Science.gov

Sample records for dynamic transpedicular stabilisation

  1. Dynamical stabilisation in optical tweezers

    NASA Astrophysics Data System (ADS)

    Jones, Philip H.; Richards, Christopher J.; Smart, Thomas J.; Cubero, David

    2015-03-01

    We present a study of dynamical stabilisation of an overdamped, microscopic pendulum realised using optical tweezers. We first derive an analytical expression for the equilibrium dynamically stabilised pendulum position in a regime of high damping and high modulation frequency of the pendulum pivot. This model implies a threshold behavior for stabilisation to occur, and a continuous evolution of the angular position which, unlike the underdamped case, does not reach the fully inverted position. We then test the theoretical predictions using an optically trapped microparticle subject to fluid drag force, finding reasonable agreement with the threshold and equilibrium behavior at high modulation amplitude. Analytical theory and experiments are complemented by Brownian motion simulations.

  2. Viscoelastic properties of a spinal posterior dynamic stabilisation device.

    PubMed

    Lawless, Bernard M; Barnes, Spencer C; Espino, Daniel M; Shepherd, Duncan E T

    2016-06-01

    The purpose of this study was to quantify the frequency dependent viscoelastic properties of two types of spinal posterior dynamic stabilisation devices. In air at 37°C, the viscoelastic properties of six BDyn 1 level, six BDyn 2 level posterior dynamic stabilisation devices (S14 Implants, Pessac, France) and its elastomeric components (polycarbonate urethane and silicone) were measured using Dynamic Mechanical Analysis. The viscoelastic properties were measured over the frequency range 0.01-30Hz. The BDyn devices and its components were viscoelastic throughout the frequency range tested. The mean storage stiffness and mean loss stiffness of the BDyn 1 level device, BDyn 2 level device, silicone component and polycarbonate urethane component all presented a logarithmic relationship with respect to frequency. The storage stiffness of the BDyn 1 level device ranged from 95.56N/mm to 119.29N/mm, while the BDyn 2 level storage stiffness ranged from 39.41N/mm to 42.82N/mm. BDyn 1 level device and BDyn 2 level device loss stiffness ranged from 10.72N/mm to 23.42N/mm and 4.26N/mm to 9.57N/mm, respectively. No resonant frequencies were recorded for the devices or its components. The elastic property of BDyn 1 level device is influenced by the PCU and silicone components, in the physiological frequency range. The viscoelastic properties calculated in this study may be compared to spinal devices and spinal structures. PMID:27018832

  3. [In vitro assessment of the lumbo-sacral spine after posterior transpedicular stabilization and anterior cage implantation].

    PubMed

    Smoczyński, Maciej; Smoczyński, Andrzej; Luczkiewicz, Piotr; Pankowski, Rafał

    2006-01-01

    The biomechanical tests were performed on 9 cadaver specimens of lumbo-sacral spine. The specimens consisted of two lumbar motion segments, sacral bone together with the sacroiliac joint and parts of pelvis. The goal of the biomechanical tests was to estimate the motion of the lumbar spine, which was stabilised by the transpedicular implant and by the intervertebral cages. The tests showed that the traspedicular stabilisation is more effective than inervetebral with cages. PMID:17128766

  4. Evolution stabilises the synchronising dynamics of poikilotherm life cycles.

    PubMed

    Cobbold, C A; Powell, J A

    2011-05-01

    Temperature is the most significant factor controlling developmental timing of most temperate poikilotherms. In the face of climate change, a crucial question is how will poikilothermic organisms evolve when faced with changing thermal environments? In this paper, we integrate models for developmental timing and quantitative genetics. A simple model for determining developmental milestones (emergence times, egg hatch) is introduced, and the general quantitative genetic recursion for the mean value of developmental parameters presented. Evolutionary steps proportional to the difference between current median parameters and parameters currently selected for depend on the fitness, which is assumed to depend on emergence density. Asymptotic states of the joint model are determined, which turn out to be neutrally stable (marginal) fixed points in the developmental model by itself, and an associated stable emergence distribution is also described. An asymptotic convergence analysis is presented for idealized circumstances, indicating basic stability criteria. Numerical studies show that the stability analysis is quite conservative, with basins of attraction to the asymptotic states that are much larger than expected. It is shown that frequency-dependent selection drives oscillatory dynamics and that the asymptotic states balance the asymmetry of the emergence distribution and the fitness function. PMID:20532991

  5. Stabilising effect of dynamic interspinous spacers in degenerative low-grade lumbar instability.

    PubMed

    Holinka, Johannes; Krepler, Petra; Matzner, Michael; Grohs, Josef G

    2011-03-01

    The aim of the study was to investigate the stabilising effect of dynamic interspinous spacers (IS) in combination with interlaminar decompression in degenerative low-grade lumbar instability with lumbar spinal stenosis and to compare its clinical effect to patients with lumbar spinal stenosis in stable segments treated by interlaminar decompression only. Fifty consecutive patients with a minimum age of 60 years were scheduled for interlaminar decompression for clinically and radiologically confirmed lumbar spinal stenosis. Twenty-two of these patients (group DS) with concomitant degenerative low-grade lumbar instability up to 5 mm translational slip were treated by interlaminar decompression and additional dynamic IS implantation. The control group (D) with lumbar spinal stenosis in stable segments included 28 patients and underwent only interlaminar decompression. The mean follow-up was 46 months in group D and 44 months in group DS. A visual analogue scale (VAS), Oswestry Disability Index (ODI) and walking distance were evaluated pre- and postoperatively. The segmental instability was evaluated in flexion-extension X-rays. The implantation of an IS significantly reduced the lumbar instability on flexion-extension X-rays. At the time of follow-up walking distance, VAS and ODI showed a significant improvement in both groups, but no statistical significance between groups D and DS. Four patients each in groups D and DS had revision surgery during the period of evaluation. The stabilising effect of dynamic IS in combination with interlaminar decompression offers an opportunity for an effective treatment for degenerative low-grade lumbar instability with lumbar spinal stenosis. PMID:20419452

  6. Acquired phototrophy stabilises coexistence and shapes intrinsic dynamics of an intraguild predator and its prey.

    PubMed

    Moeller, Holly V; Peltomaa, Elina; Johnson, Matthew D; Neubert, Michael G

    2016-04-01

    In marine ecosystems, acquired phototrophs - organisms that obtain their photosynthetic ability by hosting endosymbionts or stealing plastids from their prey - are omnipresent. Such taxa function as intraguild predators yet depend on their prey to periodically obtain chloroplasts. We present a new theory for the effects of acquired phototrophy on community dynamics by analysing a mathematical model of this predator-prey interaction and experimentally verifying its predictions with a laboratory model system. We show that acquired phototrophy stabilises coexistence, but that the nature of this coexistence exhibits a 'paradox of enrichment': as light increases, the coexistence between the acquired phototroph and its prey transitions from a stable equilibrium to boom-bust cycles whose amplitude increases with light availability. In contrast, heterotrophs and mixotrophic acquired phototrophs (that obtain  < 30% of their carbon from photosynthesis) do not exhibit such cycles. This prediction matches field observations, in which only strict ( > 95% of carbon from photosynthesis) acquired phototrophs form blooms. PMID:26833622

  7. Robust gain-scheduling energy-to-peak control of vehicle lateral dynamics stabilisation

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Zhang, Xinjie; Wang, Junmin

    2014-03-01

    In this paper, we investigate the vehicle lateral dynamics stabilisation problem to enhance vehicle handling by considering time-varying longitudinal velocity. The longitudinal velocity is described by a polytope with finite vertices and a novel technique is proposed to reduce the number of vertices. Since the tyre dynamics is nonlinear, the cornering stiffness is represented via the norm-bounded uncertainty. Concerning the time-varying velocity and the nonlinear tyre model, a linear parameter-varying vehicle model is obtained. As the velocity and the states are measurable, a gain-scheduling state-feedback controller is introduced. In the lateral control, the sideslip angle is required to be as small as possible and the yaw rate is constrained to a certain level. Thus, the control objective is to minimise the sideslip angle while the yaw rate is under a prescribed level or constrain both the sideslip angle and the yaw rate to prescribed levels. To consider the transient response of the closed-loop system, the ?-stability is also employed in the energy-to-peak control. The optimal controller can be obtained by solving a set of linear matrix inequalities. A nonlinear vehicle model is utilised to illustrate the design procedure and the effectiveness of the proposed design method. Finally, simulations and comparisons are carried out to show the significant advantage of the designed controller. Compared to the open-loop system, the closed-loop system with the designed controller can achieve much smaller sideslip angle and the yaw rate is closer to the desired yaw rate from a reference model. Therefore, the vehicle safety and the handling are both improved in our simulation cases.

  8. Large Eddy Simulation of flame stabilisation dynamics and vortex control in a lifted H2/N2 jet flame

    NASA Astrophysics Data System (ADS)

    Duwig, Christophe

    2011-06-01

    Flame stabilisation in (highly) preheated mixture is common in several industrial applications. When the reactants are injected separately in the device (usually at high-speed), the flame is lifted so that the fuel and oxidant first mix to give an ignitable mixture. If the temperature of the mixture is adequate, it auto-ignites stabilizing the flame. Here we focus on an academic lifted jet flame and Large Eddy Simulation (LES) is used to capture the flame and auto-ignition dynamics. Comparisons with experimental data show that LES simulates accurately high OH fluctuation levels at the stabilisation location. The vortex dynamics linked to these fluctuations is analyzed and it is found that small scale coherent structures play a vital role in the auto-ignition process. These structures are axial vorticity tubes (braids) and are located relatively far (in the radial direction) from the shear-layer. As a consequence, the lift-off height varies dramatically in time leading to OH fluctuations of the order of the mean OH concentration. This scenario is monitored in the compositional space highlighting the simultaneous evolution of OH, HO 2 and temperature. Further, different strategies for open-loop control of the flame lift-off height are tested. In order to anchor the flame at different positions downstream of the nozzle, the vortex dynamics in the shear-layer was modified. Promoting successively vortex ring and braids, the auto-ignition region was moved significantly. In particular, modified nozzle geometries impacted the formation of braids and ensured a good premixing very close to the nozzle. As a consequence, it was possible to reduce significantly the lift-off height and stabilise the flame few diameters downstream of the nozzle.

  9. Predator-prey dynamics stabilised by nonlinearity explain oscillations in dust-forming plasmas

    NASA Astrophysics Data System (ADS)

    Ross, A. E.; McKenzie, D. R.

    2016-04-01

    Dust-forming plasmas are ionised gases that generate particles from a precursor. In nature, dust-forming plasmas are found in flames, the interstellar medium and comet tails. In the laboratory, they are valuable in generating nanoparticles for medicine and electronics. Dust-forming plasmas exhibit a bizarre, even puzzling behaviour in which they oscillate with timescales of seconds to minutes. Here we show how the problem of understanding these oscillations may be cast as a predator-prey problem, with electrons as prey and particles as predators. The addition of a nonlinear loss term to the classic Lotka-Volterra equations used for describing the predator-prey problem in ecology not only stabilises the oscillations in the solutions for the populations of electrons and particles in the plasma but also explains the behaviour in more detail. The model explains the relative phase difference of the two populations, the way in which the frequency of the oscillations varies with the concentration of the precursor gas, and the oscillations of the light emission, determined by the populations of both species. Our results demonstrate the value of adopting an approach to a complex physical science problem that has been found successful in ecology, where complexity is always present.

  10. Predator-prey dynamics stabilised by nonlinearity explain oscillations in dust-forming plasmas.

    PubMed

    Ross, A E; McKenzie, D R

    2016-01-01

    Dust-forming plasmas are ionised gases that generate particles from a precursor. In nature, dust-forming plasmas are found in flames, the interstellar medium and comet tails. In the laboratory, they are valuable in generating nanoparticles for medicine and electronics. Dust-forming plasmas exhibit a bizarre, even puzzling behaviour in which they oscillate with timescales of seconds to minutes. Here we show how the problem of understanding these oscillations may be cast as a predator-prey problem, with electrons as prey and particles as predators. The addition of a nonlinear loss term to the classic Lotka-Volterra equations used for describing the predator-prey problem in ecology not only stabilises the oscillations in the solutions for the populations of electrons and particles in the plasma but also explains the behaviour in more detail. The model explains the relative phase difference of the two populations, the way in which the frequency of the oscillations varies with the concentration of the precursor gas, and the oscillations of the light emission, determined by the populations of both species. Our results demonstrate the value of adopting an approach to a complex physical science problem that has been found successful in ecology, where complexity is always present. PMID:27046237

  11. Predator-prey dynamics stabilised by nonlinearity explain oscillations in dust-forming plasmas

    PubMed Central

    Ross, A. E.; McKenzie, D. R.

    2016-01-01

    Dust-forming plasmas are ionised gases that generate particles from a precursor. In nature, dust-forming plasmas are found in flames, the interstellar medium and comet tails. In the laboratory, they are valuable in generating nanoparticles for medicine and electronics. Dust-forming plasmas exhibit a bizarre, even puzzling behaviour in which they oscillate with timescales of seconds to minutes. Here we show how the problem of understanding these oscillations may be cast as a predator-prey problem, with electrons as prey and particles as predators. The addition of a nonlinear loss term to the classic Lotka-Volterra equations used for describing the predator-prey problem in ecology not only stabilises the oscillations in the solutions for the populations of electrons and particles in the plasma but also explains the behaviour in more detail. The model explains the relative phase difference of the two populations, the way in which the frequency of the oscillations varies with the concentration of the precursor gas, and the oscillations of the light emission, determined by the populations of both species. Our results demonstrate the value of adopting an approach to a complex physical science problem that has been found successful in ecology, where complexity is always present. PMID:27046237

  12. Multi-responsive coordination polymers utilising metal-stabilised, dynamic covalent imine bonds.

    PubMed

    García, Fátima; Pelss, Janis; Zuilhof, Han; Smulders, Maarten M J

    2016-07-12

    We report how the combination of dynamic covalent imine bonds and coordination bonds in a single polymer material not only imparts enhanced stability to the final polymer, but also allows the material to be sensitive to a range of stimuli, offering more fine-grained control over its properties. PMID:26879208

  13. Cyanobacterial and microcystins dynamics following the application of hydrogen peroxide to waste stabilisation ponds

    NASA Astrophysics Data System (ADS)

    Barrington, D. J.; Ghadouani, A.; Ivey, G. N.

    2013-02-01

    Cyanobacteria and cyanotoxins are a risk to human and ecological health, and a hindrance to biological wastewater treatment. This study investigated the use of hydrogen peroxide (H2O2) for the removal of cyanobacteria and cyanotoxins from within waste stabilization ponds (WSPs). The daily dynamics of cyanobacteria and microcystins (a commonly occurring cyanotoxin) were examined following the addition of H2O2 to wastewater within both the laboratory and at the full-scale within a WSP. Hydrogen peroxide treatment at concentrations ≥ 10-4 g H2O2 μg-1 of total phytoplankton chlorophyll a led to the death of cyanobacteria, in turn releasing intracellular microcystins to the dissolved state. In the full-scale trial, dissolved microcystins were then degraded to negligible concentrations by H2O2 and environmental processes within five days. A shift in the phytoplankton assemblage towards beneficial chlorophyta species was also observed within days of H2O2 addition. However, within weeks, the chlorophyta population was significantly reduced by the re-establishment of toxic cyanobacterial species. This re-establishment was likely due to the inflow of cyanobacteria from ponds earlier in the treatment train, suggesting that whilst H2O2 may be a suitable short-term management technique, it must be coupled with control over inflows if it is to improve WSP performance in the longer term.

  14. Cyanobacterial and microcystins dynamics following the application of hydrogen peroxide to waste stabilisation ponds

    NASA Astrophysics Data System (ADS)

    Barrington, D. J.; Ghadouani, A.; Ivey, G. N.

    2013-06-01

    Cyanobacteria and cyanotoxins are a risk to human and ecological health, and a hindrance to biological wastewater treatment. This study investigated the use of hydrogen peroxide (H2O2) for the removal of cyanobacteria and cyanotoxins from within waste stabilization ponds (WSPs). The daily dynamics of cyanobacteria and microcystins (commonly occurring cyanotoxins) were examined following the addition of H2O2 to wastewater within both the laboratory and at the full scale within a maturation WSP, the final pond in a wastewater treatment plant. Hydrogen peroxide treatment at concentrations ≥ 0.1 mg H2O2 μg-1 total phytoplankton chlorophyll a led to the lysis of cyanobacteria, in turn releasing intracellular microcystins to the dissolved state. In the full-scale trial, dissolved microcystins were then degraded to negligible concentrations by H2O2 and environmental processes within five days. A shift in the phytoplankton assemblage towards beneficial Chlorophyta species was also observed within days of H2O2 addition. However, within weeks, the Chlorophyta population was significantly reduced by the re-establishment of toxic cyanobacterial species. This re-establishment was likely due to the inflow of cyanobacteria from ponds earlier in the treatment train, suggesting that whilst H2O2 may be a suitable short-term management technique, it must be coupled with control over inflows if it is to improve WSP performance in the longer term.

  15. Transpedicular screw fixation for type II Hangman's fracture: a motion preserving procedure.

    PubMed

    ElMiligui, Yasser; Koptan, Wael; Emran, Ihab

    2010-08-01

    Opinions have varied regarding the optimal treatment of an unstable Hangman's fracture. C2 pedicle screw instrumentation is a biomechanically strong fixation which although done through a simple posterior approach, is a technically demanding procedure. This prospective, non-randomized multicentre study included 15 consecutive patients with displaced type II traumatic spondylolisthesis of the axis. There were nine males and six females with a mean age of 37 years at surgery. The cause of injury was a road traffic accident in 11 patients and a fall from height in 4 patients. All patients had a single stage reduction and direct transpedicular screw fixation through the C2 pedicles. During follow-up, clinical evaluation and plain X-rays were performed at each visit; at 6-month follow-up, additional dynamic lateral flexion/extension views and a CT scan were performed. The average follow-up period was 32 months (range 25-56 months). At final follow-up, all patients were asymptomatic and regained a good functional outcome with no limitation of range of motion; all the patients showed solid union with no implant failure. There were no neurological complications. At 6-month follow-up, CT evaluation showed fusion in all patients and an adequate position of 28 screws. Two pedicle screws (6.6%) showed minimal (defined as <2 mm) intrusion; one into the spinal canal and the other into the vertebral foreamen. Transpedicular screw fixation through the C2 pedicles is a safe and effective method in treating type II traumatic spondylolisthesis of the axis resulting in good clinical and radiological outcomes. Adequate reduction was achieved and motion segments were preserved with its use. PMID:20401619

  16. Antioxidant Stabilisation of Polymers

    NASA Astrophysics Data System (ADS)

    Shlyapnikov, Yurii A.

    1981-06-01

    Physicochemical aspects of the stabilisation of polymers are discussed. Attention is paid mainly to the aging and stabilisation of polymers under processing conditions. Topics considered are the kinetics and mechanism of the high-temperature oxidation of polymers, critical phenomena in the inhibited oxidation of polymers, the theory of synergism and antagonism among antioxidants, the reasons for differences in efficiency of antioxidants, and certain aspects of the relation between the efficiency of antioxidants and their molecular structure. A list of 132 references is included.

  17. Mast cell stabilisers.

    PubMed

    Zhang, Tao; Finn, Deirdre Frances; Barlow, James William; Walsh, John Jarlath

    2016-05-01

    Mast cells play a critical role in type 1 hypersensitivity reactions. Indeed, mast cell mediators are implicated in many different conditions including allergic rhinitis, conjunctivitis, asthma, psoriasis, mastocytosis and the progression of many different cancers. Thus, there is intense interest in the development of agents which prevent mast cell mediator release or which inhibit the actions of such mediators once released into the environment of the cell. Much progress into the design of new agents has been made since the initial discovery of the mast cell stabilising properties of khellin from Ammi visnaga and the clinical approval of cromolyn sodium. This review critically examines the progress that has been made in the intervening years from the design of new agents that target a specific signalling event in the mast cell degranulation pathway to those agents which have been developed where the precise mechanism of action remains elusive. Particular emphasis is also placed on clinically used drugs for other indications that stabilise mast cells and how this additional action may be harnessed for their clinical use in disease processes where mast cells are implicated. PMID:26130122

  18. Measuring decomposition to understand stabilisation: A journey to Serendip? The example of root derived and pyrogenic organic matter dynamics in soils

    NASA Astrophysics Data System (ADS)

    Abiven, S.

    2012-04-01

    Soils store one of the largest organic carbon reservoirs of terrestrial ecosystems and any change in this carbon stock can significantly modify climate on the global scale. The mechanisms of this carbon stabilisation in soils are still not well known, difficult to define and, as a consequence, difficult to assess by measurement or by modelling. One method often chosen to access stabilisation processes is to measure decomposition of fresh organic inputs, with the underlying hypothesis that what did not left the soil profile should be stabilized for a certain duration in the soils. This approach is often associated with a deterministic view of organic compounds behaviour in soils, i.e. some compounds are more recalcitrant than others, and so the chemical compounds of the initial organic inputs should determine the stability of organic matter in the soils. Decomposition studies are often favoured because the initial conditions can be well characterised or controlled, while studies based on archive samples could be limited by the knowledge of the edaphic conditions. Recent findings challenge this decomposition approach: it has been shown that specific compounds tend to turnover more or less at the same speed in the soil, "recalcitrant" carbon is not always associated with the oldest ages… Recently, Schmidt et al. (2011) propose that persistence of organic matter is an ecosystem property and that environmental and biological controls dominate. In the frame of this new conceptual approach, the authors are also recommending a new generation of experiments. What could be these new experiments? How to design new decomposition experiments in order to better assess carbon stabilisation in soils? Is there serendipity to be found in decomposition studies, i.e. can we expect relevant new outcomes from controlled conditions studies? In this contribution, I will propose some thoughts regarding these questions, based on examples related to two promising long-lasting carbon inputs

  19. Percutaneous Transpedicular Fixation: Technical tips and Pitfalls of Sextant and Pathfinder Systems

    PubMed Central

    Hassan, Ahmed Salah Aldin

    2016-01-01

    Study Design The efficacy of the operative techniques, possible benefits as well as pitfalls and limitations of the techniques are discussed. Potential drawbacks are also detected. Purpose This study aims to report indications, techniques, and our experience with the use of the Sextant and PathFinder percutaneous transpedicular screw fixation systems. Overview of Literature Percutaneous pedicle screw insertion is a novel technique. Successful percutaneous placement of pedicle screws requires surgical skill and experience because of lack of anatomic surface landmarks. Fluoroscopy-guided percutaneous placement of pedicle screws is effective. Many systems are now available. Methods We conducted a prospective operative and postoperative analysis of 40 patients with absolute indication for thoracic or lumbar instability between January 2009 and June 2013. All procedures were performed with the Sextant (group A) and PathFinder (group B) systems under fluoroscopic guidance. Operative techniques are discussed and the results compared. Results Percutaneous transpedicular screw fixation minimizes the morbidity associated with open techniques without compromising the quality of fixation. A total of 190 screws were inserted. There was no additional morbidity. Postoperative computed tomography images and plain X-rays were analyzed. Reduction of visual analog scale scores of back pain was evident. Conclusions Fluoroscopy-guided percutaneous pedicular screws are feasible and can be safely done. Current systems allow multi-segmental fixation with significantly less difficulties. The described techniques have acceptable intra- and postoperative complication rates, and overall sufficient pain control with early mobilization of patients. PMID:26949466

  20. Transpedicular hydroxyapatite grafting with indirect reduction for thoracolumbar burst fractures with neurological deficit: A prospective study

    PubMed Central

    Toyone, Tomoaki; Ozawa, Tomoyuki; Wada, Yuichi; Kamikawa, Koya; Watanabe, Atsuya; Yamashita, Takeshi; Matsuki, Keisuke; Shiboi, Ryutaro; Matsumoto, Nobuhiro; Ochiai, Shunsuke; Tanaka, Tadashi

    2007-01-01

    Background: The major problem after posterior correction and instrumentation in the treatment of thoracolumbar burst fractures is failure to support the anterior spinal column leading to loss of correction of kyphosis and hardware breakage. We conducted a prospective consecutive series to evaluate the outcome of the management of acute thoracolumbar burst fractures by transpedicular hydroxyapatite (HA) grafting following indirect reduction and pedicle screw fixation. Materials and Methods: Eighteen consecutive patients who had thoracolumbar burst fractures and associated incomplete neurological deficit were operatively treated within four days of admission. Following indirect reduction and pedicle screw fixation, transpedicular intracorporeal HA grafting to the fractured vertebrae was performed. Mean operative time was 125 min and mean blood loss was 150 ml. Their implants were removed within one year and were prospectively followed for at least two years. Results: The neurological function of all 18 patients improved by at least one ASIA grade, with nine (50%) patients demonstrating complete neurological recovery. Sagittal alignment was improved from a mean preoperative kyphosis of 17°to −2°(lordosis) by operation, but was found to have slightly deteriorated to 1° at final followup observation. The CT images demonstrated a mean spinal canal narrowing preoperatively, immediate postoperative and at final followup of 60%, 22% and 11%, respectively. There were no instances of hardware failure. No patient reported severe pain or needed daily dosages of analgesics at the final followup. The two-year postoperative MRI demonstrated an increase of one grade in disc degeneration (n = 17) at the disc above and in 11 patients below the fractured vertebra. At the final followup, flexion-extension radiographs revealed that a median range of motion was 4, 6 and 34 degrees at the cranial segment of the fractured vertebra, caudal segment and L1-S1, respectively. Bone

  1. Mycorrhizal aspects in slope stabilisation

    NASA Astrophysics Data System (ADS)

    Graf, Frank

    2016-04-01

    In order to re-colonise and stabilise slopes affected by superficial soil failure with plants essential requirements have to be met: the plants must grow the plants must survive sustainably plant succession must start and continuously develop These requirements, however, are anything but easy given, particularly under the often hostile environmental conditions dominating on bare and steep slopes. Mycorrhizal fungi, the symbiotic partners of almost all plants used in eco-engineering, are said to improve the plants' ability to overcome periods governed by strongly (growth) limiting factors. Subsequently, results of investigations are presented of mycorrhizal effects on different plant and soil functions related to eco-engineering in general and soil and slope stabilisation in particular. Generally, inoculation yielded higher biomass of the host plants above as well as below ground. Furthermore, the survival rate was higher for mycorrhized compared to non-mycorrhized plants, particularly under extreme environmental conditions. However, the scale of the mycorrhizal impact may be species specific of both the plant host as well as the fungal partner(s) and often becomes evident only after a certain time lag. Depending on the plant-fungus combination the root length per soil volume was found to be between 0 and 2.5 times higher for inoculated compared to non-inoculated specimens. On an alpine graded ski slope the survival of inoculated compared to non-treated Salix herbacea cuttings was significant after one vegetation period only for one of the three added mycorrhizal fungus species. However, after three years all of the inoculated plantlets performed significantly better than the non-inoculated controls. The analysis of the potential for producing and stabilising soil aggregates of five different ectomycorrhizal fungi showed high variation and, for the species Inocybe lacera, no significant difference compared to untreated soil. Furthermore, inoculation of Salix

  2. Percutaneous Transpedicular Interbody Fusion Technique in Percutaneous Pedicle Screw Stabilization for Pseudoarthrosis Following Pyogenic Spondylitis.

    PubMed

    Ikuta, Ko; Masuda, Keigo; Yonekura, Yutaka; Kitamura, Takahiro; Senba, Hideyuki; Shidahara, Satoshi

    2016-04-01

    This report introduces a percutaneous transpedicular interbody fusion (PTPIF) technique in posterior stabilization using percutaneous pedicle screws (PPSs). An 81-year-old man presented with pseudoarthrosis following pyogenic spondylitis 15 months before. Although no relapse of infection was found, he complained of obstinate low back pain and mild neurological symptoms. Radiological evaluations showed a pseudoarthrosis following pyogenic spondylitis at T11-12. Posterior stabilization using PPSs from Th9 to L2 and concomitant PTPIF using autologous iliac bone graft at T11-12 were performed. Low back pain and neurological symptoms were immediately improved after surgery. A solid interbody fusion at T11-12 was completed 9 months after surgery. The patient had no restriction of daily activity and could play golf at one year after surgery. PTPIF might be a useful option for perform segmental fusion in posterior stabilization using PPSs. PMID:27114777

  3. Percutaneous Transpedicular Interbody Fusion Technique in Percutaneous Pedicle Screw Stabilization for Pseudoarthrosis Following Pyogenic Spondylitis

    PubMed Central

    Masuda, Keigo; Yonekura, Yutaka; Kitamura, Takahiro; Senba, Hideyuki; Shidahara, Satoshi

    2016-01-01

    This report introduces a percutaneous transpedicular interbody fusion (PTPIF) technique in posterior stabilization using percutaneous pedicle screws (PPSs). An 81-year-old man presented with pseudoarthrosis following pyogenic spondylitis 15 months before. Although no relapse of infection was found, he complained of obstinate low back pain and mild neurological symptoms. Radiological evaluations showed a pseudoarthrosis following pyogenic spondylitis at T11–12. Posterior stabilization using PPSs from Th9 to L2 and concomitant PTPIF using autologous iliac bone graft at T11–12 were performed. Low back pain and neurological symptoms were immediately improved after surgery. A solid interbody fusion at T11–12 was completed 9 months after surgery. The patient had no restriction of daily activity and could play golf at one year after surgery. PTPIF might be a useful option for perform segmental fusion in posterior stabilization using PPSs. PMID:27114777

  4. Transpedicular Curettage and Drainage of Infective Lumbar Spondylodiscitis: Technique and Clinical Results

    PubMed Central

    Lee, Byung Ho; Lee, Hwan-Mo; Kim, Tae-Hwan; Kim, Hak-Sun; Moon, Eun-Soo; Park, Jin-Oh; Chong, Hyun-Soo

    2012-01-01

    Background Infective spondylodiscitis usually occurs in patients of older age, immunocompromisation, co-morbidity, and individuals suffering from an overall poor general condition unable to undergo reconstructive anterior and posterior surgeries. Therefore, an alternative, less aggressive surgical method is needed for these select cases of infective spondylodiscitis. This retrospective clinical case series reports our novel surgical technique for the treatment of infective spondylodiscitis. Methods Between January 2005 and July 2011, among 48 patients who were diagnosed with pyogenic lumbar spondylodiscitis or tuberculosis lumbar spondylodiscitis, 10 patients (7 males and 3 females; 68 years and 48 to 78 years, respectively) underwent transpedicular curettage and drainage. The mean postoperative follow-up period was 29 months (range, 7 to 61 months). The pedicle screws were inserted to the adjacent healthy vertebrae in the usual manner. After insertion of pedicle screws, the drainage pedicle holes were made through pedicles of infected vertebra(e) in order to prevent possible seeding of infective emboli to the healthy vertebra, as the same instruments and utensils are used for both pedicle screws and the drainage holes. A minimum of 15,000 mL of sterilized normal saline was used for continuous irrigation through the pedicular pathways until the drained fluid looked clear. Results All patients' symptoms and inflammatory markers significantly improved clinically between postoperative 2 weeks and postoperative 3 months, and they were satisfied with their clinical results. Radiologically, all patients reached the spontaneous fusion between infected vertebrae and 3 patients had the screw pulled-out but they were clinically tolerable. Conclusions We suggest that our method of transpedicular curettage and drainage is a useful technique in regards to the treatment of infectious spondylodiscitic patients, who could not tolerate conventional combined anterior and posterior

  5. Preliminary stabilisation of stormwater biofilters and loss of filter material.

    PubMed

    Subramaniam, D N; Mather, P B

    2016-01-01

    Stabilisation affects performance of stormwater biofilters operating under intermittent wetting and drying, mainly due to wash-off of filter material. Understanding the dynamics of solids wash-off is crucial in designing stormwater biofilters. The current study analysed the dynamics of solids wash-off in stormwater biofilters and quantified the loss of solids from the filter. Four Perspex™ bioretention columns (94 mm internal diameter) were fabricated with a filter layer that contained 8% organic material and were fed with tap water with different numbers of antecedent dry days (0-40 day) at 100 mL/min. Samples were collected from the outflow and tested for particle size distribution and total solids and turbidity. Solids of particle size less than 50 microns were washed off from the filter during the stabilisation period, indicating that no sand particles were washed off. The very first event after commissioning the filter resulted in the highest wash-off of solids (approximately 75 g of fines) while a significant drop in wash-off followed from the second event. An empirical model fitted to the data showed that preliminary stabilisation of a filter occurs in the first three events, during which almost 25% of fines are lost from the filter. PMID:27533853

  6. Enzymatically activated emulsions stabilised by interfacial nanofibre networks.

    PubMed

    Moreira, Inês P; Sasselli, Ivan Ramos; Cannon, Daniel A; Hughes, Meghan; Lamprou, Dimitrios A; Tuttle, Tell; Ulijn, Rein V

    2016-03-01

    We report on-demand formation of emulsions stabilised by interfacial nanoscale networks. These are formed through biocatalytic dephosphorylation and self-assembly of Fmoc(9-fluorenylmethoxycarbonyl)dipeptide amphiphiles in aqueous/organic mixtures. This is achieved by using alkaline phosphatase which transforms surfactant-like phosphorylated precursors into self-assembling aromatic peptide amphiphiles (Fmoc-tyrosine-leucine, Fmoc-YL) that form nanofibrous networks. In biphasic organic/aqueous systems, these networks form preferentially at the interface thus providing a means of emulsion stabilisation. We demonstrate on-demand emulsification by enzyme addition, even after storage of the biphasic mixture for several weeks. Experimental (Fluorescence, FTIR spectroscopy, fluorescence microscopy, electron microscopy, atomic force microscopy) and computational techniques (atomistic molecular dynamics) are used to characterise the interfacial self-assembly process. PMID:26905042

  7. Mean square stabilisation of complex oscillatory regimes in nonlinear stochastic systems

    NASA Astrophysics Data System (ADS)

    Bashkirtseva, Irina; Ryashko, Lev

    2016-04-01

    A problem of stabilisation of the randomly forced periodic and quasiperiodic modes for nonlinear dynamic systems is considered. For this problem solution, we propose a new theoretical approach to consider these modes as invariant manifolds of the stochastic differential equations with control. The aim of the control is to provide the exponential mean square (EMS) stability for these manifolds. A general method of the stabilisation based on the algebraic criterion of the EMS-stability is elaborated. A constructive technique for the design of the feedback regulators stabilising various types of oscillatory regimes is proposed. A detailed parametric analysis of the problem of the stabilisation for stochastically forced periodic and quasiperiodic modes is given. An illustrative example of stochastic Hopf system is included to demonstrate the effectiveness of the proposed technique.

  8. Reset stabilisation of positive linear systems

    NASA Astrophysics Data System (ADS)

    Zhao, Xudong; Yin, Yunfei; Shen, Jun

    2016-09-01

    In this paper, the problems of reset stabilisation for positive linear systems (PLSs) are investigated. Some properties relating to reset control of PLSs are first revealed. It is shown that these properties are different from the corresponding ones of general linear systems. Second, a class of periodic reset scheme is designed to exponentially stabilise an unstable PLS with a prescribed decay rate. Then, for a given PLS with reset control, some discussions on the upper bound of its decay rate are presented. Meanwhile, the reset stabilisation for PLSs in a special case is probed as well. Finally, two numerical examples are used to demonstrate the correctness and effectiveness of the obtained theoretical results.

  9. Low frequency dynamical stabilisation in optical tweezers

    NASA Astrophysics Data System (ADS)

    Richards, Christopher J.; Smart, Thomas J.; Jones, Philip H.; Cubero, David

    2015-08-01

    It is well known that a rigid pendulum with minimal friction will occupy a stable equilibrium position vertically upwards when its suspension point is oscillated at high frequency. The phenomenon of the inverted pendulum was explained by Kapitza by invoking a separation of timescales between the high frequency modulation and the much lower frequency pendulum motion, resulting in an effective potential with a minimum in the inverted position. We present here a study of a microscopic optical analogue of Kapitza's pendulum that operates in different regimes of both friction and driving frequency. The pendulum is realized using a microscopic particle held in a scanning optical tweezers and subject to a viscous drag force. The motion of the optical pendulum is recorded and analyzed by digital video microscopy and particle tracking to extract the trajectory and stable orientation of the particle. In these experiments we enter the regime of low driving frequency, where the period of driving is comparable to the characteristic relaxation time of the radial motion of the pendulum with finite stiffness. In this regime we find stabilization of the pendulum at angles other than the vertical (downwards) is possible for modulation amplitudes exceeding a threshold value where, unlike the truly high frequency case studied previously, both the threshold amplitude and equilibrium position are found to be functions of friction. Experimental results are complemented by an analytical theory for induced stability in the low frequency driving regime with friction.

  10. Longitudinal stabilisation of bunched beams in a FEL storage ring

    NASA Astrophysics Data System (ADS)

    Migliorati, M.; Palumbo, L.; Dattoli, G.; Mezi, L.; Renieri, A.; Voykov, G. K.

    1997-02-01

    Experimental observations on FEL Storage Rings (Aco, Super-Aco, VEPP3, TERAS) have shown that in a storage ring with an operating FEL there is a mutual effect between the FEL operational mode and the beam longitudinal distribution. The main effects are the birth of a macro-temporal structure of the FEL radiation and a suppression of the synchrotron sidebands, evidence of beam stabilisation against the microwave instabilities. In this paper we discuss the main features of the beam dynamics analysed with a simulation code recently developed, which includes the FEL-beam interaction. Furtherly, we propose an heuristic model which enable to describe in a simple way the overall system.

  11. Bioconjugation and stabilisation of biomolecules in biosensors.

    PubMed

    Liébana, Susana; Drago, Guido A

    2016-06-30

    Suitable bioconjugation strategies and stabilisation of biomolecules on electrodes is essential for the development of novel and commercially viable biosensors. In the present review, the functional groups that comprise the selectable targets for practical bioconjugation methods are discussed. We focus on describing the most common immobilisation techniques used in biosensor construction, which are classified into irreversible and reversible methods. Concerning the stability of proteins, the two main types of stability may be defined as (i) storage or shelf stability, and (ii) operational stability. Both types of stability are explained, as well as the introduction of an electrophoretic technique for predicting protein-polymer interactions. In addition, solution and dry stabilisation as well as stabilisation using the covalent immobilisation of proteins are discussed including possible factors that influence stability. Finally, the integration of nanomaterials, such as magnetic particles, with protein immobilisation is discussed in relation to protein stability studies. PMID:27365036

  12. Bioconjugation and stabilisation of biomolecules in biosensors

    PubMed Central

    Drago, Guido A.

    2016-01-01

    Suitable bioconjugation strategies and stabilisation of biomolecules on electrodes is essential for the development of novel and commercially viable biosensors. In the present review, the functional groups that comprise the selectable targets for practical bioconjugation methods are discussed. We focus on describing the most common immobilisation techniques used in biosensor construction, which are classified into irreversible and reversible methods. Concerning the stability of proteins, the two main types of stability may be defined as (i) storage or shelf stability, and (ii) operational stability. Both types of stability are explained, as well as the introduction of an electrophoretic technique for predicting protein–polymer interactions. In addition, solution and dry stabilisation as well as stabilisation using the covalent immobilisation of proteins are discussed including possible factors that influence stability. Finally, the integration of nanomaterials, such as magnetic particles, with protein immobilisation is discussed in relation to protein stability studies. PMID:27365036

  13. Finite-time stabilisation of simple mechanical systems using continuous feedback

    NASA Astrophysics Data System (ADS)

    Sanyal, Amit K.; Bohn, Jan

    2015-04-01

    Stabilisation of simple mechanical systems in finite time with continuous state feedback is considered here. The dynamics are represented by generalised (local) coordinates. A general methodology to construct control Lyapunov functions that are Hölder continuous and that can be used to show finite-time stability of the feedback controlled system, is presented. This construction also gives the feedback control law, and results in the feedback system being Hölder continuous as well. Unlike Lipschitz continuous feedback control systems, the feedback control scheme given here converges to the desired equilibrium in finite time. Moreover, unlike discontinuous and hybrid control schemes, the feedback control law does not lead to chattering in the presence of measurement noise, does not excite unmodelled high-frequency dynamics, and can be implemented with actuators that can only deliver continuous control inputs. The advantages of continuous finite-time stabilisation over continuous asymptotic stabilisation of mechanical systems, has been described in some prior research on finite-time stabilisation of the double integrator. The finite-time stabilisation scheme given here generalises this prior research to multiple degree-of-freedom mechanical systems. A numerical comparison is carried out through numerical simulations on two example systems that are representative of a broad class of simple mechanical systems.

  14. Lumbar Transpedicular Implant Failure: A Clinical and Surgical Challenge and Its Radiological Assessment

    PubMed Central

    Ali, Abdel Mohsen Arafa

    2014-01-01

    Study Design It is a multicenter, controlled case study review of a big scale of pedicle-screw procedures from January 2000 to June 2010. The outcomes were compared to those with no implant failure. Purpose The purpose of this study was to review retrospectively the outcome of 100 patients with implant failure in comparison to 100 control-patients, and to study the causes of failure and its prevention. Overview of Literature Transpedicular fixation is associated with risks of hardware failure, such as screw/rod breakage and/or loosening at the screw-rod interface and difficulties in the system assembly, which remain a significant clinical problem. Removal or revision of the spinal hardware is often required. Methods Two hundred patients (88 women, 112 men) were divided into 2 major groups, with 100 patients in group I (implant failure group G1) and 100 patients in group II (successful fusion, control group G2). We subdivided the study groups into two subgroups: subgroup a (single-level instrumented group) and subgroup b (multilevel instrumented group). The implant status was assessed based on intraoperative and follow-up radiographs. Results Implant failure in general was present in 36% in G1a, and in 64% in G1b, and types of implant failure included screw fracture (34%), rod fracture (24%), rod loosening (22%), screw loosening (16%), and failure of both rod and screw (4%). Most of the failures (90%) occurred within 6 months after surgery, with no reported cases 1 year postoperatively. Conclusions We tried to address the problem and study the causes of failure, and proposed solutions for its prevention. PMID:24967042

  15. Intraoperative Computed Tomography Navigation for Transpedicular Screw Fixation to Treat Unstable Thoracic and Lumbar Spine Fractures

    PubMed Central

    Lee, Ching-Yu; Wu, Meng-Huang; Li, Yen-Yao; Cheng, Chin-Chang; Hsu, Chu-Hsiang; Huang, Tsung-Jen; Hsu, Robert Wen-Wei

    2015-01-01

    Abstract Transpedicular screw (TPS) fixation in unstable thoracic and lumbar (TL) spine fractures remains technically difficult because of destroyed anatomical landmarks, unstable gross segments, and discrepancies in anatomic orientation using conventional anatomic landmarks, fluoroscopic guidance, or computed tomography (CT)-based navigation. In this study, we evaluated the safety and accuracy of TPS placement under intraoperative computed tomography (iCT) navigation in managing unstable TL spine fractures. From 2010 to 2013, we retrospectively reviewed the Spine Operation Registry records of patients who underwent posterior instrumented fusion to treat unstable TL spine fractures via the iCT navigation system. An unstable spine fracture was identified as AO/Magerl classification type B or type C. In all, 316 screws in 37 patients with unstable TL spine fractures were evaluated and involved 7 thoracic, 23 thoracolumbar junctional, and 7 lumbar fractures. The accuracy of TPS positioning in the pedicle without breach was 98% (310/316). The average number of iCT scans per patient was 2.1 (range 2–3). The average total radiation dose to patients was 15.8 mSv; the dose per single level exposure was 2.7 mSv. The TPS intraoperative revision rate was 0.6% (2/316) and no neurovascular sequela was observed. TPS fixation using the iCT navigation system obtained a 98% accuracy in stabilizing unstable TL spine fractures. A malplaced TPS could be revised during real-time confirmation of the TPS position, and no secondary operation was required to revise malplaced screws. The iCT navigation system provides accurate and safe management of unstable TL spine fractures. In addition, operating room personnel, including surgeons and nurses, did not need to wear heavy lead aprons as they were not exposed to radiation. PMID:25997042

  16. Partial stability and stabilisation of Boolean networks

    NASA Astrophysics Data System (ADS)

    Chen, Hong-Wei; Sun, Liang-Jie; Liu, Yang

    2016-07-01

    In this paper, we investigate the stability of Boolean networks and the stabilisation of Boolean control networks with respect to part of the system's states. First, an algebraic expression of the Boolean (control) network is derived by the semi-tensor product of matrices. Then, some necessary and sufficient conditions for partial stability of Boolean networks are given. Finally, the stabilisation of Boolean control networks by a free control sequence and a state-feedback control is investigated and the respective necessary and sufficient conditions are obtained. Examples are provided to illustrate the efficiency of the obtained results.

  17. Factors that affect stabilisation times of canine spontaneous hypoadrenocorticism.

    PubMed

    Roberts, E; Boden, L A; Ramsey, I K

    2016-07-23

    The objective of this retrospective study was to examine factors that may have affected the stabilisation times of 50 dogs with spontaneous hypoadrenocorticism that were being treated with fludrocortisone acetate, with particular emphasis on dosing frequency and the concurrent use of prednisolone. Stabilisation was defined as an absence of clinical signs with a sodium:potassium ratio >27:1 and both electrolyte concentrations within a laboratory reference range. It was found that the median time till stabilisation was three months. The frequency of fludrocortisone treatment (once, twice or changed from once to twice a day) had no effect on the stabilisation time. The two groups of dogs that were started and stabilised on once a day or twice a day dosing had a median stabilisation time of two months. However, dogs that failed to stabilise on once a day dosing of fludrocortisone and were then changed onto twice a day dosing then stabilised a median of one month later. Concurrent use of prednisolone resulted in significantly faster stabilisation times. It was concluded that dogs with hypoadrenocorticism should be continued on prednisolone therapy until they are stabilised. If a dog is failing to stabilise on once a day fludrocortisone acetate, a change to twice a day administration could be considered. PMID:27269282

  18. Effects of electron beam irradiation on the property behaviour of poly(ether-block-amide) blended with various stabilisers

    NASA Astrophysics Data System (ADS)

    Murray, Kieran A.; Kennedy, James E.; Barron, Valerie; McEvoy, Brian; Vrain, Olivier; Ryan, Damien; Cowman, Richard; Higginbotham, Clement L.

    2015-05-01

    Radiosterilisation can induce modifications and/or degradation to transpire in poly(ether-block-amide) (PEBA) following irradiation. The current investigation utilises combined synergistic mixtures of stabilisers to minimise these effects, by melt blending them with the PEBA material. Hindered amine stabilisers (HAS), primary antioxidants and secondary antioxidants were the stabilisers incorporate to reduce/eliminate the effects of 50 kGy electron beam irradiation dose on the material. Results were discussed by comparing the stabilising efficiency of mixtures on the PEBA material in contrast to the control sample. Dynamic frequency sweeps demonstrated the formation of crosslinks, where the degree of crosslinking was dependent on the combination of stabilisers mixed in the base material (PEBA). The storage modulus displayed that PEBA blended with Irganox 565 had very slight changes in contrast to all other samples following irradiation. However, since this sample is a phenol containing system, severe discolouration was observed in comparison to other samples due to the oxidation of the hindered phenol. Overall, this study provides compelling evidence that a combined synergistic mixture of Irganox 565 (multifunctional phenolic antioxidant) and Tinuvin 783 (hindered amide light stabiliser) with PEBA, resulted in the best radiation stability.

  19. Polycarboxylate ethers: The key towards non-toxic TiO2 nanoparticle stabilisation in physiological solutions.

    PubMed

    Koch, S; Kessler, M; Mandel, K; Dembski, S; Heuzé, K; Hackenberg, S

    2016-07-01

    Stable, non-agglomerated TiO2 nanoparticle (NP) dispersions are a crucial requirement for an accurate NP dosing in in vitro and in vivo experiments. In this study self-synthesised TiO2 NPs were stabilised in three different cell culture media (DMEM, RPMI, BEGM) with the help of stabilising agents. Cell culture tested stabilisers (bovine serum albumin, fetal bovine serum) were compared to non-tested commercial products which are commonly utilized in the cement industry (Melflux(®) 4930 F, Melpers(®) 4343, Sika(®) ViscoCrete(®)-10110178). For a quantitative evaluation and comparison of the degree of stabilisation, a sedimentation study using UV absorbance spectroscopy was carried out and the agglomerate size was measured via dynamic light scattering. The cytotoxicity of the novel surfactants and stabilised NPs was examined in a head and neck squamous cell carcinoma-derived FaDu cell line and in human mesenchymal stem cells. We successfully stabilised TiO2 NPs with Melflux(®) 4930 F in each cell culture medium, achieving perfect stability over at least one day and agglomerate sizes of less than 100nm, while the cytotoxicity of the NPs was not affected. PMID:26998862

  20. [The posterior lumbar interbody fusion with cages (PLIF) and transpedicular stabilization].

    PubMed

    Diedrich, O; Kraft, C N; Perlick, L; Schmitt, O

    2001-01-01

    The development of intervertebral cages has significantly innovated the original technique of posterior lumbar interbody fusion (PLIF). In this study we present the results of patients treated for degenerative or postoperative segmental spinal instabilities by PLIF with cages and pedicular stabilisation (360 degrees-instrumentation). Between 1992 and 1999 we implanted either CFRP-, PEEK- or Titanium-cages in 86 patients. 78 patients were adequately followed up over a period of at least 12 months (average 2,6 years). 5 patients were stabilised over 2 segments, so that ultimately 83 fused segments were evaluated.15% of all patients had an excellent, 51% a good, 28% a moderate and 5% an insufficient clinical result. Degenerative instabilities had a better outcome with 73% good or excellent clinical results, compared to postoperative instabilities (56%). Based on stringent radiographic fusion criteria we found true bony fusion in 52% of all segments after 12 months, 63% after 24 months, 72% after 36 months, and 78% after 48 months. In 21 segments cage packing was performed with autologous spongiosa, while in 62 segments a combination of cortical bone and spongiosa obtained from osseous structures at the operation-site were used as packing material. At the 24 month radiographic control we found a slightly higher fusion rate for those segments treated with autologous spongiosa obtained from the iliac crest. Neither for cages nor for pedicular screws was implant failure or material fatigue found. Serious entero-, pulmo-, cardio- or urological complications were not observed. Nonetheless the necessity for operative revision was 9%. A postoperative semiquantitative evaluation of segments neighbouring the fused vertebra revealed in 28% an increase in degenerative changes. Particularly after 360 degrees-instrumentation, interpretation of the fusion-status should be based on structural and not on functional criteria. The modification of PLIF with cages compared to the use of

  1. [Functional Outcome after Chest Wall Stabilisation].

    PubMed

    Kyriss, T; Lenz, U; Friedel, G

    2016-09-01

    This overview reviews the current literature to compare the functional results after surgical and conservative treatment of patients with flail chest and multiple rib fractures. Regarding functional aspects, patients in the early phase after a thoracic trauma are those that benefit most from the stabilisation of the chest wall by internal fixation of the ribs. Patients recover faster from restrictive respiratory disorders, have less pain and return to the workplace earlier after an operation compared with those that receive conservative treatment. In the medium term, however, patients that are treated conservatively also achieve normal pulmonary function values and become free of pain. The period of convalescence after blunt thoracic trauma is generally underestimated. Future studies of the functional outcome after severe chest injuries should take this into account and the development of functional parameters should be monitored for at least 24 months. A prospective data collection of early and long-term surgical results in registries would be suitable to evaluate benefits and indications of chest wall stabilisation. PMID:27607891

  2. Cocoa particles for food emulsion stabilisation.

    PubMed

    Gould, Joanne; Vieira, Josélio; Wolf, Bettina

    2013-09-01

    Emulsifying properties of cocoa particles have been investigated in systems containing purified sunflower oil (PSO) and water at varying pH, concentration and source of cocoa particles including cocoa powders (CP), cocoa fibre (CF) and cocoa mass (CM). The effect of cocoa particle source, pH and cocoa particle concentration on emulsion stability was evaluated by following changes in characteristic droplet diameter. Size distributions acquired on the emulsions and aqueous cocoa particle suspensions overlapped. Based on cryo-SEM imaging of the emulsions, isolation of cocoa particle fines and a process of washing the cocoa particles to remove any water soluble molecules, it was concluded that the cocoa particle fines not captured by the small angle laser diffraction method employed for sizing, act as Pickering particles. This research has demonstrated a universal nature of a natural food particle to stabilise oil-in-water emulsions not requiring particle modification or adjusting of the solution properties of the emulsion phases. PMID:23851644

  3. Foam stabilisation using surfactant exfoliated graphene.

    PubMed

    Sham, Alison Y W; Notley, Shannon M

    2016-05-01

    Liquid-air foams have been stabilised using a suspension of graphene particles at very low particle loadings. The suspension was prepared through the liquid phase exfoliation of graphite in the presence of the non-ionic tri-block surfactant, Pluronic® F108. The graphene particles possess an extremely high aspect ratio, with lateral dimensions of between 0.1 and 1.3 μm as evidenced by TEM imaging. The particles were shown to exhibit a number of other properties known to favour stabilisation of foam structures. Particle surface activity was confirmed through surface tension measurements, suggesting the particles favour adsorption at the air-water interface. The evolution of bubble size distributions over time indicated the presence of particles yielded improvements to foam stability due to a reduction in disproportionation. Foam stability measurements showed a non-linear relationship between foam half-life and graphene concentration, indicative of the rate at which particles adsorb at bubble surfaces. The wettability of the graphene particles was altered upon addition of alkali metal chlorides, with the stability of the foams being enhanced according to the series Na(+)>Li(+)>K(+)>Cs(+). This effect is indicative of the relative hydration capacity of each salt with respect to the surfactant, which is adsorbed along the graphene plane as a result of the exfoliation process. Thus, surfactant exfoliated graphene particles exhibit a number of different features that demonstrate efficient application of high-aspect ratio particles in the customisation and enhancement of foams. PMID:26890385

  4. Disc extrusion in a Rottweiler dog with caudal cervical spondylomyelopathy after failure of intervertebral distraction/stabilisation.

    PubMed

    Marchevsky, A M; Richardson, J L

    1999-05-01

    A Rottweiler dog was presented with an 8 week history of hindlimb ataxia. Neurological examination localised the lesion to the cervical spinal cord. Myelography demonstrated dynamic compressive lesions at C5-6 and C6-7 consistent with a diagnosis of caudal cervical spondylomyelopathy. Distraction/stabilisation of both discs was performed using interbody polymethyl methacrylate. Both implants subsequently failed leading to extrusion of the remaining dorsal annulus fibrosus of the C5-6 intervertebral disc and nonambulatory tetraparesis. A ventral slot combined with distraction/stabilisation using screws and polymethyl methacrylate was performed and resulted in nearly full neurological recovery. PMID:10376097

  5. One-Stage Posterior Debridement and Transpedicular Screw Fixation for Treating Monosegmental Thoracic and Lumbar Spinal Tuberculosis in Adults

    PubMed Central

    Liu, Zhili; Peng, Aifeng; Long, Xinhua; Yang, Dong; Huang, Shanhu

    2014-01-01

    Spinal tuberculosis is still prevalent in some developing countries. The purpose of this study is to investigate the efficacy and safety of one-stage posterior debridement, autogenous bone grafting, and transpedicular screw fixation in treating monosegmental thoracic and lumbar tuberculosis in adults. 37 patients were retrospectively reviewed in this study. The data of images, operative time and blood loss volume, perioperative complications, time to achieve bony fusion, VAS score, and neurologic function preoperatively and postoperatively were collected. The mean follow-up period was 21.5 ± 3.5 months. The tuberculosis was cured after surgery in all patients, and no recurrence was observed. Bony fusion was achieved in all patients with a mean time of 5.6 ± 2.5 months. Neurological outcome did not change in one case with grade A, and increased by 1–3 grades in the other patients with nerve deficit. The average preoperative and postoperative VAS scores were 5.5 ± 2.23 and 1.5 ± 1.22, respectively; the difference was significant (P < 0.05). There were three perioperative complications (8.1%, 3/37) observed in this study. In conclusion, the procedure of one-stage posterior debridement, interbody fusion with autogenous bone grafting, and posterior fixation with pedicle screw is effective and safe for treating monosegmental thoracic and lumbar spinal tuberculosis in adults. PMID:24701134

  6. Impact on Neurological Recovery of Transforaminal Debridement and Interbody Fusion versus Transpedicular Decompression in Combination with Pedicle Screw Instrumentation for Treating Thoracic and Lumbar Spinal Tuberculosis

    PubMed Central

    Choovongkomol, Kongtush; Piyapromdee, Urawit; Leownorasate, Manoon

    2016-01-01

    Study Design Retrospective study. Purpose To compare the neurological outcome of transforaminal debridement and interbody fusion with transpedicular decompression for treatment of thoracic and lumbar spinal tuberculosis. Overview of Literature Few articles have addressed the impact of neurological recovery in patients with tuberculosis who were treated by two different operative methods via the posterior-only approach. Methods Clinical and radiographic results of one-stage posterior instrumented spinal fusion for treatment of tuberculous spondylodiscitis with neurological deficits were reviewed and analyzed from 2009 to 2013. The extensive (E) group consisted of patients who received transforaminal debridement and interbody fusion, whereas transpedicular decompression was performed on limited (L) group. Rapid recovery was improvement of at least one Frankel grade within 6 weeks after operation. Otherwise, it was slow recovery. Results All 39 patients had improved neurological signs. The median follow-up period was 24 months. Proportionately younger patients (under 65 years of age) received extensive surgery (15 of 18, 83.3% vs. 11 of 21, 52.4%; p=0.04). The mean operative time and blood loss in the group E were higher than in the group L (both p<0.01). With regard to type of procedure, especially at thoracic and thoracolumbar spine, patients who underwent extensive surgery had rapid neurological recovery significantly different from those of limited surgery (p=0.01; Relative Risk, 3.06; 95% Confidence Interval, 1.13 to 8.29). Conclusions Transforaminal debridement and interbody fusion provides more rapid neurological recovery in patients with thoracic and thoracolumbar spinal tuberculosis compared to transpedicular decompression. PMID:27340536

  7. Interactions in lipid stabilised foam films.

    PubMed

    Toca-Herrera, José Luis; Krasteva, Nadejda; Müller, Hans-Joachim; Krastev, Rumen

    2014-05-01

    The interaction between lipid bilayers in water has been intensively studied over the last decades. Osmotic stress was applied to evaluate the forces between two approaching lipid bilayers in aqueous solution. The force-distance relation between lipid mono- or bilayers deposited on mica sheets using a surface force apparatus (SFA) was also measured. Lipid stabilised foam films offer another possibility to study the interactions between lipid monolayers. These films can be prepared comparatively easy with very good reproducibility. Foam films consist usually of two adsorbed surfactant monolayers separated by a layer of the aqueous solution from which the film is created. Their thickness can be conveniently measured using microinterferometric techniques. Studies with foam films deliver valuable information on the interactions between lipid membranes and especially their stability and permeability. Presenting inverse black lipid membrane (BLM) foam films supply information about the properties of the lipid self-organisation in bilayers. The present paper summarises results on microscopic lipid stabilised foam films by measuring their thickness and contact angle. Most of the presented results concern foam films prepared from dispersions of the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) and some of its mixtures with the anionic lipid -- 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG). The strength of the long range and short range forces between the lipid layers is discussed. The van der Waals attractive force is calculated. The electrostatic repulsive force is estimated from experiments at different electrolyte concentrations (NaCl, CaCl₂) or by modification of the electrostatic double layer surface potential by incorporating charged lipids in the lipid monolayers. The short range interactions are studied and modified by using small carbohydrates (fructose and sucrose), ethanol (EtOH) or dimethylsulfoxide (DMSO). Some

  8. Cellulose degradation in alkaline media upon acidic pretreatment and stabilisation.

    PubMed

    Testova, Lidia; Nieminen, Kaarlo; Penttilä, Paavo A; Serimaa, Ritva; Potthast, Antje; Sixta, Herbert

    2014-01-16

    The present study reports on a revised kinetic model for alkaline degradation of cellulose accounting for primary peeling/stopping reactions as well as for alkaline hydrolysis followed by secondary peeling. Oxalic acid pretreated cotton linters was utilised as the model substrate for the prehydrolysis-soda anthraquinone process. The main emphasis was investigating the effect of end-group stabilising additives such as sodium borohydride (BH), anthraquinone (AQ), and anthraquinone-2-sulphonic acid sodium salt (AQS) on the rates of the yield loss reactions. BH and AQS ensured a cellulose yield gain of 13% and 11%, respectively, compared to the reference. Both stabilisation agents decreased the content of the reducing end groups in the samples, while in the case of AQS stabilisation a 25% increase in carboxyl group content compared to the reference was also observed. As expected, the addition of end group stabilisers resulted in a significant decrease in the peeling-to-stopping rate constants ratio. PMID:24188853

  9. States of fragility: stabilisation and its implications for humanitarian action.

    PubMed

    Collinson, Sarah; Elhawary, Samir; Muggah, Robert

    2010-10-01

    This paper explores the evolution of international stabilisation agendas and their significance for humanitarian action. Stabilisation includes a combination of military, humanitarian, political and economic activities to control, contain and manage areas affected by armed conflict and complex emergencies. Encompassing narrow security objectives and broader peace-building efforts, stabilisation is both a conservative and potentially transformative, comprehensive and long-term agenda. The open-ended approach allows for widely varying interpretations and applications in different circumstances and by different actors with an assortment of implications for humanitarian action. The relationship between the two is highly uncertain and contentious, due not only to the controversies surrounding stabilisation policies, but also to deep-seated ambiguities at the heart of humanitarianism. While humanitarian actors are preoccupied with the growing involvement of the military in the humanitarian sphere, the paper argues that it is trends in the humanitarian-political interface that represent the more fundamental dilemma. PMID:20846346

  10. Finding a stabilising switching law for switching nonlinear models

    NASA Astrophysics Data System (ADS)

    Lendek, Zs.; Raica, P.; Lauber, J.; Guerra, T. M.

    2016-09-01

    This paper considers the stabilisation of switching nonlinear models by switching between the subsystems. We assume that arbitrary switching between two subsystems is possible once a subsystem has been active for a predefined number of samples. We use a Takagi-Sugeno representation of the models and a switching Lyapunov function is employed to develop sufficient stability conditions. If the conditions are satisfied, we construct a switching law that stabilises the system. The application of the conditions is illustrated in several examples.

  11. High-performance electronic image stabilisation for shift and rotation correction

    NASA Astrophysics Data System (ADS)

    Parker, Steve C. J.; Hickman, D. L.; Wu, F.

    2014-06-01

    A novel low size, weight and power (SWaP) video stabiliser called HALO™ is presented that uses a SoC to combine the high processing bandwidth of an FPGA, with the signal processing flexibility of a CPU. An image based architecture is presented that can adapt the tiling of frames to cope with changing scene dynamics. A real-time implementation is then discussed that can generate several hundred optical flow vectors per video frame, to accurately calculate the unwanted rigid body translation and rotation of camera shake. The performance of the HALO™ stabiliser is comprehensively benchmarked against the respected Deshaker 3.0 off-line stabiliser plugin to VirtualDub. Eight different videos are used for benchmarking, simulating: battlefield, surveillance, security and low-level flight applications in both visible and IR wavebands. The results show that HALO™ rivals the performance of Deshaker within its operating envelope. Furthermore, HALO™ may be easily reconfigured to adapt to changing operating conditions or requirements; and can be used to host other video processing functionality like image distortion correction, fusion and contrast enhancement.

  12. Hybrid Stabilization of Thoracic Spine Fractures with Sublaminar Bands and Transpedicular Screws: Description of a Surgical Alternative and Review of the Literature

    PubMed Central

    Unterweger, Marie-Therese; Kandziora, Frank; Schnake, Klaus J.

    2015-01-01

    Stabilization of unstable thoracic fractures with transpedicular screws is widely accepted. However, placement of transpedicular screws can cause complications, particularly in the thoracic spine with physiologically small pedicles. Hybrid stabilization, a combination of sublaminar bands and pedicle screws, might reduce the rate of misplaced screws and can be helpful in special anatomic circumstances, such as preexisting scoliosis and osteoporosis. We report about two patients suffering from unstable thoracic fractures, of T5 in one case and T3, T4, and T5 in the other case, with preexisting scoliosis and extremely small pedicles. Additionally, one patient had osteoporosis. Patients received hybrid stabilization with pedicle screws adjacent to the fractured vertebral bodies and sublaminar bands at the level above and below the pedicle screws. No complications occurred. Follow-up was 12 months with clinically uneventful postoperative courses. No signs of implant failure or loss of reduction could be detected. In patients with very small thoracic pedicles, scoliosis, and/or osteoporosis, hybrid stabilization with sublaminar bands and pedicle screws can be a viable alternative to long pedicle screw constructs. PMID:26649214

  13. Embolization by Direct Puncture with a Transpedicular Approach Using an Isocenter Puncture (ISOP) Method in a Patient with a Type II Endoleak After Endovascular Aortic Repair (EVAR)

    SciTech Connect

    Ogawa, Yukihisa Hamaguchi, Shingo; Nishimaki, Hiroshi; Kon, Yuri; Chiba, Kiyoshi; Sakurai, Yuka; Murakami, Kenji; Arai, Yasunori; Miyairi, Takeshi; Nakajima, Yasuo

    2015-06-15

    BackgroundEndovascular aortic repair (EVAR) requires further intervention in 20-30 % of cases, often due to type II endoleak (T2EL). Management options for T2EL include transarterial embolization, direct puncture (DP), or transcaval embolization. We report the case of an 80-year-old man with T2EL who successfully underwent DP embolization.MethodsEmbolization by DP was performed with a transpedicular approach using an isocenter puncture (ISOP) method. An isocenter marker (ICM) was placed at a site corresponding to the aneurysm sac on fluoroscopy in two directions (frontal and lateral views). A vertebroplasty needle was inserted tangentially to the ICM under fluoroscopy and advanced to the anterior wall of the vertebral body. A 20 cm-length, 20-G-PTCD needle was inserted through the outer needle of the 13-G needle and advanced to the ICM. Sac embolization using 25 % N-buty-2-cyanoacrylate diluted with Lipiodol was performed. After complete embolization, rotational DA confirmed good filling of the sac with Lipiodol. The outer cannula and 13-G needle were removed and the procedure was completed.ResultsThe patient was discharged the next day. Contrast-enhanced computed tomography 1 and 8 months later showed no Lipiodol washout in the aneurysm sac, no endoleak recurrence, and no expansion of the excluded aneurysm.ConclusionDP with a transpedicular approach using ISOP may be useful when translumbar and transabdominal approaches prove difficult.

  14. Computational mutagenesis reveals the role of active-site tyrosine in stabilising a boat conformation for the substrate: QM/MM molecular dynamics studies of wild-type and mutant xylanases.

    PubMed

    Soliman, Mahmoud E S; Ruggiero, Giuseppe D; Pernía, J Javier Ruiz; Greig, Ian R; Williams, Ian H

    2009-02-01

    Molecular dynamics simulations have been performed for non-covalent complexes of phenyl beta-xylobioside with the retaining endo-beta-1,4-xylanase from B. circulans (BCX) and its Tyr69Phe mutant using a hybrid QM/MM methodology. A trajectory initiated for the wild-type enzyme-substrate complex with the proximal xylose ring bound at the -1 subsite (adjacent to the scissile glycosidic bond) in the (4)C(1) chair conformation shows spontaneous transformation to the (2,5)B boat conformation, and potential of mean force calculations indicate that the boat is approximately 30 kJ mol(-1) lower in free energy than the chair. Analogous simulations for the mutant lacking one oxygen atom confirm the key role of Tyr69 in stabilizing the boat in preference to the (4)C(1) chair conformation, with a relative free energy difference of about 20 kJ mol(-1), by donating a hydrogen bond to the endocyclic oxygen of the proximal xylose ring. QM/MM MD simulations for phenyl beta-xyloside in water, with and without a propionate/propionic acid pair to mimic the catalytic glutamate/glutamic acid pair of the enzyme, show the (4)C(1) chair to be stable, although a hydrogen bond between the OH group at C2 of xylose and the propionate moiety seems to provide some stabilization for the (2,5)B conformation. PMID:19156310

  15. Lumbar Spinal Stenosis Minimally Invasive Treatment with Bilateral Transpedicular Facet Augmentation System

    SciTech Connect

    Masala, Salvatore; Tarantino, Umberto; Nano, Giovanni; Iundusi, Riccardo; Fiori, Roberto Da Ros, Valerio Simonetti, Giovanni

    2013-06-15

    Purpose. The purpose of this study was to evaluate the effectiveness of a new pedicle screw-based posterior dynamic stabilization device PDS Percudyn System Trade-Mark-Sign Anchor and Stabilizer (Interventional Spine Inc., Irvine, CA) as alternative minimally invasive treatment for patients with lumbar spine stenosis. Methods. Twenty-four consecutive patients (8 women, 16 men; mean age 61.8 yr) with lumbar spinal stenosis underwent implantation of the minimally invasive pedicle screw-based device for posterior dynamic stabilization. Inclusion criteria were lumbar stenosis without signs of instability, resistant to conservative treatment, and eligible to traditional surgical posterior decompression. Results. Twenty patients (83 %) progressively improved during the 1-year follow-up. Four (17 %) patients did not show any improvement and opted for surgical posterior decompression. For both responder and nonresponder patients, no device-related complications were reported. Conclusions. Minimally invasive PDS Percudyn System Trade-Mark-Sign has effectively improved the clinical setting of 83 % of highly selected patients treated, delaying the need for traditional surgical therapy.

  16. Stabilisation of a class of 2-DOF underactuated mechanical systems via direct Lyapunov approach

    NASA Astrophysics Data System (ADS)

    Turker, Turker; Gorgun, Haluk; Cansever, Galip

    2013-06-01

    This paper represents an alternative stabilisation procedure for a class of two degree-of-freedom underactuated mechanical systems based on a set of transformations and a Lyapunov function. After simplifying dynamic equations of the system via partial feedback linearisation and coordinate changes, the stability of the system is provided with Lyapunov's direct method. Proposed control scheme is used on two different examples and asymptotic convergence for each system is proven by means of La Salle's invariance principle. The designed controller is successfully illustrated through numerical simulations for each example.

  17. Experimental and theoretical investigation of oxygen diffusion in stabilised zirconia

    NASA Astrophysics Data System (ADS)

    Kilo, M.; Fundenberger, C.; Argirusis, C.; Taylor, M. A.; Borchardt, G.; Weller, M.; Jackson, R. A.

    Oxygen diffusion in stabilised zirconias is investigated by the simultaneous application of computer modelling and experimental techniques to yttria-stabilised zirconia. Using the Mott-Littleton method, migration pathways for oxygen ions have been calculated in perfect cubic zirconia. The oxygen migration occurs through a straight pathway, but not starting from the ideal lattice positions. The calculated activation energy of migration is about 0.2 eV. Oxygen transport is investigated experimentally in YSZ containing 8-24 mol% Y2O3 as a function of stabiliser content by combining the stable isotope (O-18(2)) method with ionic conductivity measurements. It was found that for a given temperature, diffusion and conductivity are highest for YSZ containing 8-10 mol% yttria, but with differing activation energies which can be compared to the calculated values.

  18. Treatment of acute thoracolumbar burst fractures with kyphoplasty and short pedicle screw fixation: Transpedicular intracorporeal grafting with calcium phosphate: A prospective study

    PubMed Central

    Korovessis, Panagiotis; Repantis, Thomas; George, Petsinis

    2007-01-01

    Background: In the surgical treatment of thoracolumbar fractures, the major problem after posterior correction and transpedicular instrumentation is failure to support the anterior spinal column, leading to loss of correction and instrumentation failure with associated complaints. We conducted this prospective study to evaluate the outcome of the treatment of acute thoracolumbar burst fractures by transpedicular balloon kyphoplasty, grafting with calcium phosphate cement and short pedicle screw fixation plus fusion. Materials and Methods: Twenty-three consecutive patients of thoracolumbar (T9 to L4) burst fracture with or without neurologic deficit with an average age of 43 years, were included in this prospective study. Twenty-one from the 23 patients had single burst fracture while the remaining two patients had a burst fracture and additionally an adjacent A1-type fracture. On admission six (26%) out of 23 patients had neurological deficit (five incomplete, one complete). Bilateral transpedicular balloon kyphoplasty with liquid calcium phosphate to reduce segmental kyphosis and restore vertebral body height and short (three vertebrae) pedicle screw instrumentation with posterolateral fusion was performed. Gardner kyphosis angle, anterior and posterior vertebral body height ratio and spinal canal encroachment were calculated pre- to postoperatively. Results: All 23 patients were operated within two days after admission and were followed for at least 12 months after index surgery. Operating time and blood loss averaged 45 min and 60 cc respectively. The five patients with incomplete neurological lesions improved by at least one ASIA grade, while no neurological deterioration was observed in any case. The VAS and SF-36 (Role physical and Bodily pain domains) were significantly improved postoperatively. Overall sagittal alignment was improved from an average preoperative 16° to one degree kyphosis at final followup observation. The anterior vertebral body height

  19. Feedback-bounded stabilisation of certain discrete Volterra systems

    NASA Astrophysics Data System (ADS)

    Kotsios, Stelios

    2016-06-01

    Throughout this paper, we present a method for designing feedback-laws which stabilise nonlinear discrete Volterra systems. Our method is based on a factorisation algorithm which decomposes the original system as a composition of a δ-polynomial and a linear series.

  20. Protein stabilisation using additives based on multiple electrostatic interactions.

    PubMed

    Gibson, T D

    1996-01-01

    A method of elevating the storage lifetime of purified proteins has been discovered which appears to confer stability to all proteins investigated and may therefore be classed as generic in action. The basic methodology involves the formation of multiple electrostatic complexes between the protein and selected soluble polyelectrolytes to give protein-polyelectrolyte (PP) complexes and then to add solutions of polyalcohols or other compounds containing multiple hydroxyl groups. Dehydration of the resulting solution by vacuum evaporation, freeze drying or forced air convection produces a dry film or powder of stabilised protein. The method has been used mainly in the preparation of active enzymes for analytical tests. It has also been found that the formation of PP complexes also enhances the stability of enzymes in solution and the technique may be applicable to the stabilisation of virus suspensions by polycations. Examples of stabilised enzymes prepared by these methods are given and the proposed mechanism of stabilisation and applicability of the method to shelf-stable vaccine products are discussed. PMID:8854019

  1. Cervical anterior transpedicular screw fixation (ATPS)--Part II. Accuracy of manual insertion and pull-out strength of ATPS.

    PubMed

    Koller, Heiko; Acosta, Frank; Tauber, Mark; Fox, Michael; Martin, Hudelmaier; Forstner, Rosmarie; Augat, Peter; Penzkofer, Rainer; Pirich, Christian; Kässmann, H; Resch, Herbert; Hitzl, Wolfgang

    2008-04-01

    Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications in a previous study in Part I of our project. Consequently, the objectives of the current study were to assess the ex vivo accuracy of placing ATPS into the cervical vertebra as well as the biomechanical performance of ATPS in comparison to traditional vertebral body screws (VBS) in terms of pull-out strength (POS). Twenty-three ATPS were inserted alternately to two screws into the pedicles and vertebral bodies, respectively, of six cadaveric specimens from C3-T1. For insertion of ATPS, a manual fluoroscopically assisted technique was used. Pre- and post insertional CT-scans were used to assess accuracy of ATPS insertion in the axial and sagittal planes. A newly designed grading system and accuracy score were used to delineate accuracy of ATPS insertion. Following insertion of screws, 23 ATPS and 22 VBS were subjected to pull-out testing (POT). The bone mineral density (BMD) of each specimen was assessed prior to POT. Statistical analysis showed that the incidence of correctly placed screws and non-critical pedicles breaches in axial plane was 78.3%, and 95.7% in sagittal plane. Hence, according to our definition of "critical" pedicle breach that exposes neurovascular structures at risk, 21.7% (n = 5) of all ATPS inserted showed a critical pedicle breach in axial plane. Notably, no critical pedicle perforation occurred at the C6 to T1 levels. Pull-out testing of ATPS and VBS revealed that pull-out resistance of ATPS was 2.5-fold that of VBS. Mean POS of 23 ATPS with a mean BMD of 0.566 g/cm(2

  2. Food-grade Pickering emulsions stabilised with solid lipid particles.

    PubMed

    Pawlik, Aleksandra; Kurukji, Daniel; Norton, Ian; Spyropoulos, Fotis

    2016-06-15

    Aqueous dispersions of tripalmitin particles (with a minimum size of 130 nm) were produced, via a hot sonication method, with and without the addition of food-grade emulsifiers. Depending on their relative size and chemistry, the emulsifiers altered the properties of the fat particles (e.g. crystal form, dispersion state and surface properties) by two proposed mechanisms. Firstly, emulsifiers modify the rate and/or extent of polymorphic transitions, resulting in the formation of fat crystals with a range of polarities. Secondly, the adsorption of emulsifiers at the particle interface modifies crystal surface properties. Such emulsifier-modified fat particles were then used to stabilise emulsions. As the behaviour of these particles was predisposed by the kind of emulsifier employed for their manufacture, the resulting particles showed different preferences to which of the emulsion phases (oil or water) became the continuous one. The polarity of the fat particles decreased as follows: Whey Protein Isolate > Soy Lecithin > Soy Lecithin + Tween 20 > Tween 20 > Polyglycerol Polyricinoleate > no emulsifier. Consequently, particles stabilised with WPI formed oil-in-water emulsions (O/W); particles stabilised solely with lecithin produced a highly unstable W/O emulsion; and particles stabilised with a mixture of lecithin and Tween 20 gave a stable W/O emulsion with drop size up to 30 μm. Coalescence stable, oil-continuous emulsions (W/O) with drop sizes between 5 and 15 μm were produced when the tripalmitin particles were stabilised with solely with Tween 20, solely with polyglycerol polyricinoleate, or with no emulsifier at all. It is proposed that the stability of the latter three emulsions was additionally enhanced by sintering of fat particles at the oil-water interface, providing a mechanical barrier against coalescence. PMID:27198879

  3. A new methodology for studying nanoparticle interactions in biological systems: Dispersing titania in biocompatible media using chemical stabilisers

    NASA Astrophysics Data System (ADS)

    Ramirez-Garcia, Sonia; Chen, Lan; Morris, Michael A.; Dawson, Kenneth A.

    2011-11-01

    We report here a highly successful and original protocol for the dispersion of nanoparticles in biocompatible fluids for in vitro and in vivo studies of the nanoparticle-biology interaction. Titania is chosen as a suitable model as it is one of the priority materials listed by the OECD and small particles of the anatase structure are extensively used as e.g. photocatalysts in solar cells. Consequently, its delivery into the environment and its interaction with biological organisms is unavoidable. Therefore, its biological effect needs to be understood. In this work, we prepared stable nanoparticle dispersions of anatase aggregates using citrate stabilisations between 45 and 55 nm at concentrations of up to 10 mg mL-1. The optimum pH for this type of suspension was 7, resulting in ζ-potentials of approximately -50 mV. The stabilised aggregates were the subject of dialysis to produce stable dispersions without the chemical stabiliser, thus allowing studies in the absence of potentially toxic chemicals. Different sizing techniques such as Dynamic Light Scattering (DLS), Nanoparticle Tracking Analysis (NTA) and Differential Centrifuge Sedimentation (DCS) were used to characterise the different suspensions. The results obtained with each of these techniques are compared and a critical analysis of the suitability of each technique is given.We report here a highly successful and original protocol for the dispersion of nanoparticles in biocompatible fluids for in vitro and in vivo studies of the nanoparticle-biology interaction. Titania is chosen as a suitable model as it is one of the priority materials listed by the OECD and small particles of the anatase structure are extensively used as e.g. photocatalysts in solar cells. Consequently, its delivery into the environment and its interaction with biological organisms is unavoidable. Therefore, its biological effect needs to be understood. In this work, we prepared stable nanoparticle dispersions of anatase aggregates

  4. Enlargement of Neural Foramina and Dynamic Stabilization in Spondylolisthesis without Restoring the Alignment: Technical Note

    PubMed Central

    Suzer, Tuncer; Sasani, Mehdi; Oktenoglu, Tunc; Egemen, Emrah

    2016-01-01

    It is well known that the cause of radiculopathy is the compression of the nerve root within the foramina which is narrowed secondary to sliding of the corpus and reduced disc height. In some patients, unroofing the foramen does not resolve this problem. We described a new decompression technique using pedicle removal and transpedicular dynamic instrumentation to stabilization the spine. We performed this operation in 2 patients and achieved very good results. PMID:27123030

  5. Use of Reinforced Lightweight Clay Aggregates for Landslide Stabilisation

    SciTech Connect

    Herle, Vitezslav

    2008-07-08

    In spring 2006 a large landslide combined with rock fall closed a highway tunnel near Svitavy in NE part of Czech Republic and cut the main highway connecting Bohemia with Moravia regions. Stabilisation work was complicated by steep mountainous terrain and large inflow of surface and underground water. The solution was based on formation of a stabilisation fill made of reinforced free draining aggregates at the toe of the slope with overlying lightweight fill up to 10 m high reinforced with PET geogrid and steel mesh protecting soft easily degrading sandstone against weathering. Extensive monitoring made possible to compare the FEM analysis with real values. The finished work fits very well in the environment and was awarded a special prize in the 2007 transport structures contest.

  6. Gas gain stabilisation in the ATLAS TRT detector

    NASA Astrophysics Data System (ADS)

    Mindur, B.; Åkesson, T. P. A.; Anghinolfi, F.; Antonov, A.; Arslan, O.; Baker, O. K.; Banas, E.; Bault, C.; Beddall, A. J.; Bendotti, J.; Benjamin, D. P.; Bertelsen, H.; Bingul, A.; Bocci, A.; Boldyrev, A. S.; Brock, I.; Capeáns Garrido, M.; Catinaccio, A.; Celebi, E.; Cetin, S. A.; Choi, K.; Dam, M.; Danielsson, H.; Davis, D.; Degeorge, C.; Derendarz, D.; Desch, K.; Di Girolamo, B.; Dittus, F.; Dixon, N.; Dressnandt, N.; Dubinin, F. A.; Evans, H.; Farthouat, P.; Fedin, O. L.; Froidevaux, D.; Gavrilenko, I. L.; Gay, C.; Gecse, Z.; Godlewski, J.; Grefe, C.; Gurbuz, S.; Hajduk, Z.; Hance, M.; Haney, B.; Hansen, J. B.; Hansen, P. H.; Hawkins, A. D.; Heim, S.; Holway, K.; Kantserov, V. A.; Katounine, S.; Kayumov, F.; Keener, P. T.; Kisielewski, B.; Klopov, N. V.; Konovalov, S. P.; Koperny, S.; Korotkova, N. A.; Kowalski, T. Z.; Kramarenko, V.; Krasnopevtsev, D.; Kruse, M.; Kudin, L. G.; Lichard, P.; Loginov, A.; Martinez, N. Lorenzo; Lucotte, A.; Luehring, F.; Lytken, E.; Maleev, V. P.; Maevskiy, A. S.; Manjarres Ramos, J.; Mashinistov, R. Y.; Meyer, C.; Mialkovski, V.; Mistry, K.; Mitsou, V. A.; Nadtochi, A. V.; Newcomer, F. M.; Novodvorski, E. G.; Ogren, H.; Oh, S. H.; Oleshko, S. B.; Olszowska, J.; Ostrowicz, W.; Palacino, G.; Patrichev, S.; Penwell, J.; Perez-Gomez, F.; Peshekhonov, V. D.; RØhne, O.; Reilly, M. B.; Rembser, C.; Ricken, O.; Romaniouk, A.; Rousseau, D.; Ryjov, V.; Sasmaz, U.; Schaepe, S.; Schegelsky, V. A.; Shmeleva, A. P.; Shulga, E.; Sivoklokov, S.; Smirnov, S.; Smirnov, Yu.; Smirnova, L. N.; Soldatov, E.; Sulin, V. V.; Tartarelli, G.; Taylor, W.; Thomson, E.; Tikhomirov, V. O.; Tipton, P.; Valls Ferrer, J. A.; Van Berg, R.; Vasquez, J.; Vasilyeva, L. F.; Vlazlo, O.; Weinert, B.; Williams, H. H.; Wong, V.; Zhukov, K. I.; Zieminska, D.

    2016-04-01

    The ATLAS (one of two general purpose detectors at the LHC) Transition Radiation Tracker (TRT) is the outermost of the three tracking subsystems of the ATLAS Inner Detector. It is a large straw-based detector and contains about 350,000 electronics channels. The performance of the TRT as tracking and particularly particle identification detector strongly depends on stability of the operation parameters with most important parameter being the gas gain which must be kept constant across the detector volume. The gas gain in the straws can vary significantly with atmospheric pressure, temperature, and gas mixture composition changes. This paper presents a concept of the gas gain stabilisation in the TRT and describes in detail the Gas Gain Stabilisation System (GGSS) integrated into the Detector Control System (DCS). Operation stability of the GGSS during Run-1 is demonstrated.

  7. The role of particles in stabilising foams and emulsions.

    PubMed

    Hunter, Timothy N; Pugh, Robert J; Franks, George V; Jameson, Graeme J

    2008-03-18

    The use of particles as foam and emulsion stabilising species, with or without surfactants, has received great interest in recent years. The majority of work has studied the effects of particles as stabilisers in emulsion systems, but recent successes has widened consideration into foams, where industries such as flotation and food processing have encountered the effects of particle stabilisation for many years. This review seeks to clarify studies into emulsions, highlighting new research in this area, and relate similarities and differences to foam systems. Past research has focused on defining the interaction mechanisms of stability, such as principles of attachment energies, particle-particle forces at the interface and changes to the interfilm, with a view to ascertain conditions giving optimum stability. Studied conditions include effects of particle contact angle, aggregation formations, concentration, size and interactions of other species (i.e. surfactant). Mechanisms can be complex, but overall the principle of particles creating a steric barrier to coalescence, is a straitforward basis of interaction. Much research in emulsions can be applied to foam systems, however evidence would suggest foam systems are under a number of additional constraints, and the stability 'window' for particles is smaller, in terms of size and contact angle ranges. Also, because of increased density differences and interfilm perturbations in foam systems, retardation of drainage is often as important to stability as inhibiting coalescence. PMID:17904510

  8. Security for whom? Stabilisation and civilian protection in Colombia.

    PubMed

    Elhawary, Samir

    2010-10-01

    This paper focuses on three periods of stabilisation in Colombia: the Alliance for Progress (1961-73) that sought to stem the threat of communist revolution in Latin America; Plan Colombia and President Alvaro Uribe's 'democratic security' policy (2000-07) aimed at defeating the guerrillas and negotiating a settlement with the paramilitaries; and the current 'integrated approach', adopted from 2007, to consolidate more effectively the state's control of its territory.(1) The paper assesses the extent to which these stabilisation efforts have enhanced the protection of civilians and ultimately finds that in all three periods there has been a disconnect between the discourse and the practice of stabilisation. While they have all sought to enhance security, in actual fact, they have privileged the security of the state and its allies at the expense of the effective protection of the civilian population. This has not only led to widespread human rights abuses but also has undermined the long-term stability being pursued. PMID:20846351

  9. Deformation and stabilisation mechanisms of slow rock slides in crystalline bedrock

    NASA Astrophysics Data System (ADS)

    Zangerl, C.; Prager, C.

    2009-04-01

    Deep-seated rock slides are slope instabilities which are characterised by deformation along one or several shear zones where most of the measured total slope displacement localizes. Generally, a high danger potential is given when rock slides fail in a rapid manner characterised by very high sliding velocities and/or when they develop into long run-out rock avalanches. However several field surveys and deformation monitoring data show that numerous deep-seated rock slides do not fail in a high velocity regime. In fact, many slides creep downwards at rates of some centimetres per year or even less and do not show any evidence for non-reversible acceleration in the past or in the future. Furthermore some of these slope instabilities are actually inactive (dormant) or have even reached a stabilised final state. Deformation monitoring on active rock slides show that acceleration phases characterised by velocities up to meters per day can occur. The trigger for these phases can be manifold and include heavy rainfall, snow melt, water level fluctuations of reservoirs at the slope foot, changes in the slope's equilibrium state due to antecedent slow creeping processes, changes in the material behaviour within the sliding zone, erosion along the foot of the slope, etc. Whereas the role of these triggers in promoting phases of acceleration are generally understood, the same can not be said regarding the kinematics and dynamic processes/mechanisms by which rock slide masses re-stabilise once the trigger impetus has been removed. In the context of this study the term "stabilisation" is used for rock slides which decelerate from high velocities to slow base activities or even stop moving after a certain amount of displacement. Given that reliable rock slide forecasts require the fundamental understanding of possible slope stabilisation mechanisms this study focuses on field-based and numerically obtained key-properties which influence the long-term slope deformation behaviour

  10. Oil-in-oil emulsions stabilised solely by solid particles.

    PubMed

    Binks, Bernard P; Tyowua, Andrew T

    2016-01-21

    A brief review of the stabilisation of emulsions of two immiscible oils is given. We then describe the use of fumed silica particles coated with either hydrocarbon or fluorocarbon groups in acting as sole stabilisers of emulsions of various vegetable oils with linear silicone oils (PDMS) of different viscosity. Transitional phase inversion of emulsions, containing equal volumes of the two oils, from silicone-in-vegetable (S/V) to vegetable-in-silicone (V/S) occurs upon increasing the hydrophobicity of the particles. Close to inversion, emulsions are stable to coalescence and gravity-induced separation for at least one year. Increasing the viscosity of the silicone oil enables stable S/V emulsions to be prepared even with relatively hydrophilic particles. Predictions of emulsion type from calculated contact angles of a silica particle at the oil-oil interface are in agreement with experiment provided a small polar contribution to the surface energy of the oils is included. We also show that stable multiple emulsions of V/S/V can be prepared in a two-step procedure using two particle types of different hydrophobicity. At fixed particle concentration, catastrophic phase inversion of emulsions from V/S to S/V can be effected by increasing the volume fraction of vegetable oil. Finally, in the case of sunflower oil + 20 cS PDMS, the study is extended to particles other than silica which differ in chemical type, particle size and particle shape. Consistent with the above findings, we find that only sufficiently hydrophobic particles (clay, zinc oxide, silicone, calcium carbonate) can act as efficient V/S emulsion stabilisers. PMID:26549699

  11. Viscoelastic properties of sterically stabilised emulsions and their stability.

    PubMed

    Tadros, Tharwat

    2015-08-01

    The interaction forces between emulsion droplets containing adsorbed polymeric surfactants and the theory of steric stabilisation are briefly described. The results for the viscoelastic properties of O/W emulsions that are stabilised with partially hydrolysed poly(vinyl acetate) that is commonly referred to as poly(vinyl alcohol) (PVA) with 4% vinyl acetate are given. The effect of the oil volume fraction, addition of electrolytes and increasing temperature is described. This allows one to obtain various parameters such as the adsorbed layer thickness, the critical flocculation concentration of electrolyte (CFC) and critical flocculation temperature (CFT) at constant electrolyte concentration. The viscoelastic properties of O/W emulsions stabilised with an A-B-A block copolymer of polyethylene oxide (A) and polypropylene oxide (B) are described. These emulsions behave as viscoelastic liquids showing a cross-over-point between G' (the elastic component of the complex modulus) and G″ (the viscous component of the complex modulus) at a characteristic frequency. Plots of G' and G″ versus oil volume fraction ϕ show the transition from predominantly viscous to predominantly elastic response at a critical volume fraction ϕ(c). The latter can be used to estimate the adsorbed layer thickness of the polymeric surfactants. Results are also shown for W/O emulsions stabilised with an A-B-A block copolymer of polyhydroxystearic acid (PHS, A) and polyethylene oxide (PEO, B). The viscosity volume fraction curves could be fitted to the Dougherty-Krieger equation for hard-spheres. The results could be applied to give an estimate of the adsorbed layer thickness Δ which shows a decrease with increase of the water volume fraction. This is due to the interpenetration and/or compression of the PHS layers on close approach of the water droplets on increasing the water volume fraction. The last section of the review gives an example of O/W emulsion stability using an AB(n) graft

  12. Stabilised electromagnetic levitation at 2-13 MHz

    NASA Technical Reports Server (NTRS)

    Danley, T. J.; Schiffman, R. A.; Weber, J. K. R.; Krishnan, S.; Rey, C. A.; Bruno, P. A.; Nordine, P. C.

    1991-01-01

    SEL, the Stabilised Electromagnetic Levitator, has been developed to exploit the unique design opportunities available in containerless microgravity experiments. Efficiency and versatility are obtained with multiple coils driven by individual broadband amplifiers whose phase and frequency are controlled. The heating and positioning fields are decoupled. Specimen translation, spin, and for liquids, shape may be adjusted. An open coil structure provides access for optical and diagnostic probes. Results of experiments with a prototype device are discussed. Levitating and heating materials on earth were demonstrated at frequencies up to 13 MHz.

  13. Compact atomic clocks and stabilised laser for space applications

    NASA Astrophysics Data System (ADS)

    Mileti, Gaetano; Affolderbach, Christoph; Matthey-de-l'Endroit, Renaud

    2016-07-01

    We present our developments towards next generation compact vapour-cell based atomic frequency standards using a tunable laser diode instead of a traditional discharge lamp. The realisation of two types of Rubidium clocks addressing specific applications is in progress: high performance frequency standards for demanding applications such as satellite navigation, and chip-scale atomic clocks, allowing further miniaturisation of the system. The stabilised laser source constitutes the main technological novelty of these new standards, allowing a more efficient preparation and interrogation of the atoms and hence an improvement of the clock performances. However, before this key component may be employed in a commercial and ultimately in a space-qualified instrument, further studies are necessary to demonstrate their suitability, in particular concerning their reliability and long-term operation. The talk will present our preliminary investigations on this subject. The stabilised laser diode technology developed for our atomic clocks has several other applications on ground and in space. We will conclude our talk by illustrating this for the example of a recently completed ESA project on a 1.6 microns wavelength reference for a future space-borne Lidar. This source is based on a Rubidium vapour cell providing the necessary stability and accuracy, while a second harmonic generator and a compact optical comb generated from an electro-optic modulator allow to transfer these properties from the Rubidium wavelength (780nm) to the desired spectral range.

  14. Ultrasonic cell disruption of stabilised sludge with subsequent anaerobic digestion.

    PubMed

    Onyeche, T I; Schläfer, O; Bormann, H; Schröder, C; Sievers, M

    2002-05-01

    The world-wide increasing environmental awareness and its subsequent regulations have led to the application of improved technologies in wastewater purification plants. This has resulted in higher wastewater and sludge productions. Sludge is the by-product of such plants and it is not only rich in organic carbon and pathogens but also in heavy metals and other environmental pollutants. In Europe, agricultural application of dried sludge (bio-solids) is confronted with negative reactions from the citizens, governmental organisations, farmers and the food industry. Ultrasonic disruption of sludge is a popular mechanical disruption process in sludge treatment. During ultrasonic treatment, high frequency acoustic signals are used to initiate the cavitation process. The applied ultrasonic field leads to a breakdown of cohesive forces of the liquid molecules resulting in the generation of cavitation bubbles. A shock wave is released by the collapse of the cavitation bubbles and propagates in the surrounding medium forming jet streams that cause the disruption of cells in sludge. Disruption of sludge cells enables the release of light organic substances into the sludge water thereby exposing them for further anaerobic digestion. This paper presents results on the disruption of conventionally stabilised sludge through the application of the ultrasonic field. In order to reduce the specific energy input (i.e. ratio of the consumed energy during ultrasonic disruption to the input sludge mass) and improve biogas production, the total solids content of the stabilised sludge was increased before disruption. The anaerobic digestion of sludge samples was carried out in a set of specially constructed laboratory anaerobic digesters. Results showed that subsequent anaerobic digestion of the ultrasonically disrupted sludge could improve biogas production with reduced sludge quantity that is vital to the economic consideration of the wastewater treatment plants. This process

  15. Steady-state droplet size in montmorillonite stabilised emulsions.

    PubMed

    Ganley, William J; van Duijneveldt, Jeroen S

    2016-08-14

    The formation of hexadecane-in-water emulsions stabilised by montmorillonite platelets was studied. In this system the platelets form a monolayer around the droplets and the droplet size decreases with increasing platelet volume fraction. However, the number of platelets present exceeds that required for monolayer coverage. The kinetics of emulsification were investigated and coalescence of droplets during turbulent mixing was found to continue even after the droplets had reached their ultimate size. Non-spherical droplets, resulting from arrested coalescence, were not observed suggesting that particles may be desorbing from the interface during the turbulent flow. A kinetic model based on a competition between droplet break-up and coalescence, mediated by particle adsorption and desorption, reproduces experimental trends in droplet diameter. The model can be used to predict the most efficient formulation to minimise droplet diameters for given materials and mixing conditions and sheds light on the processes occurring during emulsification in this system. PMID:27407026

  16. Ammonia volatilisation in waste stabilisation ponds: a cascade of misinterpretations?

    PubMed

    Camargo Valero, M A; Mara, D D

    2010-01-01

    Ammonia volatilisation has generally been reported as, or assumed to be, the main nitrogen removal mechanism in waste stabilisation ponds (WSP). Nitrogen removal via ammonia volatilisation is based on two observations: (a) in-pond pH values can reach high values (>9, even >10), so increasing the proportion of the total ammonia present as the un-ionized form or free ammonia (NH(3)); and (b) in-pond temperatures can also be high, so improving the mass transfer rate of free ammonia to the atmosphere. Consequently, one of the most widely accepted models for ammonia removal in WSP is that reported by Pano & Middlebrooks in 1982, which was developed to reflect the occurrence of these two observations. This work reports how simple mathematical models for ammonia volatilisation in WSP, in spite of the possibility of their giving good predictions, may not accurately describe the main pathways and mechanisms involved in ammonia removal in WSP. PMID:20150690

  17. Stabilising compensators for linear time-varying differential systems

    NASA Astrophysics Data System (ADS)

    Oberst, Ulrich

    2016-04-01

    In this paper, we describe a constructive test to decide whether a given linear time-varying (LTV) differential system admits a stabilising compensator for the control tasks of tracking, disturbance rejection or model matching and construct and parametrise all of them if at least one exists. In analogy to the linear time-invariant (LTI) case, the ring of stable rational functions, noncommutative in the LTV situation, and the Kučera-Youla parametrisation play prominent parts in the theory. We transfer Blumthaler's thesis from the LTI to the LTV case and sharpen, complete and simplify the corresponding results in the book 'Linear Time-Varying Systems' by Bourlès and Marinescu.

  18. Robust transient stabilisation problem for a synchronous generator in a power network

    NASA Astrophysics Data System (ADS)

    Verrelli, C. M.; Damm, G.

    2010-04-01

    The robust transient stabilisation problem (with stability proof€) of a synchronous generator in an uncertain power network with transfer conductances is rigorously formulated and solved. The generator angular speed and electrical power are required to be kept close, when mechanical and electrical perturbations occur, to the synchronous speed and mechanical input power, respectively, while the generator terminal voltage is to be regulated, when perturbations are removed, to its pre-fault reference constant value. A robust adaptive nonlinear feedback control algorithm is designed on the basis of a third-order model of the synchronous machine: only two system parameters (synchronous machine damping and inertia constants) along with upper and lower bounds on the remaining uncertain ones are supposed to be known. The conditions to be satisfied by the remote network dynamics for guaranteeing ℒ2 and ℒ∞ robustness and asymptotic relative speed and voltage regulation to zero are weaker than those required by the single machine-infinite bus approximation: dynamic interactions between the local deviations of the generator states from the corresponding equilibrium values and the remote generators states are allowed.

  19. Recycling vs. stabilisation of soil sugars - a long-term laboratory incubation experiment

    NASA Astrophysics Data System (ADS)

    Basler, A.; Dippold, M.; Helfrich, M.; Dyckmans, J.

    2015-06-01

    Independent of its chemical structure carbon (C) persists in soil for several decades, controlled by stabilisation and recycling. To disentangle the importance of the two factors on the turnover dynamics of soil sugars, an important compound of soil organic matter (SOM), a three year incubation experiment was conducted on a silty loam soil under different types of land use (arable land, grassland and forest) by adding 13C-labeled glucose. The compound specific isotope analysis of soil sugars was used to examine the dynamics of different sugars during incubation. Sugar dynamics were dominated by a pool of high mean residence times (MRT) indicating that recycling plays an important role for sugars. However, this was not substantially affected by soil C content. Six months after label addition the contribution of the label was much higher for microbial biomass than for CO2 production for all examined soils, corroborating that substrate recycling was very effective within the microbial biomass. Two different patterns of tracer dynamics could be identified for different sugars: while fucose (fuc) and mannose (man) showed highest label contribution at the beginning of the incubation with a subsequent slow decline, galactose (gal) and rhamnose (rha) were characterised by slow label incorporation with subsequently constant levels, which indicates that recycling is dominating the dynamics of these sugars. This may correspond to (a) different microbial growing strategies (r and K-strategist) or (b) location within or outside the cell membrane (lipopolysaccharides vs. exopolysaccharides) and thus be subject of different re-use within the microbial food web. Our results show how the microbial community recycles substrate very effectively and that high losses of substrate only occur during initial stages after substrate addition.

  20. State-feedback stabilisation for stochastic non-holonomic mobile robots with uncertain visual servoing parameters

    NASA Astrophysics Data System (ADS)

    Zhang, Dongkai; Wang, Chaoli; Wei, Guoliang; Zhang, Hengjun; Chen, Hua

    2014-07-01

    The stabilising problem of stochastic non-holonomic mobile robots with uncertain parameters based on visual servoing is addressed in this paper. The model of non-holonomic mobile robots based on visual servoing is extended to the stochastic case, where their forward velocity and angular velocity are both subject to some stochastic disturbances. Based on backstepping technique, state-feedback stabilising controllers are designed for stochastic non-holonomic mobile robots. A switching control strategy for the original system is presented. The proposed controllers guarantee that the closed-loop system is asymptotically stabilised at the zero equilibrium point in probability.

  1. CT Morphometric Analysis to Determine the Anatomical Basis for the Use of Transpedicular Screws during Reconstruction and Fixations of Anterior Cervical Vertebrae

    PubMed Central

    Chen, Chun; Ruan, Dike; Wu, Changfu; Wu, Weidong; Sun, Peidong; Zhang, Yuanzhi; Wu, Jigong; Lu, Sheng; Ouyang, Jun

    2013-01-01

    Background Accurate placement of pedicle screw during Anterior Transpedicular Screw fixation (ATPS) in cervical spine depends on accurate anatomical knowledge of the vertebrae. However, little is known of the morphometric characteristics of cervical vertebrae in Chinese population. Methods Three-dimensional reconstructions of CT images were performed for 80 cases. The anatomic data and screw fixation parameters for ATPS fixation were measured using the Mimics software. Findings The overall mean OPW, OPH and PAL ranged from 5.81 to 7.49 mm, 7.77 to 8.69 mm, and 33.40 to 31.13 mm separately, and SPA was 93.54 to 109.36 degrees from C3 to C6, 104.99 degrees at C7, whereas, 49.00 to 32.26 degrees from C4 to C7, 46.79 degrees at C3 (TPA). Dl/rSIP had an increasing trend away from upper endplate with mean value from 1.87 to 5.83 mm. Dl/rTIP was located at the lateral portion of the anterior cortex of vertebrae for C3 to C5 and ipsilateral for C6 to C7 with mean value from −2.70 to −3.00 mm, and 0.17 to 3.18 mm. The entrance points for pedicular screw insertion for C3 to C5 and C6 to C7 were recommended −2∼−3 mm and 0–4 mm from the median sagittal plane, respectively, 1–4 mm and 5–6 mm from the upper endplate, with TPA being 46.79–49.00 degrees and 40.89–32.26 degrees, respectively, and SPA being 93.54–106.69 degrees and 109.36–104.99 degrees, respectively. The pedicle screw insertion diameter was recommended 3.5 mm (C3 and C4), 4.0 mm (C5 to C7), and the pedicle axial length was 21–24 mm for C3 to C7 for both genders. However, the ATPS insertion in C3 should be individualized given its relatively small anatomical dimensions. Conclusions The data provided a morphometric basis for the ATPS fixation technique in lower cervical fixation. It will help in preoperative planning and execution of this surgery. PMID:24349038

  2. Bony Healing of Unstable Thoracolumbar Burst Fractures in the Elderly Using Percutaneously Applied Titanium Mesh Cages and a Transpedicular Fixation System with Expandable Screws

    PubMed Central

    Eschler, Anica; Ender, Stephan Albrecht; Schiml, Katharina; Mittlmeier, Thomas; Gradl, Georg

    2015-01-01

    Introduction There is a high incidence of vertebral burst fractures following low velocity trauma in the elderly. Treatment of unstable vertebral burst fractures using the same principles like in stable vertebral burst fractures may show less favourable results in terms of fracture reduction, maintenance of reduction and cement leakage. In order to address these shortcomings this study introduces cementless fixation of unstable vertebral burst fractures using internal fixators and expandable intravertebral titanium mesh cages in a one-stage procedure via minimum-invasive techniques. Material and Methods A total of 16 consecutive patients (median age 76 years, range 58–94) with unstable thoracolumbar burst fractures and concomitant osteoporosis were treated by an internal fixator inserted via minimum invasive technique one level above and below the fractured vertebra. Fracture reduction was achieved and maintained by transpedicular placement of two titanium mesh cages into the fractured vertebral body during the same procedure. Intra- and postoperative safety of the procedure as well as analysis of reduction quality was analysed by 3D C-arm imaging or CT, respectively. Clinical and radiographic follow-up averaged 10.4 months (range 4.5–24.5). Results Stabilization of the collapsed vertebral body was achieved in all 16 cases without any intraoperative complication. Surgical time averaged 102±6.6 minutes (71–194). The postoperative kyphotic angle (KA) and Cobb angle revealed significant improvements (KA 13.7° to 7.4°, p<0.001; Cobb 9.6° to 6.0°, p<0.002) with partial loss of reduction at final follow-up (KA 8.3°, Cobb 8.7°). VAS (Visual Analogue Scale) improved from 7.6 to 2.6 (p<0.001). Adjacent fractures were not observed. One minor (malposition of pedicle screw) complication was encountered. Conclusion Cementless fixation of osteoporotic burst fractures revealed substantial pain relief, adequate maintenance of reduction and a low complication rate

  3. The United Kingdom's stabilisation model and Afghanistan: the impact on humanitarian actors.

    PubMed

    Gordon, Stuart

    2010-10-01

    'Stabilisation' has emerged as a powerful policy framework since 2004. The United Kingdom has been at the forefront of states adopting and developing a 'stabilisation' model and has adapted government policy, processes and structures in its efforts to deliver 'stability' in Afghanistan's Helmand Province and Iraq--as well as elsewhere, such as in Nepal and Sudan. The experience acquired in Helmand in particular is likely to shape both future UK approaches and those of other donor states. The paper argues that the UK's model has evolved significantly since 2006, from a reconstruction strategy towards one that is based on supporting host-nation governance arrangements. Consequently, this paper addresses three principal themes: the origins and conceptualisation of the stabilisation discourse (and its relationship with state-building and early recovery concepts); the role of the UK's experience in Helmand in shaping the British approach; and the impact of the stabilisation model on the humanitarian community. PMID:20846350

  4. A review of polymeric dispersant stabilisation of titania pigment.

    PubMed

    Farrokhpay, Saeed

    2009-10-30

    A review of past and present published works examining the interaction of polymeric dispersants with titania pigment particles is presented. Titania is the most important white pigments currently used in the world and its suspension properties are very important for consumer industries such as paints, papermaking and plastics; if aggregates are present, the end-use properties including gloss, opacity and storage stability will be highly affected. As polymeric dispersants are generally used to disperse titania pigment particles, it is very important to understand the interactions between the pigment particles and polymeric dispersants of varying functionality. Although, in principle, the adsorption of polymers onto titania pigment and influences on pigment dispersion and stabilisation are fairly known, it is nevertheless hardly possible to forecast the behaviour of a given polymeric dispersant in advance, unless to have a broad knowledge of the interaction occurring between pigment and dispersants and effect of dispersant structure upon adsorption. While only titania pigment is discussed, the issues raised may also apply to other mineral oxides such as alumina or zirconia. PMID:19691945

  5. Stabilising a planning guide in post-mandibulectomy prosthodontic rehabilitation.

    PubMed

    Cachalia, H; Howes, D G; Owen, C P

    2012-08-01

    Patients presenting with grafted reconstructions of the mandible often lack anatomical features that allow for the consistent placement of a diagnostic denture and planning guide. The mucosa covering the graft appears flat with no discernible ridge form. A method was therefore adapted to provide stability to a guide for the placement of implants. A diagnostic denture was constructed to the try-in stage and duplicated in clear acrylic, with radio-opaque markers placed into potential implant positions. Three mini-implants (Southern implants, Irene, SA) were then placed under local anaesthetic trans-mucosally into the bone graft at positions corresponding to teeth 46, 31 and 36. Access holes were created in the flanges of the diagnostic denture/planning guide to enable it to seat over the mini implant heads and to allow for final positioning. Auto-polymerising resin was then placed to cover each of these heads, thus stabilising the guide. The patient was then referred for a CT scan, to be taken with the planning guide in situ, and a surgical guide was made from the CT data, which also used the mini implants for orientation. At surgery, this ensured the optimal placement of the definitive implants, and the mini-implants could then be removed. This method thus provides enormous beneft to both the planning for, and the placement of, implants into grafted bone in mandibulectomy patients. PMID:23951802

  6. Moduli stabilisation with nilpotent goldstino: vacuum structure and SUSY breaking

    NASA Astrophysics Data System (ADS)

    Aparicio, Luis; Quevedo, Fernando; Valandro, Roberto

    2016-03-01

    We study the effective field theory of KKLT and LVS moduli stabilisation scenarios coupled to an anti-D3-brane at the tip of a warped throat. We describe the presence of the anti-brane in terms of a nilpotent goldstino superfield in a supersymmetric effective field theory. The introduction of this superfield produces a term that can lead to a de Sitter minimum. We fix the Kähler moduli dependence of the nilpotent field couplings by matching this term with the anti-D3-brane uplifting contribution. The main result of this paper is the computation, within this EFT, of the soft supersymmetry breaking terms in both KKLT and LVS for matter living on D3-brane (leaving the D7-brane analysis to an appendix). A handful of distinct phenomenological scenarios emerge that could have low energy implications, most of them having a split spectrum of soft masses. Some cosmological and phenomenological properties of these models are discussed. We also check that the attraction between the D3-brane and the anti-D3-brane does not affect the leading contribution to the soft masses and does not destabilise the system.

  7. CO2 dissociation in vortex-stabilised microwave plasmas

    NASA Astrophysics Data System (ADS)

    Welzel, S.; Bongers, W. A.; Graswinckel, M. F.; van de Sanden, M. C. M.

    2014-10-01

    Plasma-assisted gas conversion techniques are widely considered as efficient building blocks in a future energy infrastructure which will be based on intermittent, renewable electricity sources. CO2 dissociation in high-frequency plasmas is of particular interest in carbon capture and utilisation process chains for the production of CO2-neutral fuels. In order to achieve efficient plasma processes of high throughput specifically designed gas flow and power injection regimes are required. In this contribution vortex-stabilised microwave plasmas in undiluted CO2 were studied in a pressure range from 170 to 1000 mbar at up to 1 kW (forward) injected power, respectively. The CO2 depletion was measured downstream, e.g. by means of mass spectrometry. Although the system configuration was entirely not optimised, energy efficiencies of nearly 40%, i.e. close to the thermal dissociation limit, and conversion efficiencies of up to 23% were achieved. Additionally, spatially-resolved emission spectroscopy was applied to map the axial and radial distribution of excited atomic (C, O) and molecular (CO, C2) species along with their rotational temperatures. Eindhoven University of Technology, Postbox 513, 5600 MB Eindhoven.

  8. Interplay between toroidal rotation and flow shear in turbulence stabilisation

    NASA Astrophysics Data System (ADS)

    Camenen, Y.; Casson, F. J.; Manas, P.; Peeters, A. G.

    2016-02-01

    The interplay between toroidal rotation u, parallel flow shear u', and perpendicular flow shear γE in the stabilisation of tokamak turbulence is investigated in non-linear flux-tube gyrokinetic simulations. The simulations are performed for a reference L-mode DIII-D plasma (the so-called shortfall case) at r /a =0.8 , varying the flow parameters around their nominal values. Depending on the respective signs of u, u', and γE, turbulence is found to be enhanced, reduced, or unchanged. When the coupling is favorable, the overall effect on the non-linear heat fluxes can be very large, even at moderate flow values. The ion heat flux is, for instance, decreased by a factor of 3 when the direction of the parallel flow shear is reversed with respect to its nominal value. Even more surprising, keeping u' and γE at their nominal values, the ion heat flux decreases by more than 50% when the toroidal flow is reversed. The relevance of this mechanism in the experiments which depends on the ability to decouple u, u', and γE is discussed. The interplay between u and u' observed in the non-linear simulations qualitatively follows the linear stability results and is interpreted in the frame of a simple fluid model.

  9. Thermal characterisation of (bio)polymers with a temperature-stabilised whispering gallery mode microsensor

    NASA Astrophysics Data System (ADS)

    Kim, Eugene; Foreman, Matthew R.; Baaske, Martin D.; Vollmer, Frank

    2015-04-01

    In this work, we theoretically and experimentally investigate the thermal response of whispering gallery mode microresonators operating in an aqueous glycerol medium. Thermal stabilisation of the resonance wavelength is realised by appropriate choice of the resonator radius and glycerol concentration, with a 60 fold reduction in thermal sensitivity demonstrated. Finally, we employ our stabilised system to determine the thermal dependence of the molecular polarisability of adsorbed bovine serum albumin molecules and the refractive index of dextran and poly(diallyldimethylammonium chloride) coatings.

  10. Development of guidelines for improved hydraulic design of waste stabilisation ponds.

    PubMed

    Shilton, A; Harrison, J

    2003-01-01

    Pond hydraulic behaviour is influenced by the inlet/outlet configuration, baffles and wind, but design information relating to these factors is still very limited. This paper reviews the development of "Guidelines for the Improved Hydraulic Design of Waste Stabilisation Ponds" and summarises some of the key findings and recommendations. This work was based on review of previous research, laboratory experimentation, field studies and mathematical modelling using computational fluid dynamics. The inlet design can have a significant influence on the flow regime in a pond. Poorly considered positioning of the inlet and the outlet can create hydraulic short-circuiting problems. As an example of the nature of the work undertaken in this project, the use of a small horizontal inlet pipe was compared against a vertical inlet design. A practical method of assessing the relative significance of wind versus inlet power input was presented. The application of this analysis may allow engineers to size inlet pipes to help control the flow patterns in ponds for efficient performance. Extensive testing has been undertaken on a wide range of baffle configurations. An example of this research showed how short stub baffles could provide similar improvements to longer "traditional" baffle designs, potentially offering significant savings in construction costs. For traditional baffle designs a minimum of two baffles is recommended. For the pond modelled in this work, it was found that any more than four baffles gave only marginal improvements. PMID:14510208

  11. Nonlinear hydrodynamic and thermoacoustic oscillations of a bluff-body stabilised turbulent premixed flame

    NASA Astrophysics Data System (ADS)

    Lee, Chin Yik; Li, Larry Kin Bong; Juniper, Matthew P.; Cant, Robert Stewart

    2016-01-01

    Turbulent premixed flames often experience thermoacoustic instabilities when the combustion heat release rate is in phase with acoustic pressure fluctuations. Linear methods often assume a priori that oscillations are periodic and occur at a dominant frequency with a fixed amplitude. Such assumptions are not made when using nonlinear analysis. When an oscillation is fully saturated, nonlinear analysis can serve as a useful avenue to reveal flame behaviour far more elaborate than period-one limit cycles, including quasi-periodicity and chaos in hydrodynamically or thermoacoustically self-excited system. In this paper, the behaviour of a bluff-body stabilised turbulent premixed propane/air flame in a model jet-engine afterburner configuration is investigated using computational fluid dynamics. For the frequencies of interest in this investigation, an unsteady Reynolds-averaged Navier-Stokes approach is found to be appropriate. Combustion is represented using a modified laminar flamelet approach with an algebraic closure for the flame surface density. The results are validated by comparison with existing experimental data and with large eddy simulation, and the observed self-excited oscillations in pressure and heat release are studied using methods derived from dynamical systems theory. A systematic analysis is carried out by increasing the equivalence ratio of the reactant stream supplied to the premixed flame. A strong variation in the global flame structure is observed. The flame exhibits a self-excited hydrodynamic oscillation at low equivalence ratios, becomes steady as the equivalence ratio is increased to intermediate values, and again exhibits a self-excited thermoacoustic oscillation at higher equivalence ratios. Rich nonlinear behaviour is observed and the investigation demonstrates that turbulent premixed flames can exhibit complex dynamical behaviour including quasiperiodicity, limit cycles and period-two limit cycles due to the interactions of various

  12. The challenge of sample-stabilisation in the era of multi-residue analytical methods: a practical guideline for the stabilisation of 46 organic micropollutants in aqueous samples.

    PubMed

    Hillebrand, Olav; Musallam, Shadha; Scherer, Laura; Nödler, Karsten; Licha, Tobias

    2013-06-01

    Water sample storage and stabilisation may affect data quality, if samples are managed improperly. In this study three stabilising strategies are evaluated for 46 relevant organic micro-pollutants: addition of the biocides (i) copper sulphate and (ii) sodium azide to water samples directly after sampling with subsequent sample storage as liquid phase and (iii) direct solid phase extraction (SPE), stabilising the samples by reducing the activity of water. River water and treated effluent were chosen as commonly investigated matrices with a high potential of biotransformation activity. Analyses were carried out for sample storage temperatures of 4 and 28°C for water samples stored as liquid phase and for sample storage temperatures of 4, 20 and 40°C for SPE cartridges. Cooling of water samples alone was not sufficient for longer storage times (>24h). While copper sulphate caused detrimental interferences with nitrogen containing heterocyclic compounds, sodium azide proved to be a suitable stabilising agent. The best results could be obtained for SPE cartridges stored cool. Recommendations for samples preservation are provided. PMID:23562683

  13. Quantum gate generation by T-sampling stabilisation

    NASA Astrophysics Data System (ADS)

    Silveira, H. B.; Pereira da Silva, P. S.; Rouchon, P.

    2014-06-01

    This paper considers right-invariant and controllable driftless quantum systems with state X(t) evolving on the unitary group U(n) and m inputs u = (u1, …, um). The T-sampling stabilisation problem is introduced and solved: given any initial condition X0 and any goal state ?, find a control law u = u(X, t) such that ? for the closed-loop system. The purpose is to generate arbitrary quantum gates corresponding to ?. This is achieved by the tracking of T-periodic reference trajectories ? of the quantum system that pass by ? using the framework of Coron's return method. The T-periodic reference trajectories ? are generated by applying controls ? that are a sum of a finite number M of harmonics of sin (2πt/T), whose amplitudes are parameterised by a vector a. The main result establishes that, for M big enough, X(jT) exponentially converges towards ? for almost all fixed a, with explicit and completely constructive control laws. This paper also establishes a stochastic version of this deterministic control law. The key idea is to randomly choose a different parameter vector of control amplitudes a = aj at each t = jT, and keeping it fixed for t ∈ [jT, (j + 1)T). It is shown in the paper that X(jT) exponentially converges towards ? almost surely. Simulation results have indicated that the convergence speed of X(jT) may be significantly improved with such stochastic technique. This is illustrated in the generation of the C-NOT quantum logic gate on U(4).

  14. Stabilisation/solidification of synthetic petroleum drill cuttings.

    PubMed

    Al-Ansary, Marwa S; Al-Tabbaa, Abir

    2007-03-15

    This paper presents the results of an experimental investigation into the use of stabilisation/solidification (S/S) to treat synthetic drill cuttings as a pre-treatment to landfilling or for potential re-use as construction products. Two synthetic mixes were used based on average concentrations of specific contaminates present in typical drill cuttings from the North Sea and the Red Sea areas. The two synthetic drill cuttings contained similar chloride content of 2.03% and 2.13% by weight but different hydrocarbon content of 4.20% and 10.95% by weight, respectively; hence the mixes were denoted as low and high oil content mixes, respectively. A number of conventional S/S binders were tested including Portland cement (PC), lime and blast-furnace slag (BFS), in addition to novel binders such as microsilica and magnesium oxide cement. Physical, chemical and microstructural analyses were used to compare the relative performance of the different binder mixes. The unconfined compressive strength (UCS) values were observed to cover a wide range depending on the binder used. Despite the significant difference in the hydrocarbon content in the two synthetic cuttings, the measured UCS values of the mixes with the same binder type and content were similar. The leachability results showed the reduction of the synthetic drill cuttings to a stable non-reactive hazardous waste, compliant with the UK acceptance criteria for non-hazardous landfills: (a) by most of the binders for chloride concentrations, and (b) by the 20% BFS-PC and 30% PC binders for the low oil content mix. The 30% BFS-PC binder successfully reduced the leached oil concentration of the low oil content mix to inert levels. Finally, the microstructural analysis offered valuable information on the morphology and general behaviour of the mixes that were not depicted by the other tests. PMID:16846687

  15. Robust scalable stabilisability conditions for large-scale heterogeneous multi-agent systems with uncertain nonlinear interactions: towards a distributed computing architecture

    NASA Astrophysics Data System (ADS)

    Manfredi, Sabato

    2016-06-01

    Large-scale dynamic systems are becoming highly pervasive in their occurrence with applications ranging from system biology, environment monitoring, sensor networks, and power systems. They are characterised by high dimensionality, complexity, and uncertainty in the node dynamic/interactions that require more and more computational demanding methods for their analysis and control design, as well as the network size and node system/interaction complexity increase. Therefore, it is a challenging problem to find scalable computational method for distributed control design of large-scale networks. In this paper, we investigate the robust distributed stabilisation problem of large-scale nonlinear multi-agent systems (briefly MASs) composed of non-identical (heterogeneous) linear dynamical systems coupled by uncertain nonlinear time-varying interconnections. By employing Lyapunov stability theory and linear matrix inequality (LMI) technique, new conditions are given for the distributed control design of large-scale MASs that can be easily solved by the toolbox of MATLAB. The stabilisability of each node dynamic is a sufficient assumption to design a global stabilising distributed control. The proposed approach improves some of the existing LMI-based results on MAS by both overcoming their computational limits and extending the applicative scenario to large-scale nonlinear heterogeneous MASs. Additionally, the proposed LMI conditions are further reduced in terms of computational requirement in the case of weakly heterogeneous MASs, which is a common scenario in real application where the network nodes and links are affected by parameter uncertainties. One of the main advantages of the proposed approach is to allow to move from a centralised towards a distributed computing architecture so that the expensive computation workload spent to solve LMIs may be shared among processors located at the networked nodes, thus increasing the scalability of the approach than the network

  16. Decentralised robust stabilisation of uncertain large-scale interconnected time-delay systems with unknown upper bounds of uncertainties

    NASA Astrophysics Data System (ADS)

    Wu, Hansheng

    2016-09-01

    The problem of decentralised robust stabilisation is considered for a class of uncertain large-scale time-delay interconnected dynamical systems. In the paper, the upper bounds of delayed state perturbations, uncertainties, interconnection terms, and external disturbances are assumed to be completely unknown, and the delays are assumed to be any non-negative constants. For such a class of uncertain large-scale time-delay interconnected systems, a new method is presented whereby a class of adaptation-free decentralised local robust state feedback controllers can be constructed. In addition, it is also shown that the solutions of uncertain large-scale time-delay interconnected systems can be guaranteed to be uniformly ultimately bounded. Finally, as an application to the practical mechanical systems, some simulations of a numerical example are provided to demonstrate the validity of the theoretical results.

  17. Cervical anterior transpedicular screw fixation (ATPS)—Part II. Accuracy of manual insertion and pull-out strength of ATPS

    PubMed Central

    Acosta, Frank; Tauber, Mark; Fox, Michael; Martin, Hudelmaier; Forstner, Rosmarie; Augat, Peter; Penzkofer, Rainer; Pirich, Christian; Kässmann, H.; Resch, Herbert; Hitzl, Wolfgang

    2008-01-01

    Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications in a previous study in Part I of our project. Consequently, the objectives of the current study were to assess the ex vivo accuracy of placing ATPS into the cervical vertebra as well as the biomechanical performance of ATPS in comparison to traditional vertebral body screws (VBS) in terms of pull-out strength (POS). Twenty-three ATPS were inserted alternately to two screws into the pedicles and vertebral bodies, respectively, of six cadaveric specimens from C3–T1. For insertion of ATPS, a manual fluoroscopically assisted technique was used. Pre- and post insertional CT-scans were used to assess accuracy of ATPS insertion in the axial and sagittal planes. A newly designed grading system and accuracy score were used to delineate accuracy of ATPS insertion. Following insertion of screws, 23 ATPS and 22 VBS were subjected to pull-out testing (POT). The bone mineral density (BMD) of each specimen was assessed prior to POT. Statistical analysis showed that the incidence of correctly placed screws and non-critical pedicles breaches in axial plane was 78.3%, and 95.7% in sagittal plane. Hence, according to our definition of “critical” pedicle breach that exposes neurovascular structures at risk, 21.7% (n = 5) of all ATPS inserted showed a critical pedicle breach in axial plane. Notably, no critical pedicle perforation occurred at the C6 to T1 levels. Pull-out testing of ATPS and VBS revealed that pull-out resistance of ATPS was 2.5-fold that of VBS. Mean POS of 23 ATPS with a mean BMD of 0.566

  18. Effect of particle adsorption rates on the disproportionation process in pickering stabilised bubbles.

    PubMed

    Ettelaie, Rammile; Murray, Brent

    2014-05-28

    The degree of shrinkage of particle stabilised bubbles of various sizes, in a polydisperse bubble dispersion, has been investigated in the light of the finite adsorption times for the particles and the disproportionation kinetics of the bubbles. For the case where the system contains an abundance of particles we find a threshold radius, above which bubbles are stabilised without any significant reduction in their size. Bubbles with an initial radius below this threshold on the other hand undergo a large degree of shrinkage prior to stabilisation. As the ratio of the available particles to the bubbles is reduced, it is shown that the final bubble size, for the larger bubbles in the distribution, becomes increasingly governed by the number of particles, rather than their adsorption time per se. For systems with "adsorption controlled" shrinkage ratio, the final bubble distribution is found to be wider than the initial one, while for a "particle number controlled" case it is actually narrower. Starting from a unimodal bubble size distribution, we predict that at intermediate times, prior to the full stabilisation of all bubbles, the distribution breaks up into a bimodal one. However, the effect is transient and a unimodal final bubble size distribution is recovered, when all the bubbles are stabilised by the particles. PMID:24880317

  19. SDP-based approximation of stabilising solutions for periodic matrix Riccati differential equations

    NASA Astrophysics Data System (ADS)

    Gusev, Sergei V.; Shiriaev, Anton S.; Freidovich, Leonid B.

    2016-07-01

    Numerically finding stabilising feedback control laws for linear systems of periodic differential equations is a nontrivial task with no known reliable solutions. The most successful method requires solving matrix differential Riccati equations with periodic coefficients. All previously proposed techniques for solving such equations involve numerical integration of unstable differential equations and consequently fail whenever the period is too large or the coefficients vary too much. Here, a new method for numerical computation of stabilising solutions for matrix differential Riccati equations with periodic coefficients is proposed. Our approach does not involve numerical solution of any differential equations. The approximation for a stabilising solution is found in the form of a trigonometric polynomial, matrix coefficients of which are found solving a specially constructed finite-dimensional semidefinite programming (SDP) problem. This problem is obtained using maximality property of the stabilising solution of the Riccati equation for the associated Riccati inequality and sampling technique. Our previously published numerical comparisons with other methods shows that for a class of problems only this technique provides a working solution. Asymptotic convergence of the computed approximations to the stabilising solution is proved below under the assumption that certain combinations of the key parameters are sufficiently large. Although the rate of convergence is not analysed, it appeared to be exponential in our numerical studies.

  20. Solidification/stabilisation of liquid oil waste in metakaolin-based geopolymer

    NASA Astrophysics Data System (ADS)

    Cantarel, V.; Nouaille, F.; Rooses, A.; Lambertin, D.; Poulesquen, A.; Frizon, F.

    2015-09-01

    The solidification/stabilisation of liquid oil waste in metakaolin based geopolymer was studied in the present work. The process consists of obtaining a stabilised emulsion of oil in a water-glass solution and then adding metakaolin to engage the setting of a geopolymer block with an oil emulsion stabilised in the material. Geopolymer/oil composites have been made with various oil fraction (7, 14 and 20 vol.%). The rigidity and the good mechanical properties have been demonstrated with compressive strength tests. Leaching tests evidenced the release of oil from the composite material is very limited whereas the constitutive components of the geopolymer (Na, Si and OH-) are involved into diffusion process.

  1. Early Spin-Stabilised Rockets - the Rockets of Bergrat Heinrich Gottlob Kuhn

    NASA Astrophysics Data System (ADS)

    Fricke, H.-D.

    19th century's war rockets were at first stabilised by sticks, but these sticks produced a very uncertain flight path and it often happened that rockets changed their direction and even flew back to their firing position. So very many early inventors in Europe, America, and British-India tried to stabilise the rocket's flight in a better way. They tried fins and even rotation but they did not succeed. It is said in history that William Hale was the first who succeeded in constructing a spin stabilised (i.e. rotating) rocket which worked. But before him, in the thirties of that century, a German amateur rocket inventor succeeded as well and secretly proved his stickless rotating rockets in trials for Prussian officers and some years later officially for Saxon artillery officers. His invention was then bought by the kingdom of Saxony, but these were never use in the field because of lack of money.

  2. Delay-dependent stability and stabilisation of continuous 2D delayed systems with saturating control

    NASA Astrophysics Data System (ADS)

    Hmamed, Abdelaziz; Kririm, Said; Benzaouia, Abdellah; Tadeo, Fernando

    2016-09-01

    This paper deals with the stabilisation problem of continuous two-dimensional (2D) delayed systems, in the presence of saturations on the control signals. For this, a new delay decomposition approach is proposed to deal with the stability and stabilisation issues. The idea is that the range of variation of each delay is divided into segments, and a specific Lyapunov- Krasovskii functional is used that contains different weight matrices in each segment. Then, based on this approach, new delay-dependent stability and stabilisation criteria for continuous 2D delayed systems are derived. These criteria are less conservative and include some existing results as special cases. Some numerical examples are provided to show that a significant improvement is achieved using the proposed approach.

  3. Addressing symptoms but not causes: stabilisation and humanitarian action in Timor-Leste.

    PubMed

    Lothe, Elisabeth; Peake, Gordon

    2010-10-01

    Asia's newest nation--Timor-Leste--has an unenviable track record of two Australian-led military stabilisation missions, five United Nations (UN) missions, and a vast humanitarian and international response over the course of the past decade. Two distinct approaches to stabilisation can be observed on this small half-island. The first is a 'security-first' approach, where development activities are complementary and serve to support security sector assistance, while the second emphasises traditional development activities and institution-building as the foundation for a stable country. Whereas these different approaches highlight various interpretations of the underlying problems and the task at hand, efforts aimed at stabilisation have crystallised the challenges of coordinating and integrating activities that are clearly interlinked and interdependent, whether within a UN integrated mission or implemented by bilateral actors. Consequently, the question of whether, or how, to measure progress towards this shared objective has gone largely unaddressed. PMID:20846353

  4. Stabilising a victor's peace? Humanitarian action and reconstruction in eastern Sri Lanka.

    PubMed

    Goodhand, Jonathan

    2010-10-01

    This paper focuses on the 'Sri Lankan model' of counter-insurgency and stabilisation and its implications for humanitarian and development actors. The Sri Lanka case shows that discourses, policies and practices associated with 'stabilisation' are not confined to 'fragile state' contexts in which there is heavy (and often militarised) international engagement--even though exemplars such as Afghanistan and Iraq have tended to dominate debates on this issue. Rather than being a single template, the 'stabilisation agenda' takes on very different guises in different contexts, presenting quite specific challenges to humanitarian and development actors. This is particularly true in settings like Sri Lanka, where there is a strong state, which seeks to make aid 'coherent' with its own vision of a militarily imposed political settlement. Working in such environments involves navigating a highly-charged domestic political arena, shaped by concerns about sovereignty, nationalism and struggles for legitimacy. PMID:20846349

  5. Greenhouse gas emissions from waste stabilisation ponds in Western Australia and Quebec (Canada).

    PubMed

    Glaz, Patricia; Bartosiewicz, Maciej; Laurion, Isabelle; Reichwaldt, Elke S; Maranger, Roxane; Ghadouani, Anas

    2016-09-15

    Waste stabilisation ponds (WSPs) are highly enriched environments that may emit large quantities of greenhouse gases (GHG), including CO2, CH4 and N2O. However, few studies provide detailed reports on these emissions. In the present study, we investigated GHG emissions from WSPs in Western Australia and Quebec, Canada, and compared emissions to WSPs from other climatic regions and to other types of aquatic ecosystems. Surface water GHG concentrations were related to phytoplankton biomass and nutrients. The CO2 was either emitted or absorbed by WSPs, largely as a function of phytoplankton dynamics and strong stratification in these shallow systems, whereas efflux of CH4 and N2O to the atmosphere was always observed albeit with highly variable emission rates, dependent on treatment phase and time of the day. The total global warming potential index (GWP index, calculated as CO2 equivalent) of emitted GHG from WSPs in Western Australia averaged 12.8 mmol m(-2) d(-1) (median), with CO2, CH4 and N2O respectively contributing 0%, 96.7% and 3.3% of the total emissions, while in Quebec WSPs this index was 194 mmol m(-2) d(-1), with a relative contribution of 93.8, 3.0 and 3.2% respectively. The CO2 fluxes from WSPs were of the same order of magnitude as those reported in hydroelectric reservoirs and constructed wetlands in tropical climates, whereas CH4 fluxes were considerably higher compared to other aquatic ecosystems. N2O fluxes were in the same range of values reported for WSPs in subtropical climate. PMID:27258617

  6. Effective solidification/stabilisation of mercury-contaminated wastes using zeolites and chemically bonded phosphate ceramics.

    PubMed

    Zhang, Shaoqing; Zhang, Xinyan; Xiong, Ya; Wang, Guoping; Zheng, Na

    2015-02-01

    In this study, two kinds of zeolites materials (natural zeolite and thiol-functionalised zeolite) were added to the chemically bonded phosphate ceramic processes to treat mercury-contaminated wastes. Strong promotion effects of zeolites (natural zeolite and thiol-functionalised zeolite) on the stability of mercury in the wastes were obtained and these technologies showed promising advantages toward the traditional Portland cement process, i.e. using Portland cement as a solidification agent and natural or thiol-functionalised zeolite as a stabilisation agent. Not only is a high stabilisation efficiency (lowered the Toxicity Characteristic Leaching Procedure Hg by above 10%) obtained, but also a lower dosage of solidification (for thiol-functionalised zeolite as stabilisation agent, 0.5 g g(-1) and 0.7 g g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) and stabilisation agents (for natural zeolite as stabilisation agent, 0.35 g g(-1) and 0.4 g g(-1) for chemically bonded phosphate ceramic and Portland cement, respectively) were used compared with the Portland cement process. Treated by thiol-functionalised zeolite and chemically bonded phosphate ceramic under optimum parameters, the waste containing 1500 mg Hg kg(-1) passed the Toxicity Characteristic Leaching Procedure test. Moreover, stabilisation/solidification technology using natural zeolite and chemically bonded phosphate ceramic also passed the Toxicity Characteristic Leaching Procedure test (the mercury waste containing 625 mg Hg kg(-1)). Moreover, the presence of chloride and phosphate did not have a negative effect on the chemically bonded phosphate ceramic/thiol-functionalised zeolite treatment process; thus, showing potential for future application in treatment of 'difficult-to-manage' mercury-contaminated wastes or landfill disposal with high phosphate and chloride content. PMID:25568090

  7. Robust stabilisation and L2 -gain analysis for switched systems with actuator saturation under asynchronous switching

    NASA Astrophysics Data System (ADS)

    Wang, Juan; Zhao, Jun

    2016-09-01

    Robust stabilisation and L2-gain analysis for a class of switched systems with actuator saturation are studied in this paper. The switching signal of the controllers lags behind that of the system modes, which leads to the asynchronous switching between the candidate controllers and the subsystems. By combining the piecewise Lyapunov function method with the convex hull technique, sufficient conditions in terms of LMIs for the solvability of the robust stabilisation and weighted L2-gain problems are presented respectively under the dwell time scheme. Finally, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed results.

  8. Vertebral stabilisation and selective decompression for the management of triple thoracolumbar disc protrusions.

    PubMed

    McKee, W M; Downes, C J

    2008-10-01

    Triple adjacent thoracolumbar disc protrusions causing moderate to severe spinal cord compression were diagnosed by magnetic resonance imaging in two German shepherd dogs with marked paraparesis and pelvic limb ataxia. Both cases were managed by selective hemilaminectomy, partial annulectomy and bilateral quadruple vertebral body stabilisation using novel canine locking fixation plates (SOP). The stabilisation of multiple vertebrae in the thoracolumbar spine was possible because the plates could be contoured with six degrees of freedom. Spinal pain resolved and neurological function improved in both dogs. Screw breakage was evident in one dog five months following surgery. PMID:18631222

  9. Environmental Controls and Eco-geomorphic Interactions of the Barchan-to-parabolic Dune Stabilisation and the Parabolic-to-barchan Dune Reactivation

    NASA Astrophysics Data System (ADS)

    Yan, Na; Baas, Andreas

    2015-04-01

    Parabolic dunes are one of a few common aeolian landforms which are highly controlled by eco-geomorphic interactions. Parabolic dunes, on the one hand, can be developed from highly mobile dune landforms, barchans for instance, in an ameliorated vegetation condition; or on the other hand, they can be reactivated and transformed back into mobile dunes due to vegetation deterioration. The fundamental mechanisms and eco-geomorphic interactions controlling both dune transformations remain poorly understood. To bridge the gap between complex processes involved in dune transformations on a relatively long temporal scale and real world monitoring records on a very limited temporal scale, this research has extended the DECAL model to incorporate 'dynamic' growth functions and the different 'growth' of perennial shrubs between growing and non-growing seasons, informed by field measurements and remote sensing analysis, to explore environmental controls and eco-geomorphic interactions of both types of dune transformation. A non-dimensional 'dune stabilising index' is proposed to capture the interactions between environmental controls (i.e. the capabilities of vegetation to withstand wind erosion and sand burial, the sandy substratum thickness, the height of the initial dune, and the sand transport potential), and establish the linkage between these controls and the geometry of a stabilising dune. An example demonstrates how to use the power-law relationship between the dune stabilising index and the normalised migration distance to assist in extrapolating the historical trajectories of transforming dunes. The modelling results also show that a slight increase in vegetation cover of an initial parabolic dune can significantly increase the reactivation threshold of climatic impact (both drought stress and wind strength) required to reactivate a stabilising parabolic dune into a barchan. Four eco-geomorphic interaction zones that govern a barchan-to-parabolic dune transformation

  10. Towards a General Understanding of Carbonyl-Stabilised Ammonium Ylide-Mediated Epoxidation Reactions.

    PubMed

    Novacek, Johanna; Roiser, Lukas; Zielke, Katharina; Robiette, Raphaël; Waser, Mario

    2016-08-01

    The key factors for carbonyl-stabilised ammonium ylide-mediated epoxidation reactions were systematically investigated by experimental and computational means and the hereby obtained energy profiles provide explanations for the observed experimental results. In addition, we were able to identify the first tertiary amine-based chiral auxiliary that allows for high enantioselectivities and high yields for such epoxidation reactions. PMID:27381752

  11. Stabilisation of proteins via mixtures of amino acids during spray drying.

    PubMed

    Ajmera, Ankur; Scherließ, Regina

    2014-03-10

    Biologicals are often formulated as solids in an effort to preserve stability which generally requires stabilising excipients for proper drying. The purpose of this study was to screen amino acids and their combinations for their stabilising effect on proteins during spray drying. Catalase, as model protein, was spray dried in 1+1 or 1+2 ratios with amino acids. Some amino acids namely arginine, glycine and histidine showed good retention of catalase functionality after spray drying and subsequent storage stress. A 1+1 combination of arginine and glycine in a 1+2 ratio with catalase resulted in a tremendously good stabilising effect. Storage at high temperature/humidity also showed beneficial effects of this combination. To evaluate whether this was a general principle, these findings were transferred to an antigenic protein of comparable size and supramolecular structure (haemagglutinin) as well as to a smaller enzyme (lysozyme). Upon spray drying with the combination of amino acids it could be shown that both proteins remain more stable especially after storage compared to the unprotected protein. The combination of arginine and glycine is tailored to the needs of protein stabilisation during spray drying and may hence be utilised in dry powder formulation of biomolecules with superior stability characteristics. PMID:24412336

  12. Measurement of wind profiles by motion-stabilised ship-borne Doppler lidar

    NASA Astrophysics Data System (ADS)

    Achtert, P.; Brooks, I. M.; Brooks, B. J.; Moat, B. I.; Prytherch, J.; Persson, P. O. G.; Tjernström, M.

    2015-09-01

    Three months of Doppler lidar wind measurements were obtained during the Arctic Cloud Summer Experiment on the icebreaker Oden during the summer of 2014. Such ship-borne measurements require active stabilisation to remove the effects of ship motion. We demonstrate that the combination of a commercial Doppler lidar with a custom-made motion-stabilisation platform enables the retrieval of wind profiles in the Arctic boundary layer during both cruising and ice-breaking with statistical uncertainties comparable to land-based measurements. This holds particularly within the planetary boundary layer even though the overall aerosol load was very low. Motion stabilisation was successful for high wind speeds in open water and the resulting wave conditions. It allows for the retrieval of winds with a random error below 0.2 m s-1, comparable to the measurement error of standard radiosondes. The combination of a motion-stabilised platform with a low-maintenance autonomous Doppler lidar has the potential to enable continuous long-term high-resolution ship-based wind profile measurements over the oceans.

  13. Measurement of wind profiles by motion-stabilised ship-borne Doppler lidar

    NASA Astrophysics Data System (ADS)

    Achtert, P.; Brooks, I. M.; Brooks, B. J.; Moat, B. I.; Prytherch, J.; Persson, P. O. G.; Tjernström, M.

    2015-11-01

    Three months of Doppler lidar wind measurements were obtained during the Arctic Cloud Summer Experiment on the icebreaker Oden during the summer of 2014. Such ship-borne Doppler measurements require active stabilisation to remove the effects of ship motion. We demonstrate that the combination of a commercial Doppler lidar with a custom-made motion-stabilisation platform enables the retrieval of wind profiles in the Arctic atmospheric boundary layer during both cruising and ice-breaking with statistical uncertainties comparable to land-based measurements. This held true particularly within the atmospheric boundary layer even though the overall aerosol load was very low. Motion stabilisation was successful for high wind speeds in open water and the resulting wave conditions. It allows for the retrieval of vertical winds with a random error below 0.2 m s-1. The comparison of lidar-measured wind and radio soundings gives a mean bias of 0.3 m s-1 (2°) and a mean standard deviation of 1.1 m s-1 (12°) for wind speed (wind direction). The agreement for wind direction degrades with height. The combination of a motion-stabilised platform with a low-maintenance autonomous Doppler lidar has the potential to enable continuous long-term high-resolution ship-based wind profile measurements over the oceans.

  14. Rapid stabilisation of atherosclerotic plaque with 5-aminolevulinic acid-mediated sonodynamic therapy.

    PubMed

    Li, Zhitao; Sun, Xin; Guo, Shuyuan; Wang, Liping; Wang, Tengyu; Peng, Chenghai; Wang, Wei; Tian, Zhen; Zhao, Ruibo; Cao, Wenwu; Tian, Ye

    2015-10-01

    5-Aminolevulinic acid-mediated sonodynamic therapy (ALA-SDT) effectively induces the apoptosis of atherogenic macrophages, but whether it can stabilise atherosclerotic plaque in vivo is unclear. Here, we used an animal model to evaluate the effects of ALA-SDT on plaque stabilisation. Sixty rabbits were induced atherosclerotic plaques in the femoral artery with a combination of silastic tube placement with atherogenic diet, and randomly assigned into control (n = 12) and SDT (n = 48) groups. In the SDT group, after intravenous injected with ALA (60 mg/kg) animals underwent the treatment of ultrasound with intensities of 0.75, 1.00, 1.50 and 2.00 W/cm(²) (n = 12 for each intensity). Seven days after the treatment, the plaque disruption assay was performed to test plaque stability. We found that ALA-SDT with ultrasound intensity of 1.5 W/cm(²) showed the strongest efficacy to stabilise plaques. Under this condition, the frequency of plaque disruption decreased by 88% (p<0.01), positive area of macrophages reduced by 94% (p<0.001) and percentage content of lipids dropped by 60% (p < 0.001), while percentage content of collagens increased by 127% (p<0.001). We also found that the plaque stabilisation by ALA-SDT was associated with increased macrophage apoptosis and apoptotic cell clearance. Moreover, ALA-SDT decreased the contents and activities of matrix metalloproteinase-2,9 and increased the levels of tissue inhibitors of matrix metalloproteinase-1,2 in plaques. Our studies demonstrate that ALA-SDT promotes plaque stabilisation by inducing macrophage elimination and inhibiting matrix degradation. This method might be a promising regimen for atherosclerosis therapy. PMID:26179778

  15. Towards 12% stabilised efficiency in single junction polymorphous silicon solar cells: experimental developments and model predictions

    NASA Astrophysics Data System (ADS)

    Abolmasov, Sergey; Cabarrocas, Pere Roca i.; Chatterjee, Parsathi

    2016-01-01

    We have combined recent experimental developments in our laboratory with modelling to devise ways of maximising the stabilised efficiency of hydrogenated amorphous silicon (a-Si:H) PIN solar cells. The cells were fabricated using the conventional plasma enhanced chemical vapour deposition (PECVD) technique at various temperatures, pressures and gas flow ratios. A detailed electrical-optical simulator was used to examine the effect of using wide band gap P-and N-doped μc-SiOx:H layers, as well as a MgF2 anti-reflection coating (ARC) on cell performance. We find that with the best quality a-Si:H so far produced in our laboratory and optimised deposition parameters for the corresponding solar cell, we could not attain a 10% stabilised efficiency due to the high stabilised defect density of a-Si:H, although this landmark has been achieved in some laboratories. On the other hand, a close cousin of a-Si:H, hydrogenated polymorphous silicon (pm-Si:H), a nano-structured silicon thin film produced by PECVD under conditions close to powder formation, has been developed in our laboratory. This material has been shown to have a lower initial and stabilised defect density as well as higher hole mobility than a-Si:H. Modelling indicates that it is possible to attain stabilised efficiencies of 12% when pm-Si:H is incorporated in a solar cell, deposited in a NIP configuration to reduce the P/I interface defects and combined with P- and N-doped μc-SiOx:H layers and a MgF2 ARC.

  16. [Stabilisation of post-acute stage schizophrenics: from the hospital to the city].

    PubMed

    Dammak, A; Stiti, M; Vacheron, M N

    2014-10-01

    Schizophrenia is a debilitating disease that usually begins in young adulthood, at a time when a person would usually make the transition to independent living, but it can occur at any age. The symptoms and behaviour associated with psychosis and schizophrenia have a distressing impact on the individual, and the family. The course of schizophrenia varies considerably. Although most patients will recover, some will have persisting difficulties or remain vulnerable to future episodes. Therefore, stabilisation of patients in acute phases and avoidance of relapse are major objectives of management throughout the course of this disease. The purpose of this article is to clarify the stabilisation, to study the contributing factors and strategies to implement to achieve stability, through a literature review and key guidelines. Thus, the patient is stabilised when productive symptoms and behavioural problems have decreased. So, the stable phase represents a prolonged period of treatment and rehabilitation during which symptoms are under adequate control and the focus is on improving functioning and recovery. Important predictive criteria of stabilisation include: positive symptoms, the number of previous relapses, cooperation with the patient and family, good adherence to treatment and the use of long acting injectable second-generation antipsychotics. After an acute relapse, the careful organization of the discharge and the development of a proposed ambulatory care in tailored care structures will help consolidate stabilisation and obtain remission. Accepting the idea of continuing treatment is a complex decision in which the psychiatrist plays a central role beside patients and their families. The course of integrated actions on modifiable risk factors such as psychosocial support, addictive comorbidities, identification of prodromes, active information for the therapeutic education of patients and families and access to care will also be supported. This would improve

  17. Bathymetry mapping using a GPS-sonar equipped remote control boat: Application in waste stabilisation ponds

    NASA Astrophysics Data System (ADS)

    Coggins, Liah; Ghadouani, Anas; Ghisalberti, Marco

    2014-05-01

    Traditionally, bathymetry mapping of ponds, lakes and rivers have used techniques which are low in spatial resolution, sometimes subjective in terms of precision and accuracy, labour intensive, and that require a high level of safety precautions. In waste stabilisation ponds (WSP) in particular, sludge heights, and thus sludge volume, are commonly measured using a sludge judge (a clear plastic pipe with length markings). A remote control boat fitted with a GPS-equipped sonar unit can improve the resolution of depth measurements, and reduce safety and labour requirements. Sonar devices equipped with GPS technology, also known as fish finders, are readily available and widely used by people in boating. Through the use of GPS technology in conjunction with sonar, the location and depth can be recorded electronically onto a memory card. However, despite its high applicability to the field, this technology has so far been underutilised. In the case of WSP, the sonar can measure the water depth to the top of the sludge layer, which can then be used to develop contour maps of sludge distribution and to determine sludge volume. The coupling of sonar technology with a remotely operative vehicle has several advantages of traditional measurement techniques, particularly in removing human subjectivity of readings, and the sonar being able to collect more data points in a shorter period of time, and continuously, with a much higher spatial resolution. The GPS-sonar equipped remote control boat has been tested on in excess of 50 WSP within Western Australia, and has shown a very strong correlation (R2 = 0.98) between spot readings taken with the sonar compared to a sludge judge. This has shown that the remote control boat with GPS-sonar device is capable of providing sludge bathymetry with greatly increased spatial resolution, while greatly reducing profiling time. Remotely operated vehicles, such as the one built in this study, are useful for not only determining sludge

  18. High pressure hydrogen stabilised by quantum nuclear motion

    NASA Astrophysics Data System (ADS)

    Needs, Richard; Monserrat, Bartomeu; Pickard, Chris

    Hydrogen under extreme pressures is of fundamental interest, as it might exhibit exotic physical phenomena, and of practical interest, as it is a major component of many astrophysical objects. Structure searches have been successful at identifying promising candidates for the known phases of high pressure hydrogen. However, these searches have so far been restricted to the location of minima of the potential energy landscape. In this talk, we will describe a new structure searching method, ``saddle-point ab initio random structure searching'' (sp-AIRSS), that allows us to identify structures associated with saddle points of the potential energy landscape. Using sp-AIRSS, we find two new high-pressure hydrogen structures that exhibit a harmonic dynamical instability, but quantum and thermal anharmonic motion render them dynamically stable. These structures are formed by mixed layers of strongly and softly bound hydrogen molecules, and become thermodynamically competitive at the highest pressures reached in experiment. The experimental implications of these new structures will also be discussed. BM is supported by Robinson College, Cambridge, and the Cambridge Philosophical Society. RJN and CJP are supported by the Engineering and Physical Sciences Research Council (EPSRC) of the UK.

  19. Stabilising falling liquid film flows using feedback control

    NASA Astrophysics Data System (ADS)

    Thompson, Alice B.; Gomes, Susana N.; Pavliotis, Grigorios A.; Papageorgiou, Demetrios T.

    2016-01-01

    Falling liquid films become unstable due to inertial effects when the fluid layer is sufficiently thick or the slope sufficiently steep. This free surface flow of a single fluid layer has industrial applications including coating and heat transfer, which benefit from smooth and wavy interfaces, respectively. Here, we discuss how the dynamics of the system are altered by feedback controls based on observations of the interface height, and supplied to the system via the perpendicular injection and suction of fluid through the wall. In this study, we model the system using both Benney and weighted-residual models that account for the fluid injection through the wall. We find that feedback using injection and suction is a remarkably effective control mechanism: the controls can be used to drive the system towards arbitrary steady states and travelling waves, and the qualitative effects are independent of the details of the flow modelling. Furthermore, we show that the system can still be successfully controlled when the feedback is applied via a set of localised actuators and only a small number of system observations are available, and that this is possible using both static (where the controls are based on only the most recent set of observations) and dynamic (where the controls are based on an approximation of the system which evolves over time) control schemes. This study thus provides a solid theoretical foundation for future experimental realisations of the active feedback control of falling liquid films.

  20. Resisting regime-shifts: the stabilising effect of compensatory processes.

    PubMed

    Connell, Sean D; Ghedini, Giulia

    2015-09-01

    Ecologists seem predisposed to studying change because we are intuitively interested in dynamic systems, including their vulnerability to human disturbance. We contrast this disposition with the value of studying processes that work against change. Although powerful, processes that counter disturbance often go unexplored because they yield no observable community change. This stability results from compensatory processes which are initiated by disturbance; these adjust in proportion to the strength of the disturbance to prevent community change. By recognising such buffering processes, we might also learn to recognise the early warning signals of community shifts which are notoriously difficult to predict because communities often show little to no change before their tipping point is reached. PMID:26190138

  1. Observer-based stabilisation of a class of nonlinear systems in the presence of measurement delay

    NASA Astrophysics Data System (ADS)

    He, Qing; Liu, Jinkun

    2016-06-01

    In this paper, the stabilising control problem for a class of nonlinear system in the presence of measurement delay is addressed. A full-order observer is designed to eliminate the effect of variable output time delay, which is bounded and known. Then, the estimated states are utilised for the state feedback control law to stabilise the considered control system. Lyapunov-Razumikhin approach is employed to analyse the stability of the closed-loop system. Unlike the previous work, the exponential convergence of the estimation error is ensured, rather than asymptotic convergence, by designing a delay-dependent gain of the observer. Moreover, comparison with similar work is also made in simulation to illustrate the effectiveness of the proposed strategy.

  2. Steady-state entanglement of distant transmons, stabilised against high transmission loss

    NASA Astrophysics Data System (ADS)

    Motzoi, Felix; Halperin, Eli; Wang, Xiaoting; Whaley, Birgitta; Schirmer, Sophie

    2015-03-01

    Being able to stabilise entanglement over long distances and long times provides numerous advantages over pulsed experiments (avoiding variability, synchronisation, and calibration issues) while providing an important resource on-demand, which can then be potentially distilled and used to construct a quantum network. We show how existing superconducting technologies can be entangled over distances of tens of meters providing resilient stabilisation even in the presence of high inefficiency of the transmission channel. This can be achieved both in the dispersive and near-resonant cavity regimes using simple protocols that employ correlated environmental interactions and symmetry breaking. These require only a single-frequency drive that interacts sequentially with each cavity-qubit system. The dispersive regime protocol uses feedback while the near-resonant regime protocol is autonomous.

  3. A sol-powder coating technique for fabrication of yttria stabilised zirconia

    SciTech Connect

    Wattanasiriwech, Darunee . E-mail: darunee@mfu.ac.th; Wattanasiriwech, Suthee; Stevens, Ron

    2006-08-10

    Yttria stabilised zirconia has been prepared using a simple sol-powder coating technique. The polymeric yttria sol, which was prepared using 1,3 propanediol as a network modifier, was homogeneously mixed with nanocrystalline zirconia powder and it showed a dual function: as a binder which promoted densification and a phase modifier which stabilised zirconia in the tetragonal and cubic phases. Thermal analysis and X-ray diffraction revealed that the polymeric yttria sol which decomposed at low temperature into yttrium oxide could change the m {sup {yields}} t phase transformation behaviour of the zirconia, possibly due to the small particle size and very high surface area of both yttria and zirconia particles allowing rapid alloying. The sintered samples exhibited three crystalline phases: monoclinic, tetragonal and cubic, in which cubic and tetragonal are the major phases. The weight fractions of the individual phases present in the selected specimens were determined using quantitative Rietveld analysis.

  4. Head roll stabilisation in the nocturnal bull ant Myrmecia pyriformis: implications for visual navigation.

    PubMed

    Raderschall, Chloé A; Narendra, Ajay; Zeil, Jochen

    2016-05-15

    Ant foragers are known to memorise visual scenes that allow them to repeatedly travel along idiosyncratic routes and to return to specific places. Guidance is provided by a comparison between visual memories and current views, which critically depends on how well the attitude of the visual system is controlled. Here we show that nocturnal bull ants stabilise their head to varying degrees against locomotion-induced body roll movements, and this ability decreases as light levels fall. There are always un-compensated head roll oscillations that match the frequency of the stride cycle. Head roll stabilisation involves both visual and non-visual cues as ants compensate for body roll in complete darkness and also respond with head roll movements when confronted with visual pattern oscillations. We show that imperfect head roll control degrades navigation-relevant visual information and discuss ways in which navigating ants may deal with this problem. PMID:26994172

  5. Accessible Mannitol-Based Amphiphiles (MNAs) for Membrane Protein Solubilisation and Stabilisation.

    PubMed

    Hussain, Hazrat; Du, Yang; Scull, Nicola J; Mortensen, Jonas S; Tarrasch, Jeffrey; Bae, Hyoung Eun; Loland, Claus J; Byrne, Bernadette; Kobilka, Brian K; Chae, Pil Seok

    2016-05-17

    Integral membrane proteins are amphipathic molecules crucial for all cellular life. The structural study of these macromolecules starts with protein extraction from the native membranes, followed by purification and crystallisation. Detergents are essential tools for these processes, but detergent-solubilised membrane proteins often denature and aggregate, resulting in loss of both structure and function. In this study, a novel class of agents, designated mannitol-based amphiphiles (MNAs), were prepared and characterised for their ability to solubilise and stabilise membrane proteins. Some of MNAs conferred enhanced stability to four membrane proteins including a G protein-coupled receptor (GPCR), the β2 adrenergic receptor (β2 AR), compared to both n-dodecyl-d-maltoside (DDM) and the other MNAs. These agents were also better than DDM for electron microscopy analysis of the β2 AR. The ease of preparation together with the enhanced membrane protein stabilisation efficacy demonstrates the value of these agents for future membrane protein research. PMID:27072057

  6. Robust stabilisation of time-varying delay systems with probabilistic uncertainties

    NASA Astrophysics Data System (ADS)

    Jiang, Ning; Xiong, Junlin; Lam, James

    2016-09-01

    For robust stabilisation of time-varying delay systems, only sufficient conditions are available to date. A natural question is as follows: if the existing sufficient conditions are not satisfied, and hence no controllers can be found, what can one do to improve the stability performance of time-varying delay systems? This question is addressed in this paper when there is a probabilistic structure on the parameter uncertainty set. A randomised algorithm is proposed to design a state-feedback controller, which stabilises the system over the uncertainty domain in a probabilistic sense. The capability of the designed controller is quantified by the probability of stability of the resulting closed-loop system. The accuracy of the solution obtained from the randomised algorithm is also analysed. Finally, numerical examples are used to illustrate the effectiveness and advantages of the developed controller design approach.

  7. Arsenic and copper stabilisation in a contaminated soil by coal fly ash and green waste compost.

    PubMed

    Tsang, Daniel C W; Yip, Alex C K; Olds, William E; Weber, Paul A

    2014-09-01

    In situ metal stabilisation by amendments has been demonstrated as an appealing low-cost remediation strategy for contaminated soil. This study investigated the short-term leaching behaviour and long-term stability of As and Cu in soil amended with coal fly ash and/or green waste compost. Locally abundant inorganic (limestone and bentonite) and carbonaceous (lignite) resources were also studied for comparison. Column leaching experiments revealed that coal fly ash outperformed limestone and bentonite amendments for As stabilisation. It also maintained the As stability under continuous leaching of acidic solution, which was potentially attributed to high-affinity adsorption, co-precipitation, and pozzolanic reaction of coal fly ash. However, Cu leaching in the column experiments could not be mitigated by any of these inorganic amendments, suggesting the need for co-addition of carbonaceous materials that provides strong chelation with oxygen-containing functional groups for Cu stabilisation. Green waste compost suppressed the Cu leaching more effectively than lignite due to the difference in chemical composition and dissolved organic matter. After 9-month soil incubation, coal fly ash was able to minimise the concentrations of As and Cu in the soil solution without the addition of carbonaceous materials. Nevertheless, leachability tests suggested that the provision of green waste compost and lignite augmented the simultaneous reduction of As and Cu leachability in a fairly aggressive leaching environment. These results highlight the importance of assessing stability and remobilisation of sequestered metals under varying environmental conditions for ensuring a plausible and enduring soil stabilisation. PMID:24859701

  8. The Stabilisation Potential of Individual and Mixed Assemblages of Natural Bacteria and Microalgae

    PubMed Central

    Lubarsky, Helen V.; Hubas, Cédric; Chocholek, Melanie; Larson, Fredrik; Manz, Werner; Paterson, David M.; Gerbersdorf, Sabine U.

    2010-01-01

    It is recognized that microorganisms inhabiting natural sediments significantly mediate the erosive response of the bed (“ecosystem engineers”) through the secretion of naturally adhesive organic material (EPS: extracellular polymeric substances). However, little is known about the individual engineering capability of the main biofilm components (heterotrophic bacteria and autotrophic microalgae) in terms of their individual contribution to the EPS pool and their relative functional contribution to substratum stabilisation. This paper investigates the engineering effects on a non-cohesive test bed as the surface was colonised by natural benthic assemblages (prokaryotic, eukaryotic and mixed cultures) of bacteria and microalgae. MagPI (Magnetic Particle Induction) and CSM (Cohesive Strength Meter) respectively determined the adhesive capacity and the cohesive strength of the culture surface. Stabilisation was significantly higher for the bacterial assemblages (up to a factor of 2) than for axenic microalgal assemblages. The EPS concentration and the EPS composition (carbohydrates and proteins) were both important in determining stabilisation. The peak of engineering effect was significantly greater in the mixed assemblage as compared to the bacterial (x 1.2) and axenic diatom (x 1.7) cultures. The possibility of synergistic effects between the bacterial and algal cultures in terms of stability was examined and rejected although the concentration of EPS did show a synergistic elevation in mixed culture. The rapid development and overall stabilisation potential of the various assemblages was impressive (x 7.5 and ×9.5, for MagPI and CSM, respectively, as compared to controls). We confirmed the important role of heterotrophic bacteria in “biostabilisation” and highlighted the interactions between autotrophic and heterotrophic biofilm consortia. This information contributes to the conceptual understanding of the microbial sediment engineering that represents an

  9. Finite-time state feedback stabilisation of stochastic high-order nonlinear feedforward systems

    NASA Astrophysics Data System (ADS)

    Xie, Xue-Jun; Zhang, Xing-Hui; Zhang, Kemei

    2016-07-01

    This paper studies the finite-time state feedback stabilisation of stochastic high-order nonlinear feedforward systems. Based on the stochastic Lyapunov theorem on finite-time stability, by using the homogeneous domination method, the adding one power integrator and sign function method, constructing a ? Lyapunov function and verifying the existence and uniqueness of solution, a continuous state feedback controller is designed to guarantee the closed-loop system finite-time stable in probability.

  10. Cooling and thermal stabilisation of Faraday rotators in the temperature range 300 - 200 K using Peltier elements

    SciTech Connect

    Palashov, O V; Ievlev, Ivan V; Perevezentsev, E A; Katin, E V; Khazanov, Efim A

    2011-09-30

    A new method for cooling and thermal stabilisation of Faraday rotators using Peltier elements is proposed and experimentally demonstrated. The scheme of thermal stabilisation of the magnetooptical elements ensures reliable operation of the device at the absorbed power {approx}2 W, which corresponds to the transmitted laser radiation power 1.5 kW. The results of the work make it possible to predict high efficiency of this method at the laser power of tens of kilowatts.

  11. [Failed compression osteosynthesis of the dens axis treated by anterior C1-C2 transarticular stabilisation. Case report].

    PubMed

    Kočiš, J; Kelbl, M

    2011-01-01

    We describe the case of an 80-year-old female patient who had undergone anterior C1-C2 transarticular stabilisation and was subsequently treated by the triple-screw method for failed compression osteosynthesis of a AO type III dens axis fracture. Key words: dens axis, upper cervical spine fracture, eldery, triple screw technique, anterior transarticular C1-C2 stabilisation. PMID:21729645

  12. Stabilisation of Na,K-ATPase structure by the cardiotonic steroid ouabain

    SciTech Connect

    Miles, Andrew J.; Fedosova, Natalya U.; Hoffmann, Søren V.; Wallace, B.A.; Esmann, Mikael

    2013-05-31

    Highlights: •Ouabain binding to pig and shark Na,K-ATPase enhances thermal stability. •Ouabain stabilises both membrane-bound and solubilised Na,K-ATPase. •Synchrotron radiation circular dichroism is used for structure determination. •Secondary structure in general is not affected by ouabain binding. •Stabilisation is due to re-arrangement of tertiary structure. -- Abstract: Cardiotonic steroids such as ouabain bind with high affinity to the membrane-bound cation-transporting P-type Na,K-ATPase, leading to complete inhibition of the enzyme. Using synchrotron radiation circular dichroism spectroscopy we show that the enzyme-ouabain complex is less susceptible to thermal denaturation (unfolding) than the ouabain-free enzyme, and this protection is observed with Na,K-ATPase purified from pig kidney as well as from shark rectal glands. It is also shown that detergent-solubilised preparations of Na,K-ATPase are stabilised by ouabain, which could account for the successful crystallisation of Na,K-ATPase in the ouabain-bound form. The secondary structure is not significantly affected by the binding of ouabain. Ouabain appears however, to induce a reorganization of the tertiary structure towards a more compact protein structure which is less prone to unfolding; recent crystal structures of the two enzymes are consistent with this interpretation. These circular dichroism spectroscopic studies in solution therefore provide complementary information to that provided by crystallography.

  13. Global stabilisation of a class of generalised cascaded systems by homogeneous method

    NASA Astrophysics Data System (ADS)

    Ding, Shihong; Zheng, Wei Xing

    2016-04-01

    This paper considers the problem of global stabilisation of a class of generalised cascaded systems. By using the extended adding a power integrator technique, a global controller is first constructed for the driving subsystem. Then based on the homogeneous properties and polynomial assumption, it is shown that the stabilisation of the driving subsystem implies the stabilisation of the overall cascaded system. Meanwhile, by properly choosing some control parameters, the global finite-time stability of the closed-loop cascaded system is also established. The proposed control method has several new features. First, the nonlinear cascaded systems considered in the paper are more general than the conventional ones, since the powers in the nominal part of the driving subsystem are not required to be restricted to ratios of positive odd numbers. Second, the proposed method has some flexible parameters which provide the possibility for designing continuously differentiable controllers for cascaded systems, while the existing designed controllers for such kind of cascaded systems are only continuous. Third, the homogenous and polynomial conditions adopted for the driven subsystem are easier to verify when compared with the matching conditions that are widely used previously. Furthermore, the efficiency of the proposed control method is validated by its application to finite-time tracking control of non-holonomic wheeled mobile robot.

  14. High-pulse-repetition-rate UV lasers with the inductance-capacitance discharge stabilisation

    SciTech Connect

    Andramanov, A V; Kabaev, S A; Lazhintsev, B V; Nor-Arevyan, V A; Pisetskaya, A V; Selemir, Victor D

    2009-02-28

    Compact high-pulse-repetition-rate XeF and KrF excimer lasers and an N{sub 2} laser with plate electrodes and the inductive-capacitance discharge stabilisation are studied. The composition and pressure of the active medium of lasers are optimised for obtaining the maximum output energy and maximum pulse repetition rate at comparatively low (no more than 19 m s{sup -1}) active-medium flow rates in the interelectrode gap. The pulse repetition rate achieved 4-5 kHz for the relative root-mean-square deviation of the laser pulse energy less than 2%. It is found that the energy of the N{sub 2}-laser pulses changes periodically under the action of acoustic perturbations appearing at high pulse repetition rates. It is shown that the use of the inductance-capacitance stabilisation of the discharge provides the increase in the maximum pulse repetition rate by 0.5-1.5 kHz (depending on the active medium type). It is found that the stability of the output energy and maximum pulse repetition rate depend on the location of preionisation sparks with respect to the gas flow direction. Some ways for the development of the technology of plate electrodes and inductance-capacitance discharge stabilisation are proposed. (lasers)

  15. Flank creeping, a mechanism of stabilisation and destabilisation: example of the Tenerife NE-Rift Zone, Spain

    NASA Astrophysics Data System (ADS)

    Delcamp, A.; van Wyk de Vries, B.; Troll, V.; Petronis, M. S.; Carracedo, J. C.

    2009-12-01

    The volcanic evolution of Tenerife has been largely studied, and the eruptive story of the NE and NW rift zones is now well-constrained. A systematic and detailed mapping of dykes of the North East Rift Zone (NERZ) allows to go further and brings new highlights in the intrusive story related to the three successive collapses (1-Micheque, 2-Guïmar and 3-La Orotava) that are located on each side of the rift. Flank creeping seems to be the major mechanism that accommodates the emplacement of the intrusive complex and its associated dykes. Flank spreading allows the stabilisation of the rift until a critical point where further intrusion will generate collapse. The main features deduced from field observation are reproduced and confirmed using analogue models consisting in plaster-sand ridges intruded by golden syrup. The rift at its first stages of growth may be controlled by the regional stress field but its future development depends on the local stress field created by the rift zone evolution. Volcanic rift zones represent clearly a dynamic and changing geological and geographical environment. Keywords: rift zone, flank creeping, strike-slip, dyke intrusion, basal intrusive complex, collapse.

  16. Stabilising cubosomes with Tween 80 as a step towards targeting lipid nanocarriers to the blood-brain barrier.

    PubMed

    Azhari, Hanisah; Strauss, Mike; Hook, Sarah; Boyd, Ben J; Rizwan, Shakila B

    2016-07-01

    Coating nanoparticles with the surfactant Tween 80 have been previously shown to enhance drug delivery across the blood-brain barrier (BBB). The aim of this study was to investigate whether Tween 80 could be used to stabilise phytantriol-based cubosomes thereby enabling potential application in delivering macromolecular therapeutics to the brain. Cubosome particles with their large internal and external surface area by virtue of their nanostructure are ideal for delivery of macromolecules. Phase behaviour studies were conducted using a combination of optical microscopy and small-angle X-ray scattering (SAXS) and the addition of Tween 80 to mixtures of phytantriol and water resulted in a rich array of lyotropic mesophases. In particular, a large cubic phase region and a two-phase region of readily dispersed cubosomes is observed. Cubosomes with different concentrations of Tween 80 and phytantriol as the liquid crystal forming lipid were prepared using the solvent precursor method and their physical properties were investigated. A combination of dynamic light scattering, cryogenic electron tomography and SAXS shows formation of well-defined cubosomes with a narrow size distribution and the Im3m cubic structure. Collectively, the results confirm that Tween 80 can effectively stabilize phytantriol cubosomes, opening the possibility for future application in drug delivery across the BBB. Moreover, well-defined, homogenous cubosome formulations prepared using the mild solvent precursor dilution method has significant implications for large-scale production of cubosomes, which currently is a major barrier to the application of cubosomes in the clinic. PMID:27163239

  17. Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised?

    PubMed Central

    Imam, M. A.; Eifert, A.; Freeman, M. A. R.; Pinskerova, V.; Field, R. E.; Skinner, J.; Banks, S. A.

    2016-01-01

    Objectives Throughout the 20th Century, it has been postulated that the knee moves on the basis of a four-bar link mechanism composed of the cruciate ligaments, the femur and the tibia. As a consequence, the femur has been thought to roll back with flexion, and total knee arthroplasty (TKA) prostheses have been designed on this basis. Recent work, however, has proposed that at a position of between 0° and 120° the medial femoral condyle does not move anteroposteriorly whereas the lateral femoral condyle tends, but is not obliged, to roll back – a combination of movements which equates to tibial internal/ femoral external rotation with flexion. The aim of this paper was to assess if the articular geometry of the GMK Sphere TKA could recreate the natural knee movements in situ/in vivo. Methods The pattern of knee movement was studied in 15 patients (six male: nine female; one male with bilateral TKAs) with 16 GMK Sphere implants, at a mean age of 66 years (53 to 76) with a mean BMI of 30 kg/m2 (20 to 35). The motions of all 16 knees were observed using pulsed fluoroscopy during a number of weight-bearing and non-weight-bearing static and dynamic activities. Results During maximally flexed kneeling and lunging activities, the mean tibial internal rotation was 8° (standard deviation (sd) 6). At a mean 112° flexion (sd 16) during lunging, the medial and lateral condyles were a mean of 2 mm (sd 3) and 8 mm (sd 4) posterior to a transverse line passing through the centre of the medial tibial concavity. With a mean flexion of 117° (sd 14) during kneeling, the medial and lateral condyles were a mean of 1 mm (sd 4) anterior and 6 mm (sd 4) posterior to the same line. During dynamic stair and pivoting activities, there was a mean anteroposterior translation of 0 mm to 2 mm of the medial femoral condyle. Backward lateral condylar translation occurred and was linearly related to tibial rotation. Conclusion The GMK Sphere TKA in our study group shows movements similar in

  18. A 10-year follow-up of transpedicular screw fixation and intervertebral autogenous posterior iliac crest bone graft or intervertebral B-Twin system in failed back surgery syndrome

    PubMed Central

    Cincu, Rafael; Lorente, Francisco de Asis; Gomez, Joaquin; Eiras, Jose; Agrawal, Amit

    2015-01-01

    Background: The spine surgeons have been combining anterior and posterolateral fusion (circumferential fusion) as the final solution to treat spinal disorders and many have been using it to treat failed back surgery syndrome (FBSS). In present study, we analyzed and compared the clinical and radiological outcomes in patients with transpedicular screw fixation and intervertebral autogenous posterior iliac crest bone graft or in patients with transpedicular screw fixation and intervertebral B-Twin system for FBSS with a follow-up period of 10 years after the surgery. Materials and Methods: This study was a retrospective case study performed on 55 patients with FBSS. Clinical and radiological changes were compared between the two groups of patients on the basis of improvement of back pain, radicular pain, and work capacity. Outcome was measured in terms of Oswestry Low Back Pain Disability Index, and the changes in pain and function were documented every year from before surgery until 2012. We analyzed the evolution of 55 cases of FBSS those underwent segmental circumferential posterior fusions from June 2001 to February 2003, operated by a single surgeon and followed up during 10 years until February 2012. The patients were divided into 2 groups: In 25 patients, posterolateral fusions with Legacy™ (Medtronic, Inc. NYSE: MDT) screws and intersomatic autogenous posterior iliac crest bone graft was performed, and, in 30 patients, posterolateral fusions with the same screws and intersomatic fusion B-Twin (Biomet Spain Orthopaedics, S.L.) system was performed. In all cases, we used posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) approach for intervertebral graft, and the artrodesis was supplemented at intertransverse level with Autologus Growth Factor (AGF-MBA INCORPORADO, S.A.). The outcome was measured in terms of Oswestry Low Back Pain Disability Index, and the changes in pain and function were documented every year and compared

  19. Effect of duckweed cover on greenhouse gas emissions and odour release from waste stabilisation ponds.

    PubMed

    van der Steen, N P; Nakiboneka, P; Mangalika, L; Ferrer, A V M; Gijzen, H J

    2003-01-01

    Treatment of wastewater in stabilisation pond systems prevents the negative environmental impact of uncontrolled disposal of sewage. However, even a natural treatment system may generate secondary negative environmental impacts in terms of energy consumption, emission of greenhouse gases and emission of odorous compounds. Whereas natural systems have an advantage over electro-mechanical systems in that they use less hardware and less energy, it is not yet known whether secondary environmental effects in the form of greenhouse gas emissions are lower for these systems. This research intends to be a first step in the direction of answering this question by assessing gas emissions from two types of natural systems, namely algae-based and duckweed-based stabilisation ponds. The H2S volatilisation from laboratory scale pond-reactors has been determined by drawing the air above the water surface continuously through a solution of 1 M NaOH for absorption of sulphide. The amount of H2S that volatilised from the algae pond-reactor, and was trapped in the NaOH trap, was found to be 2.5-86 mg/m2/day. The H2S volatilisation from the duckweed pond-reactor was found to be negligible, even though the sulphide concentration was 9.7 mg/l S(2-). The duckweed cover was a physical barrier for volatilisation, since bubbles were trapped in the cover. In addition the duckweed layer was found to be afavourable environment for both aerobic sulphide oxidisers (Beggiatoa gigantae) as well as for photosynthetic purple sulphur bacteria belonging to the genus Chromatium. These may also have contributed to the prevention of H2S volatilisation. Results on methane emissions were not conclusive so far, but the same mechanisms that prevent H2S volatilisation may also prevent methane volatilisation. Therefore it was concluded that duckweed covers on stabilisation ponds may reduce the emission of both odorous and greenhouse gases. PMID:14510229

  20. Phase stabilisation of hexagonal barium titanate doped with transition metals: A computational study

    SciTech Connect

    Dawson, J.A.; Freeman, C.L.; Harding, J.H.; Sinclair, D.C.

    2013-04-15

    Interatomic potentials recently developed for the modelling of BaTiO{sub 3} have been used to explore the stabilisation of the hexagonal polymorph of BaTiO{sub 3} by doping with transition metals (namely Mn, Co, Fe and Ni) at the Ti-site. Classical simulations have been completed on both the cubic and hexagonal polymorphs to investigate the energetic consequences of transition metal doping on each polymorph. Ti-site charge compensation mechanisms have been used for the multi-valent transition metal ions and cluster binding energies have been considered. Simulations show a significant energetic gain when doping occurs at Ti sites in the face sharing dimers (Ti{sub 2} sites) of the hexagonal polymorph compared with the doping of the cubic polymorph. This energetic difference between the two polymorphs is true for all transition metals tested and all charge states and in the case of tri- and tetra-valent dopants negative solution energies are found for the hexagonal polymorph suggesting actual polymorph stabilisation occurs with the incorporation of these ions as observed experimentally. Oxidation during incorporation of Ni{sup 2+} and Fe{sup 3+} ions has also been considered. - Graphical abstract: The representation of the strongest binding energy clusters for tri-valent dopants—(a) Ti{sub 2}/O{sub 1} cluster and (b) Ti{sub 2}/O{sub 2} cluster. Highlights: ► Classical simulations show a significant energetic gain when doping occurs at Ti sites in the face sharing dimers (Ti2 sites) of the hexagonal polymorph compared with the doping of the cubic polymorph. ► This energetic difference between the two polymorphs is true for all transition metals tested and all charge states. ► In the case of tri- and tetra- valent dopants negative solution energies are found for the hexagonal polymorph suggesting actual polymorph stabilisation occurs with the incorporation of these ions.

  1. Stabilisation of strawberry (Fragaria x ananassa Duch.) anthocyanins by different pectins.

    PubMed

    Buchweitz, M; Speth, M; Kammerer, D R; Carle, R

    2013-12-01

    The objective of the present study was to evaluate the effects of different pectins on strawberry anthocyanins in viscous model solutions at pH 3.0. For this purpose, low esterified amidated, low and high methyl esterified citrus and apple pectins, and a sugar beet pectin (SBP), respectively, were added to strawberry extracts. The latter were predominantly composed of pelargonidin-glycosides, containing either reduced (E-1) or original amounts of non-anthocyanin phenolics (E-2). Model systems were stored for 18 weeks at 20±0.5 °C protected from light, and anthocyanins were quantitated in regular intervals by HPLC-DAD analyses. Half-life (t1/2) and destruction (D) values were calculated based on first-order kinetics. Generally, significant differences in pigment retention could be ascribed to differing pectin sources, while variation in the degree of esterification and amidation, respectively, had negligible effects. Compared to systems without added pectin, apple pectins and SPB enhanced anthocyanin stability moderately, while stabilising effects of citrus pectins were poor or even imperceptible. Generally, the amount of non-anthocyanin phenolics and the addition of citrate did not markedly affect anthocyanin stability. However, pectins had no influence on total phenolic contents (Folin-Ciocalteu assay) and antioxidant capacities (FRAP and TEAC assay) of strawberry phenolics over time. For pelargonidin-3-glucoside and -rutinoside largely consistent stabilities were found in all model systems. In contrast, pelargonidin-3-malonylglucoside was less stable in the blank, and stabilisation by pectins was always negligible. The findings of the present study are contrary to results reported previously for the stabilisation of cyanidin- and delphinidin-glycosides in similar model systems prepared with black currant extracts, indicating a high impact of the number of hydroxyl groups in the anthocyanin B-ring. PMID:23871051

  2. Spectroscopic properties of erbium-doped yttria-stabilised zirconia crystals

    SciTech Connect

    Ryabochkina, P A; Sidorova, N V; Ushakov, S N; Lomonova, E E

    2014-02-28

    Yttria-stabilised zirconia crystals ZrO{sub 2} – Y{sub 2}O{sub 3} (6 mol %) – Er{sub 2}O{sub 3} (5.85 mol %) are grown by directional crystallisation in a cold container using direct RF melting. The spectral and luminescent properties of these crystals are studied in order to use them as active media of solid state lasers emitting in the wavelength range 1.5 – 1.7 μm. (active media)

  3. Mathematical modelling of postbuckling in a slender beam column for active stabilisation control with respect to uncertainty

    NASA Astrophysics Data System (ADS)

    Enss, Georg C.; Platz, Roland; Hanselka, Holger

    2012-04-01

    Buckling is an important design constraint in light-weight structures as it may result in the collapse of an entire structure. When a mechanical beam column is loaded above its critical buckling load, it may buckle. In addition, if the actual loading is not fully known, stability becomes highly uncertain. To control uncertainty in buckling, an approach is presented to actively stabilise a slender flat column sensitive to buckling. For this purpose, actively controlled forces applied by piezoelectric actuators located close to the column's clamped base stabilise the column against buckling at critical loading. In order to design a controller to stabilise the column, a mathematical model of the postcritically loaded system is needed. Simulating postbuckling behaviour is important to study the effect of axial loads above the critical axial buckling load within active buckling control. Within this postbuckling model, different kinds of uncertainty may occur: i) error in estimation of model parameters such as mass, damping and stiffness, ii) non-linearities e. g. in the assumption of curvature of the column's deflection shapes and many more. In this paper, numerical simulations based on the mathematical model for the postcritically axially loaded column are compared to a mathematical model based on experiments of the actively stabilised postcritically loaded real column system using closed loop identification. The motivation to develop an experimentally validated mathematical model is to develop of a model based stabilising control algorithm for a real postcritically axially loaded beam column.

  4. On asymptotic stabilisation of a chain of integrators with nonlinearity and an uncertain input delay by output feedback

    NASA Astrophysics Data System (ADS)

    Choi, Ho-Lim

    2014-12-01

    In this paper, we provide an output feedback solution over one given by Choi and Lim [Systems & Control Letters, 59(6), 374-379 (2010)] under more generalised system set-up. More specifically, we consider a stabilisation problem of a chain of integrators that has nonlinearity and an uncertain delay in the input by output feedback. The nonlinearity is classified into four types. Then, we propose a memoryless output feedback controller which contains a gain-scaling factor to adjust controller gains depending on the given nonlinearity type. Our stability analysis shows that the controlled system has unique stabilisation result associated with each type of nonlinearity. Our result provides a new aspect to the stabilisation problem of nonlinear time-delay systems and broadens the existing control results of time-delay systems. Two examples are given for illustration.

  5. Immobilised native plant cysteine proteases: packed-bed reactor for white wine protein stabilisation.

    PubMed

    Benucci, Ilaria; Lombardelli, Claudio; Liburdi, Katia; Acciaro, Giuseppe; Zappino, Matteo; Esti, Marco

    2016-02-01

    This research presents a feasibility study of using a continuous packed-bed reactor (PBR), containing immobilised native plant cysteine proteases, as a specific and mild alternative technique relative to the usual bentonite fining for white wine protein stabilisation. The operational parameters for a PBR containing immobilised bromelain (PBR-br) or immobilised papain (PBR-pa) were optimised using model wine fortified with synthetic substrate (Bz-Phe-Val-Arg-pNA). The effectiveness of PBR-br, both in terms of hazing potential and total protein decrease, was significantly higher than PBR-pa, in all the seven unfined, white wines used. Among the wines tested, Sauvignon Blanc, given its total protein content as well as its very high intrinsic instability, was selected as a control wine to evaluate the effect of the treatment on wine as to its soluble protein profile, phenolic composition, mineral component, and sensory properties. The treatment in a PBR containing immobilised bromelain appeared effective in decreasing both wine hazing potential and total protein amount, while it did not significantly affect the phenol compounds, the mineral component nor the sensory quality of wine. The enzymatic treatment in PBR was shown to be a specific and mild technique for use as an alternative to bentonite fining for white wine protein stabilisation. PMID:27162393

  6. Visually controlled spatial stabilisation of the human head: compensation for the eye's limited ability to roll.

    PubMed

    Gresty, M A; Bronstein, A M

    1992-06-01

    During movements of the head in pitch (yes-yes) or in yaw (no-no) the visual scene appears stable whereas rolling the head (ear down to shoulder) induces an apparent swinging of the world in the opposite direction. This visual instability is due to the inadequacy, in the roll plane, of the reflex eye movements which are effective in stabilising the eyes in space during pitch and yaw. We investigated whether head is stabilised in roll to protect against visual instability. Human subjects were fixed in a gimbal with their heads free and were exposed to unpredictable oscillatory movement in pitch and, for comparison roll, about axes aligned with the head. With vision, during roll motion, the head was displaced from upright by approximately half the amplitude of the gimbal motion. In comparison, with eyes closed relying on vestibular and proprioceptive cues and during pitch stimuli with or without vision, the magnitude of head displacement from upright was approximately equal to that to the gimbal. The superior head stability in roll, dependent on a visual frame of reference, compensates for poverty of eye movement in this plane. PMID:1407702

  7. Metastable SUSY breaking, de Sitter moduli stabilisation and Kähler moduli inflation

    NASA Astrophysics Data System (ADS)

    Krippendorf, Sven; Quevedo, Fernando

    2009-11-01

    We study the influence of anomalous U(1) symmetries and their associated D-terms on the vacuum structure of global field theories once they are coupled to Script N = 1 supergravity and in the context of string compactifications with moduli stabilisation. In particular, we focus on a IIB string motivated construction of the ISS scenario and examine the influence of one additional U(1) symmetry on the vacuum structure. We point out that in the simplest one-Kähler modulus compactification, the original ISS vacuum gets generically destabilised by a runaway behaviour of the potential in the modulus direction. In more general compactifications with several Kähler moduli, we find a novel realisation of the LARGE volume scenario with D-term uplifting to de Sitter space and both D-term and F-term supersymmetry breaking. The structure of soft supersymmetry breaking terms is determined in the preferred scenario where the standard model cycle is not stabilised non-perturbatively and found to be flavour universal. Our scenario also provides a purely supersymmetric realisation of Kähler moduli (blow-up and fibre) inflation, with similar observational properties as the original proposals but without the need to include an extra (non-SUSY) uplifting term.

  8. A Scott bench with ergonomic thorax stabilisation pad improves body posture during preacher arm curl exercise.

    PubMed

    Biscarini, Andrea; Benvenuti, Paolo; Busti, Daniele; Zanuso, Silvano

    2016-05-01

    We assessed whether the use of an ergonomic thorax stabilisation pad, during the preacher arm curl exercise, could significantly reduce the excessive shoulder protraction and thoracic kyphosis induced by the standard flat pad built into the existing preacher arm curl equipment. A 3D motion capture system and inclinometers were used to measure shoulder protraction and thoracic kyphosis in 15 subjects performing preacher arm curl with a plate-loaded machine provided with the standard flat pad. The same measures were repeated after replacing the flat pad with a new ergonomic pad, specifically designed to accommodate the thorax profile and improve body posture. Pad replacement significantly (p < 0.001) reduced shoulder protraction (from [Formula: see text] to [Formula: see text]) and thoracic kyphosis (from [Formula: see text] to [Formula: see text]), enabling postural and functional improvements within the entire spine, shoulder girdle and rib cage. The ergonomic pad may potentially allow a more effective training, prevent musculoskeletal discomfort and reduce the risk of injury. Practitioner summary: We have designed an ergonomic thorax stabilisation pad for the preacher arm curl exercise. The new ergonomic pad improves the poor posture conditions induced by the standard flat pad and may potentially allow a more effective training, prevent musculoskeletal discomfort, improve the breathing function and reduce the risk of injury. PMID:26226165

  9. Benefits of helmet-mounted display image stabilisation under whole-body vibration.

    PubMed

    Wells, M J; Griffin, M J

    1984-01-01

    The effects of whole-body vertical vibration in the range 2.5-25 Hz on visual performance with two types of raster scan helmet-mounted display have been determined. The benefit of an image stabilisation system on numeral reading performance during vibration was also assessed with both display systems. Increases in mean reading time of over 130%/m . s-2 R.M.S. and increases in percentage reading error of more than 30%/m . s-2 R.M.S. were recorded with unstabilised displays. With vertical and horizontal image stabilisation, these decrements in performance were reduced to less than 40%/m . s-2 R.M.S. increase in reading time and less than 10%/m . s-2 R.M.S. increase in reading error. Data on the transmission of vibration from the seat to the head and from the head to the helmet were also obtained. These indicate a relation between biodynamic behaviour and visual performance during vibration. PMID:6696690

  10. Sludge digestion instead of aerobic stabilisation - a cost benefit analysis based on experiences in Germany.

    PubMed

    Gretzschel, Oliver; Schmitt, Theo G; Hansen, Joachim; Siekmann, Klaus; Jakob, Jürgen

    2014-01-01

    As a consequence of a worldwide increase of energy costs, the efficient use of sewage sludge as a renewable energy resource must be considered, even for smaller wastewater treatment plants (WWTPs) with design capacities between 10,000 and 50,000 population equivalent (PE). To find the lower limit for an economical conversion of an aerobic stabilisation plant into an anaerobic stabilisation plant, we derived cost functions for specific capital costs and operating cost savings. With these tools, it is possible to evaluate if it would be promising to further investigate refitting aerobic plants into plants that produce biogas. By comparing capital costs with operation cost savings, a break-even point for process conversion could be determined. The break-even point varies depending on project specific constraints and assumptions related to future energy and operation costs and variable interest rates. A 5% increase of energy and operation costs leads to a cost efficient conversion for plants above 7,500 PE. A conversion of WWTPs results in different positive effects on energy generation and plant operations: increased efficiency, energy savings, and on-site renewable power generation by digester gas which can be used in the plant. Also, the optimisation of energy efficiency results in a reduction of primary energy consumption. PMID:24473316

  11. Stabilisation of amorphous furosemide increases the oral drug bioavailability in rats.

    PubMed

    Nielsen, Line Hagner; Rades, Thomas; Müllertz, Anette

    2015-07-25

    A glass solution of the amorphous sodium salt of furosemide (ASSF) and polyvinylpyrrolidone (PVP) (80:20 w/w%) was prepared by spray drying. It was investigated if PVP was able to stabilise ASSF during storage and dissolution and whether this influenced the in vivo performance of the glass solution after oral dosing to rats. The glass solution had a glass transition temperature of 121.3 ± 0.5°C, which was significantly higher than that of the pure drug (101.2°C). ASSF in the glass solution was stable for at least 168 days when stored at 20°C and 0% relative humidity. The glass solution exhibited fast dissolution in simulated intestinal medium, pH 6.5; the intrinsic dissolution rate was found to be 10.1 ± 0.6 mg/cm(2)/min, which was significantly faster than the pure ASSF. When investigating the stability during dissolution in stimulated intestinal medium at pH 6.5, the ASSF in the glass solution showed signs of crystallinity after 1 min of dissolution, but crystallised to a lesser extent than pure ASSF. The stabilising effect of PVP on ASSF, led to improved relative oral bioavailability in rats of 263%, when compared to the pure ASSF. PMID:26026252

  12. D-branes at del Pezzo singularities: global embedding and moduli stabilisation

    NASA Astrophysics Data System (ADS)

    Cicoli, Michele; Krippendorf, Sven; Mayrhofer, Christoph; Quevedo, Fernando; Valandro, Roberto

    2012-09-01

    In the context of type IIB string theory we combine moduli stabilisation and model building on branes at del Pezzo singularities in a fully consistent global compactification. By means of toric geometry, we classify all the Calabi-Yau manifolds with 3 < h 1,1 < 6 which admit two identical del Pezzo singularities mapped into each other under the orientifold involution. This effective singularity hosts the visible sector containing the Standard Model while the Kähler moduli are stabilised via a combination of D-terms, perturbative and non-perturbative effects supported on hidden sectors. We present concrete models where the visible sector, containing the Standard Model, gauge and matter content, is built via fractional D3-branes at del Pezzo singularities and all the Kähler moduli are fixed providing an explicit realisation of both KKLT and LARGE volume scenarios, the latter with D-term uplifting to de Sitter minima. We perform the consistency checks for global embedding such as tadpole, K-theory charges and Freed-Witten anomaly cancellation. We briefly discuss phenomenological and cosmological implications of our models.

  13. Lipid oxidation in minced beef meat with added Krebs cycle substrates to stabilise colour.

    PubMed

    Yi, G; Grabež, V; Bjelanovic, M; Slinde, E; Olsen, K; Langsrud, O; Phung, V T; Haug, A; Oostindjer, M; Egelandsdal, B

    2015-11-15

    Krebs cycle substrates (KCS) can stabilise the colour of packaged meat by oxygen reduction. This study tested whether this reduction releases reactive oxygen species that may lead to lipid oxidation in minced meat under two different storage conditions. KCS combinations of succinate and glutamate increased peroxide forming potential (PFP, 1.18-1.32 mmol peroxides/kg mince) and thiobarbituric acid reactive substances (TBARS, 0.30-0.38 mg malondialdehyde (MDA) equivalents/kg mince) under low oxygen storage conditions. Both succinate and glutamate were metabolised. Moreover, under high oxygen (75%) storage conditions, KCS combinations of glutamate, citrate and malate increased PFP (from 1.22 to 1.29 mmol peroxides/kg) and TBARS (from 0.37 to 0.40 mg MDA equivalents/kg mince). Only glutamate was metabolised. The KCS combinations that were added to stabilise colour were metabolised during storage, and acted as pro-oxidants that promoted lipid oxidation in both high and low oxygen conditions. PMID:25977064

  14. Comparisons of operating envelopes for contaminated soil stabilised/solidified with different cementitious binders.

    PubMed

    Kogbara, Reginald B; Al-Tabbaa, Abir; Stegemann, Julia A

    2014-03-01

    This work initiated the development of operating envelopes for stabilised/solidified contaminated soils. The operating envelopes define the range of operating variables for acceptable performance of the treated soils. The study employed a soil spiked with 3,000 mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000 mg/kg of diesel. The binders used for treatment involved Portland cement (CEMI), pulverised fuel ash (PFA), ground granulated blast furnace slag (GGBS) and hydrated lime (hlime). The specific binder formulations were CEMI, CEMI/PFA = 1:4, CEMI/GGBS = 1:9 and hlime/GGBS = 1:4. The water contents employed ranged from 13 % to 21 % (dry weight), while binder dosages ranged from 5 % to 20 % (w/w). We monitored the stabilised/solidified soils for up to 84 days using different performance tests. The tests include unconfined compressive strength (UCS), hydraulic conductivity, acid neutralisation capacity (ANC) and pH-dependent leachability of contaminants. The water content range resulted in adequate workability of the mixes but had no significant effect on leachability of contaminants. We produced design charts, representing operating envelopes, from the results generated. The charts establish relationships between water content, binder dosage and UCS; and binder dosage, leachant pH and leachability of contaminants. The work also highlights the strengths and weaknesses of the different binder formulations. PMID:24243092

  15. Chemistry of guanidinate-stabilised diboranes: transition-metal-catalysed dehydrocoupling and hydride abstraction.

    PubMed

    Wagner, Arne; Litters, Sebastian; Elias, Jana; Kaifer, Elisabeth; Himmel, Hans-Jörg

    2014-09-22

    Herein, we analyse the catalytic boron-boron dehydrocoupling reaction that leads from the base-stabilised diborane(6) [H2 B(hpp)]2 (hpp=1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate) to the base-stabilised diborane(4) [H2 B(hpp)]2 . A number of potential transition-metal precatalysts was studied, including transition-metal complexes of the product diborane(4). The synthesis and structural characterisation of two further examples of such complexes is presented. The best results for the dehydrocoupling reactions were obtained with precatalysts of Group 9 metals in the oxidation state of +I. The active catalyst is formed in situ through a multistep process that involves reduction of the precatalyst by the substrate [H2 B(hpp)]2 , and mechanistic investigations indicate that both heterogeneous and (slower) homogeneous reaction pathways play a role in the dehydrocoupling reaction. In addition, hydride abstraction from [H2 B(hpp)]2 and related diboranes is analysed and the possibility for subsequent deprotonation is discussed by probing the protic character of the cationic boron-hydrogen compounds with NMR spectroscopic analysis. PMID:25168516

  16. Stabilisation of biodried municipal solid waste fine fraction in landfill bioreactor.

    PubMed

    Grilli, Selene; Giordano, Andrea; Spagni, Alessandro

    2012-09-01

    The biodrying process of solid waste is a pre-treatment for the bio-stabilisation of the municipal solid waste. This study aims to investigate the fate of the municipal solid waste fine fraction (MSWFF) resulting from a biodrying treatment when disposed in landfills that are operated as bioreactors. Biodried MSWFF was apparently stable due to its low moisture content that slows down the microbial activity. The lab-scale anaerobic bioreactors demonstrated that a proper moisture content leads to a complete biodegradation of the organic matter contained in the biodried MSWFF. Using a pilot-scale landfill bioreactor (LBR), MSWFF stabilisation was achieved, suggesting that the leachate recirculation could be an effective approach to accomplish the anaerobic biodegradation and biostabilisation of biodried MSWFF after landfilling. The biostabilisation of the material resulting from the LBR treatment was confirmed using anaerobic and aerobic stability indices. All anaerobic and aerobic indices showed a stability increase of approximately 80% of the MSWFF after treatment in the LBR. The similar values of OD7 and BMP stability indices well agree with the relationship between the aerobic and anaerobic indices reported in literature. PMID:22633467

  17. Hippo Stabilises Its Adaptor Salvador by Antagonising the HECT Ubiquitin Ligase Herc4

    PubMed Central

    Aerne, Birgit L.; Gailite, Ieva; Sims, David; Tapon, Nicolas

    2015-01-01

    Signalling through the Hippo (Hpo) pathway involves a kinase cascade, which leads to the phosphorylation and inactivation of the pro-growth transcriptional co-activator Yorkie (Yki). Despite the identification of a large number of pathway members and modulators, our understanding of the molecular events that lead to activation of Hpo and the downstream kinase Warts (Wts) remain incomplete. Recently, targeted degradation of several Hpo pathway components has been demonstrated as a means of regulating pathway activity. In particular, the stability of scaffold protein Salvador (Sav), which is believed to promote Hpo/Wts association, is crucially dependent on its binding partner Hpo. In a cell-based RNAi screen for ubiquitin regulators involved in Sav stability, we identify the HECT domain protein Herc4 (HECT and RLD domain containing E3 ligase) as a Sav E3 ligase. Herc4 expression promotes Sav ubiquitylation and degradation, while Herc4 depletion stabilises Sav. Interestingly, Hpo reduces Sav/Herc4 interaction in a kinase-dependent manner. This suggests the existence of a positive feedback loop, where Hpo stabilises its own positive regulator by antagonising Herc4-mediated degradation of Sav. PMID:26125558

  18. Outer membrane protein F stabilised with minimal amphipol forms linear arrays and LPS-dependent 2D crystals.

    PubMed

    Arunmanee, Wanatchaporn; Harris, J Robin; Lakey, Jeremy H

    2014-10-01

    Amphipols (APol) are polymers which can solubilise and stabilise membrane proteins (MP) in aqueous solutions. In contrast to conventional detergents, APol are able to keep MP soluble even when the free APol concentration is very low. Outer membrane protein F (OmpF) is the most abundant MP commonly found in the outer membrane (OM) of Escherichia coli. It plays a vital role in the transport of hydrophilic nutrients, as well as antibiotics, across the OM. In the present study, APol was used to solubilise OmpF to characterize its interactions with molecules such as lipopolysaccharides (LPS) or colicins. OmpF was reconstituted into APol by the removal of detergents using Bio-Beads followed by size-exclusion chromatography (SEC) to remove excess APol. OmpF/APol complexes were then analysed by SEC, dynamic light scattering (DLS) and transmission electron microscopy (TEM). TEM showed that in the absence of free APol-OmpF associated as long filaments with a thickness of ~6 nm. This indicates that the OmpF trimers lie on their sides on the carbon EM grid and that they also favour side by side association. The formation of filaments requires APol and occurs very rapidly. Addition of LPS to OmpF/APol complexes impeded filament formation and the trimers form 2D sheets which mimic the OM. Consequently, free APol is undoubtedly required to maintain the homogeneity of OmpF in solutions, but 'minimum APol' provides a new phase, which can allow weaker protein-protein and protein-lipid interactions characteristic of native membranes to take place and thus control 1D-2D crystallisation. PMID:24585057

  19. The effect of environmental conditions and soil physicochemistry on phosphate stabilisation of Pb in shooting range soils.

    PubMed

    Sanderson, Peter; Naidu, Ravi; Bolan, Nanthi

    2016-04-01

    The stabilisation of Pb in the soil by phosphate is influenced by environmental conditions and physicochemical properties of the soils to which it is applied. Stabilisation of Pb by phosphate was examined in four soils under different environmental conditions. The effect of soil moisture and temperature on stabilisation of Pb by phosphate was examined by measurement of water extractable and bioaccessible Pb, sequential fractionation and X-ray absorption spectroscopy. The addition of humic acid, ammonium nitrate and chloride was also examined for inhibition or improvement of Pb stability with phosphate treatment. The effect of moisture level varied between soils. In soil MB and DA a soil moisture level of 50% water holding capacity was sufficient to maximise stabilisation of Pb, but in soil TV and PE reduction in bioaccessible Pb was inhibited at this moisture level. Providing moisture at twice the soil water holding capacity did not enhance the effect of phosphate on Pb stabilisation. The difference of Pb stability as a result of incubating phosphate treated soils at 18 °C and 37 °C was relatively small. However wet-dry cycles decreased the effectiveness of phosphate treatment. The reduction in bioaccessible Pb obtained was between 20 and 40% with the most optimal treatment conditions. The reduction in water extractable Pb by phosphate was substantial regardless of incubation conditions and the effect of different temperature and soil moisture regimes was not significant. Selective sequential extraction showed phosphate treatment converted Pb in fraction 1 (exchangeable, acid and water soluble) to fraction 2 (reducible). There were small difference in fraction 4 (residual) Pb and fraction 1 as a result of treatment conditions. X-ray absorption spectroscopy of stabilised PE soil revealed small differences in Pb speciation under varying soil moisture and temperature treatments. The addition of humic acid and chloride produced the greatest effect on Pb speciation in

  20. The use of biogas plant fermentation residue for the stabilisation of toxic metals in agricultural soils

    NASA Astrophysics Data System (ADS)

    Geršl, Milan; Šotnar, Martin; Mareček, Jan; Vítěz, Tomáš; Koutný, Tomáš; Kleinová, Jana

    2015-04-01

    Our department has been paying attention to different methods of soil decontamination, including the in situ stabilisation. Possible reagents to control the toxic metals mobility in soils include a fermentation residue (FR) from a biogas plant. Referred to as digestate, it is a product of anaerobic decomposition taking place in such facilities. The fermentation residue is applied to soils as a fertiliser. A new way of its use is the in situ stabilisation of toxic metals in soils. Testing the stabilisation of toxic metals made use of real soil samples sourced from five agriculturally used areas of the Czech Republic with 3 soil samples taken from sites contaminated with Cu, Pb and Zn and 2 samples collected at sites of natural occurrence of Cu, Pb and Zn ores. All the samples were analysed using the sequential extraction procedure (BCR) (determine the type of Cu, Pb and Zn bonds). Stabilisation of toxic metals was tested in five soil samples by adding reagents as follows: dolomite, slaked lime, goethite, compost and fermentation residue. A single reagent was added at three different concentrations. In the wet state with the added reagents, the samples were left for seven days, shaken twice per day. After seven days, metal extraction was carried out: samples of 10 g soil were shaken for 2 h in a solution of 0.1M NH4NO3 at a 1:2.5 (g.ml-1), centrifuged for 15 min at 5,000 rpm and then filtered through PTFE 0.45 μm mesh filters. The extracts were analysed by ICP-OES. Copper The best reduction of Cu concentration in the extract was obtained at each of the tested sites by adding dolomite (10 g soil + 0.3 g dolomite). The concentration of Cu in the leachate decreased to 2.1-18.4% compare with the leachate without addition. Similar results were also shown for the addition of fermentation residue (10 g soil + 1 g FR). The Cu concentration in the leachate decreased to 16.7-26.8% compared with the leachate without addition. Lead The best results were achieved by adding

  1. Feedbacks and landscape-level vegetation dynamics.

    PubMed

    Bowman, David M J S; Perry, George L W; Marston, J B

    2015-05-01

    Alternative stable-state theory (ASS) is widely accepted as explaining landscape-level vegetation dynamics, such as switches between forest and grassland. This theory argues that webs of feedbacks stabilise vegetation composition and structure, and that abrupt state shifts can occur if stabilising feedbacks are weakened. However, it is difficult to identify stabilising feedback loops and the disturbance thresholds beyond which state changes occur. Here, we argue that doing this requires a synthetic approach blending observation, experimentation, simulation, conceptual models, and narratives. Using forest boundaries and large mammal extinctions, we illustrate how a multifaceted research program can advance understanding of feedback-driven ecosystem change. Our integrative approach has applicability to other complex macroecological systems controlled by numerous feedbacks where controlled experimentation is impossible. PMID:25837918

  2. Finite-time observer-based output-feedback control for the global stabilisation of the PVTOL aircraft with bounded inputs

    NASA Astrophysics Data System (ADS)

    Zavala-Río, A.; Fantoni, I.; Sanahuja, G.

    2016-05-01

    In this work, an output-feedback scheme for the global stabilisation of the planar vertical take-off and landing aircraft with bounded inputs is developed taking into account the positive nature of the thrust. The global stabilisation objective is proven to be achieved avoiding input saturation and by exclusively considering the system positions in the feedback. To cope with the lack of velocity measurements, the proposed algorithm involves a finite-time observer. The generalised versions of the involved finite-time stabilisers have not only permitted to solve the output-feedback stabilisation problem avoiding input saturation, but also provide additional flexibility in the control design that may be used in aid of performance improvements. With respect to previous approaches, the developed finite-time observer-based scheme guarantees the global stabilisation objective disregarding velocity measurements in a bounded input context. Simulation tests corroborate the analytical developments. The study includes further experimental results on an actual flying device.

  3. Anisotropic modulus stabilisation: strings at LHC scales with micron-sized extra dimensions

    NASA Astrophysics Data System (ADS)

    Cicoli, M.; Burgess, C. P.; Quevedo, F.

    2011-10-01

    We construct flux-stabilised Type IIB string compactifications whose extra dimensions have very different sizes, and use these to describe several types of vacua with a TeV string scale. Because we can access regimes where two dimensions are hierarchically larger than the other four, we find examples where two dimensions are micron-sized while the other four are at the weak scale in addition to more standard examples with all six extra dimensions equally large. Besides providing ultraviolet completeness, the phenomenology of these models is richer than vanilla large-dimensional models in several generic ways: ( i) they are supersymmetric, with supersymmetry broken at sub-eV scales in the bulk but only nonlinearly realised in the Standard Model sector, leading to no MSSM superpartners for ordinary particles and many more bulk missing-energy channels, as in supersymmetric large extra dimensions (SLED); ( ii) small cycles in the more complicated extra-dimensional geometry allow some KK states to reside at TeV scales even if all six extra dimensions are nominally much larger; ( iii) a rich spectrum of string and KK states at TeV scales; and ( iv) an equally rich spectrum of very light moduli exist having unusually small (but technically natural) masses, with potentially interesting implications for cosmology and astrophysics that nonetheless evade new-force constraints. The hierarchy problem is solved in these models because the extra-dimensional volume is naturally stabilised at exponentially large values: the extra dimensions are Calabi-Yau geometries with a 4D K3 or T 4-fibration over a 2D base, with moduli stabilised within the well-established LARGE-Volume scenario. The new technical step is the use of poly-instanton corrections to the superpotential (which, unlike for simpler models, are likely to be present on K3 or T 4-fibered Calabi-Yau compactifications) to obtain a large hierarchy between the sizes of different dimensions. For several scenarios we identify

  4. A novel approach for biomechanical spine analysis: Mechanical response of vertebral bone augmentation by kyphoplasty to stabilise thoracolumbar burst fractures.

    PubMed

    Germaneau, A; Vendeuvre, T; Saget, M; Doumalin, P; Dupré, J C; Brémand, F; Hesser, F; Couvertier, M; Brèque, C; Maxy, P; Roulaud, M; Monlezun, O; Rigoard, P

    2016-06-01

    Kyphoplasty has been shown as a well-established technique for spinal injuries. This technique allows a vertebral bone augmentation with a reduction of morbidity and does not involve any adjacent segment immobilisation. There is a lack of biomechanical information resulting in major gaps of knowledge such as: the evaluation of the "quality" of stabilisation provided by kyphoplasty as a standalone procedure in case of unstable fracture. Our objective is to analyse biomechanical response of spine segments stabilised by Kyphoplasty and PMMA cement after experiencing burst fractures. Six fresh-frozen cadaveric spine specimens constituted by five vertebra (T11-L3) and four disks were tested. A specific loading setup has been developed to impose pure moments corresponding to loadings of flexion-extension, lateral bending and axial rotation. Tests were performed on each specimen in an intact state and post kyphoplasty following a burst fracture. Strain measurements and motion variations of spinal unit are measured by a 3D optical method. Strain measurements on vertebral bodies after kyphoplasty shows a great primary stabilisation. Comparisons of mobility and angles variations between the intact and post kyphoplasty states do not highlight significant difference. Percutaneous kyphoplasty offers a good primary stability in case of burst fracture. Kinematics analysis during physiological movements shows that this stabilisation solution preserve disk mobility in each adjacent spinal unit. PMID:26896762

  5. A constructive method to static output stabilisation of Markov jump systems

    NASA Astrophysics Data System (ADS)

    Shen, Mouquan; Fei, Shumin

    2015-05-01

    This paper is concerned with the static output feedback stabilisation of Markov jump systems. Transition probabilities are assumed to be incomplete, namely, they may be known, uncertain with known lower and upper bounds and unknown. To linearise the nonlinearities induced by unknown transition probabilities, a linearisation is developed. To solve the static output feedback problem by means of linear matrix inequalities, a constructive method is proposed to separate the controller gain matrices from Lyapunov variables. Based on the linearisation and the separation, sufficient conditions are established to guarantee that the closed-loop system is stochastically stable by the designed static output feedback controller. The obtained results are further extended to deal with norm-bounded or polytopic uncertainties on system matrices. Numerical examples are given to demonstrate the effectiveness of the proposed method.

  6. Inacessible Andean sites reveal land-use induced stabilisation of soil organic carbon

    NASA Astrophysics Data System (ADS)

    Heitkamp, Felix; Maqsood, Shafique; Sylvester, Steven; Kessler, Michael; Jungkunst, Hermann

    2015-04-01

    Human activity affects properties and development of ecosystems across the globe to such a degree that it is challenging to get baseline values for undisturbed ecosystems. This is especially true for soils, which are affected by land-use history and hold a legacy of past human interventions. Therefore, it is still largely unknown how soil would have developed "naturally" and if processes of organic matter stabilisation would be different in comparison to managed soils. Here, we show undisturbed soil development, i.e., the processes of weathering and accumulation of soil organic carbon (SOC), by comparing pristine with grazed sites in the high Andes (4500 m) of southern Peru. We located study plots on a large ledge (0.2 km²) that is only accessible with mountaineering equipment. Plots with pristine vegetation were compared to rangeland plots that were constantly under grazing management for at least four millennia. All "state factors"; climate, potential biota, topography, parent material and time; besides "land-use" were, therefore, identical. Vegetation change, induced by grazing management, led to lower vegetation cover of the soil, thereby increasing soil surface temperatures and soil acidification. Both factors increased weathering in rangeland soils, as indicated by the presence of pedogenic oxides, especially amorphous Al-(oxy)hydroxides (oxalate-extractable Al). Higher losses of base cations (K, Na, Ca) and lower pH-values were related to a low base saturation of exchange sites in rangelands. Therefore, rangeland soils were classified as Umbrisol, whereas soils under pristine vegetation were classified as Phaeozeme. All profiles were rich in SOC (100 to 126 g kg-1) with no significant differences in concentrations or stocks. SOC of rangeland soils was, however, less available for microorganisms (proportion of microbial C on SOC: 1.8 vs. 0.6% in pristine and rangeland soils, respectively) and showed higher stability against thermal degradation. Reasons for

  7. Post-/γ-irradiation reactions in vitamin E stabilised and unstabilised HDPE

    NASA Astrophysics Data System (ADS)

    Mallégol, J.; Carlsson, D. J.; Deschênes, L.

    2001-12-01

    The oxidation of high density polyethylene (HDPE), both unstabilised and vitamin E stabilised, has been studied by infrared (IR) and electron paramagnetic resonance (EPR) spectroscopies in the period following γ-irradiation at doses from 1 to 60 kGy (range of food sterilisation). Derivatisation by reaction with sulphur tetrafluoride was used to identify macro-ketone and carboxylic acid components of the overlapped IR carbonyl region. Oxidation continued for several hundred hours after the cessation of irradiation as shown by the increase in hydroxyl, ketone and acid groups. Carboxylic acid groups are particularly important as a direct indication of backbone scission. Vitamin E, although an effective antioxidant during γ-irradiation, was less effective in reducing the post-irradiation changes, which are probably driven by migration of radical sites along the polymer backbone from within the crystalline phase to the amorphous/crystalline inter-phase, where they become oxygen accessible.

  8. Influence of interface stabilisers and surrounding aqueous phases on nematic liquid crystal shells.

    PubMed

    Noh, JungHyun; Reguengo De Sousa, Kevin; Lagerwall, Jan P F

    2016-01-14

    We investigate the nematic-isotropic (N-I) transition in shells of the liquid crystal 5CB, surrounded by aqueous phases that conventionally are considered to be immiscible with 5CB. The aqueous phases contain either sodium dodecyl sulfate (SDS) or polyvinyl alcohol (PVA) as stabiliser, the former additionally promoting homeotropic director alignment. For all shell configurations we find a depression of the clearing point compared to pure 5CB, indicating that a non-negligible fraction of the constituents of the surrounding phases enter the shell, predominantly water. In hybrid-aligned shells, with planar outer and homeotropic inner boundary (or vice versa), the N-I transition splits into two steps, with a consequent three-step textural transformation. We explain this as a result of the order-enhancing effect of a monolayer of radially aligned SDS molecules adsorbed at the homeotropic interface. PMID:26512764

  9. Stabilisation of bank slopes that are prone to liquefaction in ecologically sensitive areas.

    PubMed

    Nestler, P; Stoll, R D

    2001-01-01

    A consequence of lignite stripping in the Lusatia mining district (East Germany) is the backfilling of dumps that mainly consist of low-compacted fine and medium-grained sands. When the ground-water table, which had been lowered while stripping the coal, is rising again, these dumps might be affected by a settlement flow due to the liquefaction of soils. Common methods for stabilisation as, for instance, blasting or vibrator-jetting deep compaction, are not very useful in ecologically sensitive areas, where dumps have been afforested and embankment areas of residual lakes have developed into highly valuable biotopes. A new so-called air-impulse method in combination with directional horizontal drilling has been developed, which does not have a considerably negative impact on the vegetation during compaction. The experience gained during the first employment of this method at the lake "Katja", a residual lake of lignite stripping, is presented in this paper. PMID:11220180

  10. Input-output finite-time stabilisation of nonlinear stochastic system with missing measurements

    NASA Astrophysics Data System (ADS)

    Song, Jun; Niu, Yugang; Jia, Tinggang

    2016-09-01

    This paper considers the problem of the input-output finite-time stabilisation for a class of nonlinear stochastic system with state-dependent noise. The phenomenon of the missing measurements may occur when state signals are transmitted via communication networks. An estimating method is proposed to compensate the lost state information. And then, a compensator-based controller is designed to ensure the input-output finite-time stochastic stability (IO-FTSS) of the closed-loop system. Some parameters-dependent sufficient conditions are derived and the corresponding solving approach is given. Finally, numerical simulations are provided to demonstrate the feasibility and effectiveness of the developed IO-FTSS scheme.

  11. Comparing and validating models of driver steering behaviour in collision avoidance and vehicle stabilisation

    NASA Astrophysics Data System (ADS)

    Markkula, G.; Benderius, O.; Wahde, M.

    2014-12-01

    A number of driver models were fitted to a large data set of human truck driving, from a simulated near-crash, low-friction scenario, yielding two main insights: steering to avoid a collision was best described as an open-loop manoeuvre of predetermined duration, but with situation-adapted amplitude, and subsequent vehicle stabilisation could to a large extent be accounted for by a simple yaw rate nulling control law. These two phenomena, which could be hypothesised to generalise to passenger car driving, were found to determine the ability of four driver models adopted from the literature to fit the human data. Based on the obtained results, it is argued that the concept of internal vehicle models may be less valuable when modelling driver behaviour in non-routine situations such as near-crashes, where behaviour may be better described as direct responses to salient perceptual cues. Some methodological issues in comparing and validating driver models are also discussed.

  12. Remediation by in-situ solidification/stabilisation of Ardeer landfill, Scotland

    SciTech Connect

    Wyllie, M.; Esnault, A.; Barker, P.

    1997-12-31

    The Ardeer Landfill site at ICI Explosives factory on the west coast of Scotland had been a repository for waste from the site for 40 years. In order to safeguard the local environment ICI Explosives, with approval of Local Authorities and the Clyde River Purification Board put into action a programme of investigation and planning which culminated in the in-situ treatment of 10,000 m3 of waste within the landfill by a deep mixing method using the {open_quotes}Colmix{close_quotes} system. The paper describes in varying degrees of detail the remediation from investigation to the execution of the in-situ stabilisation and presents the post construction monitoring results.

  13. Synthesis of dense yttrium-stabilised hafnia pellets for nuclear applications by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Tyrpekl, Vaclav; Holzhäuser, Michael; Hein, Herwin; Vigier, Jean-Francois; Somers, Joseph; Svora, Petr

    2014-11-01

    Dense yttrium-stabilised hafnia pellets (91.35 wt.% HfO2 and 8.65 wt.% Y2O3) were prepared by spark plasma sintering consolidation of micro-beads synthesised by the “external gelation” sol-gel technique. This technique allows a preparation of HfO2-Y2O3 beads with homogenous yttria-hafnia solid solution. A sintering time of 5 min at 1600 °C was sufficient to produce high density pellets (over 90% of the theoretical density) with significant reproducibility. The pellets have been machined in a lathe to the correct dimensions for use as neutron absorbers in an experimental test irradiation in the High Flux Reactor (HFR) in Petten, Holland, in order to investigate the safety of americium based nuclear fuels.

  14. Molecular signatures of mood stabilisers highlight the role of the transcription factor REST/NRSF

    PubMed Central

    Warburton, Alix; Savage, Abigail L.; Myers, Paul; Peeney, David; Bubb, Vivien J.; Quinn, John P.

    2015-01-01

    Background The purpose of this study was to address the affects of mood modifying drugs on the transcriptome, in a tissue culture model, using qPCR arrays as a cost effective approach to identifying regulatory networks and pathways that might coordinate the cell response to a specific drug. Methods We addressed the gene expression profile of 90 plus genes associated with human mood disorders using the StellARray™ qPCR gene expression system in the human derived SH-SY5Y neuroblastoma cell line. Results Global Pattern Recognition (GPR) analysis identified a total of 9 genes (DRD3⁎, FOS†, JUN⁎, GAD1⁎†, NRG1⁎, PAFAH1B3⁎, PER3⁎, RELN⁎ and RGS4⁎) to be significantly regulated in response to cellular challenge with the mood stabilisers sodium valproate (⁎) and lithium (†). Modulation of FOS and JUN highlights the importance of the activator protein 1 (AP-1) transcription factor pathway in the cell response. Enrichment analysis of transcriptional networks relating to this gene set also identified the transcription factor neuron restrictive silencing factor (NRSF) and the oestrogen receptor as an important regulatory mechanism. Limitations Cell line models offer a window of what might happen in vivo but have the benefit of being human derived and homogenous with regard to cell type. Conclusions This data highlights transcription factor pathways, acting synergistically or separately, in the modulation of specific neuronal gene networks in response to mood stabilising drugs. This model can be utilised in the comparison of the action of multiple drug regimes or for initial screening purposes to inform optimal drug design. PMID:25451397

  15. Emulsions stabilised by whey protein microgel particles: towards food-grade Pickering emulsions.

    PubMed

    Destribats, Mathieu; Rouvet, Martine; Gehin-Delval, Cécile; Schmitt, Christophe; Binks, Bernard P

    2014-09-28

    We have investigated a new class of food-grade particles, whey protein microgels, as stabilisers of triglyceride-water emulsions. The sub-micron particles stabilized oil-in-water emulsions at all pH with and without salt. All emulsions creamed but exhibited exceptional resistance to coalescence. Clear correlations exist between the properties of the microgels in aqueous dispersion and the resulting emulsion characteristics. For conditions in which the particles were uncharged, fluid emulsions with relatively large drops were stabilised, whereas emulsions stabilized by charged particles contained smaller flocculated drops. A combination of optical microscopy of the drops and spectrophotometry of the resolved aqueous phase allowed us to estimate the interfacial adsorption densities of the particles using the phenomenon of limited coalescence. We deduce two classes of particle arrangement. Complete adsorption of the particles was obtained when they were neutral or when their charges were screened by salt resulting in at least one particle monolayer at the interface. By contrast, only around 50% of the particles adsorbed when they were charged with emulsion drops being covered by less than half a monolayer. These findings were supported by direct visualization of drop interfaces using cryo-scanning electron microscopy. Uncharged particles were highly aggregated and formed a continuous 2-D network at the interface. Otherwise particles organized as individual aggregates separated by particle-free regions. In this case, we suggest that some particles spread at the interface leading to the formation of a continuous protein membrane. Charged particles displayed the ability to bridge opposing interfaces of neighbouring drops to form dense particle disks protecting drops against coalescence; this is the main reason for the flocculation and stability of emulsions containing sparsely covered drops. PMID:24675994

  16. The incomprehensible success of the implant stabilised overdenture in the edentulous mandible: a literature review on transfer of chewing forces to bone surrounding implants.

    PubMed

    Chao, Y L; Meijer, H J; Van Oort, R P; Versteegh, P A

    1995-12-01

    The approach of implant stabilised overdentures has become one of the routine treatment modalities for compromised edentulous ridges. The purpose of this literature review is to analyze survival rates of loaded implants, occlusal forces and stress distributions of implant stabilised overdentures in edentulous mandibles and of fixed loaded implants at least over a medium-term period. which is comparable with fixed prostheses. Patients with implant stabilised overdentures and with fixed bridges on implants generate similar occlusal forces. The number of implants under a prosthetic construction seems to have less influence on stress distribution than design of the superstructure and related direction of forces. PMID:8603169

  17. Stabilisation of extremely As-rich mine processing waste at historic gold mines, New Zealand

    NASA Astrophysics Data System (ADS)

    Haffert, L.; Craw, D.

    2009-04-01

    The Prohibition Mill site, a historic gold mining sites in the South Islands, processed arsenopyrite-rich ore from 1938 - 1951. Roasting of the ore, which was part of the processing technique, produced arsenolite (As2O3) rich waste with up to 40 wt% As. This waste was discarded into the nearby wetland (up to 10 wt% As) and some arsenolite is also still exposed around the roaster system. The presence of arsenolite has several implications: (1) Arsenolite is soluble in the surficial environment and surface run-off can acquire up to 30 mg/L dissolved As within minutes. In wetland sediment, where reducing conditions and long residence time allow for equilibration of arsenolite and pore water, dissolved As concentrations can be up to 330 mg/L. (2) In the surficial environment, oxidation of AsIII derived from arsenolite dissolution causes acidification, lowering site pH to 3 - 4. High dissolved As concentrations and acidity in oxidising surface waters promote the precipitation of the secondary As mineral scorodite (FeAsO4•H2O) and a large volume of As (100 m3 at 10 - 30 wt% As) is currently immobilised as scorodite cement in the site substrate. Downstream dissolved As concentrations are directly dependent on the stability of the As minerals present. While exposure is the only substantial limitation on arsenolite dissolution, scorodite stability is sensitive to redox conditions, dissolved As concentrations and especially pH. In acidic conditions dissolved As in equilibrium with scorodite can theoretically be as low as 0.1 mg/L (e.g. pH 3), whereas in circum-neutral waters, maximum scorodite solubility can exceed 10 mg/L. Environmental changes, such as (a) external site neutralisation, (b) removal of exposed arsenolite resulting in lower dissolved As concentrations, or (c) promoting reducing conditions by capping the material with an impermeable layer, can destabilise scorodite. In order to maximise As stabilisation, the As-rich substrate should be maintained with low p

  18. Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame

    DOE PAGESBeta

    Karami, Shahram; Hawkes, Evatt R.; Talei, Mohsen; Chen, Jacqueline H.

    2015-07-23

    A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one-step chemistry model is employed with a mixture-fraction-dependent activation energy which can reproduce qualitatively the dependence of the laminar burning rate on the equivalence ratio that is typical of hydrocarbon fuels. The basic structure of the flame base is first examined and discussed in the context of earlier experimental studies of lifted flames. Several features previously observed in experiments are noted and clarified. Some other unobserved features are also noted. Comparison with previous DNS modelling of hydrogen flames reveals significant structural differences. The statistics of flow andmore » relative edge-flame propagation velocity components conditioned on the leading edge locations are then examined. The results show that, on average, the streamwise flame propagation and streamwise flow balance, thus demonstrating that edge-flame propagation is the basic stabilisation mechanism. Fluctuations of the edge locations and net edge velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional (2D) elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Suet al.(Combust. Flame, vol. 144 (3), 2006, pp. 494–512). However, the mechanism is not entirely 2D, and out-of-plane motion is needed to explain how flames escape the high-velocity inner region of the jet. Finally, the time-averaged structure is examined. A budget of terms in the transport equation for the product mass fraction is used to understand the stabilisation from a time-averaged perspective. The result of this analysis is found to be consistent with the instantaneous perspective. The budget reveals a fundamentally 2D structure, involving transport in both the streamwise and transverse

  19. Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame

    SciTech Connect

    Karami, Shahram; Hawkes, Evatt R.; Talei, Mohsen; Chen, Jacqueline H.

    2015-07-23

    A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one-step chemistry model is employed with a mixture-fraction-dependent activation energy which can reproduce qualitatively the dependence of the laminar burning rate on the equivalence ratio that is typical of hydrocarbon fuels. The basic structure of the flame base is first examined and discussed in the context of earlier experimental studies of lifted flames. Several features previously observed in experiments are noted and clarified. Some other unobserved features are also noted. Comparison with previous DNS modelling of hydrogen flames reveals significant structural differences. The statistics of flow and relative edge-flame propagation velocity components conditioned on the leading edge locations are then examined. The results show that, on average, the streamwise flame propagation and streamwise flow balance, thus demonstrating that edge-flame propagation is the basic stabilisation mechanism. Fluctuations of the edge locations and net edge velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional (2D) elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Suet al.(Combust. Flame, vol. 144 (3), 2006, pp. 494–512). However, the mechanism is not entirely 2D, and out-of-plane motion is needed to explain how flames escape the high-velocity inner region of the jet. Finally, the time-averaged structure is examined. A budget of terms in the transport equation for the product mass fraction is used to understand the stabilisation from a time-averaged perspective. The result of this analysis is found to be consistent with the instantaneous perspective. The budget reveals a fundamentally 2D structure, involving transport in both

  20. Selection of natural treatment processes for algae removal from stabilisation ponds effluents in Brasilia, using multicriterion methods.

    PubMed

    Neder, K D; Carneiro, G A; Queiroz, T R; de Souza, M A A

    2002-01-01

    A multicriterion methodology is used in the evaluation and selection of the most appropriate alternative(s) for removing algae from stabilisation ponds effluents in a case study in Brasilia. For this purpose, five different natural treatment processes are tested at pilot scale: rock filter, sand filter, floating aquatic plants, constructed wetlands, and overland flow. These pilot units were constructed in Brasilia and set in parallel, each one receiving a portion of the effluent that comes from an existing wastewater treatment plant composed of preliminary treatment, UASB reactors, and high-rate stabilisation ponds. Several evaluation criteria are used in order to relate the capabilities of the post-treatment processes to the multiple objectives in this case. Two multicriterion decision-aid methods--compromise programming and ELECTRE-III--are used to select the most satisfying processes. The top ranking alternatives are indicated for subsequent studies, considering the possible implementation of these technologies to existing plants. PMID:12361031

  1. Cerium reduction at the interface between ceria and yttria-stabilised zirconia and implications for interfacial oxygen non-stoichiometry

    SciTech Connect

    Song, Kepeng; Schmid, Herbert; Srot, Vesna; Aken, Peter A. van; Gilardi, Elisa; Gregori, Giuliano; Maier, Joachim; Du, Kui

    2014-03-01

    Epitaxial CeO{sub 2} films with different thickness were grown on Y{sub 2}O{sub 3} stabilised Zirconia substrates. Reduction of cerium ions at the interface between CeO{sub 2} films and yttria stabilised zirconia substrates is demonstrated using aberration-corrected scanning transmission electron microscopy combined with electron energy-loss spectroscopy. It is revealed that most of the Ce ions were reduced from Ce{sup 4+} to Ce{sup 3+} at the interface region with a decay of several nanometers. Several possibilities of charge compensations are discussed. Irrespective of the details, such local non-stoichiometries are crucial not only for understanding charge transport in such hetero-structures but also for understanding ceria catalytic properties.

  2. Reducing the conservatism of LMI-based stabilisation conditions for TS fuzzy systems using fuzzy Lyapunov functions

    NASA Astrophysics Data System (ADS)

    Faria, Flávio A.; Silva, Geraldo N.; Oliveira, Vilma A.

    2013-10-01

    In this article, the fuzzy Lyapunov function approach is considered for stabilising continuous-time Takagi-Sugeno fuzzy systems. Previous linear matrix inequality (LMI) stability conditions are relaxed by exploring further the properties of the time derivatives of premise membership functions and by introducing slack LMI variables into the problem formulation. The relaxation conditions given can also be used with a class of fuzzy Lyapunov functions which also depends on the membership function first-order time-derivative. The stability results are thus extended to systems with large number of rules under membership function order relations and used to design parallel-distributed compensation (PDC) fuzzy controllers which are also solved in terms of LMIs. Numerical examples illustrate the efficiency of the new stabilising conditions presented.

  3. Effect of human and simulated gastric juices on the digestion of whey proteins and carboxymethylcellulose-stabilised O/W emulsions.

    PubMed

    Malinauskytė, Ernesta; Ramanauskaitė, Jovita; Leskauskaitė, Daiva; Devold, Tove G; Schüller, Reidar B; Vegarud, Gerd E

    2014-12-15

    In this study, we analysed the impact of carboxymethylcellulose (CMC) on lipid digestion and physicochemical properties of whey proteins (WP)-stabilised emulsions during in vitro digestion with either artificial or human gastrointestinal juices. The emulsions were made by adsorbing WP on the fat droplets and subsequently adding CMC, which does not interact with the adsorbed proteins. The limited hydrolysis of lipids and their higher physical stability was recorded for WP-stabilised emulsions in the presence of CMC under simulated gastrointestinal conditions. The possible mechanism by which CMC lowers the digestion of WP-stabilised emulsions is related to the limited interaction of fat droplets with gastrointestinal fluids due to the extended thickening network formed by CMC in the continuous phase. The digestion of WP- and CMC-stabilised emulsions in the in vitro model with human gastric fluids led to greater lipid hydrolysis, although the enzymatic activity in both in vitro models was observed at the same level. PMID:25038655

  4. Near-infrared light-triggered irreversible aggregation of poly(oligo(ethylene glycol) methacrylate)-stabilised polypyrrole nanoparticles under biologically relevant conditions.

    PubMed

    Au, Kin Man; Chen, Mei; Armes, Steven P; Zheng, Nanfeng

    2013-11-18

    We report the use of near-infrared (NIR) radiation to trigger the irreversible flocculation of poly(oligo(ethylene glycol) methacrylate)-stabilised polypyrrole nanoparticles in physiological buffer. PMID:24089078

  5. Correction: Unexpected higher stabilisation of two classical antiaromatic frameworks with a ruthenium fragment compared to the osmium counterpart: origin probed by DFT calculations.

    PubMed

    Wu, Jingjing; Hao, Yulei; An, Ke; Zhu, Jun

    2016-01-25

    Correction for 'Unexpected higher stabilisation of two classical antiaromatic frameworks with a ruthenium fragment compared to the osmium counterpart: origin probed by DFT calculations' by Jingjing Wu et al., Chem. Commun., 2016, 52, 272-275. PMID:26699929

  6. Global sampled-data output feedback stabilisation for a class of nonlinear systems with unknown output function

    NASA Astrophysics Data System (ADS)

    Zhai, Jun-yong; Du, Hai-bo; Fei, Shu-min

    2016-03-01

    This paper discusses the problem of global sampled-data output feedback stabilisation for a class of nonlinear systems whose output function is unknown. A systematic design scheme is developed to construct a linear output feedback control law in sampled-data form. An explicit formula for the maximum allowable sampling period is computed to guarantee global stability of the uncertain nonlinear systems under the proposed controller with appropriate gains. Two examples are given to demonstrate the effectiveness of the proposed design procedure.

  7. The contribution of imaging and digitised data to mandibular reconstruction and implant stabilised occlusal rehabilitation: a case report.

    PubMed

    Watson, R M; Coward, T J; Clark, R K; Grindrod, S

    2001-03-24

    Different methods are recommended for the surgical reconstruction of the resected mandible. The advantages for implant stabilised prostheses in restoring the occlusion are recognised but few papers provide adequate data to identify the successful outcome of treatment. The literature is reviewed and the advantages of imaging together with the use of digitised data is highlighted by a case requiring rehabilitation with enhanced planning methods. PMID:11325155

  8. Re-use of stabilised flue gas ashes from solid waste incineration in cement-treated base layers for pavements.

    PubMed

    Cai, Zuansi; Jensen, Dorthe L; Christensen, Thomas H; Bager, Dirch H

    2003-02-01

    Fly ash from coal-burning power plants has been used extensively as a pozzolan and fine filler in concrete for many years. Laboratory experiments were performed investigating the effect of substituting the coal-based fly ash with chemically stabilised flue gas ashes (FGA) from waste incineration. Two types of FGA were treated by the Ferrox-process, which removes the majority of the easily soluble salts in the FGA and provides binding sites for heavy metals in terms of ferrihydrite. Cubes of cement treated base layer materials containing 5% stabilised FGA were cast, sealed and cured for two weeks. Cylinders (diameter 100 mm, length 150 mm) were drilled from these cubes for tank leaching experiments. Duplicate specimens were subject to compression strength testing and to tank leaching experiments. The compressive strength of the CTB fulfilled the Danish requirements for CTB, i.e. strength more than 5 MPa after 7 days. The tank leaching tests revealed that leaching of heavy metals was not significantly affected by the use of chemically stabilised flue gas ashes from waste incineration. Assuming that diffusion controls the leaching process it was calculated that less than 1% of the metals would leach during a 100-year period from a 0.5 m thick concrete slab exposed to water on one side. Leaching of the common ions Ca, Cl, Na and SO4 was increased 3-20 times from the specimens with chemically stabilised flue gas ashes from waste incineration. However, the quantities leached were still modest. These experiments suggest that FGA from waste incineration after Ferrox-treatment could be re-used in CTB without compromising the strength and leaching from the base layer. PMID:12667018

  9. Stereoselectivity in Oxyallyl–Furan 4+3 Cycloadditions: Control of Intermediate Conformations and Dispersive Stabilisation with Evans’ Oxazolidinones

    PubMed Central

    Krenske, Elizabeth H.; Lohse, Andrew G.; Antoline, Jennifer E.

    2011-01-01

    Chiral oxazolidinones were previously thought to control cycloaddition stereoselectivity by steric crowding of one face of the substrate. We have discovered that in 4+3 cycloaddition reactions of oxallyls, the stereoinduction is caused instead by stabilising CH–π interactions that lead to reaction at the more crowded face of the oxazolidinone. Density functional theory calculations on the 4+3 cycloadditions of oxazolidinone-substituted oxyallyls with furans establish unexpected transition state conformations and a new explanation of selectivity. PMID:21572919

  10. Global adaptive stabilisation for nonlinear systems with unknown control directions and input disturbance

    NASA Astrophysics Data System (ADS)

    Man, Yongchao; Liu, Yungang

    2016-05-01

    This paper addresses the global adaptive stabilisation via switching and learning strategies for a class of uncertain nonlinear systems. Remarkably, the systems in question simultaneously have unknown control directions, unknown input disturbance and unknown growth rate, which makes the problem in question challenging to solve and essentially different from those in the existing literature. To solve the problem, an adaptive scheme via switching and learning is proposed by skilfully integrating the techniques of backstepping design, adaptive learning and adaptive switching. One key point in the design scheme is the introduction of the learning mechanism, in order to compensate the unknown input disturbance, and the other one is the design of the switching mechanism, through tuning the design parameters online to deal with the unknown control directions, unknown bound and period of input disturbance and unknown growth rate. The designed controller guarantees that all the signals of the resulting closed-loop systems are bounded, and furthermore, the closed-loop system states globally converge to zero.

  11. Metal concentrations in lime stabilised, thermally dried and anaerobically digested sewage sludges.

    PubMed

    Healy, M G; Fenton, O; Forrestal, P J; Danaher, M; Brennan, R B; Morrison, L

    2016-02-01

    Cognisant of the negative debate and public sentiment about the land application of treated sewage sludges ('biosolids'), it is important to characterise such wastes beyond current regulated parameters. Concerns may be warranted, as many priority metal pollutants may be present in biosolids. This study represents the first time that extensive use was made of a handheld X-ray fluorescence (XRF) analyser to characterise metals in sludges, having undergone treatment by thermal drying, lime stabilisation, or anaerobic digestion, in 16 wastewater treatment plants (WWTPs) in Ireland. The concentrations of metals, expressed as mgkg(-1) dry solids (DS), which are currently regulated in the European Union, ranged from 11 (cadmium, anaerobically digested (AD) biosolids) to 1273mgkg(-1) (zinc, AD biosolids), and with the exception of lead in one WWTP (which had a concentration of 3696mgkg(-1)), all metals were within EU regulatory limits. Two potentially hazardous metals, antimony (Sb) and tin (Sn), for which no legislation currently exists, were much higher than their baseline concentrations in soils (17-20mgSbkg(-1) and 23-55mgSnkg(-1)), meaning that potentially large amounts of these elements may be applied to the soil without regulation. This study recommends that the regulations governing the values for metal concentrations in sludges for reuse in agriculture are extended to include Sb and Sn. PMID:26611400

  12. 360 degree decompresion and stabilisation of the C6-C7 cervical spine luxation - case study.

    PubMed

    Chrzanowski, Robert; Godlewski, Bartosz; Klauz, Grzegorz; Janeczko, Łukasz

    2012-01-01

    We present the operative technique employed in a young man with cervical spine luxation at the level of C6-C7 with clinical signs of damage to the spinal cord at the level of C5. In order to achieve an optimal therapeutic effect (decompression of neural structures and spinal stabilisation) during one surgical procedure, the positioning of the patient was changed twice during the procedure. Considering the positioning of the patient at the beginning of the procedure, the body position was changed by 360 degrees. The first part of the procedure was performed from an anterior approach with the patient in the supine position. It involved a C6-C7 discectomy and removal of the upper surface of the body of C7, which was protruding into the vertebral canal and compressing the spinal cord. Intraoperative inspection showed that a posterior approach was necessary to reduce the luxation. Therefore, for the second part of the operation, the patient was turned by 180 degrees and placed in the prone position. For the last (third) part of the surgical procedure, the patient was again turned by 180 degrees and placed in the supine position in order to insert an anterior spine fixator. We believe that a procedure utilising different surgical approaches and different positioning of the patient in order to achieve optimal therapeutic effect may be used in selected cases in everyday clinical practice. PMID:23382285

  13. Evaluation of biocompatible stabilised gelled soya bean oil nanoparticles as new hydrophobic reservoirs.

    PubMed

    Boudier, Ariane; Kirilov, Plamen; Franceschi-Messant, Sophie; Belkhelfa, Haouaria; Hadioui, Laila; Roques, Christine; Perez, Emile; Rico-Lattes, Isabelle

    2010-01-01

    Based on the organogel concept, in which an oil is trapped in a network of low-molecular-mass organic gelator fibres creating a gel, a formulation of gelled soya bean oil nanoparticles was evaluated for its capacity to form biocompatible hydrophobic reservoirs. The aqueous dispersions of nanoparticles were prepared by hot emulsification (T° > Tgel) and cooling at room temperature in the presence of polyethyleneimine (PEI). The dispersions were stabilised by the electrostatic interactions between the positively charged amino groups of the PEI and the negatively charged carboxylates of the gelator fibres present at the surface of the particles. The aqueous dispersions were highly stable (several months) and the gelled particles were able to entrap a hydrophobic fluorescent model molecule (Nile red), allowing testing in cells. The gelled oil nanoparticles were found to be biocompatible with the tested cells (keratinocytes) and had the ability to become rapidly internalised. Thus, organogel-based nanoparticles are a promising hydrophobic drug delivery system. PMID:20690792

  14. UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration.

    PubMed

    Chong, J Y; Aba, N F D; Wang, B; Mattevi, C; Li, K

    2015-01-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m(-2) h(-1) bar(-1) for water, and 0.14 to 7.5 L m(-2) h(-1) bar(-1) for acetone, with an unchanged low molecular weight cut off (~250 Da). PMID:26527173

  15. UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

    NASA Astrophysics Data System (ADS)

    Chong, J. Y.; Aba, N. F. D.; Wang, B.; Mattevi, C.; Li, K.

    2015-11-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m-2 h-1 bar-1 for water, and 0.14 to 7.5 L m-2 h-1 bar-1 for acetone, with an unchanged low molecular weight cut off (~250 Da).

  16. UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

    PubMed Central

    Chong, J. Y.; Aba, N. F. D.; Wang, B.; Mattevi, C.; Li, K.

    2015-01-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m−2 h−1 bar−1 for water, and 0.14 to 7.5 L m−2 h−1 bar−1 for acetone, with an unchanged low molecular weight cut off (~250 Da). PMID:26527173

  17. Stabilisation/solidification of APC residues from MSW incineration with hydraulic binders and chemical additives.

    PubMed

    Quina, Margarida J; Bordado, João C M; Quinta-Ferreira, Rosa M

    2014-01-15

    This study focuses on the stabilisation/solidification (S/S) treatment of air pollution control (APC) residues from municipal solid waste (MSW) incineration. Six formulations (T1-T6) were tested based on different cements as binders, for the immobilisation of pollutants and to prevent their entering into the environment at unacceptable rates. Soluble phosphates and silicates were considered in some cases to fix heavy metals. The performance of T1-T6 products was measured in terms of initial and final setting times, mechanical strength, total availability and leaching from S/S products. Two monolithic leaching tests were used to estimate emissions of pollutants over 48h and 64 days. The results showed that the setting time was reduced when soluble phosphates were used. Moreover, although all the treatments have met the threshold of 1MPa for unconfined compressive strength, this parameter was significantly reduced due to matrix dissolution during immersion. After three cycles of leaching, the limit of 10% for solubilisation was exceeded for all treatments with the exception of T5 (with phosphates). This study demonstrated that the S/S treatment used at the industrial level can be improved with respect to toxic heavy metals, by using soluble silicates or phosphates, but not regarding soluble salts. PMID:24291664

  18. Chemical stabilisation of lead in shooting range soils with phosphate and magnesium oxide: Synchrotron investigation.

    PubMed

    Sanderson, Peter; Naidu, Ravi; Bolan, Nanthi; Lim, Jung Eun; Ok, Yong Sik

    2015-12-15

    Three Australian shooting range soils were treated with phosphate and magnesium oxide, or a combination of both to chemically stabilize Pb. Lead speciation was determined after 1 month ageing by X-ray absorption spectroscopy combined with linear combination fitting in control and treated soils. The predominant Pb species in untreated soils were iron oxide bound Pb, humic acid bound Pb and the mineral litharge. Treatment with phosphate resulted in substantial pyromorphite formation in two of the soils (TV and PE), accounting for up to 38% of Pb species present, despite the addition of excess phosphate. In MgO treated soils only, up to 43% of Pb was associated with MgO. Litharge and Pb hydroxide also formed as a result of MgO addition in the soils. Application of MgO after P treatment increased hydroxypyromorphite/pyromorphite formation relative to soils teated with phosphate only. X-ray diffraction and Scanning electron microscopy revealed PbO precipitate on the surface of MgO. Soil pH, (5.3-9.3) was an important parameter, as was the solubility of existing Pb species. The use of direct means of determination of the stabilisation of metals such as by X-ray absorption spectroscopy is desirable, particularly in relation to understanding long term stability of the immobilised contaminants. PMID:26150282

  19. Cooperation of distinct Rac-dependent pathways to stabilise E-cadherin adhesion.

    PubMed

    Erasmus, Jennifer C; Welsh, Natalie J; Braga, Vania M M

    2015-09-01

    The precise mechanisms via which Rac1 is activated by cadherin junctions are not fully known. In keratinocytes Rac1 activation by cadherin junctions requires EGFR signalling, but how EGFR does so is unclear. To address which activator could mediate E-cadherin signalling to Rac1, we investigated EGFR and two Rac1 GEFs, SOS1 and DOCK180. EGFR RNAi prevented junction-induced Rac1 activation and led to fragmented localization of E-cadherin at cadherin contacts. In contrast, depletion of another EGFR family member, ErbB3, did not interfere with either process. DOCK180 RNAi, but not SOS1, prevented E-cadherin-induced Rac1 activation. However, in a strong divergence from EGFR RNAi phenotype, DOCK180 depletion did not perturb actin recruitment or cadherin localisation at junctions. Rather, reduced DOCK180 levels impaired the resistance to mechanical stress of pre-formed cell aggregates. Thus, within the same cell type, EGFR and DOCK180 regulate Rac1 activation by newly-formed contacts, but control separate cellular events that cooperate to stabilise junctions. PMID:25957131

  20. Cooperation of distinct Rac-dependent pathways to stabilise E-cadherin adhesion

    PubMed Central

    Erasmus, Jennifer C.; Welsh, Natalie J.; Braga, Vania M.M.

    2015-01-01

    The precise mechanisms via which Rac1 is activated by cadherin junctions are not fully known. In keratinocytes Rac1 activation by cadherin junctions requires EGFR signalling, but how EGFR does so is unclear. To address which activator could mediate E-cadherin signalling to Rac1, we investigated EGFR and two Rac1 GEFs, SOS1 and DOCK180. EGFR RNAi prevented junction-induced Rac1 activation and led to fragmented localization of E-cadherin at cadherin contacts. In contrast, depletion of another EGFR family member, ErbB3, did not interfere with either process. DOCK180 RNAi, but not SOS1, prevented E-cadherin-induced Rac1 activation. However, in a strong divergence from EGFR RNAi phenotype, DOCK180 depletion did not perturb actin recruitment or cadherin localisation at junctions. Rather, reduced DOCK180 levels impaired the resistance to mechanical stress of pre-formed cell aggregates. Thus, within the same cell type, EGFR and DOCK180 regulate Rac1 activation by newly-formed contacts, but control separate cellular events that cooperate to stabilise junctions. PMID:25957131

  1. Contact stress at the post-cam mechanism in posterior-stabilised total knee arthroplasty.

    PubMed

    Nakayama, K; Matsuda, S; Miura, H; Iwamoto, Y; Higaki, H; Otsuka, K

    2005-04-01

    We measured the contact areas and contact stresses at the post-cam mechanism of a posterior-stabilised total knee arthroplasty when a posterior force of 500 N was applied to the Kirschner Performance, Scorpio Superflex, NexGen LPS Flex Fixed, and NexGen LPS Flex Mobile knee systems. Measurements were made at 90 degrees, 120 degrees, and 150 degrees of flexion both in neutral rotation and 10 degrees of internal rotation of the tibial component. Peak contact stresses at 90 degrees, 120 degrees, and 150 degrees were 24.0, 33.9, and 28.8 MPa, respectively, for the Kirschner; 26.0, 32.4, and 22.1 MPa, respectively, for the Scorpio; and 34.1, 31.5, and 32.5 MPa, respectively, for the NexGen LPS Flex Fixed. With an internally rotated tibia, the contact stress increased significantly with all the fixed-bearing arthroplasties but not with the NexGen LPS Flex Mobile arthroplasty. The post-cam design should be modified in order to provide a larger contact area whilst avoiding any impingement and edge loading. PMID:15795197

  2. Shape stabilised phase change materials (SSPCMs): High density polyethylene and hydrocarbon waxes

    SciTech Connect

    Mu, Mulan E-mail: m.basheer@qub.ac.uk; Basheer, P. A. M. E-mail: m.basheer@qub.ac.uk; Bai, Yun; McNally, Tony

    2014-05-15

    Shape stabilised phase change materials (SSPCMs) based on high density polyethylene (HDPE) with high (HPW, T{sub m}=56-58 °C) and low (L-PW, T{sub m}=18-23 °C) melting point waxes were prepared by melt-mixing in a twin-screw extruder and their potential in latent heat thermal energy storage (LHTES) applications for housing assessed. The structure and morphology of these blends were investigated by scanning electron microscopy (SEM). Both H-PW and L-PW were uniformly distributed throughout the HDPE matrix. The melting point and latent heat of the SSPCMs were determined by differential scanning calorimetry (DSC). The results demonstrated that both H-PW and L-PW have a plasticisation effect on the HDPE matrix. The tensile and flexural properties of the samples were measured at room temperature (RT, 20±2 °C) and 70 °C, respectively. All mechanical properties of HDPE/H-PW and HDPE/L-PW blends decreased from RT to 70 °C. In all instances at RT, modulus and stress, irrespective of the mode of deformation was greater for the HDPE/H-PW blends. However, at 70 °C, there was no significant difference in mechanical properties between the HDPE/H-PW and HDPE/L-PW blends.

  3. Highly water-soluble mast cell stabiliser-encapsulated solid lipid nanoparticles with enhanced oral bioavailability.

    PubMed

    Patel, Ravi R; Chaurasia, Sundeep; Khan, Gayasuddin; Chaubey, Pramila; Kumar, Nagendra; Mishra, Brahmeshwar

    2016-05-01

    Cromolyn sodium (CS), a mast cell stabiliser, is widely employed for the prevention and treatment of allergic conditions. However, high hydrophilicity and poor oral permeability hinder its oral clinical translation. Here, solid lipid nanoparticles (SLNs) have been developed for the purpose of oral bioavailability enhancement. The CS-SLNs were engineered by double emulsification method (W1/O/W2) and optimised by using Box-Behnken experimental design. The surface and solid-state characterisations revealed the presence of CS in an amorphous form without any interactions inside the spherical-shaped SLNs. The in-vitro release study showed an extended release up to 24 hr by diffusion controlled process. Ex-vivo and in-vivo intestinal permeation study showed ∼2.96-fold increase in permeability of CS by presentation as SLNs (p < 0.05). Further, in-vivo pharmacokinetic study exhibited ∼2.86-fold enhancements in oral bioavailability of CS by encapsulating inside SLNs, which clearly indicate that SLNs can serve as the potential therapeutic carrier system for oral delivery of CS. PMID:26885889

  4. Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution

    PubMed Central

    2012-01-01

    Silver nanoparticles are extensively used due to their chemical and physical properties and promising applications in areas such as medicine and electronics. Controlled synthesis of silver nanoparticles remains a major challenge due to the difficulty in producing long-term stable particles of the same size and shape in aqueous solution. To address this problem, we examine three strategies to stabilise aqueous solutions of 15 nm citrate-reduced silver nanoparticles using organic polymeric capping, bimetallic core-shell and bimetallic alloying. Our results show that these strategies drastically improve nanoparticle stability by distinct mechanisms. Additionally, we report a new role of polymer functionalisation in preventing further uncontrolled nanoparticle growth. For bimetallic nanoparticles, we attribute the presence of a higher valence metal on the surface of the nanoparticle as one of the key factors for improving their long-term stability. Stable silver-based nanoparticles, free of organic solvents, will have great potential for accelerating further environmental and nanotoxicity studies. PACS: 81.07.-b; 81.16.Be; 82.70.Dd. PMID:22356679

  5. Stabilisation of Na,K-ATPase structure by the cardiotonic steroid ouabain.

    PubMed

    Miles, Andrew J; Fedosova, Natalya U; Hoffmann, Søren V; Wallace, B A; Esmann, Mikael

    2013-05-31

    Cardiotonic steroids such as ouabain bind with high affinity to the membrane-bound cation-transporting P-type Na,K-ATPase, leading to complete inhibition of the enzyme. Using synchrotron radiation circular dichroism spectroscopy we show that the enzyme-ouabain complex is less susceptible to thermal denaturation (unfolding) than the ouabain-free enzyme, and this protection is observed with Na,K-ATPase purified from pig kidney as well as from shark rectal glands. It is also shown that detergent-solubilised preparations of Na,K-ATPase are stabilised by ouabain, which could account for the successful crystallisation of Na,K-ATPase in the ouabain-bound form. The secondary structure is not significantly affected by the binding of ouabain. Ouabain appears however, to induce a reorganization of the tertiary structure towards a more compact protein structure which is less prone to unfolding; recent crystal structures of the two enzymes are consistent with this interpretation. These circular dichroism spectroscopic studies in solution therefore provide complementary information to that provided by crystallography. PMID:23618866

  6. Control of Sty1 MAPK activity through stabilisation of the Pyp2 MAPK phosphatase.

    PubMed

    Kowalczyk, Katarzyna M; Hartmuth, Sonya; Perera, David; Stansfield, Peter; Petersen, Janni

    2013-08-01

    In all eukaryotes tight control of mitogen-activated protein kinase (MAPK) activity plays an important role in modulating intracellular signalling in response to changing environments. The fission yeast MAPK Sty1 (also known as Spc1 or Phh1) is highly activated in response to a variety of external stresses. To avoid segregation of damaged organelles or chromosomes, strong Sty1 activation transiently blocks mitosis and cell division until such stresses have been dealt with. MAPK phosphatases dephosphorylate Sty1 to reduce kinase activity. Therefore, tight control of MAPK phosphatases is central for stress adaptation and for cell division to resume. In contrast to Pyp1, the fission yeast Pyp2 MAPK phosphatase is under environmental control. Pyp2 has a unique sequence (the linker region) between the catalytic domain and the N-terminal MAPK-binding site. Here we show that the Pyp2 linker region is a destabilisation domain. Furthermore, the linker region is highly phosphorylated to increase Pyp2 protein stability and this phosphorylation is Sty1 dependent. Our data suggests that Sty1 activation promotes Pyp2 phosphorylation to increase the stability of the phosphatase. This MAPK-dependent Pyp2 stabilisation allows cells to attenuate MAPK signalling and resume cell division, once stresses have been dealt with. PMID:23690545

  7. Delay-dependent resilient-robust stabilisation of uncertain networked control systems with variable sampling intervals

    NASA Astrophysics Data System (ADS)

    Yang, Feisheng; Zhang, Huaguang; Liu, Zhenwei; Li, Ranran

    2014-03-01

    This work is concerned with the robust resilient control problem for uncertain networked control systems (NCSs) with variable sampling intervals, variant-induced delays and possible data dropouts, which is seldom considered in current literature. It is mainly based on the continuous time-varying-delay system approach. Followed by the nominal case, delay-dependent resilient robust stabilising conditions for the closed-loop NCS against controller gain variations are derived by employing a novel Lyapunov-Krasovskii functional which makes good use of the information of both lower and upper bounds on the varying input delay, and the upper bound on the variable sampling interval as well. A feasible solution of the obtained criterion formulated as linear matrix inequalities can be gotten. A tighter bounding technique is presented for acquiring the time derivative of the functional so as to utilise many more useful elements, meanwhile neither slack variable nor correlated augmented item is introduced to reduce overall computational burden. Two examples are given to show the effectiveness of the proposed method.

  8. Linear viscoelastic behaviour of oil-in-water food emulsions stabilised by tuna-protein isolates.

    PubMed

    Ruiz-Márquez, D; Partal, P; Franco, Jm; Gallegos, C

    2013-02-01

    This work deals with the manufacture of oil-in-water food emulsions stabilised by tuna proteins. The influence of protein and oil concentrations on the linear viscoelastic properties and microstructure of these emulsions was analysed. Stable emulsions with suitable linear viscoelastic response and microstructural characteristics were formulated with 70 wt.% oil and, at least, 0.25 wt.% tuna protein. Similarly, emulsions with oil concentrations between 45 and 70 wt.% were prepared using 0.50 wt.% protein. All these emulsions showed a predominantly elastic response in the linear viscoelastic region and a well-developed plateau region in its mechanical spectrum. Rheological and droplet size distribution results pointed out an extensive droplet flocculation, due to interactions among emulsifier molecules located at the oil-water interface of adjacent droplets. As a result, the linear viscoelastic behaviour was controlled by protein-protein interactions, allowing the use of the plateau modulus to successfully normalise both the storage and loss moduli as a function of frequency onto a master curve, irrespective of the selected emulsion formulation. PMID:23239763

  9. Dual effects of β-cyclodextrin-stabilised silver nanoparticles: enhanced biofilm inhibition and reduced cytotoxicity.

    PubMed

    Jaiswal, Swarna; Bhattacharya, Kunal; McHale, Patrick; Duffy, Brendan

    2015-01-01

    The composition and mode of synthesis of nanoparticles (NPs) can affect interaction with bacterial and human cells differently. The present work describes the ability of β-cyclodextrin (β-CD) capped silver nanoparticles (AgNPs) to inhibit biofilm growth and reduce cytotoxicity. Biofilm formation of Staphylococcus epidermidis CSF 41498 was quantified by a crystal violet assay in the presence of native and capped AgNPs (Ag-10CD and Ag-20CD), and the morphology of the biofilm was observed by scanning electron microscope. The cytotoxicity of the AgNPs against HaCat cells was determined by measuring the increase in intracellular reactive oxygen species and change in mitochondrial membrane potential (ΔΨm). Results indicated that capping AgNPs with β-CD improved their efficacy against S. epidermidis CSF 41498, reduced biofilm formation and their cytotoxicity. The study concluded that β-CD is an effective capping and stabilising agent that reduces toxicity of AgNPs against the mammalian cell while enhancing their antibiofilm activity. PMID:25596861

  10. Room-temperature single-electron tunnelling in surfactant stabilised iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Moore, R. G. C.; Evans, S. D.; Shen, T.; Hodson, C. E. C.

    2001-02-01

    Iron oxide nanoparticles have been synthesised by the reduction of FeCl 3·6H 2O and FeCl 2·4H 2O (mass ratio 2:1) in propan-2-ol. The particles were stabilised by the addition of lauric acid and the resultant particles could be readily dispersed in chloroform. Room-temperature single-electron tunnelling through these iron oxide particles has been achieved (to our knowledge) for the first time, using an STM tip-particle-substrate double junction. Characterisation of the particles by XPS and FTIR show that they are Fe 2O 3, or possibly Fe 3O 4 with an outer layer of Fe 2O 3, coated with a carboxylic acid monolayer. The particle diameter given by TEM is of the order of 5.0±0.9 nm. From the Coulomb staircase behaviour observed in the I- V curves, we estimate a nanoparticle capacitance of 6.7×10 -19 F which is in agreement with that expected for particles of this size.

  11. Stabilisation of phytosterols by natural and synthetic antioxidants in high temperature conditions.

    PubMed

    Kmiecik, Dominik; Korczak, Józef; Rudzińska, Magdalena; Gramza-Michałowska, Anna; Hęś, Marzanna; Kobus-Cisowska, Joanna

    2015-04-15

    The aim of the study was to assess the potential applicability of natural antioxidants in the stabilisation of phytosterols. A mixture of β-sitosterol and campesterol was incorporated into triacylglycerols (TAGs). The following antioxidants were added to the prepared matrix: green tea extract, rosemary extract, a mix of tocopherols from rapeseed oil, a mix of synthetic tocopherols, phenolic compounds extracted from rapeseed meal, sinapic acid and butylated hydroxytoluene (BHT). Samples were heated at a temperature of 180 °C for 4 h. After the completion of heating, the losses of phytosterols were analysed, as well as the contents of β-sitosterol and campesterol oxidation products. The total content of phytosterol oxidation products in samples ranged from 96.69 to 268.35 μg/g of oil. The effectiveness of antioxidants decreased in the following order: phenolic compounds from rapeseed meal>rosemary extract>mix of tocopherols from rapeseed oil>mix of synthetic tocopherols>green tea extract>sinapic acid>BHT. PMID:25466113

  12. Geometric adaption of biodegradable magnesium alloy scaffolds to stabilise biological myocardial grafts. Part I.

    PubMed

    Bauer, M; Schilling, T; Weidling, M; Hartung, D; Biskup, Ch; Wriggers, P; Wacker, F; Bach, Fr-W; Haverich, A; Hassel, T

    2014-03-01

    Synthetic patch materials currently in use have major limitations, such as high susceptibility to infections and lack of contractility. Biological grafts are a novel approach to overcome these limitations, but do not always offer sufficient mechanical durability in early stages after implantation. Therefore, a stabilising structure based on resorbable magnesium alloys could support the biological graft until its physiologic remodelling. To prevent early breakage in vivo due to stress of non-determined forming, these scaffolds should be preformed according to the geometry of the targeted myocardial region. Thus, the left ventricular geometry of 28 patients was assessed via standard cardiac magnetic resonance imaging (MRI). The resulting data served as a basis for a finite element simulation (FEM). Calculated stresses and strains of flat and preformed scaffolds were evaluated. Afterwards, the structures were manufactured by abrasive waterjet cutting and preformed according to the MRI data. Finally, the mechanical durability of the preformed and flat structures was compared in an in vitro test rig. The FEM predicted higher durability of the preformed scaffolds, which was proven in the in vitro test. In conclusion, preformed scaffolds provide extended durability and will facilitate more widespread use of regenerative biological grafts for surgical left ventricular reconstruction. PMID:24264726

  13. Three-year performance of in-situ mass stabilised contaminated site soils using MgO-bearing binders.

    PubMed

    Wang, Fei; Jin, Fei; Shen, Zhengtao; Al-Tabbaa, Abir

    2016-11-15

    This paper provides physical and chemical performances of mass stabilised organic and inorganic contaminated site soils using a new group of MgO-bearing binders over 3 years and evaluated the time-dependent performance during the 3 years. This study took place at a contaminated site in Castleford, UK in 2011, where MgO, ground granulated blastfurnace slag (GGBS) and Portland cement (PC) were mixed with the contaminated soils in a dry form using the ALLU mass mixing equipment. Soil cores were retrieved 40-day, 1-year and 3-year after the treatment. The core quality, strength, and the leaching properties were determined via physical observation, unconfined compressive strength (UCS) and batch leaching tests. After 3-year treatment, the UCS values of ALLU mixes were in the range of 50-250kPa; the leachate concentrations of Cd, Pb, Cu and Zn (except Ni) in all mixes were lower than their drinking water standards; and the leachability of total organics was in the range of 10-105mg/L. No apparent degradation of the mass stabilised materials after 3 years' exposure to the field conditions was found. MgO-GGBS blends were found able to provide higher strength and less leachability of contaminants compared to PC and MgO-only mixes in mass stabilised soils. PMID:27427896

  14. Dynamics

    NASA Astrophysics Data System (ADS)

    Ransom, Barbara

    1984-04-01

    Dynamics!” she said, as she buried her head deep in a book on tectonics. “Must be the key to explain what we see the ignorance of which seems to be chronic.”Convection below, then density flow and phase changes are not withstanding; Thermal gradient change and compositional range are things our minds should be commanding.

  15. Immobilisation of heavy metal in cement-based solidification/stabilisation: A review

    SciTech Connect

    Chen, Q.Y. Tyrer, M.; Hills, C.D.; Yang, X.M.; Carey, P.

    2009-01-15

    Heavy metal-bearing waste usually needs solidification/stabilization (s/s) prior to landfill to lower the leaching rate. Cement is the most adaptable binder currently available for the immobilisation of heavy metals. The selection of cements and operating parameters depends upon an understanding of chemistry of the system. This paper discusses interactions of heavy metals and cement phases in the solidification/stabilisation process. It provides a clarification of heavy metal effects on cement hydration. According to the decomposition rate of minerals, heavy metals accelerate the hydration of tricalcium silicate (C{sub 3}S) and Portland cement, although they retard the precipitation of portlandite due to the reduction of pH resulted from hydrolyses of heavy metal ions. The chemical mechanism relevant to the accelerating effect of heavy metals is considered to be H{sup +} attacks on cement phases and the precipitation of calcium heavy metal double hydroxides, which consumes calcium ions and then promotes the decomposition of C{sub 3}S. In this work, molecular models of calcium silicate hydrate gel are presented based on the examination of {sup 29}Si solid-state magic angle spinning/nuclear magnetic resonance (MAS/NMR). This paper also reviews immobilisation mechanisms of heavy metals in hydrated cement matrices, focusing on the sorption, precipitation and chemical incorporation of cement hydration products. It is concluded that further research on the phase development during cement hydration in the presence of heavy metals and thermodynamic modelling is needed to improve effectiveness of cement-based s/s and extend this waste management technique.

  16. Reducing the mobility of arsenic in brownfield soil using stabilised zero-valent iron nanoparticles.

    PubMed

    Gil-Díaz, Mar; Alonso, Juan; Rodríguez-Valdés, Eduardo; Pinilla, Paloma; Lobo, Maria Carmen

    2014-01-01

    The use of nanoscale zero-valent iron (nZVI) as a new tool for the treatment of polluted soils and groundwater has received considerable attention in recent years due to its high reactivity, in situ application and cost-effectiveness. The objectives of this study were to investigate the effectiveness of using a commercial stabilised suspension of nZVI to immobilise As in brownfield soil and to investigate its impact on Fe availability in the treated soil. The phytotoxicities of the soil samples were also evaluated using a germination test with two plant species: barley (Hordeum vulgare L) and common vetch (Vicia sativa L). Two doses of the commercial nZVI suspension were studied, 1% and 10%, and two soil-nanoparticle interaction times, 72 h and 3 mo, were used to compare the stabilities of the soils treated with nZVI. The As availability was evaluated using a sequential extraction procedure and the toxicity characteristics leaching procedure (TCLP) test. The application of nZVI significantly decreased the availability of As in the soil. The immobilisation of As was more effective and more stable over time with the 10% dose than with the 1% dose of the commercial nZVI suspension. The application of nZVI did not induce an important increase in Fe mobility because the Fe leachability was less than 2 mg L(-1) over the time period studied. The lower availability of As in the soil led to a decrease in the phytotoxicity of the soil to barley and vetch germination. Thus, the proposed nanotechnology could be a potential alternative for the in situ remediation of As-polluted soils and could be combined with remediation processes where plants are involved. PMID:25072767

  17. Suitability of constructed wetlands and waste stabilisation ponds in wastewater treatment: nitrogen transformation and removal

    NASA Astrophysics Data System (ADS)

    Senzia, M. A.; Mashauri, D. A.; Mayo, A. W.

    It is estimated that 90% of sewage in cities in developing countries are today discharged untreated into water bodies. In Tanzania, pollution of rivers such as Karanga, Njoro and Rao in Moshi; Mirongo in Mwanza and Themi in Arusha is the cause of frequent disease outbreaks in communities downstreams. Solutions to effluent crisis can be found by its proper treatment and disposal. The principal objective of wastewater treatment is to allow effluents to be disposed without danger to human health or unacceptable damage to the ecology of receiving water bodies. Field investigations were made on pilot scale horizontal subsurface flow constructed wetlands (CW) units located downstream of waste stabilisation ponds (WSP). Six units filled with gravel of 6-25 mm diameters in equal proportion, which gave an initial hydraulic conductivity of 86 m/d were used. While four units covering surface area of 40.7 m 2 each, were located downstream of primary facultative pond, the other two units with surface area 15.9 m 2 each were located downstream of maturation pond. An attempt was made to compare the output of mathematical models for Phragmites and Typha macrophytes located downstream of primary facultative pond. Based on total inflow nitrogen of 1.457 gN/m 2 d, while Phragmites has shown a removal of 54%, Typha had a removal of 44.2%. Furthermore, while the system downstream of primary facultative pond has accretion as a major pathway, accounting for 19.1% of inflow nitrogen, the system downstream of maturation pond has denitrification as its major removal mechanism accounting for 20.5%. In this paper, a comparison of land required by CW and WSP based on the amount of water to be treated is made.

  18. Long-term olfactory memories are stabilised via protein synthesis in Camponotus fellah ants.

    PubMed

    Guerrieri, Fernando J; d'Ettorre, Patrizia; Devaud, Jean-Marc; Giurfa, Martin

    2011-10-01

    Ants exhibit impressive olfactory learning abilities. Operant protocols in which ants freely choose between rewarded and non-rewarded odours have been used to characterise associative olfactory learning and memory. Yet, this approach precludes the use of invasive methods allowing the dissection of molecular bases of learning and memory. An open question is whether the memories formed upon olfactory learning that are retrievable several days after training are indeed based on de novo protein synthesis. Here, we addressed this question in the ant Camponotus fellah using a conditioning protocol in which individually harnessed ants learn an association between odour and reward. When the antennae of an ant are stimulated with sucrose solution, the insect extends its maxilla-labium to absorb the solution (maxilla-labium extension response). We differentially conditioned ants to discriminate between two long-chain hydrocarbons, one paired with sucrose and the other with quinine solution. Differential conditioning leads to the formation of a long-term memory retrievable at least 72 h after training. Long-term memory consolidation was impaired by the ingestion of cycloheximide, a protein synthesis blocker, prior to conditioning. Cycloheximide did not impair acquisition of either short-term memory (10 min) or early and late mid-term memories (1 or 12 h). These results show that, upon olfactory learning, ants form different memories with variable molecular bases. While short- and mid-term memories do not require protein synthesis, long-term memories are stabilised via protein synthesis. Our behavioural protocol opens interesting research avenues to explore the cellular and molecular bases of olfactory learning and memory in ants. PMID:21900478

  19. Ecosystem function in waste stabilisation ponds: Improving water quality through a better understanding of biophysical coupling

    NASA Astrophysics Data System (ADS)

    Ghadouani, Anas; Reichwaldt, Elke S.; Coggins, Liah X.; Ivey, Gregory N.; Ghisalberti, Marco; Zhou, Wenxu; Laurion, Isabelle; Chua, Andrew

    2014-05-01

    Wastewater stabilisation ponds (WSPs) are highly productive systems designed to treat wastewater using only natural biological and chemical processes. Phytoplankton, microbial communities and hydraulics play important roles for ecosystem functionality of these pond systems. Although WSPs have been used for many decades, they are still considered as 'black box' systems as very little is known about the fundamental ecological processes which occur within them. However, a better understanding of how these highly productive ecosystems function is particularly important for hydrological processes, as treated wastewater is commonly discharged into streams, rivers, and oceans, and subject to strict water quality guidelines. WSPs are known to operate at different levels of efficiency, and treatment efficiency of WSPs is dependent on physical (flow characteristics and sludge accumulation and distribution) and biological (microbial and phytoplankton communities) characteristics. Thus, it is important to gain a better understanding of the role and influence of pond hydraulics and vital microbial communities on pond performance and WSP functional stability. The main aim of this study is to investigate the processes leading to differences in treatment performance of WSPs. This study uses a novel and innovative approach to understand these factors by combining flow cytometry and metabolomics to investigate various biochemical characteristics, including the metabolite composition and microbial community within WSPs. The results of these analyses will then be combined with results from the characterisation of pond hydrodynamics and hydraulic performance, which will be performed using advanced hydrodynamic modelling and advanced sludge profiling technology. By understanding how hydrodynamic and biological processes influence each other and ecosystem function and stability in WSPs, we will be able to propose ways to improve the quality of the treatment using natural processes, with

  20. Investigation of host liquid crystal composition on polymer stabilised blue phase properties

    NASA Astrophysics Data System (ADS)

    Mohd Said, Suhana; Rahman, Md Asiqur; Yamana, Itaru; Kimura, Munehiro

    2014-10-01

    Polymer stabilised blue phase liquid crystals (PSBPLCs) have been investigated for photonics and display applications for the following reasons: optical isotropy in the dark state, ease of fabrication due to the omission of the alignment layer, and sub-millisecond response length. Major barriers to the commercialisation of PSBPLCs are: hysteresis, residual birefringence, and most significantly, high driving voltage. We have chosen to lower the driving voltage through optimization of the mixture (host LC, chiral dopant and monomer). In this paper, investigation of the contribution of the host liquid crystal to the phase stability and electro-optic characteristics of the PSBP will be discussed. The following cases have been investigated: a) A three component host liquid crystal (E8, PE-5CNF (4-Cyano-3-fluorophenyl 4-pentyl benzoate) and CPP-3FF (4-(trans-4-n-propyl cyclohexyl)-3',4'-difluoro-1,1'-biphenyl), LCC Corporation, Japan). For a ratio of E8:PE-CNF:CPP-3FF of 5:3:2, a large BPI window of <50.4°C and low hysteresis was achieved, but the driving voltage was 79V, and b) A single host liquid crystal, 8OCB with chiral dopant CB15. For a ratio for 8OCB:CB15 of 1:1, this mixture demonstrated a significantly lower driving voltage of 65V, but exhibited a smaller BPI window of <27°C. Decrease in the ratio of 8OCB:CB15 also induced the presence of a BPII phase in the mixture. A single host liquid crystal has the advantage of simplicity of composition, and lowered driving voltage. However, the hysteresis and blue phase temperature range needs to be optimised. This investigation concludes upon the suggestion of liquid crystal characteristics which optimises the blue phase temperature range, low hysteresis, switching times and driving voltage.

  1. A stabilised nodal spectral element method for fully nonlinear water waves

    NASA Astrophysics Data System (ADS)

    Engsig-Karup, A. P.; Eskilsson, C.; Bigoni, D.

    2016-08-01

    We present an arbitrary-order spectral element method for general-purpose simulation of non-overturning water waves, described by fully nonlinear potential theory. The method can be viewed as a high-order extension of the classical finite element method proposed by Cai et al. (1998) [5], although the numerical implementation differs greatly. Features of the proposed spectral element method include: nodal Lagrange basis functions, a general quadrature-free approach and gradient recovery using global L2 projections. The quartic nonlinear terms present in the Zakharov form of the free surface conditions can cause severe aliasing problems and consequently numerical instability for marginally resolved or very steep waves. We show how the scheme can be stabilised through a combination of over-integration of the Galerkin projections and a mild spectral filtering on a per element basis. This effectively removes any aliasing driven instabilities while retaining the high-order accuracy of the numerical scheme. The additional computational cost of the over-integration is found insignificant compared to the cost of solving the Laplace problem. The model is applied to several benchmark cases in two dimensions. The results confirm the high order accuracy of the model (exponential convergence), and demonstrate the potential for accuracy and speedup. The results of numerical experiments are in excellent agreement with both analytical and experimental results for strongly nonlinear and irregular dispersive wave propagation. The benefit of using a high-order - possibly adapted - spatial discretisation for accurate water wave propagation over long times and distances is particularly attractive for marine hydrodynamics applications.

  2. Physical and hydrodynamic characteristics of a dairy shed waste stabilisation pond system.

    PubMed

    Fyfe, J; Smalley, J; Hagare, D; Sivakumar, M

    2007-01-01

    Waste stabilization pond systems are widely used to treat animal wastes under highly variable hydraulic loading regimes. These systems have received limited research attention with regard to their hydrodynamic behaviour and the potential impact of shock hydraulic loading on their performance. In this study a two-stage dairy shed waste stabilisation pond system was topographically surveyed to determine the physical shape and the theoretical hydraulic retention time (HRT) of each pond, as well as the extent of sludge accumulation in the primary pond. The primary pond was then subjected to a series of drogue tracking runs whereby weighted floating survey targets with submerged 'sails' were tracked during their movement through the pond at times of peak flow in order to characterise the hydrodynamic behaviour of the pond. The full capacity volumes of the primary and secondary ponds were calculated to be 1285 m3 and 2391 m3, respectively. Sludge had been accumulating in the primary pond at a rate of 0.73 m3/d over a period of 2.4 years and this has reduced the active treatment volume of the pond to 657 m3. Based on mean outflow, the HRTs of the ponds were 40 d and 137 d, respectively. The drogue runs revealed a vortex-like mixing pattern within the pond with higher velocities around the perimeter of the pond between the inlet and outlet, and lower velocities in the centre of the pond. In-pond velocities seemed relatively high in comparison with those from other drogue studies of larger ponds and the surging inflow caused the formation of a flow 'jet' that potentially contributed to significant short-circuiting. The range of influence of this flow jet, however, was limited to within 15 m of the inlet, suggesting that short-circuiting would be likely to occur only under certain high inflow conditions. PMID:17591191

  3. Soil stabilisation using AMD sludge, compost and lignite: TCLP leachability and continuous acid leaching.

    PubMed

    Tsang, Daniel C W; Olds, William E; Weber, Paul A; Yip, Alex C K

    2013-11-01

    Utilising locally available industrial by-products for in situ metal stabilisation presents a low-cost remediation approach for contaminated soil. This study explored the potential use of inorganic (acid mine drainage (AMD) sludge and zero-valent iron) and carbonaceous materials (green waste compost, manure compost, and lignite) for minimising the environmental risks of As and Cu at a timber treatment site. After 9-month soil incubation, significant sequestration of As and Cu in soil solution was accomplished by AMD sludge, on which adsorption and co-precipitation could take place. The efficacy of AMD sludge was comparable to that of zero-valent iron. There was marginal benefit of adding carbonaceous materials. However, in a moderately aggressive environment (Toxicity Characteristic Leaching Procedure), AMD sludge only suppressed the leachability of As but not Cu. Therefore, the provision of compost and lignite augmented the simultaneous reduction of Cu leachability, probably via surface complexation with oxygen-containing functional groups. Under continuous acid leaching in column experiments, combined application of AMD sludge with compost proved more effective than AMD sludge with lignite. This was possibly attributed to the larger amount of dissolved organic matter with aromatic moieties from lignite, which may enhance Cu and As mobility. Nevertheless, care should be taken to mitigate ecological impact associated with short-term substantial Ca release and continuous release of Al at a moderate level under acid leaching. This study also articulated the engineering implications and provided recommendations for field deployment, material processing, and assessment framework to ensure an environmentally sound application of reactive materials. PMID:24144464

  4. Calculations of single crystal elastic constants for yttria partially stabilised zirconia from powder diffraction data

    NASA Astrophysics Data System (ADS)

    Lunt, A. J. G.; Xie, M. Y.; Baimpas, N.; Zhang, S. Y.; Kabra, S.; Kelleher, J.; Neo, T. K.; Korsunsky, A. M.

    2014-08-01

    Yttria Stabilised Zirconia (YSZ) is a tough, phase-transforming ceramic that finds use in a wide range of commercial applications from dental prostheses to thermal barrier coatings. Micromechanical modelling of phase transformation can deliver reliable predictions in terms of the influence of temperature and stress. However, models must rely on the accurate knowledge of single crystal elastic stiffness constants. Some techniques for elastic stiffness determination are well-established. The most popular of these involve exploiting frequency shifts and phase velocities of acoustic waves. However, the application of these techniques to YSZ can be problematic due to the micro-twinning observed in larger crystals. Here, we propose an alternative approach based on selective elastic strain sampling (e.g., by diffraction) of grain ensembles sharing certain orientation, and the prediction of the same quantities by polycrystalline modelling, for example, the Reuss or Voigt average. The inverse problem arises consisting of adjusting the single crystal stiffness matrix to match the polycrystal predictions to observations. In the present model-matching study, we sought to determine the single crystal stiffness matrix of tetragonal YSZ using the results of time-of-flight neutron diffraction obtained from an in situ compression experiment and Finite Element modelling of the deformation of polycrystalline tetragonal YSZ. The best match between the model predictions and observations was obtained for the optimized stiffness values of C11 = 451, C33 = 302, C44 = 39, C66 = 82, C12 = 240, and C13 = 50 (units: GPa). Considering the significant amount of scatter in the published literature data, our result appears reasonably consistent.

  5. Calculations of single crystal elastic constants for yttria partially stabilised zirconia from powder diffraction data

    SciTech Connect

    Lunt, A. J. G. Xie, M. Y.; Baimpas, N.; Korsunsky, A. M.; Zhang, S. Y.; Kabra, S.; Kelleher, J.; Neo, T. K.

    2014-08-07

    Yttria Stabilised Zirconia (YSZ) is a tough, phase-transforming ceramic that finds use in a wide range of commercial applications from dental prostheses to thermal barrier coatings. Micromechanical modelling of phase transformation can deliver reliable predictions in terms of the influence of temperature and stress. However, models must rely on the accurate knowledge of single crystal elastic stiffness constants. Some techniques for elastic stiffness determination are well-established. The most popular of these involve exploiting frequency shifts and phase velocities of acoustic waves. However, the application of these techniques to YSZ can be problematic due to the micro-twinning observed in larger crystals. Here, we propose an alternative approach based on selective elastic strain sampling (e.g., by diffraction) of grain ensembles sharing certain orientation, and the prediction of the same quantities by polycrystalline modelling, for example, the Reuss or Voigt average. The inverse problem arises consisting of adjusting the single crystal stiffness matrix to match the polycrystal predictions to observations. In the present model-matching study, we sought to determine the single crystal stiffness matrix of tetragonal YSZ using the results of time-of-flight neutron diffraction obtained from an in situ compression experiment and Finite Element modelling of the deformation of polycrystalline tetragonal YSZ. The best match between the model predictions and observations was obtained for the optimized stiffness values of C11 = 451, C33 = 302, C44 = 39, C66 = 82, C12 = 240, and C13 = 50 (units: GPa). Considering the significant amount of scatter in the published literature data, our result appears reasonably consistent.

  6. Local structure in solid solutions of stabilised zirconia with actinide dioxides (UO{sub 2}, NpO{sub 2})

    SciTech Connect

    Walter, Marcus; Somers, Joseph; Bouexiere, Daniel; Rothe, Joerg

    2011-04-15

    The local structure of (Zr,Lu,U)O{sub 2-x} and (Zr,Y,Np)O{sub 2-x} solid solutions has been investigated by extended X-ray absorption fine structure (EXAFS). Samples were prepared by mixing reactive (Zr,Lu)O{sub 2-x} and (Zr,Y)O{sub 2-x} precursor materials with the actinide oxide powders, respectively. Sintering at 1600 {sup o}C in Ar/H{sub 2} yields a fluorite structure with U(IV) and Np(IV). As typical for stabilised zirconia the metal-oxygen and metal-metal distances are characteristic for the different metal ions. The bond lengths increase with actinide concentration, whereas highest adaptation to the bulk stabilised zirconia structure was observed for U---O and Np---O bonds. The Zr---O bond shows only a slight increase from 2.14 A at 6 mol% actinide to 2.18 A at infinite dilution in UO{sub 2} and NpO{sub 2}. The short interatomic distance between Zr and the surrounding oxygen and metal atoms indicate a low relaxation of Zr with respect to the bulk structure, i.e. a strong Pauling behaviour. -- Graphical abstract: Metal-oxygen bond distances in (Zr,Lu,U)O{sub 2-x} solid solutions with different oxygen vacancy concentrations (Lu/Zr=1 and Lu/Zr=0.5). Display Omitted Research Highlights: {yields} EXAFS indicates high U and Np adaption to the bulk structure of stabilised zirconia. {yields} Zr---O bond length is 2.18 A at infinite Zr dilution in UO{sub 2} and NpO{sub 2}. {yields} Low relaxation (strong Pauling behaviour) of Zr explains its low solubility in UO{sub 2}.

  7. Phase behaviour of a dispersion of charge-stabilised colloidal spheres with added non-adsorbing interacting polymer chains.

    PubMed

    Gögelein, C; Tuinier, R

    2008-10-01

    We present a theory for the phase behaviour of mixtures of charge-stabilised colloidal spheres plus interacting polymer chains in good and theta -solvents within the framework of free-volume theory. We use simple but accurate combination rules for the depletion thickness around a colloidal particle and for the osmotic pressure up to the semi-dilute concentration regime. Hence, we obtain expressions for the free energy for mixtures of charged colloidal particles and non-adsorbing interacting polymers. From that, we calculate the phase behaviour, and discuss its topology in dependence on the competition between the charge-induced repulsion and the polymer-induced attraction. The homogeneous mixture of colloids and polymers becomes more stabilised against demixing when increasing the electrostatic repulsion. This charge-induced stabilisation is strongest for small polymer-to-colloid size ratios and is more pronounced for charged colloids mixed with polymers in a good solvent than for polymers in a theta -solvent. For the weakly charged regime we find that the phase diagram becomes salt-concentration-independent in the protein limit for charged colloids plus polymers in a theta -solvent. The liquid window, i.e., the concentration regimes where a colloidal liquid exists, is narrowed down upon increasing the charge-induced repulsion. Also this effect is more pronounced when charged colloids are mixed with polymer chains in a good solvent. In summary, we demonstrate that the solvent quality significantly influences the phase behaviour of mixtures of charged colloids plus non-adsorbing polymers if the range of the screened electrostatic repulsion becomes of the order of the range of the depletion-induced attraction. PMID:18791755

  8. Production and validation of model iron-tannate dyed textiles for use as historic textile substitutes in stabilisation treatment studies

    PubMed Central

    2012-01-01

    Background For millennia, iron-tannate dyes have been used to colour ceremonial and domestic objects shades of black, grey, or brown. Surviving iron-tannate dyed objects are part of our cultural heritage but their existence is threatened by the dye itself which can accelerate oxidation and acid hydrolysis of the substrate. This causes many iron-tannate dyed textiles to discolour and decrease in tensile strength and flexibility at a faster rate than equivalent undyed textiles. The current lack of suitable stabilisation treatments means that many historic iron-tannate dyed objects are rapidly crumbling to dust with the knowledge and value they hold being lost forever. This paper describes the production, characterisation, and validation of model iron-tannate dyed textiles as substitutes for historic iron-tannate dyed textiles in the development of stabilisation treatments. Spectrophotometry, surface pH, tensile testing, SEM-EDX, and XRF have been used to characterise the model textiles. Results On application to textiles, the model dyes imparted mid to dark blue-grey colouration, an immediate tensile strength loss of the textiles and an increase in surface acidity. The dyes introduced significant quantities of iron into the textiles which was distributed in the exterior and interior of the cotton, abaca, and silk fibres but only in the exterior of the wool fibres. As seen with historic iron-tannate dyed objects, the dyed cotton, abaca, and silk textiles lost tensile strength faster and more significantly than undyed equivalents during accelerated thermal ageing and all of the dyed model textiles, most notably the cotton, discoloured more than the undyed equivalents on ageing. Conclusions The abaca, cotton, and silk model textiles are judged to be suitable for use as substitutes for cultural heritage materials in the testing of stabilisation treatments. PMID:22616934

  9. Stabilisation of crosslinked ultra-high molecular weight polyethylene (UHMW-PE)-acetabular components with alpha-tocopherol.

    PubMed

    Wolf, C; Maninger, J; Lederer, K; Frühwirth-Smounig, H; Gamse, T; Marr, R

    2006-12-01

    A stabilisation of crosslinked ultra-high molecular weight polyethylene (UHMW-PE) with alpha-tocopherol (vitamin E) used for endoprostheses can increase its resistance against oxidative degradation remarkably. However, the method used for conventional UHMW-PE of adding alpha-tocopherol to the UHMW-PE powder before processing can not be applied for crosslinked UHMW-PE, since the alpha-tocopherol hinders the crosslinking process, which would be accompanied by a heavy degradation of this vitamin. The alpha-tocopherol has therefore to be added after the crosslinking process. This paper presents two methods for a stabilisation of finished products with alpha-tocopherol. In method 1, UHMW-PE-cubes (20 x 20 x 20 mm3) were stored in pure alpha-tocopherol under inert atmosphere at temperatures from 100 degrees C to 150 degrees C resulting in a high mass fraction of alpha-tocopherol in the edge zones. For further homogenisation, the cubes were stored in inert atmosphere at temperatures from 160 degrees C to 200 degrees C. In method 2, supercritical CO2 was used to incorporate the vitamin into the UHMW-PE. In an autoclave vessel, the cubes were treated with alpha-tocopherol dissolved in supercritical CO2 for several hours at temperatures from 100 degrees C to 170 degrees C. In both cases, the mass fraction of alpha-tocopherol was detected with the help of a FTIR-microscope. Both methods are well suited to stabilise crosslinked UHMW-PE with alpha-tocopherol. A stabilisation of the sensitive edge layer as well as a nearly homogenous distribution with varying alpha-tocopherol content may be realised by varying the process parameters. Using method 2, standard hip cups were stabilized nearly homogeneously with varying mass fraction of alpha-tocopherol. No oxidation of the UHMW-PE could be detected by infrared spectroscopy (FTIR) and HPLC studies showed a very low degradation of the alpha-tocopherol for both processes. PMID:17143764

  10. Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings.

    PubMed

    Khandelwal, Hitesh; Loonen, Roel C G M; Hensen, Jan L M; Debije, Michael G; Schenning, Albertus P H J

    2015-01-01

    Electrically switchable broadband infrared reflectors that are relatively transparent in the visible region have been fabricated using polymer stabilised cholesteric liquid crystals. The IR reflectors can change their reflection/transmission properties by applying a voltage in response to changes in environmental conditions. Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector. We have also fabricated a switchable IR reflector which can also generate electricity. These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy. PMID:26132328

  11. Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings

    PubMed Central

    Khandelwal, Hitesh; Loonen, Roel C. G. M.; Hensen, Jan L. M.; Debije, Michael G.; Schenning, Albertus P. H. J.

    2015-01-01

    Electrically switchable broadband infrared reflectors that are relatively transparent in the visible region have been fabricated using polymer stabilised cholesteric liquid crystals. The IR reflectors can change their reflection/transmission properties by applying a voltage in response to changes in environmental conditions. Simulations predict that a significant amount of energy can be saved on heating, cooling and lighting of buildings in places such as Madrid by using this switchable IR reflector. We have also fabricated a switchable IR reflector which can also generate electricity. These polymer based switchable IR reflectors are of high potential as windows of automobiles and buildings to control interior temperatures and save energy. PMID:26132328

  12. Ecotoxicity of chemically stabilised metal(loid)s in shooting range soils.

    PubMed

    Sanderson, Peter; Naidu, Ravi; Bolan, Nanthi

    2014-02-01

    Five chemical amendments (soft rock phosphate, lime, commercial phosphate amendment, red mud and magnesium oxide) were applied across four different shooting range soils to chemically stabilise metal(loid)s in the soils. Soils were contaminated with Pb between 2330 and 12,167 mg/kg, Sb from 7.4 to 325 mg/kg and soil pH ranged from 5.43 to 9.29. Amendments were tested for their ability to reduce the bioavailability of Pb, Sb, Zn, Ni, Cu and As in the soils to soil organisms after one year of aging, by measuring a series of ecotoxicological endpoints for earthworms and plants and soil microbial activity. Growth-based endpoints for earthworms and plants were not significantly affected by amendment addition, except in the most contaminated soil. Per cent survival and weight-loss reduction of earthworms was enhanced by amendment addition in only the most contaminated soil. Plant biomass and root elongation was not significantly affected by amendment addition (p=<0.05). Red mud and magnesium oxide appeared toxic to plants and earthworms, probably due to highly alkaline pH (9-12). Lead in soil organisms was relatively low despite the high concentrations of Pb in the soils, suggesting low bioavailability of Pb. Uptake of Pb by earthworms was reduced by between 40 and 96 per cent by amendments, but not across all soils. Amendments reduced Sb in earthworms in Townsville soil by up to 92 per cent. For lettuce the average uptake of Pb was reduced by 40 to 70 per cent with amendment addition in Townsville, Darwin and Perth soil. The effect of amendments on the uptake of Sb, Zn, Ni, Cu and As was variable between soils and amendments. Microbial activity was increased by greater than 50 per cent with amendments addition, with soft rock phosphate and lime being the most effective in Murray Bridge and TV soils and commercial phosphate and MgO being the most effective in Darwin and Perth soils. PMID:24287010

  13. Local curvature measurements of a lean, partially premixed swirl-stabilised flame

    NASA Astrophysics Data System (ADS)

    Bayley, Alan E.; Hardalupas, Yannis; Taylor, Alex M. K. P.

    2012-04-01

    A swirl-stabilised, lean, partially premixed combustor operating at atmospheric conditions has been used to investigate the local curvature distributions in lifted, stable and thermoacoustically oscillating CH4-air partially premixed flames for bulk cold-flow Reynolds numbers of 15,000 and 23,000. Single-shot OH planar laser-induced fluorescence has been used to capture instantaneous images of these three different flame types. Use of binary thresholding to identify the reactant and product regions in the OH planar laser-induced fluorescence images, in order to extract accurate flame-front locations, is shown to be unsatisfactory for the examined flames. The Canny-Deriche edge detection filter has also been examined and is seen to still leave an unacceptable quantity of artificial flame-fronts. A novel approach has been developed for image analysis where a combination of a non-linear diffusion filter, Sobel gradient and threshold-based curve elimination routines have been used to extract traces of the flame-front to obtain local curvature distributions. A visual comparison of the effectiveness of flame-front identification is made between the novel approach, the threshold binarisation filter and the Canny-Deriche filter. The novel approach appears to most accurately identify the flame-fronts. Example histograms of the curvature for six flame conditions and of the total image area are presented and are found to have a broader range of local flame curvatures for increasing bulk Reynolds numbers. Significantly positive values of mean curvature and marginally positive values of skewness of the histogram have been measured for one lifted flame case, but this is generally accounted for by the effect of flame brush curvature. The mean local flame-front curvature reduces with increasing axial distance from the burner exit plane for all flame types. These changes are more pronounced in the lifted flames but are marginal for the thermoacoustically oscillating flames. It is

  14. Cruciate Retaining Versus Cruciate Stabilising Total Knee Arthroplasty – A Prospective Randomised Kinematic Study

    PubMed Central

    Godwin, T L; Bayan, A

    2016-01-01

    Objective: While there is a large body of research in regards to cruciate retaining(CR) and cruciate sacrificing total condylar knee replacement, the literature is spars in regards to highly conforming polyetheylene such as the triatholon cruciate stabilising tibial insert (CS).The aim was to determine whether there is a difference in the range of motion, kinematics as well as the functional outcome for Triathlon CS and CR TKJR. Methods: A single hospital consecutive series of one surgeon between 2011 and 2013 were enrolled. Kinematic data recorded prospectively at the time of surgery utilizing imageless navigation included preoperative and post-replacement extension, gravity flexion, passive flexion and rotation. Intraoperative femoral and tibial cuts and definitive implants were also recorded. Statistically analysis performed to compare CS and CR TKJR range of motion, deformity correction, and rotation pre and post-operatively. Oxford functional scores were obtained at the final follow up. 124 patients were randomised to 71 CS and 53 CR TKJR. The demographics were comparable between the two groups. Results: No significant difference was found between the groups’ preoperative range of motion. The net gain in extension for the CS group was 5.65 degrees (4.14-7.17) and for CR 5.64 degrees (4.24-7.04, p=0.99) with no significant difference shown. Post-operative gravity flexion significantly increased in CS TKJR with 129.01 degrees (127.37130.66) compared with 126.35 degrees (124.39-128.30, p =0.04) for CR. A weak positive correlation was shown between the size of distal femoral cut and post-operative extension for both CS and CR TKJR. A weak positive correlation was also shown for the difference between the intraoperative cuts (tibial and femoral) and the size of the implants used, in relation to post-operative extension. Post-operative oxford scores at average of 3.4 year follow up comparable between groups. Conclusion: The kinematics of CS and CR TKJR are

  15. On the influence of the parameter constraint on the stability of the poles and the discrimination capabilities of the stabilisation diagrams

    NASA Astrophysics Data System (ADS)

    Cauberghe, B.; Guillaume, P.; Verboven, P.; Vanlanduit, S.; Parloo, E.

    2005-09-01

    This paper analyses the influence of the parameter constraint for modal parameter estimation (MPE) methods and its impact on the quality of the stabilisation diagram. It is shown that by a proper choice of the parameter constraint a distinction can be made between physical and mathematical poles based on the sign of the damping. As a result the quality of stabilisation diagrams can be improved. This approach can be applied for several well-known modal parameter estimation methods and the user can benefit from this. Several MPE applications in aerospace, automotive and civil engineering show the implication of the constraint and the specific advantages of obtaining an easy-to-interpret stabilisation diagram.

  16. [Interactions between cyclodextrins and triglycerides: from emulsion stabilisation to the emergence of a new drug delivery system called "beads"].

    PubMed

    Hamoudi, M; Trichard, L; Grossiord, J-L; Chaminade, P; Duchêne, D; Le Bas, G; Fattal, E; Bochot, A

    2009-11-01

    Natural cyclodextrins are cyclic oligosaccharides which can be modified to obtain more water soluble or insoluble derivatives. The main interest of cyclodextrins results from their ability to form an inclusion complex with hydrophobic molecules. Inclusion constitutes a true molecular encapsulation. This property is employed in pharmaceutical industry to facilitate the formulation of poorly water soluble and/or fragile drugs. A more recent application of cyclodextrins consists in their use in the preparation of dispersed systems such as micro- and nanoparticles or even liposomes. When incorporated in dispersed systems, cyclodextrin can enhance drug solubility, drug stability and drug loading. Interestingly, cyclodextrins themselves can also be employed to form or stabilise dispersed systems (material or emulsifying agent). For example, the interactions between cyclodextrins with components of the vegetable oils (more especially with triglycerides) allow to stabilise simple or multiple emulsions but also to form particles called "beads". Very rich in oil, this novel lipid carrier presents an important potential for the encapsulation of highly lipophilic compounds and their delivery by topical and oral routes. These two applications are more particularly developed in the present paper. PMID:19900602

  17. Comparative antibacterial activity of silver nanoparticles synthesised by biological and chemical routes with pluronic F68 as a stabilising agent.

    PubMed

    Santos, Carolina Alves Dos; Seckler, Marcelo Martins; Ingle, Avinash P; Rai, Mahendra

    2016-08-01

    The authors report the comparative antibacterial activity of silver nanoparticles synthesised by biological (using Fusarium oxysporum) and chemical routes in the presence and absence of pluronic F68 as a stabilising agent. The production of silver nanoparticles was evidenced by UV-visible spectra, with absorbance at about 420 nm in the case of both biological and chemical synthesis. X-ray diffraction pattern confirmed the presence of face-centred cubic structure (FCC plane). The nanoparticles characterised by transmission and scanning electron microscopy showed spherical silver nanoparticles with size range of 5-40 and 10-70 nm in the case of biologically and chemically synthesised nanoparticles, respectively. Addition of pluronic F68 showed the stabilisation of silver nanoparticles. Antibacterial efficacy of silver nanoparticles demonstrated different inhibitory activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Overall, biologically synthesised silver nanoparticles showed higher activity as compared with chemically synthesised nanoparticles. Silver nanoparticles synthesised in the presence of pluronic F68 by the chemical route exhibited synergism in antibacterial activity as compared with those synthesised without pluronic F68. On the contrary, biogenic silver nanoparticles without pluronic F68 showed higher antibacterial potential. PMID:27463790

  18. Cr(VI) removal in acidic aqueous solution using iron-bearing industrial solid wastes and their stabilisation with cement.

    PubMed

    Singh, I B; Singh, D R

    2002-01-01

    In this study, iron-bearing industrial solid wastes iron filings, ETP sludge of steel and red mud of aluminium industries; were used for Cr(VI) removal at pH 3. A complete removal of Cr(VI) was found for initial 10 mg 1(-1) of 100 ml solutions in the presence of 2.5 g iron filings, 8 g ETP sludge and 10 g red mud for up to one hour of shaking at room temperature. After Cr(VI) removal, inclusion of chromium on the reacted iron filing surface was demonstrated by EDAX analysis. Leachability of chromium and iron from the reacted wastes was determined by using Toxicity Characteristics Leaching Procedure (TCLP). This test showed a very low level of leachability of chromium as Cr(III) and iron from the reacted wastes. To minimise their leachability further, Cr(VI)-reacted solid wastes were stabilised with Portland cement in their 3:1 ratio. Leachability tests of stabilised wastes by TCLP indicated a considerable decrease in leachability of chromium and iron compared with the that of reacted wastes alone. To explore the possibility of utilisation in building materials, bricks of cement-mixed Cr(VI)-reacted wastes were made and their comprehensive strength, durability and leachability under immersion conditions were measured. PMID:11918404

  19. Physicochemical properties of whey protein, lactoferrin and Tween 20 stabilised nanoemulsions: Effect of temperature, pH and salt.

    PubMed

    Teo, Anges; Goh, Kelvin K T; Wen, Jingyuan; Oey, Indrawati; Ko, Sanghoon; Kwak, Hae-Soo; Lee, Sung Je

    2016-04-15

    Oil-in-water nanoemulsions were prepared by emulsification and solvent evaporation using whey protein isolate (WPI), lactoferrin and Tween 20 as emulsifiers. Protein-stabilised nanoemulsions showed a decrease in particle size with increasing protein concentration from 0.25% to 1% (w/w) level with Z-average diameter between 70 and 90 nm. However, larger droplets were produced by Tween 20 (120-450 nm) especially at concentration above 0.75% (w/w). The stability of nanoemulsions to temperature (30-90°C), pH (2-10) and ionic strength (0-500 mM NaCl or 0-90 mM CaCl2) was also tested. Tween 20 nanoemulsions were unstable to heat treatment at 90°C for 15 min. WPI-stabilised nanoemulsions exhibited droplet aggregation near the isoelectric point at pH 4.5 and 5 and they were also unstable at salt concentration above 30 mM CaCl2. These results indicated that stable nanoemulsions can be prepared by careful selection of emulsifiers. PMID:26616953

  20. Stabilisation of vertical unstable distal clavicular fractures (Neer 2b) using locking T-plates and suture anchors.

    PubMed

    Herrmann, S; Schmidmaier, G; Greiner, S

    2009-03-01

    Distal clavicular fractures are associated with an increased risk of delayed union and non-union, and therefore operative treatment is favoured. Fragment dislocation and instability result from detachment of the coracoclavicular ligaments. Various methods for operative treatment can be found in the literature, but no gold standard has been established. In this retrospective study, we present a new surgical technique using a locking T-plate for osseous stabilisation in combination with vertical stabilisation by suture anchors. Between October 2006 and December 2007, eight people underwent surgery for unstable distal clavicular fracture (Neer type 2b). Subsequently one patient could only be contacted by phone and was excluded from further analysis. Mean follow-up for the remaining seven individuals was 8.3 months. The Constant and DASH scores were evaluated and stress radiographs were performed to check for vertical instability. In all cases bony union was achieved within 6 weeks postoperatively. No intraoperative or early postoperative complications were observed. All but one patient regained excellent shoulder function, the mean Constant and DASH scores were 93.3 and 15.3, respectively. Coracoclavicular distance was successfully restored with a mean 1mm (range 0-2mm) side-to-side difference. Early clinical and radiographic results of this new method are promising, with good to excellent outcome in all cases. PMID:19168176

  1. Unexpected higher stabilisation of two classical antiaromatic frameworks with a ruthenium fragment compared to the osmium counterpart: origin probed by DFT calculations.

    PubMed

    Wu, Jingjing; Hao, Yulei; An, Ke; Zhu, Jun

    2016-01-01

    Density functional theory (DFT) calculations were carried out to investigate the stability and aromaticity of metallapentalocyclobutadienes. The results reveal unexpected higher stabilisation achieved with a 4d ruthenium fragment compared to the 5d [corrected] osmium counterpart. Moreover, direct 1-3 metal-carbon bonding in the metallabutadiene unit of these two complexes is negligible. PMID:26505956

  2. Use of 130Te 2 for frequency referencing and active stabilisation of a violet extended cavity diode laser

    NASA Astrophysics Data System (ADS)

    Burns, I. S.; Hult, J.; Kaminski, C. F.

    2006-04-01

    This paper reports on the use of 130Te 2 absorption lines in active laser-locking, and in frequency referencing, of the emission of a violet extended cavity diode laser with a wavelength of around 410 nm. We note the existence of closely spaced tellurium absorption lines, suitable for referencing purposes in gas sensing applications, at wavelengths below the lower limit (417 nm) of the spectral region covered by the tellurium atlas [J. Cariou, P. Luc, Atlas du spectre d'Absorption de la Molecule de Tellure, CNRS, Paris, 1980]. The absolute positions of the lines in the acquired spectra were estimated by comparison to a simultaneously acquired fluorescence spectrum of atomic indium, and were identified using calculations based on fundamental spectroscopic data. The laser frequency was stabilised within a range of 40 MHz, which is negligible compared to typical transition widths at atmospheric pressure.

  3. Use of (130)Te(2) for frequency referencing and active stabilisation of a violet extended cavity diode laser.

    PubMed

    Burns, I S; Hult, J; Kaminski, C F

    2006-04-01

    This paper reports on the use of (130)Te(2) absorption lines in active laser-locking, and in frequency referencing, of the emission of a violet extended cavity diode laser with a wavelength of around 410 nm. We note the existence of closely spaced tellurium absorption lines, suitable for referencing purposes in gas sensing applications, at wavelengths below the lower limit (417 nm) of the spectral region covered by the tellurium atlas [J. Cariou, P. Luc, Atlas du spectre d'Absorption de la Molecule de Tellure, CNRS, Paris, 1980]. The absolute positions of the lines in the acquired spectra were estimated by comparison to a simultaneously acquired fluorescence spectrum of atomic indium, and were identified using calculations based on fundamental spectroscopic data. The laser frequency was stabilised within a range of 40 MHz, which is negligible compared to typical transition widths at atmospheric pressure. PMID:16503188

  4. Decentralised adaptive output feedback stabilisation for stochastic time-delay systems via LaSalle-Yoshizawa-type theorem

    NASA Astrophysics Data System (ADS)

    Jiao, Ticao; Xu, Shengyuan; Lu, Junwei; Wei, Yunliang; Zou, Yun

    2016-01-01

    This paper deals with the decentralised output feedback stabilisation problem for a class of large-scale stochastic time-delay nonlinear systems. A general theorem is firstly given to guarantee the global existence and uniqueness of the solution for stochastic time-delay systems. In addition, a stochastic version of the well-known LaSalle-Yoshizawa theorem with time-varying delay is initially proposed for the controller design and stability analysis. Then, for a class of large-scale stochastic systems with time-varying delays, totally decentralised adaptive delay-dependent controllers are designed by using K-filter and backstepping approach. Via LaSalle-Yoshizawa-type theorem and constructing a general Lyapunov function, it is shown that all signals in the closed-loop system are bounded almost surely and the solution is almost surely asymptotically stable. Finally, a simulation example is given to illustrate the effectiveness of the results of this paper.

  5. Sewage sludge stabilisation and fertiliser value in a silvopastoral system developed with Eucalyptus nitens Maiden in Lugo (Spain).

    PubMed

    Mosquera-Losada, M R; Ferreiro-Domínguez, N; Daboussi, S; Rigueiro-Rodríguez, A

    2016-10-01

    Copper (Cu) is one of the heavy metals with highest proportion in sewage sludge. In Europe, sewage sludge should be stabilised before using it as a fertiliser in agriculture. Depending on the stabilisation process, sewage sludge has different Cu contents, and soil Cu incorporation rates. This study was undertaken to examine the effect of fertilisation with different types of sewage sludge (anaerobic, composted, and pelletised) on the concentration of total and available Cu in the soil, the tree growth, the pasture production, and the concentration of Cu in the pasture when compared with control treatments (i.e. no fertilisation and mineral fertilisation) in a silvopastoral system under Eucalyptus nitens Maiden. The results of this experiment show that an improvement of the soil pH increased the incorporation and the mineralisation of the sewage sludge and litter, and therefore, the release of Cu from the soil. Moreover, the concentration of Cu in the pasture and the levels of Cu extracted by the pasture improved when the soil organic matter decreased because the high levels of organic matter in the soil could have formed Cu complex. The composted sewage sludge (COM) increased a) the soil variables studied (pH, total Cu, and available Cu) and b) the Cu extracted by the pasture, both probably due to the higher inputs of cations made with it. In any case, the levels of Cu found in the soil never exceeded the maximums as set by Spanish regulations and did not cause harmful effects on the plants and animals. Therefore, the use of COM as an organic fertiliser should be promoted in silvopastoral systems established in edaphoclimatic conditions similar to this study because COM enhanced the productivity of the system from a viewpoint of the soil and the pasture, without causing any environmental damage. PMID:27243933

  6. The G-quadruplex-stabilising agent RHPS4 induces telomeric dysfunction and enhances radiosensitivity in glioblastoma cells.

    PubMed

    Berardinelli, F; Siteni, S; Tanzarella, C; Stevens, M F; Sgura, A; Antoccia, A

    2015-01-01

    G-quadruplex (G4) interacting agents are a class of ligands that can bind to and stabilise secondary structures located in genomic G-rich regions such as telomeres. Stabilisation of G4 leads to telomere architecture disruption with a consequent detrimental effect on cell proliferation, which makes these agents good candidates for chemotherapeutic purposes. RHPS4 is one of the most effective and well-studied G4 ligands with a very high specificity for telomeric G4. In this work, we tested the in vitro efficacy of RHPS4 in astrocytoma cell lines, and we evaluated whether RHPS4 can act as a radiosensitising agent by destabilising telomeres. In the first part of the study, the response to RHPS4 was investigated in four human astrocytoma cell lines (U251MG, U87MG, T67 and T70) and in two normal primary fibroblast strains (AG01522 and MRC5). Cell growth reduction, histone H2AX phosphorylation and telomere-induced dysfunctional foci (TIF) formation were markedly higher in astrocytoma cells than in normal fibroblasts, despite the absence of telomere shortening. In the second part of the study, the combined effect of submicromolar concentrations of RHPS4 and X-rays was assessed in the U251MG glioblastoma radioresistant cell line. Long-term growth curves, cell cycle analysis and cell survival experiments, clearly showed the synergistic effect of the combined treatment. Interestingly the effect was greater in cells bearing a higher number of dysfunctional telomeres. DNA double-strand breaks rejoining after irradiation revealed delayed repair kinetics in cells pre-treated with the drug and a synergistic increase in chromosome-type exchanges and telomeric fusions. These findings provide the first evidence that exposure to RHPS4 radiosensitizes astrocytoma cells, suggesting the potential for future therapeutic applications. PMID:25467559

  7. Comparison of ammonia volatilisation rates in algae and duckweed-based waste stabilisation ponds treating domestic wastewater.

    PubMed

    Zimmo, O R; van der Steen, N P; Gijzen, H J

    2003-11-01

    Quantification of ammonia volatilisation from wastewater stabilisation ponds is important in order to understand its significance for overall nitrogen removal in these widely applied low-cost treatment systems. Ammonia volatilisation rates were measured in pilot plant facilities consisting of one line of four algae-based ponds in series and a parallel line of four ponds with a floating mat of duckweed (Lemna gibba). Ammonia volatilisation was assessed during a period of one and a half years. The method applied is accurate, convenient and is proposed for analysis of a wide range of gasses emitted from stabilisation ponds and possibly other aquatic systems. The ammonia volatilisation rates in algae-based ponds (ABPs) were higher than in duckweed-based ponds (DBPs). This can be explained by the lower values of NH(3) in DBPs due to shading and lower pH values, since the volatilisation rate highly correlated with free ammonia concentration (NH(3)) in pond water. The duckweed cover appeared not to provide a physical barrier for volatilisation of unionised ammonia, because whenever NH(3) concentrations were equal in ABP and DBP also the volatilisation rates were equal. Volatilisation was in the range of 7.2-37.4 mg-Nm(-2)d(-1) and 6.4 -31.5 mg-Nm(-2)d(-1) in the ABPs and DBPs, respectively. Average influent and effluent ammonium nitrogen measurements showed that the ammonia volatilisation during the study period in any system did not exceed 1.5% of total ammonium nitrogen removal. Therefore this study confirmed results from simultaneous experimental work in our laboratory indicating that nitrification/denitrification, rather than ammonia volatilisation, is the most important mechanism for N removal in ABPs and DBPs. PMID:14568043

  8. Design, characterisation, and bioefficiency of insulin-chitosan nanoparticles after stabilisation by freeze-drying or cross-linking.

    PubMed

    Diop, M; Auberval, N; Viciglio, A; Langlois, A; Bietiger, W; Mura, C; Peronet, C; Bekel, A; Julien David, D; Zhao, M; Pinget, M; Jeandidier, N; Vauthier, C; Marchioni, E; Frere, Y; Sigrist, S

    2015-08-01

    Insulin delivery by oral route would be ideal, but has no effect, due to the harsh conditions of the gastrointestinal tract. Protection of insulin using encapsulation in self-assembled particles is a promising approach. However, the lack of stability of this kind of particles in biological environments induces a low bioavailability of encapsulated insulin after oral administration. The objective of this work was to evaluate the effect of two stabilisation strategies alone or combined, freeze-drying and cross-linking, on insulin-loaded chitosan NPs, and to determine their bioefficiency in vitro and in vivo. NPs were prepared by complex coacervation between insulin and chitosan, stabilised either by cross linking with sodium tripolyphosphate solution (TPP), by freeze-drying or both treatments. In vitro bioefficiency NP uptake was evaluated by flow cytometry on epithelial models (Caco-2/RevHT29MTX (mucus secreting cells)). In vivo, NPs were injected via catheter in the peritoneum or duodenum on insulinopenic rats. Freeze-drying increased in size and charge (+15% vs control 412 ± 7 nm; + 36 ± 0.3 mV) in comparison with cross linking which decreased NP size (-25%) without impacting the NP charge. When combined the consecutive treatments reduced NPs size and increased charges as compared to standard level. Freeze drying is necessary to prevent the destruction of NP in intestinal environment in comparison with no freeze dryed one where 60% of NP were destroyed after 2h. Additionally freeze drying combined with cross linking treatments improved bioefficiency of NP with uptake in cell increased when mucus is present. Combination of both treatment showed a protection of insulin in vivo, with a reduction of glycemia when NPs were administrated. This work showed that the combination of freeze drying and cross linking treatment is necessary to stabilize (freeze-drying) and increase bioefficiency (cross-linking) of self assembled NP in the delivery of insulin in vitro and in

  9. Efficacy of stabilisation splint therapy combined with non-splint multimodal therapy for treating RDC/TMD axis I patients: a randomised controlled trial.

    PubMed

    Nagata, K; Maruyama, H; Mizuhashi, R; Morita, S; Hori, S; Yokoe, T; Sugawara, Y

    2015-12-01

    Stabilisation splint therapy has long been thought to be effective for the management of temporomandibular disorders (TMD). However, the superiority of stabilisation splint therapy compared to other TMD treatments remains controversial. The aim of this study was to determine the efficacy of stabilisation splint therapy combined with non-splint multimodal therapy for TMD. A total of 181 TMD participants were randomly allocated to a non-splint multimodal therapy (NS) group (n = 85) or a non-splint multimodal therapy plus stabilisation splint (NS+S) group (n = 96). Non-splint multimodal therapy included self-exercise of the jaw, cognitive-behavioural therapy, self-management education and additional jaw manipulation. Three outcome measurements were used to assess treatment efficacy: mouth-opening limitation, oro-facial pain and temporomandibular joint sounds. A two-factor repeated-measures analysis of variance (anova) was used to evaluate the efficacy of the two treatment modalities (NS vs. NS+S), and Scheffe's multiple comparison test was used to compare the treatment periods. Subgroup analyses were performed to disclose the splint effects for each TMD diagnostic group. All three parameters significantly decreased over time in both groups. However, there were no significant differences between the two treatment groups in the total comparison or subgroup analyses; an exception was the group with degenerative joint disease. No significant difference between the NS and NS+S treatment approaches was revealed in this study. Therefore, we conclude that the additional effects of stabilisation splint are not supported for patients with TMD during the application of multimodal therapy. PMID:26174571

  10. Dykes and structures of the NE rift of Tenerife, Canary Islands: a record of stabilisation and destabilisation of ocean island rift zones

    NASA Astrophysics Data System (ADS)

    Delcamp, A.; Troll, V. R.; van Wyk de Vries, B.; Carracedo, J. C.; Petronis, M. S.; Pérez-Torrado, F. J.; Deegan, F. M.

    2012-07-01

    Many oceanic island rift zones are associated with lateral sector collapses, and several models have been proposed to explain this link. The North-East Rift Zone (NERZ) of Tenerife Island, Spain offers an opportunity to explore this relationship, as three successive collapses are located on both sides of the rift. We have carried out a systematic and detailed mapping campaign on the rift zone, including analysis of about 400 dykes. We recorded dyke morphology, thickness, composition, internal textural features and orientation to provide a catalogue of the characteristics of rift zone dykes. Dykes were intruded along the rift, but also radiate from several nodes along the rift and form en échelon sets along the walls of collapse scars. A striking characteristic of the dykes along the collapse scars is that they dip away from rift or embayment axes and are oblique to the collapse walls. This dyke pattern is consistent with the lateral spreading of the sectors long before the collapse events. The slump sides would create the necessary strike-slip movement to promote en échelon dyke patterns. The spreading flank would probably involve a basal decollement. Lateral flank spreading could have been generated by the intense intrusive activity along the rift but sectorial spreading in turn focused intrusive activity and allowed the development of deep intra-volcanic intrusive complexes. With continued magma supply, spreading caused temporary stabilisation of the rift by reducing slopes and relaxing stress. However, as magmatic intrusion persisted, a critical point was reached, beyond which further intrusion led to large-scale flank failure and sector collapse. During the early stages of growth, the rift could have been influenced by regional stress/strain fields and by pre-existing oceanic structures, but its later and mature development probably depended largely on the local volcanic and magmatic stress/strain fields that are effectively controlled by the rift zone growth