological module (NMM-dust) and Chinese Unified Atmospheric Chemistry Environment for Dust (CUACE/Dust). The developments and applications of these models have contributed significantly to both scientific research and our daily life. However, dust storm simulation is a data and computing intensive process. Normally, a simulation for a single dust storm event may take several days or hours to run. It seriously impacts the timeliness of prediction and potential applications. To speed up the process, high performance computing is widely adopted. By partitioning a large study area into small subdomains according to their geographic location and executing them on different computing nodes in a parallel fashion, the computing performance can be significantly improved. Since spatiotemporal correlations exist in the geophysical process of dust storm simulation, each subdomain allocated to a node need to communicate with other geographically adjacent subdomains to exchange data. Inappropriate allocations may introduce imbalance task loads and unnecessary communications among computing nodes. Therefore, task allocation method is the key factor, which may impact the feasibility of the paralleling. The allocation algorithm needs to carefully leverage the computing cost and communication cost for each computing node to minimize total execution time and reduce overall communication cost for the entire system. This presentation introduces two algorithms for such allocation and compares them with evenly distributed allocation method. Specifically, 1) In order to get optimized solutions, a

Biomechanical Testing of a 3-Hole versus a 4-Hole Sliding Hip Screw in the presence of a Retrograde Intramedullary Nail for Ipsilateral Intertrochanteric and Femur Shaft Fractures.

PubMed

Olsen, Michael; Goshulak, Peter; Crookshank, Meghan C; Moktar, Joel; Brazda, Ignace J; Schemitsch, Emil H; Zdero, Radovan

2018-04-03

The goal of this study was to compare a 3-hole vs. a 4-hole sliding hip screw (SHS) in the presence of a retrograde intramedullary (RIM) nail for fixing intertrochanteric and comminuted midshaft femur fractures. Mechanical tests were performed on 10 matched pairs of human cadaveric femurs that were osteotomized and then fixed using a 3-hole SHS vs. the traditional "gold standard" 4-hole SHS in the presence of a RIM nail. Data showed no differences between the 3-hole SHS with RIM nail vs. 4-hole SHS with RIM nail for stiffness (281 +/- 127 vs. 260 +/- 118 N/mm, p=0.76), clinical failure at 10 mm of hip displacement (2014 +/- 363 vs. 2134 +/- 614 N, p=0.52), or ultimate mechanical failure (3476 +/- 776 vs. 3669 +/- 755 N, p=0.12). For this fracture pattern, a 3-hole SHS with RIM nail may be a suitable surgical alternative to the traditional "gold standard" method, since it provides the same biomechanical properties while potentially reducing surgical time, blood loss, and hardware used. Level III biomechanical study.

DEVELOPMENT OF A CALCIUM-BASED SORBENT FOR HOT GAS CLEANUP

DOE Office of Scientific and Technical Information (OSTI.GOV)

T.D. Wheelock; L.K. Doraiswamy; K. Constant

1999-10-01

The development and testing of potential calcium-based sorbents for hot gas cleanup continued. One of the most promising materials combines powdered limestone and a calcium aluminate cement by two step pelletization followed by steam curing. Reasonably strong pellets are produced with good adsorption characteristics by incorporating 20 wt.% cement in the core and 40 wt.% cement in the shell. The resulting 4.76 mm diameter pellets are capable of withstanding a crushing force approaching 11.5 N/mm before breaking and are also capable of removing H{sub 2}S from dilute, hot gas streams. The pellets are also regenerable and reusable. Another promising materialmore » combines calcium carbonate powder and finely ground calcined alumina in tablet form. The small tablets are prepared by mixing the materials with water to form a thick paste which is then molded and dried. The tablets are hardened by calcining at either 1000 to 1100 C. The resulting tablets are strong and capable of removing H{sub 2}S from a dilute, hot gas stream.« less

Weather Research and Forecasting Model Wind Sensitivity Study at Edwards Air Force Base, CA

NASA Technical Reports Server (NTRS)

Watson, Leela R.; Bauman, William H., III; Hoeth, Brian

2009-01-01

This abstract describes work that will be done by the Applied Meteorology Unit (AMU) in assessing the success of different model configurations in predicting "wind cycling" cases at Edwards Air Force Base, CA (EAFB), in which the wind speeds and directions oscillate among towers near the EAFB runway. The Weather Research and Forecasting (WRF) model allows users to choose among two dynamical cores - the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM). There are also data assimilation analysis packages available for the initialization of the WRF model - the Local Analysis and Prediction System (LAPS) and the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS). Having a series of initialization options and WRF cores, as well as many options within each core, creates challenges for local forecasters, such as determining which configuration options are best to address specific forecast concerns. The goal of this project is to assess the different configurations available and determine which configuration will best predict surface wind speed and direction at EAFB.

Identification and properties of the non-cubic phases of Mg 2Pb

DOE PAGES

Li, Yuwei; Bian, Guang; Singh, David J.

2016-12-20

Mg 2Pb occurs in the cubic fluorite structure and is a semimetal with a band structure strongly affected by spin-orbit interaction on the Pb p states. Its properties are therefore of interest in the context of topological materials. In addition a different phase of Mg 2Pb was experimentally reported, but its crystal structure and properties remain unknown. Here we determine the structure of this phase using ab initio evolutionary methods and report its properties. The energy of one tetragonal phase, space group P4/ nmm, is 2 meV per atom higher than that of the ground state structure supporting the experimentalmore » observation. We find this tetragonal phase to be a compenstated anisotropic metal with strong spin orbit effects. As a result, many other metastable structures have also been identified, especially one orthorhombic structure, space group Pnma, of which energy is 17 meV per atom higher than that of ground state structure and which perhaps could be the phase that was reported based on similarity of lattice parameters.« less

The magnetic structure of EuCu 2Sb 2

DOE PAGES

Ryan, D. H.; Cadogan, J. M.; Anand, V. K.; ...

2015-05-06

Antiferromagnetic ordering of EuCu 2Sb 2 which forms in the tetragonal CaBe 2Ge 2-type structure (space group P4/nmm #129) has been studied using neutron powder diffraction and 151Eu Mössbauer spectroscopy. The room temperature 151Eu isomer shift of –12.8(1) mm/s shows the Eu to be divalent, while the 151Eu hyperfine magnetic field (B hf) reaches 28.7(2) T at 2.1 K, indicating a full Eu 2+ magnetic moment. B hf(T) follows a smoothmore » $$S=\\frac{7}{2}$$ Brillouin function and yields an ordering temperature of 5.1(1) K. Refinement of the neutron diffraction data reveals a collinear A-type antiferromagnetic arrangement with the Eu moments perpendicular to the tetragonal c-axis. As a result, the refined Eu magnetic moment at 0.4 K is 7.08(15) μ B which is the full free-ion moment expected for the Eu 2+ ion with $$S=\\frac{7}{2}$$ and a spectroscopic splitting factor of g = 2.« less

Effect of gamma radiation on the physico-chemical properties of alginate-based films and beads

NASA Astrophysics Data System (ADS)

Huq, Tanzina; Khan, Avik; Dussault, Dominic; Salmieri, Stephane; Khan, Ruhul A.; Lacroix, Monique

2012-08-01

Alginate solution (3%, w/v) was prepared using deionized water from its powder. Then the solution was exposed to gamma radiation (0.1-25 kGy). The alginate films were prepared by solution casting. It was found that gamma radiation has strong effect on alginate solution. At low doses, mechanical strength of the alginate films improved but after 5 kGy dose, the strength started to decrease. The mechanism of alginate radiolysis in aqueous solution is discussed. Film formation was not possible from alginate solution at doses >5 kGy. The mechanical properties such as puncture strength (PS), puncture deformation (PD), viscoelasticity (Y) coefficient of the un-irradiated films were investigated. The values of PS, PD and Y coefficient of the films were 333 N/mm, 3.20 mm and 27%, respectively. Alginate beads were prepared from 3% alginate solution (w/v) by ionotropic gelation method in 5% CaCl2 solution. The rate of gel swelling improved in irradiated alginate-based beads at low doses (up to 0.5 kGy).

Bonding strength of alkyl-2-cyanoacrylates to bone in vitro.

PubMed

Kilpikari, J; Lapinsuo, M; Törmälä, P; Pätiälä, H; Rokkanen, P

1986-10-01

This study measured the bonding strength between alkyl-2-cyanoacrylates and bone, and examined how treatment of the bone surface with acid, and prolonged exposure to moisture, affected this strength. The initial strength of all cyanoacrylates was high (9.6-11.2 N/mm2). In long-term experiments under water, n- and i-butylcyanoacrylates lost their strength at a far slower rate than ethylcyanoacrylates. However, the butylcyanoacrylates also showed a decrease of 15% in strength after three weeks. Pretreatment of the bone surface with acid did not have a marked effect on bonding strength, although SEM investigation revealed that the acid treatment had increased the porosity of the bone surface. A study of the fracture surface proved that the adhesive film tended to loosen or break after 3 to 6 weeks under water. The decrease in the bonding strength was probably due to the degradation of the adhesive film in water which loosened mechanical bonds between the bone and adhesive. Considering clinical use it would be necessary to achieve better long-term strength.

Studying the Hydration of a Retarded Suspension of Ground Granulated Blast-Furnace Slag after Reactivation

PubMed Central

Schneider, Nick; Stephan, Dietmar

2016-01-01

This article presents a combined use of a retarder (d-gluconic acid) and an alkaline activator (sodium hydroxide) in a binder system based on ground granulated blast-furnace slag. The properties of the retarder are extending the dormant hydration period and suppressing the generation of strength-giving phases. Different retarder concentrations between 0.25 and 1.00 wt.% regulate the intensity and the period of the retardation and also the characteristics of the strength development. The activator concentration of 30 and 50 wt.% regulates the overcoming of the dormant period and thereby the solution of the slag and hence the formation of the hydration products. The research objective is to produce a mineral binder system based on two separate liquid components. The highest concentration of retarder and activator generates the highest compressive strength and mass of hydration products—after 90 days of hydration a compressive strength of more than 50 N/mm2. The main phases are calcium silicate hydrate and hydrotalcite. Generally, the combination of retarder and activator shows a high potential in the performance increase of the hydration process. PMID:28774054

Sensitivity of biomechanical outcomes to independent variations of hindfoot and forefoot stiffness in foot prostheses.

PubMed

Adamczyk, Peter Gabriel; Roland, Michelle; Hahn, Michael E

2017-08-01

Many studies have reported the effects of different foot prostheses on gait, but most results cannot be generalized because the prostheses' properties are seldom reported. We varied hindfoot and forefoot stiffness in an experimental foot prosthesis, in increments of 15N/mm, and tested the parametric effects of these variations on treadmill walking in unilateral transtibial amputees, at speeds from 0.7 to 1.5m/s. We computed outcomes such as prosthesis energy return, center of mass (COM) mechanics, ground reaction forces, and joint mechanics, and computed their sensitivity to component stiffness. A stiffer hindfoot led to reduced prosthesis energy return, increased ground reaction force (GRF) loading rate, and greater stance-phase knee flexion and knee extensor moment. A stiffer forefoot resulted in reduced prosthetic-side ankle push-off and COM push-off work, and increased knee extension and knee flexor moment in late stance. The sensitivity parameters obtained from these tests may be useful in clinical prescription and further research into compensatory mechanisms of joint function. Copyright © 2017 Elsevier B.V. All rights reserved.

Nonlinear quasi-static finite element simulations predict in vitro strength of human proximal femora assessed in a dynamic sideways fall setup.

PubMed

Varga, Peter; Schwiedrzik, Jakob; Zysset, Philippe K; Fliri-Hofmann, Ladina; Widmer, Daniel; Gueorguiev, Boyko; Blauth, Michael; Windolf, Markus

2016-04-01

Osteoporotic proximal femur fractures are caused by low energy trauma, typically when falling on the hip from standing height. Finite element simulations, widely used to predict the fracture load of femora in fall, usually include neither mass-related inertial effects, nor the viscous part of bone׳s material behavior. The aim of this study was to elucidate if quasi-static non-linear homogenized finite element analyses can predict in vitro mechanical properties of proximal femora assessed in dynamic drop tower experiments. The case-specific numerical models of 13 femora predicted the strength (R(2)=0.84, SEE=540N, 16.2%), stiffness (R(2)=0.82, SEE=233N/mm, 18.0%) and fracture energy (R(2)=0.72, SEE=3.85J, 39.6%); and provided fair qualitative matches with the fracture patterns. The influence of material anisotropy was negligible for all predictions. These results suggest that quasi-static homogenized finite element analysis may be used to predict mechanical properties of proximal femora in the dynamic sideways fall situation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Artificial muscles made of chiral two-way shape memory polymer fibers

NASA Astrophysics Data System (ADS)

Yang, Qianxi; Fan, Jizhou; Li, Guoqiang

2016-10-01

In this work, we demonstrate the unusual improvement of the tensile actuation of hierarchically chiral structured artificial muscle made of two-way shape memory polymer (2W-SMP) fiber. Experimental results show that the chemically cross-linked poly(ethylene-co-vinyl acetate) 2W-SMP fibers possess an average negative coefficient of thermal expansion (NCTE) that is at least one order higher than that of the polyethylene fiber used previously. As expected, the increase in axial thermal contraction of the precursor fiber leads to an increase in the recovered torque ( 4.4 Nmm ) of the chiral fiber and eventually in the tensile actuation of the twisted-then-coiled artificial muscle ( 67.81 ±1.82 % ). A mechanical model based on Castigliano's second theorem is proposed, and the calculated result is consistent with the experimental result (64.17% tensile stroke). The model proves the significance of the NCTE and the recovered torque on tensile actuation of the artificial muscle and can be used as a guidance for the future design.

Two studies evaluating the safety and immunogenicity of a live, attenuated Shigella flexneri 2a vaccine (SC602) and excretion of vaccine organisms in North American volunteers.

PubMed

Katz, David E; Coster, Trinka S; Wolf, Marcia K; Trespalacios, Fernando C; Cohen, Dani; Robins, Guy; Hartman, Antoinette B; Venkatesan, Malabi M; Taylor, David N; Hale, Thomas L

2004-02-01

We report the first community-based evaluation of Shigella flexneri 2a strain SC602, a live, oral vaccine strain attenuated by deletion of the icsA (virG) plasmid virulence gene, given at 10(4) CFU. The primary objectives of this trial were to determine the safety and immunogenicity of the vaccine and to determine the duration of colonization. Four of 34 volunteers experienced transient fevers, and three reported diarrhea during the first 3 days of the study. Half of the volunteers mounted a positive serum immunoglobulin A (IgA) response to S. flexneri lipopolysaccharide. All but one of the volunteers excreted the vaccine in their stools for 1 to 33 days, and this excretion was often intermittent. Data from the community-based study were supplemented with an inpatient trial in which three volunteers received 10(3) and nine received 10(4) CFU. All volunteers who received 10(3) CFU excreted SC602 and had an IgA antibody-secreting cell response. Two of these had a serum IgA response. Six of the nine volunteers who received 10(4) CFU excreted SC602. One vaccinee had a transient fever and two met the definition of diarrhea. Six volunteers that received 10(4) CFU had an antibody-secreting cell response, and four had a serum IgA response. SC602 has now been tested at 10(4) CFU in a total of 58 volunteers. The cumulative results of these clinical trials, reported here and previously (Coster et al., Infect. Immun. 67:3437-3443, 1999), have demonstrated that SC602 is a substantially attenuated candidate vaccine that can evoke protection against the most severe symptoms of shigellosis in a stringent human challenge model of disease.

Synthesis, structure and optical properties of two isotypic crystals, Na{sub 3}MO{sub 4}Cl (M=W, Mo)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Shujuan; Bai, Chunyan; Zhang, Bingbing

Two isotypic compounds, Na{sub 3}MO{sub 4}Cl (M = W, Mo) have been obtained from the high temperature solution, and their structures were determined by single-crystal X-ray diffraction. Both of them crystallize in the space group P4/nmm of tetragonal system with the unit cells: a=7.5181(15), c=5.360(2) for Na{sub 3}WO{sub 4}Cl and a=7.4942(12), c=5.3409(18) for Na{sub 3}MoO{sub 4}Cl. The structure exhibits a 3D network built up by the ClNa{sub 6} groups, and the MO{sub 4} groups reside in the tunnels of the 3D network. The structural similarities and differences between Na{sub 3}MO{sub 4}Cl (M=W, Mo) and Sr{sub 3}MO{sub 4}F (M=Al, Ga) havemore » been discussed. Meanwhile, detailed structure comparison analyses between Na{sub 3}MO{sub 4}Cl (M=W, Mo) and Na{sub 3}MO{sub 4}F (M=W, Mo) indicate that the different connection modes of ClNa{sub 6} and FNa{sub 6} make Na{sub 3}MO{sub 4}Cl and Na{sub 3}MO{sub 4}F crystallize in different structures. The IR spectra were used to verify the validity of the structure. The diffuse reflectance spectra show that the UV absorption edges are about 249 nm (4.99 eV) and 265 nm (4.69 eV) for Na{sub 3}WO{sub 4}Cl and Na{sub 3}MoO{sub 4}Cl, respectively. In addition, the first-principles theoretical studies are also carried out to aid the understanding of electronic structures and linear optical properties. - Graphical abstract: Two isotypic compounds, Na{sub 3}MO{sub 4}Cl (M=W, Mo) have been obtained from the high temperature solution. Both of them crystallize in the space group P4/nmm of tetragonal system. The structure exhibits a 3D network built up by the ClNa{sub 6} groups, and the MO{sub 4} groups reside in the tunnels of the 3D network. - Highlights: • Structure and properties of Na{sub 3}MO{sub 4}Cl (M=W, Mo) are reported for the first time. • They show a 3D network built by ClNa{sub 6}, and WO{sub 4} lies in the tunnels of the network. • IR spectra were used to verify the validity of the structure. • Band structures

Surface Modification with Chemically Modified Synovial Fluid for Flexor Tendon Reconstruction in a Canine Model in Vivo

PubMed Central

Ji, Xiaoxi; Reisdorf, Ramona L.; Thoreson, Andrew R.; Berglund, Lawrence R.; Moran, Steven L.; Jay, Gregory D.; An, Kai-Nan; Amadio, Peter C.; Zhao, Chunfeng

2015-01-01

Background: Functional restoration is the major concern after flexor tendon reconstruction in the hand. The purpose of the present study was to investigate the effects of modifying the surface of extrasynovial tendon autografts with carbodiimide-derivatized synovial fluid with gelatin (cd-SF-G) on functional outcomes of flexor tendon reconstruction using a canine model. Methods: The second and fifth flexor digitorum profundus tendons from eleven dogs were transected and repaired in zone II. The dogs then had six weeks of free activity leading to tendon rupture and scar formation (the repair-failure phase). In the reconstruction phase, two autologous peroneus longus tendons from each dog were harvested; one tendon was coated with cd-SF-G and the other, with saline solution, as a control. A non-weight-bearing rehabilitation protocol was followed for six weeks after reconstruction. The digits were then harvested and evaluations of function, adhesion status, gliding resistance, attachment strength, cell viability, and histology were performed. Results: The tendons coated with cd-SF-G demonstrated significantly lower values (mean and standard deviation) compared with the saline-solution group for work of flexion (0.63 ± 0.24 versus 1.34 ± 0.42 N-mm/deg), adhesion score (3.5 ± 1.6 versus 6.1 ± 1.3), proximal adhesion breaking force (8.6 ± 3.2 versus 20.2 ± 10.2 N), and gliding resistance (0.26 ± 0.08 versus 0.46 ± 0.22 N) (p < 0.05). There was no significant difference between the cd-SF-G and saline-solution groups (p > 0.05) in distal attachment-site strength (56.9 ± 28.4 versus 77.2 ± 36.2 N), stiffness (19 ± 7.5 versus 24.5 ± 14.5 N/mm), and compressive modulus from indentation testing (4.37 ± 1.26 versus 3.98 ± 1.24 N/mm). Histological analysis showed that tendons coated with cd-SF-G had smoother surfaces and demonstrated tendon-to-bone and tendon-to-tendon incorporation. No significant difference in viable cell count between the two groups was observed

Toward Improved Land Surface Initialization in Support of Regional WRF Forecasts at the Kenya Meteorological Department

NASA Technical Reports Server (NTRS)

Case. Jonathan; Mungai, John; Sakwa, Vincent; Kabuchanga, Eric; Zavodsky, Bradley T.; Limaye, Ashutosh S.

2014-01-01

Flooding and drought are two key forecasting challenges for the Kenya Meteorological Department (KMD). Atmospheric processes leading to excessive precipitation and/or prolonged drought can be quite sensitive to the state of the land surface, which interacts with the boundary layer of the atmosphere providing a source of heat and moisture. The development and evolution of precipitation systems are affected by heat and moisture fluxes from the land surface within weakly-sheared environments, such as in the tropics and sub-tropics. These heat and moisture fluxes during the day can be strongly influenced by land cover, vegetation, and soil moisture content. Therefore, it is important to represent the land surface state as accurately as possible in numerical weather prediction models. Enhanced regional modeling capabilities have the potential to improve forecast guidance in support of daily operations and high-end events over east Africa. KMD currently runs a configuration of the Weather Research and Forecasting (WRF) model in real time to support its daily forecasting operations, invoking the Nonhydrostatic Mesoscale Model (NMM) dynamical core. They make use of the National Oceanic and Atmospheric Administration / National Weather Service Science and Training Resource Center's Environmental Modeling System (EMS) to manage and produce the WRF-NMM model runs on a 7-km regional grid over eastern Africa. Two organizations at the National Aeronautics and Space Administration Marshall Space Flight Center in Huntsville, AL, SERVIR and the Short-term Prediction Research and Transition (SPoRT) Center, have established a working partnership with KMD for enhancing its regional modeling capabilities. To accomplish this goal, SPoRT and SERVIR will provide experimental land surface initialization datasets and model verification capabilities to KMD. To produce a land-surface initialization more consistent with the resolution of the KMD-WRF runs, the NASA Land Information System (LIS

Synthesis and characterization of FeSe1-xTex (x=0, 0.5, 1) superconductors

NASA Astrophysics Data System (ADS)

Zargar, Rayees A.; Hafiz, A. K.; Awana, V. P. S.

2015-08-01

In this study, FeTe1-xSex (x=0,0.5,1) samples were prepared by conventional solid state reaction method and investigated by powder XRD, SEM, Raman and resistivity measurement techniques to reveal the effect of tellurium (Te) substitution in FeSe matrix. Rietveld analysis was performed on room temperature recorded, X-ray diffraction (XRD) patterns of pure FeSe, FeTe and FeSe0.5Te0.5 which shows that all the compounds are crystallized in a tetragonal structure. SEM images show the dense surface morphology. Raman spectra recorded in the range from 100 to 700 cm-1 at ambient temperature has been interpreted by P4/nmm space group of the lattice. The variation in intensity and shift in peak positions of some phonon modes has been discussed on the basis of variation in crystalline field effect by substituting Te in FeSe lattice. The resistivity versus temperature curves reveals that FeSe becomes superconductor at 7 K and FeSe0.5Te0.5 shows superconductivity below 14 K while FeTe is non-superconducting compound.

Optimizing zonal advection of the Advanced Research WRF (ARW) dynamics for Intel MIC

NASA Astrophysics Data System (ADS)

Mielikainen, Jarno; Huang, Bormin; Huang, Allen H.

2014-10-01

The Weather Research and Forecast (WRF) model is the most widely used community weather forecast and research model in the world. There are two distinct varieties of WRF. The Advanced Research WRF (ARW) is an experimental, advanced research version featuring very high resolution. The WRF Nonhydrostatic Mesoscale Model (WRF-NMM) has been designed for forecasting operations. WRF consists of dynamics code and several physics modules. The WRF-ARW core is based on an Eulerian solver for the fully compressible nonhydrostatic equations. In the paper, we will use Intel Intel Many Integrated Core (MIC) architecture to substantially increase the performance of a zonal advection subroutine for optimization. It is of the most time consuming routines in the ARW dynamics core. Advection advances the explicit perturbation horizontal momentum equations by adding in the large-timestep tendency along with the small timestep pressure gradient tendency. We will describe the challenges we met during the development of a high-speed dynamics code subroutine for MIC architecture. Furthermore, lessons learned from the code optimization process will be discussed. The results show that the optimizations improved performance of the original code on Xeon Phi 5110P by a factor of 2.4x.

Optimizing meridional advection of the Advanced Research WRF (ARW) dynamics for Intel Xeon Phi coprocessor

NASA Astrophysics Data System (ADS)

Mielikainen, Jarno; Huang, Bormin; Huang, Allen H.-L.

2015-05-01

The most widely used community weather forecast and research model in the world is the Weather Research and Forecast (WRF) model. Two distinct varieties of WRF exist. The one we are interested is the Advanced Research WRF (ARW) is an experimental, advanced research version featuring very high resolution. The WRF Nonhydrostatic Mesoscale Model (WRF-NMM) has been designed for forecasting operations. WRF consists of dynamics code and several physics modules. The WRF-ARW core is based on an Eulerian solver for the fully compressible nonhydrostatic equations. In the paper, we optimize a meridional (north-south direction) advection subroutine for Intel Xeon Phi coprocessor. Advection is of the most time consuming routines in the ARW dynamics core. It advances the explicit perturbation horizontal momentum equations by adding in the large-timestep tendency along with the small timestep pressure gradient tendency. We will describe the challenges we met during the development of a high-speed dynamics code subroutine for MIC architecture. Furthermore, lessons learned from the code optimization process will be discussed. The results show that the optimizations improved performance of the original code on Xeon Phi 7120P by a factor of 1.2x.

Synthesis, Crystal Structure, and Physical Properties of New Layered Oxychalcogenide La2O2Bi3AgS6

NASA Astrophysics Data System (ADS)

Hijikata, Yudai; Abe, Tomohiro; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Goto, Yosuke; Miura, Akira; Tadanaga, Kiyoharu; Wang, Yongming; Miura, Osuke; Mizuguchi, Yoshikazu

2017-12-01

We have synthesized a new layered oxychalcogenide La2O2Bi3AgS6. From synchrotron X-ray diffraction and Rietveld refinement, the crystal structure of La2O2Bi3AgS6 was refined using a model of the P4/nmm space group with a = 4.0644(1) Å and c = 19.412(1) Å, which is similar to the related compound LaOBiPbS3, while the interlayer bonds (M2-S1 bonds) are apparently shorter in La2O2Bi3AgS6. The tunneling electron microscopy (TEM) image confirmed the lattice constant derived from Rietveld refinement (c ˜ 20 Å). The electrical resistivity and Seebeck coefficient suggested that the electronic states of La2O2Bi3AgS6 are more metallic than those of LaOBiS2 and LaOBiPbS3. The insertion of a rock-salt-type chalcogenide into the van der Waals gap of BiS2-based layered compounds, such as LaOBiS2, will be a useful strategy for designing new layered functional materials in the layered chalcogenide family.

Thermoelectric Coolers with Sintered Silver Interconnects

NASA Astrophysics Data System (ADS)

Kähler, Julian; Stranz, Andrej; Waag, Andreas; Peiner, Erwin

2014-06-01

The fabrication and performance of a sintered Peltier cooler (SPC) based on bismuth telluride with sintered silver interconnects are described. Miniature SPC modules with a footprint of 20 mm2 were assembled using pick-and-place pressure-assisted silver sintering at low pressure (5.5 N/mm2) and moderate temperature (250°C to 270°C). A modified flip-chip bonder combined with screen/stencil printing for paste transfer was used for the pick-and-place process, enabling high positioning accuracy, easy handling of the tiny bismuth telluride pellets, and immediate visual process control. A specific contact resistance of (1.4 ± 0.1) × 10-5 Ω cm2 was found, which is in the range of values reported for high-temperature solder interconnects of bismuth telluride pellets. The realized SPCs were evaluated from room temperature to 300°C, considerably outperforming the operating temperature range of standard commercial Peltier coolers. Temperature cycling capability was investigated from 100°C to 235°C over more than 200 h, i.e., 850 cycles, during which no degradation of module resistance or cooling performance occurred.

Simultaneous measurement of pressure evolution of crystal structure and superconductivity in FeSe[subscript 0.92] using designer diamonds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uhoya, Walter; Tsoi, Georgiy; Vohra, Yogesh

Simultaneous high-pressure X-ray diffraction and electrical resistance measurements have been carried out on a PbO-type {alpha}-FeSe{sub 0.92} compound to a pressure of 44 GPa and temperatures down to 4 K using designer diamond anvils at synchrotron source. A ambient temperature, a structural phase transition from a tetragonal (P4/nmm) phase to an orthorhombic (Pbnm) phase is observed at 11 GPa and the Pbnm phase persists up to 74 GPa. The superconducting transition temperature (T{sub c}) increases rapidly with pressure reaching a maximum of {approx}28 K at {approx}6 GPa and decreases at higher pressures, disappearing completely at 14.6 GPa. Simultaneous pressure-dependent X-raymore » diffraction and resistance measurements at low temperatures show superconductivity only in a low-pressure orthorhombic (Cmma) phase of the {alpha}-FeSe{sub 0.92}. Upon increasing pressure at 10 K near T{sub c}, crystalline phases change from a mixture of orthorhombic (Cmma) and hexagonal (P63/mmc) phases to a high-pressure orthorhombic (Pbnm) phase near 6.4 GPa where T{sub c} is maximum.« less

Weather Research and Forecasting Model Sensitivity Comparisons for Warm Season Convective Initiation

NASA Technical Reports Server (NTRS)

Watson, Leela R.

2007-01-01

This report describes the work done by the Applied Meteorology Unit (AMU) in assessing the success of different model configurations in predicting warm season convection over East-Central Florida. The Weather Research and Forecasting Environmental Modeling System (WRF EMS) software allows users to choose among two dynamical cores - the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM). There are also data assimilation analysis packages available for the initialization of the WRF model - the Local Analysis and Prediction System (LAPS) and the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS). Besides model core and initialization options, the WRF model can be run with one- or two-way nesting. Having a series of initialization options and WRF cores, as well as many options within each core, creates challenges for local forecasters, such as determining which configuration options are best to address specific forecast concerns. This project assessed three different model intializations available to determine which configuration best predicts warm season convective initiation in East-Central Florida. The project also examined the use of one- and two-way nesting in predicting warm season convection.

Laboratory evaluations on thermal debonding of ceramic brackets.

PubMed

Sernetz, F; Kraut, J

1991-01-01

The purpose of this laboratory study was to define the working parameters and physiological safety and efficacy of the Dentaurum Ceramic Debonding Unit. Extracted mandibular incisors were utilized because of their low thermal mass and low heat sensitivity. The teeth were embedded in plastic and placed on a turning force measuring apparatus. An electrothermal element was placed in the pulp chamber (filled with a conducting paste). The thermoelement temperature was registered on y-t recorder as was the turning momentum required to remove the ceramic brackets with the Dentaurum Ceramic Debonding Unit. Ceramic brackets from GAC (Allure III), Unitek (Transcend) and Dentaurum (Fascination) using one and two component adhesives (Monolok, Concise), were tested. Scanning electron microscopic views taken after debonding showed predictable (and favorable) adhesive failure at the bracket base/resin interface. No enamel damage was demonstrated. All brackets were removable under three seconds with a clinically reproducible turning force of 85-100 Nmm allowing for intrapulpal temperature increases under the 5 degrees C biocompatible threshold. The Dentaurum Ceramic Debonding Unit provided a safe, reliable, efficient modality of removing ceramic brackets while maintaining a physiologically acceptable rise in pulpal temperature without damage to tooth enamel or pulpal tissue.

Reuse of thermosetting plastic waste for lightweight concrete.

PubMed

Panyakapo, Phaiboon; Panyakapo, Mallika

2008-01-01

This paper presents the utilization of thermosetting plastic as an admixture in the mix proportion of lightweight concrete. Since this type of plastic cannot be melted in the recycling process, its waste is expected to be more valuable by using as an admixture for the production of non-structural lightweight concrete. Experimental tests for the variation of mix proportion were carried out to determine the suitable proportion to achieve the required properties of lightweight concrete, which are: low dry density and acceptable compressive strength. The mix design in this research is the proportion of plastic, sand, water-cement ratio, aluminum powder, and lignite fly ash. The experimental results show that the plastic not only leads to a low dry density concrete, but also a low strength. It was found that the ratio of cement, sand, fly ash, and plastic equal to 1.0:0.8:0.3:0.9 is an appropriate mix proportion. The results of compressive strength and dry density are 4.14N/mm2 and 1395 kg/m3, respectively. This type of concrete meets most of the requirements for non-load-bearing lightweight concrete according to ASTM C129 Type II standard.

Reduced functional loads alter the physical characteristics of the bone-PDL-cementum complex

PubMed Central

Niver, Eric L.; Leong, Narita; Greene, Janelle; Curtis, Donald; Ryder, Mark I.; Ho, Sunita P.

2011-01-01

Background Adaptive properties of the bone-PDL-tooth complex have been identified by changing the magnitude of functional loads using small-scale animal models such as rodents. Reported adaptive responses as a result of lower loads due to softer diet include decreased muscle development, change in structure-function relationship of the cranium, narrowed PDL-space, changes in mineral level of the cortical bone and alveolar jaw bone, and glycosaminoglycans of the alveolar bone. However, the adaptive role of the dynamic bone-PDL-cementum complex due to prolonged reduced loads has not been fully explained to date, especially with regards to concurrent adaptations of bone, PDL and cementum. Hence, the temporal effect of reduced functional loads on physical characteristics such as morphology and mechanical properties, and mineral profiles of the bone-periodontal ligament (PDL)-cementum complex using a rat model was investigated. Materials and Methods Two groups of six-week-old male Sprague-Dawley rats were fed nutritionally identical food with a stiffness range of 127–158N/mm for hard pellet or 0.32–0.47N/mm for soft powder forms. Spatio-temporal adaptation of the bone-PDL-cementum complex was identified by mapping changes in: 1) PDL-collagen orientation and birefringence using polarized light microscopy, bone and cementum adaptation using histochemistry, and bone and cementum morphology using micro X-ray computed tomography, 2) mineral profiles of the PDL-cementum and PDL-bone interfaces by X-ray attenuation, and 3) microhardness of bone and cementum by microindentation of specimens at ages six, eight, twelve, and fifteen weeks. Results Reduced functional loads over prolonged time resulted in 1) altered PDL orientation and decreased PDL collagen birefringence indicating decreased PDL turnover rate and decreased apical cementum resorption; 2) a gradual increase in X-ray attenuation, owing to mineral differences, at the PDL-bone and PDL-cementum interfaces without

Determining the structure of tetragonal Y 2WO 6 and the site occupation of Eu 3+ dopant

NASA Astrophysics Data System (ADS)

Huang, Jinping; Xu, Jun; Li, Hexing; Luo, Hongshan; Yu, Xibin; Li, Yikang

2011-04-01

The compound Y 2WO 6 is prepared by solid state reaction at 750 °C using sodium chloride as mineralizer. Its structure is solved by ab-initio methods from X-ray powder diffraction data. This low temperature phase of yttrium tungstate crystallizes in tetragonal space group P4/ nmm (No. 129), Z=2, a=5.2596(2) Å, c=8.4158(4) Å. The tungsten atoms in the structure adopt an unusual [WO 6] distorted cubes coordination, connecting [YO 6] distorted cubes with oxygen vacancies at the O 2 layers while other yttrium ions Y 2 form [YO 8] cube coordination. Y 3+ ions occupy two crystallographic sites of 2 c ( C4v symmetry) and 2 a ( D2d symmetry) in the Y 2WO 6 host lattice. With Eu 3+ ions doped, the high resolution emission spectrum of Y 2WO 6:Eu 3+ suggests that Eu 3+ partly substituted for Y 3+ in these two sites. The result of the Rietveld structure refinement shows that the Eu 3+ dopants preferentially enter the 2 a site. The uniform cube coordination environment of Eu 3+ ions with the identical eight Eu-O bond lengths is proposed to be responsible for the intense excitation of long wavelength ultraviolet at 466-535 nm.

Arthroscopic suture retrievers and shuttles: a biomechanical investigation of the force required for tendon penetration and defect size.

PubMed

Lenz, Christopher G; Wieser, Karl; Lajtai, Georg; Meyer, Dominik C

2015-11-17

To compare instruments designed for arthroscopic suture handling during arthroscopic rotator cuff repair, to assess the force needed to penetrate the tendon, and to evaluate the residual defect size. Twenty-one instruments were each tested ten times on thawed sheep infraspinatus tendons. The force needed to pierce the tendon with each instrument was measured using a custom setup. Bone wax plates were used to make the perforation marks visible and to quantify the lesions each instrument created. The force to pierce a tendon had a range of 5.6-18.5 N/mm. Within the group of suture retrievers, the angled instruments required in average 85 % higher forces than straight instruments. The lesion area had a range of 2-7 mm(2). Suture retrievers produced significantly larger lesion sizes compared with suture shuttles. For the identical task of passing a suture through a tendon, differences exist regarding the ease of tendon penetration and potential damage to the tendon for different tools. The design, function, and resulting lesion size may be relevant and important for surgical handling and to avoid excess structural damage to the tendon. These results suggest that choosing the most appropriate tools for arthroscopic suture stitching influences the ease of handling and final integrity of the tissue.

Study of iridium silicide monolayers using density functional theory

NASA Astrophysics Data System (ADS)

Popis, Minh D.; Popis, Sylvester V.; Oncel, Nuri; Hoffmann, Mark R.; ćakır, Deniz

2018-02-01

In this study, we investigated physical and electronic properties of possible two-dimensional structures formed by Si (silicon) and Ir (iridium). To this end, different plausible structures were modeled by using density functional theory and the cohesive energies calculated for the geometry of optimized structures, with the lowest equilibrium lattice constants. Among several candidate structures, we identified three mechanically (via elastic constants and Young's modulus), dynamically (via phonon calculations), and thermodynamically stable iridium silicide monolayer structures. The lowest energy structure has a chemical formula of Ir2Si4 (called r-IrSi2), with a rectangular lattice (Pmmn space group). Its cohesive energy was calculated to be -0.248 eV (per IrSi2 unit) with respect to bulk Ir and bulk Si. The band structure indicates that the Ir2Si4 monolayer exhibits metallic properties. Other stable structures have hexagonal (P-3m1) and tetragonal (P4/nmm) cell structures with 0.12 and 0.20 eV/f.u. higher cohesive energies, respectively. Our calculations showed that Ir-Si monolayers are reactive. Although O2 molecules exothermically dissociate on the surface of the free-standing iridium silicide monolayers with large binding energies, H2O molecules bind to the monolayers with a rather weak interaction.

Fluorescent aptasensor for detection of four tetracycline veterinary drugs in milk based on catalytic hairpin assembly reaction and displacement of G-quadruplex.

PubMed

Zhou, Chen; Zou, Haimin; Sun, Chengjun; Ren, Dongxia; Xiong, Wei; Li, Yongxin

2018-05-01

Based on a novel signal amplification strategy by catalytic hairpin assembly and displacement of G-quadruplex DNA, an enzyme-free, non-label fluorescent aptasensing approach was established for sensitive detection of four tetracycline veterinary drugs in milk. The network consisted of a pair of partially complementary DNA hairpins (HP1 and HP2). The DNA aptamer of four tetracycline veterinary drugs was located at the sticky end of the HP1. The ring region of HP1 rich in G and C could form a stable G-quadruplex structure, which could emit specific fluorescence signal after binding with the fluorescent dye and N-methylmesoporphyrin IX (NMM). When presented in the system, the target analytes would be repeatedly used to trigger a recycling procedure between the hairpins, generating numerous HP1-HP2 duplex complexes and displacing G-quadruplex DNA. Thus, the sensitive detection of target analytes was achieved in a wide linear range (0-1000 μg/L) with the detection limit of 4.6 μg/L. Moreover, this proposed method showed high discrimination efficiency towards target analytes against other common mismatched veterinary drugs, and could be successfully applied to the analysis of milk samples. Graphical abstract Schematic of target analyte detection based on catalytic hairpin assembly reaction and displacement of G-quadruplex.

The Effects of Walking Speed on Tibiofemoral Loading Estimated Via Musculoskeletal Modeling

PubMed Central

Lerner, Zachary F.; Haight, Derek J.; DeMers, Matthew S.; Board, Wayne J.; Browning, Raymond C.

2015-01-01

Net muscle moments (NMMs) have been used as proxy measures of joint loading, but musculoskeletal models can estimate contact forces within joints. The purpose of this study was to use a musculoskeletal model to estimate tibiofemoral forces and to examine the relationship between NMMs and tibiofemoral forces across walking speeds. We collected kinematic, kinetic, and electromyographic data as ten adult participants walked on a dual-belt force-measuring treadmill at 0.75, 1.25, and 1.50 m/s. We scaled a musculoskeletal model to each participant and used OpenSim to calculate the NMMs and muscle forces through inverse dynamics and weighted static optimization, respectively. We determined tibiofemoral forces from the vector sum of intersegmental and muscle forces crossing the knee. Estimated tibiofemoral forces increased with walking speed. Peak early-stance compressive tibiofemoral forces increased 52% as walking speed increased from 0.75 to 1.50 m/s, whereas peak knee extension NMMs increased by 168%. During late stance, peak compressive tibiofemoral forces increased by 18% as speed increased. Although compressive loads at the knee did not increase in direct proportion to NMMs, faster walking resulted in greater compressive forces during weight acceptance and increased compressive and anterior/posterior tibiofemoral loading rates in addition to a greater abduction NMM. PMID:23878264

Preparation of polycrystalline FeTe1- x S x ( x = 0.00-0.30) via solid-state reaction method at ambient pressure

NASA Astrophysics Data System (ADS)

Lim, Edmund H. H.; Liew, Josephine Y. C.; Awang Kechik, M. M.; Halim, S. A.; Chen, S. K.; Tan, K. B.; Qi, X.

2017-06-01

Polycrystalline samples with nominal composition FeTe1- x S x ( x = 0.00-0.30) were synthesized via solid state reaction method with intermittent grinding in argon gas flow. X-ray diffraction (XRD) patterns revealed the tetragonal structure (space group P4/nmm) of the samples with the presence of impurities Fe3O4 and FeTe2. By substitution with S, the a and c lattice parameters shrink probably due to the smaller ionic radius of S2- compared to Te2-. Scanning electron microscopy images showed that the samples developed plate-like grains with increasing S substitution. Substitution of Te with S suppresses the structural transition of the parent compound FeTe as shown by both the temperature dependence of resistance and magnetic moment measurements. All of the S-substituted samples showed a rapid drop of resistance at around 9-10 K but zero resistance down to 4 K was not observed. In addition, negative magnetic moment corresponds to diamagnetism was detected in the samples for x = 0.25 and 0.30 suggesting the coexistence of magnetic and superconducting phase in these samples. The magnetization hysteresis loops measured at room temperature showed ferromagnetic behavior for the pure and S substituted samples. However, the magnetization, rentivity and coercivity decreased with S content.

Model-based analysis of fatigued human knee extensors : Effects of isometrically induced fatigue on Hill-type model parameters and ballistic contractions.

PubMed

Penasso, Harald; Thaller, Sigrid

2018-05-05

This study investigated the effect of isometrically induced fatigue on Hill-type muscle model parameters and related task-dependent effects. Parameter identification methods were used to extract fatigue-related parameter trends from isometric and ballistic dynamic maximum voluntary knee extensions. Nine subjects, who completed ten fatiguing sets, each consisting of nine 3 s isometric maximum voluntary contractions with 3 s rest plus two ballistic contractions with different loads, were analyzed. Only at the isometric task, the identified optimized model parameter values of muscle activation rate and maximum force generating capacity of the contractile element decreased from [Formula: see text] to [Formula: see text] Hz and from [Formula: see text] to [Formula: see text] N, respectively. For all tasks, the maximum efficiency of the contractile element, mathematically related to the curvature of the force-velocity relation, increased from [Formula: see text] to [Formula: see text]. The model parameter maximum contraction velocity decreased from [Formula: see text] to [Formula: see text] m/s and the stiffness of the serial elastic element from [Formula: see text] to [Formula: see text] N/mm. Thus, models of fatigue should consider fatigue dependencies in active as well as in passive elements, and muscle activation dynamics should account for the task dependency of fatigue.

Finite Element Analysis of Bone Stress around Micro-Implants of Different Diameters and Lengths with Application of a Single or Composite Torque Force.

PubMed

Lu, Ying-juan; Chang, Shao-hai; Ye, Jian-tao; Ye, Yu-shan; Yu, Yan-song

2015-01-01

Stress on the bone surrounding dental micro-implants affects implant success. To compare the stress on the bone surrounding a micro-implant after application of a single force (SF) of 200 g or a composite force (CF) of 200 g and 6 N.mm torque. Finite element models were developed for micro-implant diameters of 1.2, 1.6, and 2.0 mm, and lengths of 6, 8, 10, and 12 mm and either a SF or CF was applied. The maximum equivalent stress (Max EQS) of the bone surrounding the micro-implant was determined, and the relationships among type of force, diameter, and length were evaluated. The Max EQS of the CF exceeded that of the SF (P< 0.05). The effect of force on stress was related to implant diameter, but not to implant length. The larger CF led to greater instability of the micro-implant and the effect was most pronounced at an implant diameter of 1.2 mm. The use of implant diameters of 1.6 mm and 2.0 mm produced no significant difference in implant stability when either a CF or SF was applied. When considering the use of an implant to perform three-dimensional control on the teeth, the implant diameter chosen should be > 1.2 mm.

Mechanical behaviour of fibre reinforced concrete using soft - drink can

NASA Astrophysics Data System (ADS)

Ilya, J.; Cheow Chea, C.

2017-11-01

This research was carried out to study the behaviour of concrete, specifically compressive and flexural strength, by incorporating recycled soft drink aluminium can as fibre reinforcement in the concrete. Another aim of the research is to determine the maximum proportion of fibres to be added in the concrete. By following standard mix design, Ordinary Portland Cement (OPC) concrete was made to have a target mean strength of 30 N/mm2 with not more than 30 mm of slump. Having the same workability, OPC concrete with 0%, 1% and 2% of soft drink can aluminium fibre was prepared based on weight of cement. The specimens were tested for compressive strength and flexural strength. Laboratory test results based on short term investigation reveals that the compressive strength and flexural strength of concrete containing fibre are higher than of normal OPC concrete. Among two volume fractions, concrete with 1% of soft drink can fibre have performed better result in compressive strength and flexural strength compared with 2% amount of soft drink can fibre. The optimum proportion of aluminium fibre to be added in the concrete as fibre reinforcement is 1% fibre content by weight of cement which gave all the positive response from all the tests conducted.

Tensile Properties of the Deep Transverse Metatarsal Ligament in Hallux Valgus: A CONSORT-Compliant Article.

PubMed

Abdalbary, Sahar Ahmed; Elshaarawy, Ehab A A; Khalid, Bahaa E A

2016-02-01

The deep transverse metatarsal ligament (DTML) connects the neighboring2 metatarsal heads and is one of the stabilizers connecting the lateral sesamoid and second metatarsal head. In this study, we aimed to determine the tensile properties of the DTML in normal specimens and to compare these results with hallux valgus specimens. We hypothesized that the tensile properties of the DTML would be different between the 2 groups of specimens.The DTML in the first interspace was dissected from 12 fresh frozen human cadaveric specimens. Six cadavers had bilateral hallux valgus and the other 6 cadavers had normal feet. The initial length (L0) and cross-sectional area (A0) of the DTML were measured using a digital caliper, and tensile tests with load failure were performed using a material testing machine.There were significant between-groups differences in the initial length (L0) P = 0.009 and cross-sectional area (A0) of the DTML P = 0.007. There were also significant between-groups differences for maximum force (N) P = 0.004, maximum distance (mm) P = 0.005, maximum stress (N/mm) P = 0.003, and maximum strain (%) P = 0.006.The DTML is an anatomical structure for which the tensile properties differ in hallux valgus.

Kondo lattice heavy fermion behavior in CeRh2Ga2

NASA Astrophysics Data System (ADS)

Anand, V. K.; Adroja, D. T.; Bhattacharyya, A.; Klemke, B.; Lake, B.

2017-04-01

The physical properties of an intermetallic compound CeRh2Ga2 have been investigated by magnetic susceptibility χ (T) , isothermal magnetization M(H), heat capacity {{C}\\text{p}}(T) , electrical resistivity ρ (T) , thermal conductivity κ (T) and thermopower S(T) measurements. CeRh2Ga2 is found to crystallize with CaBe2Ge2-type primitive tetragonal structure (space group P4/nmm). No evidence of long range magnetic order is seen down to 1.8 K. The χ (T) data show paramagnetic behavior with an effective moment {μ\\text{eff}}≈ 2.5~{μ\\text{B}} /Ce indicating Ce3+ valence state of Ce ions. The ρ (T) data exhibit Kondo lattice behavior with a metallic ground state. The low-T {{C}\\text{p}}(T) data yield an enhanced Sommerfeld coefficient γ =130(2) mJ/mol K2 characterizing CeRh2Ga2 as a moderate heavy fermion system. The high-T {{C}\\text{p}}(T) and ρ (T) show an anomaly near 255 K, reflecting a phase transition. The κ (T) suggests phonon dominated thermal transport with considerably higher values of Lorenz number L(T) compared to the theoretical Sommerfeld value L 0.

Preliminary Investigation of Acoustical Properties of Concrete Containing Oil Palm Shell as an Aggregate Replacement

NASA Astrophysics Data System (ADS)

Zanariah, J.; Zaiton, H.; Musli Nizam, Y.; Khairulzan, Y.; Dianah, M.; Nadirah, D.; Hanifi, O. Mohd

2018-03-01

Research has been so far focused extensively on mechanical properties of oil palm shell (OPS) concrete but less on sound properties. Thus, the objective of this study is to investigate whether concrete containing OPS can be applied in the field of road noise barrier. The acoustic properties of the samples were determined by using an impedance tube connected to a sound source. The noise reduction coefficient (NRC) and weighted sound absorption coefficient (αw) which is more commonly use in the road traffic noise barrier field were calculated according to BS EN ISO 11654:1997. Compressive strengths of samples were also determined by using compressive test. The results presented that the compressive strength of the OPS composites decreased as increased in w/c wit minimum of 20.44 N/mm2 at 28 days for w/c = 0.6 but still satisfactory for structural use. The sound absorption coefficient demonstrated that they were decreased as the w/c are higher with typical curve of two peaks at 315Hz and 1000Hz. All samples were then can be classified as class E as 0.5< αw < 0.25 and should be classified as L due to favourable deviation higher than 0.25 for 250 Hz.

Design and Evaluation of a Cable-Driven fMRI-Compatible Haptic Interface to Investigate Precision Grip Control

PubMed Central

Vigaru, Bogdan; Sulzer, James; Gassert, Roger

2016-01-01

Our hands and fingers are involved in almost all activities of daily living and, as such, have a disproportionately large neural representation. Functional magnetic resonance imaging investigations into the neural control of the hand have revealed great advances, but the harsh MRI environment has proven to be a challenge to devices capable of delivering a large variety of stimuli necessary for well-controlled studies. This paper presents a fMRI-compatible haptic interface to investigate the neural mechanisms underlying precision grasp control. The interface, located at the scanner bore, is controlled remotely through a shielded electromagnetic actuation system positioned at the end of the scanner bed and then through a high stiffness, low inertia cable transmission. We present the system design, taking into account requirements defined by the biomechanics and dynamics of the human hand, as well as the fMRI environment. Performance evaluation revealed a structural stiffness of 3.3 N/mm, renderable forces up to 94 N, and a position control bandwidth of at least 19 Hz. MRI-compatibility tests showed no degradation in the operation of the haptic interface or the image quality. A preliminary fMRI experiment during a pilot study validated the usability of the haptic interface, illustrating the possibilities offered by this device. PMID:26441454

Synthesis, structure, and magnetic properties of new layered phosphate halides Sr2Cu5(PO4)4X2·8H2O (X = Cl, Br) with a crown-like building unit.

PubMed

Qiu, Chaoqun; He, Zhangzhen; Cui, Meiyan; Tang, Yingying; Chen, Sihuai

2017-03-27

Two new compounds Sr 2 Cu 5 (PO 4 ) 4 X 2 ·8H 2 O (X = Cl and Br) are synthesized by a conventional hydrothermal method. Sr 2 Cu 5 (PO 4 ) 4 Cl 2 ·8H 2 O crystallizes in the tetragonal system with a space group of P42 1 2, while Sr 2 Cu 5 (PO 4 ) 4 Br 2 ·8H 2 O crystallizes in the space group P4/nmm, which are found to have a similar framework of layered structure, in which the crown-like {Cu 5 (PO 4 ) 4 X 2 } building units connect to each other forming a 2D corrugated sheet with vacancies, while the Sr 2+ cations are located along the vacancies. The spin lattice of two compounds built by Cu 2+ ions shows a new type of corrugated square. Magnetic measurements confirmed that both Sr 2 Cu 5 (PO 4 ) 4 X 2 ·8H 2 O (X = Cl and Br) exhibit antiferromagnetic ordering at low temperatures. A fit of theoretical model shows exchange interaction J = -25.62 K for the Cl-analogue and J/k B = -26.47 K for the Br-analogue.

Fracture healing in mice under controlled rigid and flexible conditions using an adjustable external fixator.

PubMed

Röntgen, Viktoria; Blakytny, Robert; Matthys, Romano; Landauer, Mario; Wehner, Tim; Göckelmann, Melanie; Jermendy, Philipp; Amling, Michael; Schinke, Thorsten; Claes, Lutz; Ignatius, Anita

2010-11-01

Mice are increasingly used to investigate mechanobiology in fracture healing. The need exists for standardized models allowing for adjustment of the mechanical conditions in the fracture gap. We introduced such a model using rigid and flexible external fixators with considerably different stiffness (axial stiffnesses of 18.1 and 0.82 N/mm, respectively). Both fixators were used to stabilize a 0.5 mm osteotomy gap in the femur of C57BL/6 mice (each n = 8). Three-point bending tests, µCT, and histomorphometry demonstrated a different healing pattern after 21 days. Both fixations induced callus formation with a mixture of intramembranous and enchondral ossification. Under flexible conditions, the bending stiffness of the callus was significantly reduced, and a larger but qualitatively inferior callus with a significantly lower fraction of bone but a higher fraction of cartilage and soft tissue was formed. Monitoring of the animal movement and the ground reaction forces demonstrated physiological loading with no significant differences between the groups, suggesting that the differences in healing were not based on a different loading behavior. In summary, flexible external fracture fixation of the mouse femur led to delayed fracture healing in comparison to a more rigid situation. © 2010 Orthopaedic Research Society.

Experimental Study on Thermal Conductivity of Self-Compacting Concrete with Recycled Aggregate

PubMed Central

Fenollera, María; Míguez, José Luis; Goicoechea, Itziar; Lorenzo, Jaime

2015-01-01

The research focuses on the use of recycled aggregate (RA), from waste pieces generated during production in precast plants for self-compacting concrete (SCC) manufactured with a double sustainable goal: recycle manufacturing waste (consumption) and improvement of the thermal properties of the manufactured product (energy efficiency). For this purpose, a mechanical study to ensure technical feasibility of the concrete obtained has been conducted, as well as a thermal analysis of recycled SCC specimens of 50 N/mm2 resistance, with different RA doses (0%, 20%, 50% and 100%). The main parameters that characterize a SCC in both states, fresh (slump-flow) and hard (compressive strength), have been tested; also, a qualitative analysis of the thermal conductivity using infrared thermography (IRT) and quantitative analysis with heat flow meter at three temperatures 20 °C, 25 °C and 30 °C have been performed. The results suggest the existence of two different thermal behaviors: concretes with 0% and 20% of RA, and on the other hand concretes with 50% and 100% of RA. It has also demonstrated the validity of the IRT as sampling technique in estimating the thermal behavior of materials having reduced range of variation in parameters. PMID:28793449

An electro-conductive fluid as a responsive implant for the controlled stimuli-release of diclofenac sodium.

PubMed

Bijukumar, Divya; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Pillay, Viness

2016-11-01

The purpose of this study was to develop an electro-responsive co-polymeric (ERP) implantable gel from polyethylene glycol (PEG), sodium polystyrene sulphonate (NaPss), polyvinyl alcohol (PVA), and diethyl acetomidomalonate (DAA) for electro-liberation of the model drug diclofenac sodium. Various physicochemical and physicomechanical characterization tests were undertaken on the synthesized drug-free gel (ERP G1) and drug-loaded gel (ERP G2). The ability of the gel to release diclofenac sodium following electrical stimulation was evaluated using a galvanostat while Molecular Mechanics (MM) simulations were performed to elucidate the experimental mechanisms. A stable electro-active gel exhibiting superior cycling stability was produced with desirable rheological properties, rigidity (BHN = 35.4 N ± 0.33 N/mm 2 ; resilience = 10.91 ± 0.11%), thermal properties (T g  ≈ 70 °C; T c  ≈ 200 °C) and homogeneous morphology. "ON-OFF" pursatile gradual drug release (37-94% from t 30 min -t 180   min ) kinetics was observed upon applying electric stimulation intermittently, indicating that drug release from the gel was electrically controlled. Overall, the galvanometric and MM evaluation ascertained the suitability of the PEG/NaPss/PVA ERP-Gel for application as a subcutaneously injectable drug delivery implant.

Temperature insensitive curvature sensor based on cascading photonic crystal fiber

NASA Astrophysics Data System (ADS)

Fu, Guangwei; Li, Yunpu; Fu, Xinghu; Jin, Wa; Bi, Weihong

2018-03-01

A temperature insensitive curvature sensor is proposed based on cascading photonic crystal fiber. Using the arc fusion splicing method, this sensor is fabricated by cascading together a single-mode fiber (SMF), a three layers air holes structure of photonic crystal fiber (3PCF), a five layers air holes structure of photonic crystal fiber (5PCF) and a SMF in turn. So the structure SMF-3PCF-5PCF-SMF can be obtained with a total length of 20 mm. During the process of fabrication, the splicing machine parameters and the length of each optical fiber are adjusted to obtain a high sensitivity curvature sensor. The experimental results show that the curvature sensitivity is -8.40 nm/m-1 in the curvature variation range of 0-1.09 m-1, which also show good linearity. In the range of 30-90 °C, the temperature sensitivity is only about 3.24 pm/°C, indicating that the sensor is not sensitive to temperature. The sensor not only has the advantages of easy fabricating, simple structure, high sensitivity but also can solve the problem of temperature measurement cross sensitivity, so it can be used for different areas including aerospace, large-scale bridge, architectural structure health monitoring and so on.

Influence of disintegrants in different substrate physical form on dimensional recovery of multi-component tablet.

PubMed

Sarkar, Srimanta; Ooi, Shing Ming; Liew, Celine Valeria; Tan, Bing Xun; Heng, Paul Wan Sia

2014-11-20

This study investigated the influence of different disintegrants, present in different substrate physical forms, on dimensional recovery of multi-component tablets prepared at different compression pressures. Formulations containing model drug, metformin, (10%, w/w), different disintegrants (10%, w/w), and lactose (80%, w/w) were compressed directly or after granulation using polyvinyl pyrrolidone (1%, w/w) as binder, into tablets (350 mg, 10mm diameter) at 150, 200, and 250 N/mm(2) compression pressures. Tablets were characterized for immediate dimensional recovery (IR) after ejection from the die, latent dimensional recovery (LR) over 24 h, tensile strength, and disintegration. The IR was predominantly contributed by crystalline components whereas LR was brought about by polymeric materials. With increased compression pressure, higher degree of plastic deformation of the polymeric disintegrants resulted in tablet with lower LR and higher tensile strength. Presence of polyvinyl pyrrolidone in the granules contributed considerably to plastic deformation, and the tablets produced had lower LR, higher tensile strength, and longer disintegration time. This study indicated that use of granules as the feed substrate physical form and a prudent selection of components may enable the coating of resultant tablets immediately after compression without the risk of coat damage due to LR. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison with CLPX II airborne data using DMRT model

USGS Publications Warehouse

Xu, X.; Liang, D.; Andreadis, K.M.; Tsang, L.; Josberger, E.G.

2009-01-01

In this paper, we considered a physical-based model which use numerical solution of Maxwell Equations in three-dimensional simulations and apply into Dense Media Radiative Theory (DMRT). The model is validated in two specific dataset from the second Cold Land Processes Experiment (CLPX II) at Alaska and Colorado. The data were all obtain by the Ku-band (13.95GHz) observations using airborne imaging polarimetric scatterometer (POLSCAT). Snow is a densely packed media. To take into account the collective scattering and incoherent scattering, analytical Quasi-Crystalline Approximation (QCA) and Numerical Maxwell Equation Method of 3-D simulation (NMM3D) are used to calculate the extinction coefficient and phase matrix. DMRT equations were solved by iterative solution up to 2nd order for the case of small optical thickness and full multiple scattering solution by decomposing the diffuse intensities into Fourier series was used when optical thickness exceed unity. It was shown that the model predictions agree with the field experiment not only co-polarization but also cross-polarization. For Alaska region, the input snow structure data was obtain by the in situ ground observations, while for Colorado region, we combined the VIC model to get the snow profile. ??2009 IEEE.

A Multi-Finger Interface with MR Actuators for Haptic Applications.

PubMed

Qin, Huanhuan; Song, Aiguo; Gao, Zhan; Liu, Yuqing; Jiang, Guohua

2018-01-01

Haptic devices with multi-finger input are highly desirable in providing realistic and natural feelings when interacting with the remote or virtual environment. Compared with the conventional actuators, MR (Magneto-rheological) actuators are preferable options in haptics because of larger passive torque and torque-volume ratios. Among the existing haptic MR actuators, most of them are still bulky and heavy. If they were smaller and lighter, they would become more suitable for haptics. In this paper, a small-scale yet powerful MR actuator was designed to build a multi-finger interface for the 6 DOF haptic device. The compact structure was achieved by adopting the multi-disc configuration. Based on this configuration, the MR actuator can generate the maximum torque of 480 N.mm with dimensions of only 36 mm diameter and 18 mm height. Performance evaluation showed that it can exhibit a relatively high dynamic range and good response characteristics when compared with some other haptic MR actuators. The multi-finger interface is equipped with three MR actuators and can provide up to 8 N passive force to the thumb, index and middle fingers, respectively. An application example was used to demonstrate the effectiveness and potential of this new MR actuator based interface.

Numerical modelling of new rockfall interception nets

NASA Astrophysics Data System (ADS)

von Boetticher, Albrecht; Volkwein, Axel; Wendeler, Corinna

2010-05-01

The design and certification of effective rockfall protection barriers is mainly achieved through 1:1 prototype testing. In order to reduce development costs of a prototype it is recommended that pre-studies using numerical simulations are performed. A large component to modelling rockfall protection systems is the numerical simulation of the nets. To date there exist several approaches to model the different mesh types such as ring nets or diagonal meshes (Nicot 1999, Cazzani et al. 2002, Volkwein 2004). However, the consideration of chain link meshes has not yet been realised. Chain link meshes are normally found as standard fence structures. However, they also exist in setups using high-strength steel and wire bundles. These variants show an enormous capacity to retain loads e.g. rockfalls, and at the same time are very efficient due to their low demand of steel material. The increasing application of chain link mesh in barrier systems requires an accurate model is available to complete prototype studies. A new approach now aims to perform a Finite Element simulation of such chain link meshes. The main challenge herein is to achieve the net deformation behaviour that is observed in field tests also in the simulation. A simulation using simple truss elements would not work since it neglects the out-of-plane-height of the mesh construction providing important reserves for local and global high deformations. Thus addressing this, a specially developed Discrete Element is able to reconstruct the mechanical behaviour of the single chain wire (bundles). As input parameters it utilises typical properties such as longitudinal and transversal mesh widths, and break loads resulting from in-plane-tension tests and steel strength. The single chain elements then can be combined to a complete mesh (e.g. 130 x 65 mm, 3 - 4 mm wire with a strength of 1770 N-mm2). Combining these elements with a supporting structure consisting of posts, ropes and energy absorbers, enables the

Effect of Hypercholesterolemia on Fatty Infiltration and Quality of Tendon-to-Bone Healing in a Rabbit Model of a Chronic Rotator Cuff Tear: Electrophysiological, Biomechanical, and Histological Analyses.

PubMed

Chung, Seok Won; Park, HaeBong; Kwon, Jieun; Choe, Ghee Young; Kim, Sae Hoon; Oh, Joo Han

2016-05-01

The incidence of healing failure after rotator cuff repair is high, and fatty infiltration is a crucial factor in healing failure. To verify the effect of hypercholesterolemia on fatty infiltration and the quality of tendon-to-bone healing and its reversibility by lowering the cholesterol level in a chronic tear model using the rabbit supraspinatus. Controlled laboratory study. Forty-eight rabbits were randomly allocated into 4 groups (n = 12 each). After 4 weeks of a high-cholesterol diet (groups A and B) and a regular diet (groups C and D), the supraspinatus tendon was detached and left alone for 6 weeks and then was repaired in a transosseous manner (groups A, B, and C). Group D served as a control. Group A continued to receive the high-cholesterol diet until the final evaluation (6 weeks after repair); however, at the time of repair, group B was changed to a general diet with administration of a cholesterol-lowering agent (simvastatin). Histological evaluation of the fat-to-muscle proportion was performed twice, at the time of repair and the final evaluation, and an electromyographic (EMG) test, mechanical test, and histological test of tendon-to-bone healing were performed at the final evaluation. For the EMG test, group A showed a significantly smaller area of compound muscle action potential compared with groups C and D (all P <.01), and group B showed a larger area than group A, almost up to the level of group C (P = .312). Similarly, group A showed significantly lower mechanical properties both in load-to-failure and stiffness compared with groups C and D (all P <.05). In addition, although not significantly different, the mechanical properties of group B were higher than those of group A (mean load-to-failure: group A = 42.01 N, group B = 58.23 N [P = .103]; mean stiffness: group A = 36.32 N/mm, group B = 47.22 N/mm [P = .153]). For the histological test, groups A and B showed a significantly higher fat-to-muscle proportion than did groups C and D at 6

Reduced functional loads alter the physical characteristics of the bone-periodontal ligament-cementum complex.

PubMed

Niver, E L; Leong, N; Greene, J; Curtis, D; Ryder, M I; Ho, S P

2011-12-01

Adaptive properties of the bone-periodontal ligament-tooth complex have been identified by changing the magnitude of functional loads using small-scale animal models, such as rodents. Reported adaptive responses as a result of lower loads due to softer diet include decreased muscle development, change in structure-function relationship of the cranium, narrowed periodontal ligament space, and changes in the mineral level of the cortical bone and alveolar jaw bone and in the glycosaminoglycans of the alveolar bone. However, the adaptive role of the dynamic bone-periodontal ligament-cementum complex to prolonged reduced loads has not been fully explained to date, especially with regard to concurrent adaptations of bone, periodontal ligament and cementum. Therefore, in the present study, using a rat model, the temporal effect of reduced functional loads on physical characteristics, such as morphology and mechanical properties and the mineral profiles of the bone-periodontal ligament-cementum complex was investigated. Two groups of 6-wk-old male Sprague-Dawley rats were fed nutritionally identical food with a stiffness range of 127-158 N/mm for hard pellet or 0.3-0.5 N/mm for soft powder forms. Spatio-temporal adaptation of the bone-periodontal ligament-cementum complex was identified by mapping changes in the following: (i) periodontal ligament collagen orientation and birefringence using polarized light microscopy, bone and cementum adaptation using histochemistry, and bone and cementum morphology using micro-X-ray computed tomography; (ii) mineral profiles of the periodontal ligament-cementum and periodontal ligament-bone interfaces by X-ray attenuation; and (iii) microhardness of bone and cementum by microindentation of specimens at ages 6, 8, 12 and 15 wk. Reduced functional loads over prolonged time resulted in the following adaptations: (i) altered periodontal ligament orientation and decreased periodontal ligament collagen birefringence, indicating decreased

Links and opportunities

NASA Astrophysics Data System (ADS)

1999-09-01

, Anglo-Saxons and Vikings in Britain; and the Football museum in Preston plans to help local pupils with their literacy and numeracy skills by preparing newspaper reports and football results tables. In this role of supporting education the various bodies will be both helping teachers to deliver the curriculum and also bringing their own cultural resources to life for the students. On a related theme, the Royal Observatory at Greenwich has just introduced its own Open Museum course to prepare adults with an interest in astronomy to study for a GCSE in the subject. The course begins in October and lasts for nine months, covering topics such as the Earth and Moon, solar system, stars, galaxies and observing techniques. Those undertaking the course will be able to use the Observatory's 28 inch refractor and a Meade LX10 Schmidt Cassegrain telescope. Further information on the course and the Open Museum is available from Joy Affection (tel: 0181 312 6747) or from the NMM website at www.nmm.ac.uk.

Optimization of a polymer composite employing molecular mechanic simulations and artificial neural networks for a novel intravaginal bioadhesive drug delivery device.

PubMed

Ndesendo, Valence M K; Pillay, Viness; Choonara, Yahya E; du Toit, Lisa C; Kumar, Pradeep; Buchmann, Eckhart; Meyer, Leith C R; Khan, Riaz A

2012-01-01

This study aimed at elucidating an optimal synergistic polymer composite for achieving a desirable molecular bioadhesivity and Matrix Erosion of a bioactive-loaded Intravaginal Bioadhesive Polymeric Device (IBPD) employing Molecular Mechanic Simulations and Artificial Neural Networks (ANN). Fifteen lead caplet-shaped devices were formulated by direct compression with the model bioactives zidovudine and polystyrene sulfonate. The Matrix Erosion was analyzed in simulated vaginal fluid to assess the critical integrity. Blueprinting the molecular mechanics of bioadhesion between vaginal epithelial glycoprotein (EGP), mucin (MUC) and the IBPD were performed on HyperChem 8.0.8 software (MM+ and AMBER force fields) for the quantification and characterization of correlative molecular interactions during molecular bioadhesion. Results proved that the IBPD bioadhesivity was pivoted on the conformation, orientation, and poly(acrylic acid) (PAA) composition that interacted with EGP and MUC present on the vaginal epithelium due to heterogeneous surface residue distributions (free energy= -46.33 kcalmol(-1)). ANN sensitivity testing as a connectionist model enabled strategic polymer selection for developing an IBPD with an optimally prolonged Matrix Erosion and superior molecular bioadhesivity (ME = 1.21-7.68%; BHN = 2.687-4.981 N/mm(2)). Molecular modeling aptly supported the EGP-MUC-PAA molecular interaction at the vaginal epithelium confirming the role of PAA in bioadhesion of the IBPD once inserted into the posterior fornix of the vagina.

Search for unconventional superconductors among the YTE 2Si2 compounds (TE  =  Cr, Co, Ni, Rh, Pd, Pt)

NASA Astrophysics Data System (ADS)

Pikul, A. P.; Samsel–Czekała, M.; Chajewski, G.; Romanova, T.; Hackemer, A.; Gorzelniak, R.; Wiśniewski, P.; Kaczorowski, D.

2017-05-01

Motivated by the recent discovery of exotic superconductivity in YFe2Ge2 we undertook reinvestigation of formation and physical properties of yttrium-based 1:2:2 silicides. Here we report on syntheses and crystal structures of the YTE 2Si2 compounds with TE  =  Cr, Co, Ni, Rh, Pd and Pt, and their low-temperature physical properties measurements, supplemented by results of fully relativistic full-potential local-orbital minimum basis band structure calculations. We confirm that most of the members of that family crystallize in a tetragonal ThCr2Si2-type structure (space group I4/mmm) and have three-dimensional Fermi surface, while only one of them (YPt2Si2) forms with a closely-related primitive CaBe2Ge2-type unit cell (space group P4/nmm) and possess quasi-two-dimensional Fermi surface sheets. Physical measurements indicated that BCS-like superconductivity is observed only in YPt2Si2 (T c  =  1.54 K) and YPd2Si2 (T c  =  0.43 K), while no superconducting phase transition was found in other systems at least down to 0.35 K. Thermal analysis showed no polymorphism in both superconducting phases. No clear relation between the superconductivity and the crystal structure (and dimensionality of the Fermi surface) was observed.

Bond strength of an alkylene bis(dilactoyl)-methacrylate bone adhesive: a biomechanical evaluation in sheep.

PubMed

Heiss, Christian; Schettler, Nicky; Wenisch, Sabine; Cords, Sven; Schilke, Frank; Lips, Katrin Susanne; Alt, Volker; Schnettler, Reinhard

2010-01-01

The purpose of this study is to assess the mechanical efficacy of an alkylene bis(dilactoyl)-methacrylate-based degradable bone adhesive in 36 sheep. Bone segmentation with osteotomies of the metaphyseal ulna was performed and adhesive was applied into the osteotomy gaps in 18 sheep. The remaining 18 animals served as controls. The segment was subsequently stabilized without any osteosynthesis in all sheep. Six animals of the adhesive group and 6 controls were killed after 21, 42 and 84 days, respectively. Bond strength of the adhesive and quality of fracture healing was studied using biomechanical, histological and radiological methods. There were no significant differences in biomechanical analysis between both groups at any time. However, an increase of in vivo bond strength with the highest stiffness of 102.83 N/mm(2) was observed in the adhesive group after 84 days. In vitro analysis showed non-significant differences in bond strength during polymerization time. Histomorphometric investigations revealed significant differences in osteotomy cross-section area after 84 days, with higher areas of callus in the control. After 84 days the X-ray examinations showed completely bridged gaps in four of six animals in the adhesive and in five animals in the control group. This bone adhesive exhibited good in vivo and in vitro bond strength and mechanical efficiency in both the short and long term without impairment of physiological fracture healing.

[Three-dimensional finite element analysis of maxillary anterior teeth retraction force system in light wire technique].

PubMed

Zhang, Xiangfeng; Wang, Chao; Xia, Xi; Deng, Feng; Zhang, Yi

2015-06-01

This study aims to construct a three-dimensional finite element model of a maxillary anterior teeth retraction force system in light wire technique and to investigate the difference of hydrostatic pressure and initial displacement of upper anterior teeth under different torque values of tip back bend. A geometric three-dimensional model of the maxillary bone, including all the upper teeth, was achieved via CT scan. To construct the force model system, lingual brackets and wire were constructed by using the Solidworks. Brackets software, and wire were assembled to the teeth. ANASYS was used to calculate the hydrostatic pressure and the initial displacement of maxillary anterior teeth under different tip-back bend moments of 15, 30, 45, 60, and 75 Nmm when the class II elastic force was 0.556 N. Hydrostatic pressure was concentrated in the root apices and cervical margin of upper anterior teeth. Distal tipping and relative intrusive displacement were observed. The hydrostatic pressure and initial displacement of upper canine were greater than in the central and lateral incisors. This hydrostatic pressure and initial intrusive displacement increased with an increase in tip-back bend moment. Lingual retraction force system of maxillary anterior teeth in light wire technique can be applied safely and controllably. The type and quantity of teeth movement can be controlled by the alteration of tip-back bend moment.

An Investigation of the Characterization of Cloud Contamination in Hyperspectral Radiances

NASA Technical Reports Server (NTRS)

McCarty, William; Jedlovec, Gary J.; LeMarshall, John

2007-01-01

In regions lacking direct observations, the assimilation of radiances from infrared and microwave sounders is the primary method for characterizing the atmosphere in the analysis process. In recent years, technological advances have led to the launching of more advanced sounders, particularly in the thermal infrared spectrum. With the advent of these hyperspectral sounders, the amount of data available for the analysis process has and will continue to be dramatically increased. However, the utilization of infrared radiances in variational assimilation can be problematic in the presence of clouds; specifically the assessment of the presence of clouds in an instantaneous field of view (IFOV) and the contamination in the individual channels within the IFOV. Various techniques have been developed to determine if a channel is contaminated by clouds. The work presented in this paper and subsequent presentation will investigate traditional techniques and compare them to a new technique, the C02 sorting technique, which utilizes the high spectral resolution of the Atmospheric Infrared Sounder (AIRS) within the framework of the Gridpoint Statistical Interpolation (GSI) 3DVAR system. Ultimately, this work is done in preparation for the assessment of short-term forecast impacts with the regional assimilation of AIRS radiances within the analysis fields of the Weather Research and Forecast Nonhydrostatic Mesoscale Model (WRF-NMM) at the NASA Short-term Prediction Research and Transition (SPORT) Center.

Finite Element Analysis of Bone Stress around Micro-Implants of Different Diameters and Lengths with Application of a Single or Composite Torque Force

PubMed Central

Lu, Ying-juan; Chang, Shao-hai; Ye, Jian-tao; Ye, Yu-shan; Yu, Yan-song

2015-01-01

Background Stress on the bone surrounding dental micro-implants affects implant success. Purpose To compare the stress on the bone surrounding a micro-implant after application of a single force (SF) of 200 g or a composite force (CF) of 200 g and 6 N.mm torque. Materials and Methods Finite element models were developed for micro-implant diameters of 1.2, 1.6, and 2.0 mm, and lengths of 6, 8, 10, and 12 mm and either a SF or CF was applied. The maximum equivalent stress (Max EQS) of the bone surrounding the micro-implant was determined, and the relationships among type of force, diameter, and length were evaluated. Results The Max EQS of the CF exceeded that of the SF (P< 0.05). The effect of force on stress was related to implant diameter, but not to implant length. The larger CF led to greater instability of the micro-implant and the effect was most pronounced at an implant diameter of 1.2 mm. The use of implant diameters of 1.6 mm and 2.0 mm produced no significant difference in implant stability when either a CF or SF was applied. Conclusion When considering the use of an implant to perform three-dimensional control on the teeth, the implant diameter chosen should be > 1.2 mm. PMID:26659581

Flux free single crystal growth and characterization of FeTe1-xSx (x=0.00 and 0.10) crystals

NASA Astrophysics Data System (ADS)

Maheshwari, P. K.; Awana, V. P. S.

2018-05-01

We report synthesis of S doped FeTe1-xSx (x = 0.00 and 0.10) single crystals using flux free method via solid state reaction. Single crystal XRD patterns of FeTe1-xSx (x = 0.00 and 0.10) confirm the single crystalline property, as the crystals are grown in (00l) plane only. Powder XRD result of FeTe1-xSx (x = 0.00 and 0.10) crystals show that crystalline in tetragonal structure having P4/nmm space group. Rietveld refinement results show that both a and c lattice parameters decreases with S doping of 10% at Te site in FeTe1-xSx. Detailed scanning electron microscopy (SEM) image of FeTe0.90S0.10 shows that the growth of crystal is in slab-like morphology. Electrical resistivity measurement results onset confirm the superconductivity in S doped 10% sample at Te site and superconducting transition Tconset occurs at 9.5K and Tcoffset(ρ=0) occurs at 6.5K. ρ-T measurement has been performed under various magnetic field up to 12 Tesla down to 2K. Upper critical field Hc2(0), for x=0.10, which comes around 70Tesla, 60Tesla and 45Tesla of normal resistivity criterion ρn = 90%, 50% and 10% criterion respectively.

Molecular level analyses of mechanical properties of PTFE sterilized by Co-60 γ-ray irradiation for clinical use

NASA Astrophysics Data System (ADS)

Furuta, Masakazu; Matsugaki, Aira; Nakano, Takayoshi; Hirata, Isao; Kato, Koichi; Oda, Takashi; Sato, Mamoru; Okazaki, Masayuki

2017-10-01

Recently, Co-60 gamma-ray irradiation has become markedly popular for the sterilization of biomedical materials, including expanded PTFE. However, its effect on the properties of PTFE has not been thoroughly examined. In this study, changes in the properties of PTFE before and after irradiation were analyzed physicochemically and discussed crystallographically. The tensile breaking strengths of PTFE decreased markedly on irradiation at 1 kGy, and were maintained at almost one fourth of the original value (44.3±2.5 N/mm2) ranging from 5 to 100 kGy. XPS analysis indicated that the atomic concentrations of carbon (C) and fluorine (F) of PTFE were not different among samples irradiated at various dosages. Raman spectra of PTFE showed a slight increase of the absorption peak intensity at 735 cm-1 in an irradiation dosage-dependent manner. X-ray diffraction showed that the crystal size of PTFE (56.7±1.0 nm) became smaller after radiation at 100 kGy (48.5±0.6 nm). These results are consistent with the above results of Raman analysis. It is suggested that the observed changes in the mechanical properties of PTFE may be due to nano-scale C-C bond scission by gamma ray irradiation, and not due to the formation of micro-scale cracks.

Meniscal shear stress for punching.

PubMed

Tuijthof, Gabrielle J M; Meulman, Hubert N; Herder, Just L; van Dijk, C Niek

2009-01-01

Experimental determination of the shear stress for punching meniscal tissue. Meniscectomy (surgical treatment of a lesion of one of the menisci) is the most frequently performed arthroscopic procedure. The performance of a meniscectomy is not optimal with the currently available instruments. To design new instruments, the punching force of meniscal tissue is an important parameter. Quantitative data are unavailable. The meniscal punching process was simulated by pushing a rod through meniscal tissue at constant speed. Three punching rods were tested: a solid rod of Oslash; 3.00 mm, and two hollow tubes (Oslash; 3.00-2.60 mm) with sharpened cutting edges of 0.15 mm and 0.125 mm thick, respectively. Nineteen menisci acquired from 10 human cadaveric knee joints were punched (30 tests). The force and displacement were recorded from which the maximum shear stress was determined (average added with three times the standard deviation). The maximum shear stress for the solid rod was determined at 10.2 N/mm2. This rod required a significantly lower punch force in comparison with the hollow tube having a 0.15 mm cutting edge (plt;0.01). The maximum shear stress for punching can be applied to design instruments, and virtual reality training environments. This type of experiment is suitable to form a database with material properties of human tissue similar to databases for the manufacturing industry.

Salubrinal improves mechanical properties of the femur in osteogenesis imperfecta mice.

PubMed

Takigawa, Shinya; Frondorf, Brian; Liu, Shengzhi; Liu, Yang; Li, Baiyan; Sudo, Akihiro; Wallace, Joseph M; Yokota, Hiroki; Hamamura, Kazunori

2016-10-01

Salubrinal is an agent that reduces the stress to the endoplasmic reticulum by inhibiting de-phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α). We and others have previously shown that the elevated phosphorylation of eIF2α stimulates bone formation and attenuates bone resorption. In this study, we applied salubrinal to a mouse model of osteogenesis imperfecta (Oim), and examined whether it would improve Oim's mechanical property. We conducted in vitro experiments using RAW264.7 pre-osteoclasts and bone marrow derived cells (BMDCs), and performed in vivo administration of salubrinal to Oim (+/-) mice. The animal study included two control groups (wildtype and Oim placebo). The result revealed that salubrinal decreased expression of nuclear factor of activated T cells cytoplasmic 1 (NFATc1) and suppressed osteoclast maturation, and it stimulated mineralization of mesenchymal stem cells from BMDCs. Furthermore, daily injection of salubrinal at 2 mg/kg for 2 months made stiffness (N/mm) and elastic module (GPa) of the femur undistinguishable to those of the wildtype control. Collectively, this study supported salubrinal's beneficial role to Oim's femora. Unlike bisphosphonates, salubrinal stimulates bone formation. For juvenile OI patients who may favor strengthening bone without inactivating bone remodeling, salubrinal may present a novel therapeutic option. Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

Mechatronic design of haptic forceps for robotic surgery.

PubMed

Rizun, P; Gunn, D; Cox, B; Sutherland, G

2006-12-01

Haptic feedback increases operator performance and comfort during telerobotic manipulation. Feedback of grasping pressure is critical in many microsurgical tasks, yet no haptic interface for surgical tools is commercially available. Literature on the psychophysics of touch was reviewed to define the spectrum of human touch perception and the fidelity requirements of an ideal haptic interface. Mechanical design and control literature was reviewed to translate the psychophysical requirements to engineering specification. High-fidelity haptic forceps were then developed through an iterative process between engineering and surgery. The forceps are a modular device that integrate with a haptic hand controller to add force feedback for tool actuation in telerobotic or virtual surgery. Their overall length is 153 mm and their mass is 125 g. A contact-free voice coil actuator generates force feedback at frequencies up to 800 Hz. Maximum force output is 6 N (2N continuous) and the force resolution is 4 mN. The forceps employ a contact-free magnetic position sensor as well as micro-machined accelerometers to measure opening/closing acceleration. Position resolution is 0.6 microm with 1.3 microm RMS noise. The forceps can simulate stiffness greater than 20N/mm or impedances smaller than 15 g with no noticeable haptic artifacts or friction. As telerobotic surgery evolves, haptics will play an increasingly important role. Copyright 2006 John Wiley & Sons, Ltd.

Transient Resonance Raman Spectroscopy of a Light-Driven Sodium-Ion-Pump Rhodopsin from Indibacter alkaliphilus.

PubMed

Kajimoto, Kousuke; Kikukawa, Takashi; Nakashima, Hiroki; Yamaryo, Haruki; Saito, Yuta; Fujisawa, Tomotsumi; Demura, Makoto; Unno, Masashi

2017-05-04

Sodium-ion-pump rhodopsin (NaR) is a microbial rhodopsin that transports Na + during its photocycle. Here we explore the photocycle mechanism of NaR from Indibacter alkaliphilus with transient absorption and transient resonance Raman spectroscopy. The transient absorption data indicate that the photocycle of NaR is K (545 nm) → L (490 nm)/M (420 nm) → O 1 (590 nm) → O 2 (560 nm) → NaR, where the L and M are formed as equilibrium states. The presence of K, L, M, and O intermediates was confirmed by the resonance Raman spectra with 442 and 532 nm excitation. The main component of the transient resonance Raman spectra was due to L which contains a 13-cis retinal protonated Schiff base. The presence of an enhanced hydrogen out-of-plane band as well as its sensitivity to the H/D exchange indicate that the retinal chromophore is distorted near the Schiff base region in L. Moreover, the retinal Schiff base of the L state forms a hydrogen bond that is stronger than that of the dark state. These observations are consistent with a Na + pumping mechanism that involves a proton transfer from the retinal Schiff base to a key aspartate residue (Asp116 in Krokinobacter eikastus rhodopsin 2) in the L/M states.

Working Ni-Mn-Ga Single Crystals in a Magnetic Field Against a Spring Load

NASA Astrophysics Data System (ADS)

Lindquist, P. G.; Müllner, P.

2015-03-01

This research characterizes ferromagnetic shape memory elements for use as mechanical actuators. A single crystal of Ni-Mn-Ga was pre-strained in compression from 0 to 6 % and then the shape was recovered with a magnetic field perpendicular to the loading direction while working against a pair of springs. The magnetic field was raised from 0 to 0.64 MA/m and then reduced to zero field. Eight pairs of springs with combined spring constants ranging from 14.3 to 269.4 N/mm were used. When the magnetic field was on, the sample expanded against the springs due to magnetic field-induced strain. When the magnetic field was turned off, the springs compressed the sample back to the initial size before the next cycle. During each cycle, force and displacement were measured and the specific work was computed. Specific work increased with the applied magnetic field and the pre-strain, with a maximum of 14 kJ/m3 at 4.5 % pre-strain and 0.64 MA/m. This value is five times less than the values suggested in the literature which were inferred from stress-strain curves measured under various magnetic fields. The spring prescribes the load-displacement path of the magnetic shape memory element and controls the work output of the actuator.

Decolorization of Congo Red by Phanerochaete chrysosporium: the role of biosorption and biodegradation.

PubMed

Bosco, Francesca; Mollea, Chiara; Ruggeri, Bernardo

2017-10-01

The degradation of Congo Red by means of Phanerochaete chrysosporium BKM-F-1767 is reported in this work. Solid and liquid cultures have been prepared to evaluate in vivo biodegradation as well as the role of biosorption phenomena on mycelium. Moreover, in vitro tests have been performed to define the influence of MnP on dye decolorization. P. chrysosporium, cultivated on Malt Extract Agar in the presence of Congo Red 0.005% (w/v), has shown good growth and the ability to decolorize the dye in the 25-39°C temperature range. It has also been cultivated in a low NMM liquid medium with the aforementioned dye concentration in immobilized stationary cultures inducted for Lignin Peroxidase (LiP) and Manganese Peroxidase (MnP) production. Congo Red was absorbed on the biomass and then decolorized (93% and 85% for the LiP and MnP cultures, respectively). The cultures with added Congo Red have shown a higher MnP synthesis rate than a control without the dye. The enzymatic degradation of Congo Red has also been investigated by means of the extracellular fluid for different MnP activities (0-300 IU/l); the decolorization percentage has been found to be clearly related to the enzyme concentration up to a value of about 200 IU/l.

Superconducting and magneto-transport properties of BiS{sub 2} based superconductor PrO{sub 1-x}F{sub x}BiS{sub 2} (x = 0 to 0.9)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jha, Rajveer; Kishan, Hari; Awana, V. P. S., E-mail: awana@mail.npindia.org

We report superconducting properties of PrO{sub 1-x}F{sub x}BiS{sub 2} compounds, synthesized by the vacuum encapsulation technique. The synthesized PrO{sub 1-x}F{sub x}BiS{sub 2} (x = 0.1, 0.3, 0.5, 0.7, and 0.9) samples are crystallized in a tetragonal P4/nmm space group. Both transport and DC magnetic susceptibility measurements showed bulk superconductivity below 4 K. The maximum T{sub c} is obtained for x = 0.7 sample. Under applied magnetic field, both T{sub c}{sup onset} and T{sub c} (ρ = 0) decrease to lower temperatures. We estimated highest upper critical field [H{sub c2}(0)] for PrO{sub 0.3}F{sub 0.7}BiS{sub 2} sample to be above 4 T (Tesla). The thermally activated flux flow activation energymore » (U{sub 0}) is estimated 54.63 meV in 0.05 T field for PrO{sub 0.3}F{sub 0.7}BiS{sub 2} sample. Hall measurement results showed that electron charge carriers are the dominating ones in these compounds. Thermoelectric effects (Thermal conductivity and Seebeck coefficient) data suggest strong electron-electron correlations in this material.« less

Optical Detection of Ketoprofen by Its Electropolymerization on an Indium Tin Oxide-Coated Optical Fiber Probe.

PubMed

Bogdanowicz, Robert; Niedziałkowski, Paweł; Sobaszek, Michał; Burnat, Dariusz; Białobrzeska, Wioleta; Cebula, Zofia; Sezemsky, Petr; Koba, Marcin; Stranak, Vitezslav; Ossowski, Tadeusz; Śmietana, Mateusz

2018-04-27

In this work an application of optical fiber sensors for real-time optical monitoring of electrochemical deposition of ketoprofen during its anodic oxidation is discussed. The sensors were fabricated by reactive magnetron sputtering of indium tin oxide (ITO) on a 2.5 cm-long core of polymer-clad silica fibers. ITO tuned in optical properties and thickness allows for achieving a lossy-mode resonance (LMR) phenomenon and it can be simultaneously applied as an electrode in an electrochemical setup. The ITO-LMR electrode allows for optical monitoring of changes occurring at the electrode during electrochemical processing. The studies have shown that the ITO-LMR sensor’s spectral response strongly depends on electrochemical modification of its surface by ketoprofen. The effect can be applied for real-time detection of ketoprofen. The obtained sensitivities reached over 1400 nm/M (nm·mg −1 ·L) and 16,400 a.u./M (a.u.·mg −1 ·L) for resonance wavelength and transmission shifts, respectively. The proposed method is a valuable alternative for the analysis of ketoprofen within the concentration range of 0.25⁻250 μg mL −1 , and allows for its determination at therapeutic and toxic levels. The proposed novel sensing approach provides a promising strategy for both optical and electrochemical detection of electrochemical modifications of ITO or its surface by various compounds.

The Transition of High-Resolution NASA MODIS Sea Surface Temperatures into the WRF Environmental Modeling System

NASA Technical Reports Server (NTRS)

Case, Jonathan L.; Jedlove, Gary J.; Santos, Pablo; Medlin, Jeffrey M.; Rozumalski, Robert A.

2009-01-01

The NASA Short-term Prediction Research and Transition (SPoRT) Center has developed a Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature (SST) composite at 2-km resolution that has been implemented in version 3 of the National Weather Service (NWS) Weather Research and Forecasting (WRF) Environmental Modeling System (EMS). The WRF EMS is a complete, full physics numerical weather prediction package that incorporates dynamical cores from both the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM). The installation, configuration, and execution of either the ARW or NMM models is greatly simplified by the WRF EMS to encourage its use by NWS Weather Forecast Offices (WFOs) and the university community. The WRF EMS is easy to run on most Linux workstations and clusters without the need for compilers. Version 3 of the WRF EMS contains the most recent public release of the WRF-NMM and ARW modeling system (version 3 of the ARW is described in Skamarock et al. 2008), the WRF Pre-processing System (WPS) utilities, and the WRF Post-Processing program. The system is developed and maintained by the NWS National Science Operations Officer Science and Training Resource Coordinator. To initialize the WRF EMS with high-resolution MODIS SSTs, SPoRT developed the composite product consisting of MODIS SSTs over oceans and large lakes with the NCEP Real-Time Global (RTG) filling data over land points. Filling the land points is required due to minor inconsistencies between the WRF land-sea mask and that used to generate the MODIS SST composites. This methodology ensures a continuous field that adequately initializes all appropriate arrays in WRF. MODIS composites covering the Gulf of Mexico, western Atlantic Ocean and the Caribbean are generated daily at 0400, 0700, 1600, and 1900 UTC corresponding to overpass times of the NASA Aqua and Terra polar orbiting satellites. The MODIS SST product is output in gridded binary-1 (GRIB-1) data

Effect of surface chemistry on the rate of osseointegration of sintered porous-surfaced Ti-6Al-4V implants.

PubMed

Taché, Alex; Gan, Lu; Deporter, Douglas; Pilliar, Robert M

2004-01-01

The effect of adding a thin sol-gel-formed calcium phosphate (CaP) coating to sintered porous-surfaced titanium alloy (Ti-6Al-4V) implants on rates of initial bone ingrowth was investigated. Control implants (as manufactured) and similar implants with sol-gel CaP coatings were randomly placed in distal femoral rabbit condyles (1 implant/leg). After healing for 6, 9, 12, and 16 days, 8 of 10 rabbits in each time group were assessed for maximum implant pullout force (N) and interface stiffness (N/mm). Selected extracted implants also were examined by secondary electron imaging to characterize affected surfaces. The implants of the remaining 2 rabbits in each group were examined by backscattered scanning electron microscopy (BSEM). Significantly greater pullout forces and interface stiffness were found for CaP-coated implants at 6 and 9 days. At 6 days, BSEM revealed bone ingrowth on CaP-coated implants but not on control implants. Secondary electron imaging and BSEM observations also suggested greater bone ingrowth with CaP-coated porous implants at 9, 12, and 16 days. Sol-gel-formed CaP surface films significantly enhance rates of bone ingrowth into sintered porous-surfaced implants. This surface treatment may have a number of clinical benefits, including shortening the period prior to functional loading of such implants and improving treatment outcomes in situations of poor bone quality and/or quantity. (More than 50 references).

Cryogenic actuator testing for the SAFARI ground calibration setup

NASA Astrophysics Data System (ADS)

de Jonge, C.; Eggens, M.; Nieuwenhuizen, A. C. T.; Detrain, A.; Smit, H.; Dieleman, P.

2012-09-01

For the on-ground calibration setup of the SAFARI instrument cryogenic mechanisms are being developed at SRON Netherlands Institute for Space Research, including a filter wheel, XYZ-scanner and a flipmirror mechanism. Due to the extremely low background radiation requirement of the SAFARI instrument, all of these mechanisms will have to perform their work at 4.5 Kelvin and low-dissipative cryogenic actuators are required to drive these mechanisms. In this paper, the performance of stepper motors, piezoelectric actuators and brushless DC-motors as cryogenic actuators are compared. We tested stepper motor mechanical performance and electrical dissipation at 4K. The actuator requirements, test setup and test results are presented. Furthermore, design considerations and early performance tests of the flipmirror mechanism are discussed. This flipmirror features a 102 x 72 mm aluminum mirror that can be rotated 45°. A Phytron stepper motor with reduction gearbox has been chosen to drive the flipmirror. Testing showed that this motor has a dissipation of 49mW at 4K with a torque of 60Nmm at 100rpm. Thermal modeling of the flipmirror mechanism predicts that with proper thermal strapping the peak temperature of the flipmirror after a single action will be within the background level requirements of the SAFARI instrument. Early tests confirm this result. For low-duty cycle operations commercial stepper motors appear suitable as actuators for test equipment in the SAFARI on ground calibration setup.

Range-Specific High-resolution Mesoscale Model Setup

NASA Technical Reports Server (NTRS)

Watson, Leela R.

2013-01-01

This report summarizes the findings from an AMU task to determine the best model configuration for operational use at the ER and WFF to best predict winds, precipitation, and temperature. The AMU ran test cases in the warm and cool seasons at the ER and for the spring and fall seasons at WFF. For both the ER and WFF, the ARW core outperformed the NMM core. Results for the ER indicate that the Lin microphysical scheme and the YSU PBL scheme is the optimal model configuration for the ER. It consistently produced the best surface and upper air forecasts, while performing fairly well for the precipitation forecasts. Both the Ferrier and Lin microphysical schemes in combination with the YSU PBL scheme performed well for WFF in the spring and fall seasons. The AMU has been tasked with a follow-on modeling effort to recommended local DA and numerical forecast model design optimized for both the ER and WFF to support space launch activities. The AMU will determine the best software and type of assimilation to use, as well as determine the best grid resolution for the initialization based on spatial and temporal availability of data and the wall clock run-time of the initialization. The AMU will transition from the WRF EMS to NU-WRF, a NASA-specific version of the WRF that takes advantage of unique NASA software and datasets. 37

Mechanical characterization and comparison of energy storage and return prostheses.

PubMed

Rigney, Stacey M; Simmons, Anne; Kark, Lauren

2017-03-01

The suitability of finite element analysis (FEA) for standardizing the mechanical characterization of energy storage and return (ESAR) prostheses was investigated. A methodology consisting of both experimental and numerical analysis was proposed and trialed for the Vari-flex ® Modular TM , Flex-foot Cheetah and Cheetah Xtreme by Össur ® and a 1E90 Sprinter by Ottobock ® . Gait analysis was conducted to determine suitable orientation angles for non-destructive testing (NDT) of the ESAR prostheses followed by a quasi-static inverse FEA procedure within COMSOL Multiphysics ® , where the NDT conditions were replicated to determine the homogenized material properties of the prostheses. The prostheses' loading response under bodyweight for an 80kg person was then simulated, using both Eigenfrequency and time-dependent analysis. The apparent stiffness under bodyweight was determined to be 94.7, 48.6, 57.4 and 65.0Nmm -1 for the Vari-flex ® Modular TM , Flex-foot Cheetah, Cheetah Xtreme and 1E90 Sprinter, respectively. Both the energy stored and returned by the prostheses varied negatively with stiffness, yet the overall efficiency of the prostheses were similar, at 52.7, 52.0, 51.7 and 52.4% for the abovementioned prostheses. The proposed methodology allows the standardized assessment and comparison of ESAR prostheses without the confounding influences of subject-specific gait characteristics. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Rapid bonding of Pyrex glass microchips.

PubMed

Akiyama, Yoshitake; Morishima, Keisuke; Kogi, Atsuna; Kikutani, Yoshikuni; Tokeshi, Manabu; Kitamori, Takehiko

2007-03-01

A newly developed vacuum hot press system has been specially designed for the thermal bonding of glass substrates in the fabrication process of Pyrex glass microchemical chips. This system includes a vacuum chamber equipped with a high-pressure piston cylinder and carbon plate heaters. A temperature of up to 900 degrees C and a force of as much as 9800 N could be applied to the substrates in a vacuum atmosphere. The Pyrex substrates bonded with this system under different temperatures, pressures, and heating times were evaluated by tensile strength tests, by measurements of thickness, and by observations of the cross-sectional shapes of the microchannels. The optimal bonding conditions of the Pyrex glass substrates were 570 degrees C for 10 min under 4.7 N/mm(2) of applied pressure. Whereas more than 16 h is required for thermal bonding with a conventional furnace, the new system could complete the whole bonding processes within just 79 min, including heating and cooling periods. Such improvements should considerably enhance the production rate of Pyrex glass microchemical chips. Whereas flat and dust-free surfaces are required for conventional thermal bonding, especially without long and repeated heating periods, our hot press system could press a fine dust into glass substrates so that even the areas around the dust were bonded. Using this capability, we were able to successfully integrate Pt/Ti thin film electrodes into a Pyrex glass microchip.

Biomechanical Properties of a Novel Biodegradable Magnesium-Based Interference Screw

PubMed Central

Ezechieli, Marco; Meyer, Hanna; Lucas, Arne; Helmecke, Patrick; Becher, Christoph; Calliess, Tilman; Windhagen, Henning; Ettinger, Max

2016-01-01

Magnesium-based interference screws may be an alternative in anterior/posterior cruciate ligament reconstruction. The well-known osteoconductive effects of biodegradable magnesium alloys may be useful. It was the purpose of this study to evaluate the biomechanical properties of a magnesium based interference screw and compare it to a standard implant. A MgYREZr-alloy interference screw and a standard implant (Milagro®; De Puy Mitek, Raynham, MA, USA) were used for graft fixation. Specimens were placed into a tensile loading fixation of a servohydraulic testing machine. Biomechanical analysis included pretensioning of the constructs at 20 N for 1 min following cyclic pretensioning of 20 cycles between 20 and 60 N. Biomechanical elongation was evaluated with cyclic loading of 1000 cycles between 50 and 200 N at 0.5 Hz. Maximum load to failure was 511.3±66.5 N for the Milagro® screw and 529.0±63.3 N for magnesium-based screw (ns, P=0.57). Elongations after preload, during cyclical loading and during failure load were not different between the groups (ns, P>0.05). Stiffness was 121.1±13.8 N/mm for the magnesium-based screw and 144.1±18.4 for the Milagro® screw (ns, P=0.32). MgYREZr alloy interference screws show comparable results in biomechanical testing to standard implants and may be an alternative for anterior cruciate reconstruction in the future. PMID:27433303

Asymmetric Outer Bow Length and Cervical Headgear Force System: 3D Analysis Using Finite Element Method.

PubMed

Geramy, Allahyar; Hassanpour, Mehdi; Emadian Razavi, Elham Sadat

2015-03-01

This study sought to assess distal and lateral forces and moments of asymmetric headgears by variable outer bow lengths. Four 3D finite element method (FEM) models of a cervical headgear attached to the maxillary first molars were designed in SolidWorks 2010 software and transferred to ANSYS Workbench ver. 11 software. Models contained the first molars, their periodontal ligament (PDL), cancellous and cortical bones, a mesiodistal slice of the maxillae and the headgear. Models were the same except for the outer bow length in headgears. The headgear was symmetric in model 1. In models 2 to 4, the headgears were asymmetric in length with differences of 5mm, 10mm and 15mm, respectively. A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was calculated trigonometrically using data from a volunteer. The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm). As the difference in outer bow length became greater, asymmetric effects increased. Greater distal force in the longer arm side was associated with greater lateral force towards the shorter arm side and more net yawing moment. A difference range of 1mm to 15 mm of length in cervical headgear can be considered as a safe length of outer bow shortening in clinical use.

Magnetic order close to superconductivity in the iron-based layered LaO1-xFxFeAs systems

NASA Astrophysics Data System (ADS)

de La Cruz, Clarina; Huang, Q.; Lynn, J. W.; Li, Jiying; , W. Ratcliff, II; Zarestky, J. L.; Mook, H. A.; Chen, G. F.; Luo, J. L.; Wang, N. L.; Dai, Pengcheng

2008-06-01

Following the discovery of long-range antiferromagnetic order in the parent compounds of high-transition-temperature (high-Tc) copper oxides, there have been efforts to understand the role of magnetism in the superconductivity that occurs when mobile `electrons' or `holes' are doped into the antiferromagnetic parent compounds. Superconductivity in the newly discovered rare-earth iron-based oxide systems ROFeAs (R, rare-earth metal) also arises from either electron or hole doping of their non-superconducting parent compounds. The parent material LaOFeAs is metallic but shows anomalies near 150K in both resistivity and d.c. magnetic susceptibility. Although optical conductivity and theoretical calculations suggest that LaOFeAs exhibits a spin-density-wave (SDW) instability that is suppressed by doping with electrons to induce superconductivity, there has been no direct evidence of SDW order. Here we report neutron-scattering experiments that demonstrate that LaOFeAs undergoes an abrupt structural distortion below 155K, changing the symmetry from tetragonal (space group P4/nmm) to monoclinic (space group P112/n) at low temperatures, and then, at ~137K, develops long-range SDW-type antiferromagnetic order with a small moment but simple magnetic structure. Doping the system with fluorine suppresses both the magnetic order and the structural distortion in favour of superconductivity. Therefore, like high-Tc copper oxides, the superconducting regime in these iron-based materials occurs in close proximity to a long-range-ordered antiferromagnetic ground state.

Hyaluronan-decorated liposomes as drug delivery systems for cutaneous administration.

PubMed

Franzé, Silvia; Marengo, Alessandro; Stella, Barbara; Minghetti, Paola; Arpicco, Silvia; Cilurzo, Francesco

2018-01-15

The work aimed to evaluate the feasibility to design hyaluronic acid (HA) decorated flexible liposomes to enhance the skin penetration of nifedipine. Egg phosphatidylcholine (e-PC) based transfersomes (Tween 80) and transethosomes (ethanol) were prepared. HA was reacted with 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (HA-DPPE) and two molar ratios (0.5 and 3%) of conjugate with respect to e-PC were tested. The presence of HA significantly increased the packing order of the bilayer (as verified by differential scanning calorimetry), reducing both the encapsulation efficiency and the flexibility of the decorated liposomes in a dose-dependent manner. In fact, at the highest HA content the constant of deformability (K, N/mm) increased and the carriers remained on the skin surface after topical application. The stiffening effect of HA was counterbalanced by the addition of ethanol as fluidizing agent that allowed to maintain the highest HA concentration, meanwhile reducing the K value of the vesicles. HA-transethosomes allowed a suitable nifedipine permeation (J ∼ 30 ng/cm 2 /h) and significantly improved the drug penetration, favouring the formation of a drug depot in the epidermis. These data suggest the potentialities of HA-transethosomes as drug delivery systems intended for the treatment of cutaneous pathologies and underline the importance of studying the effect of surface functionalization on carrier deformability to rationalize the design of such systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Drilling the near cortex with elongated figure-of-8 holes to reduce the stiffness of a locking compression plate construct.

PubMed

Chen, Jerry Yongqiang; Zhou, Zhihong; Ang, Benjamin Fu Hong; Yew, Andy Khye Soon; Chou, Siaw Meng; Chia, Shi-Lu; Koh, Joyce Suang Bee; Howe, Tet Sen

2015-12-01

To compare the stiffness of locking compression plate (LCP) constructs with or without drilling the near cortex with elongated figure-of-8 holes. 24 synthetic bones were sawn to create a 10-mm gap and were fixed with a 9-hole 4.5-mm narrow LCP. In 12 bones, the near cortex of the adjacent holes to the LCP holes was drilled to create elongated figure-of-8 holes before screw insertion. The stiffness of LCP constructs under axial loading or 4-point bending was assessed by (1) dynamic quasi-physiological testing for fatigue strength, (2) quasi-static testing for stiffness, and (3) testing for absolute strength to failure. None of the 24 constructs had subcatastrophic or catastrophic failure after 10 000 cycles of fatigue loading (p=1.000). The axial stiffness reduced by 16% from 613±62 to 517±44 N/mm (p=0.012) in the case group, whereas the bending stiffness was 16±1 Nm2 in both groups (p=1.000). The maximum axial load to catastrophic failure was 1596±84 N for the control group and 1627±48 N for the case group (p=0.486), whereas the maximum bending moment to catastrophic failure was 79±12 and 80±10 Nm, respectively (p=0.919). Drilling the near cortex with elongated figure-of-8 holes reduces the axial stiffness of the LCP construct, without compromising its bending stiffness or strength.

Joining sheet aluminum AA6061-T4 to cast magnesium AM60B by vaporizing foil actuator welding: Input energy, interface, and strength

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Bert; Vivek, Anupam; Daehn, Glenn S.

Dissimilar joining of sheet aluminum AA6061-T4 to cast magnesium AM60B was achieved by vaporizing foil actuator welding (VFAW). Three input energy levels were used (6, 8, and 10 kJ), and as a trend, higher input energies resulted in progressively higher flyer velocities, more pronounced interfacial wavy features, larger weld zones, higher peel strengths, and higher peel energies. In all cases, weld cross section revealed a soundly bonded interface characterized by well-developed wavy features and lack of voids and continuous layers of intermetallic compounds (IMCs). At 10 kJ input energy, flyer speed of 820 m/s, peel strength of 22.4 N/mm, andmore » peel energy of 5.2 J were obtained. In lap-shear, failure occurred in AA6061- T4 flyer at 97% of the base material’s peak tensile load. Peel samples failed along the weld interface, and the AM60B-side of the fracture surface showed thin, evenly-spaced lines of Al residuals which had been torn out of the base AA6061-T4 in a ductile fashion and transferred over to the AM60B side, indicating very strong AA6061-T4/AM60B bond in these areas. Furthermore, this work demonstrates VFAW’s capability in joining dissimilar lightweight metals such as Al/Mg, which is expected to be a great enabler in the ongoing push for vehicle weight reduction.« less

Pilot study of bipolar radiofrequency-induced anastomotic thermofusion-exploration of therapy parameters ex vivo.

PubMed

Winter, Hanno; Holmer, Christoph; Buhr, Heinz-Johannes; Lindner, Gerd; Lauster, Roland; Kraft, Marc; Ritz, Jörg-Peter

2010-01-01

Vessel sealing has been well-established in surgical practice in recent years. Bipolar radiofrequency-induced thermofusion (BIRTH) of intestinal tissue might replace traditionally used staples or sutures in the near future. In this experimental study, the influence of compressive pressure, fusion temperature, and duration of heating on the quality of intestinal anastomosis was investigated to obtain the relevant major parameters for the in vivo use of this system. An experimental setup for a closed-loop temperature-controlled bipolar radiofrequency-induced thermofusion of porcine intestinal tissue was developed. Twenty-four colon samples were harvested from nine different Saalower-Kräuter pigs and then anastomosed altering compressive pressure on five different levels to explore its influence on anastomotic bursting pressure. The anastomotic bursting strength depends on the compressive pressure applied to the colonic fusion site. An optimal interval of compressive pressure (CP = 1.125 N/mm(2)) in respect of a high amount of burst pressure was detected. A correlation (r = 0.54, p = 0.015) of burst pressure to delta compression indicated that increasing colonic wall thickness probably strengthens the anastomotic fusion. This study is a first step to enlighten the major parameters of tissue fusion, though effects and interactions of various main parameters of bipolar radiofrequency-induced thermofusion of colonic tissue remain unclear. Further studies exploring the main effects and interactions of tissue and process parameters to the quality of the fusion site have to follow.

Influence of artificial saliva on abrasive wear and microhardness of dental composites filled with nanoparticles.

PubMed

Mayworm, Camila D; Camargo, Sérgio S; Bastian, Fernando L

2008-09-01

The aim of this study is to compare the wear resistance and hardness of two dental nanohybrid composites and to evaluate the influence of artificial saliva storage on those properties. Specimens were made from two commercial nanohybrid dental composites (Esthet-X-Dentsply and Filtek Supreme-3M). Abrasion tests were carried out in a ball-cratering machine (three body abrasion) and microscopic analysis of the wear surfaces was made using optical and scanning electron microscopy; hardness was quantified by Vickers hardness test. Those tests were repeated on specimens stored in artificial saliva. Results show that the wear rate of the studied materials is within 10(-7)mm(3)/Nmm range, one of the composites presenting wear rate twice as large as the other. After storage in artificial saliva, the wear resistance increases for both materials. Microhardness of the composites is around 52 and 64HV, Esthet-X presents higher hardness values than Filtek Supreme. After storage in artificial saliva, the microhardness of both materials decreases. Data were analyzed using ANOVA test, p < or = 0.05. Artificial saliva storage increases the materials' wear resistance, suggesting that in both materials bulk post-cure takes place and saliva absorption occurs only on the surface of the composites. This effect was confirmed by comparing the Vickers hardness before and after artificial saliva treatment and FTIR analyses. Surface microhardness of the composites decreases after storage in artificial saliva whereas bulk microhardness of the materials increases.

Effect of amorphous silica ash used as a partial replacement for cement on the compressive and flexural strengths cement mortar.

NASA Astrophysics Data System (ADS)

Usman, Aliyu; Ibrahim, Muhammad B.; Bala, Nura

2018-04-01

This research is aimed at investigating the effect of using amorphous silica ash (ASA) obtained from rice husk as a partial replacement of ordinary Portland cement (OPC) on the compressive and flexural strength of mortar. ASA was used in partial replacement of ordinary Portland cement in the following percentages 2.5 percent, 5 percent, 7.5 percent and 10 percent. These partial replacements were used to produce Cement-ASA mortar. ASA was found to contain all major chemical compounds found in cement with the exception of alumina, which are SiO2 (91.5%), CaO (2.84%), Fe2O3 (1.96%), and loss on ignition (LOI) was found to be 9.18%. It also contains other minor oxides found in cement. The test on hardened mortar were destructive in nature which include flexural strength test on prismatic beam (40mm x 40mm x 160mm) and compressive strength test on the cube size (40mm x 40mm, by using the auxiliary steel plates) at 2,7,14 and 28 days curing. The Cement-ASA mortar flexural and compressive strengths were found to be increasing with curing time and decreases with cement replacement by ASA. It was observed that 5 percent replacement of cement with ASA attained the highest strength for all the curing ages and all the percentage replacements attained the targeted compressive strength of 6N/mm2 for 28 days for the cement mortar

Improving the mechanical properties of nano-hydroxyapatite

NASA Astrophysics Data System (ADS)

Khanal, Suraj Prasad

Hydroxyapatite (HAp) is an ideal bioactive material that is used in orthopedics. Chemical composition and crystal structure properties of HAp are similar to the natural bone hence it promotes bone growth. However, its mechanical properties of synthetic HAp are not sufficient for major load-bearing bone replacement. The potential of improving the mechanical properties of synthetic hydroxyapatite (HAp) by incorporating carboxyl functionalized single walled carbon nanotubes (CfSWCNT) and polymerized epsilon-caprolactam (nylon) is studied. The fracture toughness, tensile strength, Young's modulus, stiffness and fracture energy were studied for a series of HAp samples with CfSWCNT concentrations varying from 0 to 1.5 wt. % without, and with nylon addition. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC) were used to characterize the samples. The fracture toughness and tensile test was performed under the standard protocol of ASTM D5045 and ASTM D638-02a respectively. Reproducible maximum values of (3.60 +/- 0.3) MPa.m1/2 for fracture toughness and 65.38 MPa for tensile strength were measured for samples containing 1 wt. % CfSWCNT and nylon. The Young's modulus, stiffness and fracture energy of the samples are 10.65 GPa, 1482.12 N/mm, and 644 J/m2 respectively. These values are comparable to those of the cortical bone. Further increase of the CfSWCNT content results to a decreased fracture toughness and tensile strength and formation of a secondary phase.

A Chitosan Coating Containing Essential Oil from Origanum vulgare L. to Control Postharvest Mold Infections and Keep the Quality of Cherry Tomato Fruit

PubMed Central

Barreto, Tainá A.; Andrade, Sonalle C. A.; Maciel, Janeeyre F.; Arcanjo, Narciza M. O.; Madruga, Marta S.; Meireles, Bruno; Cordeiro, Ângela M. T.; Souza, Evandro L.; Magnani, Marciane

2016-01-01

The efficacy of an edible chitosan coating (CHI; 4 mg/mL) and Origanum vulgare L. essential oil (OVEO; 1.25 μL/mL) for maintaining the quality of cherry tomato fruit during storage at room (25°C; 12 days) and cold (12°C; 24 days) temperatures was assessed. CHI and OVEO in combination showed in vitro fungicidal effects against R. stolonifer and Aspergillus niger. CHI-OVEO coating reduced the incidence of black mold and soft rot caused by these fungi in artificially contaminated cherry tomato fruit during storage at both temperatures. CHI-OVEO coating delayed the appearance of the first visible signs of black mold and soft rot in artificially contaminated cherry tomato fruit stored at room temperature by 6 days and by more than 9 days in those stored at cold temperature. At the end of storage at room and cold temperature fruit coated with CHI-OVEO showed higher firmness (>2 N/mm) and lower weight loss (>2%) compared to uncoated tomato fruit. CHI-OVEO coating delayed the decrease of lycopene, ascorbic citric acid, glucose and fructose during the storage time assessed at room or cold temperatures. The increase of catechin, myricetin, caffeic and syringic acids was higher (1–9 mg/g) in cherry tomato fruit coated with CHI-OVEO compared to uncoated fruit during the storage at both temperatures studied. CHI-OVEO coating is a feasible treatment for maintaining the storage quality of cherry tomato fruit. PMID:27877156

Joining sheet aluminum AA6061-T4 to cast magnesium AM60B by vaporizing foil actuator welding: Input energy, interface, and strength

DOE PAGES

Liu, Bert; Vivek, Anupam; Daehn, Glenn S.

2017-09-19

Dissimilar joining of sheet aluminum AA6061-T4 to cast magnesium AM60B was achieved by vaporizing foil actuator welding (VFAW). Three input energy levels were used (6, 8, and 10 kJ), and as a trend, higher input energies resulted in progressively higher flyer velocities, more pronounced interfacial wavy features, larger weld zones, higher peel strengths, and higher peel energies. In all cases, weld cross section revealed a soundly bonded interface characterized by well-developed wavy features and lack of voids and continuous layers of intermetallic compounds (IMCs). At 10 kJ input energy, flyer speed of 820 m/s, peel strength of 22.4 N/mm, andmore » peel energy of 5.2 J were obtained. In lap-shear, failure occurred in AA6061- T4 flyer at 97% of the base material’s peak tensile load. Peel samples failed along the weld interface, and the AM60B-side of the fracture surface showed thin, evenly-spaced lines of Al residuals which had been torn out of the base AA6061-T4 in a ductile fashion and transferred over to the AM60B side, indicating very strong AA6061-T4/AM60B bond in these areas. Furthermore, this work demonstrates VFAW’s capability in joining dissimilar lightweight metals such as Al/Mg, which is expected to be a great enabler in the ongoing push for vehicle weight reduction.« less

Electronic structures and superconductivity in LuTE2Si2 phases (TE = d-electron transition metal)

NASA Astrophysics Data System (ADS)

Samsel-Czekała, M.; Chajewski, G.; Wiśniewski, P.; Romanova, T.; Hackemer, A.; Gorzelniak, R.; Pikul, A. P.; Kaczorowski, D.

2018-05-01

In the course of our search for unconventional superconductors amidst the 1:2:2 phases, we have re-investigated the LuTE2Si2 compounds with TE = Fe, Co, Ni, Ru, Pd and Pt. In this paper, we present the results of our fully relativistic ab initio calculations of the band structures, performed using the full-potential local-orbital code. The theoretical data are supplemented by the results of low-temperature electrical transport and specific heat measurements performed down to 0.35 K. All the materials studied but LuPt2Si2 crystallize with the body-centered tetragonal ThCr2Si2-type structure (space group I4/mmm). Their Fermi surfaces exhibit a three-dimensional multi-band character. In turn, the Pt-bearing compound adopts the primitive tetragonal CaBe2Ge2-type structure (space group P4/nmm), and its Fermi surface consists of predominantly quasi-two-dimensional sheets. Bulk superconductivity was found only in LuPd2Si2 and LuPt2Si2 (independent of the structure type and dimensionality of the Fermi surface). The key superconducting characteristics indicate a fully-gapped BCS type character. Though the electronic structure of LuFe2Si2 closely resembles that of the unconventional superconductor YFe2Ge2, this Lu-based silicide exhibits neither superconductivity nor spin fluctuations at least down to 0.35 K.

Modeling Diffusion as a Result of Observing Salinity, Water Temperature and Mixing of the Norwalk River into Long Island Sound

NASA Astrophysics Data System (ADS)

Giuliano, A. L.; Gillotte, C. N.; Wooldridge, T. R.

2016-02-01

This project investigates the space and time variability of salinity and temperature in the lower Norwalk River using a one-dimensional numerical model. The project uses surface measurements taken at two locations, one at the Norwalk Maritime Museum (NMM) and the other at the mouth of the river as it drains into the Norwalk Islands region adjacent to Long Island Sound (LIS). The model covers a relatively small distance of 1-2km. The size of the upriver neck and the first buoy is approximately five times smaller than the mouth between the second buoy site and Peach Island. The instrumentation will be responsible for generally characterizing the thermal physics occurring at the river-ocean environment. A one-dimensional advection-diffusion model will be used to simulate results. The data points will measure the salinity, water temperature, and pressure during a series of deployments in the river during a three-season period between 2013 and 2014. Further processes will ultimately show the overall advection occurring in the river. The upriver site is maintained by the Norwalk River Museum. A YSI XXX attached to a tether buoy is used to measure salinity and temperature at the surface.Preliminary results suggest typical temperature range at the upriver site is greater than at the mouth of the Norwalk River, and the daily peak temperature lag depends upon several factors, such as tidal state. The phenomenon of a salt wedge will also be considered.

Mechanical performance of cervical intervertebral body fusion devices: A systematic analysis of data submitted to the Food and Drug Administration.

PubMed

Peck, Jonathan H; Sing, David C; Nagaraja, Srinidhi; Peck, Deepa G; Lotz, Jeffrey C; Dmitriev, Anton E

2017-03-21

Cervical intervertebral body fusion devices (IBFDs) are utilized to provide stability while fusion occurs in patients with cervical pathology. For a manufacturer to market a new cervical IBFD in the United States, substantial equivalence to a cervical IBFD previously cleared by FDA must be established through the 510(k) regulatory pathway. Mechanical performance data are typically provided as part of the 510(k) process for IBFDs. We reviewed all Traditional 510(k) submissions for cervical IBFDs deemed substantially equivalent and cleared for marketing from 2007 through 2014. To reduce sources of variability in test methods and results, analysis was restricted to cervical IBFD designs without integrated fixation, coatings, or expandable features. Mechanical testing reports were analyzed and results were aggregated for seven commonly performed tests (static and dynamic axial compression, compression-shear, and torsion testing per ASTM F2077, and subsidence testing per ASTM F2267), and percentile distributions of performance measurements were calculated. Eighty-three (83) submissions met the criteria for inclusion in this analysis. The median device yield strength was 10,117N for static axial compression, 3680N for static compression-shear, and 8.6Nm for static torsion. Median runout load was 2600N for dynamic axial compression, 1400N for dynamic compression-shear, and ±1.5Nm for dynamic torsion. In subsidence testing, median block stiffness (Kp) was 424N/mm. The mechanical performance data presented here will aid in the development of future cervical IBFDs by providing a means for comparison for design verification purposes. Published by Elsevier Ltd.

Suprapubic track pressure and force--deformation measurements in a (live) human subject and in animal models post-mortem.

PubMed

Coveney, V A; Gepi-Attee, S; Gröver, D; Painter, D

2001-01-01

Tests have been performed on animal models shortly post-mortem and on a healthy human subject in order to obtain estimates of the forces which act on suprapubic urinary catheters and similar devices and to develop an abdominal wall simulator. Such data and test methods are required for the systematic design of suprapubic devices because of the dual need to maintain the functionality of devices and to avoid excessive pressure on soft body tissue which could lead to ischaemia and in turn necrosis. In the post-mortem animal models, electrical excitation was applied to the abdominal wall in order to stimulate muscle activity. Two types of transducers were used: a soft membrane transducer (SMT) for pressure measurement and novel instrumented 'tongs' to determine indentation stiffness characteristics in the suprapubic track or artificial pathway created for a device. The SMT has been extensively used in the urethras and bladders of human subjects while the tongs were built specifically for these tests. Only the well-established SMT was used with the human subject; a peak pressure of 22 kPa was obtained. In the animal models the pressure profile given by the SMT had a peak whose position corresponded well with the estimated location of the rectus muscle measured on the fixed tissue section. The peak value was 5.5 kPa, comparable with values likely to cause necrosis if maintained for more than 1 day. Remarkably consistent indentation stiffness values were obtained with the instrumented tongs; all values were close to 0.45 N/mm (33 kPa/mm).

Comparative biomechanical evaluation of a pin-sleeve transfixation system in cadaveric calf metacarpal bones.

PubMed

Brianza, Stefano; Vogel, Susan; Rothstock, Stephan; Thalhauser, Martin; Desrochers, Andrè; Boure, Ludovic

2013-01-01

To compare proximal fragment displacement and the peri-implant strain using a pin-sleeve cast (PSC) system and a transfixation pin cast (TPC) system on a cadaveric calf metacarpal bone fracture model. Experimental. Cadaveric calf metacarpal bones (n = 6 pairs). Paired samples were instrumented with either the TPC or the PSC systems. Strain gauges were applied proximal to the transfixation implants and the bones encased in cast material. The distal part of the construct was removed to mimic an unstable distal comminuted fracture. Constructs were fixed to the material testing machine and initially loaded in axial compression in their elastic range to determine construct stiffness. Constructs were loaded cyclically with a sinusoidal curve that increased until failure. Variables compared statistically between constructs were the initial construct stiffness and, at given load points, the mean metacarpal axial displacement in loading and unloading condition and mean axial strain. Initial construct mean ± SD axial stiffness was not significantly different between constructs (PSC: 689 ± 258; TPC: 879 ± 306 N/mm). There was no significant difference between either investigated displacements of metacarpal bones transfixed with PSC and those transfixed with TPC at all load points. The PSC constructs had a significant decrease in the recorded mean strain (502 ± 340 μstrain) compared to the TPC construct (1738 ± 2218 μstrain). The PSC significantly reduced peri-implant strain with comparable axial displacement to the TPC in cadaveric calf metacarpal bones. © Copyright 2012 by The American College of Veterinary Surgeons.

Self-locked aptamer probe mediated cascade amplification strategy for highly sensitive and selective detection of protein and small molecule.

PubMed

Li, Wei; Jiang, Wei; Wang, Lei

2016-10-12

In this work, a novel self-locked aptamer probe mediated cascade amplification strategy has been constructed for highly sensitive and specific detection of protein. First, the self-locked aptamer probe was designed with three functions: one was specific molecular recognition attributed to the aptamer sequence, the second was signal transduction owing to the transduction sequence, and the third was self-locking through the hybridization of the transduction sequence and part of the aptamer sequence. Then, the aptamer sequence specific recognized the target and folded into a three-way helix junction, leading to the release of the transduction sequence. Next, the 3'-end of this three-way junction acted as primer to trigger the strand displacement amplification (SDA), yielding a large amount of primers. Finally, the primers initiated the dual-exponential rolling circle amplification (DE-RCA) and generated numerous G-quadruples sequences. By inserting the fluorescent dye N-methyl mesoporphyrin IX (NMM), enhanced fluorescence signal was achieved. In this strategy, the self-locked aptamer probe was more stable to reduce the interference signals generated by the uncontrollable folding in unbounded state. Through the cascade amplification of SDA and DE-RCA, the sensitivity was further improved with a detection limit of 3.8 × 10(-16) mol/L for protein detection. Furthermore, by changing the aptamer sequence of the probe, sensitive and selective detection of adenosine has been also achieved, suggesting that the proposed strategy has good versatility and can be widely used in sensitive and selective detection of biomolecules. Copyright © 2016 Elsevier B.V. All rights reserved.

Asymmetric Outer Bow Length and Cervical Headgear Force System: 3D Analysis Using Finite Element Method

PubMed Central

Geramy, Allahyar; Hassanpour, Mehdi; Emadian Razavi, Elham sadat

2015-01-01

Objectives: This study sought to assess distal and lateral forces and moments of asymmetric headgears by variable outer bow lengths. Materials and Methods: Four 3D finite element method (FEM) models of a cervical headgear attached to the maxillary first molars were designed in SolidWorks 2010 software and transferred to ANSYS Workbench ver. 11 software. Models contained the first molars, their periodontal ligament (PDL), cancellous and cortical bones, a mesiodistal slice of the maxillae and the headgear. Models were the same except for the outer bow length in headgears. The headgear was symmetric in model 1. In models 2 to 4, the headgears were asymmetric in length with differences of 5mm, 10mm and 15mm, respectively. A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was calculated trigonometrically using data from a volunteer. Results: The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm). Conclusion: As the difference in outer bow length became greater, asymmetric effects increased. Greater distal force in the longer arm side was associated with greater lateral force towards the shorter arm side and more net yawing moment. Clinical Relevance: A difference range of 1mm to 15 mm of length in cervical headgear can be considered as a safe length of outer bow shortening in clinical use. PMID:26622275

Torque efficiency of square and rectangular archwires into 0.018 and 0.022 in. conventional brackets.

PubMed

Papageorgiou, Spyridon N; Sifakakis, Iosif; Doulis, Ioannis; Eliades, Theodore; Bourauel, Christoph

2016-01-01

The aim of this study was to compare the torque efficacy of square and rectangular wires in 0.018- and 0.022-in. conventionally ligated brackets. Brackets of the same prescription were evaluated in both slot dimensions. Identical acrylic resin models of the maxilla were bonded with the brackets and mounted on the Orthodontic Measurement and Simulation System. Ten 0.018 × 0.018 in., 0.018 × 0.022 in., and 0.018 × 0.025 in. stainless steel wires were evaluated in the 0.018-in. brackets and ten 0.019 × 0.019 in., 0.019 × 0.025 in., and 0.019 × 0.026 in. stainless steel wires were evaluated in the 0.022-in. brackets. A 15° buccal root torque was gradually applied to the right central incisor bracket, and the moments were recorded at this position. One-way ANOVA was applied for both bracket slot sizes along with post hoc analysis for the various archwire sizes. The mean measured moments varied between 10.78 and 30.60 Nmm among the assessed wire-and-bracket combinations. Both square and rectangular archwires in the 0.018-in. bracket system exerted statistically significantly higher moments in comparison with their counterparts in the 0.022-in. bracket system. Rectangular archwires exerted statistically significantly higher moments than square archwires, both for the 0.018- and the 0.022-in. bracket system. Rectangular archwires seem to be more efficient in torque exertion, especially in 0.018-in. brackets.

Optimal muscle fascicle length and tendon stiffness for maximising gastrocnemius efficiency during human walking and running.

PubMed

Lichtwark, G A; Wilson, A M

2008-06-21

Muscles generate force to resist gravitational and inertial forces and/or to undertake work, e.g. on the centre of mass. A trade-off in muscle architecture exists in muscles that do both; the fibres should be as short as possible to minimise activation cost but long enough to maintain an appropriate shortening velocity. Energetic cost is also influenced by tendon compliance which modulates the timecourse of muscle mechanical work. Here we use a Hill-type muscle model of the human medial gastrocnemius to determine the muscle fascicle length and Achilles tendon compliance that maximise efficiency during the stance phase of walking (1.2m/s) and running (3.2 and 3.9 m/s). A broad range of muscle fascicle lengths (ranging from 45 to 70 mm) and tendon stiffness values (150-500 N/mm) can achieve close to optimal efficiency at each speed of locomotion; however, efficient walking requires shorter muscle fascicles and a more compliant tendon than running. The values that maximise efficiency are within the range measured in normal populations. A non-linear toe-region region of the tendon force-length properties may further influence the optimal values, requiring a stiffer tendon with slightly longer muscle fascicles; however, it does not alter the main results. We conclude that muscle fibre length and tendon compliance combinations may be tuned to maximise efficiency under a given gait condition. Efficiency is maximised when the required volume of muscle is minimised, which may also help reduce limb inertia and basal metabolic costs.

Influence of Laser Power on the Microstructure and Mechanical Properties of a Laser Welded-Brazed Mg Alloy/Ni-Coated Steel Dissimilar Joint

NASA Astrophysics Data System (ADS)

Tan, Caiwang; Xiao, Liyuan; Liu, Fuyun; Chen, Bo; Song, Xiaoguo; Li, Liqun; Feng, Jicai

2017-05-01

In this work, we describe a method to improve the bonding of an immiscible Mg/steel system using Ni as an interlayer by coating it on the steel surface. Laser welding-brazing of AZ31B Mg alloy to Ni-coated Q235 steel using Mg-based filler was performed in a lap configuration. The influence of laser power on the weld characteristics, including joint appearance, formation of interfacial reaction layers and mechanical properties was investigated. The results indicated that the presence of the Ni-coating promoted the wetting of the liquid filler metal on the steel surface. A thermal gradient along the interface led to the formation of heterogeneous interfacial reaction layers. When using a low laser power of 1600 W, the reaction products were an FeAl phase in the direct laser irradiation zone, an AlNi phase close to the intermediate zone and mixtures of AlNi phase and an (α-Mg + Mg2Ni) eutectic structure near the interface at the seam head zone. For high powers of more than 2000 W, the FeAl phase grew thicker in the direct laser irradiation zone and a new Fe(Ni) transition layer formed at the interface of the intermediate zone and the seam head zone. However, the AlNi phase and (α-Mg + Mg2Ni) eutectic structure were scattered at the Mg seam. All the joints fractured at the fusion zone, indicating that the improved interface was not the weakest joint region. The maximum tensile-shear strength of the Mg/Ni-coated steel joint reached 190 N/mm, and the joint efficiency was 70% with respect to the Mg alloy base metal.

Advanced Glycation Endproducts and Bone Material Properties in Type 1 Diabetic Mice

PubMed Central

Rubin, Mishaela R.; Paschalis, Eleftherios P.; Poundarik, Atharva; Sroga, Gyna E.; McMahon, Donald J.; Gamsjaeger, Sonja; Klaushofer, Klaus; Vashishth, Deepak

2016-01-01

Fractures, particularly at the lower extremities and hip, are a complication of diabetes. In both type 1 (T1D) and type 2 diabetes (T2D), fracture risk is disproportionately worse than that predicted from the measurement of bone mineral density. Although an explanation for this discrepancy is the presence of organic matrix abnormalities, it has not been fully elucidated how advanced glycation endproducts (AGEs) relate to bone deterioration at both the macroscopic and microscopic levels. We hypothesized that there would be a relationship between skeletal AGE levels (determined by Raman microspectroscopy at specific anatomical locations) and bone macroscopic and microscopic properties, as demonstrated by the biomechanical measures of crack growth and microindentation respectively. We found that in OVE26 mice, a transgenic model of severe early onset T1D, AGEs were increased by Raman (carboxymethyl-lysine [CML] wildtype (WT): 0.0143 ±0.0005 vs T1D: 0.0175 ±0.0002, p = 0.003) at the periosteal surface. These differences were associated with less tough bone in T1D by fracture mechanics (propagation toughness WT: 4.73 ± 0.32 vs T1D: 3.39 ± 0.24 NM/m1/2, p = 0.010) and by reference point indentation (indentation distance increase WT: 6.85 ± 0.44 vs T1D: 9.04 ± 0.77 μm; p = 0.043). Within T1D, higher AGEs by Raman correlated inversely with macroscopic bone toughness. These data add to the existing body of knowledge regarding AGEs and the relationship between skeletal AGEs with biomechanical indices. PMID:27140650

Angular stable lateral plating is a valid alternative to conventional plate fixation in the proximal phalanx. A biomechanical study.

PubMed

Shanmugam, R; Ernst, M; Stoffel, K; Fischer, M F; Wahl, D; Richards, R G; Gueorguiev, B

2015-06-01

Dorsal plating is commonly used in proximal phalanx fractures but it bears the risk of interfering with the extensor apparatus. In this study, dorsal and lateral plating fixation methods are compared to assess biomechanical differences using conventional 1.5mm non-locking plates and novel 1.3mm lateral locking plates. Twenty-four fresh frozen human cadaveric proximal phalanges were equally divided into four groups. An osteotomy was set at the proximal metaphyseal-diaphyseal junction and fixed with either dorsal (group A) or lateral (group B) plating using a 1.5mm non-locking plate, or lateral plating with a novel 1.3mm locking plate with bicortical (group C) or unicortical (group D) screws. The specimens were loaded in axial, dorsovolar and mediolateral direction to assess fixation stiffness followed by a cyclic destructive test in dorsovolar loading direction. Axial stiffness was highest in group D (mean 321.02, SEM 21.47N/mm) with a significant difference between groups D and B (P=0.033). Locking plates (groups C and D) were stiffer than non-locking plates under mediolateral loading (P=0.007), no significant differences were noted under dorsovolar loading. Furthermore, no significant differences were observed under cyclic loading to failure between any of the study groups. No considerable biomechanical advantage of using a conventional 1.5mm dorsal non-locking plate was identified over the novel 1.3mm lateral locking plate in the treatment of proximal phalanx fractures. Since the novel low-profile plate is less disruptive to the extensor mechanism, it should be considered as a valid alternative. Copyright © 2015 Elsevier Ltd. All rights reserved.

Integrated chemical/biochemical sample collection, pre-concentration, and analysis on a digital microfluidic lab-on-a-chip platform

NASA Astrophysics Data System (ADS)

Fair, Richard B.; Khlystov, A.; Srinivasan, Vijay; Pamula, Vamsee K.; Weaver, Kathryn N.

2004-12-01

An ideal on-site chemical/biochemical analysis system must be inexpensive, sensitive, fully automated and integrated, reliable, and compatible with a broad range of samples. The advent of digital microfluidic lab-on-a-chip (LoC) technology offers such a detection system due to the advantages in portability, reduction of the volumes of the sample and reagents, faster analysis times, increased automation, low power consumption, compatibility with mass manufacturing, and high throughput. We describe progress towards integrating sample collection onto a digital microfluidic LoC that is a component of a cascade impactor device. The sample collection is performed by impacting airborne particles directly onto the surface of the chip. After the collection phase, the surface of the chip is washed with a micro-droplet of solvent. The droplet will be digitally directed across the impaction surface, dissolving sample constituents. Because of the very small droplet volume used for extraction of the sample from a wide colection area, the resulting solution is realatively concentrated and the analytes can be detected after a very short sampling time (1 min) due to such pre-concentration. After the washing phase, the droplet is mixed with specific reagents that produce colored reaction products. The concentration of the analyte is quantitatively determined by measuring absorption at target wavelengths using a simple light emitting diode and photodiode setup. Specific applications include automatic measurements of major inorganic ions in aerosols, such as sulfate, nitrate and ammonium, with a time resolution of 1 min and a detection limit of 30 nm/m3. We have already demonstrated the detection and quantification of nitroaromatic explosives without integrating the sample collection. Other applications being developed include airborne bioagent detection.

Toehold-mediated strand displacement reaction-dependent fluorescent strategy for sensitive detection of uracil-DNA glycosylase activity.

PubMed

Wu, Yushu; Wang, Lei; Jiang, Wei

2017-03-15

Sensitive detection of uracil-DNA glycosylase (UDG) activity is beneficial for evaluating the repairing process of DNA lesions. Here, toehold-mediated strand displacement reaction (TSDR)-dependent fluorescent strategy was constructed for sensitive detection of UDG activity. A single-stranded DNA (ssDNA) probe with two uracil bases and a trigger sequence were designed. A hairpin probe with toehold domain was designed, and a reporter probe was also designed. Under the action of UDG, two uracil bases were removed from ssDNA probe, generating apurinic/apyrimidinic (AP) sites. Then, the AP sites could inhibit the TSDR between ssDNA probe and hairpin probe, leaving the trigger sequence in ssDNA probe still free. Subsequently, the trigger sequence was annealed with the reporter probe, initiating the polymerization and nicking amplification reaction. As a result, numerous G-quadruplex (G4) structures were formed, which could bind with N-methyl-mesoporphyrin IX (NMM) to generate enhanced fluorescent signal. In the absence of UDG, the ssDNA probe could hybridize with the toehold domain of the hairpin probe to initiate TSDR, blocking the trigger sequence, and then the subsequent amplification reaction would not occur. The proposed strategy was successfully implemented for detecting UDG activity with a detection limit of 2.7×10 -5 U/mL. Moreover, the strategy could distinguish UDG well from other interference enzymes. Furthermore, the strategy was also applied for detecting UDG activity in HeLa cells lysate with low effect of cellular components. These results indicated that the proposed strategy offered a promising tool for sensitive quantification of UDG activity in UDG-related function study and disease prognosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of cross-sectional design and dimension on mechanical behavior of nickel-titanium instruments under torsion and bending: a numerical analysis.

PubMed

Zhang, En-Wei; Cheung, Gary S P; Zheng, Yu-Feng

2010-08-01

The aim of this study was to examine the influence of the cross-sectional configuration and dimensions (size and taper) on the torsional and bending behavior of nickel-titanium rotary instruments, taking into account the nonlinear mechanical properties of material. Ten cross-sectional configurations, square, triangular, U-type, S-type (large and small), convex-triangle, and 4 proprietary ones (Mani NRT and RT2, Quantec, and Mtwo), were analyzed under torsion or bending by using a 3-dimensional finite element method. The von Mises stresses were correlated with the critical values for various phases of the nickel-titanium material. Different loading conditions led to unequal patterns of stress distribution. Increasing the applied torque or bending angle resulted in a rise in the corresponding stresses in the instrument. Favorable stress distribution without dangerous stress concentration was observed if the material was undergoing superelastic transformation at that applied load. The ultimate strength of the material was not exceeded when the instrument was bent up to a 50-degree curvature. On the other hand, when a torsional moment of greater than 1.0 N*mm was applied, the maximum stresses developed in some designs would exceed the ultimate strength of the material. Little variation in the von Mises stresses was observed for instruments of different nominal sizes and tapers on bending to similar extent. The cross-sectional design has a greater impact than taper or size of the instrument on the stresses developed in the instrument under either torsion or bending. Certain cross-sectional configurations are prone to fracture by excess torsional stresses. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Comparing five simple vascular storage protocols.

PubMed

van Doormaal, Tristan P C; Sluijs, Jurren H; Vink, Aryan; Tulleken, Cornelis A F; van der Zwan, Albert

2014-11-01

We aim to find a storage protocol for vessels that preserves their dimensional, histologic, and mechanical characteristics to facilitate reproducible anastomosis experiments and microsurgical training with constant quality. We compared stored rabbit aortas, harvested in a slaughterhouse, using five different protocols with fresh controls. Aortas were preserved for 125 d in (1) NaCl 0.9% at -18°C, (2) Roswell Park Memorial Institute 1640 90% with 10% dimethyl sulfoxide (RPMI/DMSO) at -18°C, (3) RPMI/DMSO at -70°C, (4) glycerol 85% at 4°C, and (5) glycerol in stepwise increased concentrations until 85% at 4°C. After preservation, we measured vessel diameter, wall thickness, and Young's Modulus indicating stiffness. Neurosurgeons compared stored vessels with fresh vessels, blinded for preservation subgroup. We performed histologic assessment blinded for preservation subgroup. Fresh rabbit aortas showed a mean diameter of 2.65 ± 0.14 mm, a mean wall thickness of 126 ± 22 μm, and a Young's Modulus of 11.4 ± 2.4 N/mm(2). NaCl 0.9%-preserved aortas showed a significantly increased vessel diameter and decreased stiffness. RPMI/DMSO-preserved aortas showed no significant differences from fresh aortas in dimensions and mechanical characteristics. Glycerol-preserved tissue showed a significant increase in wall thickness, a related significant decrease in diameter, and increase in stiffness. Neurosurgeons regarded RPMI/DMSO tissue as most comparable with fresh tissue. Histologic assessment revealed no differences between the different protocols and fresh control group. Storage of rabbit aortas in RPMI/DMSO most adequately preserves their dimensional and mechanical properties. Copyright © 2014 Elsevier Inc. All rights reserved.

The effect of silane applied to glass ceramics on surface structure and bonding strength at different temperatures

PubMed Central

Eraslan, Oguz

2016-01-01

PURPOSE To evaluate the effect of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics. MATERIALS AND METHODS 288 specimens (lithium-disilicate, leucite-reinforced, and glass infiltrated zirconia) were first divided into two groups according to the resin cement used, and were later divided into four groups according to the given surface treatments: G1 (hydrofluoric acid (HF)+silane), G2 (silane alone-no heat-treatment), G3 (silane alone-then dried with 60℃ heat-treatment), and G4 (silane alone-then dried with 100℃ heat-treatment). Two different adhesive luting systems were applied onto the ceramic discs in all groups. SBS (in MPa) was calculated from the failure load per bonded area (in N/mm2). Subsequently, one specimen from each group was prepared for SEM evaluation of the separated-resin–ceramic interface. RESULTS SBS values of G1 were significantly higher than those of the other groups in the lithium disilicate ceramic and leucite reinforced ceramic, and the SBS values of G4 and G1 were significantly higher than those of G2 and G3 in glass infiltrated zirconia. The three-way ANOVA revealed that the SBS values were significantly affected by the type of resin cement (P<.001). FIN ceramics had the highest rate of cohesive failure on the ceramic surfaces than other ceramic groups. AFM images showed that the surface treatment groups exhibited similar topographies, except the group treated with HF. CONCLUSION The heat treatment was not sufficient to achieve high SBS values as compared with HF acid etching. The surface topography of ceramics was affected by surface treatments. PMID:27141250

Comparison of cervical spine stiffness in individuals with chronic nonspecific neck pain and asymptomatic individuals.

PubMed

Ingram, Lewis A; Snodgrass, Suzanne J; Rivett, Darren A

2015-03-01

Clinical measurement, cross-sectional. To determine if spinal joint stiffness is different in individuals with nonspecific neck pain, and whether stiffness magnitude is associated with pain intensity and disability. Manual therapists commonly evaluate spinal joint stiffness in patients presenting with nonspecific neck pain. However, a relationship between stiffness and neck pain has not yet been demonstrated. Spinal stiffness at C7 was objectively measured in participants with chronic nonspecific neck pain whose symptomatic spinal level was identified as C7 (n = 12) and in age- and sex-matched asymptomatic controls (n = 12). Stiffness (slope of the linear region of the force-displacement curve) was quantified using a device that applied 5 standardized mechanical force cycles to the C7 spinous process, while concurrently measuring displacement and resistance to movement. Stiffness was compared between groups using an independent t test. Spearman rho and Pearson r were used to determine the extent to which stiffness magnitude was associated with pain intensity (visual analog scale) and level of disability (Neck Disability Index), respectively, in the group with neck pain. Participants with nonspecific neck pain had greater spinal joint stiffness at C7 compared with asymptomatic individuals (mean difference, 1.78 N/mm; 95% confidence interval: 0.28, 3.27; P = .022). However, stiffness magnitude in the group with neck pain was not associated (P>.05) with pain intensity or level of disability. These preliminary results suggest that cervical spine stiffness may be greater in the presence of nonspecific neck pain. However, judgments regarding pain intensity and level of disability should not be inferred from examinations of spinal joint stiffness.

Characterization of synthetic nanocrystalline mackinawite: crystal structure, particle size, and specific surface area

PubMed Central

Jeong, Hoon Y.; Lee, Jun H.; Hayes, Kim F.

2010-01-01

Iron sulfide was synthesized by reacting aqueous solutions of sodium sulfide and ferrous chloride for 3 days. By X-ray powder diffraction (XRPD), the resultant phase was determined to be primarily nanocrystalline mackinawite (space group: P4/nmm) with unit cell parameters a = b = 3.67 Å and c = 5.20 Å. Iron K-edge XAS analysis also indicated the dominance of mackinawite. Lattice expansion of synthetic mackinawite was observed along the c-axis relative to well-crystalline mackinawite. Compared with relatively short-aged phase, the mackinawite prepared here was composed of larger crystallites with less elongated lattice spacings. The direct observation of lattice fringes by HR-TEM verified the applicability of Bragg diffraction in determining the lattice parameters of nanocrystalline mackinawite from XRPD patterns. Estimated particle size and external specific surface area (SSAext) of nanocrystalline mackinawite varied significantly with the methods used. The use of Scherrer equation for measuring crystallite size based on XRPD patterns is limited by uncertainty of the Scherrer constant (K) due to the presence of polydisperse particles. The presence of polycrystalline particles may also lead to inaccurate particle size estimation by Scherrer equation, given that crystallite and particle sizes are not equivalent. The TEM observation yielded the smallest SSAext of 103 m2/g. This measurement was not representative of dispersed particles due to particle aggregation from drying during sample preparation. In contrast, EGME method and PCS measurement yielded higher SSAext (276–345 m2/g by EGME and 424 ± 130 m2/g by PCS). These were in reasonable agreement with those previously measured by the methods insensitive to particle aggregation. PMID:21085620

Disposable magnetically levitated centrifugal blood pump: design and in vitro performance.

PubMed

Hoshi, Hideo; Asama, Junichi; Shinshi, Tadahiko; Ohuchi, Katsuhiro; Nakamura, Makoto; Mizuno, Tomohiro; Arai, Hirokuni; Shimokohbe, Akira; Takatani, Setsuo

2005-07-01

A magnetically levitated (MagLev) centrifugal blood pump (CBP) with a disposable pump head has been designed to realize a safe, easy-to-handle, reliable, and low-cost extracorporeal blood pump system. It consisted of a radial magnetic-coupled driver with a magnetic bearing having a two-degree freedom control and a disposable pump head unit with a priming volume of 24 mL. The easy on-off disposable pump head unit was made into a three-piece system consisting of the top and bottom housings, and the impeller-rotor assembly. The size and weight of the disposable pump unit were 75 mm x 45 mm and 100 g, respectively. Because the structure of the pump head unit is easily attachable and removable, the gap between the electromagnets of the stator and the target material in the rotor increased to 1.8 mm in comparison to the original integrated bearing system of 1.0 mm. The pump performance, power requirements, and controllability of the magnetic bearing revealed that from 1400 to 2400 rpm, the pump performance remained fairly unchanged. The amplitudes of the X- and Y-axis rotor oscillation increased to +/- 24 microm. The axial displacement of the rotor, 0.4 mm, toward the top housing was also observed at the pump rpm between 1400 and 2400. The axial and rotational stiffness of the bearing were 15.9 N/mm and 4.4 Nm/rad, respectively. The MagLev power was within 0.7 Watts. This study demonstrated the feasibility of a disposable, magnetically suspended CBP as the safe, reliable, easy-to-handle, low-cost extracorporeal circulation support device.

Effect OF NaOH Treatment on Bending Strength Of The Polyester Composite Reinforce By Sugar Palm Fibers

NASA Astrophysics Data System (ADS)

Arif Irfai, Mochamad; Wulandari, Diah; Sutriyono; Marsyahyo, Eko

2018-04-01

The objective of this research is to investigate the effect of NaOH treatment on bending strength of lamina composite reinforced by sugar palm fiber. To know of mechanism fracture can be done with visual inspection of the fracture surface. The Materials used are random sugar palm fibers that have been in the treatment of NaOH, polyester resin and hardener. Sugar palm fibers after washed and dried then soaked NaOH with a long time soaking 0, 2, 4, 6 and 8 hours. The bending test specimens were produced according to ASTM D 790. All specimens were post cured at 62°C for 4 hours. The Bending test was carried out on a universal testing machine. The SEM analysis has conducted to provide the analysis on interface adhesion between the surfaces of fiber with the matrix. The result shows that polyester composite reinforced by sugar palm fiber has highest bending stress 176.77 N/mm2 for 2 hours of a long time soaking NaOH, the highest flexural strain 0.27 mm for 2 hours of a long time soaking NaOH, elongation 24.05% for 2 hours of a long time soaking NaOH and the highest bending modulus 1.267 GPa for 2 hours of a long time soaking NaOH. Based on the results, it can be concluded that the polyester composite reinforced by sugar palm fiber has the optimum bending properties for a long time soaking 2 hours. The fracture surface shows that the polyester composite reinforced by sugar palm fiber pull out that indicate weakens the bond between fiber and matrix.

Biomechanical analysis using FEA and experiments of a standard plate method versus three cable methods for fixing acetabular fractures with simultaneous THA.

PubMed

Aziz, Mina S R; Dessouki, Omar; Samiezadeh, Saeid; Bougherara, Habiba; Schemitsch, Emil H; Zdero, Radovan

2017-08-01

Acetabular fractures potentially account for up to half of all pelvic fractures, while pelvic fractures potentially account for over one-tenth of all human bone fractures. This is the first biomechanical study to assess acetabular fracture fixation using plates versus cables in the presence of a total hip arthroplasty, as done for the elderly. In Phase 1, finite element (FE) models compared a standard plate method versus 3 cable methods for repairing an acetabular fracture (type: anterior column plus posterior hemi-transverse) subjected to a physiological-type compressive load of 2207N representing 3 x body weight for a 75kg person during walking. FE stress maps were compared to choose the most mechanically stable cable method, i.e. lowest peak bone stress. In Phase 2, mechanical tests were then done in artificial hemipelvises to compare the standard plate method versus the optimal cable method selected from Phase 1. FE analysis results showed peak bone stresses of 255MPa (Plate method), 205MPa (Mears cable method), 250MPa (Kang cable method), and 181MPa (Mouhsine cable method). Mechanical tests then showed that the Plate method versus the Mouhsine cable method selected from Phase 1 had higher stiffness (662versus 385N/mm, p=0.001), strength (3210versus 2060N, p=0.009), and failure energy (8.8versus 6.2J, p=0.002), whilst they were statistically equivalent for interfragmentary sliding (p≥0.179) and interfragmentary gapping (p≥0.08). The Plate method had superior mechanical properties, but the Mouhsine cable method may be a reasonable alternative if osteoporosis prevents good screw thread interdigitation during plating. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Structure and magnetic properties of L n MnSbO ( L n = La and Ce)

DOE PAGES

Zhang, Qiang; Kumar, C. M. N.; Tian, Wei; ...

2016-03-11

Here, a neutron powder diffraction (NPD) study of LnMnSbO (Ln = La or Ce) reveals differences between the magnetic ground state of the two compounds due to the strong Ce-Mn coupling compared to La-Mn. The two compounds adopt the P4/nmm space group down to 2 K, and whereas magnetization measurements do not show obvious anomaly at high temperatures, NPD reveals a C-type antiferromagnetic (AFM) order below T N = 255K for LaMnSbO and 240 K for CeMnSbO. While the magnetic structure of LaMnSbO is preserved to base temperature, a sharp transition at T SR = 4.5K is observed in CeMnSbOmore » due to a spin-reorientation (SR) transition of the Mn 2+ magnetic moments from pointing along the c axis to the ab plane. The SR transition in CeMnSbO is accompanied by a simultaneous long-range AFM ordering of the Ce moments, which indicates that the Mn SR transition is driven by the Ce-Mn coupling. The ordered moments are found to be somewhat smaller than those expected for Mn 2+ (S = 5/2) in insulators, but large enough to suggest that these compounds belong to the class of local-moment antiferromagnets. The lower T N found in these two compounds compared to the As-based counterparts (T N = 317 for LaMnAsO, T N = 347K for CeMnAsO) indicates that the Mn-Pn (Pn=As or Sb) hybridization that mediates the superexchange Mn-Pn-Mn coupling is weaker for the Sb-based compounds.« less

Reliability of dynamometric passive properties of the pelvic floor muscles in postmenopausal women with stress urinary incontinence.

PubMed

Morin, Mélanie; Gravel, Denis; Bourbonnais, Daniel; Dumoulin, Chantale; Ouellet, Stéphane

2008-01-01

The passive properties of the pelvic floor muscles (PFM) might play a role in stress urinary incontinence (SUI) pathophysiology. To investigate the test-retest reliability of the dynamometric passive properties of the PFM in postmenopausal SUI women. Thirty-two SUI postmenopausal women were convened to two sessions 2 weeks apart. In each session, the measurements were repeated twice. The pelvic floor musculature was evaluated in four different conditions: (1) forces recorded at minimal aperture (initial passive resistance); (2) passive resistance at maximal aperture; (3) five lengthening and shortening cycles (Forces and passive elastic stiffness (PES) were evaluated at different vaginal apertures. Hysteresis was also calculated.); (4) Percentage of passive resistance loss after 1 min of sustained stretching was computed. The generalizability theory was used to calculate two reliability estimates, the dependability indices (Phi) and the standard error of measurement (SEM), for one session involving one measurement or the mean of two measurements. Overall, the reliability of the passive properties was good with indices of dependability of 0.75-0.93. The SEMs for forces and PES were 0.24-0.67 N and 0.03-0.10 N/mm, respectively, for mean, maximal and 20-mm apertures, representing an error between 13% and 23%. Passive forces at minimal aperture showed lower reliability (Phi = 0.51-0.57) compared with other vaginal openings. The aperture at a common force of 0.5 N was the only parameter demonstrating a poor reliability (Phi = 0.35). This new approach for assessing PFM passive properties showed enough reliability for highly recommending its inclusion in the PFM assessment of SUI postmenopausal women. (c) 2008 Wiley-Liss, Inc.

The BiCu{sub 1−x}OS oxysulfide: Copper deficiency and electronic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berthebaud, D.; Guilmeau, E.; Lebedev, O.I.

2016-05-15

An oxysulfide series of nominal compositions BiCu{sub 1−x}OS with x<0.20 has been prepared and its structural properties characterized by combining powder X-ray diffraction and transmission electron microscopy techniques. It is found that this oxysulfide, crystallizing in the P4/nmm space group, tends to adopt a constant amount of copper vacancy corresponding to x=0.05 in the BiCu{sub 1−x}OS formula. The presence of Cu vacancies is confirmed by HAADF-STEM analysis showing, in the Cu atomic columns, alternating peaks of different intensities in some very localized regions. For larger Cu deficiencies (x>0.05 in the nominal composition), other types of structural nanodefects are evidenced suchmore » as bismuth oxysulfides of the “BiOS” ternary system which might explain the report of superconductivity for the BiCu{sub 1−x}OS oxysulfide. Local epitaxial growth of the BiCuOS oxysulfide on top of CuO is also observed. In marked contrast to the BiCu{sub 1−x}OSe oxyselenide, these results give an explanation to the limited impact of Cu deficiency on the Seebeck coefficient in BiCu{sub 1−x}OS compounds. - Graphical abstract: High resolution TEM image showing a Bi(Cu)OS/Bi{sub 2}O{sub 2}S interface and corresponding dislocation region. The Bi(Cu)OS structure adopts a rather constant Cu content (near 0.95); starting from BiCuOS leads to the formation of defects such as the Bi{sub 2}O{sub 2}S oxysulfide.« less

Accelerated functional recovery after skeletal muscle ischemia-reperfusion injury using freshly isolated bone marrow cells.

PubMed

Corona, Benjamin T; Rathbone, Christopher R

2014-05-01

Relatively little information exists regarding the usefulness of bone marrow-derived cells for skeletal muscle ischemia-reperfusion injury (I/R), especially when compared with I/R that occurs in other tissues. The objectives of this study were to evaluate the ability of freshly isolated bone marrow cells to home to injured skeletal muscle and to determine their effects on muscle regeneration. Freshly isolated lineage-depleted bone marrow cells (Lin(-) BMCs) were injected intravenously 2 d after I/R. Bioluminescent imaging was used to evaluate cell localization for up to 28 d after injury. Muscle function, the percentage of fibers with centrally located nuclei, and the capillary-to-fiber ratio were evaluated 14 d after delivery of either saline (Saline) or saline containing Lin(-) BMCs (Lin(-) BMCs). Bioluminescence was higher in the injured leg than the contralateral control leg for up to 7 d after injection (P < 0.05) suggestive of cell homing to the injured skeletal muscle. Fourteen days after injury, there was a significant improvement in maximal tetanic torque (40% versus 22% deficit; P < 0.05), a faster rate of force production (+dP/dt) (123.6 versus 94.5 Nmm/S; P < 0.05), and a reduction in the percentage of fibers containing centrally located nuclei (40 versus 17%; P < 0.05), but no change in the capillary-to-fiber ratio in the Lin(-) BMC as compared with the Saline group. The homing of freshly isolated BMCs to injured skeletal muscle after I/R is associated with an increase in functional outcomes. Published by Elsevier Inc.

Development of the AOML Hurricane Research System

NASA Astrophysics Data System (ADS)

Yeh, K.; Gopalakrishnan, S.; Zhang, X.; Bao, J.; Quirino, T.; Sainani, V.; Rogers, R.; Aberson, S.; Marks, F.; Atlas, R.

2008-12-01

NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML) has committed to the development of a modeling and data-assimilation system recently. This Hurricane Research System (HRS) aims to improve hurricane forecast by developing innovative modeling techniques, and by assimilating the hurricane inner-core data that is timely collected with aircrafts by the scientists at the AOML Hurricane Research Division (HRD), in addition to the data collected by other channels. We have started the development of the HRS by implementing a moving nest within a regional domain on the Weather Research and Forecasting (WRF) Nonhydrostatic Mesoscale Model (NMM). The dynamically moving nest is used to track the hurricane with an enhanced resolution to better simulate the hurricane structure with more accurate dynamical and physical processes. Combining with the diagnostic expertise at the HRD, and benefiting from the community efforts, we have quickly composed the HRS with excellent ingredients from various organizations. This baseline system has been in experimental operation for this hurricane season, and early result with these experiments seems quite promising. We have also developed a new visualization tool and an efficient post-processor emphasizing diagnostic functionality to facilitate hurricane research. Further development of the HRS includes the implementation of a third, moving nest to advance the model resolution to 1 km or higher with the limited computing resource. Innovative model initialization techniques and versatile hurricane-diagnostic tools are undergoing development. An Ensemble Kalman Filter is being constructed for the HRS to assimilate observation data. Physical parameterizations are being refined to improve the forcing and heating mechanisms, and ocean model coupling is to be implemented for realistic air-sea interactions. We will report the status up to date.

Intraoperative cervix location and apical support stiffness in women with and without pelvic organ prolapse.

PubMed

Swenson, Carolyn W; Smith, Tovia M; Luo, Jiajia; Kolenic, Giselle E; Ashton-Miller, James A; DeLancey, John O

2017-02-01

location during clinic examination and operative testing was defined by the total range of values observed in the normal/normal group. The proportion of women in each group with cervix locations within and outside the normal range was determined. Linear regression was performed to identify variables independently associated with clinic Pelvic Organ Prolapse Quantification point C. In all, 52 women were included: 14 in the normal/normal group, 11 in the normal/prolapse group, and 27 in the prolapse/prolapse group. At 1 N of traction force in the operating room, 50% of women in the normal/prolapse group had cervix locations outside the normal range while 10% had apical support stiffness outside the normal range. Of women in the prolapse/prolapse group, 81% had cervix locations outside the normal range and 8% had apical support stiffness outside the normal range. Similar results for cervix locations were observed at 18 N of traction force; however the proportion of women with apical support stiffness outside the normal range increased to 50% in the normal/prolapse group and 59% in the prolapse/prolapse group. The prolapse/prolapse group had statistically lower apical support stiffness compared to the normal/normal group with increased traction from 1-18 N (0.47 ± 0.18 N/mm vs 0.63 ± 0.20 N/mm, P = .006), but all other comparisons were nonsignificant. After controlling for age, parity, body mass index, and apical support stiffness, cervix location at 1 N traction force remained an independent predictor of clinic Pelvic Organ Prolapse Quantification point C, but only in the prolapse/prolapse group. Approximately 50% of women with cystocele and/or rectocele but normal apical support in the clinic had cervix locations outside the normal range under intraoperative traction, while 19% of women with uterine prolapse had normal apical support. Identifying women whose apical support falls outside a defined normal range may be a more accurate way to identify those who truly need a

Cation ordering and effect of biaxial strain in double perovskite CsRbCaZnCl 6

DOE PAGES

Pilania, G.; Uberuaga, B. P.

2015-03-19

Here, we investigate the electronic structure, energetics of cation ordering, and effect of biaxial strain on double perovskite CsRbCaZnCl 6 using first-principles calculations based on density functional theory. The two constituents (i.e., CsCaCl 3 and RbZnCl 3) forming the double perovskite exhibit a stark contrast. While CsCaCl 3 is known to exist in a cubic perovskite structure and does not show any epitaxial strain induced phase transitions within an experimentally accessible range of compressive strains, RbZnCl 3 is thermodynamically unstable in the perovskite phase and exhibits ultra-sensitive response at small epitaxial strains if constrained in the perovskite phase. We showmore » that combining the two compositions in a double perovskite structure not only improves overall stability but also the strain-polarization coupling of the material. Our calculations predict a ground state with P4/nmm space group for the double perovskite, where A-site cations (i.e., Cs and Rb) are layer-ordered and B-site cations (i.e., Ca and Zn) prefer a rocksalt type ordering. The electronic structure and bandgap in this system are shown to be quite sensitive to the B-site cation ordering and is minimally affected by the ordering of A-site cations. We find that at experimentally accessible compressive strains CsRbCaZnCl 6 can be phase transformed from its paraelectric ground state to an antiferroelectric state, where Zn atoms contribute predominantly to the polarization. Furthermore, both energy difference and activation barrier for a transformation between this antiferroelectric state and the corresponding ferroelectric configuration are predicted to be small. As a result, the computational approach presented here opens a new pathway towards a rational design of novel double perovskites with improved strain response and functionalities.« less

Comparison of design features and mechanical properties of commercially available Veress needles.

PubMed

Schramel, Johannes P; Kindslehner, Angelika; Bockstahler, Barbara A; Dupré, Gilles P

2017-10-01

To compare design features and mechanical properties of 13 commercially available Veress needles (VN). In vitro biomechanical study. Veress needles from 9 manufacturers (6 reusable, 6 disposable, and 1 with a reusable stylet combined with a disposable cannula) were included in the study. Veress needles are designed with a spring-loaded stylet to protect the tip of the cannula following insertion into the abdomen. Stylet forces were measured with a scale in a test jig by moving the stylet in 0.5 mm steps into the hollow cannula. Forces and spring rates were derived from force-displacement plots. Mass, mechanical dimensions, and the bevel angle and geometry were assessed. Differences between VN models were analyzed with a univariate analysis of variance. Results are reported as mean ± SD or median (range). Physical and mechanical parameters differed between models. The exposed stylet length was 3.5 mm (2-7). Three bevel geometries (bias, lancet type, and back-cut) with angles between 20° and 40° were identified. Reusable VN weigh more (24.9 ± 2.2 g) than disposable designs (6.0 ± 2.3 g). The mean values for the spring rate and the residual stylet force were 0.23 ± 0.08 Nmm -1 and 0.94 ± 0.28 N, respectively. The mean force required to move the stylet to the cannula tip was 1.81 ± 0.29 N and 2.77 ± 0.54 N to move to the proximal end of the bevel. Commercially available VN use diverse bevel geometries and have different mechanical characteristics. Studies investigating laparoscopic entry complications should explicitly report the type of VN model used. © 2017 The American College of Veterinary Surgeons.

Mechanistic evaluation of alginate-HEC gelisphere compacts for controlled intrastriatal nicotine release in Parkinson's disease.

PubMed

Choonara, Yahya E; Pillay, Viness; Khan, Riaz A; Singh, Neha; du Toit, Lisa C

2009-06-01

This study focused on elucidating a mechanistic understanding in support of the multiple mechanisms which govern the formation of crosslinked alginate-hydroxyethylcellulose (Alg-HEC) gelispheres intended for the controlled intrastriatal release of nicotine as a neuroprotectant in Parkinson's Disease. HEC was incorporated as a reinforcing "protective" colloidal polymer to induce interactions between the free carboxyl groups of alginate with hydroxylated HEC monomers. Gelispheres were compressed within an external poly(lactic-co-glycolic acid) (PLGA) matrix to further prolong the release of nicotine. Sol-gel interconversion mechanisms, matrix deformability moduli, matrix fracture energies and chemometric models of the associated energy paradigms were analyzed for their influence on the mechanism and extent of nicotine release. Textural profiling demonstrated higher fracture energies (7.94-26.69 x 10(-4) J) and lower deformability moduli (12.24-58.36 N/mm) when gelispheres were cured in 2 M HCl as a postcuring step. Ba(2+) crosslinked gelispheres resulted in superiorly compact matrices with an increase in volume of 201-329% as compared to the Ca(2+) and Zn(2+) crosslinked matrices. The order of matrix compactness was as follows: Zn(2+) < Ca(2+) < Ba(2+). Molecular mechanisms of formation, interaction, conversion, and stability of sol-gel transitions depended on the type of crosslinker, crosslinking time, energy transactions, and interactions with molecules of the hydration medium. Ba(2+) crosslinked gelispheres released nicotine slower than Ca(2+) and Zn(2+) crosslinked gelispheres due to the higher energy requirement for interconversion to sol while the energy requirements for Ca(2+) and Zn(2+) was at a lower demand. Ba(2+) crosslinked gelispheres within PLGA matrices therefore retarded nicotine release in a pseudo-zero-order manner over 21 days. (c) 2008 Wiley-Liss, Inc.

Design and performance evaluation of an interferometric controlled planar nanopositioning system

NASA Astrophysics Data System (ADS)

Hesse, S.; Schäffel, C.; Mohr, H.-U.; Katzschmann, M.; Büchner, H.-J.

2012-07-01

High technology applications for example in the semiconductor or the optical industry require positioning systems providing repeatability and uncertainty in the range of nanometers together with x-, y-travel ranges of several hundreds of millimeters. We contribute in this research by investigating the applicability of integrated planar direct drives for the realization of nanopositioning- and nanomeasuring machines (NPM/NMM). The paper introduces the concept of planar integrated direct drives and explains the engineering design of the realized system for a 100 mm circular travel range in x and y. It presents the drive system parameters and the arrangement and interaction of the main components. The results of the initial operation are presented with a special focus on the question how the closed loop system can be taken into operation with a free floating slider. The evaluation of the positioning performance leads to the result that a 2D servo error of less than exy = 1.3 nm is achieved at arbitrary positions within the travel range. As a result of repeated step response tests, the positioning resolution is 0.5 nm. The measurement of the coincidental z-movement of the aerostatically supported slider yields a z-vibration with a standard deviation of σz = 0.45 nm. Regarding the drive system these results represent the limit of what can be reached with this setup as the measured error motions are in the range of the noise of the fixed environment setup. By measuring the characteristics of the aerostatic slider support at the fully assembled system the present air bearing stiffness is determined and based on a FEM-simulation of the slider eigenfrequencies the influence on the force transfer behavior is expected to be only marginal.

EXPERIMENTAL MODELLING OF AORTIC ANEURYSMS

PubMed Central

Doyle, Barry J; Corbett, Timothy J; Cloonan, Aidan J; O’Donnell, Michael R; Walsh, Michael T; Vorp, David A; McGloughlin, Timothy M

2009-01-01

A range of silicone rubbers were created based on existing commercially available materials. These silicones were designed to be visually different from one another and have distinct material properties, in particular, ultimate tensile strengths and tear strengths. In total, eleven silicone rubbers were manufactured, with the materials designed to have a range of increasing tensile strengths from approximately 2-4MPa, and increasing tear strengths from approximately 0.45-0.7N/mm. The variations in silicones were detected using a standard colour analysis technique. Calibration curves were then created relating colour intensity to individual material properties. All eleven materials were characterised and a 1st order Ogden strain energy function applied. Material coefficients were determined and examined for effectiveness. Six idealised abdominal aortic aneurysm models were also created using the two base materials of the study, with a further model created using a new mixing technique to create a rubber model with randomly assigned material properties. These models were then examined using videoextensometry and compared to numerical results. Colour analysis revealed a statistically significant linear relationship (p<0.0009) with both tensile strength and tear strength, allowing material strength to be determined using a non-destructive experimental technique. The effectiveness of this technique was assessed by comparing predicted material properties to experimentally measured methods, with good agreement in the results. Videoextensometry and numerical modelling revealed minor percentage differences, with all results achieving significance (p<0.0009). This study has successfully designed and developed a range of silicone rubbers that have unique colour intensities and material strengths. Strengths can be readily determined using a non-destructive analysis technique with proven effectiveness. These silicones may further aid towards an improved understanding of the

An infrared and Raman study of the reorientational motions and phase transition in and structure of CsPF6

NASA Astrophysics Data System (ADS)

Heyns, Anton M.; de Waal, Danita

1992-12-01

CsPF6I is face-centered cubic and the PF6- ions are randomly distributed among the six equivalent orientations in the crystal. The ions librate in equilibrium positions for an average time τ, and also jump from one orientation to another in a time which is much shorter than τ. The six different orientations in CsPF6I are of much lower symmetry than the full molecular one. The full vibrational spectra of CsPF6 are reported over the temperature range of 300-4 K and can be analyzed in Phase I in terms of (Oh,C¯4v) where C¯4v denotes the symmetry of the ion and Oh that of the site symmetry S. The polarized Raman spectra of single crystals of CsPF6I are interpreted in terms of all the different orientations of the PF6- ions and excellent agreement is obtained between predicted and experimental results. At 90 K CsPF6 undergoes a phase transition and a crystal structure of P4/nmm-D4h7 is assigned to Phase II. This transition is of the second order and shows behavior which corresponds to those of critical phenomena. An order parameter ξ is defined and a critical constant β is calculated to be equal to 0.3. In CsPF6II two orientations of the PF6- ions exist, both conforming to 4mm-C4v symmetry and the disorder persisting in this phase causes the splitting of the vibrational bands to be fully resolved below 60 K only. An activation energy of ˜3.0 kJ/mol is calculated for the motions of the PF6- ions between 90 and 60 K from the variation of the linewidths and intensities of vibrational bands.

Mass transfer, physical, and mechanical characteristics of terebinth fruit (Pistacia atlantica L.) under convective infrared microwave drying

NASA Astrophysics Data System (ADS)

Kaveh, Mohammad; Abbaspour-Gilandeh, Yousef; Chayjan, Reza Amiri; Taghinezhad, Ebrahim; Mohammadigol, Reza

2018-01-01

This research was investigated to the thin-layer drying of terebinth fruit under convective infrared microwave (CIM) conditions with initial moisture content about 4.28% (g water/g dry matter). The effects of drying different conditions were studied on the effective moisture diffusivity, activation energy, specific energy, shrinkage, color, and mechanical properties of terebinth. Experiments were conducted at three air temperatures (45, 60, and 70 °C), three infrared power (500, 1000, and 1500 W) and three microwave power (270, 450 and 630 W). All these experiments were carried out under air velocity of 0.9 m/s. The effective moisture diffusivity of terebinth was obtained as 1.79 × 10-9 to 15.77 × 10-9 m2/s during drying. The activation energy of terebinth samples was measured to be 12.70 to 32.28 kJ/mol. To estimate the drying kinetic of terebinth, seven mathematical models were used to fit the experimental data of thin-layer drying. Results showed that the Midilli et al. model withR 2 = 0.9999, χ 2 = 0.0001 andRMSE = 0.0099 had the best performance in prediction of moisture content. Specific energy consumption was within the range of 127.62 to 678.90 MJ/kg. The maximum shrinkage during drying was calculated 69.88% at the air temperature 75 °C, infrared power of 1500 W, and microwave power 630 W. Moreover, the maximum values of the ΔL ∗ (15.89), Δa ∗ (12.28), Δb ∗(-0.12), and total color difference (ΔE= 17.44) were calculated in this work. Also, the maximum rupture force and energy for dried terebinth were calculated to be 149.2 N and 2845.4 N.mm, respectively.

Mass transfer, physical, and mechanical characteristics of terebinth fruit ( Pistacia atlantica L.) under convective infrared microwave drying

NASA Astrophysics Data System (ADS)

Kaveh, Mohammad; Abbaspour-Gilandeh, Yousef; Chayjan, Reza Amiri; Taghinezhad, Ebrahim; Mohammadigol, Reza

2018-07-01

This research was investigated to the thin-layer drying of terebinth fruit under convective infrared microwave (CIM) conditions with initial moisture content about 4.28% (g water/g dry matter). The effects of drying different conditions were studied on the effective moisture diffusivity, activation energy, specific energy, shrinkage, color, and mechanical properties of terebinth. Experiments were conducted at three air temperatures (45, 60, and 70 °C), three infrared power (500, 1000, and 1500 W) and three microwave power (270, 450 and 630 W). All these experiments were carried out under air velocity of 0.9 m/s. The effective moisture diffusivity of terebinth was obtained as 1.79 × 10-9 to 15.77 × 10-9 m2/s during drying. The activation energy of terebinth samples was measured to be 12.70 to 32.28 kJ/mol. To estimate the drying kinetic of terebinth, seven mathematical models were used to fit the experimental data of thin-layer drying. Results showed that the Midilli et al. model with R 2 = 0.9999, χ 2 = 0.0001 and RMSE = 0.0099 had the best performance in prediction of moisture content. Specific energy consumption was within the range of 127.62 to 678.90 MJ/kg. The maximum shrinkage during drying was calculated 69.88% at the air temperature 75 °C, infrared power of 1500 W, and microwave power 630 W. Moreover, the maximum values of the Δ L ∗ (15.89), Δ a ∗ (12.28), Δ b ∗(-0.12), and total color difference (Δ E= 17.44) were calculated in this work. Also, the maximum rupture force and energy for dried terebinth were calculated to be 149.2 N and 2845.4 N.mm, respectively.

Material properties and fractography of an indirect dental resin composite.

PubMed

Quinn, Janet B; Quinn, George D

2010-06-01

Determination of material and fractographic properties of a dental indirect resin composite material. A resin composite (Paradigm, 3M-ESPE, MN) was characterized by strength, static elastic modulus, Knoop hardness, fracture toughness and edge toughness. Fractographic analyses of the broken bar surfaces was accomplished with a combination of optical and SEM techniques, and included determination of the type and size of the failure origins, and fracture mirror and branching constants. The flexure test mean strength+/-standard deviation was 145+/-17 MPa, and edge toughness, T(e), was 172+/-12N/mm. Knoop hardness was load dependent, with a plateau at 0.99+/-0.02 GPa. Mirrors in the bar specimens were measured with difficulty, resulting in a mirror constant of approximately 2.6 MPa m(1/2). Fracture in the bar specimens initiated at equiaxed material flaws that had different filler concentrations that sometimes were accompanied by partial microcracks. Using the measured flaw sizes, which ranged from 35 to 100 microm in size, and using estimates of the stress intensity shape factors, fracture toughness was estimated to be 1.1+/-0.2 MPa m(1/2). Coupling the flexure tests with fractographic examination enabled identification of the intrinsic strength limiting flaws. The same techniques could be useful in determining if clinical restorations of similar materials fail from the same causes. The existence of a strong load-dependence of the Knoop hardness of the resin composite is not generally mentioned in the literature, and is important for material comparisons and wear evaluation studies. Finally, the edge toughness test was found promising as a quantitative measure of resistance to edge chipping, an important failure mode in this class of materials. Copyright (c) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The Influence of Naringin or Hesperidin Dietary Supplementation on Broiler Meat Quality and Oxidative Stability

PubMed Central

Goliomytis, Michael; Kartsonas, Nikos; Charismiadou, Maria A.; Symeon, George K.; Simitzis, Panagiotis E.; Deligeorgis, Stelios G.

2015-01-01

An experiment was conducted to examine the effects of supplementing broiler feed with hesperidin or naringin, on growth performance, carcass characteristics, breast meat quality and the oxidative stability of breast and thigh meat. Two hundred and forty 1-day-old Ross 308 broiler chickens were randomly assigned to 6 groups. One of the groups served as a control (C) and was given commercial basal diets, whereas the other five groups were given the same diets further supplemented with naringin at 0.75 g/kg (N1), naringin at 1.5 g/kg (N2), hesperidin at 0.75 g/kg (E1), hesperidin at 1.5 g/kg (E2) and a-tocopheryl acetate at 0.2 g/kg (E). At 42 days of age, 10 chickens per treatment group were slaughtered for meat quality and oxidative stability assessment. No significant differences were observed among groups in final body weight, carcass weight and internal organs weights (P>0.05) apart from liver that decreased linearly with increased levels of naringin (P-linear<0.05). Regarding the breast meat quality parameters, only redness (a*) value was higher in E1 and N1 group compared to VE group (P<0.05), while all the others i.e. shear values (N/mm2), pH24, cooking loss (%) and L* and b* color parameters were not significantly different among groups (P>0.05). Measurement of lipid oxidation values showed that after hesperidin and naringin dietary supplementation, malondialdehyde values decreased in tissue samples in a dose depended manner (P-linear<0.05). In conclusion, hesperidin and naringin, positively influence meat antioxidative properties without negative implications on growth performance and meat quality characteristics in poultry, thus appearing as important additives for both the consumer and the industry. PMID:26509968

Tooth Eruption Results from Bone Remodelling Driven by Bite Forces Sensed by Soft Tissue Dental Follicles: A Finite Element Analysis

PubMed Central

Sarrafpour, Babak; Swain, Michael; Li, Qing; Zoellner, Hans

2013-01-01

Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true ‘eruptive force’ is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, ‘biological response units’ in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner surface of

Tooth eruption results from bone remodelling driven by bite forces sensed by soft tissue dental follicles: a finite element analysis.

PubMed

Sarrafpour, Babak; Swain, Michael; Li, Qing; Zoellner, Hans

2013-01-01

Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true 'eruptive force' is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, 'biological response units' in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner surface of the

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aliev, Ziya S., E-mail: ziyasaliev@gmail.com; Institute of Physics, ANAS, H.Javid ave. 131, AZ1143 Baku; Donostia International Physics Center

Single crystals of the ternary copper compounds CuTlS and CuTlSe have been successfully grown from stoichiometric melt by using vertical Bridgman-Stockbarger method. The crystal structure of the both compounds has been determined by powder and single crystal X-Ray diffraction. They crystallize in the PbFCl structure type with two formula units in the tetragonal system, space group P4/nmm, a=3.922(2); c=8.123(6); Z=2 and a=4.087(6); c=8.195(19) Å; Z=2, respectively. The band structure of the reported compounds has been analyzed by means of full-potential linearized augmented plane-wave (FLAPW) method based on the density functional theory (DFT). Both compounds have similar band structures and aremore » narrow-gap semiconductors with indirect band gap. The resistivity measurements agree with a semiconductor behavior although anomalies are observed at low temperature. - Graphical abstract: The crystal structures of CuTl and CuTlSe are isostructural with the PbFCl-type and the superconductor LiFeAs-type tetragonal structure. The band structure calculations confirmed that they are narrow-gap semiconductors with indirect band gaps of 0.326 and 0.083 eV. The resistivity measurements, although confirming the semiconducting behavior of both compounds exhibit unusual anomalies at low temperatures. - Highlights: • Single crystals of CuTlS and CuTlSe have been successfully grown by Bridgman-Stockbarger method. • The crystal structure of the both compounds has been determined by single crystal XRD. • The band structure of the both compounds has been analyzed based on the density functional theory (DFT). • The resistivity measurements have been carried out from room temperature down to 10 K.« less

Evaluation of Strength Characteristics of Laterized Concrete with Corn Cob Ash (CCA) Blended Cement

NASA Astrophysics Data System (ADS)

Ikponmwosa, E. E.; Salau, M. A.; Kaigama, W. B.

2015-11-01

Agricultural wastes are dumped in landfills or left on land in which they constitute nuisance. This study presents the results of investigation of strength characteristics of reinforced laterized concrete beams with cement partially replaced with corn cob (agricultural wastes) ash (CCA). Laterized concrete specimen of 25% laterite and 75% sharp sand were made by blending cement with corn cob ash at 0 to 40% in steps of 10%. A concrete mix ratio of 1:2:4 was used to cast 54 cubes of 150×150×150mm size and 54 beams of dimension 750×150×150mm. The results show that the consistency and setting time of cement increased as the percentage replacement of cement with CCA increased while the workability and density of concrete decreased as the percentage of CCA increased. There was a decrease in compressive strength when laterite was introduced to the concrete from 25.04 to 22.96N/mm2 after 28 days and a continual reduction in strength when CCA was further added from 10% to 40% at steps of 10%. Generally, the beam specimens exhibited majorly shear failure with visible diagonal cracks extending from support points to the load points. The corresponding central deflection in beams, due to two points loading, increased as the laterite was added to the concrete mix but reduced and almost approaching that of the control as 10% CCA was added. The deflection then increased as the CCA content further increased to 20%, 30% and 40% in the mix. It was also noted that the deflection of all percentage replacement including 40% CCA is less than the standard recommended maximum deflection of the beam. The optimal flexural strength occurred with 10% CCA content.

The crystal structures of BiTeO 3I, NdTeO 3X (X=Cl, Br) and Bi 5TeO 8.5I 2: some crystal chemistry peculiarities of layered Bi(Ln)Te oxyhalides

NASA Astrophysics Data System (ADS)

Berdonosov, Peter S.; Charkin, Dmitry O.; Kusainova, Ardak M.; Hervoches, Charles H.; Dolgikh, Valeriy A.; Lightfoot, Philip

2000-09-01

Four new layered oxyhalides related to the Sillen family have been prepared and characterized by Rietveld refinement of powder X-ray and neutron diffraction data. BiTeO 3I and NdTeO 3Br both adopt tetragonal symmetry, space group P4/ nmm (for BiTeO 3I, a=4.10811(8), c=27.988(1) Å; NdTeO 3Br, a=4.06603(7), c=26.922(1) Å, at 25°C). The structures are composed of triple and double fluorite-related mixed metal oxide layers separated by single and double halogen layers, in the sequence MTe 2O 5XXMTe 2O 5XM 2O 2X, which may be represented by the symbol X 13X 13X 22, where the subscript signifies the number of halogen layers and the superscript the number of metal sublayers within the fluorite block, by analogy with Sillen's notation. The double fluorite layers are occupied exclusively by Bi, whereas there is an ordered arrangement of Bi/Te within the triple fluorite layers, with Te exclusively occupying the outer sublayers of the block. NdTeO 3Cl adopts an orthorhombically distorted form of this structure type, space group Pmmn, a=4.08096(8), b=4.03441(8), c=25.7582(7) Å at 25°C. Bi 5TeO 8.5I 2 adopts a distorted, non-centrosymmetric version of the simpler X 13 structure type, space group Cmm2, a=5.6878(3), b=5.7230(3), c=9.7260(6) Å, consisting of single halogen layers sandwiched between triple fluorite layers, in which there is partial ordering of the Bi/Te cations.

Initial load-to-failure and failure analysis in single- and double-row repair techniques for rotator cuff repair.

PubMed

Baums, M H; Buchhorn, G H; Gilbert, F; Spahn, G; Schultz, W; Klinger, H-M

2010-09-01

This experimental study aimed to compare the load-to-failure rate and stiffness of single- versus double-row suture techniques for repairing rotator cuff lesions using two different suture materials. Additionally, the mode of failure of each repair was evaluated. In 32 sheep shoulders, a standardized tear of the infraspinatus tendon was created. Then, n = 8 specimen were randomized to four repair methods: (1) Double-row Anchor Ethibond coupled with polyester sutures, USP No. 2; (2) Double-Row Anchor HiFi with polyblend polyethylene sutures, USP No. 2; (3) Single-Row Anchor Ethibond coupled with braided polyester sutures, USP No. 2; and (4) Single-Row Anchor HiFi with braided polyblend polyethylene sutures, USP No. 2. Arthroscopic Mason-Allen stitches were placed (single-row) and combined with medial horizontal mattress stitches (double-row). All specimens were loaded to failure at a constant displacement rate on a material testing machine. Group 4 showed lowest load-to-failure result with 155.7 +/- 31.1 N compared to group 1 (293.4 +/- 16.1 N) and group 2 (397.7 +/- 7.4 N) (P < 0.001). Stiffness was highest in group 2 (162 +/- 7.3 N/mm) and lowest in group 4 (84.4 +/- 19.9 mm) (P < 0.001). In group 4, the main cause of failure was due to the suture cutting through the tendon (n = 6), a failure case observed in only n = 1 specimen in group 2 (P < 0.001). A double-row technique combined with arthroscopic Mason-Allen/horizontal mattress stitches provides high initial failure strength and may minimize the risk of the polyethylene sutures cutting through the tendon in rotator cuff repair when a single load force is used.

Rotator cuff bridging repair using acellular dermal matrix in large to massive rotator cuff tears: histologic and clinical analysis.

PubMed

Kim, Jong Ok; Lee, Jong-Ho; Kim, Kwang-Sup; Ji, Jong-Hun; Koh, Sung-Jun; Lee, Jae-Ho

2017-11-01

This study investigated the efficacy of the bridging repair using an acellular dermal matrix (ADM) and an ADM with stem cells in rabbits. Also investigated were clinical outcomes of ADM bridging repair for large to massive rotator cuff tears. ADM, with and without stem cells, was used to cover a 5- × 5-mm-sized cuff defect in 17 rabbits, and biomechanical, histologic, and immunohistochemical analyses were conducted. Also evaluated were 24 patients with large to massive rotator cuff tears after ADM bridging repair. In the biomechanical test, the normal rotator cuff, cuff with ADM plus stem cells, and cuff with ADM in the rabbit model showed a maximum load (N) of 287.3, 217.5, and 170.3 and ultimate tensile strength (N/mm 2 ) of 11.1, 8.0, and 5.2, respectively. Histologically, the cuff tendons with the ADM or ADM plus stem cells showed characteristically mature tendons as time passed. In the clinical study, the mean American Shoulder and Elbow Surgeons score improved from preoperative 50 to postoperative 83, the University of California Los Angeles Shoulder Rating Scale from 17 to 30, and the Simple Shoulder Test from 4 to 8, respectively. No further fatty deteriorations or muscle atrophy were observed on follow-up magnetic resonance imaging. A retear was found in 5 of 24 patients (21%). Bridging repair with ADM or stem cells in the rabbit model showed cellular infiltration into the graft and some evidence of neotendon formation. Clinically, ADM repair was a safe alternative that did not show any further fatty deterioration nor muscle atrophy in large to massive rotator cuff tears. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Developing Subdomain Allocation Algorithms Based on Spatial and Communicational Constraints to Accelerate Dust Storm Simulation

PubMed Central

Gui, Zhipeng; Yu, Manzhu; Yang, Chaowei; Jiang, Yunfeng; Chen, Songqing; Xia, Jizhe; Huang, Qunying; Liu, Kai; Li, Zhenlong; Hassan, Mohammed Anowarul; Jin, Baoxuan

2016-01-01

Dust storm has serious disastrous impacts on environment, human health, and assets. The developments and applications of dust storm models have contributed significantly to better understand and predict the distribution, intensity and structure of dust storms. However, dust storm simulation is a data and computing intensive process. To improve the computing performance, high performance computing has been widely adopted by dividing the entire study area into multiple subdomains and allocating each subdomain on different computing nodes in a parallel fashion. Inappropriate allocation may introduce imbalanced task loads and unnecessary communications among computing nodes. Therefore, allocation is a key factor that may impact the efficiency of parallel process. An allocation algorithm is expected to consider the computing cost and communication cost for each computing node to minimize total execution time and reduce overall communication cost for the entire simulation. This research introduces three algorithms to optimize the allocation by considering the spatial and communicational constraints: 1) an Integer Linear Programming (ILP) based algorithm from combinational optimization perspective; 2) a K-Means and Kernighan-Lin combined heuristic algorithm (K&K) integrating geometric and coordinate-free methods by merging local and global partitioning; 3) an automatic seeded region growing based geometric and local partitioning algorithm (ASRG). The performance and effectiveness of the three algorithms are compared based on different factors. Further, we adopt the K&K algorithm as the demonstrated algorithm for the experiment of dust model simulation with the non-hydrostatic mesoscale model (NMM-dust) and compared the performance with the MPI default sequential allocation. The results demonstrate that K&K method significantly improves the simulation performance with better subdomain allocation. This method can also be adopted for other relevant atmospheric and numerical

Development of the monitoring technique on the damage of piles using the biggest shaking table "E-defense"

NASA Astrophysics Data System (ADS)

Hayashi, Kazuhiro; Hachimori, Wataru; Kaneda, Shogo; Tamura, Shuji; Saito, Taiki

2017-10-01

In case of earthquake damage to buildings, the damage to a superstructure is visible, but the damage to a foundation structure, e.g. the underground pile, is difficult to detect. In this study, the authors aim to develop a monitoring technique for pile damage due to earthquakes. The world's biggest shaking table, E-Defense, was used to reproduce damage to RC pile models embedded in the soil inside a large scale shear box (8m in diameter and 6.5m in height). The diameter of the RC pile model was 154mm. It consisted of mortar (27.2N/mm2 in compressive strength), 6 main reinforcements (6.35mm in diameter) and shear reinforcement hard steel wire (2mm in diameter at intervals of 20mm). The natural period of the superstructure above the pile models is around 0.12sec. The soil consisted of 2 layers. The lower layer is Albany sand of 80% relative density while the upper layer is only 2m from the surface ground and is Kaketsu sand of 60% relative density. Primary four excitations were scaled from JMA Kobe waves in notification at different amplitudes. The maximum acceleration of each wave is 31gal, 67gal, 304gal, and 458gal, respectively. In the test result, reinforcing steels at the pile head of the RC model yielded when the maximum acceleration was 304gal. After that, mortar of the pile head peeled off and a bending shear failure occurred when the maximum acceleration was 458gal. The peak frequency of rotational spectrum on the foundation did not change in elastic range in the piles. However, the peak frequency fell after the plastic hinge occurred.

[Reinforcement for overdentures on abutment teeth].

PubMed

Osada, Tomoko

2006-04-01

This study investigated the effect of the position of reinforcement wires, differences in artificial teeth, and framework designs on the breaking strength of overdentures. The basal surfaces of composite resin teeth and acrylic resin teeth were removed using a carbide bur. A reinforcement wire or a wrought palatal bar was embedded near the occlusal surface or basal surface. Four types of framework structures were designed : conventional skeleton (skeleton), housing with skeleton (housing), housing plus short metal backing (metal backing), and housing plus long metal backing (double structure). After the wires, bars, and frameworks were sand-blasted with 50 microm Al(2)O(3) powder, they were primed with a metal primer and embedded in a heat-polymerized denture base resin. The breaking strengths (N) and maximum stiffness (N/mm) of two-week aged (37 degrees C) specimens were measured using a bending test (n=8). All data obtained at a crosshead speed of 2.0 mm/min were analyzed by ANOVA/Tukey's test (alpha=0.01). There were no statistical differences between the two kinds of artificial teeth (p>0.01). The wrought palatal bar had significantly higher strength than the reinforcement wire (p<0.01). Greater strengths were found for specimens with frameworks than those without frameworks (p<0.01). The breaking strength of the wrought palatal bar embedded near the occlusal surface was higher than that on the basal surface (p>0.01). The breaking strength and maximum stiffness of the double structure framework were significantly greater (p<0.01) than those of the conventional frameworks. The breaking strengths of overdentures were influenced by the size and position of the reinforcement wires. Double structure frameworks are recommended for overdentures to promote a long-term prognosis without denture breakage.

Toughening mechanisms in laminated composites: A biomimetic study in mollusk shells

NASA Astrophysics Data System (ADS)

Kamat, Shekhar Shripad

2000-10-01

Mollusk shells can be described as structural biocomposite materials composed of a mineral (aragonite) and a continuous, albeit minor, organic (protein) component. The conch shell, Strombus Gigas, has intermediate strength and high fracture toughness. The high fracture toughness is a result of enhanced energy dissipation during crack propagation due to delamination, crack bridging, frictional sliding etc. A theoretical and experimental study was conducted on the crack bridging mechanisms operative in the shell. Four-point bend tests were conducted. Acoustic emission and post-mortem dye penetrants were used to characterize the crack propagation, together with conventional fractography. A two layer composite configuration is seen in the shells, with the tough and weak layers having a toughness ratio of ˜4 (Ktough = 2.2MPam1/2). This toughness ratio is a requisite for multiple cracking in the weak layer. A theoretical shear lag analysis of the crack bridging phenomena in the tough layer is shown to lead to a bridging law for the crack wake of the form of p = betau1/2 (p is the bridging traction for a crack opening u, with beta, being a constant of proportionality). Finite element analysis yielded a value of beta = 630 Nmm-5/2 and ucritical = 5 mum for the bridging law parameters. In a nonlinear fracture mechanics phenomenology, these values are relevant material parameters, rather than a critical stress intensity factor. The work of fracture for unnotched specimens is three orders of magnitude higher than mineral aragonite, and is demonstrated numerically incorporating the toughening mechanisms in the shell. Similar structural adaptations have been observed and studied in the red abalone shell, haliotis rufescens and the spines of the sea urchin, Heterocentrotus trigonarius. The toughening mechanisms seen in these shells give insight into structural design needs of brittle matrix composites (BMC) as well as conventional structural ceramics.

Effect of chemical disinfectant on the transverse strength of heat-polymerized acrylic resins subjected to mechanical and chemical polishing: an in vitro study.

PubMed

Sharan, Smitha; Kavitha, H R; Konde, Harish; Kalahasti, Deepthi

2012-05-01

To evaluate the effect of chemical disinfectant on the transverse strength of heat-polymerized acrylic resins subjected to mechanical and chemical polishing. A total of 256 rectangular specimens (65 * 10 * 3 mm) 128 per resin (Lucitone-199 and Acralyn-H) were fabricated. One side of each specimen was not polished and the other was either mechanically (n = 96) or chemically (n = 96) polished and immersed for 10, 30 and 60 minutes in 2% alkaline glutaraldehyde. Mechanically polished (n = 32) and chemically polished (n = 32) control specimens were immersed only in distilled water. The transverse strength (N/mm(2)) was tested for failure in a universal testing machine, at a crosshead speed of 5 mm/min. Data were statistically analyzed using 2-way ANOVA and Student t-test. chemical polishing resulted in significantly lower transverse strength values than mechanical polishing. Lucitone- 199 resin demonstrated the highest overall transverse strength for the materials tested. Heat-polymerized acrylic resins either mechanically or chemically polished, did not demonstrate significant changes in transverse strength during immersion in the disinfecting solution tested, regardless of time of immersion. Lucitone-199 resin demonstrated the highest overall transverse strength for the materials tested and significantly stronger than Acralyn-H with either type of polishing following immersion in 2% alkaline glutaraldehyde. There is a concern that immersion in chemical solutions often used for cleansing and disinfection of prostheses may undermine the strength and structure of denture base resins. In this study it was observed that, the transverse strength of samples of Lucitone-199 was higher than that of the samples of Acralyn-H. The chances of fracture of the denture made of Lucitone-199 are less than that of dentures made of Acralyn-H. The chemically polished dentures may be more prone to fracture than mechanically polished dentures.

Crystal Chemistry of Electrochemically and Chemically Lithiated Layered α I-LiVOPO 4

DOE PAGES

He, Guang; Bridges, Craig A.; Manthiram, Arumugam

2015-09-14

LiVOPO 4 is an attractive cathode for lithium-ion batteries with a high operating voltage and the potential to achieve the reversible insertion of two lithium ions between VOPO 4 and Li 2VOPO 4. Among the three known forms of LiVOPO 4 (α, β, and αI), the α I-LiVOPO 4 has a layered structure that could promote better ionic mobility and reversibility than others. However, a comprehensive study of its lithiated product is not available as αI-LiVOPO 4 is metastable and difficult to prepare by conventional approaches. We present here a facile synthesis of highly crystalline αI-LiVOPO 4 and α I-LiVOPOmore » 4/rGO nanocomposite by a microwave-assisted solvothermal method and its electrochemical/chemical lithiation. The LiVOPO 4/rGO cathodes exhibit a high reversible capacity of 225 mAh g –1, indicating the insertion of more than one lithium into VOPO 4. Both electrochemical and chemical lithiation imply a solid-solution reaction mechanism on inserting the second lithium into α I-LiVOPO 4, but a two-phase reaction feature could also occur under certain conditions such as insufficient time for equilibration of Li + diffusion in the structure. The fully lithiated new α I-Li 2VOPO 4 phase was characterized by combined Rietveld refinement of neutron diffraction and X-ray diffraction data and by bond-valence sum maps. The results suggest that αI-Li 2VOPO 4 retains the tetragonal P4/nmm symmetry of the parent α I-LiVOPO 4 structure, where the second lithium ions are located in the lithium layers rather than in the VOPO 4 layers« less

Biomechanics of the L5-S1 motion segment after total disc replacement - Influence of iatrogenic distraction, implant positioning and preoperative disc height on the range of motion and loading of facet joints.

PubMed

Dreischarf, Marcel; Schmidt, Hendrik; Putzier, Michael; Zander, Thomas

2015-09-18

Total disc replacement has been introduced to overcome negative side effects of spinal fusion. The amount of iatrogenic distraction, preoperative disc height and implant positioning have been considered important for surgical success. However, their effect on the postoperative range of motion (RoM) and loading of the facets merits further discussion. A validated osteoligamentous finite element model of the lumbosacral spine was employed and extended with four additional models to account for different disc heights. An artificial disc with a fixed center of rotation (CoR) was implemented in L5-S1. In 4000 simulations, the influence of distraction and the CoR's location on the RoM, facet joint forces (FJFs) and facet capsule ligament forces (FCLFs) was investigated. Distraction substantially altered segmental kinematics in the sagittal plane by decreasing range of flexion (0.5° per 1mm of distraction), increasing range of extension (0.7°/mm) and slightly affecting complete sagittal RoM (0.2°/mm). The distraction already strongly increased the FCLFs during surgery (up to 230N) and in flexion (~12N/mm), with higher values in models with larger preoperative disc heights, and increased FJFs in extension. A more anterior implant location decreased the RoM in all planes. In most loading cases, a more posterior location of the implant's CoR increased the FJFs and FCLFs, whereas a more caudal location increased the FCLFs but decreased the FJFs. The results of this study may explain the worse clinical results in patients with overdistraction after TDR. The complete RoM in the sagittal plane appears to be insensitive to detecting surgery-related biomechanical changes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Water in Volcanic Glass: From Volcanic Degassing to Secondary Hydration

NASA Astrophysics Data System (ADS)

Seligman, A. N.; Bindeman, I. N.; Palandri, J. L.; Watkins, J. M.; Ross, A. M.

2015-12-01

Volcanic glass contains both primary magmatic and secondary meteoric dissolved water, which can have distinguishable hydrogen isotopic ratios. We analyzed compositionally and globally diverse volcanic glass from recent to 640 ka for their δD (‰, VSMOW) and H2Ot (wt.%) on the TC/EA MAT 253 continuous flow system. We find that rhyolite glass is hydrated faster than basaltic glass, and in the majority of glasses an increase in age and total water content leads to a decrease in δD (‰), which is opposite the trend for magmatic degassing, while a few equatorial glasses have little change in δD (‰). To better understand these results, we imaged 6 tephra clasts ranging in age and chemical composition using BSE (by FEI SEM) down to a resolution of ~1 mm. Mafic tephra have lower vesicle number densities (N/mm2 = 25-77) than silicic tephra (736) and thicker average bubble walls (0.07 mm) than silicic tephra (0.02 mm). Lengths of water diffusion were modeled by finite difference using H2Ot concentration-dependent diffusion coefficients for diffusion of water into basalt and rhyolite glass using Zhang et al. (2007) and Ni and Zhang (2008) diffusion parameterizations extrapolated to surface temperatures. Due to the 106 times slower diffusion, water only diffused ~10-5 mm into basaltic glass and ~10 mm into rhyolitic glass after 1000 years. These hydration rates match our H2Ot wt.% values for basaltic tephra, and would cause a rhyolite glass, with an average bubble wall thickness of 0.02 mm as described above, to already be fully hydrated with ~3.0-3.5 wt.% H2Ot after ~1000 years, which is similar to what we observe. Results here are our initial steps in understanding water diffusion rates at ambient temperature in basalt and rhyolite tephra, and the isotopic changes that occur during hydration, which have implications for research in physical volcanology (quantities of residual magmatic water) and paleoenvironments (low temperature hydration rates and isotopic changes

Vertical leaping mechanics of the Lesser Egyptian Jerboa reveal specialization for maneuverability rather than elastic energy storage.

PubMed

Moore, Talia Y; Rivera, Alberto M; Biewener, Andrew A

2017-01-01

Numerous historical descriptions of the Lesser Egyptian jerboa, Jaculus jaculus , a small bipedal mammal with elongate hindlimbs, make special note of their extraordinary leaping ability. We observed jerboa locomotion in a laboratory setting and performed inverse dynamics analysis to understand how this small rodent generates such impressive leaps. We combined kinematic data from video, kinetic data from a force platform, and morphometric data from dissections to calculate the relative contributions of each hindlimb muscle and tendon to the total movement. Jerboas leapt in excess of 10 times their hip height. At the maximum recorded leap height (not the maximum observed leap height), peak moments for metatarso-phalangeal, ankle, knee, and hip joints were 13.1, 58.4, 65.1, and 66.9 Nmm, respectively. Muscles acting at the ankle joint contributed the most work (mean 231.6 mJ / kg Body Mass) to produce the energy of vertical leaping, while muscles acting at the metatarso-phalangeal joint produced the most stress (peak 317.1 kPa). The plantaris, digital flexors, and gastrocnemius tendons encountered peak stresses of 25.6, 19.1, and 6.0 MPa, respectively, transmitting the forces of their corresponding muscles (peak force 3.3, 2.0, and 3.8 N, respectively). Notably, we found that the mean elastic energy recovered in the primary tendons of both hindlimbs comprised on average only 4.4% of the energy of the associated leap. The limited use of tendon elastic energy storage in the jerboa parallels the morphologically similar heteromyid kangaroo rat, Dipodomys spectabilis . When compared to larger saltatory kangaroos and wallabies that sustain hopping over longer periods of time, these small saltatory rodents store and recover less elastic strain energy in their tendons. The large contribution of muscle work, rather than elastic strain energy, to the vertical leap suggests that the fitness benefit of rapid acceleration for predator avoidance dominated over the need to enhance

Hairpin assembly circuit-based fluorescence cooperative amplification strategy for enzyme-free and label-free detection of small molecule.

PubMed

Feng, Chunjing; Zhu, Jing; Sun, Jiewei; Jiang, Wei; Wang, Lei

2015-10-01

Here, we developed an enzyme-free, label-free, and sensitive fluorescence cooperative amplification strategy based on a hairpin assembly circuit which coupled catalytic hairpin assembly (CHA) with hybridization chain reaction (HCR) for small molecule adenosine. A double-strand DNA probe with aptamer-catalysis strand (Apt-C) and inhibit strand (Inh) was designed for adenosine recognition and signal transduction which was named as Apt-C/Inh. Hairpins H1 and H2 were employed for constructing the CHA, and hairpins H3 and H4 for the HCR. Through the binding of adenosine and the Apt-C, the Inh was released from the Apt-C/Inh. Then the free Apt-C initiated the CHA through successively opening H1 and H2, generating H1/H2 complex and recyclable Apt-C. Next, the released Apt-C entered another CHA cycle, and the H1/H2 complex further initiated the HCR of H3 and H4 which induced the formation of the concatemers of H3/H4 complex. Such a process brought the two ends of hairpins H3 into close proximity, yielding numerous integrated G-quadruplexes which were initially sequestered in the stem and two terminals of H3. Finally, N-methyl mesoporphyrin IX (NMM) was added to generate an enhanced fluorescence signal. In the proposed strategy, driven only by the energy from hybridization, one target could trigger multiple HCR events via CHA-based target-cycle, leading to a remarkable enzyme-free amplification for adenosine. The detection limit could achieve as low as 9.7 × 10(-7) mol L(-1). Furthermore, G-quadruplexes were applied to construct label-free hairpin assembly circuit, which made it more simple and cost-effective. The satisfactory recoveries were obtained when detecting adenosine in spiked human serum and urine samples, demonstrating the feasibility of this detection strategy in biological samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Tissue engineering human small-caliber autologous vessels using a xenogenous decellularized connective tissue matrix approach: preclinical comparative biomechanical studies.

PubMed

Heine, Jörg; Schmiedl, Andreas; Cebotari, Serghei; Karck, Matthias; Mertsching, Heike; Haverich, Axel; Kallenbach, Klaus

2011-10-01

Suggesting that bioartificial vascular scaffolds cannot but tissue-engineered vessels can withstand biomechanical stress, we developed in vitro methods for preclinical biological material testings. The aim of the study was to evaluate the influence of revitalization of xenogenous scaffolds on biomechanical stability of tissue-engineered vessels. For measurement of radial distensibility, a salt-solution inflation method was used. The longitudinal tensile strength test (DIN 50145) was applied on bone-shaped specimen: tensile/tear strength (SigmaB/R), elongation at maximum yield stress/rupture (DeltaB/R), and modulus of elasticity were determined of native (NAs; n = 6), decellularized (DAs; n = 6), and decellularized carotid arteries reseeded with human vascular smooth muscle cells and human vascular endothelial cells (RAs; n = 7). Radial distensibility of DAs was significantly lower (113%) than for NAs (135%) (P < 0.001) or RAs (127%) (P = 0.018). At levels of 120 mm Hg and more, decellularized matrices burst (120, 160 [n = 2] and 200 mm Hg). Although RAs withstood levels up to 300 mm Hg, ANOVA revealed a significant difference from NA (P = 0.018). Compared with native vessels (NAs), SigmaB/R values were lower in DAs (44%; 57%) (P = 0.014 and P = 0.002, respectively) and were significantly higher in RAs (71%; 83%) (both P < 0.001). Similarly, DeltaB/R values were much higher in DAs compared with NAs (94%; 88%) (P < 0.001) and RAs (87%; 103%) (P < 0.001), but equivalent in NAs and RAs. Modulus of elasticity (2.6/1.1/3.7 to 16.6 N/mm(2)) of NAs, DAs, RAs was comparable (P = 0.088). Using newly developed in vitro methods for small-caliber vascular graft testing, this study proved that revitalization of decellularized connective tissue scaffolds led to vascular graft stability able to withstand biomechanical stress mimicking the human circulation. This tissue engineering approach provides a sufficiently stable autologized graft. © 2011, Copyright the Authors. Artificial

Antiferromagnetism in EuCu 2As 2 and EuCu 1.82Sb 2 single crystals

DOE PAGES

Anand, V. K.; Johnston, D. C.

2015-05-07

Single crystals of EuCu 2As 2 and EuCu 2Sb 2 were grown from CuAs and CuSb self-flux, respectively. The crystallographic, magnetic, thermal, and electronic transport properties of the single crystals were investigated by room-temperature x-ray diffraction (XRD), magnetic susceptibility χ versus temperature T, isothermal magnetization M versus magnetic field H, specific heat C p(T), and electrical resistivity ρ(T) measurements. EuCu 2As 2 crystallizes in the body-centered tetragonal ThCr 2Si 2-type structure (space group I4/mmm), whereas EuCu 2Sb 2 crystallizes in the related primitive tetragonal CaBe 2Ge 2-type structure (space group P4/nmm). The energy-dispersive x-ray spectroscopy and XRD data for themore » EuCu 2Sb 2 crystals showed the presence of vacancies on the Cu sites, yielding the actual composition EuCu 1.82Sb 2. The ρ(T) and C p(T) data reveal metallic character for both EuCu 2As 2 and EuCu 1.82Sb 2. Antiferromagnetic (AFM) ordering is indicated from the χ(T),C p(T), and ρ(T) data for both EuCu 2As 2 (T N = 17.5 K) and EuCu 1.82Sb 2 (T N = 5.1 K). In EuCu 1.82Sb 2, the ordered-state χ(T) and M(H) data suggest either a collinear A-type AFM ordering of Eu +2 spins S = 7/2 or a planar noncollinear AFM structure, with the ordered moments oriented in the tetragonal ab plane in either case. This ordered-moment orientation for the A-type AFM is consistent with calculations with magnetic dipole interactions. As a result, the anisotropic χ(T) and isothermal M(H) data for EuCu 2As 2, also containing Eu +2 spins S = 7/2, strongly deviate from the predictions of molecular field theory for collinear AFM ordering and the AFM structure appears to be both noncollinear and noncoplanar.« less

Biomechanical characteristics of the horizontal mattress stitch: implication for double-row and suture-bridge rotator cuff repair.

PubMed

Tamboli, Mallika; Mihata, Teruhisa; Hwang, James; McGarry, Michelle H; Kang, Yangmi; Lee, Thay Q

2014-03-01

We investigated the effects of bite-size horizontal mattress stitch (distance between the limbs passed through the tendon) on the biomechanical properties of the repaired tendon. We anchored 20 bovine Achilles tendons to bone using no. 2 high-strength suture and 5-mm titanium suture anchors in a mattress-suture technique. Tendons were allocated randomly into two groups of ten each to receive stitches with a 4- or 10-mm bite. Specimens underwent cyclic loading from 5 to 30 N at 1 mm/s for 30 cycles, followed by tensile testing to failure. Gap formation, tendon strain, hysteresis, stiffness, yield load, ultimate load, energy to yield load, and energy to ultimate load were compared between groups using unpaired t tests. The 4-mm group had less (p < 0.05) gap formation and less (p < 0.05) longitudinal strain than did the 10-mm group. Ultimate load (293.6 vs. 148.9 N) and energy to ultimate load (2,563 vs. 1,472 N-mm) were greater (p < 0.001) for the 10-mm group than the 4-mm group. All tendons repaired with 4-mm suturing failed at the suture-tendon interface, with sutures pulling through the tendon, whereas the suture itself failed before the tendon did in seven of the ten specimens in the 10-mm group. Whereas a 4-mm bite fixed the tendon more tightly but at the cost of decreased ultimate strength, a 10-mm bite conveyed greater ultimate strength but with increased gap and strain. These results suggest that for the conventional double-row repair, small mattress stitches provide a tighter repair, whereas large stitches are beneficial to prevent sutures from pulling through the tendon after surgery. For suture-bridge rotator cuff repair, large stitches are beneficial because the repaired tendon has a higher strength, and the slightly mobile medial knot can be tightened by lateral fixation.

A biomechanical comparison of 2 technical variations of double-row rotator cuff fixation: the importance of medial row knots.

PubMed

Busfield, Benjamin T; Glousman, Ronald E; McGarry, Michelle H; Tibone, James E; Lee, Thay Q

2008-05-01

Previous studies have shown comparable biomechanical properties of double-row fixation versus double-row fixation with a knotless lateral row. SutureBridge is a construct that secures the cuff with medial row mattress suture anchors and knotless lateral row fixation of the medial suture ends. Recent completely knotless constructs may lead to lesser clinical outcomes if the construct properties are compromised from lack of suture knots. A completely knotless construct without medial row knots will compromise the biomechanical properties in both cyclic and failure-testing parameters. Controlled laboratory study. Six matched pairs of cadaveric shoulders were randomized to 2 groups of double row fixation with SutureBridge: group 1 with medial row knots, and group 2 without medial row knots. The specimens were placed in a materials test system at 30 degrees of abduction. Cyclic testing to 180 N at 1 mm/sec for 30 cycles was performed, followed by tensile testing to failure at 1 mm/sec. Data included cyclic and failure data from the materials test system and gap data using a video digitizing system. All data from paired specimens were compared using paired Student t tests. Group 1 had a statistically significant difference (P < .05) for gap formation for the 1st (3.47 vs 5.05 mm) and 30th cycle (4.22 vs 8.10 mm) and at yield load (5.2 vs 9.1 mm). In addition, there was a greater energy absorbed (2805 vs 1648 N-mm), yield load (233 vs 183.1 N), and ultimate load (352.9 vs 253.9 N) for group 1. The mode of failure for the majority (4/6) of group 2 was lateral row failure, whereas all group 1 specimens failed at the clamp. Although lateral row knotless fixation has been shown not to sacrifice structural integrity of this construct, the addition of a knotless medial row compromises the construct leading to greater gapping and failure at lower loads. This may raise concerns regarding recently marketed completely knotless double row constructs.

Clinical Results and Mechanical Properties of the Carotid CGUARD Double-Layered Embolic Prevention Stent.

PubMed

Wissgott, Christian; Schmidt, Wolfram; Brandt-Wunderlich, Christoph; Behrens, Peter; Andresen, Reimer

2017-02-01

To report early clinical outcomes with a novel double-layer stent for the internal carotid artery (ICA) and the in vitro investigation of the stent's mechanical properties. A prospective single-center study enrolled 30 consecutive patients (mean age 73.1±6.3 years; 21 men) with symptomatic (n=25) or high-grade (n=5) ICA stenosis treated with the new double-layer carotid CGUARD Embolic Prevention System (EPS) stent, which has an inner open-cell nitinol design with an outer closed-cell polyethylene terephthalate layer. The average stenosis of the treated arteries was 84.1%±7.9% with a mean lesion length of 16.6±2.1 mm. In the laboratory, 8×40-mm stents where tested in vitro with respect to their radial force during expansion, the bending stiffness of the stent system and the expanded stent, as well as the collapse pressure in a thin and flexible sheath. The wall adaptation was assessed using fluoroscopy after stent release in step and curved vessel models. The stent was successfully implanted in all patients. No peri- or postprocedural complications occurred; no minor or major stroke was observed in the 6-month follow-up. The bending stiffness of the expanded stent was 63.1 N·mm 2 and (not unexpectedly) was clearly lower than that of the stent system (601.5 N·mm 2 ). The normalized radial force during expansion of the stent to 7.0 mm, consistent with in vivo sizing, was relatively high (0.056 N/mm), which correlates well with the collapse pressure of 0.17 bars. Vessel wall adaptation was harmonic and caused no straightening of the vessel after clinical application. Because of its structure, the novel CGUARD EPS stent is characterized by a high flexibility combined with a high radial force and very good plaque coverage. These first clinical results demonstrate a very safe implantation behavior without any stroke up to 6 months after the procedure.

Altered Achilles tendon function during walking in people with diabetic neuropathy: implications for metabolic energy saving.

PubMed

Petrovic, M; Maganaris, C N; Deschamps, K; Verschueren, S M; Bowling, F L; Boulton, A J M; Reeves, N D

2018-05-01

The Achilles tendon (AT) has the capacity to store and release elastic energy during walking, contributing to metabolic energy savings. In diabetes patients, it is hypothesized that a stiffer Achilles tendon may reduce the capacity for energy saving through this mechanism, thereby contributing to an increased metabolic cost of walking (CoW). The aim of this study was to investigate the effects of diabetes and diabetic peripheral neuropathy (DPN) on the Achilles tendon and plantarflexor muscle-tendon unit behavior during walking. Twenty-three nondiabetic controls (Ctrl); 20 diabetic patients without peripheral neuropathy (DM), and 13 patients with moderate/severe DPN underwent gait analysis using a motion analysis system, force plates, and ultrasound measurements of the gastrocnemius muscle, using a muscle model to determine Achilles tendon and muscle-tendon length changes. During walking, the DM and particularly the DPN group displayed significantly less Achilles tendon elongation (Ctrl: 1.81; DM: 1.66; and DPN: 1.54 cm), higher tendon stiffness (Ctrl: 210; DM: 231; and DPN: 240 N/mm), and higher tendon hysteresis (Ctrl: 18; DM: 21; and DPN: 24%) compared with controls. The muscle fascicles of the gastrocnemius underwent very small length changes in all groups during walking (~0.43 cm), with the smallest length changes in the DPN group. Achilles tendon forces were significantly lower in the diabetes groups compared with controls (Ctrl: 2666; DM: 2609; and DPN: 2150 N). The results strongly point toward the reduced energy saving capacity of the Achilles tendon during walking in diabetes patients as an important factor contributing to the increased metabolic CoW in these patients. NEW & NOTEWORTHY From measurements taken during walking we observed that the Achilles tendon in people with diabetes and particularly people with diabetic peripheral neuropathy was stiffer, was less elongated, and was subject to lower forces compared with controls without diabetes. These

Identifying factors related to Achilles tendon stress, strain, and stiffness before and after 6 months of growth in youth 10-14 years of age.

PubMed

Neugebauer, Jennifer M; Hawkins, David A

2012-09-21

The purposes of this study were (1) determine if youth peak Achilles tendon (AT) strain, peak AT stress, and AT stiffness, measured during an isometric plantar flexion, differed after six months (mos) of growth, and (2) determine if sex, physical activity level (Physical Activity Questionnaire (PAQ-C)), and/or growth rate (GR) were related to these properties. AT stress, strain, and stiffness were quantified in 20 boys (13.47±0.81 years) and 22 girls (11.18±0.82 years) at 2 times (0 and 6 mos). GR (change in height in 6 mos) was not significantly different between boys and girls (3.5±1.4 and 3.4±1.1cm/6 mos respectively). Peak AT strain and stiffness (mean 3.8±0.4% and 128.9±153.6N/mm, respectively) did not differ between testing sessions or sex. Peak AT stress (22.1±2.4 and 24.0±2.1MPa at 0 and 6 mos, respectively) did not differ between sex and increased significantly at 6 mos due to a significant decrease in AT cross-sectional area (40.6±1.3 and 38.1±1.6mm(2) at 0 and 6 mos, respectively) with no significant difference in peak AT force (882.3±93.9 and 900.3± 65.5N at 0 and 6 mos, respectively). Peak AT stress was significantly greater in subjects with greater PAQ-C scores (9.1% increase with 1 unit increase in PAQ-C score) and smaller in subjects with faster GRs (13.8% decrease with 1cm/6 mos increase in GR). These results indicate that of the AT mechanical properties quantified, none differed between sex, and only peak AT stress significantly differed after 6 months and was related to GR and physical activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Biomechanical comparison of three different plate configurations for comminuted clavicle midshaft fracture fixation.

PubMed

Uzer, Gokcer; Yildiz, Fatih; Batar, Suat; Bozdag, Ergun; Kuduz, Hacer; Bilsel, Kerem

2017-12-01

The aim of this study was to compare the fixation rigidity of anterior, anterosuperior, and superior plates in the treatment of comminuted midshaft clavicle fractures. Six-hole titanium alloy plates were produced according to anatomic features of fourth-generation artificial clavicle models for anterior (group I; n = 14), anterosuperior (group II; n = 14), and superior (group III; n = 14) fixation. After plate fixation, 5-mm segments were resected from the middle third of each clavicle to create comminuted fracture models. Half the models from each group were tested under rotational forces; the other half were tested under 3-point bending forces. Failure modes, stiffness values, and failure loads were recorded. All models fractured at the level of the distalmost screw during the failure torque, whereas several failure modes were observed in 3-point bending tests. The mean stiffness values of groups I to III were 636 ± 78, 767 ± 72, and 745 ± 214 N ∙ mm/deg (P = .171), respectively, for the torsional tests and 38 ± 5, 20 ± 3, and 13 ± 2 N/mm, respectively, for the bending tests (P < .001 for group I vs. groups II and III; P = .015 for group II vs. group III). The mean failure torque values of groups I to III were 8248 ± 2325, 12,638 ± 1749, and 10,643 ± 1838 N ∙ mm (P = .02 for group I vs. II), respectively, and the mean failure loads were 409 ± 81, 360 ± 122, and 271 ± 87 N, respectively (P = .108). In the surgical treatment of comminuted midshaft clavicle fractures, the fixation strength of anterosuperior plating was greater than that of anterior plating under rotational forces and similar to that of superior plating. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Patient-related factors influence stiffness of the soft tissue complex during intraoperative gap balancing in cruciate-retaining total knee arthroplasty.

PubMed

Heesterbeek, P J C; Haffner, N; Wymenga, A B; Stifter, J; Ritschl, P

2017-09-01

How much force is needed to pre-tension the ligaments during total knee arthroplasty? The goal of this study was to determine this force for extension and flexion, and for both compartments, and to identify predicting patient-related factors. Eighty patients [55 females, mean age 71 (SD 9.7)] were recruited and had a navigated cruciate-retaining total knee arthroplasty. Distraction of the medial and lateral compartments of the extension and flexion gap (90°) with an instrumented bi-compartmental double-spring tensioner took place after finishing the bone cuts. Applied forces and resulting gap distances were recorded by the navigation system, resulting in a force-elongation curve. Lines were fitted with the intersection defined as the stiffness transition point. The slopes (N/mm) represented the stiffness of the ligamentous complex. Linear multiple regression analysis was performed to identify predicting factors. The amount of force at the stiffness transition point was on average 52.3 (CI 95 50.7-53.9), 54.5 (CI 95 52.7-56.3), 48.3 (CI 95 46.2-50.2), and 59.3 (CI 95 57.0-61.6) N for the medial and lateral extension and flexion gap, respectively, and varied considerably between patients. The force at the stiffness transition point was significantly different between extension and flexion and both compartments (P < 0.05). Stiffness of the ligaments statistically significantly helped to predict the amount of force at the stiffness transition point, as well as body mass index, gender, and varus-valgus alignment. The amount of force at the stiffness transition point varies between 48 and 59 N, depending on flexion/extension and compartment. Patient-related factors influence the stiffness transition point and can help predict the stiffness transition point. When forces higher than 60 N are used for gap distraction, the ligamentous sleeve of the knee might be over-tensioned. Prognostic study, Level I-high-quality prospective cohort study with >80 % follow-up, and

Insulin-induced capillary recruitment is impaired in both lean and obese women with PCOS.

PubMed

Ketel, I J G; Serné, E H; Ijzerman, R G; Korsen, T J M; Twisk, J W; Hompes, P G A; Smulders, Y M; Homburg, R; Vorstermans, L; Stehouwer, C D A; Lambalk, C B

2011-11-01

Insulin resistance, i.e. impaired insulin-mediated glucose uptake (IMGU), is a major risk factor for type 2 diabetes in women with polycystic ovary syndrome (PCOS). Insulin-induced capillary recruitment (IICR) is considered a significant determinant of IMGU. We investigated whether IICR is a determinant IMGU in obese and lean women with and without PCOS. The study included 36 women with PCOS (20 lean, BMI 21.9 ± 2.3 kg/m(2) and 16 obese, BMI 35.9 ± 6.0 kg/m(2)) and 27 age-matched healthy controls (14 lean, BMI 22.2 ± 1.8 kg/m(2) and 13 obese, BMI 40.5 ± 7.0 kg/m(2)). IICR was evaluated by capillary microscopy during an isoglycemic-hyperinsulinemic clamp. IMGU was expressed as M/I value. The M/I value was significantly lower in obese PCOS women compared with obese controls [0.5 (0.2-1.1) versus 0.8 (0.3-1.4) (mg kg(-1) min(-1) pmol l(-1)) × 100, P < 0.01], whereas the small difference between lean PCOS and lean control women was non-significant [1.5 (0.5-2.6) versus 1.7 (1.0-3.7) (mg kg(-1) min(-1) pmol l(-1)) × 100, P = 0.17]. Hyperinsulinemia increased capillary recruitment in lean controls (53.5 ± 20.3 versus 64.9 ± 27.4 n/mm(2), P < 0.05), but not in either PCOS group nor in obese controls. IICR and androgens were a determinant of M/I value only in lean women with or without PCOS. PCOS per se is associated with impaired IICR. Obese women with PCOS, in part independent of obesity, demonstrated a profound insulin resistance, whereas the difference between lean PCOS women and healthy controls was small and statistically non-significant. IICR was a determinant of IMGU in lean, but not in obese, women regardless of the presence of PCOS.

Experimental verification of nanoparticle jet minimum quantity lubrication effectiveness in grinding

NASA Astrophysics Data System (ADS)

Jia, Dongzhou; Li, Changhe; Zhang, Dongkun; Zhang, Yanbin; Zhang, Xiaowei

2014-12-01

coefficient, and specific grinding energy were 1.285 N/mm, 0.382, and 57.825 J/mm3, respectively. When nanoparticle mass fraction was smaller than 6 %, lubrication effects of nanoparticle jet MQL increased with the rising nanoparticle mass fraction. When nanoparticle mass fraction was larger than 6 %, lubrication effects of nanoparticle jet MQL decreased with the rising nanoparticle mass fraction.

Microstructures and Mechanical Study of Mg Alloy Foam Based on Mg-Zn-Ca-CaCO3 System

NASA Astrophysics Data System (ADS)

Erryani, A.; Pramuji, F.; Annur, D.; Amal, M. I.; Kartika, I.

2017-05-01

Magnesium alloy, a material that has potential to use some applications such as aerospace components, computer parts, and mobile phones. Magnesium alloy can also be a popular candidate as an orthopedic implant material for biodegradability, non-toxicity, and mechanical and physical properties that are excellent. Magnesium, one of the main macro elements required for the proper functioning of the human organism, is used to test the materials for biodegradable implants. The main objective of this study was to find out the microstructure, and mechanical characteristics of the Mg-Ca-Zn-CaCO3 alloy as porous implant materials are biodegradable. The presence of CaCO3 on the alloy functions as a foaming agent expected to produce gas bubbles during manufacturing process taken place that will form pores in the alloy. Mg-Ca-Zn-CaCO3 alloy was made by powder metallurgy method with three variations of composition (96Mg-Ca-3Zn-CaCO3, 91Mg-Ca-3Zn-5CaCO3, and 86Mg-Ca-3Zn-10CaCO3 wt%). Milling process was by using a shaker mill for 2 hours to produce a powder size distribution which was more homogeneous. The mixed powder was uniaxially pressed at a pressure of 100 MPa for 2 minutes and 200 MPa for 3 minutes into green compacts with dimensions of 10 mm in diameter and 10 mm in length. The sintering process was carried out at 650°C with a variation of holding time of 10 and 15 hours, and then the specimens were cooled down at room temperature. Microstructural analysis was performed by using X-Ray diffraction technique and Scanning electron microscopy equipped with an energy disperse spectrometry (EDS). The mechanical characteristics were analyzed by using Universal Testing Machine. The density and porosity of specimen were further measured by using Archimedes method. The results show that the optimum microstructure and mechanical characteristics are the holding time of 10 hours. The value of compression was 208.398 N/mm2, the density was 1.63 g/cc and a porosity was 18% on the

Quaternary rare-earth arsenides REAg{sub 1−x}Zn{sub y}As{sub 2} (RE=La–Nd, Sm, Gd–Dy) with tetragonal SrZnBi{sub 2}- and HfCuSi{sub 2}-type structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramachandran, Krishna K.; Genet, Clément; Mar, Arthur, E-mail: arthur.mar@ualberta.ca

2015-11-15

Reactions of the elements at 800 °C with the nominal compositions REAg{sub 1−x}Zn{sub x}As{sub 2} resulted in quaternary arsenides REAg{sub 1−x}Zn{sub y}As{sub 2} in which the combined Ag and Zn content deviates increasingly from unity in the Zn-richer phases, reflecting the transition from the fully stoichiometric ternary silver-containing arsenides REAgAs{sub 2} to the substoichiometric zinc-containing ones REZn{sub 0.67}As{sub 2}. Powder X-ray diffraction analysis indicated SrZnBi{sub 2}-type (space group I4/mmm, Z=4; RE=La, Ce) and HfCuSi{sub 2}-type structures (space group P4/nmm, Z=2; RE=Pr, Nd, Sm, Gd, Tb, Dy). Single-crystal X-ray diffraction analysis performed on LaAg{sub 0.5}Zn{sub 0.5}As{sub 2}, PrAg{sub 0.5}Zn{sub 0.5}As{sub 2},more » and NdAg{sub 0.5}Zn{sub 0.5}As{sub 2} indicated that the Ag and Zn atoms are disordered within metal-centred tetrahedra and provided no evidence for distortion of the square As nets. The small electron excess tolerated in these quaternary arsenides and the absence of distortion in the square nets can be traced to the occurrence of As–As states that are only weakly antibonding near the Fermi level. PrAg{sub 0.5}Zn{sub 0.5}As{sub 2} and NdAg{sub 0.5}Zn{sub 0.5}As{sub 2} are paramagnetic with effective magnetic moments consistent with trivalent RE species. - Graphical abstract: On proceeding from fully stoichiometric REAgAs{sub 2} to substoichiometric REZn{sub 0.67}As{sub 2}, deficiencies in Zn content become increasingly prominent in quaternary arsenides REAg{sub 1−x}Zn{sub y}As{sub 2}. - Highlights: • Ag and Zn atoms are disordered within quaternary arsenides REAg{sub 1−x}Zn{sub y}As{sub 2}. • In Zn-richer phases, Zn deficiencies develop to counteract electron excess. • Distortions of square As net appear to be suppressed.« less

Localizing Fracture Hydromechanical Response using Fiber Optic Distributed Acoustic Sensing in a Fractured Bedock Aquifer

NASA Astrophysics Data System (ADS)

Chevrot, S.; Wang, Y.; Monteiller, V.; Komatitsch, D.; Martin, R.

2016-12-01

Measuring fracture mechanical behavior in response to changes in fluid pressure is critical for understanding flow through petroleum reservoirs, predicting hydrothermal responses in geothermal fields, and monitoring geologic carbon sequestration injection. Distributed acoustic sensing (DAS) is new, but commercially available fiber optic technology that offers a novel approach to characterize fractured bedrock systems. DAS was originally designed to measure the amplitude, frequency, and phase of an acoustic wave, and is therefore capable of detecting strains at exceedingly small scales. Though normally used to measure frequencies in the Hz to kHz range, we adapted DAS to measure fracture displacements in response to periodic hydraulic pulses in the mHz frequency range. A field experiment was conducted in a fractured bedrock aquifer to test the ability of DAS to measure fracture mechanical response to oscillatory well tests. Fiber optic cable was deployed in a well, and coupled to the borehole wall using a flexible impermeable liner designed with an air coupled transducer to measure fluid pressure at the target fracture zone. Two types of cable were tested, a loose tube and tight buffered, to determine the effects of cable construction. Both strain and pressure were measured across the known fracture zone hydraulically connected to a well 30 m away. The companion well was subjected to alternating pumping and injection with periods between 2 and 18 minutes. Raw DAS data were collected as strain rate measured every 0.25 m along the fiber with a gauge length of 10 m, at a sampling rate of 1 kHz. Strain rate was converted to strain by integrating with respect to time. DAS measured periodic strains of less than 1 nm/m in response to periodic injection and pumping at the companion well. Strain was observed by DAS only at the depth of the hydraulically connected fracture zone. Thus, the magnitude and response of the strain could be both localized with depth and measured

Changes in Leaf Anatomical Traits Enhanced Photosynthetic Activity of Soybean Grown in Hydroponics with Plant Growth-Promoting Microorganisms.

PubMed

Paradiso, Roberta; Arena, Carmen; De Micco, Veronica; Giordano, Maria; Aronne, Giovanna; De Pascale, Stefania

2017-01-01

The use of hydroponic systems for cultivation in controlled climatic conditions and the selection of suitable genotypes for the specific environment help improving crop growth and yield. We hypothesized that plant performance in hydroponics could be further maximized by exploiting the action of plant growth-promoting organisms (PGPMs). However, the effects of PGPMs on plant physiology have been scarcely investigated in hydroponics. Within a series of experiments aimed to identify the best protocol for hydroponic cultivation of soybean [ Glycine max (L.) Merr.], we evaluated the effects of a PGPMs mix, containing bacteria, yeasts, mycorrhiza and trichoderma beneficial species on leaf anatomy, photosynthetic activity and plant growth of soybean cv. 'Pr91m10' in closed nutrient film technique (NFT). Plants were grown in a growth chamber under semi-aseptic conditions and inoculated at seed, seedling and plant stages, and compared to non-inoculated (control) plants. Light and epi-fluorescence microscopy analyses showed that leaves of inoculated plants had higher density of smaller stomata (297 vs. 247 n/mm 2 ), thicker palisade parenchyma (95.0 vs. 85.8 μm), and larger intercellular spaces in the mesophyll (57.5% vs. 52.2%), compared to non-inoculated plants. The modifications in leaf functional anatomical traits affected gas exchanges; in fact starting from the reproductive phase, the rate of leaf net photosynthesis (NP) was higher in inoculated compared to control plants (8.69 vs. 6.13 μmol CO 2 m -2 s -1 at the beginning of flowering). These data are consistent with the better maximal PSII photochemical efficiency observed in inoculated plants (0.807 vs. 0.784 in control); conversely no difference in leaf chlorophyll content was found. The PGPM-induced changes in leaf structure and photosynthesis lead to an improvement of plant growth (+29.9% in plant leaf area) and seed yield (+36.9%) compared to control. Our results confirm that PGPMs may confer benefits in

Appendicular and whole body lean mass outcomes are associated with finite element analysis-derived bone strength at the distal radius and tibia in adults aged 40years and older.

PubMed

Gibbs, Jenna C; Giangregorio, Lora M; Wong, Andy K O; Josse, Robert G; Cheung, Angela M

2017-10-01

The purpose of this cross-sectional study was to determine how appendicular lean mass index (ALMI), and whole body lean (LMI) and fat mass indices (FMI) associate with estimated bone strength outcomes at the distal radius and tibia in adults aged 40 years and older. Dual energy X-ray absorptiometry (DXA) scans were performed to determine body composition, including whole body lean and fat mass, and appendicular lean mass. ALMI (appendicular lean mass/height 2 ), LMI (lean tissue mass/height 2 ) and FMI (fat mass/height 2 ) were calculated. High-resolution peripheral quantitative computed tomography (HRpQCT) scans were performed to assess bone structural properties at the distal radius and tibia. Using finite element analysis, failure load (N), stiffness (N/mm), ultimate stress (MPa), and cortical-to-trabecular load ratio were estimated from HRpQCT scans. The associations between body composition (ALMI, LMI, FMI) and estimated bone strength were examined using bivariate and multivariable linear regression analyses adjusting for age, sex, and other confounding variables. In 197 participants (127 women; mean±SD, age: 69.5±10.3y, body mass index: 27.95±4.95kg/m 2 , ALMI: 7.31±1.31kg/m 2 ), ALMI and LMI were significantly associated with failure load at the distal radius and tibia (explained 39%-48% of the variance) and remained significant after adjusting for confounding variables and multiple testing (R 2 =0.586-0.645, p<0.001). ALMI, LMI, and FMI did not have significant associations with ultimate stress in our multivariable models. FMI was significantly associated with cortical-to-trabecular load ratio at the distal radius and tibia (explained 6%-12% of the variance) and remained significant after adjusting for confounders and multiple testing (R 2 =0.208-0.243, p<0.001). FMI was no longer significantly associated with failure load after adjusting for confounders. These findings suggest that ALMI and LMI are important determinants of estimated bone strength

Tensile failure properties of the perinatal, neonatal, and pediatric cadaveric cervical spine.

PubMed

Luck, Jason F; Nightingale, Roger W; Song, Yin; Kait, Jason R; Loyd, Andre M; Myers, Barry S; Bass, Cameron R Dale

2013-01-01

Biomechanical tensile testing of perinatal, neonatal, and pediatric cadaveric cervical spines to failure. To assess the tensile failure properties of the cervical spine from birth to adulthood. Pediatric cervical spine biomechanical studies have been few due to the limited availability of pediatric cadavers. Therefore, scaled data based on human adult and juvenile animal studies have been used to augment the limited pediatric cadaver data. Despite these efforts, substantial uncertainty remains in our understanding of pediatric cervical spine biomechanics. A total of 24 cadaveric osteoligamentous head-neck complexes, 20 weeks gestation to 18 years, were sectioned into segments (occiput-C2 [O-C2], C4-C5, and C6-C7) and tested in tension to determine axial stiffness, displacement at failure, and load-to-failure. Tensile stiffness-to-failure (N/mm) increased by age (O-C2: 23-fold, neonate: 22 ± 7, 18 yr: 504; C4-C5: 7-fold, neonate: 71 ± 14, 18 yr: 509; C6-C7: 7-fold, neonate: 64 ± 17, 18 yr: 456). Load-to-failure (N) increased by age (O-C2: 13-fold, neonate: 228 ± 40, 18 yr: 2888; C4-C5: 9-fold, neonate: 207 ± 63, 18 yr: 1831; C6-C7: 10-fold, neonate: 174 ± 41, 18 yr: 1720). Normalized displacement at failure (mm/mm) decreased by age (O-C2: 6-fold, neonate: 0.34 ± 0.076, 18 yr: 0.059; C4-C5: 3-fold, neonate: 0.092 ± 0.015, 18 yr: 0.035; C6-C7: 2-fold, neonate: 0.088 ± 0.019, 18 yr: 0.037). Cervical spine tensile stiffness-to-failure and load-to-failure increased nonlinearly, whereas normalized displacement at failure decreased nonlinearly, from birth to adulthood. Pronounced ligamentous laxity observed at younger ages in the O-C2 segment quantitatively supports the prevalence of spinal cord injury without radiographic abnormality in the pediatric population. This study provides important and previously unavailable data for validating pediatric cervical spine models, for evaluating current scaling techniques and animal surrogate models, and for the development

Evaluation of Portable Multi-Gas Analyzers for use by Safety Personnel

NASA Technical Reports Server (NTRS)

Lueck, D. E.; Meneghelli, B. J.; Bardel, D. N.

1998-01-01

During confined space entry operations as well as Shuttle-safing operations, United Space Alliance (USA)/National Aeronautics and Space Administration (NASA) safety personnel use a variety of portable instrumentation to monitor for hazardous levels of compounds such as nitrogen dioxide (N%), monomethylhydrazine (NMM), FREON 21, ammonia (NH3), oxygen (O2), and combustibles (as hydrogen (H2)). Except for O2 and H2, each compound is monitored using a single analyzer. In many cases these analyzers are 5 to 10 years old and require frequent maintenance. In addition, they are cumbersome to carry and tend to make the job of personnel monitoring physically taxing. As part of an effort to upgrade the sensor technology background information was requested from a total of 27 manufacturers of portable multi-gas instruments. A set of criteria was established to determine which vendors would be selected for laboratory evaluation. These criteria were based on requests made by USA/NASA Safety personnel in order to meet requirements within their respective areas for confined-space and Shuttle-safing operations. Each of the 27 manufacturers of multi-gas analyzers was sent a copy of the criteria and asked to fill in the appropriate information pertaining to their instrumentation. Based on the results of the sensor criteria worksheets, a total of 9 vendors out of 27 surveyed manufacturers were chosen for evaluation. Each vendor included in the final evaluation process was requested to configure each of two analyzers with NO2, NH3, O2, and combustible sensors. A set of lab tests was designed in order to determine which of the multi-gas instruments under evaluation was best suited for use in both shuttle and confined space operations. These tests included linearity/repeatability, zero/span drift response/recovery, humidity, interference, and maintenance. At the conclusion of lab testing three vendors were selected for additional field testing. Based on the results of both the lab and

50 Myr. in a serpentinite subduction channel: Insights into slow eclogite exhumation

NASA Astrophysics Data System (ADS)

Flores, K. E.; Bonnet, G.; Cai, Y.; Martin, C.; Hemming, S. R.; Brueckner, H. K.; Harlow, G. E.

2017-12-01

Modern petrochronology shows that the exhumation of metamorphosed oceanic rocks in subduction zones is commonly a brief process (<10-20 Ma) characterized by rates of 2-5 km/Ma. This rapid exhumation is essential to avoid complete retrogression of high grade assemblages during ascension. However, our multi-approach P-T-t results on retrograde eclogites from the Northern Motagua Mélange (NMM) in Guatemala challenges those previous findings because they record remarkably slower exhumation rates ( 1 km/Ma). The retrograde eclogites occur as cm to tens of m sized blocks within a serpentinite matrix mélange that also contains blocks of subgreenschist to amphibolite and blueschist facies metabasites, jadeitites, omphacitites, albitites, mica-rocks, metatrondhjemites, and minor low grade metasediments. The studied samples range from almost unaltered eclogites to retrograde blueschist and ep-amphibolite facies metabasites containing eclogite relicts. The successive assemblages define classical clockwise P-T paths: comprised of (a) prograde blueschist/eclogite facies metamorphism within garnet cores, (b) eclogite facies peak recrystallization at 2.1 GPa and 500°C, (c) post-peak blueschist facies recrystallization, (d) amphibolite facies overprinting, and (e) late stage greenschist facies retrogression. This complex polymetamorphic history defines an exhumation path with a metamorphic peak at 136-125 Ma (Sm-Nd mineral isochrons) at 70 km depth, an ascent to the middle section of a subduction channel ( 40 km) at 99-92 Ma (Ar-Ar in Ph), and exhumation to 25-20 km at 80-75 Ma (Ar-Ar in Mhb). Synchronous jadeitite and mica-rocks yielded crystallization and exhumation ages of 95 Ma (U-Pb in Zrn) and 77-53 Ma (Ar-Ar in Ph), respectively. In contrast, an associated eclogite-bearing sheet of continental crust shows a younger eclogite metamorphic peak of 77-75 Ma at 80 km depth, but similar exhumation ages of 76-66 Ma and near surface regional exposure at 30 Ma (AFT). These new

Changes in Leaf Anatomical Traits Enhanced Photosynthetic Activity of Soybean Grown in Hydroponics with Plant Growth-Promoting Microorganisms

PubMed Central

Paradiso, Roberta; Arena, Carmen; De Micco, Veronica; Giordano, Maria; Aronne, Giovanna; De Pascale, Stefania

2017-01-01

The use of hydroponic systems for cultivation in controlled climatic conditions and the selection of suitable genotypes for the specific environment help improving crop growth and yield. We hypothesized that plant performance in hydroponics could be further maximized by exploiting the action of plant growth-promoting organisms (PGPMs). However, the effects of PGPMs on plant physiology have been scarcely investigated in hydroponics. Within a series of experiments aimed to identify the best protocol for hydroponic cultivation of soybean [Glycine max (L.) Merr.], we evaluated the effects of a PGPMs mix, containing bacteria, yeasts, mycorrhiza and trichoderma beneficial species on leaf anatomy, photosynthetic activity and plant growth of soybean cv. ‘Pr91m10’ in closed nutrient film technique (NFT). Plants were grown in a growth chamber under semi-aseptic conditions and inoculated at seed, seedling and plant stages, and compared to non-inoculated (control) plants. Light and epi-fluorescence microscopy analyses showed that leaves of inoculated plants had higher density of smaller stomata (297 vs. 247 n/mm2), thicker palisade parenchyma (95.0 vs. 85.8 μm), and larger intercellular spaces in the mesophyll (57.5% vs. 52.2%), compared to non-inoculated plants. The modifications in leaf functional anatomical traits affected gas exchanges; in fact starting from the reproductive phase, the rate of leaf net photosynthesis (NP) was higher in inoculated compared to control plants (8.69 vs. 6.13 μmol CO2 m-2 s-1 at the beginning of flowering). These data are consistent with the better maximal PSII photochemical efficiency observed in inoculated plants (0.807 vs. 0.784 in control); conversely no difference in leaf chlorophyll content was found. The PGPM-induced changes in leaf structure and photosynthesis lead to an improvement of plant growth (+29.9% in plant leaf area) and seed yield (+36.9%) compared to control. Our results confirm that PGPMs may confer benefits in

Multiscale biomechanical responses of adapted bone-periodontal ligament-tooth fibrous joints

PubMed Central

Jang, Andrew T.; Merkle, Arno; Fahey, Kevin; Gansky, Stuart A.; Ho, Sunita P.

2015-01-01

Reduced functional loads cause adaptations in organs. In this study, temporal adaptations of bone-ligament-tooth fibrous joints to reduced functional loads were mapped using a holistic approach. Systematic studies were performed to evaluate organ-level and tissue-level adaptations in specimens harvested periodically from rats given powder food for 6 months (N = 60 over 8,12,16,20, and 24 weeks). Bone-periodontal ligament (PDL)-tooth fibrous joint adaptation was evaluated by comparing changes in joint stiffness with changes in functional space between the tooth and alveolar bony socket. Adaptations in tissues included mapping changes in the PDL and bone architecture as observed from collagen birefringence, bone hardness and volume fraction in rats fed soft foods (soft diet, SD) compared to those fed hard pellets as a routine diet (hard diet, HD). In situ biomechanical testing on harvested fibrous joints revealed increased stiffness in SD groups (SD:239-605 N/mm) (p<0.05) at 8 and 12 weeks. Increased joint stiffness in early development phase was due to decreased functional space (at 8wks change in functional space was −33 µm, at 12wks change in functional space was −30 µm) and shifts in tissue quality as highlighted by birefringence, architecture and hardness. These physical changes were not observed in joints that were well into function, that is, in rodents older than 12 weeks of age. Significant adaptations in older groups were highlighted by shifts in bone growth (bone volume fraction 24wks: Δ-0.06) and bone hardness (8wks: Δ−0.04 GPa, 16 wks: Δ−0.07 GPa, 24wks: Δ−0.06 GPa). The response rate (N/s) of joints to mechanical loads decreased in SD groups. Results from the study showed that joint adaptation depended on age. The initial form-related adaptation (observed change in functional space) can challenge strain-adaptive nature of tissues to meet functional demands with increasing age into adulthood. The coupled effect between functional space in

Mineral density and biomechanical properties of bone tissue from male Arctic foxes (Vulpes lagopus) exposed to organochlorine contaminants and emaciation.

PubMed

Sonne, Christian; Wolkers, Hans; Rigét, Frank F; Jensen, Jens-Erik Beck; Teilmann, Jenni; Jenssen, Bjørn Munro; Fuglei, Eva; Ahlstrøm, Øystein; Dietz, Rune; Muir, Derek C G; Jørgensen, Even H

2009-01-01

We investigated the impact from dietary OC (organochlorine) exposure and restricted feeding (emaciation) on bone mineral density (BMD; g hydroxy-apatite cm(-2)) in femoral, vertebrate, skull and baculum osteoid tissue from farmed Arctic blue foxes (Vulpes lagopus). For femur, also biomechanical properties during bending (displacement [mm], load [N], energy absorption [J] and stiffness [N/mm]) were measured. Sixteen foxes (EXP) were fed a wet food containing 7.7% OC-polluted minke whale (Balaenoptera acutorostrata) blubber in two periods of body fat deposition (Aug-Dec) and two periods of body fat mobilisation (Jan-July) in which the food contained less energy and only 2% blubber. SigmaOC food concentration in the food containing 7.7% whale blubber was 309 ng/g wet mass. This corresponded to a SigmaOC exposure of ca. 17 microg/kg body mass/d and a responding SigmaOC residue in subcutaneous adipose tissue of ca. 1700 ng/g live mass in the 8 EXP fat foxes euthanized after 16 months. A control group (CON) composed of 15 foxes were fed equal daily caloric amounts of clean pork (Sus scrofa) fat. After 16 months, 8 EXP and 7 CON foxes were euthanized (mean body mass=9.25 kg) while the remaining 8 EXP and 8 CON foxes were given restricted food rations for 6 months resulting in a body weight reduction (mean body mass=5.46 kg). The results showed that only BMD(skull) vs. BMD(vertebrae) were significantly correlated (R=0.68; p=0.03; n=10) probably due to a similar composition of trabecular and cortical osteoid tissue. No difference in any of the BMD measurements or femoral biomechanical properties was found between EXP and CON foxes although BMD baculum was 1.6-folds lower in the EXP group. However, lean summer foxes had significantly lower femoral biomechanical properties measured as displacement (mm), energy absorption (J) and time (s) biomechanical properties than fat winter foxes (all p<0.004). This indicates lower stiffness and softer bones from fasting which is in

Localizing Fracture Hydromechanical Response using Fiber Optic Distributed Acoustic Sensing in a Fractured Bedock Aquifer

NASA Astrophysics Data System (ADS)

Ciervo, C.; Becker, M.; Cole, M. C.; Coleman, T.; Mondanos, M.

2017-12-01

Measuring fracture mechanical behavior in response to changes in fluid pressure is critical for understanding flow through petroleum reservoirs, predicting hydrothermal responses in geothermal fields, and monitoring geologic carbon sequestration injection. Distributed acoustic sensing (DAS) is new, but commercially available fiber optic technology that offers a novel approach to characterize fractured bedrock systems. DAS was originally designed to measure the amplitude, frequency, and phase of an acoustic wave, and is therefore capable of detecting strains at exceedingly small scales. Though normally used to measure frequencies in the Hz to kHz range, we adapted DAS to measure fracture displacements in response to periodic hydraulic pulses in the mHz frequency range. A field experiment was conducted in a fractured bedrock aquifer to test the ability of DAS to measure fracture mechanical response to oscillatory well tests. Fiber optic cable was deployed in a well, and coupled to the borehole wall using a flexible impermeable liner designed with an air coupled transducer to measure fluid pressure at the target fracture zone. Two types of cable were tested, a loose tube and tight buffered, to determine the effects of cable construction. Both strain and pressure were measured across the known fracture zone hydraulically connected to a well 30 m away. The companion well was subjected to alternating pumping and injection with periods between 2 and 18 minutes. Raw DAS data were collected as strain rate measured every 0.25 m along the fiber with a gauge length of 10 m, at a sampling rate of 1 kHz. Strain rate was converted to strain by integrating with respect to time. DAS measured periodic strains of less than 1 nm/m in response to periodic injection and pumping at the companion well. Strain was observed by DAS only at the depth of the hydraulically connected fracture zone. Thus, the magnitude and response of the strain could be both localized with depth and measured

A novel microscopic method for analyzing Gram-stained vaginal smears in the diagnosis of disorders of vaginal microflora.

PubMed

Nenadić, Dane B; Pavlović, Miloš D; Motrenko, Tatjana

2015-08-01

The Nugent's score is still the gold standard in the great majority of studies dealing with the assessment of vaginal flora and the diagnosis of bacterial vaginosis (BV). The aim of this study was to show that the analysis of Gram-stained vaginal samples under microscope at the magnification of x200 (a novel microscopic method--NMM), as a fast and simple tool, easily applicable in everyday practice, better reflects complexity of vaginal microflora than the Nugent's methodology (x1000). Gram-stained vaginal smears from 394 asymptomatic pregnant women (24-28 week of pregnancy) were classified according to the Nugent's microscopic criteria (immersion, magnification x1000). The smears were then reexamined under immersion but at magnification x200. All samples were classified into 6 groups according to semiquanititative assessment of numbers (cellularity) and the ratio of rod (length < 1.5 microm) and small bacterial (< 1.5 microm) forms: hypercellular (normal full--NF), moderately cellular (normal mid-NM), hypocellular (normal empty--NE), bacterial vaginosis full (BVF), bacterial vaginosis mid (BVM), and bacterial vaginosis empty (BVE). Also yeasts, coccae, bifido and lepto bacterial forms as well polymorphonuclear (PMN) leukocytes were identified. According to the Nugent's scoring, BV was found in 78, intermediate findings in 63, and yeasts in 48 patients. By our criteria BV was confirmed in 88 patients (37 BVF, 24 BVM, and 27 BVN). Generally, both tools proved to be highly concordant for the diagnosis of BV (Lin's concordance correlation coefficient = 0.9852). In 40% of the women mixed flora was found: yeasts in 126 (32%), coccae in 145 (37%), bifido forms in 32 (8%) and lepto forms in 20 (5%). Almost a half of BV patients had also yeasts (39/88). Elevated PMN numbers were found in 102 (33%) patients with normal and in 36 (41%) women with BV. The newly described methodology is simpler to apply and much better reflects diversity of vaginal microflora. In this way it

Do estrogen and alendronate improve metaphyseal fracture healing when applied as osteoporosis prophylaxis?

PubMed

Kolios, Leila; Hoerster, Ann Kristin; Sehmisch, Stephan; Malcherek, Marie Christin; Rack, Thomas; Tezval, Mohammed; Seidlova-Wuttke, Dana; Wuttke, Wolfgang; Stuermer, Klaus Michael; Stuermer, Ewa Klara

2010-01-01

Osteoporosis is accompanied by predominantly metaphyseal fractures with a delayed and qualitatively reduced healing process. This study addressed the question of whether fracture healing in the context of osteoporosis prophylaxis is improved with estrogen (E) or alendronate (ALN). Thirty-six ovariectomized and 12 sham-operated 12-week-old rats received soy-free (osteoporotic C, sham), E-, or ALN- supplemented diets. After 10 weeks, a metaphyseal tibia osteotomy and standardized T-plate fixation were performed. After a 5-week healing process, the fracture callus was evaluated qualitatively by biomechanical bending test and quantitatively in microradiographic sections. The time course of callus formation was examined using fluorochrome-labeled histological sections. Administration of E improved the biomechanical properties of callus (stiffness [N/mm]: sham: 110.2 + or - 76.07, C: 41.28 + or - 33.70, E: 85.72 + or - 47.24, ALN: 72.07 + or - 34.68). The resistance to microfracturing seen in E-treated animals was significantly enhanced and even superior to sham (yield load [N] sham: 27.44 + or - 9.72, C: 21.04 + or - 12.47, E: 42.85 + or - 13.74(Delta), ALN: 25.28 + or - 6.4(.)) (* P < 0.05 vs. sham group, (Delta) P < 0.05 vs. C group, (*) P < 0.05 vs. E group). Trabecular bone in particular was improved, indicating the presence of physiological endosteal bridging (Tr.Dn [%] sham: 10.53 + or - 18.9, C: 1.01 + or - 0.14, E: 24.13 + or - 34.09(Delta), ALN: 3.99 + or - 8.3(.)). ALN did not help bone healing, as shown by mechanical tests. Compared to the C group, statistically, ALN did not show worse properties. The induction of callus formation under ALN treatment was slightly delayed (Tt.Cl [mm(2)] sham: 3.68 + or - 0.66, C: 3.44 + or - 0.42, E: 3.69 + or - 0.58, ALN: 3.06 + or - 0.56). Osteoporotic metaphyseal fracture healing was qualitatively and quantitatively improved by E prophylaxis. The process of fracture healing occurred nearly physiologically (shamlike

Anatomical and biomechanical investigations of the iliotibial tract.

PubMed

Birnbaum, K; Siebert, C H; Pandorf, T; Schopphoff, E; Prescher, A; Niethard, F U

2004-12-01

), and valgus (155 degrees) femoral neck angles. The influencing forces of the IT at the height of the greater trochanter and the forces at the femoral head or the acetabulum could be measured. Our anatomical investigations revealed a splitting of the IT into a superficial and a deep portion, which covers the tensor fasciae latae. The tensor fasciae latae has an insertion on the IT. The IT continues down the femur, passing over the greater trochanter without developing an actual fixation to the bone. Part of the insertion of the gluteus maximus radiates into the IT. The IT passes over the vastus lateralis and inserts at the infracondylar tubercle of the tibia or Gerdy's tubercle, at the head of the fibula, as well as at the lateral intermuscular septum. Portions also insert on the transverse and longitudinal retinaculum of the patella. Concerning the material properties of the IT, we found a structural stiffness of 17 N/mm extension on average (D = 17 N/mm). The subligamentous measurements at the height of the greater trochanter in the unfixed corpse and intraoperatively during hip joint replacement showed an increase of the forces during adduction and a decrease during abduction of the hip joint. We found thereby a maximum increase up to 106 N with 40 degrees adduction. Concerning the femoral neck angle, we can state that valgus leads to lower subligamentous forces and varus to higher subligamentous forces. The forces directed at the acetabulum, which were measured by the prosthesis with a sensor along the femoral neck, showed a decrease with varus angles and an increase with valgus angles. The highest force of 624 N was measured with 40 degrees adduction and an angle of 155 degrees. The finite element model of the proximal femur showed a sole hip joint-centralizing force of the IT of 655 N with a femoral neck angle of 128 degrees after subtraction of the gluteal muscle force and the body weight. At 115 degrees, we found an increase up to 997 N and a decrease to 438 N

Peak bone strength is influenced by calcium intake in growing rats.

PubMed

Viguet-Carrin, S; Hoppler, M; Membrez Scalfo, F; Vuichoud, J; Vigo, M; Offord, E A; Ammann, P

2014-11-01

In this study we investigated the effect of supplementing the diet of the growing male rat with different levels of calcium (from low to higher than recommended intakes at constant Ca/P ratio), on multiple factors (bone mass, strength, size, geometry, material properties, turnover) influencing bone strength during the bone accrual period. Rats, age 28days were supplemented for 4weeks with high Ca (1.2%), adequate Ca (0.5%) or low Ca level (0.2%). Bone metabolism and structural parameters were measured. No changes in body weight or food intake were observed among the groups. As anticipated, compared to the adequate Ca intake, low-Ca intake had a detrimental impact on bone growth (33.63 vs. 33.68mm), bone strength (-19.7% for failure load), bone architecture (-58% for BV/TV) and peak bone mass accrual (-29% for BMD) due to the hormonal disruption implied in Ca metabolism. In contrast, novel, surprising results were observed in that higher than adequate Ca intake resulted in improved peak bone strength (106 vs. 184N/mm for the stiffness and 61 vs. 89N for the failure load) and bone material properties (467 vs. 514mPa for tissue hardness) but these effects were not accompanied by changes in bone mass, size, microarchitecture or bone turnover. Hormonal factors, IGF-I and bone modeling were also evaluated. Compared to the adequate level of Ca, IGF-I level was significantly lower in the low-Ca intake group and significantly higher in the high-Ca intake group. No detrimental effects of high Ca were observed on bone modeling (assessed by histomorphometry and bone markers), at least in this short-term intervention. In conclusion, the decrease in failure load in the low calcium group can be explained by the change in bone geometry and bone mass parameters. Thus, improvements in mechanical properties can be explained by the improved quality of intrinsic bone tissue as shown by nanoindentation. These results suggest that supplemental Ca may be beneficial for the attainment of

The POLIMI forecasting chain for real time flood and drought predictions

NASA Astrophysics Data System (ADS)

Ceppi, Alessandro; Ravazzani, Giovanni; Corbari, Chiara; Mancini, Marco

2016-04-01

Nowadays coupling meteorological and hydrological models is recognized by scientific community as a necessary way to forecast extreme hydrological phenomena, in order to activate useful mitigation measurements and alert systems in advance. The development and implementation of a real-time forecasting chain with a hydro-meteorological operational alert procedure for flood and drought events is presented in this study. Different weather models are used to build the POLIMI operative chain: the probabilistic COSMO-LEPS model with 16 ensembles developed by ARPA-Emilia Romagna, the deterministic Bolam and Moloch models, developed by the Italian ISAC-CNR, and nine further simulations obtained by different runs of the WRF-ARW (3), WRF-NMM (2), ETA2012 (1) and the GFS (3), provided by the private Epson Meteo Center and Terraria companies. All the meteorological runs are then implemented with the rainfall-runoff physically-based distributed FEST-WB model, developed at Politecnico di Milano to obtain a multi-model approach system with hydrological ensemble forecasts in different areas of study over the Italian country. As far as concerning drought predictions, three test-beds are monitored: two in maize fields, one in the Puglia region (South of Italy), and another in the Po Valley area, (northern Italy), and one in a golf course in Milan city. The hydrological model was here calibrated and validated against measurements of latent heat flux and soil moisture acquired by an eddy-covariance station, TDR probes and remote sensing images. Regarding flood forecasts, two test-sites are chosen: the first one is the urban area northern Milan where three catchments (the Seveso, Olona, and Lambro River basins) are used to show how early warning systems are an effective complement to structural measures for flood control in Milan city which flooded frequently in the last 25 years, while the second test-site is the Idro Lake, located between the Lombardy and Trentino region where the

Impact of burned areas on the northern African seasonal climate from the perspective of regional modeling

NASA Astrophysics Data System (ADS)

De Sales, Fernando; Xue, Yongkang; Okin, Gregory S.

2016-12-01

This study investigates the impact of burned areas on the surface energy balance and monthly precipitation in northern Africa as simulated by a state-of-the-art regional model. Mean burned area fraction derived from MODIS date of burning product was implemented in a set of 1-year long WRF-NMM/SSiB2 model simulations. Vegetation cover fraction and LAI were degraded daily based on mean burned area fraction and on the survival rate for each vegetation land cover type. Additionally, ground darkening associated with wildfire-induced ash and charcoal deposition was imposed through lower ground albedo for a period after burning. In general, wildfire-induced vegetation and ground condition deterioration increased mean surface albedo by exposing the brighter bare ground, which in turn caused a decrease in monthly surface net radiation. On average, the wildfire-season albedo increase was approximately 6.3 % over the Sahel. The associated decrease in surface available energy caused a drop in surface sensible heat flux to the atmosphere during the dry months of winter and early spring, which gradually transitioned to a more substantial decrease in surface evapotranspiration in April and May that lessened throughout the rainy season. Overall, post-fire land condition deterioration resulted in a decrease in precipitation over sub-Saharan Africa, associated with the weakening of the West African monsoon progression through the region. A decrease in atmospheric moisture flux convergence was observed in the burned area simulations, which played a dominant role in reducing precipitation in the area, especially in the months preceding the monsoon onset. The areas with the largest precipitation impact were those covered by savannas and rainforests, where annual precipitation decreased by 3.8 and 3.3 %, respectively. The resulting precipitation decrease and vegetation deterioration caused a drop in gross primary productivity in the region, which was strongest in late winter and early

Geologic Setting of the Hamme Tungsten District, North Carolina and Virginia

USGS Publications Warehouse

Parker, John Mason

1963-01-01

derived mainly from graywackes and volcanic flows, and subordinately from pyroclastic materials, whereas the rocks of the Virgilina district were interpreted by earlier workers as being mainly volcanic with much pyroclastic material but little sediment. Igneous, and perhaps pseudo igneous, rocks in the district include hornblende gabbro, albite granodiorite, aplite, and pegmatite--all of which are probably middle Paleozoic in age--and diabase and hypersthene tonalite of Late Triassic age. The gabbro forms three lenticular to subcircular bodies up to 2% miles in width in the western part of the area. Albite granodiorite forms a pluton with a maximum width of 7 miles which occupies the center of the area. At its northeastern end the pluton narrows abruptly to a point. Phyllite forms the wall rocks on all sides of the albite granodiorite. The contact is gradational and conformable in most places, but on the northwest side it cuts across wall structure for about 3 miles. Near its western edge the albite granodiorite includes a northeast-trending zone of schistose wall rock in and near which are localized the tungsten deposits. The origin of the albite granodiorite is uncertain, but it may have formed by the metasomatic replacement of the wallrocks, during which albite porphyroblasts developed first and were followed by microcline and quartz. Diabase and hypersthene tonalite occur as dikes and sills along four northward-trending belts. The dikes are a few feet to more than 300 feet thick, and several extend along strike for more than 10 miles. The Hamme district Is in the eastern part of the Carolina slate belt, and the Virg1l1na district lies along the western side of the belt. Rocks in the Hamme district dip mostly westward and in the Vifg1lina district dip mainly eastward into a syncline. This syncline, here named the Spewmarrow syncline, may be a structure of regional significance. Tungsten in the Hamme district occurs mainly

Using Virtualization to Integrate Weather, Climate, and Coastal Science Education

NASA Astrophysics Data System (ADS)

Davis, J. R.; Paramygin, V. A.; Figueiredo, R.; Sheng, Y.

2012-12-01

To better understand and communicate the important roles of weather and climate on the coastal environment, a unique publically available tool is being developed to support research, education, and outreach activities. This tool uses virtualization technologies to facilitate an interactive, hands-on environment in which students, researchers, and general public can perform their own numerical modeling experiments. While prior efforts have focused solely on the study of the coastal and estuary environments, this effort incorporates the community supported weather and climate model (WRF-ARW) into the Coastal Science Educational Virtual Appliance (CSEVA), an education tool used to assist in the learning of coastal transport processes; storm surge and inundation; and evacuation modeling. The Weather Research and Forecasting (WRF) Model is a next-generation, community developed and supported, mesoscale numerical weather prediction system designed to be used internationally for research, operations, and teaching. It includes two dynamical solvers (ARW - Advanced Research WRF and NMM - Nonhydrostatic Mesoscale Model) as well as a data assimilation system. WRF-ARW is the ARW dynamics solver combined with other components of the WRF system which was developed primarily at NCAR, community support provided by the Mesoscale and Microscale Meteorology (MMM) division of National Center for Atmospheric Research (NCAR). Included with WRF is the WRF Pre-processing System (WPS) which is a set of programs to prepare input for real-data simulations. The CSEVA is based on the Grid Appliance (GA) framework and is built using virtual machine (VM) and virtual networking technologies. Virtualization supports integration of an operating system, libraries (e.g. Fortran, C, Perl, NetCDF, etc. necessary to build WRF), web server, numerical models/grids/inputs, pre-/post-processing tools (e.g. WPS / RIP4 or UPS), graphical user interfaces, "Cloud"-computing infrastructure and other tools into a

Comparison of Q3s ATD biomechanical responses to pediatric volunteers.

PubMed

Ita, Meagan; Kang, Yun-Seok; Seacrist, Thomas; Dahle, Eric; Bolte, John

2014-01-01

The biofidelity of pediatric anthropomorphic test devices (ATDs) continues to be evaluated with scaled-down adult data, a methodology that requires inaccurate assumptions about the likeness of biomechanical properties of children and adults. Recently, evaluation of pediatric ATDs by comparison of pediatric volunteer (PV) data has emerged as a valuable and practical alternative to the use of scaled adult data. This study utilized existing PV data to evaluate a 3-year-old side impact ATD, the Q3s. Though ATDs have been compared to volunteer responses in frontal impacts, this study is the first to extend ATD-PV comparison methods to the Q3s ATD and among the first to extend these methods to side impacts. Previously conducted experiments were replicated in order to make a direct comparison between the Q3s and PVs. PV data were used from 4- to 7-year-olds (shoulder tests, n=14) and 6- to 8-year-olds (sled tests, n=7). Force-deflection data were captured during quasistatic shoulder tests through manual displacement of the shoulder joint. Resulting shoulder stiffness was compared between the Q3s and PVs. Low-speed far-side sled tests were conducted with the Q3s at lateral (90°) and oblique (60°) impacts. Primary outcomes of interest included (1) lateral displacement of the torso, (2) torso rollout angle, and (3) kinematic trajectories of the head and neck. The Q3s exhibited shoulder stiffness values at least 32 N/mm greater than the PVs for all conditions (PV muscle tensed and relaxed, deflection calculated for full- and half-thoracic). In lateral sled tests, the Q3s demonstrated increased coronal torso rollout (Q3s: 49.2°; PVs: 35.7°±12.4°) and lateral (ΔY) movement of the top of the head (Q3s: -389 mm; PVs: -320±23 mm) compared to PVs. In oblique trials, the Q3s achieved significantly decreased lateral torso displacement (Q3s: 153.3 mm; PVs: 193.6±25.6 mm) and top of the head forward (ΔX) motion (Q3s: 68 mm; PVs: 133 ± 20 mm) compared to PVs. In all tests

Weather Research and Forecasting Model Sensitivity Comparisons for Warm Season Convective Initiation

NASA Technical Reports Server (NTRS)

Watson, Leela R.; Hoeth, Brian; Blottman, Peter F.

2007-01-01

configuration options are best to address this specific forecast concern, the Weather Research and Forecasting (WRF) model, which has two dynamical cores - the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM) was employed. In addition to the two dynamical cores, there are also two options for a "hot-start" initialization of the WRF model - the Local Analysis and Prediction System (LAPS; McGinley 1995) and the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS; Brewster 1996). Both LAPS and ADAS are 3- dimensional weather analysis systems that integrate multiple meteorological data sources into one consistent analysis over the user's domain of interest. This allows mesoscale models to benefit from the addition of highresolution data sources. Having a series of initialization options and WRF cores, as well as many options within each core, provides SMG and MLB with considerable flexibility as well as challenges. It is the goal of this study to assess the different configurations available and to determine which configuration will best predict warm season convective initiation.

Histologic and biomechanical evaluation of a novel macroporous polytetrafluoroethylene knit mesh compared to lightweight and heavyweight polypropylene mesh in a porcine model of ventral incisional hernia repair

PubMed Central

Melman, L.; Jenkins, E. D.; Hamilton, N. A.; Bender, L. C.; Brodt, M. D.; Deeken, C. R.; Greco, S. C.; Frisella, M. M.

2013-01-01

Purpose To evaluate the biocompatibility of heavyweight polypropylene (HWPP), lightweight polypropylene (LWPP), and monofilament knit polytetrafluoroethylene (mkPTFE) mesh by comparing biomechanics and histologic response at 1, 3, and 5 months in a porcine model of incisional hernia repair. Methods Bilateral full-thickness abdominal wall defects measuring 4 cm in length were created in 27 Yucatan minipigs. Twenty-one days after hernia creation, animals underwent bilateral preperitoneal ventral hernia repair with 8 × 10 cm pieces of mesh. Repairs were randomized to Bard®Mesh (HWPP, Bard/Davol, http://www.davol.com), ULTRAPRO® (LWPP, Ethicon, http://www.ethicon.com), and GORE®INFINIT Mesh (mkPTFE, Gore & Associates, http://www.gore.com). Nine animals were sacrificed at each timepoint (1, 3, and 5 months). At harvest, a 3 × 4 cm sample of mesh and incorporated tissue was taken from the center of the implant site and subjected to uniaxial tensile testing at a rate of 0.42 mm/s. The maximum force (N) and tensile strength (N/cm) were measured with a tensiometer, and stiffness (N/mm) was calculated from the slope of the force-versus-displacement curve. Adjacent sections of tissue were stained with hematoxylin and eosin (H&E) and analyzed for inflammation, fibrosis, and tissue ingrowth. Data are reported as mean ± SEM. Statistical significance (P < 0.05) was determined using a two-way ANOVA and Bonferroni post-test. Results No significant difference in maximum force was detected between meshes at any of the time points (P > 0.05 for all comparisons). However, for each mesh type, the maximum strength at 5 months was significantly lower than that at 1 month (P < 0.05). No significant difference in stiffness was detected between the mesh types or between timepoints (P > 0.05 for all comparisons). No significant differences with regard to inflammation, fibrosis, or tissue ingrowth were detected between mesh types at any time point (P > 0.09 for all comparisons). However

Histologic and biomechanical evaluation of a novel macroporous polytetrafluoroethylene knit mesh compared to lightweight and heavyweight polypropylene mesh in a porcine model of ventral incisional hernia repair.

PubMed

Melman, L; Jenkins, E D; Hamilton, N A; Bender, L C; Brodt, M D; Deeken, C R; Greco, S C; Frisella, M M; Matthews, B D

2011-08-01

To evaluate the biocompatibility of heavyweight polypropylene (HWPP), lightweight polypropylene (LWPP), and monofilament knit polytetrafluoroethylene (mkPTFE) mesh by comparing biomechanics and histologic response at 1, 3, and 5 months in a porcine model of incisional hernia repair. Bilateral full-thickness abdominal wall defects measuring 4 cm in length were created in 27 Yucatan minipigs. Twenty-one days after hernia creation, animals underwent bilateral preperitoneal ventral hernia repair with 8 × 10 cm pieces of mesh. Repairs were randomized to Bard(®)Mesh (HWPP, Bard/Davol, http://www.davol.com), ULTRAPRO(®) (LWPP, Ethicon, http://www.ethicon.com), and GORE(®)INFINIT Mesh (mkPTFE, Gore & Associates, http://www.gore.com). Nine animals were sacrificed at each timepoint (1, 3, and 5 months). At harvest, a 3 × 4 cm sample of mesh and incorporated tissue was taken from the center of the implant site and subjected to uniaxial tensile testing at a rate of 0.42 mm/s. The maximum force (N) and tensile strength (N/cm) were measured with a tensiometer, and stiffness (N/mm) was calculated from the slope of the force-versus-displacement curve. Adjacent sections of tissue were stained with hematoxylin and eosin (H&E) and analyzed for inflammation, fibrosis, and tissue ingrowth. Data are reported as mean ± SEM. Statistical significance (P < 0.05) was determined using a two-way ANOVA and Bonferroni post-test. No significant difference in maximum force was detected between meshes at any of the time points (P > 0.05 for all comparisons). However, for each mesh type, the maximum strength at 5 months was significantly lower than that at 1 month (P < 0.05). No significant difference in stiffness was detected between the mesh types or between timepoints (P > 0.05 for all comparisons). No significant differences with regard to inflammation, fibrosis, or tissue ingrowth were detected between mesh types at any time point (P > 0.09 for all comparisons). However, over time

Crystal growth and physical properties of SrCu2As2, SrCu2Sb2, and BaCu2Sb2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anand, V.K.; Perera, P. Kanchana; Pandey, Abhishek

2012-06-25

We report the growth of single crystals of SrCu2As2, SrCu2Sb2, SrCu2(As0.84Sb0.16)2, and BaCu2Sb2 using the self-flux technique and their structural, magnetic, thermal, and transport properties that were investigated by powder x-ray diffraction (XRD), magnetic susceptibility χ, specific heat Cp, and electrical resistivity ρ measurements versus temperature T from 1.8 to 350 K. Rietveld refinements of XRD patterns for crushed crystals confirm that SrCu2As2 crystallizes in the ThCr2Si2-type body-centered tetragonal structure (space group I4/mmm) and SrCu2Sb2 crystallizes in the CaBe2Ge2-type primitive tetragonal structure (space group P4/nmm). However, as reported previously, BaCu2Sb2 is found to have a large unit cell consisting ofmore » three blocks. Here a ThCr2Si2-type block is sandwiched between two CaBe2Ge2-type blocks along the c axis with an overall symmetry of I4/mmm, as reported, but likely with a monoclinic distortion. The χ data of all these compounds are diamagnetic and reveal nearly T-independent anisotropic behavior. The χ of SrCu2As2 is found to be larger in the ab plane than along the c axis, as also previously reported for pure and doped BaFe2As2, whereas the χ values of SrCu2Sb2 and BaCu2Sb2 are larger along the c axis. This difference in anisotropy appears to arise from the differences between the crystal structures. The finite values of the Sommerfeld linear specific heat coefficients γ and the T dependences of ρ reveal metallic character of all four compounds. The electronic and magnetic properties indicate that these compounds are sp metals with Cu in the nonmagnetic 3d10 electronic configuration corresponding to the oxidation state Cu+1, as previously predicted theoretically for SrCu2As2 by Singh [ Phys. Rev. B 79 153102 (2009)]. We present a brief review of theoretical and experimental work on the doping character of transition metals for Fe in BaFe2As2. The As–As covalent interlayer bond distances in the collapsed-tetragonal (Ca

Displacement of teeth without and with bonded fixed orthodontic retainers: 3D analysis using triangular target frames and optoelectronic motion tracking device.

PubMed

Chakroun, Firas; Colombo, Vera; Lie Sam Foek, Dave; Gallo, Luigi Maria; Feilzer, Albert; Özcan, Mutlu

2018-06-06

The objective of this study was to evaluate the anterior tooth movement without and with bonded fixed orthodontic retainers under incremental loading conditions. Six extracted mandibular anterior human teeth were embedded in acrylic resin in True Form I Arch type and 3D reconstruction of Digital Volume Tomography (DVT) images (0.4 mm 3 voxels) were obtained. The anatomy of each tooth was segmented and digitally reconstructed using 3D visualization software for medical images (AMIRA, FEI SVG). The digital models of the teeth were repositioned to form an arch with constant curvature using a CAD software (Rhinoceros) and a base holder was designed fitting the shape of the roots. The clearance between the roots and their slot in the holder was kept constant at 0.3 mm to replicate the periodontal ligament thickness. The holder and the teeth were then manufactured by 3D printing (Objet Eden 260VS, Stratasys) using a resin material for dental applications (E = 2-3 GPa). The 3D-printed teeth models were then positioned in the holder and the root compartments were filled with silicone. The procedure was repeated to obtain three identical arch models. Each model was tested for tooth mobility by applying force increasing from 5 to 30 N with 5 N increments applied perpendicular on the lingual tooth surface on the incisal one third (crosshead speed: 0.1 mm/s). The teeth on each model were first tested without retainer (control) and subsequently with the bonded retainers (braided bonded retainer wire; Multi-strand 1 × 3 high performance wire, 0.022″ × 0.016″). Tooth displacement was measured in terms of complicance (F/Δ movement) (N/mm) using custom-built optoelectronic motion tracking device (OPTIS) (accuracy: 5 µm; sampling rate: 200 Hz). The position of the object was detected through three LEDs positioned in a fixed triangular shape on a metal support (Triangular Target Frame). The measurements were repeated for three times for each tooth

Status Report - Cane Fiberboard Properties and Degradation Rates for Storage of the 9975 Shipping Package in KAMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daugherty, W. L.

the package is not as well characterized. While the outer drum does not provide an air-tight seal, it does greatly restrict the gain or loss of moisture in the fiberboard. Preliminary efforts have identified a relationship between the moisture content of fiberboard samples and the relative humidity of the surrounding air, but further work is needed in this area. Improvement in understanding this relationship might be realized with a change in the way humidity data are collected during field surveillances. It is recommended that the humidity be measured through a caplug hole before the package is removed from its storage location. The package would remain in thermal equilibrium, and anomalous humidity changes could be avoided. Further work should be performed to better define KAMS storage conditions and the environment within the 9975 shipping packages, and to identify appropriate limits for each property. This should be a joint effort by SRNL and NMM personnel. The results and model predictions presented in this report are applicable to 9975 packages with cane fiberboard overpack assemblies. A separate effort is underway to identify whether softwood fiberboard would behave similarly. In addition, the degradation models do not address the effects of non-conforming conditions such as the presence of excess moisture and mold, or beetle infestations.« less

Sensitivity of WRF precipitation on microphysical and boundary layer parameterizations during extreme events in Eastern Mediterranean

NASA Astrophysics Data System (ADS)

Pytharoulis, I.; Karagiannidis, A. F.; Brikas, D.; Katsafados, P.; Papadopoulos, A.; Mavromatidis, E.; Kotsopoulos, S.; Karacostas, T. S.

2010-09-01

numerical experiments. These events are characterized by strong precipitation with daily amounts exceeding 100 mm. For example, the case of 24 to 26 October 2009 was associated with floods in the eastern mainland of Greece. In Pieria (northern Greece), that was the most afflicted area, one individual perished in the overflowed Esonas river and significant damages were caused in both the infrastructure and cultivations. Precipitation amounts of 347 mm in 3 days were measured in the station of Vrontou, Pieria (which is at an elevation of only 120 m). The model results are statistically analysed and compared to the available surface observations and satellite derived precipitation data in order to identify the parameterizations (and their combinations) that provide the best representation of the spatiotemporal variability of precipitation in extreme conditions. Preliminary results indicate that the MYNN boundary layer parameterization outperforms the one of MYJ. However, the best results are produced by the combination of the Ferrier new Eta microphysics with the MYJ scheme, which are the default schemes of the well-known and reliable ETA and WRF-NMM models. Similarly, good results are produced by the combination of the New Thompson V3.1 microphysics with MYNN boundary layer scheme. On the other hand, the worst results (with mean absolute error up to about 150 mm/day) appear when the WRF Single Moment 5-classes scheme is used with MYJ. Finally, an effort is made to identify and analyze the main factors that are responsible for the aforementioned differences.

Ruschita Romanian marble - 130 years of official exploitation and 130 m depth of architectural beauty around the word

NASA Astrophysics Data System (ADS)

Cetean, Valentina

2013-04-01

Developed in a large metamorphic area, the marble deposit from Ruschita perimeter is the most important Romanian source for ornamental stone, the old quarry being operative since 1883. The closest locality offer the commercial name also, identical with the geological one as is defined in the technical referentials and in the denomination European standard. Ruschita is also an active quarry, developed by step-by-step expansion in depth (the initial extraction reached 130 m depth), but also in the adjacent areas. The important height of the open deposit offered the possibility to the owner, MARMOSIM SA, to apply an experimental extraction method, by underground mining. It is the only Romanian place, and few in the world, where this spectacular mining element can be found for dimension stone. The extraction gallery was built starting from the lower level of the old quarry and allowed obtaining nicer and bigger blocks. The Ruschita marble is a metamorphic stone with high crystallinity and medium size of crystals (until 0.2-0.5 mm). Has the basic colour from white and grey to pink, with many intermediary nuances generally given by grey veins and less by impurities from internal structure. The stone present irregular break, sometimes following the very narrow internal discontinuities, invisible at macroscopic analyse. The main physical - mechanical characteristics are presented below: Characteristic M.U. Value Apparent density Kg/m3 2680 - 2720 Water absorption % 0.12 - 0.21 Capillarity g/m2.s0,5 0.130-0.218 Porosity % 0.30 - 0.74 Compression strength N/mm2 85 - 120 Flexural strength MPa 15-18 Rupture energy J 5 Coefficient of frost cleftness % 10 -14 Abrasion resistance - Bohme cm3/50cm2 17-18 Salt crystallization % 0.1 Nowadays, the extraction in the Ruschita area is achieved by equipments from Dazzini, Fantini, Pellegrini, Korfamann, Caterpillar, Volvo and Komatsu. The average volume of blocks is bigger than 10-12 m2. The Ruschita marble can be easily cut at size and